U.S. patent application number 15/566907 was filed with the patent office on 2018-03-29 for method and device for transmitting or receiving scheduling request in mobile communication system.
The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Jaehyuk JANG, Sangbum KIM, Soenghun KIM.
Application Number | 20180092118 15/566907 |
Document ID | / |
Family ID | 57320487 |
Filed Date | 2018-03-29 |
United States Patent
Application |
20180092118 |
Kind Code |
A1 |
KIM; Soenghun ; et
al. |
March 29, 2018 |
METHOD AND DEVICE FOR TRANSMITTING OR RECEIVING SCHEDULING REQUEST
IN MOBILE COMMUNICATION SYSTEM
Abstract
The present disclosure relates to a communication method and
system for converging a 5th-Generation (5G) communication system
for supporting higher data rates beyond a 4th-Generation (4G)
system with a technology for Internet of Things (IoT). The present
disclosure may be applied to intelligent services based on the 5G
communication technology and the IoT-related technology, such as
smart home, smart building, smart city, smart car, connected car,
health care, digital education, smart retail, security and safety
services. The present invention provides a method for transmitting
a scheduling request (SR) in a wireless communication system. A SR
transmission method for a terminal according to the present
invention includes, receiving first information and second
information for SR configuration, transmitting the SR if a SR timer
based on the first information and the second information is
expired, and wherein the first information comprises SR
configuration information for a primary cell and a secondary cell,
and wherein the second information is an integer value for
configuring the SR timer.
Inventors: |
KIM; Soenghun; (Suwon-si,
KR) ; KIM; Sangbum; (Suwon-si, KR) ; JANG;
Jaehyuk; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si, Gyeonggi-do |
|
KR |
|
|
Family ID: |
57320487 |
Appl. No.: |
15/566907 |
Filed: |
May 13, 2016 |
PCT Filed: |
May 13, 2016 |
PCT NO: |
PCT/KR2016/005121 |
371 Date: |
October 16, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62162468 |
May 15, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 28/0278 20130101;
H04W 4/70 20180201; H04W 74/006 20130101; H04W 72/0406 20130101;
H04W 72/1278 20130101; H04W 72/1205 20130101; H04W 56/0005
20130101 |
International
Class: |
H04W 72/12 20060101
H04W072/12; H04W 28/02 20060101 H04W028/02 |
Claims
1. A method of transmitting a scheduling request (SR) in a wireless
communication system, the method comprising: receiving first
information and second information for SR configuration; and
transmitting the SR if a SR timer based on the first information
and the second information is expired, and wherein the first
information comprises SR configuration information for a primary
cell and a secondary cell, and wherein the second information is an
integer value for configuring the SR timer.
2. The method of claim 1, wherein the first information comprises
periodicity information of an SR on the primary cell and an SR the
secondary cell.
3. The method of claim 2, wherein a value of SR timer is configured
based on the second information and a shorter period between a
period of the SR on the primary cell and a period of the SR on the
secondary cell.
4. The method of claim 3, further comprising: transmitting a buffer
status report (BSR) on an allocated resource for a transmission of
the BSR.
5. A method of receiving a scheduling request (SR) in a wireless
communication system, the method comprising: transmitting first
information and second information for SR configuration; and
receiving the SR if a SR timer based on the first information and
the second information is expired, and wherein the first
information comprises SR configuration information for a primary
cell and a secondary cell, and wherein the second information is an
integer value for configuring the SR timer.
6. The method of claim 5, wherein the first information comprises
periodicity information of an SR on the primary cell and an SR the
secondary cell.
7. The method of claim 6, wherein a value of SR timer is configured
based on the second information and a shorter period between a
period of the SR on the primary cell and a period of the SR on the
secondary cell.
8. The method of claim 7, further comprising: allocating a resource
for transmitting a buffer status report (BSR); and receiving the
BSR on the resource.
9. A terminal of transmitting a scheduling request (SR) in a
wireless communication system, the terminal comprising: a
transceiver to transmit and receive signals to and from a base
station; and a controller configured to control to receive first
information and second information for SR configuration, and
transmit the SR if a SR timer based on the first information and
the second information is expired, and wherein the first
information comprises SR configuration information for a primary
cell and a secondary cell, and wherein the second information is an
integer value for configuring the SR timer.
10. The terminal of claim 9, wherein the first information
comprises periodicity information of an SR on the primary cell and
an SR the secondary cell.
11. The terminal of claim 10, wherein a value of SR timer is
configured based on the second information and a shorter period
between a period of the SR on the primary cell and a period of the
SR on the secondary cell.
12. The terminal of claim 11, wherein the controller is further
configured to transmit a buffer status report (BSR) on an allocated
resource for a transmission of the BSR.
13. A base station of receiving a scheduling request (SR) in a
wireless communication system, the base station comprising: a
transceiver to transmit and receive signals to and from a terminal;
and a controller configured to control to transmit first
information and second information for SR configuration, and
receive the SR if a SR timer based on the first information and the
second information is expired, and wherein the first information
comprises SR configuration information for a primary cell and a
secondary cell, and wherein the second information is an integer
value for configuring the SR timer.
14. The base station of claim 13, wherein the first information
comprises periodicity information of an SR on the primary cell and
an SR the secondary cell.
15. The base station of claim 14, wherein a value of SR timer is
configured based on the second information and a shorter period
between a period of the SR on the primary cell and a period of the
SR on the secondary cell.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method and an apparatus
for transmitting a scheduling request in a mobile communication
system, and more particularly, to a method and an apparatus for
configuring and transmitting a scheduling request in a secondary
cell.
BACKGROUND ART
[0002] To meet a demand for radio data traffic that is on an
increasing trend after commercialization of a 4G communication
system, efforts to develop an improved 5G communication system or a
pre-5G communication system have been conducted. For this reason,
the 5G communication system or the pre-5G communication system is
called a communication system beyond 4G network or a system since
the post LTE. To achieve a high data transmission rate, the 5G
communication system is considered to be implemented in a super
high frequency (mmWave) band (for example, like 60 GHz band). To
reduce a path loss of a radio wave and increase a transfer distance
of the radio wave in the super high frequency band, in the 5G
communication system, technologies of beam-forming, a massive MIMO,
a full dimensional MIMO FD-MIMO, an array antenna, analog
beam-forming, and a large scale antenna have been discussed.
Further, to improve the network of the system, in the 5G
communication system, technologies of an improved small cell, an
advanced small cell, a cloud radio access network (cloud RAN), an
ultra-dense network, device-to-device communication (D2D), wireless
backhaul, a moving network, cooperative communication, coordinated
multi-points (CoMP), interference cancellation, or the like have
been developed. In addition to this, in the 5G system, hybrid FSK
and QAM modulation (FQAM) and sliding window superposition coding
(SWSC) which are an advanced coding modulation (ACM) scheme and a
filter bank multi carrier (FBMC), a non orthogonal multiple access
(NOMA), and a sparse code multiple access (SCMA) which are an
advanced access technology, or the like have been developed.
[0003] Meanwhile, the Internet is evolved to an Internet of Things
(IoT) network that transmits and receives information, such as
things, between distributed components and processes the
information, in a human-centered connection network through which
human generates and consumes information. The Internet of
Everything (IoE) technology in which the big data processing
technology, etc., by connection with a cloud server, etc., is
combined with the IoT technology has also emerged. To implement the
IoT, technology elements, such as a sensing technology, wired and
wireless communication and network infrastructure, a service
interface technology, and a security technology, have been
required. Recently, technologies such as a sensor network, machine
to machine (M2M), and machine type communication (MTC) for
connecting between things has been researched. In the IoT
environment, an intelligent Internet technology (IT) service that
creates a new value in human life by collecting and analyzing data
generated in the connected things may be provided. The IoT may be
applied to fields, such as a smart home, a smart building, a smart
city, a smart car or a connected car, a smart grid, a health care,
smart appliances, and advanced healthcare service by fusing and
combining the existing information technology (IT) with various
industries.
[0004] Therefore, various tries to apply the 5G communication
system to the IoT network have been conducted. For example, the 5G
communication technologies such as the technologies of the sensor
network, the machine to machine (M2M), the machine type
communication (MTC), or the like are implemented by techniques such
as the beam-forming, the MIMO, the array antenna, or the like. As
the big data processing technology described above, the application
of the cloud radio access network (cloud RAN) may also be an
example of the fusing of the 5G technology with the IoT
technology.
DISCLOSURE OF INVENTION
Technical Problem
[0005] By the way, when uplink control information is transmitted
onto a physical uplink control channel (PUCCH) in a secondary cell
as well as a primary cell, there is a need to configure the
scheduling request onto the secondary cell. Therefore, there is a
need to configure and transmitting the scheduling request
transmitted onto the secondary cell.
Solution to Problem
[0006] To solve the above problem, the present invention relates to
a method for allowing a terminal to transmit a scheduling request
(SR) including: receiving first information and second information
for SR configuration; and when an SR timer based on the first
information and the second information expires, transmitting the
SR, in which the first information includes SR configuration
information for a primary cell and a secondary cell and the second
information is an integer value for configuring the SR timer.
[0007] Further, the present invention relates to a method for
receiving, by a base station, a scheduling request (SR) including:
transmitting first information and second information for SR
configuration; and receiving the SR based on the first information
and the second information, in which the first information includes
SR configuration information for a primary cell and a secondary
cell and the second information is an integer value for configuring
the SR timer.
[0008] In addition, the present invention relates to a terminal for
transmitting a scheduling request (SR) including: a transceiver
transmitting and receiving a signal to and from a base station; and
a controller performing a control to receive first information and
second information for SR configuration and when an SR timer based
on the first information and the second information expires,
transmit the SR, in which the first information includes SR
configuration information for a primary cell and a secondary cell
and the second information is an integer value for configuring the
SR timer.
[0009] Further, the present invention relates to a base station for
receiving a scheduling request (SR) including: a transceiver
transmitting and receiving a signal to and from a terminal; and a
controller performing a control to receive the SR based on the
first information and the second information, in which the first
information includes SR configuration information for a primary
cell and a secondary cell and the second information is an integer
value for configuring the SR timer.
Advantageous Effects of Invention
[0010] According to the method for transmitting a scheduling
request of a terminal in accordance with the embodiment of the
present invention, it is possible to transmit the scheduling
request depending on the SR timer even on the secondary cell.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0012] FIG. 2 is a diagram illustrating a radio protocol structure
in an LTE system to which the present embodiment is applied.
[0013] FIG. 3 is a diagram illustrating carrier aggregation within
an LTE-A base station.
[0014] FIG. 4 is a diagram illustrating dual connectivity between
base stations to which the present embodiment is applied.
[0015] FIG. 5 is a diagram for describing an uplink bearer split
operation of splitting and transmitting uplink data over MeNB and
SeNb in the dual connectivity to which the embodiment of the
present invention is applied.
[0016] FIG. 6 is a diagram illustrating a protocol stack structure
for bearer split to which the embodiment of the present invention
is applied.
[0017] FIG. 7 is a diagram illustrating an operation of a terminal
and a base station according to the present embodiment.
[0018] FIG. 8 is a flow chart illustrating the operation of the
terminal according to the present embodiment.
[0019] FIG. 9 is a diagram illustrating an operation of an MAC
apparatus of the terminal and a PDCP apparatus of the terminal
according to the present embodiment.
[0020] FIG. 10 is a diagram illustrating a method for transmitting,
by the PDCP apparatus of the terminal, a PDCP PDU to a lower layer
according to the present embodiment.
[0021] FIG. 11 is a block configuration diagram of a terminal in a
wireless communication system according to the present
embodiment.
[0022] FIG. 12 is a block configuration diagram of a main base
station in a wireless communication system according to the present
embodiment.
[0023] FIG. 13 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0024] FIG. 14 is a diagram illustrating a radio protocol structure
in an LTE system to which the present embodiment is applied.
[0025] FIG. 15 is a diagram illustrating carrier aggregation within
an LTE-A base station.
[0026] FIG. 16 is a diagram illustrating dual connectivity between
base stations to which the present embodiment is applied.
[0027] FIG. 17 is a diagram illustrating a normal PHR format.
[0028] FIG. 18 is a diagram illustrating an extended PHR
format.
[0029] FIG. 19 is a diagram illustrating a dual connectivity PHR
format.
[0030] FIG. 20 is a diagram illustrating a process of determining
the PHR format which the base station applies according to the
present embodiment.
[0031] FIG. 21 is a flow chart illustrating the operation of the
terminal according to the present embodiment.
[0032] FIG. 22 is a block configuration diagram of a terminal in a
wireless communication system according to the present
embodiment.
[0033] FIG. 23 is a block configuration diagram of a base station
in a wireless communication system according to the present
embodiment.
[0034] FIG. 24 is a diagram illustrating a structure of the LTE
system to which the present invention is applied.
[0035] FIG. 25 is a diagram illustrating a radio protocol structure
in an LTE system to which the present invention is applied.
[0036] FIG. 26 is a diagram illustrating improved carrier
aggregation applied to the terminal.
[0037] FIG. 27 illustrates a format of an MAC header according to
the existing technology.
[0038] FIG. 28 is a diagram illustrating a format in which a newly
added F field is present at the existing reserved bit position.
[0039] FIG. 29 is a diagram illustrating a format in which a new F
field is present, after two bytes.
[0040] FIG. 30 is a diagram illustrating a format in which the
existing F field is extended.
[0041] FIG. 31 is a flow chart illustrating the operation of the
terminal according to the present embodiment.
[0042] FIG. 32 is a flow chart illustrating the operation of the
base station according to the present invention.
[0043] FIG. 33 is an apparatus diagram illustrating the terminal
which may perform the present embodiment.
[0044] FIG. 34 is a block diagram illustrating the configuration of
the base station according to the present embodiment.
[0045] FIG. 35 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0046] FIG. 36 is a diagram illustrating a radio protocol structure
in the LTE system to which the present embodiment is applied.
[0047] FIG. 37 is a diagram illustrating the improved carrier
aggregation in the terminal.
[0048] FIG. 38 is a diagram illustrating a process of activating a
general SCell other than a PSCell in the related art.
[0049] FIG. 39 is a diagram illustrating a process of activating
PSCell in the related art.
[0050] FIG. 40 is a diagram illustrating a process of activating
PUCCH SCell according to the process of activating a general
SCell.
[0051] FIG. 41 is a diagram illustrating a process of activating
PUCCH SCell according to the process of activating a general
SCell.
[0052] FIG. 42 is a flow chart illustrating the operation of the
terminal according to the present embodiment.
[0053] FIG. 43 is a diagram illustrating the terminal apparatus
which may perform the present embodiment.
[0054] FIG. 44 is a diagram illustrating the structure of the LTE
system to which the present embodiment is applied.
[0055] FIG. 45 is a diagram illustrating the radio protocol
structure in an LTE system to which the present invention is
applied.
[0056] FIG. 46 is a diagram illustrating the improved carrier
aggregation in the terminal.
[0057] FIG. 47 is a diagram for describing a process of receiving a
radio resource allocated from the base station by allowing the
terminal to transmit the SR.
[0058] FIG. 48 is a diagram for describing a process of
transmitting SR from a plurality of serving cells having PUCCH.
[0059] FIG. 49 is a flow chart illustrating the operation of the
terminal according to the present embodiment.
[0060] FIG. 50 is a diagram illustrating the terminal apparatus
which may perform the present embodiment.
[0061] FIG. 51 is a diagram illustrating the structure of the LTE
system to which the present invention is applied.
[0062] FIG. 52 is a diagram illustrating the radio protocol
structure in an LTE system to which the present invention is
applied.
[0063] FIG. 53 is a diagram illustrating a message flow between the
terminal and the base station when a method for transmitting an
uplink signal to an unlicensed band according to the present
embodiment is applied.
[0064] FIG. 54 is a diagram illustrating the operation of the
terminal when the method for transmitting an uplink signal to an
unlicensed band according to the present invention is applied.
[0065] FIG. 55 is a diagram illustrating the operation of the
terminal when the method for transmitting a scheduling request
according to the present embodiment is applied.
[0066] FIG. 56 is a block diagram illustrating an internal
structure of the terminal according to the present embodiment.
BEST MODE
First Embodiment
[0067] Generally, a mobile communication system has been developed
to provide communication while securing mobility of a user. The
mobile communication system may provide a voice communication
service and a high-speed data communication service by virtue of
the rapid progress of technologies.
[0068] In recent years, as one of the next-generation mobile
communication systems, standardization for a long term evolution
(LTE) system in 3rd generation partnership project (3GPP) is in
progress. The LTE system is a technology of implementing high-speed
packet based communications having a transmission rate a maximum of
100 Mbps higher than a data transmission rate now being provided
and the standardization for the LTE system is almost complete
currently.
[0069] Recently, discussions about an advanced LTE communication
system (LTE-advanced (LTE-A)) which increases a transmission rate
by combining various new technologies with the LTE communication
system have started in earnest. A representative of the
technologies to be newly introduced may include carrier aggregation
(used together with carrier wave aggregation, carrier wave
collection, etc.). Conventionally, a terminal uses only one forward
carrier and one reverse carrier to transmit and receive data.
Differently from this, however, the carrier aggregation allows one
terminal to use a plurality of forward carriers and a plurality of
reverse carriers to transmit and receive data.
[0070] In the current LTE-A, only intra-ENB carrier aggregation is
defined. This results in reducing applicability of the carrier
aggregation. In particular, in a scenario of overlappingly
operating a plurality of pico cells and one macro cell, a problem
in that a macro cell and a pico cell are not integrated may be
caused.
[0071] To solve the problem, the 3GPP Release 12 has conducted a
study named `Small cell enhancement`. The study is mainly focusing
on the inter-ENB carrier aggregation for integrating serving cells
belonging to another base station to allow one terminal to secure a
high data transmission rate or a dual connectivity technology
between heterogeneous base stations (hereinafter, the inter-ENB
carrier aggregation or the dual connectivity between the
heterogeneous base stations are collectively called dual
connectivity). Further, other fields like mobility support have
been actively discussed, but as the existing carrier aggregation
technology supported only within the base station may be applied
between a macro base station and a pico cell or small cell base
station, the dual connectivity technology is expected to have a big
effect on future communication technologies.
[0072] As the use of data through a smart phone is suddenly
increased in the future, the number of small cells is expected to
be increased exponentially and the small cell base stations which
may independently receive the terminals along with a configuration
of the small cell using the existing remote radio head (RRH) are
expected to take up a big part in a market. According to the dual
connectivity technology, the terminal may receive other kinds of
data from a macro base station as soon as it accesses the small
cell to receive data.
[0073] The present embodiment can improve an uplink maximum
transmission rate of a terminal by transmitting data of one bearer
to two base stations.
[0074] Hereinafter, the present embodiments will be described in
detail with reference to the accompanying drawings. In this case,
it is noted that like reference numerals denote like elements in
the accompanying drawings. Further, detailed descriptions related
to well-known functions or configurations will be ruled out in
order not to unnecessarily obscure the subject matter of the
present invention.
[0075] Further, in describing in detail the present embodiment in
the present specification, the 3GPP will define the standardized
LTE as a major target. However, a main subject of the present
invention may be slightly changed to be applied even to other
communication systems having similar technical backgrounds without
greatly departing the scope of the present invention, which may be
determined by those skilled in the art to which the present
invention pertains.
[0076] Hereinafter, prior to describing the present invention, an
LTE system and carrier aggregation will be briefly described.
[0077] FIG. 1 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0078] FIG. 1 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0079] Referring to FIG. 1, a radio access network of the LTE
system is configured to include next-generation base stations
(evolved node B, hereinafter, ENB, Node B, or base station) 105,
110, 115, and 120, a mobility management entity (MME) 125, and a
serving-gateway (S-GW) 130. User equipment (hereinafter, UE or
terminal) 135 is connected to an external network through the ENBs
105, 110, 115, and 120 and the S-GW 130. In FIG. 1, the ENBs 105,
110, 115, and 120 correspond to the existing node B of a universal
mobile telecommunications system (UMTS). The ENB is connected to
the UE 135 through a radio channel and performs more complicated
role than the existing node B.
[0080] In the LTE system, in addition to a real-time service like a
voice over Internet protocol (VoIP) through the Internet protocol,
all the user traffics are served through a shared channel and
therefore an apparatus for collecting and scheduling status
information such as a buffer status, an available transmission
power status, and a channel state of the UEs is required. Here, the
ENBs 105, 110, 115, and 120 take charge of the collecting and
scheduling. One ENB generally controls a plurality of cells. To
implement a data transmission rate of 100 Mbps, the LTE system
uses, as a radio access technology, orthogonal frequency division
multiplexing (OFDM) in a bandwidth of 20 MHz. Further, an adaptive
modulation and coding (hereinafter, called AMC) determining a
modulation scheme and a channel coding rate depending on the
channel status of the terminal is applied.
[0081] The S-GW 130 is an apparatus for providing a data bearer and
generates or removes the data bearer according to the control of
the MIME 125. The MME is an apparatus for performing a mobility
management function for the terminal and various control functions
and is connected to a plurality of base stations.
[0082] FIG. 2 is a diagram illustrating a radio protocol structure
in the LTE system to which the present embodiment is applied.
[0083] Referring to FIG. 2, the radio protocol of the LTE system
consists of packet data convergence protocols (PDCPs) 205 and 240,
radio link controls (RLCs) 210 and 235, and medium access controls
(MMCs) 215 and 230 in the terminal and the ENB, respectively.
[0084] The PDCPs 205 and 240 take charge of the operation of the IP
header compression/recovery, etc., and the RLCs 210 and 235
reconfigure the PDCP packet data unit (PDU) at an appropriate size
to perform an automatic repeat reQuest (ARQ) operation, or the
like. The MACs 215 and 230 are connected to several RLC layer
apparatuses configured in one terminal and performs an operation of
multiplexing RLC PDUs in an MAC PDU and demultiplexing the RLC
PDUs.
[0085] Physical layers (PHYs) 220 and 225 perform an operation of
channel-coding and modulating upper layer data, making them as an
OFDM symbol, and transmitting them to the radio channel or an
operation of demodulating the OFDM symbol received through the
radio channel, channel-decoding it, and transmitting it to an upper
layer.
[0086] FIG. 3 is a diagram illustrating carrier aggregation within
an LTE-A base station.
[0087] Referring to FIG. 3, one base station generally transmits
and receives multi-carriers over several frequency bands. For
example, when a carrier 315 of which the forward central frequency
is f1 and a carrier 310 of which the forward central frequency is
f3 are transmitted from the base station 305, in the related art,
one terminal transmits and receives data using one of the two
carriers 315 and 310.
[0088] However, the terminal having carrier aggregation ability may
simultaneously transmit and receive data through several carriers.
Therefore, the base station 305 may allocate more carriers to the
terminal 330 having the carrier aggregation ability in some case to
increase a data transmission rate of the terminal 330.
[0089] As described above, aggregating forward carriers and reverse
carriers transmitted and received by one base station is called
intra-ENB carrier aggregation. However, in some cases, unlike one
illustrated in FIG. 3, it may be required to aggregate the forward
carrier transmitted and received by one base station with the
reverse carriers.
[0090] FIG. 4 is a diagram illustrating dual connectivity between
base stations to which the embodiment of the present invention is
applied.
[0091] Referring to FIG. 4, when base station 1 (macro cell base
station or MeNB) 405 transmits and receives a carrier 410 of which
the central frequency is f1 and base station 2 (small cell base
station or SeNB) 415 transmits and receives a carrier 420 of which
the central frequency is f2, if the terminal 430 integrates the
carrier 410 of which the forward central frequency is f1 and the
carrier 420 of which the forward central frequency is f2, one
terminal results in integrating carriers transmitted and received
from at least two base stations. According to the embodiment of the
present invention, the carrier aggregation is called inter-ENB
carrier aggregation or dual connectivity.
[0092] Hereinafter, the terms frequently used in the present
specification will be described.
[0093] As the traditional meaning, when one forward carrier
transmitted from one gas station and one reverse carrier received
by the base station configure one cell, the carrier aggregation may
also be understood that the terminal simultaneously transmits and
receives data through several cells. By doing so, the maximum
transmission rate is increased in response to the integrated number
of carriers.
[0094] Therefore, receiving, by the terminal, data through any
forward carrier or transmitting, from the terminal, the data
through any reverse carrier have the same meaning as transmitting
and receiving the data through a control channel and a data channel
which are provided from a cell a central frequency and a frequency
band characterizing the carriers. Therefore, the carrier
aggregation in the existing LTE 3GPP Release 10 standard has the
same meaning as configuring a plurality of serving cells, in which
the serving cell may be divided into a primary serving cell
(hereinafter, PCell) and a secondary serving cell (hereinafter,
SCell) according to the role of the respective serving cells. The
PCell is a main serving cell taking charging of an access of the
terminal to the network and mobility of the terminal and the SCell
is a serving cell additionally configured at the time of the
carrier aggregation to increase the uplink and downlink
transmission and reception rate of the terminal and is mainly used
to transmit user data.
[0095] In the dual connectivity, a set of the serving cells is
newly defined as follows. The serving cells (PCell, SCell, and the
like for the carrier aggregation) of the macro base station are
divided into a primary cell group (PCG) (or master cell group
(MCG)) and the serving cell (SCell, etc.) of the small cell base
station is divided into a secondary cell group (SCG). The MCG means
a set of the serving cells controlled by the macro base station
(master base station, main base station, or MeNB) controlling the
PCell and the SCG means a set of the serving cells controlled by
the base station (secondary base station, sub-base station, or
SeNB), not by the base station controlling the PCell. The base
station instructs information on whether a predetermined serving
cell belongs to the MCG or the SCG to the terminal while the
corresponding serving cell is configured.
[0096] The main use purpose of the terms is to differentiate what
cell is controlled by the base station controlling a PCell of a
specific terminal and an operation scheme of the corresponding cell
may be different depending on whether the cell is controlled by the
base station (MeNB) controlling the PCell of the specific terminal
and whether the cell is controlled by another base station
(SeNB).
[0097] FIG. 5 is a diagram for describing an uplink bearer split
operation of splitting and transmitting uplink data over MeNB and
SeNb in the dual connectivity to which the embodiment of the
present invention is applied.
[0098] Referring to FIG. 5, terminals 501 and 502 transmits a
serving cell group belonging to an MeNB 500 and SeNBs 503 and 504,
that is, measurement information on the MCG or the SCG to the MeNB
500, such that the MeNB 500 determines whether to configure the
serving cells of the SeNBs 503 and 504 for the dual connectivity in
the terminals 501 and 502. In this case, for the cell included in
the available range among the serving cells of the SCG, the MeNB
500 uses an RRC message to instruct the terminal to perform an
access procedure for the corresponding cell (505).
[0099] In this case, the terminals 501 and 502 may simultaneously
receive at least two bearers from the MeNB 500 and the SeNBs 503
and 504 in the state in which the multiple access for the cell is
maintained. Further, one bearer may be simultaneously received
through the MCG and the SCG to improve the transmission rate. This
is called a downlink bearer split. Further, at least two uplink
bearers may be transmitted by being divided into the SCG and the
MCG as illustrated in FIG. 5. The technology may also be used to
increase the transmission rate of the uplink bearer. In this case,
as illustrated in FIG. 5, the buffer status report for the
corresponding bearer may be separately reported to the MeNB 500 and
the SeNBs 503 and 504 (510).
[0100] FIG. 6 is a diagram illustrating a protocol stack structure
for bearer split to which the embodiment of the present invention
is applied.
[0101] Referring to FIG. 6, the bearer split is split in the PDCP
and a PDCP layer 661 of an MeNB 600 is connected to an RLC layer
660 of the MeNB 600 and an RLC layer 670 of an SeNB 610 and in the
terminal 605, two RLC layers 630 and 640 under an internal PDCP
layer 631 each have a structure corresponding to the MAC layer for
the MCG and the SCG.
[0102] In the MeNB 600, an enhanced packet system (EPS) bearer 650
transmits the PDCP PDU to the RLC layer 660 of the MeNB 600 or the
RLC layer 670 of the SeNB 610 in the PDCP layer (661) and schedules
it. A scheduling method may be variously implemented depending on a
radio link status of the two base stations 600 and 610 for the
terminal 605 or a traffic status of the two base stations 600 and
610. Further, the terminal 605 needs to implement a function of
reordering the PDCP PDUs received from the MeNB 600 and the SeNB
610 in order in the PDCP layer.
[0103] For the PDCP PDU lost depending on a reconfiguration of the
PDCP in the current PDCP layer, a receiving side performs a
procedure of requesting retransmission of the PDU that is not
received through a PDCP status report. However, the PDCP function
for the case in which the PDCP PDUs are not sequentially received
by the bearer split is not defined in a current standard.
Therefore, to sequentially transmit PDCP SDUs to an upper layer for
the PDCP PDUs not sequentially received as described above in the
PDCP layer, a specific buffer is disposed and thus the PDU that is
not received may wait for a predetermined time. Alternatively, to
reduce a time delay, a receiving apparatus may transmit a PDCP
status report and request a retransmission of the corresponding
PDCU PDU from a transmitting side.
[0104] Like the downlink bearer, even in the case of the uplink
bearer in FIG. 6, the PDUs of the EPS bearer 620 are scheduled into
the two RLC layers 630 and 640 in a PDCP layer 631 and the PDUs
transmitted to each of the RLC layers 630 and 640 are transmitted
to the MeNB 600 or the SeNB 610. In this case, a scheduler
implemented in the PDCP layer dynamically splits and transmits the
PDCP PDUs depending on the connection status to each of the base
stations 600 and 610 or an uplink resource allocation status. Here,
one PDCP PDU is not transmitted with being split (segmented) and is
scheduled to two different connections for each PDCP PDU. Next, a
function of approximately splitting the PDU and transmitting the
split PDU to a resource depending on a radio status is performed in
the RLC layers 630 and 640.
[0105] A buffer status report (BSR) is generated when data are
first generated or data having upper priority are generated in such
a manner that the terminal reports the uplink data status to the
base station or is generated by a periodic timer. Based on the BSR,
the base station may know the amount of data accumulated in the
buffer of the terminal, and as a result the uplink radio resource
allocation may be approximately scheduled to the terminal. When the
independent bearer is transmitted to the MeNB or the SeNB in the
dual connectivity, it may be performed depending on the BSR
operation defined in the existing standard but when the bearer
split is generated, the BSR operation is more complicated.
[0106] For example, the amount of buffer data included in the BSR
by the terminal largely points out data included in the buffers of
the RLC and the PDCP. In the case of the RLC, when a portion of the
PDCP PDU segmented to meet the uplink resource to be transmitted to
the lower MAC layer or only a portion of the specific PDCP PDU for
logical channel prioritization (LCP) processing depending on a
priority bit rate (PBR) of the MAC layer is included in the MAC
frame, the rest portions needs to wait in the RLC buffer. Further,
the process associated with the PDCP in the PDCP layer buffer, that
is, RoHC (header compression), and the encrypted PDCP PDU and the
PDCP SDU that is not processed may be present.
[0107] As illustrated in FIG. 6, data of the corresponding bearer
for each cell group may be divided from the RLC layer but in the
case of the PDCP layer, data may be transmitted to the MeNB MAC and
may also be transmitted to the SeNB MAC depending on the
scheduling, and therefore it is inaccurate which one of the two
BSRs the data belong to. Further, the method for processing data is
not defined in the current standard. Therefore, according to the
embodiment of the present invention, a BSR transmission method
depending on the bearer split is proposed.
[0108] Hereinafter, for explanation of description, the uplink
split bearer is called a split bearer. The bearer through which
data are transmitted and received only through the MCG is called an
MCG bearer and the bearer through which data are transmitted and
received through the SCG is called an SCG bearer.
[0109] Unless particularly described, abbreviations/terms used in
the present invention follows one defined standards TS 36.211,
36.213, 36.213, 36.300, 36.321, 36.322, 36.323, and 36.331.
[0110] The biggest problem of the uplink split bearer may cause
overlapping scheduling for the same data since the two base
stations take charge of scheduling.
[0111] To solve the above problem, the present invention
differentiates the buffer status report operation and the uplink
data transmission operation of the buffer based on a predetermined
threshold determined by the base station. Describing in more
detail, the terminal is operated as follows depending on the data
amount of the uplink split bearer (hereinafter, data amount).
TABLE-US-00001 TABLE 1 Data amount < Data amount .gtoreq.
Threshold Threshold BSR To a single eNB To a single ENB for type 1
triggering triggering To both ENBs for type 2 triggering BSR To a
single eNB To both ENBs reporting Data To a single eNB To both ENBs
transmission
[0112] For example, if the data amount is equal to or less than the
threshold, the terminal triggers the BSR only to the predefined
base station and reports the BSR only to the base station. If the
data amount is equal to or more than the threshold, the terminal
triggers type 1 BSR to one base station and triggers type 2 BSR to
both of the two base stations. A padding BSR, a periodic BSR, and a
timer based regular BSR corresponds to type 1 BSR and a new data
based regular BSR corresponds to type 2 BSR. If the data amount is
larger than the threshold, the terminal reports the data to both of
the two base stations and transmits the data to both of the two
base stations. In other words, it may be considered that it is
determined whether to apply the uplink split bearer operation based
on the threshold.
[0113] FIG. 7 illustrates the operation of the terminal and the
base station according to the present embodiment.
[0114] In the mobile communication system configured to include a
terminal 705, a main base station 710, and a sub-base station 715,
the terminal establishes the RRC connection in the cell controlled
by the main base station (720). The main base station may be
understand as the above-mentioned MeNB and the sub-base station may
be understood as the SeNB. Establishing the RRC connection means
transmits a first control message to the base station through the
random access process to set the connection between the base
station and the signaling and after the establishment of the RRC
connection, the terminal may transmit and receive user data to and
from the base station.
[0115] In step 725, the base station generates the RRC control
message establishing the dual connectivity and transmits it to the
terminal. The following information may be received in the RRC
control message. [0116] SCG configuration information [0117] SCG
serving cell configuration information [0118] Carrier frequency
information of SCG serving cell (EUTRA Absolute radio-frequency
channel number, EARFCN) [0119] Physical Cell identity (PCI) of SCG
serving cell [0120] Radio transmission resource related information
of SCG serving cell, or the like [0121] SCG MAC (MAC entity
configured for SCG) configuration information [0122] Buffer status
report configuration information [0123] Periodic report timer
(periodicBSR-Timer) value [0124] BSR retransmission timer
(retxBSR-Timer) value [0125] LCG (Logical Channel Group)
configuration information [0126] Information indicating which LCG
the SCG-bearer and the split bearer belong to [0127] Priority of
SCG-bearer and split bearer The periodic report timer, the BSR
retransmission timer, or the like are configured for each MAC
entity. The periodic report timer, the BSR retransmission timer, or
the like for the MCG MAC may be configured during the RRC
connection establishing process.
[0128] In the step 730, the base station generates the RRC control
message configuring at least one split bearer and transmits it to
the terminal. The following information may be received in the RRC
control message. [0129] Split bearer configuration information
[0130] Identifier of split bearer (bearer id) [0131] PDCP
configuration information of split bearer (PDCP-config) [0132]
Threshold [0133] Cell group in charge when being less than
threshold (hereinafter, cell group in charge, hereinafter, used
together with an exclusive cell group) [0134] MCG RLC configuration
information of split bearer (RLC-config) [0135] SCG RLC
configuration information of split bearer (RLC-config)
[0136] The terminal configures the SCG, the SCG-MAC, and the split
bearer according to the instruction of the RRC control message
received in steps 725 and 730.
[0137] The PDCP configuration information of the split bearer may
include the threshold and the cell group information in charge. The
cell group information in charge is 1 bit information indicating
the MCG or the SCG and when the data amount of the corresponding
split bearer is lower than the threshold, indicates the cell group
taking charge of the uplink transmission of the data of the
bearer.
[0138] The cell group in charge may be replaced by an information
element called the existing ul-DataSplitDRB-ViaSCG. If the
threshold is allocated to the corresponding split bearer or the
corresponding PDCP, the terminal reports the buffer status of the
corresponding split bearer through the cell group instructed by the
ul-DataSplitDRB-ViaSCG when the uplink data amount is equal to or
less than the threshold and reports the buffer status of the
corresponding split bearer using both cell groups including another
cell group and transmits the data of the corresponding split bearer
when the uplink data amount exceeds the threshold. If the threshold
is not allocated to the corresponding split bearer or the
corresponding PDCP, it is understood that an infinite as the
threshold is set and the buffer status of the corresponding split
bearer is always reported and the data of the corresponding split
bearer are transmitted, through the cell group instructed by the
ul-DataSplitDRB-ViaSCG.
[0139] The threshold may also be a value specified in a byte unit
and may also be a buffer status (BS) index.
[0140] The BS index is an integer between 0 and 63 and is used as a
usage indicating the BS of the BSR and is defined by a buffer size
level defined in table 6.1.3.1-1 of standard TS 36.321 or an
extended buffer size level defined in table 6.1.3.1-2.
[0141] Using the BS index as the threshold means that the threshold
is not a single value but is a range and if the amount of
transmittable PDCP data belongs to a range defined by the BS index
specified as the threshold or exceeds a range defined by the BS
index, it is considered that the amount of transmittable PDCP data
is equal to or more than the threshold. Alternatively, if the
amount of transmittable PDCP data is higher than the lowest value
in the range defined by the BS index specified as the threshold, it
is considered that the amount of transmittable PDCP data exceeds
the threshold. For example, when the extended buffer size level 15
(147<BS<=181) is defined as the threshold, it is considered
that the amount of transmittable PDCP data does not exceed the
threshold if the amount of transmittable PDCP data is smaller than
147 bytes and exceeds the threshold if the amount of transmittable
PDCP data exceeds the threshold. Alternatively, when the amount of
transmittable PDCP data is converted into the extended buffer size
level, it is considered that the amount of transmittable PDCP data
exceeds the threshold if the value is equal to or higher than 15
and the amount of transmittable PDCP data does not exceed the
threshold if the value is smaller than 15.
[0142] If it is determined whether the value exceeds the threshold,
the base station determines what table will be used and notifies
the terminal of the determined table. For example, the information
instructing whether to analyze the threshold by using which of a
buffer size table defined in table 6.1.3.1-1 and an extended buffer
size level defined in 6.1.3.1-2 may be included in the control
message configuring the split bearer or the control message
configuring the SCG MAC.
[0143] In step 735, the terminal transmits the data of the split
bearer. In this case, the terminal may report the buffer status of
the split bearer only to the cell group in charge and transmit the
data or report the buffer status of the split bearer to both base
stations using both of both cell groups and transmit the data.
[0144] FIG. 8 is a flow chart illustrating the terminal operation
according to the present embodiment.
[0145] In step 805, the terminal receives the RRC control message
configuring at least one split bearer from the base station. In
step 810, the terminal configures the split bearer depending on the
configuration information. The split bearer is configured to
include an MCG RLC apparatus taking charge of transmitting and
receiving the MCG data to and from one PDCP apparatus and an SCG
RLC apparatus transmitting and receiving to and from one PDCP. In
step 815, the terminal generates the RRC control message notifying
that the split bearer configuration is completed and transmits the
generated RRC control message to the base station.
[0146] In step 820, if the BSR is triggered depending on a
predetermined condition, the terminal proceeds to the step 820 to
check whether the data amount (or data amount of the LCG to which
the split bearer belongs) of the split bearer exceeds the threshold
and if exceeding, the terminal proceeds to step 850 and if not
exceeding, the terminal proceeds to step 825.
[0147] The terminal proceeding to the step 825 checks to what cell
group the BSR is triggered to determine that the BSR transmits the
BSR to a triggered cell group. Hereinafter, triggering that the BSR
is triggered to any cell group may be understood as the same
meaning that the BSR is triggered to MAC entity (in the case of the
MCG, MCG MAC and in the case of the SCG, SCG MAC) or to the
corresponding eNB (in the case of MCG, MeNB and in the case of SCG,
SeNB).
[0148] A method for determining to what cell group BSR is triggered
will be described below.
[0149] Padding BSR: It is determined that if the MAC PDU in which
the padding BSR is received is the MAC PDU transmitted to the MCG,
the BSR is triggered to the MCG and if the MAC PDU in which the BSR
is received is the MAC PDU to the SCG, the BSR is triggered to the
SCG.
[0150] Periodic BSR: if the periodicBSR-Timer of the MCG MAC
expires, the BSR is triggered to the MCG and if the
periodicBSR-Timer of the SCG MAC expires, the BSR is triggered to
the SCG.
[0151] Timer based regular BSR: if the retxBSR-Timer of the MCG MAC
expires, the BSR is triggered to the MCG and if the retxBSR-Timer
of the SCG MAC expires, the BSR is triggered to the SCG.
[0152] New data based regular BSR: It is triggered by new data of
the split bearer, triggered to the MCG if an exclusive cell group
(cell group in charge) is the MCG, and is triggered to the SCG if
the exclusive cell group is the SCG.
[0153] In step 830, the terminal generates the BSR to set the
buffer status (BS: refer to 6.1.3.1 of standard TS 36.321) to be an
appropriate value and then transmits the BSR toward the
corresponding eNB through the corresponding cell group determined
according to the above-mentioned method. In this case, if the BSR
is transmitted through the exclusive cell group, the BS of the LCG
to which the split bearer belongs is summed (or considered) with
the buffer status of the split bearer and if the BSR is not
transmitted through the exclusive cell group, the BS of the LCG to
which the split bearer belongs is not summed with the buffer status
of the split bearer.
[0154] The terminal proceeding to the step 850 checks to what cell
group the BSR is triggered and determines to what cell group the
BSR is transmitted in consideration of the BSR type.
[0155] If the triggered BSR is type 1 BSR, the terminal transmits
the BSR through the triggered cell group and if the triggered BSR
is type 2 BSR, the terminal triggers the BSR to other cell groups
as well as to the cell group to which the BSR is triggered and
performs an operation required to transmit the BSR.
[0156] The padding BSR, the periodic BSR, and the timer based
regular BSR corresponds to the type 1 BSR and the new data based
regular BSR corresponds to the type 2 BSR.
[0157] For example, if the periodic BSR is triggered in an xCG (xCG
may be the MCG or the SCG), even though the amount of transmittable
data of split bearer is larger than the threshold, it is determined
that the BSR is triggered only to the xCG and the terminal
transmits the BSR only to the xCG.
[0158] Alternatively, if the padding BSR is triggered in an xCG,
even though the amount of transmittable data of split bearer is
larger than the threshold, it is determined that the BSR is
triggered only to the xCG and the terminal transmits the BSR only
to the xCG.
[0159] Alternatively, if the timer based regular BSR is triggered
in an xCG, even though the amount of transmittable data of split
bearer is larger than the threshold, it is determined that the BSR
is triggered only to the xCG and the BSR is transmitted only to the
xCG.
[0160] Differently from this, when new PDCP data are generated in
the split bearer and thus the regular BSR is triggered, if the
amount of transmittable data of the split bearer is larger than the
threshold, the terminal is determined that the BSR is triggered to
both of the MCG and the SCG and transmits the BSR through both of
the MCG and the SCG. In this case, the terminal triggers a
scheduling request (SR: refer to chapter 5.4.4 of standard TS
36.321) in the MCG MAC and the SCG MAC. For reference, the BSR and
the padding BSR do not trigger the SR and the regular BSR triggers
the SR.
[0161] In the step 855, the terminal generates the BSR to set the
BS to be an appropriate value and then transmit the BS through the
MCG and SCG. The BS of the LCG to which the split bearer belongs
includes the amount of transmittable PDCP data of the split
bearer.
[0162] FIG. 9 is a diagram illustrating an operation of the MAC
apparatus of the terminal and the PDCP apparatus of the terminal
according to the present embodiment.
[0163] In the present embodiment, the MAC entity determines the
transmittable data of the bearer connected thereto to generate the
BSR. The amount of transmittable data of any bearer is a sum of the
amount of transmittable data stored in the RLC apparatus and the
PDCP apparatus. The amount of transmittable data stored in the PDCP
apparatus of the split bearer may be recognized by both of the MCG
MAC and the SCG MAC.
[0164] The present embodiment proposes a method for determining
whether the PDCP apparatus indicates the amount of transmittable
data to any MAC apparatus according to whether the amount of
transmittable PDCP data exceeds the threshold.
[0165] If events such as generation of new data are generated
periodically or according to a request of the MAC apparatus, the
PDCP apparatus indicates the amount of transmittable data to the
MAC apparatus. In this case, the PDCP apparatus of a non-split
bearer (that is, MCG bearer and/or SCG bearer) and the PDCP
apparatus of the split bearer indicate the amount of transmittable
data to the MAC apparatus by different schemes.
[0166] In step 905, an event to indicate the amount of
transmittable data from the PDCP apparatus to the MAC apparatus is
generated. For example, the event corresponds to the case in which
the MAC apparatus request the event or the event reaches the
predefined indicate timing, the case in which the amount of
transmittable data of the PDCP apparatus is changed, or the
like.
[0167] In step 910, the PDCP apparatus determines whether the
corresponding bearer is the split bearer or the non-split bearer.
Alternatively, it is checked whether the exclusive cell group
information (or information element ul-DataPath which may indicate
the exclusive cell group) is configured in the PDCP apparatus.
[0168] In the case of the split bearer, it proceeds to step 917 and
in the case of the non-split bearer, it proceeds to step 915.
[0169] In the step 915, the terminal indicates the amount of
transmittable PDCP data to the MAC entity.
[0170] The amount of transmittable PDCP data is defined as
follows.
[0171] For the purpose of MAC buffer status reporting, the UE shall
consider PDCP Control PDUs, as well as the following as data
available for transmission in the PDCP layer:
For SDUs for which no PDU has been submitted to lower layers: the
SDU itself, if the SDU has not yet been processed by PDCP, or the
PDU if the SDU has been processed by PDCP. In addition, for radio
bearers that are mapped on RLC AM, if the PDCP entity has
previously performed the re-establishment procedure, the UE shall
also consider the following as data available for transmission in
the PDCP layer: For SDUs for which a corresponding PDU has only
been submitted to lower layers prior to the PDCP re-establishment,
starting from the first SDU for which the delivery of the
corresponding PDUs has not been confirmed by the lower layer,
except the SDUs which are indicated as successfully delivered by
the PDCP status report, if received: the SDU, if it has not yet
been processed by PDCP, or the PDU once it has been processed by
PDCP.
[0172] The terminal considers one not accepted by the lower layer
as the PDCP control PDU and the PDU among the SDU as the
transmittable data within the PDCP layer when the condition that it
is the SDU not processed by the PDCP or the PDU processed by the
PDCP is satisfied.
[0173] Further, when the bearer is mapped to the RLC AM, when the
PDCP performs the reconfiguration process, and when the PDCP status
report among the SDU is received, except for the SDU indicated that
it is successfully transmitted by the PDCP report, the
corresponding PDU at which the transfer of the corresponding PDU
starts from the first SDU not confirmed by the lower layer is
accepted by the lower layer prior to the PDCP reconfiguration, the
terminal considers it as the transmittable data within the PDCP
layer when the condition that it is the SDU not processed by the
PDCP or the PDU processed by the PDCP.
[0174] In step 917, the PDCP apparatus checks whether the threshold
is set and if set, it proceeds to step 920 and if not set, it
proceeds to step 925.
[0175] In step 920, the terminal checks whether the amount of
transmittable PDCP data exceeds the threshold and if exceeding, it
proceeds to step 950 and if not exceeding, it proceeds to step
925.
[0176] In step 925, the terminal instructing that the amount of
transmittable PDCP data only to the MAC entity configured for the
cell group indicated by the exclusive cell group information (or
information element ul-DataPath) and does not indicate the amount
of transmittable PDCP data to another MAC entity. For example, if
the exclusive cell group information (or ul-DataPath) instructs the
SCG, the amount of transmittable data only to the MAC (SCG MAC)
configured for the SCG is indicated.
[0177] In step 950, the terminal indicates the amount of
transmittable PDCP data even to the MAC entity of another cell
group as well as the MAC entity of the cell group instructed by the
exclusive cell group information (or ul-DataPath). For example,
even though the exclusive cell group information (or ul-DataPath)
instructs the SCG, if the amount of transmittable data is equal to
or more than the threshold, the amount of transmittable data is
indicated to both of the SCG MAC and the MCG MAC.
[0178] If the PDCP apparatus is operated as described above, when
new PDCP data are generated in an empty buffer in the MAC entity of
the exclusive cell group, the regular BSR is triggered and if the
PDCP data has priority higher than other transmittable data of the
non-exclusive cell group, when the data amount of PDCP exceeds the
threshold, the regular BSR is triggered in the MAC entity of the
non-exclusive cell group.
[0179] FIG. 10 is a diagram illustrating a method for transmitting,
by a PDCP apparatus of a terminal, a PDCP PDU to a lower layer
according to the present embodiment.
[0180] As illustrated in FIG. 10, The PDCP apparatus transmits the
PDCP PDU to a lower layer according to the request of the lower
layer apparatus. The PDCP apparatus transmits the PDCP PDU to the
lower layer depending on the amount of transmittable PDCP data. In
this case, the PDCP apparatus of the non-split bearer and the PDCP
apparatus of the split bearer transmits the PDCP PDU to the RLC
entity by different schemes.
[0181] In step 1005, an event to transmit the PDCP PDU from the
PDCP apparatus to the lower layer apparatus is generated. For
example, the event corresponds to the case of requesting the
transmission of the data from the lower layer to the PDCP
apparatus, etc.
[0182] In step 1010, the PDCP apparatus determines whether the
corresponding bearer is the split bearer or the non-split bearer.
Alternatively, it is checked whether the exclusive cell group
information (or ul-DataPath) is configured in the PDCP
apparatus.
[0183] In the case of the split bearer, it proceeds to step 1017
and in the case of the non-split bearer, it proceeds to step
1015.
[0184] The RLC apparatus connected to the PDCP apparatus is only
one and therefore PDCP apparatus proceeding to step 1015 transmits
the PDCP PDU to the connected RLC apparatus.
[0185] In step 1017, the PDCP apparatus checks whether the
threshold is set and if set, it proceeds to step 1020 and if not
set, it proceeds to step 1025.
[0186] In step 1020, the PDCP apparatus checks whether the amount
of transmittable PDCP data exceeds the threshold and if exceeding,
it proceeds to step 1050 and if not exceeding, it proceeds to step
1025.
[0187] The amount of transmittable PDCP data is an amount
considered up to the PDCP PDU to be transmitted to the lower layer.
For example, if the threshold is 1000 bytes and the amount of
transmittable PDCP data at the corresponding timing is 1200 bytes,
that is, the size of the PDUCP PDU to be transmitted to the lower
layer is 300 bytes, it may be changed whether the amount of
transmittable PDCP data exceeds the threshold depending on whether
to consider the PDCP PDU to be transmitted to the lower layer. In
this case, even though the PDCP is scheduled to be transmitted to
the lower layer, it compares with the threshold by including the
amount of transmittable PDCP data.
[0188] In step 1025, the PDCP apparatus transmits the PDCP PDU to
RLC entity configured for exclusive CG. Alternatively, if the
ul-DataPath is configured as the SCG, it is transmitted to the RLC
entity configured for the SCG and if not, it is transmitted to the
RLC entity configured for the MCG. Even though the PDCP apparatus
receives a transmission request of the PDCP PDU, the PDCP apparatus
does not transmit the PDCP PDU to RLC entities other than the RLC
entity (or RLC entity configured for CG specified by the
ul-DataPath) configured for the exclusive CG.
[0189] In step 1050, the PDCP apparatus transmits the PDCP PDU to
the RLC entity requesting the transmission of the PDCP PDU without
considering the exclusive CG or the ul-DataPath. As a result, the
PDCP apparatus transmits the PDCP PDU to the RLC entities of an
exclusive CG and a non-exclusive CG.
[0190] FIG. 11 is a block configuration diagram of the terminal in
the wireless communication system according to the present
embodiment.
[0191] Referring to FIG. 11, the terminal includes a radio
frequency (RF) processor 1110, a baseband processor 1120, a storage
unit 1130, and a controller 1140.
[0192] The RF processor 1110 serves to transmit/receive as signal
through a radio channel, such as band conversion and amplification
of a signal. That is the RF processor 1110 up-converts a baseband
signal provided from the baseband processor 1120 into an RF band
signal and then transmits the baseband signal through an antenna
and down-converts the RF band signal received through the antenna
into the baseband signal. For example, the RF processor 1110 may
include a transmitting filter, a receiving filter, an amplifier, a
mixer, an oscillator, a digital to analog converter (DAC), an
analog to digital converter (ADC), or the like. FIG. 11 illustrates
only one antenna but the terminal may include a plurality of
antennas. Further, the RF processor 1110 may include a plurality of
RF chains. Further, the RF processor 1110 may perform beamforming.
For the beamforming, the RF processor 1110 may adjust a phase and a
size of each of the signals transmitted and received through a
plurality of antennas or antenna elements.
[0193] The baseband processor 1120 performs a conversion function
between the baseband signal and the bit string according to a
physical layer standard of the system. For example, when data are
transmitted, the baseband processor 1120 generates complex symbols
by coding and modulating a transmitting bit string. Further, when
data are received, the baseband processor 1120 recovers the
receiving bit string by demodulating and decoding the baseband
signal provided from the RF processor 1110. For example, according
to the orthogonal frequency division multiplexing (OFDM) scheme,
when data are transmitted, the baseband processor 1120 generates
the complex symbols by coding and modulating the transmitting bit
string, maps the complex symbols to sub-carriers, and then performs
an inverse fast Fourier transform (IFFT) operation and a cyclic
prefix (CP) insertion to configure the OFDM symbols. Further, when
data are received, the baseband processor 1120 divides the baseband
signal provided from the RF processor 1110 in an OFDM symbol unit
and recovers the signals mapped to the sub-carriers by a fast
Fourier transform (FFT) operation and then recovers the receiving
bit string by the modulation and decoding.
[0194] The baseband processor 1120 and the RF processor 1110
transmit and receive a signal as described above. Therefore, the
baseband processor 1120 and the RF processor 1110 may be called a
transmitter, a receiver, a transceiver, or a communication unit.
Further, at least one of the baseband processor 1120 and the RF
processor 1110 may include a plurality of communication modules to
support a plurality of different radio access technologies.
Further, at least one of the baseband processor 1120 and the RF
processor 1110 may include different communication modules to
process signals in different frequency bands. For example, the
different radio access technologies may include the wireless LAN
(IEEE 802.11), a cellular network (LTE), or the like. Further, the
different frequency bands may include a super high frequency (SHF)
(2.5 GHz, 5 GHz) band, a millimeter wave (60 GHz) band.
[0195] The storage unit 1130 stores data such as basic programs,
application programs, and configuration information for the
operation of the terminal. In particular, the storage unit 1130 may
store information associated with a second access node performing
wireless communication using a second access technology. Further,
the storage unit 1130 provides the stored data according to the
request of the control unit 1140.
[0196] The controller 1140 controls the general operations of the
terminal. For example, the controller 1140 transmits/receives a
signal through the baseband processor 1120 and the RF processor
1110. Further, the controller 1140 records and reads data in and
from the storage unit 1140. For this purpose, the controller 1140
may include at least one processor. For example, the controller
1140 may include a communication processor (CP) performing a
control for communication and an application processor (AP)
controlling an upper layer such as the application programs.
According to the embodiment of the present invention, the
controller 1140 may control the terminal to perform the operation
and the procedure of the terminal illustrated in FIGS. 7 to 10.
[0197] FIG. 12 is a block configuration diagram of a main base
station in a wireless communication system according to an
exemplary embodiment of the present disclosure.
[0198] As illustrated in FIG. 12, the base station is configured to
include an RF processor 1210, a baseband processor 1220, a backhaul
communication unit 1230, a storage unit 1240, and a controller
1250.
[0199] The RF processor 1210 serves to transmit/receive as signal
through a radio channel, such as band conversion and amplification
of a signal. That is, the RF processor 1210 up-converts a baseband
signal provided from the baseband processor 1220 into an RF band
signal and then transmits the baseband signal through an antenna
and down-converts the RF band signal received through the antenna
into the baseband signal. For example, the RF processor 1210 may
include a transmitting filter, a receiving filter, an amplifier, a
mixer, an oscillator, a DAC, an ADC, etc. FIG. 12 illustrates only
one antenna but the base station may include a plurality of
antennas. Further, the RF processor 1210 may include the plurality
of RF chains. Further, the RF processor 1210 may perform the
beamforming. For the beamforming, the RF processor 1210 may adjust
a phase and a size of each of the signals transmitted and received
through a plurality of antennas or antenna elements.
[0200] The baseband processor 1220 performs a conversion function
between the baseband signal and the bit string according to the
physical layer standard of the system. For example, when data are
transmitted, the baseband processor 1220 generates complex symbols
by coding and modulating a transmitting bit string. Further, when
data are received, the baseband processor 1220 recovers the
receiving bit string by demodulating and decoding the baseband
signal provided from the RF processor 1210. For example, according
to the OFDM scheme, when data are transmitted, the baseband
processor 1220 generates the complex symbols by coding and
modulating the transmitting bit string, maps the complex symbols to
the sub-carriers, and then performs the IFFT operation and the CP
insertion to configure the OFDM symbols. Further, when data are
received, the baseband processor 1220 divides the baseband signal
provided from the RF processor 1210 in the OFDM symbol unit and
recovers the signals mapped to the sub-carriers by the FFT
operation and then recovers the receiving bit string by the
modulation and decoding. The baseband processor 1220 and the RF
processor 1210 transmit and receive a signal as described above.
Therefore, the baseband processor 1220 and the RF processor 1210
may be called a transmitter, a receiver, a transceiver, a
communication unit, or a wireless communication unit.
[0201] The backhaul communicator 1230 provides an interface for
performing communication with other nodes within the network. That
is, the backhaul communication unit 1230 converts bit strings
transmitted from the main base station to other nodes, for example,
an auxiliary base station, a core network, etc., into physical
signals and converts the physical signals received from other nodes
into the bit strings.
[0202] The storage unit 1240 stores data such as basic programs,
application programs, and setting information for the operation of
the main base station. In particular, the storage unit 1240 may
store the information on the bearer allocated to the accessed
terminal, the measured results reported from the accessed terminal,
etc. Further, the storage unit 1240 may store information that is
the determination reference on whether to provide a multi-link to
the terminal or store the multi-link to the terminal. Further, the
storage unit 1240 provides the stored data according to the request
of the control unit 1250.
[0203] The controller 1250 controls the general operations of the
main base station. For example, the controller 1250
transmits/receives a signal through the baseband processor 1220 and
the RF processor 1210 or the backhaul communicator 1230. Further,
the controller 1250 records and reads data in and from the storage
unit 1240. For this purpose, the controller 1250 may include at
least one processor. According to the embodiment of the present
invention, the controller 1250 includes a multi-link controller
1252 that performs a control to provide the multi-link to the
terminal. For example, the controller 1250 may control the main
base station to perform the operation and the procedure of the base
station illustrated in FIGS. 7 to 10.
Second Embodiment
[0204] Generally, a mobile communication system has been developed
to provide communication while securing mobility of a user. The
mobile communication system may provide a voice communication
service and a high-speed data communication service by virtue of
the rapid progress of technologies.
[0205] In recent years, as one of the next-generation mobile
communication systems, standardization for a long term evolution
(LTE) system in 3rd generation partnership project (3GPP) is in
progress. The LTE system is a technology of implementing high-speed
packet based communications having a transmission rate a maximum of
100 Mbps higher than a data transmission rate now being provided
and the standardization for the LTE system is almost complete
currently.
[0206] Recently, discussions about an advanced LTE communication
system (LTE-advanced (LTE-A)) which increases a transmission rate
by combining various new technologies with the LTE communication
system have started in earnest. A representative of the
technologies to be newly introduced may include carrier aggregation
(used together with carrier wave aggregation, carrier wave
collection, etc.). Conventionally, a terminal uses only one forward
carrier and one reverse carrier to transmit and receive data.
Differently from this, however, the carrier aggregation allows one
terminal to use a plurality of forward carriers and a plurality of
reverse carriers to transmit and receive data.
[0207] In the current LTE-A, only intra-ENB carrier aggregation is
defined. This results in reducing applicability of the carrier
aggregation. In particular, in a scenario of overlappingly
operating a plurality of pico cells and one micro cell, a problem
in that a macro cell and a pico cell are not integrated may be
caused. To solve the problem, the 3GPP Release 12 has conducted a
study named `Small cell enhancement`. The study is mainly focusing
on the inter-ENB carrier aggregation for integrating serving cells
belonging to another base station to allow one terminal to secure a
high data transmission rate or a dual connectivity technology
between heterogeneous base stations (hereinafter, the inter-ENB
carrier aggregation or the dual connectivity between the
heterogeneous base stations are collectively called dual
connectivity). Further, other fields like mobility support have
been actively discussed, but as the existing carrier aggregation
technology supported only within the base station may be applied
between a base station and a pico cell or small cell base station,
the dual connectivity technology is expected to have a big effect
on future communication technologies.
[0208] As the use of data through a smart phone is suddenly
increased in the future, the number of small cells is expected to
be increased exponentially and the small cell base stations which
may independently receive the terminals along with a configuration
of the small cell using the existing remote radio head (RRH) are
expected to take up a big part in a market. According to the dual
connectivity technology, the terminal may receive other kinds of
data from a macro base station as soon as it accesses the small
cell to receive data.
[0209] The present embodiment can improve an uplink maximum
transmission rate of a terminal by transmitting data of one bearer
to two base stations.
[0210] Hereinafter, the present embodiments will be described in
detail with reference to the accompanying drawings. In this case,
it is noted that like reference numerals denote like elements in
the accompanying drawings. Further, detailed descriptions related
to well-known functions or configurations will be ruled out in
order not to unnecessarily obscure the subject matter of the
present invention.
[0211] Further, in describing in detail the present embodiment in
the present specification, the 3GPP will define the standardized
LTE as a major target. However, a main subject of the present
invention may be slightly changed to be applied even to other
communication systems having similar technical backgrounds without
greatly departing the scope of the present invention, which may be
determined by those skilled in the art to which the present
invention pertains.
[0212] Hereinafter, prior to describing the present embodiment, an
LTE system and carrier aggregation will be briefly described.
[0213] FIG. 13 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0214] Referring to FIG. 13, a radio access network of the LTE
system includes next-generation base stations (evolved node B,
hereinafter, ENB, Node B, or base station) 1305, 1310, 1315, and
1320, a mobility management entity (MME) 1325, and a
serving-gateway (S-GW) 1330. User equipment (hereinafter, UE or
terminal) 135 is connected to an external network through the ENBs
1305, 1310, 1315, and 1320 and the S-GW 1330. In FIG. 13, the ENBs
1305, 1310, 1315, and 1320 correspond to the existing node B of a
universal mobile telecommunications system (UMTS). The ENB is
connected to the UE 1335 through a radio channel and performs more
complicated role than the existing node B.
[0215] In the LTE system, in addition to a real-time service like a
voice over Internet protocol (VoIP) through the Internet protocol,
all the user traffics are served through a shared channel and
therefore an apparatus for collecting and scheduling status
information such as a buffer status, an available transmission
power status, and a channel status of the UEs is required. Here,
the ENBs 1305, 1310, 1315, and 1320 take charge of the collecting
and scheduling. One ENB generally controls a plurality of cells. To
implement a data transmission rate of 100 Mbps, the LTE system
uses, as a radio access technology, orthogonal frequency division
multiplexing (hereinafter, OFDM) in a bandwidth of 20 MHz. Further,
an adaptive modulation and coding (hereinafter, called AMC)
determining a modulation scheme and a channel coding rate depending
on the channel status of the terminal is applied.
[0216] The S-GW 1330 is an apparatus for providing a data bearer
and generates or removes the data bearer according to the control
of the MME 1325. The MME is an apparatus for performing a mobility
management function for the terminal and various control functions
and is connected to a plurality of base stations.
[0217] FIG. 14 is a diagram illustrating a radio protocol structure
in the LTE system to which the present embodiment is applied.
[0218] Referring to FIG. 14, the radio protocol of the LTE system
consists of packet data convergence protocols (PDCPs) 1405 and
1440, radio link controls (RLCs) 1410 and 1435, and medium access
controls (MACs) 1415 and 1430 in the terminal and the ENB,
respectively.
[0219] The PDCPs 1405 and 1440 take charge of an operation of IP
header compression/recovery, etc., and the RLCs 1410 and 1435
reconfigure a PDCP packet data unit (PDU) at an appropriate size to
perform an automatic repeat reQuest (ARQ) operation, or the like.
The MACs 1415 and 1430 are connected to several RLC layer
apparatuses configured in one terminal and performs an operation of
multiplexing RLC PDUs into an MAC PDU and demultiplexing the RLC
PDUs from the MAC PDU.
[0220] Physical layers (PHYs) 1420 and 1425 perform an operation of
channel-coding and modulating upper layer data, making them as an
OFDM symbol, and transmitting them to the radio channel or an
operation of demodulating the OFDM symbol received through the
radio channel, channel-decoding it, and transmitting it to an upper
layer.
[0221] FIG. 15 is a diagram for describing carrier aggregation
within an LTE-A base station.
[0222] Referring to FIG. 15, one base station generally transmits
and receives multi-carriers over several frequency bands. For
example, when a carrier 1505 of which the forward central frequency
is f1 and a carrier 1510 of which the forward central frequency is
f3 are transmitted from the base station 1505, in the related art,
one terminal transmits and receives data using one of the two
carriers 1515 and 1510.
[0223] However, a terminal having carrier aggregation ability may
simultaneously transmit and receive data through several carriers.
Therefore, the base station 1505 may allocate more carriers to the
terminal 1530 having the carrier aggregation ability in some case
to increase a data transmission rate of the terminal 1530.
[0224] As described above, aggregating forward carriers and reverse
carriers transmitted and received by one base station is called
intra-ENB carrier aggregation. However, in some cases, unlike one
illustrated in FIG. 15, it may be required to aggregate forward
carriers and reverse carriers transmitted and received by different
base stations.
[0225] FIG. 16 is a diagram illustrating dual connectivity between
base stations to which the embodiment of the present invention is
applied.
[0226] Referring to FIG. 16, when base station 1 (macro cell base
station or MeNB) 1605 transmits and receives a carrier 1610 of
which the central frequency is f1 and base station 2 (small cell
base station or SeNB) 1615 transmits and receives a carrier 1620 of
which the central frequency is f2, if the terminal 1630 integrates
a carrier 1610 of which the forward central frequency is f1 and a
carrier 1620 of which the forward central frequency is f2, one
terminal results in integrating carriers transmitted and received
from at least two base stations. According to the embodiment of the
present invention, the carrier aggregation is called inter-ENB
carrier aggregation or dual connectivity.
[0227] Hereinafter, the terms frequently used in the present
specification will be described.
[0228] As the traditional meaning, when one forward carrier
transmitted from one gas station and one reverse carrier received
by the base station configure one cell, the carrier aggregation may
also be understood that the terminal simultaneously transmits and
receives data through several cells. By doing so, the maximum
transmission rate is increased in response to the integrated number
of carriers.
[0229] Therefore, receiving, by the terminal, data through any
forward carrier or transmitting, from the terminal, the data
through any reverse carrier have the same meaning as transmitting
and receiving the data through a control channel and a data channel
which are provided from a cell a central frequency and a frequency
band characterizing the carriers. Therefore, the carrier
aggregation in the existing LTE 3GPP Release 10 standard has the
same meaning as configuring a plurality of serving cells, in which
the serving cell may be divided into a primary serving cell
(hereinafter, PCell) and a secondary serving cell (hereinafter,
SCell) according to the role of the respective serving cells. The
PCell is a main serving cell taking charging of an access of the
terminal to the network and mobility of the terminal and the SCell
is a serving cell additionally configured at the time of the
carrier aggregation to increase the uplink and downlink
transmission and reception rate of the terminal and is mainly used
to transmit user data.
[0230] In the dual connectivity, a set of the serving cells is
newly defined as follows. The serving cells (PCell, SCell, and the
like for the carrier aggregation) of the macro base station are
divided into a primary cell group (PCG) (or master cell group
(MCG)) and the serving cell (SCell, etc.) of the small cell base
station is divided into a secondary cell group (SCG). The MCG means
a set of the serving cells controlled by the macro base station
(master base station, main base station, or MeNB) controlling the
PCell and the SCG means a set of the serving cells controlled by
the base station (secondary base station, sub0base station, or
SeNB), not by the base station controlling the PCell. The base
station instructs information on whether a predetermined serving
cell belong to the MCG or the SCG to the terminal while the
corresponding serving cell is configured.
[0231] The main use purpose of the terms is to differentiate what
cell is controlled by the base station controlling a PCell of a
specific terminal and an operation scheme of the corresponding cell
may be different depending on whether the cell is controlled by the
base station (MeNB) controlling the PCell of the specific terminal
and whether the cell is controlled by another base station
(SeNB).
[0232] Unless particularly described, abbreviations/terms used in
the present invention follows defined standards 3GPP TS 36.211,
36.213, 36.213, 36.300, 36.321, 36.322, 36.323, and 36.331.
[0233] The present invention proposes a power headroom report (PHR)
operation associated with the dual connectivity.
[0234] The PHR allows the terminal to report the available
transmission power to the base station and if the predetermined
condition is satisfied, the terminal transmits the PHR to the base
station. Three kinds of PHAR formats of a normal PHR format, an
extended PHR format, and a dual connectivity PHR format may be
present.
[0235] FIG. 17 is a diagram illustrating the normal PHR format.
According to FIG. 17, PH information on one serving cell is
received in the normal PHR format, in which the PH 1700 is 6 bit
indexes and have a value between 0 and 63.
[0236] FIG. 18 is a diagram illustrating the extended PHR format.
According to FIG. 18, the extended PHR format includes the PH
information and PCMAX information which is the maximum information
of the terminal on a plurality of serving cells. The terminal
transmits the PH of the serving cells which is in the activated
state at the corresponding timing and is included in the extended
PHR to the base station.
[0237] FIG. 19 is a diagram illustrating the dual connectivity PHR
format.
[0238] Referring to FIG. 19, the dual connectivity PHR format is
similar to the extended PHR format and includes another type 2 PH
1900 for the primary secondary cell (PSCell) which may transmit
uplink control information among the serving cells configured in
the sub-base station, compared to the extended PHR.
[0239] The base station may determine whether the PHR function is
configured in any terminal and what format is used to instruct the
terminal.
[0240] An element defining the PHR function is several. An example
of the element may include a parameter specifying a PHR triggering
event, a parameter controlling periodic PHR transmission, etc. The
information is transmitted to the terminal through the upper layer
signal (used together mixed RRC signaling) while being received in
the information element called phr-Config.
[0241] The PHR format transmitted from the terminal to the base
station is determined by parameter of extendedPHR and
dualconnectivityPHR. If either of the two information is not
signaled, the normal PHR format is used, if the extendedPHR is
signaled, the extendedPHR format is used, and if the
dualconnectivityPHR is signaled, the dualconnectivity PHR format is
used. The base station determines what format is applied in
consideration of the current situation.
[0242] FIG. 20 illustrates a process of determining the PHR format
to which the base station will be applied, according to the present
embodiment.
[0243] Referring to FIG. 20, in step 2005, the base station starts
a process of determining the PHR format which will be configured in
any terminal.
[0244] In step 2010, the base station checks whether the dual
connectivity is configured in the terminal. Alternatively, it is
checked whether the SCG is configured in the terminal or the SCG
MAC is configured in the terminal.
[0245] As the check result, if the dual connectivity is configured,
it proceeds to the step 2015 and if the dual connectivity is not
configured, it proceeds to step 2030.
[0246] In step 2015, the base station checks whether the phr-Config
is configured and if configured, it proceeds to step 2020 and if
not configured, it proceeds to step 2025.
[0247] In the step 2020, the base station configures the dual
connectivity PHR format in the terminal. That is, the RRC control
message in which the dualconnectivity PHR is configured as setup in
the terminal is generated and transmitted to the terminal.
[0248] In step 2025, the base station generates the phr-Config
receiving parameters appropriate for the terminal and the RRC
control message including the dualconnectivity PHR configured as
the setup and transmits the generated phr-Config and RRC control
message to the terminal.
[0249] In step 2030, the base station checks whether the serving
cell with configured uplink is one or more and if so, that is, if
the uplink is configured in the plurality of serving cell, it
proceeds to step 2035 and if only one serving cell with configured
uplink is present, it proceeds to step 2040.
[0250] In step 2035, the base station checks whether the phr-Config
is configured in the terminal and if configured, it proceeds to
step 2045 and if not configured, it proceeds to step 2050.
[0251] In the step 2045, the base station configures the extended
PHR format in the terminal. That is, the RRC control message in
which the extendedPHR is configured as setup is generated and
transmitted to the terminal.
[0252] In step 2050, the base station generates the phr-Config
receiving appropriate parameters and the RRC control message
including the extendedPHR configured as the setup and transmits the
generated phr-Config and RRC control message to the terminal.
[0253] In the step 2040, the base station configures the normal PHR
format in the terminal. If the phr-Config is not configured in the
terminal, the base station generates the RRC control message in
which the phr-Config is received and transmits the generated RRC
control message to the terminal.
[0254] FIG. 21 illustrates the terminal operation according to the
present embodiment.
[0255] Referring to FIG. 21, in step 2105, the terminal establishes
the RRC connection to the base station.
[0256] If the base station needs to configure the PHR function in
performing the transmission and reception to and from the terminal,
the base station generates the RRC control message including the
phr-Config and transmits the generated RRC control message to the
terminal. In step 2110, the terminal receiving the phr-Config
configures the PHR function according to one instructed in the
control information and proceeds to step 2115 to apply the normal
PHR format, thereby performing the PHR operation.
[0257] In step 2120, when the terminal receives the control message
instructing the change in the PHR format, the terminal proceeds to
step 2123.
[0258] In step 2123, the terminal checks whether the extendedPHR is
included in the control message or the dualConnectivityPHR is
included in the control message, and if the extendedPHR is
included, the terminal proceeds to step 2125 and if the
dualConnectivityPHR is included, the terminal proceeds to step
2150.
[0259] Next, in step 2125, the terminal checks whether the dual
connectivity is configured therein, and if configured, the terminal
proceeds to step 2140 and if not configured, the terminal proceeds
to step 2130.
[0260] In step 2130, the terminal applies the extended PHR format
to perform the PHR. If the base station instructs that the
phr-Config is released in the future, the terminal releases the
extended PHR together (2135).
[0261] In step 2140, the terminal disregards the received control
message, and the terminal proceeds to step 2145 to start an RRC
connection re-establishment procedure. The reason is that the dual
connectivity is configured in the terminal but the extendedPHR
indicated as the control message by the base station is an obvious
error, and therefore the current RRC connection is highly likely to
be wrong.
[0262] In step 2150, the terminal receiving the control message in
which the dualConnectivityPHR is included checks whether the dual
connectivity is configured, and if the dual connectivity is
configured, the terminal proceeds to step 2155 and if the dual
connectivity is not configured, the terminal proceeds to step
2140.
[0263] The terminal proceeding to step 2155 checks whether both of
the phr-Config and the dualConnectivityPHR are configured in one
cell group (for example, MCG or SCG) and if not configured, the
terminal proceeds to step 2140 and if configured, the terminal
proceeds to step 2160. Proceeding from the step 2155 to the step
2140 means that the case in which the phr-Config for the MAC of the
cell group instructed by the dualConnectivityPHR is not configured
is generated. Proceeding from the step 2155 to the step 2160 means
that the phr-Config for the MAC of the cell group instructed by the
dualConnectivityPHR is configured.
[0264] The terminal proceeding to the step 2160 performs the PHR
applying the dualConnectivity PHR format to the cell group in which
both of the phr-Config and the dualConnectivityPHR are
configured.
[0265] Next, in step 2165, if the base station instructs the
release of the phr-Config of the CG in the future, even though the
base station does not separately instruct the release for the
dualConnectivityPHR, the dualConnectivityPHR of the CG is released
together.
[0266] In summary, the base station configures the PHR in the
terminal, and therefore the dual connection is not configured and
the extendedPHR is set as setup for the terminal in which the
uplink is configured in at least one serving cell and the
dualConnectivityPHR is configured as setup for the configured
terminal.
[0267] If both of the dualConnectivityPHR and the phr-Config are
configured for one cell group, the terminal uses the
dualConnectivity PHR format to perform the PHR. Further, if the
phr-Config is released for the CG, the dualConnectivityPHR of the
corresponding CG is released together.
[0268] FIG. 22 is a block configuration diagram of a terminal in a
wireless communications system according to an exemplary embodiment
of the present disclosure.
[0269] Referring to FIG. 22, the terminal includes a radio
frequency (RF) processor 2210, a baseband processor 2220, a storage
unit 2230, and a controller 2240.
[0270] The RF processor 2210 serves to transmit/receive as signal
through a radio channel, such as band conversion and amplification
of a signal. That is, the RF processor 2210 up-converts a baseband
signal provided from the baseband processor 2220 into an RF band
signal and then transmits the baseband signal through an antenna
and down-converts the RF band signal received through the antenna
into the baseband signal. For example, the RF processor 2210 may
include a transmitting filter, a receiving filter, an amplifier, a
mixer, an oscillator, a digital to analog converter (DAC), an
analog to digital converter (ADC), or the like. FIG. 22 illustrates
only one antenna but the terminal may include a plurality of
antennas. Further, the RF processor 2210 may include the plurality
of RF chains. Further, the RF processor 2210 may perform
beamforming. For the beamforming, the RF processor 2210 may adjust
a phase and a size of each of the signals transmitted and received
through a plurality of antennas or antenna elements.
[0271] The baseband processor 2220 performs a conversion function
between the baseband signal and the bit string according to a
physical layer standard of the system. For example, when data are
transmitted, the baseband processor 2220 generates complex symbols
by coding and modulating a transmitting bit string. Further, when
data are received, the baseband processor 2220 recovers the
receiving bit string by demodulating and decoding the baseband
signal provided from the RF processor 2210. For example, according
to the orthogonal frequency division multiplexing (OFDM) scheme,
when data are transmitted, the baseband processor 2220 generates
the complex symbols by coding and modulating the transmitting bit
string, maps the complex symbols to sub-carriers, and then performs
an inverse fast Fourier transform (IFFT) operation and a cyclic
prefix (CP) insertion to configure the OFDM symbols. Further, when
data are received, the baseband processor 2220 divides the baseband
signal provided from the RF processor 2210 in an OFDM symbol unit
and recovers the signals mapped to the sub-carriers by a fast
Fourier transform (FFT) operation and then recovers the receiving
bit string by the modulation and decoding.
[0272] The baseband processor 2220 and the RF processor 2210
transmit and receive a signal as described above. Therefore, the
baseband processor 2220 and the RF processor 2210 may be called a
transmitter, a receiver, a transceiver, or a communication unit.
Further, at least one of the baseband processor 2220 and the RF
processor 2210 may include a plurality of communication modules to
support a plurality of different radio access technologies.
Further, at least one of the baseband processor 2220 and the RF
processor 2210 may include different communication modules to
process signals in different frequency bands. For example, the
different radio access technologies may include the wireless LAN
(for example: IEEE 802.11), a cellular network (for example: LTE),
or the like. Further, different frequency bands may include a super
high frequency (SHF) (for example: 2.5 GHz, 5 GHz) band, a
millimeter wave (for example: 60 GHz) band.
[0273] The storage unit 2230 stores data such as basic programs,
application programs, and configuration information for the
operation of the terminal. In particular, the storage unit 2230 may
store information associated with a second access node performing
wireless communication using a second access technology. Further,
the storage unit 2230 provides the stored data according to the
request of the control unit 2240.
[0274] The controller 2240 controls the general operations of the
terminal. For example, the controller 2240 transmits/receives a
signal through the baseband processor 1420 and the RF processor
2210. Further, the controller 2240 records and reads data in and
from the storage unit 2240. For this purpose, the controller 1440
may include at least one processor. For example, the controller
2240 may include a communication processor (CP) performing a
control for communication and an application processor (AP)
controlling an upper layer such as the application programs.
According to the embodiment of the present invention, the
controller 2240 may control the terminal to perform the operation
and the procedure of the terminal illustrated in FIGS. 20 and
21.
[0275] FIG. 23 is a block configuration diagram of a main base
station in a wireless communication system according to an
exemplary embodiment of the present disclosure.
[0276] As illustrated in FIG. 23, the gas station is configured to
include an RF processor 2310, a baseband processor 2320, a backhaul
communication unit 2330, a storage unit 2340, and a controller
2350. The base station may be the main base station.
[0277] The RF processor 2310 serves to transmit/receive as signal
through a radio channel, such as band conversion and amplification
of a signal. That is, the RF processor 2310 up-converts a baseband
signal provided from the baseband processor 2320 into an RF band
signal and then transmits the baseband signal through an antenna
and down-converts the RF band signal received through the antenna
into the baseband signal. For example, the RF processor 2310 may
include a transmitting filter, a receiving filter, an amplifier, a
mixer, an oscillator, a DAC, an ADC, etc. FIG. 23 illustrates only
one antenna but the base station may include a plurality of
antennas. Further, the RF processor 2310 may include the plurality
of RF chains. Further, the RF processor 2310 may perform the
beamforming. For the beamforming, the RF processor 2310 may adjust
a phase and a size of each of the signals transmitted and received
through a plurality of antennas or antenna elements.
[0278] The baseband processor 2320 performs a conversion function
between the baseband signal and the bit string according to the
physical layer standard of the system. For example, when data are
transmitted, the baseband processor 2320 generates complex symbols
by coding and modulating a transmitting bit string. Further, when
data are received, the baseband processor 2320 recovers the
receiving bit string by demodulating and decoding the baseband
signal provided from the RF processor 2310. For example, according
to the OFDM scheme, when data are transmitted, the baseband
processor 2320 generates the complex symbols by coding and
modulating the transmitting bit string, maps the complex symbols to
the sub-carriers, and then performs the IFFT operation and the CP
insertion to configure the OFDM symbols. Further, when data are
received, the baseband processor 2320 divides the baseband signal
provided from the RF processor 2310 in the OFDM symbol unit and
recovers the signals mapped to the sub-carriers by the FFT
operation and then recovers the receiving bit string by the
modulation and decoding. The baseband processor 2320 and the RF
processor 2310 transmit and receive a signal as described above.
Therefore, the baseband processor 2320 and the RF processor 2310
may be called a transmitter, a receiver, a transceiver, a
communication unit, or a wireless communication unit.
[0279] The backhaul communicator 2330 provides an interface for
performing communication with other nodes within the network. That
is, the backhaul communication unit 2330 converts bit strings
transmitted from the main base station to other nodes, for example,
an auxiliary base station, a core network, etc., into physical
signals and converts the physical signals received from other nodes
into the bit strings.
[0280] The storage unit 2340 stores data such as basic programs,
application programs, and setting information for the operation of
the main base station. In particular, the storage unit 2340 may
store the information on the bearer allocated to the accessed
terminal, the measured results reported from the accessed terminal,
etc. Further, the storage unit 2340 may store information that is
the determination reference on whether to provide a multi-link to
the terminal or store the multi-link to the terminal. Further, the
storage unit 2340 provides the stored data according to the request
of the control unit 1550.
[0281] The controller 2350 controls the general operations of the
main base station. For example, the controller 2350
transmits/receives a signal through the baseband processor 2320 and
the RF processor 2310 or the backhaul communicator 2330. Further,
the controller 2350 records and reads data in and from the storage
unit 2340. For this purpose, the controller 2350 may include at
least one processor. According to the embodiment of the present
invention, the controller 2350 includes a multi-link controller
2352 that performs a control to provide the multi-link to the
terminal. For example, the controller 2350 may control the main
base station to perform the operation and procedure illustrated in
the operation of the base station illustrated in FIGS. 20 and
21.
Third Embodiment
[0282] Hereinafter, when it is determined that the detailed
description of the known art related to the present invention may
obscure the gist of the present invention, the detailed description
thereof will be omitted. Hereinafter, embodiments of the present
invention will be described in detail with reference to the
accompanying drawings.
[0283] The present invention relates to a method and an apparatus
for performing a scheduling request (SR) in a plurality of cells
which may transmit a physical uplink control channel (PUCCH) in an
LTE mobile communication system.
[0284] FIG. 24 is a diagram illustrating a structure of the LTE
system to which the present invention is applied.
[0285] Referring to FIG. 24, a radio access network of the LTE
system is configured to include next-generation base stations
(evolved node B, hereinafter, ENB, Node B, or base station) 2405,
2410, 2415, and 2420, a mobility management entity (MME) 2425, and
a serving-gateway (S-GW) 2430. User equipment (hereinafter, UE or
terminal) 2435 is connected to an external network through the ENBs
2405, 2410, 2415, and 2420 and the S-GW 2430.
[0286] In FIG. 24, the ENBs 2405, 2410, 2415, and 2420 correspond
to the existing node B of a UMTS system. The ENB is connected to
the UE 2435 through a radio channel and performs more complicated
role than the existing node B. In the LTE system, in addition to a
real-time service like a voice over Internet protocol (VoIP)
through the Internet protocol, all the user traffics are served
through a shared channel and therefore an apparatus for collecting
and scheduling status information such as a buffer status, an
available transmission power status, and a channel state of the UEs
is required. Here, the ENBs 2405, 2410, 2415, and 2420 take charge
of the collecting and scheduling.
[0287] One ENB generally controls a plurality of cells. For
example, to implement a transmission rate of 100 Mbps, the LTE
system uses, as a radio access technology, orthogonal frequency
division multiplexing (hereinafter, OFDM) in, for example, a
bandwidth of 20 MHz. Further, an adaptive modulation & coding
(hereinafter, called AMC) determining a modulation scheme and a
channel coding rate depending on a channel status of the terminal
is applied. The S-GW 2430 is an apparatus for providing a data
bearer and generates or removes the data bearer according to the
control of the MME 2425. The MME is an apparatus for performing a
mobility management function for the terminal and various control
functions and is connected to a plurality of base stations.
[0288] FIG. 25 is a diagram illustrating a radio protocol structure
in an LTE system to which the present invention is applied.
[0289] Referring to FIG. 25, the radio protocol of the LTE system
consists of packet data convergence protocols (PDCPs) 2505 and
2540, radio link controls (RLCs) 2510 and 2535, and medium access
controls (MMCs) 2515 and 2530 in the terminal and the ENB,
respectively. The packet data convergence protocols (PDCPs) 2505
and 2540 performs operations such as compression/recovery of an IP
header and the radio link controls (hereinafter, referred to as
RLC) 2510 and 2535 reconfigures a PDCP packet data unit (PDU) at an
appropriate length to perform an ARQ operation, or the like. The
MACs 2515 and 2530 are connected to several RLC layer apparatuses
configured in one terminal and performs an operation of
multiplexing RLC PDUs into an MAC PDU and demultiplexing the RLC
PDUs from the MAC PDU. Physical layers 2520 and 2525 perform an
operation of channel-coding and modulating upper layer data, making
them as an OFDM symbol, and transmitting them to the radio channel
or an operation of demodulating the OFDM symbol received through
the radio channel, channel-decoding it, and transmitting it to an
upper layer.
[0290] FIG. 26 is a diagram for describing improved carrier
aggregation applied to the terminal.
[0291] Referring to FIG. 26, one base station generally transmits
and receives multi-carriers over several frequency bands. For
example, when the base station 2605 transmits uplink carriers for
four cells, according to the related art, one terminal uses one of
the plurality of cells to transmit and receive data. However, the
terminal having carrier aggregation ability may simultaneously
transmit and receive data through several carriers. The base
station 2605 may allocate more carriers to the terminal 2630 having
the carrier aggregation ability in some case to increase a
transmission rate of the terminal 2630.
[0292] As the traditional meaning, when one forward carrier
transmitted from one gas station and one reverse carrier received
by the base station configure one cell, the carrier aggregation may
also be understood that the terminal simultaneously transmits and
receives data through several cells. By doing so, the maximum
transmission rate is increased in response to the integrated number
of carriers. The LTE Release 10 carrier aggregation technology may
configure up to five cells in one terminal. One of the configured
cells necessarily has the PUCCH, the cell is called a primary cell
(PCell), and the rest cells which do not have the PUCCH is called a
secondary cell (SCell). The PCell needs to be able to perform
functions of a traditional serving cell such as a handover and a
radio link failure (RLF) related operation performance, in addition
to features having the PUCCH.
[0293] Hereinafter, in describing the present invention, receiving,
by the terminal, data through any forward carrier or transmitting,
from the terminal, the data through any reverse carrier have the
same meaning as transmitting and receiving the data through a
control channel and a data channel which are provided from a cell a
central frequency and a frequency band characterizing the carriers.
Further, the following embodiment of the present invention will
describe the LTE system for convenience of explanation but the
present invention may be applied to various kinds of wireless
communication systems supporting the carrier aggregation.
[0294] In the Release 10 carrier aggregation technology, the uplink
control information may be transmitted and received through the
PUCCH only in the PCell. However, if an information amount to be
transmitted to the base station through the PUCCH is increased,
processing, by only the single PUCCH, the corresponding information
amount may be burdened. In particular, a method for supporting up
to 32 carriers has been discussed in the LTE Release 13 and in
addition to the PCell, making the SCell have the PUCCH has an
advantage of a PUCCH loading dispersion, or the like. Therefore, in
addition to the PCell, a method for introducing the PUCCH into the
SCell has been proposed. For example, in FIG. 26, the PUCCH may be
additionally introduced into one SCell 2620. In the present
invention, the SCell having the PUCCH is called a PUCCH SCell.
[0295] Conventionally, all PUCCH related signaling is transmitted
to the base station through the PCell. However, the plurality of
PUCCHs are present, and therefore there is a need to differentiate
through which PUCCH the PUCCH signalings of each SCell are
transmitted to the base station. As illustrated in FIG. 26, if it
is assumed that two PUCCHs are present, to transmit the uplink
control information, they are differentiated into a group 2635 of
cells using the PUCCH of the PCell and a group 2640 of cells using
the PUCCH of a specific SCell. In the present invention, the group
is called a PUCCH cell group.
[0296] As described above, when up to 32 carriers are configured in
one terminal to be used for a data transmitting and receiving
service, the maximum transmission rate of the corresponding
terminal is greatly improved. In this case, theoretically, the
maximum transmission rate reaches approximately 25 Gbps. To support
this, field lengths of layer 2 (PDCP, RLC, and MAC) parameters need
to be increased together.
[0297] In the present invention, when the situation in which the
field lengths of the layer 2 parameters need to be increased
happens, a method for effectively configuring the situation has
been proposed. Further, a format for variably changing a filed
indicating a length of an MAC header has been proposed.
[0298] In the present invention, as the maximum transmission rate
of the terminal is increased, a sequence number (SN) of a PDCP
layer, an SN and a segment offset (SO) of an RLC layer, and a
length L field of the MAC field are chosen as the layer 2 parameter
fields whose the field lengths need to be expanded together.
[0299] A PDCP SN field is a value given one by one for each PDCP
PDU generated at the PDCP layer and allocates the PDCP SN value
increased by 1 to the PDCP SDU according to the generated order.
The length of the PDCP SN is as the following table 2.
TABLE-US-00002 TABLE 2 Length Description 5 SRBs 7 DRBs, if
configured by upper layers (pdcp-SN-Size [3]) 12 DRBs, if
configured by upper layers (pdcp-SN-Size [3]) 15 DRBs, if
configured by upper layers (pdcp-SN-Size [3]) 16 SLRBs
[0300] Here, once a data radio bearer (DRB) associated with the
data transmission is considered, up to 15 bits are used to indicate
the length of the PDCP SN. The bit information used to indicate the
length of the PDCP SN is transmitted to and configured in the
terminal through an RRC message (PDCP-config IE).
[0301] The RLC SN field is a value given one by one for each RLC
PDU generated at the RLC layer and has different lengths according
to a kind of RLC PDUs. 10 bits in the case of an acknowledgement
mode data PDU (AMD PDU) and an AMD PDU segment and 5 bits or 10
bits in the case of an unacknowledgement mode data PDU (UMD PDU)
are used to indicate a length of the RLC SN. The bit information
used to indicate the length of the RLC SN is transmitted to and
configured in the terminal through the RRC message (PDCP-config
IE).
[0302] An RLC SO field is used to indicate to which position of an
original AMD PDU the AMD PDU segment corresponds. The length of the
field is fixed as 15 bits.
[0303] An MAC L field is used to indicate a length of an MAC SDU
introduced into the MAC layer or a length of an MAC control element
(CE) having a variable length. In the length of the field, 7 bits
or 15 bits are used to indicate the MAC L field. It is determined
which of the bit values is used based on a value of an F field just
before the L field. For example, if the F field value is 0, the
length of the L field has 7 bits and if the F field value is 1, the
length of the L field has 15 bits.
[0304] If the maximum transmission rate of the terminal is greatly
increased, the number of bits used to indicate the fields needs to
be increased. For example, the number of predicted bits to be
increased is as the following Table 3. If the terminal is
configured to have the maximum transmission rate, the field
configuration information supporting the same may be configured
together. The present invention proposes a method for configuring
and releasing an extended PDCP header and an extended RLC header
together to lower terminal implementation complexity and reduce
signaling overhead.
TABLE-US-00003 TABLE 3 Existing header Extended header field (AM
DRB) field (AM DRB) PDCP SN 12 or 15 bit 23 bit RLC SN 10 bit 18
bit RLC SO 15 bit 23 bit MAC L 7 or 15 bit 7 or 15 or 23 bit
[0305] The present embodiment is characterized in that the length
of the RLC SN for any AM DRB, the length of the RLC SO, and the
length of the MAC L are determined based on the length of the PDCP
SN. That is, if the PDCP SN for any AM DRB is set to be 15 bits or
12 bits like before, as the RLC SN, 10 bits are used, as the RLC
SO, 15 bits are used, and the MAC L field uses 7 bits or 15 bits.
Otherwise, if the PDCP SN for any AM DRB is set to be extended 23
bits, as the RLC SN, 18 bits are used, as the RLC SO, 15 bits are
used, and the MAC L field uses 7 bits, 15 bits, or 23 bits.
[0306] The length of the MAC L field is indicated based on F which
is another field within the MAC header unlike the case of the PDCP
SN configured as the RRC message, the RLC SN, and the RLC SO.
[0307] FIG. 27 illustrates a format of the MAC header according to
the existing technology.
[0308] FIG. 27 is a diagram for describing the F field indicating
the length of the MAC L field. The MAC PDU may consist of a
plurality of MAC CEs and a plurality of MAC SDUs. The MAC CE is
included if necessary, and therefore is not necessarily included in
the MAC PDU. To indicate the plurality of MAC CEs and MAC SDUs, a
header portion which is a front portion of the MAC PDU is filled
with sub-headers corresponding to the MAC CE and the MAC SDU,
respectively, one-to-one. In the existing technology, two
sub-header formats, that is, FIGS. 27A and 27B are present
depending on the length of the L field.
[0309] In FIG. 27, an R field is reserved bits 2700 and 2725 and
has a 0 value and E fields 2705 and 2730 indicate whether other
sub-headers in addition to the present sub-header are present. If
the E field is set to be 1, other sub-headers are continued on the
present sub-header, and otherwise, if the E field is set to be 0,
the MAC SDU, the MAC CE, or padding bits are continued on the
present sub-header. LCID fields 2710 and 2735 indicate a kind of
MAC CE or MAC SDU corresponding to the present sub-header. The F
fields 2715 and 2740 indicate the length of the L field included in
the present sub-header. If the F field is set to be 0, it means
that a length of an L field 2720 is 7 bits. In other words, it
means that the size of the MAC CE or the MAC SDU corresponding to
the present sub-header is smaller than 128 bytes. If the F field is
set to be 1, the length of the L field is 15 bits (2745). The L
field is described above.
[0310] The present embodiment proposes a new MAC sub-header format
which may indicate the extended L field. In the present embodiment,
as the extended L field value, the following two methods are
proposed. The first method defines a new 1-bit F field at a
position not concatenated to the existing F field. A second method
is to extend the existing F field to 2 bits and has a form in which
added 1 bit is concatenated to the existing F field. Independent of
the method, in conclusion, 1-bit F field is further added, and
therefore the L field having up to four sizes may be indicated.
[0311] According to the first method, various formats depending on
at which position newly added 1-bit F field is positioned may be
present. FIGS. 28 and 29 illustrate two of several formats.
[0312] FIG. 28 is a diagram illustrating a format in which the
newly added F field is present at the existing reserved bit
position.
[0313] As described above, the reserved bit of 2 bits is present in
the existing sub-header format, but one of them is used as the new
F field. FIG. 28 illustrates a method for using an R bit later
positioned among the two reserved bits as a new F field, that is,
F2 2800, 2825, and 2830. To differentiate the new F field, the
existing F field is named F1 2805, 2820, and 2835. If F1=0, the
length of the L field is 7 bits (2810). If F1=1 and F2=0, the
length of the L field is 15 bits (2825). If F1=1 and F2=1, the
length of the L field is 23 bits (2840). The method uses the
existing reserved bit to increase bit utilization. Further, the F
field is used in the reserved bit relatively positioned at a head
is used, and therefore when the sub-header bits are sequentially
searched, it may know whether the L field extended at very rapid
time is used.
[0314] FIG. 29 is a diagram illustrating a format in which a new F
field is present, after two bytes.
[0315] In FIG. 29, F1 fields 2905, 2915, and 2930 have 0 or 1 value
depending on whether a 7-bit F field or an F field more than that
is present. If F1=0, after F1, a 7-bit L field 2910 is continued.
In the present format, in addition to 7 bits as the length of the L
field, 15 bits or 22 bits are considered. The reason is that a
newly added F2 field is present at a position other than the
reserved bit. To prevent bits from being discarded without being
used, the sub-header needs to maintain a byte unit. Therefore, the
byte unit is maintained, and in this case, one of the available
bits is used as a new F2 field, and therefore the number of bits
used in the L field may be naturally reduced one. Generally, it is
difficult to reduce a bits allocated to another field, that is, the
LCID field.
[0316] In the present embodiment, after the first two bytes, a new
F2 field is positioned. However, in the drawings, an F2 filed among
the bits allocated to the L field may be present at any position,
and the position needs to be promised in advance. If the value of
the F2 field is 0 2920, 7-bit L field 2925 is additionally
positioned behind the F2 field. Therefore, a total 14 bits of L
field is made. If the value of the F2 field is set to be 1 2935, a
15-bit L field 2940 is additionally positioned behind the F2
field.
[0317] FIG. 30 is a diagram illustrating a format in which the
existing F field is extended.
[0318] Referring to FIG. 30, an added 1 bit is concatenated to the
existing F fields 3015, 3040, and 3065. If F=00 3015, a 6-bit L
field is present. If F=00 3040, a 14-bit L field is present. If
F=10 3065, a 22-bit L field is present.
[0319] FIG. 31 is a flow chart illustrating a terminal operation in
the present invention.
[0320] In step 3100, a terminal configures an RRC connection to a
serving cell. In step 3105, the terminal receives a control message
indicating an ability report from the base station. The control
message includes an indicator indicating a report of ability
associated with E-UTRA. In step 3110, the terminal generates a
control message reporting the E-UTRA capability and the message
includes information displaying whether to support an extended
Layer 2 header introduced in the present invention. Here,
supporting the extended Layer 2 header means supporting all of 23
bit PDCP SN, 18 bit RLC SN, 23 bit RLC SO, and extended MAC
sub-header (F1 and F2).
[0321] In step 3115, the terminal transmits the generated message
to the base station. In step 3120, the terminal receives an RRC
control message indicating the DRB configuration from the base
station. If the DRB configuration information is the same as the
existing DRB configuration information, that is, if it is mapped to
the AM RLC and the PDCP SN is 12 bits or 15 bits, the terminal
configures a format using RLC SN=10 bits and RLC SO=15 bits.
Further, the MAC PDU format is configured as a format using the
1-bit F field. This performs the existing operation. Otherwise, if
the DRB configuration information is mapped to the AM RLC and the
PDCP SN is 23 bits, as in the present invention it is configured as
a format using RLC SN=18 bit and RLC SO=23 bit without separate
signaling. Further, the MAC PDU format is configured as a format
using (or using 2-bit F field) F1 and F2 bits. The MAC sub-header
format including the detailed F1 and F2 format is already described
in detail. In step 3025, the terminal uses the configured format to
transmit and receive data.
[0322] FIG. 32 is a flow chart illustrating a base station
operation in the present invention.
[0323] In step 3200, the base station receives a capability report
message from the terminal. In step 3205, the base station transmits
a control message indicating the DRB and MAC header format
configuration to the terminal. If the terminal supports the
extended L2, PDCP SN=23 bits, RLC SN=18 bits, and RLC SO=23 bits or
PDCP SN=15 bits or 12 bits, RLC SN=10 bits, and RLC SO=15 bits.
Otherwise, if the terminal does not support the extended layer L2,
PDCP SN=15 bits or 12 bits, RLC SN=10 bits, and RLC SO=15 bits. If
the terminal supports the extended layer L2 and the RLC SO is set
to be 23 bits, it is configured to use the extended format. If the
terminal supports the extended layer L2 and the RLC SO is set to be
15 bits, it is configured not to use the extended format. If the
terminal does not support the extended layer L2, it is configured
not to use the extended format. In step 3210, the base station
performs transmission and reception to and from the terminal using
the configured L2 header format and the MAC format.
[0324] FIG. 33 is a diagram illustrating the terminal apparatus
which may perform the present embodiment.
[0325] Referring to FIG. 33 The terminal transmits and receives
data, etc., to and from an upper layer 3305, transmits and receives
control messages through a control message processor 3307, upon the
transmission, multiplexes data using a multiplexer 3303 according
to a control of a controller 3309 and then transmits (3301) the
data through the transmitter, and upon the reception, receives
(3301) a physical signal to the receiver according to the control
of the controller 3309, demultiplexes the received signal by a
demultiplexer 3303, and then transmits it to the upper layer 3305
or a control message processor 3307 according to the message
information.
[0326] In the present invention, if the control message processor
3307 receives an activation/deactivation MAC CE, the control
message processor 3307 informs an SCell activation/deactivation
processor 3311 of the received activation/deactivation MAC CE to
determine first timing upon activation and at the first timing, the
controller 3309 and the control message processor 3307 are
instructed to perform the operations to be performed at the first
timing. If the deactivation of the already activated SCell is
instructed, second timing is determined, and the controller 3309
and the control message processor 3307 are instructed to perform
first operations to be performed before the second timing and at
the second timing, are instructed to perform the second operations
to be performed at the second timing.
[0327] When using the proposed method, the defined operation is
performed at the timing when the SCell is activated and deactivated
in the case of using the carrier aggregation technology, thereby
preventing a malfunction and performing an accurate operation.
[0328] While the present invention has been described in connection
with the exemplary embodiments thereof, various modifications and
variations can be made without departing from the scope of the
present invention. Therefore, the scope of the present embodiment
should be not construed as being limited to the described exemplary
embodiments but be defined by the appended claims as well as
equivalents thereto.
[0329] FIG. 34 is a block diagram illustrating a configuration of
the base station according to the embodiment of the present
invention.
[0330] The base station apparatus of FIG. 341 includes a
transceiver 3405, a controller 3410, a multiplexer and
demultiplexer 3420, a control message processor 3435, various kinds
of upper layer processors 3425 and 3430, and a scheduler 3415.
[0331] The transceiver 3405 transmits data and a predetermined
control signal to a downlink carrier and the data and receives the
predetermined control signal through an uplink carrier. When a
plurality of carriers are configured, the transceiver 3405
transmits and receives data and a control signal through the
plurality of carriers.
[0332] The multiplexer and demultiplexer 3420 multiplexes data
generated from the upper layer processors 3425 and 3430 or the
control message processor 3435 or demultiplexes data received by
the transceiver 3405 and transmits the data to the appropriate
upper layer processors 3425 and 3430, the control message processor
3435, or the controller 3410. The control message processor 3435
allows the terminal to process the transmitted control message to
perform the required operation or generates the control message to
be transmitted to the terminal and transmits the generated control
message to the lower layer.
[0333] The upper layer processors 3425 and 3430 may be configured
for each terminal and each service and processes data generated
from user services such as FTP and VoIP and transmits the processed
data to the multiplexer and demultiplexer 3420 or processes data
transmitted from the multiplexer and demultiplexer 3420 and
transmits the processed data to service applications of the upper
layer.
[0334] The controller 3410 determines when the terminal transmits
channel status information, or the like to control the
transceiver.
[0335] The scheduler 3415 allocates a transmission resource to the
terminal at appropriate timing in consideration of the buffer
status and the channel status of the terminal, the operation time
of the terminal, etc., and allows the transceiver to process a
signal transmitted from the terminal or performs a process to
transmit a signal to the terminal.
Fourth Embodiment
[0336] Hereinafter, when it is determined that the detailed
description of the known art related to the present embodiment may
obscure the gist of the present embodiment, the detailed
description thereof will be omitted. Hereinafter, the present
embodiment will be described in detail with reference to the
accompanying drawings.
[0337] The present invention relates to a method and an apparatus
for performing a scheduling request (SR) in a plurality of cells
which may transmit a physical uplink control channel (PUCCH) in an
LTE mobile communication system.
[0338] FIG. 35 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0339] Referring to FIG. 35, a radio access network of the LTE
system is configured to include next-generation base stations
(evolved node B, hereinafter, ENB, Node B, or base station) 3505,
3510, 3515, and 3520, a mobility management entity (MME) 3525, and
a serving-gateway (S-GW) 3530. User equipment (hereinafter, UE or
terminal) 135 is connected to an external network through the ENBs
3505, 3510, 3515, and 3520 and the S-GW 3530.
[0340] In FIG. 1, the ENBs 3505, 3510, 3515, and 3520 correspond to
the existing node B of a UMTS system. The ENB is connected to the
UE 3535 through a radio channel and performs more complicated role
than the existing node B. In the LTE system, in addition to a
real-time service like a voice over Internet protocol (VoIP)
through the Internet protocol, all the user traffics are served
through a shared channel and therefore an apparatus for collecting
and scheduling status information such as a buffer status, an
available transmission power status, and a channel state of the UEs
is required. Here, the ENBs 3505, 3510, 3515, and 3520 take charge
of the collecting and scheduling.
[0341] One ENB generally controls a plurality of cells. For
example, to implement a transmission rate of 100 Mbps, the LTE
system uses, as a radio access technology, orthogonal frequency
division multiplexing (OFDM) in, for example, a bandwidth of 20
MHz. Further, an adaptive modulation & coding (AMC) determining
a modulation scheme and a channel coding rate depending on a
channel status of the terminal is applied. The S-GW 3530 is an
apparatus for providing a data bearer and generates or removes the
data bearer according to the control of the MME 3325. The MME is an
apparatus for performing a mobility management function for the
terminal and various control functions and is connected to a
plurality of base stations.
[0342] FIG. 36 is a diagram illustrating a radio protocol structure
in an LTE system to which the present embodiment is applied.
[0343] Referring to FIG. 36, the radio protocol of the LTE system
consists of packet data convergence protocols (PDCPs) 3605 and
3640, radio link controls (RLCs) 3610 and 3635, and medium access
controls (MMCs) 3615 and 3630 in the terminal and the ENB,
respectively. The packet data convergence protocols (PDCPs) 3605
and 3640 performs operations such as compression/recovery of an IP
header and the radio link controls (hereinafter, referred to as
RLC) 3610 and 3635 reconfigures a PDCP packet data unit (PDU) at an
appropriate size to perform an ARQ operation, or the like. The MACs
3615 and 3630 are connected to several RLC layer apparatuses
configured in one terminal and performs an operation of
multiplexing RLC PDUs into an MAC PDU and demultiplexing the RLC
PDUs from the MAC PDU. Physical layers 3620 and 3625 perform an
operation of channel-coding and modulating upper layer data, making
them as an OFDM symbol, and transmitting them to the radio channel
or an operation of demodulating the OFDM symbol received through
the radio channel, channel-decoding it, and transmitting it to an
upper layer.
[0344] FIG. 37 is a diagram illustrating improved carrier
aggregation system in the terminal.
[0345] Referring to FIG. 37, one base station generally transmits
and receives multi-carriers over several frequency bands. For
example, when the base station 305 receives uplink carriers for
four cells, according to the related art, one terminal uses one of
the plurality of cells to transmit and receive data. However, the
terminal having carrier aggregation ability may simultaneously
transmit and receive data using several carriers. The base station
3705 may allocate more carriers to the terminal 3730 having the
carrier aggregation ability in some case to increase a transmission
rate of the terminal 3730.
[0346] As the traditional meaning, when one forward carrier
transmitted from one gas station and one reverse carrier received
by the base station configure one cell, the carrier aggregation may
also be understood that the terminal simultaneously transmits and
receives data through several cells. By doing so, the maximum
transmission rate is increased in response to the integrated number
of carriers.
[0347] The LTE Release (Rel)-10 carrier aggregation technology may
configure up to five cells in one terminal. One of the configured
cells necessarily has the PUCCH, the cell is called a primary cell
(PCell), and the rest cells which do not have the PUCCH is called a
secondary cell (SCell). The PCell needs to be able to perform
functions of a traditional serving cell such as a handover and a
radio link failure (RLF) related operation performance, in addition
to features having the PUCCH.
[0348] Hereinafter, in describing the present invention, receiving,
by the terminal, data through any forward carrier or transmitting,
from the terminal, the data through any reverse carrier have the
same meaning as transmitting and receiving the data through a
control channel and a data channel which are provided from a cell a
central frequency and a frequency band characterizing the carriers.
Further, the following embodiment of the present invention will
describe the LTE system for convenience of explanation but the
present invention may be applied to various kinds of wireless
communication systems supporting the carrier aggregation.
[0349] In the Release 10 carrier aggregation technology, the uplink
control information may be transmitted and received through the
PUCCH only in the PCell. However, if an information amount to be
transmitted to the base station through the PUCCH is increased,
processing, by only the single PUCCH, the corresponding information
amount may be burdened. In particular, a method for supporting up
to 32 carriers has been discussed in the LTE Release 13 and in
addition to the PCell, making the SCell have the PUCCH has an
advantage of a PUCCH loading dispersion, or the like. Therefore, in
addition to the PCell, a method for introducing the PUCCH into the
SCell has been proposed. For example, in FIG. 37, the PUCCH may be
additionally introduced into one SCell 2620. In the present
invention, the SCell having the PUCCH is called a PUCCH SCell.
[0350] Conventionally, all PUCCH related signaling is transmitted
to the base station through the PCell. However, the plurality of
PUCCHs are present, and therefore there is a need to differentiate
through which PUCCH the PUCCH signalings of each SCell are
transmitted to the base station. As illustrated in FIG. 37, if it
is assumed that two PUCCHs are present, to transmit the uplink
control information, they are differentiated into a group 3735 of
cells using the PUCCH of the PCell and a group 3740 of cells using
the PUCCH of a specific SCell. In the present invention, the group
is called a PUCCH cell group.
[0351] The present invention proposes a process of activating the
PUCCH SCell. When the PUCCH SCell is activated, the present
embodiment performs the random access or the SR transmission
depending on whether the uplink synchronization is made.
[0352] Prior to describing the content of the present invention,
two methods for activating SCell according to the related art are
present, which will be described below.
[0353] FIG. 38 is a diagram illustrating a process of activating a
general SCell other than a PSCell in the related art.
[0354] Referring to FIG. 38, the terminal receives the RRC message
indicating an addition of the general SCell from the base station.
In this case, the terminal configures the general SCell. When the
terminal completes the configuration of the SCell, the state of the
SCell is deactivated (3805). Then, if the activation/deactivation
MAC CE is received from the base station, the terminal activates
the SCell (3810). If the activation of the SCell is completed, the
terminal reports valid channel state information CSI to the SCell
and transmits an SRS on the SCell (3815).
[0355] Another SCell is PSCell. The PSCell is configured when using
dual connectivity transmitting and receiving data by simultaneously
connecting the terminal to the plurality of base stations. In a
base station other than the base station including the PScell, only
one PSCell needs to be configured. The terminal transmits an uplink
PUCCH signal onto the PUCCH to the base station through the PSCell.
The PSCell is the SCell but has the PUCCH unlike the SCell and
after the configuration, is automatically activated.
[0356] FIG. 39 is a diagram illustrating a process of activating
PSCell in the related art.
[0357] Referring to FIG. 39, the terminal receives the RRC message
indicating an addition of the PSCell from the base station (3900).
In this case, the terminal configures the PSCell. If the
configuration of the PSCell is completed, the terminal
automatically activates the PSCell (3905). The PSCell is considered
as the deactivation state before the activation of the PSCell is
completed. If the activation of the PSCell is completed, the
terminal and the base station perform the random access using the
PSCell (3910).
[0358] In the present invention, the PUCCH SCell has the PUCCH like
the SCell or the PSCell. In this case, the method for activating
PUCCH SCell may introduce one of the existing two processes
described above. The configured PUCCH SCell is in the deactivation
state. According to the process of the general SCell, the terminal
receives the activation/deactivation MAC CE from the base station
and then starts the activation process. On the other hand,
according to the case of the PSCell, after the configuration
completion, the terminal automatically starts the activation
process. Another difference is an operation after the activation
completion. In the case of the general SCell, the valid CSI report
and the SRS transmission are performed, but in the case of the
PSCell, the random access is performed. The reason of performing
the random access is to synchronize the uplink of the terminal and
the base station and inform the base station that the activation of
the PSCell is completed.
[0359] FIG. 40 is a diagram illustrating a process of activating
PUCCH SCell according to the process of activating a general
SCell.
[0360] Referring to FIG. 40, the terminal receives the RRC message
indicating an addition of the PUCCH SCell from the base station
(4000). In this case, the terminal configures the PUCCH SCell. When
the terminal completes the configuration of the PUCCH SCell, the
state of the PUCCH SCell is deactivated (4005). Then, if the
terminal receives the activation/deactivation MAC CE from the base
station, the terminal activates the PUCCH SCell (4010). In this
case, the base station may not transmit the activation/deactivation
MAC CE immediately after the configuration completion. The reason
is that the terminal does not accurately know when it finishes
preparation to receive the MAC CE. Therefore, in consideration of
this situation, the base station holds a time margin to some extent
and then transmits the activation/deactivation MAC CE to the
terminal. If the activation of the PUCCH SCell is completed, the
terminal reports the valid CSI to the SCell and transmits the SRS
on the SCell (4015).
[0361] After the activation is completed, the base station may not
also know when the terminal reports the CSI and starts the SRS
transmission. Therefore, the base station needs to perform blind
decoding until the information is received. This increases the
complexity of the base station. When the uplink synchronization of
the base station and the terminal is not matched, the base station
additionally instructs the terminal to perform the random access
through a physical downlink control channel (PDCCH) order (may
serve to instruct the terminal to the random access). In this case,
a longer delay time is required for the CSI report and the SRS
transmission.
[0362] FIG. 41 is a diagram illustrating a process of activating
PUCCH SCell according to the process of activating a PSCell.
[0363] Referring to FIG. 41, the terminal receives the RRC message
indicating an addition of the PUCCH SCell from the base station
(4100). In this case, the terminal configures the PUCCH SCell. If
the configuration of the PUCCH SCell is completed, the terminal
automatically activates the PUCCH SCell (4105). The PUCCH SCell is
considered as the deactivation state before the activation of the
PUCCH SCell is completed. If the activation of the PUCCH SCell is
completed, the terminal and the base station performs the random
access to the PUCCH SCell (4110).
[0364] According to the related art, after the activation all the
times, the random access is performed, and therefore the base
station need not perform the blinding decoding. The reason is that
after the random access, the terminal will perform the valid CSI
report and the SRS transmission to the SCell. However, the case of
the rest SCell except for the case in which the base station
instructs the PUCCH SCell uses the activation/deactivation MAC CE
to perform the activation or deactivation process. Therefore, the
terminal needs to have two kinds of activation mechanisms, and
therefore the complexity is increased.
[0365] On the other hand, according to the existing process of
activating PSCell, performing the random access all the times may
be unnecessary in some cases. For example, when the SCell that is
being used as the general SCell is reconfigured as the PUCCH SCell,
the general SCell may be already synchronized. In this case, after
the activation of the PUCCH SCell is completed, it may be
unnecessary to perform the random access again.
[0366] The present embodiment proposes a method for changing the
existing process of activating PSCell to be appropriate for the
process of activating PUCCH PSCell while basically following the
existing process of activating PSCell. The present embodiment
performs another terminal operation depending on the uplink
synchronization after the PUCCH SCell is completed. That is, if the
PUCCH SCell is in the synchronized state in the uplink and the
dedicated scheduling configuration (D-SR) is configured, the
terminal transmits the D-SR n times and then starts the CSI
transmission and the SRS transmission. Otherwise, if the PUCCH
SCell is in the synchronized state in the uplink and the D-SR is
not configured, the terminal starts the CSI transmission and the
SRS transmission from the defined timing, for example, (n+m)
timing. Here, n may be timing when the RRC message configuring the
PUCCH SCell is received, timing when the configuration of the PUCCH
SCell is completed, or timing when the activation of the PUCCH
SCell is completed. If the PUCCH SCell is in an asynchronized state
in the uplink, the random access starts in the PUCCH SCell.
[0367] FIG. 42 is a flow chart illustrating a terminal operation in
the present embodiment.
[0368] Referring to FIG. 42, in step 4200, the terminal configures
the RRC connection to the LTE base station in the LTE serving cell.
In step 4205, the terminal receives a control message instructing
at least one SCell configuration from the base station. In step
4210, the terminal determines whether the configuration information
of the PUCCH SCell is included in the control message. If included,
based on the configuration information, the terminal completes the
configuration of the PUCCH SCell and then in step 4215, starts the
activation of the PUCCH SCell.
[0369] When the activation of the PUCCH SCell is completed, in step
4220, the terminal determines whether the PUCCH SCell is
synchronized in the upper link. The synchronization may be
determined depending on whether a valid time alignment timer (TAT)
timer is driving, for the PUCCH SCell. If the TAT timer is driving,
the synchronization is being maintained. Otherwise, the
synchronization process is required.
[0370] If asynchronized, in step 4225, the terminal starts the
random access on the PUCCH SCell. If synchronized, the terminal
starts the D-SR transmission on the PUCCH SCell. If the D-SR
transmission is not required, a predetermined time lapses and then
the CSI report and the SRS transmission are performed.
[0371] For the general SCell, the SCell configuration is completed
and then the SCell is configured to maintain the deactivation
state. In step 4235, the terminal receives the
activation/deactivation MAC CE from the base station. If the
instruction to activate the SCell in the deactivation state in the
A/D MAC CE is issued, in step 4240, the terminal starts the
activation of the SCell in the deactivation state. As described
above, the case except for the case in which the base station
instructs the PUCCH SCell uses the activation/deactivation MAC CE
like the general SCell to perform the process of activating or
deactivating the SCell.
[0372] In step 4245, the terminal determines whether the
instruction to activate the general SCell in the deactivation state
is issued. If the general SCell is in the asynchronized state, in
step 4250, the process waits until the synchronization is
established in the uplink. In this case, the base station will
instruct the terminal to perform the random access for
synchronization in the PDCCH order. If the general SCell is in the
synchronized state, the valid CSI report for the SCell and the SRS
transmission to the SCell start.
[0373] FIG. 43 illustrates the terminal apparatus which may perform
the present embodiment.
[0374] Referring to FIG. 43, the terminal transmits and receives
data, etc., to and from an upper layer 4305, transmits and receives
control messages through a control message processor 4307, upon the
transmission, multiplexes data using a multiplexer 4303 according
to a control of a controller 4309 and then transmits (4301) the
data through the transmitter, and upon the reception, receives
(4301) a physical signal to the receiver according to the control
of the controller 4309, demultiplexes the received signal by a
multiplexer and demultiplexer 4303, and then transmits it to the
upper layer 4305 or a control message processor 4307 according to
the message information.
[0375] In the present embodiment, if the control message processor
4307 receives the activation/deactivation MAC CE, the control
message processor 4307 informs an SCell activation/deactivation
processor 4311 of the received activation/deactivation MAC CE to
determine first timing upon activation and at the first timing, the
controller 4309 and the control message processor 4307 are
instructed to perform the operations to be performed at the first
timing. If the deactivation of the already activated SCell is
instructed, second timing is determined, and the controller 4309
and the control message processor 4307 are instructed to perform
first operations to be performed before the second timing and at
the second timing, are instructed to perform the second operations
to be performed at the second timing.
[0376] When using the proposed method, the defined operation is
performed at the defined timing when the SCell is activated and
deactivated in the case of using the carrier aggregation
technology, thereby preventing a malfunction and performing an
accurate operation.
[0377] While the present invention has been described in connection
with the exemplary embodiments thereof, various modifications and
variations can be made without departing from the scope of the
present embodiment. Therefore, the scope of the present embodiment
should be not construed as being limited to the described exemplary
embodiments but be defined by the appended claims as well as
equivalents thereto.
Fifth Embodiment
[0378] Hereinafter, when it is determined that the detailed
description of the known art related to the present embodiment may
obscure the gist of the present embodiment, the detailed
description thereof will be omitted. Hereinafter, the present
embodiment will be described in detail with reference to the
accompanying drawings.
[0379] The present invention relates to a method and an apparatus
for performing a scheduling request (SR) in a plurality of cells
which may transmit a physical uplink control channel (PUCCH) in an
LTE mobile communication system.
[0380] FIG. 44 is a diagram illustrating a structure of the LTE
system to which the present embodiment is applied.
[0381] Referring to FIG. 44, a radio access network of the LTE
system is configured to include next-generation base stations
(evolved node B, hereinafter, ENB, Node B, or base station) 4405,
4410, 4415, and 4420, a mobility management entity (MME) 4425, and
a serving-gateway (S-GW) 4430. User equipment (hereinafter, UE or
terminal) 4435 is connected to an external network through the ENBs
4405, 4410, 4415, and 4420 and the S-GW 4430.
[0382] In FIG. 44, the ENBs 4405, 4410, 4415, and 4420 correspond
to the existing node B of a UMTS system. The ENB is connected to
the UE 4435 through a radio channel and performs more complicated
role than the existing node B. In the LTE system, in addition to a
real-time service like a voice over Internet protocol (VoIP)
through the Internet protocol, all the user traffics are served
through a shared channel and therefore an apparatus for collecting
and scheduling status information such as a buffer status, an
available transmission power status, and a channel state of the UEs
is required. Here, the ENBs 4405, 4410, 4415, and 4420 take charge
of the collecting and scheduling.
[0383] One ENB generally controls a plurality of cells. For
example, to implement a transmission rate of 100 Mbps, the LTE
system uses, as a radio access technology, orthogonal frequency
division multiplexing (OFDM) in, for example, a bandwidth of 20
MHz. Further, an adaptive modulation & coding (AMC) determining
a modulation scheme and a channel coding rate depending on a
channel status of the terminal is applied. The S-GW 4430 is an
apparatus for providing a data bearer and generates or removes the
data bearer according to the control of the MME 4425. The MME is an
apparatus for performing a mobility management function for the
terminal and various control functions and is connected to a
plurality of base stations.
[0384] FIG. 45 is a diagram illustrating a radio protocol structure
in an LTE system to which the present invention is applied.
[0385] Referring to FIG. 45, the radio protocol of the LTE system
consists of packet data convergence protocols (PDCPs) 4505 and
4540, radio link controls (RLCs) 4510 and 4535, and medium access
controls (MMCs) 4515 and 4530 in the terminal and the ENB,
respectively. The packet data convergence protocols (PDCPs) 4505
and 4540 performs operations such as compression/recovery of an IP
header and the radio link controls (hereinafter, referred to as
RLC) 4510 and 4535 reconfigures a PDCP packet data unit (PDU) at an
appropriate size to perform an ARQ operation, or the like. The MACs
4515 and 4530 are connected to several RLC layer apparatuses
configured in one terminal and performs an operation of
multiplexing RLC PDUs into an MAC PDU and demultiplexing the RLC
PDUs from the MAC PDU. Physical layers 4520 and 4525 perform an
operation of channel-coding and modulating upper layer data, making
them as an OFDM symbol, and transmitting them to the radio channel
or an operation of demodulating the OFDM symbol received through
the radio channel, channel-decoding it, and transmitting it to an
upper layer.
[0386] FIG. 46 is a diagram illustrating an improved carrier
aggregation system in the terminal.
[0387] Referring to FIG. 46, one base station generally transmits
and receives multi-carriers over several frequency bands. For
example, when the base station 4605 receives uplink carriers for
four cells, according to the related art, one terminal uses one of
the plurality of cells to transmit and receive data. However, the
terminal having carrier aggregation ability may simultaneously
transmit and receive data through several carriers. The base
station 4605 may allocate more carriers to the terminal 4630 having
the carrier aggregation ability in some case to increase a data
transmission rate of the terminal 4630.
[0388] As the traditional meaning, when one forward carrier
transmitted from one gas station and one reverse carrier received
by the base station configure one cell, the carrier aggregation may
also be understood that the terminal simultaneously transmits and
receives data through several cells. By doing so, the maximum
transmission rate is increased in response to the integrated number
of carriers.
[0389] The LTE Release (Rel)-10 carrier aggregation technology may
configure up to five cells in one terminal. One of the configured
cells necessarily has the PUCCH, the cell is called a primary cell
(PCell), and the rest cells which do not have the PUCCH is called a
secondary cell (SCell). The PCell needs to be able to perform
functions of a traditional serving cell such as a handover and a
radio link failure (RLF) related operation performance, in addition
to features having the PUCCH.
[0390] Hereinafter, in describing the present invention, receiving,
by the terminal, data through any forward carrier or transmitting,
from the terminal, the data through any reverse carrier have the
same meaning as transmitting and receiving the data through a
control channel and a data channel which are provided from a cell a
central frequency and a frequency band characterizing the carriers.
Further, the following embodiment of the present invention will
describe the LTE system for convenience of explanation but the
present invention may be applied to various kinds of wireless
communication systems supporting the carrier aggregation.
[0391] In the Release 10 carrier aggregation technology, the uplink
control information may be transmitted and received through the
PUCCH only in the PCell. However, if an information amount to be
transmitted to the base station through the PUCCH is increased,
processing, by only the single PUCCH, the corresponding information
amount may be burdened. In particular, a method for supporting up
to 32 carriers has been discussed in the LTE Release 13 and in
addition to the PCell, making the SCell have the PUCCH has an
advantage of a PUCCH loading dispersion, or the like. Therefore, in
addition to the PCell, a method for introducing the PUCCH into the
SCell has been proposed. For example, in FIG. 46, the PUCCH may be
additionally introduced into one SCell 4620. In the present
invention, the SCell having the PUCCH is called a PUCCH SCell.
[0392] Conventionally, all PUCCH related signaling is transmitted
to the base station through the PCell. However, the plurality of
PUCCHs are present, and therefore there is a need to differentiate
through which PUCCH the PUCCH signalings of each SCell are
transmitted to the base station. As illustrated in FIG. 46, if it
is assumed that two PUCCHs are present, to transmit the uplink
control information, they are differentiated into a group 4635 of
cells using the PUCCH of the PCell and a group 4640 of cells using
the PUCCH of a specific SCell. In the present invention, the group
is called a PUCCH cell group.
[0393] In the LTE mobile communication system, the terminal reports
HARQ feedback information, channel status information report, and
an SR to the base station through the PUCCH.
[0394] FIG. 47 is a diagram illustrating a process of receiving a
radio resource allocated from the base station by allowing the
terminal to transmit the SR.
[0395] Referring to FIG. 47, in step 4710, a PDCP SDU to be
transmitted to a terminal 4700 is generated. In step 4715, the
terminal determines whether the radio resource transmitting the
data is present. If the resource is not present, it is determined
whether usable PUCCH is allocated. If the PUCCH is present, the SR
is transmitted to a base station 4705 using the PUCCH. In this
case, the terminal starts a scheduling request prohibit timer (SR
prohibit timer). The SR prohibit timer is introduced to prevent the
SR from being frequently transmitted. The SR prohibit timer is
derived by an sr-ProhibitTimer informationelement (IE) and SR
periodicity configured as the RRC message.
[0396] The following Table represents MAC-MainConfig IE. The IE is
provided to the terminal through the RRC message.
Sr-ProhibitTimer-r9 IE included in the MAC-MainConfig IE has values
between 0 to 7. The value of the SR prohibit timer value is derived
by a product of the value and the SR periodicity.
[0397] MAC-MainConfig Information Element
TABLE-US-00004 -- ASN1START MAC-MainConfig ::= SEQUENCE {
ul-SCH-Config SEQUENCE { maxHARQ-Tx ENUMERATED { n1, n2, n3, n4,
n5, n6, n7, n8, n10, n12, n16, n20, n24, n28, spare2, spare1}
OPTIONAL, -- Need ON periodicBSR-Timer PeriodicBSR-Timer-r12
OPTIONAL, -- Need ON retxBSR-Timer RetxBSR-Timer- r12, ttiBundling
BOOLEAN } OPTIONAL, -- Need ON drx-Config DRX-Config OPTIONAL, --
Need ON timeAlignmentTimerDedicated TimeAlignmentTimer, phr-Config
CHOICE { release NULL, setup SEQUENCE { periodicPHR-Timer
ENUMERATED {sf10, sf20, sf50, sf100, sf200, sf500, sf1000,
infinity}, prohibitPHR-Timer ENUMERATED {sf0, sf10, sf20, sf50,
sf100, sf200, sf500, sf1000}, dl-PathlossChange ENUMERATED {dB1,
dB3, dB6, infinity} } } OPTIONAL, -- Need ON ..., [[
sr-ProhibitTimer-r9 INTEGER (0..7) OPTIONAL -- Need ON ]], [[
mac-MainConfig-v1020 SEQUENCE { sCellDeactivationTimer-r10
ENUMERATED { rf2, rf4, rf8, rf16, rf32, rf64, rf128, spare}
OPTIONAL, -- Need OP extendedBSR-Sizes-r10 ENUMERATED {setup}
OPTIONAL, -- Need OR extendedPHR-r10 ENUMERATED {setup} OPTIONAL --
Need OR } OPTIONAL -- Need ON ]], [[ stag-ToReleaseList-r11
STAG-ToReleaseList- r11 OPTIONAL, -- Need ON stag-ToAddModList-r11
STAG-ToAddModList- r11 OPTIONAL, -- Need ON drx-Config-v1130
DRX-Config-v1130 OPTIONAL -- Need ON ]], [[ e-HARQ-Pattern-r12
BOOLEAN OPTIONAL, -- Need ON dualConnectivityPHR CHOICE { release
NULL, setup SEQUENCE { phr-ModeOtherCG-r12 ENUMERATED {real,
virtual} } } OPTIONAL, -- Need ON logicalChannelSR-Config-r12
CHOICE { release NULL, setup SEQUENCE {
logicalChannelSR-ProhibitTimer-r12 ENUMERATED {sf20, sf40, sf64,
sf128, sf512, sf1024, sf2560, spare1} } } OPTIONAL -- Need ON ]] }
MAC-MainConfigSCell-r11 ::= SEQUENCE { stag-Id-r11 STAG-Id-r11
OPTIONAL, -- Need OP ... } DRX-Config ::= CHOICE { release NULL,
setup SEQUENCE { onDurationTimer ENUMERATED { psf1, psf2, psf3,
psf4, psf5, psf6, psf8, psf10, psf20, psf30, psf40, psf50, psf60,
psf80, psf100, psf200}, drx-InactivityTimer ENUMERATED { psf1,
psf2, psf3, psf4, psf5, psf6, psf8, psf10, psf20, psf30, psf40,
psf50, psf60, psf80, psf100, psf200, psf300, psf500, psf750,
psf1280, psf1920, psf2560, psf0-v1020, spare9, spare8, spare7,
spare6, spare5, spare4, spare3, spare2, spare1},
drx-RetransmissionTimer ENUMERATED { psf1, psf2, psf4, psf6, psf8,
psf16, psf24, psf33}, longDRX-CycleStartOffset CHOICE { sf10
INTEGER(0..9), sf20 INTEGER(0..19), sf32 INTEGER(0..31), sf40
INTEGER(0..39), sf64 INTEGER(0..63), sf80 INTEGER(0..79), sf128
INTEGER(0..127), sf160 INTEGER(0..159), sf256 INTEGER(0..255),
sf320 INTEGER(0..319), sf512 INTEGER(0..511), sf640
INTEGER(0..639), sf1024 INTEGER(0..1023), sf1280 INTEGER(0..1279),
sf2048 INTEGER(0..2047), sf2560 INTEGER(0..2559) }, shortDRX
SEQUENCE { shortDRX-Cycle ENUMERATED { sf2, sf5, sf8, sf10, sf16,
sf20, sf32, sf40, sf64, sf80, sf128, sf160, sf256, sf320, sf512,
sf640}, drxShortCycleTimer INTEGER (1..16) } OPTIONAL -- Need OR }
} DRX-Config-v1130 ::= SEQUENCE { drx-RetransmissionTimer-v1130
ENUMERATED {psf0-v1130} OPTIONAL, --Need OR
longDRX-CycleStartOffset-v1130 CHOICE { sf60-v1130 INTEGER(0..59),
sf70-v1130 INTEGER(0..69) } OPTIONAL, --Need OR
shortDRX-Cycle-v1130 ENUMERATED {sf4-v1130} OPTIONAL --Need OR }
PeriodicBSR-Timer-r12 ::= ENUMERATED { sf5, sf10, sf16, sf20, sf32,
sf40, sf64, sf80, sf128, sf160, sf320, sf640, sf1280, sf2560,
infinity, spare1} RetxBSR-Timer-r12 ::= ENUMERATED { sf320, sf640,
sf1280, sf2560, sf5120, sf10240, spare2, spare1}
STAG-ToReleaseList-r11 ::= SEQUENCE (SIZE (1..maxSTAG-r11)) OF
STAG- Id-r11 STAG-ToAddModList-r11 ::= SEQUENCE (SIZE
(1..maxSTAG-r11)) OF STAG- ToAddMod-r11 STAG-ToAddMod-r11 ::=
SEQUENCE { stag-Id-r11 STAG-Id-r11, timeAlignmentTimerSTAG-r11
TimeAlignmentTimer, ... } STAG-Id-r11::= INTEGER (1..maxSTAG-r11)
-- ASN1STOP
[0398] In step 4720, the base station successfully receiving the SR
schedules the radio resource through which the terminal may
transmit the buffer status report (BSR) to the terminal. If the
radio resource which may transmit the BSR is not scheduled and the
SR prohibit timer expires, the terminal may again transmit the SR.
Further, every time the SR transmission is attempted, an SR_COUNTER
counter value is increased by 1. If the counter value is equal to
dsr-TransMax which is one setting value, the terminal attempts the
random access to the base station. The base station configures the
dsr-TransMax value in the terminal and the dsr-TransMax value has
one of {4, 8, 16, 32, 64}. The BSR is used to inform the base
station how much the terminal has transmission data.
[0399] In step 4725, the terminal uses the allocated radio resource
to transmit the BSR to the base station. In step 4730, the base
station allocates the radio resource to allow the terminal to
transmit the PDCP SDU. In step 4735, the terminal transmits the
data to the base station using the allocated radio resource. In
step 4740, the base station transmits ACK/NACK information on the
data to the terminal. The terminal periodically uses the allocated
SR radio resource to transmit the SR to the base station. As shown
in the following Table 4, the SR radio resource is allocated to the
PUCCH at a period of at least 1 ms and up to 80 ms.
TABLE-US-00005 Terminal 4 SR configuration SR periodicity (ms) SR
subframe offset Index I.sub.SR SR.sub.PERIODICITY N.sub.OFFSET, SR
0-4 5 I.sub.SR 5-14 10 I.sub.SR - 5 15-34 20 I.sub.SR - 15 35-74 40
I.sub.SR - 35 75-154 80 I.sub.SR - 75 155-156 2 I.sub.SR - 155 157
1 I.sub.SR - 157
[0400] In the Release-13 LTE standard technology, the plurality of
serving cells having the PUCCH may be configured. Therefore, the
terminal may also transmit the SR from at least one serving cell in
the uplink.
[0401] FIG. 48 is a diagram illustrating a process of transmitting
SR from a plurality of serving cells having PUCCH.
[0402] Referring to FIG. 48, the PCell has the PUCCH. Therefore, it
is assumed that the PUCCH is additionally configured in one SCell.
In the case, a separate SR radio resource may be allocated to each
PUCCH. It is assumed that two serving cells, that is, the PCell
4800 and one SCell 4815 provide the PUCCH. SR periodicity 4810 of
an SR radio resource 4805 in the PUCCH of the PCell need not to be
the same as SR periodicity 4825 of an SR radio resource 4820 in the
PUCCH of the SCell. Further, offset values of the positions of the
SR radio resources need not be the same.
[0403] If one SR is triggered, the terminal may select one of the
SR radio resources of the respective PUCCHs depending on a
predetermined rule to transmit the SR of the terminal to the base
station. Every time the terminal transmits the SR, the SR_COUNTER
value is increased by 1. Further, after the terminal transmits the
SR, the SR prohibit timer starts. If the SR prohibit timer expires,
the terminal may retransmit the SR again. In the case of FIG. 48,
the SR is transmitted onto the SR radio resource 4805 (4830) and
the SR prohibit timer proceeds and thus is completed (4835 and
4840), and then the new SR may be transmitted again.
[0404] By the way, in this case, there is a need to determine how
to set the SR prohibit timer value. Unlike the related art, the
reason is that two SR periodicity is present. In the present
embodiment, when the plurality of SRs are configured in the
plurality of serving cells having the PUCCH, a method for deriving
an SR prohibit value is proposed.
[0405] If the dedicated D-SR is configured in the PUCCH SCell or
the PCell, the terminal applies one of predetermined rules
enumerated below to determine the sr-ProhibitTimer IE and the SR
periodicity which will be used to the SR prohibit timer value. In
the present embodiment, it is assumed that the sr-ProhibitTimer IE
may be configured in each serving cell having the PUCCH. When the
Sr-ProhibitTimer IE is configured only in one serving cell, a rule
to determine the sr-ProhibitTimer IE and the SR periodicity which
will be used is as follows. [0406] Rule 1-1: The Sr-ProhibitTimer
IE applies the SR periodicity of the configured serving cell to
derive the SR prohibit timer value. For example, when the PUCCH is
configured in the PCell and the PUCCH SCell, if the
Sr-ProhibitTimer IE is configured only in the PCell, the SR
prohibit timer value determined using the SR periodicity of the
Pcell and the Sr-ProhibitTimer IE is applied to both of the PCell
and the PUCCH SCell. [0407] Rule 1-2: If the SR is transmitted from
the serving cell in which the Sr-ProhibitTimer IE is configured,
the rule 1-1 is applied and if the SR is transmitted from the
serving cell in which the Sr-ProhibitTimer IE is not configured,
the SR prohibit timer is not driven. For example, when the PUCCH is
configured in the PCell and the PUCCH SCell, if the
Sr-ProhibitTimer IE is configured only in the PCell, the SR
prohibit timer value determined using the SR periodicity and the
Sr-ProhibitTimer IE of the PCell is applied to the PCell and the SR
prohibit timer is not applied to the PUCCH SCell. [0408] Rule 1-3:
The SR prohibit timer value is determined by using the
sr-ProhibitTimer IE and the SR periodicity of the predetermined
serving cell. If the sr-ProhibitTimer IE is not configured in the
predetermined serving cell, the SR prohibit timer is not driven.
For example, it may be defined that the SR prohibit timer value is
determined by using the sr-ProhibitTimer IE and the SR periodicity
of the PCell or the PUCCH SCell. When the SR prohibit timer value
is determined using the sr-ProhibitTimer IE and the SR periodicity
of the PCell, if the sr-ProhibitTimer IE is configured in the
PCell, the determined SR prohibit timer value is applied to both of
the PCell and the PUCCH Scell and if the sr-ProhibitTimer IE is not
configured in the PCell, the SR prohibit timer value is not applied
to both of the PCell and the PUCCH Scell.
[0409] When the Sr-ProhibitTimer IE is configured in both serving
cells, that is, the PCell and the PUCCH SCell, the rule determining
the sr-ProhibitTimer IE and the SR periodicity which will be used
is as follows. [0410] Rule 2-1: The sr prohibit timer value is
determined using the SR periodicity and the sr-prohibitTimer IE of
the serving cell in which the SR periodicity of the PCell and the
SR periodicity of the PUCCH SCell are short or long. For example,
when the SR periodicity of the PCell is shorter than the SR
periodicity of the PUCCH SCell, if the SR periodicity of the
serving cell having the short SR periodicity and the
sr-prohibitTimer IE are used, the SR prohibit timer value is
determined using the SR periodicity and the sr-prohibitTimer IE of
the PCell to be applied to both of the PCell and the PUCCH SCell
and if the SR periodicity of the serving cell having the long SR
periodicity and the sr-prohibitTimer IE are used, the SR prohibit
timer value is determined using the SR periodicity and the
sr-prohibitTimer IE of the PUCCH SCell to be applied to both of the
PCell and the PUCCH SCell. [0411] Rule 2-2: The SR periodicity and
the sr-prohibitTimer IE of the serving cell to which the SR is
transmitted are applied or the sr-ProhibitTimer IE and the SR
periodicity of the serving cell explicitly instructed by the base
station are applied to determine the SR prohibit timer value. For
example, if the SR is transmitted just before from the PCell, the
SR periodicity and the sr-prohibitTimer IE of the PCell are used to
determine the SR prohibit timer value to be applied to both of the
PCell and the PUCCH SCell or if the base station is instructed to
use the sr-ProhibitTimer IE and the SR periodicity of the PCell,
the SR prohibit timer value is determined using the SR periodicity
and the sr-prohibitTimer IE of the PCell to be applied to both of
the PCell and the PUCCH SCell.
[0412] FIG. 49 is a flow chart illustrating a terminal operation in
the present embodiment.
[0413] Referring to FIG. 49, in step 4900, the terminal determines
whether the PUCCH SCell is configured. If the PUCCH SCell is not
configured, only the PCell is present in the serving cell which may
transmit the SR. Therefore, in step 4905, the SR transmission
process according to the related art is performed.
[0414] If the PUCCH SCell is configured in the terminal, the SR may
be transmitted from even the PUCCH SCell. In step 4910, the
terminal determines whether the sr-ProhibitTimer IE is configured
only in one of the PCell and the PUCCH SCell. Independent of
whether the IE is configured, the terminal may transmit the SR to
both of the PCell and the PUCCH SCell. If the IE is configured only
in one cells, in step 4915, the terminal selects at least one of
the proposed rules 1-1, 1-2, and 1-3 to derive the SR prohibit
timer value to be applied. If the IE is configured in all of the
two cells, in step 4920, at least one of the proposed rules 2-1 and
2-2 is selected and thus the SR prohibit timer value to be applied
is derived.
[0415] FIG. 50 illustrates the terminal apparatus which may perform
the present embodiment.
[0416] Referring to FIG. 50, the terminal transmits and receives
data, etc., to and from an upper layer 5005, transmits and receives
control messages through a control message processor 5007, upon the
transmission, multiplexes data using a multiplexer 5009 according
to a control of a controller 5003 and then transmits (5001) the
data through the transmitter, and upon the reception, receives
(5009) a physical signal to the receiver according to the control
of the controller 5001, demultiplexes the received signal by a
multiplexer and demultiplexer 5003, and then transmits it to the
upper layer 5005 or a control message processor 5007 according to
the message information.
[0417] In particular, the controller 5009 determines whether the
PUCCH SCell is configured therein according to the present
embodiment, and if so, may control the multiplexer, demultiplexer
5003 and the transceiver 5001, or the like to transmit the SR
according to the related art. Further, if the PUCCH SCell is
configured, the SR prohibit timer value to be applied is derived
depending on one of the proposed rules according whether the
sr-ProhibitTimer IE is configured in one cell or both of the two
cells and may control the multiplexer, demultiplexer 5003 and the
transceiver 5001, or the like to transmit the SR according to the
value.
[0418] The detailed description of the present invention has been
described in connection with the detailed method and apparatus,
various modifications and variations can be made without departing
from the scope of the present embodiment. Therefore, the scope of
the present embodiment should be not construed as being limited to
the described content but be defined by the appended claims as well
as equivalents thereto.
Sixth Embodiment
[0419] The present embodiment relates to a wireless communication
system, and more particularly, to a licensed assisted access using
an unlicensed frequency band with the help of a licensed band in a
long term evolution (LTE) system.
[0420] In recent years, wireless communication technologies are
rapidly developing and communication system technologies has
steadily been developed accordingly. Among those, a system
spotlighted as a fourth-generation mobile communication technology
is the very LTE system. In the LTE system, various technologies
have been introduced to meet the ever-increasing demand for
traffic. The introduced technology is a carrier aggregation (CA).
Unlike using only one carrier for communication between user
equipment (may be used together with UE, terminal, a moving
terminal, etc.) and the base station in the existing communication,
the CA technology additionally uses a main carrier and one or a
plurality of sub-carriers to surprisingly increase a transmission
amount as much as the number of sub-carriers. Meanwhile, in the
LTE, a cell within the base station using the main carrier is
called a primary cell (PCell) and the sub-carrier is called a
secondary cell (SCell). The number of PCells is only one and the
number of SCells (based on LTE Release 11) may be up to four.
However, the number of SCells may be added in the future.
[0421] Meanwhile, the LTE system is a system performing
communication using a licensed band frequency allocated to common
carriers from government, or the like. However, to meet the
recently ever-increasing demand for traffic, a technical discussion
to apply the LTE technology to the unlicensed band using wireless
LAN, Bluetooth, or the like has been conducted, which is called a
licensed-assisted access (hereinafter, called LAA) technology. When
the LAA technology is applied to the CA technology, a scenario
using the unlicensed band frequency by allowing the PCell to use a
licensed band frequency and the SCell to use the LAA technology may
be considered. As described above, the SCell using the unlicensed
band is called an unlicensed SCell (U-SCell).
[0422] Meanwhile, when the terminal performsthe uplink transmission
using the U-SCell, various problems may occur. For example, the
unlicensed band may be used by the existing heterogeneous system
like the wireless LAN, or the like or the in-band may be operated
by the U-SCell of other carriers. As a result, data transmitted to
the U-SCell are delayed due to interference or a transmission error
may occur, and as a result the terminal needs to transmit the
uplink data on the U-SCell in consideration of the problem.
[0423] The present invention proposes to solve the above problem,
and an object of the present invention is to provide an apparatus
and a method for transmitting uplink data to an unlicensed band
when an LAA technology is used in a wireless mobile communication
system.
[0424] When the data are transmitted to the uplink using the LAA
technology in the wireless communication system, the cell to be
transmitted is selected based on the nature to data to be
transmitted and it is determined whether to start the SR
transmission procedure according to a kind of cells to which the
uplink resource is allocated to allow the terminal to perform the
uplink transmission for the important message without a delay.
[0425] Hereinafter, an operation principle of the present
embodiment will be described in detail with reference to the
accompanying drawings. Hereinafter, when it is determined that the
detailed description of the known art related to the present
embodiment may obscure the gist of the present embodiment, the
detailed description thereof will be omitted. Further, the
following terminologies are defined in consideration of the
functions in the present embodiment and may be construed in
different ways by the intention of users and operators. Therefore,
the definitions thereof should be construed based on the contents
throughout the specification.
[0426] Hereinafter, the present embodiment will describe a
technology for providing a multi-link in a wireless communication
system.
[0427] Terms identifying an access node, terms indicating network
entity, terms indicating messages, terms indicating an interface
between network entities, terms indicating various types of
identification information, and so on that are used in the
following description are exemplified for convenience of
explanation. Accordingly, the present invention is not limited to
terms to be described below and other terms having the equivalent
technical meaning may be used.
[0428] Hereafter, for convenience of explanation, the present
invention uses terms and names defined in the 3rd generation
partnership project long term evolution (3GPP LTE). However, the
present invention is not limited to the terms and names but may
also be identically applied to the system according to other
standards.
[0429] FIG. 51 is a diagram illustrating a structure of the LTE
system to which the present invention is applied.
[0430] Referring to FIG. 51, a radio access network of the LTE
system is configured to include next-generation base stations
(evolved node B, hereinafter, ENB, Node B, or base station) 5105,
5110, 5115, and 5120, a mobility management entity (MME) 5125, and
a serving-gateway (S-GW) 5130. User equipment (hereinafter, UE or
terminal) 135 is connected to an external network through the ENBs
5105, 5110, 5115, and 5120 and the S-GW 5130.
[0431] In FIG. 1, the ENBs 5105, 5110, 5115, and 5120 correspond to
the existing node B of a UMTS system. The ENB is connected to the
UE 5135 through a radio channel and performs more complicated role
than the existing node B. In the LTE system, in addition to a
real-time service like a voice over Internet protocol (VoIP)
through the Internet protocol, all the user traffics are served
through a shared channel and therefore an apparatus for collecting
and scheduling status information such as a buffer status, an
available transmission power status, and a channel state of the UEs
is required. Here, the ENBs 5105, 5110, 5115, and 5120 take charge
of the collecting and scheduling.
[0432] One ENB generally controls a plurality of cells. For
example, to implement a transmission rate of 100 Mbps, the LTE
system uses, as a radio access technology, orthogonal frequency
division multiplexing (OFDM) in, for example, a bandwidth of 20
MHz. Further, an adaptive modulation & coding (AMC) determining
a modulation scheme and a channel coding rate depending on a
channel status of the terminal is applied. The S-GW 5130 is an
apparatus for providing a data bearer and generates or removes the
data bearer according to the control of the MME 5145. The MME is an
apparatus for performing a mobility management function for the
terminal and various control functions and is connected to a
plurality of base stations.
[0433] FIG. 52 is a diagram illustrating a radio protocol structure
in an LTE system to which the present invention is applied.
[0434] Referring to FIG. 52, the radio protocol of the LTE system
consists of packet data convergence protocols (PDCPs) 5205 and
5240, radio link controls (RLCs) 5210 and 5235, and medium access
controls (MMCs) 5215 and 5230 in the terminal and the ENB,
respectively.
[0435] The PDCPs 5205 and 5240 serve to perform operations such as
compression/recovery of an IP header and radio link controls (RLC)
5210 and 5235 reconfigures a PDCP packet data unit (PDU) at an
appropriate size. The MACs 5215 and 5230 are connected to several
RLC layer apparatuses configured in one terminal and performs an
operation of multiplexing RLC PDUs into an MAC PDU and
demultiplexing the RLC PDUs from the MAC PDU.
[0436] Physical layers 5220 and 5225 perform an operation of
channel-coding and modulating upper layer data, making them as an
OFDM symbol, and transmitting them to the radio channel or an
operation of demodulating the OFDM symbol received through the
radio channel, channel-decoding it, and transmitting it to an upper
layer. Further, the physical layer uses an HARQ (Hybrid ARQ) for
additional error correction and a receiving end transmits whether
to receive the packet transmitted from a transmitting end as 1 bit.
This is called HARQ ACK/NACK information. The downlink HARQ
ACK/NACK information on the uplink transmission may be transmitted
through a physical hybrid-ARQ indicator channel (PHICH) physical
channel and the uplink HARQ ACK/NACK information on the downlink
transmission may be transmitted through a physical uplink control
channel (PUCCH) or physical uplink shared channel (PUSCH) physical
channel.
[0437] The physical layer of the LTE system has a radio frame
structure having 10 ms for downlink and uplink data transmission
and is provided with two types of radio frames. [0438] Type 1:
Applied to FDD (Frequency Division Duplex) [0439] Type 2: Applied
to TDD (Time Division Duplex)
[0440] In the two types, one radio frame has a length of 10 ms and
each type consists of 10 subframes having a length of 1 ms, in
which the subframe of 1 ms is called 1 transmission time interval
(TTI). That is, one radio frame consists of a total 10 of subframes
from subframe No. 0 to subframe No. 9.
[0441] In the case of the FFD, the uplink and the downlink are
separated using different frequency regions and the uplink and the
downlink each consist of 10 subframes.
[0442] In the case of the TDD, as each subframe within one radio
frame is divided into a downlink subframe, an uplink subframe, and
a special subframe according to the configuration and the special
frame is again divided into a downlink pilot time slot (DwPTS), a
guard period (GP), and an uplink pilot time slot (UpPTS) and serves
as a switching point between the downlinks. The lengths of the
DwPTS, the GP, and the UpPTS, respectively, may be set but the sum
thereof has a length of 1 ms like other subframes.
[0443] FIG. 53 is a diagram illustrating a message flow between the
terminal and the base station when a method for transmitting an
uplink to an unlicensed band according to the present embodiment is
applied.
[0444] In FIG. 53, if is assumed that the base station is a base
station 5303 managing both of the licensed band and the unlicensed
band and a scenario to additionally configure the licensed band as
the PCell 5305 and the unlicensed band as the SCell 5307 is
assumed. The terminal 5301 tries to access the cell 5305 using the
licensed band of the base station 5303 to configure the radio
resource connection (RRC) to the base station (5311). The
connection configuration means that the terminal is connected to
the base station to transmit and receive data and to configure the
connection, the connection is configured using a message of an RRC
layer. In more detail, the terminal transmits an
RRCConnectionRequest message to the base station to request the
connection to the base station and the base station receiving the
request transmits an RRCConnectionSetup message to the terminal to
configure the connection. In this case, the terminal enters an RRC
connection (RRC_CONNECTED) in an RRC idle (RRC_IDLE) state. The
terminal receiving the RRCConnectionSetup message transmits an
RRCConnectionSetupComplete message to the base station to
acknowledge that the RRCConnectionSetup is received.
[0445] Next, the terminal receives the control message configuring
the SCell in which at least one uplink transmission is configured
from the base station (5313). This means that the base station may
configure the terminal to transmit the uplink data to the SCell
5307 using the unlicensed band in addition to the PCell 5305 which
is originally communicating. The control message may use an
RRCConnectionReconfiguration message of the RRC layer. Next, the
terminal transmits a message acknowledging the control message
(5315). As the acknowledgement control message, the
RRCConnectionReconfigurationComplete message may be used.
[0446] Next, the terminal receives an instruction from the base
station to activate the corresponding SCell so that it may actually
use the SCell 5307 configured to perform up to the uplink
transmission (5317). The instruction is transmitted using an
activation/deactivation MAC CE among a control element (CE) used by
the foregoing MAC layer. As a result, the terminal activates a
SCell 5307 newly configured to perform up to the uplink
transmission (5319). After the activation, the terminal transmits a
preamble specially designed to mach the uplink synchronization onto
the corresponding SCell to the base station to the base station to
thereby match the base station and the uplink transmission
timing.
[0447] Next, the terminal receives uplink resource allocation
information instructing new data transmission from the base station
(5321). The resource may also be allocated to the uplink of the
PCell or the uplink of the SCell. Even though the resource is
allocated to the uplink of the SCell 5307, the resource may be
allocated from the PCell (in the case of FIG. 53) or may be
allocated from the SCell (not illustrated in FIG. 53).
[0448] The terminal receiving the uplink resource allocation
information determines the transmission method according to whether
the uplink resource is allocated to the PCell 5305 (or licensed
band SCell), whether the uplink resource is allocated to the SCell
5307 using the unlicensed band, and a kind of data to be
transmitted by the terminal (5331). The detailed method will be
described below. Next, the terminal transmits the PCell 5305 of the
licensed band and the SCell 5307 of the non-licensed band (5333 and
5335).
[0449] The data to be transmitted by the terminal may be user data
or may be control data generated at the foregoing MAC layer. An
example of the user data may include a voice packet for phone
communication, or the like or an Internet packet for data
communication, or the like and the corresponding packet is received
from the upper layer of the terminal at the MAC layer, which is
called an MAC service data unit (SDU) at the MAC layer. Further, an
example of the control data generated at the foregoing MAC layer
may include the MAC CE message and the more detailed example of the
MAC CE generated by the terminal may include a buffer status report
(hereinafter, BSR) MAC CE, a power headroom (hereinafter, PHR) MAC
CE, or the like.
[0450] The BSR MAC CE is used to report the buffer status storing
data to be transmitted to uplink of the terminal and the base
station receiving the present information understands the buffer
status of the terminal to allocate the uplink resource to the
corresponding terminal. The BSR is divided as follows according to
the condition in which the transmission is triggered. [0451] First
type: Regular BSR [0452] BSR transmitted when the BSR
retransmission timer retxBSR-Timer expires, when the terminal
includes data that may be transmitted to any logical channel/radio
bearer (RB) belonging to a logical channel group (LCG) [0453] BSR
transmitted when the data to be transmitted from the upper layer
(RLC or PDCP layer) to the logical channel/radio bearer belonging
to the LCG are generated and the data have priority higher than the
logical channel/wireless bearer belonging to any LCG [0454] BSR
transmitted when the data to be transmitted from the upper layer
(RLC OR PDCP layer) to the logical channel/radio bearer belonging
to the LCG are generated and there are no data even in any LCG
other than the data [0455] Second type: Periodic BSR [0456] BSR
transmitted when a periodic BSR-timer (periodicBSR-Timer) set in
the terminal expires [0457] Third type: Padding BSR [0458] BSR
transmitted when the uplink resource is allocated and the padding
bit filling the space after the data are transmitted is equal to or
larger than the sum of the size of the BSR MAC CE and the side of
the sub-header of the BSR MAC CE [0459] When the packets are
present in the buffers of the plurality of LCGs, transmit truncated
BSR
[0460] In addition, there are Silelink BSR, padding Sidelink BSR,
or the like which may be used in terminal-to-terminal
communication.
[0461] Further, the PHR MAC CE is used to allow the terminal to
report available power information which may be used for the uplink
transmission. The PHR message may include a general PHR, an
extended PHR used in the CA system, a DC PHR used in a dual
connectivity technology which is a technology of allowing one
terminal to simultaneously use the plurality of base stations, or
the like.
[0462] Like step 5321, the terminal receives the uplink resource
allocation from the base station and if the resource allocation is
instructed to use the SCell using the unlicensed band, the resource
allocation is transmitted in a priority order of the subsequent
data. [0463] MAC SDU generated in another radio bearer other than a
signaling radio bearer (SRB) or MAC SDU generated in a bearer in
which an unlicensed band transmission from the base station is
allowedTruncated BSR. [0464] Padding BSR, padding Sidelink BSR
Further, like the step 5321, the terminal receives the uplink
resource allocation from the base station and if the resource
allocation is instructed to use the PCell or the licensed band
SCell using the unlicensed band, the resource allocation is
transmitted in a priority order of the subsequent data. [0465] MAC
SDU generated in SRB [0466] MAC SDU generated in DRB [0467] Regular
BSR, Periodic BSR, Silelink BSR [0468] PHR, extended PHR, DC PHR
[0469] Padding BSR, padding Sidelink BSR
[0470] This is to prevent the important message (for example,
control message of the RRC layer) for communication with the base
station from being transmitted to the unlicensed band. Therefore,
the terminal selects the cell to be transmitted according to a kind
of cell to which the uplink resource is allocated and a nature of
data to be transmitted to perform the uplink transmission of the
important message without a delay.
[0471] FIG. 54 is a diagram illustrating an operation order of the
terminal when the method for transmitting an uplink to an
unlicensed band according to the present invention is applied.
[0472] Referring to FIG. 54, the terminal configures the RRC
connection in the licensed band LTE serving cell (5403). In more
detail, the terminal transmits an RRCConnectionRequest message to
the base station to request the connection to the base station and
the base station receiving the request transmits an
RRCConnectionSetup message to the terminal to configure the
connection. In this case, the terminal enters an RRC connection
(RRC_CONNECTED) in an RRC idle (RRC_IDLE) state. The terminal
receiving the RRCConnectionSetup message transmits an
RRCConnectionSetupComplete message to the base station to
acknowledge that the RRCConnectionSetup is received.
[0473] Next, the terminal receives the control message configuring
the SCell in which at least one uplink transmission is configured
from the base station (5405). This means that the terminal is
configured to additionally transmit the uplink data to the SCell
using the unlicensed band.
[0474] Next, the terminal receive the activation/deactivation MAC
CE from the base station to receive an instruction to activate the
SCell to actually use the SCell configured to perform up to the
uplink transmission and activates the corresponding SCell
(5407).
[0475] Next, the terminal receives the uplink resource allocation
information instructing new data transmission from the base station
and determines whether the corresponding resource is allocated to
the PCell or the uplink of the licensed band SCell or whether the
corresponding resource is allocated to the uplink of the unlicensed
band SCell (5411).
[0476] Further, the terminal determines whether the packet to be
transmitted is the MAC SDU or the MAC CE (5413). In the case of the
MAC SDU, the terminal determines whether the MAC SDU is a first MAC
SDU or a second MAC SDU (5421).
[0477] The first MAC SDU has the following MAC SDU. [0478] MAC SDU
generated in another radio bearer other than the signaling radio
bearer (SRB) or MAC SDU generated in the bearer in which an
unlicensed band transmission from the base station is allowed. The
second MAC SDU has the following MAC SDU. [0479] MAC SDU generated
SRB [0480] MAC SDU generated in DRB in which transmission is
allowed only to the licensed band.
[0481] If the MAC SDU corresponds to the first MAC SDU, the
terminal transmits the corresponding MAC SDU using the allowable
transmission resource without differentiating the serving cell
(5425). On the other hand, if the MAC SDU corresponds to the second
MAC SDU, the terminal transmits the corresponding MAC SDU only
through the serving cell using the licensed band (5427).
[0482] In the case of the MAC CE, the terminal determines whether
the MAC CE is a first MAC CE or a second MAC CE (5423).
[0483] The first MAC CE has the following MAC CE. [0484] Truncated
BSR [0485] Padding BSR, padding Sidelink BSR
[0486] The second MAC CE has the following MAC CE. [0487] Regular
BSR, Periodic BSR, Silelink BSR [0488] PHR, extended PHR, DC PHR
[0489] Padding BSR, padding Sidelink BSR
[0490] If the MAC CE corresponds to the first MAC CE, the terminal
transmits the corresponding MAC CE using the allowable transmission
resource without differentiating the serving cell (5425). On the
other hand, if the MAC CE corresponds to the second MAC CE, the
terminal transmits the corresponding MAC CE only through the
serving cell using the licensed band (5427).
[0491] Therefore, the terminal selects the cell to be transmitted
according to a kind of cell to which the uplink resource is
allocated and a nature of data to be transmitted to perform the
uplink transmission of the important message without a delay.
[0492] FIG. 55 is a diagram illustrating the operation order of the
terminal when the method for transmitting a scheduling request
according to the present invention is applied.
[0493] Referring to FIG. 55, in the LTE system, the scheduling
request (SR) is used when the terminal request the base station to
perform new transmission to the uplink. As a result, when the new
data to be transmitted from the terminal to the base station is
generated, the terminal triggers the SR (5503). If the SR is
triggered, the base station determines whether the uplink resource
allocated to the corresponding terminal is present for each TTI
(5505). If present, it is determined whether the corresponding
allocated uplink resource is allocated to the licensed band (that
is, PCell or SCell using the licensed band) or allocated to the
SCell using the unlicensed band (5507). If the resource allocation
is allocated to use the serving cell using the licensed band, it is
determined whether the corresponding resource is transmitted
including the BSR for data triggering the SR (5509) and if the
resource allocation is transmitted including the BSR, the SR
transmission is canceled and procedure 5111 ends.
[0494] Meanwhile, in step 5505, when the uplink resource allocation
received from the base station is not present or in step 5507, even
though the allocated resource is present, when the allocated
resource is a resource allocated to the unlicensed SCell, the
terminal determines whether the resource transmitting the SR is
present in the physical uplink control channel (PUCCH) (5513). If
the SR resource configured from the base station is present, the
terminal performs an attempt to transmit the SR to the PUCCH (5515)
and if the SR resource configured from the base station is not
present, for the terminal to transmit the BSR, the terminal
performs the random access to the base station and cancel the SR
(5517) and ends a procedure.
[0495] By doing so, even when the uplink resource is allocated, the
terminal may start the SR transmission procedure to the PUCCH when
the allocated resource is allocated to the serving cell using the
unlicensed band.
[0496] FIG. 56 is a block diagram illustrating an internal
structure of the terminal according to an embodiment of the present
invention.
[0497] Referring to FIG. 56, the terminal transmits and receives
data, or the like to and from an upper layer 5610 and transmits and
receives control messages through a control message processor 5615.
Further, when the terminal transmits a control signal or data to
the base station, the terminal performs multiplexing through a
multiplexer and demultiplexer 5605 according to a control of a
controller 5620 and then transmits data through a transceiver 5600.
On the other hand, when the terminal receives data, a transceiver
5600 receives a physical signal according to the control of the
controller 5620 and then a multiplexer and demultiplexer 5605
demultiplexes the received signal and the terminal transmits the
received signal to the upper layer 5610 or the control message
processor 5615 according to the message information. For example,
the messages of foregoing RRC layer are a control message.
[0498] Meanwhile, in FIG. 56, it is described that the terminal is
configured of a plurality of blocks and each block performs
different functions, which is only embodiment and therefore is not
necessarily limited thereto. For example, the controller 5620
itself may also perform the function performed by the multiplexer
and demultiplexer 5605.
[0499] In the present embodiment, the terminal receives an on
control message transmitted from the base station to configure the
unlicensed SCeLL and determines whether to transmit data depending
on the respective kinds of serving cells according to the received
resource allocation information and a kind of generated data.
[0500] The methods according to the embodiments described in claims
or specification of the present embodiment may be implemented in
hardware, software, or a combination of hardware and software.
[0501] When the methods are implemented in the software, a computer
readable storage medium storing at least one program (software
module) may be provided. At least one programs stored in the
computer readable storage medium is configured to be executed by at
least one processor within a device. At least one program includes
instructions that execute the methods according to the embodiments
described in the claims or specification of the present
invention.
[0502] The program (software module, software) may be stored a
random access memory, a non-volatile memory including a flash
memory, a read only memory (ROM), an electrically erasable
programmable read only memory (EEPROM), a magnetic disc storage
device, a compact disc-ROM (CD-ROM), digital versatile discs (DVDs)
or other types of optical storage apparatuses, and a magnetic
cassette. Alternatively, the programs may be stored in the memory
that is configured of a combination of some or all of the memories.
Further, each memory may also be included in plural.
[0503] Further, the program may be stored in an attachable storage
device that may be accesses through communication networks such as
Internet, an intranet, a local area network (LAN), a wide LAN
(WLAN), and a storage area network (SAN) or a communication network
configured in a combination thereof. The storage device may access
an apparatus performing the embodiment of the present invention
through an external port. Further, a separate storage device on the
communication network may also access the apparatus performing the
embodiment of the present invention.
[0504] In the of the present embodiments, components included in
the present invention are represented by a singular number or a
plural number according to the detailed embodiment as described
above. However, the expressions of the singular number or the
plural number are selected to meet the situations proposed for
convenience of explanation and the present invention is not limited
to the single component or the plural components and even though
the components are represented in plural, the component may be
configured in a singular number or even though the components are
represented in a singular number, the component may be configured
in plural.
[0505] While the present invention has been described in connection
with the exemplary embodiments thereof, various modifications and
variations can be made without departing from the scope of the
present invention. Therefore, the scope of the present invention
should be not construed as being limited to the described exemplary
embodiments but be defined by the appended claims as well as
equivalents thereto.
* * * * *