U.S. patent application number 14/904355 was filed with the patent office on 2016-05-26 for method for triggering a burffer status reporting and a device therefor.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is LG ELECTRONICS INC.. Invention is credited to Sunyoung LEE, Youngdae LEE, Sungjun PARK, Seungjune YI.
Application Number | 20160150440 14/904355 |
Document ID | / |
Family ID | 52393523 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160150440 |
Kind Code |
A1 |
LEE; Sunyoung ; et
al. |
May 26, 2016 |
METHOD FOR TRIGGERING A BURFFER STATUS REPORTING AND A DEVICE
THEREFOR
Abstract
The present invention relates to a wireless communication
system. More specifically, the present invention relates to a
method and a device for triggering a buffer status reporting in the
wireless communication system, the method comprising: calculating
an amount of first DAT when the first data is arrived in a protocol
entity, wherein the amount of first DAT is less than a threshold;
calculating an amount of second DAT when the second data is arrived
in the protocol entity, wherein the second data is arrived after
the first data is arrived in the protocol entity; and triggering a
buffer status report if the amount of second DAT is more than the
threshold.
Inventors: |
LEE; Sunyoung; (Seoul,
KR) ; YI; Seungjune; (Seoul, KR) ; LEE;
Youngdae; (Seoul, KR) ; PARK; Sungjun; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
|
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
52393523 |
Appl. No.: |
14/904355 |
Filed: |
July 21, 2014 |
PCT Filed: |
July 21, 2014 |
PCT NO: |
PCT/KR2014/006594 |
371 Date: |
January 11, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61858621 |
Jul 26, 2013 |
|
|
|
Current U.S.
Class: |
455/422.1 |
Current CPC
Class: |
H04W 76/27 20180201;
H04W 24/02 20130101; H04W 24/10 20130101; H04W 72/1284 20130101;
H04W 28/0278 20130101; H04B 7/022 20130101 |
International
Class: |
H04W 28/02 20060101
H04W028/02; H04W 24/10 20060101 H04W024/10 |
Claims
1. A method for a user equipment (UE) operating in a wireless
communication system comprising a first base station (BS) and a
second BS, the method comprising: calculating an amount of first
DAT when the first data is arrived in a protocol entity, wherein
the amount of first DAT is less than a threshold; calculating an
amount of second DAT when the second data is arrived in the
protocol entity, wherein the second data is arrived after the first
data is arrived in the protocol entity; and triggering a buffer
status report if the amount of second DAT is more than the
threshold.
2. The method according to claim 1, the method further comprising:
setting an amount of DAT for a first logical channel as the
calculated amount of first DAT and an amount of DAT for a second
logical channel as `zero`, if the amount of first DAT is less than
the threshold, wherein the first logical channel is for the first
BS and the second logical channel is for the second BS.
3. The method according to claim 2, the method further comprising:
dividing the calculated amount of second DAT into the amount of DAT
for the first logical channel and the amount of DAT for the second
logical channel based on ratio if the amount of second DAT is equal
to or more than the threshold.
4. The method according to claim 1, wherein the buffer status
report is transmitted to the second BS.
5. The method according to claim 1, the method further comprising:
receiving the threshold from at least the first BS or the second
BS.
6. The method according to claim 1, wherein the protocol entity is
a Packet Data Convergence Protocol (PDCP) entity.
7. The method according to claim 6, wherein PDCP entity has two
Radio Link Control (RLC) entities and two Medium Access Control
(MAC) entities for one logical channel.
8. A user equipment (UE) operating in a wireless communication
system comprising a first base station (BS) and a second BS, the UE
comprising: an RF (radio frequency) module; and a processor
configured to control the RF module, wherein the processor is
configured to calculate an amount of first DAT when the first data
is arrived in a protocol entity, wherein the amount of first DAT is
less than a threshold, to calculate an amount of second DAT when
the second data is arrived in the protocol entity, wherein the
second data is arrived after the first data is arrived in the
protocol entity, and to trigger a buffer status report if the
amount of second DAT is more than the threshold.
9. The UE according to claim 8, wherein the processor is further
configured to set an amount of DAT for a first logical channel as
the calculated amount of first DAT and an amount of DAT for a
second logical channel as `zero`, if the amount of first DAT is
less than the threshold, wherein the first logical channel is for
the first BS and the second logical channel is for the second
BS.
10. The UE according to claim 9, wherein the processor is further
configured to divide the calculated amount of second DAT into an
amount of DAT for the first logical channel and an amount of DAT
for the second logical channel based on ratio if the amount of
second DAT is equal to or more than the threshold.
11. The UE according to claim 8, wherein the buffer status report
buffer status report is transmitted to the second BS.
12. The UE according to claim 8, wherein the processor is further
configured to receive the threshold from at least the first BS or
the second BS.
13. The UE according to claim 8, wherein the protocol entity is a
Packet Data Convergence Protocol (PDCP) entity.
14. The UE according to claim 13, wherein PDCP entity has two Radio
Link Control (RLC) entities and two Medium Access Control (MAC)
entities for one logical channel.
Description
TECHNICAL FIELD
[0001] The present invention relates to a wireless communication
system and, more particularly, to a method for triggering a buffer
status reporting and a device therefor.
BACKGROUND ART
[0002] As an example of a mobile communication system to which the
present invention is applicable, a 3rd Generation Partnership
Project Long Term Evolution (hereinafter, referred to as LTE)
communication system is described in brief.
[0003] FIG. 1 is a view schematically illustrating a network
structure of an E-UMTS as an exemplary radio communication system.
An Evolved Universal Mobile Telecommunications System (E-UMTS) is
an advanced version of a conventional Universal Mobile
Telecommunications System (UMTS) and basic standardization thereof
is currently underway in the 3GPP. E-UMTS may be generally referred
to as a Long Term Evolution (LTE) system. For details of the
technical specifications of the UMTS and E-UMTS, reference can be
made to Release 7 and Release 8 of "3rd Generation Partnership
Project; Technical Specification Group Radio Access Network".
[0004] Referring to FIG. 1, the E-UMTS includes a User Equipment
(UE), eNode Bs (eNBs), and an Access Gateway (AG) which is located
at an end of the network (E-UTRAN) and connected to an external
network. The eNBs may simultaneously transmit multiple data streams
for a broadcast service, a multicast service, and/or a unicast
service.
[0005] One or more cells may exist per eNB. The cell is set to
operate in one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20
MHz and provides a downlink (DL) or uplink (UL) transmission
service to a plurality of UEs in the bandwidth. Different cells may
be set to provide different bandwidths. The eNB controls data
transmission or reception to and from a plurality of UEs. The eNB
transmits DL scheduling information of DL data to a corresponding
UE so as to inform the UE of a time/frequency domain in which the
DL data is supposed to be transmitted, coding, a data size, and
hybrid automatic repeat and request (HARM)-related information. In
addition, the eNB transmits UL scheduling information of UL data to
a corresponding UE so as to inform the UE of a time/frequency
domain which may be used by the UE, coding, a data size, and
HARQ-related information. An interface for transmitting user
traffic or control traffic may be used between eNBs. A core network
(CN) may include the AG and a network node or the like for user
registration of UEs. The AG manages the mobility of a UE on a
tracking area (TA) basis. One TA includes a plurality of cells.
[0006] Although wireless communication technology has been
developed to LTE based on wideband code division multiple access
(WCDMA), the demands and expectations of users and service
providers are on the rise. In addition, considering other radio
access technologies under development, new technological evolution
is required to secure high competitiveness in the future. Decrease
in cost per bit, increase in service availability, flexible use of
frequency bands, a simplified structure, an open interface,
appropriate power consumption of UEs, and the like are
required.
DISCLOSURE
Technical Problem
[0007] An object of the present invention devised to solve the
problem lies in a method and device for a method for triggering a
buffer status reporting. The technical problems solved by the
present invention are not limited to the above technical problems
and those skilled in the art may understand other technical
problems from the following description.
Technical Solution
[0008] The object of the present invention can be achieved by
providing a method for operating by an apparatus in wireless
communication system, the method comprising; calculating an amount
of first DAT when the first data is arrived in a protocol entity,
wherein the amount of first DAT is less than a threshold;
calculating an amount of second DAT when the second data is arrived
in the protocol entity, wherein the second data is arrived after
the first data is arrived in the protocol entity; and triggering a
buffer status report if the amount of second DAT is more than the
threshold.
[0009] In another aspect of the present invention provided herein
is an apparatus in the wireless communication system, the apparatus
comprising: an RF (radio frequency) module; and a processor
configured to control the RF module, wherein the processor is
configured to calculate an amount of first DAT when the first data
is arrived in a protocol entity, wherein the amount of first DAT is
less than a threshold, to calculate an amount of second DAT when
the second data is arrived in the protocol entity, wherein the
second data is arrived after the first data is arrived in the
protocol entity, and to trigger a buffer status report if the
amount of second DAT is more than the threshold.
[0010] Preferably, the method further comprises: setting an amount
of DAT for a first logical channel as the calculated amount of
first DAT and an amount of DAT for a second logical channel as
`zero`, if the amount of first DAT is less than the threshold,
wherein the first logical channel is for the first BS and the
second logical channel is for the second BS.
[0011] Preferably, the method further comprises: dividing the
calculated amount of second DAT into the amount of DAT for the
first logical channel and the amount of DAT for the second logical
channel based on ratio if the amount of second DAT is equal to or
more than the threshold.
[0012] Preferably, wherein the buffer status report is transmitted
to the second BS.
[0013] Preferably, the method further comprises: receiving the
threshold from at least the first BS or the second BS.
[0014] Preferably, wherein the protocol entity is a Packet Data
Convergence Protocol (PDCP) entity.
[0015] Preferably, wherein PDCP entity has two Radio Link Control
(RLC) entities and two Medium Access Control (MAC) entities for one
logical channel.
[0016] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
Advantageous Effects
[0017] According to the present invention, triggering a buffer
status reporting can be efficiently performed in a wireless
communication system. Specifically, the UE can calculate each
amount of data available for transmission to each base station and
trigger the buffer status reporting in dual connectivity
system.
[0018] It will be appreciated by persons skilled in the art that
that the effects achieved by the present invention are not limited
to what has been particularly described hereinabove and other
advantages of the present invention will be more clearly understood
from the following detailed description taken in conjunction with
the accompanying drawings.
DESCRIPTION OF DRAWINGS
[0019] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention.
[0020] FIG. 1 is a diagram showing a network structure of an
Evolved Universal Mobile Telecommunications System (E-UMTS) as an
example of a wireless communication system;
[0021] FIG. 2A is a block diagram illustrating network structure of
an evolved universal mobile telecommunication system (E-UMTS), and
FIG. 2B is a block diagram depicting architecture of a typical
E-UTRAN and a typical EPC;
[0022] FIG. 3 is a diagram showing a control plane and a user plane
of a radio interface protocol between a UE and an E-UTRAN based on
a 3rd generation partnership project (3GPP) radio access network
standard;
[0023] FIG. 4 is a diagram of an example physical channel structure
used in an E-UMTS system;
[0024] FIG. 5 is a diagram for carrier aggregation;
[0025] FIG. 6 is a conceptual diagram for dual connectivity between
a Master Cell Group (MCG) and a Secondary Cell Group (SCG);
[0026] FIG. 7a is a conceptual diagram for C-Plane connectivity of
base stations involved in dual connectivity, and FIG. 7b is a
conceptual diagram for U-Plane connectivity of base stations
involved in dual connectivity;
[0027] FIG. 8 is a conceptual diagram for radio protocol
architecture for dual connectivity;
[0028] FIG. 9 is a diagram for a general overview of the LTE
protocol architecture for the downlink;
[0029] FIG. 10 is a diagram for prioritization of two logical
channels for three different uplink grants;
[0030] FIG. 11 is a diagram for signaling of buffer status and
power-headroom reports;
[0031] FIG. 12 is a conceptual diagram for one of radio protocol
architecture for dual connectivity;
[0032] FIG. 13 is a conceptual diagram for reporting amount of data
available for transmission according to embodiments of the present
invention;
[0033] FIG. 14 is a conceptual diagram for triggering a buffer
status reporting according to embodiments of the present
invention;
[0034] FIG. 15 is conceptual diagram an exemplary according to
embodiments of the present invention; and
[0035] FIG. 16 is a block diagram of a communication apparatus
according to an embodiment of the present invention.
BEST MODE
[0036] Universal mobile telecommunications system (UMTS) is a 3rd
Generation (3G) asynchronous mobile communication system operating
in wideband code division multiple access (WCDMA) based on European
systems, global system for mobile communications (GSM) and general
packet radio services (GPRS). The long-term evolution (LTE) of UMTS
is under discussion by the 3rd generation partnership project
(3GPP) that standardized UMTS.
[0037] The 3GPP LTE is a technology for enabling high-speed packet
communications. Many schemes have been proposed for the LTE
objective including those that aim to reduce user and provider
costs, improve service quality, and expand and improve coverage and
system capacity. The 3G LTE requires reduced cost per bit,
increased service availability, flexible use of a frequency band, a
simple structure, an open interface, and adequate power consumption
of a terminal as an upper-level requirement.
[0038] Hereinafter, structures, operations, and other features of
the present invention will be readily understood from the
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Embodiments described
later are examples in which technical features of the present
invention are applied to a 3GPP system.
[0039] Although the embodiments of the present invention are
described using a long term evolution (LTE) system and a
LTE-advanced (LTE-A) system in the present specification, they are
purely exemplary. Therefore, the embodiments of the present
invention are applicable to any other communication system
corresponding to the above definition. In addition, although the
embodiments of the present invention are described based on a
frequency division duplex (FDD) scheme in the present
specification, the embodiments of the present invention may be
easily modified and applied to a half-duplex FDD (H-FDD) scheme or
a time division duplex (TDD) scheme.
[0040] FIG. 2A is a block diagram illustrating network structure of
an evolved universal mobile telecommunication system (E-UMTS). The
E-UMTS may be also referred to as an LTE system. The communication
network is widely deployed to provide a variety of communication
services such as voice (VoIP) through IMS and packet data.
[0041] As illustrated in FIG. 2A, the E-UMTS network includes an
evolved UMTS terrestrial radio access network (E-UTRAN), an Evolved
Packet Core (EPC) and one or more user equipment. The E-UTRAN may
include one or more evolved NodeB (eNodeB) 20, and a plurality of
user equipment (UE) 10 may be located in one cell. One or more
E-UTRAN mobility management entity (MME)/system architecture
evolution (SAE) gateways 30 may be positioned at the end of the
network and connected to an external network.
[0042] As used herein, "downlink" refers to communication from
eNodeB 20 to UE 10, and "uplink" refers to communication from the
UE to an eNodeB. UE 10 refers to communication equipment carried by
a user and may be also referred to as a mobile station (MS), a user
terminal (UT), a subscriber station (SS) or a wireless device.
[0043] FIG. 2B is a block diagram depicting architecture of a
typical E-UTRAN and a typical EPC.
[0044] As illustrated in FIG. 2B, an eNodeB 20 provides end points
of a user plane and a control plane to the UE 10. MME/SAE gateway
30 provides an end point of a session and mobility management
function for UE 10. The eNodeB and MME/SAE gateway may be connected
via an S1 interface.
[0045] The eNodeB 20 is generally a fixed station that communicates
with a UE 10, and may also be referred to as a base station (BS) or
an access point. One eNodeB 20 may be deployed per cell. An
interface for transmitting user traffic or control traffic may be
used between eNodeBs 20.
[0046] The MME provides various functions including NAS signaling
to eNodeBs 20, NAS signaling security, AS Security control, Inter
CN node signaling for mobility between 3GPP access networks, Idle
mode UE Reachability (including control and execution of paging
retransmission), Tracking Area list management (for UE in idle and
active mode), PDN GW and Serving GW selection, MME selection for
handovers with MME change, SGSN selection for handovers to 2G or 3G
3GPP access networks, Roaming, Authentication, Bearer management
functions including dedicated bearer establishment, Support for PWS
(which includes ETWS and CMAS) message transmission. The SAE
gateway host provides assorted functions including Per-user based
packet filtering (by e.g. deep packet inspection), Lawful
Interception, UE IP address allocation, Transport level packet
marking in the downlink, UL and DL service level charging, gating
and rate enforcement, DL rate enforcement based on APN-AMBR. For
clarity MME/SAE gateway 30 will be referred to herein simply as a
"gateway," but it is understood that this entity includes both an
MME and an SAE gateway.
[0047] A plurality of nodes may be connected between eNodeB 20 and
gateway 30 via the S1 interface. The eNodeBs 20 may be connected to
each other via an X2 interface and neighboring eNodeBs may have a
meshed network structure that has the X2 interface.
[0048] As illustrated, eNodeB 20 may perform functions of selection
for gateway 30, routing toward the gateway during a Radio Resource
Control (RRC) activation, scheduling and transmitting of paging
messages, scheduling and transmitting of Broadcast Channel (BCCH)
information, dynamic allocation of resources to UEs 10 in both
uplink and downlink, configuration and provisioning of eNodeB
measurements, radio bearer control, radio admission control (RAC),
and connection mobility control in LTE_ACTIVE state. In the EPC,
and as noted above, gateway 30 may perform functions of paging
origination, LTE-IDLE state management, ciphering of the user
plane, System Architecture Evolution (SAE) bearer control, and
ciphering and integrity protection of Non-Access Stratum (NAS)
signaling.
[0049] The EPC includes a mobility management entity (MME), a
serving-gateway (S-GW), and a packet data network-gateway (PDN-GW).
The MME has information about connections and capabilities of UEs,
mainly for use in managing the mobility of the UEs. The S-GW is a
gateway having the E-UTRAN as an end point, and the PDN-GW is a
gateway having a packet data network (PDN) as an end point.
[0050] FIG. 3 is a diagram showing a control plane and a user plane
of a radio interface protocol between a UE and an E-UTRAN based on
a 3GPP radio access network standard. The control plane refers to a
path used for transmitting control messages used for managing a
call between the UE and the E-UTRAN. The user plane refers to a
path used for transmitting data generated in an application layer,
e.g., voice data or Internet packet data.
[0051] A physical (PHY) layer of a first layer provides an
information transfer service to a higher layer using a physical
channel. The PHY layer is connected to a medium access control
(MAC) layer located on the higher layer via a transport channel.
Data is transported between the MAC layer and the PHY layer via the
transport channel. Data is transported between a physical layer of
a transmitting side and a physical layer of a receiving side via
physical channels. The physical channels use time and frequency as
radio resources. In detail, the physical channel is modulated using
an orthogonal frequency division multiple access (OFDMA) scheme in
downlink and is modulated using a single carrier frequency division
multiple access (SC-FDMA) scheme in uplink.
[0052] The MAC layer of a second layer provides a service to a
radio link control (RLC) layer of a higher layer via a logical
channel. The RLC layer of the second layer supports reliable data
transmission. A function of the RLC layer may be implemented by a
functional block of the MAC layer. A packet data convergence
protocol (PDCP) layer of the second layer performs a header
compression function to reduce unnecessary control information for
efficient transmission of an Internet protocol (IP) packet such as
an IP version 4 (IPv4) packet or an IP version 6 (IPv6) packet in a
radio interface having a relatively small bandwidth.
[0053] A radio resource control (RRC) layer located at the bottom
of a third layer is defined only in the control plane. The RRC
layer controls logical channels, transport channels, and physical
channels in relation to configuration, re-configuration, and
release of radio bearers (RBs). An RB refers to a service that the
second layer provides for data transmission between the UE and the
E-UTRAN. To this end, the RRC layer of the UE and the RRC layer of
the E-UTRAN exchange RRC messages with each other.
[0054] One cell of the eNB is set to operate in one of bandwidths
such as 1.25, 2.5, 5, 10, 15, and 20 MHz and provides a downlink or
uplink transmission service to a plurality of UEs in the bandwidth.
Different cells may be set to provide different bandwidths.
[0055] Downlink transport channels for transmission of data from
the E-UTRAN to the UE include a broadcast channel (BCH) for
transmission of system information, a paging channel (PCH) for
transmission of paging messages, and a downlink shared channel
(SCH) for transmission of user traffic or control messages. Traffic
or control messages of a downlink multicast or broadcast service
may be transmitted through the downlink SCH and may also be
transmitted through a separate downlink multicast channel
(MCH).
[0056] Uplink transport channels for transmission of data from the
UE to the E-UTRAN include a random access channel (RACH) for
transmission of initial control messages and an uplink SCH for
transmission of user traffic or control messages. Logical channels
that are defined above the transport channels and mapped to the
transport channels include a broadcast control channel (BCCH), a
paging control channel (PCCH), a common control channel (CCCH), a
multicast control channel (MCCH), and a multicast traffic channel
(MTCH).
[0057] FIG. 4 is a view showing an example of a physical channel
structure used in an E-UMTS system. A physical channel includes
several subframes on a time axis and several subcarriers on a
frequency axis. Here, one subframe includes a plurality of symbols
on the time axis. One subframe includes a plurality of resource
blocks and one resource block includes a plurality of symbols and a
plurality of subcarriers. In addition, each subframe may use
certain subcarriers of certain symbols (e.g., a first symbol) of a
subframe for a physical downlink control channel (PDCCH), that is,
an L1/L2 control channel. In FIG. 4, an L1/L2 control information
transmission area (PDCCH) and a data area (PDSCH) are shown. In one
embodiment, a radio frame of 10 ms is used and one radio frame
includes 10 subframes. In addition, one subframe includes two
consecutive slots. The length of one slot may be 0.5 ms. In
addition, one subframe includes a plurality of OFDM symbols and a
portion (e.g., a first symbol) of the plurality of OFDM symbols may
be used for transmitting the L1/L2 control information. A
transmission time interval (TTI) which is a unit time for
transmitting data is 1 ms.
[0058] A base station and a UE mostly transmit/receive data via a
PDSCH, which is a physical channel, using a DL-SCH which is a
transmission channel, except a certain control signal or certain
service data. Information indicating to which UE (one or a
plurality of UEs) PDSCH data is transmitted and how the UE receive
and decode PDSCH data is transmitted in a state of being included
in the PDCCH.
[0059] For example, in one embodiment, a certain PDCCH is
CRC-masked with a radio network temporary identity (RNTI) "A" and
information about data is transmitted using a radio resource "B"
(e.g., a frequency location) and transmission format information
"C" (e.g., a transmission block size, modulation, coding
information or the like) via a certain subframe. Then, one or more
UEs located in a cell monitor the PDCCH using its RNTI information.
And, a specific UE with RNTI "A" reads the PDCCH and then receive
the PDSCH indicated by B and C in the PDCCH information.
[0060] FIG. 5 is a diagram for carrier aggregation.
[0061] Carrier aggregation technology for supporting multiple
carriers is described with reference to FIG. 5 as follows. As
mentioned in the foregoing description, it may be able to support
system bandwidth up to maximum 100 MHz in a manner of bundling
maximum 5 carriers (component carriers: CCs) of bandwidth unit
(e.g., 20 MHz) defined in a legacy wireless communication system
(e.g., LTE system) by carrier aggregation. Component carriers used
for carrier aggregation may be equal to or different from each
other in bandwidth size. And, each of the component carriers may
have a different frequency band (or center frequency). The
component carriers may exist on contiguous frequency bands. Yet,
component carriers existing on non-contiguous frequency bands may
be used for carrier aggregation as well. In the carrier aggregation
technology, bandwidth sizes of uplink and downlink may be allocated
symmetrically or asymmetrically.
[0062] Multiple carriers (component carriers) used for carrier
aggregation may be categorized into primary component carrier (PCC)
and secondary component carrier (SCC). The PCC may be called P-cell
(primary cell) and the SCC may be called S-cell (secondary cell).
The primary component carrier is the carrier used by a base station
to exchange traffic and control signaling with a user equipment. In
this case, the control signaling may include addition of component
carrier, setting for primary component carrier, uplink (UL) grant,
downlink (DL) assignment and the like. Although a base station may
be able to use a plurality of component carriers, a user equipment
belonging to the corresponding base station may be set to have one
primary component carrier only. If a user equipment operates in a
single carrier mode, the primary component carrier is used. Hence,
in order to be independently used, the primary component carrier
should be set to meet all requirements for the data and control
signaling exchange between a base station and a user equipment.
[0063] Meanwhile, the secondary component carrier may include an
additional component carrier that can be activated or deactivated
in accordance with a required size of transceived data. The
secondary component carrier may be set to be used only in
accordance with a specific command and rule received from a base
station. In order to support an additional bandwidth, the secondary
component carrier may be set to be used together with the primary
component carrier. Through an activated component carrier, such a
control signal as a UL grant, a DL assignment and the like can be
received by a user equipment from a base station. Through an
activated component carrier, such a control signal in UL as a
channel quality indicator (CQI), a precoding matrix index (PMI), a
rank indicator (RI), a sounding reference signal (SRS) and the like
can be transmitted to a base station from a user equipment.
[0064] Resource allocation to a user equipment can have a range of
a primary component carrier and a plurality of secondary component
carriers. In a multi-carrier aggregation mode, based on a system
load (i.e., static/dynamic load balancing), a peak data rate or a
service quality requirement, a system may be able to allocate
secondary component carriers to DL and/or UL asymmetrically. In
using the carrier aggregation technology, the setting of the
component carriers may be provided to a user equipment by a base
station after RRC connection procedure. In this case, the RRC
connection may mean that a radio resource is allocated to a user
equipment based on RRC signaling exchanged between an RRC layer of
the user equipment and a network via SRB. After completion of the
RRC connection procedure between the user equipment and the base
station, the user equipment may be provided by the base station
with the setting information on the primary component carrier and
the secondary component carrier. The setting information on the
secondary component carrier may include addition/deletion (or
activation/deactivation) of the secondary component carrier.
Therefore, in order to activate a secondary component carrier
between a base station and a user equipment or deactivate a
previous secondary component carrier, it may be necessary to
perform an exchange of RRC signaling and MAC control element.
[0065] The activation or deactivation of the secondary component
carrier may be determined by a base station based on a quality of
service (QoS), a load condition of carrier and other factors. And,
the base station may be able to instruct a user equipment of
secondary component carrier setting using a control message
including such information as an indication type
(activation/deactivation) for DL/UL, a secondary component carrier
list and the like.
[0066] FIG. 6 is a conceptual diagram for dual connectivity (DC)
between a Master Cell Group (MCG) and a Secondary Cell Group
(SCG).
[0067] The dual connectivity means that the UE can be connected to
both a Master eNode-B (MeNB) and a Secondary eNode-B (SeNB) at the
same time. The MCG is a group of serving cells associated with the
MeNB, comprising of a PCell and optionally one or more SCells. And
the SCG is a group of serving cells associated with the SeNB,
comprising of the special SCell and optionally one or more SCells.
The MeNB is an eNB which terminates at least S1-MME (S1 for the
control plane) and the SeNB is an eNB that is providing additional
radio resources for the UE but is not the MeNB.
[0068] With dual connectivity, some of the data radio bearers
(DRBs) can be offloaded to the SCG to provide high throughput while
keeping scheduling radio bearers (SRBs) or other DRBs in the MCG to
reduce the handover possibility. The MCG is operated by the MeNB
via the frequency of f1, and the SCG is operated by the SeNB via
the frequency of f2. The frequency f1 and f2 may be equal. The
backhaul interface (BH) between the MeNB and the SeNB is non-ideal
(e.g. X2 interface), which means that there is considerable delay
in the backhaul and therefore the centralized scheduling in one
node is not possible.
[0069] FIG. 7a is a conceptual diagram for C-Plane connectivity of
base stations involved in dual connectivity, and FIG. 7b is a
conceptual diagram for U-Plane connectivity of base stations
involved in dual connectivity.
[0070] FIG. 7a shows C-plane (Control Plane) connectivity of eNBs
involved in dual connectivity for a certain UE. The MeNB is C-plane
connected to the MME via S1-MME, the MeNB and the SeNB are
interconnected via X2-C (X2-Control plane). As FIG. 7a, Inter-eNB
control plane signaling for dual connectivity is performed by means
of X2 interface signaling. Control plane signaling towards the MME
is performed by means of S1 interface signaling. There is only one
S1-MME connection per UE between the MeNB and the MME. Each eNB
should be able to handle UEs independently, i.e. provide the PCell
to some UEs while providing SCell(s) for SCG to others. Each eNB
involved in dual connectivity for a certain UE owns its radio
resources and is primarily responsible for allocating radio
resources of its cells, respective coordination between MeNB and
SeNB is performed by means of X2 interface signaling.
[0071] FIG. 7b shows U-plane connectivity of eNBs involved in dual
connectivity for a certain UE. U-plane connectivity depends on the
bearer option configured: i) For MCG bearers, the MeNB is U-plane
connected to the S-GW via S1-U, the SeNB is not involved in the
transport of user plane data, ii) For split bearers, the MeNB is
U-plane connected to the S-GW via S1-U and in addition, the MeNB
and the SeNB are interconnected via X2-U, and iii) For SCG bearers,
the SeNB is directly connected with the S-GW via S1-U. If only MCG
and split bearers are configured, there is no S1-U termination in
the SeNB. In the dual connectivity, enhancement of the small cell
is required in order to data offloading from the group of macro
cells to the group of small cells. Since the small cells can be
deployed apart from the macro cells, multiple schedulers can be
separately located in different nodes and operate independently
from the UE point of view. This means that different scheduling
node would encounter different radio resource environment, and
hence, each scheduling node may have different scheduling
results.
[0072] FIG. 8 is a conceptual diagram for radio protocol
architecture for dual connectivity.
[0073] E-UTRAN of the present example can support dual connectivity
operation whereby a multiple receptions/transmissions (RX/TX) UE in
RRC_CONNECTED is configured to utilize radio resources provided by
two distinct schedulers, located in two eNBs (or base stations)
connected via a non-ideal backhaul over the X2 interface. The eNBs
involved in dual connectivity for a certain UE may assume two
different roles: an eNB may either act as the MeNB or as the SeNB.
In dual connectivity, a UE can be connected to one MeNB and one
SeNB.
[0074] In the dual connectivity operation, the radio protocol
architecture that a particular bearer uses depends on how the
bearer is setup. Three alternatives exist, MCG bearer (801), split
bearer (803) and SCG bearer (805). Those three alternatives are
depicted on FIG. 8. The SRBs (Signaling Radio Bearers) are always
of the MCG bearer and therefore only use the radio resources
provided by the MeNB. The MCG bearer (801) is a radio protocol only
located in the MeNB to use MeNB resources only in the dual
connectivity. And the SCG bearer (805) is a radio protocol only
located in the SeNB to use SeNB resources in the dual
connectivity.
[0075] Specially, the split bearer (803) is a radio protocol
located in both the MeNB and the SeNB to use both MeNB and SeNB
resources in the dual connectivity and the split bearer (803) may
be a radio bearer comprising one Packet Data Convergence Protocol
(PDCP) entity, two Radio Link Control (RLC) entities and two Medium
Access Control (MAC) entities for one direction. Specially, the
dual connectivity operation can also be described as having at
least one bearer configured to use radio resources provided by the
SeNB.
[0076] FIG. 9 is a diagram for a general overview of the LTE
protocol architecture for the downlink.
[0077] A general overview of the LTE protocol architecture for the
downlink is illustrated in FIG. 9. Furthermore, the LTE protocol
structure related to uplink transmissions is similar to the
downlink structure in FIG. 9, although there are differences with
respect to transport format selection and multi-antenna
transmission.
[0078] Data to be transmitted in the downlink enters in the form of
IP packets on one of the SAE bearers (901). Prior to transmission
over the radio interface, incoming IP packets are passed through
multiple protocol entities, summarized below and described in more
detail in the following sections: [0079] Packet Data Convergence
Protocol (PDCP, 903) performs IP header compression to reduce the
number of bits necessary to transmit over the radio interface. The
header-compression mechanism is based on ROHC, a standardized
header-compression algorithm used in WCDMA as well as several other
mobile-communication standards. PDCP (903) is also responsible for
ciphering and integrity protection of the transmitted data. At the
receiver side, the PDCP protocol performs the corresponding
deciphering and decompression operations. There is one PDCP entity
per radio bearer configured for a mobile terminal. [0080] Radio
Link Control (RLC, 905) is responsible for
segmentation/concatenation, retransmission handling, and
in-sequence delivery to higher layers. Unlike WCDMA, the RLC
protocol is located in the eNodeB since there is only a single type
of node in the LTE radio-access-network architecture. The RLC (905)
offers services to the PDCP (903) in the form of radio bearers.
There is one RLC entity per radio bearer configured for a terminal.
[0081] Medium Access Control (MAC, 907) handles hybrid-ARQ
retransmissions and uplink and downlink scheduling. The scheduling
functionality is located in the eNodeB, which has one MAC entity
per cell, for both uplink and downlink. The hybrid-ARQ protocol
part is present in both the transmitting and receiving end of the
MAC protocol. The MAC (907) offers services to the RLC (905) in the
form of logical channels (909). [0082] Physical Layer (PHY, 911),
handles coding/decoding, modulation/demodulation, multi-antenna
mapping, and other typical physical layer functions. The physical
layer (911) offers services to the MAC layer (907) in the form of
transport channels (913).
[0083] The MAC (907) offers services to the RLC (905) in the form
of logical channels (909). A logical channel (909) is defined by
the type of information it carries and are generally classified
into control channels, used for transmission of control and
configuration information necessary for operating an LTE system,
and traffic channels, used for the user data.
[0084] The set of logical-channel types specified for LTE includes:
[0085] Broadcast Control Channel (BCCH), used for transmission of
system control information from the network to all mobile terminals
in a cell. Prior to accessing the system, a mobile terminal needs
to read the information transmitted on the BCCH to find out how the
system is configured, for example the bandwidth of the system.
[0086] Paging Control Channel (PCCH), used for paging of mobile
terminals whose location on cell level is not known to the network
and the paging message therefore needs to be transmitted in
multiple cells. [0087] Dedicated Control Channel (DCCH), used for
transmission of control information to/from a mobile terminal. This
channel is used for individual configuration of mobile terminals
such as different handover messages. [0088] Multicast Control
Channel (MCCH), used for transmission of control information
required for reception of the MTCH. [0089] Dedicated Traffic
Channel (DTCH), used for transmission of user data to/from a mobile
terminal. This is the logical channel type used for transmission of
all uplink and non-MBMS downlink user data. [0090] Multicast
Traffic Channel (MTCH), used for downlink transmission of MBMS
services.
[0091] FIG. 10 is a diagram for prioritization of two logical
channels for three different uplink grants.
[0092] Multiple logical channels of different priorities can be
multiplexed into the same transport block using the same MAC
multiplexing functionality as in the downlink. However, unlike the
downlink case, where the prioritization is under control of the
scheduler and up to the implementation, the uplink multiplexing is
done according to a set of well-defined rules in the terminal as a
scheduling grant applies to a specific uplink carrier of a
terminal, not to a specific radio bearer within the terminal. Using
radio-bearer-specific scheduling grants would increase the control
signaling overhead in the downlink and hence per-terminal
scheduling is used in LTE.
[0093] The simplest multiplexing rule would be to serve logical
channels in strict priority order. However, this may result in
starvation of lower-priority channels; all resources would be given
to the high-priority channel until its transmission buffer is
empty. Typically, an operator would instead like to provide at
least some throughput for low-priority services as well. Therefore,
for each logical channel in an LTE terminal, a prioritized data
rate is configured in addition to the priority value. The logical
channels are then served in decreasing priority order up to their
prioritized data rate, which avoids starvation as long as the
scheduled data rate is at least as large as the sum of the
prioritized data rates. Beyond the prioritized data rates, channels
are served in strict priority order until the grant is fully
exploited or the buffer is empty. This is illustrated in FIG.
10.
[0094] Regarding FIG. 10, it may be assumed that a priority of the
logical channel 1 (LCH 1) is higher than a priority of the logical
channel 2 (LCH 2). In case of (A), all prioritized data of the LCH
1 can be transmitted and a portion of prioritized data of the LCH 2
can be transmitted until amount of the scheduled data rate. In case
of (B), all prioritized data of the LCH 1 and all prioritized data
of the LCH 2 can be transmitted. In case of (C) all prioritized
data of the LCH 1 and all prioritized data of the LCH 2 can be
transmitted and a portion of data of the LCH 1 can be further
transmitted.
[0095] FIG. 11 is a diagram for signaling of buffer status and
power-headroom reports.
[0096] The scheduler needs knowledge about the amount of data
awaiting transmission from the terminals to assign the proper
amount of uplink resources. Obviously, there is no need to provide
uplink resources to a terminal with no data to transmit as this
would only result in the terminal performing padding to fill up the
granted resources. Hence, as a minimum, the scheduler needs to know
whether the terminal has data to transmit and should be given a
grant. This is known as a scheduling request.
[0097] The use of a single bit for the scheduling request is
motivated by the desire to keep the uplink overhead small, as a
multi-bit scheduling request would come at a higher cost. A
consequence of the single bit scheduling request is the limited
knowledge at the eNodeB about the buffer situation at the terminal
when receiving such a request. Different scheduler implementations
handle this differently. One possibility is to assign a small
amount of resources to ensure that the terminal can exploit them
efficiently without becoming power limited. Once the terminal has
started to transmit on the UL-SCH, more detailed information about
the buffer status and power headroom can be provided through the
inband MAC control message, as discussed below.
[0098] Terminals that already have a valid grant obviously do not
need to request uplink resources. However, to allow the scheduler
to determine the amount of resources to grant to each terminal in
future subframes, information about the buffer situation and the
power availability is useful, as discussed above. This information
is provided to the scheduler as part of the uplink transmission
through MAC control element. The LCID field in one of the MAC
subheaders is set to a reserved value indicating the presence of a
buffer status report, as illustrated in FIG. 11.
[0099] From a scheduling perspective, buffer information for each
logical channel is beneficial, although this could result in a
significant overhead. Logical channels are therefore grouped into
logical-channel groups and the reporting is done per group. The
buffer-size field in a buffer-status report indicates the amount of
data awaiting transmission across all logical channels in a
logical-channel group. A buffer status report represents one or all
four logical-channel groups and can be triggered for the following
reasons:
[0100] i) Arrival of data with higher priority than currently in
the transmission buffer--that is, data in a logical-channel group
with higher priority than the one currently being transmitted--as
this may impact the scheduling decision.
[0101] ii) Change of serving cell, in which case a buffer-status
report is useful to provide the new serving cell with information
about the situation in the terminal.
[0102] iii) Periodically as controlled by a timer.
[0103] iv) Instead of padding. If the amount of padding required to
match the scheduled transport block size is larger than a
buffer-status report, a buffer-status report is inserted. Clearly
it is better to exploit the available payload for useful scheduling
information instead of padding if possible.
[0104] Data Available for Transmission in a PDCP Entity
[0105] 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 entity:
[0106] For SDUs for which no PDU has been submitted to lower
layers: i) the SDU itself, if the SDU has not yet been processed by
PDCP, or ii) the PDU if the SDU has been processed by PDCP.
[0107] 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 entity:
[0108] 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: i) the SDU, if it has not yet
been processed by PDCP, or ii) the PDU once it has been processed
by PDCP.
[0109] Data Available for Transmission in a RLC Entity
[0110] For the purpose of MAC buffer status reporting, the UE shall
consider the following as data available for transmission in the
entity: i) RLC SDUs, or segments thereof, that have not yet been
included in an RLC data PDU, ii) RLC data PDUs, or portions
thereof, that are pending for retransmission (RLC AM).
[0111] In addition, if a STATUS PDU has been triggered and
t-StatusProhibit is not running or has expired, the UE shall
estimate the size of the STATUS PDU that will be transmitted in the
next transmission opportunity, and consider this as data available
for transmission in the RLC layer.
[0112] Buffer Status Reporting (BSR)
[0113] The Buffer Status Reporting (BSR) procedure is used to
provide a serving eNB with information about the amount of data
available for transmission (DAT) in the UL buffers of the UE. RRC
may control BSR reporting by configuring the two timers
periodicBSR-Timer and retxBSR-Timer and by, for each logical
channel, optionally signalling Logical Channel Group which
allocates the logical channel to an LCG (Logical Channel
Group).
[0114] For the Buffer Status reporting procedure, the UE may
consider all radio bearers which are not suspended and may consider
radio bearers which are suspended. A Buffer Status Report (BSR) may
be triggered if any of the following events occur: [0115] UL data,
for a logical channel which belongs to a LCG, becomes available for
transmission in the RLC entity or in the PDCP entity and either the
data belongs to a logical channel with higher priority than the
priorities of the logical channels which belong to any LCG and for
which data is already available for transmission, or there is no
data available for transmission for any of the logical channels
which belong to a LCG, in which case the BSR is referred below to
as "Regular BSR"; [0116] UL resources are allocated and number of
padding bits is equal to or larger than the size of the Buffer
Status Report MAC control element plus its subheader, in which case
the BSR is referred below to as "Padding BSR"; [0117] retxBSR-Timer
expires and the UE has data available for transmission for any of
the logical channels which belong to a LCG, in which case the BSR
is referred below to as "Regular BSR"; [0118] periodicBSR-Timer
expires, in which case the BSR is referred below to as "Periodic
BSR".
[0119] A MAC PDU may contain at most one MAC BSR control element,
even when multiple events trigger a BSR by the time a BSR can be
transmitted in which case the Regular BSR and the Periodic BSR
shall have precedence over the padding BSR.
[0120] The UE may restart retxBSR-Timer upon indication of a grant
for transmission of new data on any UL-SCH.
[0121] All triggered BSRs may be cancelled in case UL grants in
this subframe can accommodate all pending data available for
transmission but is not sufficient to additionally accommodate the
BSR MAC control element plus its subheader. All triggered BSRs
shall be cancelled when a BSR is included in a MAC PDU for
transmission.
[0122] The UE shall transmit at most one Regular/Periodic BSR in a
TTI. If the UE is requested to transmit multiple MAC PDUs in a TTI,
it may include a padding BSR in any of the MAC PDUs which do not
contain a Regular/Periodic BSR.
[0123] All BSRs transmitted in a TTI always reflect the buffer
status after all MAC PDUs have been built for this TTI. Each LCG
shall report at the most one buffer status value per TTI and this
value shall be reported in all BSRs reporting buffer status for
this LCG.
[0124] FIG. 12 is a conceptual diagram for one of radio protocol
architecture for dual connectivity.
[0125] `Data available for transmission` is defined in PDCP and RLC
layers to be used for Buffer Status Reporting (BSR), Logical
Channel Prioritization (LCP), and Random Access Preamble Group
(RAPG) selection in MAC layer. In the prior art, there are only one
PDCP entity and one RLC entity for one direction (i.e. uplink or
downlink) in a Radio Bearer, and thus, when the UE calculates `data
available for transmission`, it just sums up the data available for
transmission in PDCP and that in RLC.
[0126] However, in LTE Rel-12, a new study on dual connectivity,
i.e. UE is connected to both MeNB (1201) and SeNB (1203), as shown
in FIG. 12. In this figure, the interface between MeNB (1201) and
SeNB (1203) is called Xn interface (1205). The Xn interface (1205)
is assumed to be non-ideal; i.e. the delay in Xn interface could be
up to 60 ms, but it is not limited thereto.
[0127] To support dual connectivity, one of the potential solutions
is for the UE (1207) to transmit data to both MeNB (1201) and SeNB
(1203) utilizing a new RB structure called dual RLC/MAC scheme,
where a single RB has one PDCP--two RLC--two MAC for one direction,
and RLC/MAC pair is configured for each cell, as shown in FIG. 12.
In this figure, BE-DRB (1209) stands for DRB for Best Effort
traffic.
[0128] In this case, the MAC functions addressed above, i.e. buffer
status reporting, are performed in each MAC, since the UL resource
scheduling node is located in different node in the network side,
i.e. one in MeNB (1201) and the other in SeNB (1203).
[0129] The problem is how to use the information `data available
for transmission in PDCP` in the MAC functions. If each MAC
utilizes the same information of `data available for transmission
in PDCP`, both the MeNB and the SeNB would allocate UL resource
that can cope with `data available for transmission in PDCP`, in
which case the `data available for transmission in PDCP` is
considered twice, and it leads to wastage of radio resource.
[0130] FIG. 13 is a conceptual diagram for reporting amount of data
available for transmission according to embodiments of the present
invention.
[0131] To prevent a first base station and a second base station to
over-allocate the UL resource to the UE having dual RLC/MAC scheme,
it is invented that the UE divides `Data Available for Transmission
in PDCP` (hereafter called DATP) to each MAC based on ratio.
[0132] The ratio may indicate ratio of "amount of PDCP data
transmitted to RLC1" to "amount of PDCP data transmitted to RLC2"
where RLC1 and RLC2 are connected to the PDCP entity, but it is not
limited thereto. The RLC1 is for the first base station and RLC2 is
for the second base station. Desirably, the first base station may
be a MeNB and the second base station may be a SeNB, and vice
versa.
[0133] The ratio may be configured by the first base station or the
second base station through RRC signaling or PDCP signaling or MAC
signaling, when a radio bearer is configured or reconfigured
(S1301). The ration is for calculating amount of Data Available for
Transmission (DAT) in a PDCP (Packet Data Convergence Protocol)
entity. The ratio can be a form of ratio "DATP-1 (DATP for MAC in
the first base station):DATP-2 (DATP for MAC in the second base
station", or percentile amount of DATP-2 compared to DATP-1, or
vice versa, or any type of information that indicates the amount of
data that can be used to divide the DATP to DATP-1 and DATP-2.
[0134] The UE can calculate an amount of DAT when data is arrived
in the PDCP entity (S1303).
[0135] When the UE calculates the DATP and divides it into DATP-1
and DATP-2, if the DATP is less than a threshold, the UE does not
divide the DATP into DATP-1 and DATP-2. The threshold may be called
as "minimum amount of data in PDCP".
[0136] When the result of the step of S1303 is "X", consequently,
the UE can set a first amount of DAT (DATP-1) as the calculated
amount of DAT (X) and a second amount of DAT (DATP-2) as 0 or the
first amount of DAT (DATP-1) as 0 and the second amount of DAT
(DATP-2) as the calculated amount of DAT (X)" when DATP is less
than the threshold (S1305). This method aims at reducing the waste
of UL resource considering the minimum amount of UL resources to be
assigned to the UE.
[0137] The UE may receive the information related to the threshold
from the first base station or the second base station. The
information related to the threshold may indicate the minimum
amount of data in PDCP in byte.
[0138] The UE may receive configuration information through RRC
signaling from the first base station for the second base station.
When the UE calculates DATP (S1303), if it is less than the
threshold, the UE can select one of DATP-1 or DATP-2 by following
the priority received from the first base station/the second base
station or can randomly select one of DATP-1 or DATP-2.
[0139] The priority indicates which base station is prioritized
over other base station. Then, the UE sets the selected DATP-1 or
DATP-2 equal to DATP. For example, when the DATP is less than the
threshold, if the DATP-1 is prioritized over the DATP-2 by the
first base station or the second base station, the UE divides DATP
into DATP-1 and DATP-2 so that "DATP-M=X bytes" and "DATP-S=0
byte".
[0140] After the step of S1305, the UE can report the amount of DAT
to the BS (S1307). In this case, the UE can report the amount of
DATP-1 to the first base station and can report the amount of
DATP-2 to the second base station. If the amount of DATP-2 is `0`,
the UE can report the amount of DATP-1 to the first base station
but the UE may not report the amount of DATP-2 to the second base
station.
[0141] Meanwhile, when the UE calculates the DATP and divides it
into DATP-1 and DATP-2, if the DATP is equal to or more than the
threshold, the UE may divide the DATP into DATP-1 and DATP-2 based
on the ratio (S1309). In this case, the UE may set a first amount
of DAT (DATP-1) as `Y` and a second amount of DAT (DATP-2) as `Z`
based on the ratio when DATP is equal to or more than the threshold
(S1311).
[0142] When the UE calculates the DATP and divides it into DATP-1
and DATP-2 using the ratio, there is a case that the DATP-1 and
DATP-2 are not the multiple of bytes. Since the UL resource is
always assigned by bytes, the UE aligns DATP-1 and DATP-2 with the
multiple of bytes as follows:
[0143] If the DATP-1 and DATP-2 are not the multiple of bytes,
[0144] The UE rounds off DATP-1 and DATP-2 to the nearest integer.
For example, when the DATP=101 bytes, if the UE divides the DATP
using the ratio of 3:7, the DATP-1=30.3 bytes and DATP-2=70.7
bytes. In this case, the UE rounds off DATP-1 and DATP-2 so that
the DATP-1 is 30 bytes and DATP-2 is 71 bytes. The UE also can
round off/roundup/rounddown one or both of DATP-1 and DATP-2.
[0145] The UE adds the remaining amount of data to DATP-1 or
DATP-2. For example, if the DATP=101 bytes, the DATP-M=30.3 bytes
and DATP-S=70.7 bytes. In this case, the UE adds the remaining 0.3
bytes of DATP-1 to the DATP-2 so that the DATP-1 is 30 bytes and
DATP-2 is 71 bytes.
[0146] After the step of S1311, the UE can report the amount of DAT
to the BS (S1313). In this case, the UE can report the amount of
DATP-1 to the first base station and can report the amount of
DATP-2 to the second base station.
[0147] FIG. 14 is a conceptual diagram for triggering a buffer
status reporting according to embodiments of the present
invention.
[0148] The Buffer Status Reporting (BSR) procedure is used to
provide a serving BS with information about the amount of data
available for transmission (DAT) in the UL buffers of the UE. For
the Buffer Status reporting procedure, the UE may consider all
radio bearers which are not suspended and may consider radio
bearers which are suspended.
[0149] In this prior art, a Buffer Status Report (BSR) may be
triggered when UL data, for a logical channel which belongs to a
LCG, becomes available for transmission in the RLC entity or in the
PDCP entity and either the data belongs to a logical channel with
higher priority than the priorities of the logical channels which
belong to any LCG and for which data is already available for
transmission, or there is no data available for transmission for
any of the logical channels which belong to a LCG, in which case
the BSR is referred below to as "Regular BSR". That means, when
data belongs to a logical channel with same priority as the
priorities of the logical channels which belong to any LCG and for
which data is already available for transmission, the BSR is not
triggered.
[0150] However, in dual connectivity system, the UE is required to
trigger the BSR although data belongs to a logical channel with
same priority as the priorities of the logical channels which
belong to any LCG and for which data is already available for
transmission.
[0151] Regarding FIG. 14, when the first data is arrived in a
protocol entity, the UE can calculate an amount of first DAT
(S1401). Desirably, the protocol entity is a PDCP entity, but it is
not limited thereto.
[0152] When the result of the step of S1401 is "X", if the X is
less than a threshold, the UE can set an amount of DAT for a first
logical channel (DATP-1) as the calculated amount of DAT (X) and an
amount of DAT for a second logical channel (DATP-2) as `zero`. The
first logical channel is for the first BS and the second logical
channel is for the second BS. On the other hand, if the X is equal
to or more than a threshold, the UE may trigger a BSR (S1403).
[0153] After the step of S1401, when the second data is arrived in
a protocol entity, the UE can calculate an amount of second DAT
(S1405). When the result of the step of S1405 is "Y", if the Y is
equal to or more than the threshold, the UE can trigger the BSR
(S1407) although data belongs to a logical channel with same
priority as the priorities of the logical channels which belong to
any LCG and for which data is already available for transmission.
If the Y is less than the threshold, the UE cannot trigger the BSR
(S1409).
[0154] In conclusion, in view of the second logical channel, the
second logical channel has a lower priority than the first logical
channel. Thus, in the step of the S1401, if X is less than the
threshold, an amount of DAT for a second logical channel is set to
`0`. BSR of the second logical channel is not triggered despite
having the data. In the step of S1405, if Y is equal to or more
than the threshold, the amount of DAT for a second logical channel
is set to some byte based on the certain ratio. In this case, the
BSR of the second logical channel is required to trigger the BSR
although the data belongs to a logical channel with same priority
as the priorities of the logical channels which belong to any LCG
and for which data is already available for transmission. Thus, the
UE can trigger the BSR when the amount of first DAT is less than a
threshold and the amount of second DAT is more than the
threshold.
[0155] FIG. 15 is conceptual diagram an exemplary according to
embodiments of the present invention.
[0156] An example procedure of this invention is shown in FIG. 15,
but this is one of example according to embodiments of the present
invention, so it is not limited thereto.
[0157] The UE receives ratio information of a RB identified by RB
ID from an MeNB or a SeNB. In this example, the ratio is set to
3:7. The UE also receives threshold information. The threshold is
set to 20 bytes and DATP-M is prioritized over DATP-S in this
example (S1501). The `DATP-M` is Data Available for Transmission in
PDCP for the MeNB and the `DATP-S` is Data Available for
Transmission in PDCP for the SeNB.
[0158] The first data for the indicated RB are arrived (S1503). The
UE calculates the DATP. Since the DATP is 10 bytes and less than 20
bytes, the UE does not divide it into DATP-M and DATP-S so that
DATP-M=10 bytes and DATP-S=0 byte (S1505).
[0159] For the indicated RB, the UE calculates the DATR-M (Data
Available for Transmission in RLC for the MeNB) and DATR-S (Data
Available for Transmission in RLC for the SeNB). In this example,
DATR-M=0 bytes and DATR-S=0 bytes (S1507). For the indicated RB,
the UE calculates DAT-M (Data Available for Transmission for the
MeNB) and DAT-S (Data Available for Transmission for the SeNB) such
as DAT-M=DATP-M+DATR-M and DAT-S=DATP-S+DATR-S. In this example,
DAT-M=0+10=10 bytes, and DAT-S=0+0=0 bytes (S1509). Since this is
an initial transmission and the DATP is less than threshold, the UE
sends the BSR only to the MeNB (S1511).
[0160] For the indicated RB, the data belonging to the same logical
channel are arrived (S1513). For the indicated RB, the UE
calculates the DATP. Since the DATP is 30 bytes, which is more than
20 bytes, and the previous DATP is less than the threshold, the UE
triggers BSR and divides it into DATP-M and DATP-S using ratio
(S1515). Consequently, DATP-M=9 bytes and DATP-S=21 byte.
[0161] For the indicated RB, the UE calculates the DATR-M and
DATR-S. In this example, DATR-M=2 bytes and DATR-S=0 bytes
(S1517).
[0162] For the indicated RB, the UE calculates DAT-M and DAT-S. In
this example, DAT-M=2+9=11 bytes, and DAT-S=0+21=21 bytes (S1519).
The UE sends the BSR to both of MeNB and SeNB with the calculated
buffer size (S1521) because the BSR is triggered in the step of
S1515.
[0163] FIG. 16 is a block diagram of a communication apparatus
according to an embodiment of the present invention.
[0164] The apparatus shown in FIG. 16 can be a user equipment (UE)
and/or eNB adapted to perform the above mechanism, but it can be
any apparatus for performing the same operation.
[0165] As shown in FIG. 16, the apparatus may comprises a
DSP/microprocessor (110) and RF module (transmiceiver; 135). The
DSP/microprocessor (110) is electrically connected with the
transceiver (135) and controls it. The apparatus may further
include power management module (105), battery (155), display
(115), keypad (120), SIM card (125), memory device (130), speaker
(145) and input device (150), based on its implementation and
designer's choice.
[0166] Specifically, FIG. 16 may represent a UE comprising a
receiver (135) configured to receive a request message from a
network, and a transmitter (135) configured to transmit the
transmission or reception timing information to the network. These
receiver and the transmitter can constitute the transceiver (135).
The UE further comprises a processor (110) connected to the
transceiver (135: receiver and transmitter).
[0167] Also, FIG. 17 may represent a network apparatus comprising a
transmitter (135) configured to transmit a request message to a UE
and a receiver (135) configured to receive the transmission or
reception timing information from the UE. These transmitter and
receiver may constitute the transceiver (135). The network further
comprises a processor (110) connected to the transmitter and the
receiver. This processor (110) may be configured to calculate
latency based on the transmission or reception timing
information.
[0168] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
[0169] The embodiments of the present invention described herein
below are combinations of elements and features of the present
invention. The elements or features may be considered selective
unless otherwise mentioned. Each element or feature may be
practiced without being combined with other elements or features.
Further, an embodiment of the present invention may be constructed
by combining parts of the elements and/or features. Operation
orders described in embodiments of the present invention may be
rearranged. Some constructions of any one embodiment may be
included in another embodiment and may be replaced with
corresponding constructions of another embodiment. It is obvious to
those skilled in the art that claims that are not explicitly cited
in each other in the appended claims may be presented in
combination as an embodiment of the present invention or included
as a new claim by subsequent amendment after the application is
filed.
[0170] In the embodiments of the present invention, a specific
operation described as performed by the BS may be performed by an
upper node of the BS. Namely, it is apparent that, in a network
comprised of a plurality of network nodes including a BS, various
operations performed for communication with an MS may be performed
by the BS, or network nodes other than the BS. The term eNB' may be
replaced with the term `fixed station`, `Node B`, `Base Station
(BS)`, `access point`, etc.
[0171] The above-described embodiments may be implemented by
various means, for example, by hardware, firmware, software, or a
combination thereof.
[0172] In a hardware configuration, the method according to the
embodiments of the present invention may be implemented by one or
more Application Specific Integrated Circuits (ASICs), Digital
Signal Processors (DSPs), Digital Signal Processing Devices
(DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate
Arrays (FPGAs), processors, controllers, microcontrollers, or
microprocessors.
[0173] In a firmware or software configuration, the method
according to the embodiments of the present invention may be
implemented in the form of modules, procedures, functions, etc.
performing the above-described functions or operations. Software
code may be stored in a memory unit and executed by a processor.
The memory unit may be located at the interior or exterior of the
processor and may transmit and receive data to and from the
processor via various known means.
[0174] Those skilled in the art will appreciate that the present
invention may be carried out in other specific ways than those set
forth herein without departing from the spirit and essential
characteristics of the present invention. The above embodiments are
therefore to be construed in all aspects as illustrative and not
restrictive. The scope of the invention should be determined by the
appended claims and their legal equivalents, not by the above
description, and all changes coming within the meaning and
equivalency range of the appended claims are intended to be
embraced therein.
INDUSTRIAL APPLICABILITY
[0175] While the above-described method has been described
centering on an example applied to the 3GPP LTE system, the present
invention is applicable to a variety of wireless communication
systems in addition to the 3GPP LTE system.
* * * * *