U.S. patent application number 13/951641 was filed with the patent office on 2014-01-30 for method of supporting signal transmission and reception using at least two radio access technologies and apparatus therefor.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Heejeong CHO, Jaehoon CHUNG, Eunjong LEE.
Application Number | 20140029570 13/951641 |
Document ID | / |
Family ID | 49994850 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140029570 |
Kind Code |
A1 |
LEE; Eunjong ; et
al. |
January 30, 2014 |
METHOD OF SUPPORTING SIGNAL TRANSMISSION AND RECEPTION USING AT
LEAST TWO RADIO ACCESS TECHNOLOGIES AND APPARATUS THEREFOR
Abstract
A method of supporting signal transmission/reception using at
least two RATs and apparatus therefor are disclosed. The present
invention includes, when a user equipment is simultaneously
accessing a 1.sup.st base station of a 1.sup.st communication
network supportive of a 1.sup.st RAT and a 2.sup.nd base station of
a 2.sup.nd communication network supportive of a 2.sup.nd RAT,
receiving a setup message indicating a termination of a connection
to the 2.sup.nd base station from the 1.sup.st base station and
terminating the connection to the 2.sup.nd base station. Before the
connection to the 2.sup.nd base station is terminated, the user
equipment transceives data for a specific traffic type via the
2.sup.nd base station and also transceives data except the specific
traffic type via the 1.sup.st base station. If the connection to
the 2.sup.nd base station is terminated, the user equipment
transceives the data for the specific traffic type via the 1.sup.st
base station.
Inventors: |
LEE; Eunjong; (Gyeonggi-do,
KR) ; CHO; Heejeong; (Gyeonggi-do, KR) ;
CHUNG; Jaehoon; (Gyeonggi-do, KR) |
Assignee: |
LG Electronics Inc.
Seoul
KR
|
Family ID: |
49994850 |
Appl. No.: |
13/951641 |
Filed: |
July 26, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61676312 |
Jul 26, 2012 |
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61692241 |
Aug 23, 2012 |
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61693759 |
Aug 27, 2012 |
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61699263 |
Sep 10, 2012 |
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61809423 |
Apr 8, 2013 |
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Current U.S.
Class: |
370/331 |
Current CPC
Class: |
H04W 76/34 20180201;
H04W 72/0446 20130101; H04W 36/005 20130101; H04W 36/0005 20130101;
H04W 76/15 20180201; H04W 28/0215 20130101; H04W 88/06 20130101;
H04W 76/16 20180201; H04W 48/14 20130101; H04W 72/048 20130101;
H04W 36/28 20130101; H04W 36/08 20130101 |
Class at
Publication: |
370/331 |
International
Class: |
H04W 36/00 20060101
H04W036/00 |
Claims
1. A method of supporting signal transmission and reception, by a
user equipment, using at least two radio access technologies
(RATs), the method comprising: receiving, at the user equipment
concurrently connected a first base station of a first
communication network supportive of a first RAT and a second base
station of a second communication network supportive of a second
RAT, a setup message indicating a termination of a connection to
the second base station from the first base station; and
terminating the connection to the second base station, wherein
before the connection to the second base station is terminated, the
user equipment transceives data for a specific traffic type via the
second base station and also transceives data except the specific
traffic type via the first base station and wherein if the
connection to the second base station is terminated, the user
equipment transceives the data for the specific traffic type via
the first base station.
2. The method of claim 1, wherein the setup message comprises a
flow information indicating the specific traffic type to be
transceived via the second base station.
3. The method of claim 1, wherein the setup message comprises a
disconnection time information indicating a termination time of the
connection to the second base station and wherein the user
equipment terminates the connection to the second base station at
the time indicated by the disconnection time information.
4. The method of claim 1, wherein the setup message comprises an
action time information indicating a communication start time for
the specific traffic type with the first base station and wherein
the user equipment starts the communication for the specific
traffic type with the first base station at the time indicated by
the action time information.
5. The method of claim 1, the method further comprising sending a
complete message for reporting whether the termination of the
connection to the second base station is successful to the first
base station.
6. The method of claim 5, wherein the complete message is sent if
the user equipment successfully terminates the connection to the
second base station.
7. A method of supporting signal transmission and reception, by a
first base station of a first communication network supportive of a
first RAT (radio access technology), using at least two radio
access technologies (RATs), the method comprising the steps of:
sending a setup message indicating a termination of a connection to
a second base station to the user equipment concurrently connected
the first base station and the second base station of a second
communication network supportive of a second RAT; and receiving a
complete message for reporting whether the termination of the
connection to the second base station is successful from the user
equipment, wherein the first base station redirects data for a
specific traffic type among data to be transmitted to the user
equipment into the second base station and also transmits the data
except the specific traffic type to the user equipment in direct,
and wherein if the connection between the user equipment and the
second base station is terminated, the first base station transmits
the data for the specific traffic type to the user equipment in
direct.
8. The method of claim 7, wherein the setup message comprises a
flow information indicating the specific traffic type to be
transceived via the second base station.
9. The method of claim 8, wherein the setup message comprises a
disconnection time information indicating a termination time of the
connection between the user equipment and the second base station
and wherein the first base station stops a redirection of a path of
the specific traffic type to the second base station at the time
indicated by the disconnection time information.
10. The method of claim 7, wherein the setup message comprises an
action time information indicating a communication start time for
the specific traffic type between the first base station and the
user equipment and wherein the first base station starts the
communication for the specific traffic type with the user equipment
at the time indicated by the action time information.
11. The method of claim 7, the method further comprising re-sending
the setup message to user equipment when the termination of the
connection between the user equipment and the second base station
is unsuccessful.
12. The method of claim 11, wherein if not receiving the complete
message until expiration of a timer initiated after sending the
setup message, the first base station determines the failure in the
termination of the connection between the user equipment and the
second base station.
13. In supporting signal transmission and reception using at least
two radio access technologies (RATs), a user equipment comprising:
a communication unit; and a processor, wherein if the communication
unit, concurrently connected a first base station of a first
communication network supportive of a first RAT and a second base
station of a second communication network supportive of a second
RAT, receives a setup message indicating a termination of a
connection to the second base station from the first base station,
the processor configured to control the communication unit to
terminate the connection to the second base station, wherein before
the connection to the second base station is terminated, the
processor configured to control data for a specific traffic type to
be transceived via the second base station and also control data
except the specific traffic type to be transceived via the first
base station, and wherein if the connection to the second base
station is terminated, the processor configured to control the data
for the specific traffic type to be transceived via the first base
station.
14. In supporting signal transmission and reception using at least
two radio access technologies (RATs), a base station, which belongs
to a first communication network supportive of a first RAT (radio
access technology), the base station comprising: a communication
unit; and a processor configured to control the communication unit
to send a setup message indicating a termination of a connection to
a second base station to a user equipment currently accessing both
of the communication unit and the second base station of a second
communication network supportive of a second RAT, and control the
communication unit to receive a complete message for reporting a
success or failure in the termination of the connection to the
second base station from the user equipment, wherein the processor
configured to redirect data for a specific traffic type among data
to be transmitted to the user equipment into the second base
station and also transmit the data except the specific traffic type
to the user equipment in direct, and wherein if the connection
between the user equipment and the second base station is
terminated, the processor configured to transmit the data for the
specific traffic type to the user equipment in direct.
Description
[0001] Pursuant to 35 U.S.C. .sctn.119(e), this application claims
the benefit of earlier filing date and right of priority to U.S.
Application No. 61/676,312, filed on Jul. 26, 2012, No. 61/692,241,
filed on Aug. 23, 2012, No. 61/693,759, filed on Aug. 27, 2012, No.
61/699,263, filed on Sep. 10, 2012, and No. 61/809,423, filed on
Apr. 8, 2013, the contents of which are hereby incorporated by
reference herein in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a wireless communication,
and more particularly, to a method of supporting signal
transmission and reception using at least two radio access
technologies (RATs) and apparatus therefor.
[0004] 2. Discussion of the Related Art
[0005] There may exist a multi-RAT user equipment having capability
of accessing at least two radio access technologies (RATs). In
order to access a specific radio access technology (hereinafter
abbreviated RAT), a connection to the specific RAT is established
on the basis of a user equipment request and data transmission and
reception can be then performed. Yet, even if the multi-RAT user
equipment is capable of accessing at least two RATs, it is unable
to access a plurality of RATs at the same time. In particular,
currently, even if a user equipment has multi-RAT capability, it is
unable to simultaneously perform data transmission/reception
through different RATs.
[0006] The above-mentioned multi-RAT technology of the related art
is a switching based multi-RAT technology. Since all transmitted
data are transmitted in a manner of being switched to another RAT,
the related art multi-RAT technology has a problem in selecting an
RAT suitable for characteristics of a flow. However, a solution for
this problem has not been proposed yet.
SUMMARY OF THE INVENTION
[0007] Accordingly, embodiments of the present invention are
directed to a method of supporting signal transmission and
reception using at least two radio access technologies (RATs) and
apparatus therefor that substantially obviate one or more problems
due to limitations and disadvantages of the related art.
[0008] One object of the present invention is to provide a method
for a user equipment to support signal transmission and reception
using at least two radio access technologies (RATs).
[0009] Another object of the present invention is to provide a
method for a base station to support signal transmission and
reception using at least two radio access technologies (RATs).
[0010] Another object of the present invention is to provide a user
equipment configured to support signal transmission and reception
using at least two radio access technologies (RATs).
[0011] A further object of the present invention is to provide a
base station configured to support signal transmission and
reception using at least two radio access technologies (RATs).
[0012] Technical tasks obtainable from the present invention are
non-limited by the above-mentioned technical task. And, other
unmentioned technical tasks can be clearly understood from the
following description by those having ordinary skill in the
technical field to which the present invention pertains.
[0013] Additional advantages, objects, and features of the
invention will be set forth in the disclosure herein as well as the
accompanying drawings. Such aspects may also be appreciated by
those skilled in the art based on the disclosure herein.
[0014] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a method of supporting signal
transmission and reception, by a user equipment, using at least two
radio access technologies (RATs), according to one embodiment of
the present invention may include the steps of when the user
equipment is simultaneously accessing a 1.sup.st base station of a
1.sup.st communication network supportive of a 1.sup.st RAT and a
2.sup.nd base station of a 2.sup.nd communication network
supportive of a 2.sup.nd RAT, receiving a setup message indicating
a termination of a connection to the 2.sup.nd base station from the
1.sup.st base station and terminating the connection to the
2.sup.nd base station, wherein before the connection to the
2.sup.nd base station is terminated, the user equipment transceives
data for a specific traffic type via the 2.sup.nd base station and
also transceives data except the specific traffic type via the
1.sup.st base station and wherein if the connection to the 2.sup.nd
base station is terminated, the user equipment transceives the data
for the specific traffic type via the 1.sup.st base station.
[0015] In another aspect of the present invention, a method of
supporting signal transmission and reception, by a 1.sup.st base
station of a 1.sup.st communication network supportive of a
1.sup.st RAT (radio access technology), using at least two radio
access technologies (RATs), according to another embodiment of the
present invention may include the steps of sending a setup message
indicating a termination of a connection to a 2.sup.nd base station
to the user equipment currently accessing both of the 1.sup.st base
station and the 2.sup.nd base station of a 2.sup.nd communication
network supportive of a 2.sup.nd RAT and receiving a complete
message for reporting a success or failure in the termination of
the connection to the 2.sup.nd base station from the user
equipment, wherein the 1.sup.st base station redirects data for a
specific traffic type among data to be transmitted to the user
equipment into the 2.sup.nd base station and also transmits the
data except the specific traffic type to the user equipment in
direct and wherein if the connection between the user equipment and
the 2.sup.nd base station is terminated, the 1.sup.st base station
transmits the data for the specific traffic type to the user
equipment in direct.
[0016] In another aspect of the present invention, in supporting
signal transmission and reception using at least two radio access
technologies (RATs), a user equipment according to another
embodiment of the present invention may include a communication
unit and a processor, when the communication unit is simultaneously
accessing a 1.sup.st base station of a 1.sup.st communication
network supportive of a 1.sup.st RAT and a 2.sup.nd base station of
a 2.sup.nd communication network supportive of a 2.sup.nd RAT,
controlling the communication unit to receive a setup message
indicating a termination of a connection to the 2.sup.nd base
station from the 1.sup.st base station, the processor controlling
the communication unit to terminate the connection to the 2.sup.nd
base station, the processor, before the connection to the 2.sup.nd
base station is terminated, controlling data for a specific traffic
type to be transceived via the 2.sup.nd base station and also
controlling data except the specific traffic type to be transceived
via the 1.sup.st base station, the processor, if the connection to
the 2.sup.nd base station is terminated, controlling the data for
the specific traffic type to be transceived via the 1.sup.st base
station.
[0017] In a further aspect of the present invention, in supporting
signal transmission and reception using at least two radio access
technologies (RATs), a base station, which belongs to a 1.sup.st
communication network supportive of a 1.sup.st RAT (radio access
technology), according to a further embodiment of the present
invention may include a communication unit and a processor
controlling the communication unit to send a setup message
indicating a termination of a connection to a 2.sup.nd base station
to a user equipment currently accessing both of the communication
unit and the 2.sup.nd base station of a 2.sup.nd communication
network supportive of a 2.sup.nd RAT, a processor controlling the
communication unit to receive a complete message for reporting a
success or failure in the termination of the connection to the
2.sup.nd base station from the user equipment, the processor
redirecting data for a specific traffic type among data to be
transmitted to the user equipment into the 2.sup.nd base station
and also transmitting the data except the specific traffic type to
the user equipment in direct, the processor, if the connection
between the user equipment and the 2.sup.nd base station is
terminated, transmitting the data for the specific traffic type to
the user equipment in direct.
[0018] Accordingly, the present invention provides the following
effects and/or advantages.
[0019] First of all, according to various embodiments of the
present invention, a user equipment capable of supporting both
Cellular and WLAN in a broadband wireless communication system can
efficiently perform a heterogeneous selection for a flow through a
control of a cellular network.
[0020] Secondly, according to various embodiments of the present
invention, in a broadband wireless communication system, a
multi-RAT access method of a non-switching type can be
provided.
[0021] Effects obtainable from the present invention may be
non-limited by the above mentioned effect. And, other unmentioned
effects can be clearly understood from the following description by
those having ordinary skill in the technical field to which the
present invention pertains.
[0022] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] 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. The above and other aspects,
features, and advantages of the present invention will become more
apparent upon consideration of the following description of
preferred embodiments, taken in conjunction with the accompanying
drawing figures. In the drawings:
[0024] FIG. 1 is a block diagram for configurations of a base
station 105 and a user equipment 110 in a wireless communication
system 100;
[0025] FIG. 2 is a diagram for one example of a network structure
to describe an interoperating structure of a first communication
system (e.g., LTE system) and a second communication system (e.g.,
WiFi system);
[0026] FIG. 3A and FIG. 3B are diagrams for examples to describe
scenarios according to the present invention;
[0027] FIG. 4 is a diagram for one example to describe a
multi-system capability related negotiation procedure according to
the present invention;
[0028] FIG. 5 is a diagram for one example to describe traffic
characteristics in LTE system;
[0029] FIG. 6 is a diagram to describe a system selecting method
using QoS class defined in LTE;
[0030] FIG. 7 is a diagram for one example to describe a
measurement gap in LTE system;
[0031] FIG. 8 is a flowchart of a process for a UE to report a
measurement result to an eNB;
[0032] FIG. 9 is a diagram for one example to describe a
measurement object and a report configuration for a measurement
result;
[0033] FIG. 10 is a diagram of enumerated trigger conditions;
[0034] FIG. 11 is a flowchart to describe a message defined for a
secondary system management procedure;
[0035] FIG. 12 is a flowchart to describe an additional procedure
of a secondary system;
[0036] FIG. 13 is a flowchart to describe a changing procedure of a
secondary system; and
[0037] FIGS. 14A to 14C are flowcharts to describe a deleting
procedure of a secondary system.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. In the following detailed
description of the invention includes details to help the full
understanding of the present invention. Yet, it is apparent to
those skilled in the art that the present invention can be
implemented without these details. For instance, although the
following descriptions are made in detail on the assumption that a
mobile communication system includes 3GPP LTE/LTE-A system, the
following descriptions are applicable to other random mobile
communication systems in a manner of excluding unique features of
the 3GPP LTE/LTE-A.
[0039] Occasionally, to prevent the present invention from getting
vaguer, structures and/or devices known to the public are skipped
or can be represented as block diagrams centering on the core
functions of the structures and/or devices. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0040] Besides, in the following description, assume that a
terminal is a common name of such a mobile or fixed user stage
device as a user equipment (UE), a mobile station (MS), an advanced
mobile station (AMS) and the like. And, assume that a base station
(BS) is a common name of such a random node of a network stage
communicating with a terminal as a Node B (NB), an eNode B (eNB),
an access point (AP) and the like. Although the present
specification is described based on IEEE 802.16 system, contents of
the present invention may be applicable to various kinds of other
communication systems.
[0041] In a mobile communication system, a user equipment is able
to receive information in downlink and is able to transmit
information in uplink as well. Informations transmitted or received
by the user equipment node may include various kinds of data and
control informations. In accordance with types and usages of the
informations transmitted or received by the user equipment, various
physical channels may exist.
[0042] The following descriptions are usable for various wireless
access systems including CDMA (code division multiple access), FDMA
(frequency division multiple access), TDMA (time division multiple
access), OFDMA (orthogonal frequency division multiple access),
SC-FDMA (single carrier frequency division multiple access) and the
like. CDMA can be implemented by such a radio technology as UTRA
(universal terrestrial radio access), CDMA 2000 and the like. TDMA
can be implemented with such a radio technology as GSM/GPRS/EDGE
(Global System for Mobile communications)/General Packet Radio
Service/Enhanced Data Rates for GSM Evolution). OFDMA can be
implemented with such a radio technology as IEEE 802.11 (Wi-Fi),
IEEE 802.16 (WiMAX), IEEE 802.20, E-UTRA (Evolved UTRA), etc. UTRA
is a part of UMTS (Universal Mobile Telecommunications System).
3GPP (3rd Generation Partnership Project) LTE (long term evolution)
is a part of E-UMTS (Evolved UMTS) that uses E-UTRA. The 3GPP LTE
adopts OFDMA in DL and SC-FDMA in UL. And, LTE-A (LTE-Advanced) is
an evolved version of 3GPP LTE.
[0043] Moreover, in the following description, specific
terminologies are provided to help the understanding of the present
invention. And, the use of the specific terminology can be modified
into another form within the scope of the technical idea of the
present invention.
[0044] FIG. 1 is a block diagram for configurations of a base
station 105 and a user equipment 110 in a wireless communication
system 100.
[0045] Although one base station 105 and one user equipment 110
(D2D user equipment included) are shown in the drawing to
schematically represent a wireless communication system 100, the
wireless communication system 100 may include at least one base
station and/or at least one user equipment.
[0046] Referring to FIG. 1, a base station 105 may include a
transmitted (Tx) data processor 115, a symbol modulator 120, a
transmitter 125, a transceiving antenna 130, a processor 180, a
memory 185, a receiver 190, a symbol demodulator 195 and a received
(Rx) data processor 197. And, a user equipment 110 may include a
transmitted (Tx) data processor 165, a symbol modulator 170, a
transmitter 175, a transceiving antenna 135, a processor 155, a
memory 160, a receiver 140, a symbol demodulator 155 and a received
(Rx) data processor 150. Although the base station/user equipment
105/110 includes one antenna 130/135 in the drawing, each of the
base station 105 and the user equipment 110 includes a plurality of
antennas. Therefore, each of the base station 105 and the user
equipment 110 of the present invention supports an MIMO (multiple
input multiple output) system. And, the base station 105 according
to the present invention may support both SU-MIMO (single
user-MIMO) and MU-MIMO (multi user-MIMO) systems.
[0047] In downlink, the transmitted data processor 115 receives
traffic data, codes the received traffic data by formatting the
received traffic data, interleaves the coded traffic data,
modulates (or symbol maps) the interleaved data, and then provides
modulated symbols (data symbols). The symbol modulator 120 provides
a stream of symbols by receiving and processing the data symbols
and pilot symbols.
[0048] The symbol modulator 120 multiplexes the data and pilot
symbols together and then transmits the multiplexed symbols to the
transmitter 125. In doing so, each of the transmitted symbols may
include the data symbol, the pilot symbol or a signal value of
zero. In each symbol duration, pilot symbols may be contiguously
transmitted. In doing so, the pilot symbols may include symbols of
frequency division multiplexing (FDM), orthogonal frequency
division multiplexing (OFDM), or code division multiplexing
(CDM).
[0049] The transmitter 125 receives the stream of the symbols,
converts the received stream to at least one or more analog
signals, additionally adjusts the analog signals (e.g.,
amplification, filtering, frequency upconverting), and then
generates a downlink signal suitable for a transmission on a radio
channel. Subsequently, the downlink signal is transmitted to the
user equipment via the antenna 130.
[0050] In the configuration of the user equipment 110, the
receiving antenna 135 receives the downlink signal from the base
station and then provides the received signal to the receiver 140.
The receiver 140 adjusts the received signal (e.g., filtering,
amplification and frequency downconverting), digitizes the adjusted
signal, and then obtains samples. The symbol demodulator 145
demodulates the received pilot symbols and then provides them to
the processor 155 for channel estimation.
[0051] The symbol demodulator 145 receives a frequency response
estimated value for downlink from the processor 155, performs data
demodulation on the received data symbols, obtains data symbol
estimated values (i.e., estimated values of the transmitted data
symbols), and then provides the data symbols estimated values to
the received (Rx) data processor 150. The received data processor
150 reconstructs the transmitted traffic data by performing
demodulation (i.e., symbol demapping, deinterleaving and decoding)
on the data symbol estimated values.
[0052] The processing by the symbol demodulator 145 and the
processing by the received data processor 150 are complementary to
the processing by the symbol modulator 120 and the processing by
the transmitted data processor 115 in the base station 105,
respectively.
[0053] In the user equipment 110 in uplink, the transmitted data
processor 165 processes the traffic data and then provides data
symbols. The symbol modulator 170 receives the data symbols,
multiplexes the received data symbols, performs modulation on the
multiplexed symbols, and then provides a stream of the symbols to
the transmitter 175. The transmitter 175 receives the stream of the
symbols, processes the received stream, and generates an uplink
signal. This uplink signal is then transmitted to the base station
105 via the antenna 135.
[0054] In the base station 105, the uplink signal is received from
the user equipment 110 via the antenna 130. The receiver 190
processes the received uplink signal and then obtains samples.
Subsequently, the symbol demodulator 195 processes the samples and
then provides pilot symbols received in uplink and a data symbol
estimated value. The received data processor 197 processes the data
symbol estimated value and then reconstructs the traffic data
transmitted from the user equipment 110.
[0055] The processor 155/180 of the user equipment/base station
110/105 directs operations (e.g., control, adjustment, management,
etc.) of the user equipment/base station 110/105. The processor
155/180 may be connected to the memory unit 160/185 configured to
store program codes and data. The memory 160/185 is connected to
the processor 155/180 to store operating systems, applications and
general files.
[0056] The processor 155/180 may be called one of a controller, a
microcontroller, a microprocessor, a microcomputer and the like.
And, the processor 155/180 may be implemented using hardware,
firmware, software and/or any combinations thereof. In the
implementation by hardware, the processor 155/180 may be provided
with one of ASICs (application specific integrated circuits), DSPs
(digital signal processors), DSPDs (digital signal processing
devices), PLDs (programmable logic devices), FPGAs (field
programmable gate arrays), and the like.
[0057] Meanwhile, in case of implementing the embodiments of the
present invention using firmware or software, the firmware or
software may be configured to include modules, procedures, and/or
functions for performing the above-explained functions or
operations of the present invention. And, the firmware or software
configured to implement the present invention is loaded in the
processor 155/180 or saved in the memory 160/185 to be driven by
the processor 155/180.
[0058] Layers of a radio protocol between a user equipment and an
base station may be classified into first layer L1, second layer L2
and third layer L3 based on 3 lower layers of OSI (open system
interconnection) model well known to communication systems. A
physical layer belongs to the first layer and provides an
information transfer service via a physical channel. RRC (radio
resource control) layer belongs to the third layer and provides
control radio resourced between UE and network. A user equipment
and a base station may be able to exchange RRC messages with each
other via radio communication layer and RRC layers.
[0059] In the present specification, the processor 155 of the user
equipment 110 performs operations of processing signals and data
except a signal transceiving function of the user equipment 110 and
a storing function of the user equipment 110. And, the processor
180 of the base station 105 performs operations of processing
signals and data except a signal transceiving function of the user
equipment 110 and a storing function of the user equipment 110.
Yet, for clarity of the following description, the processors 155
and 180 shall not be mentioned overall. Although the processor
155/180 is not mentioned specially, the processor 155/180 can be
regarded as performing a series of operations including data
processing and the like except a signal transceiving function and a
storing function.
[0060] The present invention proposes a method for a user
equipment, which supports both a cellular network and a wireless
LAN network (e.g., WLAN) in a broadband wireless communication
system, to efficiently perform a heterogeneous network selection
for a flow through a control of the cellular network.
[0061] FIG. 2 is a diagram for one example of a network structure
to describe an interoperating structure of a first communication
system (e.g., LTE system) and a second communication system (e.g.,
WiFi system).
[0062] In the network structure shown in FIG. 2, a backhaul control
connection is established between an AP and an eNB through a
backbone network (e.g., P-GW, EPC (evolved packet core), etc.) or a
wireless control connection may be established between the AP and
the eNB. For peak throughput and data traffic off-loading, a user
equipment (hereinafter abbreviated UE) is able to support both a
first communication system (or a first communication network) using
a first wireless communication scheme and a second communication
system (or a second communication network) using a second
communication scheme through interoperations among a plurality of
communication networks. In this case, the first communication
network and the first communication system can be named a primary
network and a primary system, respectively. The second
communication network and the second communication system can be
named a secondary network and a secondary communication system,
respectively. For instance, the UE can be configured to
simultaneously support LTE (or LTE-A) and WiFi (e.g., a short range
communication system such as WLAN, 802.11, etc.). Such a UE can be
named a multi-system capability UE in the present
specification.
[0063] In the network structure shown in FIG. 2, the primary system
has a wider coverage and may include a network for control
information transmission. For example, the primary system may
include one of WiMAX system, LTE system and the like. On the other
hand, the secondary system is a network having a smaller coverage
and may include a system for data transmission. For example, the
secondary network may include a wireless LAN system such as WLAN,
WiFi and the like.
[0064] FIG. 3A and FIG. 3B are diagrams for examples to describe
scenarios according to the present invention.
[0065] FIG. 3A shows a first scenario having a backhaul control
connection established between an AP and an eNB (i.e., a base
station) via a backbone network. And, FIG. 3B shows a second
scenario capable of a direct communication owing to a wireless
control connection established between an AP and an eNB. In aspect
of the eNB in each of the scenarios, the AP of a secondary system
may look like an entity operating in a manner identical to that of
a UE having LTE capability.
[0066] In the following description, definitions related to a
multi-RAT system of the present invention are explained.
[0067] Primary System
[0068] A primary system (e.g., WiMAX, LTE network, etc.) is a
system having a wider coverage. And, the primary system means a
network in a connected state in a network having a constant status
(or RRC connection) with a multi-system capability UE or a network
in a DRX (discontinuous reception) or idle status.
[0069] A multi-system capability UE can send an indication, which
indicates that the multi-system capability UE has capability for a
heterogeneous network (e.g., WLAN, etc.), to an eNB of a primary
system during a connection establishment with a primary network. In
this case, the indication of the multi-system capability can be
transmitted in a manner of being included as a new field in
RRCConnectionRequest or RRCConnectionSetup message. If the
indication of the multi-system capability is set to 1, a UE and an
eNB can share capability necessary for a multi-system through a
specific procedure for the multi-system capability UE.
[0070] An eNB of a primary system can periodically transmit
information on another system (secondary systems) belonging to the
same coverage for multi-system UEs using a broadcast message or a
unicast message. If deployment of a secondary system is changed, it
is able to send an updated message to indicate
added/deleted/changed information of the secondary system.
[0071] Secondary System
[0072] A secondary system is a system having a small coverage and
may include one of WLAN system, WiFi system and the like for
example. The secondary system is the system that may be added or
deleted if necessary. The secondary system may be mainly used for
data transmission and reception that requires higher bandwidth
(BW). In doing so, a specific flow (QoS) may be mapped.
[0073] A connection or release between a secondary system and a UE
is possible after confirmation from a primary system. In this case,
the connection between a secondary system and a UE may mean that it
is ready to transmit/receive data or that data is
transmitted/received.
[0074] If it is detected that a UE has entered a secondary system
coverage, information on an access to a secondary system can be
received through a primary system. In doing so, actual data
transmission/reception may not occur instantly.
[0075] If a UE has data to transmit/receive via a secondary system,
it is able to receive access information on a corresponding flow
through a primary system. In doing so, actual data
transmission/reception may occur instantly.
[0076] FIG. 4 is a diagram for one example to describe a
multi-system capability related negotiation procedure according to
the present invention.
[0077] FIG. 4 is provided for UE capability negotiation on the
basis of LTE and shows a process for an eNB, which has capability
for a heterogeneous network interoperating technology such as a
wireless LAN, to receive a heterogeneous network related
information of a UE by sending UECapabilityEnquiry message to the
UE.
[0078] Referring to FIG. 4, a UE (i.e., a multi-system capability
UE) performs an initial network entry procedure with a primary
system (i.e., an eNB of the primary system) [S410]. In particular,
the UE performs an initial connection establishment with the
primary system. In case that the primary system includes an LTE
system, the UE performs an initial RRC (radio resource control)
connection establishment of the previous LTE. In the initial
network entry procedure, the corresponding UE can inform a base
station that the corresponding UE is the multi-system or multi-RAT
capability UE. For instance, the UE can send the corresponding
indication to the base station through RRCConnectionRequest message
or in the course of RRCConnectionSetup procedure. In particular,
such a parameter (e.g., 1-bit size) as `MultiRATAccessAvaialble`
can be transmitted in a manner of being added to the
RRCConnectionRequest message or the RRCConnectionSetup
procedure.
[0079] If there is a common information, which should be received
by the UE, of a base station (hereinafter called an AP (access
point)) of a secondary system, a base station (hereinafter called
an eNB) of the primary system can transmit an information on the
secondary system to the UE [S420].
[0080] On the other hand, unlike the description of the step S410
with reference to FIG. 4, the multi-system (or multi-RAT)
capability negotiation may be performed after the initial
connection establishment.
[0081] In case of a connection reestablishment, the multi-system
(or multi-RAT) capability negotiation may be skipped. In case of a
handover, a target eNB can perform a pre-negotiation through a
backbone network from a serving eNB. After the UE has entered
RRC-IDLE state, the eNB can store the multi-system capability of
the UE for predetermined duration. If a network reconfiguration is
performed before multi-system information retain timeout, the
negotiation can be omitted.
[0082] The eNB can send a message, which queries the capability of
the UE (e.g., whether the UE is capable of accessing the
multi-system or the multi-RAT simultaneously, whether the UE is
capable to simultaneously accessing a prescribed system and a
prescribed RAT, etc.), to the UE [S430]. This message can be named
`UECapabilityEnquiry`. As a UE-CapabilityRequest parameter is added
to the UECapabilityEnquiry message, the UECapabilityEnquiry is sent
with a content of the added parameter to query whether the UE is
capable of supporting the multi-system or the multi-RAT
simultaneously or whether the UE is capable of supporting a
prescribed system. In this case, the UE-CapabilityRequest parameter
can be transmitted in a manner of including a parameter about such
a new radio access technology (RAT) (i.e., an unlicensed band) as
WiFi, WLAN, 802.11 and the like.
[0083] In response to the UECapabilityEnquiry message, the UE sends
a UECapabilityInformation message to the eNB [S440]. This
UECapabilityInformation message may contain WiFi related capability
information for example.
[0084] The UECapabilityInformation message may include an indicator
indicating capability of simultaneously accessing a plurality of
radio access technologies or system types and information on
supportable radio access technologies or system types. For
instance, if the supportable ratio access technology includes WiFi,
the UECapabilityInformation message can contain 802.11 MAC address
(for authentication information) of the UE in addition. The
UECapabilityInformation message can contain a previously accessed
AP information (UE's preferred AP). And, the information is
preferably transmitted to the eNB to which the previously accessed
AP belongs. And, the UECapabilityInformation message can
additionally contain Protocol Version (11a/b/n . . . ) information
and information on a type or characteristic (e.g., EPS bearer QoS
type) of a traffic desired to be transmitted or received via WLAN.
This information of the traffic type or characteristic shall be
described in detail later.
[0085] Thus, as the UE and the eNB exchange the UECapabilityEnquiry
message and the UECapabilityInformation message with each other,
the following content shown in Table 1 needs to be additionally
included in the previous standard specification 3GPP TS 36.331.
TABLE-US-00001 TABLE 1 5.6.3.3 Reception of the UECapabilityEnquiry
by the UE (3GPP TS 36.331) The UE shall: 1> set the contents of
UECapabilityInformation message as follows: 2> if the
ue-CapabilityRequest includes wifi and if the UE supports WiFi (or
WLAN or 802.11x) domain : 3> include the UE radio access
capabilities for WiFi within a ue-CapabilityRAT-Container and with
the rat-Type set to WiFi (or WLAN or 802.11x); 1> submit the
UECapabilityInformation message to lower layers for transmission,
upon which the procedure ends
[0086] Having received the supportable radio access technology or
system type information through the UECapabilityInformation
message, the eNB sends UECapabilityComplete or UECapabilityResponse
message [S450]. In this case, the UECapabilityComplete or
UECapabilityResponse message can contain candidate APs
information.
[0087] In the case shown in FIG. 4, only if a previous
UECapabilityEnquiry message is sent (1 step), the UE sends the
UECapabilityInformation message (2 step). In this case, the eNB can
send the UECapabilityComplete message in response to the
UECapabilityInformation message (3 step), which is an optional
step. Hence, the MultiRAT capability negotiation procedure can
include 2 or 3 steps.
[0088] Alternatively, the MultiRAT capability negotiation procedure
can be configured to include 1 or 2 steps. In particular, without a
previous UECapabilityEnquiry message, the UECapabilityInformation
can be sent to the eNB in an unsolicited manner under the decision
made by the UE (1 step). In this case, the eNB may send
UECapabilityComplete message to the UE in response to the
UECapabilityInformation message (optional) (2 steps).
[0089] After the step S450, the UE can exchange data with the eNB
[S460]. Based on the candidate AP list (or APs) received in the
step S450, the UE can select the AP by performing a secondary
system scanning [S470]. After the scanning, the UE can perform a
secondary system management [S480]. In this case, there is a
trigger condition for a secondary system (e.g., AP) measurement.
Prior to describing the definition of the trigger condition, QoS
(quality of service) indicating a traffic state is schematically
described with reference to 3GPP LTE system for example.
[0090] FIG. 5 is a diagram for one example to describe traffic
characteristics in LTE system.
[0091] Referring to FIG. 5, if a UE accesses an LTE network, EPS
(evolved packet system) Bearer is generated from the UE to P-GW
(i.e., UE-eNB-S-GW-P-GW) [GTP type tunnel]. In particular, a
plurality of EPS Bearers can be generated depending on each service
property. For instance, Internet EPS Bearer, IPTV EPS Bearer, VoIP
EPS Bearer and the like can be generated. Properties of Default EPS
Bearer and Dedicated EPS Bearer are described as follows.
[0092] Default EPS Bearer--QoS property of Default EPS Bearer
includes Non-GBR (Non-Guaranteed Bit Rate), e.g., Internet
service.
[0093] Dedicated EPS Bearer--Dedicated EPS Bearer may be generated
at GBR or Non-GBR. For instance, Dedicated EPS Bearer for VoD
service is generated at GBR.
[0094] LTE QoS is described in brief as follows.
[0095] First of all, a previous LTE enables traffic characteristics
to be defined on a network level (i.e., P-GW). In particular, the
P-GW defines 5-tuple Service Data Flow and an eNB defines GBR or
Non-GBR.
[0096] PDN connection: IP connection between UE and PDN (UE is
identified with IP address, while PDN is identified with APN).
[0097] EPS session: Having the same meaning of PDN connection. This
session has at least one EPS bearer. If IP address is assigned to a
UE, this session is maintained as long as the UE is connected to an
IP network.
[0098] EPS bearer: A delivery path established between UE and P-GW
to transmit IP traffic with specific QoS. Each EPS bearer is
configured with QoS parameters indicating property of the delivery
path.
[0099] Default bearer: This is EPS bearer newly generated when a
new PDN connection is established. This bearer is maintained until
the PDN connection is terminated. This bearer is always configured
at non-GBR.
[0100] Dedicated Bearer: This is EPS bearer generated on demand
additionally after PDN connection establishment. Corresponding to
GBR or non-GBR.
[0101] SDF (Service Data Flow): IP flow corresponding to a service
or a set of IP flows. This flow is identified by an IP of packet
and TCP/UDP header. A different QoS is applied per SDF and PCC
rules are applied by PCRF. This flow is delivered on EPS bearer
that meets QoS of SDF. Several SDFs may be mapped to the same EPS
bearer. User traffic has a different QoS property depending on
using what kind of service or application. SDF is an IP flow
generated from filtering user traffic per service or a set of IP
flows. And, a specific QoS policy is applied in accordance with a
subscriber level of UE and a used service. IP flows toward a user
are sorted into SDF through SDF template (classifier) in accordance
with service property and are then delivered to a user in a manner
of having QoS policy (e.g., bandwidth control) applied thereto per
SDF. On EPS delivery network, QoS is transmitted in a manner of
being mapped to EPS bearer.
[0102] EPS bearer: As mentioned in the foregoing description, EPS
bearers can be sorted into a default type and a dedicated type. If
a UE accesses an LTE network, an IP address is assigned to the UE.
Then, the UE establishes a PCN connection as soon as EPS bearer is
generated. While the UE uses a service (e.g., Internet) through
default bearer, if the UE uses another service (e.g., VoD) that
cannot be provided through the default bearer, dedicated bearer is
generated by on-demand. In particular, the dedicated bearer is
configured by QoS different from that of a previously configured
bearer. UE can access several APNs. And, one default EPS bearer and
sever dedicated EPS bearers can be configured per APN. Maximum 11
EPS bearers can be configured.
[0103] Default bearer is generated when a UE initially accesses a
network. The default bearer keeps being maintained even if a
service is not used in the meantime. The default bearer then
disappears when the UE leaves the network. One default bearer is
generated per PAN. How to generate a default bearer by applying
which QoS to a prescribed APN in case of an initial access to a
network is provisioned as a user's subscription information in HSS.
If a UE initially accesses a network, an MME downloads user's
subscription information from an HSS and then generates default
bearer with a corresponding PDN using subscriber QoS profile.
[0104] SDF QoS: QCI (QoS Class Identifier) and ARP (Allocation and
Retention Priority) are basic parameters applied to all SDFs. QCI
is an expression with integer values (1 to 9) by standardizing
different QoS properties. And, the standardized QoS properties can
be represented as resource type, priority, packet delay budget,
packet error loss rate and the like. The SDF can be categorized
into a GBR type SDF having a network resource allocated fixedly or
a non-GBR type SDF having a network resource not allocated fixedly
in accordance with a resource type. Besides QCI and ARP, GBR
(Guaranteed Bit Rate) and MBR (Maximum Bit Rate) are assigned as
QoS parameters to the GBR type SDF and MBR is assigned to the
non-GBR type SDF.
[0105] GBR type SDF QoS parameter: QCI, ARP, GBR (DL/UL), MBR
(DL/UL)
[0106] Non-GBR type SDF QoS parameter: QCI, ARP, MBR (DL/UL)
[0107] SDF is mapped to EPS bearer by P-GW and is then delivered to
UE through the EPS bearer. SDFs (SDF aggregate) having the same QCI
and ARP are mapped to one EPX bearer.
[0108] EPS Bearer QoS: QCI and ARP are basic QoS parameters applied
to all EPS bearers. EPS bearer is categorized into GBR type bearer
or non-GBR type bearer in accordance with QCI resource type. A
default bearer is always non-GBR type and a dedicated bearer may be
set to GBR or non-GBR. GBR type bearer QoS parameters may include
QCI, ARP, GBR (DL/UL), and MBR (DL/UL). Non-GBR type bearer QoS
parameters may include QCI, ARP, APN-AMBR (DL/UL), and UE-AMBR
(DL/UL).
[0109] Besides QCI and ARP, the GBR type bearer has GBR and MBR as
QoS parameters, which means that a fixed resource is allocated per
bearer. On the other hand, the non-GBR type bearer has AMBR
(Aggregated Maximum Bit Rate) as QoS parameter, which means that a
maximum bandwidth usable together with other non-GBR type bearers
is assigned instead of receiving resource application per bearer.
APN-AMBR is a maximum bandwidth that can be shared within the same
PDN by non-GBR type bearers and UE-AMBR is a maximum bandwidth
sharable within the same UE. In case that UE has several PDN
connections, a sum of APN-AMBRs of the PDNs cannot exceed
UE-AMBR.
[0110] In the following description, definition of a trigger
condition for a secondary system (e.g., AP) measurement is
explained. In particular, a trigger condition for a UE to initiate
other RAT measurement is described.
[0111] (1) A condition for a UE to start a measurement of neighbor
AP in a step of not starting a measurement can be determined by a
traffic transmitted on radio resource configuration) (e.g., DRB
(Data Radio Bearer) addition. The condition may be determined in
accordance with GBR, non-GBR or a new EPS bearer QoS type defined
by the present invention. If a traffic desired to be transmitted
via AP in case of Multi-RAT Capability Negotiation (S410, or S420
to S450) is defined and is generated through radio resource
configuration, the UE can start the AP measurement.
[0112] (2) If IEEE 802.11 (WLAN, AP) is selected as a preferred
system in radio resource configuration, a UE can start a
measurement of neighbor AP.
[0113] Meanwhile, a metric for starting a measurement can be
transmitted as a UE-specific value to a UE by an eNB through a
unicast message. In the following description, a traffic type used
to determine a trigger condition for a secondary system (e.g., AP)
measurement is explained.
[0114] Traffic Characteristics in LTE
[0115] As traffics transmitted on a cellular network are
diversified, if an eNB is aware of traffic characteristics and
processes radio bearers appropriately, it may help enhancement of
total system performance. Yet, a current LTE system discriminates a
service data flow (SDF) on APN (p-GW) level only in accordance with
a specific QoS policy, defines a QoS level, and then provides a
service appropriate for it.
[0116] P-GW SDF-QoS-defines a service data flow sorted by 5-tuple
(Source IP, Destination IP, Source Port number, Destination Port
number, Protocol ID) in accordance with a QoS policy. The SDF QoS
is mapped again to EPS bearer QoS. Currently, there are two types
(default, dedicated) of EPS bearers in LTE.
[0117] Referring to FIG. 5, an eNB or LTE system defines LTE EPS
bearer on a sub-divided QoS level using the corresponding SDF QoS
definition and the eNB can provide a different service for each of
the types. To this end, like SDF QoS, EPS bearers can be sorted by
the following types (EPS bearer QoS types).
[0118] Ex.) voice (Conversational Real Time service), streaming
video (streaming real time service), web browsing (Interactive BE
service), telemetry/emails (Background BE service)
[0119] EPS Bearer type 1: This type corresponds to a default EPS
bearer that is basically generated when a connection is
established.
[0120] EPS Bearer type 2: Best Effort Service type
[0121] EPS Bearer type 3: Real time service
[0122] . . .
[0123] EPS Bearer type n: Streaming video service
[0124] FIG. 6 is a diagram to describe a system selecting method
using QoS class defined in LTE.
[0125] Referring to FIG. 6, steps S605 to S630 sequentially
correspond to the former steps S410 to S460 shown in FIG. 4,
respectively. And, the contents of the S410 to S460 described with
reference to FIG. 4 can be applied to the steps S605 to S630.
[0126] Subsequently, a UE can receive an RRC connection
reconfiguration message (e.g., RRCConnectionReconfiguration
message) from an eNB [S635]. A data radio bearer (DRB) can be
transmitted in a manner of being added to the RRC connection
reconfiguration message. As mentioned in the foregoing description
of the trigger condition (1) for the UE to initiate measurement of
a different radio access technology, whether to trigger a
measurement of neighbor AP can be determined by a traffic type
transmitted through the radio resource configuration (e.g., DRB
addition). And, the trigger condition may be determined in
accordance with GBR, Non-GBR, or a new EPS bearer QoS type (or
traffic type) defined by a technology of the invention.
[0127] Thus, if a type of a traffic transmitted by being included
in the RRCConnectionReconfiguration message corresponds to a
traffic type that meets the trigger condition, the UE can perform a
measurement on a base station (e.g., neighbor APs (AP1, AP2, AP3)
shown in FIG. 6) that uses a different radio access technology
[S640]. Thereafter, the UE reports a result of the measurement to
the eNB [S645].
[0128] System Selecting Method Using QoS Class Defined in LTE
[0129] The technology of the present invention enables an eNB (or
such a network entity as MultiRAT Management entity) to select a
system appropriate for a traffic using EPS bearer type defined in
the foregoing description. It may be difficult to select an
appropriate system using the previous classification reference
(i.e., GBR, non-GBR) for data flow. The technology of the present
invention can determine an eNB to transmit a specific traffic type
(or specific flow(s)) to a network (e.g., WLAN, i.e., a secondary
system), which uses a radio access technology different from that
of an LTE network in accordance with information received from a UE
using the EPS bearer type defined in the foregoing description. To
this end, the eNB delivers the traffic, which was transmitted in
the step S620 and corresponds to a traffic type desired to be
received via WLAN, to the AP. Subsequently, the UE receives the
traffic, which corresponds to the traffic type desired to be
received via the WLAN, from the AP and is also able to receive a
traffic corresponding to another traffic type via LTE network at
the same time.
[0130] If a network entity or eNB below S-GW manages flows of a
multi-RAT UE, an RAT selection for a traffic (or flow) of the UE is
performed in a following manner. First of all, an eNB receives
information on a network (e.g., a secondary system), which uses a
different radio access technology, from the UE. Secondly, the eNB
analyzes the received information in a manner of comparing it to
information on a serving cell (i.e., a cell in a currently
connected primary system). Finally, the eNB selects an RAT for
maximizing overall system performance. According to the present
invention, the eNB is assumed as becoming a subject for the
selection.
[0131] If a network entity above P-GW is capable of managing RAT of
a UE, the corresponding network entity should be able to receive
state information of the UE and state information of a
heterogeneous network such as a cellular network, WLAN and the
like. When traffic characteristics desired to be transmitted via
wireless LAN (i.e., an access capable RAT in accordance with
capability of UE) are shared between a UE and an eNB in case of
multi-RAT capability negotiation, if a specific traffic is
generated and corresponds to a traffic preferred to be transmitted
via the wireless LAN (i.e., secondary system), the eNB controls a
state of the wireless LAN (i.e., secondary system) to be searched
using the above information.
[0132] Measurement Report
[0133] A data connection transmitted from an eNB to a UE is
established by an RRC (radio resource configuration) procedure.
Assuming that data for a specific RB (radio bearer) or LC (logical
channel) is transmitted via a secondary system (e.g., AP) under the
determination made by the eNB, if it is determined that the
specific RB or LC needs to communicate with the secondary system
(e.g., AP), the eNB may instruct the UE to scan neighbor APs.
[0134] In doing so, the eNB sends an RRCConnectionReconfiguration
message to the UE, whereby the UE can initiate a measurement. In
particular, the UE can initiate the measurement of AP by an active
scanning (e.g., Probe Request transmission and Probe Response
reception) or a passive scanning (e.g., Beacon reception).
[0135] In the RRCConnectionReconfiguration message, at least one of
Measurement Configuration and Radio Resource Configuration can be
included. The Measurement Configuration may include information for
a UE to find a secondary system quickly. For instance, the
Measurement Configuration can include at least one of SSID of AP
neighbor to the UE, a beacon transmission cycle, and a measurement
gap information. The Radio Resource Configuration can carry a field
for indicating traffic characteristics of a generated RB. For
instance, in the Radio Resource Configuration, such a parameter
value indicating traffic characteristics as EPS bearer QoS type,
QCI, ARP GBR (DL/UL), MBR (DL/UL) and the like can be included.
[0136] If a trigger condition for a secondary system measure is
already defined, the UE can initiate the measurement of AP on the
condition that the trigger condition is met irrespective of a
presence or non-presence of the reception of the
RRCConnectionReconfiguration message from the eNB.
[0137] It may be unnecessary for the Measurement Configuration of
the RRCConnectionReconfiguration message, which is mentioned in the
above description, to include the information on the measurement
gap all the time. In some cases, the information on the measurement
gap may be omitted from the Measurement Configuration. This is
described in detail with reference to FIG. 7 as follows.
[0138] FIG. 7 is a diagram for one example to describe a
measurement gap in LTE system. A UE can use
InterFreqRSTDMeasurementIndication message to instruct a network to
start or stop a measurement of RSTD (Reference Signal Time
Difference) between OTDOA (Observed Time Difference Of Arrival)
frequency bands requiring a measurement gap.
[0139] If it is indicated that an upper layer starts the
inter-frequency band RSTD measurement only, the UE is able to
confirm a measurement gap required situation as soon as receive the
indication from the upper layer. If a sufficient gap is available
at this timing point, the UE may skip the transmission of the
InterFreqRSTDMeasurementIndication message. Thereafter, even if the
measurement gap gets insufficient, the UE may skip the transmission
of the InterFreqRSTDMeasurementIndication message unless receiving
a new indication from the upper layer.
[0140] If the upper layer indicates to stop performing the
inter-frequency band RSTD measurement, the UE can send the
InterFreqRSTDMeasurementIndication message despite having skipped
the transmission of the InterFreqRSTDMeasurementIndication message
in response to the previous indication indicating to start the
inter-frequency band RSTD measurement.
[0141] Thus, it is necessary for a sufficient measurement gap to be
configured for an inter-frequency band RSTD measurement in a
switching based multi-RAT access system. Yet, the present invention
relates to a non-switching based multi-RAT access system. According
to the present invention, since a UE can access a secondary system
without transferring a primary system, a measurement of the
secondary system may be possible without configuring a measurement
gap. Therefore, information on the measurement gap can be omitted
from Measurement configuration of RRCConnectionReconfiguration.
[0142] The UE can set a given DRB as a single measurement object as
well as a given frequency. In this case, the UE can explicitly
indicate the measurement object in accordance with a radio access
technology type (e.g., E-UTRAN, UTRAN, CDMA2000, GERAN, WLAN,
etc.). In this case, a third layer can filter a measurement result
on a first layer. As mentioned in the foregoing description, the
inter-frequency band measurement can be performed in an idle
interval including the measurement gap. Yet, a measurement of
wInter-RAT (i.e., secondary system) may be performed without a
measurement gap.
[0143] Generally, in order to maintain an optimal access to a base
station, a UE should perform a measurement on at least one of a
serving base station and a neighbor base station to switch from a
specific RAT to another RAT. The UE measures the serving base
station and the base station in response to an indication of an eNB
and is able to report a result of the measurement to the eNB.
[0144] Yet, if the result of the measurement of the at least one of
the serving base station and the neighbor base station is
insignificant, the measurement result may not be transmitted to the
eNB. For instance, if a signal of the neighbor base station is
considerably lower than that of the serving base station, it is
able to raise system efficiency by not reporting the measurement
result. Hence, only if a trigger condition of the measurement
result is met, the UE can transmit the measurement result for the
at least one of the serving base station and the neighbor base
station to the eNB.
[0145] For instance, FIG. 8 is a flowchart of a process for a UE to
report a measurement result to an eNB.
[0146] Referring to FIG. 8, a UE receives RRC Configuration
Reconfiguration message from an eNB [S801]. The UE performs a
measurement [S802]. And, the UE can report a measurement result to
the eNB using Measurement Report message [S804]. In doing so, the
UE determines whether the following trigger condition is met
[S803]. Only if the trigger condition is met, the UE can report a
result of the measurement of at least one of a neighbor base
station and a serving base station to the eNB.
[0147] A1: Serving base station gets better than a first threshold
(threshold 1).
[0148] A2: Serving base station gets worse than the first
threshold.
[0149] A3: Neighbor base station gets better then PCell (primary
cell) by offset.
[0150] A4: Neighbor base station gets better than a second
threshold (threshold 2).
[0151] A5: PCell gets worse than the first threshold and the
neighbor base station gets better than the second threshold.
[0152] A6 (not shown in the drawing): Neighbor base station gets
better than SCell (secondary cell) by offset (in CA (Carrier
Aggregation) environment).
[0153] According to the present invention, a UE is not switched
from a specific RAT to another RAT. Instead, while the UE maintains
an access to a specific RAT (e.g., primary system), the present
invention enables an access to another RAT (e.g., secondary
system). Hence, measurement objects and reporting trigger
conditions different from the above-enumerated A1 to A5 are
applicable.
[0154] FIG. 9 is a diagram for one example to describe a
measurement object and a report configuration for a measurement
result. Referring to FIG. 9, a UE can set a frequency or DRB given
per radio access technology as a measurement object. For instance,
in a switching based multi-RAT access environment, a specific
frequency (or cell) is a measurement object like a single E-UTRA
carrier frequency, a set of cells on a single UTRA carrier
frequency, a set of cells GERAN carrier frequencies, a set of cells
on a single (HRPD or 1xRTT) carrier frequency and the like. On the
other hand, in a non-switching based multi-RAT access environment
like the present invention, a frequency can be set as a measurement
object like a set of WLAN carrier frequencies or a DRB can be set
as a measurement object like a set of E-UTRA data barriers (or
flows) on a single E-UTRA carrier frequency, a set of WLAN data
bearers (or flows) on a single WLAN carrier frequency and the
like.
[0155] The UE gives a measurement ID for identifying a result of
measurement of result of a measurement object and is then able to
report the measurement ID given measurement result to the eNB. The
measurement result reporting may occur periodically. Alternatively,
the measurement result reporting may occur if a trigger condition
for the reporting is met.
[0156] In the non-switching based multi-RAT access environment, a
UE can report a measurement result of a secondary system if the
following trigger condition occurs.
[0157] B1: Case that an inter-RAT neighbor gets better than a
second threshold.
[0158] B2: Case that PCell gets worse than a first threshold and an
inter-RAT neighbor gets better than the second threshold.
[0159] B3: Case that an inter-RAT serving gets worse than the first
threshold.
[0160] In the above enumerated conditions B1 to B3, the inter-RAT
may mean a base station (e.g., AP) of a secondary system. When a
serving base station of a UE is a base station (e.g., eNB) of a
primary system, the inter-RAT serving neighbor may mean that a
serving base station of the UE is a base station (e.g., AP) of a
secondary system.
[0161] FIG. 10 is a diagram of enumerated trigger conditions. A1 to
A10 diagrammatize the trigger conditions in a switching based
multi-RAT access environment. And, B1 to B3 diagrammatize the
trigger conditions in a non-switching based multi-RAT access
environment. In this case, a first threshold may be provided to
determine whether a measurement result of a primary system (or a
serving base station) is meaningful. And, a second threshold may be
provided to determine whether a measurement result of a secondary
system (or a neighbor base station) is meaningful.
[0162] A parameter value for a trigger condition for reporting may
be transmitted to a UE via a reportConfigInterRAT message. In
particular, the reportConfigInterRAT message may be broadcasted or
unicasted to a UE. When a measurement object is a DRB, the
reportConfigInterRAT may be transmitted as UE-specific information
to the UE by unicast.
[0163] The trigger conditions may be set to different values for
each measurement object. For instance, each of the first and second
thresholds may be defined as a different value depending on
preference of AP or traffic characteristics of DRB.
[0164] For instance, a voice traffic may prefer to communicate via
a primary system (e.g., a cellular network) rather than a secondary
system (e.g., WLAN network). And, a data traffic may prefer to
communicate via a secondary system rather than a primary system.
Hence, a threshold value (e.g., a second threshold) for reporting a
measurement result of the secondary system may be set high for the
voice traffic. And, a threshold value (e.g., a second threshold)
for reporting a measurement result of the secondary system may be
set low for the data traffic. Thus, as the threshold values for
reporting the measurement result may vary depending on a
transmitted traffic, trigger conditions may be defined and
transmitted in accordance with the traffic characteristics. As
mentioned in the above description, the trigger condition may be
defined differently in accordance with a traffic type (e.g., EPS
bearer QoS type) of flow or traffic characteristics (e.g., GBR,
non-GBR, etc.) of flow.
[0165] An eNB can provide a UE with a trigger condition for a
reporting through RRCConnectionReconfiguration message. In
particular, the eNB can provide the UE with the trigger condition
through measConfig./radioResourceConfg of
RRCConnectionReconfiguration. In case that the trigger conditions
is defined in accordance with a traffic type or traffic
characteristics of flow, the trigger condition for each flow (or
RB) can be transmitted to the UE. In doing so, the eNB may transmit
an appropriate trigger condition to the UE by unicast with
reference to characteristics of a traffic transmitted through radio
resource configuration.
[0166] Based on the trigger condition for the reporting, whether to
report a measurement result can be determined or set in case of
multi-RAT capability negotiation between the UE and the eNB.
[0167] For instance, although a signal strength of AP is lower than
a threshold (e.g., second threshold) determined by the trigger
condition, if a user intends to communicate using the AP, it may be
necessary to report a measurement result of the AP irrespective of
whether the trigger condition is met.
[0168] Hence, the UE can indicate whether the measurement result
will be reported by the trigger condition in case of the multi-RAT
capability negotiation. In particular, the UE can use `measurement
reporting by trigger condition` bit of UECapabilityInformation
message to indicate whether the measurement result of the AP will
be reported by the trigger condition. For instance, when a value of
the `measurement reporting by trigger condition` bit is set to 1,
the measurement result of the AP is reported only if the trigger
condition for the reporting is met. When a value of the
`measurement reporting by trigger condition` bit is set to 1,
despite that the trigger condition for the reporting is not met, if
the AP is detected, the UE can report the measurement result of the
AP. In doing so, the UE may report a measurement result of a
preferred AP among the detected APs only to the eNB.
[0169] The UE can report the measurement result of the detected AP
to the eNB. In this case, the measurement result of the AP may
include at least one of a channel state information (e.g., RSSI
(Received Signal Strength Indicator), RCPI (Received Channel Power
Indicator), RSNI (Received Signal to Noise Indicator), etc.) and a
preferred AP information.
[0170] For instance, Table 2 shows one example of a measurement
result report message (Measurement Report message) sent to an eNB
by a UE.
TABLE-US-00002 TABLE 2 1> set the measId to the measurement
identity that triggered the measurement reporting; 1> set the
measResultPCell to include the quantities of the PCell; 1> set
the measResultServFreqList to include for each SCell that is
configured, if any, within measResultSCell the quantities of the
concerned SCell; 1> if the reportConfig associated with the
measId that triggered the measurement reporting includes
reportAddNeighMeas: 2> for each serving frequency for which
measObjectId is referenced in the measIdList, other than the
frequency corresponding with the measId that triggered the
measurement reporting: 3> set the measResultServFreqList to
include within measResultBestNeighCell the physCellId and the
quantities of the best non-serving cell, based on RSRP, on the
concerned serving frequency; 1> if there is at least one
applicable neighbouring cell to report: 2> set the
measResultNeighCells to include the best neighbouring cells up to
maxReportCells in accordance with the following: 3> if the
triggerType is set to event: 4> include the cells included in
the cellsTriggeredList as defined within the VarMeasReportList for
this measId; 3> else: 4> include the applicable cells for
which the new measurement results became available since the last
periodical reporting or since the measurement was initiated or
reset; 3> for each cell that is included in the
measResultNeighCells, include the physCellId; 3> if the
triggerType is set to event; or the purpose is set to
reportStrongestCells or to reportStrongestCellsForSON: 4> for
each included cell, include the layer 3 filtered measured results
in accordance with the reportConfig for this measId, ordered as
follows: 5> if the measObject associated with this measId
concerns E-UTRA: 6> set the measResult to include the
quantity(ies) indicated in the reportQuantity within the concerned
reportConfig in order of decreasing triggerQuantity, i.e. the best
cell is included first; 5> if the measObject associated with
this measId concerns UTRA FDD and if ReportConfigInterRAT includes
the reportQuantityUTRA- FDD: 6> set the measResult to include
the quantities indicated by the reportQuantityUTRA-FDD in order of
decreasing measQuantityUTRA- FDD within the quantityConfig, i.e.
the best cell is included first; 5> if the measObject associated
with this measId concerns UTRA FDD and if ReportConfigInterRAT does
not include the reportQuantityUTRA-FDD; or 5> if the measObject
associated with this measId concerns UTRA TDD, GERAN or CDMA2000:
6>set the measResult to the quantity as configured for the
concerned RAT within the quantityConfig in order of either
decreasing quantity for UTRA and GERAN or increasing quantity for
CDMA2000 pilotStrength, i.e. the best cell is included first; 5>
if the measObject associated with this measId concerns WLAN and if
ReportConfigInterRAT includes the reportQuantityWLAN: 6>set the
measResult to include the quantities indicated by the
reportQuantityWLAN in order of decreasing measQuantityWLAN within
the quantityConfig, i.e. the best cell is included first. 3>
else if the purpose is set to reportCGI: 4> if the mandatory
present fields of the cgi-Info for the cell indicated by the
cellForWhichToReportCGI in the associated measObject have been
obtained: 5> if the cell broadcasts a CSG identity: 6>include
the csg-Identity; 6>include the csg-MemberStatus and set it to
member if the cell is a CSG member cell; 5> if the
si-RequestForHO is configured within the reportConfig associated
with this measId: 6>include the cgi-Info containing all the
fields that have been successfully acquired, except for the
plmn-IdentityList; 5> else: 6>include the cgi-Info containing
all the fields that have been successfully acquired; 1>if the
ue-RxTxTimeDiffPeriodical is configured within the corresponding
reportConfig for this measId; 2> set the ue-RxTxTimeDiffResult
to the measurement result provided by lower layers; 2> set the
currentSFN; 1> if the includeLocationInfo is configured in the
corresponding reportConfig for this measId and detailed location
information that has not been reported is available, set the
content of the locationInfo as follows: 2> include the
locationCoordinates; 2> if available, include the gnss-TOD-msec;
1> increment the numberOfReportsSent as defined within the
VarMeasReportList for this measId by 1; 1> stop the periodical
reporting timer, if running; 1> if the numberOfReportsSent as
defined within the VarMeasReportList for this measId is less than
the reportAmount as defined within the corresponding reportConfig
for this measId: 2> start the periodical reporting timer with
the value of reportInterval as defined within the corresponding
reportConfig for this measId; 1> else: 2> if the triggerType
is set to periodical: 3> remove the entry within the
VarMeasReportList for this measId; 3> remove this measId from
the measIdList within VarMeasConfig; 1> if the measured results
are for CDMA2000 HRPD: 2> set the preRegistrationStatusHRPD to
the UE's CDMA2000 upper layer's HRPD preRegistrationStatus; 1>
if the measured results are for CDMA2000 1xRTT: 2> set the
preRegistrationStatusHRPD to FALSE; 1> submit the
MeasurementReport message to lower layers for transmission, upon
which the procedure ends;
[0171] Referring to Table 2, if a measurement object for a random
measurement ID is related to WLAN and a reportConfigInterRAT
message contains a WLAN report quantity (reportQuantityWLAN), a UE
can set measResult including a quantity indicated by the
reportQuantityWLAN in decreasing order of measQuantityWLAN within
quantityConfig. In doing so, the UE can control a best cell to be
situated at a first place in the measResult.
[0172] A parameter value for a trigger condition for reporting may
be transmitted to the UE via reportConfigInterRAT message.
[0173] When a UE detects at least two APs, if an eNB receives a
measurement result of the at least two APs, the eNB selects an AP
appropriate for the UE from a plurality of APs and is then able to
inform the UE of the selected AP. When the eNB selects the AP
appropriate for the UE, at least one of the following metrics can
be used.
[0174] i) Same Operator: Preferentially select AP of the same
operator of UE
[0175] ii) UE's Priority: Preferentially select AP preferred by
UE
[0176] iii) Channel quality: Preferentially select AP having a good
channel state
[0177] iv) Load balancing: Select AP by considering load
distribution
[0178] v) Carried traffic: Select AP by considering traffic
[0179] The eNB can send indication, which indicates an AP to be
accessed, to the UE using the above enumerated metrics.
[0180] Secondary System Management
[0181] As mentioned in the foregoing description with reference to
FIG. 4 and FIG. 6, after the scanning of the secondary system, the
secondary system management procedure is initiated for example. The
secondary system management procedure may be mainly divided into a
secondary system adding procedure, a secondary system deleting
procedure and a secondary system changing procedure. Prior to the
description of each of the procedures, messages used for the
secondary system shall be described as follows.
[0182] FIG. 11 is a flowchart to describe a message defined for a
secondary system management procedure. Having detected a secondary
system that meets a preset condition, a UE can send a message for
requesting an association with an AP to an eNB [S1110]. This
message may be named a SecondarySystemRequest message.
[0183] Having received the SecondarySystemRequest message from the
UE, the eNB checks states of APs and is then able to select an AP
that the UE will access [S1120]. Subsequently, in response to a
request made by the UE, the eNB can send a message for indicating
an access to a secondary system to the UE [S1130]. This message may
be called a SecondarySystemSetup message. Information (e.g.,
identification information of the selected AP, authentication
method with the selected AP, etc.) on an AP the UE will access, DRB
(or flow) information to be transmitted to the secondary system,
and the like can be included in the SecondarySystemSetup message.
The UE transceives an association request frame, an association
response frame and the like with the AP indicated by the
SecondarySystemSetup message and is then able to attempt an access
to the AP [S140]. In case that the secondary system corresponds to
IEEE 802.11e, a traffic stream setup process (particularly, ADDTS
request frame/ADDTS response frame transceiving) with the AP can be
performed.
[0184] Thereafter, the UE can send a message for reporting a result
of connection to the AP to the eNB [S1150]. This message may be
named a SecondarySystemSetupComplete message. Through the
SecondarySystemSetupComplete message, the UE can report a result of
mapping between a DRB ID (or flow ID) of a DRB, which is to be
transmitted to the secondary system, and AID/TSID (association
ID/traffic stream ID).
[0185] If the AP is successfully accessed, the UE can transceive
data for a specific traffic type via the AP. To this end, the eNB
redirects a path of DL data for the specific flow to the AP and the
UE is able to transmit UL data for the DRB ID (or flow ID)
indicated by the eNB not to the eNB but to the AP. Data except the
specific data type may be transceived via the eNB as it is.
[0186] Reassociation with the AP or Disassociation from the AP can
be performed through the SecondarySystemSetup message and the
SecondarySystemComplete message between the UE and the eNB. The
reassociation with the AP means that the UE makes a handover into a
neighbor AP. And, the disassociation from the AP means that the UE
ends the access to the AP. In order to secure seamless data
transmission of the UE, the eNB may can support seamless flow
mobility between the AP and the eNB or between APs.
[0187] For instance, although a UE has leaved a coverage of an AP,
if there is no neighbor AP into which the UE will make a handover,
in order to secure that the data transmitted via a secondary system
can be transmitted seamlessly, an eNB can support seamless flow
mobility between the AP and the eNB.
[0188] On the contrary, if the UE detects the neighbor AP to make a
handover into, the UE can support seamless flow mobility between
APs in order to secure that data for a specific flow can be
transmitted seamlessly.
[0189] A primary system performs such a basic control operation as
an access control between UE and AP, a configuration of DRB and the
like. And a secondary system transceives data (i.e., data for a
specific traffic type) indicated by the primary system. In
particular, all data transmitted to a user equipment are configured
by a radio resource configuration procedure of
RRCConnectionReconfiguration transmitted to UE by eNB. And, data
for a specific RB can be transmitted to the UE via AP under the
determination made by the eNB. To this end, the eNB can redirect
the data, which are transmitted to specific RNTI (radio network
temporary identities) and specific DRB ID, among the data
transmitted to the eNB to the AP.
[0190] Based on the above description, a secondary system adding
procedure, a secondary system deleting procedure and a secondary
system changing procedure are described in detail as follows.
[0191] Addition of Secondary System
[0192] FIG. 12 is a flowchart to describe an additional procedure
of a secondary system. A secondary system adding procedure may be
initiated by a UE or a base station. FIG. 12 shows one example that
a secondary system adding procedure is initiated by a UE. Having
detected a secondary system that meets a preset condition, a UE can
request an association (connection setup) with the detected
secondary system via SecondarySystemRequest message [S1210]. In
doing so, one of the following conditions may be set as the preset
condition. First of all, a UE-preferred AP is detected. Secondly, a
measured signal strength of a AP is sufficiently high (e.g., a
preferred AP is detected and a measurement result of the preferred
AP is higher than a preset threshold). Thirdly, a measurement
result of AP is higher than a measurement result of eNB. Forthly, a
specific flow (or DRB) has established.
[0193] Having received the SecondarySystemRequest message from the
UE, the eNB can send a SecondarySystemSetup message indicating an
access to the secondary system in response to the request made by
the UE [S1220].
[0194] By skipping the SecondarySystemRequest message sending step
S1210 and sending a SecondarySystemSetup message to the UE, the
secondary system adding procedure may be initiated (i.e., a method
for a base station to initiate a secondary system adding
procedure). In particular, if recognizing the establishment (i.e.,
DRB addition to UE) of a specific flow connection to the UE and the
position of the UE located within an area of the secondary system,
the eNB sends a SecondarySystemSetup message irrespective of a
presence or non-presence of a reception of the
SecondarySystemRequest message, thereby instructing the UE to
access the secondary system [S1220].
[0195] In the SecondarySystemSetup message, at least one of
information on the AP selected by the eNB, information on a flow
(or DRB) to be transmitted to the secondary system, authentication
information of the secondary system, information indicating whether
to enter a doze mode after association, timer information, action
time information and a data unit information can be included.
[0196] The selected AP information may indicate an identification
information of an AP that the UE will access. The flow (or DRB)
information may indicate a traffic type of a flow that the UE will
transceive via the AP. The UE attempts an access to the AP
indicated by the selected AP information. If the access to the AP
is successfully completed, the UE can transceive the traffic type
indicated by the flow information via the selected AP.
[0197] The authentication information of the secondary system
indicates a presence or non-presence of a shared key of the
secondary system and the shared key. In case that the secondary
system is an open system that does not use the shared key, the UE
may access the secondary system without the shared key. On the
other hand, if the secondary system is an encrypted system that
uses the shared key, the UE may access the secondary system using
the shared key indicated by the authentication information.
[0198] The information indicating whether to enter the doze mode
indicates whether the UE should enter a power saving mode after the
association with the secondary system. If the UE has no data to
receive from the secondary system right now despite being
associated with the secondary system, the eNB can instruct the UE
to enter the doze mode after the association with the AP.
[0199] The timer information may indicate an expiry period until a
timer for secondary system association starting after the
transmission of the SecondarySystemSetup message expires.
[0200] The action time information may indicate a timing point for
the UE to initiate the transceiving of data for a specific traffic
type with the AP.
[0201] The data unit information may indicate a data unit (e.g.,
U-plane, APN, DRB, flow, flow in same flow) to be redirected to the
AP. The data unit information may be an 1 bit indicator indicates
whether the eNB retransmit all the flows to the AP. Or, the data
unit information may indicate a data unit (i.e., U-plane, unit of
APN, unit of DRB, unit of IP flow, unit of data in specific flow,
etc) redirected to the AP. If the data unit information indicates
that the data unit redirected to the AP is set as a unit of data in
specific flow, ratio information indicates a ratio between amount
of data in specific flow transmitted via the eNB and amount of data
transmitted via the AP may further be included in the
SecondarySystemSetup message.
[0202] In response to the reception of the SecondarySystemSetup
message, the UE may send a SecondarySystemSetup ACK message
[S1230]. Alternatively, the UE may attempt an access to the AP
without sending the ACK message.
[0203] Having received the SecondarySystemSetup from the eNB, the
UE may attempt the access to the AP [S1240]. In particular, the UE
may attempt the access to the AP through the steps of
synchronization, authentication and association with the AP.
[0204] The synchronization step is provided to match
synchronization between the UE and the AP. By receiving a beacon
frame from the AP, the UE can match the synchronization with the
AP.
[0205] The authentication step includes the steps of transmitting
an authentication request frame to the AP from the UE and
transmitting an authentication response frame to the UE from the AP
in response. In case that the AP is an open system, the
authentication may be performed without utilizing a separate shared
key. Otherwise, the authentication can be performed using a shared
key.
[0206] After the UE has been successfully authenticated, the
association step can be performed. In particular, the association
step includes the steps of transmitting an association request
frame to the AP from the UE and transmitting an association
response message to the UE from the AP in response. In this case,
AID (association ID) information on the UE may be included in the
association response frame.
[0207] In case that the secondary system includes IEEE 802.11e
system, the UE may perform a traffic stream (TS) setup. For the
traffic stream setup, the UE receives an ADDTS request from the AP
and is then able to transmit an ADDTS response to a specific AP in
response to the request.
[0208] In order to report a result of the connection to the AP, the
UE can send a SecondarySystemSetupComplete message [S1250]. The UE
configures a SecondarySystemSetupComplete message to contain a
status value indicating a success or failure in the access to the
AP. Subsequently, the UE is always able to send the
SecondarySystemSetupComplete message irrespective of the success or
failure in the result of the connection to the AP. Alternatively,
the UE may send the SecondarySystemSetupComplete message only if
the access to the AP is successful.
[0209] For instance, if the SecondarySystemSetupComplete message
contains the status value, the UE adjusts the status value to
indicate whether the establishment of the connection to the AP is
successful.
[0210] For another instance, only if the establishment of the
connection to the AP is successful, the UE may send the
SecondarySystemSetupComplete message. After the
SecondarySystemSetupComplete message has been sent, if the
SecondarySystemSetupComplete message is received within a
prescribed time, the eNB can determine that the UE has successfully
accessed the AP. On the contrary, after the
SecondarySystemSetupComplete message has been sent, if the
SecondarySystemSetupComplete message is not received within the
prescribed time, the eNB can determine that the UE has not accessed
the AP successfully.
[0211] After sending a SecondarySystemSetup message, the eNB can
start a secondary system association timer. If not receiving the
SecondarySystemSetupComplete message until the expiration of the
secondary system association timer, the eNB may determine that the
UE fails in the access to the AP. Using the timer information of
the SecondarySystemSetup message, the UE may recognize an expiry
timing point of the secondary system association timer. In order to
secure a time enough for the UE to send the
SecondarySystemSetupComplete message, the expiry period of the
secondary system association timer may be determined in
consideration of a time taken for the association between the UE
and the AP.
[0212] The SecondarySystemSetupComplete message may contain
information on an address (e.g., IP address assigned to the UE by
the AP) assigned to the UE by the AP.
[0213] If the establishment of the connection to the AP is not
successful, the eNB newly selects an AP and may be then able to
resend a SecondarySystemSetup message to the newly selected AP in
order to indicate an access to the newly selected AP. Having
received the re-sent SecondarySystemSetup message, the UE may
attempt the access to the newly selected AP indicated by the
re-received SecondarySystemSetup message.
[0214] If the establishment of the connection to the AP is
successful, the UE can transceive data for a specific traffic type
via the AP and is able to transceive data for other traffic types
via the eNB [S1260]. The traffic type to be transceived via the AP
may be indicated by DRB information (or flow information) of the
SecondarySystemSetup message. In order for downlink data of the
specific traffic type to be transmitted via the AP, the eNB can
redirect the downlink data for the specific traffic type to the AP.
To this end, the eNB can set a destination of the data for the
specific data type to an address (e.g., IP address assigned to the
UE by the AP) of the UE. The UE can transmit uplink data for the
specific traffic type to the AP. eNB (or interworking entity) may
redirect a downlink data to UE by transmitting a specific message
to an entity which manages IP information on a flow of UE (e.g.,
P-GW or terminal end). The specific message may be a flow IP
address binding update message which comprises an action time
information. Action time information included in the flow IP
address binding update message may be same as an action time
message included in SecondarySystemSetup messages transmitted from
the eNB to UE.
[0215] In doing so, the eNB can designate an action time that is a
timing point at which the UE starts the transceiving of the data
for the specific traffic type via the AP. Even if the establishment
of the connection to the AP is successful, the UE may not perform
the transceiving of the data for the specific traffic type via the
AP until an action time comes. If the SecondarySystemSetup message
is lost, the eNB is unable to recognize whether the UE has been
successfully accessed the AP. Nonetheless, if the UE intends to
transceive the data for the specific traffic type via the AP, since
the eNB is unable to change or redirect the path of the data for
the specific traffic type to the AP, the UE may have a problem in
receiving the downlink data for the specific traffic type
appropriately.
[0216] Hence, the eNB designates the action time. The eNB is then
able to control the UE to start the transceiving for the specific
traffic type with the AP only if the action time expires. In this
case, the action time may be calculated in consideration of the
expiry period of the secondary system association timer and a time
taken for the retransmission of the SecondarySystemSetup message
due to the failure in accessing the AP. In particular, after the
SecondarySystemSetup message has been sent, the action time may be
set to a time after elapse of a time equal to or greater than a sum
of the expiry period of the secondary system association timer and
the time taken for the transmission of the SecondarySystemSetup
message.
[0217] Change of Secondary System
[0218] FIG. 13 is a flowchart to describe a changing procedure of a
secondary system. If a UE leaves a coverage of an accessed AP or an
AP having a measurement higher than that of the accessed AP is
detected, an eNB can instruct the UE to make a handover into a new
AP. For clarity of the following description, an AP currently
providing a service to the UE shall be named a serving AP or an old
AP and a new AP becoming a handover target shall be named a target
AP or a new AP. In order to instruct the UE to make a handover into
a new AP, the eNB can send a SecondarySystemSetup message to the UE
[S1310]. The SecondarySystemSetup message sent to the UE may
include at least one of an information on a target AP, an
information on a flow (or DRB) to be transmitted via a secondary
system, an authentication information of the secondary system, an
information indicating whether to enter a doze mode after
association, a timer information, a disconnection time information,
an action time information and a data unit information.
[0219] The target AP information may indicate an identification
information of a new AP that the UE will newly access. And, the
flow (or DRB) information may indicate a traffic type of a flow to
be transceived by the UE via the new AP. The authentication
information of the secondary system may indicate a presence or
non-presence of a shared key of the new AP and the shared key. The
information indicating whether to enter the doze mode may indicate
whether the UE should enter a power saving mode after the
association with the new AP. The timer information may indicate an
expiry period until expiration of a secondary system reassociation
timer after sending the SecondarySystemSetup message. The
disconnection time information may indicate a timing point at which
the UE is disassociated from the old AP. Or, the disconnection time
information may indicate a timing point at which the eNB stops
redirecting data for specific flow to the old AP. The action time
information may indicate a timing point at which the UE can start
the transceiving of data for a specific traffic with the new AP.
Or, the Action information may indicate a timing point at which the
eNB redirects data for specific flow which stopped redirecting at
the timing point indicated by the disconnection time information to
the new AP. The data unit information may indicate a data unit
(e.g., U-plane, APN, DRB, flow, flow in same flow) to be redirected
to the AP.
[0220] eNB may transmit a Flow-IP address binding update message
which comprises a disconnection time information and an action time
information to an entity which manages IP information on a flow of
UE (e.g., P-GW or terminal end) in course of (or after)
transmitting the SecondarySystemSetup message. The entity which
received the Flow-IP address binding update message (e.g., P-GW)
may newly set an IP address of data on a specific flow to be
transmitted to UE based on the disconnection time information and
the action time information.
[0221] While the reassociation procedure of the UE is in progress
through a control connection (e.g., a backhaul control connection,
a radio control connection, etc.) between the old AP and the new
AP, the eNB can transmit a security information set by the old AP
to the new AP.
[0222] In response to the reception of the SecondarySystemSetup
message, the UE sends a SecondarySystemSetup ACK message [S1320] or
may disconnect the access from the old AP without sending the ACK
message.
[0223] Having received the SecondarySystemSetup message, the UE can
disconnect the connection from the old AP [S1330]. In doing so, the
UE can disconnect the connection from the old AP at the
disconnection timing point indicated by the disconnection time
information. Once the disconnection timing point is designated
through the disconnection time information, the eNB can accurately
obtain the timing point of the disconnection between the UE and the
old AP. Hence, the eNB may accurately calculate the timing point of
terminating the redirection of the data for the specific traffic
type to the old AP.
[0224] At the disassociation timing point, the UE may send a
disassociation notification message to the old AP. If an ACK
message for the disassociation notification message is received
from the old AP, the connection between the UE and the old AP may
be terminated.
[0225] Once the connection to the old AP is terminated, the UE may
attempt an access to a new AP [S1340]. In particular, the UE may be
able to attempt the access to the new AP through synchronization,
authentication and association with the new AP.
[0226] In order to report a result of the connection to the new AP,
the UE may send a SecondarySystemSetupComplete message [S1350]. The
UE configures a SecondarySystemSetupComplete message to contain a
status value indicating a success or failure in the access to the
new AP. Subsequently, the UE is always able to send the
SecondarySystemSetupComplete message irrespective of the success or
failure in the result of the connection to the new AP.
Alternatively, the UE may send the SecondarySystemSetupComplete
message only if the access to the new AP is successful.
[0227] For instance, if the SecondarySystemSetupComplete message
contains the status value, the UE adjusts the status value to
indicate whether the establishment of the connection to the new AP
is successful.
[0228] For another instance, only if the establishment of the
connection to the new AP is successful, the UE may send the
SecondarySystemSetupComplete message.
[0229] The eNB waits for the SecondarySystemSetupComplete message
to be sent from the UE for a while. If the eNB receives the
SecondarySystemSetupComplete message, the eNB determines that the
UE has succeeded in the access to the AP. On the contrary, after
the SecondarySystemSetupComplete message has been sent, if the
SecondarySystemSetupComplete message is not received within a
prescribed time, the eNB can determine that the UE has failed in
the access to the AP. After sending a SecondarySystemSetup message,
the eNB can start a secondary system reassociation timer. If not
receiving the SecondarySystemSetupComplete message until the
expiration of the secondary system reassociation timer, the eNB may
determine that the UE fails in the access to the new AP. In order
to secure a time enough for the UE to send the
SecondarySystemSetupComplete message, the expiry period of the
secondary system reassociation timer may be determined in
consideration of a time taken for the reassociation with the
AP.
[0230] The SecondarySystemSetupComplete message may contain
information on an address (e.g., IP address assigned to the UE by
the AP) assigned to the UE by the new AP.
[0231] If the establishment of the connection to the new AP is not
successful, the eNB newly selects a target AP and may be then able
to resend a SecondarySystemSetup message to indicate an access to
the newly selected target AP. Having received the re-sent
SecondarySystemSetup message, the UE may attempt the access to the
newly selected target AP indicated by the re-received
SecondarySystemSetup message.
[0232] If the establishment of the connection to the AP is
successful, the UE can transceive data for a specific traffic type
not via the old AP but via the new AP [S1360]. The traffic type to
be transceived via the new AP may be indicated by DRB information
(or flow information) of the SecondarySystemSetup message. And,
data other than the specific traffic type may be transceived via
the eNB as they are.
[0233] As mentioned in the foregoing description with reference to
FIG. 11, the eNB can designate an action time for the UE to
initiate the transceiving of the data for the specific data type
via the new AP [not shown in the drawing]. Once the action time is
designated, the UE can initiate the transceiving for the specific
traffic type with the new AP only if the action time is up.
[0234] Deletion of Secondary System
[0235] FIGS. 14A to 14C are flowcharts to describe a deleting
procedure of a secondary system. FIG. 14A and FIG. 14B are diagrams
for examples that a UE is disassociated from an AP by an indication
of an eNB. FIG. 14C is a diagram for one example that a UE is
actively disassociated from an AP.
[0236] Referring to FIG. 14A and FIG. 14B, an eNB can send a UE a
SecondarySystemSetup message to indicate disassociation from an AP
[S1410a, S1410b]. The SecondarySystemSetup message may include at
least one of an information on a disassociated AP, an information
on a flow (or DRB) transmitted from the disassociated AP, a
disconnection time information, an action time information and a
timer information.
[0237] The disassociated AP information may indicate an
identification information of an AP from which the UE will be
disconnected. And, the flow (or DRB) information may indicate a
traffic type of a flow handled by the AP to be disconnected.
[0238] The timer information may indicate an expiry period until
expiration of a secondary system disassociation timer that starts
after sending the SecondarySystemSetup message.
[0239] The disconnection time information may indicate a timing
point at which the UE is disassociated from the AP. And, the action
time information may indicate a timing point at which the UE can
start the transceiving of data for a specific traffic with the
eNB.
[0240] In response to the reception of the SecondarySystemSetup
message, the UE sends a SecondarySystemSetup ACK message [S1420a,
1420b] or may disconnect the access from the AP without sending the
ACK message.
[0241] Having received the SecondarySystemSetup message, the UE can
terminate the access from the AP [S1430a, 1430b]. In doing so, the
UE can disconnect the connection from the AP at the disconnection
time indicated by the disconnection time information. Once the
disconnection time is designated through the disconnection time
information, the eNB can accurately obtain the timing point of the
disconnection between the UE and the AP. Hence, the eNB may
accurately calculate the timing point of terminating the
redirection of the data for the specific traffic type to the
AP.
[0242] At the disassociation timing point, the UE may send a
disassociation notification message to the AP. If an ACK message
for the disassociation notification message is received from the
AP, the connection between the UE and the AP may be terminated.
[0243] Once the connection to the AP is terminated, in order to
report that the connection to the AP has been successfully
terminated, the UE may send a SecondarySystemSetupComplete message
[S1440a]. The UE configures a SecondarySystemSetupComplete message
to contain a status value indicating a success or failure in the
termination of the connection to the AP. Subsequently, the UE is
always able to send the SecondarySystemSetupComplete message
irrespective of the success or failure in the result of the
termination of the connection to the AP. Alternatively, the UE may
send the SecondarySystemSetupComplete message only if the
termination of the connection to the AP is successfully
completed.
[0244] For instance, if the SecondarySystemSetupComplete message
contains the status value, the UE adjusts the status value to
indicate whether the connection to the AP is successfully
terminated.
[0245] For another instance, only if the connection to the AP is
successfully terminated, the UE may send the
SecondarySystemSetupComplete message.
[0246] The eNB waits for the SecondarySystemSetupComplete message
to be sent from the UE for a while. If the eNB receives the
SecondarySystemSetupComplete message, the eNB determines that the
UE has succeeded in the termination of the connection to the AP. On
the contrary, after the SecondarySystemSetupComplete message has
been sent, if the SecondarySystemSetupComplete message is not
received within a prescribed time, the eNB can determine that the
UE has failed in the termination of the connection to the AP. After
sending the SecondarySystemSetup message, the eNB can start a
secondary system disassociation timer. If not receiving the
SecondarySystemSetupComplete message until the expiration of the
secondary system disassociation timer, the eNB may determine that
the UE fails in the termination of the connection between the UE
and the AP. In order to secure a time enough for the UE to send the
SecondarySystemSetupComplete message, the expiry period of the
secondary system disassociation timer may be determined in
consideration of a time taken for the disassociation from the AP.
If determining that the connection between the UE and the AP is not
successfully terminated, the eNB may resend the UE the
SecondarySystemSetup message indicating the termination of the
connection to the AP.
[0247] Having sent the SecondarySystemSetupComplete message, the UE
can transceive data for a specific traffic type, which was
transceived via the AP, via the eNB [S1450a]. In doing so, the UE
may initiate the transceiving of the data for a traffic type of a
specific flow at the action time indicated by the eNB.
[0248] For another instance, if the connection to the AP is
terminated, the UE may initiate the transceiving of the data for
the traffic type of the specific flow via the eNB immediately
[S1440b]. The step of sending the SecondarySystemSetupComplete
message for reporting a result of the termination of the connection
to the AP may be skipped or the SecondarySystemSetupComplete
message may be sent after initiation of the transceiving of the
data for the traffic type of the specific flow with the eNB
[S1450b].
[0249] Referring to FIG. 14C, irrespective of the reception of the
SecondarySystemSetup message from the eNB, the UE can terminate the
connection to the AP by itself [S1410c]. Once the connection to the
AP is terminated, the UE can send a SecondarySystemSetupComplete
message to indicate that the connection to the AP has been
successfully terminated [S1420c]. In particular, despite that a
request for sending the SecondarySystemSetupComplete message is not
made, the UE can send the SecondarySystemSetupComplete message to
the eNB [unsolicited].
[0250] Having received the SecondarySystemSetupComplete message
from the UE, the eNB stops redirection to the AP and may transmit
the data for the traffic type of the specific flow to the UE in
direct.
[0251] According to various embodiments of the present invention, a
user equipment capable of both Cellular and WLAN in a broadband
wireless communication system can efficiently make a heterogeneous
network selection for a flow through a control of the cellular
network.
[0252] The above-described embodiments may correspond to
combinations of elements and features of the present invention in
prescribed forms. And, it may be able to consider that the
respective elements or features may be selective unless they are
explicitly mentioned. Each of the elements or features may be
implemented in a form failing to be combined with other elements or
features. Moreover, it may be able to implement an embodiment of
the present invention by combining elements and/or features
together in part. A sequence of operations explained for each
embodiment of the present invention may be modified. Some
configurations or features of one embodiment may be included in
another embodiment or can be substituted for corresponding
configurations or features of another embodiment. And, it is
apparently understandable that a new embodiment may be configured
by combining claims failing to have relation of explicit citation
in the appended claims together or may be included as new claims by
amendment after filing an application.
[0253] While the present invention has been described and
illustrated herein with reference to the preferred embodiments
thereof, it will be apparent to those skilled in the art that
various modifications and variations can be made therein without
departing from the spirit and scope of the invention. Thus, it is
intended that the present invention covers the modifications and
variations of this invention that come within the scope of the
appended claims and their equivalents.
* * * * *