U.S. patent application number 16/089576 was filed with the patent office on 2019-05-23 for methods for implementing uplink channel access in elaa-based communication system.
This patent application is currently assigned to Alcatel Lucent. The applicant listed for this patent is Alcatel Lucent. Invention is credited to Junrong Gu, Jianguo Liu, Zhe Luo, Yan Meng, Gang Shen, Tao Tao, Dawei Wang.
Application Number | 20190159243 16/089576 |
Document ID | / |
Family ID | 58632538 |
Filed Date | 2019-05-23 |
![](/patent/app/20190159243/US20190159243A1-20190523-D00000.png)
![](/patent/app/20190159243/US20190159243A1-20190523-D00001.png)
![](/patent/app/20190159243/US20190159243A1-20190523-D00002.png)
United States Patent
Application |
20190159243 |
Kind Code |
A1 |
Tao; Tao ; et al. |
May 23, 2019 |
METHODS FOR IMPLEMENTING UPLINK CHANNEL ACCESS IN ELAA-BASED
COMMUNICATION SYSTEM
Abstract
The disclosure provides a method for assisting a UE to implement
a UL channel access in a base station of an eLAA-based
communication system. The method comprises determining a
listen-before-talk (LBT) priority for the UE; and transmitting a
first signaling indicating the determined LBT priority to the UE.
An enhanced UL channel access mechanism is proposed by the
disclosure. In this mechanism, the eNB can provide some assistance
to facilitate UL access. Chances of multiple user multiplexing and
spectrum efficiency in LAA UL can be improved by this solution.
Inventors: |
Tao; Tao; (Shanghai, CN)
; Liu; Jianguo; (Shanghai, CN) ; Meng; Yan;
(Shanghai, CN) ; Gu; Junrong; (Shanghai, CN)
; Wang; Dawei; (Shanghai, CN) ; Luo; Zhe;
(Shanghai, CN) ; Shen; Gang; (Shanghai,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Alcatel Lucent |
Nozay |
|
FR |
|
|
Assignee: |
Alcatel Lucent
Nozay
FR
|
Family ID: |
58632538 |
Appl. No.: |
16/089576 |
Filed: |
March 30, 2017 |
PCT Filed: |
March 30, 2017 |
PCT NO: |
PCT/IB2017/000446 |
371 Date: |
September 28, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/006 20130101;
H04W 16/14 20130101; H04W 72/121 20130101; H04W 74/0808 20130101;
H04W 72/14 20130101 |
International
Class: |
H04W 74/00 20060101
H04W074/00; H04W 16/14 20060101 H04W016/14; H04W 72/14 20060101
H04W072/14; H04W 72/12 20060101 H04W072/12; H04W 74/08 20060101
H04W074/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2016 |
CN |
201610192417.1 |
Claims
1. A method for assisting a User Equipment (UE) to implement an
Uplink (UL) channel access in a base station of an eLAA-based
communication system, comprising: determining a listen-before-talk
(LBT) priority for the UE; and transmitting a first signaling
indicating the determined LBT priority to the UE.
2. The method of claim 1, wherein determining a LBT priority for
the UE further comprises: determining a set of UL channel access
parameters according to predetermined factors; and determining the
LBT priority based on the set of UL channel access parameters.
3. The method of claim 1, wherein the predetermined factors at
least comprise one or more of: transmission duration of a UL
transmission burst; number of UEs scheduled in the UL transmission
burst; traffic types and interference situations of the scheduled
UEs; and eLAA TDD configuration information.
4. The method of claim 2, wherein, a same set of UL channel access
parameters is determined for all UEs; or different sets of UL
channel access parameters are determined for different UEs.
5.-7. (canceled)
8. A method for assisting a User Equipment (UE) to implement an
Uplink (UL) channel access in a base station of an eLAA-based
communication system, comprising: indicating to the UE an expected
transmission duration scheduled for the UE in the UL transmission
burst.
9. The method of claim 8, wherein indicating to the UE an expected
transmission duration scheduled for the UE in the UL transmission
burst further comprises: dynamically or semi-statically indicating
the expected transmission duration to the UE through a signaling;
or indicating the expected transmission duration to the UE through
a UL scheduling grant.
10. A method for implementing an Uplink (UL) channel access in a
User Equipment (UE) of an eLAA-based communication system,
comprising: receiving from a base station a first signaling, which
indicates a listen-before-talk (LBT) priority determined by the
base station for the UE or a portion of a set of UL channel access
parameters determined by the base station for the UE.
11. The method of claim 10, wherein, in case that the first
signaling indicates the LBT priority, the UE performs a LBT
operation using a set of UL channel access parameters corresponding
to the LBT priority; and in case that the first signaling indicates
a portion of a set of UL channel access parameters, the UE
determines other parameters in the set of UL channel access
parameters and the LBT priority based on traffic type and the
pre-stored relations between LBT priorities and UL channel access
parameters, and performs a LBT operation using the set of UL
channel access parameters.
12. The method of claim 11, wherein the method further comprises:
adjusting the LBT priority according to the traffic type.
13. The method of claim 11, wherein the method further comprises:
transmitting a second type of traffics only after all of a first
type of traffics have been transmitted, wherein a LBT priority of
the first type of traffics is not less than the LBT priority, and a
LBT priority of the second type of traffics is lower than the LBT
priority.
14.-17. (canceled)
18. A method for assisting a User Equipment (UE) to maintain a
Contention Window Size (CWS) in a base station of an eLAA-based
communication system, comprising: configuring a set of CWSs,
wherein each CWS in the set of CWSs is corresponding to a different
listen-before-talk (LBT) priority and the set of CWSs is applicable
to all UEs; and simultaneously updating CWSs of all LBT priorities
based on a predetermined trigger mechanism.
19. The method of claim 18, wherein simultaneously updating CWSs of
all LBT priorities based on a predetermined trigger mechanism
further comprises: updating CWSs of all LBT priorities based on a
PUSCH decoding result in the first subframe of a last UL
transmission burst; or updating CWSs of all LBT priorities based on
a PUSCH decoding result in the last valid subframe of a last UL
transmission burst; wherein the PUSCH decoding result is that by
the UEs that implement LBT Category 4 operations in the last UL
transmission burst.
20. The method of claim 18, wherein simultaneously updating CWSs of
all LBT priorities based on a predetermined trigger mechanism
further comprises: updating CWSs of all LBT priorities based on the
PUSCH decoding result in all subframes of a last UL transmission
burst, wherein the PUSCH decoding result is that by all UEs that
implement UL transmissions in the last UL transmission burst.
21. The method of claim 19, wherein the PUSCH decoding result is a
ratio of a number of incorrectly decoded PUSCHs to a number of
correctly decoded PUSCHs; and wherein if the ratio is larger than a
pre-defined threshold, the CWSs of all LBT priorities will be
exponentially or linearly increased; and wherein if the ratio is
not larger than the pre-defined threshold, the CWSs of all LBT
priorities are reset to respective minimum CWSs corresponding to
respective LBT priorities.
22. The method of claim 18, wherein the method further comprises:
transmitting the updated CWSs or a backoff counter generated
therefrom to the UE.
23.-30. (canceled)
Description
FIELD
[0001] The present disclosure relates to mobile communication
technologies, and more specifically, to methods for implementing an
uplink channel access in an eLAA-based communication system and
methods for assisting a User Equipment (UE) to maintain a
contention window size in a base station of the eLAA-based
communication system.
BACKGROUND
[0002] In RAN#70, a new work item on enhanced LAA for LTE
(eLAA-LTE) is approved to support Licensed-Assisted Access (LAA)
SCell operation on unlicensed spectrum for Uplink (UL). The
listen-before-talk (LBT) as one of the most important mechanisms to
ensure the coexistence fairness should be designed carefully. In
current ETSI BRAN discussions, it is highly possible to support the
UL transmission within a Maximum Channel Occupancy Time (MCOT)
acquired by the base station (eNB). In this case, 25 us one-shot
Clear Channel Assessment (CCA) as the LBT operation may be
sufficient within the gap between the end of a Downlink (DL)
transmission and the start of a UL transmission. However, for the
UL transmission burst, the LBT operation is not clear at the
moment.
[0003] In the RANI #84 meeting, the LBT Category 4 channel access
procedure has been agreed to be supported in the LAA UL. However,
the application scenario for the UL LBT Category 4 is not clear. To
start a UL transmission burst as shown in FIG. 1, the LBT Category
4 can ensure better coexistence fairness between WiFi and
asynchronous LAA DL transmission.
[0004] Furthermore, the detailed UL LBT Category 4 design (e.g.,
the channel access parameters, the mechanism of Contention Window
Size (CWS) adjustment) is still an open issue. In the DL LAA, the
channel access parameters and CWS value are determined at the eNB
side since eNB is the one who will contend for channel access.
However, this is not applicable to maintain the UL access
parameters at the UE side since the LAA UL transmission is
scheduled by the eNB. For example, if an eNB schedules a large
number of continuous subframes for a UE and the UE chooses a set of
channel access parameters corresponding to a high priority, the UE
has to stop the transmission and perform LBT again when the MCOT of
the higher priority is reached. If an eNB schedules only a small
number of subframes (e.g. 1 subframe) for a UE in a UL transmission
burst and the UE chooses a set of channel access parameters
corresponding to a low priority, the UE will take a long time to
compete for channel access. This will decrease the spectrum
efficiency of the UL transmission.
[0005] In addition, the CWS adjustment is based on the HARQ-ACK
feedback information in the DL LBT procedure. For the UL, such an
explicit feedback is not available at the UE side currently in LAA.
A UE may assume that the PUSCH transmission is successful if it
does not detect a corresponding PDCCH/EPDCCH with DCI format 0/4
within a certain period of time. If the eNB does not continue to
retransmit a certain HARQ process (and thereby put this for higher
layer retransmission--i.e. additional delay and much larger
overhead in the end will be caused), the reliability of such
HARQ-ACK would be lowered.
[0006] Furthermore, the LBT gap as a new feature in the LAA frame
structure is being discussed in 3GPP. Considering multi-user
multiplexing in LAA UL, multiple UEs can perform their LBT
procedures in the LBT gap. If different UEs have different CWSs,
the possibility for these UEs to be multiplexed in this subframe is
relatively small. If the eNB knows the CWS of each UE, it can avoid
scheduling UEs with very different CWSs in one subframe or can
configure a more suitable LBT gap.
SUMMARY
[0007] Therefore, it's required to propose a technical solution for
maintaining UL channel access parameters at the eNB side to assist
a UE to implement the UL channel access in the eLAA-based
communication system.
[0008] According to a first aspect of the present disclosure, there
is provided a method for assisting a UE to implement a UL channel
access in a base station of an eLAA-based communication system. The
method includes determining a listen-before-talk (LBT) priority for
the UE; and transmitting a first signaling indicating the
determined LBT priority to the UE.
[0009] According to a second aspect of the present disclosure,
there is provided a method for assisting a UE to implement a UL
channel access in a base station of an eLAA-based communication
system. The method includes determining a set of UL channel access
parameters according to predetermined factors; and transmitting a
first signaling indicating a portion of the determined set of UL
channel access parameters to the UE.
[0010] According to a third aspect of the present disclosure, there
is provided a method for assisting a UE to implement a UL channel
access in a base station of an eLAA-based communication system. The
method includes indicating to the UE an expected transmission
duration scheduled for the UE in the UL transmission burst.
[0011] According to a fourth aspect of the present disclosure,
there is provided a method for implementing a UL channel access in
a UE of an eLAA-based communication system. The method includes
receiving from a base station a first signaling, which indicates a
LBT priority determined by the base station for the UE or a portion
of a set of UL channel access parameters determined by the base
station for the UE.
[0012] According to a fifth aspect of the present disclosure, there
is provided a method for implementing a UL channel access in a UE
of an eLAA-based communication system. The method includes
acquiring from a base station an expected transmission duration
scheduled for the UE in a UL transmission burst; or in case that
the expected transmission duration is not acquired from a base
station, setting the expected transmission duration to be not more
than 1 sub-frame.
[0013] According to a sixth aspect of the present disclosure, there
is provided a method for assisting a UE to maintain a CWS in a base
station of an eLAA-based communication system. The method includes
configuring a set of CWSs, wherein respective CWSs in the set of
CWSs are corresponding to different LBT priorities and the set of
CWSs is applicable to all UEs; and simultaneously updating CWSs of
all LBT priorities based on a predetermined trigger mechanism.
[0014] According to a seventh aspect of the present disclosure,
there is provided a method for assisting a UE to maintain a CWS in
a base station of an eLAA-based communication system. The method
includes configuring a set of CWSs for each UE, wherein each CWS in
the set of CWSs is corresponding to a different LBT priority; and
updating the CWS of the LBT priority based on a predetermined
trigger mechanism.
[0015] With the present disclosure, an enhanced UL channel access
mechanism is provided. In this mechanism, the eNB can provide some
assistance to facilitate UL access. Chances of multiple user
multiplexing and spectrum efficiency in LAA UL can be improved by
this solution.
[0016] In contrast, the existing technical solution using UL LBT
Category 4 also uses DL mechanism in UL. However, the LAA UL
transmission is substantially controlled by the eNB. Before a
consensus is achieved, if a user is able to implement the LBT
entirely freely, multiple user multiplexing will be interrupted and
spectrum efficiency will be reduced. This defect can be solved by
the technical solution of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Other features, objectives and advantages of the present
disclosure will become more apparent from following detailed
description of the nonrestrictive embodiments of the disclosure in
conjunction with the accompanying drawings, wherein:
[0018] FIG. 1 illustrates the frame structure for the UL LAA;
[0019] FIG. 2 illustrates the UL transmission burst according to an
embodiment of this disclosure; and
[0020] FIG. 3 illustrates a schematic view of CWS maintenance in an
eNB according to another embodiment of this disclosure.
[0021] In the accompanying drawings, same or similar reference
numbers are used for the same or corresponding parts or
features.
DETAILED DESCRIPTION
[0022] In this disclosure, a detailed design for the UL LBT
Category 4 is proposed to support multiple QoS traffics in the UL
LAA. The proposed LBT design is assisted by the eNB with the
following features:
[0023] Determination of a Set of Channel Access Parameters
[0024] The set of channel access parameters corresponding to the
LBT priority should be determined before the UE performs the LBT
Category 4 operation. The eNB will determine the channel access
parameters by considering the following factors: [0025]
transmission duration of the UL transmission burst; [0026] number
of the UEs scheduled in the UL transmission burst; [0027] traffic
types and interference situations of the scheduled UEs; [0028] LAA
TDD configuration; and [0029] partial or full of above factors.
[0030] In an embodiment of the disclosure, the channel access
parameters determined by the eNB should be further acquired by the
UE. This will be discussed later.
[0031] In an embodiment, the eNB can explicitly indicate the
selected LBT priority X to the UE via Layer 1 signaling. The set of
channel access parameters corresponding to the LBT priority X used
for the LBT operation can be determined in the UE.
[0032] Herein, preferably, the relations between LBT priorities and
a corresponding set of UL channel access parameters are pre-stored
at the eNB side and the UE side, respectively. The eNB then is able
to determine the LBT priority X according to the table after a set
of UL channel access parameters is determined. The UE is able to
determine corresponding UL channel access parameters according to
the table and based on the aforementioned signaling
[0033] In addition, the UE could maximize channel occupancy by
transmitting additional traffics corresponding to LBT priorities
larger than X only if the traffics corresponding to LBT priorities
smaller than or equal to X have been exhausted. In the LBT
framework, the LBT priorities smaller than or equal to X indicate
LBT priorities that are not less than the LBT priorities determined
by the eNB. The LBT priorities larger than X indicate LBT
priorities that are less than the LBT priorities determined by the
eNB.
[0034] Furthermore, the UE is able to further adjust the LBT
priorities according to its own traffic type.
[0035] In another embodiment, the eNB can indicate some or one of
the access parameters (e.g., the CWS value, or maximum channel
occupancy time, or the LBT gap configuration) to the UE via Layer 1
signaling, and then the UE has flexibility to interpret the other
access parameters according to the pre-defined LBT priority table
(the aforementioned table) and its own traffic type.
[0036] In another embodiment, if the information associated with an
expected transmission duration can be acquired by the UE, the UE
could determine the LBT priority X and the corresponding UL channel
access parameters with any or any combination of the following
considerations:
[0037] 1. The MCOT of the selected LBT priority X shall not be
shorter than the expected transmission duration.
[0038] 2. The traffic corresponding to the LBT priorities smaller
than or equal to X can be transmitted in the expected transmission
duration.
[0039] Herein, the expected transmission duration indicates the
subframes or time scheduled for transmission by the UE in the UL
transmission burst.
[0040] Furthermore, similarly, as mentioned above, the UE could
maximize channel occupancy by transmitting additional traffics
corresponding to LBT priorities larger than X only if the traffics
corresponding to LBT priorities smaller than or equal to X have
been exhausted.
[0041] Preferably, the transmission duration can be indicated to
the UE from the eNB in either an implicit or an explicit
manner.
[0042] In an embodiment, the eNB can dynamically or semi-statically
inform the expected transmission duration to the UE through Layer 1
signaling.
[0043] In another embodiment, the UE can acquire the transmission
duration according to a UL grant in case of multi-subframe
scheduling.
[0044] In yet another embodiment, the UE could assume that the
transmission duration is not more than one subframe if no specific
information is received.
[0045] In each of the above embodiments, the UE will perform an LBT
operation based on the determined UL channel access parameters.
[0046] Preferably, when multiple UEs will perform the LBT
operations in a transmission burst, the eNB can configure the same
set of access parameters to all UEs or configure different sets of
access parameters to respective UEs.
[0047] CWS Maintenance
[0048] The eNB can help the UE to maintain and adjust the CWS
value.
[0049] a) Solution 1: A Common CWS maintenance is configured for
all UEs served by the eNB.
[0050] In this solution, the eNB maintains only one set of CWSs
with respect to different priorities of all UEs. Table 1 shows a
CWS table for one UE in which corresponding CWSs are set for
different priorities. Furthermore, in this embodiment, all UEs have
the same CWS table. That is to say, only one set of CWSs needs to
be maintained.
TABLE-US-00001 TABLE 1 CWSs for a UE Priority 1 CWS 1 Priority 2
CWS 2 Priority 3 CWS 3 Priority 4 CWS 4
[0051] In this solution, the CWSs will be simultaneously updated
for all LBT priorities based on the result of the CWS trigger
mechanisms.
[0052] In an embodiment, the CWS trigger mechanism can be based on
the PUSCH decoding result in the first subframe of the last UL
transmission burst. In the last UL transmission burst, only the
PUSCH decoding result of UEs that perform LBT Category 4 operations
are considered. It should be noted that the last UL transmission
burst corresponding to a UE may be different for each UE and
whether it is successful in decoding is also different. Herein,
PUSCH decoding result of those UEs that implement LBT Category 4
operations will impact the update of aforementioned CWSs.
[0053] In an embodiment of this disclosure, the last UL
transmission burst is for example completely a UL transmission
burst.
[0054] In another embodiment, the CWS trigger mechanism can be
based on PUSCH decoding result in the last valid subframe of the
last UL transmission burst. Similarly, in the last UL transmission
burst, only PUSCH decoding result of UEs that perform LBT Category
4 operations are considered. Furthermore, the last UL transmission
burst corresponding to a UE may be different for each UE and
whether it is successful in decoding is also different. Similarly,
herein, PUSCH decoding result of those UEs that implement LBT
Category 4 operations will impact the update of aforementioned
CWSs.
[0055] Similarly, the last UL transmission burst is for example
completely a UL transmission burst.
[0056] In yet another embodiment, the CWS trigger mechanism can be
based on PUSCH decoding result in all subframes of the last UL
transmission burst. In the last UL transmission burst, all UEs
perform UL transmissions. In this embodiment, as long as the UEs
perform the UL transmissions, the PUSCH decoding result of the UEs
will impact the update of the CWSs.
[0057] Preferably, the PUSCH decoding result can be defined as the
ratio of the number of incorrectly decoded PUSCHs to the number of
correctly decoded PUSCHs. If this ratio is larger than a
pre-defined value, the CWSs will be exponentially or linearly
increased. Otherwise, the CWSs will be reset to the minimum CWSs
corresponding to respective priorities.
[0058] Finally, the eNB will transmit the updated CWSs or a backoff
counter generated therefrom to the UE via a Layer 1 signaling.
[0059] b) Solution 2: Individual CWS maintenances are configured
for different UEs.
[0060] The eNB maintains individual sets of CWSs with respect to
different priorities for respective UEs. To adjust CWSs of each UE,
the follow solutions are considered.
[0061] i. For all LBT priorities, CWSs will be exponentially or
linearly updated based on the result from the CWS trigger
mechanism. In an embodiment, the CWS trigger mechanism can be based
on the PUSCH decoding result of the first subframe in the last UL
transmission burst. In the last UL transmission burst, the UE
performs LBT Category 4 operation.
[0062] In an embodiment of this disclosure, the last UL
transmission burst is for example completely a UL transmission
burst.
[0063] Furthermore, if the PUSCH is decoded correctly, all CWSs of
different LBT priorities can be reset to their minimum values.
Otherwise, the CWSs will be exponentially or linearly
increased.
[0064] ii. For conditional LBT priorities, CWSs will be updated. In
an embodiment, only the LBT priority utilized in the last
transmission burst will update its CWS. Other LBT priorities
maintain their CWS values.
[0065] Furthermore, a CWS can be reset if the number of times for
using its maximal value reaches a predetermined number of
times.
[0066] Preferably, for a certain UE, its CWS can be reset if the UE
is not scheduled for a predetermined period of time.
[0067] Finally, similar to solution 1, when the UE is scheduled for
UL transmission, the eNB will transmit the CWS value or a backoff
counter generated therefrom to the UE via a Layer 1 signaling.
[0068] Embodiments of this disclosure will be set forth in details
hereinafter. Specifically, the proposed UL channel access
enhancement with eNB assistance includes the following
features:
[0069] Determining the Set of Channel Access Parameters
[0070] The eNB determines the channel access parameters for the UE
that will perform the LBT Category 4 operation before the UL
transmission. We can assume a scenario as shown in FIG. 2.
[0071] The UE1 and UE2 will perform LBT Category 4 operations
before their UL transmissions. The eNB can help to determine the
channel access parameters used in the LBT operations for the two
UEs. The transmission duration for UE1 is 4 ms and the transmission
duration for UE2 is 2 ms. According to the LBT priority definition
in DL, UE1 should use a LBT priority larger than or equal to 3 and
UE2 can use a LBT priority larger than or equal to 1 due to MCOT
restriction. To obtain the channel access parameters at UE sides,
the following options can be considered:
[0072] 1. The eNB indicates the LBT priorities to UEs via Layer 1
signaling.
[0073] If the eNB configures a common set of UL channel access
parameters for all UEs, the eNB can indicate the LBT priority 3 to
both UE1 and UE2.
[0074] If the eNB configures different channel access parameters
for each UE, the eNB could indicate the LBT priority 3 to UE1 and
the LBT priority 1 to UE2.
[0075] 2. The eNB indicates some of the access parameters (e.g.,
the CWS value, or maximum channel occupancy time, or the LBT gap
configuration) to the UE via Layer 1 signaling.
[0076] For example, the eNB can indicate the MCOT to UEs. Each UE
can determine all UL channel access parameters according to its own
traffic, the received information and predefined LBT priority.
[0077] 3. If information on expected transmission duration can be
acquired, the UE could determine the UL channel access parameters
by itself without determining the UL channel access parameters and
the LBT priorities by the eNB.
[0078] Herein, the eNB indicates the transmission duration to the
UE explicitly or implicitly. By acquiring the transmission
duration, the UE can select the UL channel access parameters
according to the pre-defined rule described above. For example, UE2
could use LBT priority 1 for channel access according to the
transmission duration although it has only Best Effort traffic.
[0079] CWS Maintenance
[0080] Solution 1: A common CWS maintenance is configured for all
UEs served by the eNB.
[0081] In this solution, the eNB may maintain only one set of CWSs
with respect to different priorities for all UEs. Also assuming the
scenario in FIG. 2, UE1 and UE2 perform LBT Category 4 procedures
for UL transmission bursts. If the eNB can decode the PUSCHs for
the UE1 and UE2 in the first subframe of the UL transmission burst
successfully, all the CWSs can be reset to minimum values
corresponding to different priorities. If one of the PUSCHs cannot
be decoded, all CWSs should be increased. In a word, CWSs in
different priorities should be updated simultaneously as an example
shown in FIG. 3.
[0082] Solution 2: Individual CWS maintenances are configured for
different UEs.
[0083] For each UE, the eNB maintains a set of CWSs with respect to
different priorities.
[0084] Also assuming the scenario in FIG. 2, the eNB will update
the CWSs of UE1 and the CWSs of UE2 after it decodes the first
PUSCH of the UL transmission burst. [0085] For all LBT priorities,
CWSs are updated.
[0086] If the eNB can decode the PUSCH correctly, all LBT
priorities reset their CWSs. Otherwise, all LBT priorities increase
the CWS values exponentially or linearly. [0087] For conditional
LBT priorities, CWSs will be updated.
[0088] In an embodiment, only the LBT priority used in the PUSCH
will update its CWS.
[0089] It should be understood that the above embodiments which
constitute a part of the principle of the disclosure are intended
to describe but not to limit this disclosure.
[0090] It should be noted that the above embodiments are
illustrative but not to limit this disclosure thereto. All
technical solutions that are not apart from the spirit of the
disclosure should fall into the protecting scope of the disclosure.
Different technical features, apparatuses and methods presented in
different embodiments can be combined to achieve beneficial
effects. Furthermore, any reference number in claims should not be
construed to limit the related claims. The word "comprise" or
"include" does not exclude the presence of apparatuses or steps
that are not listed in the claims and description.
* * * * *