CN107294662B - Method and apparatus for adjusting CWS values for UL transmissions at UE side - Google Patents

Method and apparatus for adjusting CWS values for UL transmissions at UE side Download PDF

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Publication number
CN107294662B
CN107294662B CN201610193279.9A CN201610193279A CN107294662B CN 107294662 B CN107294662 B CN 107294662B CN 201610193279 A CN201610193279 A CN 201610193279A CN 107294662 B CN107294662 B CN 107294662B
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cws
value
cws value
adjusting
harq feedback
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CN107294662A (en
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谷俊嵘
刘建国
陶涛
孟艳
王大卫
骆喆
沈钢
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Nokia Shanghai Bell Co Ltd
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Nokia Shanghai Bell Co Ltd
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Priority to PCT/IB2017/000506 priority patent/WO2017168258A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
    • H04W74/0816—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA] with collision avoidance
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1806—Go-back-N protocols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/12—Wireless traffic scheduling
    • H04W72/1263—Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows
    • H04W72/1268—Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows of uplink data flows
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/002—Transmission of channel access control information
    • H04W74/004—Transmission of channel access control information in the uplink, i.e. towards network

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Quality & Reliability (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention provides a method and a device for adjusting CWS values for UL transmission at a UE side, wherein the CWS values are between a preset maximum CWS value and a preset minimum CWS value. The method comprises the following steps: performing a CCA a plurality of times to determine a measurement result of a channel status in each CCA in one UL LBT period; and adjusting the CWS value according to the measurement result of the channel state of the CCA for the next UL LBT period.

Description

Method and apparatus for adjusting CWS values for UL transmissions at UE side
Technical Field
The present invention relates generally to the field of wireless communications, and more particularly, to a method and apparatus for adjusting a Contention Window Size (CWS) for Uplink (UL) transmission at a UE side. Method for adjusting CWS values for UL transmission at UE side
Background
In third generation partnership project (3GPP) Long Term Evolution (LTE) Rel-13, Downlink (DL) transmission for licensed-assisted access (LAA) to unlicensed spectrum is specified (see reference [1 ]). Where Listen-before-Talk (LBT) is defined for LAA, which requires the base station to perform a channel access procedure prior to transmission and only transmit if the procedure is successful. That is, prior to data transmission, Clear Channel Assessment (CCA) will be performed (e.g., using energy detection, carrier detection, a combination thereof, or the like), and the Channel can be accessed only when the base station assesses the Channel status as being Clear.
In RAN #70, a new work item for enhanced licensed-assisted access (eLAA) for LTE is approved to support LAA SCell operation on unlicensed spectrum for UL transmission (see reference [2 ]). In eLAA, the User Equipment (UE) should also perform LBT before UL data transmission. Support for UL LBT based on Cat-4 (class 4) channel access procedure is agreed in RAN1# 84.
However, since the channel is multiplexed by a plurality of UEs in UL transmission, UL transmission is more complicated than DL transmission.
Since the UE is allocated only a part of the entire bandwidth, their UL transmission start boundaries should be aligned when multiple UEs start UL transmission after winning a channel through LBT, otherwise an interlock problem between UEs will occur. Interlocked UEs must wait for the next UL transmission opportunity without having an interlocking problem between base stations in DL transmission.
In UL transmission, multiple UEs are multiplexed, while in DL transmission there is no such multiplexing between base stations. Therefore, contention between UEs is very important, which determines whether the UEs can access the channel in time.
For example, due to interference from other Radio Access Technologies (RATs) in the vicinity or interference from neighboring UEs, it is possible that not all UEs will have UL transmissions occurring at the scheduled time instant. Therefore, LBT parameters related to contention between UEs should reflect channel conditions and be flexible.
Therefore, if the scheduled UEs still cannot win the channel for a longer time, it is necessary to adjust the LBT parameters related to the contention of these UEs.
The LBT parameters for the UL transmission of the UE may be adjusted by the UE itself or by the serving base station of the UE. However, since the UE can quickly obtain the channel condition in real time, for example, through CCA or the like, and the LBT parameter adjustment is finally applied on the UE side, the present invention focuses on the scheme of LBT parameter adjustment by the UE for UL transmission.
Disclosure of Invention
To this end, the present invention proposes a UE-side LBT parameter adjustment mechanism for UL transmission of the UE in the unlicensed band. The purpose of the adjustment is to enable harmonious coexistence of UEs, especially when UL transmissions of these UEs are multiplexed. The adjustment is mainly performed by the UE adjusting its contention window size.
According to some embodiments of the present invention, there is provided a method for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the method comprising: performing a CCA a plurality of times to determine a measurement result of a channel status in each CCA in one UL LBT period; and adjusting the CWS value according to the measurement result of the channel state of the CCA for the next UL LBT period.
According to further embodiments of the present invention, there is provided a method for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the method comprising: acquiring information about HARQ feedback values of a reference subframe set; and adjusting the CWS value according to the information of the HARQ feedback value to be used for a next UL LBT period.
According to further embodiments of the present invention, there is provided an apparatus for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the apparatus comprising: a CCA measuring unit for performing CCA a plurality of times to determine a measurement result of a channel status in each CCA in one UL LBT period; and a CWS adjusting unit for adjusting the CWS value according to the measurement result of the channel status of the CCA for multiple times to be used for a next UL LBT period.
According to further embodiments of the present invention, there is provided an apparatus for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the apparatus comprising: a HARQ feedback value acquisition unit configured to acquire information on a HARQ feedback value of a reference subframe set; and a CWS adjusting unit for adjusting the CWS value according to the information of the HARQ feedback value to be used for a next UL LBT period.
By utilizing the scheme of the invention, the problem of interlocking and competition of UL transmission of a plurality of UEs is solved and the efficiency of adjusting the LBT parameter is improved by adjusting the CWS value at the UE side.
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The present invention will be better understood and other objects, details, features and advantages thereof will become more apparent from the following description of specific embodiments of the invention given with reference to the accompanying drawings. In the drawings:
fig. 1 illustrates a flow chart of a method for adjusting CWS values for UL transmission at the UE side according to some embodiments of the present invention;
fig. 2 shows a schematic diagram of a UL LBT procedure with variable CWS value;
fig. 3 shows a flow chart of a method for adjusting CWS values for UL transmission at the UE side according to further embodiments of the present invention;
fig. 4 illustrates a block diagram of an apparatus for adjusting CWS values at the UE side for UL transmission according to some embodiments of the present invention; and
fig. 5 shows a block diagram of an apparatus for adjusting CWS values for UL transmission at the UE side according to further embodiments of the present invention.
Detailed Description
Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
Fig. 1 shows a flow diagram of a method 100 for adjusting CWS values for UL transmission at the UE side, according to some embodiments of the present invention. Wherein in the method 100, the CWS value is adjusted based on the CCA measurement.
As previously described, the UE may perform CCA multiple times in one UL LBT period to determine the channel status prior to UL transmission. Fig. 2 shows a schematic diagram of a UL LBT procedure with a variable CWS value. As shown in fig. 2, it is assumed that the first two symbols of the starting subframe of one burst transmission are reserved for performing the LBT procedure of UL transmission. It can be seen that in one LBT period, after the contention window, the UE performs CCA multiple times. After the CCA is completed multiple times of the LBT period and the channel is won, the preamble is not transmitted but delayed by a self-delay period to ensure that UL transmission start times of the UEs are aligned with each other. In the method 100, the CWS value is adjusted according to the measurement result of CCA in the current LBT procedure for the next LBT period.
Note that the adjustment of the CWS value may also be applied to the LBT procedure in the uplink pilot time slot (UpPTS). Furthermore, it will be understood by those skilled in the art that fig. 2 includes 12 symbols per sub-frame (i.e., extended Cyclic Prefix (CP)) for illustrating the frame structure diagram, however, the scheme described in the present invention can be applied to the case where each sub-frame includes 14 symbols (i.e., normal CP) in a completely similar manner.
Assuming that a maximum CWS value CWS is preset for each UE respectivelymaxAnd minimum CWS value CWSminThe CWS value can be in the CWSmaxAnd CWSminAnd (4) adjusting. Furthermore, CWSmaxAnd CWSminMay be the same for all UEs or different for each UE. For simplicity, consider the case where each UE has the same maximum CWS value and minimum CWS value.
As shown in fig. 1, the method 100 begins at step 110, where the CWS value of the UE is set to a minimum CWS value CWSminAs its initial value.
However, the present invention is not limited thereto, and the initial value of the CWS value of the UE may be set to the CWSmaxAnd CWSminWithout departing from the scope of the invention.
In step 120, the UE performs CCA a plurality of times in one UL LBT period to determine a measurement result of a channel status in each CCA.
As described previously, CCA may be performed, for example, using energy detection, carrier detection, a combination thereof, or the like, and a channel status is determined as "busy" or "idle" according to the detection result. The implementation of CCA is well known to those skilled in the art and will not be described further.
Next, in step 130, the CWS value is adjusted according to the measurement result of step 120 to be used for the next UL LBT period.
Specifically, step 130 includes step 131 of counting the number of times the measurement result of the channel state is "busy" in step 120, and determining a ratio between the number of times the measurement result of the channel state is "busy" and the total number of CCAs.
At step 132, it is determined whether the ratio is greater than a first threshold.
If the determination of step 132 is yes, indicating that the channel condition is relatively poor, the CWS value is increased according to a predetermined rule (step 134).
In one implementation, the predetermined rule includes an exponential increase. For example, each adjustment increases the CWS value to twice the original CWS value.
In another implementation, the predetermined rule includes a linear increase. For example, assuming that the range of possible values of the CWS value is {3,4,5,6,7}, the CWS value may be sequentially increased by discrete values within the range at each adjustment.
There may be further included between steps 132 and 134 a step 133 for determining whether the number of times the CWS value reaches the maximum CWS value is equal to or greater than a predetermined number of times, and increasing the CWS value according to a predetermined rule only if the number of times the CWS value reaches the maximum CWS value is less than the predetermined number of times (no in step 133) (step 134).
On the other hand, if the determination of step 132 is "no", it is further determined whether the ratio is less than a second threshold value (step 135). Wherein the second threshold is less than the first threshold.
If the determination of step 135 is yes, indicating that the channel state is relatively idle, the CWS value may be reset to the minimum CWS value (step 136).
In another implementation, it is determined whether the UE is scheduled within a predetermined time period, and the CWS value is reset to a minimum CWS value (not shown in the figure) when it is determined that the UE is not scheduled within the predetermined time period.
After step 136 or when the determination result of step 135 is no (the ratio between the number of times the measurement result indicating the channel status is busy and the total number of times of CCA is within the normal range, i.e., greater than the second threshold and less than the first threshold), the CWS value is not adjusted and the current CWS value is used for the next LBT period (step 140).
Fig. 3 shows a flow chart of a method 300 for adjusting CWS values for UL transmission at the UE side according to further embodiments of the present invention. Wherein, in the method 300, the CWS value is adjusted based on a hybrid automatic repeat request (HARQ) feedback value for a next UL LBT period.
Similar to the method 100, it is assumed that the maximum CWS value CWS is preset for each UE separatelymaxAnd minimum CWS value CWSminThe CWS value can be in the CWSmaxAnd CWSminAnd (4) adjusting. Furthermore, CWSmaxAnd CWSminMay be the same for all UEs or different for each UE. For simplicity, consider the case where each UE has the same maximum CWS value and minimum CWS value.
As shown in fig. 3, the method 300 begins at step 310, where the UE's CWS value is set to a minimum CWS value CWSminAs its initial value.
However, the present invention is not limited thereto, and the initial value of the CWS value of the UE may be set to the CWSmaxAnd CWSminWithout departing from the scope of the invention.
In step 320, the UE acquires information on HARQ feedback values of a reference subframe set. The HARQ feedback values include positive Acknowledgements (ACKs) and Negative Acknowledgements (NACKs).
In one implementation, the UE may acquire the HARQ feedback value by detecting a corresponding Physical Downlink Control Channel (PDCCH)/Enhanced Physical Downlink Control Channel (EPDCCH) of Downlink Control Information (DCI) format 0/4. For example, the UE may acquire the HARQ feedback value of the previous UL transmission by detecting whether a new UL transmission is indicated in the PDCCH or EPDCCH.
In another implementation, the UE may obtain HARQ feedback values (ACK/NACK) from a Physical HARQ Indicator Channel (PHICH) in a licensed Carrier Component (CC).
In yet another implementation, the UE may obtain a HARQ feedback value (ACK/NACK) from a PHICH in the unlicensed CC if the PHICH is configured on the unlicensed CC.
Here, the HARQ feedback is described by using the base station to transmit the HARQ feedback to the UE through the PHICH as an example, however, it may be understood by those skilled in the art that the HARQ feedback may be implemented through other mechanisms.
Further, with respect to the reference subframe set, the present invention gives the following examples.
In one example, the HARQ feedback value for the reference subframe set may be an ACK or NACK for the first subframe of a previous burst transmission. Since contention and collisions are most likely to occur at the beginning of a burst transmission, subsequent transmissions in a burst transmission will preempt the channel, during which other RATs or UEs will detect that the channel is busy and refrain from transmitting.
In another example, the HARQ feedback value for the reference subframe set may be an ACK or NACK for the last subframe that has an ACK or NACK available in the previous burst transmission. This is because the last subframe with an available ACK/NACK in the previous subframe is feedback of the most recent transmission in the UL unlicensed channel, and therefore it would be more accurate to use the ACK/NACK to indicate UL channel conditions.
In yet another example, the HARQ feedback value for the reference subframe set may be ACK or NACK for all subframes in the previous burst transmission. That is, all ACK/NACKs of subframes in the previous burst may be used for CWS adjustment.
Next, in step 330, the CWS value is adjusted according to the information of the HARQ feedback value obtained in step 320 to be used for the next UL LBT period.
Specifically, step 330 includes step 331, in which a NACK ratio in the HARQ feedback values of the reference subframe set is obtained.
In one implementation, the UE receives each individual HARQ feedback value (ACK or NACK) of the reference subframe set from the base station in accordance with any of the aforementioned methods and calculates a ratio of NACK feedback therein.
In another implementation, the UE receives statistics of HARQ feedback values of the reference subframe set (instead of individual ACKs or NACKs) from the base station, the statistics indicating a ratio of NACK feedback in the HARQ feedback values of the reference subframe set.
At step 332, it is determined whether the ratio is greater than a third threshold.
If the determination of step 332 is yes, indicating that the channel condition is relatively poor, the CWS value is increased according to a predetermined rule (step 334).
In one implementation, the predetermined rule includes an exponential increase. For example, each adjustment increases the CWS value to twice the original CWS value.
In another implementation, the predetermined rule includes a linear increase. For example, assuming that the range of possible values of the CWS value is {3,4,5,6,7}, the CWS value may be sequentially increased by discrete values within the range at each adjustment.
Wherein, between the steps 332 and 334, a step 333 may be further included for determining whether the number of times the CWS value reaches the maximum CWS value is equal to or greater than a predetermined number of times, and increasing the CWS value according to a predetermined rule only if the number of times the CWS value reaches the maximum CWS value is less than the predetermined number of times (no in step 333) (step 334).
On the other hand, if the determination of step 332 is "no," a further determination is made as to whether the ratio is less than a fourth threshold (step 335). Wherein the fourth threshold is less than the third threshold.
If the determination of step 335 is yes, indicating that the channel state is relatively idle, the CWS value may be reset to the minimum CWS value (step 336).
In another implementation, it is determined whether the UE is scheduled within a predetermined time period, and the CWS value is reset to a minimum CWS value (not shown in the figure) when it is determined that the UE is not scheduled within the predetermined time period.
After step 336 or when the determination result of step 335 is "no" (indicating that the ratio of NACKs in the HARQ feedback values of the reference subframe set is within the normal range (i.e., greater than the fourth threshold and less than the third threshold)), the CWS value is not adjusted and the current CWS value is used for the next LBT period (step 340).
According to another aspect of the invention, in the method 100 or 300, when only one LBT procedure is maintained for all types of traffic UEs, the CWS adjustment may be designed as follows:
in one design, when the CWS value of traffic belonging to one priority class (e.g., class 1) is adjusted and a new traffic type of another priority class begins transmission, no adjustment is made to the CWS values of the other priority classes. Since UE traffic is assigned a certain priority, the CWS value is adapted to the procedure, which works well for priority class 1. The UE may start a new CWS adaptation procedure for a new traffic type and win the channel according to the channel situation.
In another design, when the CWS for traffic belonging to one priority class (e.g., class 1) is adjusted and a new traffic type for another priority class begins transmission, the CWS values for all priority classes are adjusted. This is because a new traffic type arrives and it belongs to different priority classes with different CWS values. The adaptation should make it easier to adapt the new traffic type to the channel conditions.
According to another aspect of the present invention, in the method 100 or 300, when the UE simultaneously maintains a plurality of LBT procedures with different CWS values, and one traffic type corresponds to one LBT procedure, the CWS value of each LBT procedure may be adjusted according to either one of the methods 100 or 300.
For flexibility and efficiency, multiple LBT procedures may be maintained for UE UL transmissions of different traffic types in the unlicensed band. Typically, each traffic type has a specific priority class with a different CWS value. When UL transmissions are granted by the base station, the base station does not know which type of traffic the UE wants to transmit. At this time, the type of traffic to be transmitted is decided by the UE. Therefore, the UE should simultaneously maintain multiple LBT procedures with different CWS values, one traffic type corresponding to one LBT procedure. The CWS value for each LBT procedure can be adjusted individually. Once an LBT procedure first acquires a channel, the associated traffic type may be delivered first.
Fig. 4 illustrates a block diagram of an apparatus 400 for adjusting a CWS value at a UE side for UL transmission, where the CWS value is between a preset maximum CWS value and a minimum CWS value, according to some embodiments of the present invention.
As shown in fig. 4, the apparatus 400 includes a CCA measuring unit 410 for performing CCA a plurality of times to determine a measurement result of a channel state in each CCA in one UL LBT period; and a CWS adjusting unit 420 for adjusting the CWS value according to the measurement result of the channel status of the CCA for a plurality of times to be used for the next UL LBT period.
In one implementation, the CWS adjusting unit 420 is further configured to count the number of times that a measurement result of a channel state in multiple CCAs is busy; and adjusting the CWS value according to a ratio between a number of times that a measurement of a channel state is busy in a plurality of CCAs and a total number of times of the plurality of CCAs.
In one implementation, the CWS adjustment unit 420 is further configured to increase the CWS value according to a predetermined rule if the ratio is greater than a first threshold.
In one implementation, the predetermined rule includes increasing exponentially or linearly.
In one implementation, the CWS adjustment unit 420 is further configured to reset the CWS value to a minimum CWS value if the ratio is less than a second threshold.
In one implementation, CWS adjustment unit 420 is further configured to determine whether the number of times the CWS value reaches the maximum CWS value is greater than or equal to a predetermined number of times; and resetting the CWS value to the minimum CWS value when it is determined that the number of times the CWS value reaches the maximum CWS value is greater than or equal to the predetermined number of times.
In one implementation, CWS adjustment unit 420 is further configured to determine whether the UE is scheduled within a predetermined time period; and resetting the CWS value to the minimum CWS value when it is determined that the UE is not scheduled within the predetermined time period.
Fig. 5 shows a block diagram of an apparatus 500 for adjusting a CWS value at a UE side for UL transmission according to further embodiments of the present invention, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value.
As shown in fig. 5, the apparatus 500 includes a HARQ feedback value obtaining unit 510 for obtaining information on HARQ feedback values of a reference subframe set; and a CWS adjusting unit 520 for adjusting the CWS value according to the information of the HARQ feedback value to be used for the next UL LBT period.
In one implementation, the HARQ feedback value obtaining unit 510 is configured to obtain the HARQ feedback value according to any one of the following items: acquiring a HARQ feedback value by detecting a corresponding PDCCH or EPDCCH of DCI format 0/4; obtaining a HARQ feedback value from a PHICH in a grant CC; obtaining a HARQ feedback value from a PHICH in an unlicensed CC; or receiving a statistical result of the HARQ feedback values of the reference subframe set from the serving base station of the UE, wherein the statistical result indicates the NACK ratio in the HARQ feedback values of the reference subframe set.
In one implementation, the CWS adjusting unit 520 is further configured to obtain a NACK ratio in the HARQ feedback values of the reference subframe set; the CWS value is adjusted according to the ratio.
In one implementation, the HARQ feedback values for the reference subframe set include any one of: ACK or NACK of the first subframe of the previous burst transmission; ACK or NACK of the last subframe having ACK or NACK available in the previous burst transmission; or ACK or NACK for all subframes in the previous burst transmission.
In one implementation, the CWS adjustment unit 520 is further configured to increase the CWS value according to a predetermined rule if the ratio is greater than a third threshold.
In one implementation, the predetermined rule includes increasing exponentially or linearly.
In one implementation, the CWS adjustment unit 520 is further configured to reset the CWS value to a minimum CWS value if the ratio is less than a fourth threshold.
In one implementation, CWS adjustment unit 520 is further configured to determine whether the number of times the CWS value reaches the maximum CWS value is greater than or equal to a predetermined number of times; and resetting the CWS value to the minimum CWS value when it is determined that the number of times the CWS value reaches the maximum CWS value is greater than or equal to the predetermined number of times.
In one implementation, CWS adjustment unit 520 is further configured to determine whether the UE is scheduled within a predetermined time period; and resetting the CWS value to the minimum CWS value when it is determined that the UE is not scheduled within the predetermined time period.
Herein, the first threshold, the second threshold, the third threshold and/or the fourth threshold, and the predetermined number of times (k) and the predetermined period of time, etc. may be preset according to a specific application or according to experience. For example, the first threshold may be set to 70%, the second threshold is 10%, the third threshold is 80%, and the fourth threshold is 10%, it is necessary to ensure that the first threshold > the second threshold, and the third threshold > the fourth threshold; the predetermined number of times (k) can be selected to be any positive integer; the predetermined period of time may be selected to be minutes after the UE status becomes active, and so on.
By utilizing the scheme of the invention, the problem of interlocking and competition of UL transmission of a plurality of UEs is solved and the efficiency of adjusting the LBT parameter is improved by adjusting the CWS value at the UE side.
The methods disclosed herein are described herein with reference to the accompanying drawings. It should be understood, however, that the order of steps shown in the drawings and described in the specification is merely exemplary and that the method steps and/or actions may be performed in a different order and are not limited to the specific order shown in the drawings and described in the specification without departing from the scope of the claims.
In one or more exemplary designs, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. Such computer-readable media can comprise, for example, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of instructions or data structures and which can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.
The various illustrative logical blocks, modules, and circuits described in connection with the disclosure may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosure is provided to enable any person skilled in the art to make or use the present invention. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the present invention is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Reference documents:
[1]3GPP TS 36.213,“E-UTRA；Physical layer procedures(Release-13)”,v13.0.0,Dec.2015.
[2]RP-152272,“New Work Item on enhanced LAA for LTE,”Ericsson,Huawei,7th-10th Dec.2015

Claims (18)

1. a method for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the method comprising:
performing a CCA a plurality of times to determine a measurement result of a channel status in each CCA in one UL LBT period; and
adjusting the CWS value according to the measurement result of the channel state of the CCA for the next UL LBT period;
wherein the method further comprises:
when the UE simultaneously maintains a plurality of LBT procedures with different CWS values and one traffic type corresponds to one LBT procedure, the CWS value for each LBT procedure is individually adjusted.
2. The method of claim 1, wherein adjusting the CWS value according to the measurement of the channel state of the multiple CCAs comprises:
counting the number of times that the measurement result of the channel state in the CCA is busy;
and adjusting the CWS value according to the ratio of the number of times of busy channel state measurement results in the CCAs and the total number of times of the CCAs.
3. The method of claim 2, wherein adjusting the CWS value according to the ratio comprises:
if the ratio is greater than a first threshold, the CWS value is increased according to a predetermined rule.
4. The method of claim 3, wherein the predetermined rule comprises increasing exponentially or linearly.
5. The method of claim 2, wherein adjusting the CWS value according to the ratio comprises:
resetting the CWS value to the minimum CWS value if the ratio is less than a second threshold.
6. The method of claim 3, further comprising:
determining whether the number of times the CWS value reaches the maximum CWS value is greater than or equal to a predetermined number of times; and
resetting the CWS value to the minimum CWS value when it is determined that the number of times the CWS value reaches the maximum CWS value is greater than or equal to the predetermined number of times.
7. The method of claim 3, further comprising:
determining whether the UE is scheduled within a predetermined time period; and
resetting the CWS value to the minimum CWS value when it is determined that the UE has not been scheduled within the predetermined time period.
8. A method for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the method comprising:
acquiring information about HARQ feedback values of a reference subframe set; and
adjusting the CWS value according to the information of the HARQ feedback value to be used for a next UL LBT period;
wherein the method further comprises:
when the UE simultaneously maintains a plurality of LBT procedures with different CWS values and one traffic type corresponds to one LBT procedure, the CWS value for each LBT procedure is individually adjusted.
9. The method of claim 8, wherein obtaining information about HARQ feedback values for a reference subframe set comprises any one of:
acquiring a HARQ feedback value by detecting a corresponding PDCCH or EPDCCH of DCI format 0/4;
obtaining a HARQ feedback value from a PHICH in a grant CC;
obtaining a HARQ feedback value from a PHICH in an unlicensed CC; or
Receiving a statistical result of HARQ feedback values of a reference subframe set from a serving base station of the UE, the statistical result indicating a NACK ratio among the HARQ feedback values of the reference subframe set.
10. The method of claim 8, wherein adjusting the CWS value according to information of HARQ feedback values comprises:
acquiring the NACK ratio in the HARQ feedback values of the reference subframe set;
adjusting the CWS value according to the ratio.
11. The method of claim 10, wherein the HARQ feedback values for the reference subframe set comprise any of:
ACK or NACK of the first subframe of the previous burst transmission;
ACK or NACK of the last subframe having ACK or NACK available in the previous burst transmission; or
ACK or NACK for all subframes in the previous burst transmission.
12. The method of claim 10, wherein adjusting the CWS value according to the ratio comprises:
if the ratio is greater than a third threshold, increasing the CWS value according to a predetermined rule.
13. The method of claim 12, wherein the predetermined rule comprises increasing exponentially or linearly.
14. The method of claim 10, wherein adjusting the CWS value according to the ratio comprises:
resetting the CWS value to the minimum CWS value if the ratio is less than a fourth threshold.
15. The method of claim 12, further comprising:
determining whether the number of times the CWS value reaches the maximum CWS value is greater than or equal to a predetermined number of times; and
resetting the CWS value to the minimum CWS value when it is determined that the number of times the CWS value reaches the maximum CWS value is greater than or equal to the predetermined number of times.
16. The method of claim 12, further comprising:
determining whether the UE is scheduled within a predetermined time period; and
resetting the CWS value to the minimum CWS value when it is determined that the UE has not been scheduled within the predetermined time period.
17. An apparatus for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the apparatus comprising:
a CCA measuring unit for performing CCA a plurality of times to determine a measurement result of a channel status in each CCA in one UL LBT period;
a CWS adjusting unit, configured to adjust the CWS value according to the measurement result of the channel status of the CCA for multiple times to be used for a next UL LBT period; and
wherein the CWS adjustment unit is further configured to:
when the UE simultaneously maintains a plurality of LBT procedures with different CWS values and one traffic type corresponds to one LBT procedure, the CWS value for each LBT procedure is individually adjusted.
18. An apparatus for adjusting a CWS value for UL transmission at a UE side, wherein the CWS value is between a preset maximum CWS value and a minimum CWS value, the apparatus comprising:
a HARQ feedback value acquisition unit configured to acquire information on a HARQ feedback value of a reference subframe set;
a CWS adjusting unit for adjusting the CWS value according to the information of the HARQ feedback value to be used for a next UL LBT period; and
wherein the CWS adjustment unit is further configured to:
when the UE simultaneously maintains a plurality of LBT procedures with different CWS values and one traffic type corresponds to one LBT procedure, the CWS value for each LBT procedure is individually adjusted.
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