Method and device for transmitting data

Abstract

The present application proposes a method for transmitting data, comprising: a second device detecting the scheduling signaling sent by the first device, and determining the LBT mechanism and corresponding parameters of the contention channel configured by the first device; the second device performs LBT, and transmits uplink data after the LBT is successful. The LBT mechanism for data transmission of the second device can be set for a group or all second devices using a common control signaling, and the second device determines the LBT mechanism it adopts accordingly based on whether the common control signaling is received. The second device needs to report to the first device its ability to simultaneously transmit and receive on adjacent carriers, so that the first device can reasonably schedule the uplink and downlink transmissions of the second device based on this ability. The method of the present invention is used to improve the flexibility of the LBT mechanism for the base station to control the uplink transmission of the UE, avoid waste of uplink and downlink resources, and ensure friendly coexistence with other devices.

Description

[0001] This application is a divisional application of the invention patent application with application date of June 3, 2016, application number 201610391267.7, and invention name “Method and device for transmitting data”. Technical Field

[0002] The present invention relates to wireless communication system technology, and in particular to a method and device for transmitting data in an unlicensed frequency band. Background Art

[0003] The Long Term Evolution (LTE) system, standardized by the Third Generation Partnership Project (3GPP), supports three types of frame structures. These include frequency division duplex (FDD) and time division duplex (TDD), which are generally deployed in licensed bands. The third frame structure is used in unlicensed bands and coexists with other wireless access technologies based on detect-before-transmit (LBT). All three frame structures configure a radio frame length of 10ms, divided equally into 10 subframes of 1ms each. A subframe consists of two consecutive time slots of 0.5ms each, meaning the kth subframe consists of time slot 2k and time slot 2k+1, where k = 0, 1, ... 9. Figure 1 This is the frame structure of a TDD system. Each radio frame is divided into two equal 5ms half-frames. Each half-frame contains eight 0.5ms time slots and three special fields: the Downlink Pilot Time Slot (DwPTS), the Guard Period (GP), and the Uplink Pilot Time Slot (UpPTS). The total length of these three special fields is 1ms. The third frame structure also supports a partial subframe structure, where the beginning of the subframe is used for downlink transmission, equivalent to the DwPTS. A downlink transmission time interval (TTI) is defined on a subframe.

[0004] In LTE systems, carrier aggregation (CA) technology is used to achieve a larger operating bandwidth. One of the cells is the primary cell (Pcell), while the others are called secondary cells (Scells). The third frame structure deployed in the unlicensed band can be configured as an Scell, meaning that another cell in the licensed band is configured as a Pcell.

[0005] In the LTE system, the first n orthogonal frequency division multiplexing (OFDM) symbols of each downlink subframe can be used to transmit downlink control information, including the physical downlink control channel (PDCCH) and other control information, where n is equal to 0, 1, 2, 3 or 4. The remaining OFDM symbols can be used to transmit the physical downlink shared channel (PDSCH) or the enhanced physical downlink control channel (EPDCCH). In the LTE system, PDCCH and EPDCCH carry downlink control information (DCI) that allocates uplink channel resources or downlink channel resources, respectively called downlink assignment signaling (DL-Assignment) and uplink grant signaling (UL-Grant). In the LTE system, the DCI of different user equipment (UE) is sent independently, and the DL-Assignment and UL-Grant are sent independently.

[0006] In the LTE system, for uplink data transmission, the UL-Grant sent in downlink subframe n is used to schedule data transmission in uplink subframe n+k. Figure 2 As shown in , for FDD system, k is equal to 4. Figure 3 As shown, for TDD systems, due to the limitations of the frame structure, k is greater than or equal to 4. For the third frame structure, according to the progress of the current standardization meeting, the timing relationship between the UL-Grant and its scheduled uplink data can be dynamic, but the delay still meets the requirement of greater than or equal to 4.

[0007] According to the progress of discussions in the current standardization meeting, there are multiple LBT schemes for uplink transmission. One scheme is LBT Type 4 (CAT4), that is, the device generates a random number N based on the size of a certain contention window (CW). Only when the number of times it detects that the channel is idle reaches N times can it occupy the channel. Here, the device can immediately send a fill signal to occupy the channel until the start timing of the scheduled uplink transmission, and then start the scheduled uplink transmission; or, the device can also perform a self-delay (Self-Defer) process, but it needs to detect that the channel is idle for a length of T0 again before the start timing of the scheduled uplink transmission, for example, T0 is equal to 25us, before it can start the scheduled uplink transmission. Another scheme is LBT Type 2 (CAT2), that is, as long as the device detects that the channel is idle for a length of T1 before the start timing of the scheduled uplink transmission, for example, T1 is equal to 25us, the device can occupy the channel. Alternatively, another solution is NO LBT, that is, after the downlink transmission is completed, the device can delay for a period of time of T3, for example, T3 is equal to 16us, which is consistent with the short subframe interval (SIFS) of WiFi, and the device can start uplink transmission directly without performing LBT. The above-mentioned LBT schemes are still under discussion. One progress is that if the actual downlink data transmission time of the channel seized by the base station through its LBT operation is less than the maximum channel occupancy time (MCOT), then when scheduling uplink transmission within the remaining time of the above MCOT, the UE can perform CAT2 LBT; otherwise, the UE needs to perform CAT4 LBT. Based on the above-mentioned alternative LBT methods, how to schedule uplink transmission on unlicensed frequency band carriers is an urgent problem to be solved.

[0008] Furthermore, for the third frame structure, when a base station operates on multiple carriers with adjacent or closely spaced frequencies, it cannot simultaneously transmit and receive signals on these carriers. This is due to filter imperfections, causing the signal transmitted by the base station on one carrier to leak onto another, thereby interfering with reception on that carrier. Consequently, when a UE is configured with multiple carriers on an unlicensed band, how to effectively perform uplink transmissions on these multiple carriers is a pressing issue. Summary of the Invention

[0009] The present application provides a method, device and base station for transmitting data, and provides a method based on LBT competitive channels to ensure friendly coexistence with other systems in unlicensed frequency bands.

[0010] To achieve the above objectives, this application adopts the following technical solutions:

[0011] A method for transmitting data, comprising:

[0012] The second device detects the scheduling signaling sent by the first device, and determines the listen-before-talk LBT mechanism and corresponding parameters of the contention channel configured by the first device according to the scheduling signaling;

[0013] The second device performs LBT and transmits uplink data after the LBT is successful.

[0014] Preferably, the second device detecting the scheduling signaling sent by the first device includes:

[0015] The second device detects the first scheduling signaling sent by the first device;

[0016] The second device detects the second scheduling signaling sent by the first device, where the second scheduling signaling includes indication information of the LBT mechanism.

[0017] Preferably, the second device detecting the second scheduling signaling sent by the first device includes:

[0018] For a group or all second devices, detecting second scheduling signaling according to a common identifier (RNTI), where the second scheduling signaling indicates an LBT mechanism for uplink transmission;

[0019] Alternatively, a common PDCCH indicating a downlink subframe type is detected, where the common PDCCH indicates an LBT mechanism for uplink transmission.

[0020] Preferably, the second scheduling signaling indicates the LBT mechanism of uplink transmission in at least one of the following ways:

[0021] Use a bitmap to indicate the LBT mechanism used in each subframe;

[0022] Indicate the position of the first subframe in which the data transmission of the second device is scheduled, and indicate the LBT mechanism of each subframe in turn using a bit map;

[0023] Indicates a reference subframe, data transmission of the second device scheduled in the subframe before this reference subframe is based on the first LBT, and data transmission of the second device scheduled in other subframes is based on the second LBT.

[0024] Alternatively, two reference subframes are indicated. On the subframe corresponding to the first reference subframe, if data transmission of the second device is scheduled, the LBT mechanism is NO LBT; and, data transmission of the second device scheduled on the subframe after the first reference subframe and before the second reference subframe is based on CAT2, while data transmission of the second device scheduled on other subframes is based on CAT4.

[0025] Preferably, when the first scheduling signaling includes information indicating the LBT mechanism adopted by the second device, after the second device detects the first scheduling signaling sent by the first device, the method includes:

[0026] If the second device receives the second scheduling signaling, the second device competes for the channel according to the LBT mechanism indicated by the second scheduling signaling; if the second device does not receive the second scheduling signaling, the second device competes for the channel according to the LBT mechanism indicated by the first scheduling signaling, or adopts a predefined LBT mechanism to compete for the channel.

[0027] Preferably, when the first scheduling signaling does not include information indicating the LBT mechanism adopted by the second device, the method further includes:

[0028] If the second device receives the second scheduling signaling, it competes for the channel according to the LBT mechanism indicated by the second scheduling signaling; if the second device does not receive the second scheduling signaling, the second device adopts a predefined LBT mechanism to compete for the channel.

[0029] Preferably, with the base station as the first device and the UE as the second device, determining the LBT mechanism and corresponding parameters of the contention channel configured by the first device, performing uplink LBT and transmitting uplink data includes:

[0030] The UE reports to the base station its ability to transmit and receive simultaneously on adjacent carriers;

[0031] The UE receives signaling from the base station for scheduling uplink transmission of one or more carriers, where the signaling includes an LBT mechanism and corresponding parameters indicated by the base station;

[0032] The UE performs uplink LBT according to the scheduling of the base station and performs uplink transmission on one or more carriers on which LBT is successfully performed.

[0033] Preferably, the UE reporting to the base station its capability of simultaneously transmitting and receiving on adjacent carriers includes:

[0034] The UE reports only one simultaneous transmit and receive capability, and the capability applies to all combinations of channels / signals being transmitted and received.

[0035] Alternatively, the UE reports the simultaneous transmission and reception capabilities for different combinations of transmission and reception channels / signals respectively.

[0036] Preferably, the UE reporting to the base station its capability of simultaneously transmitting and receiving on adjacent carriers includes at least one of the following:

[0037] The UE reports the frequency band combinations it supports without restrictions on simultaneous transmission and reception, or the UE reports the frequency band combinations with restrictions on simultaneous transmission and reception;

[0038] Alternatively, the UE reports a frequency separation threshold T F , all frequency intervals are less than or equal to T FThe two carriers do not support simultaneous transmission and reception;

[0039] Alternatively, the UE reports a frequency separation threshold T F , all belong to different frequency bands and the frequency interval is less than or equal to T F The two carriers do not support simultaneous transmission and reception.

[0040] Preferably, the LBT mechanism and corresponding parameters indicated by the base station include:

[0041] For a group of carriers, the base station maintains the CAT4 related parameters of each carrier separately;

[0042] For a group of carriers, when the base station is configured to execute CAT4 only on one carrier, the method for the base station to determine its CW parameters is to determine it based on the CW and other parameters of all carriers in the group of carriers; or, to determine it based on the CW and other parameters of the carrier in the group of carriers that is currently actually scheduled for uplink transmission; or, for the carrier in the group of carriers that is currently actually scheduled for uplink transmission, when the uplink transmission that meets the scheduling is outside the MCOT of the base station on this carrier, the relevant parameters of the above-mentioned dynamically indicated CAT4 are determined based on the CW and other parameters of such carrier.

[0043] Preferably, the LBT mechanism and corresponding parameters indicated by the base station include:

[0044] For a group of carriers, if the base station is configured to implement CAT4 on only one carrier, the base station needs to configure the component carriers included in the group of carriers for the UE;

[0045] For a group of carriers, the base station maintains the CAT4 related parameters of each carrier respectively, and the base station does not need to configure the component carriers included in this group of carriers for the UE.

[0046] Preferably, the UE performing uplink LBT according to base station scheduling includes:

[0047] On each carrier, the UE operates according to the LBT mechanism instructed by the base station;

[0048] Alternatively, the UE may perform CAT4 on one carrier and CAT2 on other scheduled carriers.

[0049] Preferably, assuming that the base station needs to configure the uplink carrier of the UE to belong to multiple TAGs, the UE performs LBT according to the base station scheduling, including:

[0050] For carriers with a later TAG, the UE sends signal A to occupy the channel until the start timing of the uplink transmission scheduled for this carrier, and aligns the start timing of signal A with the start timing of the uplink transmission scheduled for carriers with an earlier TAG. The UE can start data transmission only after completing LBT before the start timing of signal A.

[0051] Alternatively, for the carrier of the TAG with earlier timing, the first part of its scheduled uplink transmission is discarded, so that the start timing of the uplink transmission is aligned with the start timing of the carrier of the TAG with later timing. The UE can start data transmission only after completing LBT before the start timing of the carrier of the TAG with later timing.

[0052] Preferably, the base station is the first device, the UE is the second device, the second device performs uplink LBT, and transmits uplink data after the LBT is successful, including:

[0053] When the channel is idle in the T0 us time period before the scheduled uplink transmission start timing, the UE sends uplink data. The idle time of T0 us is divided into the first 16 us and the subsequent k consecutive idle CCA time slots, where k is 1 and the CCA time slot length is 9 us. The front part of the first 16 us time period includes an idle CCA time slot.

[0054] Alternatively, when T is greater than or equal to T0, the UE detects that each CCA timeslot within the T0 time period is idle and the UE transmits uplink data; when T is less than T0, the UE detects that all times within the T time period are idle and the UE transmits uplink data, where T is the interval between the UE's CAT4 successful timing position and the scheduled UE's uplink transmission start timing;

[0055] Alternatively, when T is greater than or equal to T0, the UE detects that each CCA time slot in the T0 time period is idle, and the UE transmits uplink data; when T is less than T0, the time period in which the UE does not perform CCA detection in the time period T does not exceed X us, where X is a constant. When the UE detects that all other times in the time period T are idle, the UE transmits uplink data, where T is the interval between the UE's CAT4 successful timing position and the scheduled UE's uplink transmission start timing.

[0056] Preferably, the base station is the first device, the UE is the second device, and the LBT mechanism and corresponding parameters of the contention channel configured by the first device include:

[0057] The uplink reference subframe used by the base station to adjust the uplink CAT4 CW is the uplink subframe configured for the UE based on the CAT4 contention channel;

[0058] Alternatively, the uplink reference subframe used by the base station to adjust the uplink CAT4 CW is an uplink subframe configured for the UE based on a CAT2 and / or CAT4 contention channel;

[0059] Alternatively, the uplink reference subframe used by the base station to adjust the uplink CAT4 CW is an uplink subframe configured for the UE based on NO LBT, CAT2 and / or CAT4 contention channels.

[0060] By adopting the method of the present invention, the flexibility of the LBT mechanism of the base station controlling the uplink transmission of the UE is improved, waste of uplink and downlink resources is avoided, and friendly coexistence with other equipment is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Schematic diagram of the frame structure of an existing TDD system;

[0062] Figure 2 Schematic diagram of uplink scheduling timing relationship of existing FDD system;

[0063] Figure 3 Schematic diagram of uplink scheduling timing relationship of existing TDD system;

[0064] Figure 4 Schematic diagram of adjusting the LBT mechanism based on whether it is located in MCOT Figure 1 ;

[0065] Figure 5 Schematic diagram of adjusting the LBT mechanism based on whether it is located in MCOT Figure 2 ;

[0066] Figure 6 Flowchart of the LBT mechanism for configuring data transmission of the present invention;

[0067] Figure 7 A schematic diagram of an LBT mechanism for indicating data transmission according to the present invention;

[0068] Figure 8 A flowchart of a UE performing multi-carrier LBT according to the present invention;

[0069] Figure 9 Schematic diagram of a UE performing LBT on multiple carriers in the same TAG;

[0070] Figure 10 Schematic diagram of UE performing LBT on multiple carriers in different TAGs Figure 1 ;

[0071] Figure 11 Schematic diagram of UE performing LBT on multiple carriers in different TAGs Figure 1 ;

[0072] Figure 12 Schematic diagram of CAT4 contention channel based on self-delay;

[0073] Figure 13 This is a schematic diagram showing that the CAT4 channel detection period and the T0 us period do not overlap;

[0074] Figure 14 This is an illustration of the overlap between the CAT4 channel detection period and the T0 us period. Figure 1 ;

[0075] Figure 15 This is an illustration of the overlap between the CAT4 channel detection period and the T0 us period. Figure 2 ;

[0076] Figure 16 This is a diagram of the base station equipment of the present invention;

[0077] Figure 17 This is a diagram of the UE device of the present invention. DETAILED DESCRIPTION

[0078] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0079] Example 1

[0080] On a carrier in an unlicensed frequency band, a device uses LBT to seize a channel. The duration of its channel occupation cannot exceed the Maximum Channel Occupancy Time (MCOT), giving other devices an opportunity to compete for the channel. After a first device seizes a channel through LBT, if its actual data transmission time is less than the MCOT, then, when a second device is scheduled to transmit data after the first device's data transmission, the second device may perform a first LBT to determine whether data can be transmitted in that subframe, provided the current subframe falls within the MCOT of the first device's occupied channel. Otherwise, the second device must perform a second LBT to determine whether data can be transmitted in that subframe. The first LBT is more aggressive than the second LBT, making it easier to seize the channel. For example, the first LBT may be CAT2 LBT, and the second LBT may be CAT2 LBT; alternatively, the first LBT may be NOLBT, and the second LBT may be CAT2 LBT; alternatively, the first LBT may be NO LBT, and the second LBT may be CAT4 LBT. The first device may be a base station, and the second device may be one or more UEs. When the base station schedules multiple subframes for the UE, the UE may be scheduled to use only one or two of the three LBT mechanisms, or may be allowed to use all three LBT mechanisms.

[0081] The condition for determining whether the current subframe is within the MCOT of the channel occupied by the first device can be that the data transmission by the first device and the scheduled data transmission by the second device do not restrict the first device's data transmission and the scheduled data transmission by the second device to occupy consecutive subframes, but only requires that the sum of the data transmission time of the first device and the scheduled data transmission time of the second device does not exceed the MCOT. Alternatively, the condition for determining whether the current subframe is within the MCOT of the channel occupied by the first device can be that the data transmission by the first device and the scheduled data transmission by the second device occupy consecutive subframes, and that the sum of the data transmission time of the first device and the scheduled data transmission time of the second device does not exceed the MCOT. In both of the above methods, when calculating the sum of the data transmission time of the first device and the scheduled data transmission time of the second device (i.e., the total transmission time), the time interval reserved for performing the LBT operation, for example, one or more idle OFDM symbols, can be included in the total transmission time, or this time interval can be excluded from the total transmission time. Alternatively, if the total time from the completion of LBT channel occupation by the first device to the subframe position of the scheduled data transmission by the second device is less than or equal to the MCOT, the second device performs the first LBT regardless of whether the data transmission by the first device and the scheduled data transmission by the second device occupy consecutive subframes; otherwise, the second device performs the second LBT.

[0082] The aforementioned determination of whether a subframe is within the MCOT of the channel occupied by the first device is actually variable. Assume that the first device schedules data transmission from a second device in subframe n+k, for example, in an LTE system, where k is greater than or equal to 4. In subframe n, the first device determines whether the data transmission scheduled by the second device falls within the MCOT based on currently buffered uplink and downlink traffic information and scheduling delay k. However, prior to subframe n+k, changes in uplink and downlink traffic information may cause the determination of whether the data transmission scheduled by the second device still falls within the MCOT to change. Therefore, after the first device schedules data transmission from the second device in subframe n, a mechanism is required to allow the first device to determine the LBT mechanism for the data transmission of the second device in subframe n+k after subframe n and before subframe n+k. Adjusting the LBT mechanism can be accomplished by sending additional control information. On a carrier, whether a second device's data transmission falls within the MCOT is determined based on the first device's transmission time and the total transmission time of all second devices up to the current subframe. This determination is independent of a specific second device. Therefore, the control information for adjusting the LBT mechanism can be cell-wide or apply to a group or all second devices.

[0083] Two examples of changing the LBT of data transmission of the second device are described below, but in fact, the case of changing the LBT mechanism is not limited to these two cases.

[0084] Assume that the condition for the second device to perform the first LBT is that the data transmission of the first device and the scheduled data transmission of the second device are not restricted to occupy consecutive subframes, but only require that the sum of the data transmission time of the first device and the scheduled data transmission time of the second device does not exceed MCOT. Figure 4 As shown in the figure, assuming the MCOT is 8ms, when the base station sends a UL-Grant to schedule the UE's uplink transmission, due to low downlink traffic and other reasons, the base station decides to only send 6 subframes of downlink data. Therefore, the base station indicates that the scheduled uplink data transmission can use CAT2, because the total uplink and downlink transmission time is only 7ms, which is less than the MCOT. However, after the base station sends the UL-Grant, new downlink data arrives, and the base station temporarily decides to send 8ms of downlink data. This causes the previously scheduled uplink transmission to actually fall outside the MCOT, so the base station needs to send new control information to indicate that the LBT mechanism changes to CAT4.

[0085] Assume that the condition for the second device to perform the first LBT is that the data transmission of the first device and the scheduled data transmission of the second device occupy consecutive subframes, and the sum of the data transmission time of the first device and the scheduled data transmission time of the second device does not exceed MCOT. Figure 5 As shown in the figure, assuming that MCOT is equal to 8ms, when the base station sends a UL-Grant to schedule the UE's uplink transmission, due to reasons such as low downlink traffic volume, the base station decides to only send downlink data for 4 subframes. This results in the uplink and downlink transmissions not occupying the entire consecutive subframes, so the base station indicates that the scheduled uplink data transmission can use CAT4. However, after the base station sends the UL-Grant, new downlink data arrives. The base station temporarily decides to send 6ms of downlink data until the subframe before the uplink data is scheduled. As a result, the uplink and downlink transmissions occupy the entire consecutive subframes, and the total uplink and downlink transmission time is only 7ms, which is less than MCOT. Therefore, the base station can send new control information to indicate that the LBT mechanism changes to CAT2.

[0086] like Figure 6 Shown is a flow chart of the second device of the present invention determining its LBT mechanism and transmitting uplink data.

[0087] Step 601: The second device detects first scheduling signaling sent by the first device. The first scheduling signaling is used to schedule data transmission for the second device and indicates information such as the allocation of time-frequency resources and the MCS. For example, the first scheduling signaling is equivalent to an UL-Grant in existing LTE systems. The first scheduling signaling may or may not include uplink LBT information.

[0088] Step 602: The second device detects the second scheduling signaling sent by the first device, and the second scheduling signaling at least includes indication information related to the LBT mechanism. The second scheduling signaling may be sent to each second device separately. Alternatively, the second scheduling signaling may be applied to a group or all second devices. For example, the second scheduling signaling may be to reuse an existing DCI format, such as the number of bits of DCI 1A or DCI 1C, thereby reducing the number of blind detections of the second device. A common identifier (RNTI) may be allocated to a group or all second devices to indicate the second scheduling signaling; or, the cell common PDCCH defined for the downlink LAA system in LTE version 13 may be extended to indicate the LBT mechanism to be used for data transmission in the uplink subframe while indicating the downlink subframe type.

[0089] The LBT type indicated by the above-mentioned second scheduling signaling may be applicable to all types of uplink signals. Alternatively, the LBT types and parameter settings of different types of uplink signals may be different, or different types of uplink signals may be processed separately. For example, when PUSCH adopts CAT4, its contention window (CW) size is adjustable, while when SRS adopts CAT4, its CW is fixed. In this way, for different types of uplink signals, different second scheduling signaling may be sent to indicate their LBT types respectively, and the first device may be responsible for maintaining CAT4-related parameters. For subframes adopting CAT4, CAT4-related parameters may be further indicated; or, within the same second scheduling signaling, different domains may be used to indicate the LBT types of different types of uplink signals respectively, and the first device may be responsible for maintaining CAT4-related parameters. For subframes adopting CAT4, CAT4-related parameters may be further indicated. Alternatively, for the above-mentioned method of determining the LBT mechanism based on whether the uplink transmission is within the MCOT, since the LBT type applicable to an uplink subframe is fixed, the only difference is that when CAT4 is used, the CAT4 parameters may be different. Therefore, for multiple types of uplink signals, the same indication of the LBT type is shared, that is, there is no need to repeatedly indicate the LBT type; however, for the method in which the first device is responsible for maintaining the CAT4-related parameters, for the subframe using CAT4, the CAT4-related parameters need to be indicated separately for multiple types of uplink signals.

[0090] In the second scheduling signaling, when CAT4 parameters need to be indicated, the CAT4 parameters, including the CW size and / or backoff time, may be indicated for each uplink subframe; alternatively, only one set of CAT4 parameters may be indicated and applied repeatedly to each uplink subframe. When only one set of CAT4 parameters is indicated, the set of parameters may be derived from the maximum value of the CAT4 parameters in each scheduled uplink subframe, i.e., the indicated CW may be the maximum value of the CWs in each scheduled uplink subframe, or the indicated backoff time may be the maximum value of the backoff time in each scheduled uplink subframe.

[0091] For the above-mentioned second scheduling signaling, the method of indicating the LBT mechanism is described below.

[0092] The first method of indicating the LBT mechanism is to use a bitmap method to indicate the LBT mechanism used for each subframe in which the second device's data transmission is scheduled. For example, starting from the kth subframe after the subframe in which the second scheduling signaling is located, a bitmap is used to sequentially indicate the uplink LBT mechanism for each subframe. k is an integer or a predefined constant configured by high-layer signaling, and k can be 0, 1, or other values. For example, when k is equal to 0, it means that the end position of the downlink transmission is a downlink partial subframe, that is, the uplink transmission is located in the latter part of the same subframe, which is equivalent to the UpPTS in the existing LTE system. The present invention does not limit this part of the uplink resources to be used for PUSCH, PUCCH, PRACH, or SRS. Alternatively, assuming that the subframe in which the second scheduling signaling is located and the subframe in which the data transmission of the second device scheduled by the first scheduling signaling is located can be discontinuous, the second scheduling signaling can use an information field to indicate the starting point of the first subframe in which the second device's data transmission is scheduled, for example, indicating the offset of this subframe relative to the subframe in which the second scheduling signaling is located, and a bitmap is used to sequentially indicate the uplink LBT mechanism for each subframe starting from the first subframe in which the data transmission of the second device is scheduled. For the above two methods, for data transmission of the second device, if only one of the two LBT mechanisms can be used, one bit can be used to distinguish the LBT mechanisms; or if one of the three LBT mechanisms can be used, two bits can be used to distinguish the LBT mechanisms.

[0093] The second method of indicating the LBT mechanism is to indicate a reference subframe, for example, it may be to indicate an offset relative to the subframe where the second scheduling signaling is located. Then, on a subframe before the indicated reference subframe, if the data transmission of the second device is scheduled, the first LBT is used; on a subframe after the indicated reference subframe, if the data transmission of the second device is scheduled, the second LBT is used. Here, it can be predetermined that the data transmission of the second device scheduled on the subframe corresponding to the reference subframe uses the first LBT, or the second LBT. Here, from the perspective of the entire cell, the subframes for scheduling the data transmission of the second device may be continuous or discontinuous; in addition, the first subframe for scheduling the data transmission of the second device and the subframe where the second scheduling signaling is located may be continuous or discontinuous. The subframe corresponding to the reference subframe may be the one for scheduling the data transmission of the second device, or the one for not scheduling the data transmission of the second device.

[0094] The third method of indicating the LBT mechanism is to indicate two reference subframes, for example, they may respectively indicate the offset relative to the subframe where the second scheduling signaling is located. Then, on the subframe corresponding to the first reference subframe, if the data transmission of the second device is scheduled, the LBT mechanism is NO LBT; and all data transmissions of the second device scheduled on the subframe before the second reference subframe are based on CAT2, while data transmissions of other scheduled second devices are based on CAT4.

[0095] For situations where NO LBT needs to be distinguished, 1-bit information can also be used in the second scheduling signaling to indicate whether the first uplink transmission after the base station's downlink transmission ends uses NO LBT. If the last subframe of the base station's downlink transmission is a partial subframe and SRS transmission is triggered, it is necessary to indicate whether the uplink transmission of this subframe can use NOLBT; if the last subframe of the base station's downlink transmission is a partial subframe and SRS transmission is not triggered, it is necessary to indicate whether the uplink transmission of the next subframe of this subframe can use NO LBT; if the last subframe of the base station's downlink transmission is a complete subframe, it is necessary to indicate whether the uplink transmission of the next subframe of the last subframe of the base station's downlink transmission can use NO LBT. The indication of NO LBT can be to indicate whether the uplink transmission of the first uplink subframe scheduled by the base station uses NO LBT. The above-mentioned first uplink subframe can be a subframe for sending PUSCH or a subframe for sending only SRS. For example, the rear part of the downlink partial subframe, which is equivalent to the UpPTS part of the existing LTE, may trigger SRS transmission; or the above-mentioned SRS may also refer to SRS transmission within a complete uplink subframe. The indication of NO LBT may be to indicate the next subframe of the subframe where the second scheduling signaling is located, and whether to use NO LBT if uplink transmission is scheduled. Alternatively, the indication of NO LBT may be to indicate the subframe where the second scheduling signaling is located, and whether to use NO LBT if SRS transmission is triggered, that is, the subframe where the second scheduling signaling is located is a downlink partial subframe. Alternatively, the indication of NO LBT may be to indicate the subframe where the second scheduling signaling is located and the next subframe, and whether to use NO LBT if uplink transmission is scheduled. In order to effectively support NO LBT, the above-mentioned second scheduling signaling may be sent in the last subframe of the downlink transmission of the base station, or the last subframe and the second to last subframe, to indicate whether NO LBT can be used after the downlink transmission is completed.

[0096] According to the above method for processing the second scheduling signaling, for a second device, assuming that the first device schedules it to transmit on multiple subframes, the second device may perform a first LBT for each subframe that schedules the second device and is located within the MCOT of the channel occupied by the first device; and the second device may perform a second LBT for each subframe that schedules the second device and is located outside the MCOT of the channel occupied by the first device.

[0097] Alternatively, according to the above method for processing second-scheduling signaling, for a second device, assuming that the first device schedules it to transmit over multiple subframes, the second device may perform the first LBT for each subframe within the MCOT of the first device's occupied channel in which the second device is scheduled. For subframes of the second device scheduled outside the MCOT of the first device's occupied channel, if the second device successfully performs the second LBT within a subframe, the second device's data transmission within the MCOT of the second device's occupied channel may be permitted to use the first LBT. Specifically, for subframes of the second device scheduled outside the MCOT of the first device's occupied channel, the second device performs the second LBT on the earlier subframes in chronological order. If the second LBT fails, the second device still needs to perform CAT4 in the next subframe. If the second LBT succeeds in a subframe, the second device only needs to perform the first LBT in subsequent subframes within the MCOT of the second device's occupied channel in which the first device schedules the second device's transmission. Here, the second device may perform the first LBT on all subframes requiring LBT in which the first device subsequently schedules the transmission of the second device within the MCOT of the channel occupied by the second device; or, if the first LBT fails in one of the subframes, the second device needs to re-perform CAT4 in the next subframe requiring LBT.

[0098] like Figure 7 As shown, assuming that the MCOT is 6ms, after the base station schedules the UE's uplink transmission based on the first scheduling signaling, namely the UL-Grant, it can use the second scheduling signaling, such as the cell-common PDCCH, to indicate the LBT mechanism to be used in different subframes. Because the downlink transmission is for four subframes of data, the cell-common signaling indicates that the first two uplink subframes can use CAT2, while the subsequent subframes can only use CAT4. For example, let the subframe where the cell-common PDCCH is located be subframe n, then this indication information can indicate an offset of 3, indicating that subframes with subframe numbers less than or equal to n+3 can use CAT2; while subframes with subframe numbers greater than n+3 can only use CAT4.

[0099] Step 603: The second device performs uplink LBT according to the LBT mechanism determined in steps 601 and 602, and transmits uplink data after the LBT is successful.

[0100] Depending on whether the uplink LBT mechanism is indicated in step 601, the method of the present invention is described below in two cases.

[0101] The first method for determining the LBT mechanism for data transmission by the second device is as follows: in step 601, the first device may send first scheduling signaling to indicate the LBT mechanism to be adopted by the second device. Next, in step 602, the first device may adjust the LBT mechanism for data transmission by the second device by sending second scheduling signaling. Here, if the second scheduling signaling indicates a change from the first LBT mechanism to the second LBT mechanism, the second scheduling signaling may further indicate parameters for the second LBT mechanism, which may include the size of the CAT4 contention window (CW) and / or a random number N generated by the first device based on the CW. The random number N is the number of idle CCA slots that need to be detected when implementing CAT4.

[0102] After receiving the first scheduling signaling, the second device still needs to check for the second scheduling signaling. Upon receiving the second scheduling signaling, the second device contends for the channel based on the LBT mechanism indicated in the second scheduling signaling. If the second scheduling signaling is not received, the second device may contend for the channel based on the LBT mechanism indicated in the first scheduling signaling. This method is applicable when the first device determines that a change in the LBT mechanism is not necessary and does not send the second scheduling signaling. However, if the first device actually sends the second scheduling signaling to change the LBT mechanism but the second device fails to correctly receive it, the second device may adopt a different LBT mechanism. Alternatively, if the second scheduling signaling is not received, the second device may persist in using a specific LBT mechanism to contend for the channel. For example, to ensure friendly coexistence, the second device may adopt a relatively conservative second LBT mechanism. This method works correctly when the first device actually sends the second scheduling signaling and indicates the second LBT mechanism. However, when the first device actually sends the second scheduling signaling and indicates the first LBT mechanism, this method reduces the second device's ability to contend for the channel, but enables more friendly coexistence with other devices. Alternatively, when the second scheduling signaling is not received, assuming that the UE can obtain the start timing of the data transmission of the first device through other methods, such as indication information of other control signaling, then when the total time length from the first device completing LBT and occupying the channel to the subframe position where the scheduled data transmission of the second device is located is less than or equal to MCOT, the second device performs the first LBT; otherwise, the second device performs the second LBT. Alternatively, when the second scheduling signaling is not received, assuming that the UE can obtain the start timing of the data transmission of the first device through other methods, such as indication information of other control signaling, then when the total time length from the first device completing LBT and occupying the channel to the subframe position where the scheduled data transmission of the second device is located is less than or equal to MCOT, and the data transmission of the first device and the scheduled data transmission of the second device occupy consecutive subframes, the second device performs the first LBT; otherwise, the second device performs the second LBT.

[0103] For this method, when the first device sends the first scheduling signaling, it can set a relatively conservative second LBT for data transmissions from the second device, for which it is uncertain whether the data transmission falls within the MCOT. For example, the first LBT is set only when the total time from the first device completing the LBT to the scheduled subframe location of the second device's data transmission is less than or equal to the MCOT. Alternatively, the first LBT is set only when the total time from the first device completing the LBT to the scheduled subframe location of the second device's data transmission is less than or equal to the MCOT, and the first device can be certain that its data transmission and the scheduled data transmission of the second device occupy consecutive subframes. Alternatively, the first scheduling signaling sets all scheduled uplink transmissions to use the second LBT. In this way, the second scheduling signaling is only sent in certain situations, namely when a subframe with the second LBT set actually falls within the MCOT, to adjust the LBT to the more aggressive first LBT. With this method, because the second scheduling signaling only changes the LBT from the second LBT to the first LBT, there is no need to specify the specific parameters of the second LBT in the second scheduling signaling. In this way, when the second device does not receive the second scheduling signaling, no matter which of the above methods is adopted, that is, following the first scheduling signaling or fixedly adopting the second LBT, the effect is that the second device competes for the channel according to the second LBT, thereby achieving more friendly coexistence with other devices.

[0104] A second method for determining the LBT mechanism for data transmission by the second device involves, in step 601, the first device sending first scheduling signaling without indicating the LBT mechanism to be adopted by the second device. Next, in step 602, the first device may set the LBT mechanism for data transmission by the second device by sending second scheduling signaling. If the second scheduling signaling requires a second LBT, the second scheduling signaling may further indicate parameters for the second LBT, which may include the size of the CAT4 contention window (CW) and / or a random number N generated by the first device based on the CW. The random number N is the number of idle CCA slots that need to be detected when implementing CAT4.

[0105] After receiving the first scheduling signaling, the second device still needs to detect the second scheduling signaling. When the second scheduling signaling is received, the second device competes for the channel according to the LBT information indicated by the second scheduling signaling. When the second scheduling signaling is not received, the second device may fixedly adopt a certain LBT mechanism to compete for the channel. For example, in order to coexist in a friendly manner, the second device may adopt a relatively conservative second LBT to compete for the channel. In some cases, when the first device needs to configure the second device to work according to the second LBT, the second scheduling signaling may not be sent, thereby reducing the signaling overhead. When the first device actually sends the second scheduling signaling and indicates the second LBT, this method works accurately; when the first device actually sends the second scheduling signaling and indicates the first LBT, this method reduces the second device's own ability to compete for the channel, but achieves a more friendly coexistence with other devices. Alternatively, when the second scheduling signaling is not received, assuming the UE can obtain the start timing of the first device's data transmission through other methods, such as indication information from other control signaling, then if the total time from the first device completing LBT and occupying the channel to the subframe location of the scheduled second device's data transmission is less than or equal to the MCOT, the second device performs the first LBT; otherwise, the second device performs the second LBT. Alternatively, when the second scheduling signaling is not received, assuming the UE can obtain the start timing of the first device's data transmission through other methods, such as indication information from other control signaling, then if the total time from the first device completing LBT and occupying the channel to the subframe location of the scheduled second device's data transmission is less than or equal to the MCOT, and the first device's data transmission and the scheduled second device's data transmission occupy consecutive subframes, the second device performs the first LBT; otherwise, the second device performs the second LBT. In some cases, if the behavior of the second device upon not receiving the second scheduling signaling is the LBT mechanism desired by the first device, the first device may not send the second scheduling signaling, thereby reducing signaling overhead.

[0106] For the above two LBT mechanisms for determining the data transmission of the second device, because the LBT type applicable to the data transmission of the second device may change over time, if the first device frequently changes its scheduled uplink and downlink transmission distribution, the first device may need to send a new second scheduling signaling to change the LBT type indicated by the previous second scheduling signaling. From the perspective of the second device, when the second device receives multiple second scheduling signalings, the second device may operate according to the LBT type indicated by the most recent second scheduling signaling. Alternatively, the first device is allowed to send the second scheduling signaling multiple times, but the LBT type indicated by the multiple second scheduling signalings is restricted to be consistent. If there is a conflict in the LBT types indicated by multiple second scheduling signalings, the second device deems that the second scheduling signaling has failed to be received, that is, it is processed as if the second scheduling signaling has not been received.

[0107] Example 2

[0108] In an unlicensed frequency band, when a device operates on two or more adjacent carriers, because the frequency intervals between these carriers are relatively close, the transmission operation on one carrier will affect the reception operation of the same device on the adjacent carrier. In particular, the power leaked from the transmission operation on one carrier to the adjacent carrier will affect the CCA operation on this adjacent carrier. That is, even if the adjacent carrier is currently idle, due to the leaked power, the device will mistakenly believe that the adjacent carrier is busy and thus cannot occupy this carrier. In the existing LAA downlink operation, the solution to this situation is to start transmission operations on these adjacent carriers as simultaneously as possible. For example, CAT4 LBT can be performed on each carrier separately, but after the base station successfully completes the LBT of one carrier, it can perform a self-delay process and wait until more carriers have completed LBT before starting to transmit data together. Here, the self-delay process provides the base station with the opportunity to transmit data on multiple carriers at the same time. However, during the self-delay process of a carrier, this carrier may be preempted by other devices, causing the base station to lose the opportunity to use this carrier. Therefore, the base station can only make a compromise between these two factors. In the above method, when the base station starts to transmit data on a part of adjacent carriers, if there are still other adjacent carriers whose LBT is not completed, the base station can only suspend the LBT process of these adjacent carriers, that is, these adjacent carriers are currently unavailable.

[0109] A similar issue exists with UE uplink operations in LAA systems: the UE cannot simultaneously transmit and receive on closely spaced carriers. In practice, UEs are generally less complex than base stations for cost reasons, so the aforementioned inability to transmit and receive simultaneously on adjacent carriers is more pronounced on the UE side. Because the UE's ability to handle simultaneous transmission and reception on adjacent carriers is weaker than that of the base station, the base station can transmit and receive on both carriers without interfering with each other, but the UE's transmission and reception operations on these two carriers are actually limited.

[0110] For example, the base station schedules the downlink transmission of the UE on one carrier, but schedules the uplink transmission of the UE on another adjacent carrier at the same time, which causes the uplink transmission of the UE on these two adjacent carriers to interfere with its downlink reception. For example, if the UE is transmitting uplink data on one carrier, and the base station schedules uplink data transmission on an adjacent carrier, the UE's CCA on this adjacent carrier will be affected by the carrier that has already transmitted uplink data, resulting in the UE being unable to complete the LBT on this adjacent carrier and thus unable to start uplink transmission, resulting in a waste of uplink resources. For example, even if the base station schedules two adjacent carriers to start transmission in the same subframe, because the LBT of the two carriers is performed independently, if the time when the two carriers complete the LBT is inconsistent, the carrier that completes the LBT first will also block the CCA operation of the other carrier. The above-mentioned inconsistent time for completing the LBT may be due to the fact that the two adjacent carriers belong to different time advance groups (TAGs); or because a signal occupying the channel is sent on one carrier, resulting in blocking the operation of the other carrier.

[0111] In order to avoid the above problems, Figure 8 Shown is a flow chart of scheduling and performing uplink transmission on multiple carriers according to the present invention.

[0112] Step 801: The UE may report its ability to simultaneously transmit and receive on adjacent carriers to the base station, so that the base station can more reasonably allocate uplink and downlink resources to the UE based on this capability information. Here, the UE may report only one simultaneous transmission and reception capability, and apply it to various combinations of transmission and reception channels / signals. Alternatively, when the UE performs different types of reception operations, such as receiving downlink data and CCA operations, its ability to resist interference from uplink transmission leakage from adjacent carriers may be different, so the UE may report the simultaneous transmission and reception capability separately for different combinations of transmission and reception channels / signals. For example, the capability of downlink data reception considering that uplink transmission interferes with another carrier, and the capability of uplink CCA considering that uplink transmission interferes with another carrier.

[0113] The following describes a method for a UE to report its capability of simultaneously transmitting and receiving on multiple carriers.

[0114] The first method involves the UE being unable to simultaneously transmit and receive on carriers within the same frequency band. When the UE supports Carrier Access Control (CA) on multiple frequency bands, it reports supported band combinations that do not limit simultaneous transmission and reception. This means that within such a band combination, uplink signals can be transmitted on a carrier in one frequency band and received on a carrier in another frequency band. A combination can include one or more frequency bands, which are generally non-overlapping and widely spaced, allowing simultaneous transmission and reception. Alternatively, when the UE supports Carrier Access Control (CA) on multiple frequency bands, it reports a band combination with limitations on simultaneous transmission and reception. This means that when configured with such a band combination, the UE must avoid transmitting uplink signals on a carrier in one frequency band while receiving on a carrier in another frequency band. A combination can include one or more frequency bands, which may overlap or have closely spaced frequencies, preventing the UE from simultaneously transmitting and receiving on carriers within such frequency bands.

[0115] The second method is that the UE reports a frequency separation threshold T F , then all frequency intervals are less than or equal to T F The UE cannot transmit or receive on two carriers at the same time, regardless of whether they belong to the same frequency band or different frequency bands.

[0116] The third method is that the UE cannot perform transmission and reception operations simultaneously on each carrier in the same frequency band. When the UE supports CA on multiple frequency bands (inter-band CA), the UE reports a frequency separation threshold T F , then all belong to different frequency bands and the frequency interval is less than or equal to T F The UE cannot transmit or receive on these two carriers simultaneously.

[0117] When the UE reports the simultaneous transmission and reception capabilities for different transceiver channel / signal combinations separately, the UE may report the multi-carrier simultaneous transmission and reception capabilities for each transceiver channel / signal combination separately according to the three methods described above. For example, the multi-carrier simultaneous transmission and reception capabilities considering uplink transmission interfering with downlink data reception on another carrier, and the multi-carrier simultaneous transmission and reception capabilities considering uplink transmission interfering with uplink CCA on another carrier.

[0118] Step 802: The UE receives signaling from the base station for scheduling uplink transmission of one or more carriers.

[0119] Step 803: The UE performs uplink LBT according to the base station scheduling, and transmits uplink data on one or more carriers on which LBT is successfully performed.

[0120] Based on the capabilities reported by the UE, if the UE is performing uplink transmission on one carrier, the base station can avoid scheduling downlink data transmission for this UE on an adjacent carrier, thereby avoiding resource waste. On the UE side, assuming the UE is performing uplink transmission on one carrier, in the case of cross-carrier scheduling, if the UE simultaneously detects that the base station has scheduled its downlink data transmission on an adjacent carrier, the UE can skip data reception and directly feedback HARQ-ACK information (NACK) to the base station; alternatively, the UE can receive downlink data without performing uplink transmission.

[0121] If a UE is triggered to transmit SRS within a subframe, the following describes how the UE handles uplink and downlink transmissions within that subframe. First, the UE may assume that this subframe is an uplink subframe and, therefore, not detect PDCCH / EPDCCH on the aforementioned multiple adjacent carriers, thus failing to receive downlink transmissions from the base station. Alternatively, the UE may assume that this subframe may be a partial downlink subframe, similar to DwPTS, and, therefore, continue to detect common PDCCH and PDCCH / EPDCCH on multiple adjacent carriers. If the UE detects a common PDCCH on one or more adjacent carriers, and the common PDCCH indicates a complete downlink subframe, or the common PDCCH indicates a partial downlink subframe but there is insufficient guard time (GP) between the OFDM symbols of the partial downlink subframe and the SRS symbols, and the UE further detects a downlink transmission scheduled for it by the base station on such an adjacent carrier, then the UE may abandon the SRS transmission and instead receive downlink data on the adjacent carrier that schedules the downlink transmission of this UE; or, the UE may also abandon the above-mentioned complete downlink subframe and downlink transmission on the carrier without sufficient GP, but may receive downlink transmission on the carrier with sufficient GP between the downlink OFDM symbols of the downlink partial subframe indicated by the common PDCCH and the SRS symbols, and send a triggered SRS; or, the UE may also receive downlink transmission on only the first part of the OFDM symbols of the subframe on the above-mentioned complete downlink subframe and the carrier without sufficient GP, and receive downlink transmission on the carrier with sufficient GP between the downlink OFDM symbols of the downlink partial subframe indicated by the common PDCCH and the SRS symbols, and send a triggered SRS. If the UE detects a common PDCCH on one or more adjacent carriers, and the UE detects downlink transmissions scheduled for it by the base station only on adjacent carriers of the downlink partial subframe indicated by the common PDCCH, and there is enough GP between the downlink OFDM symbol and the SRS symbol of the downlink partial subframe indicated by the common PDCCH, the UE can first receive downlink data on the above-mentioned multiple adjacent carriers, and then send a triggered SRS. If the UE detects a common PDCCH on one or more adjacent carriers, and the base station does not schedule downlink transmissions for it, the UE can send a triggered SRS. Alternatively, on the carrier where the SRS is triggered, the UE only sends a triggered SRS when there is a guard time (GP) between the downlink OFDM symbol and the SRS symbol of the downlink partial subframe indicated by the common PDCCH.

[0122] For the LBT operation of the UE in the unlicensed frequency band, in the case of adopting CAT4, the relevant status and parameters of CAT4 can be maintained on the base station side, or can also be maintained on the UE side. For the method of maintaining CAT4 related parameters for the base station, the base station needs to notify the UE of the CAT4 parameters to be adopted through physical layer signaling; and the method of maintaining CAT4 related parameters for the UE may be a method that does not require the base station to indicate the CAT4 parameters. For example, the relevant parameters of CAT4 may include the size of the contention window CW of CAT4 and / or the random number N generated by the first device based on CW, etc. The random number N is the number of idle CCA time slots that need to be detected when executing CAT4. For the case where the uplink transmission interferes with the CCA operation of the adjacent carrier, the method of the present invention is described below in different cases.

[0123] The UE's carriers may be grouped, and LBT may be performed on each group of carriers separately. The following describes a method of determining the LBT mechanism and corresponding parameters for a group of carriers according to the present invention. The group of carriers may be all uplink carriers configured for the UE; or the group of carriers may be carriers belonging to the same TAG configured for the UE; or the group of carriers may be carriers belonging to the same frequency band configured for the UE; or, assuming that the UE is configured with carriers of multiple frequency bands and the UE does not support simultaneous transmission and reception on these frequency bands, the group of carriers may include all carriers configured for the UE on the multiple frequency bands; or the group of carriers may be a portion of all uplink carriers configured for the UE. The carrier grouping method may not require additional signaling, such as the first four grouping methods mentioned above; or the grouping method may require additional signaling, such as the fifth grouping method mentioned above. Here, the LBT operation may be performed on the group of carriers configured above, or only on the activated carriers in the group of carriers configured above. The group of carriers may occupy adjacent frequencies, so that the UE's transmission and reception operations on this group of carriers affect each other.

[0124] The first method for processing LBT for a group of carriers is to maintain the relevant CAT4 parameters for each carrier in the group, including the CW size, etc. The base station can separately determine and indicate the LBT mechanism for each carrier scheduled for uplink transmission. If it is CAT4, it can further determine and indicate the relevant CAT4 parameters. Here, each carrier can indicate its own CW parameters, or the maximum CW value of each carrier in the group can be obtained and indicated for each carrier. Alternatively, the UE can maintain the CAT4 parameters. For example, the uplink LBT mechanism can be determined according to whether the uplink data transmission is within the MCOT of the base station according to the method in Example 1.

[0125] A second method for handling LBT for a group of carriers is to implement CAT4 on only one carrier in the group, while implementing CAT2 on the other carriers. For the carrier implementing CAT4, the base station can dynamically indicate the relevant CAT4 parameters for this carrier. Alternatively, the UE can maintain the CAT4 parameters. The CAT4 parameters can be determined based on parameters such as the CW of all carriers in the group, for example, by using the maximum CW value of each carrier, or by maintaining only a single CW value for each carrier. Alternatively, the CAT4 parameters can be determined based on parameters such as the CW of the carrier currently scheduled for uplink transmission in the group, for example, by using the maximum CW value of each carrier, or by maintaining only a single CW value for each carrier. When each carrier maintains a separate CW, the CW parameters of the carrier configured to implement CAT4 can be fixed to determine the currently used CAT4 parameters, or their CW parameters can be used to determine the currently used CAT4 parameters only when uplink transmission is scheduled. Alternatively, for a carrier in the group of carriers, if an uplink transmission is currently scheduled on the carrier and the scheduled uplink transmission is outside the MCOT of the base station for the carrier, then the CW and other parameters of the carrier may be used to determine the aforementioned CAT4-related parameters. For a carrier configured to implement CAT4, its CW parameters may be fixed for determining the currently used CAT4 parameters, or may be used only when an uplink transmission is scheduled and the scheduled uplink transmission is outside the MCOT of the base station for the carrier.

[0126] The carriers configured to implement CAT4 can be configured to the UE via higher-layer signaling. The base station may only need to dynamically indicate the CAT4-related parameters for this carrier, or the UE may maintain the CAT4 parameters, while other carriers default to CAT2. Alternatively, the base station may separately indicate the LBT mechanism for each carrier in the group of carriers, further indicating the CAT4-related parameters for the CAT4 carriers, or the UE may maintain the CAT4 parameters. When scheduling uplink transmissions for the group of carriers, the base station may schedule uplink transmissions on at least the carrier configured to implement CAT4, causing the UE to implement CAT4 on this carrier and implement CAT2 on other scheduled carriers. Alternatively, when scheduling uplink transmissions for the group of carriers, the base station may not schedule uplink transmissions on the carrier semi-statically configured to implement CAT4 within a subframe, but the base station may still need to dynamically indicate the CAT4-related parameters for this carrier. Alternatively, the UE may maintain the CAT4 parameters, causing the UE to continue implementing CAT4 on the configured carrier and implement CAT2 on other scheduled carriers.

[0127] For the carrier configured to execute CAT4 as described above, the higher-level signaling can be configured to execute only CAT4 on this carrier for each scheduled uplink transmission. Alternatively, the base station can dynamically instruct the carrier configured to execute CAT4 to execute CAT2 in a subframe. For example, assuming that, according to the method of embodiment 1, uplink transmissions on all carriers scheduled by the base station are within the MCOT in the current subframe, the base station can dynamically instruct the UE to execute CAT2 on the carrier configured to execute CAT4, and also execute CAT2 on other carriers scheduled for UE uplink transmission. When uplink transmissions on at least one carrier are outside its MCOT, the base station can dynamically instruct the UE to execute CAT4 on the carrier configured to execute CAT4. For the carrier configured to execute CAT4 as described above, the higher-level signaling can be configured to execute only CAT4 on this carrier for each scheduled uplink transmission, and execute CAT2 on other carriers. Alternatively, the UE can be allowed to execute CAT2 in the subframes of the carrier configured to execute CAT4, and also execute CAT2 on other carriers, in subframes that meet certain conditions. When the base station indicates CAT2 for uplink transmissions scheduled on all carriers in the group, the UE may implement CAT2 on the carrier configured for CAT4. Otherwise, the UE implements CAT4 on the carrier configured for CAT4. Specifically, if within a subframe, the base station indicates CAT2 on the carrier configured for CAT4, but at least one other carrier in the group indicates CAT4, the UE implements CAT4 on the carrier configured for CAT4.

[0128] The carrier configured to implement CAT4 can also be selected by the base station, but does not need to be configured to the UE via higher-layer signaling. The base station's selection of a carrier to implement CAT4 can be semi-static. Alternatively, if the UE is responsible for maintaining CAT4 status and parameters, the carrier configured to implement CAT4 can also be selected by the UE, and the selection of the carrier to implement CAT4 can be semi-static. Regarding the method for maintaining CAT4 status and parameters for the base station, if the base station is allowed to select different carriers as CAT4 carriers for different UEs, the information indicating to the UE which carrier to implement CAT4 can be sent separately to each UE. The LBT type for each subframe scheduled for uplink transmission by the base station can be common to the cell, common to a group of UEs, or sent separately to each UE. When scheduling uplink transmission for the group of carriers, the base station can schedule uplink transmission on at least the CAT4 carrier selected by the base station and dynamically indicate CAT4 and corresponding parameters in the corresponding scheduling signaling, thereby instructing the UE to implement CAT4 on the CAT4 carrier selected by the base station and to implement CAT2 on other scheduled carriers. Alternatively, the base station may separately indicate the LBT mechanism of each carrier in the group of carriers, and for a CAT4 carrier, may further indicate relevant parameters of CAT4.

[0129] On the carrier selected for CAT4, only CAT4 can be configured for each scheduled uplink transmission. Alternatively, the base station can dynamically instruct the carrier selected for CAT4 to execute CAT2 in a subframe. For example, assuming that, according to the method of embodiment 1, uplink transmissions on all carriers scheduled by the base station are within the MCOT in the current subframe, the base station can dynamically instruct the UE to execute CAT2 on the carrier selected for CAT4 and also execute CAT2 on other carriers scheduled for UE uplink transmission. When uplink transmissions on at least one carrier are outside its MCOT, the base station can dynamically instruct the UE to execute CAT4 on the carrier selected for CAT4. On the carrier selected for CAT4, only CAT4 can be configured for each scheduled uplink transmission, and CAT2 can be executed on other carriers. Alternatively, the UE can be allowed to execute CAT2 in the subframes of the carrier selected for CAT4 and also execute CAT2 on other carriers in subframes that meet certain conditions. When the base station indicates CAT2 for uplink transmissions scheduled on all carriers in the group, the UE may implement CAT2 on the carrier selected for CAT4. Otherwise, the UE implements CAT4 on the carrier selected for CAT4. Specifically, if within a subframe, the base station indicates CAT2 on the selected CAT4 carrier, but CAT4 is indicated on at least one other carrier in the group, the UE implements CAT4 on the carrier selected for CAT4.

[0130] Alternatively, the base station can dynamically select a carrier to implement CAT4. This dynamic selection can be base station-specific, or the base station can be required to randomly select CAT4 carriers based on a uniform distribution. For example, the selection of a CAT4 carrier can be performed each time uplink data is scheduled for a subframe; alternatively, the base station can be required to perform this operation before each downlink transmission ends and before starting uplink transmission. Specifically, the base station can select a carrier to configure for CAT4 based on the uplink carrier currently scheduling the UE. The base station also needs to dynamically indicate the LBT mechanism for this carrier and its CAT4-related parameters, and configure other carriers to implement CAT2. Alternatively, the base station can separately indicate the LBT mechanism for each carrier in the group, further indicating CAT4-related parameters for CAT4 carriers. Furthermore, within a subframe, the base station can dynamically indicate that all carriers scheduling UE uplink transmissions implement CAT2. For example, assuming that, according to the method of Example 1, uplink transmissions for all carriers scheduled by the base station in the current subframe are within the MCOT, the base station can dynamically instruct the UE to implement CAT2 on the carrier selected for CAT4, and also on other carriers scheduling UE uplink transmissions. Accordingly, on the carrier indicated by the base station for execution of CAT4, the UE may only execute CAT4 on this carrier each time uplink transmission is scheduled, and execute CAT2 on other carriers. Alternatively, the UE may be allowed to execute CAT2 on the subframes of the carrier selected for execution of CAT4 and also execute CAT2 on other carriers in subframes that meet certain conditions. When the uplink transmissions scheduled by the base station on all carriers in this group of carriers indicate CAT2, the UE may execute CAT2 on the carrier selected for execution of CAT4; otherwise, the UE executes CAT4 on the carrier selected for execution of CAT4. In particular, within a subframe, if the base station indicates CAT2 on the selected CAT4 carrier, but CAT4 is indicated on at least one other carrier in this group of carriers, the UE executes CAT4 on the carrier selected for execution of CAT4.

[0131] Alternatively, the UE may be allowed to dynamically select a carrier for executing CAT4. The above dynamic selection may be UE implementation-dependent, or the UE may be required to randomly select a CAT4 carrier according to a uniform distribution. For example, the operation of selecting a CAT4 carrier may be performed each time uplink data of a subframe is scheduled; or, it may be performed each time the base station starts scheduling uplink transmission. Specifically, the UE may select a carrier to configure and execute CAT4 based on the currently scheduled uplink carrier. The UE is responsible for maintaining and generating relevant parameters for CAT4, and executes CAT2 on other carriers. Alternatively, on subframes that meet certain conditions, the UE is allowed to execute CAT2 on the subframes of the carrier selected for executing CAT4, and also execute CAT2 on other carriers. When the uplink transmissions scheduled by the base station on all carriers in this group of carriers indicate CAT2, the UE may execute CAT2 on the carrier selected for executing CAT4; otherwise, the UE executes CAT4 on the carrier selected for executing CAT4. Specifically, within a subframe, the base station indicates CAT2 on the selected CAT4 carrier, but at least one other carrier in the group of carriers indicates CAT4, then the UE performs CAT4 on the carrier selected to perform CAT4.

[0132] Assume that the UE's carriers are configured to be divided into multiple groups, and LBT is performed on each group of carriers according to the above method. The base station can configure the UE with grouping information for the group of carriers for which LBT is performed, such as which component carriers are included in the group, through higher-layer signaling. For example, for the second method for handling LBT on a group of carriers, if higher-layer signaling further configures carriers within the group to implement CAT4, the base station only needs to dynamically indicate the CAT4-related parameters for the carriers configured to implement CAT4, or the UE is responsible for maintaining the CAT4-related parameters. If higher-layer signaling is not used to configure carriers within the group to implement CAT4, the base station needs to dynamically indicate the carriers configured to implement CAT4 and can further indicate the CAT4-related parameters for the CAT4 carriers, or the UE is responsible for maintaining the CAT4-related parameters. Thus, the UE explicitly implements CAT4 and its CAT4 parameters on one carrier and only needs to implement CAT2 on other carriers. For example, for the first method for handling LBT on a group of carriers, it is assumed that the base station specifies the LBT mechanism for each carrier separately, but the UE is responsible for maintaining the CAT4-related parameters and performs LBT based on the maximum CW value of each carrier within the group. Alternatively, the base station may configure the UE with the grouping information of the group of carriers on which LBT is to be performed without using higher-layer signaling. That is, the UE may default to operating on these carriers according to the LBT mechanism and / or parameters indicated by the base station. For example, for the first method of processing LBT for a group of carriers described above, the base station needs to use other signaling, such as dynamic control information at the physical layer, to indicate the LBT mechanism for each carrier scheduled for uplink transmission, and may further indicate CAT4-related parameters for each CAT4 carrier. Alternatively, the UE is responsible for maintaining the CAT4-related parameters and using the CW parameters of each carrier separately for each carrier.

[0133] Specifically, the base station may group the carriers configured for the UE, and each group of carriers may employ a different LBT processing method. For a group of carriers, for the first method for processing LBT for a group of carriers described above, the base station may indicate the LBT mechanism for each carrier separately, and may further indicate CAT4-related parameters for each CAT4 carrier separately. Alternatively, the UE is responsible for maintaining CAT4-related parameters and using the CW parameters of each carrier separately for each carrier. In this case, the base station may not indicate the grouping information for this group of carriers to the UE, i.e., the UE may default to operating on these carriers according to the LBT mechanism and / or parameters indicated by the base station. Otherwise, for a group of carriers, for the first method for processing LBT for a group of carriers described above, assuming that the base station indicates the LBT mechanism for each carrier separately, but the UE is responsible for maintaining CAT4-related parameters and processing LBT based on the maximum CW value of each carrier in the group; or for the second method for processing LBT for a group of carriers described above; or; then the base station may indicate the grouping information for this group of carriers to the UE.

[0134] Assume that the base station schedules uplink transmission on multiple carriers of the same TAG, and the LBT types on the multiple carriers can be different, or the parameters of CAT4 can be different. Assume that the specific method of uplink CAT4 is that after completing the LBT of CAT4, the UE performs a self-delay process, and when the UE detects that the channel is idle for T0 us before the start timing of the scheduled uplink transmission, for example, T0 is equal to 25us, the UE can perform uplink transmission. Then, if Figure 9 As shown, on multiple carriers scheduled for uplink transmission in the same TAG, the UE can work according to the LBT mechanism indicated by the base station respectively, so that uplink transmission can be performed on one or more carriers that successfully complete the corresponding LBT operation. Alternatively, on multiple carriers scheduled for uplink transmission in the same TAG, the UE can compete for the channel according to CAT4 on a carrier configured to execute CAT4, or on a carrier instructed by the base station to execute CAT4, or on a carrier selected by the UE to execute CAT4, and execute CAT2 on other scheduled carriers, so that uplink transmission can be performed on one or more carriers that successfully complete the corresponding LBT operation. Here, the combination of the two factors of the same TAG and the fact that no signal for occupying the channel is sent after the successful completion of CAT4 ensures that the UE starts uplink transmission on multiple carriers within the TAG at the same time.

[0135] Alternatively, assuming that the specific method for uplink CAT4 is that after completing LBT for CAT4, the UE can transmit a signal occupying the channel until before the start timing of the scheduled uplink transmission, and then transmit the scheduled uplink signal. Then, when the UE completes CAT4 on one of the adjacent carriers, if it immediately starts transmitting a signal occupying the channel, it will inevitably affect the UE's LBT operation on other adjacent carriers. In this case, the UE can perform a self-delay process after completing CAT4 on one carrier, and wait until more carriers complete LBT before starting to transmit the signal occupying the channel and the scheduled uplink signal together. Assuming that the base station schedules the UE's uplink transmission on N carriers, the UE can be restricted to attempt to complete LBT on as many carriers as possible. That is, before the scheduled uplink transmission start time arrives, as long as the LBT of one scheduled carrier has not been successful, but there is still a possibility of success, the UE will perform self-delay on all other carriers that have completed the LBT operation. After LBT is completed on all carriers, the UE transmits occupied channel signals and scheduled uplink signals on each scheduled carrier. Alternatively, if LBT on a carrier where LBT is currently incomplete is no longer possible, the UE may transmit occupied channel signals and scheduled uplink signals on all carriers where LBT has already completed. Alternatively, the UE may be allowed to begin transmitting occupied channel signals and scheduled uplink signals after completing LBT on a certain percentage of carriers. This percentage may be predefined, configured using higher-layer signaling, or the determination of this percentage may be entirely left to the UE implementation. Here, through UE implementation, CCA detection may begin on other carriers that have completed CAT4 ahead of time, T0 us before CAT4 is completed on the last carrier that has completed CAT4. Therefore, when CAT4 is completed on the last carrier that has completed CAT4, CCA on all other carriers that have completed CAT4 ahead of time is also completed T0 us, allowing the UE to simultaneously begin uplink transmission on all carriers that have completed CAT4.

[0136] Assuming that the base station needs to configure the UE's uplink carriers to belong to multiple TAGs, when configuring the UE's carriers using higher-layer signaling, the base station may make the frequency spacing of carriers in different TAGs sufficiently far apart, thereby avoiding the problem of the UE not transmitting and receiving simultaneously on carriers in different TAGs. Alternatively, when configuring the UE's carriers using higher-layer signaling, the base station may configure different TAGs to include carriers with relatively close frequency spacing, but the base station will not simultaneously activate carriers belonging to different TAGs whose frequency spacing is not far enough apart, thereby avoiding the problem of the UE not transmitting and receiving simultaneously on carriers in different TAGs. However, in some cases, due to the limitation of available uplink carriers, the base station cannot fully ensure that the spacing between configured and activated carriers in different TAGs is sufficiently far apart, which affects the base station's uplink and downlink scheduling and the UE's uplink and downlink transmission. Based on the UE's reported capability of simultaneous multi-carrier transmission and reception, the base station may avoid scheduling the UE's uplink and downlink transmission simultaneously on carriers that are not far enough apart from each other. In some cases, if the base station schedules uplink and downlink transmission on two carriers in different TAGs that are not far enough apart from each other, and the transmission and reception of these two carriers interfere with each other, two processing methods are described below.

[0137] The first approach is to Figure 10 As shown, for carriers of TAGs with later timing, the UE can send signal A occupying the channel until the start timing of the uplink transmission scheduled for this carrier, and align the start timing of signal A with the start timing of the uplink transmission scheduled for carriers of TAGs with earlier timing. For carriers of TAGs with later timing, the time period in which they can perform LBT operations is reduced because of the additional signal A occupying the channel. Specifically, if the base station instructs it to use CAT2 uplink LBT, the CCA detection of CAT2 is actually completed in a time period of length T1 before the start timing of signal A occupying the channel, for example, T1 is equal to 25us. If the base station instructs it to use CAT4 uplink LBT, and the UE performs the self-delay process after completing CAT4 LBT, then when the UE detects that the channel is idle for T0 us before the start timing of signal A occupying the channel, for example, T0 is equal to 25us, the UE performs uplink transmission on this carrier. By using this method, the channel-occupying signal A may be added to the uplink transmission of only the carriers whose reception operation is affected in the TAG with later timing, or the channel-occupying signal A may be added to the uplink transmission of all carriers in the TAG with later timing.

[0138] The second approach is to Figure 11As shown, for the carrier of the TAG with earlier timing, the first part of its scheduled uplink transmission is cut off, so as to be aligned with the start timing of the carrier of the TAG with later timing. Here, because a part of the uplink transmission scheduled by the carrier of the TAG with earlier timing is cut off, this cut off time can be used for CCA detection, so the time period in which it can perform LBT operation is increased. Specifically, if the base station instructs it to adopt CAT2 uplink LBT, then the CAT2 CCA detection is actually completed in a time period of length T1 before the start timing of the uplink transmission scheduled by the TAG with later timing, for example, T1 is equal to 25us. If the base station instructs it to adopt CAT4 uplink LBT, and the UE performs the self-delay process after completing the CAT4 LBT, then when the UE detects that the channel is idle for T0 us before the start timing of the uplink transmission scheduled by the TAG with later timing, for example, T0 is equal to 25us, the UE performs uplink transmission on this carrier. By using this method, only a portion of the uplink transmission signal of the carrier affecting the receiving operation in the TAG with earlier timing can be discarded, or a portion of the uplink transmission signal of all carriers of the TAG with earlier timing can be discarded.

[0139] Example 3

[0140] On a carrier in the unlicensed band, depending on the base station's scheduling, the UE can perform either CAT2 or CAT4 LBT to contend for the channel and begin uplink transmission after successfully completing LBT. For CAT2, the UE only needs to detect channel idleness for T1 us before the uplink transmission start time (for example, T1 equals 25 us) to occupy the channel. For CAT4, a random number N is generated based on the current CW size. After detecting channel idleness for T2 us (for example, T2 equals 25 us), the UE continues to monitor the channel. It can only occupy the channel when the number of currently idle CCA timeslots reaches N. After successfully completing CAT4, the UE has two options. The first option is to immediately send a fill signal to occupy the channel until the scheduled uplink transmission start time, and then begin transmitting the scheduled uplink signal. The second option is to perform a self-delay process. If the UE detects channel idleness for T0 us before the scheduled uplink transmission start time (for example, T0 equals 25 us), the UE can transmit the scheduled uplink signal.

[0141] The second method of processing CAT4 as above is as follows: Figure 12 As shown in a, the CAT4 completion time and the idle time of length T0 us can be non-overlapping; or Figure 12 As shown in Figure b, when the UE completes CAT4, the time from the start of the scheduled uplink transmission is less than T0 us, that is, the time period for executing CAT4 and the time period of T0 us overlap.

[0142] right Figure 12 a situation, such as Figure 13 As shown, the idle time of T0 us can be divided into the first 16 us and the subsequent k consecutive idle CCA time slots, for example, k is equal to 1, and the CCA time slot length is 9 us. Here, the front part of the first 16 us time period includes an idle CCA time slot.

[0143] right Figure 12 In case b, although the T0 us period overlaps with the CAT4 period, it can be Figure 13 The structure of the T0 us time period can still require that each CCA time slot in the T0 us time period is idle. Specifically, if Figure 14 As shown in a, the first CCA time slot of the T0 time period is within the CAT4 time period, so the first CCA time slot is idle; the 7us part of the T0 time period overlaps with the last CCA time slot of CAT4, because the 7us part does not require CCA detection, so there is no need to limit it; the last CCA time slot of the T0 time period must be idle before the UE can perform uplink transmission. Figure 14 As shown in Figure b, the first CCA time slot of the T0 time period overlaps with the last CCA time slot of the CAT4 time period. After completing CAT4, the UE needs to continue to detect the channel to ensure that the first CCA time slot is idle. There is no CCA detection requirement for the 7us part of the T0 time period. The last CCA time slot of the T0 time period must be idle before the UE can perform uplink transmission. Figure 14 As shown in c, the first CCA time slot of the T0 time period is within the CAT4 time period, and the first CCA time slot is idle; there is no CCA detection requirement for the 7us part of the T0 time period; the last CCA time slot of the T0 time period partially overlaps with the last CCA time slot of CAT4. After completing CAT4, the UE needs to continue to detect the channel to ensure that the last CCA time slot is idle, and then the UE can perform uplink transmission.

[0144] Alternatively, the interval T between the UE's CAT4 successful timing position and the scheduled UE's uplink transmission start timing and T0 is processed separately. When T is greater than or equal to T0, that is, Figure 12 In case of a, the UE can be Figure 13According to the method, when it is detected that the channel is idle in the time period of T0 us, that is, each CCA time slot in the time period of T0 is idle, the UE can start uplink transmission. When T is less than T0, it may be required that the UE can occupy the channel to send uplink signals only after detecting that the channel is idle at all times in the time period of T. For example, any time in the time period of T belongs to a certain CCA time slot, and this CCA time slot needs to be idle. The time period of T0 us is divided into two 9us CCA time slots from the start of the scheduling of the UE's uplink transmission, and the remaining 7us time also needs to be part of another CCA time slot to detect that the channel is idle. As Figure 15 As shown, it is assumed here that the penultimate CCA time slot partially overlaps with the CAT4 time period, so the UE needs to detect that the penultimate CCA time slot is idle, and detect that the channel is idle in the portion of the penultimate CCA time slot that does not overlap with the CAT4 time period. Alternatively, when T is less than T0, it may also be required that the time period during which the UE does not perform CCA detection within time period T does not exceed X us, for example, X is equal to 7, and the UE is required to detect that the channel is idle at all other times in time period T before occupying the channel to send uplink signals. For example, all other times in time period T belong to a certain CCA time slot, and this CCA time slot needs to be idle.

[0145] According to the existing LAA standard, the device needs to detect a time of at least Tcca within the 9us CCA time slot, for example, equal to 4us. Only when the energy detected is less than the CCA threshold can the CCA time slot be considered to be empty; otherwise, the CCA time slot is considered to be busy. When a CCA time slot in the T0 time period partially overlaps with a CCA time slot of CAT4, the total time length Tt after the two CCA time slots overlap is greater than Ts, for example, Ts is equal to 9us. At this time, the UE may be required to detect a longer time Tc within the time period Tt, that is, Tc is greater than Tcca. Only when the energy detected is less than the CCA threshold can the CCA time slot be considered to be empty; otherwise, the CCA time slot is considered to be busy. For example, Tc and Tt can be increased proportionally, for example, T c =T cca ·T t / T s Alternatively, when a CCA time slot in the T0 period partially overlaps with a CCA time slot in CAT4, it is required that the total time period after the two CCA time slots overlap is at least 2T. cca , for example, channel detection is performed within 8us. Or, when a CCA time slot in the T0 time period partially overlaps with a CCA time slot in CAT4, when the overlapping time length Tp is less than or equal to a threshold, here, T p +T t =2T s, the UE may consider a CCA time slot in the above T0 period to be idle; otherwise, the UE is required to perform additional CCA detection. For example, the CCA time may be increased proportionally according to the total time length Tt after the overlap, that is, the total CCA time requirement is T c =T cca ·T t / T s Alternatively, it is required that the total time period after the two CCA slots overlap is at least 2T cca =8us. Alternatively, when a CCA time slot in the T0 time period partially overlaps with a CCA time slot in CAT4, it may also be required to detect the channel within a time period of length Tcca in a CCA time slot in the T0 time period. Only when the detected energy is less than the CCA threshold can the CCA time slot be considered empty. Here, the time period of length Tcca is not restricted in its position within a CCA time slot in the T0 time period, nor is it restricted in whether it completely overlaps, partially overlaps, or does not overlap with the time period of length Tcca of the detection channel of a CCA time slot in the CAT4 time slot.

[0146] Example 4

[0147] On a carrier in an unlicensed band, depending on the base station's scheduling, a UE can perform either CAT2 or CAT4 LBT to contend for the channel and begin uplink transmission after successfully completing LBT. For CAT2, the UE only needs to detect idleness for T1 us before the uplink transmission start time (e.g., T1 equals 25 us) to occupy the channel. For CAT4, a random number N is generated based on the current CW size. After detecting idleness for T2 us (e.g., T2 equals 25 us), the UE continues to monitor the channel. It can only occupy the channel when the number of currently idle CCA timeslots reaches N. For CAT4 LBT, the CW size can be variable. For example, the CW is initially set to an initial value, such as the minimum CW value. When a data transmission error occurs, the CW size is increased, for example, exponentially. When certain conditions are met, such as successful data transmission, the CW can be restored to the minimum value.

[0148] The difference between CAT2 and CAT4 lies in the fact that CAT2's CCA detection period is fixed at T1, facilitating channel seizure. CAT4's CCA detection period is variable, consisting of a fixed period T2 plus k CCA slots, where k is a random number ranging from 0 to the current CW value. The CW varies between CWmin and CWmax, for example, CWmin = 3 and CWmax = 7. By defining the CW value to always be greater than or equal to 1, CAT4 requires a longer channel idle time than CAT2, resulting in weaker channel seizure capabilities but offering more friendly coexistence. To achieve the best of both CAT2 and CAT4, one approach is to configure the minimum CW value for CAT4, setting CWmin to 0, while maintaining CWmax as a positive integer. When CW is set equal to CWmin = 0, the random number N generated by the CAT4 mechanism is always 0, requiring the UE to begin transmitting uplink data only after detecting an idle period of T2, equivalent to the CAT2 mechanism. In this way, when the channel is idle, the UE can mainly work based on CAT2. When the channel load increases, decoding fails due to problems such as hidden terminals. By increasing the CW, the UE starts to work according to CAT4, thereby achieving coexistence.

[0149] In the existing downlink LAA standard, the base station decides whether to adjust the size of the CW based on the HARQ-ACK information of the data transmission of the first subframe in a downlink transmission time period. If the above-mentioned first subframe is not a complete subframe, the HARQ-ACK information of the second subframe in the above-mentioned downlink transmission time period is also used to decide whether to adjust the size of the CW. Specifically, on one or two subframes that can be used to adjust the CW, if the proportion of NACKs fed back by each UE is greater than or equal to Z = 80%, the size of the CW needs to be increased; otherwise, the CW size is set to CWmin. In addition, if for an LBT priority, the base station has transmitted the number of randomly backed-off CCA time slots based on the maximum CW value for K consecutive times, the CW size is reset to CWmin.

[0150] For uplink transmissions on a carrier in an unlicensed frequency band, the method of Embodiment 1 can be used to configure the UE's uplink LBT mechanism to CAT2, CAT4, or even "No LBT," depending on whether the uplink transmission is within the base station's MCOT. The following describes the method for determining a reference subframe for adjusting the uplink CAT4 CW.

[0151] The first method to determine the uplink reference subframe is to limit the uplink reference subframe to the uplink subframe configured for the UE based on the CAT4 contention channel, because the CW size of CAT4 needs to be adjusted. This is because the data transmission failure that occurs when the UE actually executes CAT4 more realistically reflects the improper setting of the CAT4 CW parameters. Here, for a UE, its uplink reference subframe can be an uplink subframe scheduled by the base station based on CAT4. For example, the first uplink subframe of the most recent uplink transmission scheduled based on CAT4, that is, the base station may have continuously scheduled multiple subframes, of which the first part uses CAT2 and the other subframes use CAT4, then the uplink reference subframe is the first uplink subframe scheduled using CAT4. Alternatively, for a UE, its uplink reference subframe may be an uplink subframe actually transmitted by the UE during the most recent uplink transmission scheduled by the base station based on CAT4. For example, the first uplink subframe actually transmitted during the most recent uplink transmission scheduled based on CAT4. That is, the base station may have consecutively scheduled multiple subframes, the first portion of which uses CAT2 and the remaining subframes uses CAT4. In this case, the uplink reference subframe is the first uplink subframe actually transmitted by the UE using CAT4 scheduling. Here, due to the lack of UL-Grant and / or LBT failure of the UE, the first uplink subframe actually transmitted may not be the first CAT4 subframe scheduled by the base station. Alternatively, for a UE, its uplink reference subframe may be a portion or all of all uplink subframes scheduled based on CAT4 within the most recent uplink transmission time period. In the above method, the most recent uplink transmission refers to the most recent uplink transmission for which the base station already knows whether the UE's data transmission was successful. The present invention does not limit the use of other methods to determine the uplink reference subframe within one or more uplink subframes of the most recent uplink transmission scheduled based on CAT4.

[0152] According to the method of the second embodiment, if the base station configures LBT for a group of carriers and only executes CAT4 on one carrier and executes CAT2 on other carriers, then, because the carrier executing CAT4 has actually taken into account the data transmission status of other carriers in the same group, the uplink subframes executing CAT2 of all other carriers can be used as uplink reference subframes for CW adjustment of CAT4 on the corresponding carriers.

[0153] The second method for determining the uplink reference subframe is to adjust the CW size based on whether the UE's uplink data is successfully decoded, regardless of whether the above-mentioned data transmission of the UE is based on the LBT type, i.e., CAT2 and CAT4; and uplink data sent using NO LBT is not used as a basis for adjusting the CW size. Alternatively, the third method for determining the uplink reference subframe is to adjust the CW size based on whether the UE's uplink data is successfully decoded, regardless of whether the above-mentioned data transmission of the UE is based on CAT2, CAT4 or NO LBT. For example, for a UE, its uplink reference subframe can be an uplink subframe of the most recent uplink transmission scheduled by the base station. For example, for the second method for determining the uplink reference subframe, it can be the first scheduled uplink subframe excluding the uplink subframe scheduled using NO LBT, and for the third method for determining the uplink reference subframe, it can be the first uplink subframe scheduled by the base station. Alternatively, for a UE, its uplink reference subframe may be an uplink subframe actually transmitted by the UE in the most recent uplink transmission scheduled by the base station. For example, for the second method of determining the reference subframe, it is the first uplink subframe actually transmitted in the most recent uplink transmission scheduled by the base station, excluding the uplink subframe using NO LBT. For the third method of determining the uplink reference subframe, it is the first uplink subframe actually transmitted in the most recent uplink transmission scheduled by the base station. Alternatively, for a UE, its uplink reference subframe may be part or all of all uplink subframes in the most recent uplink transmission time period. For example, for the second method of determining the uplink reference subframe, uplink transmission scheduled using NO LBT is not used to adjust the CW size. In the above method, the most recent uplink transmission refers to the most recent uplink transmission for which the base station can already know whether the UE's data transmission is successful. For the second method of determining the reference subframe, excluding the uplink subframe using NO LBT, for one or more uplink subframes of the most recent uplink transmission scheduled by the base station, the present invention does not limit the use of other methods to determine the uplink reference subframe. For the third method of determining the reference subframe, for one or more subframes of the latest uplink transmission scheduled by the base station, the present invention does not limit the use of other methods to determine the uplink reference subframe.

[0154] For the case where the base station is responsible for maintaining the CW of the CAT4 operation of the UE, the above method of adjusting the CW can further distinguish the following three situations: whether the UE does not send uplink data because it does not receive the UL-Grant; or the UE fails to send uplink data due to uplink LBT failure; and the UE detects the UL-Grant, successfully performs LBT and sends uplink data, but the base station fails to decode it.

[0155] After determining the uplink reference subframe, for example, using the above three methods for determining the uplink reference subframe, the following describes a method for updating the CW. The present invention does not limit the use of other methods for updating the CW based on the uplink reference subframe.

[0156] For example, when the proportion of uplink data decoding failures in the uplink reference subframe is greater than or equal to a threshold Y, for example, threshold Y is equal to 80%, the CW of this UE is increased, unless the CW has reached the maximum value. Alternatively, when at least one uplink data decoding of the uplink reference subframe fails, the CW of this UE is increased, unless the CW has reached the maximum value. Alternatively, when all uplink data decoding of the uplink reference subframe fails, the CW of this UE is increased, unless the CW has reached the maximum value. When the uplink transmission supports multiple LBT priorities, the above operation may refer to updating the CAT4 parameters of all LBT priorities together; or, the above operation may refer to updating the CAT4 parameters of the LBT priorities separately, that is, in this example, only the CW size of the LBT priority of the uplink transmission in the uplink reference subframe is updated, and the CW of other LBT priorities is not changed.

[0157] For example, when the proportion of uplink data decoding failures of the uplink reference subframe is greater than or equal to a threshold W, for example, the threshold W is less than or equal to 80%, the CW size is set to CWmin. Alternatively, when all uplink data of the uplink reference subframe are successfully received, the CW size is set to CWmin. Alternatively, when at least one uplink data of the uplink reference subframe is successfully received, the CW size is set to CWmin. When the uplink transmission supports multiple LBT priorities, the above operation may mean that the CWs of all LBT priorities are set to CWmin at the same time. Alternatively, the above operation may mean updating the CAT4 parameters of the LBT priorities separately, that is, in this example, only the CW of the LBT priority of the uplink transmission in the uplink reference subframe is set to CWmin, and the CWs of other LBT priorities are not changed.

[0158] For both the aforementioned cases of increasing the CW size and restoring the CW to CWmin, the same method may be used to determine the uplink reference subframe, for example, one of the three aforementioned methods for determining the uplink reference subframe. Alternatively, different methods for determining the uplink reference subframe may be used for each of the aforementioned two cases. For example, for increasing the CW size, the second or third aforementioned method for determining the uplink reference subframe may be used, while for restoring the CW to CWmin, only the first aforementioned method for determining the uplink reference subframe may be used.

[0159] When the uplink transmission supports one or more LBT priorities, for one LBT priority, when the number of CCA time slots for random backoff has been generated based on the maximum CW value for K consecutive times, and K is greater than or equal to 1, the CW size of this LBT priority can be reset to CWmin; or, the CW size of all LBT priorities can be reset to CWmin. Here, if the base station only schedules uplink data transmission based on NO LBT or CAT2 for one UE, the base station may not update the number of times the number of CCA time slots for random backoff is generated based on the maximum CW value for any LBT priority of this UE. Alternatively, assume that the base station schedules the UE's uplink transmission based on CAT4, and the currently used CW size is the maximum CW value of the LBT priority scheduled this time, but the base station detects that the UE has not actually sent uplink data, for example, UE If no UL-Grant is received or LBT fails, the base station may not update the number of CCA time slots for random backoff generated based on the maximum CW value for the LBT priority of this scheduling, or the base station may still add one to the number of CCA time slots for random backoff generated based on the maximum CW value for the LBT priority of this scheduling. Assuming that the UE maintains the CAT4 parameter, if the UE receives a UL-Grant and indicates CAT4, and the currently used CW size is the maximum CW value of the current LBT priority, but the UE fails to successfully complete LBT and thus fails to send uplink data, the UE may not update the number of CCA time slots for random backoff generated based on the maximum CW value for the current LBT priority, or the UE may still add one to the number of CCA time slots for random backoff generated based on the maximum CW value for the current LBT priority.

[0160] The above-mentioned CW adjustment operation can be to adjust the CAT4 CW size based on the UE's most recent uplink transmission each time the base station schedules uplink transmission for a UE; or, to adjust the CAT4 CW size based on the UE's most recent uplink transmission each time the base station schedules uplink transmission for a UE based on CAT4. Alternatively, the time interval T between two CW size adjustments can be limited, where T is a predefined or high-level configured parameter. For example, the CW size needs to be adjusted only when the time interval between two uplink schedulings is greater than T; or, the CW size needs to be adjusted only when the time interval between two CAT4-based uplink schedulings is greater than T. Alternatively, the CW size needs to be adjusted only when the two uplink schedulings do not belong to the same MCOT; or, the CW size needs to be adjusted only when the two CAT4-based uplink schedulings do not belong to the same MCOT. Alternatively, when adjusting the CW based on the uplink reference subframe, the CW size may only need to be adjusted when the uplink reference subframe of the current uplink transmission scheduled based on CAT4 is a different subframe from the uplink reference subframe of the previous uplink transmission scheduled based on CAT4; otherwise, the CW may remain unchanged. For example, assuming that the base station sends multiple UL-Grants within a downlink subframe, or sends UL-Grants separately on consecutive downlink subframes, and the multiple UL-Grants are respectively scheduled for uplink transmission based on CAT4, because the multiple UL-Grants are located in the same downlink subframe or consecutive downlink subframes, the uplink reference subframe for adjusting the CW may point to the same uplink subframe. In this case, there is no need to repeatedly update the CW for the uplink transmissions scheduled by the multiple UL-Grants.

[0161] Corresponding to the above method, the present application also discloses a base station device, such as Figure 16 As shown, the device includes a scheduling module and a transceiver module, wherein:

[0162] The scheduling module is used to allocate uplink and downlink resources to the UE based on its ability to handle CA and LBT, and configure the LBT mechanism and related parameters used for uplink transmission. It also includes adjusting the CAT4 status parameters based on the UE's feedback message;

[0163] The transceiver module is used to send scheduling signaling to the UE, instructing the UE to perform uplink and downlink transmission, and to send downlink data and receive uplink data accordingly.

[0164] Corresponding to the above method, the present application also discloses a UE device, such as Figure 17 As shown, the device includes a scheduling and parsing module and a transceiver module, wherein:

[0165] The scheduling analysis module is used to analyze the scheduling instructions of the base station, determine the uplink and downlink resources allocated by the base station, and determine the LBT mechanism and related parameters used by the base station to configure uplink transmission;

[0166] The transceiver module is used to report the UE's ability to handle CA and LBT, and send downlink data and receive uplink data accordingly according to the base station scheduling signaling.

[0167] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0168] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0169] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0170] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method performed by a terminal in wireless communication, the method comprising: Sending an uplink signal to a base station in a first reference time domain resource; Determining hybrid automatic repeat request HARQ related information corresponding to the uplink signal; adjusting a value of a contention window CW used to perform the first process based on the determined HARQ-related information; If the HARQ-related information includes at least one ACK, setting the value of the CW to a value of a CW having a minimum size for each of a plurality of priority levels, otherwise increasing the value of the CW for each of the plurality of priority levels; as well as If the value of the CW for a first priority level among the plurality of priority levels is used for generating a number K times in succession with being equal to the value of the CW of the largest size, the value of the CW is reset to the value of the CW with the smallest size only for the first priority level.

2. The method according to claim 1, in, The priority level is a detect-before-transmit (LBT) priority level.

3. The method according to claim 1, in, K is greater than or equal to 1, and Here, the number is set between 0 and the value of CW.

4. A terminal, comprising: transceiver; and The processor is configured to: Sending an uplink signal to a base station in a first reference time domain resource; Determining hybrid automatic repeat request HARQ related information corresponding to the uplink signal; adjusting a value of a contention window CW used to perform the first process based on the determined HARQ-related information; If the HARQ-related information includes at least one ACK, setting the value of the CW to a value of a CW having a minimum size for each of a plurality of priority levels, otherwise increasing the value of the CW for each of the plurality of priority levels; as well as If the value of the CW for a first priority level among the plurality of priority levels is used for generating a number K times in succession with being equal to the value of the CW of the largest size, the value of the CW is reset to the value of the CW with the smallest size only for the first priority level.

5. The terminal according to claim 4, in, The priority level is a detect-before-transmit (LBT) priority level.

6. The terminal according to claim 4, in, K is greater than or equal to 1, and wherein the number is set between 0 and the value of CW.

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