Adaptive contention window and burst length for receiver-based ECCA for mmWave bands

Abstract

Aspects of improving LBT by associating a contention window with a transmission burst length and by allowing the contention window and maximum burst length to be adjusted based on interference activity are provided. For the downlink, the UE receives a PG for downlink transmission from a base station, the PG indicating a CCA length based on a contention window size associated with at least the burst length for downlink transmission. The UE performs CCA based on the CCA length after receiving a pre-grant, sends an APG to the base station when the CCA is successful, and receives a downlink transmission in response to the APG. For the uplink, the base station performs CCA based on a contention window associated with at least the burst length for uplink transmission, sends an uplink grant to the UE when the CCA is successful, and receives an uplink transmission in response to the uplink grant.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the following applications: U.S. Provisional Application Serial No. 62 / 971,495, filed on February 7, 2020, and entitled “ADAPTIVE CONTENTION WINDOW AND BURST LENGTH FOR RECEIVER BASED ECCA FOR MMWAVE BAND”; and U.S. Patent Application Serial No. 17 / 125,059, filed on December 17, 2020, and entitled “ADAPTIVE CONTENTION WINDOW AND BURST LENGTH FOR RECEIVER BASED ECCA FORMMWAVE BAND”, the entire contents of all of the above applications are expressly incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to communication systems, and more particularly, to wireless communication systems between user equipment (UE) and base stations. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at city, country, region, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution released by the Third Generation Partnership Project (3GPP) to meet new requirements and other requirements associated with latency, reliability, security, scalability (e.g., about the Internet of Things (IoT)). 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Some aspects of 5GNR can be based on 4G Long Term Evolution (LTE) standards. There is a need for further improvement of 5G NR technology. These improvements can also be applied to other multiple access technologies and telecommunication standards that adopt these technologies. Summary of the invention

[0006] A simplified summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive review of all contemplated aspects, and is neither intended to identify key or important elements of all aspects, nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be presented later.

[0007] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The apparatus receives a pre-grant for downlink transmission from a base station, the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission. After receiving the pre-grant, the apparatus performs a CCA based on the CCA length. When the CCA succeeds, the apparatus sends an acknowledgment (APG) of the pre-grant to the base station. The apparatus receives the downlink transmission in response to the APG from the base station.

[0008] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The apparatus receives an uplink grant from a base station after a clear channel assessment (CCA) of the base station. The apparatus sends an uplink transmission to the base station in response to the uplink grant, wherein the CCA is based on a contention window associated with at least a burst length for the uplink transmission.

[0009] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a base station. The apparatus sends a pre-grant for downlink transmission to a user equipment (UE), the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission. When a CCA of the UE based on the CCA length is successful, the apparatus receives an acknowledgment (APG) of the pre-grant from the UE. The apparatus sends the downlink transmission to the UE in response to the APG.

[0010] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a base station. The apparatus performs a clear channel assessment (CCA) based on a contention window associated with at least a burst length for uplink transmission. When the CCA is successful, the apparatus sends an uplink grant to a user equipment (UE). The apparatus receives the uplink transmission in response to the uplink grant from the UE.

[0011] To accomplish the foregoing and related ends, one or more aspects include features hereinafter fully described and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of only some of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram illustrating an example of a wireless communication system and an access network.

[0013] Figure 2A , 2B , 2C and 2D are schematic diagrams showing examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame and a UL channel within a 5G / NR subframe, respectively.

[0014] Figure 3 is a schematic diagram showing an example of a base station and a user equipment (UE) in an access network.

[0015] Figure 4 is a schematic diagram showing an example in which a UE receives a downlink burst from a base station.

[0016] Figure 5 is a schematic diagram showing another example in which a UE receives a downlink burst from a base station.

[0017] Figure 6 is a schematic diagram showing an example in which a UE receives different downlink bursts from a base station.

[0018] Figure 7 is a schematic diagram showing an example in which a base station receives different uplink bursts from a UE.

[0019] Fig. 8A and 8B is a schematic diagram showing an example in which a UE receives and acknowledges different downlink bursts from a base station.

[0020] Fig. 9 The present invention is a flow chart of a method for wireless communication in which a UE receives downlink data.

[0021] Fig.10 The present invention is a flow chart of a method for wireless communication in which a UE sends uplink data.

[0022] Fig.11 The present invention is a flow chart of a method for wireless communication in which a base station sends downlink data.

[0023] Fig.12 The present invention is a flow chart of a method for wireless communication in which a base station receives uplink data.

[0024] Fig.13 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0025] Fig.14 is a schematic diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

[0026] Fig.15 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0027] Fig.16 is a schematic diagram illustrating an example of a hardware implementation for an apparatus employing a processing system. DETAILED DESCRIPTION

[0028] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be implemented. In order to provide a thorough understanding of each concept, the detailed description includes specific details. However, it will be apparent to those skilled in the art that these concepts may be implemented without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid blurring such concepts.

[0029] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0030] For example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. Examples of processors include: microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set operations (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout the present disclosure. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language or other names, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0031] Accordingly, in one or more example aspects, the described functions can be implemented with hardware, software or any combination thereof. If implemented with software, the functions can be stored on a computer-readable medium or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media can be any available media that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the above types, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

[0032] Figure 11 is a schematic diagram showing an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0033] The base station 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with the EPC 160 via a first backhaul link 132 (e.g., an S1 interface). The base station 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) can interface with the core network 190 via a second backhaul link 184. Among other functions, the base station 102 can also perform one or more of the following functions: transmission of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, positioning, and transmission of warning messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a third backhaul link 134 (eg, an X2 interface). The third backhaul link 134 may be wired or wireless.

[0034] Base station 102 can communicate wirelessly with UE 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. There can be overlapping geographic coverage areas 110. For example, a small cell 102' can have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 can include an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from base station 102 to UE 104. The communication link 120 can use multiple input multiple output (MIMO) antenna technology, which includes spatial multiplexing, beamforming and / or transmit diversity. The communication link can be through one or more carriers. The base station 102 / UE 104 may use spectrum with a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) for transmission in each direction. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0035] Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communications may be through a variety of wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0036] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communicating to determine whether the channel is available.

[0037] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as the 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may improve coverage and / or increase capacity of the access network.

[0038] The base station 102 (whether a small cell 102' or a large cell (e.g., a macro base station)) may include and / or be referred to as an eNB, a gNodeB (gNB), or another type of base station. Some base stations (such as gNB180) may operate in the traditional sub-6 GHz spectrum, in millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with the UE 104. When the gNB180 operates in mmW or near mmW frequencies, the gNB180 may be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and has a wavelength between 1 mm and 10 mm. Radio waves in this band may be referred to as millimeter waves. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also referred to as centimeter waves. Communications using the mmW / near mmW radio frequency bands (e.g., 3 GHz-300 GHz) have extremely high path losses and short distances. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range. The base station 180 and the UE 104 may each include multiple antennas to facilitate beamforming, such as antenna elements, antenna panels, and / or antenna arrays.

[0039] Base station 180 may transmit beamformed signals in one or more transmit directions 182' to UE 104. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182". UE 104 may also transmit beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction for base station 180 may be the same or may be different. The transmit direction and receive direction for UE 104 may be the same or may be different.

[0040] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0041] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Typically, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0042] A base station may include and / or be referred to as a gNB, a Node B, an eNB, an access point, a base transceiver, a radio base station, a radio transceiver, a transceiver functional unit, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), or some other appropriate term. The base station 102 provides an access point to the EPC 160 or the core network 190 for the UE 104. Examples of UE 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio unit, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of the UEs 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, an oven, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0043] Refer again Figure 1In certain aspects, the UE 104 may include a UE LBT component 198 configured to: receive a pre-grant for downlink transmission from a base station, the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length for the downlink transmission; after receiving the pre-grant, perform a CCA based on the CCA length; when the CCA is successful, send an acknowledgment (APG) of the pre-grant to the base station; and receive a downlink transmission in response to the APG from the base station. The UE LBT component 198 may also be configured to: receive an uplink grant from the base station after the clear channel assessment (CCA) of the base station; and send an uplink transmission to the base station in response to the uplink grant, wherein the CCA is based on a contention window associated with at least a burst length for the uplink transmission.

[0044] Still reference Figure 1 In other aspects, the base station 102 / 180 may include a base station LBT component 199 configured to: send a pre-grant for downlink transmission to a user equipment (UE), the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission; when the UE's CCA based on the CCA length is successful, receive an acknowledgment (APG) of the pre-grant from the UE; and send a downlink transmission to the UE in response to the APG. The base station LBT component 199 may also be configured to perform a clear channel assessment (CCA) based on a contention window associated with at least a burst length for uplink transmission; when the CCA is successful, send an uplink grant to the user equipment (UE); and receive an uplink transmission in response to the uplink grant from the UE.

[0045] Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0046] Figure 2A 200 is a diagram illustrating an example of a first subframe within a 5G NR frame structure. Figure 2B 230 is a diagram illustrating an example of DL channels within a 5G NR subframe. Figure 2C 250 is a diagram illustrating an example of a second subframe within a 5G NR frame structure. Figure 2D 280 is a diagram illustrating an example of UL channels within a 5G NR subframe. The 5G NR frame structure may be FDD (wherein, for a particular set of subcarriers (carrier system bandwidth), subframes within the subcarrier set are dedicated to either DL or UL), or may be TDD (wherein, for a particular set of subcarriers (carrier system bandwidth), subframes within the subcarrier set are dedicated to both DL and UL). Figure 2A, 2C In the example provided, the 5G / NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (most of which are DL), where D is DL, U is UL, and X is flexible between DL / UL, and subframe 3 is configured with slot format 34 (most of which are UL). Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe can be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mix of DL, UL and flexible symbols. The UE is configured to have a slot format (dynamically configured by DL control information (DCI) or semi-statically / statically configured by radio resource control (RRC) signaling) through a received slot format indicator (SFI). It should be noted that the following description also applies to the 5G NR frame structure as TDD.

[0047] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 subframes (1ms) of equal size. Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4 or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbol on the DL may be a cyclic prefix (CP) OFDM (CP-OFDM) symbol. The symbol on the UL may be a CP-OFDM symbol (for high throughput scenarios) or a discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbol (also known as a single carrier frequency division multiple access (SC-FDMA) symbol) (for power-limited scenarios; limited to single stream transmission). The number of time slots in a subframe may be based on the time slot configuration and numerology. For slot configuration 0, different digital schemes μ0 to 5 allow 1, 2, 4, 8, 16 and 32 slots per subframe, respectively. For slot configuration 1, different digital schemes 0 to 2 allow 2, 4 and 8 slots per subframe, respectively. Accordingly, for slot configuration 0 and digital scheme μ, there are 14 symbols / slot and 2 μ time slots / subframe. The subcarrier spacing and symbol length / duration are functions of the digital scheme. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is digital scheme 0 to 5. Therefore, digital scheme μ=0 has a subcarrier spacing of 15kHz, and digital scheme μ=5 has a subcarrier spacing of 480kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figures 2A-2DAn example is provided for slot configuration 0 with 14 symbols per slot and a digital scheme μ = 2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

[0048] The resource grid can be used to represent the frame structure. Each time slot includes a resource block (RB) (also called a physical RB (PRB)), which extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0049] like Figure 2A As shown in , some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) for channel estimation at the UE (indicated as R for a specific configuration). x , where 100x is the port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0050] Figure 2B Examples of various DL channels within a subframe of a frame are shown. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE includes nine RE groups (REGs), and each REG includes 4 consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) can be within symbol 2 of a specific subframe of the frame. The PSS is used by UE104 to determine the subframe / symbol timing and the physical layer identification. The secondary synchronization signal (SSS) can be within symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identification group number and the radio frame timing. Based on the physical layer identification and the physical layer cell identification group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the above-mentioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth and the system frame number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not sent through the PBCH (such as System Information Blocks (SIBs)), and paging messages.

[0051] As in Figure 2CAs shown in , some of the REs carry DM-RS for channel estimation at the base station (indicated as R for a specific configuration, but other DM-RS configurations are possible). The UE can send DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS can be sent in the first one or two symbols of the PUSCH. The PUCCH DM-RS can be sent in different configurations depending on whether a short PUCCH or a long PUCCH is sent and depending on the specific PUCCH format used. The UE can send a sounding reference signal (SRS). The SRS can be sent in the last symbol of the subframe. The SRS can have a comb structure, and the UE can send the SRS on one of the combs in the comb. The SRS can be used by the base station for channel quality estimation to achieve frequency-dependent scheduling on the UL.

[0052] Figure 2D Examples of various UL channels within a subframe of a frame are shown. The PUCCH may be positioned as indicated in one configuration. The PUCCH carries uplink control information (UCI) such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and HARQ ACK / NAC feedback. The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0053] Figure 33 is a block diagram of a base station 310 in an access network communicating with a UE 350. In the DL, IP packets from the EPC 160 may be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functions. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides: RRC layer functions associated with: broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with: header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and switching support functions; RLC layer functions associated with: transmission of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0054] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation diagram based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be split into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived based on reference signals and / or channel condition feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0055] At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If multiple spatial streams are destined for the UE 350, the RX processor 356 can merge them into a single OFDM symbol stream. The RX processor 356 then transforms the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by the base station 310. The data and control signals are then provided to the controller / processor 359, which implements layer 3 and layer 2 functions.

[0056] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0057] Similar to the functions described for DL ​​transmission performed in conjunction with the base station 310, the controller / processor 359 provides: RRC layer functions associated with: system information (e.g., MIB, SIB) capture, RRC connection, and measurement reporting; PDCP layer functions associated with: header compression / decompression, and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with: transmission of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0058] The TX processor 368 may select an appropriate coding and modulation scheme and facilitate spatial processing using channel estimates derived by the channel estimator 358 based on a reference signal or feedback sent by the base station 310. The spatial streams generated by the TX processor 368 may be provided via separate transmitters 354TX to different antennas 352. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0059] At the base station 310, the UL transmission is processed in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

[0060] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0061] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to perform operations related to Figure 1 Various aspects related to the UE LBT component 198.

[0062] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 Various aspects related to the base station LBT component 199.

[0063] In millimeter wave (mmW) links, due to the highly directional nature of transmission, different interference patterns are observed by the transmitter and receiver. Therefore, a listen-before-talk (LBT) process is generally used to protect the reception of data from interference from other nodes. In LBT, a receiver (e.g., UE or base station) applies a clear channel assessment (CCA) check before using the channel. CCA uses at least energy detection to determine the presence or absence of other signals on the channel in order to determine whether the channel is occupied or idle, respectively. After obtaining channel access via a successful LBT operation, the receiver reserves the channel so that other nodes sense the channel to be occupied and therefore avoid sending on the channel. As a result, when obtaining access to the channel, data received by the UE or base station can be protected from interference. In addition, unnecessary backoff during LBT can be avoided and the receiver can be protected.

[0064] Channel access schemes can be classified into several categories: not utilizing LBT (category 1) and utilizing LBT (category 2-4). In category 2 LBT, the UE or base station applies LBT without random backoff. That is, the duration for which the channel is sensed as idle before transmission on the channel is deterministic (not random). In category 3 LBT and category 4 LBT, the UE or base station applies LBT with random backoff, respectively, with a contention window of fixed size or variable size. In this process, the UE or base station derives a random number N within the contention window. The size of the contention window is specified by the minimum and maximum values ​​of N. The size of the contention window is fixed in category 3 LBT, while the size of the contention window can be changed when a random number is derived in category 4 LBT. For example, the contention window size in category 4 LBT can be changed based on the channel access priority level (CAPC) or the quality of service (QoS) of the service. The random number N is used in the LBT process to determine the duration for which the channel is sensed as idle before transmission on the channel.

[0065] In Category 2 LBT, the UE or base station applies CCA to detect whether the channel is idle within a fixed time period. If the channel is sensed to be busy, the UE or base station avoids accessing the channel. Otherwise, the UE or base station continues to access the channel within the channel occupation time (COT). In contrast, in Category 3 and 4 LBT (also known as long LBT), if the initial CCA is unsuccessful, the UE or base station further applies an extended CCA (eCCA) to detect whether the channel is idle within a random time period corresponding to the derived random number within the contention window. The UE or base station waits for a postponement period (e.g., a time period equal to the time period used for the initial CCA), and then senses whether the channel is busy during the random time period. If the channel is sensed to be busy, the UE or base station avoids accessing the channel, and the eCCA process may be repeated. Otherwise, the UE or base station continues to access the channel within the COT.

[0066] Typically, when the UE is receiving downlink data, the base station performs Category 2 LBT and, if successful, sends a downlink grant to the UE that schedules downlink transmission. However, although the base station may sense an idle channel due to the lack of interference from the base station, the UE may still experience interference and may therefore fail to successfully receive a downlink grant or transmission from the base station. Therefore, in order to allow the UE to confirm that the receiver side channel is idle for reception, the base station may send a pre-grant (PG) to the UE, which is a control signaling message that triggers the UE to perform Category 4 LBT (including eCCA). When the UE receives the PG, the UE performs eCCA, and if low interference or no interference is detected as a result, the UE sends an acknowledgment of the pre-grant (APG) to the base station. The base station can determine that the UE is in a safe state to receive data based on the APG, and the base station can then send a downlink grant and a downlink transmission to the UE in a downlink burst accordingly. Otherwise, if a large amount of interference is detected, the UE avoids sending the APG (thereby refusing to receive the scheduling), and the base station determines not to send a downlink burst.

[0067] Figure 4 An example schematic diagram 400 is shown of a UE 402 receiving a downlink burst from a base station 404 after sending an APG in response to a PG. The base station performs a CCA 406 (e.g., a Category 2 LBT) to determine whether the channel is idle for transmission. If the CCA 406 is successful, the base station sends a PG 408 to the UE. After receiving the PG, the UE then performs an eCCA 410 (e.g., a Category 4 LBT) to determine whether the channel is idle for transmission. If the eCCA 410 is successful, the UE sends an APG 412 to the base station. When the base station receives the APG, the base station again performs a CCA 414 (e.g., a Category 2 LBT) to determine whether the channel is idle for transmission, and if the CCA 414 is successful, the base station sends a downlink burst 416 (including a downlink grant and a downlink transmission) to the UE. After receiving a downlink transmission, the UE performs CCA 418 (e.g., Category 2 LBT) to determine whether the channel is idle for transmission, and if CCA 418 is successful, the UE sends an acknowledgement (ACK) / negative acknowledgement (NACK) feedback 420 to the base station based on whether the downlink transmission was successfully received.

[0068] However, in some situations, the base station may not receive the APG from the UE. For example, although the UE receives the PG, the UE may fail to pass the Category 4 LBTCCA for the APG transmission due to the presence of interfering transmissions (e.g., caused by a jammer). That is, when competing for a channel with a jammer, the UE may fail to pass the CCA and therefore does not send the APG to the base station. In such a case, if the base station does not receive the APG from the UE, the base station will consider that the APG has not been received, indicating that the UE has detected a jammer and is therefore unable to receive a pre-approved downlink burst. In another example, the UE may not receive the PG, for example, due to an ongoing transmission from a jammer (which interferes with the UE's reception of the PG), or due to link budget constraints, beam management limitations, or control channel rate control limitations.

[0069] For example, Figure 5 An example schematic diagram 500 is shown of a UE 502 served by a base station 504 and an aggressor base station 506 serving another UE (not shown). Figure 4 Similar to the described example, the base station 504 may generally perform CCA 508 (e.g., Category 2 LBT) and, if the CCA is successful, send a PG 510 to the UE, and the UE may perform eCCA 512 (e.g., Category 4 LBT) and, if the CCA is successful, send an APG 514 to the base station. If the base station receives the APG, the base station may perform CCA 516 (e.g., Category 2 LBT) and, if the CCA is successful, send a DL data burst 518 to the UE, and the UE may perform CCA 520 (e.g., Category 2 LBT) and, if the CCA is successful, send ACK / NACK feedback 522 to the base station. However, in the case where the aggressor base station 506 simultaneously transmits its own transmission 524 to another UE (which interferes with the transmission of UE 502), the base station 504 may fail to receive the APG 514 from the UE. Although the base station 504 may not be able to distinguish whether the failure to receive the APG from the UE is due to the UE's failure to receive the PG or due to the UE's failure to perform eCCA, in either case the base station 504 may omit sending a downlink burst due to the failure to receive the APG.

[0070] In the above example, by randomizing the start time for transmission over a channel, Category 4 LBT can be effective in minimizing collisions in sub-7 GHz operation. For example, by having a large contention window, there can be a low probability that a receiver (e.g., UE 502) may derive the same random number as other nodes, and thus these nodes will likely have different random start positions in eCCA. Additionally, if other nodes derive a larger random number compared to the receiver, the receiver's early transmission will be used to block interfering transmissions from other nodes, thereby minimizing the chance of collisions.

[0071] However, in a mmW environment, collisions may not necessarily be avoided by randomizing the start time for transmission over a channel for each node. For example, narrow beams are typically used for transmission and reception in mmW, and thus fewer nodes may interfere with a receiver (e.g., UE 502). As a result, it is less likely that the receiver and these nodes will derive random numbers in eCCA at the same time. Additionally, having a large contention window to reduce the collision probability for a large number of nodes may not necessarily be as efficient as in sub-7 GHz operation, since the effective node density may be reduced due to fewer interfering nodes in mmW. Therefore, a smaller contention window can be effectively used for Category 4 LBT in a mmW environment.

[0072] However, although a smaller contention window (e.g., a contention window of one time slot, also referred to as single-shot LBT) can be used to effectively measure a high interference level in a mmW environment (since the same interference level will be sensed from one or more measurements, but with a small difference in accuracy), a larger contention window can be used to provide a higher confidence level that interference will not likely occur in the near future when the receiver (e.g., UE 502) is receiving a downlink burst. When a transmission is received in a burst, the interference activity can be time-correlated with the observed time slots in the contention window, and thus the receiver can determine with different confidence levels whether future interference is likely to occur in the next burst. For example, if the receiver measures that X observed time slots have no interference, the receiver can determine that the next Y ms will also have no interference. This time correlation may degrade over time (e.g., if Y1 < Y2, the next Y1 ms will be more likely to have no interference than the next Y2 ms). Additionally, a higher confidence level can be determined from a larger contention window (e.g., if X1 > X2, the next Y ms will be more likely to have no interference based on similar observations in X1 time slots compared to in X2 time slots).

[0073] Therefore, in order to improve LBT in mmW environments based on the above-mentioned time correlation, the present disclosure allows a receiver (e.g., UE 502 for downlink or base station 504 for uplink) that performs long LBT to associate the size of the contention window with the burst length of the received transmission. For example, when the burst length is large, the receiver can perform eCCA using a larger contention window, and when the burst length is short, the receiver can perform eCCA using a smaller contention window. In addition, based on the above-mentioned time correlation, the present disclosure allows the receiver to adjust the maximum burst length and / or contention window size to perform long LBT in subsequent receptions. In this way, eCCA and / or maximum COT can be adjusted to account for changes in interference activity at the receiver.

[0074] For DL ​​bursts, the base station may indicate to the UE in the PG how long the UE should perform long LBT. The base station may indicate the CCA length in the PG based on a contention window size associated with at least the burst length of the downlink transmission. For example, the base station may indicate a random number (e.g., backoff or countdown) in the PG. Alternatively or in addition, the base station may indicate the contention window size in the PG. The UE may determine the size of the contention window based on the association of the burst length with the contention window. The association may be preconfigured by the network (e.g., core network 190) or configured by the base station. For example, if the base station sends a DL transmission with a burst length of 10ms, the associated contention window may be [0 to 511], and if the base station sends a DL transmission with a burst length of 5ms, the associated contention window may be [0 to 255]. As a result, when performing eCCA, the UE may derive a random number between 0 and 511 or between 0 and 255 based on the burst length of the downlink data. Other examples of burst lengths and associated contention windows are possible.

[0075] Figure 6An example schematic diagram 600 is shown of a UE 602 performing LBT of different sizes after receiving downlink bursts of different lengths from a base station 604. The base station sends a PG 606 indicating information 608 about an eCCA to be performed by the UE. For example, the PG may indicate a CCA length based on a contention window size associated with at least a burst length of an upcoming downlink transmission 610. In this example, the base station may configure the burst length of the downlink transmission 610 to be 10 ms. The UE then performs an eCCA 612 after receiving the PG. For example, the UE may determine the contention window associated with the 10 ms burst length to be [0 to 511] based on a configured association between the burst length and the contention window size, and the UE may derive a large random number (e.g., the indicated CCA length) within the contention window. If the eCCA is successful (e.g., the UE senses that the channel is idle during a number of observation slots corresponding to the derived random number), the UE sends an APG 614 to the base station. After receiving the APG, the base station sends a downlink transmission 610 to the UE.

[0076] Subsequently (or alternatively), the base station may send a PG 616 indicating information 618 about another eCCA to be performed by the UE. For example, the PG may indicate a CCA length based on a contention window size associated with at least the burst length of the upcoming downlink transmission 620. In this example, the base station may configure the burst length of the downlink transmission 620 to be 5 ms. Then, the UE performs eCCA 622 after receiving the PG. For example, the UE may determine the contention window associated with the 5 ms burst length to be [0 to 255] based on the configured association between the burst length and the contention window size, and the UE may derive a smaller random number (e.g., the indicated CCA length) within the contention window than in the previous example. Therefore, the number of observed slots measured by the UE when performing eCCA 622 is smaller than in eCCA 612. If the eCCA is successful, the UE sends an APG 624 to the base station. After receiving the APG, the base station sends a downlink transmission 620 to the UE.

[0077] Finally (or alternatively), the base station may send a PG 626 indicating information 628 about another eCCA to be performed by the UE. For example, the PG may indicate a CCA length based on a contention window size associated with at least the burst length of the upcoming downlink transmission 630. In this example, the base station may configure the burst length of the downlink transmission 630 to be 2 ms. The UE then performs an eCCA 632 after receiving the PG. For example, the UE may determine the contention window associated with the 2 ms burst length to be [0 to 127] based on the configured association between the burst length and the contention window size, and the UE may derive a smaller random number (e.g., the indicated CCA length) within the contention window than in the previous two examples. Therefore, the number of observation slots measured by the UE when performing the eCCA 632 is smaller than in the eCCAs 612 and 622. If the eCCA is successful, the UE sends an APG 634 to the base station. After receiving the APG, the base station sends a downlink transmission 630 to the UE.

[0078] For UL bursts, the base station performs a long LBT before sending an uplink grant that schedules an uplink transmission with a configured burst length from the UE. The base station may determine the size of the contention window based at least on the association of the burst length of the uplink transmission with the contention window. The association may be preconfigured by the network (e.g., core network 190) or configured by the base station. For example, in one example, if the UE sends an UL transmission with a burst length of 10ms, the associated contention window may be [0 to 511], and in another example, if the UE sends an UL transmission with a burst length of 5ms, the associated contention window may be [0 to 255]. As a result, when performing eCCA, the base station may derive a random number between 0 and 511 or between 0 and 255 based on the burst length of the uplink data in these examples. Other examples of burst lengths and associated contention windows are possible.

[0079] Figure 7An example schematic diagram 700 is shown in which a base station 702 performs LBT of different sizes before sending an uplink grant that schedules uplink bursts of different lengths from a UE 704. The base station can determine the burst length of a planned uplink transmission 706. For example, the base station can configure the burst length of the uplink transmission 706 to be 10 ms. Then, the base station performs eCCA 708 after determining the burst length. For example, the base station can determine the contention window associated with the 10 ms burst length to [0 to 511] based at least on the configured association between the burst length and the contention window size, and the base station can derive a large random number within the contention window. If the eCCA is successful (e.g., the base station senses that the channel is idle during the number of observation slots corresponding to the derived random number), the base station sends an uplink grant 710 to the UE. Then, the base station receives the uplink transmission 706 from the UE.

[0080] Subsequently (or alternatively), the base station may determine the burst length of another planned uplink transmission 712. For example, the base station may configure the burst length of the uplink transmission 712 to 5 ms. Then, the base station performs eCCA 714 after determining the burst length. For example, the base station may determine the contention window associated with the 5 ms burst length to [0 to 255] based at least on the configured association between the burst length and the contention window size, and the base station may derive a smaller random number within the contention window than in the previous example. Therefore, the number of observed time slots measured by the base station when performing eCCA 714 may be smaller than in eCCA 708. If the eCCA is successful, the base station sends an uplink grant 716 to the UE. Then, the base station receives the uplink transmission 712 from the UE.

[0081] Finally (or alternatively), the base station may determine the burst length of another planned uplink transmission 718. For example, the base station may configure the burst length of the uplink transmission 718 to be 2 ms. The base station then performs eCCA 720 after determining the burst length. For example, the base station may determine the contention window associated with the 2 ms burst length to be [0 to 127] based at least on the configured association between the burst length and the contention window size, and the base station may derive a smaller random number within the contention window than in the previous two examples. Therefore, the number of observed time slots measured by the base station when performing eCCA 720 may be smaller than in eCCA 708 and 714. If the eCCA is successful, the base station sends an uplink grant 722 to the UE. The base station then receives uplink transmission 718 from the UE.

[0082] In the above example, the receiver (e.g., UE 602 or base station 702) performs LBT using contention windows of different sizes according to the burst length of the upcoming transmission (downlink or uplink). Generally, the larger the contention window size (e.g., the more measurements to determine whether the channel is idle), the greater the confidence that the receiver can have about the channel will be idle in a larger amount of time in the future. Therefore, a larger contention window can be associated with a larger downlink or uplink burst, and similarly, a smaller contention window can be associated with a smaller downlink or uplink burst. However, despite the confidence that the upcoming downlink or uplink burst will be idle, interference activity at the receiver may still occur, which may cause the receiver to fail to successfully decode the transmission. In such a case, the receiver can notify the transmitter of an error event (e.g., the transmission is not successfully received) by sending a NACK feedback.

[0083] To address these error events, the base station can adjust the maximum downlink or uplink burst length (e.g., maximum COT) and / or the size of the contention window, and the receiver (e.g., UE for downlink or base station for uplink) can apply the adjusted maximum burst length or adjusted contention window when performing LBT for receiving subsequent transmissions. The maximum burst length or contention window can be adjusted based on feedback from error events. For example, after a UE (e.g., UE602) receives a downlink transmission from a base station, the UE can send ACK / NACK feedback to the base station, which indicates which (which) time slots in the downlink transmission are successfully received (ACK) and not successfully received (NACK), and the base station can adjust the maximum downlink burst length or contention window according to the received feedback. Similarly, in another example, after a base station (e.g., base station 702) receives an uplink transmission from a UE, the base station can determine which (which) time slots in the uplink transmission are successfully received or not successfully received, and the base station can adjust the maximum uplink burst length or contention window accordingly.

[0084] When determining which time slot(s) in a downlink transmission or uplink transmission (e.g., COT) is successfully received or unsuccessfully received, the base station applies a reference duration to the transmission, which includes the time slot of the transmission to be tested (e.g., for NACK). Although placing the reference duration at the beginning of the COT can help test current conflicts, this placement may not be as effective as at the end of the COT when testing the confidence or possibility of future conflict-free (based on the above-mentioned time correlation). Therefore, in the present disclosure, the base station applies the reference duration to the end of the COT. For example, when a UE receives a PDSCH transmission, the UE can determine whether it successfully or unsuccessfully decoded the last time slot in the PDSCH transmission, and sends ACK / NACK feedback, which indicates whether the time slot of the PDSCH transmission is ACK or NACK. The base station can then determine whether the feedback corresponding to the last time slot in the PDSCH transmission is ACK or NACK, and adjust the maximum COT for subsequent downlink transmissions or the contention window for the UE to perform subsequent eCCA accordingly. Similarly, when the UE sends a PUSCH transmission, the base station can determine whether it successfully or unsuccessfully decoded the last slot in the PUSCH transmission and adjust the maximum COT for subsequent uplink transmissions or the contention window for the base station to perform subsequent eCCA accordingly. After receiving a PUSCH transmission, the base station can send feedback to the UE by toggling (for ACK) or not toggling (for NACK) the new data indicator (NDI) in the subsequent uplink grant.

[0085] When the receiver determines the decoding result of PDSCH or PUSCH within the reference duration of COT, the base station can adjust the maximum COT length and / or the contention window size. In one example, the base station may not change the maximum COT length (e.g., the maximum burst length for subsequent transmissions will be the same as the previous transmission), but the base station may change the size of the contention window based on the error event. For example, if the reference duration is one time slot and indicates NACK, or if the reference duration is multiple time slots and at least a threshold number of time slots in these time slots indicate NACK, the base station may increase the contention window size for subsequent LBT (e.g., double it). Conversely, if the reference duration is one time slot and indicates ACK, or if the reference duration is multiple time slots and at least a threshold number of time slots in these time slots indicate ACK, the base station may reduce the contention window size for subsequent LBT (e.g., reset it to a minimum value).

[0086] In another example, the base station may not change the contention window size, but the base station may change the maximum COT length according to the error event. For example, if the reference duration is one time slot and indicates NACK, or if the reference duration is multiple time slots and at least a threshold number of time slots in these time slots indicate NACK, the base station may reduce the contention window size for subsequent LBT (e.g., halve it). Conversely, if the reference duration is one time slot and indicates ACK, or if the reference duration is multiple time slots and at least a threshold number of time slots in these time slots indicate ACK, the base station may increase the contention window size for subsequent LBT (e.g., reset it to a maximum value).

[0087] In another example, the base station may combine the previous two examples by adjusting both the maximum COT length and the size of the contention window based on error events as described above.

[0088] Fig. 8A and 8B UE 802, 852 is shown performing LBT with adjusted contention window size after receiving different downlink transmissions with the same maximum burst length from base stations 804, 854. Fig. 8A ) or performing LBT with the same contention window size after receiving a different downlink transmission with an adjusted maximum burst length from the base station ( Figure 8B ) example diagrams 800, 850. Initially, the base station sends a PG 806, 856 indicating information about an eCCA to be performed by the UE. For example, the PG may indicate a CCA length based on a contention window size associated with at least the maximum burst length of an upcoming downlink transmission 808, 858. In this example, the base station may configure the maximum burst length (e.g., maximum COT) of the downlink transmission 808, 858 to be 10ms. The UE then performs an eCCA 810, 860 after receiving the PG. For example, the UE may determine the contention window associated with the 10ms maximum burst length to be [0 to 511] based on the configured association between the maximum burst length and the contention window size, and the UE may derive a large random number (e.g., the indicated CCA length) within the contention window. If the eCCA is successful (e.g., the UE senses that the channel is idle during a number of observation slots corresponding to the derived random number), the UE sends an APG 812, 862 to the base station. After receiving the APG, the base station sends a downlink transmission 808, 858 to the UE.

[0089] When the UE receives the downlink transmission 808, 858, the UE determines whether it successfully or unsuccessfully decoded the data within the reference duration 814, 864. For example, the reference duration 814, 864 may be the last time slot of the PDSCH. In this example, the UE failed to successfully decode the data within the reference duration (e.g., due to new interference activity from the interferer base station), and therefore the UE sends NACK feedback 816, 866 to the base station. When the base station receives the NACK feedback from the UE, the base station determines that the UE likely failed to receive the data due to interference, and therefore Fig. 8A In the example of , the base station increases the contention window size for subsequent LBT while maintaining the same maximum burst length for subsequent downlink transmissions, and Figure 8B In the example of , the maximum burst length for subsequent downlink transmission is reduced while maintaining the same contention window size for subsequent LBT. The base station can then send the adjusted contention window size or the adjusted maximum burst length to the UE (e.g., in PG).

[0090] Subsequently, the base station may send a PG 818, 868 indicating information about another eCCA to be performed by the UE. For example, the PG may indicate a CCA length based on at least a contention window size associated with an adjusted maximum burst length for an upcoming downlink transmission 870, or based on an adjusted contention window size for performing an eCCA prior to receiving an upcoming downlink transmission 820. Fig. 8A In the example of , the base station may again configure the maximum burst length of the downlink transmission 820 to 10 ms. Then, the UE performs eCCA 822 after receiving the PG. For example, the UE may determine the contention window associated with the 10 ms burst length to be [0 to 1023] based on the adjusted contention window size, and the UE may derive a larger random number within the contention window than in the previous example (e.g., the indicated CCA length). If the eCCA is successful, the UE sends an APG 824 to the base station. After receiving the APG, the base station sends a downlink transmission 820 to the UE.

[0091] exist Figure 8BIn the example of , the base station can adjust the maximum burst length of the downlink transmission to 5 ms while keeping the contention window size the same. The UE then performs an eCCA 872 after receiving the PG. For example, the UE can determine the contention window associated with the 5 ms burst length to remain at [0 to 511] based on the adjusted maximum burst length, and the UE can derive a random number similar to the previous example within the contention window (e.g., the indicated CCA length). If the eCCA is successful, the UE sends an APG 874 to the base station. After receiving the APG, the base station sends a downlink transmission 870 to the UE.

[0092] When the UE receives the downlink transmission 820, 870, the UE determines whether it successfully or unsuccessfully decoded the data within the reference duration. In this example, the UE successfully decoded the data within the reference duration (e.g., due to the lack of interference activity from the interferer base station), and therefore the UE sends ACK feedback 826, 876 to the base station. When the base station receives the ACK feedback from the UE, the base station determines that the UE most likely successfully received the data due to the lack of interference, and therefore Fig. 8A In the example of , the base station resets the contention window size for subsequent LBT while maintaining the same maximum burst length for subsequent downlink transmissions, and Figure 8B In the example of , the maximum burst length for subsequent downlink transmission is increased while maintaining the same contention window size for subsequent LBT. The base station can then send the adjusted contention window size or the adjusted maximum burst length to the UE (e.g., in PG).

[0093] Finally, the base station may send a PG 828, 878 indicating information about another eCCA to be performed by the UE. For example, the PG may indicate a CCA length based on at least a contention window size associated with an adjusted maximum burst length for an upcoming downlink transmission 880, or based on an adjusted contention window size for performing an eCCA prior to receiving an upcoming downlink transmission 830. Fig. 8A In the example of , the base station may again configure the maximum burst length for downlink transmission 830 to 10 ms. Then, the UE performs eCCA 832 after receiving the PG. For example, the UE may determine the contention window associated with the 10 ms burst length to be [0 to 7] based on the adjusted contention window size, and the UE may derive a smaller random number within the contention window (e.g., the indicated CCA length) than in the previous example. If the eCCA is successful, the UE sends an APG 834 to the base station. After receiving the APG, the base station sends a downlink transmission 830 to the UE.

[0094] exist Figure 8B In the example of , the base station can adjust the maximum burst length of the downlink transmission to 15 ms while keeping the contention window size the same. The UE then performs eCCA 882 after receiving the PG. For example, the UE can determine the contention window associated with the 15 ms burst length to remain at [0 to 511] based on the adjusted maximum burst length, and the UE can derive a random number within the contention window similar to the previous example (e.g., the indicated CCA length). If the eCCA is successful, the UE sends an APG 884 to the base station. After receiving the APG, the base station sends a downlink transmission 880 to the UE.

[0095] therefore, Fig. 8A and 8B A downlink example is shown, where the contention window size or maximum burst length can be adjusted based on interference activity. The above process is similar for the uplink. For example, refer to Figure 7 , the base station 702 may perform LBT using the modulated contention window size before sending uplink grants 710, 716, 722 that schedule uplink bursts 706, 712, 718 from the UE 704 with the same maximum burst length (similar to Fig. 8A ), or performing LBT with the same contention window size before sending an uplink grant 710, 716, 722 scheduling an uplink burst 706, 712, 718 from the UE with an adjusted maximum burst length (similar to Figure 8B ). The base station may determine a maximum burst length for a planned uplink transmission 706, 712, 718, and perform an eCCA 708, 714, 720 after determining the maximum burst length. If the eCCA is successful, the base station sends an uplink grant 710, 716, 722 to the UE, and then receives an uplink transmission 706, 712, 718 from the UE. When the base station receives the uplink transmission, the base station determines whether it successfully or unsuccessfully decoded data within a reference duration (e.g., at the end of the COT). Based on whether the base station succeeded or failed to decode data within the reference duration, the base station may adjust the contention window size for a subsequent LBT while maintaining the same maximum burst length for subsequent uplink transmissions (similar to Fig. 8A ), or adjust the maximum burst length for subsequent uplink transmissions while maintaining the same contention window size for subsequent LBTs (similar to Figure 8B ).

[0096] Fig. 9900 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 104, 350, 402, 502, 602, 704, 802, 852, which may include memory 360, and may be the entire UE 350 or a component of the UE 350, such as TX processor 368, RX processor 356, and / or controller / processor 359). Optional aspects are shown with dashed lines. The method allows for improved receiver-based LBT for downlink transmissions.

[0097] At 902, a UE receives a pre-grant for a downlink transmission from a base station, the pre-grant indicating a CCA length based on a contention window size associated with at least a burst length of the downlink transmission.

[0098] At 904, the UE, after receiving the pre-grant, performs a CCA based on a CCA length. The CCA length may include a backoff within a contention window for the UE to apply when performing the CCA.

[0099] At 906, when the CCA is successful, the UE sends an acknowledgment (APG) of the pre-grant to the base station.

[0100] At 908, the UE receives a downlink transmission from the base station in response to the APG.

[0101] At 910, the UE sends an acknowledgement (ACK) / negative acknowledgement (NACK) feedback to a base station in response to a downlink transmission.

[0102] At 912, the UE performs a subsequent CCA before receiving a subsequent downlink transmission from the base station. At least one of the subsequent CCA or the subsequent downlink transmission may be based on ACK / NACK feedback associated with a reference duration at the end of the burst length for the downlink transmission. The downlink transmission may be a physical downlink shared channel (PDSCH), and the reference duration may be the last time slot of the PDSCH.

[0103] In one example, a subsequent downlink transmission may include the same maximum burst length as the maximum burst length for the downlink transmission, and a subsequent CCA may be performed based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on ACK / NACK feedback associated with the reference duration. When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window may be increased, and when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window may be decreased.

[0104] In another example, a subsequent downlink transmission may include an adjusted maximum burst length based on ACK / NACK feedback associated with a reference duration. A subsequent CCA may be performed based on a contention window that is the same as the contention window used for the downlink transmission. When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length may be reduced, and when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length may be increased.

[0105] In another example, subsequent downlink transmissions may include an adjusted maximum burst length, subsequent CCA may be performed based on an adjusted contention window associated with the adjusted maximum burst length, and the adjusted maximum burst length and the adjusted contention window may be based on ACK / NACK feedback associated with a reference duration.

[0106] Fig.10 1000 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 104, 350, 402, 502, 602, 704, 802, 852, which may include memory 360, and may be the entire UE 350 or a component of the UE 350, such as TX processor 368, RX processor 356, and / or controller / processor 359). Optional aspects are shown with dashed lines. The method allows for improved receiver-based LBT for uplink transmissions.

[0107] At 1002, a UE receives an uplink grant from a base station following a clear channel assessment (CCA) of the base station.

[0108] At 1004, the UE sends an uplink transmission to the base station in response to the uplink grant, wherein the CCA is based on a contention window associated with at least a burst length for the uplink transmission.

[0109] At 1006, the UE receives a feedback indication from the base station in response to the uplink transmission.

[0110] At 1008, after a subsequent CCA of the base station, the UE receives another uplink grant from the base station for a subsequent uplink transmission. At least one of the subsequent CCA or the subsequent uplink transmission may be based on a feedback indication associated with a reference duration at the end of a burst length for the uplink transmission. The uplink transmission may be a physical uplink shared channel (PUSCH), the reference duration may be the last time slot of the PUSCH, and the feedback indication may be based on a new data indicator (NDI) in another uplink grant for a hybrid automatic repeat request (HARQ) process.

[0111] In one example, a subsequent uplink transmission may include a maximum burst length that is the same as the maximum burst length for the uplink transmission, and a subsequent CCA may be based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on a feedback indication associated with a reference duration. When the feedback indication associated with the reference duration is a NACK, the adjusted contention window may be increased, and when the feedback indication associated with the reference duration is an ACK, the adjusted contention window may be decreased.

[0112] In another example, a subsequent uplink transmission may include an adjusted maximum burst length, the adjusted maximum burst length being based on a feedback indication associated with a reference duration. A subsequent CCA may be based on a contention window that is the same as the contention window used for the uplink transmission. When the feedback indication associated with the reference duration is a NACK, the adjusted maximum burst length may be reduced, and when the feedback indication associated with the reference duration is an ACK, the adjusted maximum burst length may be increased.

[0113] In another example, a subsequent uplink transmission may include an adjusted maximum burst length, a subsequent CCA may be based on an adjusted contention window associated with the adjusted maximum burst length, and the adjusted maximum burst length and the adjusted contention window may be based on a feedback indication associated with a reference duration.

[0114] Fig.11 1100 is a flow chart of a method of wireless communication. The method may be performed by a base station 310 (e.g., a base station 102 / 180, 310, 404, 504, 604, 702, 804, 854, which may include a memory 376 and may be the entire base station 310 or a component of the base station 310, such as a TX processor 316, a RX processor 370, and / or a controller / processor 375). Optional aspects are shown with dashed lines. The method allows for improved receiver-based LBT for downlink transmissions.

[0115] At 1102, a base station sends a pre-grant to a user equipment (UE) for a downlink transmission, the pre-grant indicating a CCA length based on a contention window size associated with at least a burst length of the downlink transmission.

[0116] At 1104, when the UE's CCA based on the CCA length is successful, the base station receives an acknowledgment (APG) of the pre-grant from the UE. The CCA length may include a backoff for the UE's CCA within a contention window.

[0117] At 1106, the base station sends a downlink transmission to the UE in response to the APG.

[0118] At 1108, the base station receives an acknowledgement (ACK) / negative acknowledgement (NACK) feedback from the UE in response to the downlink transmission.

[0119] At 1110, the base station sends a subsequent downlink transmission to the UE after a subsequent CCA of the UE. At least one of the subsequent CCA or the subsequent downlink transmission may be based on an ACK / NACK feedback associated with a reference duration at the end of the burst length for the downlink transmission. The downlink transmission may be a physical downlink shared channel (PDSCH), and the reference duration may be the last time slot of the PDSCH.

[0120] In one example, a subsequent downlink transmission may include the same maximum burst length as the maximum burst length for the downlink transmission, and a subsequent CCA may be based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on ACK / NACK feedback associated with the reference duration. When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window may be increased, and when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window may be decreased.

[0121] In another example, a subsequent downlink transmission may include an adjusted maximum burst length based on ACK / NACK feedback associated with a reference duration. A subsequent CCA may be based on a contention window that is the same as the contention window used for downlink transmissions. When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length may be reduced, and when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length may be increased.

[0122] In another example, subsequent downlink transmissions may include an adjusted maximum burst length, subsequent CCA may be based on an adjusted contention window associated with the adjusted maximum burst length, and the adjusted maximum burst length and adjusted contention window may be based on ACK / NACK feedback associated with a reference duration.

[0123] Fig.121200 is a flow chart of a method of wireless communication. The method may be performed by a base station 310 (e.g., a base station 102 / 180, 310, 404, 504, 604, 702, 804, 854, which may include a memory 376 and may be the entire base station 310 or a component of the base station 310, such as a TX processor 316, an RX processor 370, and / or a controller / processor 375). Optional aspects are shown with dashed lines. The method allows for improved receiver-based LBT for uplink transmissions.

[0124] At 1202, a clear channel assessment (CCA) is performed based on a contention window associated with at least a burst length for uplink transmission.

[0125] At 1204, when the CCA is successful, the base station sends an uplink grant to the user equipment (UE).

[0126] At 1206, the base station receives an uplink transmission from the UE in response to the uplink grant.

[0127] At 1208, the base station sends a feedback indication to the UE in response to the uplink transmission.

[0128] At 1210, the base station performs a subsequent CCA before sending another uplink grant for a subsequent uplink transmission to the UE. At least one of the subsequent CCA or the subsequent uplink transmission may be based on a feedback indication associated with a reference duration at the end of a burst length for the uplink transmission. The uplink transmission may be a physical uplink shared channel (PUSCH), the reference duration may be the last slot of the PUSCH, and the feedback indication may be based on a new data indicator (NDI) in another uplink grant for a hybrid automatic repeat request (HARQ) process.

[0129] In one example, a subsequent uplink transmission may include a maximum burst length that is the same as the maximum burst length for the uplink transmission, and a subsequent CCA may be performed based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on a feedback indication associated with a reference duration. When the feedback indication associated with the reference duration is a NACK, the adjusted contention window may be increased, and when the feedback indication associated with the reference duration is an ACK, the adjusted contention window may be decreased.

[0130] In another example, a subsequent uplink transmission may include an adjusted maximum burst length, the adjusted maximum burst length being based on a feedback indication associated with a reference duration. A subsequent CCA may be performed based on a contention window that is the same as the contention window used for the uplink transmission. When the feedback indication associated with the reference duration is a NACK, the adjusted maximum burst length may be reduced, and when the feedback indication associated with the reference duration is an ACK, the adjusted maximum burst length may be increased.

[0131] In another example, subsequent uplink transmissions may include an adjusted maximum burst length, subsequent CCA may be performed based on an adjusted contention window associated with the adjusted maximum burst length, and the adjusted maximum burst length and the adjusted contention window may be based on a feedback indication associated with a reference duration.

[0132] Fig.13 1300 is a conceptual data flow diagram illustrating the data flow between different units / components in an exemplary apparatus 1302. The apparatus may be a UE (eg, UE 104, 350, 502, 602, 704, 802, 852) in wireless communication with a base station 1350.

[0133] The apparatus includes a receiving component 1304 that receives downlink communications from a base station 1350. The receiving component 1304 may be configured to receive signals and / or other information from other devices including, for example, the base station 1350. The signals / information received by the receiving component 1304 may be provided to one or more components of the apparatus 1302 for further processing and for use in performing various operations according to the methods discussed above (including the processes of the flowcharts 900 and 1000 described above). Thus, via the receiving component 1304, the apparatus 1302 and / or one or more components therein receive signals and / or other information (such as downlink data and / or other control signaling for the apparatus 1302) from the base station 1350, as discussed above and also discussed in more detail below.

[0134] In some aspects, receiving component 1304 is configured to receive from a BS a pre-grant for a downlink transmission from a base station, e.g., as described in conjunction with Fig. 9 In some aspects, the pre-grant indicates a CCA length based on a contention window size associated with at least a burst length of a downlink transmission, e.g., as described in conjunction with Fig. 9 In some aspects, the receiving component 1304 is further configured to receive a downlink transmission from a base station in response to the APG, for example, as described in conjunction with Fig. 9As described in block 908 of . In some aspects, the receiving component 1304 is further configured to receive a subsequent downlink transmission from the BS. In some aspects, the subsequent downlink transmission includes a maximum burst length that is the same as the maximum burst length for the downlink transmission. In some aspects, the subsequent downlink transmission is based on an ACK / NACK feedback associated with a reference duration at the end of the burst length for the downlink transmission. In some aspects, the downlink transmission is a PDSCH and the reference duration is the last time slot of the PDSCH. In some aspects, the receiving component 1304 is configured to receive an uplink grant from the base station following a CCA of the base station, for example, as described in conjunction with Fig.10 In some aspects, the receiving component 1304 is configured to receive another uplink grant for a subsequent uplink transmission from the base station after a subsequent CCA of the base station, for example, as described in conjunction with Fig.10 In some aspects, the subsequent downlink transmission includes an adjusted maximum burst length. In some aspects, the adjusted maximum burst length is based on a feedback indication associated with the reference duration, such as ACK / NACK feedback. For example, when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length is reduced. In another example, when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length is increased.

[0135] The apparatus includes a clear channel assessment component 1308 configured to perform a CCA based on a CCA length after receiving a pre-grant, e.g., as in conjunction with Fig. 9 In some aspects, the CCA length includes a backoff within a contention window size for the UE to apply when performing the CCA. In some aspects, the clear channel assessment component 1308 performs the CCA based on at least the contention window associated with the burst length for the uplink transmission. The clear channel assessment component 1308 is also configured to perform a subsequent CCA before receiving a subsequent downlink transmission from the base station, for example, as described in conjunction with Fig. 9 912 of . In some aspects, subsequent CCA is performed based on an adjusted contention window associated with the same maximum burst length. In other aspects, subsequent CCA is performed based on a contention window size that is the same as the contention window size used for downlink transmissions. In other aspects, subsequent CCA is based on a contention window that is the same as the contention window used for uplink transmissions. In some aspects, subsequent CCA is based on ACK / NACK feedback associated with a reference duration at the end of the burst length used for downlink transmissions.

[0136] The apparatus includes a confirm pre-grant component 1310 configured to send a confirmation of the pre-grant (APG) to the base station when the CCA is successful, for example, as combined with Fig. 9 As described in block 906 of .

[0137] The apparatus includes a feedback component 1312 configured to receive a feedback indication from a base station in response to an uplink transmission, e.g., as in conjunction with Fig.10 In some aspects, the feedback indication is based on a new data indicator (NDI) in another uplink grant for a hybrid automatic repeat request (HARQ) process.

[0138] The apparatus includes a contention window component 1314 configured to determine a contention window. In some aspects, the contention window component 1314 is further configured to determine an adjusted contention window. In some aspects, the adjusted contention window is based on ACK / NACK feedback associated with a reference duration. For example, when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window is increased. In another example, when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window is reduced.

[0139] The apparatus includes a transmitting component 1306 that transmits uplink communications to a base station 1350. The transmitting component 1306 may be configured to transmit various messages to one or more external devices (e.g., including the base station 1350) in accordance with the methods disclosed herein. The message / signal to be transmitted may be generated by one or more other components as discussed above, or the message / signal to be transmitted may be generated by the transmitting component 1306 under the guidance / control of one or more other components discussed above. Thus, in various configurations, via the transmitting component 1306, the apparatus 1302 and / or one or more components therein transmit signals and / or other information (e.g., uplink data, control messages, and / or other signals) to an external device such as the base station 1350. In some aspects, the transmitting component 1306 is configured to send an acknowledgement (ACK) / negative acknowledgement (NACK) feedback to the base station in response to a downlink transmission, for example, as in conjunction with Fig. 9 In some aspects, the transmitting component 1306 is configured to transmit a subsequent downlink transmission. In some aspects, the subsequent uplink transmission includes an adjusted maximum burst length. In some aspects, the subsequent uplink transmission includes a maximum burst length that is the same as the maximum burst length for the uplink transmission. In some aspects, the transmitting component 1306 is configured to transmit an uplink transmission to the base station in response to the uplink grant, e.g., as described in conjunction with Fig.10As described in block 1004 of . In some aspects, the uplink transmission is a PUSCH, wherein the reference duration is a last slot of the PUSCH.

[0140] The device may include performing the above Fig. 9 and 10 Each block in the flowchart of the algorithm has additional components. Therefore, the above components can be executed by Fig. 9 and 10 Each block in the flowchart of the process / algorithm may be included in the apparatus, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0141] Fig.14 14 is a schematic diagram 1400 showing an example of a hardware implementation for an apparatus 1302' employing a processing system 1414. The processing system 1414 may be implemented using a bus architecture, generally represented by bus 1424. The bus 1424 may include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the processing system 1414. The bus 1424 connects together various circuits including one or more processors and / or hardware components (represented by processor 1420, components 1304, 1306, 1308, 1310, 1312, 1314, and computer readable medium / memory 1422). The bus 1424 may also connect various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described again.

[0142] The processing system 1414 may be coupled to a transceiver 1430. The transceiver 1430 is coupled to one or more antennas 1432. The transceiver 1430 provides a means for communicating with various other devices over a transmission medium. The transceiver 1430 receives signals from one or more antennas 1432, extracts information from the received signals, and provides the extracted information to the processing system 1414 (specifically, the receiving component 1304). In addition, the transceiver 1430 receives information from the processing system 1414 (specifically, the transmitting component 1306), and generates signals to be applied to one or more antennas 1432 based on the received information. The processing system 1414 includes a processor 1420 coupled to a computer-readable medium / memory 1422. The processor 1420 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1422. The software, when executed by the processor 1420, causes the processing system 1414 to perform the various functions described above for any particular device. The computer-readable medium / memory 1422 may also be used to store data manipulated by the processor 1420 when executing software. The processing system 1414 also includes at least one of the components 1304, 1306, 1308, 1310, 1312, 1314. The component may be a software component running in the processor 1420, located / stored in the computer-readable medium / memory 1422, one or more hardware components coupled to the processor 1420, or some combination thereof. The processing system 1414 may be a component of the UE 350 and may include at least one of the TX processor 368, the RX processor 356, and the controller / processor 359 and / or the memory 360.

[0143] In one configuration, an apparatus 1302 / 1302' for wireless communication includes: a unit for receiving a pre-grant for downlink transmission from a base station. In some aspects, the pre-grant indicates a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission. The apparatus 1302 / 1302' also includes: a unit for performing a CCA based on the CCA length after receiving the pre-grant. The apparatus 1302 / 1302' also includes: a unit for sending an acknowledgment (APG) of the pre-grant to the base station when the CCA is successful. The apparatus 1302 / 1302' also includes: a unit for receiving a downlink transmission in response to the APG from the base station.

[0144] In another configuration, the apparatus 1302 / 1302' for wireless communication includes: means for receiving an uplink grant from a base station after a CCA of the base station. The apparatus 1302 / 1302' also includes: means for sending an uplink transmission to the base station in response to the uplink grant. In some aspects, the CCA is based on a contention window associated with at least a burst length for the uplink transmission.

[0145] The aforementioned means may be one or more of the aforementioned components of the apparatus 1302 and / or a processing system 1414 of the apparatus 1302' configured to perform the functions recited by the aforementioned means. As described above, the processing system 1414 may include the TX processor 368, the RX processor 356, and the controller / processor 359. Thus, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0146] Fig.15 is a conceptual data flow diagram 1500 illustrating the data flow between different units / components in an exemplary apparatus 1502. The apparatus may be a base station (eg, BS 102, 180, 310, 504, 506, 604, 702, 804, 854) in wireless communication with a UE 1550.

[0147] Device 1502 includes a burst length component 1508, which is configured to determine the maximum burst length. In some aspects, subsequent uplink transmissions include an adjusted maximum burst length. In some aspects, subsequent uplink transmissions include a maximum burst length identical to the maximum burst length for uplink transmissions. In other aspects, the burst length component 1508 is configured to determine the adjusted maximum burst length. In some aspects, subsequent downlink transmissions include an adjusted maximum burst length. In some aspects, the adjusted maximum burst length is based on a feedback indication associated with a reference duration. For example, the adjusted maximum burst length is based on ACK / NACK feedback associated with a reference duration. In some aspects, when the feedback indication associated with the reference duration is NACK, the adjusted maximum burst length is reduced. For example, when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length is reduced. In other aspects, when the feedback indication associated with the reference duration is ACK, the adjusted maximum burst length is increased. For example, when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length is increased.

[0148] The apparatus 1502 includes a feedback indication component 1510 configured to receive an acknowledgement (ACK) / negative acknowledgement (NACK) feedback from a UE in response to a downlink transmission, for example, as described in conjunction with Fig.11 In some aspects, the feedback indication component 1510 is configured to send a feedback indication to the UE in response to the uplink transmission, for example, as described in conjunction with Fig.12 In some aspects, the feedback indication is based on a new data indicator (NDI) in another uplink grant for a hybrid automatic repeat request (HARQ) process. In some aspects, the adjusted maximum burst length and the adjusted contention window are based on the feedback indication associated with the reference duration. For example, the adjusted maximum burst length and the adjusted contention window are based on ACK / NACK feedback associated with the reference duration.

[0149] The apparatus 1502 includes a clear channel assessment component 1512 configured to perform CCA based on at least a contention window associated with a burst length for uplink transmission, e.g., as described in conjunction with Fig.12 In some aspects, the clear channel assessment component 1510 is further configured to perform a subsequent CCA before sending another uplink grant to the UE for a subsequent uplink transmission, for example, as described in conjunction with Fig.12 As described in block 1210 of . In some aspects, at least one of a subsequent CCA or a subsequent uplink transmission is based on a feedback indication associated with a reference duration at the end of a burst length for uplink transmission. In some aspects, a subsequent CCA is performed based on an adjusted contention window associated with the same maximum burst length. In other aspects, a subsequent CCA is performed based on a contention window that is the same as the contention window for uplink transmission. In some aspects, a subsequent CCA is based on a contention window size that is the same as the contention window size for downlink transmission. In some aspects, a subsequent CCA is performed based on an adjusted contention window associated with the adjusted maximum burst length.

[0150] The apparatus 1502 includes an uplink grant component 1514 configured to send an uplink grant to the UE when the CCA is successful, for example, as described in conjunction with Fig.12 as described in block 1204 of FIG.

[0151] The device 1502 includes a contention window component 1516, which is configured to determine an adjusted contention window. In some aspects, the adjusted contention window is based on a feedback indication associated with a reference duration. For example, the adjusted contention window is based on ACK / NACK feedback associated with the reference duration. In some aspects, when the feedback indication associated with the reference duration is NACK, the adjusted contention window is increased. For example, when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window is increased. In other aspects, when the feedback indication associated with the reference duration is ACK, the adjusted contention window is reduced. For example, when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window is reduced.

[0152] The apparatus 1502 includes a pre-grant component 1518 configured to send a pre-grant for downlink transmission to the UE, for example, as described in conjunction with Fig.11 In some aspects, the pre-grant indicates a CCA length based on a contention window size associated with at least a burst length of the downlink transmission. In some aspects, the CCA length includes a backoff for the CCA for the UE within the contention window size.

[0153] Apparatus 1502 includes a transmitting component 1506 that transmits uplink communications to UE 1550. Transmitting component 1506 may be configured to transmit various messages to one or more external devices (e.g., including UE 1550) in accordance with the methods disclosed herein. The message / signal to be transmitted may be generated by one or more other components as discussed above, or the message / signal to be transmitted may be generated by transmitting component 1506 under the guidance / control of one or more other components discussed above. Thus, in various configurations, via transmitting component 1506, apparatus 1502 and / or one or more components therein transmit signals and / or other information (e.g., downlink data, control messages, and / or other signals) to an external device (such as UE 1550). In some aspects, transmitting component 1506 is configured to transmit downlink transmissions to the UE in response to an APG, for example, as in conjunction with Fig.11 In some aspects, the transmitting component 1506 is configured to transmit a subsequent downlink transmission to the UE after a subsequent CCA of the UE, for example, as described in conjunction with Fig.11In some aspects, the subsequent downlink transmission includes a maximum burst length that is the same as the maximum burst length for the downlink transmission. In some aspects, at least one of a subsequent CCA or a subsequent downlink transmission is based on an ACK / NACK feedback associated with a reference duration at the end of the burst length for the downlink transmission. In some aspects, the downlink transmission is a PDSCH and the reference duration is a last time slot of the PDSCH.

[0154] The apparatus 1502 includes a receiving component 1504 that receives uplink communications from the UE 1550. The receiving component 1504 may be configured to receive signals and / or other information from other devices including, for example, the UE 1550. The signals / information received by the receiving component 1504 may be provided to one or more components of the apparatus 1502 for further processing and use in performing various operations in accordance with the methods discussed above (including the processes of the flowcharts 1100 and 1200 described above). Thus, via the receiving component 1504, the apparatus 1502 and / or one or more components therein receive signals and / or other information (e.g., uplink data and / or other control signaling for the apparatus 1502) from the UE 1550, as discussed above and also discussed in more detail below. In some aspects, the receiving component 1504 is configured to receive an uplink transmission from the UE in response to an uplink grant, for example, as described in conjunction with Fig.12 In some aspects, the uplink transmission is a PUSCH. In some aspects, the reference duration is the last time slot of the PUSCH. In some aspects, the receiving component 1504 is configured to receive an acknowledgment of the pre-grant (APG) from the UE when the CCA based on the CCA length of the UE is successful, for example, as described in conjunction with Fig.11 As described in box 1104.

[0155] The device 1505 may include executing the above Fig.11 and 12 Each block in the flowchart of the algorithm has additional components. Therefore, the above components can be executed by Fig.11 and 12 Each block in the flowchart of the process / algorithm may be included in the apparatus, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0156] Fig.161 is a schematic diagram 1600 showing an example of a hardware implementation for an apparatus 1502' employing a processing system 1614. The processing system 1614 may be implemented using a bus architecture, generally represented by bus 1624. The bus 1624 may include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the processing system 1614. The bus 1624 connects together various circuits including one or more processors and / or hardware components (represented by processor 1620, components 1504, 1506, 1508, 1510, 1512, 1514, 1516, 1518, and computer readable medium / memory 1622). The bus 1624 may also connect various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described again.

[0157] The processing system 1614 may be coupled to a transceiver 1630. The transceiver 1630 is coupled to one or more antennas 1632. The transceiver 1630 provides a means for communicating with various other devices over a transmission medium. The transceiver 1630 receives signals from the one or more antennas 1632, extracts information from the received signals, and provides the extracted information to the processing system 1614 (specifically the receiving component 1504). In addition, the transceiver 1630 receives information from the processing system 1614 (specifically the transmitting component 1506) and generates signals to be applied to the one or more antennas 1632 based on the received information. The processing system 1614 includes a processor 1620 coupled to a computer-readable medium / memory 1622. The processor 1620 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1622. The software, when executed by the processor 1620, causes the processing system 1614 to perform the various functions described above for any particular device. The computer-readable medium / memory 1622 may also be used to store data manipulated by the processor 1620 when executing software. The processing system 1614 also includes at least one of the components 1504, 1506, 1508, 1510, 1512, 1514, 1516, 1518. The component may be a software component running in the processor 1620, located / stored in the computer-readable medium / memory 1622, one or more hardware components coupled to the processor 1620, or some combination thereof. The processing system 1614 may be a component of the UE 350 and may include at least one of the TX processor 368, the RX processor 356, and the controller / processor 359 and / or the memory 360.

[0158] In one configuration, an apparatus 1502 / 1502' for wireless communication includes: a unit for sending a first signal in an uplink (UL) resource to a first base station; a unit for receiving a second signal in a downlink (DL) resource concurrently with sending the first signal to the first base station, the received second signal including interference associated with the sent first signal; a unit for determining an interference level associated with the sent first signal received in the second signal; and a unit for sending information associated with the determined interference level to the first base station.

[0159] In another configuration, an apparatus 1502 / 1502' for wireless communication includes: a unit for performing a clear channel assessment (CCA) based on a contention window associated with at least a burst length for uplink transmission. The apparatus 1502 / 1502' also includes: a unit for sending an uplink grant to a user equipment (UE) when the CCA is successful. The apparatus 1502 / 1502' also includes: a unit for receiving an uplink transmission in response to the uplink grant from the UE.

[0160] The aforementioned means may be one or more of the aforementioned components of the apparatus 1502 and / or a processing system 1614 of the apparatus 1502' configured to perform the functions recited by the aforementioned means. As described above, the processing system 1614 may include the TX processor 368, the RX processor 356, and the controller / processor 359. Thus, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0161] The following aspects are merely illustrative and may be combined with other implementations or teachings described herein, but are not limited thereto.

[0162] Aspect 1 is a method for wireless communication at a user equipment (UE), comprising: receiving a pre-grant for downlink transmission from a base station, the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission; after receiving the pre-grant, performing CCA based on the CCA length; when the CCA is successful, sending an acknowledgment (APG) of the pre-grant to the base station; and receiving the downlink transmission in response to the APG from the base station.

[0163] In aspect 2, the method according to aspect 1 further includes: the CCA length includes a backoff within the contention window size for the UE to apply when performing the CCA.

[0164] In aspect 3, the method according to aspect 1 or aspect 2 also includes: sending an acknowledgement (ACK) / negative acknowledgement (NACK) feedback to the base station in response to the downlink transmission; and performing a subsequent CCA before receiving a subsequent downlink transmission from the base station; wherein at least one of the subsequent CCA or the subsequent downlink transmission is based on the ACK / NACK feedback associated with a reference duration at the end of the burst length used for the downlink transmission.

[0165] In aspect 4, the method according to any one of aspects 1-3 further includes: the downlink transmission is a physical downlink shared channel (PDSCH), and the reference duration is the last time slot of the PDSCH.

[0166] In aspect 5, the method according to any one of aspects 1-4 also includes: the subsequent downlink transmission includes a maximum burst length that is the same as the maximum burst length used for the downlink transmission; and the subsequent CCA is performed based on an adjusted contention window associated with the same maximum burst length, and the adjusted contention window is based on the ACK / NACK feedback associated with the reference duration.

[0167] In aspect 6, the method according to any one of aspects 1-5 also includes: when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window is increased, and wherein, when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window is reduced.

[0168] In aspect 7, the method according to any one of aspects 1-6 also includes: the subsequent downlink transmission includes an adjusted maximum burst length, and the adjusted maximum burst length is based on the ACK / NACK feedback associated with the reference duration; and wherein the subsequent CCA is performed based on a contention window size that is the same as the contention window size used for the downlink transmission.

[0169] In aspect 8, the method according to any one of aspects 1-7 also includes: when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length is reduced, and wherein, when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length is increased.

[0170] In aspect 9, the method according to any one of aspects 1-8 also includes: the subsequent downlink transmission includes an adjusted maximum burst length; the subsequent CCA is performed based on an adjusted contention window associated with the adjusted maximum burst length; and the adjusted maximum burst length and the adjusted contention window are based on the ACK / NACK feedback associated with the reference duration.

[0171] Aspect 10 is a device comprising: one or more processors; and one or more memories in electronic communication with the one or more processors, storing instructions executable by the one or more processors to cause a system or device to implement a method as in any of aspects 1 to 9.

[0172] Aspect 11 is a system or apparatus, comprising: a method for implementing any of aspects 1 to 9 or an apparatus for implementing any of aspects 1 to 9.

[0173] Aspect 12 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of aspects 1 to 9.

[0174] Aspect 13 is a method for performing wireless communications at a user equipment (UE), comprising: receiving an uplink grant from a base station after a clear channel assessment (CCA) of the base station; and sending an uplink transmission to the base station in response to the uplink grant; wherein the CCA is based on a contention window associated at least with a burst length used for the uplink transmission.

[0175] In aspect 14, the method according to aspect 13 also includes: receiving a feedback indication in response to the uplink transmission from the base station; and receiving another uplink grant for a subsequent uplink transmission from the base station after a subsequent CCA of the base station; wherein at least one of the subsequent CCA or the subsequent uplink transmission is based on a feedback indication associated with a reference duration at the end of the burst length used for the uplink transmission.

[0176] In aspect 15, the method according to aspect 13 or aspect 14 also includes: the uplink transmission is a physical uplink shared channel (PUSCH), wherein the reference duration is the last time slot of the PUSCH, and wherein the feedback indication is based on a new data indicator (NDI) in the other uplink grant for a hybrid automatic repeat request (HARQ) process.

[0177] In aspect 16, the method according to any one of aspects 1-15 also includes: the subsequent uplink transmission includes a maximum burst length that is the same as the maximum burst length used for the uplink transmission; and the subsequent CCA is based on an adjusted contention window associated with the same maximum burst length, and the adjusted contention window is based on the feedback indication associated with the reference duration.

[0178] In aspect 17, the method according to any one of aspects 1-16 also includes: when the feedback indication associated with the reference duration is NACK, the adjusted contention window is increased, and wherein, when the feedback indication associated with the reference duration is ACK, the adjusted contention window is reduced.

[0179] In aspect 18, the method according to any one of aspects 1-17 also includes: the subsequent uplink transmission includes an adjusted maximum burst length, and the adjusted maximum burst length is based on the feedback indication associated with the reference duration; and the subsequent CCA is based on a contention window that is the same as the contention window used for the uplink transmission.

[0180] In aspect 19, the method according to any one of aspects 1-18 also includes: when the feedback indication associated with the reference duration is NACK, the adjusted maximum burst length is reduced, and wherein, when the feedback indication associated with the reference duration is ACK, the adjusted maximum burst length is increased.

[0181] In aspect 20, the method according to any one of aspects 1-9 also includes: the subsequent uplink transmission includes an adjusted maximum burst length; the subsequent CCA is based on an adjusted contention window associated with the adjusted maximum burst length; and the adjusted maximum burst length and the adjusted contention window are based on the feedback indication associated with the reference duration.

[0182] Aspect 21 is a device comprising: one or more processors; and one or more memories in electronic communication with the one or more processors, storing instructions that can be executed by the one or more processors to enable the system or device to implement a method as in any of Aspects 1 to 20.

[0183] Aspect 22 is a system or apparatus, comprising: a method for implementing any of aspects 1 to 20 or an apparatus for implementing any of aspects 1 to 20.

[0184] Aspect 23 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of aspects 1 to 20.

[0185] Aspect 24 is a method for performing wireless communications at a base station, comprising: sending a pre-grant for downlink transmission to a user equipment (UE), the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission; when a CCA of the UE based on the CCA length is successful, receiving an acknowledgment (APG) of the pre-grant from the UE; and sending the downlink transmission to the UE in response to the APG.

[0186] In aspect 25, the method according to aspect 24 further comprises: the CCA length comprises a backoff for the CCA for the UE within the contention window size.

[0187] In aspect 26, the method according to aspect 24 or aspect 25 also includes: receiving an acknowledgement (ACK) / negative acknowledgement (NACK) feedback in response to the downlink transmission from the UE; and sending a subsequent downlink transmission to the UE after a subsequent CCA of the UE; wherein at least one of the subsequent CCA or the subsequent downlink transmission is based on the ACK / NACK feedback associated with a reference duration at the end of the burst length used for the downlink transmission.

[0188] In aspect 27, the method according to any one of aspects 24-26 further comprises: the downlink transmission is a physical downlink shared channel (PDSCH), and the reference duration is the last time slot of the PDSCH.

[0189] In aspect 28, the method according to any one of aspects 24-27 also includes: the subsequent downlink transmission includes a maximum burst length that is the same as the maximum burst length used for the downlink transmission; the subsequent CCA is based on an adjusted contention window associated with the same maximum burst length, and the adjusted contention window is based on the ACK / NACK feedback associated with the reference duration, when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window is increased, and when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window is reduced.

[0190] In aspect 29, the method according to any one of aspects 24-28 also includes: the subsequent downlink transmission includes an adjusted maximum burst length, and the adjusted maximum burst length is based on the ACK / NACK feedback associated with the reference duration; the subsequent CCA is based on a contention window size that is the same as the contention window size used for the downlink transmission, and when the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length is reduced, and when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length is increased.

[0191] In aspect 30, the method according to any one of aspects 24-29 also includes: the subsequent downlink transmission includes an adjusted maximum burst length; the subsequent CCA is based on an adjusted contention window associated with the adjusted maximum burst length; and the adjusted maximum burst length and the adjusted contention window are based on the ACK / NACK feedback associated with the reference duration.

[0192] Aspect 31 is a device comprising: one or more processors; and one or more memories in electronic communication with the one or more processors, storing instructions that can be executed by the one or more processors to enable the system or device to implement a method as in any of aspects 1 to 30.

[0193] Aspect 32 is a system or apparatus, comprising: a method for implementing any of aspects 1 to 30 or an apparatus for implementing any of aspects 1 to 30.

[0194] Aspect 23 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement the method as in any of aspects 1 to 30.

[0195] Aspect 34 is a method for wireless communication at a base station, comprising: performing a clear channel assessment (CCA) based on a contention window associated at least with a burst length for uplink transmission; sending an uplink grant to a user equipment (UE) when the CCA is successful; and receiving the uplink transmission from the UE in response to the uplink grant.

[0196] In aspect 35, the method according to aspect 34 also includes: sending a feedback indication to the UE in response to the uplink transmission; and performing a subsequent CCA before sending another uplink grant for a subsequent uplink transmission to the UE; wherein at least one of the subsequent CCA or the subsequent uplink transmission is based on the feedback indication associated with a reference duration at the end of the burst length used for the uplink transmission.

[0197] In aspect 36, the method according to aspect 34 or aspect 35 also includes: the uplink transmission is a physical uplink shared channel (PUSCH), wherein the reference duration is the last time slot of the PUSCH, and wherein the feedback indication is based on a new data indicator (NDI) in the other uplink grant for a hybrid automatic repeat request (HARQ) process.

[0198] In aspect 37, the method according to any one of aspects 34-36 also includes: the subsequent uplink transmission includes a maximum burst length that is the same as the maximum burst length used for the uplink transmission; the subsequent CCA is performed based on an adjusted contention window associated with the same maximum burst length, and the adjusted contention window is based on the feedback indication associated with the reference duration, when the feedback indication associated with the reference duration is NACK, the adjusted contention window is increased, and when the feedback indication associated with the reference duration is ACK, the adjusted contention window is reduced.

[0199] In aspect 38, the method according to any one of aspects 34-36 also includes: the subsequent uplink transmission includes an adjusted maximum burst length, and the adjusted maximum burst length is based on the feedback indication associated with the reference duration; the subsequent CCA is performed based on a contention window that is the same as the contention window used for the uplink transmission, and when the feedback indication associated with the reference duration is NACK, the adjusted maximum burst length is reduced, and when the feedback indication associated with the reference duration is ACK, the adjusted maximum burst length is increased.

[0200] In aspect 39, the method according to any one of aspects 34-38 also includes: the subsequent uplink transmission includes an adjusted maximum burst length; the subsequent CCA is performed based on an adjusted contention window associated with the adjusted maximum burst length; and the adjusted maximum burst length and the adjusted contention window are based on the feedback indication associated with the reference duration.

[0201] Aspect 40 is a device comprising: one or more processors; and one or more memories in electronic communication with the one or more processors, storing instructions that can be executed by the one or more processors to cause the system or device to implement a method as in any of aspects 1 to 39.

[0202] Aspect 41 is a system or apparatus, comprising: a method for implementing any of aspects 1 to 39 or an apparatus for implementing any of aspects 1 to 39.

[0203] Aspect 42 is a non-transitory computer-readable medium storing instructions executable by one or more processors to cause the one or more processors to implement a method as in any of aspects 1 to 39.

[0204] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is an illustration of an exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart can be rearranged based on design preferences. In addition, some blocks can be merged or omitted. The attached method claims provide the elements of each block in an exemplary order and are not meant to be limited to the specific order or hierarchy provided.

[0205] The foregoing description is provided so that any person skilled in the art can implement the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the various aspects shown herein, but are given the full scope consistent with the textual claims, wherein, unless explicitly stated, the elements mentioned in the singular form are not intended to mean "one and only one", but "one or more". The word "exemplary" used herein means "used as an example, instance or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred to other aspects or having advantages over other aspects. Unless otherwise explicitly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B or C", "one or more of A, B or C", "at least one of A, B and C", "one or more of A, B and C", and "A, B, C or any combination thereof" include any combination of A, B and / or C, and may include multiple A, multiple B or multiple C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B and C," "one or more of A, B and C," and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members or several members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure are expressly incorporated herein by reference, and are intended to be included by the claims, and these structural and functional equivalents are known or will later become known to those of ordinary skill in the art. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly recorded in the claims. The words "module," "mechanism," "element," "device," and the like may not be a substitute for the word "unit." Thus, no claim element is to be interpreted as a unit plus function unless the element is explicitly recorded using the phrase "unit for..."

Claims

1. A method for wireless communication at a user equipment (UE), comprising: receiving a pre-grant for a downlink transmission from a base station, the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission; After receiving the pre-grant, performing a CCA based on the CCA length; When the CCA is successful, sending an acknowledgment (APG) of the pre-grant to the base station; as well as The downlink transmission is received from the base station in response to the APG.

2. The method according to claim 1, wherein: The CCA length includes a backoff within the contention window size for the UE to apply when performing the CCA.

3. The method according to claim 1, further comprising: sending an acknowledgement (ACK) / negative acknowledgement (NACK) feedback to the base station in response to the downlink transmission; as well as performing a subsequent CCA prior to receiving a subsequent downlink transmission from the base station, Therein, at least one of the subsequent CCA or the subsequent downlink transmission is based on the ACK / NACK feedback associated with a reference duration at an end of the burst length for the downlink transmission.

4. The method according to claim 3, wherein: The downlink transmission is a Physical Downlink Shared Channel (PDSCH), and the reference duration is a last slot of the PDSCH.

5. The method according to claim 3, wherein: The subsequent downlink transmission comprises a maximum burst length that is the same as the maximum burst length for the downlink transmission, and The subsequent CCAs are performed based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on the ACK / NACK feedback associated with the reference duration.

6. The method according to claim 5, wherein: When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window is increased, and wherein when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window is decreased.

7. The method according to claim 3, wherein: The subsequent downlink transmission includes an adjusted maximum burst length, the adjusted maximum burst length being based on the ACK / NACK feedback associated with the reference duration, and The subsequent CCA is performed based on a contention window size that is the same as the contention window size used for the downlink transmission.

8. The method according to claim 7, wherein: When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length is decreased, and wherein when the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length is increased.

9. The method according to claim 3, wherein: the subsequent downlink transmission comprising the adjusted maximum burst length, The subsequent CCA is performed based on the adjusted contention window associated with the adjusted maximum burst length, and The adjusted maximum burst length and the adjusted contention window are based on the ACK / NACK feedback associated with the reference duration.

10. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: at least one processor; as well as A memory coupled to the at least one processor storing computer executable code that, when executed by the at least one processor, causes the apparatus to: receiving an uplink grant from a base station following a clear channel assessment (CCA) of the base station; as well as sending an uplink transmission to the base station in response to the uplink grant, Therein, the CCA is based on a contention window associated with at least a burst length for the uplink transmission.

11. The apparatus according to claim 10, further comprising: receiving, from the base station, a feedback indication in response to the uplink transmission; as well as receiving, after a subsequent CCA by the base station, another uplink grant for a subsequent uplink transmission from the base station, Therein, at least one of the subsequent CCA or the subsequent uplink transmission is based on the feedback indication associated with a reference duration at an end of the burst length for the uplink transmission.

12. The device according to claim 11, wherein: The uplink transmission is a physical uplink shared channel (PUSCH), wherein the reference duration is a last time slot of the PUSCH, and wherein the feedback indication is based on a new data indicator (NDI) in the other uplink grant for a hybrid automatic repeat request (HARQ) process.

13. The device according to claim 11, wherein: The subsequent uplink transmission includes a maximum burst length that is the same as the maximum burst length used for the uplink transmission, and The subsequent CCA is based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on the feedback indication associated with the reference duration.

14. The device according to claim 13, wherein: When the feedback associated with the reference duration indicates a NACK, the adjusted contention window is increased, and wherein when the feedback associated with the reference duration indicates an ACK, the adjusted contention window is decreased.

15. The device according to claim 11, wherein: The subsequent uplink transmission includes an adjusted maximum burst length, the adjusted maximum burst length being based on the feedback indication associated with the reference duration, and The subsequent CCA is based on a contention window that is the same as the contention window used for the uplink transmission.

16. The device according to claim 15, wherein: When the feedback associated with the reference duration indicates a NACK, the adjusted maximum burst length is decreased, and wherein when the feedback associated with the reference duration indicates an ACK, the adjusted maximum burst length is increased.

17. The device according to claim 11, wherein: the subsequent uplink transmission comprising the adjusted maximum burst length, The subsequent CCA is based on the adjusted contention window associated with the adjusted maximum burst length, and The adjusted maximum burst length and the adjusted contention window are based on the feedback indication associated with the reference duration.

18. A method for wireless communication at a base station, comprising: sending a pre-grant for a downlink transmission to a user equipment (UE), the pre-grant indicating a clear channel assessment (CCA) length based on a contention window size associated with at least a burst length of the downlink transmission; When the CCA of the UE based on the CCA length is successful, receiving an acknowledgment (APG) of the pre-grant from the UE; and The downlink transmission is sent to the UE in response to the APG.

19. The method according to claim 18, wherein: The CCA length includes a backoff for the CCA for the UE within the contention window size.

20. The method of claim 18, further comprising: receiving an acknowledgement (ACK) / negative acknowledgement (NACK) feedback from the UE in response to the downlink transmission; as well as sending a subsequent downlink transmission to the UE after a subsequent CCA of the UE; Therein, at least one of the subsequent CCA or the subsequent downlink transmission is based on the ACK / NACK feedback associated with a reference duration at an end of the burst length for the downlink transmission.

21. The method according to claim 20, wherein: The downlink transmission is a Physical Downlink Shared Channel (PDSCH), and the reference duration is a last slot of the PDSCH.

22. The method of claim 20, wherein: the subsequent downlink transmission comprising a maximum burst length that is the same as the maximum burst length used for the downlink transmission, the subsequent CCA is based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window is based on the ACK / NACK feedback associated with the reference duration, When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted contention window is increased, and When the ACK / NACK feedback associated with the reference duration is ACK, the adjusted contention window is reduced.

23. The method of claim 20, wherein: the subsequent downlink transmission comprising an adjusted maximum burst length, the adjusted maximum burst length being based on the ACK / NACK feedback associated with the reference duration, The subsequent CCA is based on a contention window size that is the same as the contention window size used for the downlink transmission, When the ACK / NACK feedback associated with the reference duration is NACK, the adjusted maximum burst length is reduced, and When the ACK / NACK feedback associated with the reference duration is ACK, the adjusted maximum burst length is increased.

24. The method of claim 20, wherein: the subsequent downlink transmission comprising the adjusted maximum burst length, The subsequent CCA is based on the adjusted contention window associated with the adjusted maximum burst length, and The adjusted maximum burst length and the adjusted contention window are based on the ACK / NACK feedback associated with the reference duration.

25. An apparatus for wireless communication at a base station, the apparatus comprising: at least one processor; as well as A memory coupled to the at least one processor storing computer executable code that, when executed by the at least one processor, causes the apparatus to: performing a clear channel assessment (CCA) based on a contention window associated with at least a burst length for uplink transmission; When the CCA is successful, sending an uplink grant to a user equipment (UE); as well as The uplink transmission is received from the UE in response to the uplink grant.

26. The device according to claim 25, wherein The code also causes the device to: sending a feedback indication to the UE in response to the uplink transmission; and performing a subsequent CCA before sending another uplink grant to the UE for a subsequent uplink transmission, Therein, at least one of the subsequent CCA or the subsequent uplink transmission is based on the feedback indication associated with a reference duration at an end of the burst length for the uplink transmission.

27. The device according to claim 26, wherein: The uplink transmission is a physical uplink shared channel (PUSCH), wherein the reference duration is a last time slot of the PUSCH, and wherein the feedback indication is based on a new data indicator (NDI) in the other uplink grant for a hybrid automatic repeat request (HARQ) process.

28. The apparatus of claim 26, wherein: the subsequent uplink transmission comprising a maximum burst length that is the same as the maximum burst length used for the uplink transmission, the subsequent CCA is performed based on an adjusted contention window associated with the same maximum burst length, the adjusted contention window being based on the feedback indication associated with the reference duration, When the feedback indication associated with the reference duration is NACK, the adjusted contention window is increased, and When the feedback associated with the reference duration indicates an ACK, the adjusted contention window is reduced.

29. The apparatus of claim 26, wherein: the subsequent uplink transmission comprising an adjusted maximum burst length, the adjusted maximum burst length being based on the feedback indication associated with the reference duration, The subsequent CCA is performed based on a contention window that is the same as the contention window used for the uplink transmission, When the feedback indication associated with the reference duration is NACK, the adjusted maximum burst length is reduced, and When the feedback indication associated with the reference duration is ACK, the adjusted maximum burst length is increased.

30. The apparatus of claim 26, wherein: the subsequent uplink transmission comprising the adjusted maximum burst length, The subsequent CCA is performed based on the adjusted contention window associated with the adjusted maximum burst length, and The adjusted maximum burst length and the adjusted contention window are based on the feedback indication associated with the reference duration.

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