Enhanced Licensed Assisted Access Uplink Channel Access

Abstract

The present disclosure relates to enhanced licensed assisted access uplink channel access. A solution to the delay problem of channel acquisition by a UE in a contention-based shared radio frequency spectrum band is disclosed. For example, if the eNB is aware of a recent or ongoing downlink transmission on a frequency used by the UE for uplink transmission, the eNB can instruct the UE to skip the execution of an LBT on that frequency or to perform a type of LBT that is shorter in duration than a full CCA. One way for the eNB to instruct the UE in this manner is to set an indicator in an uplink grant sent to the UE on another frequency. In addition, to avoid truncation of uplink transmission opportunities, the eNB can notify the UE that the uplink grant is valid for more than one starting point.

Description

[0001] This application is a divisional application of the Chinese patent application with application number 201680064376.6, filed on October 28, 2016, and invention name “Enhanced Licensed Assisted Access Uplink Channel Access”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to co-pending U.S. Provisional Patent Application No. 62 / 252,278, filed on November 6, 2015, entitled “ENHANCED LICENSED ASSISTED ACCESS UPLINK CHANNEL ACCESS,” and U.S. Non-Provisional Patent Application No. 15 / 336,509, filed on October 27, 2016, entitled “ENHANCED LICENSED ASSISTED ACCESS UPLINK CHANNEL ACCESS,” both of which are expressly incorporated herein by reference in their entirety.

[0004] background

[0005] field

[0006] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly to licensed assisted access (LAA) uplink channel access. Background Art

[0007] Wireless communication systems are widely deployed to provide various types of communication content (such as voice, video, packet data, messaging, broadcast, etc.). These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems.

[0008] As an example, a wireless multiple access communication system may include several base stations, each of which simultaneously supports communication for multiple communication devices, or user equipment (UE). The base station may communicate with the UE on a downlink channel (e.g., for transmission from the base station to the UE) and an uplink channel (e.g., for transmission from the UE to the base station).

[0009] Some communication modes may enable communication between a base station and a UE on a contention-based shared RF spectrum band or on a different RF spectrum band (e.g., a licensed RF spectrum band or an unlicensed RF spectrum band) of a cellular network. As data traffic in cellular networks using licensed RF spectrum bands continues to increase, offloading at least some of the data traffic to unlicensed RF spectrum bands may provide cellular operators with an opportunity to enhance data transmission capacity. Unlicensed RF spectrum bands may also provide services in areas where access to licensed RF spectrum bands is unavailable.

[0010] Before obtaining access to a contention-based shared radio frequency spectrum band and communicating on the contention-based shared radio frequency spectrum band, a base station or a UE may perform a listen-before-talk (LBT) procedure to compete for access to the shared radio frequency spectrum band. The LBT procedure may include performing a clear channel assessment (CCA) procedure to determine whether a channel of the contention-based shared radio frequency spectrum band is available. When it is determined that a channel of the contention-based shared radio frequency spectrum band is available, a channel reservation signal (such as a channel usage beacon signal (CUBS)) may be transmitted to reserve the channel.

[0011] Overview

[0012] According to various aspects disclosed herein, the present disclosure is directed to solving problems associated with delays in channel acquisition by a UE in a contention-based shared radio frequency spectrum band. For example, if an evolved Node B (eNB) has recently or is transmitting on a frequency used by the UE for uplink transmission, and / or if another base station or remote radio head in a CoMP set has already done so, the eNB may instruct the UE to skip the execution of an LBT on that frequency or to perform a type of LBT that is shorter in duration than a full CCA. One way for the eNB to instruct the UE in this manner is to set an indicator in an uplink grant sent to the UE on another frequency. Additionally, in order to avoid truncation of an uplink transmission opportunity (TXOP) due to the UE's failure to acquire a frequency in time to transmit at a starting point on that frequency, the eNB may notify the UE that the uplink grant is valid for more than one starting point.

[0013] In one aspect, a wireless communication method includes determining, by an evolved Node B (eNB), a type of listen-before-talk (LBT) indication to be set in an uplink (UL) grant transmitted on a first frequency (F1) to allocate uplink resources on a second frequency (F2) for a user equipment (UE). The method additionally includes setting, by the eNB, the LBT indication in the UL grant to correspond to a condition associated with a potential downlink transmission on F2, and transmitting, by the eNB, the UL grant to the UE at a time T.

[0014] In another aspect, a wireless communication apparatus has means for determining, by an evolved Node B (eNB), a type of listen-before-talk (LBT) indication to be set in an uplink (UL) grant transmitted on a first frequency (F1) in order to allocate uplink resources on a second frequency (F2) for a user equipment (UE). The apparatus also has means for setting, by the eNB, the LBT indication in the UL grant to correspond to a condition associated with a potential downlink transmission on F2, and means for transmitting, by the eNB, the UL grant to the UE at a time T.

[0015] In another aspect, a wireless communication apparatus includes at least one computer processor configured to determine, by an evolved Node B (eNB), a type of listen-before-talk (LBT) indication to be set in an uplink (UL) grant transmitted on a first frequency (F1) in order to allocate uplink resources on a second frequency (F2) for a user equipment (UE). The processor is also configured to set, by the eNB, the LBT indication in the UL grant to correspond to a condition associated with a potential downlink transmission on F2, and to transmit, by the eNB, the UL grant to the UE at a time T. The apparatus further has at least one memory coupled to the at least one computer processor.

[0016] In another aspect, a computer program stored on a non-transitory computer-readable medium includes program code for causing at least one computer to determine, by an evolved Node B (eNB), a type of listen-before-talk (LBT) indication to be set in an uplink (UL) grant transmitted on a first frequency (F1) in order to allocate uplink resources on a second frequency (F2) for a user equipment (UE). The program code also causes the at least one computer to set, by the eNB, the LBT indication in the UL grant to correspond to a condition associated with a potential downlink transmission on F2, and to transmit, by the eNB, the UL grant to the UE at a time T.

[0017] In another aspect, a wireless communication method includes receiving, by a user equipment (UE) on a first frequency (F1), an uplink (UL) grant transmitted by an evolved Node B (eNB), wherein the UL grant allocates uplink resources on a second frequency (F2) for the UE. The method additionally includes determining a type of a listen-before-talk (LBT) indication in the UL grant, accessing F2 based on the determined type of the LBT indication, and performing an UL transmission on F2 based on the UL grant.

[0018] In another aspect, a wireless communication apparatus has means for receiving, by a user equipment (UE) on a first frequency (F1), an uplink (UL) grant transmitted by an evolved Node B (eNB), wherein the UL grant allocates uplink resources on a second frequency (F2) for the UE. The apparatus also has means for determining a type of a listen-before-talk (LBT) indication in the UL grant, means for accessing F2 based on the determined type of the LBT indication, and means for performing an UL transmission on F2 based on the UL grant.

[0019] In another aspect, a wireless communication apparatus has at least one processor configured to receive, by a user equipment (UE) on a first frequency (F1), an uplink (UL) grant transmitted by an evolved Node B (eNB), wherein the UL grant allocates uplink resources on a second frequency (F2) for the UE. The at least one processor is further configured to determine a type of a listen-before-talk (LBT) indication in the UL grant, access F2 based on the determined type of the LBT indication, and perform UL transmission on F2 based on the UL grant. The apparatus further has at least one memory coupled to the at least one processor.

[0020] In another aspect, a computer program stored on a non-transitory computer readable medium includes program code for causing at least one computer to receive, by a user equipment (UE) on a first frequency (F1), an uplink (UL) grant transmitted by an evolved Node B (eNB), wherein the UL grant allocates uplink resources on a second frequency (F2) for the UE. The program code also causes the at least one computer to determine a type of a listen-before-talk (LBT) indication in the UL grant, access F2 based on the determined type of the LBT indication, and perform UL transmission on F2 based on the UL grant.

[0021] In another aspect, a wireless communication method includes indicating, by an evolved Node B (eNB) to a user equipment (UE), that an uplink (UL) grant is valid for two or more starting positions, the two or more starting positions including at least a first starting position and a second starting position. The method additionally includes transmitting, by the eNB, the UL grant to the UE, and attempting, by the eNB, to receive an UL transmission from the UE at the first starting position. The method also includes determining, by the eNB, that the attempt to receive the UL transmission at the first starting position was unsuccessful. The method further includes attempting, by the eNB and in response to determining that the attempt to receive the UL transmission at the first starting position was unsuccessful, to receive an UL transmission from the UE at a second starting position.

[0022] On the other hand, a wireless communication equipment has a device for indicating to a user equipment (UE) by an evolved Node B (eNB) that an uplink (UL) grant is valid for two or more starting positions, the two or more starting positions including at least a first starting position and a second starting position. The equipment additionally has a device for transmitting the UL grant to the UE by the eNB, and a device for attempting to receive an UL transmission from the UE at the first starting position by the eNB. The equipment also has a device for determining by the eNB that the attempt to receive the UL transmission at the first starting position was unsuccessful. The equipment further has a device for attempting to receive the UL transmission from the UE at the second starting position by the eNB and in response to determining that the attempt to receive the UL transmission at the first starting position was unsuccessful.

[0023] In another aspect, a wireless communication device has at least one processor configured to indicate, by an evolved Node B (eNB) to a user equipment (UE), that an uplink (UL) grant is valid for two or more starting positions, the two or more starting positions including at least a first starting position and a second starting position. The processor is additionally configured to transmit, by the eNB, the UL grant to the UE, and to attempt, by the eNB, to receive an UL transmission from the UE at the first starting position. The at least one processor is also configured to determine, by the eNB, that an attempt to receive an UL transmission at the first starting position was unsuccessful. The at least one processor is further configured to attempt, by the eNB and in response to determining that an attempt to receive an UL transmission at the first starting position was unsuccessful, to receive an UL transmission from the UE at a second starting position. The device further has at least one memory coupled to the at least one processor.

[0024] In another aspect, a computer program stored on a non-transitory computer-readable medium includes program code for causing at least one computer to perform the following operations: indicating, by an evolved Node B (eNB) to a user equipment (UE), that an uplink (UL) grant is valid for two or more starting positions, the two or more starting positions including at least a first starting position and a second starting position. The program code additionally causes the at least one computer to transmit, by the eNB, the UL grant to the UE, and to attempt, by the eNB, to receive an UL transmission from the UE at the first starting position. The program code also causes the at least one computer to determine, by the eNB, that an attempt to receive an UL transmission at the first starting position was unsuccessful. The program code further causes the at least one computer to attempt, by the eNB and in response to determining that an attempt to receive an UL transmission at the first starting position was unsuccessful, to receive an UL transmission from the UE at the second starting position.

[0025] In another aspect, a wireless communication method includes receiving, by a user equipment (UE) from an evolved Node B (eNB), an uplink (UL) grant, and receiving, by the UE from the eNB, an indication that the UL grant is valid for two or more starting positions, the two or more starting positions including a first starting position and a second starting position. The method additionally includes attempting, by the UE, to acquire a channel in time to perform an UL transmission using the first starting position, and determining, by the UE, that the attempt to acquire the channel in time to perform an UL transmission using the first starting position was unsuccessful. The method also includes attempting, by the UE and in response to determining that the attempt to acquire the channel in time to perform an UL transmission using the first starting position was unsuccessful, to acquire the channel in time to perform an UL transmission using the second starting position.

[0026] In another aspect, a wireless communication apparatus has means for receiving an uplink (UL) grant by a user equipment (UE) from an evolved Node B (eNB), and means for receiving an indication by the UE from the eNB that the UL grant is valid for two or more starting positions, the two or more starting positions including a first starting position and a second starting position. The apparatus additionally has means for the UE to attempt to acquire a channel in time to perform an UL transmission using the first starting position, and means for determining by the UE that the attempt to acquire a channel in time to perform an UL transmission using the first starting position was unsuccessful. The apparatus further has means for the UE and in response to determining that the attempt to acquire a channel in time to perform an UL transmission using the first starting position was unsuccessful, to attempt to acquire a channel in time to perform an UL transmission using the second starting position.

[0027] In another aspect, a wireless communication apparatus has at least one processor configured to receive, by a user equipment (UE) from an evolved Node B (eNB), an uplink (UL) grant, and to receive, by the UE from the eNB, an indication that the UL grant is valid for two or more starting positions, the two or more starting positions including a first starting position and a second starting position. The at least one processor is additionally configured to attempt, by the UE, to acquire a channel in time to perform an UL transmission using the first starting position, and to determine, by the UE, that the attempt to acquire the channel in time to perform an UL transmission using the first starting position was unsuccessful. The at least one processor is also configured to attempt, by the UE and in response to determining that the attempt to acquire the channel in time to perform an UL transmission using the first starting position was unsuccessful, to acquire the channel in time to perform an UL transmission using the second starting position.

[0028] In another aspect, a computer program stored on a non-transitory computer-readable medium includes program code for causing at least one computer to perform the following operations: receiving, by a user equipment (UE) from an evolved Node B (eNB), an uplink (UL) grant, and receiving, by the UE from the eNB, an indication that the UL grant is valid for two or more starting positions, the two or more starting positions including a first starting position and a second starting position. The program code additionally causes the at least one computer to attempt, by the UE, to acquire a channel in time to perform an UL transmission using the first starting position, and to determine, by the UE, that the attempt to acquire a channel in time to perform an UL transmission using the first starting position was unsuccessful. The program code also causes the at least one computer to attempt, by the UE and in response to determining that the attempt to acquire a channel in time to perform an UL transmission using the first starting position was unsuccessful, to acquire a channel in time to perform an UL transmission using the second starting position.

[0029] The foregoing has broadly outlined the features and technical advantages of examples according to the present disclosure in an effort to make the following detailed description better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples can be easily used as a basis for modifying or designing other structures for implementing the same purpose as the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, both in terms of their organization and method of operation, and the associated advantages will be better understood by considering the following description in conjunction with the accompanying drawings. Each of the accompanying drawings is provided for illustration and description purposes and does not define limitations on the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] A further understanding of the nature and advantages of the present disclosure may be obtained by reference to the following drawings. In the drawings, similar components or features may have the same reference numeral. In addition, individual components of the same type may be distinguished by following the reference numeral with a dash and a second reference numeral that distinguishes between similar components. If only the first reference numeral is used in the specification, the description may apply to any of the similar components having the same first reference numeral regardless of the second reference numeral.

[0031] Figure 1 A diagram illustrating an example of a wireless communication system in accordance with various embodiments is shown.

[0032] Figure 2A A diagram illustrating an example of a deployment scenario for using LTE in unlicensed spectrum according to various embodiments is shown.

[0033] Figure 2B A diagram illustrating another example of a deployment scenario for using LTE in unlicensed spectrum according to various embodiments is shown.

[0034] Figure 3 An illustration of an example of wireless communications over an unlicensed radio frequency spectrum band in accordance with various aspects of the present disclosure.

[0035] Figure 4 An illustration of an example of a CCA procedure performed by a transmitting device when competing for access to a contention-based shared radio frequency spectrum band in accordance with various aspects of the present disclosure.

[0036] Figure 5 An illustration of an example of an extended CCA (ECCA) procedure performed by a transmitting device when competing for access to a contention-based shared radio frequency spectrum band in accordance with various aspects of the present disclosure.

[0037] Figure 6 A block diagram showing a design of a base station / eNB and a UE, which may be Figure 1 One of the base stations / eNBs and one of the UEs in the.

[0038] Figure 7 is a block diagram illustrating example blocks executed to implement aspects of the present disclosure.

[0039] Figure 8 is a block diagram illustrating example blocks executed to implement aspects of the present disclosure.

[0040] Fig. 9A is a block diagram illustrating example blocks executed to implement aspects of the present disclosure.

[0041] Fig. 9B is a block diagram illustrating example blocks executed to implement aspects of the present disclosure.

[0042] Fig. 10A is a block diagram illustrating a UE configured according to one aspect of the present disclosure.

[0043] Fig. 10B is a block diagram illustrating an eNB configured according to one aspect of the present disclosure. Detailed Description

[0044] 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 limit the scope of the present disclosure. Instead, this detailed description includes specific details in order to provide a thorough understanding of the subject matter of the present invention. It will be apparent to those skilled in the art that these specific details are not required in every case, and in some instances, for clarity of description, well-known structures and components are shown in block diagram form.

[0045] Techniques are described in which unlicensed radio frequency spectrum bands are used for at least a portion of contention-based communications on a wireless communication system. In some examples, contention-based shared radio frequency spectrum bands may be used for Long Term Evolution (LTE) communications or Advanced LTE (LTE-A) communications. Contention-based radio frequency spectrum bands may be used in combination with non-contention licensed radio frequency spectrum bands or independently. In some examples, contention-based radio frequency spectrum bands may be radio frequency spectrum bands that devices may also need to contend for access to because the radio frequency spectrum bands are at least partially available for unlicensed uses (such as WiFi uses).

[0046] As data traffic in cellular networks using licensed RF spectrum bands increases, offloading at least some of the data traffic to a contention-based shared RF spectrum band (such as in an unlicensed band) may provide cellular operators (e.g., a public land mobile network (PLMN) or an operator of a coordinated set of base stations that defines a cellular network (such as an LTE / LTE-A network)) with the opportunity for enhanced data transmission capacity. As described above, prior to communicating on a contention-based shared RF spectrum band (such as an unlicensed spectrum), a device may perform an LBT procedure to gain access to the shared RF spectrum band. Such an LBT procedure may include performing a CCA procedure (or an extended CCA procedure) to determine whether a channel of the unlicensed RF spectrum band is available. When it is determined that the channel of the contention-based RF spectrum band is available, a channel reservation signal (e.g., CUBS) may be transmitted to reserve the channel. When it is determined that the channel is not available, the CCA procedure (or an extended CCA procedure) may be performed again on the channel at a later time.

[0047] When a base station and / or UE includes multiple antenna ports capable of transmitting on a contention-based shared radio frequency spectrum band, transmissions from different antenna ports may interfere with each other due to correlation between the transmitted signals. For a channel reservation signal used to reserve a channel of a contention-based shared radio frequency spectrum band, reducing interference caused by correlation between the transmitted signals may be important for providing good detection capabilities for reserving the channel and preventing false detections that would unnecessarily reserve the channel and prevent other devices from using the channel. In order to reduce such interference caused by cross-correlation of signals from different antennas or autocorrelation of signals from a single antenna, the base station or UE may generate the sequence of channel reservation signals based at least in part on an antenna port identifier associated with the antenna port that transmits the sequence. In this way, the correlation of the channel reservation signal can be reduced, thereby improving the detection capability of the signal transmission, resulting in more efficient and accurate reservation of the channel of the contention-based shared radio frequency spectrum band.

[0048] In other words, for the channel reservation signal used to reserve a channel in an unlicensed radio frequency spectrum band, the channel reservation signal should be configured with good detection capabilities to reduce false alarms so that the channel reservation can be easily detected by other devices attempting to access the shared radio frequency spectrum band. Therefore, the channel reservation signal sequence should have good autocorrelation properties and good cross-correlation properties with sequences from neighboring base stations. For example, in a contention-based shared radio frequency spectrum band, the primary synchronization signal (PSS), secondary synchronization signal (SSS) and / or channel state information reference signal (CSI-RS) may not have good autocorrelation properties or good cross-correlation properties between different base stations. Therefore, the channel reservation signal sequence should be configured at least in part based on the antenna port identifier to provide good autocorrelation and cross-correlation properties.

[0049] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements discussed without departing from the scope of the present disclosure. Various examples may appropriately omit, substitute, or add various procedures or components. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to some examples may be combined in other examples.

[0050] Figure 1 1 is an illustration of an example wireless communication system 100 according to various aspects of the present disclosure. The wireless communication system 100 may include a base station 105, a UE 115, and a core network 130. The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The base station 105 may interface with the core network 130 via a backhaul link 132 (e.g., S1, etc.) and may perform radio configuration and scheduling for communications with the UE 115, or may operate under the control of a base station controller (not shown). In various examples, the base station 105 may communicate with other base stations 105 directly or indirectly (e.g., through the core network 130) on a backhaul link 134 (e.g., X2, etc.), which may be a wired or wireless communication link.

[0051] The base station 105 may communicate wirelessly with the UE 115 via one or more base station antennas. Each of these base station 105 sites may provide communication coverage for a respective geographic coverage area 110. In some examples, the base station 105 may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a Home Node B, a Home Evolved Node B, or some other suitable term. The geographic coverage area 110 of the base station 105 may be divided into sectors (not shown) that constitute a portion of the coverage area. The wireless communication system 100 may include different types of base stations 105 (e.g., macro base stations or small cell base stations). There may be overlapping geographic coverage areas 110 of different technologies.

[0052] In some examples, the wireless communication system 100 may include an LTE / LTE-A network. In an LTE / LTE-A network, the term evolved Node B (eNB) may be used to describe the base station 105, and the term UE may be used to describe the UE 115. The wireless communication system 100 may be a heterogeneous LTE / LTE-A network in which different types of eNBs provide coverage for various geographic regions. For example, each eNB or base station 105 may provide communication coverage for a macro cell, a small cell, or other types of cells. Depending on the context, the term "cell" is a 3GPP term that may be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., a sector, etc.) of a carrier or base station.

[0053] A macro cell may cover a relatively large geographic area (e.g., an area with a radius of several kilometers) and may allow unrestricted access by UEs with service subscriptions to a network provider. Compared to a macro cell, a small cell may be a low-power base station that may operate in the same or different (e.g., licensed, unlicensed, etc.) radio frequency spectrum band as a macro cell. According to various examples, a small cell may include a pico cell, a femto cell, and a micro cell. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions to a network provider. A femto cell may also cover a relatively small geographic area (e.g., a residence) and may provide access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in the residence, etc.) with restrictions. An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or more (eg, two, three, four, etc.) cells (eg, component carriers).

[0054] The wireless communication system 100 may support synchronous or asynchronous operation. For synchronous operation, each base station may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, each base station may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operation.

[0055] A communication network that can accommodate some of the various disclosed examples can be a packet-based network that operates according to a layered protocol stack. In the user plane, the communication of the bearer or packet data convergence protocol (PDCP) layer can be IP-based. The radio link control (RLC) layer can perform packet segmentation and reassembly to communicate on a logical channel. The media access control (MAC) layer can perform priority handling and multiplex logical channels into transport channels. The MAC layer can also use hybrid ARQ (HARQ) to provide retransmission of the MAC layer, thereby improving link efficiency. In the control plane, the radio resource control (RRC) protocol layer can provide the establishment, configuration and maintenance of the RRC connection of the radio bearer supporting user plane data between the UE 115 and the base station 105 or the core network 130. In the physical (PHY) layer, the transport channel can be mapped to the physical channel.

[0056] UE 115 may be dispersed throughout the wireless communication system 100, and each UE 115 may be stationary or mobile. UE 115 may also include or be referred to by those skilled in the art as 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 term. UE 115 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, and the like. UE may be able to communicate with various types of base stations and network equipment (including macro eNBs, small cell eNBs, relay base stations, and the like).

[0057] The communication link 125 shown in the wireless communication system 100 may include a downlink (DL) transmission from the base station 105 to the UE 115, or an uplink (UL) transmission from the UE 115 to the base station 105. Downlink transmissions may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions. In some examples, the UL transmission may include transmission of uplink control information, which may be transmitted on an uplink control channel (e.g., a physical uplink control channel (PUCCH) or an enhanced PUCCH (ePUCCH)). The uplink control information may include, for example, an acknowledgement or negative acknowledgement of a downlink transmission, or channel state information. The uplink transmission may also include transmission of data, which may be transmitted on a physical uplink shared channel (PUSCH) or an enhanced PUSCH (ePUSCH). The uplink transmission may also include a sounding reference signal (SRS) or an enhanced SRS (eSRS), a physical random access channel (PRACH) or an enhanced PRACH (ePRACH) (e.g., in reference to Figure 2A and 2B ), or a Scheduling Request (SR) or an Enhanced SR (eSR) (e.g., in the dual connectivity mode or standalone mode described in Figure 2A and 2B References to PUCCH, PUSCH, PRACH, SRS, or SR in this disclosure are assumed to inherently include references to the corresponding ePUCCH, ePUSCH, ePRACH, eSRS, or eSR.

[0058] In some examples, each communication link 125 may include one or more carriers, where each carrier may be a signal consisting of multiple subcarriers modulated according to the various radio technologies described above (e.g., waveform signals of different frequencies). Each modulated signal may be sent on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. The communication link 125 may transmit bidirectional communications using frequency domain duplex (FDD) operation (e.g., using paired spectrum resources) or time domain duplex (TDD) operation (e.g., using unpaired spectrum resources). A frame structure for FDD operation (e.g., frame structure type 1) and a frame structure for TDD operation (e.g., frame structure type 2) may be defined.

[0059] In some aspects of the wireless communication system 100, the base station 105 or the UE 115 may include multiple antennas to employ an antenna diversity scheme to improve the communication quality and reliability between the base station 105 and the UE 115. Additionally or alternatively, the base station 105 or the UE 115 may employ multiple-input multiple-output (MIMO) technology, which may utilize a multipath environment to transmit multiple spatial layers carrying the same or different encoded data.

[0060] The wireless communication system 100 may support operation on multiple cells or carriers, a feature that may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC), layer, channel, etc. The terms "carrier," "component carrier," "cell," and "channel" are used interchangeably herein. A UE 115 may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. Carrier aggregation may be used with both FDD and TDD component carriers.

[0061] The wireless communication system 100 may also or alternatively support operation on a non-contention licensed radio frequency spectrum band (e.g., a radio frequency spectrum band to which each transmitting device may not contend for access because the radio frequency spectrum band is licensed to a specific user for a specific purpose, such as a licensed radio frequency spectrum band that can be used for LTE / LTE-A communications) or a contention-based shared radio frequency spectrum band (e.g., an unlicensed radio frequency spectrum band to which each transmitting device may need to contend for access because the radio frequency spectrum band is available for unlicensed purposes (such as WiFi purposes)). After winning the competition for access to the contention-based shared radio frequency spectrum band, the transmitting device (e.g., base station 105 or UE 115) may transmit one or more channel reservation signals (e.g., one or more CUBS) on the unlicensed radio frequency spectrum band. The channel reservation signal may be used to reserve unlicensed radio frequency spectrum by providing detectable energy on the unlicensed radio frequency spectrum band. The channel reservation signal may also be used to identify the transmitting device and / or the transmitting antenna, or may be used to synchronize the transmitting device and the receiving device. In some examples, the channel reservation signal transmission may begin at a symbol period boundary (e.g., an OFDM symbol period boundary). In other examples, CUBS transmissions may begin between symbol period boundaries.

[0062] Figure 1 The number and arrangement of components shown are provided as examples. In practice, the wireless communication system 100 may include additional devices, fewer devices, different devices, or different Figure 1 Additionally or alternatively, a set of devices (eg, one or more devices) of the wireless communication system 100 may perform one or more functions described as being performed by another set of devices of the wireless communication system 100.

[0063] Next go to Figure 2A, diagram 200 shows an example of a supplemental downlink mode (e.g., licensed assisted access (LAA) mode) and a carrier aggregation mode for an LTE network supporting extension to LTE / LTE-A with contention-based shared spectrum. Diagram 200 may be Figure 1 105 - a may be an example of a system 100 of FIG. Figure 1 105, and UE 115-a may be Figure 1 Example of UE 115.

[0064] In the example of a supplemental downlink mode (e.g., LAA mode) in diagram 200, the base station 105-a can transmit OFDMA communication signals to the UE 115-a using a downlink 205. The downlink 205 is associated with a frequency F1 in an unlicensed spectrum. The base station 105-a can transmit OFDMA communication signals to the same UE 115-a using a bidirectional link 210, and can receive SC-FDMA communication signals from the UE 115-a using the bidirectional link 210. The bidirectional link 210 is associated with a frequency F4 in a licensed spectrum. The downlink 205 in the unlicensed spectrum and the bidirectional link 210 in the licensed spectrum can operate concurrently. The downlink 205 can provide downlink capacity offloading for the base station 105-a. In some embodiments, the downlink 205 can be used for unicast services (e.g., addressed to one UE) or for multicast services (e.g., addressed to several UEs). This scenario may occur with any service provider (eg, a traditional mobile network operator or MNO) that uses licensed spectrum and needs to relieve some traffic and / or signaling congestion.

[0065] In one example of a carrier aggregation mode in diagram 200, a base station 105-a may transmit OFDMA communication signals to a UE 115-a using a bidirectional link 215, and may receive SC-FDMA communication signals from the same UE 115-a using a bidirectional link 215. The bidirectional link 215 is associated with a frequency F1 in an unlicensed spectrum. The base station 105-a may also transmit OFDMA communication signals to the same UE 115-a using a bidirectional link 220, and may receive SC-FDMA communication signals from the same UE 115-a using a bidirectional link 220. The bidirectional link 220 is associated with a frequency F2 in a licensed spectrum. The bidirectional link 215 may provide downlink and uplink capacity offloading for the base station 105-a. Similar to the supplemental downlink (e.g., LAA mode) described above, this scenario may occur in any service provider (e.g., MNO) that uses a licensed spectrum and needs to alleviate certain traffic and / or signaling congestion.

[0066] In another example of the carrier aggregation mode in diagram 200, the base station 105-a can transmit OFDMA communication signals to the UE 115-a using a bidirectional link 225, and can receive SC-FDMA communication signals from the same UE 115-a using the bidirectional link 225. The bidirectional link 225 is associated with the frequency F3 in the unlicensed spectrum. The base station 105-a can also transmit OFDMA communication signals to the same UE 115-a using a bidirectional link 230, and can receive SC-FDMA communication signals from the same UE 115-a using the bidirectional link 230. The bidirectional link 230 is associated with the frequency F2 in the licensed spectrum. The bidirectional link 225 can provide downlink and uplink capacity offloading for the base station 105-a. This example and those provided above are given for illustrative purposes, and there may be other similar operating modes or deployment scenarios that combine LTE / LTE-A with or without contention-based shared spectrum for capacity offloading.

[0067] As described above, typical service providers that can benefit from the capacity offloading provided by using LTE / LTE-A extended to contention-based spectrum are traditional MNOs with LTE spectrum. For these service providers, an operating configuration may include a bootstrap mode (e.g., supplemental downlink (e.g., LAA mode), carrier aggregation) using an LTE primary component carrier (PCC) on non-contention spectrum and an LTE secondary component carrier (SCC) on contention-based spectrum.

[0068] In the supplemental downlink mode, control of LTE / LTE-A extended to contention-based spectrum may be transmitted over the LTE uplink (e.g., the uplink portion of the bidirectional link 210). One of the reasons for providing downlink capacity offloading is because data demand is largely driven by downlink consumption. Moreover, in this mode, there may be no regulatory impact because the UE is not transmitting in an unlicensed spectrum. There is no need to implement listen-before-talk (LBT) or carrier sense multiple access (CSMA) requirements on the UE. However, LBT can be implemented on a base station (e.g., an eNB) by, for example, using periodic (e.g., every 10 milliseconds) clear channel assessment (CCA) and / or grab-and-release mechanisms aligned with radio frame boundaries.

[0069] In carrier aggregation mode, data and control may be communicated in LTE (e.g., bidirectional links 210, 220, and 230), while data may be communicated in LTE / LTE-A extended to contention-based shared spectrum (e.g., bidirectional links 215 and 225). The carrier aggregation mechanisms supported when using LTE / LTE-A extended to contention-based shared spectrum may fall into hybrid frequency division duplex-time division duplex (FDD-TDD) carrier aggregation or TDD-TDD carrier aggregation with different symmetries across component carriers.

[0070] Figure 2B Diagram 200-a is shown to illustrate an example of a standalone mode for LTE / LTE-A extended to contention-based shared spectrum. Diagram 200-a may be Figure 1 105 - b may be an example of the various parts of the system 100. Figure 1 Base station 105 and Figure 2A 105 - a, and UE 115 - b may be Figure 1 UE 115 and Figure 2A Example of UE 115-a.

[0071] In the example of the standalone mode in diagram 200-a, base station 105-b may transmit OFDMA communication signals to UE 115-b using bidirectional link 240 and may receive SC-FDMA communication signals from UE 115-b using bidirectional link 240. Bidirectional link 240 is similar to the bidirectional link 240 described above. Figure 2A The standalone mode is associated with frequency F3 in the contention-based shared spectrum described. The standalone mode can be used in non-traditional wireless access scenarios, such as in-stadium access (e.g., unicast, multicast). Examples of typical service providers for this mode of operation can be stadium owners, cable companies, event organizers, hotels, enterprises, and large companies that do not have licensed spectrum. For these service providers, an operational configuration for standalone mode can use PCC on contention-based spectrum. Moreover, LBT can be implemented on both the base station and the UE.

[0072] In some examples, the transmitting device (such as reference Figure 1 , 2A or one of the base stations 105 or 105-a described in 2B or reference Figure 1 , 2AOr one of the UEs 115, 115-a, or 115-b described in 2B) can use a gating interval to obtain access to a channel of a contention-based shared radio frequency spectrum band (e.g., a physical channel of an unlicensed radio frequency spectrum band). In some examples, the gating interval can be periodic. For example, the periodic gating interval can be synchronized with at least one boundary of the LTE / LTE-A radio interval. The gating interval can define the application of a contention-based protocol (such as an LBT protocol based at least in part on the LBT protocol specified in the European Telecommunications Standards Institute (ETSI) (EN 301 893)). When a gating interval that defines the application of the LBT protocol is used, the gating interval can indicate when the transmitting device needs to perform a contention procedure (e.g., an LBT procedure), such as a clear channel assessment (CCA) procedure. The result of the CCA procedure can indicate to the transmitting device whether the channel of the contention-based shared radio frequency spectrum band is available for use or in use during the gating interval (also referred to as an LBT radio frame). When the CCA procedure indicates that the channel is available for the corresponding LBT radio frame (e.g., "cleared" for use), the transmitting device may reserve or use the channel of the contention-based shared radio frequency spectrum band during part or all of the LBT radio frame. When the CCA procedure indicates that the channel is not available (e.g., the channel is used or reserved by another transmitting device), the transmitting device may be blocked from using the channel during the LBT radio frame.

[0073] Figure 2A and 2B The number and arrangement of components shown are provided as examples. In practice, the wireless communication system 200 may include additional devices, fewer devices, different devices, or different Figure 2A and 2B Those shown are arranged differently.

[0074] Figure 3 is an illustration of an example 300 of wireless communication 310 over an unlicensed radio frequency spectrum band in accordance with various aspects of the present disclosure. In some examples, an LBT radio frame 315 may have a duration of 10 milliseconds and include a number of downlink (D) subframes 320, a number of uplink (U) subframes (SF) 325, and two types of special subframes (S subframes 330 and S' subframes 335). The S subframes 330 may provide a transition between a downlink subframe 320 and an uplink subframe 325, while the S' subframes 335 may provide a transition between an uplink subframe 325 and a downlink subframe 320, and in some examples, a transition between LBT radio frames.

[0075] During the S′ subframe 335, a downlink clear channel assessment (CCA) procedure 345 may be performed by one or more base stations (such as reference Figure 1or 2) to reserve a channel for wireless communication 310 to occur on a contention-based shared radio frequency spectrum band for a period of time. After a successful downlink CCA procedure 345 is executed by the base station, the base station may transmit a preamble (such as a channel usage beacon signal (CUBS)) (e.g., a downlink CUBS (D-CUBS 350)) to provide an indication to other base stations or devices (e.g., UEs, Wi-Fi access points, etc.) that the base station has reserved the channel. In some examples, the D-CUBS 350 may be transmitted using multiple interleaved resource blocks. Transmitting the D-CUBS 350 in this manner enables the D-CUBS 350 to occupy at least a certain percentage of the available frequency bandwidth of the contention-based shared radio frequency spectrum band and satisfy one or more regulatory requirements (e.g., a requirement that transmissions on an unlicensed radio frequency spectrum band occupy at least 80% of the available frequency bandwidth). In some examples, D-CUBS 350 may take the form of a cell-specific reference signal (CRS) or a channel state information reference signal (CSI-RS) similar to LTE / LTE-A. When downlink CCA procedure 345 fails, D-CUBS 350 may not be transmitted.

[0076] The S' subframe 335 may include multiple OFDM symbol periods (e.g., 14 OFDM symbol periods). The first portion of the S' subframe 335 may be used by several UEs as a shortened uplink (U) period 340. The second portion of the S' subframe 335 may be used for a downlink CCA procedure 345. The third portion of the S' subframe 335 may be used by one or more base stations that successfully contend for access to a channel of a contention-based shared radio frequency spectrum band to transmit D-CUBS 350.

[0077] During the S subframe 330, the uplink CCA procedure 365 may be performed by one or more UEs (such as those described above with reference to Figure 1 , 2Aor 2B described in one or more of the UE 115, 215, 215-a, 215-b, or 215-c) to reserve a channel on which wireless communication 310 occurs for a period of time. After a successful uplink CCA procedure 365 is executed by the UE, the UE may transmit a preamble (such as an uplink CUBS (U-CUBS 370)) to provide an indication to other UEs or devices (e.g., base stations, Wi-Fi access points, etc.) that the UE has reserved the channel. In some examples, the U-CUBS 370 may be transmitted using multiple interleaved resource blocks. Transmitting the U-CUBS 370 in this manner enables the U-CUBS 370 to occupy at least a certain percentage of the available frequency bandwidth of a contention-based radio frequency spectrum band and meet one or more regulatory requirements (e.g., a requirement that transmissions on a contention-based radio frequency spectrum band occupy at least 80% of the available frequency bandwidth). In some examples, the U-CUBS 370 may take a form similar to the LTE / LTE-A CRS or CSI-RS. When the uplink CCA procedure 365 fails, U-CUBS 370 may not be transmitted.

[0078] The S subframe 330 may include multiple OFDM symbol periods (e.g., 14 OFDM symbol periods). The first part of the S subframe 330 may be used by several base stations as a shortened downlink (D) period 355. The second part of the S subframe 330 may be used as a guard period (GP) 360. The third part of the S subframe 330 may be used for an uplink CCA procedure 365. The fourth part of the S subframe 330 may be used as an uplink pilot time slot (UpPTS) or for transmitting U-CUBS 370 by one or more UEs that successfully compete for access to a channel of a contention-based radio frequency spectrum band.

[0079] In some examples, the downlink CCA procedure 345 or the uplink CCA procedure 365 may include the execution of a single CCA procedure. In other examples, the downlink CCA procedure 345 or the uplink CCA procedure 365 may include the execution of an extended CCA procedure. The extended CCA procedure may include a random number of CCA procedures, and in some examples may include multiple CCA procedures.

[0080] As indicated above, Figure 3 are provided as examples. Other examples are possible and may differ from the combination Figure 3 The content of the description.

[0081] Figure 4 is an illustration of an example 400 of a CCA procedure 415 performed by a transmitting device when competing for access to a contention-based shared radio frequency spectrum band in accordance with aspects of the present disclosure. In some examples, the CCA procedure 415 may be a reference to Figure 34. An example of a downlink CCA procedure 345 or an uplink CCA procedure 365 described in the specification. The CCA procedure 415 may have a fixed duration. In some examples, the CCA procedure 415 may be performed according to an LBT frame-based equipment (LBT-FBE) protocol (e.g., the LBT-FBE protocol described by EN 301 893). After the CCA procedure 415, a channel reservation signal (such as CUBS 420) may be transmitted, followed by data transmission (e.g., uplink transmission or downlink transmission). As an example, the data transmission may have an expected duration 405 of four subframes and an actual duration 410 of three subframes.

[0082] As indicated above, Figure 4 are provided as examples. Other examples are possible and may differ from the combination Figure 4 The content of the description.

[0083] Figure 5 is an illustration of an example 500 of an extended CCA (ECCA) procedure 515 performed by a transmitting device when contending for access to a contention-based shared radio frequency spectrum band in accordance with aspects of the present disclosure. In some examples, the ECCA procedure 515 may be a reference to Figure 3 An example of a downlink CCA procedure 345 or an uplink CCA procedure 365 described. The ECCA procedure 515 may include a random number of CCA procedures, and in some examples may include multiple CCA procedures. The ECCA procedure 515 may therefore have a variable duration. In some examples, the ECCA procedure 515 may be executed according to an LBT load-based equipment (LBT-LBE) protocol (e.g., the LBT-LBE protocol described by EN301 893). The ECCA procedure 515 may provide a greater possibility of winning competition for access to a contention-based shared radio frequency spectrum band, but at the potential cost of shorter data transmission. After the ECCA procedure 515, a channel reservation signal (such as CUBS 520) may be transmitted, followed by data transmission. As an example, the data transmission may have an expected duration 505 of four subframes and an actual duration 510 of two subframes.

[0084] As indicated above, Figure 5 are provided as examples. Other examples are possible and may differ from the combination Figure 5 The content of the description.

[0085] Figure 6 A block diagram shows a design of a base station / eNB 105 and a UE 115, which may be Figure 1105 and one of the base stations / eNBs and one of the UEs in the UE. The eNB 105 may be equipped with antennas 634a to 634t, and the UE 115 may be equipped with antennas 652a to 652r. At the eNB 105, the transmit processor 620 may receive data from the data source 612 and control information from the controller / processor 640. The control information may be used for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid automatic repeat request indicator channel (PHICH), a physical downlink control channel (PDCCH), etc. The data may be used for a physical downlink shared channel (PDSCH), etc. The transmit processor 620 may process (e.g., encode and symbol map) the data and the control information to obtain data symbols and control symbols, respectively. The transmit processor 620 may also generate reference symbols (e.g., reference symbols for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a reference signal that varies from cell to cell). The transmit (TX) multiple-input multiple-output (MIMO) processor 630 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, and / or reference symbols where applicable, and may provide an output symbol stream to modulators (MOD) 632a to 632t. Each modulator 632 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 632 may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signals from modulators 632a to 632t may be transmitted via antennas 634a to 634t, respectively.

[0086] At the UE 115, antennas 652a through 652r may receive downlink signals from the eNB 105 and may provide received signals to demodulators (DEMODs) 654a through 654r, respectively. Each demodulator 654 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 654 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 656 may obtain received symbols from all demodulators 654a through 654r, perform MIMO detection on the received symbols where applicable, and provide detected symbols. A receive processor 658 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 115 to a data sink 660, and provide decoded control information to a controller / processor 680.

[0087] On the uplink, at the UE 115, a transmit processor 664 may receive and process data from a data source 662 (e.g., data for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 680 (e.g., control information for a physical uplink control channel (PUCCH)). The transmit processor 664 may also generate reference symbols for a reference signal. The symbols from the transmit processor 664 may be precoded by a TX MIMO processor 666, if applicable, further processed by demodulators 654a through 654r (e.g., for SC-FDM, etc.), and transmitted to the eNB 105. At the eNB 105, uplink signals from the UE 115 may be received by the antenna 634, processed by the modulator 632, detected by the MIMO detector 636, if applicable, and further processed by the receive processor 638 to obtain decoded data and control information sent by the UE 115. Processor 638 may provide decoded data to data sink 646 and decoded control information to controller / processor 640 .

[0088] The controller / processors 640 and 680 may direct the operation at the eNB 105 and the UE 115, respectively. The controller / processor 640 and / or other processors and modules at the eNB 105 may perform or direct the execution of various processes for the techniques described herein. The controller / processor 680 and / or other processors and modules at the UE 115 may also perform or direct the execution of various processes for the techniques described herein. Figure 8 , 10A , the functional blocks illustrated in 10B, and / or the execution of other processes for the techniques described herein. Memories 642 and 682 may store data and program codes for eNB 105 and UE 115, respectively. Scheduler 644 may schedule UEs for data transmission on the downlink and / or uplink.

[0089] A device (such as a UE) may have multiple antennas (N) for receiving and / or transmitting signals. The device may divide the use and assignment of antennas for a specific radio access technology (RAT) (such as LTE, WiFi, etc.), a specific carrier frequency, or both. For example, in each CA scenario, the device may use a fixed number of antennas for one carrier, or when the device supports both WiFi and other technologies (such as LTE), it may use a fixed number of antennas for WiFi. In one example, a UE may have 4 antennas, and 2 of these antennas are assigned for WiFi communication and 2 antennas for LTE communication. A device (such as a UE) may also dynamically or semi-statically select the number of antennas (antenna selection) for a technology or a carrier. In such a dynamic or semi-static scheme, specific measurement results (such as channel quality indicators (CQI), reference signal received power (RSRP), etc.) may trigger sharing or selection.

[0090] Communication networks (such as LTE) can have frequency division multiplexing (FDM) implementations and time division multiplexing (TDM) implementations. The sharing option in the FDM implementation does not really share different antennas, but rather shares the spectrum received on the antennas. For example, a UE can use a diplexer / switch to use all antennas for different air interfaces at the same time. The diplexer / switch acts as a filter by filtering out unwanted frequencies. However, in such FDM sharing schemes, there is usually a considerable loss in signal strength as the signal is filtered. Such losses may also increase with higher frequency bands. A TDM implementation can actually use or assign a separate antenna for each air interface / each technology. Thus, when communications through such air interfaces / techniques are not in use, those antennas assigned or designated to unused communications can be shared with other air interfaces / techniques. Various aspects of the present disclosure relate to communication systems implemented using TDM.

[0091] According to some aspects of the present disclosure, a UE may blindly detect whether a subframe has a valid downlink transmission by testing the presence of a CRS in symbol 0. For example, within symbol 0, it is foreseeable that a one-time LBT may be performed for a duration of twenty-five microseconds. A one-time LBT is also referred to herein as a short LBT because it is shorter in duration than a full CCA. A short LBT may also refer to any LBT that is shorter in duration than a full LBT. Accordingly, there are multiple types of LBT that may be performed by a UE. As described below with reference to Figure 7 and 8 Described in more detail, the eNB may indicate to the UE the type of LBT (if any) that the UE should perform based on the eNB's knowledge of ongoing or recent downlink transmissions on the frequency to be used by the UE for UL transmissions. Thus, when the eNB knows that the channel is likely to be clear, the UE may acquire the channel more quickly and / or save resources by avoiding a full CCA.

[0092] In this document, a transmission opportunity (TXOP) is defined as a sequence of one or more transmissions performed by a master device and one or more slave devices, optionally initiated by the master device, using a basic access mechanism. As explored in more detail below, pausing a TXOP can accommodate UL scheduling delays in LAA to ensure that time not used by the eNB can be used by the UE in a TXOP after a four millisecond delay. If the UE is unable to acquire the channel before the start time of the UL grant, the UE may not be able to transmit on all subframes allocated by the grant. In other words, the UE's TXOP may be truncated due to limitations on the end point of the TXOP and failure to acquire the channel in time to start uplink transmission at the start point of the uplink transmission. However, as described below with reference to Fig. 9A and 9B More specifically described, the present disclosure contemplates semi-persistent grants with more than one start time, each with an end time that provides a full length TXOP, such that the UE can begin transmission at a later start time (if desired) and still transmit the entire TXOP.

[0093] See also Figure 7 , a wireless communication method can be performed by an eNB. Figure 7 The method represents a process performed by an eNB to set an LBT indication in an uplink grant to correspond to a condition associated with a potential downlink transmission. As explained below, the LBT indication may indicate no LBT, a one-time LBT, a UE decision, and / or a full CCA, and the LBT indication may indicate more than one type of LBT and / or a range of types of LBT.

[0094] Beginning at block 700, the eNB may determine a type of LBT indication to be set in an UL grant transmitted on a first frequency (F1) in order to allocate uplink resources on a second frequency (F2) for a user equipment (UE). It is contemplated that the indicator may be a field, a flag, a bit, or any other type of indicator. As explained in more detail below, the type of LBT may be no LBT, one-time LBT, UE decision, full CCA, and / or a combination thereof is foreseeable. Processing may proceed from block 700 to block 702.

[0095] At block 702, the eNB may set the LBT indication in the UL grant to correspond to a condition associated with a potential downlink transmission on F2. For example, it is contemplated that the condition may correspond to a potential downlink transmission occurring on F2 at time T, where time T corresponds to the start of the UL transmission scheduled by the UL grant. Alternatively or additionally, it is contemplated that the condition may correspond to a potential downlink transmission occurring on F2 until time T. p = Potential downlink transmissions occurring on F2 up to time Tp Before time T, and T and T p The time difference between is less than a threshold. Alternatively or additionally, it is contemplated that the condition may correspond to a potential downlink transmission occurring during a predetermined window, wherein the time window overlaps with time T. Further, the potential downlink transmission may correspond to a transmission from a serving eNB or a remote radio head (RRH) in a set of eNBs and / or a CoMP set to a UE and / or to another UE. Still further, the type of LBT may correspond to a first type of LBT if the condition is met at time T, and to a second type of LBT if the condition is not met at time T. For example, it is contemplated that a first type of LBT indication may correspond to no LBT, a one-time LBT, a short LBT, and / or a UE decision, while a second type of LBT indication may correspond to a full CCA. Processing may proceed from box 702 to box 704.

[0096] At block 704, at time T, the eNB may transmit an UL grant to the UE. Alternatively or additionally, the eNB may receive an UL transmission at one or more start times, as described below with reference to Fig. 9A Alternatively, the process may end.

[0097] See also Figure 8 , a wireless communication method can be performed by a UE. Figure 8 The method represents a process performed by a UE to perform LBT based on an LBT indication included in an uplink grant. As described above, the LBT indication may indicate no LBT, a one-time LBT, a UE decision and / or a complete CCA, and the LBT indication may indicate more than one type of LBT and / or a range of types of LBT.

[0098] Beginning at block 800, the UE may receive an UL grant transmitted by the eNB on F1. The UL grant may allocate uplink resources on F2 for the UE. Processing may proceed from block 800 to block 802.

[0099] In block 802, the UE may determine the type of LBT indication in the UL grant. For example, the UE may determine that the LBT indicator is set to indicate no LBT or a one-time LBT. Alternatively or additionally, the UE may determine that the LBT indicator is set to indicate a UE decision. Alternatively or additionally, the UE may determine that the LBT indicator is set to indicate a full CCA. Processing may proceed from block 802 to block 804.

[0100] In box 804, the UE may access F2 according to the type of LBT indication determined. For example, the UE may perform UL transmission on F2 without performing LBT on F2 in response to determining that the LBT indicator is set to indicate no LBT. Alternatively or additionally, the UE may perform a one-time LBT on F2 before performing UL transmission on F2 in response to determining that the LBT indicator is set to indicate a one-time LBT. Alternatively or additionally, the UE may perform a one-time LBT on F2 before performing UL transmission on F2 and in response to determining that the LBT indicator is set to indicate the UE decision, and then perform a full CCA on F2 only if the one-time LBT on F2 proves unsuccessful. Alternatively or additionally, the UE may perform a full CCA on F2 before performing UL transmission on F2 in response to determining that the LBT indicator is set to indicate a full CCA. Processing may proceed from box 804 to box 806.

[0101] At block 806, the UE may perform UL transmission on F2 according to the UL grant. Fig. 9B As further explained, it is contemplated that the UL grant may be a semi-persistent UL grant. Accordingly, it is contemplated that at block 806, the UE may perform an UL transmission on F2 in accordance with the semi-persistent UL grant.

[0102] See also Fig. 9A , a wireless communication method can be performed by an eNB. Fig. 9A The method of represents a process performed by an eNB to schedule a semi-persistent UL grant to a UE. Such a grant can accommodate suspension of transmission opportunities by being valid for more than one start time.

[0103] Beginning at block 900, the eNB may indicate to the UE that the UL grant is valid for two or more starting positions, including at least a first starting position and a second starting position. It is contemplated that the eNB may schedule a semi-persistent grant to only one UE at a time. Processing may proceed to block 902.

[0104] At block 902, the eNB may transmit a UL grant to the UE. Processing may proceed to block 904.

[0105] At block 904, the eNB may communicate the maximum number of starting positions to the UE. For example, it is contemplated that the maximum number of starting positions may be transmitted in an uplink grant. Alternatively or additionally, it is contemplated that the maximum number of starting positions may be communicated in a common control message, in a system information message, and / or in an RRC message. Processing may proceed to block 906.

[0106] At block 906 , the eNB may attempt to receive an UL transmission from the UE at a current starting position, such as a first starting position. For example, the current starting position variable may be initialized to the first starting position. Processing may proceed to block 908 .

[0107] At block 908, the eNB may determine whether the attempt to receive the UL transmission at the first starting position was successful. If the eNB determines that the attempt was successful, the process may end. However, if the eNB determines that the attempt was unsuccessful, the process may proceed to block 910.

[0108] At block 910, the eNB may determine whether it has attempted to receive an UL transmission from the UE at a maximum number of starting positions. For example, the eNB may compare a current starting position variable to a maximum starting position. If the eNB determines that the maximum number of starting positions has been reached, the process may end. Thus, the eNB may limit the number of two or more starting positions to the maximum number of starting positions. However, if the eNB determines that the maximum number of starting positions has not been reached, the process may proceed to block 912.

[0109] At block 912, the eNB may proceed to the next starting position. For example, the eNB may increment the current starting position variable. The process may then return to block 906, at which point the eNB may attempt to receive an UL transmission from the UE at a second starting position in response to determining that the attempt to receive the UL transmission at the first starting position was unsuccessful. The process may thus continue in this manner until the eNB determines at block 908 that the UL transmission is successfully received, or until the eNB determines at block 910 that the maximum number of starting positions has been reached.

[0110] See also Fig. 9B , a wireless communication method can be performed by a UE. Fig. 9B The method of represents a process performed by a UE in response to a semi-persistent UL grant from an eNB. Such a grant can accommodate suspension of transmission opportunities by being valid for more than one start time.

[0111] Beginning at block 950, the UE may receive a UL grant from the eNB. Processing may proceed to block 952.

[0112] At block 952 , the UE may receive an indication from the eNB that the UL grant is valid for two or more starting positions, including a first starting position and a second starting position. Processing may proceed to block 954 .

[0113] At block 954, the UE may determine the maximum number of the two or more starting positions. For example, the UE may observe the maximum number of starting positions communicated in the UL grant. Alternatively or additionally, the UE may observe the maximum number of starting positions communicated in the RRC message. Processing may proceed to block 956.

[0114] At block 956, the UE may attempt to acquire the channel in time to perform an UL transmission using the first starting position. For example, the UE may initialize the current starting position variable to the first starting position and attempt to acquire the channel in time to perform an UL transmission using the current starting position. Similarly, the UE may perform a short LBT or a full CCA depending on the indicator in the grant, as described above with reference to Figure 8 Processing may proceed to block 958 .

[0115] At block 958, the UE may determine whether the attempt to acquire a channel in time to perform an UL transmission using the first starting position was successful. If the UE determines that the attempt was successful, the process may proceed to block 960. However, if the UE determines that the attempt was unsuccessful, the process may proceed to block 962.

[0116] At block 960, the UE may perform transmissions starting at the current starting position and may transmit the entire TXOP. The process may then end.

[0117] At block 962, the UE may determine whether acquisition of the channel has been attempted at a maximum number of starting positions. For example, the UE may compare a current starting position variable to a maximum starting position. If the UE determines that the maximum number of starting positions has been reached, the process may end. Thus, the UE may limit the number of two or more starting positions at which to attempt to start transmission to the maximum number of starting positions. However, if the eNB determines that the maximum number of starting positions has not been reached, the process may proceed to block 964.

[0118] At block 964, the UE may proceed to the next start position. For example, the eNB may increment the current start position variable. The process may then return to block 956, at which point the UE may attempt to acquire a channel in time to perform an UL transmission using the current (e.g., second) start position in response to determining that an attempt to acquire a channel in time to perform an UL transmission using the previous (e.g., first) start position was unsuccessful. The process may thus continue in this manner until the UE determines at block 958 that the channel was successfully acquired, or until the UE determines at block 962 that the maximum number of start positions has been reached.

[0119] Reference Fig. 10A , UE 115 may have a processor 680 and a memory 682, wherein the memory 682 may store the processor 680 configured to perform the above Figure 8 and 9BThe instructions for the described operations. For example, the memory 682 may store an uplink grant processor application 1000 that configures the processor 680 to observe an indicator in an UL grant to determine the type of LBT to be performed. The UL grant processor application 1000 may also configure the processor 680 to identify an indication of a semi-persistent grant and a maximum number of starting positions. The LBT application 1002 may be implemented to perform various types of LBT in response to the indicator observed in the grant. The UL transmission application 1004 may configure the processor 680 to use the radio 1000a-r and the antenna 652a-r to perform an uplink transmission in accordance with the grant. The RRC layer application 1006 may respond to an RRC message containing the maximum number of starting positions as described above.

[0120] Reference Fig. 10B , the eNB 105 may have a processor 640 coupled to a radio 1009a-1 having antennas 634a-t and a memory 642, wherein the memory 642 may store instructions for configuring the processor 640 to perform as described above with respect to Figure 7 and 9A 1054 to determine one of two or more types of indicators 1052 to be set in the UL grant. The scheduler 1054 may also allocate a semi-persistent grant to the UE and indicate to the UE that the grant is semi-persistent, as described above. The memory 1056 may store a maximum number of starting positions 1056 and store information about the attempted starting positions 1058. The scheduler may communicate the maximum number of starting positions to the UE in the UL grant, or the RRC layer application 1060 may communicate the information in an RRC message.

[0121] Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0122] Figure 6 , 7 The functional blocks and modules in , 8, 9A, 9B, 10A and 10B may include processors, electronic devices, hardware devices, electronic components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

[0123] The technician will further appreciate that the various illustrative logic boxes, modules, circuits, and algorithm steps described in conjunction with the disclosure herein can be implemented as electronic hardware, computer software, or a combination of the two. To clearly explain this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described in the form of their functionality above. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician can implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as causing departure from the scope of the present disclosure. The technician will also easily recognize that the order or combination of components, methods, or interactions described herein are only examples and the components, methods, or interactions of various aspects of the present disclosure can be combined or performed in a manner different from those explained and described herein.

[0124] The various illustrative logical blocks, modules, and circuits described in conjunction with the disclosure herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0125] The steps of the method or algorithm described in conjunction with the disclosure of this article can be implemented directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module can reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read and write information from / to the storage medium. Alternatively, the storage medium can be integrated into the processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative, the processor and the storage medium can reside in a user terminal as discrete components.

[0126] In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any media that facilitates the transfer of a computer program from one place to another. Computer-readable storage media may be any available media that can be accessed by a general or special-purpose computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code means in the form of an instruction or data structure and can be accessed by a general or special-purpose computer, or a general or special-purpose processor. Moreover, a connection may also be properly referred to as a computer-readable medium. For example, if the software is transmitted from a web site, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, or a digital subscriber line (DSL), the coaxial cable, the fiber optic cable, the twisted pair, or the DSL is included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk usually reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0127] As used herein, including in the claims, the term "and / or" used in a list of two or more items means that any of the listed items may be taken alone, or any combination of two or more of the listed items may be taken. For example, if a composition is described as comprising components A, B, and / or C, the composition may comprise only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C. In addition, as used herein, including in the claims, "or" used in a list of items followed by "at least one of" indicates a disjunctive list, so that, for example, a list of "at least one of A, B, or C" means any of A or B or C or AB or AC or BC or ABC (i.e., A and B and C) or any combination thereof.

[0128] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the universal principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Therefore, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wireless communication method performed by a base station, the method comprising: determining a predetermined time window on a second frequency F2 allocated for downlink transmission; determining, from a plurality of listen-before-talk LBT types, an LBT type to be set in an uplink UL grant scheduled for transmission on a first frequency F1; generating the UL grant including the predetermined time window and an LBT indication based on the LBT type; as well as The UL grant is transmitted to a user equipment UE on the F1, wherein the UL grant allocates uplink resources on the F2 starting at a time T for the UE, the time T overlapping the predetermined time window.

2. The method of claim 1, wherein the F1, the F2, or a combination thereof is included in an unlicensed spectrum.

3. The method of claim 1, wherein the plurality of LBT types include a complete clear channel assessment (CCA) and a one-shot LBT.

4. The method of claim 3, wherein the one-time LBT is shorter in duration than the complete CCA.

5. The method of claim 3, wherein the one-shot LBT is configured to be performed for a duration of twenty-five microseconds within a single symbol.

6. The method of claim 1, further comprising receiving a UL transmission from the UE.

7. The method of claim 1, further comprising transmitting a downlink transmission before or at the time T.

8. A base station, comprising: at least one processor; as well as a memory coupled to the at least one processor and storing processor-readable code, the processor-readable code being configured, when executed by the at least one processor, to: determining a predetermined time window on a second frequency F2 allocated for downlink transmission; determining, from a plurality of listen-before-talk LBT types, an LBT type to be set in an uplink UL grant scheduled for transmission on a first frequency F1; generating the UL grant including the predetermined time window and an LBT indication based on the determined type, the LBT type; as well as Initiating transmission of the UL grant to a user equipment UE on the F1, wherein the UL grant allocates uplink resources for the UE on the F2 starting at a time T, the time T overlapping the predetermined time window.

9. The base station of claim 8, wherein the F1, the F2, or a combination thereof is included in an unlicensed spectrum.

10. The base station of claim 8, wherein the plurality of LBT types include complete clear channel assessment (CCA) and one-shot LBT.

11. The base station of claim 10, wherein the one-time LBT is shorter in duration than the complete CCA.

12. The base station of claim 10, wherein the one-time LBT is configured to be performed for a duration of twenty-five microseconds within a single symbol.

13. The base station of claim 8, further comprising receiving a UL transmission from the UE.

14. The base station of claim 8, further comprising transmitting a downlink transmission before or at the time T.

15. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform operations comprising: determining a predetermined time window on a second frequency F2 allocated for downlink transmission; determining, from a plurality of listen-before-talk LBT types, an LBT type to be set in an uplink UL grant scheduled for transmission on a first frequency F1; generating the UL grant including the predetermined time window and an LBT indication based on the LBT type; as well as The UL grant is transmitted to a user equipment UE on the F1, wherein the UL grant allocates uplink resources on the F2 starting at a time T for the UE, the time T overlapping the predetermined time window.

16. The non-transitory computer-readable medium of claim 15, wherein the F1, the F2, or a combination thereof is included in an unlicensed spectrum.

17. The non-transitory computer-readable medium of claim 15, wherein the plurality of LBT types include a complete clear channel assessment (CCA) and a one-shot LBT.

18. The non-transitory computer-readable medium of claim 17, wherein the one-time LBT is shorter in duration than the complete CCA.

19. The non-transitory computer-readable medium of claim 17, wherein the one-shot LBT is configured to be performed for a duration of twenty-five microseconds within a single symbol.

20. The non-transitory computer-readable medium of claim 15, further comprising receiving a UL transmission from the UE.

21. The non-transitory computer readable medium of claim 15, further comprising transmitting a downlink transmission before or at the time T.

22. A method of wireless communication performed by a user equipment (UE), the method comprising: receiving an uplink UL grant transmitted by a base station on a first frequency F1, wherein the UL grant allocates uplink resources on a second frequency F2 for the UE starting at time T, the time T overlapping a predetermined time window, and the UL grant includes the predetermined time window and a listen-before-talk LBT indication; determining the predetermined time window based on the UL grant; determining an LBT type from among a plurality of LBT types based on the LBT indication; accessing the F2 by performing LBT based on the determined LBT type; as well as UL transmission is performed on the F2 based on the UL grant.

23. The method of claim 22, wherein the F1, the F2, or a combination thereof is included in an unlicensed spectrum.

24. The method of claim 22, wherein the plurality of LBT types include a full clear channel assessment (CCA) and a one-shot LBT, the one-shot LBT being shorter in duration than the full CCA.

25. The method of claim 24, wherein determining the LBT type comprises determining that the LBT indication corresponds to the one-time LBT, and wherein accessing the F2 comprises performing the one-time LBT on the F2 before performing an UL transmission on the F2.

26. The method of claim 24, wherein determining the LBT type comprises determining that the LBT indication corresponds to the full CCA, and wherein accessing the F2 comprises performing the full CCA on the F2 before performing an UL transmission on the F2.

27. The method of claim 22, further comprising receiving a downlink transmission from the base station before or at the time T.

28. A user equipment UE, comprising: at least one processor; as well as a memory coupled to the at least one processor and storing processor-readable code, the processor-readable code being configured, when executed by the at least one processor, to: receiving an uplink UL grant transmitted by a base station on a first frequency F1, wherein the UL grant allocates uplink resources on a second frequency F2 for the UE starting at time T, the time T overlapping a predetermined time window, and the UL grant includes the predetermined time window and a listen-before-talk LBT indication; determining the predetermined time window based on the UL grant; determining an LBT type from among a plurality of LBT types based on the LBT indication; accessing the F2 by performing LBT based on the determined LBT type; as well as UL transmission is performed on the F2 based on the UL grant.

29. The UE of claim 28, wherein the F1, the F2, or a combination thereof is included in an unlicensed spectrum.

30. The UE of claim 28, wherein the plurality of LBT types include a full clear channel assessment (CCA) and a one-time LBT, the one-time LBT being shorter in duration than the full CCA.

31. The UE of claim 30, wherein: To determine the LBT type, the processor readable code, when executed by the at least one processor, is further configured to determine that the LBT indication corresponds to the one-time LBT, and To access the F2, the processor readable code, when executed by the at least one processor, is further configured to perform the one-time LBT on the F2 before performing UL transmission on the F2.

32. The UE of claim 30, wherein: To determine the LBT type, the processor readable code, when executed by the at least one processor, is further configured to determine that the LBT indication corresponds to the complete CCA, and To access the F2, the processor readable code, when executed by the at least one processor, is further configured to perform the full CCA on the F2 before performing an UL transmission on the F2.

33. The UE of claim 28, the processor readable code when executed by the at least one processor is further configured to receive a downlink transmission from the base station before or at the time T.

34. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform operations comprising: receiving an uplink UL grant transmitted by a base station on a first frequency F1, wherein the UL grant allocates uplink resources on a second frequency F2 for a user equipment UE starting at a time T, the time T overlapping a predetermined time window, the UL grant including the predetermined time window and a listen-before-talk LBT indication; determining the predetermined time window based on the UL grant; determining an LBT type from among a plurality of LBT types based on the LBT indication; accessing the F2 by performing LBT based on the determined LBT type; as well as UL transmission is performed on the F2 based on the UL grant.

35. The non-transitory computer-readable medium of claim 34, wherein the F1, the F2, or a combination thereof is included in an unlicensed spectrum.

36. The non-transitory computer-readable medium of claim 34, wherein the plurality of LBT types include a full clear channel assessment (CCA) and a one-shot LBT, the one-shot LBT being shorter in duration than the full CCA.

37. The non-transitory computer-readable medium of claim 36, wherein determining the LBT type comprises determining that the LBT indication corresponds to the one-time LBT, and wherein accessing the F2 comprises performing the one-time LBT on the F2 before performing an UL transmission on the F2.

38. The non-transitory computer-readable medium of claim 36, wherein determining the LBT type comprises determining that the LBT indication corresponds to the full CCA, and wherein accessing the F2 comprises performing the full CCA on the F2 prior to performing an UL transmission on the F2.

39. The non-transitory computer-readable medium of claim 34, wherein the operations further comprise receiving a downlink transmission from the base station before or at the time T.

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