BR112018074297B1 - HARQ FEEDBACK IN THE SHARED RF SPECTRUM BAND - Google Patents

Abstract

Methods, systems and devices for wireless communication are described. Wireless communications systems operating in the unlicensed or shared radio frequency spectrum band can use different modes to manage hybrid automatic repeat request (HARQ) feedback. HARQ feedback can be transmitted autonomously or, in some cases, HARQ feedback can be requested from a user equipment (UE) to one or several HARQ processes. Requested feedback may be called surveyed feedback, or autonomous feedback may be called unsurveyed feedback. Polled and un-polled feedback can be transmitted using different physical channels and can be grant-based or triggered without an express grant. Buffers for polled and unpolled feedback can be maintained and managed separately. In a multicarrier configuration, the uplink control information (UCI) for one or more carriers may be transmitted on a subset of configured uplink carriers. A number of carriers used for UCI may depend on the operating conditions of a UE.

Description

Cross References

[01] This patent application claims the priority of US Patent Application No. 15/604,326 by Chendamarai Kannan et al, entitled “HARQ Feedback in Shared RF Spectrum Band”, filed on May 24, 2017; and US Provisional Patent Application No. 62/342,870 by Patel et al. entitled “HARQ Feedback in Shared RF Spectrum Band”, filed May 27, 2016; each of which is assigned to the transferee thereof.

BACKGROUND

[02] The following refers generally to wireless communication, and more specifically to hybrid automatic repeat request (HARQ) feedback in unlicensed radio frequency (RF) spectrum.

[03] Wireless communication systems are widely employed to deliver various types of communication content such as voice, video, packet data, messaging, broadcast and so on. These systems may be able to support communication with multiple users by sharing available system resources (eg 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, and Orthogonal Frequency Division (OFDMA), eg a Long Term Evolution (LTE) system. A wireless multiple access communication system may include a number of base stations, each simultaneously supporting communication to multiple communication devices, which may otherwise be known as user equipment (UE).

[04] In some wireless communication systems, devices may communicate using resources from a shared or unlicensed RF spectrum band. This communication can be contention-based, and the shared nature of the wireless medium can introduce complexities for transmitting or receiving certain types of information, including control information. Systems that operate without accounting or compensation for the opportunistic nature of shared spectrum communication can be inefficient or error prone.

SUMMARY

[05] Wireless communications systems operating in unlicensed radio frequency (RF) spectrum may use different modes to manage hybrid automatic repeat request (HARQ) feedback and clearing of feedback buffers. For example, a wireless device can receive downlink data during a transmission opportunity (TxOP) and transmit HARQ feedback within the same TxOP or a subsequent TxOP. After transmission of HARQ feedback and during a TxOP, the wireless device may receive an indication to clear a buffer with HARQ feedback. Additionally or alternatively, the buffer can be cleared based on the feedback transmission. In some examples, the wireless device may indicate an ability to support uplink carriers and, in response, receive a carrier configuration. The wireless device can select a subset of uplink carriers for feedback transmissions and transmit feedback using the subset.

[06] A wireless communication method is described. The method may include receiving a downlink data transmission utilizing shared RF spectrum band resources during a first TxOP; transmitting HARQ feedback in response to the downlink data transmission during the first TxOP or a second TxOP; determine to clear a HARQ feedback buffer after transmitting HARQ feedback during the second TxOP or a third TxOP; and clearing the HARQ feedback from the buffer based, at least in part, on the determination to clear the buffer.

[07] An equipment for wireless communication is described. The equipment may include means for receiving a downlink data transmission utilizing shared RF spectrum band resources during a first TxOP; means for transmitting HARQ feedback in response to the downlink data transmission during the first TxOP or a second TxOP; means for determining to clear a HARQ feedback buffer after transmitting the HARQ feedback during the second TxOP or a third TxOP; and means for clearing the HARQ feedback from the buffer based, at least in part, on the determination to clear the buffer.

[08] Other equipment for wireless communication is described. Equipment may include a processor, memory in electronic communication with the processor, and instructions stored in memory. The instructions may be operable to cause the processor to receive a downlink data transmission using resources of a shared RF spectrum band during a first TxOP; transmit HARQ feedback in response to downlink data transmission during the first TxOP or a second TxOP; determine to clear a HARQ feedback buffer after transmitting HARQ feedback during the second TxOP or a third TxOP; and clear the HARQ feedback from the buffer based, at least in part, on the determination to clear the buffer.

[09] A non-transient computer-readable medium for wireless communication is described. The non-transient computer-readable medium may include instructions operable to cause a processor to receive a downlink data transmission utilizing resources of a shared RF spectrum band during a first TxOP; transmit HARQ feedback in response to downlink data transmission during the first TxOP or a second TxOP; determine to clear a HARQ feedback buffer after transmitting HARQ feedback during the second TxOP or a third TxOP; and clear the HARQ feedback from the buffer based, at least in part, on the determination to clear the buffer.

[010] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions to identify a trigger to transmit additional HARQ feedback. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for transmitting the additional HARQ feedback based at least in part on the trigger. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for clearing additional HARQ feedback from an additional buffer based at least in part on transmitting the HARQ feedback. additional.

[011] In some examples of the method, equipment and non-transient computer-readable medium described above, the buffer may be associated with a request-based feedback mode and the additional buffer may be associated with an autonomous feedback mode.

[012] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for receiving a request to transmit HARQ feedback. Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, facilities, means or instructions for receiving a grant of resources for HARQ feedback, where the HARQ feedback can be transmitted using the resources in response to the request.

[013] In some examples of the method, equipment, and non-transient computer-readable medium described above, the resource grant includes an indication of an identifier for a HARQ process of the HARQ feedback. In some examples of the method, equipment, and non-transient computer-readable medium described above, the request comprises a request to retransmit a previously transmitted subset of feedback.

[014] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for identifying a trigger to transmit HARQ feedback, in which the HARQ feedback can be transmitted based on , at least partly in identifying the trigger. In some examples of the method, equipment, and non-transient computer-readable medium described above, the buffer comprises a common buffer for a short physical uplink control channel (sPUCCH), an enhanced physical uplink control channel (ePUCCH), or a shared channel physical uplink (PUSCH). Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for clearing the buffer according to a predetermined periodicity.

[015] A wireless communication method is described. The method may include transmitting a downlink data transmission utilizing resources of a shared RF spectrum band during a first TxOP, receiving HARQ feedback in response to the downlink data transmission during the first TxOP or a second TxOP, and transmitting an indication to clear a feedback buffer during the second TxOP or a third TxOP.

[016] An equipment for wireless communication is described. The equipment may include means for transmitting a downlink data transmission utilizing resources of a shared RF spectrum band during a first TxOP, means for receiving HARQ feedback in response to the downlink data transmission during the first TxOP or a second TxOP, and means for to transmit an indication to clear a feedback buffer during the second TxOP or a third TxOP.

[017] Other equipment for wireless communication is described. Equipment may include a processor, memory in electronic communication with the processor, and instructions stored in memory. The instructions may be operable to cause the processor to transmit a downlink data transmission utilizing shared RF spectrum band resources during a first TxOP, receive HARQ feedback in response to the downlink data transmission during the first TxOP or a second TxOP , and transmit an indication to clear a feedback buffer during the second TxOP or a third TxOP.

[018] A non-transient computer-readable medium for wireless communication is described. The non-transient computer-readable medium may include instructions operable to cause a processor to transmit a downlink data transmission using resources of a shared RF spectrum band during a first TxOP, receive HARQ feedback in response to the downlink data transmission during the first TxOP or a second TxOP, and transmit an indication to clear a feedback buffer during the second TxOP or a third TxOP.

[019] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions to identify a trigger for additional HARQ feedback. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for receiving the additional HARQ feedback based at least in part on the trigger.

[020] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for transmitting a request for HARQ feedback. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for transmitting a grant of resources for HARQ feedback, where the HARQ feedback may be transmitted using the resources in response to the request.

[021] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for determining that an identifier for a HARQ process associated with the transmission of downlink data may not be recognized, where the request for HARQ feedback can be transmitted based at least in part on the determination.

[022] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for determining that an identifier for a HARQ process associated with the transmission of downlink data may not be recognized. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for transmitting an additional downlink data transmission based at least in part on a determination.

[023] In some examples of the method, equipment and non-transient computer-readable medium described above, the buffer comprises a common buffer for an sPUCCH, ePUCCH, or a PUSCH.

[024] A wireless communication method is described. The method may include transmitting an indication of an amount of uplink carriers of a shared RF spectrum band for which uplink control information (UCI) transmissions are supported, receiving a carrier configuration that includes a set of uplink carriers for UCI transmissions based at least in part on the indication, selecting a subset of the uplink carriers for UCI transmissions, where the subset comprises fewer uplink carriers than the set of uplink carriers for UCI, and transmitting UCI using the subset of uplink carriers.

[025] An equipment for wireless communication is described. The equipment may include means for transmitting an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, means for receiving a carrier configuration that includes a set of uplink carriers for transmissions UCI based at least in part on the indication, means for selecting a subset of the uplink carriers for UCI transmissions, wherein the subset comprises fewer uplink carriers than the set of uplink carriers for UCI, and means for transmitting UCI using the subset of uplink carriers.

[026] Other equipment for wireless communication is described. Equipment may include a processor, memory in electronic communication with the processor, and instructions stored in memory. The instructions may be operable to cause the processor to transmit an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, receive a carrier configuration that includes a set of uplink carriers for UCI transmissions based at least in part on the indication, select a subset of the uplink carriers for UCI transmissions, where the subset comprises fewer uplink carriers than the set of uplink carriers for UCI, and transmit UCI using the subset of uplink carriers.

[027] A non-transient computer-readable medium for wireless communication is described. The non-transient computer-readable medium may include instructions operable to cause a processor to transmit an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, receive a carrier configuration that includes a set of uplink carriers for UCI transmissions based at least in part on the indication, select a subset of the uplink carriers for UCI transmissions, where the subset comprises fewer uplink carriers than the set of uplink carriers for UCI, and transmit UCI using the subset of uplink carriers.

[028] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for identifying a local condition of a user equipment (UE), in which the subset of the carriers uplink can be selected by the UE based at least in part on the local condition of the UE.

[029] In some examples of the method, equipment, and non-transient computer-readable medium described above, the local condition comprises a power consumption condition of the UE, a power tolerance condition of the UE, an interference profile of neighboring devices to the UE or a concurrent transmission condition.

[030] In some examples of the method, equipment, and non-transient computer-readable medium described above, the UCI comprises feedback to a plurality of downlink carriers of the carrier configuration. In some examples of the method, equipment, and non-transient computer-readable medium described above, the UCI comprises a downlink carrier indicator of the carrier configuration.

[031] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for receiving an indication of the subset of uplink carriers from a base station, in which the subset of uplink carriers can be selected at least in part in the received indication. In some examples of the method, equipment, and non-transient computer-readable medium described above, the received indication may be received via radio resource control (RRC) signaling or in a resource grant.

[032] Some examples of the method, equipment and non-transient computer-readable medium described above may further include processes, facilities, means or instructions for receiving a payload configuration for the UCI, wherein the payload configuration comprises an indication by the least one of HARQ feedback, a programming request (SR), channel state information (CSI), a ranking indicator (RI), a precoding matrix indicator (PMI), or a hidden node interference indicator.

[033] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for receiving a downlink control message. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for identifying a network of facilities for transmitting the UCI based at least in part on the downlink control message and a or more additional parameters.

[034] In some examples of the above-described method, equipment, and non-transient computer-readable medium, the resource interleaving comprises at least one of a cyclic shift or Walsh code index. In some examples of the method, equipment, and non-transient computer-readable medium described above, one or more additional parameters comprise at least one of a control channel element (CCE) of a downlink common physical control channel (C-PDCCH) or an indicator received via radio resource control (RRC) signaling.

[035] A wireless communication method is described. The method may include receiving an indication of a number of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, transmitting a carrier configuration that includes a set of UCI carriers based on at least in part in the indication, and receive UCI using a subset of uplink bearers.

[036] An equipment for wireless communication is described. The equipment may include means for receiving an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, means for transmitting a carrier configuration that includes a set of UCI carriers based on at least in part in the indication, and means for receiving UCI using a subset of uplink bearers.

[037] Other equipment for wireless communication is described. Equipment may include a processor, memory in electronic communication with the processor, and instructions stored in memory. The instructions may be operable to cause the processor to receive an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, transmit a carrier configuration that includes a set of carriers from UCI based at least in part on the indication, and receive UCI using a subset of uplink bearers.

[038] A non-transient computer-readable medium for wireless communication is described. The non-transient computer-readable medium may include instructions operable to cause a processor to receive an indication of a number of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, transmit a carrier configuration that includes a set of UCI bearers based at least in part on the indication, and receive UCI using a subset of uplink bearers.

[039] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for selecting a subset of uplink carriers for UCI transmissions, where the subset comprises fewer uplink carriers than the set for UCI transmissions. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for transmitting a subset indication to a UE.

[040] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions to identify at least one of a channel quality for the UE, a power tolerance report of the UE, or a past history of successful listen-before-talk (LBT) by the UE, where the subset of uplink carriers may be selected based at least in part on identification. In some examples of the method, equipment, and non-transient computer-readable medium described above, the subset indication comprises RRC signaling or in a resource grant.

[041] Some examples of the method, equipment and non-transient computer-readable medium described above may also include processes, resources, means or instructions for transmitting a downlink control message. Some examples of the method, equipment, and non-transient computer-readable medium described above may also include processes, facilities, means, or instructions for identifying a resource pool for the UCI based at least in part on the downlink control message and one or more plus additional parameters.

[042] In some examples of the above-described method, equipment, and non-transient computer-readable medium, the resource interleaving comprises at least one of a cyclic shift or Walsh code index. In some examples of the method, equipment, and non-transient computer-readable medium described above, one or more additional parameters comprise at least one of a CCE of a C-PDCCH or an indicator received via RRC signaling.

BRIEF DESCRIPTION OF THE DRAWINGS

[043] FIG. 1 illustrates an example of a system for wireless communication that supports hybrid automatic repeat request (HARQ) feedback in the unlicensed radio frequency (RF) spectrum in accordance with various aspects of the present disclosure;

[044] FIG. 2 illustrates an example of a wireless communication system that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure;

[045] FIG. 3 illustrates examples of the transmission opportunities (TxOPs) that support HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure;

[046] FIGs. 4 and 5 illustrate examples of process flows in a system that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure;

[047] FIGs. 6-8 show block diagrams of a device that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure;

[048] FIG. 9 illustrates a block diagram of a system including a user equipment (UE) that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure;

[049] FIGs. 10 to 12 show block diagrams of a device that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure;

[050] FIG. 13 illustrates a block diagram of a system including a base station that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure; It is

[051] FIGs. 14-17 illustrate methods for HARQ feedback in the unlicensed RF spectrum in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

[052] A user equipment (UE) can use different modes to manage hybrid automatic repeat request (HARQ) feedback, and the various modes can be accounted for or activated based on the operating conditions of a system using a spectrum band shared or unlicensed radio frequency (RF) technology. In some cases, a shared spectrum band may refer to spectrum that is licensed lightly and/or in which there may be some level of coordination between communications from different radio access technologies (RATs) or some level of preference given to communications from a specific RAT, such as an acting RAT, for example. In other cases, a shared spectrum band can generally refer to spectrum in which different RATs co-exist or operate within the same RF spectrum band, which can include loosely licensed/coordinated spectrum or, alternatively, purely unlicensed spectrum in which different RATs can freely compete for access to the channel medium using various channel contention techniques. Aspects described in the present disclosure may be applicable to various shared or unlicensed spectrum regimes. Accordingly, the terms shared spectrum and unlicensed spectrum are used interchangeably herein, unless otherwise noted.

[053] While operating in the unlicensed RF spectrum band, a UE may send feedback messages for data received from the base station. However, a UE may be able to transmit feedback using a variety of different techniques, and transmissions based on these techniques may introduce a number of redundancies and result in increased operational uncertainty within the system. Such redundancies and uncertainties can negatively affect the efficiency of communication. Consequently, the UE can use techniques, as described in more detail below, that are based on certain channel conditions or wireless medium conditions to solve the potential problems described above.

[054] For example, HARQ feedback can be transmitted autonomously for predefined resources (for example, a special subframe) or, in some cases, HARQ feedback can be requested from a UE to one or several HARQ processes . Requested feedback may be called surveyed feedback or request-based feedback, and autonomous feedback may be called unsurveyed feedback. Polled and non-polled feedback can be transmitted using different physical channels and can be grant-based or triggered without an explicit grant. Buffers for polled and unpolled feedback can be maintained and managed separately.

[055] HARQ feedback can be transmitted using one or multiple physical channels. For example, a UE may transmit uplink control information (UCI) using a short physical uplink control channel (sPUCCH), an enhanced physical uplink control channel (ePUCCH), or a physical uplink shared channel (PUSCH). The use of different control channels can be based on signals received from a base station, as a trigger, or a grant that allows a UE to transmit to the base station during a transmission opportunity (TxOP). However, prioritization associated with different channels and potential UCI overlap across different channels can result in complex scheduling and feedback processes. Consequently, the feedback channel used by each UE, or group of UEs, can be different, and there is a possibility of redundancy and ambiguity related to the different ways in which the UCI can be transmitted on various channels. Examples of such redundancy and ambiguity are described in greater detail below with respect to FIG. 1.

[056] Some wireless communications systems may use different feedback operations, such as polled operation (for example, where a base station explicitly directs a UE to provide feedback using a certain channel) and unpolled operation (for example, where a UE provides feedback autonomously and the base station does not explicitly tell the UE when to provide feedback). To avoid unwanted redundancy and ambiguity, a wireless communication system can use certain channels for both polled and non- polled operation. Separate HARQ buffers can also be maintained for unattended and polled operations, and these buffers can be cleared based on both polled and non-fetched operations.

[057] Techniques may also allow optimization of UE power usage and/or LBT success when transmitting HARQ feedback. The UE can indicate that it is capable of using a certain number of uplink carriers and that a base station can configure the UE to transmit the UCI on a set of uplink carriers. Based on power consumption requirements and an interference profile of neighboring UEs, the UE can determine a subset of uplink carriers to transmit the UCI.

[058] The aspects of the disclosure introduced above are described below in the context of a wireless communication system. Additional examples are given to illustrate different physical channels used for UCI transmission including HARQ feedback. Aspects of the disclosure are further illustrated and described with reference to equipment diagrams, system diagrams and flowcharts which relate to HARQ feedback in the unlicensed RF spectrum.

[059] FIG. 1 illustrates an example of a wireless communication system 100 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Wireless communication system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, wireless communication system 100 may be a Long Term Evolution (LTE) or LTE-Advanced (LTE) network. -A). Wireless communications system 100 can provide efficient HARQ feedback using feedback operations that allow clearing feedback from a buffer.

[060] The wireless communication system 100 may include an LTE/LTE-A network, a MuLTEFire network, a small network of neutral host cells or the like, operating with overlapping coverage areas 110. A MuLTEFire network may include access points (APs) and/or base stations 105 that communicate in an unlicensed RF spectrum band, for example, without a licensed frequency anchor carrier. For example, the MuLTEFire network can operate without an anchor carrier in the licensed spectrum.

[061] The base stations 105 can communicate remotely with the UEs 115 through one or more antennas of the base station. Each base station 105 may provide communication coverage for a respective geographic coverage area 110. The communication links 125 shown in the wireless communication system 100 may include uplink transmissions from a UE 115 to a base station 105 or downlink transmissions to from a base station 105 to a UE 115. The UEs 115 can be dispersed throughout the wireless communication system 100, and each UE 115 can be stationary or mobile. A UE 115 may also be referred to as a mobile station, a subscriber station, a remote unit, a wireless device, an access terminal (AT), a mobile device, a user agent, a client, or similar terminology. A UE 115 can also be a cell phone, wireless modem, handheld device, personal computer, tablet, personal electronic device, machine-type communication device (MTC), etc.

[062] The base stations 105 can communicate with the core network 130 and with each other. For example, base stations 105 may interface with core network 130 through backhaul channel links 132 (eg, SI, etc.). Base stations 105 may communicate with each other over backhaul links (eg, X2, etc.) either directly or indirectly (eg, through core network 130). Base stations 105 can perform radio configuration and programming for communication with UEs 115 or can operate under the control of a base station controller (not shown). In some examples, base stations 105 can be macro cells, small cells, hotspots, or the like. Base stations 105 may also be referred to as eNodeBs (eNBs) 105.

[063] HARQ can be a method of ensuring that data is received correctly over a wireless communication link 125. HARQ can include a combination of error detection (eg, using a cyclic redundancy check (CRC)), forward error correction (FEC) and retransmission (for example, using an automatic retry request (ARQ)). HARQ can improve throughput at the media access control (MAC) layer under poor radio conditions (eg, signal-to-noise conditions). In Incremental Redundancy HARQ, incorrectly received data can be buffered and combined with subsequent transmissions to improve the overall probability of successfully decoding the data. In some cases, redundancy bits are added to each message before transmission. This can be useful in poor conditions. In other cases, the redundancy bits are not added to each transmission, but are retransmitted after the sender of the original message receives a negative acknowledgment (NACK) indicating a failed attempt to decode the information. The chain of transmit, reply, and retransmit can be referred to as an HARQ process. In some cases, a limited number of HARQ processes may be used for a given communication link 125.

[064] A physical uplink control channel (PUCCH) may be used for uplink acknowledgments (ACKs), schedule requests (SRs), channel quality indicators (CQIs), and other UCIs. A PUCCH can be mapped to a control channel defined by a code and two consecutive resource blocks. Uplink control signaling can depend on the presence of timing synchronization for a cell. PUCCH resources for SR and CQI reports can be assigned (and revoked) through radio resource control (RRC) signaling. In some cases, resources for SR can be assigned after synchronization is acquired through a Random Access Channel (RACH) procedure. In other cases, an SR may not be assigned to a UE 115 via the RACH (ie, synchronized UEs may or may not have a dedicated SR channel). PUCCH resources for SR and CQI may be lost when the UE is no longer synchronized.

[065] The wireless communication system 100 can support uplink transmission using an ePUCCH. An ePUCCH can include resources from portions of several resource blocks. For example, the ePUCCH can be interleaved with other transmissions within resource blocks. In some cases, ePUCCH transmissions from multiple UEs 115 may be interleaved within a set of resource blocks.

[066] The wireless communication system 100 may also support a shortened control channel, which may be referred to as a short duration PUCCH or sPUCCH. An sPUCCH can use an interleaving structure similar to the ePUCCH, but can include resources from a smaller number of resource blocks. For example, sPUCCH can use resources of four or fewer OFDM (Orthogonal Frequency Division Multiplexing) symbols. In some examples, UE 115 may transmit an sPUCCH using a special subframe (e.g., a subframe that allows switching from downlink to uplink scheduling, or vice versa), and base station 105 may use a common physical downlink control channel. (C-PDCCH) to dynamically indicate the presence of the special subframe to a UE 115. The ability of the UE 115 to transmit a control message using the shortened control channel may be indicated by the presence of a downlink message (e.g., a grant downlink, etc.) from base station 105. In some cases, the control message may be transmitted in unlicensed spectrum using a channel that includes multiple subbands, such as an 80 MHz channel comprising four 20 MHz bands.

[067] In some cases, a UE 115 or base station 105 may operate in a shared or unlicensed RF spectrum. These devices can perform a listen-before-talk (LBT) procedure such as a clear channel assessment (CCA) prior to communication to determine if the channel is available. A CCA can include a power detection procedure to determine if there are other active transmissions. For example, the device may infer that a change in a received signal strength indicator (RSSI) from a power meter indicates that a channel is busy. Specifically, signal power that is concentrated within a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA can also include detection of specific sequences that indicate channel usage. For example, another device may transmit a specific preamble before transmitting a data stream.

[068] A wireless device using a radio access technology (RAT), such as LTE/LTE-A, can operate as an independent carrier in multiple bands of shared or unlicensed RF spectrum. As a result, the wireless device can use techniques from one RAT (eg, LTE/LTE-A) to improve upon those used by a different RAT that also communicates within the unlicensed RF spectrum, such as Wi-Fi. For example, HARQ feedback processes can be used by wireless devices to allow efficient communication over unlicensed RF spectrum, where the HARQ feedback can be stored in a buffer to be made available for retransmission.

[069] Wireless devices operating in the shared or unlicensed RF spectrum may use different channels to transmit control information. For example, a UE 115 can transmit UCI using a sPUCCH (e.g., a control channel that is less than one subframe in duration), an ePUCCH, or a PUSCH. The use of different control channels can be based on signals received from a base station 105, such as a trigger, or a grant that allows a UE 115 to transmit to the base station 105 during a TxOP.

[070] HARQ feedback transmissions in unlicensed spectrum can be affected by a number of factors, including factors associated with the number of different channels used to transmit HARQ feedback (such as feedback timing, impact of LBT processes, and feedback buffer management). In addition, multi-carrier operation for uplink and downlink transmissions, payload size management (e.g. mapping, compression, etc.), payload mapping (e.g. mapping HARQ, channel state information (CSI ) and SR for a channel) and control channel resource allocation (such as resource allocation for a PUCCH) can also factor into the transmission of HARQ feedback in the unlicensed RF spectrum.

[071] However, in some cases, a prioritization associated with different channels and a potential overlap of control information, such as UCI on different channels, can result in complex programming and feedback processes. For example, an sPUCCH transmission might not be grant-based and instead might trigger implicitly based on detection of a C-PDCCH. A sPUCCH can also carry an ACK or NACK for subframes that satisfy a HARQ feedback timeline (for example, an N+4 timeline, where N is the subframe on which a specific downlink transmission is received and HARQ feedback for that particular downlink transmission at least 4 subframes later are provided), and further ACK/NACK messages may be transmitted at the next sPUCCH opportunity (e.g., during a subsequent TxOP). Similarly, the ePUCCH can be uplink grant based or C-PDCCH firing based, and both ePUCCH and sPUCCH can be triggered by UE 115, by UE group 115, or by all UEs 115. UCI in a PUSCH can be based on the uplink grant and the specific UE 115. Consequently, the feedback channel used by each UE 115, or group of UEs 115, can be different, and there is a possibility of redundancy and ambiguity related to the different ways in which the UCI can be transmitted on various channels. In some cases, a trigger for UCI on ePUCCH and UCI on PUSCH might be a common trigger, for example in an uplink lease. The uplink grant may contain bits indicating where the UCI should be sent (eg using ePUCCH, PUSCH or both) where the features (eg subframes) for UCI feedback may be the same or different for ePUCCH and PUSCH.

[072] As an example of the ambiguity encountered when a number of channels can be used for feedback, a first UE 115 may send UCI using a PUSCH, where a second UE 115 may not have a PUSCH grant, and one or both of the UEs 115 can be triggered to send sPUCCH. However, it may not be clear whether the first UE 115 should repeat a UCI transmission on sPUCCH if it has already transmitted the UCI. Additionally, there may not be a clearly defined precedence rule between different channels, and it may not be clear whether a UE 115 should retain feedback buffers after UCI transmission (eg, to repeat on another channel). In another example, HARQ feedback can be based on a HARQ process identity (ID), which can be implicitly or explicitly signaled. In the case of repeated transmissions of HARQ feedback from a UE 115, a base station 105 may reuse previously recognized HARQ process IDs when scheduling new transmissions. In such cases, UE 115 may be tasked with ensuring that ambiguity is avoided, for example by determining the correct HARQ feedback associated with the reused HARQ process ID. In an example illustrating redundancy in feedback transmissions, ACK/NACKs for certain subframes can be transmitted on a first TxOP using sPUCCH, whereupon other ACK/NACKs are transmitted on a subsequent TxOP using another sPUCCH. An intervening ePUCCH/PUSCH transmission that includes these same ACK/NACKs can lead to redundant feedback in the system.

[073] In this way, the wireless communications system 100 can operate in unlicensed RF spectrum and use different modes for managing HARQ feedback and clearing feedback buffers. For example, a wireless device may receive downlink data from a base station 105 during a TxOP and transmit HARQ feedback within the same TxOP or a subsequent TxOP. Upon transmission of the HARQ feedback and during a TxOP, the wireless device may determine to clear a buffer based on receipt of an indication from the base station 105. The base station 105 may transmit the indication after receiving the HARQ feedback and may indicate or identify the HARQ feedback to be cleared from the buffer, or the buffer to be cleared, within the statement. Additionally or alternatively, the buffer can be cleared automatically based on the feedback transmission. In some examples, the wireless device may indicate an ability to support uplink carriers and, in response, receive a carrier configuration. The wireless device can select a subset of uplink carriers for feedback transmissions and transmit feedback using the subset.

[074] FIG. 2 illustrates an example of a wireless communication system 200 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Wireless communication system 200 may include base stations 105-a with a corresponding coverage area 110-a, and UR 115-a, which may be examples of a base station 105, coverage area 110, and UE 115 as described with reference to FIG. 1. The wireless communication system 200 can support the use of separate HARQ feedback buffers and different channels for efficient HARQ feedback. Additionally, the wireless communication system 200 can use different feedback operations, such as polled operation (e.g., where base station 105-a explicitly directs UE 115-a to provide feedback on a certain channel, such as an ePUCCH) and unpolled operation (for example, where a UE 115-a provides feedback autonomously and the base station does not explicitly tell the UE 115-a when to provide feedback).

[075] To resolve programming complexity due to ambiguity and redundancy, as discussed above, the wireless communication system 200 may use certain channels (e.g., trigger-based spucch, epucch, or epusch) for unpolled operation and other channels (e.g. ePUCCH) for searched operation. For example, for a downlink data transmission received during the TxOP 205, the UE 115-a may transmit the HARQ feedback using different channels within subframes 210, where the type of channel used (e.g., a lease-based or lease-based on trigger) may depend on the searched or unsearched operation described above. Separate buffers for HARQ feedback can also be maintained for unattended and polled operations. In some examples, when a trigger-based channel or a grant-based channel is scheduled, UE 115-a may send the available HARQ feedback at the earliest opportunity (e.g., on subframe N+4 or later).

[076] When communicating in unlicensed RF spectrum, there may be an increased likelihood that a feedback transmission is lost due to LBT glitches and/or interference. As a result, the use of polled operation can be used to request UE 115-a to transmit the missing HARQ feedback. That is, base station 105-a may provide an uplink grant for a lease-based channel (eg an uplink grant for ePUCCH) which further indicates a subset of HARQ feedback to be retransmitted by UE115-a. The HARQ feedback subset can be specified with a limited granularity to limit an uplink grant size. In some cases, to allow retransmission of HARQ feedback, UE 115-a may maintain a separate HARQ buffer for polled operation until base station 105-a provides a trigger to UE 115-a that indicates that the HARQ buffer can be cleaned. In this way, the UE 115-a can store the HARQ feedback that was identified as lost for possible repeated retransmissions, in case the HARQ feedback is lost again. Buffers for unpolled operation can be cleared immediately after transmission. In such cases, the HARQ feedback may be erased because it cannot be used again in unpolled operation and may instead be later stored in a buffer for polled operations if the base station 105-a indicates that the unpolled HARQ feedback was not received correctly. In some cases, HARQ feedback serving a timeline is transmitted, while other ACK/NACK bits are transmitted at the next similar opportunity (i.e., a next unpolled HARQ feedback opportunity for unpolled HARQ operation and a next unpolled opportunity HARQ feedback loop for searched operation).

[077] In some examples, a trigger-based channel (e.g., sPUCCH or PUSCH) may be used for unpolled HARQ feedback, and a grant or trigger-based channel (e.g., ePUCCH, trigger- or grant-based) may be used. used for searched operation. In these cases, when using the polled operation, a previous pending ACK/NACK “K” is transmitted through the ePUCCH, a first “K” ACK/NACK since the last ePUCCH buffer clear may be transmitted, or an uplink grant for ePUCCH may be transmitted. specify the missing ACK/NACKs to be transmitted. As mentioned above, separate buffers with HARQ feedback may be maintained for polled and unpolled operation, where buffers for unpolled operation may be cleared immediately after transmission, and buffers for polled operation are cleared after an explicit indication from the base station is received.

[078] In some cases, base station 105-a cannot implement polling operations to request retransmission of missing feedback transmissions. Instead, UE1-15-a can transmit HARQ feedback (e.g. on an unpolled operation) on the first available (and configured) uplink channel, e.g. whether it is sPUCCH or ePUCCH (trigger or grant based) or PUSCH. In such cases, a common buffer can be used for HARQ feedback based on sPUCCH, ePUCCH and PUSCH, and the buffer can be cleared on an explicit base station indication to do so and/or completion of a certain fixed time duration.

[079] The HARQ feedback for unpolled operation may be associated with an implicit HARQ process ID indication (for example, an ith bit of HARQ corresponds to a HARQ process ID of j without loss of generality (for example, semi-static mapping)). Additionally or alternatively, if a HARQ process ID is not programmed, the HARQ feedback can be set to NACK by default. In some cases, the HARQ feedback for the searched operation on an uplink lease may include an explicit indication of the HARQ process ID. Based on this explicit indication, the base station 105-a can identify a bitmap per HARQ process ID or a set of HARQ process IDs, for which to request ACK/NACK feedback. The programming of HARQ process IDs by the base station 105-a can be a programming decision, where unrecognized HARQ process IDs can be polled or new data can be transmitted.

[080] In some cases, HARQ feedback transmissions related to multi-carrier operation may be enhanced. For example, if UE 115-a supports N uplink carriers, a wireless communication system may allow UE 115-a to send HARQ ACK on all carriers simultaneously, subject to a configuration of the base station 105-a. As an example, multi-carrier support may be applicable to ePUCCH and sPUCCH transmissions. However, configuring the HARQ feedback for M downlink carriers to be transmitted on the N uplink carriers, where M > N, may inflate the transmission payload of the control channel and therefore affect the coverage range of the uplink transmission. For example, when M = 4 and N = 1, the coverage range can be reduced by up to 6 dB, which can have a significant impact for UEs 115 located at an edge of the cell. However, multi-carrier operation can provide the benefit of aggregating all downlink HARQs into a subset of uplink carriers, allowing efficiency and power savings on some uplink carriers (which may not be activated for uplink control signaling only). In some cases (for example, when configuring HARQ feedback for M downlink carriers when M > N), transmitting feedback on more than one uplink carrier can incur redundancy of UCI information across multiple carriers, which can influence power consumption. energy on UE 115-a. However, this redundancy can provide the benefit of increasing the success of the LBT of UCI transmissions to UE 115-a.

[081] The wireless communication system 200 can manage the exchange of increasing LBT success and energy consumption dynamically. For example, the wireless communication system 200 can be directed towards optimization of UE power usage or LBT success. In such cases, UE 115-a may indicate that it is capable of using N uplink carriers, which may be a static number of carriers. Base station 105-a may configure UE 115-a to transmit the UCI up to N1 uplink carriers, where N1 < N. In some cases, base station 105-a may base the configuration on power consumption requirements, a interference profile of neighboring UEs 115 (eg, for LBT success), a power tolerance of UE 115-a, or simultaneous transmissions on several channels (eg, PUCCH on some channels and PUSCH on others). UE 115-a may determine a subset of uplink carriers N_2 to transmit UCI. In some cases, each uplink carrier may contain HARQ feedback for all downlink carriers, and N2 may not be explicitly specified by UE 1 15-a. If each uplink carrier contains HARQ feedback for a subset of downlink carriers, then the control channel payload may include a field to indicate the number and index of component carriers (CCs) for which the HARQ feedback is carried in the payload. useful.

[082] In some cases, there may be an optimization for coverage and scheduling in the wireless communications system 200. That is, UE 115-a may indicate an ability to use N uplink carriers and, considering a range of coverage and scheduling requirements for UE 115-a, base station 105-a may semi-statically configure a subset of N uplink carriers, where N1 < N. Base station 105-a may also consider UE power consumption and success history previous LBT on each uplink carrier. In some cases, a semi-static configuration of N carriers per UE 115 may be indicated through RRC signaling. Additionally or alternatively, there may be a dynamic configuration of N carriers per UE 115, as indicated by means of a grant, as in cases where a channel used for feedback is grant-based.

[083] Payload mapping (eg, HARQ, CSI, and SR mapping) can also be used to improve the transmission of HARQ feedback. In some examples, ePUCCH and sPUCCH can transmit HARQ feedback; an SR; or CSI, which may include a ranking indicator (RI) and a precoding matrix indicator (PMI); or a combination thereof. In some cases, a payload can be configured for multiple carriers, and a field carrying a hidden node interference indication can also be included in the UCI. In such cases, the field may indicate that one or more NACKs were caused due to hidden node interference that is unknown to the base station 105-a.

[084] In some cases, one or more of the indicator fields may be present, depending on the configuration of a base station, and different channels may use different configurations. For example, an sPUCCH can use a semi-static configuration, while an ePUCCH can use a semi-static configuration or an explicit grant statement. For example, some indication bits can be used to configure the UE115-a to transmit either HARQ feedback, CSI feedback, or both, including variations of an RI (eg, Rank1 and Rank2) for a reported rank value. Additionally, the encoding order can follow a CC encoding, with CSI and HARQ encoded as configured by CC.

[085] A channel resource index can be used to improve communication of control channels in unlicensed spectrum. For example, a PUCCH resource index table can be used to identify PUCCH resources derived as a function of a PDCCH departure control channel (CCE) element, a PUCCH offset, a resource block (RB) allocation, or a combination thereof. In some cases, a resource may refer to an interleave allocated for uplink control channel transmissions (eg, PUCCH) and a cyclic shift index/Walsh code used for multiplexing within the same interleave. For a lease-based channel such as ePUCCH, channel resources can be derived based on an initial CCE of an uplink lease and other semi-static parameters. Additionally or alternatively, for trigger-based channels (e.g. sPUCCH/ePUCCH), resources can be derived using an initial CCE of a downlink grant and other semi-static parameters or an initial CCE of a downlink grant and an initial CCE of a C-PDCCH and other semi-static parameters.

[086] FIG. 3 illustrates examples of TxOPs 300 that support HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. In some cases, TxOPs 300 may represent aspects of communications between a UE 115 and base station 105 as described with reference to FIGs. 1 and 2. TxOPs 300 illustrate multiple TxOPs 305 that allow transmission of HARQ feedback using different channels according to an operating mode.

[087] A TxOP 305 may include a radio frame 310 that includes a number of downlink subframes 315 scheduled for downlink transmissions, special subframes 320 and uplink subframes 325 scheduled for uplink transmissions. These subframes can be used to carry control channels or shared to facilitate the transmission of grants, triggers and feedback messages. For example, a downlink subframe 315 may include an uplink grant used by a UE 115 to transmit HARQ feedback using an sPUCCH or ePUSCH in a special subframe 320 or an uplink subframe 325, respectively. Likewise, a trigger can be included in a downlink subframe 315 to allow HARQ feedback on a sPUCCH included in an uplink subframe 325.

[088] When communicating in unlicensed spectrum, polled and unpaved operations can determine different techniques used by a wireless device for feedback. For example, in polled operation, a base station 105 may explicitly indicate when and how a UE 115 may provide HARQ feedback for downlink data during a TxOP 305. In a non-polled operation, a UE 115 may autonomously send HARQ feedback to the station base 105.

[089] [0089] In some cases polled and unpolled operations can be used to reduce unnecessary redundancy incurred when multiple different channels are used to provide feedback at different times. For example, in unpolled operation, different channels (such as a trigger-based sPUCCH, ePUCCH, or ePUSCH) can be used for HARQ feedback. Additionally or alternatively, the searched operation can use a grant-based ePUCCH. In such cases, a UE 115 may send HARQ feedback 330 at the earliest opportunity.

[090] For example, during a first TxOP 305-a, a UE 115 may receive downlink data during a downlink subframe 315 and provide a HARQ response 330-a using a sPUCCH in the special subframe 320-a based on a trigger. HARQ feedback 330-b for downlink data received during other downlink subframes 315 may be transmitted during a second TxOP 305-b on an sPUCCH in special subframe 320-b. As another example, a UE 115 may receive a trigger to transmit the HARQ response 330-c during an uplink subframe 325. Likewise, the UE 115 may receive a grant during a downlink subframe 315, and the HARQ response 330-c may be provided in an ePUSCH in a 325 uplink subframe. In some cases, the HARQ feedback may be sent during a 325 uplink subframe that is N + 4 subframes of the subframe where the downlink data was received.

[091] After HARQ feedback is transmitted, the HARQ feedback buffers can be cleared. Separate HARQ buffers may be maintained for polled and non-poll operations, and the UE may determine to clear the buffers (e.g., setting ACK/NACK bits to NACK and transmitting when applicable) based on an indication from a base station or autonomously by the UE 115. For example, a UE may clear a buffer by itself when feedback is transmitted using an sPUCCH, while UE 115 may wait for a trigger to clear the buffer when feedback is transmitted using an ePUCCH.

[092] FIG. 4 illustrates an example of a process flow 400 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Process flow 400 may include a UE 115-b and base station 105-b, which may be examples of corresponding devices described with reference to Figs. 1 and 2. Process flow 400 can illustrate examples of efficient HARQ feedback techniques using different feedback operations, such as polled and non-polled (i.e., stand-alone) operations.

[093] At 405, base station 105-b may transmit, and UE 115-b may receive, a downlink data transmission using resources of a shared RF spectrum band during a first TxOP. At 410, UE 115-b may optionally identify a trigger for transmitting additional HARQ feedback. At 415, UE 115-b may transmit the HARQ feedback in response to the downlink data transmission - or, in cases where the trigger has been identified, based on the trigger - during the first TxOP or a second TxOP.

[094] At 420, UE 115-b may optionally receive a request from base station 105-b to transmit HARQ feedback, and at 425, UE 115-b may optionally receive a resource grant for HARQ feedback from base station 105- b. In some cases, the resource grant may include an indication of an identifier for an HARQ process from the HARQ feedback. The request may, in some cases, include a request to retransmit a subset of previously transmitted HARQ feedback.

[095] At 430, UE 115-b may, in cases where it has received the request, transmit HARQ feedback in response to the downlink data transmission and the request. UE 115-b may transmit the HARQ feedback using the resources in response to the request. In an example, at 430, the HARQ feedback transmitted by UE 115-b may be the same HARQ feedback as transmitted at 415, but additionally transmitted in response to the request or trigger, and UE 115-b may clear the additional HARQ feedback of an additional buffer based on transmitting the additional HARQ feedback.

[096] At 435, base station 105-b may optionally transmit, and UE 115-b may receive, an indication to clear a HARQ feedback buffer during the second TxOP or a third TxOP. At 440, UE 115-b may clear the HARQ feedback from the buffer, for example, based on transmitting the feedback or based on receiving the indication to clear the buffer. In some examples, the buffer is associated with a request-based feedback mode and the additional buffer is associated with an autonomous feedback mode. In some examples, the buffer includes a common buffer for an sPUCCH, an ePUCCH, or a PUSCH. Additionally or alternatively, the UE 15-b can determine to clear the buffer according to a predetermined periodicity.

[097] FIG. 5 illustrates an example of a process flow 500 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Process flow 500 may include a UE 15-c and base station 105-c, which may be examples of corresponding devices described with reference to Fig. 1 and 2. Process flow 500 may illustrate examples of efficient UCI transmission in a network. deployment of multiple carriers.

[098] At 505, the UE 115-c may transmit, and the base station 105-c may receive, an indication (e.g., a capacity indication) of a quantity of uplink carriers of a shared RF spectrum band for which UCI streams are supported. For example, the indication may indicate a number of uplink carriers that can support simultaneous UCI transmissions. At 510, the UE 115-c may receive a bearer configuration that includes a set of uplink bearers for UCI transmissions based on the indication. At 515, UE 115-c may identify a local condition, where the local condition may include a power consumption condition of UE 115-c, a power tolerance condition of UE 115-c, an interference profile from neighboring devices UE 115-c, a simulcast condition, or a combination thereof. At 520, base station 105-c can select a subset of uplink carriers for UCI transmissions, where the subset includes less uplink carriers than the set, and at 525, UE 115-c can receive an indication of the subset of carriers base station uplink 105-c. In some cases, the indication is received via RRC signaling or in a resource grant.

[099] At 530, UE 115-c may select a subset of uplink carriers for UCI transmissions, where the subset includes less uplink carriers than the set of uplink carriers for UCI. In some examples, the subset of uplink carriers is selected by UE 115-c based on the local condition. Additionally or alternatively, the subset of uplink carriers may be selected based on the indication received from base station 105-c. At 535, UE 115-c may transmit the UCI to base station 105-c using the uplink carrier subset. In some cases, the UCI includes feedback for a plurality of downlink carriers from the carrier configuration. The UCI may include a downlink carriers indicator of the carrier configuration.

[0100] In some cases, UE 115-c may receive a downlink control message and identify a resource loop to transmit the UCI based on the downlink control message and one or more additional parameters. In some cases, the interweaving of features includes at least one of a Walsh code or cyclic shift index. Additionally or alternatively, the one or more additional parameters may include at least one of a CCE of a C-PDCCH or an indicator received via RRC signaling. In some examples, base station 105-c may transmit, and UE 115-c may receive, a payload configuration for the UCI, where the payload configuration includes an indication of at least one of hybrid HARQ feedback, a SR, CSI, an RI, a PMI, or a hidden node interference indicator.

[0101] FIG. 6 shows a block diagram 600 of a wireless device 605 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Wireless device 605 may be an example of aspects of a UE 115 as described with reference to FIGs. 1 and 2. Wireless device 605 may include receiver 610, a UE HARQ manager 615, and transmitter 620. Wireless device 605 may also include a processor. Each of these components can be in communication with each other (eg, through one or more buses).

[0102] Receiver 610 can receive information, such as packets, user data, and/or control information associated with various information channels (e.g., control channels, data channels, and information related to HARQ feedback in the spectrum of unlicensed RF, etc.). Information can be passed to other device components. Receiver 610 may be an example of aspects of transceiver 935 as described with reference to FIG. 9. In some cases, receiver 610-b may receive a downlink data transmission using shared RF spectrum band resources during a first TxOP. Additionally, receiver 610 may receive a downlink control message.

[0103] The HARQ manager of UE 615 may be an example of aspects of the HARQ manager of UE 915 described with reference to FIG. 9. The HARQ manager of UE 615 may transmit HARQ feedback during the first TxOP or a second TxOP in response to the downlink data transmission. The HARQ manager of UE 615 may determine to clear a buffer of HARQ feedback after transmitting the HARQ feedback (e.g. based on receipt of an indication during the second TxOP or a third TxOP) and may clear the HARQ feedback from the buffer based on in determining to clear the buffer. Additionally, UE HARQ manager 615 can transmit an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, receive a carrier configuration that includes a set of uplink carriers for UCI transmissions based at least in part on the indication, select a subset of the uplink carriers for UCI transmissions, where the subset comprises fewer uplink carriers than the set of uplink carriers for UCI, and transmit UCI using the subset of uplink carriers.

[0104] The transmitter 620 can transmit signals generated by other components of the device. In some examples, transmitter 620 may be collocated with a receiver 610 in a transceiver module. For example, transmitter 620 may be an example of aspects of transceiver 935 as described with reference to FIG. 9. Transmitter 620 can include a single antenna, or it can include an array of antennas. Transmitter 620 may transmit the UCI using the uplink carrier subset. In some cases, the UCI may include feedback for a plurality of downlink carriers from the carrier configuration. In some cases, the UCI includes a downlink carriers indicator of the carrier configuration.

[0105] FIG. 7 shows a block diagram 700 of a wireless device 705 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Wireless device 705 may be exemplary aspects of a wireless device 605 or a UE 115 as described with reference to FIGs. 1, 2, and 6. Wireless device 705 may include receiver 710, a UE HARQ manager 715, and transmitter 720. Wireless device 705 may also include a processor. Each of these components can be in communication with each other (eg, through one or more buses).

[0106] The receiver 710 can receive information such as packets, user data and/or control information associated with various information channels (e.g. control channels, data channels, information related to HARQ feedback in the RF spectrum unlicensed, etc.). Information can be passed to other device components. Receiver 710 may be an example of aspects of transceiver 935 as described with reference to FIG. 9.

[0107] The HARQ manager of the UE 715 may be an example of aspects of the HARQ manager of the UE 615 or the HARQ manager of the UE 915 as described with reference to FIGs. 6 and 9. The HARQ manager of the UE 715 may also include the HARQ component 725, the buffer manager 730, the UCI bearer capacity component 735 and the UCI bearer selection component 740. The HARQ component 725 can transmit HARQ feedback in response to a downlink data transmission during a first TxOP or a second TxOP and transmit additional HARQ feedback based on a trigger.

[0108] Buffer manager 730 may determine to clear a HARQ feedback buffer after transmitting HARQ feedback (eg, based on receipt of an indication to clear the buffer during the second TxOP or a third TxOP). Buffer manager 730 may clear the HARQ feedback from the buffer based on the determination to clear the buffer. In some cases, buffer manager 730 may clear additional HARQ feedback from an additional buffer based on transmission of additional HARQ feedback, or may clear the buffer according to a predetermined periodicity. In some cases, the buffer is associated with a request-based feedback mode and the additional buffer is associated with an autonomous feedback mode. In some examples, the buffer includes a common buffer for an sPUCCH, an ePUCCH, or a PUSCH.

[0109] The UCI bearer capacity component 735 may transmit an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported. The UCI carrier selection component 615 can receive a carrier configuration that includes a set of uplink carriers for UCI transmissions based at least in part on the indication, select a subset of the uplink carriers for UCI transmissions, wherein the subset comprises less uplink carriers than the set of uplink carriers for UCI and transmit UCI using the subset of uplink carriers. In some cases, the UCI carrier selection component 740 may receive an uplink carrier subset indication from a base station, where the uplink carrier subset is selected based on the received indication. In some cases, the received indication is received via RRC signaling or in a resource grant.

[0110] The transmitter 720 can transmit signals generated by other components of the device. In some examples, transmitter 720 may be collocated with a receiver 710 in a transceiver module. For example, transmitter 720 may be an example of aspects of transceiver 935 as described with reference to FIG. 9. Transmitter 720 may include a single antenna, or it may include an array of antennas.

[0111] FIG. 8 shows a block diagram 800 of a UE HARQ manager 815 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. UE HARQ manager 815 may be an example of aspects of a UE HARQ manager 615, a UE HARQ manager 715 or a UE HARQ manager 915 as described with reference to FIGs. 6, 7 and 9. The HARQ manager of UE 815 may include HARQ component 825, buffer manager 830, UCI bearer capability component 835, UCI bearer selection component 840, HARQ trigger component 845 , lookup component 850, grant component 855, location condition component 860, payload configuration component 865, and uplink resource component 870. Each of these modules can communicate directly or indirectly with each other (e.g., through one or more buses).

[0112] HARQ component 825 may transmit HARQ feedback in response to a downlink data transmission during a first TxOP or a second TxOP and transmit additional HARQ feedback based on a trigger. Buffer manager 830 may determine to clear a HARQ feedback buffer after transmission of the HARQ. Buffer manager 830 may clear HARQ feedback from the buffer based on the determination to clear the buffer and may clear additional HARQ feedback from an additional buffer based on transmission of additional HARQ feedback. In some cases, buffer manager 830 may clear the buffer according to a predetermined periodicity. In some cases, the buffer is associated with a request-based feedback mode and the additional buffer is associated with an autonomous feedback mode. In some examples, the buffer includes a common buffer for an sPUCCH, an ePUCCH, or a PUSCH.

[0113] The UCI bearer capacity component 835 may transmit an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported. UCI carrier selection component 840 may receive a carrier configuration that includes a set of uplink carriers for UCI transmissions based on the indication, select a subset of uplink carriers for UCI transmissions, wherein the subset comprises fewer uplink carriers than the set of uplink carriers to UCI and receive an indication of the subset of uplink carriers from a base station, where the subset of uplink carriers is selected based on the indication received. In some cases, the received indication is received via RRC signaling or in a resource grant.

[0114] The HARQ trigger component 845 can identify the trigger for transmitting the additional HARQ feedback and identify a trigger for transmitting the HARQ feedback, where the HARQ feedback is transmitted based, at least in part, on the identification of the trigger. The polling component 850 may receive a request to transmit the HARQ feedback. The grant component 855 may receive a grant of resources for the HARQ feedback, where the HARQ feedback is transmitted using the resources in response to the request. In some cases, the resource grant includes an indication of an identifier for an HARQ process from the HARQ feedback. In some cases, the request includes a request to retransmit a subset of previously transmitted feedback.

[0115] Local condition component 860 can identify a local condition of a UE, where the subset of uplink carriers is selected by the UE based on the local condition of the UE. In some cases, the local condition may include a UE power consumption condition, a UE power tolerance condition, an interference profile from neighboring devices to UE 115-c, a simulcast condition, or a combination thereof. .

[0116] The payload configuration component 865 may receive, a payload configuration for the UCI, where the payload configuration includes an indication of at least one HARQ feedback, an SR, CSI, an RI, a PMI or a hidden node interference indicator. The uplink resource component 870 may identify a resource thread to transmit the UCI based on a downlink control message and one or more additional parameters. In some cases, the interweaving of features includes at least one of a Walsh code or cyclic shift index. In some cases, the one or more additional parameters include at least one of a CCE of a C-PDCCH or an indicator received via RRC signaling.

[0117] FIG. 9 shows a diagram of a system 900 including a device 905 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Device 905 may be exemplary of or include the components of wireless device 605, wireless device 705, or a UE 15 as described above, for example, with reference to FIGs. 1, 2, 6 and 7.

[0118] Device 905 may include components for bidirectional voice and data communications, including components for transmitting and receiving communications, including UE 915 HARQ manager, processor 920, memory 925, software 930, transceiver 935, antenna 940 and controller of I/O 945.

[0119] The processor 920 may include an intelligent hardware device (for example, a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device, a discrete gate logic component or transistor logic, a discrete hardware component, or any combination thereof. In some cases, processor 920 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor 920. Processor 920 may be configured to execute computer-readable instructions stored in memory (e.g., memory 925) to perform various functions (for example, functions or tasks that support HARQ feedback in the unlicensed RF spectrum).

[0120] Memory 925 may include random access memory (RAM) and read-only memory (ROM). Memory 925 may store computer-readable, computer-executable software 930 containing instructions that, when executed, cause processor 920 to perform various functions described herein. In some cases, memory 925 may contain, among other things, a Basic Input-Output System (BIOS) that can control basic hardware and/or software operation, such as interaction with peripheral components or devices.

[0121] Software 930 may include code to implement aspects of the present disclosure, including code to support HARQ feedback in unlicensed RF spectrum. Software 930 may be stored on a non-transient computer readable medium such as system memory or other memory. In some cases, software 930 may not be directly executable by processor 920 but may cause a computer (eg, when compiled and executed) to perform the functions described herein.

[0122] The transceiver 935 can communicate bidirectionally, through one or more antennas 940, with wired links, wirelessly as described above. For example, transceiver 935 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver (eg, a wireless transceiver that is a component of a base station, such as base station 105-d). Transceiver 935 may also include a modem for modulating packets and delivering the modulated packets to antennas 940 for transmission, and for demodulating packets received from antennas 940.

[0123] In some cases, the wireless device may include a single antenna 940. However, in some cases the device may have more than one antenna 940, which may be capable of simultaneously transmitting or receiving multiple wireless transmissions. I/O controller 945 can manage input and output signals to device 905. I/O controller 945 can also manage peripherals not integrated with device 905. In some cases, I/O controller 945 can represent a physical connection or port for an external peripheral. In some cases, the 945 I/O Controller may use an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX® or another known operating system.

[0124] FIG. 10 shows a block diagram 1000 of a wireless device 1005 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Wireless device 1005 may be an example of aspects of a base station 105 as described with reference to FIGs. 1 and 2. Wireless device 1005 may include receiver 1010, a base station HARQ manager 1015, and transmitter 1020. Wireless device 1005 may also include a processor. Each of these components can be in communication with each other (eg, via one or more buses).

[0125] The receiver 1010 can receive information, such as packets, user data, and/or control information associated with various information channels (e.g., control channels, data channels, and information related to HARQ feedback in the spectrum of unlicensed RF, etc.). Information can be passed to other device components. Receiver 1010 may be an example of aspects of transceiver 1335 as described with reference to FIG. 13. Receiver 1010 may receive the UCI using the subset of uplink carriers.

[0126] Base station HARQ manager 1015 may be an example of aspects of base station UE HARQ manager 1315 as described with reference to FIG. 13. Base station HARQ manager 1015 may receive HARQ feedback in response to a downlink data transmission during a first TxOP or a second TxOP, transmit an indication to clear a buffer of HARQ feedback during the second TxOP or a third TxOP, receive an indication of the number of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, and transmit a carrier configuration that includes the set of uplink carriers for UCI based on the indication.

[0127] The transmitter 1020 can transmit signals generated by other components of the device. In some examples, transmitter 1020 may be collocated with a receiver 1010 in a transceiver module. For example, transmitter 1020 may be an example of aspects of transceiver 1335 as described with reference to FIG. 13. Transmitter 1020 can include a single antenna, or it can include an array of antennas. Transmitter 1020 may transmit the downlink data transmission using resources of a shared radio spectrum band during the first TxOP, transmit an additional downlink data transmission based on a determination, transmit a subset indication to a UE, and transmit a message of downlink control.

[0128] FIG. 11 shows a block diagram 1100 of a wireless device 1105 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Wireless device 1105 may be an example of aspects of a wireless device 1005 or a base station 105 as described with reference to FIGs. 1, 2, and 10. Wireless device 1105 may include receiver 1110, a base station HARQ manager 1115, and transmitter 1120. Wireless device 1105 may also include a processor. Each of these components can be in communication with each other (eg, via one or more buses).

[0129] The receiver 1110 can receive information such as packets, user data and/or control information associated with various information channels (e.g. control channels, data channels, information related to HARQ feedback in the RF spectrum unlicensed, etc.). Information can be passed to other device components. Receiver 1110 may be an example of aspects of transceiver 1335 as described with reference to FIG. 13.

[0130] Base station HARQ manager 1115 may be an example of aspects of base station UE HARQ manager 1315 as described with reference to FIG. 13. Base station HARQ manager 1115 may also include HARQ component 1125, clear indication component 1130 and UCI bearer component 1135.

[0131] The HARQ component 1125 can receive HARQ feedback in response to a downlink data transmission during a first TxOP or a second TxOP, receive additional HARQ feedback based on a trigger, and determine that an identifier for a HARQ process associated with the transmission downlink data is not recognized, where a HARQ feedback request is transmitted based on the determination.

[0132] Clear indication component 130 may transmit an indication to clear a HARQ feedback buffer during the second TxOP or a third TxOP. In some examples, the buffer includes a common buffer for an sPUCCH, an ePUCCH, or a PUSCH. The UCI bearer component 1135 can receive an indication of a number of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported, transmit a carrier configuration that includes a set of uplink carriers for UCI based in the statement, and select a subset of the uplink carriers for UCI transmissions, where the subset includes less uplink carriers than the set for UCI transmissions. In some cases, the subset indication includes RRC signaling or a resource grant.

[0133] The transmitter 1120 can transmit signals generated by other components of the device. In some examples, transmitter 1120 may be collocated with a receiver 1110 in a transceiver module. For example, transmitter 1120 may be an example of aspects of transceiver 1335 as described with reference to FIG. 13. Transmitter 1120 can include a single antenna, or it can include an array of antennas.

[0134] FIG. 12 shows a block diagram 1200 of a base station HARQ manager 1215 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Base station HARQ manager 1215 may be an example of aspects of a base station HARQ manager 1015, 1115 or 1315 as described with reference to FIGs. 10, 1, 1 and 13. Base station HARQ manager 1215 may include HARQ component 1225, clear indication component 1230, UCI bearer component 1235, HARQ trigger component 1240, HARQ search component 1245, grant component 1250, selection parameter component 1255, and uplink resource component 1260. Each of these modules can communicate directly or indirectly with each other (eg, over one or more buses).

[0135] HARQ component 1225 may receive HARQ feedback in response to a downlink data transmission during a first TxOP or a second TxOP and may receive additional HARQ feedback based on a trigger. HARQ component 1225 may also determine that an identifier for a HARQ process associated with the downlink data transmission is not recognized, whereupon the request for HARQ feedback is transmitted based, at least in part, on the determination.

[0136] Clear indication component 1230 may transmit an indication to clear a feedback buffer during the second TxOP or a third TxOP. In some examples, the buffer includes a common buffer for an sPUCCH, an ePUCCH, or a PUSCH. The UCI bearer component 1235 can receive an indication of a number of uplink carriers from a shared RF spectrum band for which UCI transmissions are supported, transmit a carrier configuration that includes a set of uplink carriers for UCI based in the statement, and select a subset of the uplink carriers for UCI transmissions, where the subset includes less uplink carriers than the set for UCI transmissions. In some cases, the subset indication includes RRC signaling or a resource grant.

[0137] The HARQ trigger component 1240 can identify a trigger for additional HARQ feedback. The HARQ Lookup component 1245 may transmit a request for HARQ feedback. Grant component 1250 may transmit a grant of resources for HARQ feedback, where the HARQ feedback is transmitted using the resources in response to the request. The selection parameter component 1255 can identify at least one channel quality for the UE, a report of the power tolerance of the UE, or a past history of LBT success by the UE, where the subset of the uplink carriers is selected based on the identification.

[0138] The uplink resource component 1260 may identify a resource loop for the UCI based on a downlink control message and one or more additional parameters. In some cases, the interweaving of features includes at least one of a Walsh code or cyclic shift index. In some cases, the one or more additional parameters include at least one of a CCE of a C-PDCCH or an indicator received via RRC signaling.

[0139] FIG. 13 shows a diagram of a system 1300 including a device 1305 that supports HARQ feedback in the unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Device 1305 may be an example of or include the components of wireless device 1005, a wireless device 1105, or a base station 105 as described above, for example, with reference to FIGs. 1, 2, 10 and 11.

[0140] Device 1305 may include components for bidirectional voice and data communications, including components for transmitting and receiving communications, including base station HARQ manager 1315, processor 1320, memory 1325, software 1330, transceiver 1335, antenna 1340, communication network manager 1345 and a base station communication manager 1350.

[0141] The processor 1320 may include an intelligent hardware device (for example, a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete or logic gate component transistor, a discrete hardware component, or any combination thereof. In some cases, processor 1320 can be configured to operate a memory array using a memory controller. In other cases, a memory controller can be integrated into processor 1320 Processor 1320 may be configured to execute computer-readable instructions stored in memory 1325 to perform various functions (e.g., functions or tasks that support HARQ feedback in the unlicensed RF spectrum).

[0142] Memory 1325 may include RAM and ROM. Memory 1325 may store computer-readable, computer-executable software 1330 containing instructions that, when executed, cause processor 1320 to perform various functions described herein. In some cases, memory 1325 may contain, among other things, a BIOS that may control basic hardware and/or software operation, such as interaction with peripheral components or devices.

[0143] Software 1330 can include code to implement aspects of the present disclosure, including code to support HARQ feedback in unlicensed RF spectrum. Software 1330 may be stored on a non-transient computer readable medium such as system memory or other memory. In some cases, software 1330 may not be directly executable by processor 1320 but can cause a computer (eg, when compiled and executed) to perform the functions described herein.

[0144] The transceiver 1335 can communicate bidirectionally, through one or more antennas 1340, with wired links, wirelessly as described above. For example, transceiver 1335 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. Transceiver 1335 may also include a modem for modulating packets and delivering modulated packets to antennas 1340 for transmission, and for demodulating packets received from antennas 1340. In some cases, the wireless device may include a single antenna 1340 However, in some cases the device may have more than one antenna 1340, which may be capable of simultaneously transmitting or receiving multiple wireless transmissions (eg, with UEs 115-d and 115-e).

[0145] The network communication manager 1345 may manage communications with the core network 130-a (eg, over one or more backhaul channel links). For example, the network communications module 1345 can manage data communication transfer to client devices such as one or more UEs 115.

[0146] The base station communication manager 1350 can manage communications with other base stations 105 (e.g., base stations 105-e and 105-f), and can include a controller or scheduler to control communications with UEs 115 in cooperation with other base stations 105. For example, base station communication manager 1350 can coordinate scheduling for transmissions to UEs 115 using various interference mitigation techniques, such as beamforming or co-broadcasting. In some examples, the base station communication manager 1350 may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations 105.

[0147] FIG. 14 shows a flowchart illustrating a method 1400 for feedback HARQ in unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Operations of method 1400 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of method 1400 may be performed by a HARQ manager of the UE as described above with reference to FIGs. 6 to 9 . In some examples, a UE 115 may execute a set of codes to control functional elements of the device to perform the functions described below. Additionally or alternatively, UE 115 may perform aspects of the functions described below using general purpose hardware.

[0148] In block 1405, UE 115 may receive a downlink data transmission using resources of a shared RF spectrum band during a first TxOP. The operations of block 1405 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1405 may be performed by a receiver as described with reference to FIGs. 6 to 9.

[0149] In block 1410, UE 115 may transmit HARQ feedback during the first TxOP or a second TxOP in response to the downlink data. The operations of block 1410 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1410 may be performed by an HARQ component as described with reference to FIGs. 6 to 9.

[0150] In block 1415, the UE 115 can determine to clear a buffer of the HARQ feedback during the second TxOP or a third TxOP after the transmission of the feedback. The operations of block 1415 can be performed according to the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1415 may be performed by a buffer manager as described with reference to FIGs. 6 to 9.

[0151] At block 1420, the UE may clear the HARQ feedback from the buffer based on the determination to clear the buffer. The operations of block 1420 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1420 may be performed by a buffer manager as described with reference to FIGs. 6 to 9.

[0152] FIG. 15 shows a flowchart illustrating a method 1500 for feedback HARQ in unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Operations of method 1500 may be implemented by a base station 105 or components thereof as described herein. For example, operations of method 1500 may be performed by a base station HARQ manager as described above with reference to FIGs. 10 - 13 . In some examples, a base station 105 may execute a set of codes to control functional elements of the device to perform the functions described below. Additionally or alternatively, base station 105 may perform aspects of the functions described below using general purpose hardware.

[0153] In block 1505, base station 105 may transmit a downlink data transmission using resources of a shared RF spectrum band during a first TxOP. The operations of block 1505 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1505 may be performed by a transmitter as described with reference to FIGs. 10 to 13.

[0154] In block 1510, base station 105 may receive HARQ feedback in response to downlink data transmission during the first TxOP or a second TxOP. The operations of block 1510 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1510 may be performed by an HARQ component as described with reference to FIGs. 10 to 13.

[0155] In block 1515, the base station 105 may, in some cases, transmit an indication to clear a feedback buffer during the second TxOP or a third TxOP. The operations of block 1515 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1515 may be accomplished by a clear indication component as described with reference to FIGs. 10 to 13.

[0156] FIG. 16 shows a flow chart illustrating a method 1600 for feedback HARQ in unlicensed RF spectrum, in accordance with various aspects of the present disclosure. The operations of method 1600 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of method 1600 may be performed by a HARQ manager of the UE as described above with reference to FIGs. 6 to 9 . In some examples, a UE 115 may execute a set of codes to control functional elements of the device to perform the functions described below. Additionally or alternatively, UE 115 may perform aspects of the functions described below using general purpose hardware.

[0157] In block 1605, UE 115 may transmit an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported. The operations of block 1605 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1605 may be performed by a carrier capability component UCI as described with reference to FIGs. 6 to 9.

[0158] In block 1610, UE 115 may receive a bearer configuration that includes a set of uplink bearers for UCI transmissions based on the indication. The operations of block 1610 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1610 may be performed by a UCI carrier selection component as described with reference to FIGs. 6 to 9.

[0159] In block 1615, UE 115 can select a subset of uplink carriers for UCI transmissions, where the subset includes less uplink carriers than the set of uplink carriers for UCI. The operations of block 1615 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1615 may be performed by a UCI carrier selection component as described with reference to FIGs. 6 to 9.

[0160] In block 1620, UE 115 may transmit the UCI using the subset of uplink carriers. The operations of block 1620 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1620 may be performed by a transmitter as described with reference to FIGs. 6 to 9.

[0161] FIG. 17 shows a flowchart illustrating a method 1700 for feedback HARQ in unlicensed RF spectrum, in accordance with various aspects of the present disclosure. Operations of method 1700 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of method 1700 may be performed by a base station HARQ manager as described above with reference to FIGs. 10 to 13. In some examples, a base station 105 may execute a set of codes to control functional elements of the device to perform the functions described below. Additionally or alternatively, base station 105 may perform aspects of the functions described below using general purpose hardware.

[0162] In block 1705, base station 105 may receive an indication of a quantity of uplink carriers of a shared RF spectrum band for which UCI transmissions are supported. The operations of block 1705 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1705 may be performed by a UCI carrier component as described with reference to FIGs. 10 to 13.

[0163] In block 1710, base station 105 may transmit a bearer configuration that includes a set of uplink bearers for UCI based on the indication. The operations of block 1710 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1710 may be performed by a UCI carrier component as described with reference to FIGs. 10 to 13.

[0164] In block 1715, base station 105 may receive the UCI using a subset of uplink carriers. The operations of block 1715 may be performed in accordance with the methods described with reference to FIGs. 1 through 5. In certain examples, aspects of the operations of block 1715 may be performed by a receiver as described with reference to FIGs. 10 to 13.

[0165] It should be noted that the methods described above describe possible implementations, and that operations and steps can be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects of two or more of the methods may be combined.

[0166] The techniques described here can be used for various wireless communication systems such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), multiple access carrier frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA) and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system can implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers the IS-2000, IS-95, and IS-856 standards. IS-2000 Versions may be commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Broadband CDMA (WCDMA) and other variants of CDMA. A TDMA system can implement a radio technology such as Global System for Mobile Communications (GSM).

[0167] An OFDMA system can implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM , etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunication System (UMTS). 3GPP LTE and LTE-A are new versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in the organization's documents called “Project Partnership for the 3rd Generation” (3GPP). CDMA2000 and UMB are described in documents from an organization called “Partnership Project for 3rd Generation 2” (3GPP2). The techniques described here can be used for the radio systems and technologies mentioned above as well as other radio systems and technologies. While aspects of an LTE system can be described for example purposes, and LTE terminology can be used in most of the description, the techniques described here are applicable beyond LTE applications.

[0168] In LTE/LTE-A networks, which include those networks described here, the term eNode B can generally be used to describe base stations. The wireless communication system or systems described herein may include a heterogeneous LTE/LTE-A network in which different types of B-nodes provide coverage for different geographic regions. For example, each eNB can provide communication coverage for a macro cell, a small cell, or other types of cells. The term “cell” can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on the context. .

[0169] Base stations may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a B Node, and B Node, Home NodeB, a eNode B Homemade, or some other suitable terminology. The geographic coverage area for a base station can be divided into sectors that make up a portion of the coverage area. The wireless communication system or systems described herein may include base stations of different types (eg macro or small cell base stations). The UEs described herein may be capable of communicating with various types of base stations and network equipment including eNBs, small cell eNBs, relay base stations and the like. There may be overlapping geographic coverage areas for different technologies.

[0170] A macro cell usually covers a relatively large geographic area (eg, several kilometers in radius) and can allow unrestricted access by UEs with service subscriptions with the network provider. A small cell is a low power base station compared to a macro cell which can operate in the same or different (eg licensed or unlicensed etc.) frequency bands as the macro cells. Small cells can include pico cells, femto cells and micro cells according to various examples. A pico cell, for example, can cover a small geographic area and can allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and, furthermore, may provide restricted access by UEs that have an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for home users and the like). An eNB for a cell macro 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 homemade eNB. An eNB can support one or several (eg two, three, four, and the like) cells (eg, component carriers). A UE may be able to communicate with various types of base stations and network equipment including eNBs, small cell eNBs, relay base stations and the like.

[0171] The wireless communication system or systems described herein may support synchronous or asynchronous operation. For synchronous operation, base stations can have similar frame timing and transmissions from different base stations can be approximately time-aligned. For asynchronous operation, base stations may have different frame timing and transmissions from different base stations may not be time-aligned. The techniques described here can be used for either synchronous or asynchronous operations.

[0172] The downlink transmissions described here can also be called forward link transmissions while uplink transmissions can also be called reverse link transmissions. Each communication link described herein - including, for example, wireless communication system 100 and 200 of Figures 1 and 2 - may include one or more carriers, where each carrier may be a signal made up of several sub-carriers (e.g., waveform signals of different frequencies).

[0173] The description presented here, in connection with the attached drawings, describes example configurations and does not represent all configurations that can be implemented or that are within the scope of the claims. The term "exemplary" used herein means "to serve as an example, case, or illustration," not "preferred" or "advantageous over other examples." The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, can be practiced without these specific details. In some cases, well-known structures and devices are shown in block diagram form, in order to avoid obscuring the concepts of the examples described.

[0174] In the attached figures, similar components or resources may have the same reference label. Furthermore, multiple components of the same type can be distinguished by following the reference label by a dash and a second label that distinguishes between similar components. If only the first reference label is used in the specification, the description is applicable to any of the similar components with the same first reference label regardless of the second reference label.

[0175] Information and signals described herein 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 voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0176] The various illustrative blocks and modules described in connection with the present disclosure can be implemented or executed with a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device (PLD), discrete port or logic of transistor, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively the processor may be any conventional processor, controller, microcontroller, or conventional state machine. A processor can also be implemented as a combination of computing devices (for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other type of configuration).

[0177] The functions described here can be implemented in hardware, software executed by a processor, firmware or any combination thereof. If implemented in software executed by a processor, functions may be stored in or transmitted via one or more instructions or code on computer-readable media. Other examples and implementations are within the scope of the accompanying disclosure and claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring or combinations thereof. Resources that implement the functions can also be physically located in various locations, including being distributed so that portions of the functions are implemented in different physical locations. Also, as used herein, including in claims, "or", as used in a list of items (e.g., a list of items preceded by a phrase such as "at least one of or "one or more of") indicates a list inclusive such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or AC or ABC (that is, A and B and C).

[0178] Computer-readable media include both non-transient computer storage media and communication media, including any media that facilitates the transfer of a computer program from one place to another. A non-transient storage medium can be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transient computer-readable media may comprise RAM, ROM, electrically erasable programmable read-only memory (EEPROM), compact disc (CD) ROM or other optical disk storage, disk storage magnetic or other magnetic storage devices, or any other non-transient media that can be used to transport or store desired program code media in the form of instructions or data structures and that can be accessed by a general purpose computer or computer special purpose processor, or a general purpose processor or special purpose processor. Also, any connection is properly called a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source over coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, so coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave are included in the definition of media. Disk and floppy disk as used herein include CD, laser disk, optical disk, digital versatile disk (DVD), floppy disk and Blu-ray disk where floppy disks generally reproduce data magnetically, while disks reproduce data optically with lasers. Combinations of the foregoing are also included within the scope of computer-readable media.

[0179] The description of the present invention is provided to enable a 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 general principles defined herein can be applied to other variations without departing from the scope of the disclosure. Thus, the description is not limited to the examples and drawings described herein, but must conform to the widest scope consistent with the principles and novel features described herein.

Claims (14)

1. Method (1400) for wireless communication performed by a user equipment, UE, in a 3GPP system, characterized in that it comprises: receiving (1405) a downlink data transmission using resources of a radio frequency spectrum band , RF, shared during a first transmission opportunity, TxOP, from a base station; transmitting (1410) Hybrid Auto-Repeat Request, HARQ, feedback in response to the downlink data transmission during the first TxOP or a second TxOP, and storing the transmitted HARQ feedback in a buffer of the UE; receiving a request from the base station to retransmit a subset of previously transmitted HARQ feedback; relay the requested HARQ feedback; receiving an indication to clear the buffer after retransmission of the requested HARQ feedback, wherein the indication identifies the HARQ feedback to be cleared from the buffer; determining (1415) to clear a buffer of the HARQ feedback during the second TxOP or a third TxOP, the determination based, at least in part, on the indication to clear the buffer; and clearing (1420) the HARQ feedback from the buffer. 2. Method according to claim 1, characterized in that it additionally comprises: identifying a trigger to transmit additional HARQ feedback; pass additional HARQ feedback based at least in part on the trigger; and clearing the additional HARQ feedback from an additional buffer based, at least in part, on transmitting the additional HARQ feedback. 3. Method according to claim 2, characterized in that the buffer is arranged to store polled feedback associated with a request-based feedback mode and the additional buffer is arranged to store un-polled feedback associated with a request-based feedback mode. autonomous feedback. 4. Method according to claim 1, further comprising: receiving a resource grant for the HARQ feedback, wherein the HARQ feedback is transmitted using the resources in response to the request, wherein the resource grant includes an indication of an identifier for a HARQ process from the HARQ feedback. 5. Method according to claim 1, characterized in that it further comprises: identifying a trigger for transmitting the HARQ feedback, wherein the HARQ feedback is transmitted based, at least in part, on identifying the trigger. 6. Method according to claim 1, characterized in that the buffer comprises a common buffer for a short physical uplink control channel, spUCCH, an enhanced physical uplink control channel, ePUCCH, or a shared channel of physical uplink, PUSCH. 7. Method (1500) for wireless communication performed by a base station in a 3GPP system, characterized in that it comprises: transmitting (1505) a downlink data transmission using resources of a radio frequency spectrum band, RF, shared during a first transmission opportunity, TxOP, to a user equipment, UE; transmitting signals to indicate that hybrid auto-repeat request feedback, HARQ, is to be transmitted over at least one physical control channel; receiving (1510) Hybrid Auto-Retry Request, HARQ, feedback in response to the downlink data transmission during the first TxOP or a second TxOP; transmitting a request to retransmit a previously transmitted subset of HARQ feedback; receive requested HARQ feedback; and transmitting (1515) an indication to the UE to clear the buffer containing the requested HARQ feedback during the second TxOP or a third TxOP, where the indication identifies the HARQ feedback to be cleared from the buffer. 8. Method according to claim 7, characterized in that it additionally comprises: identifying a trigger for additional HARQ feedback; and receive additional HARQ feedback based at least in part on the trigger. 9. Method according to claim 7, characterized in that it additionally comprises: transmitting a request for HARQ feedback; and transmitting a resource grant for the HARQ feedback, wherein the HARQ feedback is transmitted using the resources in response to the request. 10. Method according to claim 9, characterized in that it further comprises: determining that an identifier for a HARQ process associated with downlink data transmission is not recognized, wherein the request for HARQ feedback is transmitted based on , at least in part, in determination. 11. Method according to claim 7, characterized in that it additionally comprises: determining that an identifier for a HARQ process associated with the transmission of downlink data is not recognized; and transmitting an additional downlink data transmission based, at least in part, on the determination. 12. Method according to claim 7, characterized in that the buffer comprises a common buffer for a short physical uplink control channel, spUCCH, an enhanced physical uplink control channel, ePUCCH, or a shared channel of physical uplink, PUSCH. 13. User equipment, UE, (700) for wireless communication in a 3GPP system, characterized in that it comprises: means (710) for receiving a downlink data transmission using resources of a radio frequency spectrum band, RF , shared during a first transmission opportunity, TxOP, from a base station; means (720) for transmitting Hybrid Auto-Repeat Request, HARQ, feedback in response to the downlink data transmission during the first TxOP or a second TxOP, and storing the transmitted HARQ feedback in a buffer of the UE; means for receiving a request from the base station to retransmit a subset of previously transmitted HARQ feedback; means for relaying the requested HARQ feedback; means for receiving an indication to clear the buffer after retransmission of the requested HARQ feedback, the indication identifying the HARQ feedback to be cleared from the buffer; means (730) for determining to clear a buffer of the HARQ feedback during the second TxOP or a third TxOP, the determination based, at least in part, on the indication to clear the buffer; and means (730) for clearing the HARQ feedback from the buffer. 14. Base station (1100) for wireless communication in a 3GPP system, characterized in that it comprises: means (1120) for transmitting a downlink data transmission using resources of a radio frequency spectrum band, RF, shared during a first transmission opportunity, TxOP, to a user equipment, UE; means (1120) for transmitting signals to indicate that hybrid autorepeat request feedback, HARQ, is to be transmitted over the at least one physical control channel; means (1125) for receiving Hybrid Auto Repeat Request, HARQ, feedback in response to the downlink data transmission during the first TxOP or a second TxOP; means for transmitting a request to retransmit a subset of previously transmitted HARQ feedback; means to receive requested HARQ feedback; and means (1130) for transmitting an indication to the UE to clear the buffer containing the requested HARQ feedback during the second TxOP or a third TxOP, wherein the indication identifies the HARQ feedback to be cleared from the buffer.