Medium access control-control element (MAC-CE) communication

Some aspects provide an apparatus for wireless communication, in accordance with some aspects of the present disclosure. The apparatus generally includes at least one processor, and at least one memory communicatively coupled with the at least one processor and storing processor-readable code. The processor-readable code, when executed by the at least one processor, may be configured to transmit a packet including at least one medium access control-control element (MAC-CE), receive hybrid automatic request (HARQ) signaling indicating whether the packet was decoded successfully, determine, in response to the HARQ signaling, whether to retransmit the at least one MAC-CE or transmit at least one other MAC-CE based on whether the packet comprises data, and transmit another packet having the at least one MAC-CE or the at least one other MAC-CE based on the determination.

TECHNICAL FIELD

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for managing medium access control-control element (MAC-CE) communication.

BACKGROUND

A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. For example, a base station may transmit a MAC CE to a user-equipment (UE) to put the UE into a discontinuous reception (DRX) mode to reduce the UE's power consumption. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel. A MAC-CE may also be used to communicate information that facilitates communication, such as information regarding buffer status and available power headroom.

SUMMARY

One innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication. The method includes transmitting a packet including at least one medium access control-control element (MAC-CE), receiving hybrid automatic request (HARQ) signaling indicating whether the packet was decoded successfully, determining, in response to the HARQ signaling, whether to retransmit the at least one MAC-CE or transmit at least one other MAC-CE based on whether the packet comprises data, and transmitting another packet having the at least one MAC-CE or the at least one other MAC-CE based on the determination.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication. The method includes receiving a packet including at least one MAC-CE, determining whether the packet was decoded successfully, transmitting a negative acknowledgment (NACK) indicating that the packet was not decoded successfully, receiving an indication to avoid adjusting a transmit power of other HARQ signaling in response to reception of at least one other MAC-CE instead of a retransmission of the at least one MAC-CE, and receiving another packet having the at least one other MAC-CE instead of the retransmission of the at least one MAC-CE, wherein the transmit power for the other HARQ signaling is set in accordance with the received indication.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication. The method includes receiving a packet including at least one medium access control-control element (MAC-CE), determining whether the packet further comprises data, generating HARQ signaling indicating whether the packet was decoded successfully, wherein the HARQ signaling further indicates whether a retransmission of the at least one MAC-CE is required based on the determination of whether the packet further comprises the data, transmitting the HARQ signaling, and receiving another packet including the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

Another innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication. The method includes transmitting control signaling indicating whether a packet to be transmitted comprises data, generating the packet including at least one MAC-CE, transmitting the packet including the at least one MAC-CE, receiving HARQ signaling indicating whether the packet was decoded successfully, wherein the HARQ signaling further indicates whether a retransmission of the at least one MAC-CE is required based on whether the packet comprises the data, and transmitting another packet comprises the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes at least one processor, and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to: transmit a packet including at least one MAC-CE; receive HARQ signaling indicating whether the packet was decoded successfully; determine, in response to the HARQ signaling, whether to retransmit the at least one MAC-CE or transmit at least one other MAC-CE based on whether the packet comprises data; and transmit another packet having the at least one MAC-CE or the at least one other MAC-CE based on the determination.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes at least one processor, and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to: receive a packet including at least one MAC-CE; determine whether the packet was decoded successfully; transmit a NACK indicating that the packet was not decoded successfully; receive an indication to avoid adjusting a transmit power of other HARQ signaling in response to reception of at least one other MAC-CE instead of a retransmission of the at least one MAC-CE; receive another packet having the at least one other MAC-CE instead of the retransmission of the at least one MAC-CE; and transmit the other HARQ signaling, the transmit power for the other HARQ signaling being set in accordance with the received indication.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes at least one processor, and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to: receive a packet including at least one MAC-CE; determine whether the packet further comprises data; generate HARQ signaling indicating whether the packet was decoded successfully, the HARQ signaling further indicating whether a retransmission of the at least one MAC-CE is required based on the determination of whether the packet further comprises the data; transmit the HARQ signaling; and receive another packet including the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes at least one processor, and at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to: transmit control signaling indicating whether a packet to be transmitted comprises data; generate the packet including at least one MAC-CE; transmit the packet including the at least one MAC-CE; receive HARQ signaling indicating whether the packet was decoded successfully, the HARQ signaling further indicating whether a retransmission of the at least one MAC-CE is required based on whether the packet comprises the data; and transmit another packet comprises the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

One innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes means for transmitting a packet including at least one MAC-CE, means for receiving HARQ signaling indicating whether the packet was decoded successfully, means for determining, in response to the HARQ signaling, whether to retransmit the at least one MAC-CE or transmit at least one other MAC-CE based on whether the packet comprises data, and means for transmitting another packet having the at least one MAC-CE or the at least one other MAC-CE based on the determination.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes means for receiving a packet including at least one MAC-CE, means for determining whether the packet was decoded successfully, means for transmitting a NACK indicating that the packet was not decoded successfully, means for receiving an indication to avoid adjusting a transmit power of other HARQ signaling in response to reception of at least one other MAC-CE instead of a retransmission of the at least one MAC-CE, and means for receiving another packet having the at least one other MAC-CE instead of the retransmission of the at least one MAC-CE, wherein the transmit power for the other HARQ signaling is set in accordance with the received indication.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes means for receiving a packet including at least one MAC-CE, means for determining whether the packet further comprises data, means for generating HARQ signaling indicating whether the packet was decoded successfully, wherein the HARQ signaling further indicates whether a retransmission of the at least one MAC-CE is required based on the determination of whether the packet further comprises the data, transmitting the HARQ signaling, and means for receiving another packet including the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication. The apparatus includes means for transmitting control signaling indicating whether a packet to be transmitted comprises data, means for generating the packet including at least one MAC-CE, transmitting the packet including the at least one MAC-CE, means for receiving HARQ signaling indicating whether the packet was decoded successfully, wherein the HARQ signaling further indicates whether a retransmission of the at least one MAC-CE is required based on whether the packet comprises the data, and means for transmitting another packet comprises the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

One innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause an apparatus to transmit a packet including at least one MAC-CE, receive HARQ signaling indicating whether the packet was decoded successfully, determine, in response to the HARQ signaling, whether to retransmit the at least one MAC-CE or transmit at least one other MAC-CE based on whether the packet comprises data, and transmit another packet having the at least one MAC-CE or the at least one other MAC-CE based on the determination.

One innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause an apparatus to receive a packet including at least one MAC-CE, determine whether the packet was decoded successfully, transmit a NACK indicating that the packet was not decoded successfully, receive an indication to avoid adjusting a transmit power of other HARQ signaling in response to reception of at least one other MAC-CE instead of a retransmission of the at least one MAC-CE, and receive another packet having the at least one other MAC-CE instead of the retransmission of the at least one MAC-CE, wherein the transmit power for the other HARQ signaling is set in accordance with the received indication.

One innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause an apparatus to receive a packet including at least one MAC-CE, determine whether the packet further comprises data, generate HARQ signaling indicating whether the packet was decoded successfully, wherein the HARQ signaling further indicates whether a retransmission of the at least one MAC-CE is required based on the determination of whether the packet further comprises the data, transmitting the HARQ signaling, and receive another packet including the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

One innovative aspect of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause an apparatus to transmit control signaling indicating whether a packet to be transmitted comprises data, generating the packet including at least one MAC-CE, transmit the packet including the at least one MAC-CE, receive HARQ signaling indicating whether the packet was decoded successfully, wherein the HARQ signaling further indicates whether a retransmission of the at least one MAC-CE is required based on whether the packet comprises the data, and transmit another packet comprises the retransmission of the at least one MAC-CE or at least one other MAC-CE in accordance with the HARQ signaling.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail some illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for managing the communication of a medium access control-control element (MAC-CE). A MAC-CE may be used to indicate various information for sidelink, downlink, and uplink communications. A MAC-CE may be transmitted on a shared channel with or without data. If the shared channel includes data, the shared channel may be retransmitted in response to a negative acknowledgment (NACK) to facilitate combining of the original transmission and the retransmission for decoding. However, if the shared channel does not include data, it may be preferable to transmit a new MAC-CE instead of a retransmission of the previously transmitted MAC-CE. In other words, it may be preferable for the transmitter of the MAC-CE to transmit a new MAC-CE having the latest information (for example, channel state information). Some aspects of the present disclosure describe various protocols for controlling whether a new transmission of MAC-CE, or a retransmission of a previously transmitted MAC-CE is to occur based on whether the shared channel having the MAC-CE also includes data and various other factors associated with the MAC-CE, as described in more detail herein.

FIG.1illustrates an example wireless communication network100in which aspects of the present disclosure may be performed. For example, the wireless communication network100may be an NR system (for example, a 5G NR network). As shown inFIG.1, the BS110aand the UEs120a,120bmay each include a MAC-CE manager111,122a,122b, respectively, that determines whether a MAC-CE retransmission or a new MAC-CE transmission is to occur, in accordance with some aspects of the present disclosure.

NR access (for example, 5G NR) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (for example, 80 MHz or beyond), millimeter wave (mmWave) targeting high carrier frequency (for example, 25 GHz or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, or mission critical services targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same time-domain resource (for example, a slot or subframe) or frequency-domain resource (for example, component carrier).

Wireless communication network100may also include relay stations (for example, relay station110r), also referred to as relays or the like, that receive a transmission of data or other information from an upstream station (for example, a BS110aor a UE120r) and sends a transmission of the data or other information to a downstream station (for example, a UE120or a BS110), or that relays transmissions between UEs120, to facilitate communication between devices.

A network controller130may couple to a set of BSs110and provide coordination and control for these BSs110. The network controller130may communicate with the BSs110via a backhaul. The BSs110may also communicate with one another (for example, directly or indirectly) via wireless or wireline backhaul.

FIG.2shows a block diagram illustrating an example base station (BS) and an example user equipment (UE) in accordance with some aspects of the present disclosure.

At the BS110, a transmit processor220may receive data from a data source212and control information from a controller/processor240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. The processor220may process (for example, encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor220may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor230may perform spatial processing (for example, precoding) on the data symbols, the control symbols, or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs)232a-232t. Each modulator232may process a respective output symbol stream (for example, for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators232a-232tmay be transmitted via the antennas234a-234t, respectively.

The memories242and282may store data and program codes for BS110and UE120, respectively. A scheduler244may schedule UEs for data transmission on the downlink or uplink.

The controller/processor280or other processors and modules at the UE120may perform or direct the execution of processes for the techniques described herein. As shown inFIG.2, the controller/processor280of the UE120has a MAC-CE manager121that determines whether a MAC-CE retransmission or a new MAC-CE transmission is to occur based on various factors as further described herein. As shown inFIG.2, the controller/processor240of the BS110may also include a MAC-CE manager111that determines whether a MAC-CE retransmission or a new MAC-CE transmission is to occur based on various factors as further described herein. Although shown at the Controller/Processor, other components of the UE or BS may be used to perform the operations described herein.

FIGS.3A and3Bshow diagrammatic representations of example vehicle to everything (V2X) systems in accordance with some aspects of the present disclosure. The V2X systems, provided inFIGS.3A and3Bprovide two complementary transmission modes. A first transmission mode, shown by way of example inFIG.3A, involves direct communications (for example, also referred to as side link communications) between participants in proximity to one another in a local area. A second transmission mode, shown by way of example inFIG.3B, involves network communications through a network, which may be implemented over a Uu interface (for example, a wireless communication interface between a radio access network (RAN) and a UE).

Referring toFIG.3A, a V2X system300(for example, including vehicle to vehicle (V2V) communications) is illustrated with two vehicles302,304. The first transmission mode allows for direct communication between different participants in a given geographic location. As illustrated, a vehicle can have a wireless communication link306with an individual (V2P) (for example, via a UE) through a PC5interface. Communications between the vehicles302and304may also occur through a PC5interface308. In a like manner, communication may occur from a vehicle302to other highway components (for example, highway component310), such as a traffic signal or sign (V2I) through a PC5interface312. With respect to each communication link illustrated inFIG.3A, two-way communication may take place between elements, therefore each element may be a transmitter and a receiver of information. The V2X system300may be a self-managed system implemented without assistance from a network entity. A self-managed system may enable improved spectral efficiency, reduced cost, and increased reliability as network service interruptions do not occur during handover operations for moving vehicles. The V2X system may be configured to operate in a licensed or unlicensed spectrum, thus any vehicle with an equipped system may access a common frequency and share information. Such harmonized/common spectrum operations allow for safe and reliable operation.

FIG.3Bshows a V2X system350for communication between a vehicle352and a vehicle354through a network entity356. These network communications may occur through discrete nodes, such as a base station (for example, an eNB or gNB), that sends and receives information to and from (for example, relays information between) vehicles352,354. The network communications through vehicle to network (V2N) links358and310may be used, for example, for long range communications between vehicles, such as for communicating the presence of a car accident a distance ahead along a road or highway. Other types of communications may be sent by the node to vehicles, such as traffic flow conditions, road hazard warnings, environmental/weather reports, and service station availability, among other examples. Such data can be obtained from cloud-based sharing services.

Example Techniques for Medium Access Control-Control Element (MAC-CE) Communication

In some wireless communication systems (for example, 5G NR systems), hybrid automatic request (HARQ) operations are employed to improve the reliability of data transmissions. For example, HARQ operations may provide mechanisms for detecting errors in a transmission (for example, via a cyclic redundancy check) and forward error correction (FEC) coding that introduces redundancy to the information data bits (for example, by adding parity bits based on the data bits) in the transmission to enable a receiver to correct the detected errors. HARQ may also provide a feedback mechanism that enables the receiver to trigger retransmissions from the transmitter in response to detecting an error in a received transmission. For example, a receiver may send HARQ signaling to indicate to a transmitter whether a shared channel has been successfully decoded. In some cases, the receiver may combine retransmissions of the same transport block (TB) to improve decoding performance. For example, a UE may store a received TB having errors in a soft buffer (for example, a HARQ buffer), and when a re-transmission of the TB is received, the UE may combine the received data with the data currently in the HARQ buffer and attempt to decode the combined data.

In some circumstances, two or more subordinate entities (for example, UEs) may communicate with each other using sidelink signals. As described above, V2V and V2X communications are examples of communications that may be transmitted via a sidelink. Other applications of sidelink communications may include public safety or service announcement communications, communications for proximity services, communications for UE-to-network relaying, device-to-device (D2D) communications, Internet of Everything (IoE) communications, Internet of Things (IoT) communications, mission-critical mesh communications, among other suitable applications. Generally, a sidelink may refer to a direct link between one subordinate entity (for example, UE1) and another subordinate entity (for example, UE2). As such, a sidelink may be used to transmit and receive a communication (also referred to herein as a “sidelink signal”) without relaying the communication through a scheduling entity (for example, a BS), even though the scheduling entity may be utilized for scheduling or control purposes. In some examples, a sidelink signal may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum).

Various sidelink channels may be used for sidelink communications, including a physical sidelink discovery channel (PSDCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), and a physical sidelink feedback channel (PSFCH). The PSDCH may carry discovery expressions that enable proximal devices to discover each other. The PSCCH may carry control signaling such as sidelink resource configurations and other parameters used for data transmissions, and the PSSCH may carry the data transmissions. The PSFCH may carry feedback such as channel state information (CSI) related to a sidelink channel quality.

As used herein, a “receiver device” generally refers to any wireless node that receives a MAC-CE, and a “transmitter device” generally refers to any wireless node that transmits a MAC-CE. Each of the receiver device and the transmitter device may be any wireless node, such as a UE or BS. Moreover, while some examples provided herein are described with a shared channel having a MAC-CE to facilitate understanding, the aspects of the present disclosure are applicable to any channel having one, or multiple MAC-CEs.

In some cases, a transmitter, such as a base station, may transmit a downlink (DL) command via downlink control information (DCI) over a physical downlink control channel (PDCCH). Similarly, a transmitter, such as a UE, may transmit an uplink (UL) command via uplink control information (UCI) over a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). However, using DCI or UCI may be less reliable but result in lower latency as compared to using a MAC-CE because, unlike a MAC-CE, no HARQ acknowledgment (ACK)/negative-acknowledgment (NACK) (also referred to herein as “A/N”) signaling is implemented for DCI and UCI. DCI and UCI may also have less control information capacity and the type of control information that can be carried in DCI and UCI is not as flexible as that that can be carried in a MAC-CE.

In some cases, a MAC-CE may be used to communicate various information or commands such as information related to a beam change, discontinuous reception (DRX) related information, a power head room (PHR), a buffer status report (BSR), or a recommended bit-rate to be used, among other examples. In some cases, a MAC-CE may be associated with an expiration time (for example, indicating when information indicated by the MAC-CE expires). A MAC-CE may be carried in a shared channel (for example, physical downlink shared channel (PDSCH), physical uplink shared channel (PUSCH), or PSSCH). HARQ signaling may be implemented for the shared channel. Therefore, the communication of the MAC-CE may be reliable, but has a higher latency due to the latency associated with the HARQ operations. For example, a receiver may transmit a HARQ ACK to the transmitter of the MAC-CE to provide confirmation that a command has been received via the MAC-CE.

In some cases, even if high reliability is not necessary, a MAC-CE may still be a convenient way to package control information. For example, for V2X, V2V or other sidelink communications, it may be preferable to use a MAC-CE for channel state information (CSI)-reporting. As another example, it may be preferable to use a MAC-CE because a MAC-CE provides more flexibility in payload size as compared to DCI or UCI.

In some cases, if a packet fails HARQ (for example, the MAC-CE is not successfully decoded by the receiver), it may be desirable to retransmit only the data of the shared channel without retransmitting the MAC-CE included in the original shared channel transmission. For example, the next transmission by the transmitter may include a new MAC-CE, which may be of the same size as or a different size than the original MAC-CE. In some cases, the next transmission may not include a MAC-CE at all. However, in some implementations, if the new transmission does not include a MAC-CE or has a new MAC-CE instead of a retransmission of the original MAC-CE, the receiver cannot perform a HARQ data-combining operation (for example, combining of the original data transmission and the data retransmission for decoding).

In some aspects of the present disclosure, the transmitter may generate a new transmission of a MAC-CE, or a retransmission of an original MAC-CE transmission based on whether the original transmission (for example, a shared channel packet) includes a MAC-CE without data. In other words, a wireless node may determine whether to retransmit the MAC-CE based on whether the original transmission of the MAC-CE is in a shared channel with data. In some implementations, the determination of whether the MAC-CE is to be retransmitted may be made by the transmitter of the MAC-CE (for example, according to a “transmitter-controlled protocol”), or by the receiver of the MAC-CE (for example, according to a “receiver-controlled protocol”).

FIG.4shows a flowchart illustrating an example process400for wireless communication in accordance with some aspects of the present disclosure. In some implementations, the process400may be specifically directed to operations that use a transmitter-controlled protocol. The operations of the process400may be performed, for example, by a transmitter device such as the BS110ain the wireless communication network100or by a UE such as a UE120ain the wireless communication network100.

The operations of the process400may be implemented by software components including instructions that are executed on one or more processors (for example, controller/processor240or280ofFIG.2). Further, the transmission and reception of signals by the transmitter device in process400may be enabled, for example, by one or more antennas (for example, antennas234or252ofFIG.2). In some aspects, the transmission or reception of signals by the transmitter device may be implemented via a bus interface of one or more processors (for example, controller/processor240or280) obtaining or outputting signals.

In some implementations, the process400may begin in block405with the transmitter device transmitting a packet including one or more MAC-CEs (also referred to as at least one MAC-CE). In block410, the transmitter device receives HARQ signaling indicating whether the packet was decoded successfully. In block415, the transmitter device determines, in response to the HARQ signaling, whether to retransmit one or more of the MAC-CEs (also referred to as the original MAC-CE) or whether to transmit at least one other MAC-CE (also referred to as a new MAC-CE) based on whether the packet comprises data. In block420, the transmitter device transmits, based on the determination in block415, another packet that may include a retransmission of the original MAC-CE or that may include a new MAC-CE. For example, if the packet does not include data, the transmitter device may determine to transmit a new MAC-CE (for example, an updated MAC-CE), instead of retransmitting the original MAC-CE. Additionally or alternatively, in some cases, the HARQ signaling may indicate that the packet was not decoded successfully (for example, via a NACK) but that a retransmission of the original MAC-CE is not required if the packet having the original MAC-CE does not comprise data.

In some aspects, the determination in block415of whether to retransmit a MAC-CE or whether to transmit a new updated MAC-CE is further based on a type of the original MAC-CE. For example, the determination in block415may include determining to transmit a new updated MAC-CE if the original MAC-CE is used for CSI-reporting and if the packet having the original MAC-CE does not comprise data.

As another example, the determination of whether to retransmit the original MAC-CE or whether to transmit a new updated MAC-CE in block415may be further based on whether the original MAC-CE is associated with an expiration time. For example, some MAC-CE information may only be valid for a limited duration of time. In some such implementations, if the expiration time has passed, the transmitter device may determine in block415to transmit a new updated MAC-CE instead of retransmitting the original MAC-CE because the information in the original MAC-CE has expired. On the other hand, if the information in the original MAC-CE has not expired, the transmitter device may determine to retransmit the original MAC-CE in block415.

As described above, in some instances, the HARQ signaling by the receiver may include a NACK. In such instances, the determination in block415may include determining to transmit the new updated MAC-CE instead of retransmitting the original MAC-CE in response to the NACK if the packet does not comprise data, as described in more detail with respect toFIG.5below.

FIG.5shows a call-flow diagram illustrating an example process500for wireless communication of MAC-CE using a transmitter-controlled protocol, in accordance with some aspects of the present disclosure. As illustrated, the transmitter device502may transmit a MAC-CE503. In block505, the receiver device504may generate HARQ signaling in response to receiving the MAC-CE503. For example, if the receiver device504fails to successfully decode the packet including the MAC-CE503, the receiver device504may transmit a NACK510to the transmitter device502. In block512, the transmitter device502may determine whether to retransmit the MAC-CE503, or transmit another MAC-CE514, based on whether the MAC-CE503is in a packet with data, and in some cases, based on various other factors described herein (for example, the type of MAC-CE, or whether the MAC-CE is associated with an expiration time).

Because the receiver device504is expecting a retransmission of the MAC-CE503, if the transmitter device502transmits the new MAC-CE514instead of retransmitting the MAC-CE503, the receiver device504may adjust a transmit power control loop for further HARQ signaling to be sent. In other words, the receiver device504may assume that the NACK510was not received by the transmitter device502, and may increase the transmit power of further HARQ signaling to be transmitted by the receiver device504. Thus, in some aspects, the transmitter device502may transmit control signaling513indicating that the receiver device504is to avoid adjusting a transmit power for further HARQ signaling in response to the transmission of the new MAC-CE514, as described in more detail with respect toFIG.6.

FIG.6shows a flowchart illustrating an example process600for wireless communication, in accordance with some aspects of the present disclosure. In some implementations, the process600may be specifically directed to operations that use a transmitter-controlled protocol. The process600may be performed, for example, by a receiver device such as the BS110ain the wireless communication network100or the UE120ain the wireless communication network100.

The operations of the process600may be implemented as software components that are executed and run on one or more processors (for example, controller/processor240or280ofFIG.2). Further, the transmission and reception of signals by the receiver device in process600may be enabled, for example, by one or more antennas (for example, antennas234or252ofFIG.2). In some aspects, the transmission or reception of signals by the receiver device may be implemented via a bus interface of one or more processors (for example, controller/processor240or280) obtaining or outputting signals.

In some implementations, the process600may begin, in block605, by the receiver device receiving a packet including at least one MAC-CE (also referred to as the original MAC-CE), and in block610, determining whether the packet was decoded successfully. In block615, the receiver device may transmit a negative acknowledgment (NACK) indicating that the packet was not decoded successfully, and in block620, receive an indication to avoid adjusting a transmit power of other HARQ signaling in response to reception of a new MAC-CE (also referred to as “at least one other MAC-CE”) instead of a retransmission of the original MAC-CE. In block625, the receiver device may receive another packet having the new MAC-CE instead of the retransmission of the original MAC-CE. In some aspects, the transmit power for the other HARQ signaling may be set in accordance with the received indication. In other words, the receiver device may avoid adjusting the transmit power of the other HARQ signaling even though the receiver device received the new MAC-CE instead of a retransmission of the original MAC-CE. In some cases, the indication to avoid adjusting the transmit power of the other HARQ signaling is received via radio resource control (RRC) signaling, MAC-CE signaling, or control information signaling.

FIG.7shows a flowchart illustrating an example process700for wireless communication, in accordance with some aspects of the present disclosure. In some implementations, the process700may be specifically directed to operations that use a receiver-controlled protocol. The process700may be performed, for example, by a receiver device such as the BS110ain the wireless communication network100or by a UE such as a UE120ain the wireless communication network100.

The operations of the process700may be implemented as software components that are executed and run on one or more processors (for example, controller/processor240or280ofFIG.2). Further, the transmission and reception of signals by the receiver device in process700may be enabled, for example, by one or more antennas (for example, antennas234or252ofFIG.2). In some aspects, the transmission or reception of signals by the receiver device may be implemented via a bus interface of one or more processors (for example, controller/processor240or280) obtaining or outputting signals.

The process700may begin, in block705, by the receiver device receiving a packet including at least one MAC-CE (also referred to as the original MAC-CE), and in block710, determining whether the packet further comprises data. For instance, the receiver device may receive control signaling indicating whether the packet comprises the data, the determination in block710being based on the received indication by the control signaling. The receiver device may receive the control signaling prior to the reception of the packet having the original MAC-CE, in some cases.

In block715, the receiver device may generate HARQ signaling indicating whether the packet was decoded successfully. In some aspects, the HARQ signaling further indicates whether a retransmission of the original MAC-CE is required based on the determination in block710of whether the packet further comprises the data. In block720, the receiver device transmits the HARQ signaling, and in block725, receives another packet including the retransmission of the original MAC-CE or at least one other MAC-CE (also referred to as a new MAC-CE) in accordance with the HARQ signaling.

In some cases, the packet may not be decoded successfully by the receiver device. In this case, if the packet having the original MC-CE does not include data, the HARQ signaling by the receiver device may indicate that the retransmission of the packet having the original MAC-CE is not required, and a new packet may be transmitted having a new MAC-CE in response to the HARQ signaling. For example, if the packet having the original MAC-CE does not include data, the HARQ signaling may include a NACK indicating that the packet was not decoded successfully but that the retransmission of the packet is not required. As another example, if the packet does not include data, the HARQ signaling may be an ACK indicating that the packet was decoded successfully, as described in more detail with respect toFIG.8.

FIG.8shows a call flow diagram illustrating example process800for wireless communication of MAC-CE using a receiver-controlled protocol, in accordance with some aspects of the present disclosure. As illustrated, the transmitter device802may send control signaling803, indicating to the receiver device804whether a packet having the MAC-CE805also includes data. In some cases, the control signaling803may also indicate other MAC-CE information that may be used by the receiver device804for determining whether to retransmit the MAC-CE805, as described in more detail herein. The other MAC-CE information may include the type of the MAC-CE805(for example, whether the MAC-CE is for beam-change or is DRX related), the size or the number of MAC-CE to be transmitted in a shared channel (for example, PDSCH, PUSCH, or PSSCH), power head room (PHR)/buffer status report (BSR), recommended bit-rate to be used, and whether the MAC-CE is associated with an expiration timer. For example, if the MAC-CE805may be used for CSI reporting and if the packet does not include data, the HARQ signaling may indicate that the retransmission of the packet is not required.

In block806, the receiver device804determines that the decoding of the MAC-CE805is unsuccessful, and in block808, determines whether to request a retransmission of the MAC-CE805, as described herein. The receiver device804then transmits HARQ signaling810indicating that a retransmission of the MAC-CE805is not required. For example, the HARQ signaling810may be a NACK indicating that the MAC-CE805was not decoded successfully, but that a retransmission of the MAC-CE805is not required, or may be an ACK. Thus, the transmitter device802may transmit another MAC-CE820, as illustrated.

FIG.9shows a flowchart illustrating an example process900for wireless communication, in accordance with some aspects of the present disclosure. In some implementations, the process900may be specifically directed to operations that use a receiver-controlled protocol. The process900may be performed, for example, by a transmitter device such as the BS110ain the wireless communication network100or by a UE such as a UE120ain the wireless communication network100.

The operations of the process900may be implemented as software components that are executed and run on one or more processors (for example, controller/processor240or280ofFIG.2). Further, the transmission and reception of signals by the transmitter device in process900may be enabled, for example, by one or more antennas (for example, antennas234or252ofFIG.2). In some aspects, the transmission or reception of signals by the transmitter device may be implemented via a bus interface of one or more processors (for example, controller/processor240or280) obtaining or outputting signals.

In some implementations, the process900may begin, in block905, by the transmitter device transmitting control signaling indicating whether a packet to be transmitted comprises data, in block910, generating the packet including generating at least one MAC-CE (also referred to as the original MAC-CE) in the packet, and in block915, transmitting the packet including the original MAC-CE. In some aspects, the transmitter device may, in block920, receive HARQ signaling indicating whether the packet was decoded successfully, where the HARQ signaling further indicates whether to retransmit the original MAC-CE based on whether the packet comprises the data, and in block925, transmit another packet including the retransmission of the original MAC-CE or at least one other MAC-CE (also referred to as the new MAC-CE) in accordance with the HARQ signaling.

In other words, a transmitter device may use a control channel to indicate information about the original MAC-CE (for example, whether data is present in the payload of a shared channel packet that also includes the original MAC-CE). For example, the control channel may be DCI for DL, SCI for SL, or UCI for UL. The packet information may indicate whether a MAC-CE is present in a shared channel, whether data is present in the shared channel, or whether both data and MAC-CE are present in the shared channel. In some cases, the receiver device may use various parameters indicated by the packet information to determine whether to request a retransmission. For example, the parameters may include the size or the number of MAC-CEs in the shared channel, the types of MAC-CE (for example, whether the MAC-CE is for beam-change or is DRX related), PHR/BSR, recommended bit-rate, and whether the MAC-CE has an expiration time).

From the receiver device perspective, if the MAC-CE information indicates that the packet contains only MAC-CE(s) that are not required to be received with high reliability, the receiver device may indicate ACK even if the receiver device failed to decode the packet resulting in the transmitter device transmitting the latest version of the control information in the MAC-CE, rather than retransmitting the original MAC-CE. In some cases, the receiver device may indicate a NACK to the transmitter device, yet still request that the transmitter device not retransmit the original MAC-CE so that the transmitter prioritizes transmission of the latest version of the control information in a MAC-CE. For instance, a wireless node may be implemented to use additional A/N signaling. For example, a three-state A/N signaling (for example, ACK, NACK with retransmission, and NACK without retransmission) or additional A/N bits may be implemented to indicate either ACK, NACK with retransmission, or NACK without retransmission.

As an example for sidelink (for example, UE to UE communication, as described with respect toFIG.3A), a receiver may determine that an original MAC-CE includes a CSI-report and should not be retransmitted, even if the original MAC-CE was not successfully decoded, since it is preferable for the transmitter device to retransmit a new MAC-CE having the latest CSI information. As another example, some MAC-CEs (for example, related to beam-change) may have an expiration time defined. For instance, the information indicated by the MAC-CE may only be valid for a limited duration (e.g., 3 ms) after sending the ACK for the shared channel carrying the MAC-CE. Therefore, the MAC-CE may be urgent, and the receiver may request that the MAC-CE be retransmitted, or if the expiration time has expired, a new transmission may be requested instead of a retransmission of the original MAC-CE transmission.

In a transmitter-controlled protocol, instead of the transmitter device indicating the MAC-CE information to the receiver device, the transmitter device may determine not to retransmit the original MAC-CE even if the transmitter device receives a NACK from the receiver device. For instance, for a packet with only MAC-CEs of low reliability requirement, the transmitter device may determine to send a new transmission instead of a retransmission of an original MAC-CE, even if the transmitter device receives a NACK indicating that the original MAC-CE was not successfully decoded at the receiver.

With regards to an access link (for example, link between UE and BS), the transmitter device may send a new transmission instead of a retransmission in response to a NACK on DL (for example, when the transmitter is the BS, which controls the new or retransmission packet). For UL however, the A/N signal may be in the form of a new data indicator in the UL grant (for example, UCI) which the UE may have to honor. In other words, if the UL grant is for a retransmission (for example, based on a new data indicator (NDI) bit in the grant), the UE may have to honor the UL grant and retransmit the MAC-CE because the BS is expecting the retransmission in order to combine the retransmission and the original transmission to facilitate decoding. Therefore, if the UE receives a NACK associated with an original MAC-CE transmission, and transmits a new MAC-CE instead of a retransmission of the original MAC-CE, the BS may interpret the reception of the new MAC-CE as an ACK error and adjust a transmit power control loop for a following A/N transmission based on this event. In other words, the BS may not be aware that the UE has transmitted a new MAC-CE instead of a retransmission of the original MAC-CE. The BS may therefore attempt to combine the new transmission from the UE with the original transmission. That is, the BS may assume that the latest transmission from the UE is a retransmission and therefore attempt HARQ-combining, but it will be unable to combine the transmissions to correct for decoding errors. The BS may then increase the power of a following A/N transmission (also referred to herein as “other HARQ signaling”).

Similarly, with regards to DL and SL transmissions of a MAC-CE, an ACK error may result at a receiving UE after a transmitter device (a base station or another UE) transmits a new packet having a new MAC-CE instead of a retransmission of an original MAC-CE. At least for SL and DL channels, unnecessary power adjustment may be prevented by specification, by an RRC/MAC-CE based configuration, or by adding a field (for example, power control adjustment prevention field) in the scheduling grant (for example, DCI or SCI), as described herein. In some aspects, the BS may indicate to the UE that the new packet is a new transmission of the MAC-CE such that the UE does not determine that an ACK error has occurred and does not adjust the power control of the following A/N transmission.

In some cases, a transport block (TB) of a shared channel may be implemented with a single code block (CB), in which case, a single A/N may be communication for the TB. In other cases, a TB may be implemented with multiple CBs, also referred to as a CB group (CBG). In this case, an ACK may be indicated if all the CBGs are decoded, and a NACK may be indicated otherwise. With respect to the receiver-controlled protocol described herein, if the receiver device transmits an ACK even though the receiver device could not decode the MAC-CE, the transmitter device may assume that all CBGs were decoded successfully. Alternatively, the receiver device may indicate to the transmitter device that some CBGs were not decoded successfully, but that the CBGs need not be retransmitted even though the CBGs were not decoded successfully. In this case, the decoded CBGs may either be partially processed (for example, for processing MAC-CE commands the decoded CBGs contain) or rejected all together, based on behavior that may be defined in the specification. With respect to the transmitter-controlled protocol, the indication to avoid adjusting the transmit power of HARQ signaling may be sent separately per CB/CBG or could apply to the entire TB, as the outer control loop may react on a per CB/CBG basis or on a TB basis.

FIG.10shows a block diagram of an example communication device1000(for example, UE120aor UE120bshown inFIG.1, or BS110as shown inFIG.1) that may include various components (for example, corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated inFIGS.4-9. The communications device1000includes a processing system1002coupled to a transceiver1008(for example, a transmitter or receiver). The transceiver1008is configured to transmit and receive signals for the communications device1000via an antenna1010, such as the various signals as described herein. The processing system1002may be configured to perform processing functions for the communications device1000, including processing signals received or to be transmitted by the communications device1000.

The processing system1002includes a processor1004coupled to a computer-readable medium/memory1012via a bus1006. In some aspects, the computer-readable medium/memory1012is configured to store instructions (for example, computer-executable code) that when executed by the processor1004, cause the processor1004to perform the operations illustrated inFIGS.4-9, or other operations for performing the various techniques discussed herein for managing communication of a MAC-CE.

In some aspects, computer-readable medium/memory1012stores code for transmitting1014, code for receiving1016, code for determining1018(e.g., determining whether to retransmit, determining whether a packet was decoded successfully, or determining whether a packet includes data), and code for generating1020(e.g., generating a packet including a MAC-CE or generating HARQ signaling). In some aspects, the processor1004has circuitry configured to implement the code stored in the computer-readable medium/memory1012. The processor1004includes circuitry for transmitting1026, circuitry for receiving1028, circuitry for determining1030, and circuitry for generating1032.

The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G, 4G, or 5G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using TDD. In NR, a subframe is still 1 ms, but the basic TTI is referred to as a slot. A subframe contains a variable number of slots (for example, 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing. The NR RB is 12 consecutive frequency subcarriers. NR may support a base subcarrier spacing of 15 KHz and other subcarrier spacing may be defined with respect to the base subcarrier spacing, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. In some examples, MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. In some examples, multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

As used herein, the term “determining” may encompass one or more of a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (for example, looking up in a table, a database or another data structure), and the like. Also, “determining” may include receiving (for example, receiving information), accessing (for example, accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

As used herein, “or” is used intended to be interpreted in the inclusive sense, unless otherwise explicitly indicated. For example, “a or b” may include a only, b only, or a combination of a and b. As used herein, a phrase referring to “at least one of” or “one or more of” a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.