Patent Description:
In the conventional technology, downlink data transmission services provided by a wireless communication system for a terminal device may generally be classified into two types: a unicast service and a broadcast/multicast service.

Unicasting is point-to-point communication, namely, single-point communication between a network device and a terminal device. The network device may send data for each terminal device to implement a personalized service. However, when there are a large quantity of terminal devices and access traffic of the terminal devices is heavy, if all data is transmitted through unicast, the network device is overburdened. Broadcasting and multicasting can support point-to-multipoint communication, that is, a network device transmits same data to a plurality of terminal devices, for example, a mobile phone television service. Broadcasting is the most common form. In a broadcast data transmission manner, all terminal devices located in a local area network receive data transmission, and path selection does not need to be performed for broadcasting. Therefore, network costs are relatively low, but a personalized service cannot be provided for a plurality of terminal devices that receive data. However, in multicasting, data is transmitted to a group of terminal devices, and terminal devices that require a same data stream can share one data stream, reducing network device load and providing more abundant services than that in broadcasting. However, multicasting does not have an error correction mechanism compared with unicasting, and communication quality is severely affected when packet loss occurs. Therefore, a relatively robust modulation and coding scheme needs to be used, resulting in low spectral efficiency.

With increasingly wide application of broadcast and multicast communication modes, spectral efficiency of communication systems needs to be urgently improved.

<NPL>, relates to physical layer procedure.

<CIT> relates to method for transmitting ACK/NACK response for broadcast signal/multicast signal in wireless communication system, and device therefor.

Implementations of this application provide a communication method and an apparatus, to improve spectrum resource efficiency of a communication system.

A network architecture and a service scenario that are described in the implementations of this application are intended to describe the technical solutions in the implementations of this application more clearly, and do not constitute a limitation on the technical solutions provided in the implementations of this application. A person of ordinary skill in the art may be aware that the technical solutions provided in the implementations of this application are also applicable to similar technical problems as the network architecture evolves and new service scenarios emerge.

In descriptions of the implementations of this application, "at least one" refers to one or more, and "a plurality of" refers to two or more. The term "and/or" describes an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following three cases: Only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. The character "/" generally indicates an "or" relationship between the associated objects. "At least one item (piece) of the following" or a similar expression thereof refers to any combination of these items, including any combination of singular items (pieces) or plural items (pieces). For example, at least one (piece) of a, b, or c may represent: a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural.

In addition, unless otherwise stated, in the implementations of this application, ordinal numbers such as "first" and "second" are used to distinguish between a plurality of objects, and are not intended to limit an order, a time sequence, a priority, or importance of the plurality of objects. For example, a first identifier and a second identifier are identifiers with different meanings, but do not indicate different content, priorities, importance, or the like of the two identifiers.

In the following, some terms of the implementations of this application are described, to help a person skilled in the art have a better understanding.

A terminal device includes a device that provides a user with voice and/or data connectivity, for example, may include a handheld device having a wireless connection function, or a processing device connected to a wireless modem. The terminal device may communicate with a core network through a radio access network (radio access network, RAN) and exchange voice and/or data with the RAN. The terminal device may include user equipment (user equipment, UE), a wireless terminal device, a mobile terminal device, a subscriber unit (subscriber unit), a subscriber station (subscriber station), a mobile station (mobile station), a remote station (remote station), an access point (access point, AP), a remote terminal (remote terminal), an access terminal (access terminal), a user terminal (user terminal), a user agent (user agent), a user device (user device), or the like. For example, the terminal device may include a mobile phone (which is also referred to as a "cellular" phone), a computer having a mobile terminal device, a portable, pocket-sized, handheld, computer built-in, or vehicle-mounted apparatus, a smart wearable device, and the like. For example, the terminal device is a device such as a personal communications service (personal communications service, PCS) phone, a cordless phone, a session initiation protocol (session initiation protocol, SIP) phone, a wireless local loop (wireless local loop, WLL) station, or a personal digital assistant (personal digital assistant, PDA). The terminal device further includes a limited device, for example, a device with low power consumption, a device with a limited storage capability, or a device with a limited computing capability. For example, the terminal device may be an information sensing device, for example, a barcode, radio frequency identification (radio frequency identification, RFID), a sensor, a global positioning system (global positioning system, GPS), or a laser scanner. A specific technology and a specific device form that are used by the terminal device are not limited in the implementations of this application. For ease and brevity of description, UE is used as an example for the terminal device in the following description.

In different systems, an access network device corresponds to different devices. For example, in a second generation (2nd generation, <NUM>) communication system, a RAN device may include a base station and a base station controller. In a third generation (3rd generation, <NUM>) communication system, a RAN device may include a base station and a radio network controller (radio network controller, RNC); include an evolved base station (NodeB, eNB, or e-NodeB, evolved NodeB) in a long term evolution (long term evolution, LTE) system or a long term evolution-advanced (long term evolution-advanced, LTE-A) system; may include a next generation node B (next generation node B, gNB) in a fifth generation (the 5th generation, <NUM>) new radio (new radio, NR) system; or may include a centralized unit (centralized unit, CU) and a distributed unit (distributed unit, DU) in a cloud radio access network (cloud radio access network, Cloud RAN) system. A new network side device may correspond to a future evolved or emerging system. This is not limited in the implementations of this application.

The communication method provided in the implementations of this application is applied to a broadcast/multicast mode in communication systems such as a <NUM> new radio (new radio, NR) communication system and a long term evolution (long term evolution, LTE) communication system. The following describes some terms in the implementations of this application, to facilitate understanding by a person skilled in the art.

There are two broadcast/multicast service modes in an LTE communication system: a multimedia broadcast multicast service (multimedia broadcast multicast service, MBMS) mode and a single-cell point-to-multipoint (single-cell point-to-multipoint, SC-PTM) mode.

The MBMS broadcast mode provides a point-to-multipoint multimedia data transmission mechanism. As shown in <FIG>, a plurality of cells in broadcast areas of neighboring base stations generally form an MBMS area. A same service is sent on a same time-frequency resource in cells in a same MBMS area, to improve transmission signal strength of the MBMS, and to improve reception strength of a terminal device (terminal equipment, TE) located in an edge cell. A broadcast area in an MBMS mode needs to be statically planned in advance. A size of the area and a quantity of covered cells are relatively fixed and an order of magnitude is large. Service content transmitted in the area is also statically configured. Consequently, flexible and dynamic area adjustment cannot be performed based on a location of the terminal device and a required service. Currently, the MBMS mode has some disadvantages. In one aspect, because of a static configuration of the MBMS area, all control information of the MBMS area is carried in radio resource control (radio resource control, RRC) signaling, and currently there is no channel state information (channel state information, CSI) feedback and hybrid automatic repeat request (hybrid automatic repeat request, HARQ) feedback for the MBMS mode. Consequently, scheduling parameters such as a resource configuration and a modulation and coding scheme cannot be flexibly and dynamically adjusted. In another aspect, for UE located in the MBMS area and not required to receive a broadcast service, the base station still needs to send a broadcast service to the UE on a broadcast resource, causing a serious waste of resources.

In the MBSFN broadcast mode, the access network device configures a multicast control channel (multicast control channel, MCCH) of the MBSFN by using a system information block (system information block, SIB), including information required for receiving the MCCH, and including at least one of a time domain position of the MCCH, an area identifier, and a modulation and coding scheme (modulation and coding scheme, MCS). The MCCH carries information required for receiving a multicast traffic channel (multicast traffic channel, MTCH), including configuration information of the MTCH, for example, at least one of a temporary mobile group identity (temporary mobile group identity, TMGI), a session identifier (session ID), a time domain position of the MTCH, and an MCS. The UE receives, based on the configuration information, a physical channel PMCH, and obtains service data carried on the PMCH. It should be noted that the two logical channels MCCH and MTCH are both mapped to the PMCH at a physical layer, and the PMCH carries service data in the MTCH.

The SC-PTM broadcast mode supports providing a broadcast service in a single cell. As shown in <FIG>, a base station may perform broadcasting or multicasting for a group of UEs in a cell. In the SC-PTM mode, services do not need to be synchronously transmitted in a plurality of cells. A granularity of multicast cell planning in the SC-PTM mode may be a physical cell, which can be configured based on a UE location and a service requirement. Compared with large area planning of the MBMS, planning in the SC-PTM mode is more flexible. In addition, control information of the SC-PTM mode is carried in physical layer signaling, for example, downlink control information (downlink control information, DCI). Therefore, dynamic scheduling can be supported. In the SC-PTM mode, scheduling parameters such as a resource configuration and a modulation and coding scheme can be flexibly adjusted. In addition, a service in the SC-PTM mode can further be dynamically switched to a unicast service. However, the SC-PTM mode has the following disadvantages: First, the SC-PTM mode supports only single-cell point-to-multipoint. Consequently, mobility is insufficiently supported. When UE is handed over between different cells, service continuity of the UE may be affected. Second, coverage of a single cell is relatively small, and further there is a low probability that a plurality of UEs share a broadcast service. Consequently, gains of the SC-PTM mode are not obvious compared with those in unicast transmission. Third, minimum signal-to-noise ratios of all served UEs in the cell need to be ensured in the SC-PTM mode. The SC-PTM mode has little gain compared with unicast transmission. In some scenarios, spectral efficiency of the SC-PTM mode is even lower than that of unicast transmission. In addition, no feedback mechanism is introduced in the SC-PTM mode currently.

In the SC-PTM broadcast mode, the access network device configures a single-cell multicast control channel (single-cell multicast control channel, SC-MCCH) by using a SIB, including a time domain position of the SC-MCCH. SC-PTM configuration information carried on the SC-MCCH includes configuration information of a single-cell multicast traffic channel (single-cell multicast traffic channel, SC-MTCH). The configuration information includes a TMGI, a session ID, a G-RNTI used to scramble DCI, and time domain discontinuous reception (discontinuous reception, DRX) configuration information. It should be noted that the two logical channels SC-MCCH and SC-MTCH are both mapped to a PDSCH at a physical layer, and the DCI is carried on a physical downlink control channel (physical downlink control channel, PDCCH). The terminal device obtains, by detecting the DCI scrambled by the G-RNTI, a physical downlink channel PDSCH scheduled by using the DCI, and further obtains service data carried on the PDSCH.

A <NUM> NR system is a next-generation wireless communication system of an LTE system, and has better and more flexible forward compatibility than the LTE system. The multi-cell multipoint-to-multipoint (multi-cell multipoint-to-multipoint, MC-MTM) broadcast mode can be obtained through extension based on SC-PTM. The MC-MTM mode has the following features: First, an MC-MTM broadcast/multicast area includes a plurality of cells and may be dynamically planned based on a UE location and a required service. A configuration in the MC-MTM mode is more flexible compared with static large area planning in the MBMS mode. Second, the MC-MTM broadcast/multicast area includes a plurality of cells, and a coverage area thereof is larger than a coverage area in the SC-PTM mode. Therefore, a probability that a plurality of UEs share a broadcast service is relatively high, and further service continuity of the UEs is relatively stable when a cell handover occurs. Third, in the MC-MTM mode, single frequency networks (single frequency networks, SFNs) may be applied to form a multimedia broadcast multicast service single frequency network (multimedia broadcast multicast service single frequency network, MBSFN) to transmit a broadcast service. In this way, a signal-to-noise ratio is improved. This resolves a problem that spectral efficiency is low because minimum signal-to-noise ratios of all served UEs in the cell need to be ensured in the SC-PTM mode.

In the MC-MTM broadcast mode, the access network device configures a multi-cell multicast control channel (multi-cell multicast control channel, MC-MCCH) of the MC-MTM by using a SIB, which includes a time domain position of the MC-MCCH, and is used to specify a time domain position at which the UE receives the MC-MCCH. The MC-MTM configuration information carried on the MC-MCCH includes configuration information of a multi-cell multicast traffic channel (multi-cell multicast traffic channel, MC-MTCH). The configuration information includes a temporary TMGI, a session ID, a G-RNTI used to scramble DCI, a scrambling code identifier used to scramble a PDSCH, a cell list of the MC-MTCH, and DRX configuration information. It should be noted that the two logical channels MC-MCCH and MC-MTCH are both mapped to a PDSCH at a physical layer, and the DCI is carried on a physical downlink control channel (physical downlink control channel, PDCCH). The UE obtains, by detecting the DCI scrambled by the G-RNTI, a physical downlink channel PDSCH scheduled by using the DCI, and further obtains service data carried on the PDSCH.

Compared with the SC-PTM broadcast mode in which a cell identifier is used to scramble the PDSCH in a configuration procedure, in the MC-MTM broadcast mode, a configuration procedure of a scrambling code identifier of the PDSCH is added. PDSCHs of a plurality of cells or a plurality of beams located in the MC-MTM broadcast area are scrambled by using a same scrambling code identifier, so that signals of the plurality of cells or the plurality of beams may be combined at a physical layer, thereby enhancing a signal-to-noise ratio. In addition, a cell list configuration is further added to the MC-MTM broadcast mode. When the UE is handed over between cells in the broadcast area, the UE may determine, based on the cell list, that the UE is located in a same MC-MTM area, and that the foregoing configuration procedure does not need to be performed again. Broadcast data may be seamlessly received directly in the broadcast area, to improve broadcast service continuity. It should be noted that the MC-MTM broadcast mode may be switched to the SC-PTM broadcast mode by adjusting the configuration procedure. For example, the scrambling code identifier of the PDSCH is no longer configured, or the scrambling code identifier is configured to a physical cell identifier of a cell in which the UE is located.

Currently, no feedback mechanism is introduced in the foregoing broadcast/multicast modes. Therefore, a relatively robust modulation and coding scheme needs to be used, resulting in relatively low spectral efficiency of a system. Implementations of this application provide a signal sending method to implement a feedback and retransmission mechanism. The method may be applied to the foregoing broadcast/multicast modes, to improve spectral efficiency of a broadcast system.

For ease of understanding, the following specifically describes the communication method provided in the implementations of this application with reference to the accompanying drawings.

As shown in <FIG>, an implementation of this application provides a communication method, including steps <NUM> to <NUM>. The communication method includes a signal sending method.

<NUM>: An access network device sends a first downlink channel to a terminal device, where the first downlink channel is used to carry first data, and the first downlink channel is scrambled by using a first identifier.

<NUM>: The terminal device receives the first downlink channel. Further, the terminal device obtains, based on the first identifier, the first data carried on the first downlink channel.

In an optional design, the method further includes step <NUM>: The terminal device determines a channel resource used to feed back acknowledgment information, and the terminal device sends a negative acknowledgment to the access network device.

Further, the method further includes step <NUM>: The access network device receives the negative acknowledgment from the terminal device, and the access network device determines a second area based on the channel resource of the negative acknowledgment, where the second area is a retransmission area.

The communication method provided in step <NUM> to step <NUM> may be applied to a feedback mechanism. When failing to receive the first downlink channel, the terminal device may determine, by using at least one of a first resource set, an identification information set, and a correspondence therebetween, the channel resource carrying the acknowledgment, and the terminal device feeds back the acknowledgment to the access network device. The access network device determines the corresponding second area by using identification information corresponding to the channel resource carrying the negative acknowledgment. The access network device may learn of a transmission status of the first data by using the communication method provided in this implementation of this application, to improve robustness of a communication system.

In an optional design, the method further includes step <NUM>: The access network device sends a second downlink channel to the terminal device, where the second downlink channel is used to retransmit the first data, the second downlink channel is scrambled by using a second identifier, and the first identifier and the second identifier are identifiers configured by the access network device.

Further, the method further includes step <NUM>: The terminal device receives the second downlink channel, where the second downlink channel is used to retransmit the first data; and the terminal device obtains the first data based on the second identifier.

The communication method provided in step <NUM>, step <NUM>, step <NUM>, and step <NUM> may be applied to a retransmission mechanism. The access network device sends the first downlink channel to a first area, where the first downlink channel carries the first data. The access network device sends the second downlink channel to the second area, where the second downlink channel is used to retransmit the first data. In a scenario in which the second area is less than the first area, the access network device may send a retransmission channel to a local area, to reduce load of the network device while ensuring communication quality, and improve spectral efficiency of the communication system.

It should be noted herein that execution of step <NUM> does not depend on step <NUM>. After step <NUM> and step <NUM>, step <NUM> and step <NUM> may be performed independently or in combination, and whether an association relationship exists between step <NUM> and step <NUM> is determined based on a specific solution.

The communication method provided in step <NUM> to step <NUM> may be applied to the feedback and retransmission mechanism. After failing to receive the first downlink channel, the terminal device may feed back the acknowledgment to the access network device, and further obtain the retransmission channel, to ensure communication quality. The access network device may determine the retransmission area by using the channel resource for feeding back the acknowledgment. Further, the access network device sends the retransmission channel to the local area, but does not need to send retransmission information to an initial transmission area. Therefore, spectral efficiency of the communication system is improved.

In step <NUM>, the access network device sends the first downlink channel to the terminal device, where the first downlink channel is used to carry the first data, and the first downlink channel is scrambled by using the first identifier.

In a possible implementation, the first identifier includes at least one of a first cell identifier and a first radio network temporary identifier, the first cell identifier is an identifier corresponding to the first area, and the first area includes one or more cells located in a broadcast area of at least one access network device. Specifically, the first area is a first area set or a proper subset of the first area set, and the first area set includes all cells in a broadcast area of the access network device and all cells in a broadcast area of another access network device that may be used for retransmission. It should be noted that the first cell identifier is a cell identifier or a virtual cell identifier and is different from a radio network temporary identifier. For example, when the first identifier includes the first cell identifier and the first radio network temporary identifier, the first identifier may be represented as follows: <MAT>
cinit represents the first identifier used to scramble the first downlink channel, q is a codeword, ns is a slot identifier, nRNTI represents the first radio network temporary identifier RNTI, and <MAT> and <MAT> are each a first cell identifier corresponding to a corresponding broadcast mode. When the broadcast area is one cell, the first cell identifier may correspond to a physical cell identifier. When the broadcast area is a plurality of cells, the first cell identifier may correspond to a unified virtual cell identifier of the plurality of cells. Further, optionally, the at least one of the first cell identifier and the first radio network temporary identifier is carried in a first broadcast message. Specifically, the first cell identifier and the first radio network temporary identifier may be configured by using a same broadcast message or different broadcast messages, or by using a same information element (information element, IE) or different information elements in a same broadcast message. This is not limited in this implementation of this application.

It should be noted that the first downlink channel is used to transmit the first data to the first area. In a possible case, the terminal device is located in the first area to receive the first downlink channel. In another possible case, the terminal device is not located in the first area, and the access network device sends the first downlink channel to the terminal device through the first area, or the access network device sends the first downlink channel in the first area. A location relationship between the terminal device and the first area is not limited in this implementation of this application.

The communication method provided in this implementation of this application may be applied to a plurality of broadcast modes, which are separately described below.

In a first possible implementation, the method is applied to a multi-cell multipoint-to-multipoint (multi-cell multipoint-to-multipoint, MC-MTM) broadcast mode. The first downlink channel is a physical downlink shared channel (physical downlink shared channel, PDSCH), and the first identifier includes at least one of a group radio network temporary identifier (group radio network temporary identifier, G-RNTI) and the first cell identifier. According to the method provided in this implementation of this application, the access network device sends the PDSCH to the terminal device, where the PDSCH is used to carry the first data, and the PDSCH is scrambled by using at least one of the G-RNTI and the first cell identifier.

Optionally, the first cell identifier is a scrambling code identifier used to scramble the first downlink channel. Further, optionally, the first cell identifier is a cell identifier of a broadcast area, and the broadcast area includes a plurality of cells or a plurality of beams. Further, the first cell identifier corresponds to a physical cell identifier of one cell or a unified identifier of a plurality of cells. In this implementation of this application, the first cell identifier used to scramble the PDSCH is configured for the plurality of cells, so that the plurality of cells or the plurality of beams in the MC-MTM broadcast area may be scrambled by using the unified first cell identifier. In this manner, signals of the plurality of cells or the plurality of beams may be combined at a physical layer, to enhance a signal-to-noise ratio.

Optionally, the G-RNTI and the first cell identifier are configured by using a broadcast message, and the G-RNTI and the first cell identifier may be configured by using a same broadcast message or different broadcast messages, or by using a same IE or different IEs in a same broadcast message. This is not limited in this implementation of this application.

Specifically, the access network device configures a multi-cell multicast control channel (multi-cell multicast control channel, MC-MCCH) of the MC-MTM by using a system information block (system information block, SIB), including time domain position information of the MC-MCCH. MC-MTM configuration information carried on the MC-MCCH includes configuration information of a multi-cell multicast traffic channel (multi-cell multicast traffic channel, MC-MTCH). The configuration information includes a temporary mobile group identity (temporary mobile group identity, TMGI), a session identifier (session ID), a G-RNTI used to scramble downlink control information (downlink control information, DCI), a scrambling code identifier used to scramble a PDSCH, a cell list of the MC-MTCH, and time domain discontinuous reception (discontinuous reception, DRX) configuration information. It should be noted that the two logical channels MC-MCCH and MC-MTCH are both mapped to a same PDSCH at a physical layer, and the DCI is carried on a physical downlink control channel (physical downlink control channel, PDCCH).

Optionally, the first downlink channel PDSCH is scheduled by using the DCI, and a cyclic redundancy code (cyclic redundancy code, CRC) of the DCI is scrambled by using the G-RNTI.

In a second possible implementation, the method is applied to a multimedia broadcast multicast service single frequency network (multimedia broadcast multicast service single frequency network, MBSFN) broadcast mode. The first downlink channel is a physical multicast channel (physical multicast channel, PMCH), and the first identifier is the first cell identifier. According to the method provided in this implementation of this application, the access network device sends the PMCH to the terminal device, where the PMCH is used to carry the first data, and the PMCH is scrambled by using the first cell identifier.

Optionally, the first cell identifier is a cell identifier of a broadcast area, and the broadcast area includes at least one cell or beam. Further, when the broadcast area includes one cell, the first cell identifier is a physical cell identifier corresponding to the cell. When the broadcast area includes a plurality of cells or a plurality of beams, the first cell identifier is a unified identifier of the plurality of cells or the plurality of beams.

Optionally, the first cell identifier is configured by using a broadcast message.

Specifically, the access network device configures a multicast control channel (multicast control channel, MCCH) of the MBSFN by using a SIB, including information required for receiving the MCCH, for example, a time domain position of the MCCH, the first cell identifier, and a modulation and coding scheme (modulation and coding scheme, MCS) of the MCCH. The MCCH carries information required for receiving a multicast traffic channel (multicast traffic channel, MTCH), including configuration information of the MTCH, for example, at least one of a TMGI, a session ID, a time domain position of the MTCH, or an MCS of the MTCH. It should be noted that the two logical channels MCCH and MTCH are both mapped to a same PMCH at a physical layer, and the PMCH carries service data in the MTCH.

Optionally, the first downlink channel PMCH is semi-statically configured by using higher layer signaling, where the higher layer signaling includes broadcast signaling and radio resource control (radio resource control, RRC) dedicated signaling.

In a third possible implementation, the method is applied to a single-cell point-to-multipoint (single-cell point-to-multipoint, SC-PTM) broadcast mode. The first downlink channel is a PDSCH, and the first identifier is at least one of a G-RNTI and the first cell identifier. According to the method provided in this implementation of this application, the access network device sends the PDSCH to the terminal device, where the PDSCH is used to carry the first data, and the PDSCH is scrambled by using at least one of the G-RNTI and the first cell identifier.

Optionally, the first cell identifier is a physical cell identifier of a corresponding cell.

Optionally, both the G-RNTI and the scrambling code identifier are configured by using a broadcast message, and the G-RNTI and the scrambling code identifier may be configured by using a same broadcast message or different broadcast messages, or by using a same IE or different IEs in a same broadcast message. This is not limited in this implementation of this application.

Specifically, the access network device configures a single-cell multicast control channel (single-cell multicast control channel, SC-MCCH) of the SC-PTM by using a SIB, including configuring time domain position information of the SC-MCCH. SC-PTM configuration information carried on the SC-MCCH includes configuration information of a single-cell multicast traffic channel (single-cell multicast traffic channel, SC-MTCH). The configuration information includes a TMGI, a session ID, a G-RNTI used to scramble DCI, and DRX configuration information. It should be noted that the two logical channels SC-MCCH and SC-MTCH are mapped to a same PDSCH at a physical layer, and the DCI is carried on a PDCCH.

Optionally, the first downlink channel PDSCH is scheduled by using the DCI, and a CRC of the DCI is scrambled by using the G-RNTI.

It should be noted that the configuration method described in this implementation of this application is merely an example, and another similar configuration procedure is not excluded. In addition, the communication method may be further applied to another possible broadcast mode.

In step <NUM>, the terminal device receives the first downlink channel, where the first downlink channel is used to carry the first data, and further the terminal device obtains the first data based on the first identifier.

The terminal device receives the first downlink channel in the first area, where the first area includes one or more cells located in a broadcast area of at least one access network device. Specifically, the first area is a first area set or a proper subset of the first area set, and the first area set includes all cells in a broadcast area of the access network device and all cells in a broadcast area of another access network device that may be used for retransmission.

Optionally, the terminal device receives at least one of the first cell identifier and the first radio network temporary identifier, where the at least one of the first cell identifier and the first radio network temporary identifier is carried in a first broadcast message. Specifically, the first cell identifier and the first radio network temporary identifier may be configured by using a same broadcast message or different broadcast messages, or by using a same IE or different IEs in a same broadcast message. This is not limited in this implementation of this application.

It should be noted that the communication method provided in this implementation of this application may be applied to a plurality of broadcast modes. The following uses the MC-MTM as an example for description. Another broadcast mode is also applicable.

In a possible implementation, the method is applied to an MC-MTM broadcast mode, and the terminal device receives the first downlink channel PDSCH and obtains the first data. Specifically, the terminal device receives, in the first area, the first downlink channel from the access network device, obtains, by detecting the DCI scrambled by using the G-RNTI, the physical downlink channel PDSCH scheduled by using the DCI, descrambles the PDSCH by using the first identifier, and then obtains the first data carried on the PDSCH, where the first data is service data of the MC-MTCH.

In step <NUM>, the terminal device determines the channel resource used to feed back the acknowledgment information. Further, the terminal device sends the negative acknowledgment to the access network device.

In a scenario in which the terminal device fails to receive the first downlink channel, or the terminal device fails to descramble the first downlink channel after receiving the first downlink channel, or the terminal device fails to check the first data, the terminal device needs to feed back an acknowledgment to the access network device. Further, optionally, as described in step <NUM> and step <NUM>, the access network device may retransmit the first data to the terminal device. In this implementation of this application, for ease of description, the following describes, by using an example in which the first downlink channel fails to be received, a terminal device that needs to receive retransmitted data.

According to the communication method provided in this implementation of this application, when failing to receive the first downlink channel, the terminal device may feed back an acknowledgment to the access network device by using a hybrid automatic repeat request (hybrid automatic repeat request, HARQ) mechanism. Specifically, in a first possible implementation of the HARQ mechanism, the terminal device performs no feedback when successfully receiving the first downlink channel, to avoid interference caused by excessive uplink data, and the terminal device feeds back a negative acknowledgment (negative acknowledgment, NACK) to the access network device when failing to receive the first downlink channel. In a second possible implementation of the HARQ mechanism, UE in an RRC connected mode feeds back an acknowledgment (acknowledgment, ACK) when successfully receiving the first downlink channel, and feeds back a NACK when failing to receive the first downlink channel. However, UE in an RRC idle mode feeds back a NACK only when failing to receive the first downlink channel, but does not feed back an acknowledgment when successfully receiving the first downlink channel.

Before feeding back the acknowledgment, the terminal device determines a channel resource used to feed back a NACK, where the channel resource is a feedback channel resource corresponding to the second area, the second area is a retransmission area and includes one or more cells located in the broadcast area of the at least one access network device, the second area is the first area set or the proper subset of the first area set, and the first area set includes all the cells in the broadcast area of the access network device and all the cells in the broadcast area of the another access network device that may be used for retransmission. In a possible scenario, that the second area is a subset of the first area may be understood as that the retransmission area is included in an initial transmission area. In another possible scenario, the second area may have an intersection with the first area, but is not completely included in the first area. For example, UE receives an initial transmission channel from an access network device A, where the initial transmission channel corresponds to the first area. The UE receives a retransmission channel from an access network device B, where the retransmission channel corresponds to the second area, and the second area is not included in the first area.

The terminal device determines, based on corresponding identification information, a corresponding channel resource used to feed back a NACK. Further, the terminal device feeds back an acknowledgment to the access network device by using the corresponding feedback channel resource.

In a first possible implementation, the channel resource used to feed back the acknowledgment corresponds to a physical cell. Specifically, one channel resource or one group of channel resources is/are configured for each cell to feed back an acknowledgment, and all UEs located in the cell perform a feedback by using corresponding channel resources.

In a second possible implementation, the UE in the RRC connected mode feeds back an acknowledgment on a channel resource indicated by dedicated signaling, where the dedicated signaling includes one of an RRC message and DCI. Specifically, before step <NUM>, step <NUM> is further included: The access network device indicates, to the terminal device by using the dedicated signaling, a channel resource used to feed back an acknowledgment. The terminal device may determine, after receiving the dedicated signaling, the channel resource used to feed back the acknowledgment. Further, the terminal device feeds back the acknowledgment by using the corresponding feedback channel resource.

In a third possible implementation, the channel resource used to feed back the acknowledgment is determined by using at least one of an identification information set, a first resource set, and a correspondence therebetween. Specifically, before step <NUM>, the method further includes step <NUM>. The terminal device obtains the identification information set and the first resource set from the access network device. The channel resource belongs to the first resource set, the first resource set is a set of feedback channel resources corresponding to the first area or the first area set. For definitions of the first area and the first area set, refer to related descriptions in step <NUM>. The identification information set is a set of identification information corresponding to the first area or the first area set, and different identification information corresponds to different areas. For example, the identification information may be at least one of a physical cell identifier, a synchronization signal block (synchronization signal and PBCH block, SSB) index, and a reference signal (reference signal, RS). The physical cell identifier may identify a physical cell in which the terminal device is located, the SSB index may identify an area covered by a corresponding beam, and the RS may identify a corresponding area. A correspondence exists between the identification information in the identification information set and the feedback channel resource in the first resource set. The terminal device determines, based on the identification information, the feedback channel resource corresponding to the identification information. Further, the terminal device feeds back the acknowledgment by using the corresponding channel resource.

Optionally, the identification information set and the first resource set are indicated by using a fourth broadcast message. Specifically, the identification information set and the first resource set may be configured by using a same broadcast message or different broadcast messages, or by using a same information element IE or different information elements IEs in a same broadcast message. This is not limited in this implementation of this application.

In step <NUM>, the access network device receives the negative acknowledgment from the terminal device. Further, the access network device determines the second area based on the channel resource of the negative acknowledgment, where the second area is the retransmission area.

After receiving the negative acknowledgment, the access network device may determine the second area based on the channel resource of the negative acknowledgment. For a definition of the second area, refer to related descriptions in step <NUM>. Step <NUM> to step <NUM> may be applied to a feedback mechanism of a broadcast system. When failing to receive the first downlink channel from the access network device, the terminal device feeds back the negative acknowledgment to the access network device by using the corresponding feedback channel resource. After receiving the negative acknowledgment, the access network device may determine the second area based on a correspondence between channel resources. A method for determining the second area is as follows:
In a first possible implementation, the channel resource used to feed back the acknowledgment corresponds to a physical cell. Specifically, one channel resource or one group of channel resources is/are configured for each cell to feed back the acknowledgment, and UEs located in the cell perform a feedback on corresponding channel resources by using a same sequence.

Further, after receiving the negative acknowledgment from the terminal device, the access network device determines, based on a correspondence between a channel resource for the negative acknowledgment and a physical cell, the second area corresponding to the physical cell. For a definition of the second area, refer to related descriptions in step <NUM>. It should be noted that, for each physical cell, there may be a corresponding second area, and the second area is a retransmission area of the corresponding physical cell.

In a second possible implementation, the UE in the RRC connected mode feeds back the acknowledgment on the channel resource indicated by the dedicated signaling. Specifically, before step <NUM>, step <NUM> is further included: The access network device indicates, to the terminal device by using the dedicated signaling, the channel resource used to feed back the acknowledgment.

Further, after receiving the negative acknowledgment from the UE, the access network device determines, based on the channel resource of the negative acknowledgment, the second area corresponding to the retransmission area of the UE.

In a third possible implementation, the access network device determines corresponding identification information based on a channel resource that carries the negative acknowledgment. Specifically, the channel resource belongs to a first resource set, the identification information belongs to an identification information set, and a correspondence exists between identification information in the identification information set and the feedback channel resource in the first resource set. For example, the identification information may be at least one of a physical cell identifier, an SSB index, and an RS.

Further, after receiving the negative acknowledgment from the terminal device, the access network device determines, based on the channel resource of the negative acknowledgment, the identification information corresponding to the negative acknowledgment, and further determines the second area corresponding to the identification information.

For example, <FIG> shows a possible method for determining a feedback channel resource. The identification information set includes three SSB indexes, which are respectively an SSB <NUM> to an SSB <NUM>. The first resource set includes three feedback channel resources, which are respectively a feedback channel resource <NUM> to a feedback channel resource <NUM>. Elements in the identification information set are in a one-to-one correspondence with elements in the first resource set. The SSB <NUM> corresponds to the feedback channel resource <NUM>, the SSB <NUM> corresponds to the feedback channel resource <NUM>, and the SSB <NUM> corresponds to the feedback channel resource <NUM>. Each SSB index corresponds to one beam (beam). When UE located in a beam <NUM> broadcast area corresponding to the SSB <NUM> fails to receive the first downlink channel, the UE finds, based on the identification information set and the first resource set, the feedback channel resource <NUM> corresponding to the SSB <NUM>, and feeds back a NACK by using the feedback channel resource <NUM>. After receiving the NACK carried on the feedback channel resource <NUM>, the access network device determines, based on the feedback channel resource <NUM>, that the identification information corresponding to the feedback channel resource <NUM> is the SSB <NUM>, and further determines that retransmitted data needs to be sent only in a beam <NUM> direction corresponding to the SSB <NUM>. When the access network device does not receive a NACK on another feedback channel resource, the access network device does not need to send the retransmitted data in the other two beam directions.

For another example, the identification information set includes two RSs, an RS <NUM> corresponds to a cell (cell) <NUM>, and an RS <NUM> corresponds to a cell <NUM>. The first resource set includes two feedback channel resources, namely, a channel resource <NUM> and a channel resource <NUM>. Elements in the identification information set is in a one-to-one correspondence with elements in the first resource set, the RS <NUM> corresponds to the channel resource <NUM>, and the RS <NUM> corresponds to the channel resource <NUM>. When UE in the cell <NUM> fails to receive the first downlink channel, the UE finds the corresponding channel resource <NUM> based on the corresponding identification information RS <NUM>, and feeds back a negative acknowledgment by using the channel resource <NUM>. After receiving the NACK carried on the channel resource <NUM>, the access network determines the corresponding RS <NUM> based on the channel resource <NUM>, and further determines that the cell <NUM> corresponding to the RS <NUM> is the second area.

In step <NUM>, the access network device sends the second downlink channel to the terminal device, where the second downlink channel is used to retransmit the first data, the second downlink channel is scrambled by using the second identifier, and the first identifier and the second identifier are identifiers configured by the access network device.

In this implementation of this application, both the first downlink channel and the second downlink channel are physical data channels sent in a broadcast manner. The second downlink channel is a retransmission channel of the first downlink channel, or the first downlink channel is used to initially transmit the first data, and the second downlink channel is used to retransmit the first data. The first downlink channel is scrambled by using the first identifier, the second downlink channel is scrambled by using the second identifier, and the first identifier and the second identifier are identifiers configured by the access network device. It should be noted herein that the first identifier and the second identifier are two independent identifiers configured by the access network device. The independence herein means that configuration manners are independent, but specific content may be the same or different. This is not specifically limited herein.

It should be noted that the second downlink channel is sent by the access network device in the second area and is used to carry the first data, and the second area may be understood as a retransmission area. For a definition of the second area, refer to related descriptions in step <NUM>. In a possible case, the terminal device receives the second downlink channel in the second area. In another possible case, the access network device sends the second downlink channel to the terminal device through the second area, or the access network device sends the second downlink channel in the second area. A location relationship between the terminal device and the second area is not limited in this implementation of this application.

Optionally, the access network device that sends the second downlink channel is different from the access network device that sends the first downlink channel. For example, an access network device A sends the first downlink channel to the terminal device, and an access network device B sends the second downlink channel to the terminal device. The first downlink channel and the second downlink channel are respectively used to initially transmit and retransmit the first data. This may be understood as that the terminal device may obtain the retransmission channel by using different access network devices.

Optionally, waveform parameters of the first downlink channel and the second downlink channel are different. The waveform parameter includes at least one of a subcarrier spacing, a cyclic prefix (cyclic prefix, CP), and a reference signal (reference signal, RS). Specifically, the first downlink channel is used to initially transmit the first data, and a broadcast area of the first downlink channel needs to cover the first area. For a definition of the first area, refer to related descriptions in step <NUM>. In a scenario in which the first area is larger, a multipath delay of data transmission is larger. Therefore, a larger CP needs to be configured for the first downlink channel. In this scenario, a corresponding subcarrier spacing and an RS time domain density are smaller. However, the second downlink channel is used to retransmit the first data to the second area. The second area is usually smaller compared with the first area. In this scenario, a smaller CP may be configured for the second downlink channel, and correspondingly a larger subcarrier spacing and a larger RS time domain density may be configured.

In a first possible implementation, at least one of a first control channel for scheduling the first downlink channel and a second control channel for scheduling the second downlink channel includes a first indication field, and the first indication field is used to indicate that transmission of the second downlink channel is retransmission for the first downlink channel. Further, the UE may determine a retransmission relationship between the first control channel and the second control channel based on the first indication field in the first control channel and the second control channel, and further obtain the first data. For example, DCI for scheduling the first downlink channel and DCI for scheduling the second downlink channel may include a HARQ process number indication field, and two downlink channels with a same HARQ process number are respectively an initial transmission channel and a retransmission channel. Further, the UE may combine received channels based on the HARQ process number, and obtain the first data.

In a second possible implementation, a preset or predefined time sequence relationship exists between a time domain resource of the first downlink channel and a time domain resource of the second downlink channel. Specifically, a time sequence-based implicit rule exists between the time domain resource of the first downlink channel and the time domain resource of the second downlink channel. The time sequence-based implicit rule is used to indicate a relationship between the initial transmission channel and the retransmission channel. Further, the UE may determine the retransmission relationship between the initial transmission channel and the retransmission channel based on the time sequence relationship, and then obtain the first data. For example, the first downlink channel is not scheduled by using DCI, and the second downlink channel is scheduled by using DCI. In this scenario, a time point at which the first data is initially transmitted on the first downlink channel may be used to correspond to a HARQ process number, and different time points correspond to different HARQ process numbers. The HARQ process number is included in the DCI for scheduling the second downlink channel to indicate that the second downlink channel is the retransmission channel of the first downlink channel. Further, the UE may determine the retransmission relationship between the first downlink channel and the second downlink channel based on the initial transmission time of the first downlink channel and the process number in the DCI for scheduling the second downlink channel, and obtain the first data.

In a third possible implementation, the first downlink channel and the second downlink channel indicate a retransmission channel by using a preset or predefined time sequence relationship. Specifically, a relationship between initial transmission and retransmission is preconfigured or predefined between two successive downlink channels within a specific time interval. In this case, the UE may determine the retransmission relationship between the first downlink channel and the second downlink channel based on transmission time of the first downlink channel and transmission time of the second downlink channel, and further obtain the first data.

In another possible implementation, based on descriptions of the foregoing three possible implementations, in a possible scenario, any two or all of the foregoing manners may be used, for the first downlink channel and the second downlink channel, to indicate a retransmission relationship between the first downlink channel and the second downlink channel.

The first identifier and the second identifier are separately configured by the access network device, and are respectively used to scramble the first downlink channel and the second downlink channel. Specifically, for the first cell identifier, refer to related descriptions in step <NUM>. The second identifier includes at least one of a second cell identifier and a second radio network temporary identifier (radio network temporary identifier, RNTI), and the second cell identifier is an identifier corresponding to the second area. It should be noted that the second cell identifier is a cell identifier or a virtual cell identifier, instead of a radio network temporary identifier.

In a possible implementation, the second cell identifier is a physical cell identifier, and is carried by a synchronization signal of a cell corresponding to the second area. In another possible implementation, the second cell identifier is an area identifier independent of the first cell identifier, and when the second area includes a plurality of cells, the second cell identifier is a unified identifier of all cells in the second area. The second area is a retransmission area and includes the one or more cells located in the broadcast area of the at least one access network device, the second area is a first area set or a proper subset of the first area set, and the first area set includes all cells in a broadcast area of the access network device and all cells in a broadcast area of another access network device that may be used for retransmission. It should be noted that an access network device used to retransmit the first data and an access network device used to initially transmit the first data may be different devices, and all cells in a broadcast area of all access network devices that may be used for retransmission are included in the first area.

Optionally, the second cell identifier is carried in a second broadcast message, and the second RNTI is carried in a third broadcast message or a UE dedicated message. The UE dedicated message includes RRC dedicated signaling sent for the UE in the RRC connected mode. The second cell identifier and the second RNTI may be configured by using a same broadcast message or different broadcast messages, or by using a same IE or different IEs in a same broadcast message. This is not limited in this implementation of this application.

Optionally, the second downlink channel is scheduled by using DCI, and a CRC of the DCI is scrambled by using the second RNTI. Therefore, the second downlink channel may support dynamic scheduling, and parameters such as a resource configuration and a modulation and coding scheme can be flexibly adjusted as required.

As shown in <FIG>, a base station is used as an example of the access network device. The base station sends the first data to cells, namely, a cell <NUM> to a cell <NUM>, located in the first area. It is assumed that only UE <NUM> located in the cell <NUM> fails to receive the first downlink channel. Further, the base station retransmits the first data to the second area in which the cell <NUM> is located, but does not need to send retransmitted data to the cell <NUM> and the cell <NUM>. The retransmitted first data is carried on the second downlink channel, and the second downlink channel is scrambled by using at least one of a second cell identifier of the cell <NUM> and a second RNTI. The access network device may send the second downlink channel to the terminal device through broadcasting or unicasting.

In a possible implementation, the access network device sends, to the second area through broadcasting, the second downlink channel that carries the retransmitted data. Optionally, the second downlink channel is scrambled by using at least one of the second cell identifier and a G-RNTI. In this implementation, the retransmitted data may be sent to the UE in the RRC connected mode and the UE in the RRC idle mode.

In another possible implementation, the access network device sends, to the second area through unicasting, the second downlink channel that carries the retransmitted data. Optionally, the second downlink channel is scrambled by using at least one of the second cell identifier and a cell radio network temporary identifier (cell radio network temporary identifier, C-RNTI). In this implementation, the retransmitted data may be sent to the UE in the RRC connected mode.

In step <NUM>, the terminal device receives the second downlink channel, where the second downlink channel is used to retransmit the first data; and further the terminal device obtains the first data based on the second identifier.

The terminal device receives the second downlink channel in the second area, where the second area includes one or more cells located in the broadcast area of the at least one access network device. The second downlink channel is scrambled by using the second identifier. The second identifier includes at least one of the second cell identifier and a second radio network temporary identifier, and the second cell identifier is an identifier corresponding to the second area. Further, the terminal device obtains, based on the second identifier, the first data carried on the second downlink channel. For definitions of the second downlink channel and the second identifier, refer to related descriptions in step <NUM>.

It should be noted that, in the method provided in this implementation of this application, steps <NUM> and <NUM> and steps <NUM> and <NUM> are optional steps, and steps <NUM> to <NUM> may be applied to a feedback mechanism, or steps <NUM> and <NUM> and steps <NUM> and <NUM> may be applied to a retransmission mechanism, or steps <NUM> to <NUM> are applied to a feedback retransmission mechanism. This is not limited in this implementation of this application.

In a first possible implementation, the communication method provided in steps <NUM> to <NUM> may be applied to the feedback retransmission mechanism. The feedback retransmission mechanism is applicable to a broadcast communication system. The access network device determines the second area by using at least one of a first resource set, an identification information set, and a correspondence therebetween. Further, a method of combining initial broadcast transmission and data retransmission for a local area is used, so that the terminal device can obtain a retransmission channel in a plurality of broadcast modes.

Specifically, the access network device sends the first data to the first area by sending the first downlink channel, where the first downlink channel is scrambled by using the first identifier. After receiving the first downlink channel, the terminal device descrambles the first downlink channel by using the first identifier, and further obtain the first data. When failing to receive the first downlink channel, the terminal device may determine, by applying the method in step <NUM>, a channel resource corresponding to an area in which the terminal device is located and used to feed back an acknowledgment, and send a negative acknowledgment to the access network device by using the channel resource. After receiving the negative acknowledgment, the access network device determines, based on the channel resource of the negative acknowledgment, that an area corresponding to the corresponding identification information is the second area. The access network device sends the second downlink channel to the second area, where the second downlink channel carries the first data, and the second downlink channel is scrambled by using the second identifier. After receiving the second downlink channel, the terminal device descrambles the second downlink channel by using the second identifier, and further obtain the first data. The first identifier and the second identifier are identifiers independent of each other and configured by the access network device.

In a second possible implementation, the communication method provided in steps <NUM> and <NUM> and steps <NUM> and <NUM> may be applied to the retransmission mechanism. The retransmission mechanism is applicable to a broadcast communication system. A method of combining initial broadcast transmission and data retransmission for a local area is used, so that the terminal device can obtain a retransmission channel in a plurality of broadcast modes, and improve spectral efficiency of the system. Specifically, the access network device sends the first downlink channel to the first area, where the first downlink channel carries the first data. The access network device sends the second downlink channel to the second area, where the second downlink channel is used to retransmit the first data. In a scenario in which the second area is less than the first area, the access network device may send a retransmission channel to a local area, to reduce load of the network device while ensuring communication quality, and improve spectral efficiency of a communication system.

In a third possible implementation, the communication method provided in step <NUM> to step <NUM> may be applied to the feedback mechanism. The feedback mechanism is applicable to a broadcast communication system. Specifically, after receiving a negative acknowledgment, the access network device may determine, by using at least one of the first resource set, the identification information set, and the correspondence therebetween, the identification information corresponding to the channel resource carrying the negative acknowledgment, and further determine the second area. The access network device may learn of a transmission status of the first data by using the communication method provided in this implementation of this application, to improve robustness of a communication system.

UE is used as an example of the terminal device. In the conventional technology, a broadcast service not only serves UE in an RRC connected mode, but also serves UE in an RRC idle mode. On one hand, currently, there is no HARQ feedback mechanism for the UE in the RRC idle mode. The UE in the RRC idle mode may receive broadcast data, but does not have a feedback resource used to feed back an acknowledgment. Therefore, currently, a network side cannot perform broadcast retransmission for specified UE in an RRC idle mode. On the other hand, it is assumed that a feedback mechanism is introduced for UE in an RRC idle mode, but an acknowledgment feedback of an area or specified UE cannot be distinguished by using a feedback resource. After receiving a NACK, the network side can only retransmit the NACK in an entire broadcast area. However, an actual probability of NACK occurrence is generally <NUM>% to <NUM>%, which is far less than a probability of correct reception. Therefore, retransmission in the entire broadcast area is performed due to a reception failure of specific UE or a local area, greatly decreasing spectral efficiency.

The method provided in this implementation of this application combines initial broadcast transmission for a plurality of cells or a plurality of beams and data retransmission for a local area, to provide a feedback retransmission mechanism applicable to a plurality of broadcast modes such as SC-PTM, MBSFN, and MC-MTM, thereby improving resource usage efficiency of the system. In the method provided in this implementation of this application, the correspondence between the identification information set and the first resource set is further established, to calibrate a feedback acknowledgment of the UE, and enable the foregoing feedback retransmission mechanism.

When the modules or units are implemented by using hardware, the hardware may be any one or any combination of a CPU, a microprocessor, a DSP, an MCU, an artificial intelligence processor, an ASIC, an SoC, an FPGA, a PLD, a dedicated digital circuit, a hardware accelerator, or a non-integrated discrete component, and the hardware may run necessary software or does not depend on software, to perform the foregoing method procedures.

The following describes, with reference to the accompanying drawings, apparatuses configured to implement the foregoing methods in the implementations of this application. Therefore, the foregoing content may be used in subsequent implementations, and repeated content is not described.

<FIG> is a schematic block diagram of an apparatus <NUM> according to an implementation of this application. For example, the communication device <NUM> is a terminal device <NUM>. The terminal device <NUM> includes a processing module <NUM> and a transceiver module <NUM>. The processing module <NUM> may be configured to perform all operations, except receiving and sending operations, performed by the terminal device in the implementation shown in <FIG>, for example, that the terminal device descrambles a first downlink channel and obtains first data, and the method in step <NUM>, and/or configured to support another process of the technology described in this specification. The transceiver module <NUM> may be configured to perform all receiving and sending operations, for example, step <NUM> and step <NUM>, performed by the terminal device in the implementation shown in <FIG>, and/or configured to support another process of the technology described in this specification.

The transceiver module <NUM> is configured to receive a first downlink channel from an access network device, where the first downlink channel is used to carry first data.

The processing module <NUM> is configured to: after the transceiver module <NUM> receives the first downlink channel, obtain the first data based on a first identifier.

In an optional implementation, the processing module <NUM> is further configured to determine a channel resource used to feed back acknowledgment information. Further, the transceiver module <NUM> sends a negative acknowledgment to the access network device.

In an optional implementation, the transceiver module <NUM> is further configured to receive a second downlink channel, where the second downlink channel is used to retransmit the first data. Further, the processing module <NUM> obtains the first data based on a second identifier.

It should be understood that the processing module <NUM> in this implementation of this application may be implemented by a processor or a processor-related circuit component, and the transceiver module <NUM> may be implemented by a transceiver or a transceiver-related circuit component.

As shown in <FIG>, an implementation of this application further provides a communication device <NUM>. For example, the communication device <NUM> is a terminal device <NUM>. The terminal device <NUM> includes a processor <NUM>, a memory <NUM>, and a transceiver <NUM>. The memory <NUM> stores instructions or a program. The processor <NUM> is configured to execute the instructions or the program stored in the memory <NUM>. When the instructions or the program stored in the memory <NUM> are/is executed, the processor <NUM> is configured to perform the operations performed by the processing module <NUM> in the foregoing implementation, and the transceiver <NUM> is configured to perform the operations performed by the transceiver module <NUM> in the foregoing implementation.

It should be understood that the terminal device <NUM> or the terminal device <NUM> in the implementations of this application may correspond to the terminal device in the implementation shown in <FIG>, and operations and/or functions of the modules in the terminal device <NUM> or the terminal device <NUM> are respectively used to implement corresponding procedures in the implementation shown in <FIG>. For brevity, details are not described herein again.

<FIG> is a schematic block diagram of a communication device <NUM> according to an implementation of this application. For example, the communication device <NUM> is an access network device <NUM>. The access network device <NUM> includes a processing module <NUM> and a transceiver module <NUM>. The processing module <NUM> may be configured to perform all operations, for example, the communication method in step <NUM>, except receiving and sending operations, performed by the access network device in the implementation shown in <FIG>, and/or configured to support another process of the technology described in this specification. The transceiver module <NUM> may be configured to perform all receiving and sending operations, for example, the communication method in step <NUM> and step <NUM>, performed by the access network device in the implementation shown in <FIG>, and/or configured to support another process of the technology described in this specification.

The transceiver module <NUM> is configured to send a first downlink channel to a terminal device, where the first downlink channel is used to carry first data, and the first downlink channel is scrambled by using a first identifier.

In an optional implementation, the transceiver module <NUM> is further configured to receive a negative acknowledgment from the terminal device. Further, the processing module <NUM> determines a location of the terminal device based on a channel resource of the negative acknowledgment.

In an optional implementation, the transceiver module <NUM> is further configured to send a second downlink channel to the terminal device, where the second downlink channel is used to retransmit the first data, and the second downlink channel is scrambled by using a second identifier.

As shown in <FIG>, an implementation of this application further provides a communication device <NUM>. For example, the communication device <NUM> is an access network device <NUM>. The access network device <NUM> includes a processor <NUM>, a memory <NUM>, and a transceiver <NUM>. The memory <NUM> stores instructions or a program. The processor <NUM> is configured to execute the instructions or the program stored in the memory <NUM>. When the instructions or the program stored in the memory <NUM> are/is executed, the processor <NUM> is configured to perform the operations performed by the processing module <NUM> in the foregoing implementation, and the transceiver <NUM> is configured to perform the operations performed by the transceiver module <NUM> in the foregoing implementation.

It should be understood that the access network device <NUM> or the access network device <NUM> in the implementations of this application may correspond to the access network device in the implementation shown in <FIG>, and operations and/or functions of the modules in the access network device <NUM> or the access network device <NUM> are respectively used to implement corresponding procedures in the implementation shown in <FIG>. For brevity, details are not described herein again.

An implementation of this application further provides a communication apparatus. The communication apparatus may be a terminal device, or may be an apparatus in the terminal device, for example, an integrated circuit or a chip. The communication apparatus may be configured to perform an action performed by the terminal device in the foregoing method implementation shown in <FIG>.

When the communication apparatus is a terminal device, <FIG> is a simplified schematic structural diagram of the terminal device. For ease of understanding and convenience of illustration, an example in which the terminal device is a mobile phone is used in <FIG>. As shown in <FIG>, the terminal device includes a processor, a memory, a radio frequency circuit, an antenna, and an input/output apparatus. The processor is mainly configured to: process a communication protocol and communication data, control the terminal device, execute a software program, process data of the software program, and the like. The memory is mainly configured to store the software program and the data. The radio frequency circuit is mainly configured to perform conversion between a baseband signal and a radio frequency signal, and process the radio frequency signal. The antenna is mainly configured to receive and send a radio frequency signal in an electromagnetic wave form. The input/output apparatus, for example, a touchscreen, a display screen, or a keyboard, is mainly configured to receive data entered by a user and output data to the user. It should be noted that some types of terminal devices may have no input/output apparatus.

When data needs to be sent, the processor performs baseband processing on the to-be-sent data, and then outputs a baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal, and then sends a radio frequency signal in an electromagnetic wave form through the antenna. When data is sent to the terminal device, the radio frequency circuit receives a radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data, and processes the data. For ease of description, <FIG> shows only one memory and one processor. In an actual terminal device product, there may be one or more processors and one or more memories. The memory may also be referred to as a storage medium, a storage device, or the like. The memory may be disposed independent of the processor, or may be integrated with the processor. This is not limited in this implementation of this application.

In this implementation of this application, the antenna having a sending and receiving function and the radio frequency circuit may be considered as a transceiver unit of the terminal device, and the processor having a processing function may be considered as a processing unit of the terminal device. As shown in <FIG>, the terminal device includes a transceiver unit <NUM> and a processing unit <NUM>. The transceiver unit may also be referred to as a transceiver, a transceiver machine, a transceiver apparatus, or the like. The processing unit may also be referred to as a processor, a processing board, a processing module, a processing apparatus, and the like. Optionally, a component that is in the transceiver unit <NUM> and that is configured to implement a reception function may be considered as a receiving unit, and a component that is in the transceiver unit <NUM> and that is configured to implement a sending function may be considered as a sending unit. In other words, the transceiver unit <NUM> includes the receiving unit and the sending unit. The transceiver unit sometimes may also be referred to as a transceiver machine, a transceiver, a transceiver circuit, or the like. The receiving unit sometimes may also be referred to as a receiver machine, a receiver, a receiving circuit, or the like. The sending unit sometimes may also be referred to as a transmitter machine, a transmitter, a transmitter circuit, or the like.

It should be understood that the transceiver unit <NUM> is configured to perform sending and receiving operations on a terminal device side in the method implementation shown in <FIG>, and the processing unit <NUM> is configured to perform an operation other than the sending and receiving operations on the terminal device side in the method implementation shown in <FIG>.

For example, in an implementation, the transceiver unit <NUM> is configured to perform the receiving and sending steps, for example, <NUM> and <NUM>, on the terminal device side in the implementation shown in <FIG>, and/or configured to support another process of the technology described in this specification. The processing unit <NUM> is configured to perform another operation, for example, <NUM>, other than the transceiver operation, on the terminal device side in the implementation shown in <FIG>, and/or configured to support another process of the technology described in this specification.

When the communication apparatus is a chip, the chip includes a transceiver unit and a processing unit. The transceiver unit may be an input/output circuit or a communication interface. The processing unit may be a processor, a microprocessor, or an integrated circuit, integrated on the chip.

When the communication apparatus in this implementation of this application is the terminal device, reference may be made to a device shown in <FIG>. In an example, the device may implement a function similar to that of the processor <NUM> in <FIG>. In <FIG>, the device includes a processor <NUM>, a data sending processor <NUM>, and a data receiving processor <NUM>. The processing module <NUM> in the foregoing implementation may be the processor <NUM> in <FIG>, and completes a corresponding function. The transceiver module <NUM> in the foregoing implementation may be the data sending processor <NUM> and/or the data receiving processor <NUM> in <FIG>.

Although <FIG> shows a channel encoder and a channel decoder, it may be understood that the modules do not constitute a limitation on this implementation, and are merely an example.

<FIG> shows another form of this implementation. A processing apparatus <NUM> includes modules such as a modulation subsystem, a central processing subsystem, and a peripheral subsystem. The communication apparatus in this implementation may be used as the modulation subsystem in the processing apparatus. Specifically, the modulation subsystem may include a processor <NUM> and an interface <NUM>. The processor <NUM> completes a function of the processing module <NUM>, and the interface <NUM> completes a function of the transceiver module <NUM>. In another variation, the modulation subsystem includes a memory <NUM>, a processor <NUM>, and a program that is stored in the memory <NUM> and that can be run on the processor. When executing the program, the processor <NUM> implements the method on the terminal device side in the foregoing method implementation shown in <FIG>. It should be noted that the memory <NUM> may be non-volatile or volatile. The memory <NUM> may be located inside the modulation subsystem, or may be located in the processing apparatus <NUM>, provided that the memory <NUM> can be connected to the processor <NUM>.

An implementation of this application further provides a communication apparatus. The communication apparatus may be an access network device, or may be an apparatus in the access network device, for example, an integrated circuit or a chip. The communication apparatus may be configured to perform an action performed by the access network device in the method implementation shown in <FIG>.

When the communication apparatus is an access network device, the apparatus <NUM> in <FIG> is a simplified schematic structural diagram of the access network device. <FIG> is a schematic diagram of a hardware structure of the apparatus <NUM> according to an implementation of this application. The apparatus <NUM> includes at least one processor <NUM>, and is configured to implement a function of the access network device provided in the implementations of this application. The apparatus <NUM> may further include a bus <NUM> and at least one communication interface <NUM>. The apparatus <NUM> may further include a memory <NUM>.

The bus <NUM> may be configured to transmit information between the foregoing components.

The communication interface <NUM> is configured to communicate with another device or a communication network, for example, an Ethernet, a RAN, or a WLAN. The communication interface <NUM> may be an interface, a circuit, a transceiver, or another apparatus that can implement communication. This is not limited in this application. The communication interface <NUM> may be coupled to the processor <NUM>. It should be noted that in this implementation of this application, when the access network device is used as a receive end device, the transceiver may be replaced with a receiver; when the access network device is used as a transmit end device, the transceiver may be replaced with a transmitter. Certainly, no matter whether the access network device is used as a receive end device or a transmit end device, the access network device has both a sending function and a receiving function, that is, the access network device includes the foregoing transceiver.

The memory <NUM> is configured to store program instructions, which may be controlled and executed by the processor <NUM>, to implement the communication method provided in the following implementations of this application. For example, the processor <NUM> is configured to invoke and execute the instructions stored in the memory <NUM>, to implement the communication method provided in the following implementations of this application.

Optionally, the memory <NUM> may be included in the processor <NUM>.

In a specific implementation, in an implementation, the processor <NUM> may include one or more CPUs, for example, a CPU <NUM> and a CPU <NUM> in <FIG>. The CPU herein is merely an example for description. In different implementations, the CPU may be replaced with a processor of any type or function.

In a specific implementation, in an implementation, the apparatus <NUM> may include a plurality of processors, for example, the processor <NUM> and a processor <NUM> in <FIG>. Each of the processors may be a single-core processor, or may be a multi-core processor. The processor herein may be one or more devices, circuits, and/or processing cores for processing data (for example, computer program instructions).

An implementation of this application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the program is executed by a processor, a procedure related to the terminal device in the implementation shown in <FIG> provided in the foregoing method implementations may be implemented.

An implementation of this application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the program is executed by a processor, a procedure related to the access network device in the implementation shown in <FIG> provided in the foregoing method implementations may be implemented.

An implementation of this application further provides a computer program product including instructions. When the instructions are executed, the method on a terminal device side in the method implementation shown in <FIG> is performed.

An implementation of this application further provides a computer program product including instructions. When the instructions are executed, the method on an access network device side in the method implementation shown in <FIG> is performed.

It should be understood that the processor mentioned in the implementations of this application may include but is not limited to at least one of the following: a central processing unit (central processing unit, CPU), a microprocessor, a digital signal processor (digital signal processor, DSP), a microcontroller unit (microcontroller unit, MCU), or various computing devices that run software, such as an artificial intelligence processor, where each computing device may include one or more cores configured to execute software instructions to perform an operation or perform processing. The processor may be an independent semiconductor chip, or may be integrated with another circuit to constitute a semiconductor chip. For example, the processor may constitute a system on chip (system on chip, SoC) with another circuit (for example, an encoding/decoding circuit, a hardware acceleration circuit, or various buses and interface circuits). Alternatively, the processor may be integrated into an application-specific integrated circuit (application specific integrated circuit, ASIC) as a built-in processor of the ASIC, and the ASIC integrated with the processor may be independently packaged or may be packaged with another circuit. The processor includes a core configured to perform an operation or processing by executing software instructions, and may further include a necessary hardware accelerator, for example, a field programmable gate array (field programmable gate array, FPGA), a programmable logic device (programmable logic device, PLD), or a logic circuit that implements a special-purpose logic operation.

It should be noted that when the processor is a general-purpose processor, a DSP, an ASIC, an FPGA or another programmable logic device, a discrete gate or a transistor logic device, or a discrete hardware component, the memory (storage module) is integrated into the processor.

It should be further understood that the memory mentioned in the implementations of this application may be a volatile memory or a nonvolatile memory, or may include both a volatile memory and a nonvolatile memory. The nonvolatile memory may be a read-only memory (read-only memory, ROM), a programmable read-only memory (programmable ROM, PROM), an erasable programmable read-only memory (erasable PROM, EPROM), an electrically erasable programmable read-only memory (electrically EPROM, EEPROM), or a flash memory. The volatile memory may be a random access memory (random access memory, RAM) that is used as an external cache. Through examples rather than limitative descriptions, RAMs in many forms may be used, for example, a static random access memory (static RAM, SRAM), a dynamic random access memory (dynamic RAM, DRAM), a synchronous dynamic random access memory (synchronous DRAM, SDRAM), a double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), an enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), a synchlink dynamic random access memory (synchlink DRAM, SLDRAM), and a direct rambus random access memory (direct rambus RAM, DR RAM).

It should be noted that the memory described in this specification is intended to include but is not limited to these and any memory of another proper type.

It should be understood that sequence numbers of the foregoing processes do not mean execution sequences in the implementations of this application. The execution sequences of the processes should be determined according to functions and internal logic of the processes, and should not be construed as any limitation on the implementation processes of the implementations of this application.

A person of ordinary skill in the art may be aware that units and algorithm steps in the examples described with reference to the implementations disclosed in this specification can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on particular applications and design constraint conditions of the technical solutions.

A person skilled in the art may clearly understand that for the purpose of convenient and brief description, for detailed working processes of the foregoing system, apparatus, and unit, refer to corresponding processes in the foregoing method implementations, and details are not described herein again.

In the several implementations provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described apparatus implementations are merely an example. For example, division into the units is merely logical function division and may be other division during actual implementation. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electrical, mechanical, or other forms.

Some or all of the units may be selected based on an actual requirement to achieve the objectives of the solutions of the implementations.

In addition, function units in the implementations of this application may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

When the functions are implemented in a form of a software function unit and sold or used as an independent product, the functions may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of this application essentially, or the part contributing to the prior art, or some of the technical solutions may be implemented in a form of a software product. The computer software product is stored in a storage medium, and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some of the steps of the method described in the implementations of this application. The storage medium includes any medium such as a USB flash drive, a removable hard disk, a read-only memory (read-only memory, ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disc, that can store program code.

Claim 1:
A communication method, wherein the method is performed by a terminal device, and the method comprises:
receiving (<NUM>) a first downlink channel in a first area, wherein the first downlink channel is used to carry first data in a broadcast manner, wherein the first area comprises one or more cells located in a broadcast area of an access network device; and
receiving (<NUM>) a second downlink channel in a second area, wherein the second downlink channel is used to retransmit the first data in a broadcast manner, wherein the second area comprises one or more cells located in the broadcast area of the access network device;
wherein the second area is smaller than the first area;
wherein the first downlink channel is scrambled by using a first identifier, the second downlink channel is scrambled by using a second identifier, and the first identifier and the second identifier are identifiers configured by the access network device;
wherein before the receiving a second downlink channel, the method further comprises:
determining (<NUM>) a channel resource used to feed back acknowledgment information, wherein the channel resource is indicated by using indication information, and sending a negative acknowledgment to the access network device on the channel resource;
wherein the channel resource is a feedback channel resource corresponding to the second area, the channel resource belongs to a first resource set, and the first resource set is a set of feedback channel resources corresponding to the first area;
wherein the first downlink channel and the second downlink channel meet the following: waveform parameters of the first downlink channel and the second downlink channel are different, wherein a larger cyclic prefix, CP, is configured for the first downlink channel, and a smaller CP is configured for the second downlink channel.