CN113573247B

CN113573247B - Multicast transmission method, device and system

Info

Publication number: CN113573247B
Application number: CN202010351576.8A
Authority: CN
Inventors: 刘云; 徐海博; 王洲; 周永行
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-04-28
Filing date: 2020-04-28
Publication date: 2023-04-18
Anticipated expiration: 2040-04-28
Also published as: CN113573247A; WO2021219041A1

Abstract

The application provides a multicast transmission method, a device and a system, which can be applied to multicast transmission in V2X, wherein the method comprises the following steps: the first terminal equipment receives M pieces of indication information from N pieces of second terminal equipment; one or more of the M indication information are used to indicate a resource; the first terminal device may determine resources for multicast transmission according to the M pieces of indication information. In the method, the first terminal device determines the resource for transmitting the multicast message through the M pieces of indication information, so that extra signaling and resource configuration overhead are not introduced, and the resource utilization rate is improved. Furthermore, the resource for multicast transmission is indicated by the second terminal device, the probability of multicast message retransmission can be reduced, and the method and the device can be applied to the fields of Internet of vehicles, artificial intelligence and the like.

Description

Multicast transmission method, device and system

Technical Field

The present application relates to the field of communications technologies, and in particular, to a method, an apparatus, and a system for multicast transmission.

Background

As communication technologies have evolved and the interconnection of Everything has been accelerating, the third generation partnership project (3 GPP) introduced Vehicle-to-Vehicle (V2V) and Vehicle-to-Everything (V2X) services in Long Term Evolution (LTE) systems and New Radio (NR) systems to extend the 3GPP platform to the automotive industry.

V2X may support multicast transmission, where the transmission of messages is limited to only end devices belonging to a group. One end device (hereinafter referred to as a multicast originating end device) can transmit a message to a plurality of end devices (hereinafter referred to as multicast receiving end devices) belonging to the same group.

In the current multicast technology, resources for transmitting multicast messages are allocated by a base station, and if the base station does not allocate resources or the allocated resources are not appropriate, the transmission of the multicast messages cannot be performed.

Disclosure of Invention

Embodiments of the present application provide a multicast transmission method, apparatus, and system, so as to solve a problem of how to allocate resources required for multicast transmission.

In a first aspect, the present application provides a multicast transmission method, including: the first terminal equipment receives M pieces of indication information from N pieces of second terminal equipment; one or more pieces of indication information in the M pieces of indication information are used for indicating resources, N is an integer greater than 0, and M is an integer greater than or equal to N; and the first terminal equipment determines resources for multicast transmission according to the M pieces of indication information.

In the method, the first terminal device determines the resource for transmitting the multicast message through the M pieces of indication information, so that extra signaling and resource configuration overhead are not introduced, and the resource utilization rate is improved. Further, the resource for multicast transmission is indicated by the second terminal device, which may reduce the probability of multicast message retransmission.

In one possible design, the resource in which the one or more indication information is located is used to indicate the resource for multicast transmission.

In the method, the indication information in the prior art can be reused through indirectly indicating the resources, and the utilization rate of the resources is improved.

In one possible design, before the first terminal device receives M pieces of indication information from N second terminal devices, the method further includes: the first terminal equipment sends a first multicast message to a group of terminal equipment comprising the N second terminal equipment; one or more of the M pieces of indication information are used to indicate that the second terminal device sending the corresponding indication information fails to receive the first multicast message.

In the method, the M pieces of indication information are feedback information of the transmission result of the multiplexing first multicast message, so that the resource configuration overhead can be further reduced, and the resource utilization rate can be improved.

In a possible design, a second resource in which a first indication information of the one or more indication information is located is used to indicate a first resource, where the first resource corresponds to the second resource, and the first resource is a candidate resource for multicast transmission by the first terminal device.

In one possible design, the first resource corresponds to a second resource, including: the first identity of the first resource and the second identity of the second resource satisfy a first constraint relationship.

In one possible design, the first constraint is: the second identification is determined by a modulus operation according to the first variable and the second variable; wherein the first variable is determined according to the first identifier, and the second variable is determined according to the number Z of candidate resources for carrying the M pieces of indication information and the number Y of code domain sequences supported by the candidate resources.

In one possible design, the first variable H satisfies any one of the following equations:

H＝L_ID+R ₁ or H = L _ ID-R ₁ Or H = R ₁ Or H = L _ ID + R ₁ -R ₃ Or H = L _ ID + R ₃ -R ₁ ；

The second variable K satisfies any one of the following formulas:

k = Z Y, or K = Z Y-1;

wherein R is ₁ Is said first label, R ₃ And sending the identifier of the resource of the first multicast message to the first terminal equipment, wherein the L _ ID is the identifier of the first terminal equipment.

In one possible design, H is less than or equal to K, or H is less than or equal to K-1, H = H1-H2+1, H1 is the maximum value of the value range of H, and H2 is the minimum value of the value range of H.

By the method, the situation that the first resource cannot be accurately determined due to the fact that the first resource and the second resource cannot be in one-to-one correspondence due to the fact that a plurality of second identifications are determined according to the first variable can be avoided.

In one possible design, before the first terminal device receives M pieces of indication information from N second terminal devices, the method further includes: the first terminal equipment sends a second multicast message to a group of terminal equipment comprising the N second terminal equipment; the second multicast message is used for triggering the second terminal equipment receiving the second multicast message to indicate resources to the first terminal equipment.

In one possible design, the second multicast message includes channel indication information; the channel indication information is used for indicating a physical direct link feedback channel (PSFCH) or a preset feedback channel, and the PSFCH or the preset feedback channel is used for transmitting the indication information.

Through the method, the N second terminal devices send the indication information in the same channel, so that the feedback efficiency can be improved, the signaling storm is avoided, and the purposes of reducing the multicast delay and reducing the power consumption are achieved.

In one possible design, the predetermined feedback channel includes 1 AGC symbol and at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol.

In one possible design, when the channel indication information is used to indicate the preset feedback channel, at least one indication information from one or more of the N second terminal devices is carried through at least one OFDM symbol in the preset feedback channel.

In a possible design, a first indication information of the one or more indication information is used to indicate a first resource, where the first indication information is a code domain sequence corresponding to the first resource, and the first resource is a candidate resource for multicast transmission by the first terminal device.

In a possible design, when the first indication information is a code domain sequence corresponding to the first resource, the third identifier of the first indication information and the first identifier of the first resource satisfy a second constraint relationship.

In one possible design, the second constraint is: the third identification is determined by a modulus operation according to a third variable and a fourth variable; wherein the third variable is determined according to the first identifier, and the fourth variable is determined according to the number Z of candidate resources for carrying the M indication information and the number Y of code domain sequences supported by the candidate resources.

In one possible design, the third variable T satisfies any one of the following equations:

T＝R ₁ or T = R ₅ -R ₁ Or T = R ₅ +R ₁ Or T = R ₁ -R ₅ ；

The fourth variable X satisfies any one of the following equations:

X＝Z*Y；

wherein R is ₁ Is said first label, R ₅ And sending the identifier of the resource of the second multicast message to the first terminal equipment.

In one possible design, T is less than or equal to X, T = T1-T2+1, T1 being the maximum value of the value range of T, and T2 being the minimum value of the value range of T.

In one possible design, at least one resource indicated by the M pieces of indication information is a resource with less interference or better channel quality.

In one possible design, the determining, by the first terminal device, resources for multicast transmission according to the M pieces of indication information includes: the first terminal equipment determines the detection power of each piece of indication information used for indicating resources in the M pieces of indication information; the first terminal device takes the resource indicated by the indication information with the maximum detection power as the resource for multicast transmission; or the first terminal device takes the resource indicated by any indication information with the detection power larger than the preset threshold value as the resource for multicast transmission.

In a second aspect, the present application further provides a communication device having a function of implementing any one of the methods provided by the first aspect. The communication device may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more units or units corresponding to the above functions.

In one possible implementation, the communication device includes: a processor configured to enable the communication apparatus to perform the respective functions of the first terminal device in the above-indicated method. The communication device may also include a memory, which may be coupled to the processor, that retains program instructions and data necessary for the communication device. Optionally, the communication apparatus further includes a communication interface, and the communication interface is configured to support communication between the communication apparatus and a second terminal device or the like.

In one possible implementation, the communication device includes corresponding functional units, which are respectively used for implementing the steps in the above method. The functions may be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more units corresponding to the above functions.

In a possible implementation manner, the structure of the communication device includes a processing unit and a communication unit, and these units may perform corresponding functions in the above method example, specifically refer to the description in the method provided in the first aspect, and are not described herein again.

In a third aspect, the present application provides a method comprising: the second terminal equipment determines the indication information; the indication information is used for indicating the resource determined by the second terminal equipment by the first terminal equipment; and the second terminal equipment sends the indication information to the first terminal equipment.

In one possible design, before the second terminal device determines the indication information, the method further includes:

the second terminal equipment fails to receive the first multicast message sent by the first terminal equipment; the indication information is further used for indicating that the second terminal device fails to receive the first multicast message.

In one possible design, the sending, by the second terminal device, the indication information to the first terminal device includes: the second terminal equipment determines a first resource; the second terminal device sends the indication information to the first terminal device through a second resource, wherein the first resource is a candidate resource for multicast transmission of the first terminal device; the first resource corresponds to the second resource.

In one possible design, the first resource corresponds to the second resource, including: the first identity of the first resource and the second identity of the second resource satisfy a first constraint relationship.

In one possible design, the first constraint is: the second identification is determined by a modulus operation according to the first variable and the second variable; wherein the first variable is determined according to the first identifier, and the second variable is determined according to the number Z of candidate resources for carrying the indication information and the number Y of code domain sequences supported by the candidate resources.

H＝L_ID+R ₁ or H = L _ ID-R ₁ Or H = R ₁ Or H = L _ ID + R ₁ -R ₃ ；

The second variable K satisfies any one of the following formulas:

k = Z x Y, or, K = Z x Y-1;

In one possible design, before the second terminal device determines the indication information, the method further includes: the second terminal equipment receives a second multicast message from the first terminal equipment; the second multicast message is used for triggering the second terminal equipment to indicate resources to the first terminal equipment.

In one possible design, the second multicast message includes channel indication information;

the channel indication information is used for indicating a physical direct link feedback channel (PSFCH) or a preset feedback channel, and the PSFCH or the preset feedback channel is used for transmitting the indication information.

In one possible design, the determining, by the second terminal device, the indication information includes: the second terminal equipment determines a first resource; the first resource is a candidate resource for multicast transmission of the first terminal device; and the second terminal equipment determines a code domain sequence corresponding to the first resource as the indication information.

In one possible design, the third identifier of the code domain sequence corresponding to the first resource and the first identifier of the first resource satisfy a second constraint relationship.

In one possible design, the second constraint relationship is: the third identification is determined by a modulus operation according to a third variable and a fourth variable; wherein the third variable is determined according to the first identifier, and the fourth variable is determined according to the number Z of candidate resources for carrying the indication information and the number Y of code domain sequences supported by the candidate resources.

In one possible design, the third variable T satisfies any one of the following formulas:

T＝R ₁ or T = R ₅ -R ₁ Or T = R ₅ +R ₁ Or T = R ₁ -R ₅ ；

The fourth variable X satisfies any one of the following equations:

X＝Z*Y；

wherein R is ₁ Is said first mark, R ₅ And sending the identifier of the resource of the second multicast message to the first terminal equipment.

In a fourth aspect, the present application further provides a communication device having a function of implementing any one of the methods provided in the third aspect. The communication device may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more units or units corresponding to the above functions.

In one possible implementation, the communication device includes: a processor configured to enable the communication apparatus to perform the respective functions of the second terminal device in the above-illustrated method. The communication device may also include a memory, which may be coupled to the processor, that retains program instructions and data necessary for the communication device. Optionally, the communication apparatus further includes a communication interface, and the communication interface is configured to support communication between the communication apparatus and a first terminal device or the like.

In one possible implementation, the communication device comprises corresponding functional units, each for implementing the steps in the above method. The functions may be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more units corresponding to the above functions.

In a possible implementation manner, the structure of the communication device includes a processing unit and a communication unit, and these units may perform corresponding functions in the above method example, specifically refer to the description in the method provided in the third aspect, and are not described herein again.

In a fifth aspect, the present application further provides a system comprising: a first terminal device, configured to send a first multicast message to a group of terminal devices including at least N second terminal devices; n is an integer greater than 0;

the second terminal device is used for sending indication information to the first terminal device when determining that the first multicast message is failed to be received; the indication information is used for indicating that the second terminal equipment fails to receive the first multicast message and indicating the resource determined by the second terminal equipment;

the first terminal device is used for receiving M pieces of indication information from N pieces of second terminal devices; one or more pieces of indication information in the M pieces of indication information are used for indicating resources, wherein M is an integer greater than or equal to N; and determining resources for multicast transmission according to the M pieces of indication information.

In a sixth aspect, the present application further provides a system comprising: a first terminal device for sending a second multicast message to a group of terminal devices including at least N second terminal devices; the second multicast message is used for triggering a second terminal device receiving the second multicast message to indicate resources to the first terminal device, and N is an integer greater than 0;

the second terminal device is used for sending indication information to the first terminal device when the second multicast message is determined to be received; the indication information is used for indicating the resource determined by the second terminal equipment;

In a seventh aspect, the present application provides a chip comprising a processor, coupled with a memory, for executing a computer program or instructions stored in the memory, and when the processor executes the computer program or instructions, the method of the first aspect or the third aspect is implemented.

In an eighth aspect, the present application provides a communication device comprising a processor, which when executing a computer program or instructions in a memory, performs a method as described in the first or third aspect.

In a ninth aspect, the present application provides a communications apparatus comprising a processor and a memory for storing computer programs or instructions; the processor is configured to execute the computer program or instructions stored by the memory to cause the communication device to perform the respective method as shown in the first or third aspect.

In a tenth aspect, the present application provides a communication device comprising a processor, a memory, and a transceiver for receiving signals or transmitting signals; the memory for storing computer programs or instructions; the processor being configured to invoke the computer program or instructions from the memory to perform the method according to the first or third aspect.

In an eleventh aspect, the present application provides a communication device comprising a processor and a communication interface for receiving code instructions and transmitting the code instructions to the processor; the processor executes the code instructions to perform a corresponding method as shown in the first or third aspect.

In a twelfth aspect, the present application provides a computer readable storage medium for storing a computer program or instructions which, when read and executed by a computer, cause the method of the first or third aspect to be implemented.

In a thirteenth aspect, the present application provides a computer program product comprising instructions which, when read and executed by a computer, cause the method of the first or third aspect to be carried out.

Drawings

Fig. 1 is a schematic view of an application scenario provided in an embodiment of the present application;

fig. 2 is a flowchart illustrating a multicast transmission method according to an embodiment of the present application;

fig. 3 is a schematic diagram illustrating multicast message transmission according to an embodiment of the present application;

fig. 4 is a schematic diagram illustrating an indication information transmission according to an embodiment of the present application;

fig. 5 is a schematic diagram of multicast message retransmission provided in an embodiment of the present application;

fig. 6 is a schematic resource diagram provided in an embodiment of the present application;

FIG. 7 is a resource diagram according to an embodiment of the present application;

FIG. 8 is a resource diagram according to an embodiment of the present application;

FIG. 9 is a resource diagram according to an embodiment of the present application;

fig. 10 is a flowchart illustrating a multicast transmission method according to an embodiment of the present application;

fig. 11 is a schematic diagram of multicast message transmission according to an embodiment of the present application;

fig. 12 is a schematic diagram of a channel structure according to an embodiment of the present application;

fig. 13 is a schematic diagram illustrating an indication information transmission according to an embodiment of the present application;

fig. 14 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 15 is a schematic structural diagram of a communication device according to an embodiment of the present application.

Detailed Description

The embodiments of the present application will be described in detail below with reference to the drawings attached hereto.

The embodiment of the application can be applied to a direct link (sidelink) multicast transmission technology supported in V2X. In the sidelink multicast transmission technology, a plurality of terminal devices may be configured into one multicast group according to actual situations. The number of end devices in the multicast group may be dynamically changing, and an end device may join or leave the multicast group at any time.

In this embodiment, the terminal device in the multicast group may be a device supporting NR V2X or LTE V2X, and may include, but is not limited to, a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device having a Wireless communication function, a computing device, or another processing device connected to a Wireless modem, a vehicle-mounted device, a wearable device, and the like.

For example, as shown in fig. 1, the terminal devices 1 to 4 are all vehicle-mounted devices, and the terminal devices 1 to 4 all travel in the same direction on a road. In fig. 1, the end devices 1 to 4 may communicate with each other in a multicast manner, specifically, the end devices 1 to 4 may form a multicast group, where one end device in the multicast group may send a multicast message to all other end devices in the multicast group, and transmission of the multicast message is limited to only one multicast group. When multicast transmission is adopted, the terminal equipment sending data can only send one piece of data, so that all the terminal equipment in a multicast group can receive the same data, only the terminal equipment in the multicast group can receive the data, and the terminal equipment outside the multicast group cannot receive the data. By adopting multicast transmission, high-efficiency data transmission can be realized, network bandwidth can be greatly saved, and network load can be reduced.

It should be noted that fig. 1 is only an example, and other scenarios may exist, for example, a group of wearable devices, a group of smartphones, and the like, which are not illustrated herein one by one.

Further, in order to improve reliability of multicast transmission, the terminal device receiving the multicast message feeds back a reception result according to a demodulation condition, where the reception result includes a Negative Acknowledgement (NACK) or an Acknowledgement (ACK). NACK indicates that the multicast receiving terminal equipment fails to receive, and ACK indicates that the multicast receiving terminal equipment succeeds in receiving. When one terminal device feeds back NACK, the multicast initiating terminal device needs to retransmit. Considering the specificity of achieving multicast feedback, two multicast feedback modes, namely a feedback mode 1 and a feedback mode 2, are established at present.

For convenience of description, in the embodiment of the present application, a terminal device that sends a multicast message is referred to as a multicast initiating terminal device, and a terminal device that receives the multicast message is referred to as a multicast receiving terminal device.

In the feedback method 1, the multicast receiving terminal device feeds back NACK when reception fails, and does not feed back ACK when reception succeeds, and all multicast receiving terminal devices feed back NACK using the same feedback resource. And the multicast initiating terminal equipment judges whether the multicast receiving terminal equipment feeds back NACK according to the energy on the detection feedback channel so as to determine whether to retransmit.

It should be noted that, in the feedback method 1, the code domain sequences generated through cyclic shift are sent by the multicast receiving terminal device in the feedback channel, and the code domain sequences of different cyclic shifts are mutually orthogonal, so that the multicast initiating terminal device can distinguish different multicast receiving terminal devices according to the orthogonality of the code domain sequences. When the multicast initiating terminal device receives a code domain sequence, it can determine that the multicast receiving terminal device that sent the code domain sequence fails to receive.

In addition, the Feedback Channel may also be referred to as a Physical Sidelink Feedback Channel (PSFCH). In the prior art, the multicast receiving terminal device may determine the resource identifier corresponding to the feedback channel according to formula (1), specifically, formula (1) satisfies the following relationship:

R _PSFCH ＝Tx_ID mod(Z*Y)···(1)

wherein R is _PSFCH The resource identifier corresponding to the feedback channel is represented, tx _ ID represents the identifier of the multicast initiating terminal device, Z represents the number of Physical Resource Blocks (PRBs) included in the PSFCH, Y represents the number of code domain sequences supported by each PRB, and mod represents the remainder operation.

In the feedback mode 2, each multicast receiving terminal device has a separate feedback channel, where the feedback channel of each multicast receiving terminal device includes two feedback resources, 1 feedback resource is used for transmitting ACK, and the other feedback resource is used for transmitting NACK.

It should be noted that, in the feedback mode 2, the feedback resource corresponding to each multicast receiving terminal device may be configured by the base station, or may be determined according to other modes, and the embodiment of the present application is not limited.

Currently, in the multicast transmission technology, any terminal device may receive a failure due to interference, thereby triggering retransmission. Under the condition that the number of terminal devices in the multicast group is large, the probability of retransmission is increased, and the retransmission times are correspondingly increased. To this end, embodiments of the present application provide a method that can reduce the probability of retransmission, which will be described in detail below.

The network architecture and the service scenario described in the embodiment of the present application are for more clearly illustrating the technical solution of the embodiment of the present application, and do not form a limitation on the technical solution provided in the embodiment of the present application, and as a person of ordinary skill in the art knows that along with the evolution of the network architecture and the appearance of a new service scenario, the technical solution provided in the embodiment of the present application is also applicable to similar technical problems.

The method provided in the embodiments of the present application may be applied to initial transmission of a multicast message, and may also be applied to retransmission of a multicast message, which are described below separately.

In the embodiment of the present application, for convenience of description, a terminal device that sends a multicast message is referred to as a first terminal device, and a terminal device that receives the multicast message is referred to as a second terminal device.

The first embodiment is as follows:

in the first embodiment, after the initial transmission of the multicast message is performed, when there is a second terminal device that fails to receive the multicast message, the second terminal device that fails to receive may feed back NACK to the first terminal device according to the feedback method 1. The second terminal device that failed in reception may indirectly indicate the resource to the first terminal device through NACK. In the first embodiment, NACK is indication information, and the specific content of the indication information will be described in detail later.

In the first embodiment, the second terminal device may indicate the resource to the first terminal device through the resource indicated by the indication information, and the first terminal device may thereby select a resource for retransmitting the multicast message from the resources indicated by the one or more second terminal devices. The first embodiment is mainly different from the prior art in that, when the second terminal device sends the indication information, the resource for transmitting the indication information is determined by using formula (1) in the prior art, but the resource formula (1) for transmitting the indication information is determined by using other methods, which may be specifically referred to as fig. 2.

Further optionally, in this embodiment of the application, before performing step 201, the first terminal device may further indicate that the current multicast transmission supports multicast transmission of the resource fed back by the indication information, that is, indicate that the other terminal devices feed back the resource by the indication information when receiving the multicast message fails. For example, the first terminal device may use at least 1 bit in first-stage direct connection Control information carried in a Physical direct connection link Control Channel (PSCCH) to indicate that other terminal devices feed back resources through the indication information when receiving the multicast message fails. The first-stage direct connection Control Information may be direct connection link Control Information (SCI) and other Information.

As shown in fig. 2, a flowchart of a multicast transmission method provided in the embodiment of the present application is shown.

Optionally, step 201: the first terminal device sends a first multicast message.

For example, as shown in fig. 3, the first end device may send the first multicast message to all end devices in the multicast group in which the first end device is located. In addition to the first end device, the multicast group may include at least N second end devices, where N is an integer greater than 0.

The content of the first multicast message sent by the first terminal device is not limited in this embodiment, and may be, for example, data or a control instruction that needs to be sent by the first terminal device.

Step 202: and the second terminal equipment sends the indication information to the first terminal equipment.

In step 202, a second terminal device is taken as an example for illustration, and actually, N second terminal devices may send indication information to the first terminal device. For example, reference may be made to FIG. 4 in conjunction with FIG. 3. Assuming that after the first terminal device sends the first multicast message to the plurality of second terminal devices in fig. 3, the indication information may be sent to the first terminal device when the second terminal device fails to receive the first multicast message in fig. 4.

The instruction information may also be referred to as auxiliary information or the like, and the name of the instruction information is not limited in the embodiments of the present application.

Optionally, in step 202, the second terminal device may send the indication information when the first multicast message fails to be received, where the indication information may also be used to indicate that the second terminal device fails to receive the first multicast message, that is, the indication information is NACK.

Further, the second terminal device may send the indication information to the first terminal device according to feedback manner 1, that is, the resource for transmitting the indication information is the resource in the PSFCH,

in the first embodiment, the second terminal device may determine, according to an actual situation, the first resource that needs to be indicated to the first terminal device, and how the second terminal device specifically determines the first resource, which is not limited in this embodiment of the present application. For example, the second terminal device may use the resource with better channel quality or less interference as the first resource.

In a first embodiment, the indication information may indirectly indicate the first resource, and specifically, the resource where the indication information is located may be used to indicate the first resource. The first resource is a resource indicated by the second terminal device to the first terminal device, and the first resource may be a candidate resource for multicast transmission by the first terminal device.

Specifically, the second resource used for transmitting the indication information may correspond to the first resource. After the second terminal device determines the first resource, a resource corresponding to the first resource may be determined as a second resource for transmitting the indication information.

The first resource corresponds to the second resource, which may mean that a first identifier of the first resource and a second identifier of the second resource satisfy a first constraint relationship. The first identifier may be a resource number of the first resource, and correspondingly, the second identifier may be a resource number of the second resource.

Further, in this embodiment of the application, the first constraint relationship may satisfy the following formula:

R ₂ ＝H mod K···(2)

wherein R is ₂ A second identity representing a second resource, H representing a first variable, which may be determined from the first identity of the first resource; k denotes a second variable, which may be determined according to the number Z of candidate resources for carrying indication information and the number Y of code domain sequences supported by the candidate resources, as illustrated in the following.

Mode for carrying out 1,R ₂ ＝(L_ID+R ₁ )mod(Z*Y)···(3)

Wherein H = L _ ID + R ₁ K = Z x Y, and the values of Z and Y are determined according to actual conditions, for example, the value of Y may be 2 or 3 or 4 or 6 or 12, and the like. The L _ ID is an identifier of the first terminal device, and may be, for example, a layer 1 identifier of the first terminal device, or may be another identifier of the first terminal device.

Mode for implementation 2,R ₂ ＝(L_ID-R ₁ )mod(Z*Y)···(4)

Wherein H = L _ ID-R ₁ ，K＝Z*Y。

Implementation mode 3,R ₂ ＝R ₁ mod(Z*Y)···(5)

Wherein H = R ₁ ，K＝Z*Y。

Implementation mode 4,R ₂ ＝(L_ID+R ₁ -R ₃ )mod(Z*Y)···(6)

Wherein H = L _ ID + R ₁ -R ₃ ，K＝Z*Y，R ₃ And sending the identifier of the resource of the first multicast message to the first terminal equipment.

In the above equation (6), the second resource is determined according to a difference between the first identifier of the first resource for the second terminal device to transmit the indication information and the identifier of the resource for the first terminal device to transmit the first multicast message, where the difference may be a positive value or a negative value, and if the difference is a negative value, the difference may be the following equation (7).

Because the first terminal device can determine the identifier of the first terminal device, the first identifier of the first resource for transmitting the indication information, and the values of the parameters such as Z, Y, etc., after the first terminal device receives the indication information, the second terminal device can determine the second identifier of the second resource according to the above constraint relationship, and then determine the second resource.

For example, assume that there are 6 resources, whose identities are 1 to 6, respectively. Suppose that in formula (6), Z =1,y =6,r ₁ -R ₃ And =1, when the layer 1 identifier of the first terminal device corresponds to the third cyclic shift3, determining the resource identified as 2. When the layer 1 identifier of the first terminal device corresponds to other cyclic shifts, for example, shift1, shift2, shift4, shift5, and shift6, identifiers of other resources may be determined, for example, the identifier of the resource determined when the layer 1 identifier of the first terminal device corresponds to shift4 is 1 greater than the identifier of the resource determined when the layer 1 identifier of the first terminal device corresponds to shift3,i.e., the resource identified as 3; the identifier of the resource determined when the layer 1 identifier of the first terminal device corresponds to shift2 is 1 less than the identifier of the resource determined when the layer 1 identifier of the first terminal device corresponds to shift3, that is, the identifier is the resource of 1.

Implementation mode 5,R ₂ ＝(L_ID+R ₃ -R ₁ )mod(Z*Y)···(7)

Wherein H = L _ ID + R ₃ -R ₁ ，K＝Z*Y。

Mode for implementation 6,R ₂ ＝R ₁ mod(Z*Y)···(8)

Wherein H = R ₁ K = Z × Y. In this implementation, the second identity is determined only by the first identity of the first resource.

Implementation mode 7,R ₂ ＝(R ₃ -R ₁ )mod(Z*Y)···(9)

Wherein H = R ₃ -R ₁ K = Z × Y. In this implementation, the second identifier is determined by a difference between the identifier of the resource that sent the first multicast message and the first identifier of the first resource.

For example, suppose that in formula (9), Z =4,y =2,r ₃ -R ₁ And =1, the determined second identifier is 7.

Mode for implementation 8,R ₂ ＝(R ₁ -R ₃ )mod(Z*Y)···(10)

Wherein H = R ₁ -R ₃ K = Z × Y. For example, suppose that in equation (10), Z =4,y =2,r ₁ -R ₃ =1, then the determined second identifier is 1.

Implementation mode 9,R ₂ ＝(L_ID+R ₁ )mod(Z*Y-1)···(11)

Wherein H = L _ ID + R ₁ ，K＝Z*Y-1。

Mode for carrying out 10,R ₂ ＝(L_ID-R ₁ )mod(Z*Y-1)···(12)

Wherein H = L _ ID-R ₁ ，K＝Z*Y。

Implementation mode 11,R ₂ ＝R ₁ mod(Z*Y-1)···(13)

Wherein H = R ₁ ，K＝Z*Y。

Mode for carrying out 12,R ₂ ＝(L_ID+R ₁ -R ₃ )mod(Z*Y-1)···(14)

Wherein H = L _ ID + R ₁ -R ₃ ，K＝Z*Y-1。

Mode for carrying out 13,R ₂ ＝(L_ID+R ₃ -R ₁ )mod(Z*Y-1)···(15)

Wherein H = L _ ID + R ₃ -R ₁ ，K＝Z*Y。

Implementation 14,R ₂ ＝R ₁ mod(Z*Y-1)···(16)

Implementation mode 15,R ₂ ＝(R ₃ -R ₁ )mod(Z*Y-1)···(17)

Implementation mode 16,R ₂ ＝(R ₁ -R ₃ )mod(Z*Y-1)···(18)

Wherein H = R ₁ -R ₃ ，K＝Z*Y。

The above are examples only, and other implementations are possible and are not illustrated herein in any order.

Further, in this embodiment, the value number included in the value range of the first variable is less than or equal to that of the second variable. Specifically, assuming that the value range of H is [ H2, H1], where H1 is the maximum value of the value range of H and H2 is the minimum value of the value range of H, then in implementation 1 to implementation 4, H is less than or equal to K, and H = H1-H2+1; in implementations 5-8, h is less than or equal to K-1. In this case, the first resource may uniquely determine one second resource, so as to avoid that the first terminal device cannot receive the indication information transmitted through the second resource due to the fact that the first resource corresponds to multiple second resources.

It should be noted that the first identifier of the first resource may be a resource sub-channel index (sub-channel index), and/or an offset identifier in a time domain, and is used to determine a frequency domain position and/or a time domain position of one resource through the first identifier. Specifically, the first resource may be a frequency domain resource, and at this time, the first identifier of the first resource may be a resource sub-channel index (sub-channel index) and the like, which indicates a position of the first resource on the frequency domain; when the first resource is a time-frequency resource, the first identifier of the first resource may be a resource sub-channel identifier of the first resource and an identifier of an offset identifier in a time domain, for example, a Physical Resource Block (PRB) number, and the like, and the first identifier of the first resource may indicate a position of the first resource in a frequency domain and a time domain; when the first resource is a time domain resource, the first identifier of the first resource may be an identifier of an offset identifier in the time domain, for example, an Orthogonal Frequency Division Multiplexing (OFDM) symbol number or a slot number, and the first identifier of the first resource may indicate a position of the first resource in the time domain.

The second terminal device determines the recommended resource (i.e. the second resource) by using the first identifier of the first resource, and then transmits the indication information through the first resource. Correspondingly, after receiving the indication information, the first terminal device determines a first identifier of the first resource according to at least one of the frequency domain position and the time domain position of the first resource for transmitting the indication information and the cyclic shift parameter corresponding to the indication information, and then determines a resource position of the second resource indicated by the second terminal device according to the first identifier.

Optionally, when the first resource is a time-frequency resource, and the first identifier of the first resource is a resource sub-channel identifier of the first resource and an identifier of an offset identifier in a time domain, in a possible implementation manner, the resource number of the first resource may be numbered in a frequency domain-first manner; in another possible implementation manner, the resource numbers of the first resources are numbered according to a time domain priority manner.

For example, assuming that there are currently 6 resources, when numbering is performed in a frequency domain first manner, different time-frequency resources may be numbered in order according to frequency domain, for example, as shown in fig. 5. In fig. 5, in

time domain position

1, 3 time-frequency resources at different frequency domain positions are numbered as 1, 2, and 3 in sequence from large to small in the frequency domain; in the time domain position 2, the 3 time frequency resources at different frequency domain positions are numbered as 4, 5 and 6 in sequence from large to small in the frequency domain.

Alternatively, the different time-frequency resources may be numbered sequentially in the frequency domain, for example, as shown in fig. 6. In fig. 6, in

time domain position

2, 3 time frequency resources at different frequency domain positions are numbered as 4, 5, and 6 in sequence from large to small in the frequency domain; in the

time domain position

1, 3 time frequency resources at different frequency domain positions are numbered as 1, 2 and 3 in sequence from large to small in the frequency domain.

As another example, assuming that there are currently 6 resources, when numbering is performed in a time domain first manner, different time-frequency resources may be numbered in a time domain from front to back, for example, as shown in fig. 7. In fig. 7, in

frequency domain position

1, 2 time-frequency resources at different time domain positions are numbered as 1 and 2 in sequence from front to back in the frequency domain; in the frequency domain position 2, the 2 time frequency resources at different time domain positions are numbered as 3 and 4 in sequence from front to back on the frequency domain; in the

frequency domain position

3, 2 time frequency resources at different time domain positions are numbered as 5 and 6 in sequence from front to back in the frequency domain.

Alternatively, the different time frequency resources may also be numbered in the order from the back to the front in the time domain, for example, as shown in fig. 8. In fig. 8, in

frequency domain position

3, 2 time-frequency resources at different time domain positions are numbered as 1 and 2 in sequence from the back to the front in the frequency domain, and so on for other cases, which is not described again.

Further, a second terminal device may also indicate a plurality of second resources simultaneously, each second resource being carried by a different channel, for example, each second resource being carried by a different PFSCH channel, in this case, the second terminal device may transmit a plurality of channels in one OFDM symbol, the transmission power of the signal is divided equally or power-divided over the plurality of channels, the identifier of each channel in the plurality of channels implicitly indicates one second resource, and the second terminal device may thereby indicate the plurality of second resources.

In step 202, it is described by way of example that the second terminal device transmits only one piece of instruction information, but the second terminal device may transmit a plurality of pieces of instruction information to the first terminal device. When the second terminal device sends a plurality of indication information, each indication information is implemented by the same technology, which is not described herein again. Optionally, when the second terminal device sends multiple pieces of indication information, the multiple pieces of indication information may indicate the same resource, or may indicate different resources, which is not limited in the embodiment of the present application.

As mentioned above, in step 202, one second terminal device is taken as an example for explanation, and actually, there may be N second terminal devices that send the indication information to the first terminal device, where N is an integer greater than 0. Therefore, in step 203, the first terminal device receives the instruction information of the N second terminal devices as an example.

Step 203: the first terminal device receives M pieces of indication information from N pieces of second terminal devices.

One or more indication information of the M indication information is used to indicate the resource, and since one second terminal device may send multiple indication information, in this embodiment of the present application, M may be an integer greater than or equal to N.

It should be noted that any one of the M pieces of indication information may also be used to indicate that the second terminal device that sent the indication information fails to receive the first multicast message.

That is to say, in the first embodiment herein, the second terminal device that failed to receive the first multicast message may send the indication information to the first terminal device, and the second terminal device that succeeded in receiving the first multicast message does not send the indication information to the first terminal device.

Step 204: and the first terminal equipment determines resources for multicast transmission according to the M pieces of indication information.

It should be noted that, in step 204, the resource determined by the first terminal device according to the M pieces of indication information may be used for retransmission of the multicast message, for example, retransmission of the first multicast message.

As described above, the resource in which one or more of the M pieces of indication information are located may be used to indicate the resource used by the first terminal device for multicast transmission, and for this reason, the first terminal device may determine the resource used for multicast transmission according to the resource in which one or more of the M pieces of indication information are located.

Further, the one or more indication information may indicate at least one resource, and the first terminal device may determine one indication information from the one or more indication information, and use the resource indicated by the resource where the indication information is located as a resource for multicast transmission.

The first terminal device may determine how to determine one indication information from the one or more indication information, for example, the first terminal device may determine the detection power of each of the M indication information.

In a possible implementation manner, the first terminal device may use, as a resource for multicast transmission, a resource indicated by the indication information with the largest detection power among the M pieces of indication information.

For example, after the first terminal device determines the indication information with the maximum detection power, the identifier of the resource for transmitting the indication information may be determined; the first terminal device may determine, according to the first constraint relationship, an identifier that satisfies the first constraint relationship with the identifier of the resource, so that the resource that satisfies the identifier of the first constraint relationship may be determined as a resource for multicast transmission.

The first constraint relationship may be that the base station and the first terminal device are configured in advance, for example, factory configuration is good, or the base station sends configuration information to the first terminal device in advance for configuration after the terminal is started to use. The first constraint relation may be stored in the form of a correspondence table or may be calculated according to a stored preset formula.

In another possible implementation manner, the first terminal device may use, as a resource for multicast transmission, a resource indicated by any indication information, of the M indication information, whose detection power is greater than a preset threshold. The preset threshold may be determined according to an actual situation, which is not limited in the embodiment of the present application.

In connection with the previous step 201, the first terminal device may retransmit the first multicast message via the resource determined according to the M indication information.

For example, as shown in fig. 9, it is assumed that a resource determined by the first terminal device according to the M pieces of indication information is referred to as a target resource, and the first terminal device may retransmit the first multicast message through the target resource.

It should be noted that, the second terminal device that successfully receives the first multicast message for the first time may not receive the first multicast message retransmitted by the first terminal device, so that resource occupation and power consumption of the second terminal device may be reduced.

For example, when the first terminal device retransmits the first multicast message, the first terminal device may further transmit a first hybrid automatic repeat request (HARQ) identifier, where the first HARQ identifier is an identifier of an HARQ process used for processing the last transmission of the first multicast message by the first terminal device.

All terminal devices in the multicast group where the first terminal device is located may determine whether to receive the first multicast message retransmitted by the first terminal device according to the first HARQ identifier, specifically:

for any second terminal equipment, the second terminal equipment receives the first HARQ identification, and if the HARQ process corresponding to the first HARQ identification is determined to have successfully received the first multicast message, the first multicast message retransmitted by the first terminal equipment is ignored.

Further, if it is determined that the HARQ process corresponding to the first HARQ identifier fails to receive the first multicast message, the second terminal device receives the first multicast message retransmitted by the first terminal device.

It should be noted that, if a second terminal device receives the first multicast message retransmitted by the failed first terminal device, the second terminal device that failed to receive may further perform step 202 again, and correspondingly, the first terminal device needs to perform step 203 and step 204 again until all terminal devices in the multicast group where the first terminal device is located successfully receive the first multicast message.

As can be seen from the process of the first embodiment, the first terminal device determines the resource for transmitting the multicast message through the M pieces of indication information sent by the N pieces of second terminal devices. Because M pieces of indication information are transmitted in the PSFCH channel, extra signaling and configuration information cannot be introduced, the overhead is extremely low, the probability of multicast message retransmission can be reduced, and the resource utilization rate is improved.

Example two:

in the second embodiment, before the multicast message is initially transmitted, the first end device may trigger the end device in the multicast group to indicate the resource to the first end device. After determining at least one resource indicated by the terminal device in the multicast group, the first terminal device may select a resource for multicast message initial transmission from the at least one resource, which may be specifically shown in fig. 10.

Step 1001: the first terminal device sends the second multicast message.

For example, as shown in fig. 11, a first end device sends a second multicast message to a group of end devices including at least N second end devices, where the N second end devices are in the same multicast group as the first end device. The second multicast message may be used to trigger a second terminal device receiving the second multicast message to indicate resources to the first terminal device.

Further, the first terminal device may send channel indication information, and the channel indication information may be used to instruct the second terminal device to transmit the indication information through the PSFCH channel or the preset feedback channel. As to the specific contents of the indication information, the following description may be referred to. For example, the first terminal device may send the channel indication information through a direct connection control channel.

It should be noted that, in step 1001, when the first terminal device instructs the second terminal device to transmit the indication information through the PSFCH channel through the channel indication information, this is equivalent to multiplexing the PSFCH channel, and this method needs to instruct, when transmitting the channel indication information, to no longer determine the resource of the transmission indication information by using the feedback mechanism of the feedback method 2, but to replace the mechanism described in the first embodiment to determine the resource of the transmission indication information. In this case, all end devices in the multicast group in which the first end device is located may be all end devices supporting Release 17 (Rel-17).

Accordingly, when the first terminal device indicates the second terminal device to transmit the indication information through the PSFCH channel through the channel indication information, the second terminal device receiving the second multicast message may determine the resource for transmitting the indication information according to any one of formulas (1) to (18).

It should be noted that, when the first terminal device indicates the preset feedback channel transmission indication information through the channel indication information, the resource location corresponding to the preset feedback channel may be predetermined, or the indication may be performed through the second multicast message.

The symbols included in the preset feedback channel may refer to the PSFCH channel setting, and may also be set differently from the PSFCH channel, for example, as shown in fig. 12, the preset feedback channel may include an Automatic Gain Control (AGC) symbol and at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol, where the AGC symbol is used to adjust the power range of the receiving end, and specifically how to adjust, reference may be made to the description in the prior art, which is not limited in this embodiment of the application, and one OFDM symbol in the at least one OFDM symbol is used to carry the indication information.

It should be noted that the second terminal device may send multiple pieces of indication information, and the multiple pieces of indication information sent by the second terminal device may indicate the same resource or may be used to indicate different resources.

Further, as shown above, in this embodiment of the application, the PSFCH channel or the preset feedback channel, where the second terminal device sends the indication information, includes at least one OFDM symbol. Each of the at least one OFDM symbol may carry one indication information. When the second terminal device sends L pieces of indication information, L is an integer greater than 1, and each OFDM symbol in the L OFDM symbols may carry one piece of indication information.

Each of the L OFDM symbols may carry the same indication information, and at this time, it may be indicated that the resource indicated by the indication information is a resource with least interference.

Each of the L OFDM symbols may also carry different indication information, and at this time, the second terminal device may indicate a plurality of different resources through the different indication information. Of course, not every OFDM symbol needs to carry indication information, for example, a total of 3 OFDM symbols is included, the first two OFDM symbols may respectively carry different indication information, and the last OFDM symbol may not carry any information, which may be determined specifically according to an actual situation, and is not described herein again.

It should be noted that, in the first embodiment, only the second terminal device that failed to receive the first multicast message sends the indication information, and in the second embodiment, the second terminal device that receives the second multicast message in the multicast group may send the indication information to the first terminal device. The second terminal device that has not received the second multicast message may not transmit the indication information to the first terminal device.

Step 1002: and the second terminal equipment sends the indication information to the first terminal equipment.

In step 1002, the indication information sent by the second terminal device may be used to indicate a first resource, and the first resource may be used as a candidate resource for multicast transmission by the first terminal device. The second terminal device specifically determines how to determine the first resource, which is not limited in this embodiment of the application. For example, the second terminal device may use the resource with better channel quality or less interference as the first resource.

In the second embodiment, the indication information may directly indicate the first resource. Specifically, the indication information may be a code domain sequence, and the code domain sequence corresponds to the first resource. After determining the first resource, the second terminal device may send a code domain sequence corresponding to the first resource to the first terminal device as the indication information.

The code domain sequence is a code domain sequence corresponding to the first resource, and may be that the third identifier of the code domain sequence and the first identifier of the first resource satisfy a second constraint relationship. The third identifier of the code domain sequence may be a number of the code domain sequence, and the first identifier may be a resource number of the first resource.

It should be noted that the code domain sequences sent by different second terminal devices are mutually orthogonal, so that when N second terminal devices transmit the code domain sequences in the same channel, the first terminal device can distinguish the code domain sequences sent by different second terminal devices according to orthogonality. For example, a Physical Uplink Control Channel (PUCCH) format (format) 0 may be used as a base sequence, and different second terminal devices perform different cyclic shifts according to the base sequence to obtain corresponding code domain sequences.

Further, in this embodiment of the application, the second constraint relationship may satisfy the following formula:

C＝T mod X···(19)

wherein C represents a third identifier, T represents a third variable, which may be determined according to the first identifier of the first resource; x denotes a fourth variable, which may be determined according to the number Z of candidate resources for carrying indication information and the number Y of code domain sequences supported by the candidate resources, which are respectively illustrated below.

Implementation mode 1,c = r ₁ mod(Z*Y)···(20)

Wherein T = R ₁ ，R ₁ For the first identifier, X = Z × Y, and values of Z and Y are determined according to actual conditions, for example, Y may be 2, 3, 4, 6, 12, and the like. R ₁ Is a first identification of a first resource.

For example, suppose that in formula (20), Z =1,y =6,r ₁ And =7, the determined third identifier is 7.

Implementation 2,c = (R) ₅ -R ₁ )mod(Z*Y)···(21)

Wherein T = R ₅ -R ₁ ，X＝Z*Y，R ₅ Is the firstAnd the terminal equipment sends the identifier of the resource of the second multicast message. For example, suppose that in formula (21), Z =4,y =2,r ₅ -R ₁ And =1, the determined third identifier is 1.

Implementation 3,c = (R) ₅ +R ₁ )mod(Z*Y)···(22)

Wherein T = R ₁ ，X＝Z*Y。

Implementation 4,c = (R) ₁ -R ₅ )mod(Z*Y)···(23)

Wherein T = R ₁ -R ₅ X = Z × Y. For example, suppose that in equation (23), Z =4,y =2,r ₁ -R ₅ And =1, the determined third identifier is 1.

Implementation 5,c = (L _ ID + R) ₁ )mod(Z*Y)···(24)

Wherein, T = L _ ID + R ₁ L _ ID is the identifier of the first terminal device, for example, may be a layer 1 identifier of the first terminal device, and may also be another identifier of the first terminal device, for example, Y may be 2, 3, 4, 6, 12, and so on. R ₁ Is a first identification of the first resource.

Implementation 6,c = (L _ ID + R) ₅ -R ₁ )mod(Z*Y)···(25)

Wherein T = L _ ID + R ₅ -R ₁ ，X＝Z*Y，R ₅ And sending the identifier of the resource of the second multicast message to the first terminal equipment.

Implementation 7,c = (L _ ID + R) ₅ +R ₁ )mod(Z*Y)···(26)

Wherein T = R ₁ ，X＝Z*Y。

Implementation mode 8,c = (L _ ID + R) ₁ -R ₅ )mod(Z*Y)···(27)

Wherein, T = L _ ID + R ₁ -R ₅ ，X＝Z*Y。

Further, in this embodiment, a value number included in a value range of the third variable is less than or equal to that of the fourth variable. Specifically, assuming that the value range of T is [ T2, T1], where T1 is the maximum value of the value range of T and T2 is the minimum value of the value range of T, in implementation 1 to implementation 4, T is less than or equal to X, and T = T1-T2+1. In this case, the first resource may uniquely determine one code domain sequence, and avoid the occurrence that the first resource corresponds to a plurality of code domain sequences.

In step 1002, it is described that only the second terminal device transmits one piece of instruction information, but the second terminal device may transmit a plurality of pieces of instruction information to the first terminal device. When the second terminal device sends a plurality of indication information, each indication information is implemented by the same technology, which is not described herein again. Optionally, when the second terminal device sends multiple pieces of indication information, the multiple pieces of indication information may indicate the same resource, or may indicate different resources, which is not limited in this embodiment of the application.

For example, as shown in fig. 12, the resource carrying the indication information may include one AGC symbol and at least one OFDM symbol. The second terminal device may transmit a plurality of indication information in a plurality of OFDM symbols of the at least one OFDM symbol, wherein one indication information may be transmitted in one OFDM symbol. When a plurality of indication information indicate the same resource, a plurality of OFDM symbols carrying the plurality of indication information carry the same indication information; when the plurality of indication information indicate different resources, a plurality of OFDM symbols carrying the plurality of indication information carry different indication information.

If N second terminal devices receive the second multicast message sent by the first terminal device, the first terminal device may receive M pieces of indication information of the N second terminal devices, which may specifically refer to step 1003.

Step 1003: the first terminal device receives M pieces of indication information from N pieces of second terminal devices.

For example, as shown in fig. 13, the example that N second terminal devices send indication information to the first terminal device through the preset feedback channel is described.

Step 1004: and the first terminal equipment determines the resources for multicast transmission according to the M pieces of indication information.

It should be noted that the resource for multicast transmission determined by the first terminal device may be used for initial transmission of a multicast message, for example, initial transmission of a third multicast message. The specific content of the third multicast message is not limited in this embodiment, for example, the third multicast message may include data that the first terminal device needs to transmit, and may also include control signaling.

As mentioned above, one or more of the M indication information may be used to indicate resources used by the first terminal device for multicast transmission, and for this purpose, the first terminal device may determine resources used for multicast transmission according to the resources in which the one or more of the M indication information is located.

Further, the one or more indication information may indicate at least one resource, and the first terminal device may determine one indication information from the one or more indication information, and use the resource indicated by the indication information as a resource for multicast transmission.

The first terminal device may determine how to determine one indication information from the one or more indication information, for example, the first terminal device may determine the detected power of each of the M plurality of indication information.

Further, in a possible implementation manner, the first terminal device may use, as a resource for multicast transmission, a resource determined by the indication information with the largest detection power among the M pieces of indication information. In another possible implementation manner, the first terminal device may use, as a resource for multicast transmission, a resource determined by any one of the M pieces of indication information whose detection power is greater than a preset threshold. The preset threshold may be determined according to actual conditions, which is not limited in the embodiment of the present application.

Further, in another possible implementation manner, when one second terminal device indicates the same resource through multiple pieces of indication information, for example, as shown in fig. 12, the resource carrying the indication information may include one AGC symbol and at least one OFDM symbol, where one OFDM symbol in the at least one OFDM symbol may carry one indication information, and multiple OFDM symbols may carry the same indication information. In this case, the first terminal device may further determine a sum of detection powers of the indication information indicating the same resource among the M indication information. The first terminal device may use a resource determined by the indication information corresponding to the maximum sum of the detection powers as a resource for multicast transmission, or the first terminal device may use any one of the resources determined by the indication information that the sum of the detection powers is greater than a preset threshold as a resource for multicast transmission.

It should be noted that, in the second embodiment, after the first terminal device transmits the third multicast message, the N second terminal devices may perform feedback by using the feedback method 2. In the feedback mode 2, when the second terminal device successfully receives the third multicast message, ACK is fed back; and feeding back NACK when the second terminal equipment fails to receive the third multicast message.

With reference to the above description, if there is a second terminal device that fails to receive the third multicast message in the N second terminal devices, the second terminal device that fails to receive the third multicast message may perform feedback in the feedback mode 2.

Optionally, if the first multicast message sent by the first terminal device is successfully received by all the second terminal devices in the group of terminal devices where the first terminal device is located, after the first terminal device transmits the third multicast message, the N second terminal devices may also perform feedback in the feedback mode 1.

Further, after the first terminal device transmits the third multicast message, if there is a second terminal device that fails to receive the third multicast message in the N second terminal devices, the first terminal device may have the following two implementation manners:

the implementation mode is as follows: the first terminal equipment determines a third resource from the at least one resource, wherein the third resource is a resource except for the first transmission of the third multicast message;

and the first terminal equipment retransmits the third multicast message through a third resource. Optionally, a second HARQ identity may also be transmitted, where the second HARQ identity is an identity of a HARQ process for processing the third multicast message.

And the second terminal device receives the second HARQ identifier, and if it is determined that the HARQ process corresponding to the second HARQ identifier has successfully received the third multicast message, the third multicast message retransmitted by the first terminal device may be ignored.

Further, if it is determined that the HARQ process corresponding to the second HARQ identifier fails to receive the third multicast message, the second terminal device receives the third multicast message retransmitted by the first terminal device.

The implementation mode two is as follows: the first terminal device performs step 1001 again and correspondingly, the N second terminal devices perform step 1002 again. The first terminal device may thus determine the resource for retransmitting the third multicast message again according to the obtained M pieces of indication information, and the specific process is not described again.

As can be seen from the process of the second embodiment, in the multicast group where the first terminal device is located, only N second terminal devices that receive the first multicast message need to send the indication information in the same channel, so that the feedback efficiency can be improved, and a signaling storm can be avoided. Further, in the multicast group where the first terminal device is located, the second terminal device that does not receive the first multicast message may not send the indication information, so as to achieve the purpose of reducing multicast delay and power consumption.

The various embodiments described herein may be implemented as stand-alone solutions or combined in accordance with inherent logic and are intended to fall within the scope of the present application.

In the embodiments provided by the present application, the method provided by the embodiments of the present application is introduced from the perspective of interaction between the devices. In order to implement the functions in the method provided by the embodiment of the present application, the first terminal device or the second terminal device may include a hardware structure and/or a software module, and the functions are implemented in the form of a hardware structure, a software module, or a hardware structure plus a software module. Whether any of the above-described functions is implemented as a hardware structure, a software module, or a hardware structure plus a software module depends upon the particular application and design constraints imposed on the technical solution.

The division of the modules in the embodiment of the present application is schematic, and is only a logic function division, and there may be another division manner in actual implementation. In addition, functional modules in the embodiments of the present application may be integrated into one processor, may exist alone physically, or two or more modules are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode.

Similar to the above concept, as shown in fig. 14, an apparatus 1400 is further provided in this embodiment of the present application for implementing the function of the first terminal device or the second terminal device in the foregoing method. The device may be a software module or a system-on-a-chip, for example. In the embodiment of the present application, the chip system may be composed of a chip, and may also include a chip and other discrete devices. The apparatus 1400 may include: a processing unit 1401 and a communication unit 1402.

In this embodiment, the communication unit may also be referred to as a transceiver unit, and may include a sending unit and/or a receiving unit, which are respectively configured to perform the steps of sending and receiving by the first terminal device or the second terminal device in the foregoing method embodiments.

Hereinafter, a communication device according to an embodiment of the present application will be described in detail with reference to fig. 14 to 15. It should be understood that the description of the apparatus embodiments corresponds to the description of the method embodiments, and therefore, for brevity, details are not repeated here, since the details that are not described in detail may be referred to the above method embodiments.

The communication unit may also be referred to as a transceiver, a transceiving means, etc. A processing unit may also be referred to as a processor, a processing board, a processing module, a processing device, or the like. Alternatively, a device for implementing a receiving function in the communication unit 1402 may be regarded as a receiving unit, and a device for implementing a transmitting function in the communication unit 1402 may be regarded as a transmitting unit, that is, the communication unit 1402 includes a receiving unit and a transmitting unit. A communication unit may also sometimes be referred to as a transceiver, transceiver circuit, or the like. A receiving unit may also be referred to as a receiver, a receiving circuit, or the like. A transmitting unit may also sometimes be referred to as a transmitter, or a transmitting circuit, etc.

It should be understood that the communication unit 1402 is configured to perform the transmitting operation and the receiving operation of the first terminal device in the method embodiment shown in fig. 2 or fig. 10, and the processing unit 1401 is configured to perform other operations besides the transceiving operation of the first terminal device in the method embodiment shown in fig. 2 or fig. 10.

For example, in one implementation, the communication unit 1402 is configured to perform all transceiving steps of the first terminal device in the embodiment shown in fig. 2, such as performing step 201 and step 203, and/or other processes for supporting the techniques described herein. A processing unit 1401 for performing other operations than the transceiving operations of the first terminal device in the embodiment shown in fig. 2, for example, for performing step 204, and/or for supporting other processes of the techniques described herein.

Alternatively, the communication unit 1402 is configured to perform the sending operation and the receiving operation of the second terminal device in the method embodiment shown in fig. 2, and the processing unit 1401 is configured to perform other operations besides the sending and receiving operation of the second terminal device in the method embodiment shown in fig. 2.

For example, in another implementation, communication unit 1402 is configured to perform all transceiving steps of the first terminal device in the embodiment shown in fig. 10, such as performing steps 1001 and 1003, and/or other processes for supporting the techniques described herein. A processing unit 1401 for performing other operations than transceiving operations, such as performing step 1004, and/or other processes for supporting the techniques described herein, of the first terminal device in the embodiment shown in fig. 10.

Alternatively, the communication unit 1402 is configured to perform the transmitting operation and the receiving operation of the second terminal device in the method embodiment shown in fig. 10, and the processing unit 1401 is configured to perform other operations except the transceiving operation of the second terminal device in the method embodiment shown in fig. 10.

As shown in fig. 15, which is a device 1500 provided in the embodiment of the present application, the device shown in fig. 15 may be a hardware circuit implementation of the device shown in fig. 14. The communication apparatus may be adapted to the flow chart shown above, and perform the functions of the first terminal device or the second terminal device in the above method embodiment. For convenience of explanation, fig. 15 shows only main components of the communication apparatus.

The apparatus 1500 can also include at least one memory 1530 for storing program instructions and/or data. The memory 1530 and the processor 1520 are coupled. The coupling in the embodiments of the present application is an indirect coupling or a communication connection between devices, units or modules, and may be an electrical, mechanical or other form for information interaction between the devices, units or modules. The processor 1520 may operate in conjunction with the memory 1530. The processor 1520 may execute program instructions stored in the memory 1530. At least one of the at least one memory may be included in the processor.

The apparatus 1500 shown in fig. 15 includes at least one processor 1520 and a communications interface 1510, the processor 1520 for executing instructions or programs stored in the memory 1530. When the instructions or programs stored in the memory 1530 are executed, the processor 1520 is configured to perform the operations performed by the processing unit 1401 in the above-described embodiment, and the communication interface 1510 is configured to perform the operations performed by the communication unit 1402 in the above-described embodiment.

In embodiments of the present application, the communication interface may be a transceiver, circuit, bus, module, or other type of communication interface. In the embodiment of the present application, when the communication interface is a transceiver, the transceiver may include an independent receiver and an independent transmitter; a transceiver that integrates transceiving functions, or a communication interface may also be used.

The apparatus 1500 may also include communication lines 1540. Wherein the communication interface 1510, the processor 1520, and the memory 1530 may be connected to each other through a communication line 1540; the communication line 1540 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication lines 1540 can be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in FIG. 15, but this is not intended to represent only one bus or type of bus.

The application also provides a system, which comprises the first terminal device and at least N second terminal devices.

The first terminal device and the N second terminal devices may execute the steps in the flow shown in fig. 2;

alternatively, the first terminal device and the N second terminal devices may execute the steps in the flow shown in fig. 10, which specifically refers to the foregoing description and is not repeated herein.

In combination with the above, the present application also provides the following embodiments, and it should be noted that the numbering of the following embodiments does not necessarily need to follow the numbering sequence of the previous embodiments:

embodiment 1, a multicast transmission method, wherein the method comprises:

the first terminal equipment receives M pieces of indication information from N pieces of second terminal equipment; one or more pieces of indication information in the M pieces of indication information are used for indicating resources, N is an integer larger than 0, and M is an integer larger than or equal to N;

and the first terminal equipment determines resources for multicast transmission according to the M pieces of indication information.

Embodiment 2 is the method according to embodiment 1, wherein the resource in which the one or more indication information is located is used to indicate the resource for multicast transmission.

Embodiment 3, according to the method of embodiment 2, before the first terminal device receives M pieces of indication information from N second terminal devices, the method further includes:

the first terminal equipment sends a first multicast message to a group of terminal equipment comprising the N second terminal equipment; one or more of the M pieces of indication information are used to indicate that the second terminal device sending the corresponding indication information fails to receive the first multicast message.

Embodiment 4 is the method according to

embodiment

2 or 3, wherein a second resource in which a first indication information in the one or more indication information is located is used to indicate a first resource, the first resource corresponds to the second resource, and the first resource is a candidate resource for multicast transmission by the first terminal device.

Embodiment 5, the method of embodiment 4, wherein the first resource corresponds to a second resource, comprising:

the first identity of the first resource and the second identity of the second resource satisfy a first constraint relationship.

Embodiment 6, according to the method of embodiment 5, the first constraint relationship is: the second identification is determined by a modulus operation according to the first variable and the second variable; wherein the first variable is determined according to the first identifier, and the second variable is determined according to the number Z of candidate resources for carrying the M indication information and the number Y of code domain sequences supported by the candidate resources.

Embodiment 7 the method of embodiment 6, wherein the first variable H satisfies any one of the following formulas:

The second variable K satisfies any one of the following formulas:

k = Z x Y, or, K = Z x Y-1;

Embodiment 8 the method of embodiment 7, wherein the first constraint is R ₂ = H mod K, wherein R ₂ Is the first identifier.

Embodiment 9, according to the method in embodiment 1, before the first terminal device receives M pieces of indication information from N pieces of second terminal devices, the method further includes:

the first terminal equipment sends a second multicast message to a group of terminal equipment comprising the N second terminal equipment;

the second multicast message is used for triggering the second terminal equipment receiving the second multicast message to indicate resources to the first terminal equipment.

Embodiment 10, the method of embodiment 9, wherein the second multicast message includes channel indication information;

Embodiment 11 the method of embodiment 10, wherein the predetermined feedback channel comprises 1 AGC symbol and at least one OFDM symbol.

Embodiment 12 and the method according to embodiment 11, wherein when the channel indication information is used to indicate the preset feedback channel, at least one indication information from one or more second terminal devices of the N second terminal devices is carried through at least one OFDM symbol in the preset feedback channel.

Embodiment 13 and according to the method of any one of embodiments 9 to 12, wherein a first indication information of the one or more indication information is used to indicate a first resource, the first indication information is a code domain sequence corresponding to the first resource, and the first resource is a candidate resource for multicast transmission by the first terminal device.

Embodiment 14, according to the method in embodiment 12, when the first indication information is a code domain sequence corresponding to the first resource, a third identifier of the first indication information and the first identifier of the first resource satisfy a second constraint relationship.

Embodiment 15, according to the method of embodiment 14, the second constraint is: the third identification is determined by a modulus operation according to a third variable and a fourth variable;

wherein the third variable is determined according to the first identifier, and the fourth variable is determined according to the number Z of candidate resources for carrying the M indication information and the number Y of code domain sequences supported by the candidate resources.

Embodiment 16, the method of embodiment 15, wherein the third variable T satisfies any one of the following formulas:

T＝R ₁ or T = R ₅ -R ₁ Or T = R ₅ +R ₁ Or T = R ₁ -R ₅ ；

The fourth variable X satisfies any one of the following equations:

X＝Z*Y；

Embodiment 17, the method of embodiment 16, wherein the second constraint is C = T mod X, where C is the third indicator.

Embodiment 18 is the method according to any one of embodiments 5 to 8 and 13 to 17, wherein the first identifier is a resource number of the first resource, and the resource number is numbered in a frequency domain priority manner, or the resource number is numbered in a time domain priority manner.

Embodiment 19 and the method according to any of embodiments 1 to 18, where the determining, by the first terminal device, the resource for multicast transmission according to the M pieces of indication information includes:

the first terminal equipment determines the detection power of each piece of indication information used for indicating resources in the M pieces of indication information;

the first terminal device takes the resource indicated by the indication information with the maximum detection power as the resource for multicast transmission;

or the first terminal device takes the resource indicated by any indication information with the detection power larger than the preset threshold value as the resource for multicast transmission.

Embodiment 20, a method for multicast transmission, wherein the method comprises:

the second terminal equipment determines the indication information; the indication information is used for indicating the resource determined by the second terminal equipment by the first terminal equipment;

and the second terminal equipment sends the indication information to the first terminal equipment.

Embodiment 21, according to the method of embodiment 20, before the second terminal device determines the indication information, the method further includes:

Embodiment 22 and the method according to embodiment 21, where the sending, by the second terminal device, the indication information to the first terminal device includes:

the second terminal equipment determines a first resource; the first resource is a candidate resource for multicast transmission of the first terminal device;

and the second terminal equipment sends the indication information to the first terminal equipment through a second resource, wherein the first resource corresponds to the second resource.

Embodiment 23, the method of embodiment 22, wherein the first resource corresponds to the second resource, comprising:

Embodiment 24, according to the method of embodiment 23, the first constraint relationship is: the second identification is determined by a modulus operation according to the first variable and the second variable;

wherein the first variable is determined according to the first identifier, and the second variable is determined according to the number Z of candidate resources for carrying the M indication information and the number Y of code domain sequences supported by the candidate resources.

Embodiment 25, the method of embodiment 24, wherein the first variable H satisfies any one of the following formulas:

The second variable K satisfies any one of the following formulas:

k = Z x Y, or, K = Z x Y-1;

Embodiment 26, the method according to embodiment 20, wherein before the second terminal device determines the indication information, the method further includes:

the second terminal equipment receives a second multicast message from the first terminal equipment; the second multicast message is used for triggering the second terminal device to indicate resources to the first terminal device.

Embodiment 27 the method of embodiment 26, wherein the second multicast message comprises channel indication information;

Embodiment 28 and the method according to embodiment 26, wherein the determining, by the second terminal device, the indication information includes:

the second terminal equipment determines a first resource;

and the second terminal equipment determines the code domain sequence corresponding to the first resource as the indication information.

Embodiment 29 and the method according to embodiment 28, wherein the third identifier of the code domain sequence corresponding to the first resource and the first identifier of the first resource satisfy a second constraint relationship.

Embodiment 30, according to the method of embodiment 29, the second constraint relationship is: the third identification is determined by a modulus operation according to a third variable and a fourth variable;

Embodiment 31 the method of embodiment 30, wherein the third variable T satisfies any one of the following formulas:

T＝R ₁ or T = R ₅ -R ₁ Or T = R ₅ +R ₁ Or T = R ₁ -R ₅ ；

The fourth variable X satisfies any one of the following equations:

X＝Z*Y；

An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, may implement the process related to the first terminal device in the embodiment shown in fig. 2 and provided by the foregoing method embodiment.

An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, can implement the process related to the second terminal device in the embodiment shown in fig. 2 and provided by the foregoing method embodiment.

The embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, can implement the process related to the first terminal device in the embodiment shown in fig. 10 and provided by the foregoing method embodiment.

An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, may implement the process related to the second terminal device in the embodiment shown in fig. 10 and provided in the foregoing method embodiment.

An embodiment of the present application further provides a computer program product containing instructions, where the instructions are executed to perform the method of the first terminal device in the method embodiment shown in fig. 2.

An embodiment of the present application further provides a computer program product containing instructions, where the instructions are executed to perform the method of the second terminal device in the method embodiment shown in fig. 2.

Embodiments of the present application further provide a computer program product containing instructions, which when executed, perform the method of the first terminal device in the method embodiment shown in fig. 10.

An embodiment of the present application further provides a computer program product containing instructions, which when executed, perform the method of the second terminal device in the method embodiment shown in fig. 10.

An embodiment of the present application further provides a chip, which includes a processor, where the processor is coupled to a memory, and is configured to execute a computer program or an instruction stored in the memory, and when the processor executes the computer program or the instruction, the method of the first terminal device in the method embodiment shown in fig. 2 is executed.

An embodiment of the present application further provides a chip, which includes a processor, where the processor is coupled to a memory, and is configured to execute a computer program or an instruction stored in the memory, and when the processor executes the computer program or the instruction, the method of the second terminal device in the method embodiment shown in fig. 2 is executed.

An embodiment of the present application further provides a chip, which includes a processor, where the processor is coupled to a memory, and is configured to execute a computer program or an instruction stored in the memory, and when the processor executes the computer program or the instruction, the method of the first terminal device in the method embodiment shown in fig. 10 is performed.

An embodiment of the present application further provides a chip, which includes a processor, where the processor is coupled to a memory, and is configured to execute a computer program or an instruction stored in the memory, and when the processor executes the computer program or the instruction, the method of the second terminal device in the method embodiment shown in fig. 10 is performed.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A method of transmission, comprising:

the first terminal equipment receives indication information from the N second terminal equipment; the indication information is carried by a physical direct link feedback channel PSFCH channel, and N is an integer greater than 0;

and the first terminal equipment determines a first resource according to the resource of the PSFCH channel and determines a resource for transmitting the message according to the first resource.

2. The method according to claim 1, wherein the resource on which the PSFCH channel is located corresponds to the first resource.

3. The method according to claim 1 or 2, wherein the first resource is a time-frequency resource.

4. The method of claim 1, wherein before the first terminal device receives the indication information from the N second terminal devices, the method further comprises:

the first terminal equipment sends a first message to a group of terminal equipment comprising the N second terminal equipment;

the indication information is used for indicating that the second terminal equipment which sends the corresponding indication information fails to receive the first message.

5. The method according to claim 4, wherein the second resource in which the indication information is located is used to indicate a first resource, the first resource corresponds to a second resource, and the first resource is a candidate resource for the first terminal device to transmit.

6. The method of claim 5, wherein the first resource corresponds to a second resource, comprising:

7. The method of claim 6, wherein the first constraint relationship is: the second identification is determined by a modulus operation according to the first variable and the second variable;

wherein the first variable is determined according to the first identifier, and the second variable is determined according to the number Z of candidate resources for carrying the indication information and the number Y of code domain sequences supported by the candidate resources.

8. The method of claim 7, wherein the first variable H satisfies any one of the following equations:

The second variable K satisfies any one of the following formulas:

k = Z x Y, or, K = Z x Y-1;

wherein R is ₁ Is said first label, R ₃ And sending the identifier of the resource of the first message for the first terminal equipment, wherein the L _ ID is the identifier of the first terminal equipment.

9. The method of claim 1, wherein before the first terminal device receives the indication information from the N second terminal devices, the method further comprises:

the first terminal equipment sends a second message to a group of terminal equipment comprising the N second terminal equipment;

the second message is used for triggering the second terminal equipment receiving the second message to send the indication information to the first terminal equipment.

10. The method of claim 9, wherein the second message comprises channel indication information;

11. The method of claim 10, wherein when the channel indication information is used for indicating the predetermined feedback channel, the indication information is carried by at least one OFDM symbol in the predetermined feedback channel.

12. The method according to any of claims 9 to 11, wherein the indication information is used to indicate a first resource, the indication information is a code domain sequence corresponding to the first resource, and the first resource is a candidate resource for transmission by the first terminal device.

13. The method of claim 12, wherein when the indication information is a code domain sequence corresponding to the first resource, a third flag of the indication information and the first flag of the first resource satisfy a second constraint relationship.

14. The method of claim 13, wherein the second constraint is: the third identification is determined by a modulus operation according to a third variable and a fourth variable;

wherein the third variable is determined according to the first identifier, and the fourth variable is determined according to the number Z of candidate resources for carrying M indication information and the number Y of code domain sequences supported by the candidate resources.

15. The method of claim 14, wherein the third variable T satisfies any one of the following equations:

T＝R ₁ or T = R ₅ -R ₁ Or T = R ₅ +R ₁ Or T = R ₁ -R ₅ ；

The fourth variable X satisfies any one of the following equations:

X＝Z*Y；

wherein R is ₁ Is said first mark, R ₅ And sending the identifier of the resource of the second message for the first terminal equipment.

16. A method of transmission, comprising:

the second terminal equipment determines the indication information; the indication information is carried by a physical direct connection link feedback channel PSFCH channel; the resource where the PSFCH channel is located is used for determining a first resource, and the first resource is used for determining a resource for transmitting a message by a first terminal device;

17. The method according to claim 16, wherein the resource on which the PSFCH channel is located is used to determine a first resource, wherein the first resource is used to determine a resource for the first terminal device to transmit a message, and wherein the resource on which the PSFCH channel is located corresponds to the first resource.

18. The method of claim 17, wherein the first resource is a time-frequency resource.

19. The method of claim 16, wherein before the second terminal device determines the indication information, the method further comprises:

the second terminal equipment fails to receive the first message sent by the first terminal equipment; the indication information is further used for indicating that the second terminal device fails to receive the first message.

20. The method of claim 19, wherein the second terminal device sends the indication information to the first terminal device, and wherein the sending comprises:

the second terminal equipment determines a first resource; the first resource is a candidate resource for transmission by the first terminal device;

21. The method of claim 20, wherein the first resource corresponds to the second resource, and wherein the method comprises:

22. The method of claim 21, wherein the first constraint relationship is: the second identification is determined by a modulus operation according to the first variable and the second variable;

23. The method of claim 22, wherein the first variable H satisfies any one of the following equations:

The second variable K satisfies any one of the following formulas:

k = Z x Y, or, K = Z x Y-1;

wherein R is ₁ Is said first label, R ₃ And sending the identifier of the resource of the first message to the first terminal equipment, wherein the L _ ID is the identifier of the first terminal equipment.

24. The method of claim 16, wherein before the second terminal device determines the indication information, the method further comprises:

the second terminal equipment receives a second message from the first terminal equipment; the second message is used for triggering the second terminal device to indicate resources to the first terminal device.

25. The method of claim 24, wherein the second message comprises channel indication information;

26. The method of claim 24, wherein the second terminal device determines the indication information, and comprises:

27. The method of claim 26, wherein the third identifier of the code-domain sequence corresponding to the first resource and the first identifier of the first resource satisfy a second constraint relationship.

28. The method of claim 27, wherein the second constraint is: the third identification is determined by a modulus operation according to a third variable and a fourth variable;

wherein the third variable is determined according to the first identifier, and the fourth variable is determined according to the number Z of candidate resources for carrying the indication information and the number Y of code domain sequences supported by the candidate resources.

29. The method of claim 28, wherein the third variable T satisfies any one of the following equations:

T＝R ₁ or T = R ₅ -R ₁ Or is orT = R ₅ +R ₁ Or T = R ₁ -R ₅ ；

The fourth variable X satisfies any one of the following equations:

X＝Z*Y；

wherein R is ₁ Is said first label, R ₅ And sending the identifier of the resource of the second message for the first terminal equipment.

30. A communications apparatus, comprising a processor and a memory:

the processor for executing a computer program or instructions stored in the memory, the method of any of claims 1 to 29 being performed when the computer program or instructions are executed.

31. A communication system, comprising:

a first terminal device for sending a first message to a group of terminal devices comprising at least N second terminal devices; n is an integer greater than 0;

the second terminal device is used for sending the indication information to the first terminal device when determining that the first message is unsuccessfully received; the indication information is used for indicating that the second terminal equipment fails to receive the first message, and the indication information is carried by a physical direct link feedback channel (PSFCH);

the first terminal device is used for receiving indication information from N second terminal devices; and determining a first resource according to the resource of the PSFCH channel, and determining the resource for transmitting the message according to the first resource.

32. A communication system, comprising:

the first terminal equipment is used for sending a second message to a group of terminal equipment comprising at least N second terminal equipment; the second message is used for triggering the second terminal equipment receiving the second message to send indication information to the first terminal equipment, and N is an integer larger than 0;

the second terminal device is used for sending the indication information to the first terminal device when the second message is determined to be received; the indication information is carried by a physical direct connection link feedback channel PSFCH channel;