Communication method, apparatus and system

Abstract

The present application relates to the technical field of communications. Disclosed are a communication method, apparatus and system. The method comprises: a first communication apparatus receiving on a first resource broadcast information from a second communication apparatus, wherein the broadcast information is used for sidelink synchronization; and sending a first message on a second resource, wherein the first message is used for requesting access to the second communication apparatus, the second resource is an access resource in a first access resource set, the first access resource set is located after the first resource in terms of time domain, the first access resource set comprises Y access resources located in X periods, each of the X periods includes N access resources, where Y=X*N, and Y is an integer greater than 1. In this way, by selecting one access resource from among Y access resources in X periods to send a first message, the probability of a collision caused by means of different T nodes sending access request messages on the same access resource is reduced, and the efficiency of random access is improved.

Description

A communication method, apparatus and system

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411786868.9, filed on December 5, 2024, entitled "A Communication Method, Apparatus and System", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of communication technology, and in particular to a communication method, apparatus and system. Background Technology

[0004] With the development of wireless communication technology, people's demand for high data rates and user experience is increasing. At the same time, the demand for neighborhood services—which allow people to know and communicate with people or things around them—is also gradually increasing. Therefore, device-to-device (D2D) technology (i.e., side-by-side communication) has emerged. The application of D2D technology can reduce the burden on cellular networks, reduce the battery power consumption of user devices, improve data rates, and well meet the needs of neighborhood services.

[0005] In a side-link communication scenario, the grant node (G node) sends a broadcast message, which can be received by one or more terminal node (T node) devices. The terminal node then performs side-link synchronization with the G node and connects to the G node.

[0006] However, when there are many T nodes, multiple access attempts initiated by T nodes may collide (e.g., access attempts are initiated on the same resource), resulting in long access times and low access efficiency for T nodes. Summary of the Invention

[0007] This application provides a communication method, apparatus, and system that selects one access resource from Y access resources over X periods to send a first message, thereby reducing the probability of collisions when different T nodes send the first message on the same access resource and improving the efficiency of random access.

[0008] In a first aspect, embodiments of this application provide a communication method, which can be executed by a first communication device. Unless otherwise specified, the "first communication device" in this application can refer to a communication device (e.g., a first terminal device or a T-node), a component of the communication device (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the functions of the communication device. For example, in the method provided in the first aspect, the first communication device receives broadcast information from a second communication device on a first resource, the broadcast information being used for side-by-side synchronization; and sends a first message on a second resource, the first message being used to request access to the second communication device; wherein, the second resource is an access resource in a first access resource set, the first access resource set being located after the first resource in the time domain; the first access resource set includes Y access resources located in X periods, each of the X periods including N access resources, Y = X * N, where Y is an integer greater than 1; X is an integer greater than or equal to 1, and N is an integer greater than 1; or, X is an integer greater than 1, and N is an integer greater than or equal to 1.

[0009] By using the above method, the first message is sent by selecting one access resource from the Y access resources in X periods. Compared with the scheme of sending the first message in the next subframe after the subframe where the broadcast information is located, this method is more effective in reducing the probability of collisions when different T nodes send access request messages on the same access resource, thereby improving the efficiency of random access.

[0010] In one possible design, the values ​​of Y, X, and N are indicators, configurations, pre-configurations, or predefined.

[0011] In one possible design, the time units in which the N access resources occupy the period are determined based on the time unit in which the first resource occupies the period. Alternatively, the subframe in which the N access resources occupy the period is associated with or corresponds to the subframe in which the first resource occupies the period.

[0012] In this way, different broadcast resources can correspond to different access resources, so that different G nodes can detect access request messages on the access resources corresponding to their respective broadcast resources, and T nodes can also send access request messages on the corresponding access resources to access the corresponding G nodes.

[0013] In one possible design, the index of the time unit in which access resource i is located in the period among the N access resources is Fi, and the index of the time unit in which the first resource is located in the period is FH; Fi = FH + A + T * i, or Fi = (FH + A + T * i) mod L, i = 0, 1, 2, ..., N-1; where L is the number of time units included in each period, and A and T are integers greater than or equal to 0.

[0014] In one possible design, the index of the time unit in which the access resource n in the N access resources is located in the period is Fn, and the index of the time unit in which the first resource is located in the period is FH; Fn = FH + B + (L*n / N), or, Fn = (FH + B + (L*n / N)) mod L, n = 0, 1, 2, ..., N-1; where B is an integer greater than or equal to 0.

[0015] In one possible design, the first message includes a first signal and access information; or, the first message is the first signal; wherein the first signal is generated based on a first SLSSID.

[0016] In one possible design, sending a first message on the second resource includes: after the physical layer of the first communication device receives an instruction from a higher layer of the first communication device, it sends a first message on the second resource; wherein the first cycle of the X cycles is the most recent cycle after receiving the instruction.

[0017] In one possible design, before sending the first message on the second resource, the method further includes: sending a second message on a third resource, the second message being used to request access to the second communication device; wherein the third resource is located after the first resource in the time domain, and the first of the X cycles is the next cycle after the first cycle in which the third resource is located.

[0018] In one possible design, before sending the first message on the second resource, the method further includes: sending a second message on a third resource, the second message being used to request access to the second communication device; determining that the access request of the second message has failed; wherein the third resource is located after the first resource in the time domain, and the first period of the X periods is the most recent period after determining that the access request of the second message has failed.

[0019] In one possible design, sending the second message on the third resource includes: after the physical layer of the first communication device receives indication information from a higher layer of the first communication device, sending the second message on the third resource; wherein the third resource is the most recent access resource after receiving the indication information; or, the third resource is the first access resource in the first period, or the third resource is randomly determined from the access resources in the first period, the first period being the most recent period after receiving the indication information; or, the third resource is randomly determined from the access resources in the first period after receiving the indication information, the first period being the period for receiving the indication information.

[0020] Thus, after receiving the instruction from the higher layer, the physical layer of the first communication device first attempts to send an access request message on a nearby resource (i.e., the third resource) to facilitate access to the second communication device as quickly as possible. If access fails, it can randomly select resources within a wider range to access the device, thereby reducing the probability of collisions with other accessing communication devices.

[0021] In one possible design, the second message includes a second signal and access information; or, the second message is the second signal; wherein the second signal is generated based on a second SLSSID.

[0022] In one possible design, the method further includes: sending a third message on a fourth resource, the third message being used to request access to the second communication device; wherein the fourth resource is an access resource in a second access resource set, the first period of the resource in the second access resource set is the period following the last period of the X periods, and the second access resource set includes access resources in P periods, where P is an integer greater than or equal to X.

[0023] Thus, by selecting one access resource from the P access resources to send the third message, it is convenient to quickly access the G node when the number of T nodes is small.

[0024] In one possible design, the method further includes: determining that the access request of the first message request has failed; sending a third message on a fourth resource, the third message being used to request access to the second communication device; wherein the fourth resource is an access resource in a second access resource set; the first period of the resource in the second access resource set is the most recent period after determining that the access request of the first message request has failed, and the second access resource set includes access resources for P periods, where P is an integer greater than or equal to X.

[0025] In one possible design, the value of P is equal to the value of X.

[0026] In one possible design, the value of P is determined based on the value of X and a first set.

[0027] In one possible design, the value of P is the next value in the first set that is greater than X.

[0028] In one possible design, if the value of X is not the largest value in the first set, then the value of P is the next largest value in the first set that is greater than X, and / or, if the value of X is the largest value in the first set, then the value of P is equal to the value of X.

[0029] In one possible design, the broadcast information includes information indicating how the value of P is determined and / or the value of X; wherein the method of determining the value of P includes: the value of P being equal to the value of X, or the value of P being determined based on the value of X and a first set.

[0030] In one possible design, the third message includes a third signal and access information; or, the third message is the third signal; wherein the third signal is generated based on a third SLSSID.

[0031] In one possible design, the method further includes: determining that the number of times the first communication device requests access is greater than or equal to a first threshold.

[0032] In one possible design, before sending the third message on the fourth resource, the method further includes: determining that a response message to the first message has not been received; or determining that access to the second communication device has not been successfully completed.

[0033] In one possible design, the method further includes: receiving a response message to the first message, the response message including information about the second resource, or the response message being scrambled based on information about the second resource, the information about the second resource being used to indicate that the response message responds to the first message sent on the second resource.

[0034] Thus, since the response message includes information about the second resource, when multiple T nodes send access request messages on different access resources, even if these multiple T nodes select the same SLSSID, after receiving the response message, these multiple T nodes can determine whether the response message was sent to them based on the information about the second resource in the response message. This avoids multiple T nodes sending Msg3 on the same resource based on the response message, forming a competition relationship and causing access failure.

[0035] In one possible design, the information of the second resource includes at least one of the following: the location information of the period in which the second resource is located; the location information of the time unit in which the second resource is located; and the location information of the second resource.

[0036] Secondly, embodiments of this application provide a communication method, which can be executed by a second communication device. Unless otherwise specified, the "second communication device" in this application can refer to a communication device (e.g., a second terminal device or a G-node), a component of the communication device (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the functions of the communication device. For example, in the method provided in the second aspect, the second communication device sends broadcast information on a first resource, the broadcast information being used for side-by-side synchronization; receives a first message on the second resource, the first message being used to request access to the second communication device; wherein, the second resource is an access resource in a first access resource set, the first access resource set being located after the first resource in the time domain; the first access resource set includes Y access resources located in X periods, each of the X periods including N access resources, Y = X * N, where Y is an integer greater than 1; X is an integer greater than or equal to 1, N is an integer greater than 1; or, X is an integer greater than 1, N is an integer greater than or equal to 1.

[0037] In one possible design, the first message includes a first signal and access information; or, the first message is the first signal; wherein the first signal is generated based on a first SLSSID.

[0038] In one possible design, the time unit in which the N access resources are located in the period is determined based on the time unit in which the first resource is located in the period.

[0039] In one possible design, the index of the time unit in which access resource i is located in the period among the N access resources is Fi, and the index of the time unit in which the first resource is located in the period is FH; Fi = FH + A + T * i, or Fi = (FH + A + T * i) mod L, i = 0, 1, 2, ..., N-1; where L is the number of time units included in each period, and A and T are integers greater than or equal to 0.

[0040] In one possible design, the index of the time unit in which the access resource n in the N access resources is located in the period is Fn, and the index of the time unit in which the first resource is located in the period is FH; Fn = FH + B + (L*n / N), or, Fn = (FH + B + (L*n / N)) mod L, n = 0, 1, 2, ..., N-1; where B is an integer greater than or equal to 0.

[0041] In one possible design, the method further includes: sending a response message to the first message, the response message including information about the second resource, or the response message being scrambled based on information about the second resource, the information about the second resource being used to indicate that the response message responds to the first message sent on the second resource.

[0042] In one possible design, the information of the second resource includes at least one of the following: the location information of the period in which the second resource is located; the location information of the time unit in which the second resource is located; and the location information of the second resource.

[0043] In one possible design, the first resource is located in the second cycle; the first resource is located in one of the first Z time units included in the second cycle, where Z is an integer greater than or equal to 1.

[0044] In one possible design, the first resource is located in a first time unit, which is one of at least one available time unit; the available time unit refers to a time unit that is not occupied by broadcast information or access request messages from other communication devices, and when it is the first time unit, the corresponding access resource is not occupied by broadcast information or access request messages from other communication devices.

[0045] Alternatively, the first resource is located in a first time unit, which is one of at least one available time unit; the available time unit refers to a time unit that is not occupied by broadcast information or access request messages from other communication devices, and the access resource corresponding to the first resource is not occupied by broadcast information or access request messages from other communication devices.

[0046] Thirdly, this application provides a communication device that has the functions involved in the first or second aspect above. For example, the communication device includes modules, units or means corresponding to the operations involved in the first or second aspect above. The functions, units or means can be implemented by software, or by hardware, or by hardware executing corresponding software.

[0047] In one possible design, the communication device includes a processing unit and a communication unit. The communication unit can be used to transmit and receive signals to enable communication between the communication device and other devices. The processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit can correspond to the operations involved in the first or second aspect described above.

[0048] In one possible design, the communication device includes a processor that can be coupled to a memory. The memory can store necessary computer programs or instructions for implementing the functions described in the first or second aspect above. The processor can execute the computer programs or instructions stored in the memory, causing the communication device to implement the methods in any possible design or implementation of the first or second aspect above when the computer programs or instructions are executed.

[0049] In one possible design, the communication device includes a processor and a memory, the memory of which may store the necessary computer programs or instructions for implementing the functions involved in the first or second aspect described above. The processor may execute the computer programs or instructions stored in the memory, and when the computer programs or instructions are executed, cause the communication device to implement the methods in any possible design or implementation of the first or second aspect described above.

[0050] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and to perform the methods in any possible design or implementation of the first or second aspect described above.

[0051] Understandably, in the third aspect described above, the processor can be implemented in hardware or software. When implemented in hardware, the processor can be a logic circuit, integrated circuit, etc.; when implemented in software, the processor can be a general-purpose processor that reads software code stored in memory. Furthermore, there can be one or more processors, and one or more memories. The memory can be integrated with the processor or separated from it. In specific implementations, the memory can be integrated with the processor on the same chip or disposed on different chips. This application does not limit the type of memory or the arrangement of the memory and processor.

[0052] Fourthly, this application provides a communication system, which may include a first communication device and a second communication device; wherein the first communication device is used to perform the method described in the first aspect, and the second communication device is used to perform the method described in the second aspect.

[0053] Fifthly, this application provides a computer-readable storage medium storing a computer program (or computer-readable instructions) in which, when a computer reads and executes some or all of the computer-readable instructions, the method in any of the possible designs in the first or second aspect described above is executed.

[0054] For example, a computer-readable storage medium can be any available medium that a computer can access. This includes, but is not limited to, non-transient computer-readable media, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), CD-ROM or other optical disc storage, magnetic disk storage media, or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer.

[0055] Sixthly, this application provides a computer program product that, when read and executed by a computer, causes the method in any of the possible designs in the first or second aspect to be executed.

[0056] In a seventh aspect, this application provides a chip (or chip system) including a processor coupled to a memory storing a computer program; the processor is configured to invoke part or all of the computer program in the memory, such that the method in any of the possible designs in the first or second aspect described above is executed. Attached Figure Description

[0057] Figure 1(a) is a schematic diagram of the architecture of a communication system applicable to an embodiment of this application;

[0058] Figure 1(b) is a schematic diagram of the architecture of a communication system applicable to an embodiment of this application;

[0059] Figure 1(c) is a schematic diagram of the architecture of a communication system applicable to an embodiment of this application;

[0060] Figure 1(d) is a schematic diagram of the architecture of a communication system applicable to an embodiment of this application;

[0061] Figure 2 is a schematic diagram of a random access procedure provided in an embodiment of this application;

[0062] Figure 3 is a schematic diagram of broadcast information and access request messages provided in an embodiment of this application;

[0063] Figure 4 is a flowchart illustrating the communication method provided in the embodiments of this application;

[0064] Figure 5 is a schematic diagram of the access resources included in the subframe provided in the embodiment of this application;

[0065] Figure 6 is a schematic diagram showing the location of the second resource provided in an embodiment of this application;

[0066] Figure 7 is a flowchart illustrating the communication method provided in Embodiment 1 of this application;

[0067] Figure 8 is a schematic diagram of the access provided in scenario 1 of this application;

[0068] Figure 9 is a flowchart illustrating the communication method provided in Embodiment 2 of this application.

[0069] Figure 10 is a schematic diagram of the access provided in scenario 2 of this application;

[0070] Figure 11 is a flowchart illustrating the communication method provided in Embodiment 3 of this application.

[0071] Figure 12 is a schematic diagram of the access provided in scenario 3 of this application;

[0072] Figure 13 is a flowchart corresponding to the communication method provided in Embodiment 4 of this application;

[0073] Figure 14 is a schematic diagram of the access provided in scenario 4 of this application;

[0074] Figure 15 is a possible exemplary block diagram of the apparatus involved in the embodiments of this application;

[0075] Figure 16 is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Detailed Implementation

[0076] The technical solutions in the embodiments of this application will be described below with reference to the accompanying drawings. The technical solutions provided in the embodiments of this application can be applied to links between devices. These links can be new radio (NR) systems, long-term evolution (LTE) systems, or links in next-generation mobile communication systems or other similar communication systems; no specific limitations are imposed. Of course, these links can also be links in other possible communication systems. For example, the link is a link in a wireless local area network (WLAN), such as a link in an Internet of Things (IoT) network or a Vehicle to X (V2X) network.

[0077] In this application's embodiments, the inter-device link refers to a link established between devices of the same type, such as a device-to-device (D2D) link. A D2D link can also be called a sidelink (SL), direct link, edge link, or secondary link. In this application's embodiments, D2D link, or sidelink, or secondary link all refer to links established between devices of the same type, and their meanings are the same. The so-called "same type of device" can be a link between terminal devices, a link between network devices, or a link between relay nodes, etc., and this application's embodiments do not limit this. For ease of description, the following uses the technical solution provided in this application's embodiments applied to SL as an example.

[0078] Links between terminal devices include D2D links, vehicle-to-everything (V2X) links, and SL-U links. It should be understood that V2X specifically includes direct communication between vehicles (V2V), between vehicles and roadside infrastructure (V2I), and between vehicles and pedestrians (V2P), as well as V2X links between vehicles and networks (V2N) or between vehicles and any entity. V2V refers to communication between vehicles; V2P refers to communication between vehicles and people (including pedestrians, cyclists, drivers, or passengers); V2I refers to communication between vehicles and infrastructure, such as roadside units (RSUs) or network equipment. RSUs include two types: terminal-type RSUs, which are stationary due to their roadside location and do not require consideration of mobility; and base station-type RSUs, which provide timed synchronization and resource scheduling for vehicles communicating with them. V2N refers to communication between vehicles and network devices. In 4G LTE systems, cellular mobile communication standardized unlicensed spectrum, enabling LTE systems to coexist with Wi-Fi devices based on the LBT mechanism, thus enabling LTE Uu interface communication on unlicensed spectrum. In the next-generation 5G NR system, NR Uu interface communication on unlicensed spectrum has been further enhanced, and the related protocol technologies are collectively referred to as NR-U. In addition to the Uu interface mentioned above, there is also a PC5 interface, which is the communication interface between UEs. The transmission link in the PC5 interface is defined as SL. Enabling SL communication on unlicensed spectrum within the local area is an important evolution direction, and the corresponding protocol technologies can be collectively referred to as SL-U. Similar to the Uu interface, UEs operating via SL-U also need to coexist with nearby Wi-Fi devices based on the LBT mechanism.

[0079] In this application embodiment, any device capable of data communication with a base station can be considered a terminal device. Terminal devices are also called terminals, user equipment (UE), mobile stations, or mobile terminals. Terminal devices can be widely used in various scenarios, such as D2D communication, V2X communication, machine-type communication (MTC), IoT, virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, or smart cities. For example, terminal devices can be: mobile phones, computers, mobile internet devices (MID), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, robotic arms, cameras, robots, or smart home devices (such as televisions, air conditioners, robot vacuums, speakers, set-top boxes), relays, customer premises equipment (CPE), etc.

[0080] The various terminal devices described above, if located in a vehicle (e.g., placed inside or installed inside the vehicle), can all be considered in-vehicle terminal devices. In-vehicle terminal devices can be built into a vehicle's in-vehicle module, in-vehicle component, in-vehicle chip, or in-vehicle unit as one or more components or units. The vehicle can implement the methods of this application through the built-in in-vehicle module, in-vehicle component, in-vehicle chip, or in-vehicle unit. In-vehicle terminal devices can be vehicle equipment, in-vehicle modules, vehicles, on-board units (OBU), roadside units (RSU), in-vehicle systems (or in-vehicle transmitting units) (telematics boxes, T-boxes), chips, or systems on chips (SOCs), etc. These chips or SOCs can be installed in the vehicle, OBU, RSU, or T-box. In-vehicle terminal devices may include LTE-V2X communication modules and / or NR-V2X communication modules.

[0081] The terminal device can be located within or outside the coverage area of ​​the network device. Terminal devices within the coverage area can also communicate directly with terminal devices outside the coverage area. For example, Figures 1(a)-1(d) show schematic diagrams of the architecture of various communication systems applicable to embodiments of this application.

[0082] Figure 1(a) illustrates the architecture of a communication system including cellular communication and direct communication between terminal devices. This communication system may include at least one network device and at least two terminal devices. Figure 1(a) shows only one network device and two terminal devices (terminal device 1 and terminal device 2 as shown in Figure 1(a)). The network device can send information to terminal device 1 via a downlink, and terminal device 1 can send information to the network device via an uplink. Terminal device 1 and terminal device 2 can communicate directly via a side link.

[0083] In Figure 1(a), terminal device 1 and terminal device 2 are both shown within the coverage area of ​​the network device. Alternatively, terminal device 1 may be within the coverage area of ​​the network device while terminal device 2 is outside the coverage area of ​​the network device, without limitation.

[0084] Figure 1(b) illustrates the architecture of a communication system including cellular communication and vehicle-to-everything (V2X) communication. This communication system may include at least one network device and at least two terminal devices. Exemplarily, Figure 1(b) shows one network device and three terminal devices, with vehicles (vehicle 1, vehicle 2, and vehicle 3) as examples. The network device can send information to vehicle 1 via a downlink, and vehicle 1 can send information to the network device via an uplink. Vehicle 1 and vehicle 2 can communicate directly via a sidelink, and vehicle 1 and vehicle 3 can also communicate directly via a sidelink.

[0085] In Figure 1(b), vehicle 1 and vehicle 2 are shown within the coverage area of ​​the network device, while vehicle 3 is outside the coverage area of ​​the network device. Alternatively, vehicle 1 may be within the coverage area of ​​the network device, while both vehicle 2 and vehicle 3 are outside the coverage area of ​​the network device, or vehicle 1 and vehicle 3 may be within the coverage area of ​​the network device, while vehicle 2 is outside the coverage area of ​​the network device, without any restrictions.

[0086] The aforementioned cellular communication may include one or more of the following: LTE communication, 5G NR communication, or future mobile communication, without limitation.

[0087] Figure 1(c) illustrates the architecture of a communication system for direct communication between terminal devices. This communication system may include two terminal devices. The two terminal devices can communicate with each other via a side link. Figure 1(c) illustrates an example where one terminal device is an AR, VR, or MR device, and the other is a processing device or a display device.

[0088] Figure 1(d) illustrates the architecture of a communication system incorporating wireless fidelity (WiFi) communication and direct communication. This communication system may include at least one network device and at least two terminal devices. For example, Figure 1(d) shows one network device and three terminal devices (terminal device 1, terminal device 2, and terminal device 3 in Figure 1(d)). In Figure 1(d), the network device is illustrated as a router. The router can send information to terminal device 1 via a downlink, and terminal device 1 can send information to the router via an uplink. Terminal device 1 and terminal device 2 can communicate directly via a side link, and terminal device 1 and terminal device 3 can also communicate directly via a side link.

[0089] The network architecture and application scenarios described in this application are intended to more clearly illustrate the technical solutions of this application and do not constitute a limitation on the technical solutions provided in this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new application scenarios, the technical solutions provided in this application are also applicable to similar technical problems.

[0090] Here, we first explain the terms "period," "subframe," and "symbol" used in the embodiments of this application: period, subframe, and symbol can be understood as different time units or time units. In the sidelink communication scenario, by introducing a period, a unified time reference framework is provided, facilitating the synchronous operation of different devices. The length of the period can be 20 milliseconds (ms), 40 ms, 80 ms, 160 ms, or 320 ms. The period can be replaced with other possible descriptions, such as time period, time range, etc., without specific limitation. A period can include multiple subframes. For example, if the length of a period is 160 ms and the length of a subframe is 1 ms, then a period includes 160 subframes (subframe 0, subframe 1...subframe 159). A subframe can include multiple symbols. For example, a subframe includes 14 symbols. In the embodiments of this application, the time unit, superframe, radio frame, frame, subframe, time slot, symbol, second (s), or millisecond (ms) can be interchanged.

[0091] Based on the above description of the communication system architecture, taking a G node and a T node in a long-distance direct communication scenario as an example, the G node periodically sends broadcast information. After the T node detects the broadcast information of the G node and performs side-by-side synchronization, it can access the system to achieve a series of objectives, including establishing a link with the G node. The random access process illustrated in Figure 2 will be described in detail below. In this embodiment, "random access" can also be replaced with "access". Similarly, "access resources" in this embodiment can be replaced with "candidate access resources".

[0092] It should be understood that the configurations, instructions, pre-configurations, and pre-defined terms in the embodiments of this application can be direct or indirect. For example, an indirect instruction means that this information is determined based on another piece of information. Optionally, selection (or random selection) can also be replaced by determination (or random determination).

[0093] Figure 2 is a schematic diagram of a random access procedure. As shown in Figure 2, it includes the following steps:

[0094] S200, the G node sends a broadcast message. This step can be considered as preparatory work before performing the random access procedure, and is not a step included in the random access procedure.

[0095] Broadcast information is used for side-by-side synchronization, and can also be replaced by broadcast messages. A G node can periodically send broadcast information, and one or more T nodes can receive this broadcast information and perform side-by-side synchronization with the G node, facilitating subsequent access to the G node.

[0096] The periodic broadcasting of information by node G can mean that node G sends a broadcast message once in a subframe (e.g., subframe 2) of each period. For example, as shown in Figure 3, node G sends a broadcast message once in subframe 2 of period n, once in subframe 2 of period n+1, and so on.

[0097] For example, the broadcast information includes information carried on the broadcast channel and a synchronization signal block (SS), which includes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). Optionally, the information carried on the broadcast channel may also be referred to as a communication domain basic message or broadcast information bits. Optionally, the broadcast channel may be, for example, a physical sidelink broadcast channel (PSBCH). Optionally, the primary synchronization signal and the secondary synchronization signal may also be referred to as the first training signal (FTS) and the second training signal (STS), respectively. For example, referring to Figure 3, B in Figure 3 represents PSBCH, P represents PSS, and S represents SSS; in the time domain, the broadcast information (i.e., PSBCH / PSS / SSS) occupies the first 13 symbols of subframe 2, and the last symbol of subframe 2 is the guard interval; in the frequency domain, the broadcast information occupies 6 resource blocks (RBs) at the center frequency of the system bandwidth.

[0098] Furthermore, the information carried in the PSBCH may include the identifier of the G node and the sidelink synchronization signal identifier (i.e., SLSSID) selected by the G node. Optionally, the SLSSID may also be called the training signal ID (TSID). The aforementioned PSS / SSS may be generated based on the SLSSID selected by the G node. Optionally, the value range of the SLSSID is [0, D]. The G node can randomly select an SLSSID from [C+1, D], and the T node can randomly select an SLSSID from [0, C]. Optionally, the values ​​of C and D may be indications, configurations, pre-configurations, or predefined. For example, the value range of the SLSSID is [0, 167]. The G node can randomly select an SLSSID from [157, 167], and the T node can randomly select an SLSSID from [0, 156], that is, the range of SLSSIDs selected by the G node and the T node is different.

[0099] S201, Node T sends an access request message, which is used to request access to Node G. This access request message can be referred to as the first message of the random access procedure, message 1 (Msg1), an access signal, or access information.

[0100] For example, after the physical layer of node T receives the indication information sent by the higher layer of node T (the indication information is used to indicate access to node G, i.e., the indication information is the information indicating the sending of Msg1), it can send an access request message in the next subframe (such as subframe 3) after the subframe where the broadcast information is located. The higher layer of node T can send the indication information to the physical layer of node T after determining that the preparatory work before access is completed (such as side-link synchronization with node G). This embodiment of the application does not limit the specific timing of the higher layer of node T sending the indication information. For example, the higher layer can be a layer above the physical layer, such as the radio link control (RLC) layer, media access control (MAC) layer, or radio resource control (RRC) layer, and is not specifically limited.

[0101] For example, node T receives broadcast information on subframe 2 of period n and performs side-by-side synchronization with node G; at a certain time point in period n (for example, this time point is in subframe 120 of period n), the physical layer of node T receives indication information sent by the higher layer of node T, and then the physical layer of node T can send an access request message on subframe 3 of period n+1.

[0102] The access request message includes access information and signals. Signals may include a PSS and an SSS, which can be generated based on the SLSSID selected by the T node. The access information is scrambled based on the SLSSID selected by the T node. The access information includes the identifier of the G node requesting access. For example, referring to Figure 3, where A represents access information, in the time domain, the access request message occupies the first 13 symbols of subframe 3, and the last symbol of subframe 3 is the guard interval; in the frequency domain, the access request message occupies 6 RBs at the center frequency of the system bandwidth.

[0103] S202, after detecting the access request message sent by node T, node G sends a response message to node T. This response message can be referred to as message 2 or message 2 (Msg2) of the random access procedure.

[0104] For example, after parsing the access request message, if node G determines that the identifier of node G carried in the access request message is its own identifier, it can send a response message to node T. The response message may include resource information, and may also include other possible information, without specific limitations.

[0105] In other examples, if a G node determines that the identifier of the G node carried in the access request message is not its own identifier, it can ignore the access request message, for example, by not sending a response message.

[0106] S203, Node T sends Message 3 or Message 3 (Msg3) of the Random Access Procedure to Node G on the resource indicated by the resource information in the response message.

[0107] In step S204, node G sends a contention resolution message to node T. Correspondingly, node T can receive the contention resolution message from node G. If the contention resolution message indicates that the random access conflict has been won, then random access is considered successful; otherwise, node T determines that random access has failed. This contention resolution message can be referred to as message 4 or message 4 (Msg4) in the random access procedure.

[0108] It is understood that the random access process shown in Figure 2 above is only one possible process example, and the embodiments of this application do not limit it.

[0109] As described in Figure 2, T nodes send access request messages in the subframe following the subframe containing the broadcast information. Each T node randomly selects an SLSSID within a certain range and scrambles the access information based on this SLSSID, generating a PSS / SSS. Therefore, different T nodes may select the same SLSSID and / or different T nodes may send Msg1 in the same subframe, leading to collisions or conflicts between different T nodes and affecting their access. In particular, when there are many T nodes, the probability of collisions increases, resulting in long access times, low access efficiency, poor access experience, and high power consumption.

[0110] Based on this, embodiments of this application provide a communication method, apparatus, and system that selects one access resource from Y access resources in X cycles to send a first message (such as Msg1), thereby reducing the probability of collisions when different T nodes send the first message on the same access resource and improving the efficiency of random access.

[0111] The communication method provided in this application is described below with reference to specific embodiments. The communication method provided in this application involves a first communication device and a second communication device. For example, the first communication device is a first terminal device (such as a T-node) or a component within the first terminal device, such as a processor, chip (such as a baseband chip), or chip system disposed within the terminal device; the second communication device is a second terminal device (such as a G-node) or a component within the second terminal device, such as a processor, chip, or chip system disposed within the second terminal device. In this application, the example of "the first communication device being a T-node and the second communication device being a G-node" is used for description.

[0112] In this embodiment, "send" and "receive" indicate the direction of signal transmission. "Send" can also be understood as the "output" of the chip interface, and "receive" can be understood as the "input" of the chip interface. In other words, "send" or "receive" can occur between devices, such as between a network device and a terminal device via an air interface. "Send" or "receive" can also occur within a device, such as between components, modules, chips, software modules, or hardware modules within the device via a bus, wiring, or interface.

[0113] Figure 4 is a flowchart illustrating the communication method provided in this application embodiment. As shown in Figure 4, the method may include:

[0114] S401, Node G sends a broadcast message on the first resource; correspondingly, Node T receives the broadcast message on the first resource, and the broadcast message is used for side synchronization.

[0115] Here, the first resource is a broadcast resource of node G. For example, the first resource is located in subframe 2 of period n, specifically, the first resource includes the first 13 symbols in subframe 2 of period n. Optionally, the position of the first resource in each period can be called indicator1.

[0116] Optionally, the G node can send broadcast information on multiple time units in each cycle.

[0117] S402, Node T sends a first message on the second resource. The first message is used to request access to Node G. For example, the first message is an access request message or Msg1.

[0118] (1) Introduce the first message.

[0119] As one possible implementation, the first message includes a first signal and access information. The first signal is generated based on a first SLSSID, which may include a PSS and / or an SSS. The first SLSSID is an SLSSID randomly selected by the T node from a preset range. For example, the preset range is [0, 156]. The access information may be scrambled based on the first SLSSID. For example, the access information may be scrambled based on a first scrambling value, which is obtained based on the first SLSSID, or the first scrambling value corresponds to or is associated with the first SLSSID. The access information may include the identifier of the G node requesting access.

[0120] As another possible implementation, the first message is the first signal, as described above. That is, the first message only includes the first signal and does not carry the identifier of the G node requesting access. In this case, the first message can occupy 4 symbols.

[0121] On the one hand, considering that in some scenarios (such as emergency rescue scenarios), it is necessary for node T to connect to node G in a timely manner, without specifying which specific node G to connect to, the access request message does not need to carry the identifier of the node G to which it is requesting access.

[0122] On the other hand, access information is scrambled based on SLSSID. Because the scrambled information differs, for one T-node, the access information from other T-nodes is interference (approximately constant Gaussian white noise after descrambling, leading to a decrease in the signal-to-interference-plus-noise ratio (SINR), causing demodulation failure at the G-node). Typically, PSS / SSS generated by different SLSSIDs are orthogonal. Even if PSS / SSS generated by different SLSSIDs are superimposed (e.g., occupying the same resources), the G-node can still successfully detect PSS / SSS generated by different SLSSIDs. Therefore, when the access request message includes access information and a signal, if node T sends access request message a1 (including access information a1 and signal a1) on the second resource at the same time, and other nodes T send access request message a2 (including access information a2 and signal a2) on the same resource, then regardless of whether node T and other nodes T select the same SLSSID, node G will fail to demodulate. However, when the access request message is a signal, if node T sends access request message b1 (i.e., signal b1) on the second resource at the same time, and other nodes T send access request message b2 (i.e., signal b2) on the same resource, then even if node T and other nodes T select different SLSSIDs, node G can successfully detect access request messages b1 and b2. That is, when the access request message does not carry the identifier of the requesting node G, it can effectively reduce the problem of collisions between different nodes T selecting different SLSSIDs on the same access resource.

[0123] (2) Introduce the second resource.

[0124] The second resource is one of the access resources in the first access resource set, which is located after the first resource in the time domain (this can be understood as the access resources included in the first access resource set being located after the first resource in the time domain). The access resources in the first access resource set can also be called candidate access resources, and the first access resource set can also be called a candidate access resource set; similar considerations can be found here. The first access resource set includes Y access resources located in X periods, and each of the X periods includes N access resources, where Y = X * N, and Y is an integer greater than 1. X is an integer greater than or equal to 1, and N is an integer greater than 1; or, X is an integer greater than 1, and N is an integer greater than or equal to 1. In the embodiments of this application, "X periods" can refer to X consecutive periods.

[0125] Each period includes N access resources, which can mean that each period includes N1 subframes, and each subframe includes N2 access resources, i.e., N = N1 * N2. The value of N1 can be 1, 2, 4, 8, or 16, and the value of N2 can be 1, 2, or 3. When the access request message is a signal, it occupies 4 symbols. For example, if N2 is 1, then one subframe includes one access resource, which can include symbols 1, 2, 11, and 12 in the subframe, as shown in Figure 5(a). As another example, if N2 is 2, then one subframe includes two access resources, one of which can include symbols 0 to 3 in the subframe, and the other can include symbols 7 to 10 in the subframe, as shown in Figure 5(b). For example, N2 is 3, meaning a subframe includes 3 access resources. The first access resource may include symbols 0 to 3 in the subframe, the second access resource may include symbols 4 to 7 in the subframe, and the third access resource may include symbols 8 to 11 in the subframe, as shown in Figure 5(c). It can be understood that when N2 is 1 (i.e., a subframe includes one access resource), N = N1. This embodiment uses an N2 value of 1 as an example for description.

[0126] For example, the values ​​of Y, X, and N (or N1, N2) can be indicated or configured by the G node. For instance, the G node can indicate or configure the values ​​of Y, X, and N (or N1, N2) through broadcast information or system messages (such as system information blocks (SIBs)). Alternatively, the values ​​of Y, X, and N (or N1, N2) can also be pre-configured or pre-defined. For example, the values ​​of Y, X, and N can all be indicated or configured by the G node, or the values ​​of Y, X, and N can all be pre-configured or pre-defined, or the value of Y can be pre-configured or pre-defined, and the values ​​of X and N can all be indicated or configured by the G node; that is, the methods for determining the values ​​of Y, X, and N can be independent of each other.

[0127] Optionally, the position of the second resource in the period can be referred to as indicator2. Optionally, indicator2 is a random value from 0 to N-1, that is, the resource corresponding to indicator2 is one of the N access resources in the period.

[0128] Optionally, the higher layers of node T can indicate the location of the first resource and / or the location of the second resource to the physical layer of node T. Taking the higher layers of node T indicating the location of the second resource to the physical layer of node T as an example, there are several specific indication methods. For example, the higher layers of node T send information indicating the second resource to the physical layer of node T. The information indicating the second resource includes at least one of the following ①②③:

[0129] ① Location information of the period in which the second resource is located. For example, the location information of the period in which the second resource is located includes the index of the period in which the second resource is located within X periods. Optionally, this index can be an ascending index or a descending index. For example, the X periods include periods n+1 to n+4, the period in which the second resource is located is period n+2, and the location information of the period in which the second resource is located includes 2 bits. When using an ascending index, the index of the period in which the second resource is located within X periods is 01; when using a descending index, the index of the period in which the second resource is located within X periods is 10.

[0130] ② The location information of the subframe where the second resource is located. For example, the location information of the subframe where the second resource is located includes: the index of the subframe where the second resource is located in X*N1 subframes, where X*N1 subframes refer to the X*N1 subframes in X periods used to send access request messages; or, the index of the subframe where the second resource is located in N1 subframes in the period where the second resource is located; or, the index of the subframe where the second resource is located in the period where the second resource is located (for example, if the period where the second resource is located includes 160 subframes, then it is: the index of the subframe where the second resource is located in these 160 subframes. Optionally, the specific determination method can refer to (3) the relationship between the first resource and N access resources), and the period where the second period is located can refer to the description in ①. Optionally, the index involved here can be an ascending index or a descending index, and can refer to the description of ascending index or descending index in "the index of the period where the second resource is located in X periods".

[0131] ③ Location information of the second resource. For example, the location information of the second resource includes: the index of the second resource among Y access resources in X periods; or, the index of the second resource among N1*N2 access resources in the period where the second resource is located; or, the index of the second resource among N2 access resources in the subframe where the second resource is located. The period in which the second period is located can be referred to in ①, and the subframe in which the second resource is located can be referred to in ②.

[0132] Optionally, the higher layers of node T can determine the location of the second resource in various ways. For example, the higher layers of node T may randomly determine the period in which the second resource is located from X periods, for example, randomly determining the period in which the second resource is located from [0, X-1]; and / or, the higher layers of node T may randomly determine the subframe in which the second resource is located from X*N1 subframes in X periods, or the higher layers of node T may randomly determine the subframe in which the second resource is located from N1 subframes in the period in which the second resource is located; and / or, the higher layers of node T may randomly determine the second resource from Y access resources in X periods, or the higher layers of node T may randomly determine the second resource from N1*N2 access resources in the period in which the second resource is located, or the higher layers of node T may randomly determine the second resource from N2 access resources in the subframe in which the second period is located.

[0133] Thus, since node T selects one access resource from Y access resources in X periods to send the first message (such as Msg1), compared to the scheme where node T sends the first message in the next subframe after the subframe where the broadcast information is located, it is easier to reduce the probability of collisions when different nodes send access request messages on the same access resource, thereby improving the efficiency of random access.

[0134] (3) The relationship between the first resource and the N access resources is introduced.

[0135] For example, the subframe in which the N access resources are located in the period can be determined based on the subframe in which the first resource is located in the period; or, the subframe in which the N access resources are located in the period is associated with or corresponds to the subframe in which the first resource is located in the period.

[0136] For example, let Fi be the index of the subframe containing access resource i in a period of N access resources, and FH be the index of the subframe containing the first resource in the period; Fi = FH + A + T*i, i = 0, 1, 2, ..., N-1; where A and T are integers greater than or equal to 0. Taking "the index of the subframe containing the first resource in the period" as an example (other similar descriptions can be referred to), the index of the subframe containing the first resource in the period refers to the index of the subframe containing the first resource in the period containing the first resource. For example, if the period containing the first resource includes 160 subframes, then FH is the index of the subframe containing the first resource in these 160 subframes.

[0137] For example, if the first resource is located in subframe 2 (i.e., FH=2), A=1, and T=20 in the period, then the index F0 of the subframe where access resource 0 is located in the period is 2+1+20*0=3 (i.e., the subframe where access resource 0 is located is subframe 3 in the period), and the index F0 of the subframe where access resource 1 is located in the period is 2+1+20*1=23 (i.e., the subframe where access resource 1 is located is subframe 23 in the period), and so on.

[0138] Optionally, when N=2, A=1, T=80; when N=4, A=1, T=40; when N=8, A=1, T=20. That is, when N=2, the positions of the N access resources are indicator1+1, indicator1+81; when N=4, the positions of the N access resources are indicator1+1, indicator1+41, indicator1+81, indicator1+121; when N=8, the positions of the N access resources are indicator1+1, indicator1+21, indicator1+41, indicator1+61, indicator1+81, indicator1+101, indicator1+121, indicator1+141.

[0139] For example, let Fi be the index of the subframe in which access resource i is located in a period among N access resources, and let FH be the index of the subframe in which the first resource is located in a period; Fi = (FH + A + T * i) mod L, i = 0, 1, 2, ..., N-1; where L is the number of subframes included in each period, and A and T are integers greater than or equal to 0. For example, L = 160.

[0140] Optionally, when N=2, A=1, T=80; when N=4, A=1, T=40; when N=8, A=1, T=20. That is, when N=2, the positions of the N access resources are (indicator1+1)mod L, (indicator1+81)mod L; when N=4, the positions of the N access resources are (indicator1+1)mod L, (indicator1+41)mod L, (indicator1+81)mod L, (indicator1+121)mod L; when N=8, the positions of the N access resources are (indicator1+1)mod L, (indicator1+21)mod L, (indicator1+41)mod L, (indicator1+61)mod L, (indicator1+81)mod L, (indicator1+101)mod L, (indicator1+121)mod L, (indicator1+141)mod L.

[0141] For example, the index of the subframe in which access resource n is located in the period among N access resources is Fn, and the index of the subframe in which the first resource is located in the period is FH; Fn=FH+B+(L*n / N), n=0,1,2,……N-1; where B is an integer greater than or equal to 0.

[0142] Optionally, B = 1. That is, when N = 2, the positions of the N access resources are indicator1+1, indicator1+81; when N = 4, the positions of the N access resources are indicator1+1, indicator1+41, indicator1+81, indicator1+121; when N = 8, the positions of the N access resources are indicator1+1, indicator1+21, indicator1+41, indicator1+61, indicator1+81, indicator1+101, indicator1+121, indicator1+141.

[0143] For example, the index of the subframe in which access resource n is located in the period among N access resources is Fn, and the index of the subframe in which the first resource is located in the period is FH; Fn = (FH + B + (L*n / N)) mod L, n = 0, 1, 2, ..., N-1; where B is an integer greater than or equal to 0.

[0144] Optionally, B = 1. That is, when N = 2, the positions of the N access resources are (indicator1+1)mod L, (indicator1+81)mod L; when N = 4, the positions of the N access resources are (indicator1+1)mod L, (indicator1+41)mod L, (indicator1+81)mod L, (indicator1+121)mod L; when N = 8, the positions of the N access resources are (indicator1+1)mod L, (indicator1+21)mod L, (indicator1+41)mod L, (indicator1+61)mod L, (indicator1+81)mod L, (indicator1+101)mod L, (indicator1+121)mod L, (indicator1+141)mod L.

[0145] (4) Introduce the subframe in which the first resource is located in the cycle.

[0146] As one possible implementation, the G node can randomly select a subframe from the multiple subframes included in a period (assuming a period includes Z' subframes, then the multiple subframes here are subframe 0, subframe 1... subframe Z'-1, that is, the selection range is [0, Z'-1]). For example, the selected subframe is subframe 2 (that is, the subframe in which the first resource is located in the period is subframe 2).

[0147] As another possible implementation, the G node can randomly select a subframe from the first Z subframes included in the period (the first Z subframes are subframe 0, subframe 1... subframe Z-1, i.e., the selection range is [0, Z-1]), where Z is an integer greater than or equal to 1 and less than Z'. For example, Z' = 160, and Z can be an integer greater than or equal to 1 and less than 160. The value of Z or Z-1 can be configured, pre-configured, or predefined, without any specific limitation.

[0148] Regarding the two implementations mentioned above, taking the example of the G node randomly selecting a subframe from [0, Z-1] (the implementation of "the G node randomly selecting a subframe from [0, Z'-1]" can be referred to), one specific implementation is as follows: The G node first determines at least one available subframe from subframe 0 to subframe Z-1, and then randomly selects one available subframe from the at least one available subframe. Here, an available subframe refers to a subframe that is not occupied by broadcast information or access request messages from other nodes, and when used as a broadcast resource, the corresponding access resource is not occupied by broadcast information or access request messages from other nodes. For example, after powering on, the G node can first perform monitoring within one or more periods, and determine the subframes occupied by broadcast information and access request messages from other nodes based on the monitoring results, thereby determining at least one available subframe from subframe 0 to subframe Z-1.

[0149] For example, Z=7, meaning the selection range is subframes 0 to 6. Node G, through monitoring, determines that broadcast information from other nodes occupies subframes 0 and 4. According to the formula (Fi=FH+A+T*i), the subframe containing the access resource corresponding to subframe 0 includes subframe 1, and the subframe containing the access resource corresponding to subframe 4 includes subframe 5. Therefore, subframes 0, 1, 4, and 5 are occupied by broadcast information and access request messages from other nodes. Regarding subframe 3, when it is a broadcast resource, according to the formula (Fi=FH+A+T*i), the subframe containing the access resource corresponding to subframe 3 includes subframe 4. However, subframe 4 is already occupied by broadcast information from other nodes. Therefore, the available subframes that meet the conditions include subframes 2 and 6, and Node G can randomly select one subframe from subframes 2 and 6. It is understood that the above description can also be referenced when determining the second resource based on the first resource using other protection methods or formulas.

[0150] Thus, by randomly selecting an available subframe from at least one available subframe as the subframe containing the broadcast resource, broadcast resources of different G nodes can correspond to different access resources. For example, broadcast resources of G node 1 correspond to A1 access resources, and broadcast resources of G node 2 correspond to A2 access resources. Since access resources A1 and A2 do not overlap, G node 1 can detect access request messages on access resources A1, and G node 2 can detect access request messages on access resources A2. When node T requests access to G node 1, node T sends an access request message on the access resources within A1. When node T requests access to G node 2, node T sends an access request message on the access resources within A2. Therefore, even if the access request message sent by node T does not carry the identifier of the G node requesting access, node T can still access the corresponding G node.

[0151] Optionally, the above method further includes:

[0152] S403, node G sends a response message to node T for the first message, and node T receives the response message for the first message accordingly.

[0153] For example, the response message includes a first SLSSID, or the response message is scrambled based on the first SLSSID, the first SLSSID indicating that the response message responds to a first message sent based on the first SLSSID. And / or, the response message includes information about a second resource, or the response message is scrambled based on information about a second resource, the information about the second resource indicating that the response message responds to a first message sent on the second resource. Wherein, scrambling the response message based on information about the second resource can mean that the response message is scrambled based on a second scrambling value, the second scrambling value being obtained based on the information about the second resource.

[0154] The information of the second resource includes at least one of the following ①②③:

[0155] ① Location information of the period in which the second resource is located. For example, if the period in which the second resource is located is period n+1, the location information of period n+1 can be an index of period n+1. This index can be an absolute index; or it can be a relative index. A relative index can refer to a backward or forward index with the period in which the response message is located as the reference point. It can be understood that with the period in which the response message is located as the reference point, a backward index means that the index of a period closer to the period in which the response message is located is smaller. Optionally, the period of the index includes the period in which the response message is located, that is, the period corresponding to index 0 is the period in which the response message is located; or, the period of the index does not include the period in which the response message is located, that is, the period corresponding to index 0 is the previous period in which the response message is located. With the period in which the response message is located as the reference point, a forward index means that the index of a period farther from the period in which the response message is located is smaller. Optionally, the index period includes the period in which the response message is located, meaning the period corresponding to the largest index that the location information of the period in which the second resource is located corresponds to the period in which the response message is located. Alternatively, the index period does not include the period in which the response message is located, meaning the period corresponding to the largest index that the location information of the period in which the second resource is located corresponds to the period preceding the period in which the response message is located. Optionally, a forward-reverse index can also refer to an index from back to front, or the index can be sorted in descending order according to temporal chronology. Optionally, a forward-forward index can also refer to an index from front to back, or the index can be sorted in ascending order according to temporal chronology. For the case of a relative index, for example, if the location information of the period in which the second resource is located includes 2 bits, which can indicate a range of 4 periods, then it can indicate the relative index of the period in which the second resource is located within the 4 periods. For example, if the period in which the response message is located is period n+3, then the location information of period n+1 can be 10 (forward-reverse index), or the location information of period n+1 can be 01 (forward-forward index).

[0156] ② The location information of the subframe where the second resource is located. For example, if the subframe where the second resource is located is subframe x, the location information of subframe x can be its index. The index of subframe x can be an absolute index; or it can be a relative index. A relative index can refer to a backward or forward index with the subframe where the response message is located as the reference point; or it can be the index of subframe x within the period. It can be understood that with the subframe where the response message is located as the reference point, a backward index means that the index of a subframe closer to the subframe where the response message is located is smaller. Optionally, the indexed subframe does not include the subframe where the response message is located, that is, the subframe corresponding to index 0 is the previous subframe used to send access information. With the subframe where the response message is located as the reference point, a forward index means that the index of a subframe farther from the subframe where the response message is located is smaller. Optionally, the subframe corresponding to the largest index indicated by the location information of the subframe where the second resource is located is the previous subframe used to send access information. Optionally, a forward reverse index can also refer to an index from back to front, or the index can be sorted in descending order according to temporal sequence. Optionally, a forward ascending index can also refer to an index from front to back, or the index can be sorted in ascending order according to temporal sequence. For example, the position information of the subframe containing the second resource can also be used to indicate the index of the subframe containing the second resource within the period containing the second resource. Specific descriptions can be found above and will not be repeated here. Optionally, the position information of the period containing the second resource can be determined according to method ①.

[0157] ③ Location information of the second resource. For example, the location information of the second resource can be an index of the second resource. This index can be a relative index, which can refer to a backward or forward index with the resource where the response message is located as the reference point. It can be understood that a backward index with the resource where the response message is located as the reference point means that the closer the resource is to the resource where the response message is located, the smaller the index. Optionally, the indexed resource does not include the resource where the response message is located; that is, the resource corresponding to index 0 is the resource preceding the resource where the response message is located that was used to send access information. It can be understood that a forward index with the resource where the response message is located as the reference point means that the farther the resource is from the resource where the response message is located, the smaller the index. Optionally, the resource corresponding to the largest index indicated by the location information of the second resource is the resource preceding the resource where the response message is located that was used to send access information. Optionally, a backward index can also refer to an index from back to front, or the index can be sorted from largest to smallest according to temporal order. Optionally, a forward index can also refer to an index from front to back, or the index can be sorted from smallest to largest according to temporal order. Optionally, the location information of the second resource includes 3 bits, which can indicate the index of the second resource among the first 8 resources of the resource containing the response message. For example, when the location information of the second resource includes 3 bits, it can indicate a range of 8 access resources, as shown in Figure 6. The location information of the second resource can be 100 (reverse forward index) or 011 (forward forward index). For example, the location information of the resource containing the second resource can also be used to indicate the index of the second resource in the period containing the second resource, or to indicate the index of the second resource in the subframe containing the second resource. Specific descriptions can be found above and will not be repeated here. Optionally, the location information of the period containing the second resource can be determined according to method ①, and the location information of the subframe containing the second resource can be determined according to method ②. It is understood that when N2 is 1, the location information of the subframe containing the second resource and the location information of the second resource can be equivalent.

[0158] Thus, since the response message includes the first SLSSID (or the response message is scrambled based on the first SLSSID), when multiple T nodes select different SLSSIDs, even if these multiple T nodes send access request messages on the same access resource (or adjacent access resources), after all multiple T nodes receive the response message, they can also determine whether the response message was sent to themselves based on the first SLSSID in the response message. This avoids multiple T nodes sending Msg3 on the same resource based on the response message, forming a competition relationship and causing access failure.

[0159] Since the response message includes information about the second resource, when multiple T nodes send access request messages on different access resources, even if these multiple T nodes select the same SLSSID, after receiving the response message, these multiple T nodes can determine whether the response message was sent to them based on the information about the second resource in the response message. This avoids multiple T nodes sending Msg3 on the same resource based on the response message, forming a competition relationship and causing access failure.

[0160] In other words, by carrying the first SLSSID (or the response message is scrambled based on the first SLSSID) and / or the information of the second resource in the response message, different T nodes can accurately determine whether the response message is sent to them, thereby avoiding Msg3 collisions and improving access efficiency.

[0161] Based on the above description, in order to successfully connect to node G, node T can attempt to connect multiple times (i.e., send multiple access request messages). Several possible implementations are described below in conjunction with scenarios 1 to 4.

[0162] (1) Case 1

[0163] Figure 7 is a flowchart illustrating the communication method provided in Embodiment 1 of this application. As shown in Figure 7, the method may include:

[0164] S701, the G node sends a broadcast message on the first resource; correspondingly, the T node receives the broadcast message on the first resource, and the broadcast message is used for side synchronization.

[0165] The specific implementation of S701 can be found in the description of S401.

[0166] S702, Node T sends a second message on the third resource. The second message is used to request access to Node G; that is, the second message is an access request message. The third resource is located after the first resource in the time domain.

[0167] (1) Introduce the second message.

[0168] As one possible implementation, the second message includes a second signal and access information. The second signal is generated based on a second SLSSID, which may include a PSS and / or an SSS. The second SLSSID is an SLSSID randomly selected by the T node from a preset range, such as [0, 156]. The access information can be scrambled based on the second SLSSID, as described in the first message description, and will not be repeated here.

[0169] As another possible implementation, the second message is a second signal, as described above. That is to say, the second message does not carry access information.

[0170] (2) Introduce the third resource.

[0171] For example, after receiving indication information from the higher layer of node T (the indication information is used to indicate access to node G, that is, the indication information is the information indicating the sending of Msg1), the physical layer of node T can determine the third resource and send the second message on the third resource.

[0172] Optionally, the information instructing the transmission of Msg1 includes one or more of the following: Msg1 transmission trigger information, the location of the first resource, and the location of the third resource. Optionally, the higher layer instructing the physical layer to transmit Msg1 can be a direct or indirect instruction. For example, transmitting Msg1 directly instructs the physical layer to transmit Msg1 via a Msg1 transmission trigger information. Another example is indirectly instructing the physical layer to transmit Msg1 by indicating the location of the first resource and / or the location of the third resource.

[0173] As one possible implementation, the third resource is the nearest access resource after receiving the indication information. For example, continuing the previous example, the first resource is located in subframe 2 of period n, and the access resources corresponding to the first resource are located in subframe 3, subframe 23...subframe 143; the physical layer of node T receives the indication information at subframe 120 of period n, then the nearest access resource after receiving the indication information is the access resource in subframe 123 of period n, that is, the third resource is located in subframe 123 of period n.

[0174] As another possible implementation, the third resource is the first access resource in the first cycle, or the third resource is randomly determined from the access resources in the first cycle, where the first cycle is the most recent cycle after receiving the indication information. For example, following the previous example, the first resource is located in subframe 2 of cycle n, and the access resources corresponding to the first resource are located in subframe 3, subframe 23...subframe 143; the physical layer of node T receives the indication information at subframe 140 of cycle n, and the most recent cycle after receiving the indication information is cycle n+1, that is, the first cycle is cycle n+1.

[0175] As another possible implementation, the third resource is randomly determined from the access resources located after receiving the indication information in the first period, where the first period is the period of receiving the indication information. For example, following the previous example, the first resource is located in subframe 2 of period n, and the access resources corresponding to the first resource are located in subframe 3, subframe 23...subframe 143; the time point at which the physical layer of node T receives the indication information is located in subframe 120 of period n, then the first period is period n, and the access resources located after receiving the indication information in the first period are located in subframe 123 and 143.

[0176] Optionally, the location of the third resource can be determined by the physical layer, or based on instructions from higher layers. See the description of the second resource for details.

[0177] Thus, after receiving the instruction from the higher layer, the physical layer of node T first attempts to send an access request message on a nearby resource (i.e., the third resource) in order to access node G as soon as possible.

[0178] S703, Node T sends a first message on the second resource. The first message is used to request access to Node G.

[0179] The specific implementation of S703 can be referred to S402. As mentioned above, the second resource is an access resource in the first access resource set, which includes Y access resources located in X periods.

[0180] Optionally, the first of the X cycles is the cycle following the first cycle in which the third resource is located.

[0181] For example, if node T determines that access has failed before sending the first message on the second resource, it may send the first message on the second resource. That is, if node T receives a response message to the second message or determines that access to node G has been successful (e.g., receiving Msg4 and determining successful access based on Msg4) before sending the first message on the second resource, it may not send the first message on the second resource; or, if node T's physical layer receives an instruction from a higher layer to stop access before sending the first message on the second resource, node T's physical layer may not send the first message on the second resource. Optionally, the position of the second resource among the Y access resources is determined by the physical layer.

[0182] Optionally, unsuccessful access can be understood as not receiving the response message of the second message, or failing to successfully access the G node, or the physical layer not receiving an instruction from the higher layer to stop access. Optionally, if the higher layer receives the response message of the second message before the first timer expires, or successfully accesses the G node, it will send an instruction to the physical layer to stop access. Optionally, the length of the first timer represents the maximum time to wait for Msg2 after Msg1 has been sent, or the maximum time to wait for Msg2 after the higher layer instructs the physical layer to send Msg1. Optionally, the length of the first timer is pre-configured or predefined. For example, 160ms or 320ms. Optionally, the first timer can also be a first duration or a first time period.

[0183] S704, Node T sends a third message on the fourth resource, while the first message is used to request access to Node G.

[0184] (1) Introduce the third message.

[0185] As one possible implementation, the third message includes a third signal and access information. The third signal is generated based on a third SLSSID, which may include a PSS and / or an SSS. The third SLSSID is an SLSSID randomly selected by the T node from a preset range, such as [0, 156]. The access information can be scrambled based on the third SLSSID, as described in the first message description, and will not be repeated here.

[0186] As another possible implementation, the third message is a third signal, as described above. That is to say, the third message does not carry access information.

[0187] (2) Introduce the fourth resource.

[0188] The fourth resource is one of the access resources in the second access resource set. The second access resource set includes V access resources located in P cycles. Each of the P cycles includes N access resources, where V = P * N. The first cycle of the P cycles is the cycle following the last cycle of the X cycles, where P is an integer greater than or equal to X. In the embodiments of this application, "P cycles" can refer to P consecutive cycles.

[0189] Implementation Method 1: The number of random periods remains constant (i.e., P = X, V = Y), and the number of random periods is the number of periods in which the access resources in the access resource set are located. In other words, after sending the second message, node T selects an access resource from the Y access resources in X periods each time, and sends an access request message on the selected access resource.

[0190] For example, assuming X=2 and N=2, as shown in Figure 8(a), node T receives broadcast information on the first resource in period n. At a certain time point in period n, the physical layer of node T receives an instruction from the higher layer of node T and sends a second message on the third resource in period n. Node T selects an access resource from the first access resource set (which includes two access resources in period n+1 and two access resources in period n+2), and the selected access resource is the second resource. Node T then sends a first message on the second resource. Node T selects an access resource from the second access resource set (which includes two access resources in period n+3 and two access resources in period n+4), and the selected access resource is the fourth resource. Node T then sends a third message on the fourth resource. This process continues until Msg2 is received or access is successful.

[0191] Implementation Method 2: The number of random cycles continuously increases. For example, the value of P can be determined based on the number of random access cycles in the previous instance (i.e., the value of X) and the first set (or first sequence). The first set can include multiple values. The first set can be configured by node G to node T, or it can be pre-configured or predefined. For example, X is the first value in the first set. a) If the first value is not the largest value in the first set, then P is the next value greater than X, and so on. Optionally, when the number of random cycles X reaches the maximum value in the first set, access can be re-initiated, i.e., the steps of this invention can be re-executed; or, access can continue to be attempted with the number of random cycles as the maximum value, i.e., P = X, until Msg2 is received or access is successful. b) If the first value is the maximum value in the first set, then P equals X. Optionally, node T can continue to attempt access with the number of random cycles as the maximum value until Msg2 is received or access is successful.

[0192] For example, suppose X = 2, N = 2, and the first set is {2, 4, 8}. As shown in Figure 8(b), node T receives broadcast information on the first resource in period n. At a certain time point in period n, the physical layer of node T receives instruction information from the higher layer of node T and sends a second message on the third resource in period n. Node T selects an access resource from the first access resource set (which includes 2 access resources in period n+1 and 2 access resources in period n+2), and the selected access resource is the second resource. Node T then sends a first message on the second resource. Node T selects an access resource from the second access resource set (which includes 8 access resources from period n+3 to period n+6), and the selected access resource is the fourth resource. Node T then sends a third message on the fourth resource. And so on.

[0193] For example, whether to use implementation method 1 or implementation method 2 can be indicated by node G. That is, node G can indicate to node T that the number of random cycles is fixed or continuously increasing. There are various specific indication methods. For example, information 'a' can be carried in broadcast information or system messages. Information 'a' is used to indicate whether the number of random cycles is fixed or continuously increasing. For example, if the first set is {2,4,8}, then information 'a' can include 2 bits: 00 indicates that the number of random cycles increases according to the first set {2,4,8}, i.e., implementation method 2 is used; 01 indicates that the number of random cycles is 2 and fixed; 10 indicates that the number of random cycles is 4 and fixed; 11 indicates that the number of random cycles is 8 and fixed, i.e., implementation method 1 is used. It can be understood that: 00 indicates that the number of random cycles increases with each access attempt, specifically determined according to the first set; 01 to 11 indicate that the number of random cycles remains unchanged with each access attempt, and indicate the number of random cycles.

[0194] Furthermore, for example, if node T determines that access has failed before sending the third message on the fourth resource, it may send the third message on the fourth resource. That is, if node T receives a response message to the first or second message before sending the third message on the fourth resource, or determines that access to node G has been successful (e.g., receiving Msg4 and confirming successful access based on Msg4), it may not send the third message on the fourth resource; or, if node T's physical layer receives an instruction from a higher layer to stop access before sending the third message on the fourth resource, then node T's physical layer may not send the third message on the fourth resource. Optionally, the position of the fourth resource among the V access resources is determined by the physical layer. The description of "access failed" can be found above and will not be repeated here.

[0195] (3) The relationship between the first SLSSID, the second SLSSID and the third SLSSID is introduced.

[0196] As one possible implementation, node T sends access request messages based on the same SLSSID each time, without selecting a new SLSSID, until it receives Msg2 or successfully accesses the network. In this case, the first SLSSID, the second SLSSID, and the third SLSSID are the same SLSSID.

[0197] One possible implementation is that node T sends access request messages based on the same SLSSID each time without selecting a new SLSSID, until the number of access requests by node T is greater than or equal to a first threshold. Then, a new SLSSID is selected, and access is re-initiated based on the newly selected SLSSID. For example, node T maintains a counter, initially set to 0. The counter increments by 1 with each access request message sent. Specifically, after sending the second message, node T increments the counter (currently 1); after sending the first message, it increments the counter (currently 2); and after sending the third message, it increments the counter (currently 3). Assuming the first threshold is 8, when the counter reaches 8, node T can reset the counter to 0 and re-initiate access. The first threshold can be predefined or preconfigured, such as 8 or 16, without specific limitations.

[0198] As another possible implementation, node T selects a new SLSSID each time it sends an access request message. For example, after sending the second message based on the second SLSSID, node T selects a new SLSSID (the new SLSSID is the first SLSSID) and sends the first message based on the first SLSSID; after sending the first message, it selects a new SLSSID (the new SLSSID is the third SLSSID) and sends the third message based on the third SLSSID. Since the first, second, and third SLSSIDs are all randomly selected from a preset range, they may be the same or different.

[0199] It is understood that Figure 7 above only illustrates the process of three accesses. In actual implementation, there may be more or fewer accesses than this. This application embodiment does not limit this.

[0200] (2) Case 2

[0201] Figure 9 is a flowchart illustrating the communication method provided in Embodiment 2 of this application. As shown in Figure 9, the method may include:

[0202] S901, node G sends a broadcast message on the first resource; correspondingly, node T receives the broadcast message on the first resource, and the broadcast message is used for side synchronization.

[0203] In S902, node T sends a second message on the third resource. This second message is used to request access from node G; that is, the second message is an access request message. The third resource is located after the first resource in the time domain.

[0204] S903, Node T determines that the access request for the second message failed.

[0205] Optionally, determining that the access failure of the second message request can be understood as the first timer timing out, the access still not receiving a response message for the second message, or the access to the G node failing. Optionally, the length of the first timer represents the maximum waiting time for Msg2 after Msg1 has been sent, or, the higher layer instructing the physical layer to wait the maximum waiting time for Msg2 after sending Msg1. Optionally, the length of the first timer is pre-configured or predefined. For example, 160ms or 320ms. Optionally, the first timer can also be a first duration or a first time period.

[0206] For example, node T can determine whether it has received a response message for the second message within the first time period. If it has received a response message for the second message within the first time period, or has successfully connected to node G (e.g., received Msg4 and confirmed successful connection based on Msg4), then the connection is considered successful. If it has not received a response message for the second message within the first time period, or has not successfully connected to node G, then the connection is considered failed. Alternatively, the physical layer of node T can determine whether it has received an instruction from a higher layer to stop access within the first time period. If it has received such an instruction, then the connection is considered successful. If it has not received such an instruction, then the connection is considered failed.

[0207] It is understandable that if node T determines that the access to the second message request has failed, the subsequent process can be executed; if node T determines that the access to the second message request has succeeded, the subsequent process does not need to be executed.

[0208] S904, Node T sends the first message on the second resource. The first message is used to request access to Node G.

[0209] The specific implementation of S703 can be referred to S402. As mentioned above, the second resource is an access resource in the first access resource set, which includes Y access resources located in X periods.

[0210] As one possible implementation, the first of the X cycles is the next cycle after determining that the access failure of the second message request has been determined.

[0211] For example, if node T determines that access has failed before sending the first message on the second resource, it may send the first message on the second resource. That is, if node T receives a response message to the second message or determines that access to node G has been successful (e.g., receiving Msg4 and determining successful access based on Msg4) before sending the first message on the second resource, it may not send the first message on the second resource; or, if node T's physical layer receives an instruction from a higher layer to stop access before sending the first message on the second resource, node T's physical layer may not send the first message on the second resource. Optionally, the position of the second resource among the Y access resources is determined by the physical layer.

[0212] For example, node T can determine whether it has received a response message for the second message before the first timer expires. If it has received a response message for the second message before the first timer expires, it can be determined that the access is successful, and the higher layer does not instruct the physical layer to send the Msg1 message. If it has not received a response message for the second message before the first timer expires, it can be determined that the access has failed, and the higher layer instructs the physical layer to send the Msg1 message.

[0213] Optionally, the information instructing the transmission of Msg1 includes one or more of the following: Msg1 transmission trigger information, the location of the first resource, and the location of the second resource. Optionally, the higher layer instructing the physical layer to transmit Msg1 can be a direct or indirect instruction. For example, transmitting Msg1 directly instructs the physical layer to transmit Msg1 via a Msg1 transmission trigger information. Another example is indirectly instructing the physical layer to transmit Msg1 by indicating the location of the first resource and / or the location of the second resource.

[0214] As another possible implementation, the first cycle of the X cycles is the cycle following the cycle in which the instruction from the higher layer to send the Msg1 message is received.

[0215] For example, before sending the first message on the second resource, if node T determines that the previous Msg1 access failed, then the higher layer of node T sends an instruction to the physical layer to send Msg1, and the physical layer can then send the first message on the second resource. That is, if node T does not receive an instruction from the higher layer to send Msg1 before sending the first message on the second resource, it may not send the first message on the second resource; or, if the physical layer of node T receives an instruction from the higher layer to stop access before sending the first message on the second resource, then the physical layer of node T may not send the first message on the second resource. Optionally, the position of the second resource among the Y access resources is determined by the higher layer and indicated to the physical layer.

[0216] S905, Node T determines that the access request for the first message failed.

[0217] The specific implementation of S905 can be found in the description of S903.

[0218] S906, Node T sends a third message on the fourth resource, which is used to request access to Node G.

[0219] For example, the fourth resource is an access resource in the second access resource set, which includes V access resources located in P periods, and each of the P periods includes N access resources, where V = P * N.

[0220] As one possible implementation, the first of the P cycles is the most recent cycle after the access failure of the first message request is determined.

[0221] For example, if node T determines that access has failed before sending the third message on the fourth resource, it may send the third message on the fourth resource. That is, if node T receives a response message to the first or second message before sending the third message on the fourth resource, or determines that access to node G has been successful (e.g., receiving Msg4 and confirming successful access based on Msg4), it may not send the third message on the fourth resource; or, if node T's physical layer receives an instruction from a higher layer to stop access before sending the third message on the fourth resource, node T's physical layer may not send the third message on the fourth resource. Optionally, the position of the fourth resource among the Y access resources is determined by the physical layer.

[0222] As another possible implementation, the first of the P cycles is the cycle following the cycle in which the instruction from the higher layer to send the Msg1 message is received.

[0223] For example, before sending the third message on the fourth resource, if node T determines that the previous Msg1 access failed, then the higher layer of node T sends an instruction to the physical layer to send Msg1, and the physical layer can then send the third message on the fourth resource. That is, if node T does not receive an instruction from the higher layer to send Msg1 before sending the third message on the fourth resource, it may not send the third message on the fourth resource; or, if the physical layer of node T receives an instruction from the higher layer to stop access before sending the third message on the fourth resource, then the physical layer of node T may not send the third message on the fourth resource. Optionally, the position of the fourth resource among the Y access resources is determined by the higher layer and indicated to the physical layer.

[0224] Taking the example of "the first period of P periods being the most recent period after the failure of the first message request to access", let's assume X = P = 2, N = 2, and the duration of the first time period is 160ms (i.e., the length of one period). As shown in Figure 10, node T receives broadcast information on the first resource in period n. At a certain time point in period n, the physical layer of node T receives an indication message from the higher layer of node T and sends the second message on the third resource in period n. After determining that the access request for the second message has failed, node T selects an access resource from the first access resource set (which includes two access resources in period n+2 and two access resources in period n+3). The selected access resource is the second resource, and the first message is sent on the second resource. After determining that the access request for the first message has failed, node T selects an access resource from the second access resource set (which includes two access resources in period n+4 and two access resources in period n+5). The selected access resource is the fourth resource, and the third message is sent on the fourth resource. This process continues until Msg2 is received or access is successful.

[0225] Understandably, the difference between Situation 2 and Situation 1 lies in the following: In Situation 2, after node T sends the access request message, it waits for a period of time (i.e., the first time period) and, after confirming that the previously requested access has failed, initiates access again; in Situation 1, access is initiated continuously until Msg2 is received or access is successful. Apart from this difference, Situation 2 and Situation 1 can be used interchangeably.

[0226] (3) Case 3

[0227] Figure 11 is a flowchart illustrating the communication method provided in Embodiment 3 of this application. As shown in Figure 11, the method may include:

[0228] S1101, Node G sends a broadcast message on the first resource; correspondingly, Node T receives the broadcast message on the first resource, and the broadcast message is used for side synchronization.

[0229] S1102, Node T sends a first message on the second resource. The first message is used to request access to Node G.

[0230] For example, after receiving indication information from a higher layer of node T (indicating access to node G), the physical layer of node T can determine the second resource and send a first message on the second resource. The specific implementation can be found above. The second resource is an access resource in a first set of access resources, which includes Y access resources located in X periods. The first period in the X periods is the most recent period after receiving the indication information.

[0231] Optionally, the information instructing the transmission of Msg1 includes one or more of the following: Msg1 transmission trigger information, the location of the first resource, and the location of the second resource. Optionally, the higher layer instructing the physical layer to transmit Msg1 can be a direct or indirect instruction. For example, transmitting Msg1 directly instructs the physical layer to transmit Msg1 via a Msg1 transmission trigger information. Another example is indirectly instructing the physical layer to transmit Msg1 by indicating the location of the first resource and / or the location of the second resource.

[0232] Optionally, the location of the second resource can be determined by the physical layer, or by instructions from a higher layer.

[0233] S1103, Node T sends a third message on the fourth resource, while the first message is used to request access to Node G.

[0234] For example, the fourth resource is an access resource in the second access resource set, which includes V access resources located in P periods. Each of the P periods includes N access resources, where V = P * N. The first period of the P periods is the period following the last period of the X periods, where P is an integer greater than or equal to X.

[0235] For example, assuming X = P = 2 and N = 2, as shown in Figure 12, node T receives broadcast information on the first resource in period n. At a certain point in period n, the physical layer of node T receives an instruction from the higher layer of node T (i.e., the last period after receiving the instruction is period n+1). Then, node T selects an access resource from the first access resource set (the first access resource set includes two access resources in period n+1 and two access resources in period n+2), which is the second resource, and sends the first message on the second resource. Node T then selects an access resource from the second access resource set (the second access resource set includes two access resources in period n+3 and two access resources in period n+4), which is the fourth resource, and sends the third message on the fourth resource. This process continues until Msg2 is received or access is successful.

[0236] Understandably, the difference between Situation 3 and Situation 1 lies in the following: In Situation 1, after receiving the instruction information from the higher layer, the physical layer of Node T first attempts to send an access request message on a nearby resource (i.e., the third resource), and then selects one of the Y access resources over X periods to send the first message; in Situation 3, Node T directly selects one of the Y access resources over X periods to send the first message. Aside from this difference, Situation 3 and Situation 1 can be referenced interchangeably.

[0237] (4) Case 4

[0238] Figure 13 is a flowchart illustrating the communication method provided in Embodiment 4 of this application. As shown in Figure 13, the method may include:

[0239] S1301, Node G sends a broadcast message on the first resource; correspondingly, Node T receives the broadcast message on the first resource, and the broadcast message is used for side synchronization.

[0240] S1302, Node T sends a first message on the second resource. The first message is used to request access to Node G.

[0241] S1303, Node T determines that the access request for the first message has failed.

[0242] The specific implementation of S1303 can be found in the description of S903.

[0243] S1304, Node T sends a third message on the fourth resource, while the first message is used to request access to Node G.

[0244] For example, the fourth resource is an access resource in the second access resource set, which includes V access resources located in P periods. Each of the P periods includes N access resources, where V = P * N, and P is an integer greater than or equal to X.

[0245] As one possible implementation, the first of the P cycles is the most recent cycle after the access failure of the first message request is determined.

[0246] For example, if node T determines that access has failed before sending the third message on the fourth resource, it may send the third message on the fourth resource. That is, if node T receives a response message to the first or second message before sending the third message on the fourth resource, or determines that access to node G has been successful (e.g., receiving Msg4 and confirming successful access based on Msg4), it may not send the third message on the fourth resource; or, if node T's physical layer receives an instruction from a higher layer to stop access before sending the third message on the fourth resource, node T's physical layer may not send the third message on the fourth resource. Optionally, the position of the fourth resource among the Y access resources is determined by the physical layer.

[0247] As another possible implementation, the first of the P cycles is the cycle following the cycle in which the instruction from the higher layer to send the Msg1 message is received.

[0248] For example, before sending the third message on the fourth resource, if node T determines that the previous Msg1 access failed, then the higher layer of node T sends an instruction to the physical layer to send Msg1, and the physical layer can then send the third message on the fourth resource. That is, if node T does not receive an instruction from the higher layer to send Msg1 before sending the third message on the fourth resource, it may not send the third message on the fourth resource; or, if the physical layer of node T receives an instruction from the higher layer to stop access before sending the third message on the fourth resource, then the physical layer of node T may not send the third message on the fourth resource. Optionally, the position of the fourth resource among the Y access resources is determined by the higher layer and indicated to the physical layer.

[0249] Taking the example of "the first period of P periods being the most recent period after the failure of the first message request to access", let's assume X = P = 2, N = 2, as shown in Figure 14. Node T receives broadcast information on the first resource in period n. At a certain point in period n, the physical layer of node T receives an indication message from the higher layer of node T (i.e., the last period after receiving the indication message is period n+1). Then, node T selects an access resource from the first access resource set (the first access resource set includes 2 access resources in period n+1 and 2 access resources in period n+2), which is the second resource, and sends the first message on the second resource. After determining that the access of the first message request has failed, node T selects an access resource from the second access resource set (the second access resource set includes 2 access resources in period n+4 and 2 access resources in period n+5), which is the fourth resource, and sends the third message on the fourth resource. This process continues until Msg2 is received or access is successful.

[0250] Understandably, the difference between scenario 4 and scenario 3 lies in the following: In scenario 4, after node T sends the access request message, it waits for a period of time (i.e., the first time period) and, after confirming that the previously requested access has failed, initiates access again; in scenario 3, access is initiated continuously until Msg2 is received or access is successful. Apart from this difference, scenarios 4 and 3 can be used interchangeably.

[0251] Regarding the above embodiments, it is understood that:

[0252] (1) The above focuses on describing the differences between different examples, different situations and different implementation methods. In each process of this application, unless otherwise specified or logically conflicting, the terms and / or descriptions between different examples, different situations and different implementation methods are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0253] (2) The various numerical designations used in this application are merely for descriptive convenience and are not intended to limit the scope of this application. The step numbers in the above flowcharts are only examples of the execution process and do not constitute a restriction on the order of execution of the steps. That is, the size of each step number does not imply the order of execution; the execution order of each step should be determined by its function and internal logic. Furthermore, not all steps shown in the flowcharts are mandatory steps; some steps may be added or deleted based on actual needs.

[0254] The foregoing mainly describes the solutions provided by the embodiments of this application from the perspective of communication device interaction. It is understood that, in order to achieve the above functions, the communication device may include hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0255] The embodiments of this application can divide the communication device into functional units according to the above method examples. For example, each function can be divided into a separate functional unit, or two or more functions can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0256] In the case of using integrated units, FIG15 shows a possible exemplary block diagram of the device involved in the embodiments of this application. As shown in FIG15, the device 1500 may include a processing unit 1502 and a communication unit 1503. The processing unit 1502 is used to control and manage the operation of the device 1500. The communication unit 1503 is used to support communication between the device 1500 and other devices. Optionally, the communication unit 1503 is also called a transceiver unit, and may include a receiving unit and / or a sending unit, respectively used to perform receiving and sending operations. The device 1500 may also include a storage unit 1501 for storing the program code and / or data of the device 1500.

[0257] (1) The device 1500 can be the first communication device (such as a terminal device) in the above embodiments. The processing unit 1502 can support the device 1500 in performing the actions of the first communication device in the above method embodiments. Alternatively, the processing unit 1502 mainly performs the internal actions of the first communication device in the method embodiments, and the communication unit 1503 can support communication between the device 1500 and other devices.

[0258] For example, in one embodiment, the communication unit 1503 is configured to: receive broadcast information from a second communication device on a first resource, the broadcast information being used for side-by-side synchronization; and send a first message on the second resource, the first message being used to request access to the second communication device; wherein the second resource is an access resource in a first access resource set, the first access resource set being located after the first resource in the time domain; the first access resource set includes Y access resources located in X periods, each of the X periods including N access resources, Y = X * N, where Y is an integer greater than 1; X is an integer greater than or equal to 1, and N is an integer greater than 1; or, X is an integer greater than 1, and N is an integer greater than or equal to 1.

[0259] Further related implementations can be found in the description in the method embodiments.

[0260] (2) The device 1500 can be the second communication device (such as the first computing node) in the above embodiments. The processing unit 1502 can support the device 1500 in performing the actions of the second communication device in the above method embodiments. Alternatively, the processing unit 1502 mainly performs the internal actions of the second communication device in the method embodiments, and the communication unit 1503 can support communication between the device 1500 and other devices.

[0261] For example, in one embodiment, the communication unit 1503 is configured to: send broadcast information on a first resource, the broadcast information being used for side-by-side synchronization; receive a first message on a second resource, the first message being used to request access to the second communication device; wherein, the second resource is an access resource in a first access resource set, the first access resource set being located after the first resource in the time domain; the first access resource set includes Y access resources located in X periods, each of the X periods including N access resources, Y = X * N, where Y is an integer greater than 1; X is an integer greater than or equal to 1, and N is an integer greater than 1; or, X is an integer greater than 1, and N is an integer greater than or equal to 1.

[0262] Further related implementations can be found in the description in the method embodiments.

[0263] It should be understood that the division of units in the above device is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, all units in the device can be implemented entirely through software calls from processing elements; all units can be implemented entirely in hardware; or some units can be implemented through software calls from processing elements, while others are implemented in hardware. For example, each unit can be a separate processing element, or it can be integrated into a chip within the device. Alternatively, it can be stored as a program in memory, called and executed by a processing element of the device. Moreover, these units can be fully or partially integrated together, or implemented independently. The processing element here can also be called a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, the operations or units described above can be implemented through integrated logic circuits in the processor element or through software calls from processing elements.

[0264] In one example, a unit in any of the above devices can be one or more integrated circuits configured to implement the methods described above, such as: one or more application-specific integrated circuits (ASICs), or one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs), or a combination of at least two of these forms of integrated circuits. As another example, when a unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a central processing unit (CPU), or other processor capable of calling programs. Furthermore, these units can be integrated together and implemented as a System-on-a-Chip (SoC).

[0265] The receiving unit described above is an interface circuit of the device, used to receive signals from other devices. For example, when the device is implemented as a chip, the receiving unit is an interface circuit for the chip to receive signals from other chips or devices. The transmitting unit described above is an interface circuit of the device, used to transmit signals to other devices. For example, when the device is implemented as a chip, the transmitting unit is an interface circuit for the chip to transmit signals to other chips or devices.

[0266] Based on the above embodiments, this application also provides a communication device. Referring to FIG16, the communication device 1600 may include one or more processors 1601. Optionally, the communication device 1600 may further include a memory 1602, which may be disposed inside or outside the communication device 1600. It is understood that FIG16 only shows the main components of the communication device, and the communication device may further include a transceiver (not shown in the figure).

[0267] Specifically, processor 1601 may be a CPU, a network processor (NP), or a combination of a CPU and an NP. Processor 1601 may further include a hardware chip. The aforementioned hardware chip may be an ASIC, a programmable logic device (PLD), or a combination thereof. The aforementioned PLD may be a complex programmable logic device (CPLD), an FPGA, generic array logic (GAL), or any combination thereof.

[0268] The processor 1601 and memory 1602 are interconnected. Optionally, the processor 1601 and memory 1602 are interconnected via bus 1603; bus 1603 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, only one thick line is used in Figure 16, but this does not indicate that there is only one bus or one type of bus.

[0269] In one alternative implementation, memory 1602 is used to store programs, etc. Specifically, the program may include program code, which includes computer operation instructions. Memory 1602 may include RAM, and may also include non-volatile memory, such as one or more disk storage devices. Processor 1601 executes the application program stored in memory 1602 to implement the above-mentioned functions, thereby realizing the functions of communication device 1600.

[0270] For example, the communication device 1600 may be the first communication device or the second communication device in the above embodiments.

[0271] In one embodiment, when the communication device 1600 performs the functions of the first communication device in the above method embodiment, the transceiver can perform the transmit and receive operations executed by the first communication device in the above method embodiment; the processor 1601 can perform other operations besides the transmit and receive operations executed by the first communication device in the above method embodiment. Specific details can be found in the relevant descriptions in the above embodiments, and will not be elaborated upon here.

[0272] In one embodiment, when the communication device 1600 implements the functions of the second communication device in the above method embodiment, the transceiver can perform the transmit and receive operations executed by the second communication device in the above method embodiment; the processor 1601 can perform other operations besides the transmit and receive operations executed by the second communication device in the above method embodiment. Specific details can be found in the relevant descriptions in the above embodiments, and will not be elaborated upon here.

[0273] The terms "system" and "network" in this application embodiment are used interchangeably. "At least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of A, B, and C" includes A, B, C, AB, AC, BC, or ABC. And, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in this application embodiment are used to distinguish multiple objects and are not used to limit the order, sequence, priority, or importance of multiple objects.

[0274] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0275] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can 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 one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0276] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0277] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

Claims

1. A communication method, characterized in that, The method is applied to a first communication device, and the method includes: Receive broadcast information from a second communication device on a first resource, the broadcast information being used for side-by-side synchronization; Send a first message on the second resource, the first message being used to request access to the second communication device; Wherein, the second resource is an access resource in the first access resource set, and the first access resource set is located after the first resource in the time domain; The first set of access resources includes Y access resources located in X periods, and each of the X periods includes N access resources, where Y = X * N, and Y is an integer greater than 1; X is an integer greater than or equal to 1, and N is an integer greater than 1; or, X is an integer greater than 1, and N is an integer greater than or equal to 1.

2. The method according to claim 1, characterized in that, The time units in which the N access resources are located in the period are determined based on the time unit in which the first resource is located in the period.

3. The method according to claim 2, characterized in that, The index of access resource n in the N access resources in the period is Fn, and the index of the first resource in the period is FH. Fn = FH + B + (L*n / N), or Fn = (FH + B + (L*n / N)) mod L, n = 0, 1, 2, ..., N-1; where B is an integer greater than or equal to 0, L is the number of time units included in the period, and mod is the modulo operation.

4. The method according to any one of claims 1 to 3, characterized in that, The first message includes a first signal and access information; or, the first message is the first signal. The first signal is generated based on the first SLSSID.

5. The method according to any one of claims 1 to 4, characterized in that, Send the first message on the second resource, including: After receiving the instruction information from the higher layer of the first communication device, the physical layer of the first communication device sends a first message on the second resource; The first of the X cycles is the most recent cycle after the indication information is received.

6. The method according to any one of claims 1 to 4, characterized in that, Before sending the first message on the second resource, the method further includes: Send a second message on the third resource, the second message being used to request access to the second communication device; Wherein, the third resource is located after the first resource in the time domain, and the first period of the X periods is the period following the first period in which the third resource is located.

7. The method according to any one of claims 1 to 4, characterized in that, Before sending the first message on the second resource, the method further includes: Send a second message on the third resource, the second message being used to request access to the second communication device; It has been determined that the access request in the second message has failed; Wherein, the third resource is located after the first resource in the time domain, and the first period of the X periods is the most recent period after the access failure of the second message request is determined.

8. The method according to claim 6 or 7, characterized in that, Send a second message on a third resource, including: After receiving the instruction information from the higher layer of the first communication device, the physical layer of the first communication device sends the second message on the third resource; Wherein, the third resource is the most recent access resource after receiving the indication information; or, The third resource is either the first access resource in the first period, or the third resource is randomly determined from the access resources in the first period, where the first period is the most recent period after receiving the indication information; or... The third resource is randomly determined from the access resources located after receiving the indication information in the first period, where the first period is the period for receiving the indication information.

9. The method according to any one of claims 1 to 8, characterized in that, The method further includes: Send a third message on the fourth resource, the third message being used to request access to the second communication device; The fourth resource is an access resource in the second access resource set. The first period of the resource in the second access resource set is the period following the last period of the X periods. The second access resource set includes access resources in P periods, where P is an integer greater than or equal to X.

10. The method according to any one of claims 1 to 8, characterized in that, The method further includes: It has been determined that the access request in the first message has failed; Send a third message on the fourth resource, the third message being used to request access to the second communication device; The fourth resource is an access resource in the second access resource set; The first period in which the resources in the second access resource set are located is the most recent period after the access failure of the first message request was determined. The second access resource set includes access resources for P periods, where P is an integer greater than or equal to X.

11. The method according to claim 9 or 10, characterized in that, The value of P is determined based on the value of X and the first set.

12. The method according to claim 11, characterized in that, If the value of X is not the largest value in the first set, then the value of P is the next value in the first set that is greater than X, and / or, if the value of X is the largest value in the first set, then the value of P is equal to the value of X.

13. The method according to any one of claims 9 to 12, characterized in that, The broadcast information includes information indicating how the value of P was determined and / or the value of X; The value of P is determined in the following ways: the value of P is equal to the value of X, or the value of P is determined based on the value of X and the first set.

14. The method according to any one of claims 1 to 13, characterized in that, The method further includes: receiving a response message to the first message, the response message including information about the second resource, or the response message being scrambled based on information about the second resource, the information about the second resource being used to indicate that the response message responds to the first message sent on the second resource.

15. The method according to claim 14, characterized in that, The information of the second resource includes at least one of the following: Location information of the cycle in which the second resource is located; Location information of the time unit where the second resource is located; The location information of the second resource.

16. A communication method, characterized in that, The method is applied to a second communication device, and the method includes: A broadcast message is sent on the first resource, the broadcast message being used for side-row synchronization; Receive a first message on the second resource, the first message being used to request access to the second communication device; Wherein, the second resource is an access resource in the first access resource set, and the first access resource set is located after the first resource in the time domain; The first set of access resources includes Y access resources located in X periods, and each of the X periods includes N access resources, where Y = X * N, and Y is an integer greater than 1; X is an integer greater than or equal to 1, and N is an integer greater than 1; or, X is an integer greater than 1, and N is an integer greater than or equal to 1.

17. The method according to claim 16, characterized in that, The time units in which the N access resources are located in the period are determined based on the time unit in which the first resource is located in the period.

18. The method according to claim 17, characterized in that, The index of access resource n in the N access resources in the period is Fn, and the index of the first resource in the period is FH. Fn = FH + B + (L*n / N), or Fn = (FH + B + (L*n / N)) mod L, n = 0, 1, 2, ..., N-1; where B is an integer greater than or equal to 0, L is the number of time units included in the period, and mod is the modulo operation.

19. The method according to any one of claims 16 to 18, characterized in that, The first message includes a first signal and access information; or, the first message is the first signal. The first signal is generated based on the first SLSSID.

20. The method according to any one of claims 16 to 19, characterized in that, The method further includes: sending a response message to the first message, the response message including information about the second resource, or the response message being scrambled based on information about the second resource, the information about the second resource being used to indicate that the response message responds to the first message sent on the second resource.

21. The method according to claim 20, characterized in that, The information of the second resource includes at least one of the following: Location information of the cycle in which the second resource is located; Location information of the time unit where the second resource is located; The location information of the second resource.

22. The method according to any one of claims 16 to 21, characterized in that, The first resource is located in the second cycle; The first resource is located in one of the first Z time units included in the second cycle, where Z is an integer greater than or equal to 1.

23. The method according to any one of claims 16 to 22, characterized in that, The first resource is located in a first time unit, which is one of at least one available time unit; The available time unit refers to the time unit that is not occupied by broadcast information or access request messages from other communication devices, and when used as the first time unit, the corresponding access resource is not occupied by broadcast information or access request messages from other communication devices.

24. A communication device, characterized in that, Includes units for performing the method as described in any one of claims 1 to 23.

25. A communication device, characterized in that, The device includes a processor coupled to a memory in which a computer program is stored; the processor is configured to invoke part or all of the computer program in the memory such that the method as described in any one of claims 1 to 23 is executed.

26. A communication system, characterized in that, The communication system includes a first communication device and a second communication device, wherein the first communication device is used to perform the method as described in any one of claims 1 to 15, and the second communication device is used to perform the method as described in any one of claims 16 to 23.

27. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that, when some or all of the computer program is executed by a computer, causes the method described in any one of claims 1 to 23 to be performed.

28. A computer program product, characterized in that, When the computer reads and executes the computer program product, the method described in any one of claims 1 to 23 is performed.

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