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CN-116390062-B - Relay selection method and system for vehicle-vehicle multi-hop cooperative communication system

CN116390062BCN 116390062 BCN116390062 BCN 116390062BCN-116390062-B

Abstract

The invention discloses a relay selection method and a system for a vehicle-oriented multi-hop cooperative communication system, which are used for constructing a random geometric model of a vehicle networking network, determining the position and the size of a candidate relay area according to a non-relay probability threshold and the communication service quality of a relay link, acquiring all candidate relay vehicles in the relay selection area to obtain a candidate relay set, selecting the relay vehicles in the candidate relay vehicles according to a relay selection strategy for guaranteeing the service quality of source nodes-relay vehicles, respectively sending messages to the relay vehicles and destination nodes by a source node, forwarding the messages to the next relay vehicle or the destination node according to the relative position between the relay vehicles and the destination node after the message is decoded by the relay vehicles, and repeating the current selected relay nodes as the source node until the messages are forwarded to the destination node after one hop is finished. The invention effectively reduces the relay hop count, so that the communication is more reliable and the delay is lower.

Inventors

  • ZHANG CHAO
  • Ou Lianghao

Assignees

  • 西安交通大学

Dates

Publication Date
20260505
Application Date
20230411

Claims (7)

  1. 1. A relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system is characterized by comprising the following steps: S1, constructing a random geometric model of a vehicle networking network according to the distribution characteristics of vehicles, wherein a source node and a destination node in the random geometric model are any nodes in the network, and the source node and the destination node cooperatively communicate in a multi-hop relay mode; s2, determining the position and the size of a candidate relay area according to the relay probability threshold and the communication service quality of a relay link based on the random geometric model obtained in the step S1, wherein the method specifically comprises the following steps: Constructing a signal propagation model between a source node and a relay vehicle, representing small-scale fading by using Nakagami-m fading, simulating different fading environments by changing the value of m, and when m=1, the Nakagami-m fading is Rayleigh fading, and the small-scale fading coefficient is the Rayleigh fading at the moment Obeying parameters of Calculating the average value of the interference power of the Internet of vehicles system, and then calculating the average value of the noise power to obtain the distance At the lower boundary of the communication success probability of the source node-candidate relay vehicle, if in the communication range of the vehicle Within the range, the success probability of the communication between vehicles is larger than the set success probability threshold value I.e. The maximum range satisfying the condition is defined as the communication range of the vehicle ; Communication range of vehicle The method comprises the following steps: Wherein, the To decode the required signal-to-interference-and-noise ratio threshold, For the vehicle density to be the same, For the purpose of strength, the strength of the material, A communication success probability threshold value set for a communication range, For the probability that the vehicle is active at a certain moment and uses the same frequency band as the receiver, For the origin to the road Is used for the distance of (a), For vehicles on the road and feet on the road Is used for the distance of (a), As a coefficient of the path loss, Is the standard deviation of the noise and, Transmitting power for the transmitter; The size and position of the candidate relay area are: Wherein, the As the radius of the candidate relay zone, The position of the center of the candidate relay area; Wherein, the The optimization requirement of (1) ensures that the probability of no relay vehicles in the candidate relay area is smaller than a set threshold value, and the condition of no relay is avoided; in order to avoid that the distance between the relay vehicle and the destination node is larger than the distance between the source node d and the destination node, the method ensures the communication quality ; The probability of the number of candidate relay vehicles being 0 is: according to the set threshold value of no-relay probability Determining candidate relay zone radius, which needs to be satisfied Order-making Obtaining the radius of the candidate relay area ; S3, acquiring all candidate relay vehicles in the relay selection area to obtain a candidate relay set, if the set is an empty set, expanding the candidate relay radius, repeating the step S2, and selecting a relay vehicle from the candidate relay vehicles according to a relay selection strategy for guaranteeing the service quality of the source node-relay vehicle; S4, the source node respectively sends messages to the relay vehicle and the destination node obtained in the step S3, and after the relay vehicle decodes the messages, the messages are forwarded to the next relay vehicle or the destination node according to the relative position with the destination node; S5, the distance between the relay vehicle and the destination node is larger than the communication range, the currently selected relay node is used as a source node after one hop is finished, and the steps S2 to S4 are repeated until the message is forwarded to the destination node.
  2. 2. The relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system according to claim 1, wherein in step S1, the road system is modeled as a strength Poisson wire process of (2) Each straight line Distance from origin to corresponding straight-line foot drop Angle and angle Determining and mutually independent, modeling vehicles on the road as density on the poisson wire based on the course of the road forming the poisson wire Is a one-dimensional poisson point process The vehicles on each line are independently distributed and the positions of the vehicles form a poisson-wire Kax process 。
  3. 3. The relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system according to claim 1, wherein in step S3, all candidate relay vehicles in the relay selection area are acquired by using the candidate relay area selected in step S2, and a candidate relay set is obtained And then selecting the relay vehicle by taking the expected signal-to-interference-plus-noise ratio of the received signal of the vehicle as a performance index of a measurement source node-relay link.
  4. 4. The relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system according to claim 3, wherein a vehicle with a maximum expected signal-to-interference-plus-noise ratio is selected from a candidate relay vehicle set as a relay Forwarding the message, namely: Wherein, the To relay the signal-to-interference-and-noise ratio of the vehicle received signal, And the signal to interference and noise ratio of the ith vehicle in the candidate relay area.
  5. 5. The relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system according to claim 1, wherein in step S4, the relay vehicle decodes the message in a decoding and forwarding manner, and forwards the message to the next relay vehicle or the destination node according to the relative position with the destination node, if the distance is smaller than the communication range obtained in step S2 And directly forwarding the message to a destination node, combining and decoding the signals by the destination node in a mode of selecting and combining, and ending transmission, otherwise forwarding the message to the next relay.
  6. 6. The relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system according to claim 5, wherein the received signal of the vehicle is relayed Received signal with destination node The method comprises the following steps of: Wherein, the For the transmit power of the transmitter, For the small-scale fading coefficients of the channel, For the distance between the transmitter and the receiver, As a coefficient of the path loss, And Respectively the variance is Is added to white noise.
  7. 7. A relay selection system for a vehicle-to-vehicle multi-hop cooperative communication system, comprising: The construction module constructs a random geometric model of the vehicle networking network according to the distribution characteristics of the vehicles, wherein a source node and a destination node in the random geometric model are any nodes in the network, and the source node and the destination node cooperatively communicate in a multi-hop relay mode; The position module is used for determining the position and the size of the candidate relay area according to the relay probability threshold and the communication service quality of the relay link based on the random geometric model obtained by the construction module, and specifically comprises the following steps: Constructing a signal propagation model between a source node and a relay vehicle, representing small-scale fading by using Nakagami-m fading, simulating different fading environments by changing the value of m, and when m=1, the Nakagami-m fading is Rayleigh fading, and the small-scale fading coefficient is the Rayleigh fading at the moment Obeying parameters of Calculating the average value of the interference power of the Internet of vehicles system, and then calculating the average value of the noise power to obtain the distance At the lower boundary of the communication success probability of the source node-candidate relay vehicle, if in the communication range of the vehicle Within the range, the success probability of the communication between vehicles is larger than the set success probability threshold value I.e. The most range satisfying the condition is defined as the communication range of the vehicle ; Communication range of vehicle The method comprises the following steps: Wherein, the To decode the required signal-to-interference-and-noise ratio threshold, For the vehicle density to be the same, For the purpose of strength, the strength of the material, A communication success probability threshold value set for a communication range, For the probability that the vehicle is active at a certain moment and uses the same frequency band as the receiver, For the origin to the road Is used for the distance of (a), For vehicles on the road and feet on the road Is used for the distance of (a), As a coefficient of the path loss, Is the standard deviation of the noise and, Transmitting power for the transmitter; The size and position of the candidate relay area are: Wherein, the As the radius of the candidate relay zone, The position of the center of the candidate relay area; Wherein, the The optimization requirement of (1) ensures that the probability of no relay vehicles in the candidate relay area is smaller than a set threshold value, and the condition of no relay is avoided; in order to avoid that the distance between the relay vehicle and the destination node is larger than the distance between the source node d and the destination node, the method ensures the communication quality ; The probability of the number of candidate relay vehicles being 0 is: according to the set threshold value of no-relay probability Determining candidate relay zone radius, which needs to be satisfied Order-making Obtaining the radius of the candidate relay area ; The selection module is used for acquiring all candidate relay vehicles in the relay selection area to obtain a candidate relay set, expanding the candidate relay radius if the set is an empty set, and repeating the position module to select a relay vehicle from the candidate relay vehicles according to a relay selection strategy for guaranteeing the service quality of the source node-relay vehicle; the decoding module is used for respectively sending the message to the relay vehicle and the destination node obtained by the selection module by the source node, and forwarding the message to the next relay vehicle or the destination node according to the relative position between the relay vehicle and the destination node after the message is decoded by the relay vehicle; And the output module is used for repeating the current selected relay node serving as the source node until the message is forwarded to the destination node after one hop is finished.

Description

Relay selection method and system for vehicle-vehicle multi-hop cooperative communication system Technical Field The invention belongs to the technical field of wireless communication, and particularly relates to a relay selection method and a relay selection system for a vehicle-to-vehicle multi-hop cooperative communication system. Background Along with the development of society, vehicles on roads are increased, the intelligent degree is higher, and the Internet of vehicles system is developed. The internet of vehicles system can realize information intercommunication among vehicles, roads and vehicles and people through mutual communication, is a core component part of the intelligent traffic system in the future, can effectively promote road safety, lighten traffic jams and promote unmanned realization. The development of the internet of vehicles brings more convenience to people and simultaneously faces a plurality of challenges. Firstly, vehicles have higher speed and more frequent position change compared with the traditional mobile terminal, so that the network topology structure of the Internet of vehicles can be changed frequently and rapidly, secondly, the environment on the road is complex, and vehicles and other obstacles are more, so that the path loss and the multipath effect in the Internet of vehicles communication are more serious, and the communication quality is influenced. And vehicles are faster, once communication is interrupted or an error occurs, serious consequences can occur, which can present challenges for internet of vehicles. The third generation partnership project (3 GPP) organization proposed a cellular technology based internet of vehicles communication (C-V2X) scheme. The C-V2X scheme also supports cooperative communication of vehicles with the assistance of existing infrastructure, based on the direct communication mode. That is, when the direct link channel condition of the vehicle is bad, the infrastructure of the cellular base station or other vehicles or the like can be utilized as a relay of the link, thereby improving the reliability of the communication. However, the vehicle is used as a relay carrier and has the characteristic of high mobility, but the existing relay selection scheme lacks analysis of the random position of the vehicle, the relay vehicle does not have limitation on the spatial position, and the situation that the relay vehicle is too close to or too far from a source node is easy to occur. Too close a relay vehicle can cause small progress per hop, increase in the number of relay hops, resulting in reduced efficiency and increased delay, and too far a relay vehicle can cause poor quality of a source node-relay vehicle link, resulting in increased outage probability and increased retransmission times. In view of the above problems, no effective solution has been proposed at present. Disclosure of Invention The invention aims to solve the technical problems of high relay hop count, large delay and low cooperative communication efficiency when the channel condition of a vehicle direct link is bad. The invention adopts the following technical scheme: A relay selection method for a vehicle-to-vehicle multi-hop cooperative communication system comprises the following steps: S1, constructing a random geometric model of a vehicle networking network according to the distribution characteristics of vehicles, wherein a source node and a destination node in the random geometric model are any nodes in the network, and the source node and the destination node cooperatively communicate in a multi-hop relay mode; S2, determining the position and the size of a candidate relay area according to the non-relay probability threshold and the communication service quality of the relay link based on the random geometric model obtained in the step S1; S3, acquiring all candidate relay vehicles in the relay selection area to obtain a candidate relay set, if the set is an empty set, expanding the candidate relay radius, repeating the step S2, and selecting a relay vehicle from the candidate relay vehicles according to a relay selection strategy for guaranteeing the service quality of the source node-relay vehicle; S4, the source node respectively sends messages to the relay vehicle and the destination node obtained in the step S3, and after the relay vehicle decodes the messages, the messages are forwarded to the next relay vehicle or the destination node according to the relative position with the destination node; S5, the distance between the relay vehicle and the destination node is larger than the communication range, the currently selected relay node is used as a source node after one hop is finished, and the steps S2 to S4 are repeated until the message is forwarded to the destination node. Specifically, in step S1, the road system is modeled as having a strength ofPoisson wire process of (2)Each straight lineDistance from origin to corresponding straight-line foot