冲突检测的载波侦听多重访问（CSMA/CD）协议在局域网中已获广泛应用,以太网就是典型。这类协议中,报文分组均平等地竞争信道,其传输延迟不保证有确定值。某些紧急的、有严格延迟限制的信息如实时话音传输信息就可能遭受过量延迟,这在...冲突检测的载波侦听多重访问（CSMA/CD）协议在局域网中已获广泛应用,以太网就是典型。这类协议中,报文分组均平等地竞争信道,其传输延迟不保证有确定值。某些紧急的、有严格延迟限制的信息如实时话音传输信息就可能遭受过量延迟,这在重信道负载时时尤为严重。本文提出一种设定报文分组优先级为基础的新协议。协议设 N 个优先级,每个分组分配一个 n 位（n=Log<sub>2</sub>N+1）优先码,采用二进制优先码比较算法。展开更多
In this study, the transmission capacity of VANETs in a highway scenario is analysed on the basis of a 1D line model and the carrier sense multiple access with collision avoidance(CSMA/CA) protocol. We describe the CS...In this study, the transmission capacity of VANETs in a highway scenario is analysed on the basis of a 1D line model and the carrier sense multiple access with collision avoidance(CSMA/CA) protocol. We describe the CSMA/CA protocol used in IEEE802.11 p from the perspective of the geometric relationship amongst simultaneous transmitters. The desired channel and interfering channels are assumed to experience the same amount of path-loss and Rayleigh fading. On the basis of the proposed model, we analyse the attempted transmission probability of each road segment and the maximum intensity of active transmitters, including their theoretical values. Then, we employ the physical model to obtain the outage probability and derive the upper bound of the transmission capacity of a VANET, which is defined as the average spatial density of successful transmissions in the network. Simulation results indicate that the theoretical value offers a good bound on network capacity.展开更多
文摘冲突检测的载波侦听多重访问（CSMA/CD）协议在局域网中已获广泛应用,以太网就是典型。这类协议中,报文分组均平等地竞争信道,其传输延迟不保证有确定值。某些紧急的、有严格延迟限制的信息如实时话音传输信息就可能遭受过量延迟,这在重信道负载时时尤为严重。本文提出一种设定报文分组优先级为基础的新协议。协议设 N 个优先级,每个分组分配一个 n 位（n=Log<sub>2</sub>N+1）优先码,采用二进制优先码比较算法。
基金supported in part by the National Natural Science Foundation of China under Grant No.61271184 and 61571065
文摘In this study, the transmission capacity of VANETs in a highway scenario is analysed on the basis of a 1D line model and the carrier sense multiple access with collision avoidance(CSMA/CA) protocol. We describe the CSMA/CA protocol used in IEEE802.11 p from the perspective of the geometric relationship amongst simultaneous transmitters. The desired channel and interfering channels are assumed to experience the same amount of path-loss and Rayleigh fading. On the basis of the proposed model, we analyse the attempted transmission probability of each road segment and the maximum intensity of active transmitters, including their theoretical values. Then, we employ the physical model to obtain the outage probability and derive the upper bound of the transmission capacity of a VANET, which is defined as the average spatial density of successful transmissions in the network. Simulation results indicate that the theoretical value offers a good bound on network capacity.
