电子不停车收费系统(Electronic Toll Collection,ETC)是解决目前交通拥堵问题最有效的手段。为规范ETC设计,统一国内ETC标准,我国制定了电子收费专用短程通信国家标准(Dedicated Short Range Communications,DSRC)。DSRC数据链路层采...电子不停车收费系统(Electronic Toll Collection,ETC)是解决目前交通拥堵问题最有效的手段。为规范ETC设计,统一国内ETC标准,我国制定了电子收费专用短程通信国家标准(Dedicated Short Range Communications,DSRC)。DSRC数据链路层采用由国际标准化组织(ISO)制定的高级数据链路控制规程(High-Level Data Link Control,HDLC)。文章遵循DSRC短程通信协议数据链路层标准规范,采用硬件描述语言Verilog HDL实现了一种基于串行结构的HDLC解码电路,并对其中‘0’比特删除模块、CRC校验模块着重分析,设计较短时延的解码电路。在解码时钟为256 k Hz时,可以在0.2 ms时间内完成解码和读取工作。展开更多
In this paper the DSRC/IEEE 802.11p Medium Access Control (MAC) method of the vehicular communication has been simulated on highway road scenario with periodic broadcast of packets in a vehicle-to-vehicle situation. I...In this paper the DSRC/IEEE 802.11p Medium Access Control (MAC) method of the vehicular communication has been simulated on highway road scenario with periodic broadcast of packets in a vehicle-to-vehicle situation. IEEE 802.11p MAC method is basically based on carrier sense multiple accesses (CSMA) where nodes listen to the wireless channel before sending the packets. If the channel is busy, the vehicle node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets/messages because no channel access was possible before the next message/packet was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad- hoc vehicular networks.展开更多
文摘电子不停车收费系统(Electronic Toll Collection,ETC)是解决目前交通拥堵问题最有效的手段。为规范ETC设计,统一国内ETC标准,我国制定了电子收费专用短程通信国家标准(Dedicated Short Range Communications,DSRC)。DSRC数据链路层采用由国际标准化组织(ISO)制定的高级数据链路控制规程(High-Level Data Link Control,HDLC)。文章遵循DSRC短程通信协议数据链路层标准规范,采用硬件描述语言Verilog HDL实现了一种基于串行结构的HDLC解码电路,并对其中‘0’比特删除模块、CRC校验模块着重分析,设计较短时延的解码电路。在解码时钟为256 k Hz时,可以在0.2 ms时间内完成解码和读取工作。
文摘In this paper the DSRC/IEEE 802.11p Medium Access Control (MAC) method of the vehicular communication has been simulated on highway road scenario with periodic broadcast of packets in a vehicle-to-vehicle situation. IEEE 802.11p MAC method is basically based on carrier sense multiple accesses (CSMA) where nodes listen to the wireless channel before sending the packets. If the channel is busy, the vehicle node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets/messages because no channel access was possible before the next message/packet was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad- hoc vehicular networks.
