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
Over the past few years, wireless networking technologies have made vast forays in our daily lives. In wireless ad-hoc networks, links are set up by a number of units without any permanent infrastructures. In this pap...Over the past few years, wireless networking technologies have made vast forays in our daily lives. In wireless ad-hoc networks, links are set up by a number of units without any permanent infrastructures. In this paper, the resource optimization is considered to maximize the network throughput by efficiently using the network capacity, where multi-hop functionality and spatial TDMA （STDMA） access scheme are used. The objective is to find the minimum frame length with given traffic distributions and corresponding routing information. Because of the complex structure of the underlying mathematical problem, previous work and analysis become intractable for networks of realistic sizes. The problem is addressed through mathematical programming approach, the linear integer formulation is developed for optimizing the network throughput, and then the similarity between the original problem and the graph edge coloring problem is shown through the conflict graph concept. A column generation solution is proposed and several enhancements are made in order to fasten its convergence. Numerical results demonstrate that the theoretical limit of the throughput can be efficiently computed for networks of realistic sizes.展开更多
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.
基金This paper is supported by the National Natural Science Foundation of China under Grant Nos. 60241004 and 90104010, the National Basic Research 973 Program of China under Grant No, 2003CB314801, and the State Key Laboratory of Networking and Switching Technology,
文摘Over the past few years, wireless networking technologies have made vast forays in our daily lives. In wireless ad-hoc networks, links are set up by a number of units without any permanent infrastructures. In this paper, the resource optimization is considered to maximize the network throughput by efficiently using the network capacity, where multi-hop functionality and spatial TDMA （STDMA） access scheme are used. The objective is to find the minimum frame length with given traffic distributions and corresponding routing information. Because of the complex structure of the underlying mathematical problem, previous work and analysis become intractable for networks of realistic sizes. The problem is addressed through mathematical programming approach, the linear integer formulation is developed for optimizing the network throughput, and then the similarity between the original problem and the graph edge coloring problem is shown through the conflict graph concept. A column generation solution is proposed and several enhancements are made in order to fasten its convergence. Numerical results demonstrate that the theoretical limit of the throughput can be efficiently computed for networks of realistic sizes.
