高速环境下车车通信网络的MAC层接入协议研究
发布时间：2019-05-14 21:30
【摘要】：智能交通系统(ITS)下的车车通信技术已经成为最近几年学术和研究的热点问题。在本文中,我们重点介绍了在高速公路环境下基于周期性位置信息发送的一种媒体接入控制方法---自组织时分复用多址接入技术。快速变化的路况使得发送接收信息必须要有一个时间限制,所以对于整个车载系统来说,及时与可预测的信道接入对于整个系统格外得重要。然而,应用在802.11p中的传统MAC层随机接入机制使得一个节点可能丢掉其发送的位置信息中的80%。我们根据仿真得到的结论是,目前在国际上普遍使用的的802.11p通信标准中,带有冲突避免机制的载波侦听多路访问(CSMA/CA)接入协议,不能够保证严格意义上的实时通信,不能满足高速公路中快速可靠的通信。 本文在分析研究传统的几种随机接入机制的基础上,借鉴AIS系统中船舶通信系统的STDMA机制,将STDMA应用在高速公路车车通信系统中。应用该技术,不管竞争信道的用户节点有多少,每个节点总是能够获得可以预估的信道接入资格,并能够预估最大的接入时延不到一个SI的时间,这种时延还是很小的,也不存在大量发送数据掉包情况,仿真结果显示连续掉包5次以上的概率极小。根据STDMA的机制,本文先介绍了数据在信道接入中的处理流程,然后借鉴其它文章中提到的相应的算法公式推出数据信息在无线链路中连续碰撞的概率。 在实际仿真阶段,为了深入研究STDMA技术,本文根据相关协议描述,建立了一个仿真平台,在平台中建立了模拟高速公路路况的拓扑,并且拓扑中实时地变化,所有用户一直在互相交互信息,也就是说一直存在着信道预约和竞争。于是本文通过仿真,观察不同参数配置和条件下系统表现出的性能。仿真结果中,最关键的时隙复用率高低情况可以明确显现系统承受高负载高通信压力的能力。最后本文得到的结论是信道复用率在较大的时候会增大信息之间的干扰,那么在节点数量较小的情况下,可以调节参数配置节约系统资源,而在节点数量增多的情况下,为了减小复用率,可以调整位置信息感知范围等一些参数配置来大大提高系统性能。
[Abstract]:Vehicle communication technology under intelligent transportation system (ITS) has become a hot academic and research issue in recent years. In this paper, we focus on a media access control method based on periodic position information transmission in expressway environment, which is called self-organizing time division multiplex multiple access technology. Because of the rapidly changing road conditions, there must be a time limit for sending and receiving information, so for the whole vehicle system, timely and predictable channel access is particularly important for the whole system. However, the traditional MAC layer random access mechanism applied in 802.11p makes it possible for a node to lose 80% of the location information it sends. According to the simulation results, it is concluded that the carrier listening multiaccess (CSMA/CA) access protocol with collision avoidance mechanism can not guarantee the real-time communication in the strict sense in the 802.11p communication standard, which is widely used in the world at present. It can not satisfy the fast and reliable communication in the expressway. Based on the analysis and study of several traditional random access mechanisms, this paper applies STDMA to the expressway vehicle communication system by using the STDMA mechanism of ship communication system in AIS system for reference. Using this technique, no matter how many user nodes there are in the competitive channel, each node can always obtain the channel access qualification that can be predicted, and can predict the maximum access delay less than one SI, which is still very small. There is no large number of data swaps, and the simulation results show that the probability of switching more than 5 times continuously is very small. According to the mechanism of STDMA, this paper first introduces the processing flow of data in channel access, and then deduces the probability of continuous collision of data information in wireless link by using the corresponding algorithm formula mentioned in other articles for reference. In the actual simulation stage, in order to deeply study the STDMA technology, according to the description of the relevant protocols, this paper establishes a simulation platform, and establishes the topology to simulate the highway road conditions in the platform, and the topology changes in real time. All users have been interacting with each other, that is to say, there has been channel reservation and competition. Therefore, the performance of the system under different parameter configurations and conditions is observed by simulation. In the simulation results, the most critical time slot reuse rate can clearly show the ability of the system to withstand high load and high communication pressure. Finally, the conclusion of this paper is that the channel reuse rate will increase the interference between the information when the number of nodes is large, so when the number of nodes is small, the parameter allocation can be adjusted to save the system resources, while when the number of nodes increases, In order to reduce the reuse rate, some parameter configurations, such as location information perception range, can be adjusted to greatly improve the system performance.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5;U495
本文编号：2477065
[Abstract]:Vehicle communication technology under intelligent transportation system (ITS) has become a hot academic and research issue in recent years. In this paper, we focus on a media access control method based on periodic position information transmission in expressway environment, which is called self-organizing time division multiplex multiple access technology. Because of the rapidly changing road conditions, there must be a time limit for sending and receiving information, so for the whole vehicle system, timely and predictable channel access is particularly important for the whole system. However, the traditional MAC layer random access mechanism applied in 802.11p makes it possible for a node to lose 80% of the location information it sends. According to the simulation results, it is concluded that the carrier listening multiaccess (CSMA/CA) access protocol with collision avoidance mechanism can not guarantee the real-time communication in the strict sense in the 802.11p communication standard, which is widely used in the world at present. It can not satisfy the fast and reliable communication in the expressway. Based on the analysis and study of several traditional random access mechanisms, this paper applies STDMA to the expressway vehicle communication system by using the STDMA mechanism of ship communication system in AIS system for reference. Using this technique, no matter how many user nodes there are in the competitive channel, each node can always obtain the channel access qualification that can be predicted, and can predict the maximum access delay less than one SI, which is still very small. There is no large number of data swaps, and the simulation results show that the probability of switching more than 5 times continuously is very small. According to the mechanism of STDMA, this paper first introduces the processing flow of data in channel access, and then deduces the probability of continuous collision of data information in wireless link by using the corresponding algorithm formula mentioned in other articles for reference. In the actual simulation stage, in order to deeply study the STDMA technology, according to the description of the relevant protocols, this paper establishes a simulation platform, and establishes the topology to simulate the highway road conditions in the platform, and the topology changes in real time. All users have been interacting with each other, that is to say, there has been channel reservation and competition. Therefore, the performance of the system under different parameter configurations and conditions is observed by simulation. In the simulation results, the most critical time slot reuse rate can clearly show the ability of the system to withstand high load and high communication pressure. Finally, the conclusion of this paper is that the channel reuse rate will increase the interference between the information when the number of nodes is large, so when the number of nodes is small, the parameter allocation can be adjusted to save the system resources, while when the number of nodes increases, In order to reduce the reuse rate, some parameter configurations, such as location information perception range, can be adjusted to greatly improve the system performance.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5;U495
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