高速環(huán)境下車車通信網(wǎng)絡(luò)的MAC層接入?yún)f(xié)議研究
發(fā)布時(shí)間：2019-05-14 21:30
【摘要】：智能交通系統(tǒng)(ITS)下的車車通信技術(shù)已經(jīng)成為最近幾年學(xué)術(shù)和研究的熱點(diǎn)問題。在本文中,我們重點(diǎn)介紹了在高速公路環(huán)境下基于周期性位置信息發(fā)送的一種媒體接入控制方法---自組織時(shí)分復(fù)用多址接入技術(shù)。快速變化的路況使得發(fā)送接收信息必須要有一個(gè)時(shí)間限制,所以對于整個(gè)車載系統(tǒng)來說,及時(shí)與可預(yù)測的信道接入對于整個(gè)系統(tǒng)格外得重要。然而,應(yīng)用在802.11p中的傳統(tǒng)MAC層隨機(jī)接入機(jī)制使得一個(gè)節(jié)點(diǎn)可能丟掉其發(fā)送的位置信息中的80%。我們根據(jù)仿真得到的結(jié)論是,目前在國際上普遍使用的的802.11p通信標(biāo)準(zhǔn)中,帶有沖突避免機(jī)制的載波偵聽多路訪問(CSMA/CA)接入?yún)f(xié)議,不能夠保證嚴(yán)格意義上的實(shí)時(shí)通信,不能滿足高速公路中快速可靠的通信。 本文在分析研究傳統(tǒng)的幾種隨機(jī)接入機(jī)制的基礎(chǔ)上,借鑒AIS系統(tǒng)中船舶通信系統(tǒng)的STDMA機(jī)制,將STDMA應(yīng)用在高速公路車車通信系統(tǒng)中。應(yīng)用該技術(shù),不管競爭信道的用戶節(jié)點(diǎn)有多少,每個(gè)節(jié)點(diǎn)總是能夠獲得可以預(yù)估的信道接入資格,并能夠預(yù)估最大的接入時(shí)延不到一個(gè)SI的時(shí)間,這種時(shí)延還是很小的,也不存在大量發(fā)送數(shù)據(jù)掉包情況,仿真結(jié)果顯示連續(xù)掉包5次以上的概率極小。根據(jù)STDMA的機(jī)制,本文先介紹了數(shù)據(jù)在信道接入中的處理流程,然后借鑒其它文章中提到的相應(yīng)的算法公式推出數(shù)據(jù)信息在無線鏈路中連續(xù)碰撞的概率。 在實(shí)際仿真階段,為了深入研究STDMA技術(shù),本文根據(jù)相關(guān)協(xié)議描述,建立了一個(gè)仿真平臺,在平臺中建立了模擬高速公路路況的拓?fù)?并且拓?fù)渲袑?shí)時(shí)地變化,所有用戶一直在互相交互信息,也就是說一直存在著信道預(yù)約和競爭。于是本文通過仿真,觀察不同參數(shù)配置和條件下系統(tǒng)表現(xiàn)出的性能。仿真結(jié)果中,最關(guān)鍵的時(shí)隙復(fù)用率高低情況可以明確顯現(xiàn)系統(tǒng)承受高負(fù)載高通信壓力的能力。最后本文得到的結(jié)論是信道復(fù)用率在較大的時(shí)候會增大信息之間的干擾,那么在節(jié)點(diǎn)數(shù)量較小的情況下,可以調(diào)節(jié)參數(shù)配置節(jié)約系統(tǒng)資源,而在節(jié)點(diǎn)數(shù)量增多的情況下,為了減小復(fù)用率,可以調(diào)整位置信息感知范圍等一些參數(shù)配置來大大提高系統(tǒng)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.
【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN929.5;U495
本文編號：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.
【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN929.5;U495
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