Research On Data Distribution Mechanism Of Association Network Coding In Vehicle Ad Hoc Networks

Vehicular Ad-hoc Networks (VANETs) is a special mobile ad hoc network. In the VANETs, high dynamic topological structure easily causes high mobility in short-haul communication. In addition, limited wireless resources and lossy nature wireless channel pose major challenges to VANETs data distribution performance. How to distributing data effectively is a research focus in the current Vehicular Ad-hoc Networks. In the Vehicular Ad-hoc Networks, Road Side Unit (RSU), which able to support high power data transceivers, is very expensive. How to improving the base installation service efficiency to the Infrastructure-to-Vehicle (12V) becomes the major issue. Moreover, after broadcasting information in the original node, effective coordination and data distribution among Vehicle-to-Vehicle (V2V) is also a question deserving research. Applicability of network code in wireless network has been proved, the network coding technology used in wireless networks can improve the distribution of multicast data capacity, enhanced transmission reliability, while reducing transmission delay. But related research, such as how to applying the network code into the VANETs, is limited. This paper mainly discusses how to improve the data distribution system performance. Combing various factors, we raised data distribution algorithm suitable for VANETs in I2V and V2V scenarios associated network coding, which mainly include the following aspects:1) In I2V, wireless channel instability, quick topology dynamic changes and limited network capacity of VANETs, this article addresses how to transfer database to vehicles more rapidly, effectively, reliably from the Road Side Unit. This paper proposed a RSU multicast retransmission algorithm based on network coding technology. At the end of the first stage of RSU multicast retransmission, integrating vehicles’location, speed, direction and data validity, thus to get an optimal combination of network coding, and then multicasting the composite of the above network coding combination so as to improve data distribution efficiency. The simulation experiment results show that comparing with the random network coding retransmission algorithm, the above algorithm realized 4 times improvement of data download average rate and average download delay reduced 90%, data distribution delay reduced 40% and 20% respectively, which dramatically improved the data distribution capacity in VANETs.2) In V2V, considering the features of high vehicle speed and serious signal loss, this article proposed a collision less V2V distributed a relay cooperative algorithm, comprehensively considered factors like signal channel, data receiving, vehicle location and speed, determined the candidate relay vehicle by requesting-confirming. Besides, in the data relay retransmission, instant decodable network coding method was used in the data relay retransmission which effectively reduced the average turn-on time of users and improved each user’s data download rate at the same time. The simulation experiment results proved that with no extra overhead, the above algorithm effectively shortened data collaboration distribution and enhanced data download rate and wireless signal channel resource usage rate.