Study On Opportunistic Routing Based On Network Coding

Wireless Mesh Network (WMN) is a new type network, which introduces the characters of bothWLAN and Ad Hoc into itself. Easy to deploy and flexible to expand, making it possible for users to getaccess to the wireless network no matter when and where they are. The design and improvement of WMN’sopportunistic routing strategy, which is based on network coding, have been gaining an increasing interestfrom scholars home and abroad. Research in this area, however, still cannot meet the demands. There isalso a lot of work ahead, such as how to choose the forwarding nodes, the effect of multi bit-rates onsending data and the node exit mechanism. The thesis aims to solve the problmes above and involvesseveral parts as following:First, detailed analysis and study have been done on opportunistic routing protocols based on networkcoding, and an opportunistic routing algorithm BNC_OR (Balanced Network Coding and OpportunisticRouting) is proposed, which considers coding opportunities and how to select forwarding nodes. Thealgorithm chooses the number of expected transmission as a metric. By adjusting the coefficients, letBNC_OR achieve the highest throughout while improving the coding opportunities as much as possible.Results show that when compared to CORE, BNC_OR can increase throughout of system and reduce theend-to-end delays.Subsequently, an analysis has been given on the potential benefits when combining opportunisticrouting and network coding with the bit-rate selection mechanism, and then a model is proposed. Themodel has two main parts: the framework for calculation of expected opportunistically coded transmissiontime (ExOC_TT) and the algorithm to find the optimal forwarding scheme to minimize ExOC_TT. Theresults show that applying bit-rate selection in opportunistic routing and network coding has a substantialbenefit on expected transmission time.Finally, an analysis has been given on the existing node exit mechanism, and an algorithm ofdynamically node adjusting is proposed to solve the problem. By defining similar nodes, ADNA highlyexplores the uncertain path characters of opportunistic routing and minimizes the impact on datatransmission by nodes exiting, seeking to optimize the whole network performance. Results indicate thatprotocols with ADNA would have an obvious improvement in system’s throughout.