Research On Multi-channel Slot Assignment Algorithms Based On Chain-Type Multi-hop Networks

Ad Hoc networks with dynamic topology, nodes’ limited energy and unstable links, make video transmission facing lots of issuesa such as long end-to-end delay, limited bandwidth, packet loss rate and others. In recent years Ad Hoc networks have been widely used in underground communication in coal mine, wireless monitoring in transportation, marine communication and other occasions. Ad Hoc networks in these occasions usually have a multi- hop chain topology. Video transmission in emergency and security situations have become increasingly demanding, which have exacerbated the challenges in video transmission. Therefor improving Ad Hoc networks’ performance is the key area of the research.This thesis provides an overview of the problems in the multi- hop Ad Hoc networks video transmission and the current study abroad, and it analyzes the key factors affecting network performance, details the classification and study of MAC protocols and routing protocols. For the problem of throughput decreasing rapidly in a single-channel multi- hop network, a multi- interface multi- channel AODV protocol(MIMC-AODV) is proposed, and channel assignment algorithms and channel recovery algorithms in this protocol are analyzed. This article uses NS2 simulation software to test the performance of MIMC-AODV protocol.The results in NS2 show that, MIMC-AODV protocol has a better performance.Secondly, MIMC-AODV using competitive MAC protocol causes collision when access network. To solve this problem, the SA-TDMA protocol, using non-competitive MAC protocol, combined with traditional TDMA protocol is proposed. The SA-TDMA protocol designs slot assignment algorithms for Ad Hoc networks with the topology of chain-type, reducing collision within the scope of the two-hop neighbor nodes.The results in NS2 show that, SA-TDMA protocol meets the better fairness of the nodes.Finally, the MSAT protocol combined with channel assignment technology and the slot assignment is proposed to solve slot waste problem and fairness deficiencies. MSAT protocol uses AODV protocol in routing protocol and TDMA protocol in MAC layer. With the channel assignment and slot assignment, every node in the networks is assigned to different channels, different data slots assigned to neighbors. It reduces interference between channels and improving the fairness of the network nodes. MIMC-AODV, SA-TDMA and MSAT have been tested in NS2 and the MyEvalvid tool. Test results show that MSAT is more suitable for the linear chain-type Ad Hoc networks video multihop transmission.