Wireless Ad Hoc Network Mac Protocol And Related Technologies

Recently the research on Ad hoc network has been a hotspot. Ad hoc network is a dynamic distributed self-organized system consisting of wireless nodes. Each node is not only a host, but a router. Medium Access Control (MAC) protocol is an important part in the network protocol stack of Ad hoc network, and it is mainly used to coordinate nodes to access the shared wireless channel. Whether MAC protocol can utilize the limited wireless resource plays a crucial role in Ad hoc network performance. So the research of MAC protocol and related techniques in Ad hoc networks is significant. This dissertation is part of results of research into the adaptive backoff algorithm, multi-rate MAC protocol and packet scheduling algorithm of Ad hoc networks, when the project "Research on key technologies of mobile wireless Ad hoc networks based on MPLS" is in progress, which sponsored by National Natural Science Fund, China (Grant No. 60372101).The main issues of this paper are:Chapter 1 introduces the background and significance of the dissertation, briefly describes the characteristics of Ad hoc networks, and summarizes the main research content and innovation.Chapter 2 mainly discusses the protocol stack structure of Ad hoc networks, concludes the present research on various MAC protocol, and detailedly describes the IEEE 802.11 MAC protocol which is based on shared wireless channel.Chapter 3 firstly proposes a binary negative exponential backoff (BNEB) algorithm which applies for high-level node, validate that the node with smaller average contention window has higher channel contending ability. And based on this, two adaptive backoff algorithms RBAB and CABEB are proposed, which can adjust the packet receiving and forwarding rate of the congested node when congestion occurs and can effectively alleviate the network congestion.Chapter 4 summarizes the research about the present multi-rate MAC protocols. According to the congestion problem in multihop Ad hoc networks, a new multi-rate MAC protocol ACC-AR with dynamic transmitting window is proposed, which uses back-to-back transmission to send several successive data frames. ACC-AR protocol not only utilizes the high quality channel but also improves the wireless channel utilization ratio.Chapter 5 proposes an opportunistic packet scheduling algorithm CBOS. The sender sends multicast RTS frame targeting serval receivers simultaneously, and the receivers respond CTS according to a probability based on congestion level. It improves the spatial reuse ratio of Ad hoc networks and helps to the congestion control.Finally, summarizes the dissertation and points out the directions for further study.