Wireless Mobile Self-organizing Network Channel Access Control Protocol Design And Analysis

The Wireless Mobile Self-organizing Network (WMSN) demonstrates a new kind of network architecture that combines the self-organization of Ad hoc networks and the user management of cellular mobile systems. Thus, it can be deployed easily and flexibly and also makes mobile users more convenient to access it. In WMSN, channel access and communication mode on link layer are very important for reliable communication on higher layer. So, this paper discusses the above issues in the two hierarchies respectively.The system infrastructure of WMSN is firstly described in this paper so that we can understand the environment thoroughly. Because Medium Access Control protocol of IEEE 802.11 (DFWMAC) is adopted in WMSN, this paper gives an introduction to DFWMAC in its second part. For the hierarchy which provides network access to mobile users, this paper explains channel access, handoff procedure and communication mode for wireless hosts. At the same time, it gives the experiment results which illustrates the sequence of management frame exchanged and computes the handoff delay. For the backbone, this paper focuses on two performance problems-TCP instability and unfairness, which are caused by multihop links and rooted in MAC layer. In the last part, this paper proposed a different backoff algorithm for DFWMAC based on resource estimation. Simulation results indicate that the new backoff algorithm can address the above two problems effectively without lose of simplicity.