Anti-Interference Performance And Routing Optimization Research Under WPAN Application Environment

In the wireless personal area networks (WPAN) application environment, the situation of co-existence of networks is very complex. It is very important for networks belonged to different standards to mitigate co-interference and cooperate with each other, so as to improve the throughput of the whole systems in the complex environments. Wireless Ad Hoc network does not depend on any fixed support infrastructure and has the advantages of deployability, flexibility, robustness, etc. The requirements on information share and data exchange among wireless smart devices and consumer electronics promote greatly the research on wireless Ad Hoc networks. Co-existence problem of devices belong to different systems under WPAN application environment and routing research of Bluetooth Ad Hoc networks are focused on in this dissertation.Firstly, the throughput performance of IEEE 802.11b under WPAN application environment is studied. To using IEEE 802.11b'characteristic of variable packet length, packet collision (due to WPAN packet interference) probability is deduced in theory. The deduction that there is only one packet length resulting in max throughput also can be validated by simulating. Based on this, a scheme of adaptive packet length of IEEE 802.11b is presented. Simulation results show that throughput performance of IEEE802.11b can be improved obviously by adopting the scheme.Secondly, the problem of co-interference between WPAN and other systems working on ISM channel is studied. To improve the performance of WPAN system that adopted adaptive frequency hopping technology, a collision avoidance and adaptive packet selecting scheme, is proposed. Analysis results show that throughput of WPAN system can be obviously increased when channel state changes not very frequently and the number of bad channel is not excessive. The scheme is very practicable because it only needs to upgrade the software of the system.Thirdly, by taking adjacent and co-channel interference into account, self-interference problem of multi-WPANs coexistence is addressed, and an adaptive packet type selected scheme is proposed. The impact of distributing density of WPANs, distance between transmitter and receiver, path loss exponent, and packet length on packet error probability are discussed, respectively. Simulation results show that anti-self-interference performance ofWPAN can be improved effectively. Based on former analysis, ideas of improving data transmission rate on two representative applications of WPAN are proposed after abstracting the characters of the two applications.Finally, the routing problem of multi-hop mobile Ad Hoc networks based on Bluetooth system is studied. To deal with the insufficiency in existing routing protocol, for example, route confusion problems possibly caused by existing master-slave compound nodes and route failure caused by flooding route searching packets, a new routing protocol scheme is presented. Analysis and simulation results show that Bluetooth's technical characteristics can be adequately used, at the same time, not only the former problems can be figured out but route discovery time can be obviously decreased and the route discovery probability can be increased.