Research And Realization Of AMulti-Channel MAC Protocol Of Wireless Networks

At present, concerning the communication of swarm robots, most of communication mode use radio to broadcast. Many bottleneck problems still exist in field of communication of swarm robot system, since the big number of robots and changing network topology. For instance, with the number of robots increasing, radio collisions increases, transmission speed and throughput reduce. MAC protocols have a great influence on the performance of wireless network. Therefore, the research of MAC protocol is of important practical significance.In this paper, we presented, designed and implemented a kind of multi-channel MAC protocol based on CC2430 communication module. The basic idea was that making good use of CC2430's 16 non-overlapping subchannels, the adjacent robots selected different subchannels to send data, without interference when parallel transmitting message. Firstly, swarm robot and its communication profiles are introduced in the thesis overall. Then we discuss the existing MAC Protocols and the performance of back-off algorithms. Then a multi-channel MAC protocol called RobotNet is designed and implemented for our robots.The paper's main achievements include:(1) Analysis of the fairness of the back-off algorithms: Comparing binary exponential back-off algorithm with multiplicative increase line decrease algorithm, the results show that, the back-off algorithm have greatly influence on the performance of fairness.(2) A multi-channel MAC schemes presented: Since each robot is equipped with a CC2430 communication module, we propose a multi-channel MAC protocol called RobotNet that agrees one of N channels as a control channel and N-1 channels as data channel. Communication mode between robots uses broadcast on the control channel to negotiate data channel and uses unicast on the data channels.(3) Realization of RobotNet: Besides using CSMA, a dynamic channel allocation mechanism and a channel reservation mechanism are designed. RobotNet is implemented in ANSI C, based on CC2430 communication module.(4) Performance testing of RobotNet: In order to verify the attributes of RobotNet, ten physical robots were adopted to set up test environment and several experiments were designed to compare attributes with a classic MAC protocol CSMA. As a result, the performance of RobotNet is better than CSMA's on throughput and packet loss rate.The study in this paper shows that RobotNet can efficiently reduce the radio collision probability and greatly improve the throughput of the network performance with increasing the number of robots.