Design And Implementation Of Wireless Communication Control System Based On CM-MAC Protocol

In recent years,Wireless Local Area Networks(WLAN)has been widely used in various fields because of its advantages of mobility,Maintainable and low cost.The IEEE 802.11 standard defines multiple non-overlapping physical layer channels of WLAN in 2.4 GHz and 5 GHz bands,which also helps to promote the application of wireless communication technology.However,it also aggravates the congestion of radio channel resources and causes a lot of interference.In some application scenarios with complex network or physical environment,compared with low-frequency transmation,high-frequency wireless has obvious lower communication quality because of its weak diffraction property,lots of signal attenuation and shorter transmission distance.In this paper,we presents a wireless communication solution based on 433MHz frequency band.Used for mobile ad hoc network(MANET)with single half-duplex transceiver,which is applied to multi-channel switching control system.On the basis of in-depth study of existing media access control protocol(MAC),this paper designes and implements a cooperative wireless multi-channel(CM-MAC)protocol.The main contents of this protol are as follows:setting up a common control channel and N data channels,using common code to send packets on the control channel,and every node maintains a channel usage list(CUL).The source nodes and destination nodes complete channel reservation by shaking hands with each other and the broadcasting information of cooperative nodes.After that,they transmit the packets and confirmation on the negotiated data channel.This system has the following characteristics:i)the multi-channel systm effectively utilizes the total bandwidth in the frequency band so that we can improve the throughput of transmission;ii)Compared with the complete but complex network protocol in the standard of IE802.11,this scheme is more suitable for transplanting to low-cost hardware systems,and iii)it does not need clock synchronization,which greatly reduces the network burden.The main work of this paper is as follows:1)Determine the research content:consult a large amount of data,study various existing communication technologies,communication frequency bands and wireless MAC protocols,analyze the problems existing in the current research,and determine the research direction of this design.2)Design and performance study of CM-MAC protocol:Design a multi-channel MAC protocol based on cooperative node and channel negotiation.Modify the existing simulation model of the network simulation tool NS-2 and add relevant code to verify the validity of the MAC protocol.3)Hardware implementation of this wireless communication system:complete the chip selection,build the hardware system,and transplant the multi-channel MAC protocol based on negotiation to the hardware platform,which further proves the practicability of the protocol.4)System design and experimental results:In order to verify the practical performance of the protocol,this paper designs two experimental schemes,one is the large indoor office area with single coordinator and multi-terminal,the experimental area is about 1500 m~2;the second is Multiple adjacent rooms with multi-coordinator and several terminals communicating simultaneously.The basic parameters and overall performance of the system were tested several times.The experimental results show that,by adjusting the parameters such as the transmit power and antenna equipment of the wireless module Si4463,the communication quality of the wireless communication system with CM-MAC protocol added can meet the application requirements in different environments,and the effectiveness and application value of the system are fully verified.