Studyand Design On Multi-channel MAC Rotocol For Wireless Sensor Networks In Industry

There is contradiction between the essential requirement and the situation ofindustrial wireless network. Owing to the presence of electromagnetic interferencefrom wireless communication and frequent starting of large equipment, thephenomenon of packet loss is serious, which cannot meet the requirement ofindustrial essential requirement. The traditional single channel MAC protocolcannot effectively resolve the contradiction. Therefore, the multi-channel MACprotocol for a specific application environment emerges. It can be well effective inensuring the real-time and reliable transmission in wireless sensor network andreducing network interference simultaneously, and also improving the networkcapacity.Firstly, various wireless signals were analyzed in the2.4GHz ISM frequencyband using spectrum analysis tools, signal feature was extracted and the maininterference source in industrial environment was found.Secondly, practical wireless sensor network test platform was built up and thevalues of RSSI in the2.4GHz each channel was obtained through the measured.Variance changes of experimental data were analyzed through designing windowmechanism. Channel model was built based on Markov chain theory and thecorresponding packet loss rate was calculated, which as the basis of channel assigningof wireless sensor network next.Then, the reasonable channel allocation algorithm was designed and channelmodel was optimized through analyzing the characteristics and application situationsof existing channel assignment schemes.Finally, in order to accommodate multiple channel information, the MAC layerframe of the standard was designed by investigating the MAC protocol and theIEEE802.15.4standard. Theoretical analysis showed that, On the premise of reliabletransmission, the multi-channel MAC protocol can improve network capacity andchannel utilization ratio effectively.A multi-channel MAC protocol based on IEEE802.15.4was designed throughthe above research and experiment, which not only provided a new research idea andmethod for the industrial application of wireless sensor network, but also provides atheoretical basis for research of multi channel MAC protocol.