Research On Real-time MAC Protocol For Wireless Multimedia Sensor Networks

Along with the increasingly complex and variable monitoring environment, the simple data obtained from the traditional Wireless Sensor Networks (WSN) can not meet the overall demand of the environment monitoring. In order to achieve the comprehensive and effective environment monitoring, it's urgently needed to introduce the media with abundant information such as images, audio, video etc. into the sensor networks-based environment monitoring. And the Wireless Multimedia Sensor Networks (WMSN) is a new sensor network with the information perception performance which introduces multimedia such as audio, video, images into the traditional WSN. Because of the abundant information, it has a broader application prospect. In this paper, the important issue QoS in WMSN is taken as the research background and the MAC protocol which supports QoS in the typical application environment is studied. The main work is as follows:Based on the analysis of the MAC protocols in the traditional WSN and QoS requirement in WMSN, a multi-channel real-time MAC protocol StreamPathMac using time reservation is proposed according to the data features of the two service modes. The protocol uses two-level network architecture based on single-hop clusters and combines the competition mechanism with the scheduling mechanism, and it not only ensures the timeliness of two kinds of data, but also takes the energy efficiency and the streaming jitter processing into account. StreamPathMac establishes a time slots reservation based flow path from the source node to the convergent node before responding to the streaming media inquiries, thereby it can minimize each channel access delay while transmitting the data package.In order to simulate and evaluate the protocol in this paper, the simulation platform OMNeT++ with Mobility Framework have been expanded to meet the application scenarios of WMSN. In addition, in order to construct a network model for the protocol, firstly the typical clustering algorithm HEED is implemented, and then the Minimum Hops Routing protocol is extended to support broadcasting over all cluster heads.Based on the above work, the protocol-StreamPathMac is implemented on the simulation platform and the performance of the protocol is studied in aspects including the end-to-end delay and delay jitter of streaming data packet, the response time of streaming media query, the end-to-end delay of report data packet, and the energy consumption of the source node during a streaming media query. The simulation result shows that the protocol significantly reduces the end-to-end delay and delay jitter of streaming data, and has achieved better energy efficiency.