Research On QoS Guarantee In Wireless Multimedia Sensor Networks

The availability of low-cost hardware such as CMOS cameras and microphones hasfostered the development of Wireless Multimedia Sensor Networks (WMSNs), i.e.,networks of wirelessly interconnected devices that are able to ubiquitously retrievemultimedia content such as video and audio streams, still images, and scalar sensor datafrom the environment. To provide quality of service（QoS）for these various traffics,enormous challenges need to be solved. Service differentiation is used for traffic to beassigned priority with the application requirements, ensuring that more network sources areused for the higher prioritized traffic. Cross layer method has been used to optimize thelimited resources of the sensor networks with the available parameters and technologies ofevery layer. Based on service differentiation and cross layer optimization, some newmethods and strategies are proposed for wireless multimedia QoS support. The main workcan be expressed as follows:To the flat network structure, service differentiation with the real time requirements ofthe application, also with cross layer method of physical layer, MAC layer and networklayer, an energy efficiency and real time communication mechanism was proposed. Withreceived signal strength the sensor networks were layered. The priority of the packet wasassigned on it’s per hop deadline and the current nodes’ residual energy. Polling contentionperiod based prioritized MAC was uesed to reduce the competition number of nodeseffectively. Receiver with more residual energy and higer traversal speed was used toforward the packet dynamically. To avoid congestion, simple policies such as admissioncontrol and early-drop miss deadline packets were used. Simulation results have shown thatthe new mechanism has the better performance in terms of packet delivery rate, end-to enddelay and network lifetime.With effective parameters of cross layer for WMSNs QoS routing model, multi-antand multi-path routing algorithm was proposed for the optimal route that satisfied QoSmetric. CANT was used to support WMSNs’ scalability and susutianable energy of thenodes. FANT, BANT and VANT were used for the optimal path and video transmission.MANT was used to deal with problems of congestion and link failure. Path that satisfyingthe requirements of the application was set more pheromones to attract more ants, instead of evaporating pheromone to avoid more ants visit. Simulation results have shown that thenew algorithm has the better performance in terms of packet delivery rate, end-to end delayand routing overhead, especially the video traffic’s average peak signal to noise ratio withthe multi-path.Assigned priority for the traffic combined with cross layer method include MAC layerand transport layer, a new congestion control approach was proposed to support WMSNswith throughput and delay. Congestion index and residual memory were used for detectionthe congestion. By inviting new types of control frames in MAC, the new mechanism hasgranted the receiving nodes permission to reject the sender’s data, protecting higher prioritytraffic and also protecting the nodes against local congestion. According to the detection ofrate error, input rate was adjusted by the priority of the node to avoid global congestion.With random service time, some nodes of failure and local congestion, simulation resultshave shown better performance than CCF and PCCP.