Research On Uplink Scheduling Algorithm In Wireless Multi Media Sensor Networks

Wireless Sensor Networks(WSNs)have been widely deployed in monitoring and surveillance areas.With the improvement of sensor nodes'processing capability,some sensor nodes are equipped with multi-media devices,such as cameras that are capable of retrieving video and audio streams,thus multi-media transmission in WSNs has become a new trend.The uplink of wireless sensor network is responsible for transmitting the data to the central node.Sensor nodes have many constraint conditions such as processing capability,buffer size and power supply,while multi-media has strict Quality of Service(QoS)requirements,which calls for efficient resources allocation algorithm that could guarantee the multi-media QoS requirements and network life time.The research of resources allocation algorithm in wireless multi-media sensor networks has practical significance.We will study this problem in this thesis.The main work is as follows:Firstly,we present a utility-based scheduling algorithm for wireless multi-media sensor networks.The algorithm transfer the scheduling problem into a utility function maximization to guarantee multi-media stream Qos requirements.The proposed algorithm includes the following aspects:first,predict the incoming data of the next slot by a semi-markov model to reduce the packet loss caused by buffer overflow.Then,we design a utility function joint considering the buffer condition,energy condition and multi-media emergency level.Finally,the algorithm scheduled the sensor with max utility function.Simulation results show that the proposed algorithm can achieve better performance compared to Crankshaft in terms of guaranteeing the end-to-end delay and packet loss of multi-media stream.Secondly,we propose a subcarrier allocation algorithm with resource reservation in order to guarantee the system throughput and QoS requirements of multi-media sensor.The proposed algorithm includes the following aspects:first,we analysis the requirements of different media streams and make a resource reservation for the multi-media sensors.Then we allocate subcarrier for the multi-media sensor with the improved Max-Min subcarrier allocation algorithm.Finally,we allocate the subcarriers for other sensors with greedy algorithm.Simulation results show the proposed subcarriers allocation algorithm with resource reservation can guarantee the QoS requirements of multi-media stream and achieve a better system throughput.