Research On Low-power Consumption MAC Protocol And Cross-layer Optimization In Wireless Sensor Networks

With the development of communication and computer technology,wireless sensor networks have gained unprecedented attention and have been widely used.The small,light,and low-cost sensor nodes deployed in the environment transmit and collect data to the sink nodes.The data is then transmitted to the user terminal using the Internet or satellite.The advantages of miniature sensor nodes also limit their working time and ability.Today,battery technology has not made breakthrough progress,how to make sensor networks serve people for a longer time is an urgent problem.In the wireless sensor network protocol stack,the MAC layer protocol determines the way the node accesses the channel and controls the communication module with the highest energy consumption.Therefore,a well-designed MAC protocol is very important to improve network survival time.This thesis first analyzes the main working mechanism and disadvantages of the SMAC protocol,and proposes the NSMAC protocol.In the SMAC protocol,the fixed contention window and duty cycle mechanism make it difficult to apply the protocol to dynamic changes in load,especially in networks with high load and large scale.Therefore,in the NSMAC protocol,the contention window can be flexibly adjusted according to the number of data packets in the node's cache queue,avoiding the situation where the choice of the backoff time does not match the network load.Then,the average growth rate of packets in the queue is used as an indicator to dynamically adjust the duty cycle.Simulation results show that the NSMAC protocol has a very good energy efficiency performance in networks with dynamically changing loads,while delays and throughput have also improved.Next,this thesis studies the idea and method of cross-layer design and designs the CLSMAC protocol.This protocol first improves the routing algorithm,making the load distribution of the network more balanced.Then optimize the handshake mechanism of the sensor network MAC protocol,so that data packets can be transmitted in multiple hops within a scheduling period.Through the above two measures,the CLSMAC protocol can greatly reduce the idle listening time of nodes,and reduce the probability of collision and crosstalk.Simulation results show that the CLSMAC protocol effectively reduces the average energy consumption of the network when the network load is large.The protocol also enables significant improvements in latency and throughput.Finally,summarize the full text and the more valuable research directions of MAC protocols in wireless sensor networks are prospected.