Research On Distributed Energy-efficient TDMA Protocol For Wireless Sensor Networks

Wireless Sensor Network(WSN)is a multi-hop ad hoc network system formed by wireless communication in a large number of micro sensor nodes deployed in the monitoring area.The purpose is to collaboratively perceive,collect and process information on the monitored objects in the network coverage area and send them to the end user.Different from traditional wireless network,the most important feature of wireless sensor network is the ability to achieve the longest survival time under limited resource conditions.Therefore,one of the main factors restricting the wireless sensor network is power consumption.The medium access control(MAC)protocol determines how to allocate limited wireless communication resources between sensor nodes,which directly affect the performance of wireless sensor networks.And the existing MAC protocol is not well applied to wireless sensor network.It is the focus of the present study to propose a good MAC protocol to make a compromise between energy efficiency and network performance.Firstly,in order to solve the problem that BMA(Bit-map-assisted)protocol has idle listening and large energy consumption,and E-BMA(Energy-efficient Bit-mapassisted)protocol has high latency of data transmission,a new MAC protocol named LL-BMA(Low-latency Bit-map-assisted)was proposed,which maintain high energy efficiency basically and reduce transmission latency significantly as well.To reduce idle listening of contention period and latency of data transmission,this protocol divided the process of node reserve data slot into two ways,making reservation through piggybacking and making reservation through contention period.Secondly,to improve the scalability of the protocol,we also propose a MAC protocol based on TDMA(Time Division Multiple Access)named SR-BMA(Scalable and Reservable Bit-map-assisted)protocol.Compared with the traditional protocol,the protocol sets the data slot to a smaller size,the number of data slots is more than the number of nodes,CH allocates the corresponding number of data slots according to the data request of the source nodes,in this way it can improve the utilization of data slot greatly.We optimize knapsack algorithm,the optimization algorithm is a good way to avoid large latency and to ensure fairness.To reserve data slot of the next session for source node which is not allocate data slot successful can reduce control.Then,through MATLAB simulation software,according to the number of nodes,the number of frames,the probability the events happened and packet size,we carry out simulation analysis from the average energy consumption of node and the maximum transmission latency,the results shows: comparing among TDMA,BMA and E-BMA,LL-BMA protocol can compromise relationship of latency and energy efficiency,only a fraction of energy consumption can it reduce the latency of data transmission effectively.And comparing with BEST-MAC(Bitmap-Assisted Efficient and Scalable TDMA-Based MAC)protocol,SR-BMA protocol reduces the control overhead,thus reducing the energy consumption,while using the optimization algorithm of knapsack algorithm,it can reduce the maximum transmission delay significantly.Finally,we compare the two protocols proposed.The results show that the LLBMA protocol is more suitable for the network which topology is stable,and the SRBMA protocol is more scalable and can be applied to the dynamic changes of the network topology.