Adaptive Research On Medium Access Control Protocol For Wireless Sensor Networks

Wireless sensor network MAC (Medium Access Control) protocol mainlycontrol nodes access to the channel and redistribute the channel when itconflict. MAC protocol is the main part of the data link layer, between thephysical layer and network layers. Through the management of channelresources, the MAC protocol can orderly and full use of media resources totransmit data, so the nodes can increase network throughput and reduceenergy consumption. Therefore a good MAC protocol should ensure channelutilization at the same time, equitable distribution of channel resources, toprotect the efficient communication between the sensor network nodes.In this paper, we set the adaptive of wireless sensor network as the researchtarget, analyze the MAC layer protocol and try to improve it, assure the nodesmake full use of their energy and also increase the efficiency on the wholenetwork, the main contribution of this paper is as follows:1. Analysis the performance of typical routing protocol with the SMAC.Since the characteristic of the sensor network is different from traditionalwireless network, the existing wireless routing protocol cannot be perfect usedin sensor networks, so we analysis the existing typical routing protocol withSMAC protocol and observed network overall performance indicators, try tofind out the most suitable routing protocol for SMAC protocol under differenttopology structure, provide some basis for the next step improve experiment.2. Dynamic duty cycle adjustment mechanism. SMAC protocol for wirelesssensor network cannot adapt to the dynamic changes of the network load,leading to network packet loss and delay jitter, so D-SMAC protocol isdesigned to solve these problems. The protocol based on packets in the queuewaiting time on average to predict the current network load conditions anddynamically adjust the duty cycle of nodes, thus achieving efficient use ofenergy while ensuring timely and reliable data transmission. The simulationresults show that the improved protocol can make effective use of the energy, and also ensure the network throughput, lower latency between end-to-endtransmissions.3. Dynamically adjust the contention window based on the residual energyand the number of channel conflicts. For the limited in energy and fixedcontention window, this chapter proposed a MAC protocol based on the noderesidual energy and channel conflict number (EC-SMAC).The protocol hasimproved the competition back off mechanism of SMAC, considering thenode remaining energy and channel conflict number to dynamically adjustcontention window to reduce the conflict between the transmission nodes, sothat the network can keep load balance, and extend the network lifetime. Thesimulation results show that in the premise of ensuring the networkthroughput and delay stability, EC-SMAC extended the network life time byan average of7%.