Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-06-19 Cooperative journals: 《计算机应用研究》
Abstract： To increase the performance of throughput for 802.15.4 network, this paper designed an improved process of node state transition. Movever, it proposed a model of node access channel considering the hidden terminal problem and retransmission, and it carried out the analysis and calculation of model. Based on the calculation results and the analysis of channel state model, Then, it gave out the derivations of the data collisions probability、packet lost rate and throughput channel considering the hidden terminal problem. Finally, it studied the impact of packet arrival rate、backoff exponent and hidden terminal on the performance of network throughput. Experimental results show that, compare with 802.15.4 network without retransmission mechanism, the network throughput is increased by 83.9% or so. Compare with the sleep methods under some conditions, the network throughput is increased by 13.3% on average, the proposed model can effectively improve network throughput performance.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-05-18 Cooperative journals: 《计算机应用研究》
Abstract： In order to reduce the packet lost rate in 802.15.4MAC layer, this paper raised a model of channel competition mechanism based on Markov chain by analyzing the reason of packet loss rate. Then, throught the mathematical derivations of the steady-state probability on the network transmission, backoff and the channel detection state based on the model of channel access, this paper燿iscussed the formulas of channel collision and the frame packet lost rate. Finally, this paper studied the impact of protocol parameters such as packet arrival rate, the number of nodes, bit error rate, backoff exponent, and number of backoffs on the collision probability and the packet lost rate. Experimental results show that, compared with 802.15.4 network without node sleep state, the packet lost rate was reduced by 23.7%. And the model describes the MAC layer channel access mechanism very well, and reasonable settings for parameters could optimize the frame packet lost rate. The research outcome could provide reference for the reliable transmission optimization in the practical application of wireless sensor network.
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