As Time Slots In The Ieee 802.15.4 Csma / Ca Algorithm To Improve The Research And Performance Analysis

IEEE802.15.4 is a standard introduced for low-rate wireless personal area networks under the demand of low-date application. Although IEEE802.15.4 is one of the best standards for the present wireless sensor networks, it still needs further researches and optimizations to greatly meet the requests of wireless sensor networks. When wireless sensor networks are applied to real-time environment, high-priority packets should transmit as soon as possible, but IEEE 802.15.4 standard protocol itself does not support any priority mechanism. Then slotted CSMA/CA algorithm based on the priority concept is proposed.network nodes are considered as non-saturation, which is more practical significance.This thesis, firstly, analyzes the MAC protocol of the IEEE802.15.4 standard, and studies the facts which impact the standard's performance. Then the slotted CSMA/CA algorithm simulation model is established with OPNET software. Based on this simulation model, this thesis analyzes under different network loads the impacts of BO, BE, CW on the network performance of IEEE802.15.4, including throughput and average delay. In the rest part of this thesis, the concept of priority is introduced. Service-differentiation mechanism and Back-off count optimization strategy are proposed, and priority scheduling strategy is adopted, then a Priority-based analytical method for IEEE802.15.4 slotted CSMA/CA algorithm under non-saturation is proposed.A comprehensive mathematical modeling for the slotted CSMA/CA algorithm is established, including the node Markov model and channel Markov model, and the thesis analyzes the performance of slotted CSMA/CA algorithm which is improved.The simulation results show that slotted CSMA/CA algorithm based on the priority concept can effectively promote the real-reality of high-priority packets.