Research And Advancement Of IEEE 802.15.4 Network Based On Real-Time Applications

Wireless sensor networks (WSN) technology is a cross-disciplinary high-tech in the field of modern information technology, which has a very wide range of applications in military, civilian and industrial areas. IEEE 802.15.4 protocol provides international standards for communication between nodes for WSNs, which has low rate, low cost, low power, high quality features. Currently the research of IEEE 802.15.4 generally focus on the model building, performance evaluation and low power consumption, whereas the research on the network features is quite rare, such as throughput, delay and packet loss rate.In this paper, we consider the delay sensitive for the WSNs in the real-time application fields, comprehensively analysis the IEEE 802.15.4 protocol, and make a deeply research for the Guarantee Time Slot Mechanism which the standard support for protection transmission. The paper use network calculus to analyze the delay boundary of GTS, get a rate-delay service curve and definition formula for delay limits. In the basis of First Come First Service scheduling strategy in standard, a new GTS scheduling algorithm based on delay priority is proposed. The New algorithm calculate the success rate, cache utilization and bandwidth usage of data packet which is to be send, evaluate the priority of packet, orderly responses the GTS request by priority and dynamically adjust the GTS slots, ensure real-time transmission and bandwidth utilization.Finally, we use the OPNET Modeler simulation tool model and analysis features for IEEE 802.15.4 network. The Modeler use the way of object-oriented simulation, establish corresponding node model for each class of nodes, included model for the physical layer, MAC layer and network layer. According to comparison and analysis simulation result between standard algorithm and improved algorithm, the results of experiments show the proposed mechanism could provide less delay and better transmission efficiency than the standard allocation method whereas without affecting the overall efficiency of the network.