Research And Advancement Of IEEE802.15.4 Network Based On Time-Sensitive Applications

IEEE 802.15.4 is a standard designed for low-rate WPAN provides under the demand of low-date-rate applications, with the feature of low power, low complexity, low data rate, short range, low cost etc. As a novel wireless network standard, the research of IEEE802.15.4 generally focus on the model building, Performance Evaluation and low power consumption whereas the research on the other feature and particular applications is quite rare.The paper focused on the research and advancement of IEEE 802.15.4 network for the time-sensitive applications, with two pivotal components of data transmission and network association respectively.Firstly, the paper introduced PHY and MAC layers of IEEE 802.15.4, and especially, presented the IEEE 802.15.4 network function in detail. Based on the deep analysis and research on the IEEE 802.15.4 standard, the paper compared Guaranteed Time Slot (GTS) mechanism with other transmission mechanism of IEEE 802.15.4 and consequently drew the primary conclusion that GTS mechanism fit the Real-time applications. Furthermore, network calculus which is the novel mathematic network analysis tools was introduced to analyze the network delay feature of GTS. By the means of representing the mathematical derivation and expressions of the GTS delay bound, the paper pointed out the optimal GTS parameter on varies of occasions for the real-time applications.On the other hand, owing to find that a long network association delay is a critical problem in some time-sensitive applications, this paper proposes a new association scheme named fast association mechanism (FAM). By NS2 simulation results, FAM scheme shortens the association delay by 90%and 80%compared with the standard scheme respectively in two steps of association process. The effect of improvement is very obvious, and makes the wireless sensor network be applied to time-sensitive applications.Finally, based on the ZigBee development platform, the real system was designed and implemented for the improvement of the IEEE802.15.4 network association mechanism. The paper presented the hardware and software environment of Jennic ZigBee development platform. Following that, the paper proposed the system design proposal including occasion design, selection of time counting and format redefinition of the MAC data frame while represented the design cycle of the system software and designment and implement of Supervisory Computer. Ultimately, the measurement of the real system presented the similar results with NS2 simulation.