An adaptive interleaving access scheme (IAS) for IEEE 802.15.4 WPANs

The key features of IEEE 802.15.4 wireless personal area network (WPAN) standard are the low data rate, short transmission distance, and low power consumption. The WPAN consisting of coordinator and device nodes is often established for monitoring the environmental information in a periodic fashion. The most critical issue of IEEE 802.15.4 WPAN is the capability of dealing with real-time or near real-time services, which require the limited latency and delay jitter. Two parameters, named as beacon order (BO) and superframe order (SO), are defined to control the superframe length as well as the active and inactive periods in superframe. However, using two parameters is very difficult to achieve deliver smooth and constant data stream from device nodes to coordinator. Although standard allots a portion of active period to be the guarantee time slots (GTS) for real-time services, the access interval of real-time frames is still affected by the assigned superframe length. Instead of using the inefficient GTS scheme, this paper proposes an adaptive interleaving access scheme (IAS) with a parameter interleaving order (IO) to adjust the superframe structure such that the active portion is spread over entire superframe in order to control the access latency as well as the bandwidth wastage. The simulation results demonstrate that the proposed IAS not only decreases average data renew interval (i.e. access latency) but also increases the battery lifetime of device nodes.