A New GTS Allocation Scheme in IEEE 802.15.4 Sensor-Actuator Networks

Due to construction and maintenance ease, wireless networked control systems have gained a lot of popularity. Currently a lot of wireless communication protocols are available which can be used in wireless control systems. For example, IEEE 802.15.4 has gained a lot of attention, it presents the advantage to fit different requirements of applications by setting its parameters. When used in beacon-enabled mode, it ensures real-time guarantees by using Guaranteed Time Slot (GTS) mechanism. In this mode, the Personal Area Network (PAN) coordinator reserves and assigns the GTS to end devices on a first come first service (FCFS) basis in response to the request of the end devices. However, the standard protocol has a limitation that the coordinator can allocate up to only seven GTSs to end devices. Moreover, the fixed number and the fixed length of GTS duration offered by the standard protocol may not meet the stringent timing requirements of hard real time applications, and always make the GTS utilization inefficiently. In this paper, a new GTS allocation scheme for IEEE 802.15.4 network is proposed, which can improve the bandwidth utilization of the GTS and allow sharing GTSs among more than seven end devices.