Low power MAC protocols for infrastructure wireless sensor networks

Abstract: This paper addresses low power MAC pro-tocols for the downlink of infrastructure wireless sensor networks. We are interested in the trade-off between power consumption and transmission delay, focusing on low traf-fic. We describe WiseMAC (Wireless Sensor MAC), a new protocol for the downlink of infrastructure wireless sen-sor networks. Another original contribution is the anal-ysis of the performance of PTIP (Periodic Terminal Initi-ated Polling). Here, polling is used in the reversed direc-tion as compared to common polling protocols. WiseMAC and PTIP are compared with PSM, the power save proto-col used in both the IEEE 802.11 and IEEE 802.15.4 Zig-Bee standards. Analytical expressions are given for the power consumption and the transmission delay for each protocol, as a function of the wake-up period. It is shown that WiseMAC provides, for the same delay, a significantly lower power consumption than PSM. Although less energy efficient than WiseMAC and PSM, it is shown that PTIP can, thanks to its implementation simplicity, become at-tractive for applications tolerating large transmission de-lays1.