An Energy Saving Scheme with Error Recovery for Multi-Polling in Wireless LANs

Various multi-polling schemes have been proposed to reduce the overhead resides in legacy IEEE 802.11 WLAN protocols. In particular, the two-step multi-polling (TSMP) scheme utilizes the acquired buffer status and channel condition to derive exact required time of each wireless station. Consequently, it seems to be easy to incorporate an energy saving schedule to prolong the operating time of the portable devices. However, even though it adopted the concept of rate adaptation, the TSMP scheme did not take into account frame retransmissions caused by transmission errors due to, say, fading of the wireless channel. The uncertain time spent on retransmission of former stations in the schedule may introduce energy-consuming overhearing for later ones. In this paper, we propose wake-up time schedules and an adaptive updating algorithm to save more energy for the later stations under the error-prone wireless environment. The proposed scheme is simple and thus quite feasible. Besides, from extensive simulation results, we found that the proposed solution is effective.