A robust real-time message scheduling scheme capable of handling channel errors in wireless local area networks

Abstract

This paper proposes and analyzes the performance of a robust real-time message scheduling scheme capable of handling channel errors by exploiting an auxiliary schedule on the IEEE 802.11 WLAN. While the primary schedule is derived from the legacy EDF (Earliest Deadline First) scheme, the auxiliary schedule is generated based on the slack and arrival times of each message stream. During runtime, with the support of a channel probing functionality, the access point dynamically switches the two polling schedules according to the channel status, giving a temporaily unreachable stream more chances to meet its time constraints. Simulation results show that the proposed scheme improves the success ratio by up to 8.56 % and performs well even if the length of error duration gets larger, demonstrating that it is also robust to the bursty errors.