Optimized HCCA schedulers for an IEEE 802.11e/AFDX hybrid network

Abstract

This paper proposes a new HCCA scheduling scheme for AFDX (Avionics Full DupleX switched Ethernet) traffics on IEEE 802.11e Wireless LAN (WLAN). The AFDX requirements are related to the temporal constraints (end-to-end latency and jitter). Our scheduling algorithm AWS (AFDX Wireless Scheduler) improves the HCCA reference scheduler (RS); in order to convey AFDX traffic on IEEE 802.11e wireless network. Notice that, the HCCA reference scheduler is more suitable for CBR (Constant Bit Rate) traffics. AWS is based on the priority class, on the frame retransmission management, on the EDF (Earliest Deadline First) algorithm and on the maximal jitter. We also present, in this paper, an optimized version of AWS (OAWS) which uses the un-used bandwidth of TXOPs to transmit frames in critical or retransmission state. The simulation results show that we have a very large reduction of dropped packets (reached deadline) with AWS compared to RS, and the OAWS performances are better than AWS performances.