Iterative Collision Recovery for OFDM based WLAN

In this paper, we propose an Iterative Collision Recovery (ICR) method to significantly alleviate the hidden terminal problem in OFDM based Wireless Local Area Networks (WLAN). We prove that when hidden terminal exists, more than half of the overall collisions are repeated because of the retransmission and binary exponential backoff mechanisms in IEEE 802.11. ICR is designed to recover the repeatedly collided packets by iterative cancellation. ICR first reconstructs the collided packets and gets an interference suppressed estimation of the transmitted signal. Then the estimation is iteratively updated by Successive Interference Cancellation (SIC) technique to fully decode the whole packets. Mathematical analysis of a network with two hidden nodes shows that the system throughput can be improved by 80% when ICR is utilized. Simulation results illustrate that the Bit Error Rate (BER) of ICR is much lower than that of Zigzag, and ICR is more suitable for OFDM based WLAN system.