On the Benefit of Forward Error Correction at IEEE 802.11 Link Layer Level

This study examines the error distribution of aggregated MPDUs in 802.11n networks and whether or not forward error correction like raptor coding at the link layer would be useful in these networks. Several experiments with Qualcomm 4x4 802.11n hardware were performed. Two devices were used in a data link, while a third device sniffed all transmitted packets. The collected data was analyzed and used to calculate the packet error rate which would be obtained if FEC was used in order to determine whether FEC is useful at the link layer. It is shown that the error distribution of A-MPDUs does not follow the binomial distribution. Because of this, the performance of FEC in real networks is worse than for theoretical cases where a binomial distribution is assumed. Therefore, other ways to decrease the packet error rate have more impact than forward error correction.