A novel cross coding scheme for OFDM systems

In wireless OFDM-based systems, coding jointly over all the sub-carriers simultaneously performs better than coding separately per sub-carrier. However, the joint coding is not always optimal. In this paper, we propose a novel coding scheme based on fountain codes, which combines the separate coding and the joint coding over all the sub-carriers. The key element in the new proposed system is that each fountain-encoded packet is transmitted over a single sub-carrier. The packets can be discarded if they have encountered a low-energy channel. Fountain codes can recover the source data by using only the surviving packets. With this new approach, we have a gain of around 8.5 dB comparing to the FEC layer used in current WLAN standards (i.e. the IEEE 802.11a standard and the IEEE 802.11n standard).