LLC-Level FEC Scheme in IEEE 802.11 WLAN

In this paper, we apply a forward error correction (FEC) technique to the logical link control (LLC) layer in order to improve the reliability of IEEE 802.11 wireless local area network (WLAN). This approach, named LLC-level FEC, makes it possible to implement the robust FEC functionality without modifying the off-the-shelf WLAN hardware. Moreover, a WLAN device implementing our scheme can still maintain the interoperability with legacy devices since a specific field in the LLC/SNAP header is exploited. Two different versions of LLClevel FEC scheme are proposed since some parts of MAC header can be protected further in the LLC layer via a cross-layer approach. Their theoretical error performance is studied based on the bit error probability of the modulation and channel coding schemes of the 802.11a physical layer (PHY). Finally, both analysis and simulation results demonstrate that substantial gain in terms of packet error probability could be obtained. Keywords-802.11, RS coding, logical link control (LLC)