An intelligent secondary MAC protocol using shared spectrum with IEEE802.11 wireless LAN

In this paper, we have proposed a MAC protocol for secondary system overlaying to the primary wireless LAN (PU: Primary User). This MAC protocol can achieve protecting the communication of the primary system and improving the throughput of the secondary system (SU: Secondary User). A conventional wireless LAN uses CSMA/CA MAC protocol which can share the same spectrum among multiple nodes. However, CSMA/CA has a hidden node problem, which causes serious quality degradation of transmission. Although amount of works address this problem, any method cannot solve it completely. In this paper, we classify a hidden node problem and reveal mutual interference patterns between PU pair and SU pair. The proposed method collects the information of the mutual interference and store at a database. By using the database, the transmit parameters of SU MAC protocol are adaptively changed. We confirm superiority of the proposed MAC protocol by using computer simulations.