Interframe spacing adaptation method for IEEE 802.11 WLANs coexisting with IEEE 802.16 networks

In cognitive networks, secondary users (SUs) are regulated to prevent them from accessing a channel if primary users (PUs) are currently occupying the channel. However, there is no strict regulation about how to coordinate the channel access among multiple SUs belonging to heterogeneous networks with different channel access policies. In this paper, we consider the coexistence problem for two specific SUs of carrier sense multiple access (CSMA)-based IEEE 802.11 network and centralized scheduling-based IEEE 802.16 network. We propose an inter frame spacing (IFS) adaptation method that allows IEEE 802.11 SUs to fully utilize idle intervals between successive IEEE 802.16 frames while not interfering with the following IEEE 802.16 frame. Through various simulations, we show that our proposed method significantly improves the throughput of IEEE 802.11 networks without harmful interference to IEEE 802.16 systems.