On the Range Performance of Decode-And-Forward Relays in IEEE 802.11 WLANs

We consider a wireless local area network (WLAN) in the 5 GHz band. The coverage is one of the main challenges in high-frequency wireless systems and we focus on enhancing the coverage range of such a system by relaying. So far no relaying functions are defined in IEEE 802.11 medium access control (MAC). We introduce three simple MAC schemes for multihop communications and classify them based on delay, simplicity, capacity and application. We also point out the deficiency of the actual standard regarding multihop connections. We study the outage behaviour of a single input single output (SISO) two-hop link and improve it by developing a multiple input multiple output (MIMO) system. We investigate the tradeoff between coverage range and number of relays in a two-dimensional scenario. We also discuss the tradeoffs between having relays instead of adding more access points (APs) to the system and give an estimation of the number of required APs/relays to fully cover an area. In other words we show how much range one can gain from decode-and-forward (DF) relaying in a WLAN scenario