Effects of hidden nodes in wireless local area networks

Abstract

The effects of hidden nodes in an omni-directional antenna based AP and in a multi-sector antenna based AP are analyzed, respectively. In an omni-directional antenna based AP network, the hidden nodes affect uplink traffic and the performance is degraded. In a multi-sector antenna based AP network, the hidden nodes affect downlink traffic and the performance is degraded. Hidden nodes may severely degrade the performance of wireless LANs. Focusing on the hidden node effect, we analyze goodput in a single cell WLAN environment with hidden nodes under a non-saturated condition. Uplink and downlink goodputs are analytically derived using an approximation technique and are compared with simulation results. We also propose a pseudo-TDD (Time Division Duplex) scheme to avoid downlink traffic collision in a multi-sector antenna based AP network. It improves downlink goodput performance.