Collision resolution in pseudocellular WLANs with beamforming

Abstract

The paper provides a technique that can successfully recover data when collision occurs in pseudocellular wireless local area networks (WLANs). Pseudocellular WLANs use beamforming at the access point (AP). Mobile users send multiple data packets at the same time using different signature waveforms as in CDMA cellular network. Each user randomly chooses a signature waveform during the contention frame. If the same signature waveforms is selected by more than one user, a collision occurs. The proposed successive multiuser detection scheme with orthogonal ID sequence design enables the system to recover the data from collision. This helps to prevent mobile users from starting back-off timing due to failure in contention for the channel. Hence the total delay is lowered and the capacity of the system improves by a large amount under heavy traffic.