CDMA Non-Linear Interference Canceller with Multi-Beam Reception

In this paper, a multistage parallel interference canceller (MPIC) with multi-beam reception for a DS-CDMA system was proposed to suppress multiple access interference (MAI) effectively. Its aim is to reduce the computational complexity of the conventional MPIC cascaded with an adaptive array antenna. It employs multiple fixed beams based on phased array and selects suitable beams to demodulate the transmitted signal of each user. Then it suppresses residual interference signals by the MPIC cascaded with multi-beam receiver. Its bit error rate (BER) performance is evaluated by computer simulations assuming an uplink single-chip-rate variable spreading factor DS-CDMA system over exponentially decaying Rayleigh distributed 5-path channels. When 8 high-rate-users with spreading factor (SF) of 8 and 8 low-rate-users with SF of 32 coexist in an 120deg sectored single cell, the proposed receiver with 6-element receiving antenna and 2-stage MPIC is better than the conventional receiver. Its improvement is about 0.5dB for high-data-rate users and about 0.2dB for low-data-rate users in terms of the required E_b /N₀ to achieve an average BER of 10^-4, with the computational complexity of about three-fourth of the conventional receiver