The paper revisits adaptive beamforming assisted receiver for multiple antenna aided multiuser systems that employ binary phase shift keying (BPSK) modulation. The standard minimum mean square error (MMSE) design is based on the criterion of minimising the mean square error (MSE) between the beamformer's desired output and complex-valued beamformer's output. Since the desired output for BPSK systems is real-valued, minimising the MSE between the beamformer's desired output and real-part of the beamformer's output can significantly improve the bit error rate (BER) performance, and we refer to this alternative MMSE design as the real-valued MMSE (RV-MMSE) to contrast to the standard complex-valued MMSE (CV-MMSE) design. The minimum BER (MBER) design however still outperforms the RV-MMSE solution, particularly for overloaded systems where degree of freedom of the antenna array is smaller than the number of BPSK users. Adaptive implementation of this RV-MMSE beamforming design is realised using a least mean square (LMS) type adaptive algorithm, which we refer to as the RV-LMS, in comparison to the standard CV-LMS algorithm. The RV-LMS adaptive beamformer is shown to have a similar computational complexity as the adaptive MBER beamforming implementation known as the least bit error rate (LBER), imposing only half of the computational requirements of the CV-LMS algorithm.
rv-lms adaptive beamformer,adaptive beamforming,bit error rate,adaptive mber beamforming implementation,alternative mmse design,complex-valued beamformer,minimum bit error rate,minimum mean square error,binary phase shift keying modulation,communication system,rv-mmse beamforming design,type adaptive algorithm,real-valued mmse,binary phase shift,adaptive implementation,mean square error,lms algorithm,least mean square,computational complexity,antenna array,degree of freedom
Least mean squares filter,Beamforming,Adaptive beamformer,Control theory,Antenna array,Minimum mean square error,Adaptive algorithm,Mathematics,Phase-shift keying,Bit error rate