SNR loss due to feedback quantization and errors in closed loop transmit diversity systems

The paper presents the performance degradation in terms of average signal-to-noise ratio (SNR) loss due to quantization of the optimum weights and due to errors in the feedback channel for a two transmit and one receive antenna diversity system. Closed-form expressions are derived and are used to determine the theoretical performance loss of the two closed loop transmit diversity modes as described in the 3GPP UMTS specification (see Technical Specification Group Radio Access Network, "Physical layer procedures (FDD)", 3GPP TS 25.214).