Performance of space orthogonal resource transmit diversity for delay spreads in PUCCH using cyclic shift CDMA

This paper investigates the block error rate (BLER) performance of space orthogonal-resource transmit diversity (SORTD) against delay spreads for the physical uplink control channel (PUCCH) in the Long-Term Evolution (LTE) uplink using discrete Fourier transform (DFT)-precoded orthogonal frequency division multiple access (OFDMA). Channel estimation accuracy using a reference signal (RS) becomes a bottleneck to achieving a high diversity gain from SORTD under the highly channel-loaded conditions. This is because the inter-code interference due to frequency selectivity deteriorates the channel estimation accuracy particularly in a longer delay spread channel. Hence, we investigate the combined effect of SORTD and hybrid RS multiplexing using block spread (BS) and cyclic shift (CS) for a larger number of multiplexed PUCCHs such as K = 12. Computer simulation results show that SORTD particularly combined with hybrid RS multiplexing is effective in decreasing the required received signal-to-noise power ratio (SNR) that satisfies the target BLER for the PUCCH in the LTE uplink.