Impact of Angular Spread and DOA Estimation on the Performance of Wideband CDMA Array-Receivers

Many research efforts were recently spent to address the challenging problem of DOA and angular spread estimation. However, to the best of our knowledge, no previous work has thoroughly investigated their specific impact on the performance of DOA-based antenna-array beamforming. In this contribution, we address this issue in the particular context of wideband CDMA using pilot-assisted or blind antenna-array receivers. In the process, we also assess whether the generalized channel-matched beamforming (i.e., without DOA estimation or a priori knowledge of the spatial structure of the channel) offers a better alternative. Link-level simulation results in terms of required SNR at target BER of 1% suggest that wideband CDMA array-receivers, whether pilot-assisted or blind, are extremely sensitive to angular spread mismatches and that the benefits of exploiting the spatial structure of the channel (i.e., estimation of DOA, angular spread, etc..) translate, at best, in negligible SNR gains when accurate channel identification is already implemented. These results call for implementing channel-matched instead of conventional DOA-based beamforming.