Multi-Antenna FSR Receivers: Low Complexity, Non-Coherent, Massive Antenna Receivers

Many 5G applications require low complexity transceivers that can exploit the benefits of massive antenna arrays while still maintaining low hardware, energy and computation costs. As a solution, this paper proposes a novel multi- antenna frequency shift reference (MA-FSR) receiver that uses only one down-conversion chain, supports single spatial-stream wide-band transmission with non-coherent demodulation, and can perform receive beamforming without requiring phase-shifters, explicit channel estimation, or complicated signal processing. In MA-FSR a reference tone is transmitted along with the data. At each receive antenna, the received signal for the data is correlated with the received signal for the reference, via a squaring operation, thereby compensating for the inter-antenna phase shift. The resulting signals are then summed and fed to a single down-conversion chain. In this paper, performance of the MA-FSR receiver is studied analytically and a near-optimal power allocation policy for the reference and data signals is proposed. Simulations suggest that the signal-to-noise ratio for MA-FSR is around 9 dB lower than that of coherent analog beamforming, although the bandwidth efficiency is also reduced to 50%. Several extensions to MA-FSR that can achieve better performance, though with a higher hardware cost, are also discussed.