Improve Uplink Achievable Rate for Massive MIMO Systems With Low-Resolution ADCs

Massive multiple-input multiple-output (MIMO) with low-resolution analog-to-digital converters is a sensible solution to cut down hardware costs and to achieve the optimal energy efficiency. In particular, 1-bit and 2-bit ADCs are the best choice for massive MIMO systems when both transmission power and the dissipation power of the ADCs are taken into consideration. Thanks to the bounded maximum error, low complexity, and robustness, the uniform scalar quantizer should be used to convert the analog amplitude signal to the discrete amplitude signal. In this paper, we optimize the truncation limits for the uniform scalar quantizer according to the resolution levels of the ADCs in order to minimize the overall quantization distortion. Ultimately, the achievable sum-rate of uplink multi-user MIMO (MU-MIMO) systems is significantly improved for the practical resolution level of the ADCs, especially for an extreme case of 1-bit ADCs. Experiments show that the optimized uniform scalar quantizer, on the one hand, can improve the sum-rate as much as 9 bits/s/Hz and 2 bits/s/Hz for 1-bit ADCs and 2-bit ADCs, respectively. On the other hand, the performance of the optimized uniform quantizer approaches the performance of the non-uniform quantizer at all considered resolution levels of the ADCs while possessing some advantages mentioned above.