Efficient Low-Resolution ADC Relaying for Multiuser Massive MIMO System
Peihao Dong, Hua Zhang, Wei Xu, Xiaohu You · IEEE Transactions on Vehicular Technology · 2017
In this paper, we investigate a multiuser massive MIMO amplify-and-forward relay uplink, where low-resolution analog-to-digital convertors (ADCs) are used at the relay station (RS). Both the base station (BS) and the RS are equipped with large numbers, i.e., NBand NR, respectively, of antennas. For both perfect and imperfect channel state information (CSI), we derive closed-form sum rate expressions with respect to finite NBand NR. Under some mild assumptions, we demonstrate that sum rates with perfect and imperfect CSI, respectively, increase with α and α2both logarithmically, where α is linear quantization gain of ADCs at the RS. We show that low-resolution, e.g., 2-3 bits, ADCs only cause limited sum rate loss when NBand NRare relatively large compared to the number of users, i.e., K. Based on the obtained sum rate expressions, we further discover the generalized power scaling laws that guarantee a nonvanishing sum rate, as NBand NRgrow to infinity, where we find that low-resolution ADCs at the RS do not bring substantial impact on power scaling laws. Numerical results verify the correctness of our theoretical analysis and consequently justify the large-scale antenna arrays at the RS in a low-cost and energy efficient manner, yet still achieving considerable sum rate performance.