mmWave Massive MIMO with Simple RF and Appropriate DSP

摘要

There is considerable interest in the combined use of millimeter-wave(mmwave) frequencies and arrays of massive numbers of antennas (massive MIMO)for next-generation wireless communications systems. A symbiotic relationshipexists between these two factors: mmwave frequencies allow for densely packedantenna arrays, and hence massive MIMO can be achieved with a small formfactor; low per-antenna SNR and shadowing can be overcome with a large arraygain; steering narrow beams or nulls with a large array is a good match for theline-of-sight (LOS) or near-LOS mmwave propagation environments, etc.. However,the cost and power consumption for standard implementations of massive MIMOarrays at mmwave frequencies is a significant drawback to rapid adoption anddeployment. In this paper, we examine a number of possible approaches to reducecost and power at both the basestation and user terminal, making up for it withsignal processing and additional (cheap) antennas. These approaches includelowresolution Analog-to-Digital Converters (ADCs), wireless local oscillatordistribution networks, spatial multiplexing and multistreaming instead ofhigher-order modulation etc.. We will examine the potential of these approachesin making mmwave massive MIMO a reality and discuss the requirements in termsof digital signal processing (DSP).