Resolution-Adaptive Hybrid MIMO Architectures for mmWave Communication
Moving to a millimeter wave (mmWave) spectrum in range of 30-300 GHz enables the utilization of multi-gigahertz bandwidth and offers an order of magnitude increase in achievable rate. The small wavelength allows a large number of antennas to be packed into transceivers with very small antenna spacing. Leveraging the large antenna arrays, mmWave systems can manipulate directional beamforming to produce high beamforming gain, which helps overcome large free-space pathloss of mmWave signals.
Problems with hardware cost and power consumption, however, arise from deploying large antenna arrays coupled with power-demanding ADCs. To overcome these challenges, hybrid analog-digital processing architectures that attempt to reduce the burden of fully digital processing, and receivers with low-resolution ADCs have attracted the most interest in recent years.
To take advantage of the two considered architectures, WNCG Professor Brian L. Evans, WNCG student Mr. Jinseok Choi, and Huawei Baseband SOC CTO Dr. Alan Gatherer propose a hybrid massive-MIMO architecture with resolution-adaptive ADCs for mmWave communications. They investigate the ADC bit-allocation problem to minimize the quantization distortion of received signals by leveraging the flexibility of ADC resolutions. A derived closed-form bit-allocation solution reveals that the optimal number of ADC bits increases logarithmically proportional to the RF chain's SNR raised to the 1/3 power given the ADC power constraint. The proposed algorithm that utilizes the solution outperform the conventional fixed ADCs in terms of both the sum rate and energy efficiency in the mmWave communication environment.
This research was supported by Huawei Technologies.
J. Choi, B. L. Evans and A. Gatherer, ``Resolution-Adaptive Hybrid MIMO Architectures for Millimeter Wave Communications'', IEEE Transactions on Signal Processing, vol. 65, no. 23, pp. 6201-6216, Dec. 2017, DOI 10.1109/TSP.2017.2745440.