Hybrid Precoding for Massive MIMO Systems in Cloud RAN Architecture with Capacity-Limited Fronthauls
arXiv:1709.07963
Abstract
Cloud RAN (C-RAN) is a promising enabler for distributed massive MIMO systems, yet is vulnerable to its fronthaul congestion. To cope with the limited fronthaul capacity, this paper proposes a hybrid analog-digital precoding design that adaptively adjusts fronthaul compression levels and the number of active radio-frequency (RF) chains out of the entire RF chains in a downlink distributed massive MIMO system based on C-RAN architecture. Following this structure, we propose an analog beamformer design in pursuit of maximizing multi-user sum average data rate (sum-rate). Each element of the analog beamformer is constructed based on a weighted sum of spatial channel covariance matrices, while the size of the analog beamformer, i.e. the number of active RF chains, is optimized so as to maximize the large-scale approximated sum-rate. With these analog beamformer and RF chain activation, a regularized zero- forcing (RZF) digital beamformer is jointly optimized based on the instantaneous effective channel information observed through the given analog beamformer. The effectiveness of the proposed hybrid precoding algorithm is validated by simulation, and its design criterion is clarified by analysis.
Submitted to IEEE Journal of Selected Topics in Signal Processing
References in corpus (9)
- An Overview of Signal Processing Techniques for Millimeter Wave MIMO Systems
- Channel Estimation and Hybrid Precoding for Millimeter Wave Cellular Systems
- A Coordinated Approach to Channel Estimation in Large-scale Multiple-antenna Systems
- Fronthaul-Constrained Cloud Radio Access Networks: Insights and Challenges
- On the Number of RF Chains and Phase Shifters, and Scheduling Design with Hybrid Analog-Digital Beamforming
- Hybrid Analog-Digital Channel Estimation and Beamforming: Training-Throughput Tradeoff
- Optimized Uplink Transmission in Multi-Antenna C-RAN with Spatial Compression and Forward
- Layered Downlink Precoding for C-RAN Systems with Full Dimensional MIMO
- Regularized ZF in Cooperative Broadcast Channels under Distributed CSIT: A Large System Analysis