Distributed Receive Beamforming for Multi-Satellite Networks With Multiple Ground-Based Nodes Under Fronthaul Constraints

Abstract

Future multi-satellite networks can enhance downlink reliability through cooperative reception at geographically distributed ground nodes (GNs), but limited fronthaul restricts centralized signal collection and instantaneous channel state information (CSI) exchange. We develop distributed beamforming where GNs combine local and quantized soft-symbol estimates over multiple stages. We derive stage-wise signal-to-interference-plus-noise ratio (SINR) expressions accounting for quantization-noise accumulation, pilot contamination, and residual phase errors. We formulate a fronthaul-aware max–min design of forwarding, quantization rates, and combining weights, and propose stage-decoupled multistage design (SDMD) and threshold-based weak-user forwarding (TWF). Results show that SDMD achieves the highest worst-user spectral efficiency (SE) among distributed schemes, while TWF provides lower-complexity gains; excessive forwarding yields diminishing returns due to accumulated quantization noise.