Capacity Scaling for Cloud Radio Access Networks with Limited Orthogonal Fronthaul

Uplink and downlink cloud radio access networks are modeled as two-hop K-user L-relay networks, whereby small base-stations act as relays and are connected to a central processor via orthogonal fronthaul links of finite capacities. Based on noisy network coding and distributed decode-forward inner bounds on the capacity regions for uplink and downlink, respectively, the total fronthaul link capacity required to approach the centralized MIMO sum-rate is characterized. The capacity scaling law when the network size increases is examined under certain uplink and downlink network models, both theoretically and via simulations.