# Capacity Bounds on the Downlink of Symmetric, Multi-Relay, Single Receiver C-RAN Networks

## TL;DR

This paper derives capacity bounds for symmetric multi-relay C-RAN downlink networks, using coding techniques and auxiliary variables, and characterizes capacity in key regimes.

## Contribution

It introduces new capacity bounds for symmetric multi-relay C-RANs and demonstrates their tightness in certain operational regimes.

## Key findings

- Bounds meet and characterize capacity in specific regimes
- Marton's coding achieves the lower bound
- Ozarow's technique provides the upper bound

## Abstract

The downlink of symmetric Cloud Radio Access Networks (C-RANs) with multiple relays and a single receiver is studied. Lower and upper bounds are derived on the capacity. The lower bound is achieved by Marton's coding which facilitates dependence among the multiple-access channel inputs. The upper bound uses Ozarow's technique to augment the system with an auxiliary random variable. The bounds are studied over scalar Gaussian C-RANs and are shown to meet and characterize the capacity for interesting regimes of operation.