Backhaul Reliability Analysis on Cluster-Based Transmit Diversity Schemes in Private Networks

For a multi-cluster-based transmit diversity scheme that supports joint transmissions (JT) in private networks, a distributed remote radio unit system (dRRUS) is deployed in each of the clusters to increase the spectral efficiency and coverage, and to achieve flexible spatial degrees of freedom. Due to its distributed structure, the dRRIJS relies on backhaul communications between the private network server (PNS) and cluster master (CM), which is the main backhaul communication, and between the CM to remote radio units (RRUs), which is the secondary backhaul communication. Thus, this paper mainly investigates the reliability of main and secondary backhaul connections for cluster-based transmit diversity schemes in private networks. Employing a Bernoulli process to model each backhaul reliability, a composite backhaul connection is modeled by an independent product of Bernoulli processes. By employing the distributed cyclic delay diversity scheme over the dRRUS and precision time protocol for clock synchronization, the multi-cluster-based JT can be achieved without full channel state information of the private network environment at the PNS and CMs. Having developed necessary distributions for the signal-to-noise ratio realized at the receiver, the closed-form expressions for the outage probability and spectral efficiency are derived. To verify their accuracy, the analytical performances are compared with link-level simulations.