C-RAN and Optical Fronthaul Latency in Representative Network Topologies

This paper presents a feasibility study aimed at understanding centralized radio access network (C-RAN) deployments based on incumbent distributed radio access network (D-RAN) topologies. A model is derived to allow realistic latency characteristics to be calculated for fronthaul connectivity between existing cell sites and transport network aggregation nodes (hubs) suitable for baseband centralization. Analysis has demonstrated that as much as 96% of urban cell site neighbor pairs could satisfy C-RAN fronthaul latency budgets if baseband processing were to be centralized at the local transport hub and 91% when centralized at the regional transport hub using single mode fiber. Findings suggest that the feasibility of advanced coordinated transmission schemes between such pairings could be realized based on existing real-world fiber deployment topologies. Furthermore, the proportion of sites that could support C-RAN requirements could be increased further to 97% when aggregated at local transport hubs and 95% at regional hubs where hollow core fiber transport solutions are employed.