Low-Latency Routing Scheme for a Fronthaul Bridged Network

Abstract

A fronthaul bridged network has attracted attention as a means of efficiently constructing the centralized radio access network (C-RAN) architecture. If we change the functional split of C-RAN and employ timedivision duplex (TDD), the data rate in fronthaul will become variable, and the global synchronization of front-haul streams will occur. This feature results in an increase in the queuing delay in fronthaul bridges among fronthaul flows. To address this problem, this paper proposes a novel low-latency routing scheme designed to minimize the worst-case delay in fronthaul networks with path-control protocols. The proposed scheme formulates the worst-case delay of each fronthaul stream based on the distribution of nodes, the propagation delay, and metric of the links. It selects the set of paths that minimizes the maximum value of the worst-case delay from the candidate path sets for fronthaul flows generated with the k-th shortest path algorithm. We confirmed with computer simulations that the proposed scheme can adequately minimize the worst-case delay, irrespective of the network topology. The maximum queuing delay is minimized by considering the time synchronization between fronthaul flows and the burst size determined by the TDD subframe length.