Research On Reliability Technologies Of Mobile Fronthaul Networks Based On Time-Sensitive Networking

With the rapid development of Internet and 5G technology,the way people live and work has a greatly change.Mobile network mainly consists of wireless access,fronthaul network,midhaul network,backhaul network,core network and cloud data center.Mobile fronthaul network is connected by RRU(Remote Radio Unit)and DU(Distributed Unit).Because of high data rates demand of CPRI(Common Public Radio Interface),mobile fronthaul network suffers from the bottleneck of transmission capacity.However,optical fronthaul solutions have some problems,such as poor statistical multiplexing ability,low bandwidth utilization and high network cost.Time-Sensitive Networking,based on the enhancements of Ethernet,is a series of technologies and standards,and the FRER(Frame Replication and Elimination for Reliability)mechanism is one of the key technologies for high reliability in TSN.FRER transmits duplicated frames through two disjoint paths and eliminates one copy at the destination node to improve the service reliability of critical data flow.However,the traditional FRER mechanism duplicates frames at the source node and eliminates redundant frames at the destination node,which brings unnecessary bandwidth waste to fonthaul network.Besides,FRER mechanism is not always easy to find two completely disjoint paths between the source and destination nodes.And it only considers paths with the shortest number of hops but without considering the properties of links when selecting the forwarding path.In order to solve the problem of frame replication and elimination nodes optimizing selection,we proposed the FRER mechanism based on frame replication and elimination node optimizing selection(FRER-NOS).The FRER-NOS mechanism considers the positions and attributes of switch nodes,including the proximity degree,degree centrality and load rate,taking them as the node selection metrics.Then the FRER-NOS mechanism transforms the problem of nodes selection into multi-objective optimization problem.And FRER-NOS utilizes Genetic Algorithm(GA)to compute and order the fitness of nodes,which realizes optimizing selection of nodes.Simulation results shows that the path reliability of the FRER-NOS improves 2.25% averagely compared to the shortest path(SP),and the bandwidth consumption ratio of FRER-NOS decreases 6.64% on average compared to the traditional FRER.In order to solve the problem of optimized FRER paths computation,we proposed the FRER mechanism based on multiple Cascaded Preconfigured Cycles(FRER-MPC).The FRER-MPC mechanism selects a working path based on the link priority model considering the properties of links,such as reliability,load,and centrality.Then FRER-MPC computes a redundant path based on multiple preconfigured cycles and merges P-Cycles with shared links to reduce the bandwidth consumption.Simulation results show that,compared to the SP and the traditional FRER,the path reliability of FRER-MPC(the hops of P-Cycles is 3)improves 2.03% and 3.50% on average respectively,and the average frame delay variation of the FRER-MPC(the hops of P-Cycles is 3)decreases 18.16% averagely compared to the FRER-MPC(the hops of P-Cycles is 4).In summary,this paper proposes the FRER-NOS and FRER-MPC mechanisms from two aspects: frame replication and elimination nodes selection,and two optimized paths computation,which effectively improves the path reliability of mobile fronthaul network based on TSN and reduces the extra bandwidth consumption.This paper provides technology solutions for the design of mobile fronthaul network.