A Dynamic Replication Scheme of User Plane Data over Lossy Backhaul Links

Abstract

5G networks are characterized by strict latency, jitter and reliability requirements. On the other hand, a lossy backhaul scenario where high packet losses over the backhaul transmission medium can render backhaul links unavailable for service consumption. This necessities a multi-transmission scheme over backhaul using the existing resources of the operators such as base stations and core networks. This can enhance reliability for 5G backhaul networks to meet the requirements of new 5G services that have strict end-to-end latency requirements. In this paper, we propose a GPRS Tunnelling Protocol User Plane (GTP-U) Protocol Data Unit (PDU) multitransmission scheme that achieves improved Transmission Control Protocol (TCP) latency and packet loss probability at the expense of higher resource (bandwidth) utilization compared to existing traditional systems. The scheme can use several measuring mechanisms such as continuous Two-Way Active Measurement Protocol (TWAMP) testing between core network and base stations, GTP-U user plane echo requests/replies or backhaul quality testing during evolved Packet System Radio Access Bearer (eRAB) establishment phase. This mechanism can also be applied to X2 interface between base stations to reduce the service latency and improve the backhaul link performance. Our simulation results using ns-3 indicate that by applying the proposed strategy in backhaul systems, the application level packet loss and TCP delay can be improved at the expense of the bandwidth improvement at certain drop or loss levels.

Network Coding Aware User Plane for Mobile Networks

“…• We propose a NC-enabled transmission strategy in the User Plane (UP) of mobile backhaul for networks operators, which operates in an iterative manner without requiring extra buffer for NC operations, • We derive analytical analysis and asymptotic behaviour of our proposed method, • Our simulation results in NS3 reveal that an average 1% loss ratio in the backhaul link creates 59,44% additional total transmission time compared to normal standard GTP-U transmission. In case NC is applied, the total transmission time increases by 52,99% and 56,26% for 1% and 2% NC ratio respectively compared to no coded transmission , and • In comparison with dynamic replication scheme presented in [4] with two replicated UP packets, the performance of proposed approach in terms of the total transmission time is better when coding rates are %1 and %2 while keeping bandwidth utilization at much lower ratios. Moreover after NC ratio of 5%, NC creates too much total transmission time which also match with our analytical calculations.…”

“…In our experimental setup, we compare no coding scheme (i.e. regular UE application re-transmission in case of data loss), NC with 1%, 2%, 5% and 10% coding rate and dynamic replication scheme of [4] with 2 packets replicated in the mobile backhaul network. The relevant metrics used for comparisons are total processing time and bandwidth utilization.…”

“…In a backhaul link where average 1% loss ratio exists, NC ratio of 5% seems upper limit providing benefit and after 5% NC ratio, coding creates too much T e2e time when compared with no coded transmission that allows re-transmission in the TCP session of the UE for the lost packets. Dynamic replication scheme presented in [4] with two replicated UP packets sent to the backhaul has T e2e of %157 and its performance is worse than coding rate %1 and %2. Additionally, the tested dynamic replication scheme doubles the used bandwidth.…”

“…1: A packet loss in UP results a re-transmission process in the application layer protocol. [4] concentrates on evaluating effect of replication of the lost UP packets when failures occur on mobile backhaul links of transport network. Although some of the advantages are presented in [4], the amount of generated bandwidth usage is too high during the replication process.…”

“…[4] concentrates on evaluating effect of replication of the lost UP packets when failures occur on mobile backhaul links of transport network. Although some of the advantages are presented in [4], the amount of generated bandwidth usage is too high during the replication process. Therefore, NC in the UP side may be more advantageous in terms of bandwidth usage when compared to making replication.…”