L4S in 5G networks

Sammanfattning: Low Latency Low Loss Scalable Throughput (L4S) is a technology which aims to provide high throughput and low latency for the IP traffic, lowering also the probability of packet loss. To reach this goal, it relies on Explicit Con- gestion Notification (ECN), a mechanism to signal congestion in the network avoiding packets drop. The congestion signals are then managed at sender and receiver side thanks to scalable congestion control algorithms. Initially, in this work the challenges to implement L4S in a 5G network have been analyzed. Using a proprietary state-of-the-art network simulator, L4S have been imple- mented at the Packed Data Convergence Protocol layer in a 5G network. The 5G network scenario represents a context where the physical layer has a carrier frequency of 600 MHz, a transmission bandwidth of 9 MHz, and the proto- col stack follows the New Radio (NR) specifications. L4S has been adopted to support Augmented Reality (AR) video gaming traffic, using the IETF ex- perimental standard Self-Clocked Rate Adaptation for Multimedia (SCReAM) for congestion control. The results showed that when supported by L4S, the video gaming traffic experiences lower delay than without L4S support. The improvement on latency comes with an intrinsic trade-off between throughput and latency. In all the cases analyzed, L4S yields to average application layer throughput above the minimum requirements of high-rate latency-critical ap- plication, even at high system load. Furthermore, the packet loss rate has been significantly reduced thanks to the introduction of L4S, and if used in combi- nation with a Delay Based Scheduler (DBS), a packet loss rate very close to zero has been reached.