Multipath Packet Scheduling for 5G Systems

Abstract: Modern mobile phones often have multiple network interfaces. By utilising these interfaces concurrently, the user experience can be enhanced, e.g., increased performance, stability and reliability. The introduction of 5G has increased the theoretical bandwidth and lowered the latency compared to previous generations of cellular techniques. However, this leads to a larger parameter space, which in a multipath system, increases the likelihood of asymmetric paths. Path asymmetry affects the overall performance of a reliable multipath connection, due to, e.g.,variation in delay which can cause packets to arrive out-of-order. This thesis first explores how multipath systems perform in comparison to single-path systems. Secondly, when the simultaneous use of paths is not beneficial for 5G-like multipath systems, and finally, if its possible to translate the findings into an effective scheduling strategy to improve the performance. With the use of Mininet, a network emulator, path parameters relating to 3G, 4G, 5G and WiFi are used to generate results representing a large spectrum of path combinations. The results gives insight to how MPTCP performs, from symmetric to highly asymmetric paths. The results show that the usage of multiple paths is not beneficial when the round-trip times are of different orders-of-magnitude. Based on observations, a proof-of-concept scheduler is proposed that reduce the negative effect of path asymmetry while still performing low amount of calculations.