Hybrid Transmission Time Intervals for TCP Slow Start in Mobile Edge Computing System

In this paper, a novel scheduling scheme with hybrid transmission time intervals (TTI) is proposed to improve the performance of Transmission Control Protocol (TCP) transmission in Mobile Edge Computing (MEC) systems. Two use cases with diverse service requirements, i.e., low latency communication (LLC) and enhanced mobile broadband (eMBB), are considered and originally assigned to separate bands with short TTI of 0.143 ms and long TTI of 1 ms, respectively. With the proposed scheduling scheme, eMBB traffic at TCP slow start stage can be scheduled with short TTI and utilize the remaining resource after scheduling LLC users, thus speeding up the slow start procedure at the initial transmission phase due to faster feedback of acknowledgement. After a given time threshold, while the throughput probably approaching saturation, eMBB traffic switches to its own band with long TTI to lower transmission overhead. System level simulations demonstrate that the proposed solution can achieve high performance improvement for eMBB users while not affecting LLC users in terms of user throughput and transmission latency, particularly when the eMBB traffic load is heavy compared to its available bandwidth. The switching time threshold should be flexibly adapted to control the amount of eMBB traffic allocated with frequency resources initially reserved for LLC users, such that the eMBB traffic can benefit from utilizing the vacant resource, thereby achieving the potential gain.