X-TCP: A Cross Layer Approach for TCP Uplink Flows in mmWave Networks

摘要

Millimeter wave frequencies will likely be part of the fifth generation ofmobile networks and of the 3GPP New Radio (NR) standard. MmWave communicationindeed provides a very large bandwidth, thus an increased cell throughput, buthow to exploit these resources at the higher layers is still an open researchquestion. A very relevant issue is the high variability of the channel, causedby the blockage from obstacles and the human body. This affects the design ofcongestion control mechanisms at the transport layer, and state-of-the-art TCPschemes such as TCP CUBIC present suboptimal performance. In this paper, wepresent a cross layer approach for uplink flows that adjusts the congestionwindow of TCP at the mobile equipment side using an estimation of the availabledata rate at the mmWave physical layer, based on the actual resource allocationand on the Signal to Interference plus Noise Ratio. We show that this approachreduces the latency, avoiding to fill the buffers in the cellular stack, andhas a quicker recovery time after RTO events than several other TCP congestioncontrol algorithms.