mmCPTP: A Cross-Layer Pull based Transport Protocol for 5G mmWave Networks

This paper presents mmCPTP, a cross-layer end-toend protocol for fast delivery of data over mmWave channels associated with emerging 5G services. Recent measurement studies of mmWave channels in urban micro cellular deployments show considerable fluctuation in received signal strength along with intermittent outages resulting from user mobility. This results in significant impairment of end-to-end data transfer throughput when regular TCP is used to transport data over such mmWave channels. To address this issue, we propose mmCPTP, a novel cross-layer end-to-end data transfer protocol that sets up a transport plug-in at or near the base station and uses feedback from the lower layer (RLC/MAC) to opportunistically pull data at the mobile client without the slow start and probing delays associated with TCP. The system model and end-to-end protocol architecture are described and compared with TCP and IndirectTCP (I-TCP) in terms of achievable data rate. The proposed mmCPTP protocol is evaluated using NS3 simulation for 5G NR (New Radio) considering a high-speed mobile user scenario. The system is further validated using a proof-of-concept prototype which emulates the high-speed mmWave/NR access link with traffic shaping over Gbps ethernet. Results show significant performance gains for mmCPTP over TCP and I-TCP (2.5x to 17.2x, depending on the version).