Handover Friendly TCP Proxy Integrated in the LTE eNodeB

Serving online applications and commercial web sites with low latency is business critical. As content requests originate from geographically distant locations and increasingly from mobile devices, globally ensuring service quality is challenging. The content is delivered to the clients predominantly via the Transmission Control Protocol (TCP), therefore optimal TCP operation over radio access is highly relevant. The split connection TCP Proxy is an optimization mechanism by itself and also a basic component of solutions such as transparent caching aiming at improved interactivity and reduced access latency. In Long Term Evolution (LTE) systems, the Evolved Node B (eNB) is the best location for the TCP Proxy. However, the eNB side TCP Proxy may inherently cause the collapse of TCP connections after handover, a problem this paper is first to analyze. Due to how user plane connectivity is switched over during LTE handovers, the TCP Proxy uniquely creates the possibility for losing data that cannot be recovered through TCP retransmissions. As a solution, the paper presents a TCP Proxy integrated with the eNB Packet Data Convergence Protocol (PDCP) layer. Simulation results indicate that the PDCP integration complemented with X2 prioritization efficiently prevents unrecoverable losses and enables to safely leverage the benefits of an eNB side TCP Proxy.