The Right Time: Reducing Effective End-to-End Delay in Time-Slotted Packet-Switched Networks

Abstract

Modern access network technologies like Long Term Evolution (LTE) and High Speed Packet Access (HSPA) use time-slotting mechanisms to optimize resource sharing and overall network performance. In time-slotted networks, the one-way delay of all packets in a packet stream depends on the absolute point in time when the first packet of the stream is sent. With appropriate feedback signals, applications can exploit this effect to reduce their effective end-to-end delay. Time-critical applications such as real-time sensor data acquisition or voice-over-IP (VoIP) communications can shift their acquisition interval in order to adapt to the network timing. Information about the actual time-slotting periods can be gathered by active network measurements or through implementation of cross-layer information exchange. In this paper, a method is proposed to determine the optimum send time for particular destinations and to support applications in adjusting their send time accordingly. Theoretical findings are supported by the offline analysis of measurement data and by a proof-of-concept implementation that confirms the feasibility and effectiveness of the proposed solution in operational LTE and HSPA networks.