Investigating a reduced size real-time transport protocol for low-bandwidth networks

Abstract

Optimization of bandwidth usage for video streaming is of paramount importance in networks where low bitrate links are typical. Among the solutions proposed to address this problem is header compression. Real-Time Transport Protocol (RTP) and RTP Control Protocol (RTCP) are the major protocols responsible for the delivery of real-time media. Previously, header compression at the hardware layer and multiplexing of media frames into single RTP packets was considered sufficient for reducing the bit overhead of the RTP packets. However, at the very low bit rates encountered in congested and low throughput networks, multiplexing and hardware compression do not suffice for end-to-end delivery and therefore the use of a lightweight version of RTP, defined in this work as RTP-Lite, requires investigation. A cyclical approach to compression of the RTP headers was used with different compression cycle patterns for Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) transport. Measurements over the public Internet showed that end-to-end compression of the RTP header at the application layer was achieved with the expected reduction in required throughput and minimal degradation of packet loss and jitter performance.