A Robust Header Compression Simulator & Visualizer

Abstract

IP-based realtime multimedia communication provides for a large Layer-3 and Layer-4 header overhead due to usually small payload sizes of single packets in a realtime flow. Because of the restricted bandwidth of wireless links, header compression represents an essential prerequisite for the Mobile Internet, i.e., whenever an IP-based mobile end device has to communicate with an IP-based infrastructure. RFC 3095 on Robust Header Compression (ROHC) represents the state-of- the-art header compression proposal. It provides a complex framework that allows to fine-tune compression efficiency versus robustness against link errors. We present a Java-based simulator/visualizer currently running ROHC Profile 2 (UDP/IP) in Uni-directional Mode that allows experimentation with all relevant ROHC parameters (like state transition timers and repeat counters) as well as with various link conditions. We present the implementation and report on simulation results. An average header length of about 2.8 bytes is achieved. In general, the tool is useful as an educational tool for assessing ROHC performance and to see Robust Header Compression ‘at work’, i.e., to explore the underlying parameter space. For the future, the simulator will be also used to generate realistic audio/video packet flows for evaluation with respect to audio/video decompression handling in the presence of packet losses.