Interactions between TCP and RLP protocols in a cellular system

We investigate the interactions between the transmission control protocol (TCP) and radio link protocols (RLP) of various reliability, when used in a spectrally efficient microcellular system similar to the EDGE cellular system. The study is done through detailed downlink simulations of a large cellular system with numerous simultaneous users. Either fixed-load or WWW-like packet traffic is generated for each link, and RENO TCP is run. The results show that the choice of RLP retransmission parameters impacts the throughput loss and application packet delay significantly, and that the range of 3-10 RLP block retransmissions (60-200ms persistency) offers the smallest performance degradation caused by TCP/RLP interactions. We conclude that variable RLP persistency based on the knowledge of radio conditions for individual users, is highly desirable