Performance enhancement of incremental redundancy in wireless data networks by measurement-based transmission control

Incremental redundancy (IR) is a technique that can dynamically adapt the effective code rate to channel conditions. It accomplishes this by incrementally transmitting additional redundancy until the information can be decoded successfully. IR is especially suitable for wireless data services, which can tolerate variable transmission delay. We propose an enhancement to current IR approaches, which uses a special transmission mode, "mode 0". The basic idea of mode 0 is to temporarily delay a user's transmission if its link quality is lower than a pre-determined threshold. Mode 0 reduces unnecessary retransmissions and therefore, uses the resource more efficiently. Using simulations, we show that introducing a mode 0 improves the system throughput and delay performance. To implement mode 0, link quality measurements are required, which increases system complexity. However, in light of the performance gain provided by mode 0, this might be a good tradeoff.