Throughput of hybrid ARQ types for UTRA TDD

The throughput of hybrid ARQ types I and II-III based on simulations for unconstrained delay data (UDD) is investigated. We focus on the differences between types I and II. A subset of the protocol on layers 1-3 for UMTS terrestrial radio access (UTRA) time division duplex (TDD) mode is simulated for a single cell, both user traffic and signalling messages suffer from fading and interference in the model, interference due to traffic in neighbouring cells is also taken into account. Results are obtained for downlink traffic for various code-rates and interleaving schemes. The results include capacity, distribution of the number of retransmissions, and PDU delay. It is shown that type II-III greatly outperforms type I for the cases “UDD 2048 pico” and “UDD 384 micro” in terms of capacity and the number of retransmissions. The benefit of using type II-III decreases at lower bitrates but it remains significant. This is shown by a simulation for the case “UDD 8 micro”, thus hybrid ARQ type II-III outperforms type I for all UDD services between 8 kbit/s and 2 Mbit/s for UTRA TDD mode