Type-II Hybrid ARQ Scheme in a DS-CDMA Packet Transmission Network
J. Pérez-Romero, Ramon Agusti, José Oriol Sallent Roig · RECERCAT (Consorci de Serveis Universitaris de Catalunya) · 1999
In this study a type-II hybrid ARQ strategy is analyzed in a DS-CDMA packet transmission network.A comparison is performed with other strategies such as simple ARQ and type-I hybrid ARQ, resulting in a better performance for ARQ-II in terms of capacity, although the delay becomes worse compared to ARQ-I.The main advantage of ARQ-II over ARQ-I is that it deals with channel errors by sending the required redundancy only when it is strictly necessary and as a result it can send information bits in those bits where ARQ-I working with the same packet length sends redundancy bits.Only when channel errors become present redundancy is sent, thus reducing the useful information rate but maintaining the channel bit rate.This idea suggests that ARQ-II can be regarded as a strategy that performs an information rate adaptation at the DLC (Data Link Control) layer, and consequently it can be compared with other multirate strategies that perform this adaptation at the MAC (Medium Access Control) level by varying the channel bit rate.