Advanced HARQ and scheduler schemes in TDD-CDMA HSDPA systems

An enhancement HARQ method (E-HARQ) for TDD-CDMA supporting HSDPA techniques is firstly proposed. The basic idea is to discard the retransmission and change the modulation and coding when the link quality is lower than a pre-determined threshold. E-HARQ reduces the unnecessary retransmissions and makes MAC more efficient; hence the system performance improves. As compared to the change of MCS selections between HARQ retransmissions, the increase of system complexity due to E-HARQ is small. Furthermore, an advanced proportionally fair scheduling (APFS) algorithm is proposed, which aims at guaranteeing the long-term and short-term fairness as well as maximizing the system throughput These advanced adaptive techniques can improve the system throughput under the constraint of the user's quality of service (QoS).