實體層動態調變編碼和混合式自動重傳機制的最佳化演算法

Abstract

For data transmission services, adaptive transmission can enhance the throughput performance by adjusting modulation and coding schemes (MCS) according to the instantaneous channel conditions. In time-varying channels, the performance degradation of adaptive transmission caused by delay or inaccurate channel condition feedback can be mitigated with the use of hybrid automatic repeat request(HARQ). With these two techniques jointly implemented, the selection of MCS becomes a complex process highly dependent on channel and system characteristics, and is usually difficult to be optimized. In this thesis, we propose an adaptive throughput maximization algorithm that can dynamically adjust the thresholds depending on feedback SNR and increase the overall throughput performance. When transmission time interval (TTI) varies, throughput performance can be further enhanced by allowing users with better channel conditions to transmit longer periods. The proposed algorithm with variable TTI is also discussed in this thesis. The algorithm is simulated in IEEE 802.16 platform.