Research On Adaptive Modulation And Coded Technology In TD-HSDPA

The basic principle of adaptive modulation and coded technology is to change the mode of modulation and coded scheme accurately according to the instantaneous channel condition and current resource situation, in order to be adapted to channel condition and to achieve the best balance between the data transfer rate and the bit error rate within the system restriction, and thus to achieve the maximum data throughput.Firstly, the basic principles of the HSDPA system and the physical layer structure is discussed in this paper, then compared the similarities and differences between W-HSDPA and TD-HSDPA .Secondly, a brief introduction of the fade of wireless channel is presented, analysis of the Doppler frequency shift of the signal transmission by the simulation, and introduced the SNR prediction and channel estimation; simulation and analysis the bit error rate performance of different modulation schemes.This paper focused on the application of Adaptive Modulation and Coded technology in HSDPA.Based on the MCS selection algorithms has been proposed before, studied the relationships between SNR and the MCS switching threshold, proposed improved algorithm-the MCS selection algorithm based on channel estimation, so provided the method that selected the suitable MCS switching threshold according to the results of channel estimation.Compared the throughput performance of improved algorithm and ARF algorithm,the result showed the former is better than the later. An optimization scheme about MCS switching threshold selection is proposed, adding an additional threshold below the minimum threshold. The analysis showed that the new scheme would be more efficient. Simulated the principle of the adaptive modulation and coded technology; verified the improvement of the link performance by using adaptive modulation and coded technology according to the HSDPA downlink simulation.