中文摘要：

针对衰落信道下频谱资源利用率较低的问题,提出了一种自适应Turbo码调制方法。该方法在一定平均辐射功率和通信误码率的约束下,以优化平均频谱效率为目标,将衰落信道划分为N个相邻的衰落区域,并利用拉格朗日函数法求得了最优的衰落区域边界值。仿真结果表明：与同等复杂度的自适应网格编码调制方案相比,本文方法的平均频谱效率获得了将近2~3dB的性能增益,与香农极限仅相差3dB;与非最优4衰落区域相比,最优4衰落区域有将近1dB的性能增益。本文方法可显著提高无线通信系统的平均频谱效率。

英文摘要：

Considering the low spectrum resource utilization restricting high-speed data transmission over fading channels,this paper proposes an adaptive Turbo-coded modulation to maximize the spectral efficiency of system.Fading channel is divided into N adjacent regions,and Lagrange Multiplier is used to obtain the optimal switching thresholds under an average power constraint and bit-error constraint.Numerical results show that the spectral efficiency of adaptive Turbo-coded modulation has a 2~3dB gain in performance with the same complexity of TCM scheme,and within 3dB of the fading Shannon limit;comparing with the not optimized 4fading regions and the optimal 4fading regions,nearly 1dB performance gain can be obtained.The average spectral efficiency of wireless communication system can improve significantly.