摘要
高效率编码技术(如LDPC,Turbo码)的发展迫切要求降低解调门限。提出一种适用于QPSK调制方式的低信噪比解调方案,该方案采用频域非线性定时估计算法进行定时误差估计,利用FFT进行载波频差估计,利用周期性插入的导频序列进行载波相位估计。首先仿真了定时误差和载波相位误差对解调性能的影响,并在此基础上确定了算法的具体参数,最后对解调器的综合性能进行了仿真,仿真结果表明上述算法在Es/N0=2dB时的解调性能恶化小于0.5 dB。
An implementation solution for QPSK demodulator at low SNR is proposed to make the best of the capability of the highly efficient channel encoder technique,such as LDPC coder and Turbo coder.Firstly,timing error is obtained by using the frequency domain nonlinear timing estimate algorithm,and then FFT is used to estimate carrier frequency error,at last periodical pilot sequences is inserted to estimate carrier phase.Performance debasement caused by timing error or carrier phase error is first simulated to determine the algorithm parameter,and based on this,system performance simulation result is obtained.The simulation results showed that performance loss could be less than 0.5dB when Es/N0=2 dB.
出处
《无线电通信技术》
2011年第2期55-58,共4页
Radio Communications Technology
关键词
低信噪比解调
定时恢复
载波恢复
导频
demodulation at low SNR
timing recovery
carrier recovery
pilot
