相干DS-SS/MPSK系統(tǒng)中頻差影響的簡化評估
Simplified Evaluation for the Effect of Frequency Offset in Coherent DS-SS/MPSK Systems
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摘要: 該文針對單徑慢衰落信道模型下的相干DS-SS/MPSK系統(tǒng)，分析了頻差對系統(tǒng)性能的影響，得到了誤比特率的封閉表達式。首先推導了匹配濾波解擴符號的信噪比特性和相干相位估計誤差的分布；然后給出了衰落信道中誤比特率的精確積分式，并利用MPSK條件誤符號率的麥克勞林級數(shù)形式，推導了AWGN，Nakagami-m衰落和瑞利衰落信道中BPSK，QPSK誤比特率的簡化逼近式。最后的數(shù)值結果表明：逼近式的精度非常高，基本沒有損失，可應用于實際系統(tǒng)設計和性能評估。Abstract: Focusing on coherent DS-SS/MPSK system in single path slow fading channel model, this paper analyzes the effect of frequency offset on system performance, and the closed-form Bit Error Rate (BER) expressions are also obtained. Firstly, the Signal Noise Ratio (SNR) characteristic of matched filter despread symbol and the distribution of coherent phase estimation error are derived. Secondly, the exact integration formula of BER for fading channel is presented, moreover, by using the Maclaurin series expansion of MPSK conditional Symbol Error Rate (SER), the simplified BER approximations for BPSK and QPSK are derived over AWGN, Nakagami-m fading and Rayleigh fading channel. Finally, numerial results show that the approximations provide excellent accuracy without loss and can be applied to practical system design and performance evaluation.
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