MC-CDMA系統工作於存在高斯相關分支與選頻性通道環境中的效能分析

本文主要研究MC-CDMA(multi-carrier coded-division multiple-access)系統工作於不相關(uncorrelated)與相關(correlated)衰落通道的Nakagami-m統計分佈。其中相關分支假設呈現高斯相關(correlated Gaussian)模型，在MC-CDMA系統中，其接收方法採用二位元相移鍵(binary phase shift key, BPSK)、非同調頻移鍵(noncoherent frequency shift key, NCFSK)以及差分同調相移鍵(differential coherent phase shift key, DCPSK)等調變架構，並分析位元錯誤率(bit error rate, BER)效能。為了得到分支之間任意相關通道的完全式，本文採用Gamma變數的機率密度函數(probability density function, pdf)，以避免在最大比例合成(maximum ratio combining, MRC)輸出，求得SNR(signal-to-noise ratio)之機率密度函數的困難。由本文所分析之系統BER效能得知，MC-CDMA系統極易受衰落通道相關性影響的，就MC-CDMA系統的BER效能而言，考慮無相關分支與相關分支的現象時，兩者之間約有3dB以上之差異。

關鍵字

MC-CDMA系統；不相關通道；相關通道； Nakagami-m衰落統計； NCFSK ； BPSK ； DCPSK

並列摘要

The performance of an MC-CDMA system working with both uncorrelated and correlated branches in a slowly varying fading channel, characterized by an Nakagami-m channel model wherein a branch correlation with Gaussian distribution is adopted, is studied. Modulation schemes consisting of a BPSK (binary-phase shift key), an NCFSK (non-coherent frequency shift key) and a DCPSK (differential coherent phase shift key) are assumed to serve as the MC-CDMA system. In order to avoid difficulty in determining the pdf (probability density function) for the random variable of an SNR (signal-to-noise ratio) at the MRC (maximum ratio combining) output, a sum of Gamma variates is applied. Some closed-form formulas for the average BER(bit error rate)for an MC-CDMA system operating with both uncorrelated and correlated branch cases are calculated. It is noteworthy that the numerical results indicate that the difference between the BER performance of the MC-CDMA system in these two cases is about 3dB.

並列關鍵字

MC-CDMA system ； uncorrelated channels ； correlated channels ； Nakagami-m fading statistics ； NCFSK ； BPSK ； DCPSK

國際替代計量

MC-CDMA系統工作於存在高斯相關分支與選頻性通道環境中的效能分析

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