正交分頻多工系統(OFDM)具有高峰值對平均功率比(PAPR)，單載波調變(SCM)系統可以解決高峰值對平均功率比問題，我們還可以實現前置編碼 OFDM（POFDM）架構下的單載波調變。針對符號間干擾(ISI)，使用快速傅立葉轉換(FFT)計算及足夠的保護區間(GI)的頻率等化可以代替複雜的傳統時域等化。
OFDM是沒有多路徑多樣性(multipath diversity)的，在多路徑瑞利衰減(multipath Rayleigh fading)通道中多樣性只有1階。在POFDM架構下的SCM線性前置編碼具有多路徑多樣性。藉由模擬我們比較了在POFDM架構下OFDM和SCM系統的位元錯誤率(BER)。我們驗證了SCM具有多路徑多樣性。我們進一步在 OFDM和SCM系統結合分碼多工（CDMA）。對於OFDM系統的子通道CDMA可以提供多樣性。

Orthogonal frequency-division multiplexing (OFDM) have high peak-to-average power ratio (PAPR), while the single-carrier modulation (SCM) system does not have high PAPR problem. We can also implement the SCM under the precoded OFDM (POFDM) architecture. As for the intersymbol interference (ISI), frequency-domain equalization with fast Fourier transform computation and sufficient guard interval (GI) can substitute for complex conventional time-domain equalization.
The OFDM system does not have multipath diversity, and the diversity order is only one in the multipath Rayleigh fading channel. With the linear precoding, the SCM under the POFDM architecture has the multipath diversity. By simulation we compare the BER performance of the OFDM and SCM under the POFDM architecture. We verify the multipath diversity of the SCM. We further combine the code division multiple access (CDMA) into the OFDM and SCM systems. The CDMA can provide the diversity across sub-channels for the OFDM system.

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