全雙工系統是未來5G發展重要的一項技術，比起半雙工系統，他可以讓設備間同時去傳送與接收，提升頻譜效率，並減少延遲，而全雙工最大的問題是受限於自干擾，所以必須去消除自干擾，而數位的自干擾消除方法有最低的複雜度，但是能消除的自干擾也相對有限。 本篇的上行鏈及下行鏈分別使用單載波頻分多重存取(SC -FDMA)，及正交分頻多工存取(OFDMA)，為LTE的標準模型，而上行鏈單載波頻分多工存取(SC-FDMA)相較於OFDM有較低的PAPR，但容易受到頻率偏移的影響，因此本篇探討了如何在不需要估測自干擾通道下消除來自下行鏈的自干擾，以及在有頻率偏移的情況下如何估測出頻率偏的值然後做補償。 ;Full duplex systems are expected to double the spectral efficiency compared to conventional half-duplex systems if the self-interference can be significantly mitigated. And digital cancellation is one of the lowest complexity self-interference cancellation techniques in full duplex systems. However its mitigation is very limited. We use SC-FDMA in uplink and OFDMA in downlink in this paper, it is also the standard in LTE. And SC-FDMA in uplink generate lower PAPR than OFDM, but in the other hand, the frequency offset effects SC-FDMA easier. Hence, we discuss how to remove the self-interference from downlink if we need not to estimate the self-interference channel and how to estimate the frequency offset and compensate when frequency offset exists in this paper.
