A Study on Improve Performance in the Next-generation Broadband Wireless Communication Systems

在许多无线通信系统中都采用了正交频分复用(OFDM)技术。众所周知，ofdm对载波频偏(CFO)很敏感。由于CFO破坏了子载波间的正交性，由此产生的载波间干扰(ICI)导致了性能的严重下降。另一方面，直接转换接收机(DCR)因其体积小、成本低而近年来受到了广泛的关注。然而，代价是额外的扰动，如直流偏置(DCO)、I/Q不平衡。显然，CFO和DCO的共存是OFDMDCR中的一个关键问题。为了改善存在模拟损伤时的误码率性能，提出了一种新的CFO、DCO和I/Q不平衡联合估计方法。

Orthogonal frequency division multiplexing(OFDM) has been adopted in many wireless communication systems. OFDM is known for its sensitivity to carrier frequency offset(CFO). Since the CFO destroys the orthogonality among subcarriers, the resulting inter-carrier interference(ICI) leads to severe performance degradation.On the other hand, direct-conversion receiver(DCR) has attracted a lot of attention in recent years, for its smaller size and lower cost. However, the price is the additional disturbances, such as DC offset(DCO), I/Q imbalance. Obviously, the coexistence of the CFO and DCO is a critical problem in an OFDM DCR. In order to improve bit error ratio performance in the presence of analog impairments, a novel joint estimated method of CFO, DCO and I/Q imbalance were proposed.