Iterative frequency‐domain fractionally spaced receiver for zero‐padded multi‐carrier code division multiple access systems
Yanxin Yan, Yi Gong, Maode Ma, Qinghua Shi · IET Communications · 2014
In this study, the authors propose an improved frequency‐domain fractionally spaced (FDFS) minimum mean square error (MMSE) receiver for zero‐padded multi‐carrier code division multiple access (MC‐CDMA) systems when the guard interval is not enough to avoid the inter‐symbol interference (ISI) caused by the multipath channel. The proposed novel iterative FDFS‐based receivers firstly reconstruct the received symbol to reduce the ISI and then followed by the FDFS‐based equalisers to minimise the effect of ISI and inter‐carrier interference (ICI) caused by carrier frequency offset (CFO) and Doppler shifts. A few iterations are performed to achieve the expected bit error rate (BER) performance. To reduce the receiver complexity, the novel simplified diagonal FDFS‐based receivers with a fixed noise variance are developed with slight performance degradation. The proposed iterative receivers have never been studied in the existing literature. Simulation results show that the proposed iterative FDFS‐based receivers can significantly improve the BER performance of the conventional FDFS‐MMSE receiver in severe multiple interferences environments caused by multipath, CFO and Doppler shift.