Interleaved-OFDMA中基于子空间的上行链路载波频偏估计方法

在OFDMA系统中,通过为每个用户分配不同的子载波可以实现并行数据传输.采用Interleaved子载波分配方法可以提高频率分集和系统容量,但是发射机和接收机之间的载波频率偏移会破坏子载波间的正交性,从而导致本用户的载波间干扰(ICI)以及用户间干扰(MUI).本文提出了一种基于子空间的两阶段频偏搜索方法,该方法只采用一个OFDMA符号块就可以实现Interleaved-OFDMA上行链路多个用户频偏的联合估计,并且不需要知道接入的用户个数及用户所占用的子信道,因此适用于随机分配子信道的情况.仿真结果验证了算法的精确度和有效性.

Subspace-Based Uplink Carrier-Frequency Offset Estimation for Interleaved-OFDMA

In orthogonal frequency-division multiple access(OFDMA),closely spaced multiple subcarriers are assigned to different users for parallel signal transmission.An interleaved subcarrier-assignment scheme is preferred because it provides maximum frequency diversity and increases the capacity in frequency-selective fading channels.Carrier-frequency offsets(CFOs) between the transmitter and the receiver destroy the orthogonality and introduce ICI and multiuser interferences.A subspace-based two stages searching algorithm is proposed in this paper for estimating the CFOs of all users simultaneously in the uplink of Interleaved OFDMA systems using only one OFDMA block.Compared with existing CFO-estimation algorithms,it does not need the a priori info,such as the number of users and their occupied subchannels,so it is suitable for the case that subchannels randomly assigned.Simulation results illustrate the high accuracy and efficiency of the proposed algorithm.