基于子空间的交织OFDMA上行载波频偏估计

Subspace-based uplink carrier-frequency offset estimation for interleaved-OFDMA

为了实现采用交织子载波分配方法的正交频分多址(orthogonal frequency division multiplexing access,OFDMA)上行链路多个用户频偏的联合估计,提出一种基于子空间的两阶段频偏搜索方法。由于多重信号分类法(multiple signal characteristic,MUSIC)的采用,使得该方法具有较高的精确度,并且该方法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。仿真结果表明:当信噪比大于5 dB时,其标准均方根误差小于子载波间隔的1%,满足宽带无线接入系统关于载波频率偏差应小于子载波间隔2%的频率同步要求。

A subspace-based two stage search algorithm was developed to estimate the carrier frequency offsets （CFOs） in uplinks of interleaved orthogonal frequency division multiplexing access （OFDMA） systems. The main advantage of the method is that it simultaneously obtains the CFOs of all users using only one OFDMA block and has high accuracy due to use of multiple signal characteristic （MUSIC） algorithm. Unlike existing CFO-estimation algorithms, this algorithm does not need a priori information, such as the number of users and their occupied subchannels, so it is suitable for randomly assigned subchannels. Simulation results show that for signal-to-nolse ratio （SNR） larger than 5 dB, the normalized root mean square error （NRMSE） is less than 1% of the subcarrier spacing, which satisfies the frequency synchronization requirement of broadband wireless access systems requiring a precision of 2% of the subcarrier spacing.