Efficient multi user CFO estimation and correction techniques in uplink OFDMA systems

2014 First International Conference on Computational Systems and Communications (ICCSC) Pub Date : 2014-12-01 DOI:10.1109/COMPSC.2014.7032668

Neetha I. Eappen, J. Prakash, G. Ramachandra Reddy

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引用次数: 4

Abstract

Inter carrier interference and multiple access interference are induced in uplink OFDMA systems due to Carrier Frequency Offset (CFO) which is a mismatch between the transmitter and receiver frequencies that in turn affects the orthogonality among subcarriers. A different CFO value is experienced by each user data and each of these CFO values needs to be estimated and corrected. A novel Extended Viterbi-and-Viterbi (EVAV) algorithm is employed for CFO estimation in the present study. A conventional algorithm for CFO compensation that deals with Minimum Mean Square Error (MMSE) filter output, involves inversion of interference matrix, adding to the computational complexity. The complexity was found to increase with the number of subcarriers. Hence, here an iterative Conjugate Gradient (CG) method is used to compute the MMSE filter output without an inverse operation, thereby reducing the complexity. Both the EVAV method and the CG method have been analyzed in terms of various performance measures. The results showed that they function better than their conventional counterparts.

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上行OFDMA系统中高效的多用户CFO估计与校正技术

在上行OFDMA系统中，由于载波频率偏移(CFO)而引起载波间干扰和多址干扰，即发送频率和接收频率之间的不匹配，进而影响子载波之间的正交性。每个用户数据都体验到不同的CFO值，需要对每个CFO值进行估计和修正。本文提出了一种新的扩展Viterbi-and-Viterbi (EVAV)算法用于CFO估计。传统的CFO补偿算法处理最小均方误差(MMSE)滤波器输出，涉及干扰矩阵的反演，增加了计算复杂度。复杂度随着子载波数量的增加而增加。因此，本文采用迭代共轭梯度(CG)方法来计算MMSE滤波器输出，而无需进行逆操作，从而降低了复杂度。对EVAV方法和CG方法进行了各种性能指标的分析。结果表明，它们的功能比传统的同类产品更好。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2014 First International Conference on Computational Systems and Communications (ICCSC)

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