基于压缩感知的高分辨OFDM信道估计

Title    OFDM channel estimation based on compressive sensing
Abstract
Orthogonal Frequency Division Multiplexing (OFDM) is the basis for the next generation of wireless communications technology. Channel estimation is one of the key challenges in OFDM, since high-resolution channel estimation can significantly improve the equalization at the receiver and consequently enhance the communication performances. In this paper, we design the measurement matrix and use the sparsity of channel to achieve channel estimation with compressed sensing. CS is developed based on the compressibility of the sensing signals, and senses the high dimension signals by using the incoherence measurments in the low-dimensional space, low-resolution, and sub-Nyquist rate. It has high probability to guarantee the reconstruction of the signals. CS can greatly reduce the sampling rate and solves many of the traditional signal processing problems. In the simulation experiment, this paper uses OMP to achieve OFDM channel estimation, and evaluates the estimation results under different sampling rates. It is shown that the success rate of the OFDM channel estimation decreases as the reduction of the sampling rate.

Keywords  OFDM; Compressed sensing; OMP; Channel estimation

1  绪论1
1.1  Nyquist采样与压缩感知的意义…1
1.2  压缩感知的理论背景2
1.3  本文主要内容及安排… 3
2  压缩感知基础理论… 5
2.1  信号的稀疏表示… 6
2.2  观测矩阵的设计…7
2.3  重构算法 8
3  OFDM信号压缩采样的数学模型及信道估计仿真… 10
3.1  OFDM信号压缩采样的数学模型… 10
3.2  用OMP算法实现信道估计仿真… 10
3.3  降低采样率对信道估计的影响… 13
3.4  仿真总结16

1  绪论
1.1  从Nyquist采样到压缩感知
OFDM已经广泛适用于无线通信系统中，因为它具有高速率传输，可以实现高带宽效率，并且有相对稳定的多径衰落和延时。OFDM可以应用在数字音频广播（DAB），高清晰度电视，数字视频广播（DVB），无线LAN网络，3GPP长期演进（LTE），以及IEEE802.16宽带无线接入系统等。当前OFDM基于WLAN标准（如IEEE802.11a/g），需要在OFDM接收机进行相干检测。此要求需要一个准确的多径信道状态的信道估计（CSI）。关于OFDM信道估计存在大量的相关文献，本文提供一个简要的概述。

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