Wireless systems and standards are now progressing toward the implementation of fifth generation (5G) to combat with an expected and explosive growth of demands of wireless services in future. Consequently, wireless i...Wireless systems and standards are now progressing toward the implementation of fifth generation (5G) to combat with an expected and explosive growth of demands of wireless services in future. Consequently, wireless interoperability for microwave access (WiMAX) with orthogonal frequency division multiplexing (OFDM) technology at its physical layer is being utilized for the uplink and downlink transmission to afford the high spectral efficiency in fading environments. However, the 5G implementation requires additional improvements to meet the futuristic stress. This work proposes an innovative solution that combines WiMAX system with multiple input multiple output (MIMO) technology to meet the required elevated data rates as desired by the growing application needs of 5G. MIMO is capable to fulfil the vision of 5G to realize a huge number of base stations equipped with a large number of terminals to be served in the same time-frequency resource without severe inter-user interference. Furthermore, the proposed system is demon- strated incorporation with discrete wavelet transform (DWT), and fractional Fourier transforms (FrFTs) in the physical layer of the WiMAX system. The evaluated outcomes exemplify a considerable improvement in bit error rate (BER) performance in contrast with the earlier reported work.展开更多
为了消除水声正交频分复用调制(Orthogonal Frequency Division Multiplexing,OFDM)系统中噪声对稀疏多径信道估计的影响,提出了一种改进的最小二乘(Least-Square,LS)信道估计算法。该方法在传统基于离散傅里叶变换(Discrete Fourier Tr...为了消除水声正交频分复用调制(Orthogonal Frequency Division Multiplexing,OFDM)系统中噪声对稀疏多径信道估计的影响,提出了一种改进的最小二乘(Least-Square,LS)信道估计算法。该方法在传统基于离散傅里叶变换(Discrete Fourier Transform,DFT)插值的信道估计结构上进行了改进,得到了基于阈值探测的DFT插值信道估计方法,该方法将小于阈值的时域信道响应置零,探测最有效信道抽头,有效消除噪声干扰的影响。仿真结果验证了DFT插值在稀疏多径水声信道估计中的实用性;得到了当循环前缀长度与信道长度越接近时信道估计性能(Bit Error Rate,BER)越好的结论;确定了在两种调制方式下算法的阈值系数范围;且该新算法与已有算法所需的信噪比可低约2 d B,解决了用循环前缀长度来近似信道真实长度的实际问题。展开更多
针对传统的基于离散余弦变换(DCT)信道估计算法没有处理循环前缀之内噪声的问题,提出了一种基于小波去噪与DCT插值相结合的正交频分复用(OFDM)系统信道估计方法。首先,采用最小二乘(LS)法对接收到的导频信号进行信道初步估计;然后,对LS...针对传统的基于离散余弦变换(DCT)信道估计算法没有处理循环前缀之内噪声的问题,提出了一种基于小波去噪与DCT插值相结合的正交频分复用(OFDM)系统信道估计方法。首先,采用最小二乘(LS)法对接收到的导频信号进行信道初步估计;然后,对LS法估计出的结果进行离散小波阈值去噪处理;最后,利用DCT插值对循环前缀内的噪声再次处理,以进一步减小噪声的影响。在Matlab 2012平台上仿真,与传统的基于DCT信道估计算法相比较,误码率相同的条件下,所提算法的信噪比(SNR)性能提升了1 d B左右;均方误差相同的条件下,所提算法的SNR性能提升2 d B左右。仿真实验结果表明,该算法能够较好地减小加性高斯白噪声(AWGN)的影响,并有效提高信道估计的准确度,其总体性能较基于DCT的信道估计算法更优。展开更多
提出一种基于子载波消噪和小波阈值去噪的多天线频谱池信道估计方法。多天线接收信号携带的噪声同时分布在禁用子载波和可用子载波上,为了降低噪声对信道估计带来的影响,需要分步消除这两部分噪声。禁用子载波携带的噪声可在频域消除,...提出一种基于子载波消噪和小波阈值去噪的多天线频谱池信道估计方法。多天线接收信号携带的噪声同时分布在禁用子载波和可用子载波上,为了降低噪声对信道估计带来的影响,需要分步消除这两部分噪声。禁用子载波携带的噪声可在频域消除,可用子载波上的信号可通过小波变换做降噪处理。在低信噪比和没有信道统计特性的条件下,将信号转换到频域对禁用子载波做消噪处理,采用最小二乘(Least square,LS)方法在时域进行信道估计,并对各支路信道估计进行小波阈值去噪处理,进一步降低可用子载波噪声对信道估计性能的影响。最后通过最大比合并(Maximal Ratio Combining,MRC)的方法得到合并信号的最小二乘信道估计。仿真分析表明,采用子载波消噪和小波阈值去噪的信道估计方法可有效提高多天线频谱池系统性能。展开更多
文摘Wireless systems and standards are now progressing toward the implementation of fifth generation (5G) to combat with an expected and explosive growth of demands of wireless services in future. Consequently, wireless interoperability for microwave access (WiMAX) with orthogonal frequency division multiplexing (OFDM) technology at its physical layer is being utilized for the uplink and downlink transmission to afford the high spectral efficiency in fading environments. However, the 5G implementation requires additional improvements to meet the futuristic stress. This work proposes an innovative solution that combines WiMAX system with multiple input multiple output (MIMO) technology to meet the required elevated data rates as desired by the growing application needs of 5G. MIMO is capable to fulfil the vision of 5G to realize a huge number of base stations equipped with a large number of terminals to be served in the same time-frequency resource without severe inter-user interference. Furthermore, the proposed system is demon- strated incorporation with discrete wavelet transform (DWT), and fractional Fourier transforms (FrFTs) in the physical layer of the WiMAX system. The evaluated outcomes exemplify a considerable improvement in bit error rate (BER) performance in contrast with the earlier reported work.
文摘为了消除水声正交频分复用调制(Orthogonal Frequency Division Multiplexing,OFDM)系统中噪声对稀疏多径信道估计的影响,提出了一种改进的最小二乘(Least-Square,LS)信道估计算法。该方法在传统基于离散傅里叶变换(Discrete Fourier Transform,DFT)插值的信道估计结构上进行了改进,得到了基于阈值探测的DFT插值信道估计方法,该方法将小于阈值的时域信道响应置零,探测最有效信道抽头,有效消除噪声干扰的影响。仿真结果验证了DFT插值在稀疏多径水声信道估计中的实用性;得到了当循环前缀长度与信道长度越接近时信道估计性能(Bit Error Rate,BER)越好的结论;确定了在两种调制方式下算法的阈值系数范围;且该新算法与已有算法所需的信噪比可低约2 d B,解决了用循环前缀长度来近似信道真实长度的实际问题。
文摘针对传统的基于离散余弦变换(DCT)信道估计算法没有处理循环前缀之内噪声的问题,提出了一种基于小波去噪与DCT插值相结合的正交频分复用(OFDM)系统信道估计方法。首先,采用最小二乘(LS)法对接收到的导频信号进行信道初步估计;然后,对LS法估计出的结果进行离散小波阈值去噪处理;最后,利用DCT插值对循环前缀内的噪声再次处理,以进一步减小噪声的影响。在Matlab 2012平台上仿真,与传统的基于DCT信道估计算法相比较,误码率相同的条件下,所提算法的信噪比(SNR)性能提升了1 d B左右;均方误差相同的条件下,所提算法的SNR性能提升2 d B左右。仿真实验结果表明,该算法能够较好地减小加性高斯白噪声(AWGN)的影响,并有效提高信道估计的准确度,其总体性能较基于DCT的信道估计算法更优。
文摘提出一种基于子载波消噪和小波阈值去噪的多天线频谱池信道估计方法。多天线接收信号携带的噪声同时分布在禁用子载波和可用子载波上,为了降低噪声对信道估计带来的影响,需要分步消除这两部分噪声。禁用子载波携带的噪声可在频域消除,可用子载波上的信号可通过小波变换做降噪处理。在低信噪比和没有信道统计特性的条件下,将信号转换到频域对禁用子载波做消噪处理,采用最小二乘(Least square,LS)方法在时域进行信道估计,并对各支路信道估计进行小波阈值去噪处理,进一步降低可用子载波噪声对信道估计性能的影响。最后通过最大比合并(Maximal Ratio Combining,MRC)的方法得到合并信号的最小二乘信道估计。仿真分析表明,采用子载波消噪和小波阈值去噪的信道估计方法可有效提高多天线频谱池系统性能。
