日前,《广西植物》正式被波兰《哥白尼索引》(IC)旗下的两个知名数据库哥白尼索引期刊数据库(ICI World of Journals)和哥白尼索引精选数据库(ICI Journals Master List)全文收录,这是该期刊继被瑞典知名数据库(DOAJ)成功收录后的又一...日前,《广西植物》正式被波兰《哥白尼索引》(IC)旗下的两个知名数据库哥白尼索引期刊数据库(ICI World of Journals)和哥白尼索引精选数据库(ICI Journals Master List)全文收录,这是该期刊继被瑞典知名数据库(DOAJ)成功收录后的又一大喜讯。展开更多
As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in...As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in multi-path fading channel. However, when there are frequency offsets during the signal transmission, the inter-carrier interference （ICI） is introduced, which significantly degrades the performance. The existing ICI self-cancellation schemes such as PCC-OFDM are not optimum to minimize the interference considering both noise and ICI. In this paper, a new metric named S1NR （signal-to-interference- and-noise ratio） is proposed. We discuss the optimization issue when a constant frequency offset exists and in time-varying channels. The optimum weighting-coefficient-pair （OWCP） is obtained, which maximizes SINR theoretically through the alternant iteration algorithm. Simulations show that the performance of OWCP-OFDM is better than that of PCC-OFDM, especially when the frequency offset is large. Although the ICI self-cancellation scheme suffers bandwidth inefficiency, from the simulation results we can also see that the performance of OWCP-OFDM is much better than that of the standard OFDM systems with the same bandwidth efficiency when a frequency offset exists. Moreover, since the redundant modulation provides the capability to suppress ICI as well as a receiving SNR gain, it can be considered as exchanging the bandwidth for SNR.展开更多
A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that...A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that the ICI generated by a subcarrier to the two adjacent subcarriers is approximately equal, a data pair with opposite sign and equal magnitude is modulated onto two adjacent subcarriers as pilot pair to eliminate the effect of ICI on pilots. Secondly, a new OFDM channel estimation model based on linear time-varying（LTV） model and compressed sensing（CS） is constructed, which obtains the mean of the gains of the multipath.Finally, a pilot pair optimization algorithm based on two layers loop is used to realize the minimization of the mutual coherence of the measurement matrix. For time-varying channel scenes with different numbers or delay of multipath and maximum Doppler frequency shift, the performances of several channel estimation methods are verified by simulation. The result shows that the new method has obvious advantage in both the performance of the channel estimation and the spectral efficiency.展开更多
日前,《橡胶工业》陆续收到通知,被美国EBSCO学术数据库和《乌利希国际期刊指南》(Ulrichsweb Global Serials Directory)以及哥白尼索引期刊数据库(ICI World of Journals)和哥白尼精选数据库(ICI Master List)等国际重要数据库收录为...日前,《橡胶工业》陆续收到通知,被美国EBSCO学术数据库和《乌利希国际期刊指南》(Ulrichsweb Global Serials Directory)以及哥白尼索引期刊数据库(ICI World of Journals)和哥白尼精选数据库(ICI Master List)等国际重要数据库收录为来源期刊。2022年12月,《橡胶工业》收到EBSCO学术数据库通知,从2022年第9期开始被EBSCO学术数据库收录。2022年11月,《橡胶工业》被《乌利希国际期刊指南》收录。2022年10月,《橡胶工业》被哥白尼索引期刊数据库和哥白尼精选数据库(后者为前者的子集)收录。展开更多
基金Project (No. 2006AA01Z273) supported by the Hi-Tech ResearchDevelopment Program (863) of China
文摘As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in multi-path fading channel. However, when there are frequency offsets during the signal transmission, the inter-carrier interference （ICI） is introduced, which significantly degrades the performance. The existing ICI self-cancellation schemes such as PCC-OFDM are not optimum to minimize the interference considering both noise and ICI. In this paper, a new metric named S1NR （signal-to-interference- and-noise ratio） is proposed. We discuss the optimization issue when a constant frequency offset exists and in time-varying channels. The optimum weighting-coefficient-pair （OWCP） is obtained, which maximizes SINR theoretically through the alternant iteration algorithm. Simulations show that the performance of OWCP-OFDM is better than that of PCC-OFDM, especially when the frequency offset is large. Although the ICI self-cancellation scheme suffers bandwidth inefficiency, from the simulation results we can also see that the performance of OWCP-OFDM is much better than that of the standard OFDM systems with the same bandwidth efficiency when a frequency offset exists. Moreover, since the redundant modulation provides the capability to suppress ICI as well as a receiving SNR gain, it can be considered as exchanging the bandwidth for SNR.
基金supported by the National Natural Science Foundation of China(61571368)
文摘A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that the ICI generated by a subcarrier to the two adjacent subcarriers is approximately equal, a data pair with opposite sign and equal magnitude is modulated onto two adjacent subcarriers as pilot pair to eliminate the effect of ICI on pilots. Secondly, a new OFDM channel estimation model based on linear time-varying（LTV） model and compressed sensing（CS） is constructed, which obtains the mean of the gains of the multipath.Finally, a pilot pair optimization algorithm based on two layers loop is used to realize the minimization of the mutual coherence of the measurement matrix. For time-varying channel scenes with different numbers or delay of multipath and maximum Doppler frequency shift, the performances of several channel estimation methods are verified by simulation. The result shows that the new method has obvious advantage in both the performance of the channel estimation and the spectral efficiency.
文摘日前,《橡胶工业》陆续收到通知,被美国EBSCO学术数据库和《乌利希国际期刊指南》(Ulrichsweb Global Serials Directory)以及哥白尼索引期刊数据库(ICI World of Journals)和哥白尼精选数据库(ICI Master List)等国际重要数据库收录为来源期刊。2022年12月,《橡胶工业》收到EBSCO学术数据库通知,从2022年第9期开始被EBSCO学术数据库收录。2022年11月,《橡胶工业》被《乌利希国际期刊指南》收录。2022年10月,《橡胶工业》被哥白尼索引期刊数据库和哥白尼精选数据库(后者为前者的子集)收录。
