An interference suppression design scheme based on conjugate weighted butterfly interleaving mapping(CWBIM)is proposed for inter-carrier interference(ICI)and inter-subband interference(IBI)in the received signals of u...An interference suppression design scheme based on conjugate weighted butterfly interleaving mapping(CWBIM)is proposed for inter-carrier interference(ICI)and inter-subband interference(IBI)in the received signals of universal filtered multi-carrier(UFMC)systems.It applies an interleaving mapping operation to subtract the interference coefficients of adjacent terms in ICI and IBI twice,thereby achieving suppression effects similar to the self-cancellation(SC)algorithm while maintaining the original data transmission efficiency.Meanwhile,conjugate and complex weighting operations can effectively suppress the impact of phase rotation errors in high-speed mobile channel environments,thereby further improving the bit error rate(BFR)performance of the system,Moreover,butterfly operation can effectively control the computational complexity of the interleaving mapping process.Theoretical analysis and simulation results show that,compared with the PSC-UFMC algorithm,the CWBIM-UFMC scheme proposed in this paper can effectively suppress ICI and IBI in the received signal without compromising data transmission efficiency and reducing computational complexity,thereby achieving good BER performance of the system.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
在基于分段线性模型的正交频分复用(orthogonal frequency division multiplexing,OFDM)时变信道估计中,存在模型参数估计精度受到载波间干扰(inter-carrier interference,ICI)影响的问题。为此,本文采用ICI自消除技术,抑制了导频子载波...在基于分段线性模型的正交频分复用(orthogonal frequency division multiplexing,OFDM)时变信道估计中,存在模型参数估计精度受到载波间干扰(inter-carrier interference,ICI)影响的问题。为此,本文采用ICI自消除技术,抑制了导频子载波的ICI,改善了模型参数的估计性能。此外,还推导了单抽头Jakes信道条件下模型参数估计均方误差的表达式,理论分析表明,与基本的分段线性模型方法相比,本文方法可以使均方误差下降约13dB。仿真结果验证了在多抽头信道和大的多普勒扩展条件下,本文方法也能明显提高ICI抑制能力,从而得到更好的系统误码性能。展开更多
针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于...针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于对称子载波的ICI自消除算法与时域加窗相结合,即在发送数据符号之前,与升余弦函数相乘。对算法进行仿真实验,相对于相邻符号自消除算法,该算法减小了子载波间的干扰系数;加窗后OFDM符号频谱的边瓣衰减速度快,最大可衰减至-40 d B;对于系统的信号干扰比性能(SIR),加窗后的算法同相邻符号自消除算法相比可提高8 d B左右;在信噪比较大的情况下,改善了系统的误码率。仿真结果表明,所提算法能够抑制ICI,提高系统抗干扰性能。展开更多
Inter-cell interference (ICI) mitigation is always a challenge issue in LTE system. In this paper, several common interference parameters are firstly analyzed for both cell edge users and center users, and then a nove...Inter-cell interference (ICI) mitigation is always a challenge issue in LTE system. In this paper, several common interference parameters are firstly analyzed for both cell edge users and center users, and then a novel fractional frequency reuse (FFR) architecture based on interference avoidance scheme coupled with power control is proposed to solve the problem of interference management in multi-cell LTE environment. The scheme divides the whole sub-carriers into three groups orthogonally. One is allocated to cell edge users, while another two are assigned to cell center users with different transmitter power. Then a parameter named interference avoidance factor (IAF) is defined to avoid ICI and adjust the number of allocated sub-carriers to match the number of users. The parameter also takes weight factor and fairness factor into consideration. The simulation results show the proposed scheme can improve the performance of cell edge users obviously.展开更多
针对基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的新型多载波系统,提出统一的预编码应用模型,该模型可以通过配置不同的预编码方案和多载波调制得到多种实例系统,同时可基于互模糊函数对信号和载波间干扰(inte...针对基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的新型多载波系统,提出统一的预编码应用模型,该模型可以通过配置不同的预编码方案和多载波调制得到多种实例系统,同时可基于互模糊函数对信号和载波间干扰(inter-carrier interference,ICI)进行量化分析,并利用原始信号的统计特性得到应用预编码后系统的载干比(carrier-to-interference power ratio,CIR)。在该模型的基础上,提出一种基于双向抵消载波间干扰思想的预编码方案,此方案将目标载波2个方向的多个子载波加权进行ICI抵消,可以更好解决系统中普遍存在的载波间干扰问题,获得更强的抗频偏能力。仿真结果表明,在实例系统OFDM和滤波正交频分复用(filtered orthogonal frequency division multiplexing,F-OFDM)中,所提方案均较传统的预编码抑制ICI方案约有0.7 dB的CIR性能改善,较未编码的系统约有3.5~6 dB的改善。展开更多
Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from performance deterioration when the length of Cyclic Prefix (CP) is shorter than the Channel Impulse Response (CIR). The fundamental reason of this ...Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from performance deterioration when the length of Cyclic Prefix (CP) is shorter than the Channel Impulse Response (CIR). The fundamental reason of this impairment is the InterCarrier Interference (ICI) and Inter- Symbol Interference (ISI) introduced by the excessive multipath delay. Specifically, Multiple Input Multiple Output (MIMO) beamforming is helpful in cancelling such interference since it can spatially suppress some of the multipath. In this paper, we propose an ICI eliminating beamforming scheme employing a per-tone processing approach, thus with moderate computational complexity. The ISI is removed by using a simple decision feedback equalizer, while the optimal steering and combining vectors are then derived to maximize the Signal to Interference plus Noise Ratio (SINR). This method not only achieves the beamforming benefit, but also significantly alleviates the ICI. Simulation results show that the proposed algorithm can effectively reduce the system Symbol Error Rate (SER), per- mitting good performance for multipath delay profiles that would break conventional links.展开更多
基金Supported by the National Natural Science Foundation of China(No.61601296,61701295)the Science and Technology Innovation ActionPlan Project of Shanghai Science and Technology Commission(No.20511103500)the Talent Program of Shanghai University of Engineer-ing Science(No.2018RC43)。
文摘An interference suppression design scheme based on conjugate weighted butterfly interleaving mapping(CWBIM)is proposed for inter-carrier interference(ICI)and inter-subband interference(IBI)in the received signals of universal filtered multi-carrier(UFMC)systems.It applies an interleaving mapping operation to subtract the interference coefficients of adjacent terms in ICI and IBI twice,thereby achieving suppression effects similar to the self-cancellation(SC)algorithm while maintaining the original data transmission efficiency.Meanwhile,conjugate and complex weighting operations can effectively suppress the impact of phase rotation errors in high-speed mobile channel environments,thereby further improving the bit error rate(BFR)performance of the system,Moreover,butterfly operation can effectively control the computational complexity of the interleaving mapping process.Theoretical analysis and simulation results show that,compared with the PSC-UFMC algorithm,the CWBIM-UFMC scheme proposed in this paper can effectively suppress ICI and IBI in the received signal without compromising data transmission efficiency and reducing computational complexity,thereby achieving good BER performance of the system.
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.
文摘在基于分段线性模型的正交频分复用(orthogonal frequency division multiplexing,OFDM)时变信道估计中,存在模型参数估计精度受到载波间干扰(inter-carrier interference,ICI)影响的问题。为此,本文采用ICI自消除技术,抑制了导频子载波的ICI,改善了模型参数的估计性能。此外,还推导了单抽头Jakes信道条件下模型参数估计均方误差的表达式,理论分析表明,与基本的分段线性模型方法相比,本文方法可以使均方误差下降约13dB。仿真结果验证了在多抽头信道和大的多普勒扩展条件下,本文方法也能明显提高ICI抑制能力,从而得到更好的系统误码性能。
文摘针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于对称子载波的ICI自消除算法与时域加窗相结合,即在发送数据符号之前,与升余弦函数相乘。对算法进行仿真实验,相对于相邻符号自消除算法,该算法减小了子载波间的干扰系数;加窗后OFDM符号频谱的边瓣衰减速度快,最大可衰减至-40 d B;对于系统的信号干扰比性能(SIR),加窗后的算法同相邻符号自消除算法相比可提高8 d B左右;在信噪比较大的情况下,改善了系统的误码率。仿真结果表明,所提算法能够抑制ICI,提高系统抗干扰性能。
基金Sponsored by the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT0949)the Fundamental Research Funds for the Central Universities(Grant No.2010JBZ008),the Fundamental Research Funds for the Central Universities(Grant No.KWJB10006536)+1 种基金the Joint Funds of State Key Program of NSFC(Grant No.60830001)the State Key Laboratory of Rail Traffic Control and Safety(Grant No.RCS2008ZZ007)
文摘Inter-cell interference (ICI) mitigation is always a challenge issue in LTE system. In this paper, several common interference parameters are firstly analyzed for both cell edge users and center users, and then a novel fractional frequency reuse (FFR) architecture based on interference avoidance scheme coupled with power control is proposed to solve the problem of interference management in multi-cell LTE environment. The scheme divides the whole sub-carriers into three groups orthogonally. One is allocated to cell edge users, while another two are assigned to cell center users with different transmitter power. Then a parameter named interference avoidance factor (IAF) is defined to avoid ICI and adjust the number of allocated sub-carriers to match the number of users. The parameter also takes weight factor and fairness factor into consideration. The simulation results show the proposed scheme can improve the performance of cell edge users obviously.
文摘针对基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的新型多载波系统,提出统一的预编码应用模型,该模型可以通过配置不同的预编码方案和多载波调制得到多种实例系统,同时可基于互模糊函数对信号和载波间干扰(inter-carrier interference,ICI)进行量化分析,并利用原始信号的统计特性得到应用预编码后系统的载干比(carrier-to-interference power ratio,CIR)。在该模型的基础上,提出一种基于双向抵消载波间干扰思想的预编码方案,此方案将目标载波2个方向的多个子载波加权进行ICI抵消,可以更好解决系统中普遍存在的载波间干扰问题,获得更强的抗频偏能力。仿真结果表明,在实例系统OFDM和滤波正交频分复用(filtered orthogonal frequency division multiplexing,F-OFDM)中,所提方案均较传统的预编码抑制ICI方案约有0.7 dB的CIR性能改善,较未编码的系统约有3.5~6 dB的改善。
基金Supported by the National Science Fund for Distinguished Young Scholars (No. 60725105)the National Basic Re-search Program of China (2009CB320404)+5 种基金the Program for Changjiang Scholars and Innovative Research Team in Universitythe National High Technology Research and Development Program of China (2007AA01Z288)the 111 Project (B08038)the National Natural Science Founda-tion of China (No. 60902032, 60902033, and 60702057)the Key Project of Chinese Ministry of Education (107103) the Program for State Key Laboratory of Integrated Service Networks (ISN02080001)
文摘Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from performance deterioration when the length of Cyclic Prefix (CP) is shorter than the Channel Impulse Response (CIR). The fundamental reason of this impairment is the InterCarrier Interference (ICI) and Inter- Symbol Interference (ISI) introduced by the excessive multipath delay. Specifically, Multiple Input Multiple Output (MIMO) beamforming is helpful in cancelling such interference since it can spatially suppress some of the multipath. In this paper, we propose an ICI eliminating beamforming scheme employing a per-tone processing approach, thus with moderate computational complexity. The ISI is removed by using a simple decision feedback equalizer, while the optimal steering and combining vectors are then derived to maximize the Signal to Interference plus Noise Ratio (SINR). This method not only achieves the beamforming benefit, but also significantly alleviates the ICI. Simulation results show that the proposed algorithm can effectively reduce the system Symbol Error Rate (SER), per- mitting good performance for multipath delay profiles that would break conventional links.
