选择映射(selected mapping,SLM)技术是一种无失真降低OFDM(orthogonal frequency divisionmultiplexing)信号峰均比PAPR(peak-to-average power ratio)的有效方法.但是普通的SLM技术因为相位序列边带信息的传输而导致了数据传输速率的...选择映射(selected mapping,SLM)技术是一种无失真降低OFDM(orthogonal frequency divisionmultiplexing)信号峰均比PAPR(peak-to-average power ratio)的有效方法.但是普通的SLM技术因为相位序列边带信息的传输而导致了数据传输速率的损失.因此提出了一种改进的SLM技术来降低OFDM信号的PAPR,它把相位序列信息嵌入在编码后的OFDM数据块的检测符号上,避免了系统特意传输边带信息而造成的数据传输速率的损失.Matlab仿真结果表明,所提出的改进SLM技术可以在不过分增加系统复杂性的基础上,获得比普通的SLM技术更好地降低PAPR的性能.展开更多
High peak-to-average power ratio(PAPR) is a concern in orthogonal frequency division multiplexing(OFDM) systems. Hadamard based selected mapping(HSLM) which uses Hadamard code as the phase sequence in selected mapping...High peak-to-average power ratio(PAPR) is a concern in orthogonal frequency division multiplexing(OFDM) systems. Hadamard based selected mapping(HSLM) which uses Hadamard code as the phase sequence in selected mapping(SLM) is an attractive technique to reduce PAPR. But it requires sending side information(SI) to the receiver for each data block, and this results in a reduction in bandwidth efficiency. In this paper, we proposed a modified PAPR reduction method called semi-Hadamard based selected mapping(semi-HSLM) to decouple the phase information matrix into a phase rotation matrix for PAPR reduction and a SI matrix for side information hiding. We proposed a semi-hadamard matrix generation method to generate the phase rotation matrix, and designed a cyclic shift matrix as the SI matrix. Compared with the traditional HSLM, the semi-HSLM saves half of the phase storage and achieves good PAPR reduction performance.展开更多
At present, mud pulse transmission systems are widely used in downhole data transmission. But the systems are very low in transmission efficiency, only 5-10 bits/s, with very large anti-inter-symbol-interference (ISI)...At present, mud pulse transmission systems are widely used in downhole data transmission. But the systems are very low in transmission efficiency, only 5-10 bits/s, with very large anti-inter-symbol-interference (ISI). It cannot meet high requirements for high-speed transmission of modern logging system. The development of communication technology has laid some foundation for this requirement. For this purpose, the Orthogonal Frequency Division Multiplexing (OFDM) Wireless Downhole Transmission Systems are proposed for the first time because of their high transmission rate, anti-inter-symbol-interference (ISI), and high spectral efficiency, etc. Due to non-linear power amplifier (PA) of logging systems with limited dynamic range, the drawbacks of high peak-average power ratio (PAPR) may outweigh all the potential benefits of OFDM wireless downhole transmission systems. Selective mapping (SLM) method can reduce the PAPR of OFDM logging signals without distortion. But at the receiver, the conventional SLM method needs exact bits of side information (SI) to recover the data signal. The probability of erroneous SI detection has a significant influence on the error performance of the system. And individual transmissions of SI result in the reduction of bandwidth efficiency. To restore the exact data signal, our scheme codes the SI bits by linear block codes (LBC), and is easily decoded by syndrome decoding. And then the coding SI bits are superimposed onto the logging signals to omit SI bits transmission. The theory and simulation results show that the proposed method has better performance than the conventional one. Accordingly, the OFDM wireless downhole transmission systems can tackle the high PAPR problem, and highten the transmission rate of logging signals.展开更多
Orthogonal frequency division multiplexing(OFDM) is an attractive technology to provide immense improvement in wireless transmission capacity but high peak-to-average power ratio(PAPR) is a major drawback of OFDM syst...Orthogonal frequency division multiplexing(OFDM) is an attractive technology to provide immense improvement in wireless transmission capacity but high peak-to-average power ratio(PAPR) is a major drawback of OFDM system.Selected mapping(SLM) scheme has good performance for PAPR reduction.It requires the transmitting data to be multiplied by random phase sequences.However,the sequences are pseudo-random which will decrease the method effectiveness.Exhaustive entropy is introduced in this paper which can identify the strength of random phase sequences property.Then an exhaustive entropy based on SLM method is proposed.The scheme improves the effectiveness of random phase sequences by selecting the larger exhaustive entropy of them.The simulation results show that the PAPR reduction performance is better than that of conventional SLM through this method.展开更多
One of main disadvantage of OFDM is high peak-to-average power ratio (PAPR). In this paper, two effective PAPR reduction schemes are proposed. These techniques combine DCT and SLM techniques. The scheme 1 is composed ...One of main disadvantage of OFDM is high peak-to-average power ratio (PAPR). In this paper, two effective PAPR reduction schemes are proposed. These techniques combine DCT and SLM techniques. The scheme 1 is composed of the DCT followed by SLM technique, and the DCT is used followed by conventional SLM in proposed scheme 2. Simulation results show that the proposed schemes can obtain significant PAPR reduction performance with that of ordinary SLM techniques.展开更多
提出一种信号畸变SLM(selective mapping)算法来降低OFDM系统PAPR(peak-to-average power ratio).传统SLM算法大大降低OFDM系统中高PAPR出现的概率,但并不能完全限制高PAPR信号的出现.信号畸变SLM算法在保持其余信号不变基础上,对高PAP...提出一种信号畸变SLM(selective mapping)算法来降低OFDM系统PAPR(peak-to-average power ratio).传统SLM算法大大降低OFDM系统中高PAPR出现的概率,但并不能完全限制高PAPR信号的出现.信号畸变SLM算法在保持其余信号不变基础上,对高PAPR信号进行畸变,将系统PAPR控制在期望的范围之内.经过SLM算法处理后大大降低了高PAPR信号出现的概率,所以对高PAPR信号进行畸变在很好地控制了OFDM系统PAPR的同时,并不会影响系统其余性能.仿真结果验证了新方法的有效性.展开更多
Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called informat...Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.展开更多
文摘选择映射(selected mapping,SLM)技术是一种无失真降低OFDM(orthogonal frequency divisionmultiplexing)信号峰均比PAPR(peak-to-average power ratio)的有效方法.但是普通的SLM技术因为相位序列边带信息的传输而导致了数据传输速率的损失.因此提出了一种改进的SLM技术来降低OFDM信号的PAPR,它把相位序列信息嵌入在编码后的OFDM数据块的检测符号上,避免了系统特意传输边带信息而造成的数据传输速率的损失.Matlab仿真结果表明,所提出的改进SLM技术可以在不过分增加系统复杂性的基础上,获得比普通的SLM技术更好地降低PAPR的性能.
基金the Wireless Network Positioning and Communication Integration Research Center in BUPT for financial support
文摘High peak-to-average power ratio(PAPR) is a concern in orthogonal frequency division multiplexing(OFDM) systems. Hadamard based selected mapping(HSLM) which uses Hadamard code as the phase sequence in selected mapping(SLM) is an attractive technique to reduce PAPR. But it requires sending side information(SI) to the receiver for each data block, and this results in a reduction in bandwidth efficiency. In this paper, we proposed a modified PAPR reduction method called semi-Hadamard based selected mapping(semi-HSLM) to decouple the phase information matrix into a phase rotation matrix for PAPR reduction and a SI matrix for side information hiding. We proposed a semi-hadamard matrix generation method to generate the phase rotation matrix, and designed a cyclic shift matrix as the SI matrix. Compared with the traditional HSLM, the semi-HSLM saves half of the phase storage and achieves good PAPR reduction performance.
文摘At present, mud pulse transmission systems are widely used in downhole data transmission. But the systems are very low in transmission efficiency, only 5-10 bits/s, with very large anti-inter-symbol-interference (ISI). It cannot meet high requirements for high-speed transmission of modern logging system. The development of communication technology has laid some foundation for this requirement. For this purpose, the Orthogonal Frequency Division Multiplexing (OFDM) Wireless Downhole Transmission Systems are proposed for the first time because of their high transmission rate, anti-inter-symbol-interference (ISI), and high spectral efficiency, etc. Due to non-linear power amplifier (PA) of logging systems with limited dynamic range, the drawbacks of high peak-average power ratio (PAPR) may outweigh all the potential benefits of OFDM wireless downhole transmission systems. Selective mapping (SLM) method can reduce the PAPR of OFDM logging signals without distortion. But at the receiver, the conventional SLM method needs exact bits of side information (SI) to recover the data signal. The probability of erroneous SI detection has a significant influence on the error performance of the system. And individual transmissions of SI result in the reduction of bandwidth efficiency. To restore the exact data signal, our scheme codes the SI bits by linear block codes (LBC), and is easily decoded by syndrome decoding. And then the coding SI bits are superimposed onto the logging signals to omit SI bits transmission. The theory and simulation results show that the proposed method has better performance than the conventional one. Accordingly, the OFDM wireless downhole transmission systems can tackle the high PAPR problem, and highten the transmission rate of logging signals.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 61101126)the Postdoctoral Science Foundation of China (Grant No.2011M500664)
文摘Orthogonal frequency division multiplexing(OFDM) is an attractive technology to provide immense improvement in wireless transmission capacity but high peak-to-average power ratio(PAPR) is a major drawback of OFDM system.Selected mapping(SLM) scheme has good performance for PAPR reduction.It requires the transmitting data to be multiplied by random phase sequences.However,the sequences are pseudo-random which will decrease the method effectiveness.Exhaustive entropy is introduced in this paper which can identify the strength of random phase sequences property.Then an exhaustive entropy based on SLM method is proposed.The scheme improves the effectiveness of random phase sequences by selecting the larger exhaustive entropy of them.The simulation results show that the PAPR reduction performance is better than that of conventional SLM through this method.
文摘One of main disadvantage of OFDM is high peak-to-average power ratio (PAPR). In this paper, two effective PAPR reduction schemes are proposed. These techniques combine DCT and SLM techniques. The scheme 1 is composed of the DCT followed by SLM technique, and the DCT is used followed by conventional SLM in proposed scheme 2. Simulation results show that the proposed schemes can obtain significant PAPR reduction performance with that of ordinary SLM techniques.
文摘提出一种信号畸变SLM(selective mapping)算法来降低OFDM系统PAPR(peak-to-average power ratio).传统SLM算法大大降低OFDM系统中高PAPR出现的概率,但并不能完全限制高PAPR信号的出现.信号畸变SLM算法在保持其余信号不变基础上,对高PAPR信号进行畸变,将系统PAPR控制在期望的范围之内.经过SLM算法处理后大大降低了高PAPR信号出现的概率,所以对高PAPR信号进行畸变在很好地控制了OFDM系统PAPR的同时,并不会影响系统其余性能.仿真结果验证了新方法的有效性.
文摘Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.
