In this paper, trellis shaping is applied to reducing the Peak-to-Average Power Ratio(PAPR) of NC-OFDM signals due to the fact that the total number of active subcarriers and their locations might change continuously ...In this paper, trellis shaping is applied to reducing the Peak-to-Average Power Ratio(PAPR) of NC-OFDM signals due to the fact that the total number of active subcarriers and their locations might change continuously in a dynamic spectrum access network.A new branch metric of trellis shaping is proposed which reduces the PAPR of OFDM signals through minimizing the variance of the power by VA decoder.The overall performance considerably depends on the type of signal mapping, and therefore a new type of 64QAM mapping method is designed.Simulation results show that this scheme significantly reduces the PAPR.Finally, a significant phenomenon is demonstrated that the PAPR of NC-OFDM signals in which the deactivated carriers is distributed in the Bernoulli distribution has better performance than that of OFDM signals.展开更多
Constant envelope orthogonal frequency division multiplexing(CE-OFDM) is a waveform that can achieve 0d B peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifi er. However, ...Constant envelope orthogonal frequency division multiplexing(CE-OFDM) is a waveform that can achieve 0d B peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifi er. However, the carrier frequency offset(CFO) in CE-OFDM systems can cause errors at phase unwrapper module. In this paper, a CFO estimation scheme is proposed for CEOFDM in satellite communication system. As the null subcarrier is inherent in the conjugate symmetric symbol structure at the transmitter, the proposed scheme uses the null subcarrier as prior information to estimate the CFO at the receiver. The ideal estimation range of normalized CFO is obtained by mathematical analysis. Simulation results show that the proposed scheme can estimate the CFO accurately under additive white Gaussian noise(AWGN) channel and multipath fading channel, especially for moderate and high signal-to-noise ratio(SNR).展开更多
In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlatio...In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.展开更多
The high peak-to-average power ration (PAPR) values of optical orthogond frequency division multiplexing (OFDM) signal limit the system nonlinear tolerance (NLT). In this paper, a novel method based on Hadamard precod...The high peak-to-average power ration (PAPR) values of optical orthogond frequency division multiplexing (OFDM) signal limit the system nonlinear tolerance (NLT). In this paper, a novel method based on Hadamard precoding is proposed to reduce the peak-to-average power ratio in optical direct detection OFDM system. The proposed scheme is successfully applied to an experimental system of optical direct-detection OFDM signal transmission through fiber. In this experiment, the 2.5 Gbit/s binary phase shift keying (BPSK) optical OFDM signals with Hadamard precoding are generated and transmitted though a single mode fiber. The experimental results show that the proposed scheme can reduce PAPR by almost 1.5 dB. Meantime the received sensitivity is improved by 2 dB with 100 km fiber transmission compared with that of an ordinary optical direct detection OFDM system.展开更多
Because the partial transmit sequence(PTS) peak-to-average power ratio(PAPR) reduction technology for optical orthogonal frequency division multiplexing(O-OFDM) systems has higher computational complexity, a novel two...Because the partial transmit sequence(PTS) peak-to-average power ratio(PAPR) reduction technology for optical orthogonal frequency division multiplexing(O-OFDM) systems has higher computational complexity, a novel two-stage enhanced-iterative-algorithm PTS(TS-EIA-PTS) PAPR reduction algorithm with lower computational complexity is proposed in this paper. The simulation results show that the proposed TS-EIA-PTS PAPR reduction algorithm can reduce the computational complexity by 18.47% in the condition of the original signal sequence partitioned into 4 sub-blocks at the remaining stage of n-d=5. Furthermore, it has almost the same PAPR reduction performance and the same bit error rate(BER) performance as the EIA-PTS algorithm, and with the increase of the subcarrier number, the computational complexity can be further reduced. As a result, the proposed TS-EIA-PTS PAPR reduction algorithm is more suitable for the practical O-OFDM systems.展开更多
Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear comp...Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding process.In this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.展开更多
Transmitter identification(TxID) technique is used to diagnose the operation status of radio transmitters in DTV distributed transmission network.A new TxID method for digital video broadcasting-handheld (DVB-H) syste...Transmitter identification(TxID) technique is used to diagnose the operation status of radio transmitters in DTV distributed transmission network.A new TxID method for digital video broadcasting-handheld (DVB-H) system is proposed.Watermark is embedded in the DVB-H signal to form the composite signal.According to watermarking theory we demonstrate the required signal level for watermarking signal to achieve given bit error probability under different circumstance.By selecting the reference pattern to generate watermarking signal,peak-to-average power ratio(PAPR) of the transmitted signal can be improved.Simulation results show that even in wireless situation the receiver can distinguish the watermarking signal with low embedding strength, and distortion to the host signal can also be ignored.展开更多
基金Supported by the National Natural Science Foundation of China (No.60832008)National Basic Research Program of China (973 Program, No.2009CB320403)
文摘In this paper, trellis shaping is applied to reducing the Peak-to-Average Power Ratio(PAPR) of NC-OFDM signals due to the fact that the total number of active subcarriers and their locations might change continuously in a dynamic spectrum access network.A new branch metric of trellis shaping is proposed which reduces the PAPR of OFDM signals through minimizing the variance of the power by VA decoder.The overall performance considerably depends on the type of signal mapping, and therefore a new type of 64QAM mapping method is designed.Simulation results show that this scheme significantly reduces the PAPR.Finally, a significant phenomenon is demonstrated that the PAPR of NC-OFDM signals in which the deactivated carriers is distributed in the Bernoulli distribution has better performance than that of OFDM signals.
基金supported by the National Natural Science Foundation of China(No.61601045,No.91438114 and No.61372111)
文摘Constant envelope orthogonal frequency division multiplexing(CE-OFDM) is a waveform that can achieve 0d B peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifi er. However, the carrier frequency offset(CFO) in CE-OFDM systems can cause errors at phase unwrapper module. In this paper, a CFO estimation scheme is proposed for CEOFDM in satellite communication system. As the null subcarrier is inherent in the conjugate symmetric symbol structure at the transmitter, the proposed scheme uses the null subcarrier as prior information to estimate the CFO at the receiver. The ideal estimation range of normalized CFO is obtained by mathematical analysis. Simulation results show that the proposed scheme can estimate the CFO accurately under additive white Gaussian noise(AWGN) channel and multipath fading channel, especially for moderate and high signal-to-noise ratio(SNR).
基金supported by the Scientific Research Foundation for the Doctor′s Degree,Beijing University of Technology(No.X0002012200903)the State Key Laboratory of Integrated Services Networks(Xidian University),China(No.ISN10-02)
文摘In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.
基金supported by the National High-tech Research and Development Program of China (No.2007AA01Z263)the Natural Science Foundation of Hunan Proviuce of China (No.06JJ50108)the Open Fund of Key Laboratory of Optical Communication and Lightwave Technologies of Education Ministry of China at Beijing University of Posts and Telecommunications
文摘The high peak-to-average power ration (PAPR) values of optical orthogond frequency division multiplexing (OFDM) signal limit the system nonlinear tolerance (NLT). In this paper, a novel method based on Hadamard precoding is proposed to reduce the peak-to-average power ratio in optical direct detection OFDM system. The proposed scheme is successfully applied to an experimental system of optical direct-detection OFDM signal transmission through fiber. In this experiment, the 2.5 Gbit/s binary phase shift keying (BPSK) optical OFDM signals with Hadamard precoding are generated and transmitted though a single mode fiber. The experimental results show that the proposed scheme can reduce PAPR by almost 1.5 dB. Meantime the received sensitivity is improved by 2 dB with 100 km fiber transmission compared with that of an ordinary optical direct detection OFDM system.
基金supported by the National Natural Science Foundation of China(Nos.61472464 and 61471075)the Program for Innovation Team Building at Institutions of Higher Education in Chongqing(No.J2013-46)+1 种基金the Natural Science Foundation of Chongqing Science and Technology Commission(Nos.cstc2015jcyj A0554 and cstc2013jcyj A40017)the Program for Postgraduate Science Research and Innovation of Chongqing University of Posts and Telecommunications(Chongqing Municipal Education Commission)(No.CYS14144)
文摘Because the partial transmit sequence(PTS) peak-to-average power ratio(PAPR) reduction technology for optical orthogonal frequency division multiplexing(O-OFDM) systems has higher computational complexity, a novel two-stage enhanced-iterative-algorithm PTS(TS-EIA-PTS) PAPR reduction algorithm with lower computational complexity is proposed in this paper. The simulation results show that the proposed TS-EIA-PTS PAPR reduction algorithm can reduce the computational complexity by 18.47% in the condition of the original signal sequence partitioned into 4 sub-blocks at the remaining stage of n-d=5. Furthermore, it has almost the same PAPR reduction performance and the same bit error rate(BER) performance as the EIA-PTS algorithm, and with the increase of the subcarrier number, the computational complexity can be further reduced. As a result, the proposed TS-EIA-PTS PAPR reduction algorithm is more suitable for the practical O-OFDM systems.
基金supported by the Research Grant of BB(Brain Busan)21 Project of 2015
文摘Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding process.In this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.
文摘Transmitter identification(TxID) technique is used to diagnose the operation status of radio transmitters in DTV distributed transmission network.A new TxID method for digital video broadcasting-handheld (DVB-H) system is proposed.Watermark is embedded in the DVB-H signal to form the composite signal.According to watermarking theory we demonstrate the required signal level for watermarking signal to achieve given bit error probability under different circumstance.By selecting the reference pattern to generate watermarking signal,peak-to-average power ratio(PAPR) of the transmitted signal can be improved.Simulation results show that even in wireless situation the receiver can distinguish the watermarking signal with low embedding strength, and distortion to the host signal can also be ignored.
