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In orthogonal frequency division multiplexing (OFDM) systems, the existing timing synchronization (TS) methods are challenged by high computational complexity, large processing delay, and performance degradation in wireless scenarios. To alleviate these issues, a lightweight cascaded one-dimensional convolutional neural network (1-D CNN)-based TS scheme is proposed in this paper, which is developed from the joint perspective of considering cascaded mode and network lightweight. Specifically, we meticulously design two lightweight subnetworks. The first one is implemented with only one 1-D CNN layer due to the coarse timing offset task, which aims to reduce the search range of TS for the following subnetwork. Based on the narrowed search range of TS, the second subnetwork is also light-weighted with a two-layer 1-D CNN, which refines the estimation of timing offset. By jointly considering the cascaded mode and the lightweight 1-D CNN, the proposed scheme improves the TS correctness with reduced computational complexity and processing delay compared with the existing works. Simulation results validate the effectiveness and robustness of the proposed TS scheme given variant parameters.

Generalized frequency division multiplexing (GFDM) is a block-based multicarrier modulation scheme that is a potential candidate for the fifth generation (5G) and beyond wireless communication systems. A critical factor in enhancing the performance of GFDM is achieving precise synchronization. To that end, a new timing synchronization algorithm that utilizes cross-correlation and the sliding window algorithm is presented in this article. The algorithm uses a training symbol based on a chirp sequence. The simulation results of the proposed estimator and conventional CP based approach are analyzed under indoor office scenarios and urban macro cells scenarios for orthogonal frequency division multiplexing and GFDM. The performance of the proposed method is better for GFDM in terms of the three parameters: mean of the timing offset, mean square error of the timing offset, and probability of timing failure. For the proposed algorithm, the results show that the probability of timing failure decreases with increasing signal to noise ratio in the case of the GFDM system. [ABSTRACT FROM AUTHOR]

Considering the problem that the timing synchronization calculation in high-speed remote sensing signal reception is complex and it is difficult for it to be parallel, this paper deduces and designs a parallel timing error estimation and correction scheme. This paper presents the design of polyphase DFT filter banks with non-maximum decimation. The feedforward timing error estimation and correction method is then improved to enhance synchronization performance. Finally, an implementation scheme for parallel timing error estimation and correction is proposed using the polyphase filter bank time domain decomposition method and the filter polyphase model. In the estimation module, the parallel implementation structure of the joint second-order and fourth-order cyclic statistics methods is designed, which improves the estimation accuracy. In the correction module, a fractional delay filtering method with higher accuracy is adopted in order to improve the calibration accuracy and reduce the computational complexity. The timing synchronization of a high-speed remote sensing signal with timing error is simulated and verified. The experimental results show that the parallel method proposed in this paper greatly reduces the processing speed of subband data, and has a good synchronization performance, which is close to the theoretical limit in the demodulation error rate. This paper utilizes a multi-phase DFT filter bank architecture to achieve parallel timing synchronization, which presents a novel approach for the future parallel reception of high-speed remote sensing signals. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since orthogonal frequency division multiplexing (OFDM) systems are very susceptible to symbol timing offset (STO) and carrier frequency offset (CFO), which cause inter-symbol interference (ISI) and inter-carrier interference (ICI), accurate STO and CFO estimations are very important. In this study, first, a new preamble structure based on the Zadoff–Chu (ZC) sequences was designed. On this basis, we proposed a new timing synchronization algorithm, called the continuous correlation peak detection (CCPD) algorithm, and its improved algorithm: the accumulated correlation peak detection (ACPD) algorithm. Next, the correlation peaks that were obtained during the timing synchronization were used for the frequency offset estimation. For this, the quadratic interpolation algorithm was adopted as the frequency offset estimation algorithm, which was better than the fast Fourier transform (FFT) algorithm. The simulation results showed that when the correct timing probability reached 100%, under the parameters of m = 8 and N = 512, the performance of the CCPD algorithm was 4 dB higher than that of Du's algorithm, and that of the ACPD algorithm was 7 dB. Under the same parameters, the quadratic interpolation algorithm also had a great performance improvement in both small and large frequency offsets, when compared with the FFT algorithm. [ABSTRACT FROM AUTHOR]

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Orthogonal frequency division multiplexing (OFDM)-based Power-Line Communications (PLC) systems are vulnerable to synchronization errors, and the particularities of the PLC channel affect the performance of the synchronization process. In this context, this work is focused on the initial pilot symbol detection, presenting a comparison between autocorrelation- (AC) and crosscorrelation (CC)-based timing metrics, which include the most common preamble-based synchronization strategies. Two robust timing metrics are defined and the effect of multipath, Colored Background Noise (CBN) and Impulsive Noise (IN) is theoretically evaluated on each. A detailed analysis of the probability distributions of the timing metrics is performed and primary detection thresholds and lower bounds for the symbol detection probability are derived. Simulations of the OFDM-PLC system are performed in order to validate the analysis, considering a statistic PLC channel model and different noise sources. Results show that the CBN and IN significantly degrade the timing metrics behavior, and that the CC-based timing metric is more robust to this worsening, thus achieving a better synchronization performance than the AC-based timing metric. [ABSTRACT FROM AUTHOR]

Recent advances in continuous-flow microfluidics have enabled highly integrated lab-on-a-chip biochips. These chips can execute complex biochemical applications precisely and efficiently within a tiny area, but they require a large number of control ports and the corresponding control logic to generate required pressure patterns for flow control, which, consequently, offset their advantages and prevent their wide adoption. In this article, we propose the first flow-control layer co-synthesis flow called MiniControl, for continuous-flow microfluidic biochips under strict constraints for control ports, incorporating high-level synthesis, physical design, and control system design simultaneously, which has never been considered in previous work. With the maximum number of allowed control ports specified in advance, this synthesis flow aims to generate biochip architectures with high execution efficiency and the corresponding control systems with optimized timing performance. Besides, the overall cost of a biochip can be reduced and the tradeoff between a control system and execution efficiency of biochemical applications can be evaluated for the first time. The experimental results demonstrate that MiniControl leads to high execution efficiency, low platform cost, as well as excellent timing performance, while strictly satisfying the given control-port constraints. [ABSTRACT FROM AUTHOR]

Narrowband internet of things (NB-IoT) technology is widely used in data communications for a large number of low-speed and low-power devices, but it is diff cult to provide services for remote areas that cannot be covered by terrestrial networks.With its global coverage and low cost, the LEO satellite constellation can supplement and expand the terrestrial NB-IoT infrastructure, providing an eff ective solution for the space-based internet of things.Facing the application requirements of space-based internet of things, on the basis of reviewing the NB-IoT system architecture, the challenges of channel environment high dynamic delay and frequency off set faced by the application of NB-IoT technology in the LEO satellite constellation scenario were analyzed.For the uplink random access process, an eff ective user detection and timing synchronization method was designed, which had the advantages of high performance and low complexity, and provided an eff cient receiving method for the LEO satellite NB-IoT uplink random access synchronization.

Due to short frames of short-term burst signals, the performance of conventional non-data-aided feedforward timing estimators is unsatisfactory. This letter investigates an estimator based on multiple cyclic correlations addressing this issue. The cyclic correlations at high-valued timing lags provide the timing information for estimating timing offset. Motivated by it, we combine the timing information at various timing lags, utilizing the second-order statistical characteristics of the limited sample data for accurate estimation. Considering the estimation range of roll-off factors and computational complexity, an asymptotically unbiased estimation using four correlations is deduced. Simulation results show that the proposed estimator outperforms other estimators. [ABSTRACT FROM AUTHOR]

High definition video transmission is one of the prime demands of modern day communication. Changing needs demand diverse features to be offered by the video codec standards, H.264 fits to these requirements for video compression. In this work, an attempt has been made to optimize the inter prediction along with improved intra prediction to ensure the minimal bit rates thereby reduction in the channel bandwidth, which is required in most of the wireless applications. In intraprediction, only DC prediction mode is chosen out of 9 modes with 4*4 luma blocks that reduces the coding complexity towards optimal logic utilization in order to support typical FPGA board for hardware implementation. Most significantly, Inter prediction is carried out utilizing the M9K blocks efficiently with proper timing synchronization to reduce the latency in the encoding operation. Experimental set up comprising of two Altera DE2-115 boards connected through Ethernet cable demonstrated the video transmission. These optimized intra prediction and inter prediction stages resulted in significant improvement in the video compression possessing good subjective quality and increased video compression.

Considering the problem that the timing synchronization calculation in high-speed remote sensing signal reception is complex and it is difficult for it to be parallel, this paper deduces and designs a parallel timing error estimation and correction scheme. This paper presents the design of polyphase DFT filter banks with non-maximum decimation. The feedforward timing error estimation and correction method is then improved to enhance synchronization performance. Finally, an implementation scheme for parallel timing error estimation and correction is proposed using the polyphase filter bank time domain decomposition method and the filter polyphase model. In the estimation module, the parallel implementation structure of the joint second-order and fourth-order cyclic statistics methods is designed, which improves the estimation accuracy. In the correction module, a fractional delay filtering method with higher accuracy is adopted in order to improve the calibration accuracy and reduce the computational complexity. The timing synchronization of a high-speed remote sensing signal with timing error is simulated and verified. The experimental results show that the parallel method proposed in this paper greatly reduces the processing speed of subband data, and has a good synchronization performance, which is close to the theoretical limit in the demodulation error rate. This paper utilizes a multi-phase DFT filter bank architecture to achieve parallel timing synchronization, which presents a novel approach for the future parallel reception of high-speed remote sensing signals.

The asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM)-based visible light communication (VLC) system has received widespread attention due to its capability to support high spectrum efficiency as well as high power efficiency. The accuracy of symbol timing offset estimation is a critical factor limiting the performance of ACO-OFDM. In order to cope with this challenge, a training symbol-aided symbol timing synchronization method tailored for ACO-OFDM is put forward. The influence of the design of training symbol structure and timing metric on the synchronization accuracy is investigated, and three timing metrics are presented to supply simple and efficient timing offset estimation by utilizing the structure of odd-even mirror-symmetric and complementary symmetric of the newly designed training symbol. In addition, the system bit error rate (BER) penalty induced by timing synchronization error is analyzed, and the approximate relationship between BER performance loss and timing estimation error probability and ideal BER performance is presented. Simulation is used to assess the performance of the three proposed timing metric methods in different channel environments, and they are compared with the two existing timing synchronization algorithms in ACO-OFDM, namely the modified Park method and the Tian method. The results show that the new synchronization method is superior to the comparison methods concerning achievable synchronization accuracy and system BER penalty. [ABSTRACT FROM AUTHOR]

Cell search is the first step to establish downlink synchronization between user equipment (UE) and base station (BS) in the fifth generation (5G) new radio (NR) system. However, frequency offset and noise will cause a massive loss of synchronization performance. To solve this problem, a novel timing synchronization algorithm of primary synchronization signal (PSS) with anti-frequency offset and anti-noise is proposed, which includes the improved coarse synchronization algorithm based on Fourier transform and the fine synchronization algorithm based on the triple auto-correlation algorithm. The improved coarse synchronization algorithm not only has a strong frequency offset resistance, especially for large frequency offset, but also obtains the estimated frequency offset. The fine synchronization algorithm is more resistant to noise than the conventional algorithm. Finally, the algorithm analysis and simulation results show that the improved algorithm can work very well even when the normalized frequency offset increases to greater than 0.8, but the conventional algorithm fails to synchronize properly. Meanwhile, when the SNR is as low as -6dB, the detection accuracy of the timing synchronization based on the proposed fine synchronization algorithm is improved by about 31.7% compared with the conventional algorithm.

Timing synchronization has a vital role in swarm drones’ network (SDN) or a swarm of unmanned aerial vehicle (UAV) network. Current timing synchronization methods focus on enhancing single-hop skews which remarkably improve timing synchronization precision at this level. The improper clock of the drone system can cause interference, affect spectrum precision and interrupt the operation of the transceiver. In the drones’ network, master drones’ (MD) neighbor drone’s timing synchronization approaches like Reference Broadcast System (RBS) realize a good performance. However, the requirement of one super drone with a large number of broadcasts for RBS makes it unrealistic to use in some situations like SDN network situation. Appropriate study and adjustments are needed to have real timing synchronization by eliminating the clocks drift and enhancing the timing synchronization precision. Therefore, a new self-timing synchronization approach is proposed in this paper where several MD drones can autonomously generate swarm clusters. The cluster head (CH) instigates a timing synchronization procedure starting with intra-Swarm cluster timing synchronization. The intermediate drones (ID) are elected between two swarm clusters to synchronize all drones in line with the inter-swarm cluster timing synchronization approach. The proposed approach is distributed and flexible to achieve high timing synchronization precision. The paper proposes a novel self-timing synchronization approach for in large scale semi-flat SND network architecture. Self-timing synchronization is swarm cluster-based and applicable for a huge number of master drones in SDN. One is the intra-Swarm cluster where the timing synchronization procedure starts with the CH to synchronize all CM. Secondly, in the inter-swarm cluster timing synchronization, two clusters are synchronized via intermediate drone (ID). However, the simulations demonstrated that in many cases all CHs are synchronized by the synchronized CHs from intra-swarm cluster timing synchronizations; this increased the system throughput and synchronization delay to about 75% compared to what we planned to achieve. Moreover, the simulation results also proved that the achieved synchronization precision can be used for position estimation and prediction with high accuracy.

Being sensitive to synchronization errors, symbol timing synchronization is a key factor affecting the performance of orthogonal frequency division multiplexing (OFDM) -based visible light communication (VLC) systems. A novel timing synchronization method based on odd-even symmetry for direct current biased optical OFDM (DCO-OFDM) is investigated in this paper. The proposed method produces an excellent pulse-like timing metric, resulting in a sharper peak at the correct place, while the values of other parts are negligible. The performance of the proposed timing synchronization approach is assessed by measuring the root mean squared error (RMSE) and mean absolute error (MAE) of timing offset estimation and bit error rate (BER) performance by computer simulation. The simulation results show that this novel symbol timing synchronization approach is superior to the typical methods for DCO-OFDM, such as the Park method and Guerra method, in various channel environments.

For the problem of system timing synchronization inaccuracy caused by impulsive noise in Multiple-Input Multiple-Output (MIMO) Power Line Communication (PLC), an Orthogonal Frequency Division Multiplexing (OFDM) symbol timing synchronization algorithm based on MIMO PLC system is proposed in this paper, which uses differential correlation and Maximum Ratio Combining (MRC) to improve the synchronization performance. Under 2×2 MIMO PLC channel model, the two transmitting ports send preamble sequences with good autocorrelation and cross-correlation characteristics. At the receiving end, the impulse noise in the power line is filtered by setting the threshold, and the timing coarse synchronization is realized by using the improved delay autocorrelation algorithm. Next, the window summation method is used to reduce the estimation range of fine synchronization. Then, a combined differential correlation and MRC algorithm is used in the timing fine synchronization stage, which has 2 dB improvement compared with the previous method. The simulation shows that the synchronization performance of the proposed method is obviously superior to the traditional cross-correlation method.

For the problem of system timing synchronization inaccuracy caused by impulsive noise in Multiple-Input Multiple-Output (MIMO) Power Line Communication (PLC), an Orthogonal Frequency Division Multiplexing (OFDM) symbol timing synchronization algorithm based on MIMO PLC system is proposed in this paper, which uses differential correlation and Maximum Ratio Combining (MRC) to improve the synchronization performance. Under 2×2 MIMO PLC channel model, the two transmitting ports send preamble sequences with good autocorrelation and cross-correlation characteristics. At the receiving end, the impulse noise in the power line is filtered by setting the threshold, and the timing coarse synchronization is realized by using the improved delay autocorrelation algorithm. Next, the window summation method is used to reduce the estimation range of fine synchronization. Then, a combined differential correlation and MRC algorithm is used in the timing fine synchronization stage, which has 2 dB improvement compared with the previous method. The simulation shows that the synchronization performance of the proposed method is obviously superior to the traditional cross-correlation method.

Copyright of Study on Optical Communications / Guangtongxin Yanjiu is the property of Study on Optical Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since orthogonal frequency division multiplexing (OFDM) systems are very susceptible to symbol timing offset (STO) and carrier frequency offset (CFO), which cause inter-symbol interference (ISI) and inter-carrier interference (ICI), accurate STO and CFO estimations are very important. In this study, first, a new preamble structure based on the Zadoff–Chu (ZC) sequences was designed. On this basis, we proposed a new timing synchronization algorithm, called the continuous correlation peak detection (CCPD) algorithm, and its improved algorithm: the accumulated correlation peak detection (ACPD) algorithm. Next, the correlation peaks that were obtained during the timing synchronization were used for the frequency offset estimation. For this, the quadratic interpolation algorithm was adopted as the frequency offset estimation algorithm, which was better than the fast Fourier transform (FFT) algorithm. The simulation results showed that when the correct timing probability reached 100%, under the parameters of m = 8 and N = 512, the performance of the CCPD algorithm was 4 dB higher than that of Du’s algorithm, and that of the ACPD algorithm was 7 dB. Under the same parameters, the quadratic interpolation algorithm also had a great performance improvement in both small and large frequency offsets, when compared with the FFT algorithm.

Copyright of Space-Integrated-Ground Information Networks is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An improved timing and frequency synchronization algorithm based on Zadoff-Chu(ZC) sequence for OFDM system is proposed. The algorithm constructs a training sequence with conjugate repetition relationship. Firstly, the timing synchronization is completed by utilizing the conjugate characteristics of the training sequence in time domain, and the integer frequency offset(IFO) estimation is obtained directly, not affected by the frequency synchronization performance. Then the fractional frequency offset(FFO) estimation is done using the repeatability of the training sequence after timing synchronization. Theoretical analysis and simulation results show that the improved algorithm′s timing and frequency offset estimation mean square error is lower, the integer and fractional frequency offset estimation range is expanded, and computational complexity is reduced.

Ground-based positioning systems are necessary as the conventional satellite-based systems suffer from weak received signals. In this paper, we proposed a precise ranging method in single-carrier frequency domain equalization (SC-FDE) system using the amplitude nonlinearity of oversampled signals. A new pattern of the preamble and the unique word was designed for SC-FDE system, where the preamble can be exploited in correlation-based timing algorithm to obtain impulse-like timing metric. Combining with the coarse timing procedure, we proposed a fine ranging method relying on the oversampled signals in SC-FDE receiver employing Qth-power nonlinearity, and then analyzed its estimation mean and variance. The extensive simulations were conducted to validate the proposed method with distinct modulation schemes, rolling-off factors, block lengths, and nonlinearity factors. The results show that the proposed ranging method can achieve unbiased estimate and its root mean square errors will reach the order of centimeter at medium-to-high signal-to-noise ratio region in flat-fading channels, whereas the observed performance degradation in frequency selective channel can be mitigated by using equalized oversampled signals.

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High definition video transmission is one of the prime demands of modern day communication. Changing needs demand diverse features to be offered by the video codec standards, H.264 fits to these requirements for video compression. In this work, an attempt has been made to optimize the inter prediction along with improved intra prediction to ensure the minimal bit rates thereby reduction in the channel bandwidth, which is required in most of the wireless applications. In intraprediction, only DC prediction mode is chosen out of 9 modes with 4*4 luma blocks that reduces the coding complexity towards optimal logic utilization in order to support typical FPGA board for hardware implementation. Most significantly, Inter prediction is carried out utilizing the M9K blocks efficiently with proper timing synchronization to reduce the latency in the encoding operation. Experimental set up comprising of two Altera DE2-115 boards connected through Ethernet cable demonstrated the video transmission. These optimized intra prediction and inter prediction stages resulted in significant improvement in the video compression possessing good subjective quality and increased video compression [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We consider the problem of uplink timing synchronization for Orthogonal Time Frequency Space (OTFS) modulation based systems where information is embedded in the delay-Doppler (DD) domain. For this, we propose a novel Random Access (RA) preamble waveform based on OTFS modulation. We also propose a method to estimate the round-trip propagation delay between a user terminal (UT) and the base station (BS) based on the received RA preambles in the DD domain. This estimate (known as the timing advance estimate) is fed back to the respective UTs so that they can advance their uplink timing in order that the signal from all UTs in a cell is received at the BS in a time-synchronized manner. Through analysis and simulations we study the impact of OTFS modulation parameters of the RA preamble on the probability of timing error, which gives valuable insights on how to choose these parameters. Exhaustive numerical simulations of high mobility scenarios suggests that the timing error probability (TEP) performance of the proposed OTFS based RA is much more robust to channel induced multi-path Doppler shift when compared to the RA method in Fourth Generation (4G) systems. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Because people do not consider the requirement of communication in the construction of power line, that resulting in the poor channel environment and the orthogonality between the sub-carriers are damaged. Meanwhile, the symbol offset will occur in the receiving terminal, which will cause the inter symbol interference, so it has very important significance to estimate and compensate the frequency offset and symbol offset for OFDM symbol effectively. According to the special frame structure of G3-PLC, this paper uses the double correlation detection method to compensate the frequency offset and symbol offset of the OFDM system. At last, the algorithm is confirmed by Monte Carlo approach. The results indicate that the synchronization algorithm used in this paper can be very good to compensate for the frequency offset and symbol offset of the system, and the algorithm is very simple and has strong adaptability to the channel.

The digital video broadcasting-terrestrial-second generation (DVB-T2) system provides the so-called P1 symbol as preamble for the fast synchronization tasks. In this paper, a simple and robust timing synchronization scheme for a multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM)-based DVB-T2 system is proposed to improve the initial time and frequency synchronization performance. In doing so, the proposed synchronization scheme utilizes a decimated correlation for the P1 symbol timing detection, thus producing a sharper peak timing detection metric. A new timing detection metric can help the proposed scheme to be robust against frequency-selective fading. It is found that the proposed synchronization scheme works well with a reduced computational complexity and outperforms the conventional estimation scheme.

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We constructed a synchronized femtosecond optical laser system with spatiotemporal stabilization for pump-probe experiments at SPring-8 Angstrom Compact Free Electron Laser (SACLA). Stabilization of output power and pointing has been achieved with a small fluctuation level of a few percent by controlling conditions of temperature and air-flow in the optical paths. A feedback system using a balanced optical-microwave phase detector (BOMPD) has been successfully realized to reduce jitter down to 50 fs. We demonstrated the temporal stability with a time-resolved X-ray diffraction measurement and observed the coherent phonon oscillation of the photo-excited Bi without the post-processing using the timing monitor. [ABSTRACT FROM AUTHOR]

Visible Light Communication (VLC) systems are more vulnerable to timing synchronization problems due to the employed incoherent modulation scheme. In this work, a blind timing synchronization algorithm is introduced to DC biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) systems, based on cyclostationarity of the received signal that relies on second-order statistics only. It does not require any channel impulse response, as it is a blind estimator. The performance of the proposed estimator is evaluated using computer simulations in the Lab-view software and also validated through experimental results obtained using the VLC testbed using Universal Software defined Radio Peripheral (USRP) hardware. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The traditional auto-correlation-based timing synchronization and the cross-correlation-based timing synchronization have the disadvantage that the sidelobe of the correlation peak is too wide or the timing metric is sensitive to carrier frequency offset (CFO). Neither of them can meet the fast and accurate timing synchronization requirement of wireless ad hoc communication system. To address these issues, this paper proposes a new timing synchronization algorithm based on the improved cross-correlation. By splitting a long correlator into the product of two parallel sub-correlators, the new method makes the main peak sharper and the second peak lower. The sensitivity to CFO and computational complexity are theoretically analyzed. The Monte Carlo simulation results of the proposed and the traditional cross-correlation timing algorithm show that while remaining the complexity level the proposed method has a gain of 1.1 dB in terms of detection accuracy and the CFO robustness is better. [ABSTRACT FROM AUTHOR]