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In this article, a complexity-effective secondary synchronization signal (SSS) detection scheme is presented for fifth-generation (5G) new radio (NR) communication systems, which uses a gold sequence for SSS generation by multiplying two different m-sequences. By taking advantage of good autocorrelation property between cyclic-shifted versions of m-sequence, the search space of SSS hypothesis testing is reduced by decoupling the detection of two m-sequences. The combination of such a sequential strategy with maximum likelihood detection criterion facilitates low-complexity and reliable SSS detection in the 5G NR system. Both numerical and simulation results are presented to justify the effectiveness of the proposed detection scheme. It is demonstrated from presented results that the proposed SSS detector achieves a considerable complexity reduction while incurring slight performance loss, compared to existing SSS detectors. [ABSTRACT FROM AUTHOR]

Synchronization is a challenging problem of device-to-device (D2D) communications, particularly when D2D devices are out-of-network coverage. This article proposes an efficient initial synchronization method for D2D communication in a long term evolution system. The proposed synchronization approach is based on the correlation between both received primary sidelink synchronization signal and secondary sidelink synchronization signal to remove the effects of channel fading and symbol timing offset (STO). This design facilitates reduced-complexity joint detection of carrier frequency offset, sidelink synchronization signal, and cyclic prefix (CP) mode during the initial synchronization procedure. Simulation results show that the proposed synchronization scheme achieves robust and low-complexity detection of carrier frequency offset, sidelink synchronization signal, and CP mode when there is a nonnegligible STO or frequency-selective fading distortion. [ABSTRACT FROM AUTHOR]

The main features for future machine-type communication (MTC) cellular networks are to support low-power consumption, low-bandwidth, and long-range communication. One of the most challenging issues to meet these goals in the MTC cellular network is a low-complexity and reliable initial synchronization. To address this issue, in this article an efficient joint detection of integer carrier frequency offset (IFO) and cell identity (CID) is proposed for MTC in a long-term evolution (LTE) system. Unlike the conventional approach, the primary synchronization signal (PSS) and secondary synchronization signal (SSS) transmitted in the LTE-MTC system are used together to remove the effect of channel fading and symbol timing offset (STO). This design facilitates robust detection of the IFO and CID in the presence of residual STO without priori information on the SSS. The grouping of PSS subcarriers is integrated for joint detection, which plays an important role on reducing computational load. Both analytical and simulation results are provided to corroborate the feasibility of the proposed method. It has been demonstrated that the unique characteristics of the PSS and SSS sequences are effectively used for robust cell search in the presence of residual STO, compared to existing methods. [ABSTRACT FROM AUTHOR]

In this paper, a complexity-effective integer carrier frequency offset (IFO) and primary synchronization signal (PSS) detection scheme is proposed for 5G new radio systems. To estimate the IFO without any prior information about the PSS, the proposed detector uses the fact that three PSS sequences are cyclic-shifted versions of each other, which enables sequential detection of IFO and PSS. Both theoretical and simulation results are presented to verify the effectiveness of the proposed synchronization scheme. It is shown that the proposed scheme achieves a considerable complexity reduction while suffering from only slight degradation in the detection performance, compared to the conventional scheme. [ABSTRACT FROM AUTHOR]

The integrated services digital broadcasting-terrestrial (ISDB-T) system provides the interesting advantages of hierarchical transmission and partial reception using band segmented transmission orthogonal frequency division multiplexing scheme. In ISDB-T, the hierarchical configuration varies depending on whether a segment is modulated coherently or differentially. Thus, it is important to accomplish frequency synchronization regardless of segment type. For this purpose, an effective weighted least-squares (WLS) carrier frequency synchronization method is presented using transmission and multiplexing configuration control (TMCC) and auxiliary channel (AC) in a blind manner. Thus, the proposed estimation scheme is performed without resorting to a priori knowledge on segment type that can be known after correct TMCC decoding. To eliminate bias caused by using non-uniformly distributed TMCC and AC subcarriers, an appropriate subset is selected to form the basis of robust WLS estimation. Extensive simulations are conducted to verify the efficiency of the proposed WLS estimation method and compare its performance with that of the conventional WLS estimation scheme. [ABSTRACT FROM AUTHOR]

The integrated services digital broadcasting-terrestrial (ISDB-T) system adopts band segmented transmission orthogonal frequency division multiplexing (BST-OFDM) to support different services using hierarchical transmission. In the ISDB-T system, in particular, a hierarchical configuration depends on modulation type used in OFDM segment, which has to be decoded at the receiver. Therefore, it is necessary to detect integer carrier frequency offset (IFO) before decoding the modulation type carried through transmission and multiplexing configuration control (TMCC) signal. To address this issue, an effective IFO estimation scheme is presented for the ISDB-T system, considering information-carrying TMCC signal as pilot symbol without any need of additional pilots. In order to verify the performance of the proposed estimation scheme, theoretical detection error rate is derived. It is shown from simulation results that the redundantly transmitted TMCC signal can be efficiently utilized for IFO detection, offering an approximate performance of maximum likelihood detection. [ABSTRACT FROM AUTHOR]

In this paper, an efficient symbol timing offset (STO) and sampling frequency offset (SFO) estimation scheme is proposed in an orthogonal frequency division multiplexing-based digital radio mondiale system using cyclic delay diversity. By using a periodic nature of channel transfer function, cyclic delay and pilot pattern with a maximum channel power are chosen, which aids to enable a robust estimation of STO and SFO against frequency selectivity of the channel. As a performance measure, the mean squared error of the proposed scheme is theoretically derived and is verified through simulations. By simulation results, the proposed estimation scheme is proved to profit from properly selected cyclic delay and pilot pattern, with a superior performance over the conventional estimation scheme. [ABSTRACT FROM AUTHOR]

In this paper, we focus on improving the accuracy of frequency offset estimation for an orthogonal frequency-division multiplexing (OFDM) system under the conditions of the joint impairments in both carrier frequency offset (CFO) and in-phase/quadrature (I/Q) imbalance. To propose a robust CFO estimation scheme and to benchmark its performance, the performance of the conventional frequency estimation algorithm in the presence of I/Q imbalance is analyzed, and some modifications to the conventional estimation scheme are highlighted. We show via simulations that such a design achieves a remarkable robustness against I/Q imbalance; thereby, the proposed scheme can efficiently estimate the CFO, irrespective of the I/Q mismatch. [ABSTRACT FROM PUBLISHER]

In this paper, we propose an improved sampling frequency offset (SFO) estimation scheme for orthogonal frequency division multiplexing (OFDM) based digital radio mondiale (DRM) broadcasting systems. To demonstrate the performance of the proposed frequency estimator, analytical expression of the mean square error (MSE) is derived and performances are compared with conventional pilot-assisted estimators. Based on the simulation and theoretical analysis, our proposed estimator shows an improved estimation performance compared to the conventional estimators. [ABSTRACT FROM AUTHOR]

Cyclic delay diversity (CDD) is a simple transmit diversity technique for coded OFDM systems with multiple transmit antennas. However, high frequency selectivity caused by CDD degrades the performance of post- FFT estimation, i.e., integer frequency offset (IFO). This paper suggests a simple way of improving the performance of the IFO estimator based on the pilot subset partitioning which is designed to reduce the effect of frequency selective fading by adopting the CDD. By partitioning uncorrelated pilot subcarriers into subsets to satisfy high correlation, and performing frequency estimation for each pilot subset, a robust IFO estimation scheme is derived. The simulation results show that the proposed method can provide benefit to the overall system performance . [ABSTRACT FROM AUTHOR]

This letter proposes a low complexity integer frequency offset (IFO) estimation scheme in an orthogonal frequency division multiplexing (OFDM) based digital radio mondiale plus (DRM+) system with nonuniform phased pilot symbols. To reduce the computational complexity, the pilot symbols used for frequency estimation in the DRM+ system are partitioned into a number of pilot subsets, and pilots in each subset are phase-rotated to have a unique phase so that the estimator is made computationally efficient. [ABSTRACT FROM PUBLISHER]

A combining of MIMO signal processing with OFDM is regarded as a promising solution of enhancing the performance of next generation wireless system. Therefore, in the paper, an OFDM-based wireless system employing layered space-time architecture is considered for a high-rate transmission. With an emphasis on a preamble design for multi-channel separation, we address a channel estimation based on the time-domain windowing and its imperfectness in MIMO-OFDM system. By properly designing each preamble for multiple antennas to be orthogonal in the time domain, the channel estimation can be executed based on semi-blind processing in the case of more than two transmitting antennas. And also we evaluate PAR performance in the MIMO-OFDM system using the SLM and PTS approaches. The investigated SLM and PTS schemes for MIMO-OFDM signals select the transmitted sequence with lowest average PAR over all transmitting antennas and retrieve the side information very accurately at the expense of a slight degradation of the PAR performance. The low probability of false side information can improve the overall detection performance of the MIMO-OFDM system with erroneous side information compared to the ordinary SLM and PTS approaches, respectively. Also, we provide closed form of the average BER performance in MIMO-OFDM system using analytic approach. [ABSTRACT FROM AUTHOR]

This paper proposes an improved pilot-based algorithm for joint estimation of carrier frequency offset (CFO) and sampling frequency offset (SFO) in ultrawideband orthogonal frequency division multiplexing (UWBOFDM) systems with cyclic delay diversity. By proper selection of cyclic delay time and a frequency band with maximum channel power, a joint estimation of CFO and SFO is derived. Via computer simulation and analysis, the proposed frequency estimator is shown to benefit from the properly selected delay parameter and frequency band. [ABSTRACT FROM AUTHOR]

In this paper, we propose an improved and low-cost integer frequency offset (IFO) estimation method by partitioning pilot symbols effectively in an orthogonal frequency division multiplexing based digital radio mondiale (DRM) system. To this end, the time reference cell (TRC) symbol for frequency estimation is grouped into a number of pilot clusters, so that the TRC subcarriers in each cluster are closely spaced to show approximately frequencynonselective characteristics. The performance of the proposed IFO estimator is compared with that of the conventional estimator, and shows that the proposed technique can effectively achieve lower estimation errors in frequency offset estimation as well as can be implemented with reduced computational complexity. [ABSTRACT FROM AUTHOR]