This paper proposes a method of implementing an efficient Frequency Domain Equalization (FDE) as a post-equalization in the Faster-than-Nyquist (FTN) signaling block transmission system. The FDE is implemented by applying a process that pre-inserts and removes the cyclic prefix (CP) and the cyclic suffix (CS) for the pulse filter, the matched filter, and the channel respectively in the FTN signaling based block transmission system. Finally, we evaluate the simulation results of the performance of CP/CS-assisted FDE scheme for FTN block transmission system.

Abstract In this paper, we study the performance of a training‐based least square (LS) and linear minimum mean‐square‐error (LMMSE) channel estimation for both hop‐by‐hop and multi‐hop direct forwarding wireless sensor networks over frequency‐selective fading channels. Specifically, to investigate the properties of the channel estimation, we accomplish a theoretical analysis of MSE in terms of various link parameters. From the performance evaluation, we analytically present the effects of the number of hops on the MSE performance for channel estimations in both multi‐hop networks. Interesting observations of MSE behaviors under various conditions are discussed, and the receiver complexity and channel equalization performance are also analyzed. Finally, through the computer simulations, the analytical results and detection performance are demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.

Recently, filter bank multicarrier (FBMC) has been given a huge interest as an alternative to orthogonal frequency division multiplexing (OFDM). FBMC scheme has increased frequency efficiency and low out-of-band (OOB) emission as compared with OFDM. However, FBMC still suffers from a high peak-to-average power ratio (PAPR) as in OFDM systems. Several OFDM based PAPR reduction techniques have been adopted for FBMC system. In this paper, novel techniques for PAPR reduction for FBMC systems are proposed based on the evolution of the phase realignment (PR) and modified PR (MPR) techniques used for OFDM systems. The proposed PAPR reduction techniques are designed to improve the PAPR performance at the cost of minimal degradation of the bit error rate (BER) performances, defined by a transmit error vector magnitude (EVM). Unlike other existing techniques, the proposed techniques reduce the average power of the FBMC symbols, which help to retain low BER per unit energy. Simulation results show the proposed techniques as the potential alternative for PAPR reduction in FBMC systems.

In this paper, we analyze the effect of the imperfect channel estimation on the equalization performance in three-node cooperative wireless networks. Specifically, we consider a distributed time-reversal space-time block coded single-carrier (D-TR-STBC-SC) system over frequency-selective fading channels with amplify-and-forward (AF) half-duplex relaying. Through the comprehensive analysis of mean-square-error (MSE), it is shown that, unlike the point-to-point communications, the imperfection of the channel knowledge leads to the unstable performance of channel equalization under the condition of high quality reception from relay-to-destination link. The analytical results show the main reason for such phenomenon. The validity of the theoretical analysis is demonstrated through the computer simulations.

In this study, the authors investigate a distributed time‐reversal space‐time block coded (D‐TR‐STBC) system with amplify‐and‐forward full duplex relaying (FDR) over frequency‐selective channel. In the first, they present an FDR to use in a cooperative D‐STBC relaying in which a relay transmits the delayed signal as much as one frame in order to maintain the orthogonal property of STBC at the destination. Then, they briefly present the conventional full self‐interference cancellation (SIC) which continuously removes the self‐interference signal. As an alternative to the full SIC, they further introduce a partial SIC that periodically performs the SIC process. As a result, it can reduce cancellation processing by a half time compared to the full SIC. In the second, they propose the efficient and yet optimal destination structure consisting of the forward interference cancellation (IC), backward IC and joint equalisation and data combining in order to obtain a full coding gain. It is shown that the proposed D‐TR‐STBC‐FDR system has ∼3 dB signal‐to‐noise ratio gain compared to cooperative half‐duplex relaying with D‐TR‐STBC while it has the same diversity order. In addition, they show that there are no performance losses between FDR with full SIC and FDR with partial SIC.

In this paper, we present a cooperative system with amplify-and-forward (AF) multiple-full-duplex relays (FDRs) that receives and transmits signals simultaneously. In the first, we propose a new concept of delayed M-FDR relaying (M-D-FDR) scheme being able to achieve the full spatial diversity. At this time, we consider each delayed FDR receives a signal from source, adjacent relays and its delayed loop interference signal from its transmit antenna. In the second, we propose an efficient iterative successive interference cancellation (SIC) technique at destination that gradually cancels a delayed signal in order to fully obtain link diversity generated from M-D-FDR. Then, we investigate the various properties of the proposed M-D-FDR network by analyzing the pairwise-error-probability (PEP) analysis, especially in terms of signal-to-noise ratios (SNRs) between source to relays and source to destination links, respectively. Finally, we accomplish the performance evaluations to verify the analysis results and to compare with a non-delayed M-FDR (M-N-FDR) network.

We propose an improved CIR(Channel Impulse Response)-based fine STR(Symbol Timing Recovery) scheme for multi-input single-output (MISO) transmission mode of DVB-T2 system. At first, we present an efficient method to estimate the CIRs of MISO transmission. Then, the effective method for resolving the ambiguity of CIR is proposed by categorizing the ambiguity effect under the assumption of a false coarse STO(Symbol Timing Offset) and by changing the starting point of FFT window successively. Simulation results show that the proposed fine STR achieves the fine synchronization without an inter-symbol interference(ISI) in the large delay channels causing the ambiguity effect of CIR.

MIMO-OFDM system significantly improves the data rates over wireless channels. V-BLAST is well known effective technique which enhances the system performance while allowing low implementation complexity. However, the performance of V-BLAST technique would be degraded by the error propagation due to the nulling and canceling process. In order to improve the performance of V-BLAST, this paper proposes spatial diversity technique combined with rotated constellation for MIMO-OFDM systems. It is demonstrated in the simulation evaluation that the proposed technique can offer excellent performance with spatial diversity gain in time-varying typical urban channel.

An orthogonal frequency division multiplexing (OFDM) has been considered as most promising technique for the next generation mobile communication and broadcasting system to realize high-speed data rate and robustness to fading channel. However, main drawback in OFDM system is the high peak-to-average power ratio (PAPR) when a number of independently modulated subcarriers are added up coherently, and amplified by the high power amplifier (HPA). This paper classifies and illustrates systematic code design method of the high PAPR codes. Look-up table (LUT) based PAPR reduction method is proposed to exclude the high PAPR codes.

This paper introduces a novel data synchronization method for ATSC distributed translator (DTxR) to improve the indoor reception performance of DTV (Digital TV). The proposed method extracts the frame sync information from the received RF signal and utilizes it for constructing the rebroadcast signal of DTxR. Computer Simulations are performed for the basic working algorithm of prototype system and some practical application issues are described.

Multiple input multiple output (MIMO) system provides a promising means to increase the spectral efficiency. Orthogonal frequency division multiplexing (OFDM) allows broadband transmission over frequency selective fading channels. Recently, a coordinate interleaver (CI) is considered in order to maximize the diversity gain for MIMO system. In this paper, a new concept of coordinate interleaver for MIMO-OFDM system and an optimum receiver structure are suggested. Using the CI, the real and imaginary components of signals experience different fading channels and it provides additional diversity gains. Simulation results show that the system employing the proposed CI outperforms the conventional V-BLAST architecture.

In this paper, an exact distribution of channel capacity for MISO (Multiple-Input Single-Output) system with co-channel interference is derived from the information theoretical viewpoint. It is found that the MISO channel capacity in the noise-limited channel follows the chi-square distribution, and capacity in the interference-limited channel follows the F-distribution. Using these distributions of capacity, the outage capacity in Rayleigh fading channels can be accurately computed. From simulations, we have confirmed the accuracy of our analysis which exactly coincides with the empirical simulations in the noise-limited and in the interference-limited systems.

MIMO-OFDM systems would provide both multiplexing gain and diversity gain in order to improve the system capacity and the receive performance. This paper introduces the coordinate interleaved hybrid transmission for use in MIMO- OFDM systems to meet such requirements. The proposed CID- SFBC-OFDM and CID-STBC-OFDM combine the coordinate interleaver with Double SFBC-OFDM and Double STBC-OFDM to achieve additional diversity gain whilst retaining their spatial multiplexing gain. Our simulation results show that CID-SFBC- OFDM and CID-STBC-OFDM outperform the conventional schemes in typical urban (TU) channel.

This paper presents a robust block iterative/adaptive frequency-domain channel estimation scheme, in which a channel frequency response (CFR) is estimated iteratively through the proposed weighted element-wise block adaptive frequency-domain channel estimation (WEB-CE) using the soft information obtained from a soft-input soft-output (SISO) decoder. In the WEB-CE, an one-tap equalizer first structures the element-wise block by assembling its input elements out of discrete Fourier transform (DFT) of the soft information. Then, it updates the correction term of its coefficient in each block so as to minimize a weighted conditional squared-norm of the a posteriori error vector defined for the element-wise block. Simulation results verify the superiority of the WEB-CE in a time-varying typical urban (TU) channel.

In this paper, a weighted space-time block-coding (STBC)-like matrix-wise block adaptive frequency-domain equalization (WSB-FDE), which has a flexibility over the STBC-like matrix-wise block length as compared to a normalized least- mean-square (NLMS)-FDE and a recursive-least-square (RLS)- FDE, is proposed for the cyclic-prefixed STBC single-carrier systems equipped with a diversity combining. In the WSB-FDE, the STBC-like matrix-wise block is first formulated from received blocks. The correction terms of the equalizer coefficients in each block are then updated so as to minimize a weighted squared- norm of the a posteriori error vector for the formulated block. Moreover, a square-root adaptive algorithm based on an unitary Givens rotations is proposed to achieve the numerical stability and computational efficiency in update procedure of the WSB- FDE. Finally, simulation results show in a typical urban (TU) channel that the bit-error-rate (BER) performance of the WSB- FDE is superior to that of the RLS-FDE as the STBC-like matrix- wise block length increases.

In the space-time block-coded (STBC) single-carrier systems with a cyclic-prefix, decoupling and equalization procedures at the receiver require an exact channel impulse response (CIR). In this paper, we propose a weighted STBC-like matrix-wise block adaptive/iterative frequency-domain channel estimation (WSB-CE) that is operated iteratively by using soft information obtained from the SISO decoder. In the WSB-CE, the correction terms of the channel estimator coefficients in each block are calculated so as to minimize a weighted conditional squared norm of the a posteriori error vector in a weighted least-square (LS) sense. Our simulation results verify the superiority of the WSB-CE by comparing with an approximated modified recursive-least-square (RLS)-CE in the time-varying typical urban (TU) channel.

In this paper, a weighted space-time block-coding (STBC)-like matrix-wise block adaptive frequency-domain equalization (WSB-FDE), which has a flexibility over the STBC-like matrix-wise block length as compared to a normalized least-mean-square (NLMS)-FDE and a recursive-least-square (RLS)-FDE, is proposed for the cyclic-prefixed STBC single-carrier systems equipped with a diversity combining. In the WSB-FDE, the STBC-like matrix-wise block is first formulated from received blocks. The correction terms of the equalizer coefficients in each block are then updated so as to minimize a weighted squared-norm of the a posteriori error vector for the formulated block. Moreover, a square-root adaptive algorithm based on an unitary Givens rotation is proposed to achieve the numerical stability and computational efficiency in update procedure of the WSB-FDE. The theoretic convergence and the steady-state excess mean-square error (EMSE) of the WSB-FDE are analyzed, where it is observed that the EMSE decreases as the STBC-like matrix-wise block length and the number of antenna increase. Finally, the performance evaluation shows in a typical urban (TU) channel that the bit-error-rate (BER) performance of the WSB-FDE is superior to that of the RLS-FDE as the STBC-like matrix-wise block length increases.

In this paper, a weighted element-wise block adaptive frequency-domain equalization (WEB-FDE) is proposed for a single-carrier system with the cyclic-prefix. In the WEB-FDE, the one-tap equalizer corresponding to a frequency-bin first preserves input DFT elements (element-wise block). Its coefficient in each block is then calculated by minimizing a weighted squared norm of the a posteriori error. Simulation results in a time-varying typical urban (TU) channel show that the bit-error-rate (BER) performances of the WEB-FDE outperform those of the normalized least-mean-square (NLMS)-FDE and recursive-least-square (RLS)-FDE.

This paper investigates the subcarrier and power allocation problem of multi-user space-time block coded OFDM systems with each subcarrier shared by two users. The objective is to maximize the total system capacity subject to the power and proportional rate constraints of each user. A low-complexity suboptimal algorithm that separates subcarrier allocation and power allocation is proposed. Simulation results show that the proposed resource allocation algorithm for space-time block coded OFDM can improve the capacity significantly with the same BER performance compared with static FDMA fixed allocation algorithm and the MIMO-OFDMA scheme in which each subcarrier is used only by one user. Furthermore, the more important point is that it can make the capacity be distributed more fairly, very close to the ideal rate constraints, among users than the scheme which maximizes the system capacity only.

This paper presents an efficient design of the block adaptive frequency-domain equalization (FDE) for space-time block-coded (STBC) single-carrier system with the cyclic-prefix. We propose a weighted STBC-like matrix-wise block adaptive FDE (STBC-BFDE). In the STBC-BFDE, the STBC-like matrix-wise block is first formulated for the receive blocks. The correction terms of the equalizer coefficients in each block are then calculated in a weighted least-square (LS) sense that the weighted squared norm of the a posteriori error vector is minimized. An approximate steady-state excess mean-square error (EMSE) of the STBC-BFDE for the stationary optimal coefficient is also analyzed. From the theoretical analysis, it is shown that the EMSE decreases as the STBC-like matrix-wise block length increases. Simulation results also show in a time-varying typical urban (TU) channel that the bit-error-rate (BER) performances of the STBC-BFDE are improved as the STBC-like matrix-wise block length increases.

This paper presents a turbo coded OFDM receiver structure using joint synchronization, channel estimation and decoding. In this proposed scheme, the estimator uses soft-decision information from the previous soft-input soft-output (SISO) decoder to produce better estimates of the unknown parameters, which will in turn help the decoder to make more reliable decision. The whole process will be performed in an iterative manner and good system performance can be achieved with only a few iterations for moderate initial synchronization errors.

This paper proposes novel techniques to minimize the error propagation caused by large precursors and postcursors in decision feedback equalizer (DFE) of 8VSB DTV system. We first minimize the effect of large precursors by selecting a reference tap (symbol timing of DFE) from the channel estimation. By locating the reference tap, i.e., decision delay, in a feedforward filter (FFF) based on the channel estimation and the amplitude of a reference tap, the effect caused by large postcursors is minimized. Additionally, the combined structure of the feedback filter (FBF) and Viterbi decoder is proposed to correct the past incorrect decision symbols as well as to reduce the decision error probability. Simulation results show that the proposed techniques can prevent effectively the error propagation, and also they can remove much longer precursors as compared to conventional methods.

In this paper, we propose a novel transmitter identification (TxID) technique for use in distributed 8VSB DTV systems. Channel information (CI) is obtained by utilizing the properties of training sequence (TS). Channel applied data (CAD) is obtained by applying the detected DTV data to the estimated CI. Thereby, the CAD becomes similar to the received signal except for the embedded watermark. Since the in-band DTV signal can be eliminated efficiently from the received signal when the CAD is used, the proposed method will provide a large dynamic range and fast acquisition of TxID as well as high signal to interference and noise ratio (SINR).

This paper investigates the subcarrier and power allocation problems of MIMO-OFDMA systems in order to maximize the total system capacity subject to the total power and proportional rate constraints of each user. We proposed an efficient resource allocation algorithm to determine the number of subcarriers for each user and then assign the subcarriers to each user. Simulation results show that the proposed resource allocation algorithm can make the capacity be distributed more fairly, very close to the ideal rate constraints, among users than the scheme which maximizes the system capacity only

A new power and bandwidth efficient modem technique - correlative encoded FSK (CEFSK) is proposed for use in RF home networking system. Power spectral densities (PSD) and BER performance of CEFSK are analyzed and compared with those of GFSK via computer simulation. A new fractional multi-bit differential detection (FMDD) technique is also proposed in order to improve the BER performance of CEFSK. Our simulation results show that CEFSK has a spectral efficiency comparable to GFSK, and that BER performance of CEFSK using 5-branch FMDD technique outperforms that of GFSK by 2.0 dB at BER=1/spl times/10/sup -4/ in AWGN and multipath fading channel. It is also found that our FMDD technique provides a noticeable improvement of BER performance in the adjacent channel interference (ACI) environment.

The performance of 16-state SQAM (superposed-QAM) system, in a nonlinearly amplified multichannel environment, in the presence of additive white Gaussian noise (AWGN), intersymbol interference (ISI), and adjacent channel interference (ACI), is experimentally analyzed via computer simulation. Various channel conditions, such as channel spacings between the main and adjacent channels, and fade depth on the desired main channel, are examined. Baseband signal waveshape of 16-SQAM as well as the receive low-pass filter bandwidth are optimized to achieve a good P(e) performance. The result shows that 16-SQAM system is more efficient than MAMSK (multiamplitude MSK) in the frequency utilization. >

The performance of new bandwidth compressive 16 SQAM (Superposed-QAM) modems, operating in a highly power-efficient saturation mode, is analyzed. Nonlinearly amplified 16 SQAM retains the out-of-band energy much lower than 4-level rectangular (i.e., 16 QAM) or sinusoidal shaped (i.e., MAMSK) QAM, and operates within 0.7 dB of theoretical (i.e., 16 QAM in Nyquist linear channel) performance atP(e) = 10^{-6}using simple 4th-order Butterworth LPF's. Effects of baseband pulse shaping, receive filter BTs, power level variations and propagation time difference (or static phase shift) of transmit HPA's are analyzed in terms of BER.

A spectral and power efficient modulation techniquesuperposed quadrature amplitude modulation (SQAM-is introduced. In SQAM, the premodulation baseband signal is a double-interval (2T_{s}) raised-cosine pulse superposed with weighted single-interval (Ts) raisedcosine pulses. Our results indicate that SQAM has spectral advantages over OQPSK, QBL, and MSK, and betterP(e)performance than MSK, IJF-OQPSK (or SQORC), and TFM.