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In order to solve the problem of inter-carrier interference (ICI) in fractional Fourier transform orthogonal frequency division multiplexing (FrFT-OFDM) system caused by time-frequency double selective channel, a joint self-cancellation scheme based on ICI self-cancellation coding and frequency offset compensation is proposed. In this scheme, the self-cancellation matrix with phase compensation is used to encode the signal. By taking advantage of the structural advantage of the adjustable rotation angle of the subcarriers in the FrFT-OFDM system, the fractional Fourier transform is carried out under the appropriate rotation angle to compensate the frequency offset, so as to achieve better ICI suppression effect than the traditional ICI self-cancellation technology under the same coding efficiency. The simulation results verify the performance of the scheme. [ABSTRACT FROM AUTHOR]

Underwater acoustic (UWA) communication is an essential technology that supports underwater surveys by transmitting images and movies wirelessly. However, UWA communication is still challenging due to the large delay and Doppler spreads in UWA channels. Doppler-resilient orthogonal signal division multiplexing (D-OSDM) under water has been found effective in such channels, but Doppler modeling errors prevent further improvement in communication quality. In this paper, we clarify the effect of Doppler modeling errors on the communication quality of D-OSDM and propose the use of a window function in D-OSDM to address the issues that such errors raise. We also evaluate the communication quality of D-OSDM using the window function through simulations and experiments. The experimental results show a 56% increase in the number of error-free data blocks, indicating that windowing can improve communication quality. [ABSTRACT FROM AUTHOR]

Visible-light communication (VLC) using light-emitting diodes (LEDs) is gaining attention in the wireless communication field. LEDs can be used as data transmitters without losing their main functionality as lighting devices. In some VLC applications, such as traffic signs and road signals in intelligent transportation systems, high brightness is required to help people recognize the signs and signals conveyed by the light sources. In this paper, the use of inverted modified prime sequence codes (MPSCs) is shown to be efficient for increasing brightness in an optical code-division multiple access (CDMA) system for VLC, while the original MPSCs, namely non-inverted codes, provide much lower brightness. The average light intensity of a system using an inverted MPSC is several times the intensity of a system using an original MPSC, without losing the capabilities of channel multiplexing and multi-user interference canceling. Average light intensity and normalized fluctuation are investigated for the optical CDMA systems with the original and inverted MPSCs. The results show that the systems with the inverted MPSCs provide higher average light intensity and lower normalized fluctuation than the systems with the original MPSCs do. Moreover, the bit error rates of the systems with the inverted MPSCs are evaluated by computer simulation and compared with those of the systems with the original MPSCs. [ABSTRACT FROM AUTHOR]

• Simultaneous ICI and SSBI suppression for the MWP SEFDM transmission link. • Constellation random displacement for performance improvement. • Good adaptability to different interference intensities. An iterative algorithm is proposed to simultaneously eliminate both the inter-carrier interference (ICI) and the signal-signal beat interference (SSBI) in the microwave photonic spectrally efficient frequency-division multiplexing (SEFDM) transmission systems. The received signal is iteratively modified to minimize the distortion. In each iteration, the modified signal undergoes the fast Fourier transform and the decoding process to obtain the bit information, which is then corrected and remapped into quadrature-amplitude modulation (QAM) symbols again to reconstruct the SEFDM signal for the signal modification in the next iteration. To enhance the performance of SSBI elimination and ICI compensation, random displacement is introduced to the QAM symbols before demapping, which can prevent the iteration from getting trapped in the local optimum. Experiments are conducted under different conditions, which indicate that the proposed method exhibits enhanced capabilities in interference cancellation and signal recovery compared to the conventional methods. Furthermore, the performance of the proposed algorithm in fiber transmission scenarios is experimentally verified. A 16-QAM SEFDM signal with a bandwidth compression ratio of 0.85 is successfully transmitted through a 25.2-km standard single-mode fiber with an error vector magnitude of 5.8 %. [ABSTRACT FROM AUTHOR]

Performing effective medium access control (MAC) encounters great challenges for mobile underwater acoustic networks (UANs), because it suffers from low signal-to-noise ratio, Doppler shift, large communication latency, and so on. Multi-carrier code-division multiple access (MC-COMA) is a promising modulation technique appropriate for solving the above restrictions. In this article, we design a novel MC-COMA-based cross-layer MAC scheme for mobile UANs, called MCI-MAC, to achieve efficient high-concurrency communication. Specifically, this method allocates spread spectrum sequences dynamically on the basis of velocity, propagation distance, data size, and data grade to improve robustness and flexibility of communication. Moreover, we propose an ant-colony-based optimal channel selection algorithm to decrease inter-carrier interference and inter-symbol interference, which concurrently maximizes energy efficiency and network throughput. In addition, we further propose a solution to solve multihop networks' collisions. Simulation results show that MCI-MAC is more effective than the state-of-the-art methods in mobile UANs. [ABSTRACT FROM AUTHOR]

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In high-mobility scenarios, the time variation of mobile radio channels leads to a loss of orthogonality among subcarriers in orthogonal frequency division multiplexing (OFDM) systems, resulting in intercarrier interference (ICI) and performance deterioration. Conventional channel estimation schemes are usually based on pilot tones, which are distributed in each OFDM symbol to estimate the channel variation. Hence, the channel estimator itself suffers from ICI. In this study, a new estimation scheme, which does not suffer from ICI, is proposed to estimate the channel variation within OFDM symbols. The main idea is to zero-pad (ZP) the OFDM symbol in the time domain. Then, in the middle of the ZP interval, an impulse signal is inserted as a pilot sample, which is used to estimate the channel at the pilot signal in the OFDM symbol. Finally, a linear model is used to estimate the channel variation over an OFDM symbol. Additionally, we derive the mean squared error (MSE) of the proposed estimation technique under the constraint that the channel varies linearly within OFDM symbols. Simulation results show that our scheme can achieve a substantial improvement in the bit error rate (BER) performance of OFDM, in spite of the OFDM symbol length being increased. Moreover, in many cases, the new scheme can achieve the same BER performance as the perfect knowledge of channel state information (CSI). Theoretical analysis and numerical simulations show that our scheme achieves excellent performance with much lower computational complexity. [ABSTRACT FROM AUTHOR]

Nowadays, there is a great demand for ultra-high data rate (UHDR) transmission on most 5th generation wireless networks. In this concern, the multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) scheme is used on a large scale to achieve UHDR transmission with reduced inter-symbol interference (ISI) and inter-carrier interference (ICI). Discrete wavelet transform-based OFDM (DWT-OFDM) provides better orthogonality due to presence of orthogonal wavelets, which mitigates the effects caused by ISI and ICI. Also, it has extended bandwidth than the traditional OFDM systems. But a major drawback in this system is that it suffers from down sampling. The down-sampling effect reduces the actual size of the input bit streams. As a result, the system performance is degraded. For solving this problem, a multilevel redundant discrete wavelet transform (ML-RDWT) is used instead of DWT to achieve improved spectral performance. Here, complex down-sampling operation is eliminated. From the simulation outcomes, it is clearly viewed that effects caused by ICI, ISI and BER are mitigated by improving the performance of CIR. The proposed method employs optimal red deer algorithm (ORDA) to locate the optimized weights for the ICI cancellation system. This algorithm enhances the spectral efficiency by achieving high CIR with reduced BER, ISI and ICI. The BER in the proposed MIMO-ML-RDWT-OFDM-ORDA method is 68%, 76%, 38% and 75%, which is very low when compared to the BER in the existing techniques like MIMO-DWT-OFDM-RDA, MIMO-RNS-OFDM-PNMA, MIMO-OFDM-BMA and MIMO-OFDM-ICIMA. The ISI in the proposed method is 94%, 91%, 95% low when compared to the ISI in the existing techniques. The ICI in the proposed work is 71%, 57%, 73% and 86% low when compared to the ICI in the existing techniques. Therefore, the general performance of the proposed MIMO-ML-RDWT-OFDM-ORDA method is improved in an efficient way with less complexity, error rate and processing delay. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) is considered to be a new technology with great potential and is being studied extensively and deeply. And the application extension of STBC in the RIS-aided scheme provides a new train of thought for the research of channel coding. In this paper, we propose we extend the scheme of using the RIS to adjust the phase and reconfigure the reflected signal and propose the design of the RIS-aided QO-STBC scheme and the RIS-aided QO-STBC scheme with interference cancellation. Particularly in the RIS-aided QO-STBC scheme with interference cancellation, the design can achieve the transmission of the full rate and full diversity using an auxiliary reflection group to eliminate the influence of interference term. Also, the advantages and disadvantages of the schemes are analyzed in the paper, and the decoding algorithms with different complexity used in the proposed schemes are described. The simulation results show that the performance of the RIS-aided QO-STBC scheme with interference cancellation is better than that of the RIS-aided QO-STBC scheme and the RIS-aided Alamouti scheme by about 5 dB and 7 dB at 1 0 − 3 BER because of diversity gain and coding gain. [ABSTRACT FROM AUTHOR]

Performance of visible light communication systems which is encoded using turbo product codes is studied in this article. It is the first time to show the effect of turbo product codes in these systems. We chose ceiling bounce model since its accuracy with the practical measurements is proved. Our simulations are carried out in two different link distance and two different data rates. Encoder parameters are selected according to the code rate. This way, meaningful comparison can be made among the results considering distance, data rate, and code rate. Our investigations infer that using turbo product codes, higher data rate is achieved where link distance is the same. Similarly, it can be reached higher link distance when data rate is set to a constant value. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation scheme that combines a large number of low data rate carriers into a composite high data communication system. Unlike in many other modulation techniques, the addition of cyclic prefix to the OFDM symbols combats the intersymbol interference and the orthogonality of the carriers allows it to combat Intercarrier interference in the OFDM modulation technique. Acknowledging these advantages, OFDM is the most preferred modulation technique in most of the next-generation wireless communication networks for transmitting many forms of digital data with higher efficiency. To evaluate the functionality and overall performance of an OFDM system, a digital data corresponding to a two-dimensional gray-scale image is used as a test signal. This paper aims at evaluating the performance of various phase shift keying (PSK) techniques taking a real time image as a test sample, which is converted into a form suitable for OFDM transmission, then transmitting the converted OFDM signal over the additive white Gaussian noise channel over various signal to noise ratio values. The performance is evaluated by comparing the clarity of the received image after demodulation with the original image, bit error rate (BER) Vs SNR, transmission and reception times of various PSK schemes (BPSK, QPSK,16-PSK and 256-PSK). The BER offered by BPSK is the least while transmission times offered by 256-PSK is the least. Along with these, different PSK schemes are compared by changing the clipping amplitude that is done to combat nonlinearities due to high peak to average power ratio. [ABSTRACT FROM AUTHOR]

Advanced wireless communications to support high vehicular speeds in the scenario of intelligent mobility have attracted considerable research attentions in both academia and industry. Multi-dimensional index modulation, which exploits transmission media resources for combining the concept of index modulation to achieve higher throughput with lower energy consumption, is regarded as a potential candidate for addressing the challenges in intelligent mobility communications. However, for the multi-dimensional index modulation system used in the mobile environment, the inter-carrier-interference (ICI) imposes a significant adverse impact on the system, especially in the context of multicarrier transmission. Therefore, by focusing on the two-dimensional index modulation system, the ICI impact on space-frequency index modulation is studied in this paper. Thanks to the grouping strategies and the Gaussian approximation to model the ICI, the approximate theoretical bounds for the error performance of the two dimensional systems are derived. Moreover, a novel robust space-frequency index modulation scheme is also developed. Finally, simulation results are presented to validate the system performances and the theoretical derivations.

Multiple carrier frequency offsets exist in the orthogonal frequency-division multiple access (OFDMA) uplink receivers, and consequently induce inter-carrier interference and multiple-access interferences simultaneously. We therefore propose a joint carrier frequency offset (CFO) and channel estimation scheme by leveraging the characteristic of transmission signals in the OFDMA uplink systems. A fully loaded assignment of subcarriers to active users is also supported by the proposed method. By modeling the system in a Hadamard product form, we develop an iterative algorithm wherein a closed-form estimate of CFO and channel is applied in each updating iteration. Different from the traditional expectation-maximization type methods, which update only a single CFO and channel of one user while keeping the other users' CFOs and channels constant in each iteration, our proposed scheme updates the CFOs and channels of all active users simultaneously. Therefore, the proposed CFO and channel estimator enjoys faster convergence and lower complexity. Through numerical results, the proposed scheme is demonstrated to be robust to large CFOs and perform comparably well to the conventional approaches. [ABSTRACT FROM AUTHOR]

Achieving higher spectral efficiency is an efficient approach to address the bandwidth crisis of optical networks, but it faces significant technical challenges. High-spectral-efficiency non-orthogonal frequency-division multiplexing (NOFDM) has been proposed for meeting the requirement of optical networks' capacity upgrade. Compared to orthogonal frequency-division multiplexing, NOFDM can achieve higher spectral efficiency by compressing the subcarrier spacing narrower than the Nyquist orthogonal spacing, but this inevitably induces inter-carrier interference (ICI). ICI cancellation algorithms are crucial in NOFDM for correctly recovering the transmitted signal at the expense of extra processing power. Nowadays, processing power is no longer the obstacle to eliminate ICI due to the rapid development of application-specific integrated circuits for efficient implementation of digital signal processing. In this article, fast multiplexing and demultiplexing for NOFDM are implemented based on inverse fast Fourier transform and fast Fourier transform, respectively. Meanwhile, three representative ICI cancellation algorithms are discussed, and one of them is experimentally implemented. Furthermore, we propose non-orthogonal discrete multitone (NODMT) by integrating the advantages of NOFDM and DMT, which has the potential to achieve improved spectral efficiency for future optical networks. [ABSTRACT FROM AUTHOR]

This paper designs and analyzes the bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) framework under color-shift-keying (CSK) modulation to achieve spectrally efficient transmissions in visible light communication (VLC) systems. Specifically, we investigate the protograph low-density parity-check (LDPC) codes, bit-to-symbol mapping schemes, and constellation labeling rules in higher-order CSK-aided VLC systems. To fully explore the BICM-ID benefit, we propose an irregular CSK mapping, in which an $M$ -ary standardized constellation (called “Standard constellation”) and a new $M$ -ary constellation (called “Target constellation”) are separately applied to modulate two different coded sub-blocks in a codeword to optimize the error performance of the CSK-aided VLC systems. Furthermore, using a modified protograph extrinsic information transfer (PEXIT) algorithm, we construct two types of protograph LDPC codes (i.e., unpunctured and punctured protograph LDPC codes) that outperform the conventional protograph LDPC codes. Both analytical and simulation results show that the proposed irregular-CSK-mapped BICM-ID employing the new protograph LDPC codes and Target constellation is capable of achieving outstanding performance, and is a promising transmission solution for high-speed VLC applications. [ABSTRACT FROM AUTHOR]

To overcome unpredictable spikes in the peak-toaverage power ratio (PAPR) in the presence of an orthogonal frequency-division multiplexing (OFDM) for multi-input-multioutput (MIMO) systems, implementation of a new SLM scheme is presented in this paper, which is extended from our previous study of IQ-SLM in SISO-OFDM system. In each transmit antenna, both real and imaginary parts of the base-band data symbol were modified independently using a corresponding phase element within a commonly generated phase vector, instead of modifying the complex data symbol as a single component. After applying an inverse fast Fourier transform (IFFT) for the real, imaginary, and original base-band vectors, the minimum PAPR component was observed. Therefore, the phase vector that introduced the minimal PAPR was considered to convert the original data block for transmission. This technique is called the In-phase/Quadrature-SLM (IQ-SLM) scheme. In this proposal, only U phase vectors were generated to treat all Nt data blocks, simultaneously, unlike the conventional MIMO-SLM techniques which generate UNt candidate phase blocks. The thing which, in turn, can be considered as a further computational complexity reduction, specifically in data-phase conversion stages. As a result, in terms of the complementary cumulative distribution function of PAPR performance(CCDF-PAPR), the proposal achieved a greater decibel reduction than conventional SLM methods such as dSLM, oSLM, and sSLM, at different subcarrier lengths N, candidate phase vectors U, transmit antennas Nt. Also, it shows a comparable BER performances over the dSLM scheme referencing to the theoretical curves, in the case where Nt ≤ Nr for both zero-forcing (ZF) and ZF with vertical Bell laboratories layered space-time (V-BLAST) detector. [ABSTRACT FROM AUTHOR]

Due to the imaginary interference, the filter bank multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) performs poor in context of multiple-input multiple-output (MIMO) communication scenarios. In this article, we propose an imaginary interference-free method for FBMC/OQAM, which is appropriate for both of the subcarrier-based singular valued decomposition (SVD) precoding as well as subband-based precoding with codebook schemes. Specifically, the critical design utilizes a repeated block with the reverse arrangement of symbols. Moreover, we investigate the leakage of imaginary interference of the precoding MIMO-FBMC/OQAM system under frequency selective channel. It is found that these developed precoding solutions may particularly inhibit the inter-carrier interference (ICI) via the meticulous designed symbols block. Theoretical analysis and simulation results over different frequency selective channels validate that the proposed precoding schemes are capable of providing considerable performance gains over the conventional schemes in terms of bit error rate (BER). [ABSTRACT FROM AUTHOR]

In order to mitigate the error propagation (EP) effect on the bit error rate (BER) performance due to the imperfect successive interference cancellation for the non-orthogonal multiple access (NOMA)-based visible light communication (VLC) downlinks, adjustable bit rate superposition coding (ABRSC) and sample-and-sum successive interference cancellation (SSSIC) decoding schemes are proposed in this paper. Based on the modified fixed-power allocation (MFPA) strategy, the closed-form expressions of BER are derived for the two-user case with on-off keying, and further extended to the multi-user scenario. The residual probability of EP is introduced and derived to theoretically assess the effectiveness of the proposed ABRSC and SSSIC schemes. Monte Carlo simulation is also conducted to validate the analytical BER results. The BER performance of the NOMA-based VLC system with multiple users is further analyzed and discussed in detail. It is found that under the total average optical transmission power constraint, the allocated average optical transmission power to current user should be higher than that to all rest of users, i.e., the power allocation factor (PAF) is supposed to be greater than 1/2, in order to avoid the error floor issue of current user, hence facilitating the successful implementation of SSSIC. Besides, increasing the bit-rate factor (BRF) could mitigate the effect of EP, and larger BRF leads to more efficient outcomes in alleviating the effect of EP. [ABSTRACT FROM AUTHOR]

In this letter, performance analysis of orthogonal frequency division multiplexing with index modulation (OFDM-IM) is presented in term of bit error rate (BERs). The analysis considers its performance under two impairments, symbol time offset (STO) and carrier frequency offset (CFO) in frequency-selective fading channel. As orthogonal multicarrier system, OFDM-IM is subject to both inter-symbol interference (ISI) and inter-carrier interference (ICI) in a frequency-selective fading channel. OFDM-IM is a new multicarrier communication system, where the active subcarriers indices are used to carry additional bits of information. In general, in the previous existing works, OFDM-IM are evaluated only for near-ideal communication scenarios by only incorporating the CFO factor. In this work, the OFDM-IM performance is investigated and compared with conventional OFDM in the presence of two impairments, STO and CFO. Simulation results show that OFDM-IM outperforms the conventional OFDM with the presence of STO and CFO, especially at high SNR areas. [ABSTRACT FROM AUTHOR]

Secure downlink transmission in massive multiple-input multiple-output (MIMO) systems has sparked great research enthusiasm. However, the secrecy of uplink transmission is equally important although relatively less attention has been dedicated to. In this paper, we show that a multi-antenna eavesdropper could potentially reduce the secrecy rate of legitimate communications severely through channel estimation in the training phase and coherent detection in the payload data transmission phase. To safeguard uplink transmission, an artificial noise (AN)-assisted scheme is proposed. Specifically, the optimization problem that aims to optimize the power allocation between AN and data symbols in the sense of maximizing the secrecy rate is formulated. We investigate optimal power allocation strategies for two distinct cases. That is, the base station and the eavesdropper know the channel state information to the users, and the opposite case. In each case, we further consider whether the accurate position of the eavesdropper is known to the users. Due to the complexity of the cost function, a closed-form solution is intractable. As a result, the bisection method is employed to obtain the numerical results. The impacts of the non-idealities, including the channel estimation error and the uncertainty of eavesdropper's position, on the power allocation strategy are discussed. Finally, extensive simulations are carried out to validate our proposed algorithms. [ABSTRACT FROM AUTHOR]

Impulsive noise significantly deteriorates the performance of orthogonal frequency-division multiplexing (OFDM)-based underwater acoustic (UWA) communication systems. The pulse blanking (PB) based approach can mitigate the impulsive noise. However, it causes inter-carrier interference (ICI) and signal attenuation to the receiver. In this work, we first show that the ICI introduces pronounced non-Gaussianity to the receiver chain and leads to significant performance degradation. We then propose a non-Gaussianity-aware iterative ICI cancelation scheme to mitigate the adverse impacts of PB. A companding transformation scheme is incorporated into the soft symbol computation to alleviate the non-Gaussianity of the log-likelihood ratios (LLRs) caused by the residual ICI and impulsive noise. Simulation results illustrate that the proposed non-Gaussianity-aware iterative receiver achieves significant performance gains over the conventional non-Gaussianity-agnostic one with even lower computational complexity. [ABSTRACT FROM AUTHOR]

The nonlinear distortions attributed by the radio frequency (RF) power amplifier (PA) and other RF circuits from the enormous bandwidth of millimeter wave (mmWave) and high frequency design limitations of the integrated circuits involved, degrade the performance of the hybrid mmWave multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. This nonlinear distortions in the hybrid mmWave systems cause nonlinear coupling of the hybrid precoder with the data signals. Further, it induces intercarrier interference (ICI) in the OFDM systems, which also involves the interference from the precoders of other subcarriers. These difficulties in collusion with frequency selective channel and carrier frequency offset (CFO) may pose great challenges to the estimation accuracy of these parameters (channel gains and CFO) and signal detection. The nonlinearity causes the target posterior distribution for data detection as non-Gaussian and analytically intractable. In this work, we present a novel pilot assisted maximum likelihood (ML) based framework for estimating the CFO with PA impairment in the time domain by formulating a low dimensional equivalent channel matrix. The low dimensional equivalent channel matrix is composed of hybrid precoders-combiners, high dimensional MIMO channel, and the nonlinearly distorted components from PA. We further propose a group-sparse Bayesian learning (G-SBL) based semi-blind channel estimator in the time domain, which incorporates the CFO and nonlinearity of PA in its estimation process. With the estimated channel, a procedure to obtain the hybrid precoder and combiner matrices for data transmission is developed next. An iterative algorithm based on particle filter (PF) that effectively handles the nonlinear coupling of precoder matrix with data, and ICI is also proposed for data detection. The performance of the algorithms are evaluated on two different channel models: (a) synthetic geometric based mmWave channel (b) realistic mmWave channel for an urban microcell (UMi) environment. To validate the efficacy of the CFO and channel estimator, the Cramer-Rao bound (CRB) and Bayesian CRB (BCRB) are derived respectively. [ABSTRACT FROM AUTHOR]

• Phase noise induces ICI in optical coherent OFDM transmission. • For DFT-S OFDM, phase noise in symbol domain is similar to that in time domain. • The proposed phase noise compensation is operated in time domain and symbol domain. • The compensation scheme can efficiently suppress ICI induced by phase noise. Previous studies have revealed the similarity between phase noise in the symbol domain of discrete Fourier transform spread (DFT-Spread) coherent orthogonal frequency division multiplexing (CO-OFDM) systems and that in the time domain. This paper further details this characteristic through both formulas and simulation results, while also analyzing and summarizing its formation conditions and influencing factors. Based on this, a phase noise compensation (PNC) scheme based on DFT-Spread OFDM is proposed for high-order quadrature amplitude modulation (QAM) transmission with large fast Fourier transform (FFT) sizes. The proposed scheme effectively suppresses inter-carrier interference (ICI) introduced by phase noise in OFDM systems, as verified through simulations of dual-polarization (DP) 64-QAM CO-OFDM transmission over 80 km single-mode fiber (SMF). This work suggests that proposed PNC scheme enhance the tolerance for laser linewidth in OFDM systems, and may offer a possible solution for short distance high-baud-rate high-order QAM coherent transmission. [ABSTRACT FROM AUTHOR]

In this paper, a new precoder for a coherent optical filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) system is proposed. The precoder is designed based on an iterative polynomial eigenvalue decomposition (PEVD) algorithm to jointly mitigate the inter-symbol interference and inter-carrier interference. The PEVD algorithm is used to decompose a polynomial channel matrix into polynomial eigenvectors and eigenvalues matrices, then a precoder is designed based on the decomposed matrices. The precoder acts as a filter applied to each subcarrier and to its adjacent subcarriers. In addition, a new adaptive optimum energy algorithm is proposed to truncate the insignificant precoder filter coefficients produced by the PEVD algorithm and consequently reduce the computational complexity. A mathematical model and algorithm for implementing the precoder are also presented. Robustness of the proposed precoder has been analyzed and compared to existing precoder in optical channel with different dispersion effects. Numerical results demonstrate that the new precoder significantly outperforms the existing precoder in terms of error vector magnitude, bit error rate, Frobenius norm of the error matrix, and computational complexity.

Automatic gain control (AGC) is widely adopted in orthogonal frequency division multiplexing (OFDM) systems to compensate the significant variation of the received signal. In OFDM systems, the duration of the cyclic prefix (CP) is usually equal to the delay spread of the channel to minimize the system overhead. The inter-symbol interference (ISI) between consecutive OFDM symbols spreads over a large portion of the CP. The CP contaminated by the ISI should not be used to estimate the received power. If the duration of the remaining CP is shorter than the settling time of the AGC, then the gain adjustment will be carried out within the useful portion of the OFDM symbol. The subcarrier orthogonality is lost and the system performance is degraded by the resulting inter-carrier interference (ICI). In this paper, we propose a simple and efficient scheme to mitigate the ICI. The proposed scheme can be easily implemented in actual systems because of its low computational complexity. The simulation results show that the proposed scheme can increase the signal-to-interference-plus-noise ratio significantly compared to the traditional scheme.

This paper studies the application of physical-layer network coding (PNC) in vehicle-to-everything communications to accommodate the time-critical nature of vehicular ad-hoc networks (VANETs). The idea can theoretically reduce the transmission latency by 50%, thus alleviating the short contact time issues caused by high-speed vehicle motion. Conventional studies of PNC primarily considered static networks. In highly mobile networks like VANETs, the carrier frequency offsets (CFOs) due to high-speed motion will lead to inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) systems. Moreover, the vehicular environment with time–frequency-selective channels further undermines accurate channel estimation for multiple users. It is also worth noting that the CFO that exists in OFDM modulated PNC cannot be completely eliminated through CFO tracking and equalization as in conventional point-to-point transmissions. These critical issues can significantly increase the bit error rate at the receiver. To address these challenges, this paper proposes an ICI-aware approach that jointly achieves accurate channel estimation, signal detection, and channel decoding. We express the channel estimation and detection and decoding as two optimization problems and resolve them with the expectation–maximization algorithm and the belief propagation algorithm, respectively. The proposed approach can efficiently mitigate the negative effect of ICI by exploiting both pilot and data tones in channel estimation, detection, and decoding. Both simulation and experiment are conducted to evaluate the proposed approach, and the results reveal that the proposed algorithm outperforms the benchmark that simply treats ICI as Gaussian noise.

In this paper, calculations of intercarrier interference (ICI) and bit error probability (BEP) of hyperbolic fractional Fourier transform (FRFT) based systems for the satellite internet of things applications, has been considered. Analysis of ICI power and BEP in Rician flat fading channels has been done, mathematically. Simulations approve that the systems based on the hyperbolic FRFT are resistant against carrier frequency offset in high-speed moving conditions. Also, in severely deep fade conditions, the hyperbolic FRFT based systems have an acceptable performance in the achieved bit error probability. [ABSTRACT FROM AUTHOR]

The 3rd Generation Partnership Project (3GPP) adopted cyclic prefix OFDM (CP-OFDM) for both uplink and downlink communications (although DFT-s-OFDM is also allowed in the uplink) in 5G New Radio (NR) Release 15. However, due to the variety of proposed deployment options and scenarios, a single numerology will not be enough to fulfil all performance requirements. A scalable OFDM numerology was required to enable diverse services on a wide range of frequencies and deployments, and finding the right numerology for each scenario is of special relevance for the proper functioning of 5G NR. Using a simulator calibrated according to the parameters established for NR performance by the 3GPP, this paper presents the performance evaluation of NR for the main 5G scenarios and different CP-OFDM numerologies and device speeds. Results show that increasing subcarrier spacing boosts the strength of the system against intercarrier interference (ICI) caused my Doppler spread; however, to increase subcarrier spacing, the CP must be reduced proportionally, which makes intersymbol interference (ISI) and ICI caused by insufficient CP have a more predominant effect. Therefore, it is necessary to quantify the total interference of the system, in order to determine the proper numerology for each scenario, which will depend on all the factors mentioned above, and not only on the operation band, as suggested in the standardization process. All this allows concluding that the choice of the appropriate numerology for a particular system depends not only on the band of operation but also on the deployment scenario and the speed of the user equipment (UE). Likewise, it is concluded that it is even possible to use more than one numerology for the same scenario. [ABSTRACT FROM AUTHOR]

This article investigates the reliability gain of broadcast (BC)/broadband (BB) cooperation for mobile scalable video streaming. A specific form of BC-BB cooperation is introduced, which is referred to as cooperative casting. The proposed system primarily utilizes a BC transmission for streaming, while BB backup transmissions are requested whenever the BC signal is not decodable. For BC deliveries in this system, a cross-layer collaboration between scalable video coding (SVC) and layered-division multiplexing is used to improve spectral efficiency by coupling their hierarchical structures. In this end, in tandem with designing the uplink requesting rules based on channel status, delivery performance of the cooperative casting is analytically evaluated in a probabilistic framework. The system design and analyses presented in this article focus on the service continuity in a mobile and time-varying channel, where the physical aspects, such as delayed unicast response and inter-carrier interference, are carefully taken into account. Compared to the standalone network transmissions, the cooperative casting is numerically verified to better prevent the delivery failures in high-speed mobile channels, especially when the SVC layer-combined (full-scale video) service is intended. Furthermore, it is also shown that relaxing the criteria for the BB stream requesting can reduce delivery failures substantially, while it increases transmission redundancy. [ABSTRACT FROM AUTHOR]

Filter bank multicarrier (FBMC) seems to be one of the new waveforms candidate for fifth generation (5G) to utilize the available bandwidth and fit the requirements of high spectral efficiency (SE), less Out-of-band emission (OOBE) and self equalization. Although it has powerful advantages, FBMC has some drawbacks. Some of the most significant drawbacks are Imaginary Inter-Carrier Interference (ICI) and/or Inter-Symbol Interference (ISI) problems. The main objective of this paper is to compare between different types of preamble-based channel estimation (CE) methods for time invariant channels using single/multiple antenna systems with special attention in Interference Approximation Methods (IAM). A comparison among different structures of IAM such as: IAM-R, IAM-C, E-IAM-C, NPS and N-IAM is presented. It is performed mainly in terms of performance metrics such as: Bit Error Rate (BER), Peak to average power ratio (PAPR), and Mean Square Error (MSE). [ABSTRACT FROM AUTHOR]

In-home health networks greatly rely on the massive connected monitoring devices. Compared to orthogonal multiple access (OMA), non-orthogonal multiple access (NOMA) can connect more monitoring devices and enhance the spectrum efficiency (SE) performance, which makes it an ideal solution to in-home health networks. However, conventional NOMA (C-NOMA) is mostly constrained to single-carrier scenario. The problem of multi-carrier NOMA lies in the inter-carrier interference (ICI) from neighboring carriers. In this article, we propose a sparse vector coding-based NOMA (SVC-NOMA) to suppress the ICI. We give closed-form expressions of capacity and symbol error rate (SER) performances for both C-NOMA and SVC-NOMA within the considered multi-carrier scenario. Simulation results demonstrate that compared to C-NOMA, SVC-NOMA has better capacity and SER performances. In addition, we find from our results that there is a trade-off between SVC-NOMA’s ICI suppression ability and the system capacity performance. [ABSTRACT FROM AUTHOR]

Under-Water Acoustic (UWA) communication networks are commonly formed by associating various independent UWA vehicles and transceivers connected to the bottom of the sea with battery-operated power modems. Orthogonal Frequency Division Multiplexing (OFDM) is one of the most vital innovations for UWA communications, having improved data rates and the ability to transform fading channels into flat fading. Moreover, OFDM is more robust on Inter- Symbol and Inter-Carrier Interferences (ISI and ICI respectively). However, OFDM technology suffers from a high Peak to Average Power Ratio (PAPR), resulting in nonlinear distortions and higher Bit Error Rates (BERs). Saving power of battery deployed modems is an important necessity for sustainable underwater communications. This paper studies PAPR in UWA OFDM communications, employing Selective Mapping (SLM) as a tool to mitigate PAPR. The proposed SLM with the oversampling factor method proves to be less complex and more efficient. Simulation results indicate that SLM is a promising PAPR reduction method for UWA OFDM communications reducing BER. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impact of rate and power adaptation (RPA) and rate adaptation (RA) using square M-ary quadrature amplitude modulation (MQAM) on the average spectral efficiency (ASE) of orthogonal frequency division multiplexing (OFDM) systems under instantaneous bit-error-rate (BER) constraint over high mobility Nakagami multipath fading (NMF) channels. Especially, the closed-form expressions for the average spectral efficiency (ASE) of RPA and RA are obtained when these adaptive schemes are used over NMF channels with existence inter-carrier interference (ICI) caused by the high mobility. By comparing the ASE of RPA and RA under different number of subcarriers, a simplified rate and subcarriers bandwidth adaptation (RSBA) algorithm is obtained. Simulation results indicate that RSBA is more suitable for high-speed communication environment than RA. [ABSTRACT FROM AUTHOR]

OFDM is a multicarrier transmission technique, widely preferred due to advantages like high data rate, less bandwidth consumption and channel robustness. IEEE 802.11a standard uses conventional OFDM which uses IFFT for generating orthogonal carriers and multiplexing. Due to extra bandwidth consumption by cyclic prefix in conventional OFDM, DWT has now emerged as new alternative over FFT. It offers advantages like increased spectral efficiency, better orthogonality and less bit error rate. Performance degradation due to frequency offsets has been reported in literature. Carrier frequency offset (CFO) arises due to Doppler shift and imperfect synchronisation of transmitter and receiver. CFO results in inter-carrier interference that effect BER. In this paper, we investigated the offset effect on conventional and DWT-based OFDM under different communication channels (AWGN and Rayleigh). Effect of different modulation techniques and wavelets on DWT-OFDM model is also analysed. [ABSTRACT FROM AUTHOR]

This paper addresses the carrier frequency offset (CFO) problem in OFDM modulated physical-layer network coding (PNC) operated in a two-way relay channel (TWRC). CFO, caused by node-motion induced Doppler shifts and/or asynchronous oscillators, induces inter-carrier interference (ICI) between OFDM subcarriers and hence, degrades PNC performance. To mitigate the CFO/ICI effect in PNC, this paper considers channel-coded PNC and focuses on the receiver design at the relay. CFO compensation, signal detection, and channel decoding are the three basic signal processing blocks at the relay node. For the latter two, we consider both a joint and a separate design. For the joint design, we construct a factor graph to integrate channel coding with ICI, and then, propose a scheme based on belief propagation. For the separate design, two low-complexity schemes differing in channel decoding are proposed. Our simulation results, using repeat-accumulate channel codes, reveal that (1) a CFO compensation approach that amounts to positioning the relay's oscillator frequency at the middle of the received frequencies from the two end nodes is bit error rate (BER)-optimal for all the three schemes; (2) the joint design is superior at low SNR and/or high CFO levels; and (3) more importantly, with the joint design, for low-to-medium CFO levels, the BER of the channel-coded PNC is comparable with that of traditional point-to-point communications without CFO, thus manifesting itself as a promising technique in OFDM modulated TWRC with practical CFO constraints.

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Summary: In recent years, the demand on data communication is rapidly increasing, and there is a need of spectrally efficient modulation scheme for massive data transmissions. Multicarrier modulation (MCM) is widely used in wireless systems to support high data rate multimedia services such as audio, video, image, and data. Multicarrier code division multiple access (MC‐CDMA) is one of the MCM techniques which combines the best features of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). The carrier frequency offset (CFO) due to oscillator instabilities or Doppler shifts greatly deteriorates the performance of MC‐CDMA system. Hence, the subcarriers are no longer orthogonal and introduce intercarrier interference (ICI) at the receiver. The simultaneous CFO estimation and compensation in multiuser mobile environment are a challenging task which needs to be addressed for optimum performance. The blind CFO estimation such as maximum likelihood estimation (MLE) has limited estimation range which is less than half the subcarrier spacing. Multiple signal classification (MUSIC) is the spectral estimation‐based subspace method suited for simultaneous CFO estimation in the multiuser environment. MUSIC offers precise CFO estimation only for the well‐spaced CFOs and fails to discriminate the strictly spaced CFOs. Hence, a novel subspace method is proposed in this paper to improve the estimation accuracy for closely spaced CFOs with the reduced computational complexity. Simulation results show that the proposed enhanced root MUSIC estimation outperforms MLE and MUSIC in terms of estimation accuracy, bit error rate (BER), and ICI power. [ABSTRACT FROM AUTHOR]

Summary: Massive multiple‐input multiple‐output orthogonal frequency division multiplexing (MIMO‐OFDM) system is an approach to increase data rate and spectral efficiency of 5G wireless communication systems. It's easy to analyze the performance of any system with the assumption of immobile users, but if the user is moving with varying velocity, then the communication between user and base station (BS) is very difficult to maintain. Under high mobility, rapidly fading, doubly dispersive, and nonstationary environment, the conventional system fails to respond and leads to the problem of intercarrier interference (ICI). To overcome these problems, fractional Fourier transform (FrFT) has been used in place of Fourier transform (FT) to increase the correlation coefficient, to mitigate effect of ICI, and to improve bit error rate. In this paper, novel formulae for correlation coefficient, average power of ICI, and closed form bit error expression have been derived for the proposed system by considering fast‐fading model and imperfect channel state information. Finally, the comparison of both the systems conventional and proposed proved that the proposed system has improved bit error rate by 40% and intercarrier interference cancelation by 70%. [ABSTRACT FROM AUTHOR]

In this correspondence paper, an adaptive turbo equalizer for differential OFDM systems in underwater acoustic communications is proposed. This scheme first reconstructs the demodulation symbols using the soft information fed back from the channel decoder, and then eliminates the residual intercarrier interference (ICI) induced by estimated symbols using an adaptive turbo equalizer. Moreover, a pilot-based differential encoding method is presented to mitigate the impact of the feedback error, thereby improving the convergence of turbo equalization. Theoretical analysis and simulation results demonstrate that, the proposed equalizer outperforms the linear minimum mean-squared error (MMSE) estimation-based turbo equalizer for coherent systems in medium-to-high signal-to-noise ratio (SNR) region, while enjoys significantly reduced computational complexity, and its performance is more robust against the change of Doppler frequency. [ABSTRACT FROM AUTHOR]

In orthogonal frequency-division multiple access (OFDMA), carrier frequency offset (CFO) destroys the orthogonality between subcarriers due to Doppler effect of the channel and also causes inter-carrier interference (ICI) as well as multiple access interference (MAI). In this paper, CFO tracking algorithm for OFDMA system is presented to overcome the effect of ICI as well as MAI. The proposed algorithm employs normalized least-mean-square (NLMS) algorithm which tracks the residual carrier frequency offset in OFDMA system. The proposed NLMS-based tracking algorithm uses average of all residual carrier frequency offset (RCFO) for improving the mean square error (MSE) performance. The proposed NLMS-based frequency tracking along with frequency offset compensator improves the error performance by reducing the effect of ICI and MAI. Simulation results indicate that the proposed algorithm achieves better tracking performance in the presence of frequency offset. From the results, it is observed that the MSE of the proposed estimator is improved about 3.8 dB at SNR = 20 dB with the frequency offset. [ABSTRACT FROM AUTHOR]

In a frequency division complementary coded CDMA (FD-CC-CDMA) system, multiple tuners have to be used for multi-carrier modulation, which has a very high complexity and power consumption. In this paper, we propose a CP-free OFDM scheme to implement multi-carrier modulation in an FD-CC-CDMA system, which is named as CP-free OFDM-CC-CDMA system. The transmitter in the CP-free OFDM-CC-CDMA system offers a unique flexibility to adjust the amount of data processed at the same time to ensure that the OFDM block size exceeds the delay spread of a multipath channel, which attributes to effective mitigation of multipath induced inter-symbol interference (ISI). At the receiver of a CP-free OFDM-CC-CDMA system, minimum mean square error (MMSE) equalization and MMSE combining are used to mitigate multi-user interference (MUI) and inter-carrier interference (ICI). The obtained results show that a CP-free OFDM-CC-CDMA system offers a much higher transmission efficiency than FD-CC-CDMA and OFDM-DS-CDMA systems. In addition, the proposed CP-free OFDM-CC-CDMA system outperforms OFDM-DS-CDMA system in terms of bit error rate due to its inherent powerful diversity gain. [ABSTRACT FROM AUTHOR]

Wireless channels generally exhibit dispersion in both time and frequency domain, known as doubly selective or doubly dispersive channels. To combat the delay spread effect, multicarrier modulation (MCM) such as orthogonal frequency division multiplexing (OFDM) and its universal filtered variant (UF-OFDM) can be employed, leading to a simple per-subcarrier one tap equalization. The time-varying nature of the channel, in particular, the intra-multicarrier-symbol channel variation induces spectral broadening and thus inter-carrier interference (ICI). Most existing works address both effects separately, focusing on the one effect while ignoring the respective other. This paper considers both effects simultaneously for cyclic prefix (CP)-, zero padded (ZP)- and universal filtered (UF)-based OFDM with a simple one tap equalization, assuming doubly dispersive wireless channel model. For this general channel model, we show that the independent (wide sense stationary uncorrelated scatter, WSSUS) selectivity in time and frequency domain starts to intertwine in contrast to the ideal cases with single selectivity. We derive signal-to-interference-plus-noise ratio (SINR) in closed form for arbitrary system settings and channel parameters, e.g., bandwidth, delay- and Doppler-spread. With the SINR analysis, we compare the three MCM schemes under different channel scenarios. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we consider a rateless coded Orthogonal Frequency Division Multiplexing (OFDM) system under a quasistatic fading channel. During each transmission round, transmitter keeps transmitting to the receiver using Raptor code until the receiver feeds back an acknowledgement (ACK). On the other hand, frequency offset between the transmitter and receiver ruins the orthogonality of OFDM subcarriers and cause intercarrier interference (ICI). We resort to ICI self‐cancelation precoding to combat ICI, wherein the data symbol vectors are multiplied with some precoding matrix before transmission. To improve the system robustness, we jointly optimize the precoding matrix and the degree profile of Raptor code, with only statistical channel state information (CSI) being assumed at the transmitter. The optimization problem is formulated based on the extrinsic information transfer (EXIT) analysis of the decoding process at the receiver. The advantage of the proposed design is that the instant CSI is not required at the transmitter, which reduces the system overhead. Simulation results verify that the proposed scheme with the optimized precoding matrix and degree profile can effectively combat ICI and achieve good performance both in bit error ratio (BER) and average transmission rate. [ABSTRACT FROM AUTHOR]

Summary: In the context of the on‐going evolution of satellite communications (SatCom) systems to their next generation, and in the direction of their integration with fifth generation (5G) terrestrial networks, it is of interest to study in depth the applicability in realistic SatCom of waveforms that have shown promise to meet the 5G requirements. This paper presents a comparative study, based on total degradation (TD) over a range of output back‐off (OBO) values, on out‐of‐band emission and spectral efficiency, of frequency division multiple access (FDMA) schemes employing offset quadrature amplitude modulation‐based filter bank multi‐carrier (FBMC /OQAM), classical orthogonal FDMA (OFDMA), and their single‐carrier counterparts to illustrate the potential gains from the integration of the FBMC waveforms in the satellite context and standards. The air interface simulated follows the digital video broadcasting (DVB) family of standards for the satellite uplink, considering both time and frequency synchronization impairments and two typical input constellations. Our results confirm the superiority of the single‐carrier (SC) schemes in such a nonlinear environment. The SC‐FBMC waveform is shown to be the most practical candidate since it is shown to attain a TD performance similar to that of SC‐OFDM at absolutely no cost in spectral efficiency. [ABSTRACT FROM AUTHOR]

Orthogonal Frequency Division Multiplexing (OFDM) signal would be damaged significantly by intercarrier interference (ICI) in higher time-varying fading channels. The ICI leads to fatal degradation of bit error rate (BER) performance due to the loss of orthogonality among subcarriers. To solve this problem, this paper proposes a high accuracy time-domain channel impulse response (CIR) estimation method and low-complexity based timedomain equalization (TDE) method for solving the simultaneous equations instead of using an inverse matrix calculation which can achieve better BER performance and lower computation complexity even in higher time-varying fading channels. The salient features of proposed method are to employ a time-domain training sequence (TS) in the estimation of channel impulse response (CIR) instead of using pilot subcarriers in the frequency domain and to employ the time domain equalization (TDE) method with maximum likelihood (ML) estimation instead of using a conventional frequency domain equalization (FDE) method. This paper also proposes a low-complexity iterative method for solving the simultaneous equations instead of using an inverse matrix calculation, which remains the computation complexity up to 7.8% of inverse matrix calculation with the same BER performance but achieves the BER performance when compared with the conventional method. This paper presents various simulation results in higher time-varying fading channels (vehicle speed ≈ 381 km/hrs) to demonstrate the effectiveness of the proposed method as compared with conventional FDE and TDE methods. [ABSTRACT FROM AUTHOR]

In this article, three novel systems for wireless sensor networks based on Alamouti decoding were investigated and then compared, which are Alamouti space–time block coding multiple-input single-output/multiple-input multiple-output multicarrier modulation (MCM) system, extended orthogonal space–time block coding multiple-input single-output MCM system, and multiple-input multiple-output system. Moreover, the proposed work is applied over multiple-input multiple-output systems rather than the conventional single-antenna orthogonal chirp division multiplexing systems, based on the discrete fractional cosine transform orthogonal chirp division multiplexing system to mitigate the effect of frequency-selective and time-varying channels, using low-complexity equalizers, specifically by ignoring the intercarrier interference coming from faraway subcarriers and using the LSMR iteration algorithm to decrease the equalization complexity, mainly with long orthogonal chirp division multiplexing symbols, such as the TV symbols. The block diagrams for the proposed systems are provided to simplify the theoretical analysis by making it easier to follow. Simulation results confirm that the proposed multiple-input multiple-output and multiple-input single-output orthogonal chirp division multiplexing systems outperform the conventional multiple-input multiple-output and multiple-input single-output orthogonal frequency division multiplexing systems. Finally, the results show that orthogonal chirp division multiplexing exhibited a better channel energy behavior than classical orthogonal frequency division multiplexing, thus improving the system performance and allowing the system to decrease the equalization complexity. [ABSTRACT FROM AUTHOR]

We present the latest developments in the physical layer evolution for the transmission of Multimedia Broadcast Multicast Service (MBMS) over fifth generation (5G) cellular networks. We first provide an overview of how the MBMS physical layer has evolved during the initial releases of the Third Generation Partnership Project (3GPP) specifications and provide motivations and insights for key developments that have helped mature MBMS into a competitive broadcasting solution. We provide an overview of dedicated MBMS carriers for Multimedia Broadcast multicast service Single Frequency Network (MBSFN) transmission as well as Orthogonal Frequency Division Multiplexing (OFDM) numerologies with longer cyclic prefixes to support MBSFN transmission over large geographical areas with large distances between cooperating cell sites. Next, we describe the most recent enhancements to the MBMS physical layer, addressing advanced use cases in the recently completed release of the 3GPP specifications (Release 16). First, we describe the physical layer design for enabling MBSFN-based MBMS services for rooftop receivers with inter-site distances between cooperating cell sites as large as 125 km. In this realm, we demonstrate the need for an OFDM numerology with a 300-microsecond cyclic prefix to communicate effectively over channels with very large delay spreads. Next, we explain how support for high mobility up to 250 kmph was added to the standards by using an OFDM numerology that gracefully trades off inter-symbol interference due to large delay spreads and inter-carrier interference due to large doppler spreads to achieve better performance than existing numerologies at high speeds. Finally, we describe the enhancements that were made to the Cell Acquisition Subframe (CAS)—specifically, the introduction of larger aggregation levels for the Physical Downlink Control Channel (PDCCH) and the support of Physical Broadcast Channel (PBCH) repetitions—that significantly increase the coverage for the control and system information associated with MBMS that are carried by these subframes. [ABSTRACT FROM AUTHOR]

In radio communications, using wavelet signal analysis to recover the symbol rate timing clock of orthogonal frequency-division multiplexing (OFDM) is a new approach that can tolerate signal distortion from intersymbol interference (ISI) and intercarrier interference of encoding digital data on multiple carrier frequencies. Typically, the reception synchronization with wavelet signal analysis in OFDM can improve the performance over the fourier transform-based OFDM. However, a synchronization procedure that is stable against distortion and noise is essential to diminish the symbol synchronization establishment and operation sampling period. In this paper, we propose an OFDM synchronization system and analyze the impact of the wavelet denoise procedure on the OFDM system, which extracts the symbol rate of the OFDM frame. The evaluation results show that the proposed system can optimize the frequency window size to enable an efficient timing and frequency offset estimation with high and stable performance in terms of bit error rate (BER) and Frame Error Rate (FER) especially when the value of EbN0 (a normalized signal-to-noise ratio SNR measure) is greater than 8 dB, thanks to the wavelet transform. [ABSTRACT FROM AUTHOR]

The growing interest towards wireless communication advancement with smart devices has provided the desired throughput of wireless communication mechanisms. But, attaining high-speed data packets amenities is the biggest issue in different multimedia applications. Recently, OFDM has come up with the useful features for wireless communication however it faces interference issues at carrier level (intercarrier interferences). To resolve these interference issues in OFDM, various existing mechanisms were utilized cyclic prefix, but it leads to redundancy in transmitted data. Also, the transmission of this redundant data can take some more power and bandwidth. All these limitations factors can be removed from a parallel cancellation mechanism. The integration of parallel cancellation and Convolution Viterbi encoding and decoding in MIMOOFDMA will be an effective solution to have high data rate which also associations with the benefits of both the architectures of MIMO and OFDMA modulation approaches. This paper deals with this integrated mechanism for efficient resource allocation and power consumption. For performance analysis, MIMO-OFDMA system is analyzed with three different approaches likeMIMO-OFDM system without parallel cancellation (MIMO-OFDMA-WPC), MIMO-OFDMA System with parallel cancellation (MIMO-OFDMA-PC) and proposed IMO-OFDMA system with parallel cancellation and Convolution Viterbi encoding/decoding (pMIMO-OFDMAPC &CVed) for 4x4 transmitter and receiver. Through performance analysis, it is found that the proposed system achieved better resource allocation (bandwidth) with high data rate by minimized BER rate and achieved least power consumption with least BER. [ABSTRACT FROM AUTHOR]