Next generation networks will support diverse use cases that require higher flexibility in the resource allocation. To this end, we propose a new waveform referred to as Lagrange Vandermonde division multiplexing (LVDM) that generalizes the zero padding orthogonal frequency division multiplexing (ZP-OFDM) while guaranteeing the perfect recovery of the transmitted signal. The LVDM transceiver design relies on the signature roots that have been judiciously selected to 1) provide a flexible resource allocation and 2) keep the complexity low where one-tap equalization is adopted. Carrying out the simulations in both frequency selective and 3GPP channels, our proposed waveform outperforms the ZP-OFDM where performance results are shown in terms of bit error ratio (BER). The LVDM achieves a signal-to-noise ratio gain of 5 dB over the ZP-OFDM when applying the optimized power allocation over subcarriers.

Lagrange Vandermonde division multiplexing (LVDM), that generalizes yet outperforms the zero padding orthogonal frequency division multiplexing (ZP-OFDM) while guaranteeing the perfect recovery of the transmitted signal, has been proposed recently as a new waveform. Therein, the transceiver design relies on the signature roots that have been optimized to keep the implementation complexity low where a simple one-tap equalization has been performed in frequency selective channels. While the beyond 5G solutions ought to be designed to overcome the intercarrier interference in high mobility, a new advanced receiver for LVDM that deals with doubly selective channels is needed. We propose two new schemes using time-frequency domain equalization where performance and implementation complexity have been discussed for each. Simulation results show that both schemes drastically boost the performance while keeping the complexity low compared to the state of the art solutions.

Forthcoming wireless systems will have to cope with heterogeneous and dense traffic. High demands in terms of bandwidth use efficiency and increased flexibility are therefore required for the related air-interface technology. In this context, Filter-Bank MultiCarrier with Offset QAM (FBMC/OQAM) waveform has been recognized as an enabling technology providing strong assets with a well-confined spectrum and enhanced spectral efficiency with respect to cyclic prefix orthogonal frequency-division multiplexing (OFDM). Nonetheless, FBMC-OQAM presents a few challenges to overcome: the intrinsic interference must be taken into consideration in the channel estimation processes and multiple antenna schemes’ design. Those challenges are induced by the reduction of the orthogonality property to the real field. In this paper, OFDM precoding/decoding is proposed as an alternative to the OQAM signaling for filter-bank-based waveforms. The OFDM precoding makes the waveforms near-complex orthogonal, which enables a straightforward adaptation to channel estimation techniques and MIMO scheme design. Two waveforms based on this precoding, namely fast Fourier transform FBMC and block-filtered OFDM, have been proposed. A common framework is proposed to study the two waveforms. This paper also investigates changing the time structure of the transmitted signal by introducing the rate factor parameter. It is shown that intrinsic interference can be greatly reduced at the price of a slight side-lobe increase.

This paper studies the joint multiplexing, Resource-Block and power allocation problem in underlay Device-to-Device (D2D) communications. The interfering signals are assumed fully asynchronous at the device receivers and at the Base Station. Inter-Channel Interference (ICI) then generates major impairment on the expected rate gain if Orthogonal Frequency Division Multiplex (OFDM) multi-carrier modulation is used, contrary to new multi-carrier modulations such as Filter Bank Multi-Carrier (FBMC) or Fast Fourier Transform (FFT)-FBMC. The proposed centralized algorithm provides a lower bound to the maximum sum rate over D2D pairs, taking into account ICI. It increases the sum data rate compared to a Frequency Division Multiple Access (FDMA) technique and compared to two other algorithms allowing multiplexing and applying power control.

This paper studies two different multiplexing problems for Device to Device (D2D) asynchronous communications with different multi-carrier modulations. Several D2D pairs may be multiplexed on the same Resource Blocks (RB) if they are jointly able to reach a high Signal to Interference plus Noise Ratio (SINR). In asynchronous communications, inter-channel interference (ICI) is present on top of co-channel interference, and the multiplexing problem can consequently not be split per RB since RB are no longer orthogonal. In this paper, we derive the system model that takes into account ICI and then study the maximum multiplexing problem. Two heuristics based on the Frobenius and the infinity norms that lead to lower bounds on the multiplexing gain are proposed. Then, the maximum sum SINR problem is studied with the infinity norm, showing that higher rates are achieved with Filter Bank Multi-Carrier (FBMC) modulation than with Orthogonal Frequency Division Multiplex (OFDM).

We consider the downlink resource allocation for a multi-carrier-based asynchronous cognitive radio network with statistical knowledge of the channel state information of both primary and secondary systems available at the secondary base station. The problem of secondary utility maximization is investigated under primary and secondary user outage constraints and total power constraint. Analyses are provided for cases where both primary and secondary systems are utilizing either orthogonal frequency-division multiplexing or filter-bank based multi-carrier modulations. The highly complex yet challenging and non-convex joint power-subcarrier allocation problem is tackled by leveraging the principle of alternating optimization techniques. A per-carrier outage-based solution is provided for the subcarrier allocation stage. In the second stage, we introduce an upper bound to the outage constraints to ensure tractability. We propose an efficient convex approximation method to obtain near-optimal solutions of the centralized power control problem. Furthermore, to reduce computational complexity, a distributed implementation based on dual decomposition method is designed. Extensive simulation results are further provided to corroborate the validity of the theoretical findings and demonstrate the effectiveness of the proposed algorithms.

In this paper, we propose a scheme that preserves the advantages of Windowed Cyclic Prefix FBMC/Circular Offset Quadrature Amplitude Modulation (WCP-COQAM) while guaranteeing the complex orthogonality. Indeed, WCP-COQAM is based on block processing and uses circular filtering in order to remove time overheads. However, like FBMC/OQAM scheme, WCP-COQAM suffers from the presence of intrinsic interference that prevents the combination with some Multiple Input Multiple Output (MIMO) techniques such as Alamouti Coding. This intrinsic interference results from the non-complex orthogonal property of WCP-COQAM and Filter Bank MultiCarrier (FBMC). In this work, we show that circular filtering makes the transmultiplexer impulse response circulant. Our proposed scheme, called COW-CFMC, exploits this circularity to restore the complex orthogonality by precoding the data symbols in each subcarrier. Thus, we show by simulation that our proposed scheme can enable Alamouti coding in a straightforward manner.

Recently, fast Fourier transform filter-bank multicarrier (FFT-FBMC) modulation was proposed to enable diverse multiple-input multiple-output (MIMO) techniques with FBMC by eliminating the intrinsic interference. A per-subcarrier (PSC) channel equalizer was derived under the assumption of low frequency selectivity. However, this equalization scheme cannot be directly applied to highly frequency selective channels without performance degradation. In this letter, we analyze the received signal after demodulation without any assumption on the channel selectivity. We develop a general closed-form expression for the equivalent channel seen at the demodulator. Furthermore, we design the associate channel equalizer. Simulation results demonstrate that the developed equalizer performs as equally with the previous PSC equalizer in the case of low frequency selectivity, and outperforms the PSC equalizer in highly frequency selective channels.

This paper studies the weighted sum rate maximization problem for device-to-device (D2D) underlay communications. Since each D2D transmitter is synchronized with its receiver, all D2D receivers get asynchronous interference from the other transmitters, and so does the Base Station (BS). This is modelled by a uniformly-distributed timing offset which generates inter-channel interferences in multi-carrier transmissions. Filter Bank based Multi-Carrier (FBMC) is then far more efficient than Orthogonal Frequency Division Multiplex (OFDM) to limit the inter-channel interference spread. In this context, D2D pairs are clustered through graph coloring in order to avoid high interference situations. Then we derive the weighted sum rate maximization algorithm with inter-channel interference and with an interference constraint at the BS. An iterative implementation of this algorithm converges to the global optimal solution, when the high Signal-to-Interference-plus-Noise Ratio (SINR) condition holds. Simulation results show that D2D users can be efficiently multiplexed, achieving high data rates while fulfilling the BS interference constraint.

In this paper we study the effect of the FBMC intrinsic interference on the error rate performance in the presence of a phase error. We focus our study on the symbol error rate (SER) performance in additive white Gaussian noise (AWGN) channel, and we derive the SER performance expressions for any 2m-PAM (pulse amplitude modulation) data mapping and a phase error φ. The SER performance also depends on the probability distribution of the interference term. Since the intrinsic interference is generated from the transmitted data symbols, the probability distribution of the interference is related to the data symbol mapping. We suggest to approximate the interference probability distribution to Gaussian one for the high order constellations, and simplify the analytical expression of the SER performance. The analytical expressions developed in the paper are checked and confirmed by numerical simulations. We will show in the paper that the performance curves obtained by simulation and theoretical analysis are the same for high order constellation where the approximation of the interference to the Gaussian one is suitable.

Filter-bank multicarrier (FBMC) transmission system was proposed as an alternative approach to orthogonal frequency division multiplexing (OFDM) system since it has a higher spectral efficiency. One of the characteristics of FBMC is that the demodulated transmitted symbols are accompanied by interference terms caused by the neighboring transmitted data in time-frequency domain. The presence of this interference is an issue for some multiple-input multiple-output (MIMO) schemes and until today their combination with FBMC remains an open problem. We can cite, among these techniques, the Alamouti scheme and the maximum likelihood detection (MLD) with spatial multiplexing (SM). In this paper, we shall propose a new FBMC scheme and transmission strategy in order to avoid this interference term. This proposed scheme (called FFT-FBMC) transforms the FBMC system into an equivalent system formulated as OFDM regardless of some residual interference. Thus, any OFDM transmission technique can be performed straightforwardly to the proposed FBMC scheme with a corresponding complexity growth compared to the classical FBMC. First, we will develop the FFT-FBMC in the case of single-input single-output (SISO) configuration. Then, we extend its application to SM-MIMO configuration with MLD and Alamouti coding scheme. Simulation results show that FFT-FBMC can almost reach the OFDM performance, but it remains slightly outperformed by OFDM.

Multicarrier modulation and especially CP-OFDM is widely used nowadays in several radio communications. However, Filter Bank Multicarrier (FBMC) is a potential alternative to CP-OFDM since it does not require cyclic prefix and thus it has a higher spectral efficiency. One of the characteristics of FBMC is that it induces intrinsic interference among the transmitted data. The presence of this interference complicates the application of the MLD (Maximum Likelihood Detection) in the MIMO Spatial Data Multiplexing configuration which is known to improve the capacity. In this paper, we are interested in the encoded data case and we propose two receiver schemes. Both schemes are based on interference estimation and cancellation. The first one uses MMSE equalization in order to get an estimation of the intrinsic interference. The second one improves the interference estimation by exploiting the decided symbols around the considered time-frequency position. The performance of both approaches are assessed by simulation, and we show that the second approach exhibits either the same performance or better than OFDM

Multi-carrier modulation and especially CP-OFDM is widely used nowadays in several radio communications. However, FBMC is a potential alternative to CP-OFDM since it does not require cyclic prefix, and thus, it has a higher spectral efficiency. One of the characteristics of FBMC is that the received data are accompanied by a two dimensional inter-symbol interference term (2D ISI), which complicates MIMO techniques when combined with optimum detection. In this paper we consider the association of FBMC with the multiple-input multiple-output (MIMO) technique focusing on the spatial data multiplexing (SDM), and we investigate the use of Maximum Likelihood (ML) detection. We propose modified FBMC schemes based on inserting null data among QAM symbols to reduce, in this way, the overlapping of the symbols.