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The Last decade saw significant growth in the digital terrestrial television (DTT) subscribers. The High peak-to-average power ratio (PAPR) of the transmitted signal is implied by the large fluctuations in its amplitude, which is a serious issue in the contemporary and next generation DTT broadcasting systems. These large fluctuations prevent feeding the high power amplifier (HPA) at an operating point near its non-linear (NL) saturation region, thereby lowering its power efficiency. For a better future, energy-efficient green communications is the need of hour. This paper focuses on digital predistortion (DPD), which is among the widely used techniques for HPA linearization in order to minimize the NL effects. DPD technique requires a feedback signal. This paper proposes a novel adding signal-based digital predistortion, where the output of the HPA is gradually linearized by adding a signal at the input in an iterative manner. By Taylor series approximation, the DPD problem can be posed as a convex one. We prove that a tighter upper bound exists for the convergence factor and instead of directly solving the convex problem, we pick a convergence factor value within its bounds that offers a good trade-off between convergence speed and residual error value. The simulation results show that the proposed technique can quickly linearize the HPA with good convergence.

The Filter Bank Multi-Carrier with Offset Quadrature Amplitude Modulation has already gained popularity as one of the alternatives to OFDM for next generation beyond 5G broadband wireless access systems. Like any other multicarrier modulation technique, FBMC is prone to non-linear (NL) effects of high power amplifier (HPA). Then, it is essential to mitigate NL effects to achieve energy efficient radio communications. This paper focuses on HPA linearization, and proposes a novel adding signal based digital predistortion with a quasi-optimal convergence rate. The simulation results show that proposed technique can quickly linearize the HPA.

International audience; Tone Reservation (TR) is one of the common algorithms proposed for peak-to-average power ratio (PAPR) reduction in next generation American digital video broadcasting (ATSC 3.0) transmitters. Recently, a quasi-optimal TR technique with a novel kernel definition named as grouped individual carrier multiple peaks (GICMP) scheme has been proposed. In GICMP, firstly, the reserved tones are partitioned into G groups, which also equals to the number of iterations. Then, a comb-like kernel is constructed with each group and it is adjusted to cancel a given set of peaks of data signal at each iteration. This scheme not only offers good performance/complexity trade-off but also compatible with ATSC 3.0 standard. Based on same kernel definition, we have proposed a new method, named as grouped carrier peak windowing (GCPW), which requires less hardware resources, compared to GICMP. Instead of choosing a set of peaks, this new method introduces a peak window to consider a given number of signal samples that exceed the predetermined threshold. This new method aims of reducing first peaks falling within the window, while leaving out higher peaks that may occur later. The simulation results show that the proposed low-complexity GCPW has less hardware memory requirements and with a good choice of threshold, window size and groups, offers quasi-optimal PAPR reduction performance same as that of GICMP. © 2018 IEEE.

International audience; A common issue in any multicarrier communication system such as the American digital video broadcasting (ATSC 3.0) standard is the high peaks of the transmitted signal. This disadvantage constrains the high power amplifiers to be deployed in their linear region which lowers their power efficiency. To overcome this issue, various techniques aiming at reducing the signal fluctuations have been investigated. Recently, Tone Reservation (TR) based algorithms have been studied and proposed for the second generation of Digital Video Broadcasting (DVB-T2) and ATSC 3.0 standards. The algorithm is essentially based on an iterative gradient approach to cancel one peak of the time-domain signal at each iteration. In this paper, we propose a novel TR-based algorithm implementable and compatible with the ATSC 3.0 standard and named as Grouped Carrier Peak Windowing (GCPW). This algorithm is based on a new kernel definition targeting the cancellation of multiple signal peaks at a time which highly reduces the total number of iterations, therefore reducing the system global latency and being more suited for implementation in today's ATSC 3.0 transmitters. Taking into account hardware resources requirements, we propose a new method to select the highest signal peaks to be considered in the PAPR reduction process. Hence, the system latency, complexity and memory resources are reduced and better performance than the ATSC 3.0 gradient-based algorithm can be offered. The implementation of the GCPW algorithm in fixed-point architectures is also studied and optimized in this paper. We demonstrate through simulation results that the proposed algorithm offers very good performance/latency/complexity/memory trade-off in both floating and fixed point implementations.

International audience; In this paper, the problem of peak-to-average power ratio (PAPR) reduction of orthogonal frequency division multiplexing (OFDM) signals is investigated in the context of second generation of digital video broadcasting for terrestrial transmission (DVB-T2) and the American digital video broadcasting standard ATSC3.0. As a multicarrier modulation technique is characterized by a high PAPR of the transmitted signal and OFDM is prone to non-linear (NL) effects of power amplifiers. DVB-T2 and ATSC3.0 have adopted a gradient-based tone reservation (TR) PAPR reduction technique which is based on an iterative process where, at each iteration, a predefined kernel is used to reduce one peak in time domain. Recently, a new TR PAPR reduction technique termed individual carrier allocation for multiple peaks (ICMP), based on a novel kernel definition has been proposed. However, it suffers from latency issues in ATSC3.0 and higher modes of DVB-T2. So, we propose another novel TR technique, grouped ICMP (GICMP). The simulation results show that GICMP offers better performance than the gradient-based DVB-T2 algorithm. Furthermore, it not only yields the same performance as ICMP but also has less latency. © 2017 IEEE.

Filter-bank multi-carrier (FBMC) modulations, and more specifically FBMC-offset quadrature amplitude modulation (OQAM), are seen as an interesting alternative to orthogonal frequency division multiplexing (OFDM) for the 5th generation radio access technology. In this paper, we investigate the problem of peak-to-average power ratio (PAPR) reduction for FBMC-OQAM signals. Recently, it has been shown that FBMC-OQAM with trellis-based selected mapping (TSLM) scheme not only is superior to any scheme based on symbol-by-symbol approach but also outperforms that of the OFDM with classical SLM scheme. This paper is an extension of that work, where we analyze the TSLM in terms of computational complexity, required hardware memory, and latency issues. We have proposed an improvement to the TSLM, which requires very less hardware memory, compared to the originally proposed TSLM, and also have low latency. Additionally, the impact of the time duration of partial PAPR on the performance of TSLM is studied, and its lower bound has been identified by proposing a suitable time duration. Also, a thorough and fair comparison of performance has been done with an existing trellis-based scheme proposed in literature. The simulation results show that the proposed low-latency TSLM yields better PAPR reduction performance with relatively less hardware memory requirements.

The Filter Bank Multi-Carrier (FBMC) with Offset Quadrature Amplitude Modulation (OQAM) has some appealing properties that make it to gain currency as one of the alternatives to OFDM for next generation broadband wireless access systems. Albeit, being a multicarrier modulation (MCM) technique, it is prone to non-linear (NL) effects of power amplifier (PA). As energy efficiency radio communications is the need of hour, it is essential to mitigate NL effects. This paper focuses on PA linearization, especially digital predistortion (DPD). It is imperative that, any new DPD technique suggested for FBMC-OQAM, need to take into account its overlapping signal structure. A novel DPD technique, termed as overlapped recursive error correction has been proposed in this paper for linearization of non-linearly amplified FBMC-OQAM signals.

The coexistence of broadband systems with currently deployed Professional Mobile Radio (PMR) communication systems like Public Protection and Disaster Relief (PPDR) has gained much deserved attention. In the recent literature, it has been suggested that LTE-like FBMC-OQAM system working on linear devices can coexist in PMR band, while conventional OFDM-based LTE system fails. When we take into account, the RF impairments in radio communication systems; it is inevitable to consider the non-linear nature of High Power Amplifiers (HPAs), as they add severe hindrance in this aspect. In this paper, we address this issue and show that LTE-like FBMC-OQAM system working on non-linear devices can still co-exist with PMR/PPDR systems, when suitable peak-to-average power ratio (PAPR) is applied.