35 research outputs found

    Analysis and Implementation of PAPR reduction algorithms for C-OFDM signals

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    Nowadays multicarrier modulation has become a key technology for communication systems; for example C-OFDM schemes are used in wireless LAN (802.11a/g/n), terrestrial digital television (DVB-T) and audio broadcaster (DAB) in Europe, and discrete multitone (DMT) in x.DSL systems. The principal difficulty with OFDM is the occurrence of the coherent alignment of the time domain parallel signals at the transmitted side which forces system designer to introduce either additional hard computationally device or a suitable power back-off at the high power amplifier in order to cope with the large magnitude signal fluctuation. This leads to a significant increment in computational cost in the former case whereas in a worse allowable power utilization in the latter case with respect to the original system. However since both allowable power and computational cost are subject to a design as well as regulatory limit others solution must be accomplished. Peak reduction techniques reduce maximum-to-mean amplitude fluctuations nominating as a feasible solution. Peak-to-average power ratio is the key metric to measure this amplitude fluctuations at transmitter and to give a clear figure of merit for comparison among different techniques

    DVB-T2: The Second Generation of Terrestrial Digital Video Broadcasting System

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    This paper provides a review of the second generation of terrestrial digital video broadcasting standard (DVB-T2). DVB-T2 is the evolution of DVB-T and, together with DVB-S2 and DVB-C2, inaugurated a new transition from the firstgeneration digital broadcasting systems, similar to the transition from analog-to-digital systems. In this paper, the most relevant features of DVB-T2 are explained in detail, along with their benefits and trade-offs. This paper also presents a comprehensive review of the laboratory and field trial results available so far. Especial emphasis is placed in the results of the measurements carried out to test the mobile reception and the novel technologies as multiple input single output and time frequency slicing.This work was supported in part by the University of the Basque Country UPV/EHU under Grant UFI 11/30, in part by the Basque Government under Grants IT-683-13 and SAIOTEK, and in part by the Spanish Ministry of Economy and Competitiveness Project HEDYT-GBB under Grant TEC2012-33302.Eizmendi, I.; Velez, M.; G贸mez Barquero, D.; Morgade, J.; Baena Lecuyer, V.; Slimani, M.; Zoellner, J. (2014). DVB-T2: The Second Generation of Terrestrial Digital Video Broadcasting System. IEEE Transactions on Broadcasting. 60(2):258-271. https://doi.org/10.1109/TBC.2014.2312811S25827160

    New methods of partial transmit sequence for reducing the high peak-to-average-power ratio with low complexity in the ofdm and f-ofdm systems

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    The orthogonal frequency division multiplexing system (OFDM) is one of the most important components for the multicarrier waveform design in the wireless communication standards. Consequently, the OFDM system has been adopted by many high-speed wireless standards. However, the high peak-to-average- power ratio (PAPR) is the main obstacle of the OFDM system in the real applications because of the non-linearity nature in the transmitter. Partial transmit sequence (PTS) is one of the effective PAPR reduction techniques that has been employed for reducing the PAPR value 3 dB; however, the high computational complexity is the main drawback of this technique. This thesis proposes novel methods and algorithms for reducing the high PAPR value with low computational complexity depending on the PTS technique. First, three novel subblocks partitioning schemes, Sine Shape partitioning scheme (SS-PTS), Subsets partitioning scheme (Sb-PTS), and Hybrid partitioning scheme (H-PTS) have been introduced for improving the PAPR reduction performance with low computational complexity in the frequency-domain of the PTS structure. Secondly, two novel algorithms, Grouping Complex iterations algorithm (G-C-PTS), and Gray Code Phase Factor algorithm (Gray-PF-PTS) have been developed to reduce the computational complexity for finding the optimum phase rotation factors in the time domain part of the PTS structure. Third, a new hybrid method that combines the Selective mapping and Cyclically Shifts Sequences (SLM-CSS-PTS) techniques in parallel has been proposed for improving the PAPR reduction performance and the computational complexity level. Based on the proposed methods, an improved PTS method that merges the best subblock partitioning scheme in the frequency domain and the best low-complexity algorithm in the time domain has been introduced to enhance the PAPR reduction performance better than the conventional PTS method with extremely low computational complexity level. The efficiency of the proposed methods is verified by comparing the predicted results with the existing modified PTS methods in the literature using Matlab software simulation and numerical calculation. The results that obtained using the proposed methods achieve a superior gain in the PAPR reduction performance compared with the conventional PTS technique. In addition, the number of complex addition and multiplication operations has been reduced compared with the conventional PTS method by about 54%, and 32% for the frequency domain schemes, 51% and 65% for the time domain algorithms, 18% and 42% for the combining method. Moreover, the improved PTS method which combines the best scheme in the frequency domain and the best algorithm in the time domain outperforms the conventional PTS method in terms of the PAPR reduction performance and the computational complexity level, where the number of complex addition and multiplication operation has been reduced by about 51% and 63%, respectively. Finally, the proposed methods and algorithms have been applied to the OFDM and Filtered-OFDM (F-OFDM) systems through Matlab software simulation, where F-OFDM refers to the waveform design candidate in the next generation technology (5G)

    Single-Frequency Network Terrestrial Broadcasting with 5GNR Numerology

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    L'abstract 猫 presente nell'allegato / the abstract is in the attachmen

    High mobility in OFDM based wireless communication systems

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    Orthogonal Frequency Division Multiplexing (OFDM) has been adopted as the transmission scheme in most of the wireless systems we use on a daily basis. It brings with it several inherent advantages that make it an ideal waveform candidate in the physical layer. However, OFDM based wireless systems are severely affected in High Mobility scenarios. In this thesis, we investigate the effects of mobility on OFDM based wireless systems and develop novel techniques to estimate the channel and compensate its effects at the receiver. Compressed Sensing (CS) based channel estimation techniques like the Rake Matching Pursuit (RMP) and the Gradient Rake Matching Pursuit (GRMP) are developed to estimate the channel in a precise, robust and computationally efficient manner. In addition to this, a Cognitive Framework that can detect the mobility in the channel and configure an optimal estimation scheme is also developed and tested. The Cognitive Framework ensures a computationally optimal channel estimation scheme in all channel conditions. We also demonstrate that the proposed schemes can be adapted to other wireless standards easily. Accordingly, evaluation is done for three current broadcast, broadband and cellular standards. The results show the clear benefit of the proposed schemes in enabling high mobility in OFDM based wireless communication systems.Orthogonal Frequency Division Multiplexing (OFDM) wurde als 脺bertragungsschema in die meisten drahtlosen Systemen, die wir t盲glich verwenden, 眉bernommen. Es bringt mehrere inh盲rente Vorteile mit sich, die es zu einem idealen Waveform-Kandidaten in der Bit眉bertragungsschicht (Physical Layer) machen. Allerdings sind OFDM-basierte drahtlose Systeme in Szenarien mit hoher Mobilit盲t stark beeintr盲chtigt. In dieser Arbeit untersuchen wir die Auswirkungen der Mobilit盲t auf OFDM-basierte drahtlose Systeme und entwickeln neuartige Techniken, um das Verhalten des Kanals abzusch盲tzen und seine Auswirkungen am Empf盲nger zu kompensieren. Auf Compressed Sensing (CS) basierende Kanalsch盲tzverfahren wie das Rake Matching Pursuit (RMP) und das Gradient Rake Matching Pursuit (GRMP) werden entwickelt, um den Kanal pr盲zise, robust und rechnerisch effizient abzusch盲tzen. Dar眉ber hinaus wird ein Cognitive Framework entwickelt und getestet, das die Mobilit盲t im Kanal erkennt und ein optimales Sch盲tzungsschema konfiguriert. Das Cognitive Framework gew盲hrleistet ein rechnerisch optimales Kanalsch盲tzungsschema f眉r alle m枚glichen Kanalbedingungen. Wir zeigen au脽erdem, dass die vorgeschlagenen Schemata auch leicht an andere Funkstandards angepasst werden k枚nnen. Dementsprechend wird eine Evaluierung f眉r drei aktuelle Rundfunk-, Breitband- und Mobilfunkstandards durchgef眉hrt. Die Ergebnisse zeigen den klaren Vorteil der vorgeschlagenen Schemata bei der Erm枚glichung hoher Mobilit盲t in OFDM-basierten drahtlosen Kommunikationssystemen

    On Transmission System Design for Wireless Broadcasting

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    This thesis considers aspects related to the design and standardisation of transmission systems for wireless broadcasting, comprising terrestrial and mobile reception. The purpose is to identify which factors influence the technical decisions and what issues could be better considered in the design process in order to assess different use cases, service scenarios and end-user quality. Further, the necessity of cross-layer optimisation for efficient data transmission is emphasised and means to take this into consideration are suggested. The work is mainly related terrestrial and mobile digital video broadcasting systems but many of the findings can be generalised also to other transmission systems and design processes. The work has led to three main conclusions. First, it is discovered that there are no sufficiently accurate error criteria for measuring the subjective perceived audiovisual quality that could be utilised in transmission system design. Means for designing new error criteria for mobile TV (television) services are suggested and similar work related to other services is recommended. Second, it is suggested that in addition to commercial requirements there should be technical requirements setting the frame work for the design process of a new transmission system. The technical requirements should include the assessed reception conditions, technical quality of service and service functionalities. Reception conditions comprise radio channel models, receiver types and antenna types. Technical quality of service consists of bandwidth, timeliness and reliability. Of these, the thesis focuses on radio channel models and errorcriteria (reliability) as two of the most important design challenges and provides means to optimise transmission parameters based on these. Third, the thesis argues that the most favourable development for wireless broadcasting would be a single system suitable for all scenarios of wireless broadcasting. It is claimed that there are no major technical obstacles to achieve this and that the recently published second generation digital terrestrial television broadcasting system provides a good basis. The challenges and opportunities of a universal wireless broadcasting system are discussed mainly from technical but briefly also from commercial and regulatory aspectSiirretty Doriast

    Reception performance studies for the evaluation and improvement of the new generation terrestrial television systems

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    270 p.La industria de la TV ha experimentado grandes cambios en las 煤ltimas d茅cadas. Las expectativas cada vez mayores de los espectadores y la reducci贸n del espectro disponible para los servicios de TV han provocado la necesidad de sistemas m谩s robustos de Televisi贸n Digital Terrestre (TDT).El primer intento de cumplir estos requisitos es el est谩ndar europeo DVB-T2 (2009). La publicaci贸n de un nuevo est谩ndar significa el inicio de un proceso de evaluaci贸n del rendimiento del mismo mediante, por ejemplo, estudios de cobertura u obtenci贸n de valores de umbral de relaci贸n se帽al / ruido (SNR). Al inicio de esta tesis, este proceso estaba casi terminado para recepci贸n fija y m贸vil. Sin embargo, la recepci贸n en interiores no se hab铆a estudiado en detalle. Por esta raz贸n, esta tesis completa la evaluaci贸n de DVB-T2 en interiores y define una nueva metodolog铆a de evaluaci贸n optimizada para este escenario.A pesar de que DVB-T2 emplea tecnolog铆as muy avanzadas, el sistema se defini贸 hace casi diez a帽os y desde entonces han aparecido nuevas t茅cnicas avanzadas, como por ejemplo nuevos c贸digos de correcci贸n de errores o la nueva t茅cnica de multiplexaci贸n por divisi贸n en capas (LDM). Estas nuevas t茅cnicas tampoco han sido evaluadas en entornos de interior, por lo que esta tesis incluye el an谩lisis de las mismas evaluando su idoneidad para mejorar el rendimiento de DVB-T2. Adem谩s, se ha comprobado que los algoritmos tradicionales de los receptores TDT no est谩n optimizados para los nuevos escenarios en los que se consideran las se帽ales multicapa y recepci贸n m贸vil. Por esta raz贸n, se han propuesto nuevos algoritmos para mejorar la recepci贸n en este tipo de situaciones.El 煤ltimo intento de hacer frente a los altos requisitos actuales de TDT es el est谩ndar americano ATSC 3.0 (2016). Al igual que con DVB-T2, se necesita proceso completo de evaluaci贸n del sistema. Por ello, en esta tesis se han realizado simulaciones y pruebas de laboratorio para completar el estudio de rendimiento de ATSC 3.0 en diferentes escenarios

    PAPR Reduction in Multicarrier Communication Systems Using Efficient Pulse Shaping Technique

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    Emerging multicarrier modulation schemes have been considered for the fifth generation (5G) communication systems. However, existing designs often suffer from a high peak-to-average power ratio (PAPR) in the transmitted signal. This thesis aims to (i) design pulse shaping filters to reduce the PAPR using computationally efficient optimisation approach (ii) investigate the performance of the multicarrier systems employing the designed filter and (iii) study the power utilisation efficiency of the nonlinear amplifier with the use of the designed filters

    Modeling and Optimization of Next-Generation Wireless Access Networks

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    The ultimate goal of the next generation access networks is to provide all network users, whether they are fixed or mobile, indoor or outdoor, with high data rate connectivity, while ensuring a high quality of service. In order to realize this ambitious goal, delay, jitter, error rate and packet loss should be minimized: a goal that can only be achieved through integrating different technologies, including passive optical networks, 4th generation wireless networks, and femtocells, among others. This thesis focuses on medium access control and physical layers of future networks. In this regard, the first part of this thesis discusses techniques to improve the end-to-end quality of service in hybrid optical-wireless networks. In these hybrid networks, users are connected to a wireless base station that relays their data to the core network through an optical connection. Hence, by integrating wireless and optical parts of these networks, a smart scheduler can predict the incoming traffic to the optical network. The prediction data generated herein is then used to propose a traffic-aware dynamic bandwidth assignment algorithm for reducing the end-to-end delay. The second part of this thesis addresses the challenging problem of interference management in a two-tier macrocell/femtocell network. A high quality, high speed connection for indoor users is ensured only if the network has a high signal to noise ratio. A requirement that can be fulfilled with using femtocells in cellular networks. However, since femtocells generate harmful interference to macrocell users in proximity of them, careful analysis and realistic models should be developed to manage the introduced interference. Thus, a realistic model for femtocell interference outside suburban houses is proposed and several performance measures, e.g., signal to interference and noise ratio and outage probability are derived mathematically for further analysis. The quality of service of cellular networks can be degraded by several factors. For example, in industrial environments, simultaneous fading and strong impulsive noise significantly deteriorate the error rate performance. In the third part of this thesis, a technique to improve the bit error rate of orthogonal frequency division multiplexing systems in industrial environments is presented. This system is the most widely used technology in next-generation networks, and is very susceptible to impulsive noise, especially in fading channels. Mathematical analysis proves that the proposed method can effectively mitigate the degradation caused by impulsive noise and significantly improve signal to interference and noise ratio and bit error rate, even in frequency-selective fading channels

    Reception performance studies for the evaluation and improvement of the new generation terrestrial television systems

    Get PDF
    270 p.La industria de la TV ha experimentado grandes cambios en las 煤ltimas d茅cadas. Las expectativas cada vez mayores de los espectadores y la reducci贸n del espectro disponible para los servicios de TV han provocado la necesidad de sistemas m谩s robustos de Televisi贸n Digital Terrestre (TDT).El primer intento de cumplir estos requisitos es el est谩ndar europeo DVB-T2 (2009). La publicaci贸n de un nuevo est谩ndar significa el inicio de un proceso de evaluaci贸n del rendimiento del mismo mediante, por ejemplo, estudios de cobertura u obtenci贸n de valores de umbral de relaci贸n se帽al / ruido (SNR). Al inicio de esta tesis, este proceso estaba casi terminado para recepci贸n fija y m贸vil. Sin embargo, la recepci贸n en interiores no se hab铆a estudiado en detalle. Por esta raz贸n, esta tesis completa la evaluaci贸n de DVB-T2 en interiores y define una nueva metodolog铆a de evaluaci贸n optimizada para este escenario.A pesar de que DVB-T2 emplea tecnolog铆as muy avanzadas, el sistema se defini贸 hace casi diez a帽os y desde entonces han aparecido nuevas t茅cnicas avanzadas, como por ejemplo nuevos c贸digos de correcci贸n de errores o la nueva t茅cnica de multiplexaci贸n por divisi贸n en capas (LDM). Estas nuevas t茅cnicas tampoco han sido evaluadas en entornos de interior, por lo que esta tesis incluye el an谩lisis de las mismas evaluando su idoneidad para mejorar el rendimiento de DVB-T2. Adem谩s, se ha comprobado que los algoritmos tradicionales de los receptores TDT no est谩n optimizados para los nuevos escenarios en los que se consideran las se帽ales multicapa y recepci贸n m贸vil. Por esta raz贸n, se han propuesto nuevos algoritmos para mejorar la recepci贸n en este tipo de situaciones.El 煤ltimo intento de hacer frente a los altos requisitos actuales de TDT es el est谩ndar americano ATSC 3.0 (2016). Al igual que con DVB-T2, se necesita proceso completo de evaluaci贸n del sistema. Por ello, en esta tesis se han realizado simulaciones y pruebas de laboratorio para completar el estudio de rendimiento de ATSC 3.0 en diferentes escenarios
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