Enabling Technology and Algorithm Design for Location-Aware Communications

Location-awareness is emerging as a promising technique for future-generation wire­ less network to adaptively enhance and optimize its overall performance through location-enabled technologies such as location-assisted transceiver reconfiguration and routing. The availability of accurate location information of mobile users becomes the essential prerequisite for the design of such location-aware networks. Motivated by the low locationing accuracy of the Global Positioning System (GPS) in dense multipath environments, which is commonly used for acquiring location information in most of the existing wireless networks, wireless communication system-based po­sitioning systems have been investigated as alternatives to fill the gap of the GPS in coverage. Distance-based location techniques using time-of-arrival (TOA) mea­surements are commonly preferred by broadband wireless communications where the arrival time of the signal component of the First Arriving Path (FAP) can be con­verted to the distance between the receiver and the transmitter with known location. With at least three transmitters, the location of the receiver can be determined via trilatération method. However, identification of the FAP’s signal component in dense multipath scenarios is quite challenging due to the significantly weaker power of the FAP as compared with the Later Arriving Paths (LAPs) from scattering, reflection and refraction, and the superposition of these random arrival LAPs’ signal compo­ nents will become large interference to detect the FAP. In this thesis, a robust FAP detection scheme based on multipath interference cancellation is proposed to im­ prove the accuracy of location estimation in dense multipath environments. In the proposed algorithm, the signal components of LAPs is reconstructed based on the estimated channel and data with the assist of the communication receiver, and sub­ sequently removed from the received signal. Accurate FAP detection results are then achieved with the cross-correlation between the interference-suppressed signal and an augmented preamble which is the combination of the original preamble for com­ munications and the demodulated data sequences. Therefore, more precise distance estimation (hence location estimation) can be obtained with the proposed algorithm for further reliable network optimization strategy design. On the other hand, multiceli cooperative communication is another emerging technique to substantially improve the coverage and throughput of traditional cellular networks. Location-awareness also plays an important role in the design and imple­mentation of multiceli cooperation technique. With accurate location information of mobile users, the complexity of multiceli cooperation algorithm design can be dra­matically reduced by location-assisted applications, e.g., automatic cooperative base station (BS) determination and signal synchronization. Therefore, potential latency aroused by cooperative processing will be minimized. Furthermore, the cooperative BSs require the sharing of certain information, e.g., channel state information (CSI), user data and transmission parameters to perform coordination in their signaling strategies. The BSs need to have the capabilities to exchange available information with each other to follow up with the time-varying communication environment. As most of broadband wireless communication systems are already orthogonal frequency division multiplexing (OFDM)-based, a Multi-Layered OFDM System, which is spe­cially tailored for multiceli cooperation is investigated to provide parallel robust, efficient and flexible signaling links for BS coordination purposes. These layers are overlaid with data-carrying OFDM signals in both time and frequency domains and therefore, no dedicated radio resources are required for multiceli cooperative networks. In the final aspect of this thesis, an enhanced channel estimation through itera­ tive decision-directed method is investigated for OFDM system, which aims to provide more accurate estimation results with the aid of the demodulated OFDM data. The performance of traditional training sequence-based channel estimation is often lim­ ited by the length of the training. To achieve acceptable estimation performance, a long sequence has to be used which dramatically reduces the transmission efficiency of data communication. In this proposed method, the restriction of the training se­quence length can be removed and high channel estimation accuracy can be achieved with high transmission efficiency, and therefore it particular fits in multiceli coopera­tive networks. On the other hand, as the performance of the proposed FAP detection scheme also relies on the accuracy of channel estimation and data detection results, the proposed method can be combined with the FAP detection scheme to further optimize the accuracy of multipath interference cancellation and FAP detection

Techno-economic analysis of a 5G network in Spain

Information society and mobile society are two concepts that are both linked and undeniable. The first one refers to the necessity of high amount of information to develop most aspects of our lives, while the second one is related to the importance of mobile devices to get, analyse and use that information. In other words, every mobile device (that embraces not only mobile phones but also many other gadgets) has become a tool that shall interact with information. In order to fulfil those needs, technology has evolved, resulting into faster, more secure and more reliable networks. Needless to say, mobile networks are playing an indispensable role, as long as the society is evolving to a more and more mobile one, as above mentioned. Furthermore, new applications that had not been even imagined years ago must be fulfilled as well (i.e. smart cities). There are many industries that carry the weight of this progress. Companies of various sectors of our economy must develop each piece of the puzzle to ensure that the jigsaw is solved. Another important player should not be forgotten. The regulatory institutions and frameworks must coordinate all this investigations and progress in order to assure the universality, integrity and reachability of itself. The purpose of this document is to consider what the mobile communications needs of today’s society are, what they will be on a short, mid and long run, and how can they be solved. To face this task, the two main actors above mentioned will be taken into account. From the regulatory perspective, the proposals and law measures (i.e. IMT-2020 and new frequency allocations) must be considered, as well as the technical requirements for 5G generation, whether to be considered the subsequent evolution of LTE network or a new network, or even both. From the mobile companies’ point of view, a dense analysis on technical solutions to reach the above mentioned requirements will be followed by an economic analysis to discuss the profitability of the deployment of a 5G network. It must be understood that this study contemplates several scenarios, due to the different possibilities in terms of the spectrum policies and demand evolution in the forthcoming years. To this end, the several scenarios combined with the different cases of use must be taken into account, as well as many other KPIs. The coherent combination and analysis of all this parameters will reveal the requirements’ feasibility amongst varying scenarios.Ingeniería en Tecnologías de Telecomunicació

Transceiver design for wireless energy harvesting cooperative networks

In this thesis, the RF energy harvesting technique is studied in the cooperative wireless network, and different optimization studies are investigated. First, an energy-efficient optimization is considered in the cooperative system with the time switching relaying and power splitting relaying protocols. Then, a security issue in the cooperative network with energy harvesting is proposed, in which the optimization problem is designed to maximize the secrecy rate. We also consider the application of energy harvesting in the full-duplex relaying network with a self-energy recycling protocol. Finally, the energy harvesting is studied in the full-duplex cooperative cognitive radio network. The system performance of all studies is verified in the thesis with MATLAB simulation results

Radio Planning and Management of Energy-Efficient Wireless Access Networks

RÉSUMÉ Dans les dernières années, le secteur des Technologies de l'Information et de la Communication (TIC) a transformé la façon dont nous vivons: il joue un rôle principal sur le développement économique et la productivité, en offrant des services innovants qui sont devenus partie intégrante de la vie quotidienne. En raison de ce phénomène, l'effet des technologies de l'information et de la communication sur le réchauffement climatique ne peut plus être ignoré. Le concept des TIC Vertes (ou Green ICT, en anglais) est né dans le but de stimuler la recherche vers des solutions respectueuses de l'environnement et économes en énergie. Étant une partie important des TIC, les réseaux de télécommunication connaissent une croissance en plein essor. Les contraintes de qualité de service et de capacité sont les principaux responsables de l'augmentation de la consommation d'énergie; en particulier, une grande partie de la facture d'électricité des opérateurs de réseaux est due aux exigences élevées de puissance des stations de base sans fil, qui ont été identifiées comme les composantes les plus énergivores des réseaux. Jusqu'à présent, l'industrie de la communication mobile s'est essentiellement concentrée sur le développement de terminaux mobiles à faible consommation d'énergie afin d'attirer un plus grand nombre de clients et, par conséquent, d'augmenter les profits des opérateurs; en revanche, le monde de la recherche étudie la question de l'efficacité énergétique d'un point de vue plus large. En plus des études sur dispositifs et protocoles économes en puissance, des travaux plus récents ont abordé la problème du design et du fonctionnement éco-énergétiques dans les infrastructures de réseaux câblés et sans fil. De nombreux aspects de la planification et gestion des réseaux verts ont été explorés. Cependant, les deux problèmes n'ont jamais été liés et abordés à la fois, en négligeant le fait que l'efficacité d'une gestion de réseau à faible consommation d'énergie dépend en grande partie des décisions prises dans la phase de design.----------ABSTRACT In the last years, the ICT sector has transformed the way we live. Consistently delivering innovative products and services, the ICT assumed a primary role on economic development and productivity, becoming an integral part of everyday life. However, due to their wide and constantly increasing diffusion, the effect of information and communication technologies on global warming can no longer be ignored. The concept of Green ICT has originated with the aim of building awareness of this, thus boosting the research toward environmentally sustainable, energy-efficient technologies and solutions. As an important part of the ICT, telecommunication networks are experiencing a booming growth. Capacity issues and quality of service constraints are some of the main concerns that contribute to raise the power consumption. In particular, a large portion of the electricity bill results from the high power requirements of wireless base stations, which have been proved to be the most energy-hungry network components. Up to now, the mobile communication industry has focused mostly on the development of power-efficient mobile terminals, so as to attract a higher number of customers and consequently increase the operators' profits; on the other hand, the research world has been investigating energy efficiency from a wider point of view. Besides studies on power-efficient devices and protocols, more recent works addressed the problem of energy-aware design and operation in wired and wireless network infrastructures. Many aspects and challenges of green network planning and management have been explored; nevertheless, the two problems have never been linked and tackled at the same time, neglecting the fact that an effective power-efficient network operation largely depends on the decisions taken in the design phase. The research presented in this doctoral thesis aims at filling this gap by developing an optimization framework that jointly considers the design and operation of wireless networks. The proposed joint planning and energy management problem (JPEM) strives to prove that, when cell sleeping is adopted as network management technique, the level of flexibility offered by the installed topology strongly improves the system capability to adapt to the varying traffic load. By minimizing the trade-off between capital expenditures (CapEx) related to the network deployment and operational expenditures (OpEx) calculated over the network lifetime, the model finds the most energy-efficient network topology while meeting the capital investment limitations imposed by the mobile operator