Mobile and Wireless Communications

Mobile and Wireless Communications have been one of the major revolutions of the late twentieth century. We are witnessing a very fast growth in these technologies where mobile and wireless communications have become so ubiquitous in our society and indispensable for our daily lives. The relentless demand for higher data rates with better quality of services to comply with state-of-the art applications has revolutionized the wireless communication field and led to the emergence of new technologies such as Bluetooth, WiFi, Wimax, Ultra wideband, OFDMA. Moreover, the market tendency confirms that this revolution is not ready to stop in the foreseen future. Mobile and wireless communications applications cover diverse areas including entertainment, industrialist, biomedical, medicine, safety and security, and others, which definitely are improving our daily life. Wireless communication network is a multidisciplinary field addressing different aspects raging from theoretical analysis, system architecture design, and hardware and software implementations. While different new applications are requiring higher data rates and better quality of service and prolonging the mobile battery life, new development and advanced research studies and systems and circuits designs are necessary to keep pace with the market requirements. This book covers the most advanced research and development topics in mobile and wireless communication networks. It is divided into two parts with a total of thirty-four stand-alone chapters covering various areas of wireless communications of special topics including: physical layer and network layer, access methods and scheduling, techniques and technologies, antenna and amplifier design, integrated circuit design, applications and systems. These chapters present advanced novel and cutting-edge results and development related to wireless communication offering the readers the opportunity to enrich their knowledge in specific topics as well as to explore the whole field of rapidly emerging mobile and wireless networks. We hope that this book will be useful for students, researchers and practitioners in their research studies

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

BEP Analysis of OSTBC-OFDM systems with broadband pa and imperfect memory compensation

We analyze the performance of an OFDM system with diversity, in particular Orthogonal Space Time Block Coding (OSTBC) systems, including a broadband nonlinear power amplifier (PA) with memory. Closed-form expressions for the BER are obtained for cases when PA memory is compensated at the transmitter or the receiver. The results confirm that not only clipping noise, but also imperfect PA memory compensation has a significant impact on the system performance.Fil: Gregorio, Fernando Hugo. University of Helsinski; Finlandia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Werner, Stefan. University of Helsinski; FinlandiaFil: Hamalainen, Jyri. Nokia Siemens Networks; FinlandiaFil: Wichman, Risto Ilari. University of Helsinski; FinlandiaFil: Cousseau, Juan Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentin

Epälineaaristen tehovahvistimien suorituskykyanalyysi ja epälineaarisuuksien kompensointi usean antennin OFDM-järjestelmissä

The high peak to average power ratio (PAPR) levels associated with multicarrier systems require the use of linear power amplifiers (PA) with large dynamic range. Unfortunately, linearity and power efficiency are two conflicting specifications for practical PAs. However, systems with high power efficiency are required, for example, in case of battery operated mobile terminals. Thus, the PA needs to operate in a high power efficiency region which compromises the linearity constraints. The evaluation of the effect of nonlinear amplification on the system performance is an important issue that must be considered in a realistic system design. This thesis first addresses the performance analysis of multiuser OFDM systems (space division multiple access (SDMA)-OFDM) employing nonlinear PAs. Bit error probability (BEP) and capacity expressions are derived for an OFDM system with diversity, assuming a memoryless PA. Moreover, BEP expressions are derived for an orthogonal space-time coded (OSTBC)-OFDM system that include the effect of a broadband nonlinear PA and imperfect memory compensation. Thereafter, techniques to reduce the effects of power amplifier distortion are proposed. We consider techniques that can be implemented either in the receiver, the transmitter, or as a combination of both, all with the same goal of relieving the linearity constaints and improving the power efficiency. A low PAPR OFDM implementation is addressed where subcarriers are allocated to different users in such a way that the generated intermodulation distortion is kept at minimum. Then, we propose the combination of multiuser detection and nonlinear distortion mitigation techniques. Initially, knowledge of the PA model (modelled as memoryless) is required for the implementation. The extension to broadband PAs and to PA model estimation in the receiver are also made. Efficient channel estimation strategies are developed that work in the presence of nonlinear distortion. Finally, a split predistorter structure to remove nonlinear distortion caused by a broadband PA is proposed. The idea is to reduce the transmitter complexity by distributing the predistorter tasks such that the transmitter compensates for the static nonlinearity, and the receiver equalizes the PA memory.Lähetystehon suuri vaihtelu monikantoaaltojärjestelmissä asettaa tiukkoja vaatimuksia tehovahvistimille. Vahvistimien lineaarisen alueen pitää olla suuri, mikä johtaa huonoon hyötysuhteeseen ja suureen tehonkulutukseen vahvistimen operoidessa lineaarisella alueella. Jos vahvistimen hyötysuhde halutaan pitää korkeana, kuten esimerkiksi akuilla toimivissa kannettavissa päätelaitteissa, vahvistettu signaali väistämättä vääristyy. Näiden epälineaaristen vääristymien kompensointi on tärkeä osa langattomien tietoliikennejärjestelmien suunnittelua. Tässä työssä tarkastellaan epälineaaristen tehovahvistimien vaikutusta monen käyttäjän OFDM-järjestelmiin ja näiden vaikutusten kompensointia lähettimessä ja/tai vastaanottimessa, kun päätelaitteissa voi olla useampia antenneja. Lähettimessä vääristymien epäedullista vaikutusta vähennetään lomittelemalla lähetettyjä kantoaaltoja eri lähetysantennien kesken. Vastaanottimessa monen käyttäjän ilmaisu yhdistetään vääristymien kompensointiin ja kanavaestimointiin. Lopuksi työssä kehitetään algoritmi, jossa vääristymien kompensointi jaetaan lähettimen ja vastaanottimen kesken. Työssä myös johdetaan vastaanottimen virhetodennäköisyyslausekkeet ja kanavan kapasiteettilausekkeet erilaisille systeemimalleille, kun lähetetty signaali on vääristynyt epälineaarisesti.reviewe