SIMPLIFIED TECHNIQUE FOR DESIGNING OF BROADBAND PATCH ANTENNAS ab 49 € als Taschenbuch: Novel technique is devised in order to increase the bandwidth for a linear polarized Microwave antenna. Aus dem Bereich: Bücher, Wissenschaft, Technik,
SIMPLIFIED TECHNIQUE FOR DESIGNING OF BROADBAND PATCH ANTENNAS ab 49 EURO Novel technique is devised in order to increase the bandwidth for a linear polarized Microwave antenna
Multi-Carrier Direct-Sequence Code Division Multiple Access (MC-DS-CDMA) is a multiplexing technique that combines the advantages of both multi-carrier modulation and DS-CDMA. Among them are high system flexibility, high data rate transmission, high bandwidth efficiency and fading resilience. Adopted as an option for the down-link transmission in the CDMA2000 third Generation (3G) cellular standard, MC-DS-CDMA is also one of the potential candidates for the future fourth Generation (4G) broadband wireless systems. When designing receivers for MC-DS-CDMA mobile wireless systems, two main problems must be taken into account. Firstly, the Multiple Access Interference (MAI) caused by other active users greatly limits the system capacity. Secondly, the multi-path fading of mobile radio channels which highly degrades the system performance. Therefore, in this book, our objective is twofold. Firstly, we aim at designing new receivers for MC-DS-CDMA systems that are able to suppress the MAI. Secondly, as receiver design usually requires the explicit channel estimation, we intend to develop new techniques to estimate time-varying fading channels.
This book is intended to illustrate an art of antenna design technique for wireless communication system, and its development and implementation on field of antenna technology. The endeavor is to impart a working knowledge of the subject not just for students and researchers but for the entire wireless community. This book focuses on designing three types of new broadband antennas. Design analysis has been carried out covering the frequency of IMT-2000 and ultrawideband (UWB). The first two types of the antenna designs adopt contemporary techniques, L-probe feeding, inverted patch structure with air-filled dielectric and the new shape patches. The composite effect of integrating these techniques and by introducing the new EE-H and E-H shaped patches, offers a low profile, high gain, broadband, and compact antenna element. The third type of antenna is developed for UWB frequency band which is based on new stacked patch technique with a folded patch feed. The bandwidth is obtained by a stacked patch fed with a folded patch feed, and the size reduction is realized through the use of shorting wall.
Nowadays, the requirements in terms of communication are increasing exponentially and getting more diverse. The transmission data rates must be high while maintaining very good quality of service (QoS) despite the very hostile propagation channels. Generally, transmissions that are carried out on mobile radio channels are selective both in time and frequency. To overcome the channel selectivity and allows high transmission data rates, the Long Term Evolution (LTE) standard makes use of the Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) technique. By implementing this technique in the context of mobile transmission, new approaches for time and frequency synchronization, equalization and channel estimation are needed. This book focuses on the study, modeling and development of efficient channel estimation techniques for broadband mobile radio channels and specifically for LTE systems. This book is interesting for both undergraduate and postgraduate students in the field of wireless communication systems. The professional engineers will find also this book useful in improving and designing new wireless communication systems.
Wireless Mesh Networking is envisioned as an economically viable paradigm and a promising technology in providing wireless broadband services. A key factor in designing protocols for a wireless mesh network (WMN) is to exploit its distinct characteristics, mainly immobility of mesh routers and less-constrained power consumption. In this work, we present a literature review of the work done on routing and scheduling in WMNs before. In addition, we study the effect of varying the transmission power to allow and maximize the number of simultaneously active transmissions in the network. We propose a QoS-aware routing framework using transmission power control. The framework addresses both link scheduling and QoS routing problems taking into consideration the spatial reuse of the network bandwidth. We formulate an optimization problem to find the optimal link schedule and use it as a fitness function in a genetic algorithm to find candidate routes. Using computer simulations, we show that by optimal power allocation the QoS constraints for the different traffic flows are met.
Microstrip patch antennas (MPA) were preferred for such work due to their small size. The development of MPA enters its prosperous era after the debut of the first practical microstrip antenna in 1970s. Since then, microstrip patch antennas have been widely employed in modern wireless communication systems. It is because microstrip patch antennas have many advantages of low profile, light weight, easy fabrication, conformal and easy integration with integrated circuits. However, conventional patch antennas suffer from narrow bandwidth and large size. Along with the rising demand for wider bandwidth and smaller size, wide-band and compact patch antennas have been developed extensively. A technique of broad banding by slot loading is preferred. By means, slots are cut into rectangular patch antenna in order to cut the current flow lines, so that higher frequency modes can be perturbed and ratio of two frequencies can be adjusted by adjusting the slot size. Then to reduce the size of the antenna the loading of shorting pins was introduced. This type of antenna is often known as PIFA. Due to its compact size, PIFA is used in mobile and wireless communication.