Energy Efficient Cooperative Wireless Communication and Networks

Energy Efficient Cooperative Wireless Communication and Networks
Author: Zhengguo Sheng
Publisher: CRC Press
Total Pages: 216
Release: 2014-11-11
Genre: Computers
ISBN: 1482238225

Compared with conventional communications, cooperative communication allows multiple users in a wireless network to coordinate their packet transmissions and share each other's resources, thus achieving high-performance gain and better service coverage and reliability. Energy Efficient Cooperative Wireless Communication and Networks provides a comp

Improving Efficiency of Wireless Networks Using Network Optimized Beamforming, Virtual Terrain Leveling, and High-performance Computing

Improving Efficiency of Wireless Networks Using Network Optimized Beamforming, Virtual Terrain Leveling, and High-performance Computing
Author: Vinay Bharadwaj Ramakrishnaiah
Publisher:
Total Pages: 131
Release: 2018
Genre: Antenna arrays
ISBN: 9780438395138

Wireless communication is sensitive to ambient noise as well as interference due to the use of a shared medium, unlike wired communication. The range of frequencies used for wireless communication is limited, which prompts the reuse of frequencies causing increased interference. Wireless devices are often portable or mobile units with limited battery capacity, which makes effective low-power communication in harsh noise environments a high priority. In addition, wireless communication is significantly affected by the surrounding terrain like buildings, hills, foliage, etc. Many of these problems can be addressed through careful antenna design. Typically, omni-directional antennas are used in wireless communication due to their relative simplicity. These antennas radiate signal equally in all directions resulting in a waste of transmitter power and a source of interference to other nodes. More sophisticated techniques are available, but these can be challenging as they require complex software, which in turn demands powerful and expensive hardware. Use of adaptive directional antenna arrays can minimize interference while also being more energy efficient. Such “smart antennas” use digital beamforming based on signal processing algorithms to compute the appropriate weights to form effective antenna patterns. Smart antennas require the knowledge of the signal received at each antenna in the antenna array, thereby increasing the complexity of hardware and cost. Analog beamforming is a low hardware complexity alternative to smart antennas, which relies on a single transceiver and power splitter/combiner. Computer controlled analog amplifiers and phase shifters are used to form the desired beam patterns. The disadvantage of analog beamforming is that the computer only has access to the combined signals in the antenna array. We use analog beamforming in our implementation along with Noise-to-Signal ratio of nearby communicating nodes to mitigate this disadvantage. Conventional smart antennas optimize results for each individual node, while it is preferable to have a global optimal solution. It is also possible to compute the antenna array weights to adapt to the radio propagation characteristics of the surrounding terrain. This requires the knowledge of path loss at various distances and directions from the transmitter calculated using one of several available path loss models to compute a radio propagation map. This research has the following objectives: The first objective is to develop a new analog beamforming technique using Noise-to-Signal ratio as the performance measure. An iterative algorithm is developed that uses distributed node information along with analog beamforming, instead of individual antenna information. The antenna weights are sequentially adjusted across all nodes in the route to achieve optimization across the network. This provides a network optimized, low cost and hardware complexity solution for adaptive beamforming. The second objective is to explore another novel method called Virtual Terrain Leveling (VTL) where the effects of the terrain are virtually nullified using antenna arrays up to a specified distance from the transmitter. This work investigates whether VTL can mitigate the difficulties that the terrain features pose for implementation of wireless networks by attempting to provide uniform propagation in the presence of terrain with the use of directional antennas. The final objective is to use high performance computing (HPC) to develop more efficient storage and processing of radio propagation maps. Processing and storage of radio propagation maps can be computationally intensive based on the area and the resolution of the map. The technique of adaptive region construction is developed to efficiently store radio propagation maps while preserving the shape of the external contour for a given set of points. A GPU implementation of the algorithm with optimizations tailored to the hardware shows possible near - real time performance.

Adaptation in Wireless Communications - 2 Volume Set

Adaptation in Wireless Communications - 2 Volume Set
Author: Mohamed Ibnkahla
Publisher: CRC Press
Total Pages: 1048
Release: 2018-10-08
Genre: Technology & Engineering
ISBN: 1482290332

The widespread use of adaptation techniques has helped to meet the increased demand for new applications. From adaptive signal processing to cross layer design, Adaptation in Wireless Communications covers all aspects of adaptation in wireless communications in a two-volume set. Each volume provides a unified framework for understanding adaptation and relates various specializations through common terminologies. In addition to simplified state-of-the-art cross layer design approaches, they also describe advanced techniques, such as adaptive resource management, 4G communications, and energy and mobility aware MAC protocols.

Simplified Robust Adaptive Detection and Beamforming for Wireless Communications

Simplified Robust Adaptive Detection and Beamforming for Wireless Communications
Author: Ayman ElNashar
Publisher: John Wiley & Sons
Total Pages: 424
Release: 2018-08-20
Genre: Technology & Engineering
ISBN: 1118938240

This book presents an alternative and simplified approaches for the robust adaptive detection and beamforming in wireless communications. It adopts several systems models including DS/CDMA, OFDM/MIMO with antenna array, and general antenna arrays beamforming model. It presents and analyzes recently developed detection and beamforming algorithms with an emphasis on robustness. In addition, simplified and efficient robust adaptive detection and beamforming techniques are presented and compared with exiting techniques. Practical examples based on the above systems models are provided to exemplify the developed detectors and beamforming algorithms. Moreover, the developed techniques are implemented using MATLAB—and the relevant MATLAB scripts are provided to help the readers to develop and analyze the presented algorithms. em style="mso-bidi-font-style: normal;"Simplified Robust Adaptive Detection and Beamforming for Wireless Communications starts by introducing readers to adaptive signal processing and robust adaptive detection. It then goes on to cover Wireless Systems Models. The robust adaptive detectors and beamformers are implemented using the well-known algorithms including LMS, RLS, IQRD-RLS, RSD, BSCMA, CG, and SD. The robust detection and beamforming are derived based on the existing detectors/beamformers including MOE, PLIC, LCCMA, LCMV, MVDR, BSCMA, and MBER. The adopted cost functions include MSE, BER, CM, MV, and SINR/SNR.

Advanced Wireless Communications

Advanced Wireless Communications
Author: Savo G. Glisic
Publisher: John Wiley & Sons
Total Pages: 878
Release: 2005-12-13
Genre: Technology & Engineering
ISBN: 0470867779

The wireless community is on the verge of the standardization of fourth generation (4G) systems. Research has generated a number of solutions for significant improvement of system performance. The development of enabling technologies such as adaptive coding and modulation, iterative (turbo) decoding algorithms and space-time coding, means that industry can now implement these solutions. Advanced Wireless Communications: 4G Technologies focuses on the system elements that provide adaptability and reconfigurability and discusses how these features can improve 4G system performance. There are several different systems comprising 4G, including adaptive WCDMA (Wideband Code Division Multiple Access), ATDMA (Adaptive Time Division Multiple Access), Multicarrier (OFDMA) and Ultra Wide Band (UWB) receiver elements. This book provides a comparative study of these technologies and focuses on their future co-existence. Topics covered include: Space Time Coding, including discussions on diversity gain, the encoding and transmission sequence, the combining s cheme and ML decision rule for two-branch transmit diversity scheme with one and M receivers. Ultra Wide Band Radio, UWB multiple access in Gaussian channels, the UWB channel, UWB system with M-ary modulation, M-ary PPM UWB multiple access, coded UWB schemes, multi-user detection in UWB radio, UWB with space time processing and beam forming for UWB radio. Antenna array signal processing with focus on Space-Time receivers for CDMA communications, MUSIC and ESPRIT DOA estimation, joint array combining and MLSE receivers, joint combiner and channel response estimation and complexity reduction in the wide-band beam forming Channel modeling and measurement, adaptive MAC, adaptive routing and TCP layer are also addressed. This book will supply the reader with a comprehensive understanding of the relationship between the systems performance, its complexity/reliability and cost-effectiveness. It gives an insight into the impact of existing and new technologies on the receiver structure and provides an understanding of current approaches and evolving directions for personal and indoor communication.

Wireless Sensor Networks

Wireless Sensor Networks
Author: Suraiya Tarannum
Publisher: BoD – Books on Demand
Total Pages: 352
Release: 2011-06-30
Genre: Technology & Engineering
ISBN: 953307325X

The importance and ubiquity of wireless networks in the modern age justifies the depth and scope of the chapters included in this book, with its special focus on sensors. Topics covered include MAC protocols, with one contribution offering a literature review on them. Energy efficiency is also important, with several chapters addressing cooperative beamforming, modern spatial-diversity techniques and MEMS. Hardware issues are addressed by a batch of chapters, on extending network coverage areas, CMOS RF transceivers, the use of an accelerometer sensor module and a fall-detection monitoring system and a couple of contributions on hierarchical paradigms in wireless sensor networks. More mathematical approaches are also included, with chapters on data aggregation tree construction and distributed localization algorithms.