Reducing Multiple Access Interference in Broadband Multi-user Wireless Networks PDF Download

Author: Ali Nayef Alqatawneh
Publisher:
ISBN: 9781321885637
Category : Broadband communication systems
Languages : en
Pages : 238

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Book Description
This dissertation is devoted to developing multiple access interference (MAI) reduction techniques for multi-carrier multi-user wireless communication networks. In multi-carrier code division multiple access (MC-CDMA) systems, a full multipath diversity can be achieved by transmitting one symbol over multiple orthogonal subcarriers by means of spreading codes. However, in frequency selective fading channels, orthogonality among users can be destroyed leading to MAI. MAI represents the main obstacle to support large number of users in multi-user wireless systems. Consequently, MAI reduction becomes a main challenge when designing multi-carrier multi-user wireless networks. In this dissertation, first, we study MC-CDMA systems with different existing MAI reduction techniques. The performance of the studied systems can be further improved by using a fractionally spaced receivers instead of using symbol spaced receivers. A fractionally spaced receiver is obtained by oversampling received signals in a time domain. Second, a novel circular-shift division multiple access (CSDMA) scheme for multi-carrier multi-user wireless systems is developed. In CSDMA, each symbol is first spread onto multiple orthogonal subcarriers in the frequency domain through repetition codes. The obtained frequency-domain signals are then converted to a time-domain representation. The time-domain signals of different users are then circularly shifted by different numbers of locations. The time-domain circular shifting enables the receiver to extract signals from different users with zero or a small amount of MAI. Our results show that the CSDMA scheme can achieve a full multipath diversity with a performance outperforms that of orthogonal frequency division multiple access (OFDMA). Moreover, multipath diversity of CSDMA can be further improved by employing the time-domain oversampling. Performance fluctuations due to a timing offset between transmitter and receiver clocks in MC-CDMA and CSDMA systems can be removed by employing the time-domain oversampling. Third, we study the theoretical error performance of high mobility single-user wireless communication system with doubly selective (time-varying and frequency-selective) fading channel under impacts of imperfect channel state information (CSI). Throughout this dissertation, intensive computer simulations are performed under various system configurations to investigate the obtained theoretical results, excellent agreements between simulation and theoretical results were observed in this dissertation.

Author: Man-On Pun
Publisher: World Scientific
ISBN: 1860949460
Category : Computers
Languages : en
Pages : 272

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Book Description
Multi-Carrier Techniques for Broadband Wireless Communications provides an accessible introduction to OFDM-based systems from a signal processing perspective. The first part presents a concise treatment of some fundamental concepts related to wireless communications and multicarrier systems, while the second offers a comprehensive survey of recent developments on a variety of critical design issues. These include synchronization techniques, channel estimation methods, adaptive resource allocation and practical schemes for reducing the peak-to-average power ratio of the transmitted waveform.

Author: Vasanth Raj P T
Publisher: Classicsbooks
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 0

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Book Description
Wireless Communication has emerged enormously in recent years. The habit of internet turns out to be an obligatory for present-day living lifestyle. Information transformation over wireless medium gets increased due to the development in technology. Information over mobile communication is transferred from base station (BS) to mobile station (MS), vice versa over wireless medium. This leads to increase in users. Future generation (5G) wireless networks objective is to offer high data rate, and supports voice, data and video which requires larger bandwidth. Information's are transferred in the form data, pictures and video to the user. Data, pictures and videos are transmitted through the wireless network in the form of data packets. These are transmitted through antenna. To increase the data rate of transmission Multiple-input-Multiple-output (MIMO) technique is introduced. MIMO helps to transfer large amount of data in short span due to its high data rate performance. Recent studies show that users are increasing rapidly due to this advantage. When users get increased then there will be a lag in the entire performance of the system especially in bit error rate (BER) performance.Movement of the users and propagation in an unconstrained media may leads to fading, shadowing and delay spread. It front-runners to major interferences like Multiple Access Interference (MAI), Co-Channel Interference (CCI) and Inter Symbol Interference (ISI). Research reveals that this will affect the future of wireless communication. These interferences will affect the system's BER performance. Researcher from various countries paid a lot of consciousness on Multi-Carrier Code Division Multiple Access (MC-CDMA) technique. It is one of the most powerful air interfaces for reverse link of next generation broadband mobile communication system and for tranquillize the interferences. MC-CDMA has the welfare of frequency-diversity, better advantages of orthogonal frequency division multiplexing (OFDM) and Code Division Multiple Access (CDMA). MC-CDMA has the high prospective to transmit data's in the form of pictures, voice and video. It enrolls Multi-User detection (MUD) technique to mitigate the effect of interference. MUD algorithm is employed to achieve better BER performance of the system. MUD is used to demodulate mutual interfering signals. MUD reduces the interference to increase the capacity of the channel. It alleviates the problems that occurs nearby as well as far away.Transmitter Pre-processing (TP) is carried out to diminish the interference by signal processing at the transmitter side. Multi-user transmitter preprocessing (MUTP) is for transmitter, multiuser interferences conquestTP can be consummate at the transmitter side. MUTP are categories into mainly two type Optimal Maximum-likelihood sequence estimation (MLSE) and Suboptimal. From there MUTP are different types: Zero Forcing (ZF) MUTP, Minimum Mean Square Error (MMSE) MUTP, Maximum Mutual Information (MMI) MUTP, Minimum Variance Distortionless Response MUTP, etc. With this type of MUTP, system performance can be improved. Turbo Codes has the capacity to increase the gain of the channel. It is error correcting codes that comes closer to Shannon's limit. Turbo codes have an astonishing performance of BER at low signal to noise rate (SNR).Image transmission over wireless medium is a grueling errand for the users. Security of the image has to be taken care of while transmissionEncryption alike Advanced Encryption Standard (AES) and Arnold Cat Map (ACM) are frequently worn encrypting algorithm for secured transmission of data. Compression of image place a vital role when it comes to transmission of image. For compression discrete wavelet transform (DWT) and integrate wavelet transform (IWT) are preferred for their simple computation and low complexity.Super resolution (SR) is a practice castoff for improving the quality of the image.

Author: Lin Cai
Publisher:
ISBN:
Category :
Languages : en
Pages : 169

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Book Description
The next-generation wireless networks are expected to integrate diverse network architectures and various wireless access technologies to provide a robust solution for ubiquitous broadband wireless access, such as wireless local area networks (WLANs), Ultra-Wideband (UWB), and millimeter-wave (mmWave) based wireless personal area networks (WPANs), etc. To enhance the spectral efficiency and link reliability, smart antenna systems have been proposed as a promising candidate for future broadband access networks. To effectively exploit the increased capabilities of the emerging wireless networks, the different network characteristics and the underlying physical layer features need to be considered in the medium access control (MAC) design, which plays a critical role in providing efficient and fair resource sharing among multiple users. In this thesis, we comprehensively investigate the MAC design in both single- and multi-hop broadband wireless networks, with and without infrastructure support.

Author: Patrick Vandenameele
Publisher: Springer Science & Business Media
ISBN: 0306473240
Category : Technology & Engineering
Languages : en
Pages : 242

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Book Description
This volume proposes novel transmission techniques that achieve multi-path mitigation, through orthogonal frequency-domain processing, in combination with a high bandwidth efficiency, through space division multiple access. It also pays special attention to the real-world problems encountered when integrating core detection algorithms into a complete system.

Author: Hsiao-Hwa Chen
Publisher: John Wiley & Sons
ISBN: 0470024356
Category : Technology & Engineering
Languages : en
Pages : 512

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Book Description
Next Generation Wireless Systems and Networks offers an expert view of cutting edge Beyond 3rd Generation (B3G) wireless applications. This self-contained reference combines the basics of wireless communications, such as 3G wireless standards, spread spectrum and CDMA systems, with a more advanced level research-oriented approach to B3G communications, eliminating the need to refer to other material. This book will provide readers with the most up-to-date technological developments in wireless communication systems/networks and introduces the major 3G standards, such as W-CDMA, CDMA2000 and TD-SCDMA. It also includes a focus on cognitive radio technology and 3GPP E-UTRA technology; areas which have not been well covered elsewhere. Covers many hot topics in the area of next generation wireless from the authors’ own research, including: Bluetooth, all-IP wireless networking, power-efficient and bandwidth-efficient air-link technologies, and multi-user signal processing in B3G wireless Clear, step-by-step progression throughout the book will provide the reader with a thorough grounding in the basic topics before moving on to more advanced material Addresses various important topics on wireless communication systems and networks that have emerged only very recently, such as Super-3G technology, 4G wireless, UWB, OFDMA and MIMO Includes a wealth of explanatory tables and illustrations This essential reference will prove invaluable to senior undergraduate and postgraduate students, academics and researchers. It will also be of interest to telecommunications engineers wishing to further their knowledge in this field.

Author: Seyed Javad Kazemitabar
Publisher: Springer Science & Business Media
ISBN: 9048199905
Category : Technology & Engineering
Languages : en
Pages : 109

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Book Description
Unlike wired networks where transmitters have no effect on receivers other than their own, in wireless networks we are limited by interference. The traditional routing methods are not optimal any more when it comes to a wireless medium. The maximum data rate on each link depends not only on the power in that link but also on the transmitted power from adjacent links. That is why the problem of power optimal routing needs to be solved jointly with scheduling. This suggests a cross layer design method as opposed to traditional networking where the algorithm for each layer is designed separately. In Coping with Interference in Wireless Networks we introduce several methods engaging different layers of network to mitigate interference in a wireless network.

Author: Seyyed Hassan Mahboubi
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Spectrum sharing is known as a key solution to accommodate the increasing number of users and the growing demand for throughput in wireless networks. Interference is the primary barrier to enhancing the overall throughput of the network, especially in the medium and high signal to noise ratios (SNRs). Managing interference to overcome this barrier has emerged as a crucial step in developing efficient wireless networks. An interference management strategy, named interference Alignment, is investigated. It is observed that a single strategy is not able to achieve the maximum throughput in all possible scenarios, and in fact, a careful design is required to fully exploit all available resources in each realization of the system. In this dissertation, the impact of interference on the capacity of X networks with multiple antennas is investigated. Degrees of freedom (DoF) are used as a figure of merit to evaluate the performance improvement due to the interference management schemes. A new interference alignment technique called layered interference alignment, which enjoys the combined benefits of both vector and real alignment is introduced in this thesis. This technique, which uses a type of Diophantine approximation theorems first introduced by the author, is deployed and was proved to enable the possibility of joint decoding among the antennas of a receiver. With a careful transmitter signal design, this method characterizes the total DoF of multiple-input multiple-output (MIMO) X channels. Then, this result is used to determine the total DoF of two families of MIMO X channels. The Diophantine approximation theorem is also extended to the field of complex numbers to accommodate the complex channel realizations as well.

Author: Mojtaba Vaezi
Publisher: Springer
ISBN: 3319920901
Category : Technology & Engineering
Languages : en
Pages : 692

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Book Description
This book presents comprehensive coverage of current and emerging multiple access, random access, and waveform design techniques for 5G wireless networks and beyond. A definitive reference for researchers in these fields, the book describes recent research from academia, industry, and standardization bodies. The book is an all-encompassing treatment of these areas addressing orthogonal multiple access and waveform design, non-orthogonal multiple access (NOMA) via power, code, and other domains, and orthogonal, non-orthogonal, and grant-free random access. The book builds its foundations on state of the art research papers, measurements, and experimental results from a variety of sources.

Author: Martin Haenggi
Publisher: Now Publishers Inc
ISBN: 1601982984
Category : Wireless communication systems
Languages : en
Pages : 136

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Book Description
Since interference is the main performance-limiting factor in most wireless networks, it is crucial to characterize the interference statistics. The main two determinants of the interference are the network geometry (spatial distribution of concurrently transmitting nodes) and the path loss law (signal attenuation with distance). For certain classes of node distributions, most notably Poisson point processes, and attenuation laws, closed-form results are available, for both the interference itself as well as the signal-to-interference ratios, which determine the network performance. This monograph presents an overview of these results and gives an introduction to the analytical techniques used in their derivation. The node distribution models range from lattices to homogeneous and clustered Poisson models to general motion-invariant ones. The analysis of the more general models requires the use of Palm theory, in particular conditional probability generating functionals, which are briefly introduced in the appendix.