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Author: Daniel Jeffrey Carey Publisher: ISBN: Category : Asynchronous transfer mode Languages : en Pages : 140
Book Description
Most standardisation bodies have based their 3G cellular systems on DS-CDMA (W-CDMA, UMTS, cdma2000). With 4G systems desiring improved services and quality of service standards, this thesis investigates multicarrier CDMA (MC-CDMA) as a genuine air interface candidate. A statistical model of the total MAI power incurred over the uplink channel is shown to be very accurately characterised by the Nakagami-m distribution for both asynchronous DS-CDMA and MC-CDMA techniques. Two new CDMA schemes, DF/DS-CDMA and DF/MC-CDMA, are proposed based on the dual-frequency (DF) switching technique introduced in this thesis. These proposed DF schemes offer substantial MAI reduction upon asynchronous reception and clearly outperform (MAI & BER) the standard DS-CDMA and MC-CDMA systems, however, additional bandwidth is required.
Author: Daniel Jeffrey Carey Publisher: ISBN: Category : Asynchronous transfer mode Languages : en Pages : 140
Book Description
Most standardisation bodies have based their 3G cellular systems on DS-CDMA (W-CDMA, UMTS, cdma2000). With 4G systems desiring improved services and quality of service standards, this thesis investigates multicarrier CDMA (MC-CDMA) as a genuine air interface candidate. A statistical model of the total MAI power incurred over the uplink channel is shown to be very accurately characterised by the Nakagami-m distribution for both asynchronous DS-CDMA and MC-CDMA techniques. Two new CDMA schemes, DF/DS-CDMA and DF/MC-CDMA, are proposed based on the dual-frequency (DF) switching technique introduced in this thesis. These proposed DF schemes offer substantial MAI reduction upon asynchronous reception and clearly outperform (MAI & BER) the standard DS-CDMA and MC-CDMA systems, however, additional bandwidth is required.
Author: Paulo Silva Publisher: CRC Press ISBN: 1000794156 Category : Science Languages : en Pages : 264
Book Description
Future broadband wireless communication systems are expected to be able to offer new and powerful services enabling fast transmission rates of several tens of Mbit/s. This is an ambitious challenge especially for mobile communication systems since these systems should be able to cope with severely time dispersive channels, associated to the signal multipath propagation. Moreover, these systems should have high spectral and power efficiencies, as well as high capacity and flexibility. Spread spectrum techniques, particularly coded division multiple access (CDMA) techniques allow high capacity and flexibility, continuous transmission requiring low-peak power requirements for the amplifiers, as well as some robustness against fading and time-dispersion effects associated with the multipath propagation. When employed in prefix assisted (PA) block transmission schemes combined with frequency-domain receiver implementations they become especially interesting for broadband wireless systems. In Frequency-Domain Multiuser Detection for CDMA Systems the use of PA block transmission is considered in the context of both DS (Direct Sequence) and MC (Multicarrier) CDMA schemes. The main goal is the study of frequency-domain multiuser detection techniques with iterative signal detection/decoding techniques, also in combination with estimation and cancelation of nonlinear distortion effects. The receiver structures are suitable to scenarios with high interference levels and strongly time-dispersive channels.
Author: Luca Fanucci Publisher: Springer Science & Business Media ISBN: 1402025378 Category : Technology & Engineering Languages : en Pages : 284
Book Description
An Experimental Approach to CDMA and Interference Mitigation was written with the admittedly ambitious intent of filling the gap between communication theory and VLSI implementation, and thus to provide a more general/theoretical approach to the design, development, and testing of a CDMA receiver. As a consequence, the concepts and techniques that are presented turn out to be applicable to a more general kind of digital wireless modems in terms of receiver architecture design and implementation. As the reader will easily find out, the subject of digital modem design and implementation is addressed in the book starting from a theoretical approach (supported by proper bibliographic references), and is followed by application issues, with reference to an ESA experiment assumed as a case study. A complete design flow, from specification to implementation, including testing and final verification is then presented. This leads the reader step-by-step to a thorough understanding of CDMA transmission and detection, and constitutes a practical guidance for the design of VLSI wireless mobile terminals.
Author: Hui Liu Publisher: Artech House Publishers ISBN: Category : Computers Languages : en Pages : 224
Book Description
Dramatically improve CDMA system performance using this new book, which contains the most comprehensive description of signal processing treatments for wideband CDMA. Based upon the author's in-depth research of key CDMA signal processing issues, you get solutions to problems such as diversity combining, multiuser detection, channel estimation, and carrier synchronization.
Author: Ramesh Annavajjala Publisher: ISBN: Category : Languages : en Pages : 145
Book Description
Some of the challenges in the design of next generation wireless systems are providing high data rate multimedia services, increasing user capacity, improving reliability and range, terminal mobility, robustness to interference, limited spectrum availability, and transmission power constraints. The approaches that we take in this dissertation to address some of the aforementioned issues are cross-layer design and user cooperation. In the first part of the dissertation, on a wideband CDMA channel with a finite transmission bandwidth constraint, we consider the problem of optimal bandwidth allocation for source coding, channel coding and spread-spectrum modulation. For analytical tractability, we assume a memoryless Gaussian source with an optimum quantizer, a convolutional encoder with a soft-decision decoder, and a spread spectrum modulator with random spreading codes and a RAKE receiver. In the presence of both multiple access interference (MAI) and narrowband interference (NBI), for frequency-selective Nakagami fading channels, we derive upper and lower bounds on the end-to-end average source distortion. Since an exact expression for the average distortion is difficult to derive, we seek to obtain the three-tuple (i.e., source coding rate, channel coding rate, and spreading factor) that optimizes the upper and lower bounds on the average distortion. Under various channel conditions and interference levels, we numerically computed the optimum three-tuple, and verify the accuracy with system-level simulations. For small values of spreading factor, we show that the system performance is hurt by the self-interference of the user-of-interest, thus cautioning against aggressive channel coding. Since a multi-carrier DS-CDMA (or, simply MC-CDMA) system is more robust to NBI, we propose to employ an MC-CDMA system to improve the distortion performance on channels with severe NBI. For a fixed channel code rate, we then quantify the tradeoff between source coding and spreading for an MC-CDMA system. In the second part of the dissertation, we consider a parallel relay channel wherein the relay nodes help the source transmissions to provide improved reliability at the destination. With multiple relay nodes, we design and analyze robust noncoherent amplify-and forward receivers for use on rapidly varying Rayleigh fading channels with unknown instantaneous channel knowledge. Next, with a sum power constraint, we consider the problem of optimal transmit power allocation when only statistical knowledge, in terms of the average fading power, of the channel is available at the transmitting nodes. We quantify the improvements in both outage probability performance and asymptotic cooperation gain of various relaying protocols with optimal power allocation.
Author: Khaled Fazel Publisher: Springer Science & Business Media ISBN: 9781402044359 Category : Computers Languages : en Pages : 528
Book Description
The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side have motivated many researchers to investigate the combination of both techniques since 1993. This combination known as multi-carrier spread spectrum (MC-SS) benefits from the advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: The spreading is performed as direct sequence spread spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers are employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users’ signals can be performed in the code domain. MC-SS systems can perform the spreading in frequency direction, which allows for simple signal detection strategies. Since 1993, MC-SS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA. The aim of Multi-Carrier Spread-Spectrum is to edit the ensemble of the newest contributions and research results in this new field that have been presented during the 5th International Workshop on Multi-Carrier Spread-Spectrum (MC-SS 2005), held in Oberpfaffenhofen, Germany.
Author: Daniel Jeffrey Carey
Author: Daniel Jeffrey Carey
Author: Xuan Li
Author: Paulo Silva
Author: 
Author: Luca Fanucci
Author: Weiping Xu
Author: Banisrekha Mohd Nawi
Author: Hui Liu
Author: Ramesh Annavajjala
Author: Khaled Fazel