IST-2000-30148 I-METRA: D3.1 Design, analysis and selection of suitable algorithms

This deliverable contains a description of the space-time coding algorithms to be simulated within the I-METRA project. Different families of algorithms have been selected and described in this document with the objective of evaluating their performance. One of the main objectives of the I-METRA project is to impact into the current standardisation efforts related to the introduction of Multiple Input Multiple Output (MIMO) configurations into the High Speed Downlink and Uplink Packet Access concepts of UMTS (HSDPA and HSUPA). This required a review of the current specifications for these systems and the analysis of the impact of the potential incorporation of the selected MIMO schemes.Preprin

IST-2000-30148 I-METRA: D4 Performance evaluation

This document considers the performance of multiantenna transmit/receive techniques in high-speed downlink and uplink packet access. The evaluation is done using both link and system level simulations by taking into account link adaptation and packet retransmissions. The document is based on the initial studies carried out in deliverables D3.1 and D3.2.Preprin

Soft-demodulation of QPSK and 16-QAM for turbo coded WCDMA mobile communication systems

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Iterative multiuser receivers for coded DS-CDMA systems

The introduction of cellular wireless systems in the 1980s has resulted in a continuous and growing demand for personal communication services. This demand has made larger capacity systems necessary. With the interest from both the research community and industry in wireless code-division multiple-access (CDMA) systems, the application of multiuser detection (MUD) techniques to wireless systems is becoming increasingly important. MUD is an important area of interest to help obtain the significant increase in capacity needed for future wireless services. The standardisation of direct-sequence CDMA (DS-CDMA) systems in the third generation of mobile communication systems has raised even more interest in exploiting the capabilities and capacity of this type of technology. However, the conventional DS-CDMA system has the major problem of multiple-access interference (MAI). The MAI is unavoidable because receivers deal with information which is transmitted not by a single source but by several uncoordinated and geographically separated sources. As a result, the capacity of these systems is inherently interference limited by other users. To overcome these limitations, MUD emerges as a promising approach to increase the system capacity. This thesis addresses the problem of improving the downlink capacity of a coded DS-CDMA system with the use of MUD techniques at the mobile terminal receiver. The optimum multiuser receiver scheme is far too computational intensive for practical use. Therefore, the aim of this thesis is to investigate sub-optimal multiuser receiver schemes that can exploit the advantages of MUD but also simplify its implementation. The attention is primarily focused on iterative MUD receiver schemes which apply the turbo multiuser detection principle. Essentially this principle consists of an iterative exchange of extrinsic information among the receiver modules to achieve improved performance. In this thesis, the implementation of an iterative receiver based on a linear MUD technique and a cancellation scheme over an additive white Gaussian noise (AWGN) channel is first proposed and analysed. The interference analysis shows that good performance is achieved using a lowcomplexity receiver structure. In more realistic mobile channels, however, this type of receiver suffers from the presence of higher levels of interference resulting in poor receiver performance. The reason for this is that in such scenarios the desired signals are no longer linearly separable. Therefore, non-linear detection techniques are required to provide better performance. With this purpose, a hybrid iterative multiuser receiver is investigated for the case of a stationary multipath channel. The incorporation of antenna arrays is an effective and practical technique to provide a significant capacity gain over conventional single-antenna systems. In this context, a novel space-time iterative multiuser receiver is proposed which achieves a large improvement in spectral efficiency and performance over multipath fading channels. In addition, it is shown that this architecture can be implemented without a prohibitive complexity cost. The exploitation of the iterative principle can be used to approach the capacity bounds of a coded DS-CDMA system. Using the Shannon’s sphere packing bound, a comparison is presented to illustrate how closely a practical system can approach the theoretical limits of system performance

Linear space-time modulation in multiple-antenna channels

This thesis develops linear space–time modulation techniques for (multi-antenna) multi-input multi-output (MIMO) and multiple-input single-output (MISO) wireless channels. Transmission methods tailored for such channels have recently emerged in a number of current and upcoming standards, in particular in 3G and "beyond 3G" wireless systems. Here, these transmission concepts are approached primarily from a signal processing perspective. The introduction part of the thesis describes the transmit diversity concepts included in the WCDMA and cdma2000 standards or standard discussions, as well as promising new transmission methods for MIMO and MISO channels, crucial for future high data-rate systems. A number of techniques developed herein have been adopted in the 3G standards, or are currently being proposed for such standards, with the target of improving data rates, signal quality, capacity or system flexibility. The thesis adopts a model involving matrix-valued modulation alphabets, with different dimensions usually defined over space and time. The symbol matrix is formed as a linear combination of symbols, and the space-dimension is realized by using multiple transmit and receive antennas. Many of the transceiver concepts and modulation methods developed herein provide both spatial multiplexing gain and diversity gain. For example, full-diversity full-rate schemes are proposed where the symbol rate equals the number of transmit antennas. The modulation methods are developed for open-loop transmission. Moreover, the thesis proposes related closed-loop transmission methods, where space–time modulation is combined either with automatic retransmission or multiuser scheduling.reviewe

A Framework Design for the Next-Generation Radio Access System

Extensive use of the Internet and huge demands for multimedia services via portable devices require the development of packet-based radio access systems with high transmission efficiency. Advanced radio transmission technologies have recently been proposed to achieve this challenging task. However, few researches have been reported on the design of an integrated system that can efficiently exploit the advantages of these transmission technologies. This paper considers the design of a packet-based cellular system for next-generation radio access. We propose a novel system framework that can incorporate various advanced transmission technologies such as link adaptation, opportunistic packet scheduling, channel coding, and multiantenna techniques. For efficient use of these technologies together, we first investigate the interoperability between these technologies by proposing a so-called cause and effect analysis. Based on this investigation, we design a differentiated-segments-based orthogonal frequency-division multiplexing system, called DiffSeg, to accommodate heterogeneous operating conditions in a seamless manner. Simulation results show that the proposed DiffSeg system can provide a nearly optimum performance with flexible configuration in a wide range of wireless channel conditions

Initial synchronisation of wideband and UWB direct sequence systems: single- and multiple-antenna aided solutions

This survey guides the reader through the open literature on the principle of initial synchronisation in single-antenna-assisted single- and multi-carrier Code Division Multiple Access (CDMA) as well as Direct Sequence-Ultra WideBand (DS-UWB) systems, with special emphasis on the DownLink (DL). There is a paucity of up-to-date surveys and review articles on initial synchronization solutions for MIMO-aided and cooperative systems - even though there is a plethora of papers on both MIMOs and on cooperative systems, which assume perfect synchronization. Hence this paper aims to ?ll the related gap in the literature