A universal space-time architecture for multiple-antenna aided systems

In this tutorial, we first review the family of conventional multiple-antenna techniques, and then we provide a general overview of the recent concept of the powerful Multiple-Input Multiple-Output (MIMO) family based on a universal Space-Time Shift Keying (STSK) philosophy. When appropriately configured, the proposed STSK scheme has the potential of outperforming conventional MIMO arrangements

EXIT charts for system design and analysis

Near-capacity performance may be achieved with the aid of iterative decoding, where extrinsic soft information is exchanged between the constituent decoders in order to improve the attainable system performance. Extrinsic information Transfer (EXIT) charts constitute a powerful semi-analytical tool used for analysing and designing iteratively decoded systems. In this tutorial, we commence by providing a rudimentary overview of the iterative decoding principle and the concept of soft information exchange. We then elaborate on the concept of EXIT charts using three iteratively decoded prototype systems as design examples. We conclude by illustrating further applications of EXIT charts, including near-capacity designs, the concept of irregular codes and the design of modulation schemes

Design and analysis of space-time block and trellis coding schemes for single-band UWB communications systems

Ultra Wide-Band (UWB) technology has recently attracted much research interest due to its appealing features in short-range mobile communications. These features include high-data rates, low power consumption, multiple-access communications and precise positioning capabilities. Space-Time Coding (STC) techniques, such as block coding and trellis coding, are known to be simple and practical ways to increase both the spectral efficiency and the capacity in wireless communications. The the- sis aims at designing robust and efficient space-time coding schemes well adapted to single-band UWB signalling. Thus, this work incorporates a fine analysis of a stan- dard Single Input Single Output (SISO) single-band UWB system, scrutinising every important aspect of this system including transceiver structure, channel modelling, multiple-access techniques and detection process. Research also leads to the deriva- tion of a novel closed-form approximation for the average probability of bit-error for single-band UWB systems. This in-depth study highlights drawbacks inherent to UWB systems such as time-jitter effects or rake-receiver complexity and proposes schemes that benefit from spatial diversity to mitigate these problems. Thus, the thesis concentrates on the design of new multiple-antenna space-time coding systems tailored for UWB communications. As a result, this work derives and generates gen- eralised full-rate space-time block codes based on orthogonal pulses to capture both spatial and multipath diversities. Space-time trellis coded modulation is then revis- ited to further improve the spectral efficiency limit and to deliver the high-data rates promised by UWB technology. A new version of space-time trellis coding is developed for the peculiar UWB signalling structure. Finally, thanks to a novel closed-form ap- proximation, a theoretical comparison is undertaken between any SISO-UWB system and the multiple antenna UWB systems proposed in this thesis. The results clearly underline the impact of STC on a single-band UWB system in terms of enhanced robustness against timing-jitter effects, higher spectral efficiency and capacity im- provement. These advantages are finally confirmed through the numerical evaluation of the error-rate performance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Location-aware and Cooperative Communication in an OFDM based Ultra-wideband Radio System

Die auf dem orthogonalen Frequenzmultiplex (OFDM, Orthogonal Frequency Division Multiplexing) basierende Ultra-Breitband-(UWB, Ultra-wideband) Technologie stellt eine verheißungsvolle Technologie dar, um hohe Datenübertragungsraten und Lokalisierungs- und deren Tracking-Anwendungen zu realisieren. Im Gegensatz zu anderen Systemen ist die Reichweite von OFDM UWB Systemen durch eine strenge Regulierung sehr stark begrenzt. Darüber hinaus ist die Lokalisierung nicht zufriedenstellend. Damit sind bereits die beiden größten Nachteile im Bezug auf bestehende OFDM UWB System benannt. Die Motivation und Hauptaufgabe dieser Arbeit ist damit die Lösung der eben genannten Nachteile. Es wird ein OFDM UWB System vorgestellt, das Space Frequency Block Coding (SFBC) und FFH OFDM miteinander verbindet. Dieses vereinte System wertet die räumliche und frequentielle Diversität eines OFDM-Symbols aus und zeigt dabei eine hohe Güte in der Punkt-zu-Punkt Kommunikation. Beim Design von kooperativen UWB-Systemen wird ein AF-(Amplify-and-Forward) basiertes echtzeitfähriges SFBC-TFC (Time Frequency Code) Protokoll vorgestellt. In Kombination mit den oben genannten Strategien, kann eine Erhöhung in den Reichweite von OFDM UWB Systemen erreicht werden. In den Ausführungen zur Ortung anhand von OFDM UWB Signalen wird ein Algorithmus entwickelt, der aufgrund einer Kanalschätzung eine Minimierung des Phasenversatzes zwischen geschätztem und realem Kanal im Frequenzbereich durchführt. Diese Minimierung erwirkt eine Unterdrückung der Energie am Ende der Kanalimpulsantwort (CIR, Channel Impulse Response) im Zeitbereich. Zum Zweck der einfachen Implementierbarkeit wird das RTT (Round-Trip-Time) Messprotokoll in WiMedia UWB Systemen dahingehend verändert, dass das mobile Gerät keine Minimierung vornimmt. Es leitet seine Informationen an das mit ihm Kommunizierende, stationäre Gerät weiter, das direkt den gesamten Zeitversatz innerhalb des RTT berechnet. Der vorgeschlagene Algorithmus und das vorgeschlagene Protokoll haben ein besseres Ortungsvermögen als bekannte UWB Lokalisierungsprozeduren und bedürfen nur etwas zusätzlicher Berechnungsleistung. Diese Arbeit zeigt, dass Systeme mit hohen Datenraten wie OFDM UWB auch eine gute Lokalisierungsgenauigkeit erreichen können. Zusätzlich ist die Schwachstelle einer limitierten Reichweite ebenso kompensiert worden. Diese Erweiterungen dienen der Entwicklung von nützlichen UWB-Applikationen und sichern den Anteil der OFDM UWB Technik im Markt der drahtlosen Kommunikationssysteme der Zukunft.The Orthogonal Frequency Division Multiplexing (OFDM) based Ultra-wideband (UWB) is one of the most promising technologies for high data rate transmission and localization and tracking applications. However, the restricted transmit power causes a shorter communication range compared to other indoor radio systems. In addition, the ranging functionality is still not well supported by the current OFDM based UWB technology. These two drawbacks are the main disadvantages existing in the current OFDM UWB systems. To get rid of the two drawbacks, is the motivation and main task of this thesis. Within the scope of this thesis, a joint design of Space Frequency Block Coding (SFBC) with Fast Frequency Hopping (FFH) OFDM scheme is investigated in a multiple antenna OFDM UWB system. The joint scheme is able to exploit spatial and frequency domain diversity within one OFDM symbol, and can improve the data transmission quality in point-to-point communication. To the cooperative communication in UWB systems, an Amplify-and-Forward (AF) based distributed SFBC-TFC (Time Frequency Code) protocol is designed. In combination with the aforementioned strategies an increase in the communication range is achieved. Within the scope of this thesis, accurate ranging schemes for the OFDM UWB systems are designed. Fine ToA detection method based on the estimated channel is developed. The fine ToA is estimated by minimizing the accumulated energy of the tail taps of the estimated Channel Impulse Response (CIR). For the purpose of a feasible implementation, the Round-Trip-Time (RTT) measurement protocol in [WiM09] is modified in a way that the complicated computational tasks are burden onto the powerful device. The proposed fine ToA detection method and modified RTT protocol provides an accurate ranging capability and ensures feasible implementation to the MB-OFDM UWB systems. In carrying out this scheme, only some computational tasks are needed, no extra hardware support is required. It is shown in this thesis, OFDM UWB systems with very high data rate transmission and good ranging capability could be achieved, and the weakness of limited communication range is also compensated. These improvements will cause the rise of more valuable UWB applications for customers and ensures a bright future for the OFDM UWB technique

Self-concatenated coding for wireless communication systems

In this thesis, we have explored self-concatenated coding schemes that are designed for transmission over Additive White Gaussian Noise (AWGN) and uncorrelated Rayleigh fading channels. We designed both the symbol-based Self-ConcatenatedCodes considered using Trellis Coded Modulation (SECTCM) and bit-based Self- Concatenated Convolutional Codes (SECCC) using a Recursive Systematic Convolutional (RSC) encoder as constituent codes, respectively. The design of these codes was carried out with the aid of Extrinsic Information Transfer (EXIT) charts. The EXIT chart based design has been found an efficient tool in finding the decoding convergence threshold of the constituent codes. Additionally, in order to recover the information loss imposed by employing binary rather than non-binary schemes, a soft decision demapper was introduced in order to exchange extrinsic information withthe SECCC decoder. To analyse this information exchange 3D-EXIT chart analysis was invoked for visualizing the extrinsic information exchange between the proposed Iteratively Decoding aided SECCC and soft-decision demapper (SECCC-ID). Some of the proposed SECTCM, SECCC and SECCC-ID schemes perform within about 1 dB from the AWGN and Rayleigh fading channels’ capacity. A union bound analysis of SECCC codes was carried out to find the corresponding Bit Error Ratio (BER) floors. The union bound of SECCCs was derived for communications over both AWGN and uncorrelated Rayleigh fading channels, based on a novel interleaver concept.Application of SECCCs in both UltraWideBand (UWB) and state-of-the-art video-telephone schemes demonstrated its practical benefits.In order to further exploit the benefits of the low complexity design offered by SECCCs we explored their application in a distributed coding scheme designed for cooperative communications, where iterative detection is employed by exchanging extrinsic information between the decoders of SECCC and RSC at the destination. In the first transmission period of cooperation, the relay receives the potentially erroneous data and attempts to recover the information. The recovered information is then re-encoded at the relay using an RSC encoder. In the second transmission period this information is then retransmitted to the destination. The resultant symbols transmitted from the source and relay nodes can be viewed as the coded symbols of a three-component parallel-concatenated encoder. At the destination a Distributed Binary Self-Concatenated Coding scheme using Iterative Decoding (DSECCC-ID) was employed, where the two decoders (SECCC and RSC) exchange their extrinsic information. It was shown that the DSECCC-ID is a low-complexity scheme, yet capable of approaching the Discrete-input Continuous-output Memoryless Channels’s (DCMC) capacity.Finally, we considered coding schemes designed for two nodes communicating with each other with the aid of a relay node, where the relay receives information from the two nodes in the first transmission period. At the relay node we combine a powerful Superposition Coding (SPC) scheme with SECCC. It is assumed that decoding errors may be encountered at the relay node. The relay node then broadcasts this information in the second transmission period after re-encoding it, again, using a SECCC encoder. At the destination, the amalgamated block of Successive Interference Cancellation (SIC) scheme combined with SECCC then detects and decodes the signal either with or without the aid of a priori information. Our simulation results demonstrate that the proposed scheme is capable of reliably operating at a low BER for transmission over both AWGN and uncorrelated Rayleigh fading channels. We compare the proposed scheme’s performance to a direct transmission link between the two sources having the same throughput

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Initial Synchronisation in the Multiple-Input Multiple-Output Aided Single- and Multi-Carrier DS-CDMA as well as DS-UWB Downlink

In this thesis, we propose and investigate code acquisition schemes employing both colocated and cooperative Multiple Input/Multiple Output (MIMO) aided Single-Carrier (SC) and Multi-Carrier (MC) Code Division Multiple Access (CDMA) DownLink (DL) schemes. We study their characteristics and performance in terms of both Non-Coherent (NC) and Differentially Coherent (DC) MIMO scenarios. Furthermore, we also propose iterative code acquisition schemes for the Direct Sequence-Ultra WideBand (DS-UWB) DL. There is a paucity of code acquisition techniques designed for transmit diversity aided systems. Moreover, there are no in-depth studies representing the fundamental characteristics of code acquisition schemes employing both co-located and cooperative MIMOs. Hence we investigate both NC and DC code acquisition schemes in the co-located and cooperative MIMO aided SC and MC DS-CDMA DL, when communicating over spatially uncorrelated Rayleigh channels. The issues of NC initial and post-initial acquisition schemes as well as DC schemes are studied as a function of the number of co-located antennas by quantifying the attainable correct detection probability and mean acquisition time performances. The research of DS-UWB systems has recently attracted a significant interest in both the academic and industrial community. In the DS-UWB DL, initial acquisition is required for both coarse timing as well as code phase alignment. Both of these constitute a challenging problem owing to the extremely short chip-duration of UWB systems. This leads to a huge acquisition search space size, which is represented as the product of the number of legitimate code phases in the uncertainty region of the PN code and the number of legitimate signalling pulse positions. Therefore the benefits of the iterative code acquisition schemes are analysed in terms of the achievable correct detection probability and mean acquisition time performances. Hence we significantly reduce the search space size with the aid of a Tanner graph based Message Passing (MP) technique, which is combined with the employment of beneficially selected generator polynomials, multiple receive antennas and appropriately designed multiple-component decoders. Finally, we characterise a range of two-stage iterative acquisition schemes employing iterative MP designed for a multiple receive antenna assisted DS-UWB DL scenario

Journal of Telecommunications and Information Technology, 2021, nr 1

kwartalni

Initial synchronisation in the multiple-input multiple-output aided single- and multi-carrier DS-CDMA as well as DS-UWB downlink

In this thesis, we propose and investigate code acquisition schemes employing both colocated and cooperative Multiple Input/Multiple Output (MIMO) aided Single-Carrier (SC) and Multi-Carrier (MC) Code Division Multiple Access (CDMA) DownLink (DL) schemes. We study their characteristics and performance in terms of both Non-Coherent (NC) and Differentially Coherent (DC) MIMO scenarios. Furthermore, we also propose iterative code acquisition schemes for the Direct Sequence-Ultra WideBand (DS-UWB) DL. There is a paucity of code acquisition techniques designed for transmit diversity aided systems. Moreover, there are no in-depth studies representing the fundamental characteristics of code acquisition schemes employing both co-located and cooperative MIMOs. Hence we investigate both NC and DC code acquisition schemes in the co-located and cooperative MIMO aided SC and MC DS-CDMA DL, when communicating over spatially uncorrelated Rayleigh channels. The issues of NC initial and post-initial acquisition schemes as well as DC schemes are studied as a function of the number of co-located antennas by quantifying the attainable correct detection probability and mean acquisition time performances. The research of DS-UWB systems has recently attracted a significant interest in both the academic and industrial community. In the DS-UWB DL, initial acquisition is required for both coarse timing as well as code phase alignment. Both of these constitute a challenging problem owing to the extremely short chip-duration of UWB systems. This leads to a huge acquisition search space size, which is represented as the product of the number of legitimate code phases in the uncertainty region of the PN code and the number of legitimate signalling pulse positions. Therefore the benefits of the iterative code acquisition schemes are analysed in terms of the achievable correct detection probability and mean acquisition time performances. Hence we significantly reduce the search space size with the aid of a Tanner graph based Message Passing (MP) technique, which is combined with the employment of beneficially selected generator polynomials, multiple receive antennas and appropriately designed multiple-component decoders. Finally, we characterise a range of two-stage iterative acquisition schemes employing iterative MP designed for a multiple receive antenna assisted DS-UWB DL scenario.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Performance analysis of space-time block coded systems with channel estimation

Ph.DDOCTOR OF PHILOSOPH