Tutorials - Sunday 7 May, 2005
T1: Uma S. Jha, Qualcom -3G and beyond - 9.30 am - 1.00pm, Sunday 7 May 2006, Grosvenor Room
T2: Mischa Dohler, France Telecom and Hamid Aghvami, King's College London - Cooperative Wireless Communications - 9.30 am - 1.00pm, Sunday 7 May 2006, Mayfair 2 Room
T3: Iain B. Collings, ICT Centre, CSIRO, Australia and Robert W. Heath Jr., The University of Texas at Austin - Adaptive MIMO Techniques and Performance - 2.00 pm - 5.30pm, Sunday 7 May 2006, Grosvenor Room
T4: Lajos Hanzo, Univ. of Southampton - Adaptive OFDM vs MC-CDMA for next-generation wireless systems - 9.30 am - 5.30 pm, Sunday 7 May 2006, Mayfair 3 Room
T1: 3G and Beyond
Uma S. Jha
Grosvenor Room
Abstract
This tutorial covers the evolution of 3rd generation (IMT 2000) cellular standards based on CDMA multiple access scheme. 1st and 2nd generations of cellular standards were voice centric but 3rd generation systems are built data centric and have provisions for multimedia services and features. Next generation of systems would bring convergence of fixed, satellite, and mobile systems and is envisioned to be based on IP core network, which will provide seamless interoperability and desired QoS in cost effective manner irrespective of access schemes and mobility aspects. The lecture delineates capabilities and air interface aspects of standards and emphasizes their capabilities such as capacity, coverage, and throughput. The tutorial emphasizes enhancements of the air interface and network protocols for the evolution of 3GPP and 3GPP2 standards, which successively adds broadband capable downlink and uplink enhancements. The coverage and capacity enhancements of 3G and beyond schemes will be covered with respect to spectral and power efficiency. Other important air interface schemes such as Multi-Carrier (MC), Orthogonal Frequency Division Multiple (OFDM) including link diversity schemes using State Space, beam forming, and MIMO including UWB schemes will be covered as well.
About the Presenter
Dr. Jha has over 26 years of industry experience specializing in the wireless/cellular systems architecture and systems engineering. He is currently Standards Fora Expert at Qualcomm Inc. Prior to this Dr. Jha was Chief Mobility Architect at Boeing Co and Chief Technology Officer (CTO) of Airify Communications, a venture backed wireless router company engaged in building the universal wireless platform unifying the WWAN, WLAN and WPAN wireless/cellular systems with seamless access/connectivity to the mobile users based on price, access and throughput requirements. Uma has served as the Director of Systems Engineering at Morphics Technology, Manager at Philips Semiconductors and Systems Staff Engineer at Conexant to name a few. He received his BSEE from BIT Sindri, MSEE from CSU, Fullerton, Engineer degree from USC, Los Angeles and Ph.D. degree from university of Aalborg, Denmark. Dr. Jha is a senior member of IEEE. Dr. Jha has been invited to deliver tutorials on Cellular Systems, 3G-WCDMA, OFDM and other cellular/wireless topics all around the world. He has served on NesCom IEEE Standards board including the chairperson and panelists for many conferences and has several publications and key patents in the area of wireless/cellular systems. Uma is on the editorial board of Wireless Personal Communication magazine published by Kluwer publication. He has served on many Technical Program committees such as IWWAN-2004, WPMC-2004, ISSSTA-2004, VTC-2004, VTC-2003, VTC-2002, WPMC-2002, WPMC-2001 and ICPWC-2000. He is the General Chair of WPMC 2006 to be held in San Diego, CA, USA.
T2: Distributed Cooperative Communication Networks
- with application to cellular, ad hoc and sensor networks
Mischa Dohler and Hamid Aghvami
Mayfair 2 Room
1. Tutorial Outline
A communication network where at least one information source communicates with at least one information sink via topologically imposed distributed and potentially collaborating relaying nodes, factually creating distributed multiple-input-multiple-output (MIMO) channels, is referred to as a Distributed Cooperative Communication Network. An example of such communication topology is depicted in Figure 1.
Figure 1: Distributed-MIMO relaying network with arbitrary source(s) and sink(s).
The aim of this tutorial is to expose an industrial and academic audience to the challenges related to the analysis, design and deployment of such recently emerged networks at PHY and MAC layers - with particular emphasis on application within cellular, ad hoc and sensor networks.
The logical thread of the tutorial, ranging from channel modelling, capacity analysis, code and transcoder design, resource allocation and scheduling within distributed collaborative networks, proves vital in conveying the most essential issues relating to the design of these networks.
The tutorial is structured into several parts, i.e. application scenarios for distributed communication systems, historical background, channel models, information theoretical bounds, cooperative and distributed transceiver structures, medium access control and elements of cross-layer design.
Scenarios. In the tutorial, we will commence with a plethora of scenarios for which distributed and cooperative communication paradigms are beneficial. For example, cellular extensions yield drastic capacity and range improvements, thereby potentially saving large investment costs. Also, systems, primarily designed to operate in ad hoc mode, benefit from a distributed and cooperative deployment in terms of increased data rates and/or power savings. A further example is the application to sensor networks, where a distributed approach yields significant power savings and also an increased link stability.
Background. We will then continue with a brief summary of the historical developments related to distributed and cooperative networks. Milestone contributions by e.g. Aazhang & Erkip, Laneman & Tse, Kumar & Gupta, Wong & Shea, etc., will be briefly illuminated and their impact onto the contents of the tutorial explained.
Channel Models. Capacity and transceiver performance analysis strongly depends on the underlying channel models. This part of the tutorial hence endeavours to introduce some suitable channel models which correctly reflect the underlying communication scenarios. Parameters of interest are the pathloss, shadowing and fading behaviour, as well as the temporal, frequency and spatial selectivity.
Shannon Capacity. The information theoretical limits of distributed and cooperative systems are then revised in simple and understandable terms without requiring a strong background in information theory. Early contributions by van der Meulen and Cover & Gamal are elaborated, as well as their extensions by Kumar & Gupta. Emphasis will be put onto the ergodic and outage capacities assuming a variety of channels and various degrees of imperfections. This will prove vital in comparing the performance of realistic distributed transceiver structures to the predicted bounds.
Transceiver Design. The capacity bounds can only be approached by appropriate code design, where we will elaborate on the theory of space-time coding from a distributed and cooperative network point of view. To this end, space-time code design criteria are exposed, as well as closed form expressions and upper bounds for the error performance of space-time encoded distributed relaying networks given. The error rates of various distributed transceiver schemes are compared and tendencies explained.
Medium Access Control. Finally, suitable MACs for distributed and cooperative networks will be introduced and analysed. In particular, the advantages and disadvantages of reservation-based and random medium access control protocols will be compared. Furthermore, cross-layer design guidelines will be given, where PHY-layer specific parameters are incorporated into the MAC, so as to optimise throughput and latency.
Final Remarks. General conclusions are drawn and design guidelines given which facilitate a proper deployment of distributed and cooperative communication networks. Important open research topics for academia and industry are suggested. Finally, there will be time for questions.
2. Audience
MIMO and its practical realisation through distributed topologies is a topic gaining in serious momentum in both the academic and industrial communities. This tutorial is tailored to the level of practicing engineers and advanced researchers who are interested in the fundamentals and design of future generation communication networks involving novel non-centralised communication paradigms of distributed and cooperative communication.
3. Required Skills & Background
The attendee is expected to be well equipped in the functioning and understanding of modern communication systems. Knowledge in information theory, channel modelling, space-time code design and medium access control is advantageous but not vital. Since the topic of distributed and cooperative systems is very new, the tutorial presenters will endeavour to make the presentation self-consistent.
About the Presenters
Mischa Dohler (mischa.dohler@francetelecom.com) obtained his MSc degree in Telecommunications from King's College London in 1999, and his Diploma in Electrical Engineering from Dresden University of Technology, Germany, in 2000. He has been lecturer at the Centre for Telecommunications Research, King's College London, until June 2005. He is now in the R&D department of France Télécom working on embedded and future communication systems. Prior to Telecommunications, he studied Physics in Moscow. He has won various competitions in Mathematics and Physics, and participated in the 3rd round of the International Physics Olympics for Germany. He has published numerous research papers and holds six patents. He is a member of the IEEE, has been the Student Representative of the IEEE UKRI Section and a member of the Student Activity Committee of IEEE Region 8. He has also been the London Technology Network Business Fellow for King's College London. In addition to being an experienced lecturer in academia (King's) and industry (Mobile VCE and France Télécom), he has given four international short-courses, two on UMTS and Beyond at WPMC02 & ATAMS02 and two on distributed cooperative systems at VTC Spring 2004 & COST273.
Hamid Aghvami (hamid.aghvami@kcl.ac.uk) is presently the Director of the Centre for Telecommunications Research at King’s. He has published over 300 technical papers and given invited talks all over the world on various aspects of Personal and Mobile Radio Communications as well as giving courses on the subject world wide. He was Visiting Professor at NTT Radio Communication Systems Laboratories in 1990 and Senior Research Fellow at BT Laboratories in 1998-1999. He is currently Executive Advisor to Wireless Facilities Inc., USA and Managing Director of Wireless Multimedia Communications LTD. He leads an active research team working on numerous mobile and personal communications projects for third and fourth generation systems, these projects are supported both by the government and industry. He is a distinguished lecturer and a member of the Board of Governors of the IEEE Communications Society. He has been member, Chairman, Vice-Chairman of the technical programme and organising committees of a large number of international conferences. He is also founder of PIMRC & ICT. He is a fellow of the Royal Academy of Engineering, and fellow member of the IEEE and IEE.
T3: Adaptive MIMO Techniques and Performance
Iain B. Collings, ICT Centre, CSIRO, Australia
Robert W. Heath Jr., The University of Texas at Austin
Matthew R. McKay, University of Sydney
Antonio Forenza, The University of Texas at Austin
Grosvenor Room
Overview
Multiple-input multiple-output (MIMO) antenna systems have recently attracted considerable attention as they offer substantial capacity and performance improvements over single antenna systems without requiring additional power or bandwidth. The initial MIMO research focussed on idealized uncorrelated scattering environments, and spawned an explosion of interest in the area. This tutorial will present an introduction to general MIMO systems, with a particular focus on practical correlated transmission environments. We will discuss a number of low complexity transmission architectures suitable for practical coded MIMO implementations, including the IEEE802.11n and IEEE802.16 standards. The focus of the tutorial will be on examining the potential advantages that can be gained by adapting and switching between different coded MIMO transmission schemes, depending on the quality and correlation in the MIMO channel. A summary of the main analysis techniques will be presented, as well as simulation studies which examine the various system design tradeoffs.
Outline
Introduction
- General MIMO channel model
- Correlated MIMO channels and impact of array configuration
Low Complexity Transmission Schemes
- Bit-Interleaved Coded Modulation for MIMO
- Spatial multiplexing (SM) schemes (ZF, MMSE, ML, VBLAST)
- Beamforming schemes (Instantaneous, Statistical (SB) )
- Space-time block coding (STBC)
Analysis Techniques
- BER expressions (with a case study)
- Multivariate statistics (Wishart matrices, Quadratic forms, ... )
- Moment generating functions (MGF)
Practical Adaptive MIMO Schemes & Performance in Correlated Channels
- Uncoded (SM-STBC switching, multi-mode antenna selection, ... )
- Coded SM-SB switching
- Coded SM-STBC switching
About the Presenters
Iain B. Collings (BE Melb, PhD ANU) has held academic positions at the University of Melbourne and the University of Sydney, where he was an Associate Professor. Since August 2005 he has been the Science Leader in Communications and Signal Processing in the ICT Centre of the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia. He has published over 80 international journal and conference papers, and most recently has focused his research on the capacity and performance of MIMO systems in practical correlated environments. His other research interests include synchronization, channel estimation, equalization, and multi-carrier modulation, for time-varying and frequency-selective channels. Dr Collings currently serves as an Editor for the IEEE Transactions on Wireless Communications, and as a Guest Editor for the EURASIP Journal on Advanced Signal Processing. He is also the Vice Chair of the Technical Program Committee (TPC) for the IEEE Vehicular Technology Conf. (Spring) 2006, and has served on the TPCs of IEEE Int. Conf. on Communications 2005, IEEE Int. Symp. on Spread Spectrum Techniques and Applications 2004, IEEE Vehicular Technology Conf. (Fall) 2003, IEEE GLOBECOM Conf. 2002, and on the Organizing Committees of IEEE Information Theory Workshop 2001, IEEE Int. Symp. on Spread Spectrum Techniques and Applications 2004, and the Australian Communication Theory Workshops 2000-06. He is a Senior Member of the IEEE and a Member of Engineers Australia. For further information on research in progress and associated papers see: www.ee.usyd.edu.au/~iain/
Robert W. Heath Jr. (BS & MS Virginia, PhD Stanford) has held senior positions in both industry and universities. From 1998-99 he was a Senior Member of the Technical Staff at Iospan Wireless Inc, San Jose, CA where he played a key role in the design and implementation of the physical and link layers of the rst commercial MIMO-OFDM communication system. From 1999 to 2001 he served as a Senior Consultant for Iospan Wireless Inc. In 2003 he founded MIMO Wireless Inc. Since January 2002, he has been with the Department of Electrical and Computer Engineering at The University of Texas at Austin where he serves as an Assistant Professor as part of the Wireless Networking and Communications Group. His research interests include interference management in wireless networks, sequence design, and all aspects of MIMO communication including antenna design, practical receiver architectures, limited feedback techniques, and scheduling algorithms. Dr. Heath serves as an Associate Editor for the IEEE Transactions on Communication and the IEEE Transactions on Vehicular Technology.
Matthew R. McKay (BE & BIT QUT) is currently working toward the Ph.D. degree in Electrical Engineering at The University of Sydney. To date, he has published 10 international journal and conference papers in MIMO communications. He received the University Medal for his undergraduate degrees.
Antonio Forenza (BS & MS Politecnico di Torino, Dip Eurécom) is currently working toward the Ph.D. degree in Electrical Engineering at The University of Texas at Austin. To date, he has published 20 international journal and conference papers and standards contributions. In 2001 he interned as systems engineer at Iospan Wireless, Inc. (San Jose, CA), a startup company developing high-speed xed wireless system, based on MIMO-OFDM technology. His main research focus was on link-adaptation and physical layer algorithms design. In the fall 2001 he joined ArrayComm, Inc. (San Jose, CA), where he was involved in the design of smart antenna WCDMA systems. Over the summer 2004 and 2005 he interned as systems research engineer at Samsung Advanced Institute of Technology (SAIT, Suwon, Korea) and Freescale Semiconductor, Inc. (Austin, TX), respectively, designing adaptive MIMO transmission techniques for 3GPP, IEEE 802.11n and IEEE 802.16e standards systems. His research interests include adaptive MIMO techniques, MIMO antenna array design, smart antenna signal processing, precoding techniques for MU-MIMO. Fore more information about his research and related publications visit his web-site: http://www.ece.utexas.edu/~forenza
T4: Adaptive OFDM versus MC-CDMA for next-generation wireless systems - A One-Day Overview
Lajos Hanzo
Mayfair 3 Room
Morning Session: Introduction to OFDM/MC-CDMA
This course is based on an amalgam of [1]-[4]. The introductory part of this two-part overview commences with a rudimentary coverage of the subject, assuming only a modest background in signal processing and wireless communications [1, 3]. Following the fundamental OFDM/MC-CDMA principles we continue by demonstrating that OFDM modems can be efficiently implemented by invoking the Fourier transform or the fast Fourier Transform (FFT). A number of basic OFDM design issues are discussed in an accessible style, including the effects of dispersive fading channels and pilot-based channel estimation, crest-factor aspects and the impact of signal-clipping introduced by finite dynamic-range amplifiers. The effects of finite A/ D conversion accuracy are also considered and a range of synchronisation techniques are highlighted. The first part of the course concludes by considering the performance benefits of adaptive modulation.
Afternoon Session: Advanced OFDM/MC-CDMA Research
2.1 A future-proof MC-CDMA standard framework[4]
Multi-standard operation is an important requirement for the future generations of wireless systems. This overview commences with the portrayal of a versatile broadband multiple access scheme, combining frequency-hopping (FH) with multicarrier DS-CDMA (FH/MC DS-CDMA). The proposed FH/MC DS-CDMA scheme is capable of meeting the requirements of future generations of wireless systems, by supporting backwards compatibility with the existing 2nd-and 3rdgeneration systems, while also introducing more advanced techniques facilitated by the employment of Software Defined Radios (SDR) and efficient adaptive baseband algorithms [1]-[4].
2.2 Adaptive versus Space-time Coded OFDM/MC-CDMA [3]
The presentation continues by demonstrating that Symbol-by-symbol adaptive Orthogonal Frequency Division Multiplex (OFDM) modems have the potential of counteracting the near instantaneous channel quality variations of wireless channels and hence attain an increased throughput in comparison to their fixed-mode counterparts. By contrast, various diversity techniques, such as Rake receivers and space-time coding, mitigate the channel quality variations in their effort to obtain a reduced BER. This overview investigates a combined system constituted by a constant-power adaptive modem employing space-time coded diversity techniques in the context of both OFDM and MC-CDMA. The combined system can be configured to produce a constant uncoded BER and exhibits virtually error free performance, when a turbo convolutional code is concatenated with a space-time block code. It was found that the advantage of the adaptive modem erodes, as the overall diversity-order increases [3].
2.3 PIC-assisted channel estimation for SDMA-aided multiuser OFDM [3]
OFDM systems employing multiple transmit antennas have recently drawn wide interest in the context of both space-time coded-and multi-user space-division multiple access (SDMA) arrangements. A prerequisite for using coherent detection at the receiver is the availability of reliable channel transfer factor estimates. Robust parallel interference cancellation (PIC) assisted decision-directed channel estimation (DDCE) has been shown in the literature to be also applicable to scenarios, where the number of users is in excess of the number of OFDM subcarriers -normalized to the number of Channel Impulse Response (CIR) related taps to be estimated -which imposed a limitation in the context of least-squares assisted DDCE techniques invoked in conjunction with multiple transmit antennas. In this paper we will demonstrate that the Recursive Least-Squares (RLS) algorithm is applicable to optimizing the predictors’ coefficients on a CIR-related tap-by-tap basis. Compared to ’robust’, non-adaptive approaches the proposed solution has the advantage of a potentially lower estimation MSE and a higher resilience to erroneous subcarrier symbol decisions [3]
2.4 Multiuser detection for MC-CDMA [4]
In this part of the presentation a Genetic Algorithm (GA) assisted Multiuser Detector (MUD) designed for MC-CDMA is investigated in the context of frequency selective Rayleigh fading channels. The achievable BER performance of the GA assisted MUD as well as its near-far resistance are investigated for a range of parameter values. It is shown that the proposed GA assisted MUD is capable of significantly reducing the complexity in comparison to that of Verdu’s optimum MUD. For example, when supporting K = 20 users, the number of likelihood function evaluations is reduced by a factor of 1300 [4]
This overview of next-generation wireless enabling techniques will be concluded with a future-proof new design paradigm, highlighting a range of open problems for the radical researcher.
References
[1] L. Hanzo, S-X. Ng, W.T. Webb, T. Keller: Quadrature Amplitude Modulation: From Basics to Adaptive Trellis-Coded, Turbo-Equalised and Space-Time Coded OFDM, CDMA and MC-CDMA Systems, IEEE Press-John Wiley, 2nd edition, Sept. 2004 1105 pages.
[2] L. Hanzo, T.H. Liew, B.L. Yeap: Turbo Coding, Turbo Equalisation and Space-Time Coding, John Wiley, August 2002, ISBN 0-47084726-3, p 766
[3] L. Hanzo, M. Münster, B.J. Choi and T. Keller: OFDM and MC-CDMA for Broadband Multi-user Communications, WLANs and Broadcasting, John Wiley-IEEE Press, May 2003, 1010 pages [4] L. Hanzo, L-L. Yang, E-L. Kuan and K. Yen: Single-and Multi-Carrier CDMA: Multi-User Detection, Space-Time Spreading, Synchronisation, Standards and Networking, IEEE Press-John Wiley, June 2003, 1060 pages
About the Presenter
During his 28-year career Lajos Hanzo, FRAEng, DSc, FIEEE, FIEE has held various academic and research positions in Hungary, Germany and the UK. Since 1986 he has been with the University of Southampton, where he holds the Chair of Telecommunications. Over the years he has co-authored 11 books on mobile radio communications, published in excess of 500 research papers. Lajos has also been awarded a number of distinctions and he is an IEEE Distinguished Lecturer of both the Communications and the Vehicular Technology Society. For further information on research in progress and for associated papers and book chapters please refer to http://www-mobile.ecs.soton.ac.uk