Multiple antenna (MIMO) techniques have been shown to significantly improve the performance of a wireless link. While these techniques are relatively well understood at the link level, the impact of interference and different performance measures at the system level necessitate fundamentally new investigations. The purpose of this tutorial is to explore the performance tradeoffs of MIMO in wireless systems consisting of multiple simultaneous MIMO links found in emerging next-generation wireless networks. The tutorial would be based on our most up-to-date understanding of the theoretical system-level traits of MIMO systems as applied to different types of wireless networks. Beyond providing a system-level perspective of MIMO, this tutorial also addresses system simulation methodologies for MIMO networks and shows how the discussed principles are already penetrating the design and analysis of next-generation wireless standards.
We feel that this information, which to the best of our knowledge has not been presented in a tutorial format by anyone else, could potentially appeal to a broad audience that includes anyone interested in state-of-the-art 4G wireless system design at the MAC/physical layer. We also feel that we are uniquely qualified to present this information because of our nearly two decades of combined experience in MIMO research, development, and standards.
A tentative outline of the tutorial follows.
1. Introduction to MIMO.
Review basic principles and the fundamental theory of the MIMO link. Show the gains achievable using spatial multiplexing and compare with diversity-only techniques.
2. MIMO system capacity
Discuss fundamental MIMO system-level capacity based on the achievable rate region of the Gaussian broadcast channel. Show how this capacity can be achieved using dirty paper coding techniques and show how the capacity scales with the number of antennas and users.
3. Practical physical-layer techniques for MIMO systems
Introduce space-division multiple access (SDMA) and present sectorization and beamforming as the two fundamental SDMA techniques. Introduce the MIMO system model for a downlink cellular network and study the performance tradeoffs between SDMA and spatial multiplexing in terms of cell throughput and user peak rate metrics. Show how these practical techniques fare against theoretical optimal performance.
4. Interaction with higher protocol layers.
Consider the impact of cross-layer techniques including multiuser scheduling and opportunistic beamforming. The interplay of the PHY and the MAC layer is addressed, as it plays a key role in system-level MIMO.
5. Application to 4G systems.
Discuss application of the MIMO techniques for 4G systems including 3GPP LTE, 3GPP2 RevC, WiMax, and 802.20. Investigate the feasibility of achieving stated performance goals.
Dr. Howard C. Huang
Dr. Howard Huang was born in Houston, Texas in 1969. He received a BS in electrical engineering from Rice University in 1991 and a Ph.D. in electrical engineering from Princeton University in 1995. Since then, he has been a researcher in the Wireless Communications Research Department at Bell Labs, Lucent Technologies. In 2003, he was named as a Distinguished Member of Technical Staff. Dr. Huang has studied multiple antenna techniques for a variety of wireless networks including the AirLoop fixed-wireless network, IS-95, cdma2000, and UMTS HSDPA. He has been a leading proponent of MIMO technologies in 3GPP UMTS standards, representing Lucent when MIMO was first proposed in 2000 and serving as the rapporteur for the MIMO work item from 2002 onward. He was also a member of the team that developed the unified MIMO spatial channel model for 3GPP and 3GPP2 standards groups. Dr. Huang's research interests include MIMO system design, coordinated networks, and multiuser detection, and he is a Senior Member of the IEEE.
Dr. Constantinos B. Papadias
Dr. Constantinos B. Papadias is an Associate Professor at Athens Information Technology in Athens, Greece, where he was born in 1969. He received the Diploma of Electrical Engineering from the National Technical University of Athens (NTUA) in 1991 and the Doctorate degree in Signal Processing (highest honors) from the Ecole Nationale Supérieure des Télécommunications (ENST), Paris, France, in 1995. In 1995, he joined the Information Systems Laboratory, Stanford University, Stanford, CA, as Post-Doctoral Researcher, working in the Smart Antennas Research Group. In November 1997 he joined the Wireless Research Laboratory of Bell Labs, Lucent Technologies, Holmdel, NJ, as Member of Technical Staff and was later promoted to Technical Manager. From 2004 to 2005 he was an adjunct Associate Professor at Columbia University. He is currently on leave from Lucent. He has authored over 100 papers, book chapters, patents and standards contributions on these topics and has received various awards for his work. He is involved in the organization of several technical conferences and special issues and is the co-editor of an upcoming book on MIMO systems. He also participates in several research projects funded by the European Commission and DARPA and has represented Lucent Technologies at the steering board of the Wireless World Research Forum. He served as an Associate Editor for the IEEE Transactions on Signal Processing and is currently a member of the Signal Processing for Communications Technical Committee of the IEEE Signal Processing Society. Dr. Papadias is a Senior Member of the IEEE and a member of the Technical Chamber of Greece.