Exploiting Antenna Arrays for Next Generation Wireless Communications Systems

Prof. Lee Swindlehurst (Electrical Engineering and Computer Science, University of California Irvine) is a Hans Fischer Senior Fellow collaborating with TUM professors Josef A. Nossek (Circuit Theory and Signal Processing) and Wolfgang Utschick (Signal Processing Methods). It is estimated that there are more wireless devices in use today than people on the planet. This explosive growth has created a capacity crisis for mobile operators, and the impact of this crisis goes well beyond the inconveniences experienced by casual users. Wireless communications is now a commodity, like roads, water, and electricity, on which the economic development and governmental services of most nations rely. Emergency services, medical information systems, environmental monitoring, smart-grid energy distribution, smart transportation systems -- all of these technologies depend on reliable access to high-speed broadband wireless. To achieve the dramatic improvements in capacity and spectral efficiency needed to accommodate such access and the multitude of users who want access to it anytime and anywhere, dramatic advances in wireless communication technology are required.

This Focus Group is dedicated to the study of how to exploit the presence of multiple antennas or antenna arrays to help achieve the needed improvements in wireless capacity. Multiple antennas offer a number of advantages in this regard: (1) They can increase the number of spatial "channels" over which information can be transferred, leading to a proportional increase in capacity; (2) They can provide a high degree of spatial "selectivity," which in turn can reduce the impact of interference and the leakage of sensitive signals in unwanted directions; and (3) By coherently combining signal reception or coordinating signal transmission at different points in space, they can achieve a significant energy savings -- the increase in power due to additional antenna hardware is more than offset by the combined coherent energy gain. There are several unique aspects of the research conducted in this Focus Group. One of these is the joint consideration of the physical aspects of the antennas and their matching to the subsequent electronic system and signal processing. Another is the study of how such arrays would perform at millimeter wave frequencies above 20-30 GHz, where the antennas are small and a very large number of them can be densely packed together. These two unique research directions come together in the Focus Group's research on so-called "massive" arrays composed of tens and even hundreds of antenna elements. The practical aspects of implementing a massive array at millimeter wave frequencies requires advances in channel modeling and estimation, equalization, interference management, and in practical energy-efficient hardware designs. It is expected that the efforts of this Focus Group will have important implications for the development of next generation (5G) of wireless systems.

TUM-IAS funded doctoral candidates:
Fabian Steiner, Circuit Theory and Signal Processing