Motivation

The major challenges in wireless communication include spectral efficiency, link reliability, coverage and energy efficiency. This is due to the limited available bandwidth, the fading nature of the propagation channel and the mobility and autonomy of the wireless nodes. One of the most exciting recent trends is MIMO (Multiple Input/Multiple Output) Wireless, i.e. the use of the spatial dimension to improve spectral efficiency, coverage and reliability. The benefit of conventional MIMO Wireless with colocated antennas is constrained by the limited number of antennas per mobile node and by its dependence on a rich scattering environment.

In the last decade wireless communication has witnessed an explosive growth of applications ranging from Wireless Sensor Networks (WSN) and Wireless Body Area Networks (WBAN) to gigabit per second WLANs and high speed cellular radio. In the upcoming ubiquitous wireless world we will be surrounded by multiple heterogeneous wireless nodes, which are in radio range and share a common frequency band. This poses a huge challenge but also a unique new opportunity to wireless system design: how to utilize the high node density to improve the performance of all constituent wireless systems. This question is at the core of Cooperative Wireless Communication (CWC). As an example of the vast potential of CWC consider the large form factor of the virtual antenna array, which is formed by locally cooperating nodes. Here the cooperation enables us to overcome the above mentioned constraints of colocated MIMO. To fully benefit from cooperation, we have to regard the constituent wireless networks as heterogeneous entity rather than overlay of interfering networks and we have to consider cooperation across all layers.

An efficient short range wireless technology is a key enabler of CWC, as it facilitates the cooperation of spatially adjacent nodes. Ultra-Wideband (UWB) Wireless is an extremely promising short range candidate technology for CWC, as it features a rich tradeoff between range and data rate and supports precise position location and clustering. It is also a key to ultra low power operation: for WSN as well as for medium rate data streaming low duty cycle operation is the enabler of ultra low power. Here the high peak data rate of UWB is crucial.

The Wireless Communications Group (WCG) strives to develop core technology for a ubiquitous wireless world. Since 2002 our work has concentrated on CWC and on UWB.