Flexible Wireless Systems

Prof. Christoph Mecklenbräuker is leading the research group on flexible wireless systems.


IMG_5108Present 4G wireless systems enable efficient transmission and distribution of digital content: The Internet has arrived in the mobile domain and allows the generation, transmission, distribution, storage, and manipulation of information. The next technical challenge is the extension of the mobile Internet to production, transportation, distribution, storage, and manipulation of objects (“internet of things”). Fifth Generation (5G) wireless technologies need to become dependable. This requires major improvements in availability (coverage) and transmission latency, packet delivery guarantees, guaranteed data rates, as well as energy efficiency and cost structure. Therefore, we investigate novel transmission techniques and protocols, their behavior at high network load energy efficient solutions.

The use of MIMO transmission using antenna array technology has become the commercially available state of the art since 3.5G mobile communications. The current trend towards MIMO-OFDM continues. Major improvements compared to UMTS since 2006 have been achieved in spectral efficiency from the use of dynamic resource allocation which takes into account the current system load, advanced precoding techniques, and spatial multiplexing.


Direct radio communication between mobile entities enjoys a renaissance in connection with the recent interest in peer-to-peer and ad-hoc networks. This is especially true for safety-related vehicle-to-vehicle communication to enable advanced active safety. Traffic telematics applications are currently under intense research and development for making transportation safer, more efficient, and cleaner. Co-operative systems have become an important field of research in the area of telematics. Wireless networking of sensors and instrumentation enables new application fields: Intelligent Transport, Smart Metering, Intelligent Production, etc. We investigate dynamic resource allocation schemes which employ channel prediction, take into account the current system load, as well as transmission latency. Here, we see a seamless transition from 3GPP Long Term Evolution Advanced (LTE-A) towards heterogeneous wireless networks based on software-defined radio (SDR) concepts.

Nonlinear detection techniques offer resource efficient solutions in communication systems. The nonlinearity is adapted to the interference scenario, such that the interference is discriminated whereas the information of interest is detected largely unperturbed. Such communication systems are interference resilient.

IMG_0011One family of wireless systems features extreme bandwidths and low power spectral densities. These ultra-wideband (UWB) transmission techniques will revolutionize the communication among electronic sensors and actuators over short ranges in buildings. They cause little interference to existing small bandwidth systems. Here, the spectral efficiency is of less importance than the power efficiency of the transmission scheme in short-range links. Key applications will be low-power sensor networks and robust embedded systems which require neither batteries, nor external antennas. We are exploring UWB impulse-radio techniques experimentally with integrated on-chip antennas for power-efficient short-range wireless communication, sensing, and localization. Thus, UWB technology provides a dependable association of data with objects: A key to the Internet of Things.

Research Topics

Current research in flexible wireless systems is in the following application areas:

  • Dependable vehicular connectivity (ETSI ITS G5 and 4G/5G cellular)
  • Smart Tags and Sensor Nets (RFID, multifrequency, smart readers)
  • Mobile Communications Evolution (5G and millimeter wave)
  • Nearfield Power Efficiency (advanced tag antenna design)
  • Integrated Vehicle-Chassis Antennas (antennas on carbon fiber chassis)

Available research infrastructure:

  • Shielded anechoic chamber (5m x 5m x 5m, 800 MHz – 100 GHz)
  • Nearfield scanner (800 MHz – 40 GHz)
  • GTEM cell (up to 6 GHz)
  • Vienna MIMO testbed (4 sites, antennas each, centered at 2.503 GHz)
  • RFID testbed
  • National Instruments USRP RIO (software defined radio prototyping platform, 50 MHz – 6 GHz, 40 MHz bandwidth, 2×2 MIMO, 3 nodes)
  • reconfigurable SteppIR DB36 Yagi-Uda antenna (7 MHz – 50 MHz)


The previous Christian Doppler Laboratory “Wireless Technologies for Sustainable Mobility” (2009-2016) defined the fundamentals which provide the scientific base for today’s research project landscape in the area “flexible wireless systems”: