Research

The Communications Laboratory (in German: Labor KommunikationsTechnik, LKT) of the Landshut University of Applied Sciences focuses on the following research areas.

Wireless Sensor Networks

A modern topic in wireless communications is the Internet of Things (IoTs), like e.g., the network of sensors and other electronic equipment in a smart home. Another interesting application in this field of research is the so-called smart dust, i.e., a system of many tiny sensors which are wirelessly connected with each other in order to exchange and process measured data. The underlying wireless networks can have different topologies.

We are especially interested in a wireless meshed network of sensors which are measuring a physical field like, e.g., the temperature distribution in a room or the moisture distribution on an agricultural land. Thereby, data processing is done either centralized in a master node or distributed over the network, also denoted as in-network processing. The focus of research is on low-energy, low-cost, and reliable solutions. Low-energy realizations are especially important for applications where a long battery life is obligatory. These solutions are also supported via energy harvesting.

Synchronization

In most of the research areas within communications, synchronization, e.g., frame, clock or carrier synchronization, is often assumed to be ideal. However, in real systems, synchronization methods are erroneous and have a non-negligible effect on the performance of the whole system.

Our research focuses on an approach for clock synchronization, which is inspired by nature. A group of periodically flashing fireflies are synchronizing when they are in the vicinity of each other. This synchronization is performed in a non-centralized manner, i.e., there is no master firefly who tells the other flies when to flash. On the contrary, each firefly is adjusting its flashing times by observing the flashes of neighboring flies.

The following movie demonstrates a communications network whose nodes are synchronized by a method which is related to the synchronization of fireflies, therefore, also denoted as firefly synchronization.

Video demonstrating firefly synchronization of a communications network (source: G. Dietl)

Software Defined Radios

Software Defined Radios (SDRs) are radios whose properties like, e.g., the modulation alphabet, the type of pulse shaping, the type of receiver structure, can be easily adopted via changing the underlying software. While this implementation approach is especially appealing for prototyping of new communications standards due to its flexibility, it has also some severe drawbacks.

Usually, SDR implementations are much less energy efficient than comparable hardware solutions. This is also the reason why SDRs are still not used in today’s communications devices like, e.g., a mobile phone, where a long battery life is one of the key requirements. Therefore, our research focuses on the development of low-energy, low-complexity, and low-cost SDRs.

MIMO and Millimeter Wave Communications

Multiple-Input Multiple-Output (MIMO) in modern communications systems refers to the usage of several antennas at the transmitter as well as at the receiver. These antennas can be used to enhance the reliability of communications, e.g., by applying so-called diversity techniques, and/or to increase the data rate. If one is interested in very high data rates, MIMO systems are often combined with millimeter Wave (mmWave) communications, i.e, communications systems whose carrier frequencies have a wavelength of only a few millimeters.

Popular research topics in the area of MIMO are, e.g.,

  • massive MIMO, i.e., a communications system with a huge amount of antennas at the receiver and/or transmitter,
  • MIMO in combination with millimeter Wave (mmWave) communications, and
  • multicell and multiuser MIMO.