Institut für Hochfrequenztechnik und Elektronik (IHE)

Misalignment Analysis of Line of Sight MIMO System

Introduction of the work:

Line-of-sight(LOS) multiple input and multiple output(MIMO) systems offer the possibility of high-speed data transmission by means of radio communication between mobile base stations through LOS path. These systems are used for backhaul communication as well as for communication between base stations where the laying of fiber optic cables would be too time-consuming and thus cost-intensive. In this case, the multipath propagation is not used as in conventional MIMO systems, but the distance of the antennas is selected so that the interference signal between the transmission channels are cancelled out during the processing of the received signals [1] by using either analog or digital equalizations.

It is obvious that LOS MIMO requires a strict distance between the antennas in order to achieve the best interference cancellation. However, distortions like vibrations, rotations may occur which leads to degradation of system performance. In this work, we are also interested in how robust is a LOS MIMO against these physical mismatches, and the corresponding recoveries.

Aims of the work:

Within the work, a LOS-MIMO system is to be set up and examined. The work will be divided into the following parts:

  1. Build up a LOS MIMO system at 28GHz and prove the concept of interference cancellation.
  2. By using software defined radio (SDR), which is controlled by host computer via Matlab and GNU radio software, add digital signal processing into the system.
  3. Compare the LOS MIMO performance using analog and digital signal processing at the receiver side.
  4. Analyze the LOS MIMO system performance under physical misalignments.


  1. Basic knowledge of communication systems and technologies.
  2. Proficiency usage of Matlab simulation.
  3. Programming skills using C++ or Python. 

[1] J. Hansryd and J. Edstam, “Microwave capacity evolution,” Ericsson Rev. (English Ed.), vol. 88, no. 1, pp. 22–27, 2011.