DIVERSITY : User Terminal With Path Diversity For Constellations

Title:  User Terminal With Path Diversity For Constellations (DIVERSITY)
Funding source: ESA - European Space Agency. (ARTES AT)
Prime Contractor: SnT, University of Luxembourg, Luxembourg
Partners: SES.
Principal investigator: Prof. Symeon Chatzinotas
Researchers: Dr. Juan Merlano Duncan, Dr. Bhavani Shankar, Dr. Jorge Querol, Dr. Jorge Luis Gonzalez, Dr. Wallace Martins, Dr. Eva Lagunas, Dr. Lei Lei, Dr. Houcine Chougrani, Dr. Rakesh Palisetty, Ms. Liz Martinez-Marrero, Mr. Mohammad Gholamian.
Starting date / Duration: November 2021 / 24 months



Satellites with their wide coverage can enable “anytime/anywhere access” at affordable costs, thereby staking a claim in future 5G networks. In particular, the space-based component can substantially augment the 5G service capabilities.  These enhancements are enabled by the satellite’s inherent structure that supports perceived multimedia traffic growth and ubiquitous coverage. These, in turn, will be crucial in several applications such as machine-to-machine communications, critical telecommunication setup, and backhauling and trunking.

However, some of these new applications are not economically viable today due to the requirements of the receiver terminals. Therefore, there is a commercial interest in small and low-cost terminals for medium and low-orbit satellite systems, based on a wide-beam and low-gain antenna with a half-power beamwidth of 10 degrees or wider. Since such an antenna will see multiple, at least two, satellites at the same time, there is an opportunity to combine the signals from multiple satellites for improving the aggregated data rate, for beam load balancing, or for improving the robustness of the satellite link through path diversity.



The objective of this activity is to develop and test in a representative environment a ground transceiver that combines the RF signals from two or more medium-orbit or low-orbit satellites operating in Ka-Band. In order to demonstrate the concept, two breadboard receivers shall be developed, one assumed to be located at the user terminal, fed through a wide-beam and low-gain Ka-Band antenna, and one at the gateway considering a hub-spoke network typical of broadband applications.

To quantify the potential gains and benefits of path diversity and signal combination, it is proposed to perform first a measurement campaign. The measurements will be executed by using the beacon signals transmitted by medium orbit (MEO) satellites. The hereto-proposed activity would quantify the impact of signal fading due to multipath effects near the terminal and by quantifying the potential link improvements through path diversity.

After a proper channel modeling, the activity will develop and implement the software, firmware, and hardware of the GW and UT receivers. The prototyped receivers will undergo thorough laboratory performance validation according to a detailed test plan, which will be formulated as part of the activity. This test plan will make use of a satellite signal generator and a satellite channel emulator.

The targeted improvement is to increase up to a factor of 2 the data throughput from near 3dB gain in link performance by dual signal combination.

The target Technology Readiness Level (TRL) for this activity is 4, starting from TRL equal to 3.


System Architecture

As a baseline design, the combining receivers will consider the scenario depicted in the figure below, with two satellites connected by two highly directive antennas at the Gateway side and a user terminal that receives the signal from the two satellites. The RT link is also sent using the signal received by the two satellites and sent to the Gateway antennas. This scenario will be replicated in a laboratory environment using a Gateway modem, a UT modem, and a multilink satellite channel emulator already available at SnT. With this configuration, the communication system can emulate different orbits and satellite payload characteristics.

The measurement campaign will include two different live experiments: Experiment A, using two highly directive antennas pointing to different satellites, and Experiment B, using a small antenna with a wide beam covering two adjacent satellites in the constellation. Experiment A will allow the acquisition of information related to the orbits, Doppler effect, phase, amplitudes, and received sequences. While Experiment B will permit to characterize multipath and fading, having previous knowledge of the received signal obtained from Experiment A. The measurement campaign will be extended and complemented by emulating the multipath environment, busted by the results from the experimental phase, using the In-House Developed Satellite Channel Emulator, available in the SnT premises.

Related Projects:

  • SERENADE - Satellite Precoding Hardware Demonstrator (see more). 
  • LiveSatPreDem – Live Satellite Precoding Demonstration (see more). 
  • MEO MODEMS - Modem prototype for MEO broadband access (see more)
  • CGD - Prototype of a Centralized Broadband Gateway for Precoded Multi-beam Networks (see more). 
  • DISBuS - Dynamic Beam Forming and In-band Signalling for Next-Generation Satellite Systems (see more). 



Dr. Juan Carlos Merlano Duncan, Research Scientist,