Demonstrating End to End Standards Based Beam Hopping With Commercial Equipment Derisking the Physical Layer Challenges

In the current high throughput satellite (HTS) systems, beams are continuously illuminated. To allocate bandwidth and avoid adjacent beam interference, spectrum and polarization are divided in disjunct and fixed portions, called FDM. In this paradigm, seamless flexibility to adjust beams to the demand can only be achieved by (1) an advanced and costly processing payload with flexible filter sizes and, in case of beamforming, circuits for all of the beams that are continuously illuminated, (2) make‐before‐break handovers requiring more expensive modems. Fortunately, there is an alternative providing seamless flexibility to adjust to demand, called beam hopping, where an on‐board beam hopper illuminates a number of coverages, denoted cells (e.g., 8 cells), consecutively in time (hence TDM). The flexibility is achieved as the fraction of time by which each cell can be illuminated is configurable. As much less beams are simultaneously illuminated and no make before break (MBB) handover capability is required for the modems, this alternative is cheaper and less complex. The challenges to perform beam hopping are mainly situated at the physical layer, which have been addressed already partly by standardization (DVB‐S2X, annex E formats 5, 6 and 7), by proprietary payload implementations with beam hopping and several funded ESA projects. This paper reports work from the ESA Free Hopper projects, which intends to fully validate and derisk an end to end HTS system with standards based beam hopping with commercial equipment from iDirect, Easii‐ic (chip based receiver), Airbus (ABFN), and Honeywell (ferrite switches). The paper focuses on the gateway modulator architecture and the “ground only” synchronization mechanism, which is currently implemented and tested. The synchronization time‐aligns the waveform with a transparent beam hopping satellite and then remains time aligned (taking into account satellite movement and clock drifts), without requiring a terminal to be collocated with the gateway transmitter.