Post Your Answer
2 years ago in RF & Antenna Systems By Bhagirathi Bisht
What are the most suitable adaptive beamforming algorithms for electronically steered antennas on a stratospheric platform (HAPS), considering platform motion and dynamic interference?
I'm designing the beamforming subsystem for a HAPS communication payload. The platform has slow drift and sway, and the user geometry changes. We need to maintain directed beams toward ground users while nulling interference. Given the processing constraints on board and the relatively slow channel variation (compared to terrestrial mobile), should I use classic LMS/RLS algorithms, or are more modern approaches like MVDR with diagonal loading or hybrid analog-digital solutions better? How do I handle the calibration of the array in this environment?
All Answers (1 Answers In All)
By Jayalakshmi Answered 1 year ago
For HAPS, the channel changes slowly (coherence time ~100ms–1s), but platform attitude uncertainty and calibration drift are the main challenges. I recommend a robust MVDR (Capon) beamformer with diagonal loading. The classic LMS/RLS algorithms are less suitable as they require a reference signal and can be slow to adapt to new interference. MVDR can form nulls based on covariance matrix estimation. Diagonal loading is essential to prevent signal self-nulling due to slight errors in the steering vector caused by platform sway. Implement a hybrid architecture: use digital beamforming for wide-area sector coverage and analog phase shifters for coarse user tracking. For calibration, implement periodic in-situ calibration using pilot signals from known ground beacons to correct for phase drifts in the RF chain. The algorithm complexity is manageable for modern onboard processors.
Reply to Jayalakshmi
Related Questions