Abstract
The high Doppler effects in satellite communications make the equivalent channels fast varying, which leads to channel estimation difficulties and the need for high channel estimation overheads. In this paper we propose a state-space approach for tracking channel variations for satellite links with high Doppler frequency shifts. We consider the communication between satellite links where a multi-antenna receiving satellite is connected to several transmitting satellites, which can have substantially different Doppler drifts. The proposed channel tracking technique follows the individual Doppler drifts for the different satellites. Finally, our performance results indicate that the proposed channel tracking is able to cope with strong Doppler drifts, without the need for high channel estimation overheads, making it a promising technique for future systems using satellite mega-constellations.
Highlights
T HE integration of non-terrestrial networks (NTN) into 5G as specified by the 3GPP [1]–[4] represents the first systematic effort to include satellite-based networks into the the standard of a new mobile communications generation
This is due to the fact that SC combined with frequency-domain equalization (SC-FDE) schemes have simpler transmitters, lower peak-to-average power ratio (PAPR), and increased robustness to carrierfrequency offset (CFO) compared to OFDM
Since we will be using the channel estimate obtained in the current time-slot, l, in the ensuing time-slot, l + 1, we update (25) with the value of the Doppler shift obtained with the extended Kalman filter (EKF), i.e., hEnK,lF+(1r,m) = α0(r,m) δ(lT − τm)×
Summary
T HE integration of non-terrestrial networks (NTN) into 5G as specified by the 3GPP [1]–[4] represents the first systematic effort to include satellite-based networks into the the standard of a new mobile communications generation. The Kalman filter is shown to improve the stability of estimated frequency offset and track the time-varying frequency offset This approach is limited to scenarios with a single satellite link or multiple satellite links with identical Doppler shifts. For terrestrial mobile communications SC-FDE has been advocated as a promising scheme for the uplink (i.e., when the communication signal goes from the mobile terminal to the base station) [32] This is due to the fact that SC-FDE schemes have simpler transmitters, lower peak-to-average power ratio (PAPR), and increased robustness to carrierfrequency offset (CFO) compared to OFDM.
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