Search

US-20260128786-A1 - SELECTION, DIVERSITY COMBINING OR SATELLITE MIMO TO MITIGATE SCINTILLATION AND/OR NEAR-TERRESTRIAL MULTIPATH TO USER DEVICES

US20260128786A1US 20260128786 A1US20260128786 A1US 20260128786A1US-20260128786-A1

Abstract

A ground station processes downlink signals received from respective satellites. The ground station has a plurality of signal conditioning devices each receiving a respective one of the downlink signals and providing a conditioned downlink signal. A plurality of Doppler and/or Delay compensator devices each receive a respective conditioned downlink signal from a respective one of the plurality of signal conditioning devices. The compensator devices conduct Doppler and/or Delay compensation on the received conditioned downlink signal, and provide a compensated downlink signal output. A selector or diversity combiner receives the compensated downlink signal from each of the plurality of Doppler and/or Delay compensators. The selector or diversity combiner selects one of the received compensated downlink signals based on received signal strength of each received compensated downlink signal to provide a selected downlink signal, or diversity combines all of the received compensated downlink signals to provide a diversity combined signal. The selector or diversity combiner provides the selected downlink signal or the diversity combined signal to an eNodeB.

Inventors

  • Sriram Jayasimha
  • Jyothendar Paladugula

Assignees

  • AST & SCIENCE, LLC

Dates

Publication Date
20260507
Application Date
20251103
Priority Date
20190629

Claims (20)

  1. 1 . A ground station comprising: memory; and one or more processors coupled to the memory, wherein the one or more processors are configured to: condition a signal to generate a conditioned signal, wherein to condition the signal, the one or more processors are configured to translate a signal frequency of the signal from a first frequency band to a second frequency band; compensate the conditioned signal for delay and Doppler to generate a compensated signal; and perform, based on determining whether there is a residual frequency and a phase mismatch between the conditioned signal and one or more other compensated signals, at least one of: select the compensated signal from among the one or more other compensated signals to be provided to a base station, or combine the compensated signal with another compensated signal of the one or more other compensated signals to generate a diversity combined signal to be provided to the base station.
  2. 2 . The ground station of claim 1 , wherein the first frequency band comprises a Q-band or V-band, and wherein the second frequency band comprises a Long Term Evolution (LTE) band.
  3. 3 . The ground station of claim 1 , wherein the one or more processors are configured to select the compensated signal from among the one or more other compensated signals based on determining, from the frequency and phase of the compensated signal and the one or more other compensated signals, that there is a residual frequency and a phase mismatch.
  4. 4 . The ground station of claim 1 , wherein the one or more processors are configured to combine the compensated signal with the another compensated signal based on determining, from the frequency and phase of the compensated signal and the another compensated signal, that there is not a residual frequency and a phase mismatch.
  5. 5 . The ground station of claim 1 , wherein the base station comprises an eNodeB.
  6. 6 . The ground station of claim 1 , wherein the one or more processors are configured to compensate the conditioned signal for delay and Doppler based on satellite ephemeris data associated with a satellite.
  7. 7 . The ground station of claim 6 , wherein the satellite ephemeris data comprises a position and one or more orbital parameters of the satellite.
  8. 8 . The ground station of claim 1 , wherein the one or more processors are configured to compensate the conditioned signal for delay and Doppler based on location information of the ground station.
  9. 9 . The ground station of claim 8 , wherein the location information of the ground station is obtained from a global positioning satellite (GPS) location of the ground station.
  10. 10 . The ground station of claim 1 , wherein the signal comprises one or more of a downlink signal or an uplink signal.
  11. 11 . A method comprising: conditioning, by one or more processors of a ground station, a signal to generate a conditioned signal, wherein conditioning the signal comprises translating a signal frequency of the signal from a first frequency band to a second frequency band; compensating, by the one or more processors of the ground station, the conditioned signal for delay and Doppler to generate a compensated signal; and based on determining whether there is a residual frequency and a phase mismatch between the compensated signal and one or more other compensated signals, performing, by the one or more processors of the ground station, at least one of: selecting the compensated signal from among the one or more other compensated signals to be provided to a base station, or combining the compensated signal with another compensated signal of the one or more other compensated signals to generate a diversity combined signal to be provided to the base station.
  12. 12 . The method of claim 11 , wherein the first frequency band comprises a Q-band or V-band, and wherein the second frequency band comprises a Long Term Evolution (LTE) band.
  13. 13 . The method of claim 11 , wherein selecting the compensated signal from among one or more other compensated signals is based on determining, from a frequency and a phase of the compensated signal and the one or more other compensated signals, that there is a residual frequency and a phase mismatch.
  14. 14 . The method of claim 11 , wherein combining the compensated signal with another compensated signal is based on determining, from a frequency and a phase of the compensated signal and the another compensated signal, that there is not a residual frequency and a phase mismatch.
  15. 15 . The method of claim 11 , wherein compensating the conditioned signal for delay and Doppler is based on satellite ephemeris data associated with a satellite, wherein the satellite ephemeris data comprises a position and one or more orbital parameters of the satellite.
  16. 16 . The method of claim 11 , wherein compensating the conditioned signal for delay and Doppler is based on location information of the ground station.
  17. 17 . The method of claim 11 , wherein the signal comprises one or more of a downlink signal or an uplink signal.
  18. 18 . Non-transitory computer-readable media comprising instructions that when executed, cause one or more processors to: condition a signal to generate a conditioned signal, wherein to condition the signal comprises translating a signal frequency of each downlink signal from a first frequency band to a second frequency band; compensate the conditioned signal for delay and Doppler to generate a compensated signal; and based on determining whether there is a residual frequency and a phase mismatch between the compensated signal and one or more other compensated signals, perform at least one of: selecting the compensated signal from among the one or more other compensated signals to be provided to a base station, or combining the compensated signal with another compensated signal of the one or more other compensated signals to generate a diversity combined signal to be provided to the base station.
  19. 19 . The ground station of claim 1 , wherein to select the compensated signal from among one or more other compensated signals to be provided to a base station, the one or more processors are configured to: select the compensated signal from among one or more other compensated signals based on a received signal strength of the compensated signal.
  20. 20 . The ground station of claim 1 , wherein selecting the compensated signal from among one or more other compensated signals to be provided to a base station comprises selecting the compensated signal from among one or more other compensated signals based on a received signal strength of the compensated signal.

Description

RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/738,626, filed 10 Jun. 2024, which is a continuation of U.S. patent application Ser. No. 18/080,424, filed 13 Dec. 2022, now issued as U.S. Pat. No. 12,009,907, granted 11 Jun. 2024, which is a continuation of U.S. patent application Ser. No. 16/905,446, filed 18 Jun. 2020, now issued as U.S. Pat. No. 11,528,077, granted 13 Dec. 2022, which claims the benefit of U.S. Provisional Patent Application No. 62/951,618, filed 20 Dec. 2019, IN Provisional Patent Application No. 201911025299, filed 29 Jun. 2019, and IN Provisional Patent Application No. 201911026070, filed 25 Jun. 2019, the entire content of each application is incorporated herein by reference. BACKGROUND The present disclosure relates to standard mobile user equipment (UEs) to be connected to base-station equipment (e.g., eNodeB's or gNodeB's in 4G and 5G mobile communications parlance) located at gateways, with at least two directional antennas, tracking Low-Earth Orbit (LEO) relay satellites. The communications between the UEs and the LEO satellites are typically in UHF/L-band (i.e., 600-900 MHz or 1800-2100 MHz bands), while the satellite-to-gateway links are in Q/V band. Impairments of interest in the UHF/L-band to LEO satellite links are ionospheric scintillation and terrestrial multipath losses. The primary impairments in the Q/V band link from/to the gateway to/from the satellite are rain-induced attenuation and/or depolarization. While diversity combining is a well-understood concept in many communication systems (including satellite communication systems), we focus here on the type of diversity combining needed in the above-stated scenario. SUMMARY A ground station processes downlink signals received from respective satellites. The ground station has a plurality of signal conditioning devices each receiving a respective one of the downlink signals and providing a conditioned downlink signal. A plurality of Doppler and/or Delay compensator devices each receive a respective conditioned downlink signal from a respective one of the plurality of signal conditioning devices. The compensator devices Doppler and/or Delay compensate the received conditioned downlink signal to a nominal zero frequency offset and a constant delay right through the satellite pass. A selector or diversity combiner receives the compensated downlink signal from each of the plurality of Doppler and/or Delay compensators. The selector or diversity combiner selects one of the received compensated downlink signals based on received signal strength of each received compensated downlink signal to provide a selected downlink signal, or diversity combines all of the received compensated downlink signals to provide a diversity combined signal. The selector or diversity combiner provides the selected downlink signal or the diversity combined signal to an eNodeB. BRIEF DESCRIPTION OF THE FIGURES FIG. 1(a) shows satellites visible to a geographic cell in polar region. FIG. 1(b) shows the concept of Satellite Diversity Combining (SDC). FIG. 2(a) is a block diagram of scintillation mitigation through RSSI-based satellite switching or diversity combining. FIG. 2(b) shows scintillation/multipath mitigation through RSSI-based satellite switching or diversity combining or SIMO. FIG. 3 is a 2×2 bi-directional MIMO exploiting two-antenna UEs. DETAILED DESCRIPTION In describing the illustrative, non-limiting embodiments of the disclosure illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in similar manner to accomplish a similar purpose. Several embodiments of the disclosure are described for illustrative purposes, it being understood that the disclosure may be embodied in other forms not specifically shown in the drawings. Ionospheric scintillations are rapid temporal fluctuations in both amplitude and phase of trans-ionospheric UHF and L-band signals caused by the scattering due to irregularities in the distribution of electrons encountered along the radio propagation path. The most severe scintillations are observed near the poles (at auroral latitudes) and near the equator (within ±20° of geomagnetic equator). For example, with a polar constellation, satellite selection in polar regions can overcome scintillation loss there, since the terminal devices or stations, e.g., User Equipment (UE) can see two (or more) satellites 10a, 10b served by the same Ground Station (GS) 200, as shown in FIG. 1(a), 1(b). In addition, depending on satellite elevation seen by the User Equipment (UE), both uplink and downlink encounter near-terrestrial multipath spread. As further illustrated in FIG. 1(a), 1(b), UEs such as mobile cellphones are in a ground cell served by a single base st