BROADBAND ACCESS SYSTEM VIA DRONE/UAV PLATFORMS

• US 20160105233A1
• Filed: 05/21/2014
• Published: 04/14/2016
• Est. Priority Date: 02/17/2014
• Status: Active Grant

• Current Assignee: Bridgewest Finance, LLC
• Original Assignee: Ubiqomm LLC
• Inventors: Jalali, Ahmad
• Granted Patent: US 9,853,715 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H04B 17/104 of other parameters, e.g. DC offset, delay or propagation times
• CPC Class Codes: H04B 17/12 of transmit antennas, e.g. of the amplitude or phase
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 56/0025 synchronizing potentially movable access points

Abstract

The present disclosure describes the system and methods for providing broadband internet access to homes and enterprises using a network of aerial platforms such as drones/UAVs/balloons. The drone communication system is composed of an antenna sub-system, a radio sub-system and a data switching sub-system. Drones form and point beams toward ground terminals in different areas in a space division multiple access scheme. Ground terminals are composed of an antenna sub-system and a radio sub-system. Ground terminals search for the drone from which they receive the strongest signals. Drone and ground terminals comprise of methods and systems to calibrate receive and transmit antenna elements. Drone radio sub-system keeps track of the drone'"'"'s position and orientation changes and adjust drone'"'"'s antenna beam accordingly to point to the same location on the ground as the drone moves. Depending on the changes in drone'"'"'s position and orientation, the drone radio sub-system may switch the antenna aperture and/or the antenna fixture that is used to form a beam toward a specific ground terminal. Drones communicate with the terminals using a space and time division multiple access scheme.

Claims

1. A system for broadband wireless access communication between ground terminals and a network of one or more aerial platforms, comprising:

at least one antenna fixture on each aerial platform capable of generating at least one beam toward the ground, forming beams toward terminals located in a wide area on the ground;

at least one radio sub-system on each aerial platforms with a receiver for demodulating and decoding signals received from the ground terminals, a transmitter for modulating data and transmitting the modulated signals to ground terminals through at least one aerial platform antenna, sending at least one pilot signal to ground terminals, and controlling and configuring the aerial platform antenna to form beams in specific directions;

at least one aerial platform switching sub-system with capability to switch data received at the aerial platform from one set of terminals on the ground to another set of terminals;

an antenna sub-system at the ground terminal with capability to point beams toward specific aerial platforms; and

a radio sub-system at the ground terminal with a receiver for demodulating and decoding signals received from aerial platforms, a transmitter for modulating ground terminal data and transmitting the signals to aerial platforms through the ground terminal antenna, sending at least one pilot signal to aerial platforms, and controlling and configuring the ground terminal antenna to from its beam toward aerial platforms.

2. The system of claim 1 further comprising aerial platform antenna fixtures containing a plurality of antenna apertures with each antenna aperture pointed to cover different areas.

3. The system of claim 2 wherein the plurality of antenna fixtures are installed on different locations on the aerial platform to cover a foot print of the aerial platform even as the aerial platform rolls, pitches and yaws.

4. The system of claim 3 wherein at least one antenna fixture on each aerial platform is disposed to steer a beam toward at least one other aerial platform in the network.

5. The system of claim 3 further comprising:

means for detecting changes in aerial platform'"'"'s position, roll, pitch, and yaw orientation; and

means for instructing the plurality of antenna fixtures to accordingly steer the aerial platform beam to point to the same location on the ground.

6. The system of claim 1, further comprising means for detecting that the aerial platform'"'"'s position or orientation has moved enough that the antenna fixture or the antenna aperture that points to a given location on the ground must be switched/handed over to a different antenna fixture or to a different antenna aperture of the same antenna fixture.

7. The system of claim 1, further comprising a ground terminal antenna having an aperture installed on a structure that can move the aperture in two axes in azimuth and elevation directions to approximately point the ground terminal antenna toward a aerial platform, the aperture having elements with electronic beam forming capability in azimuth and elevation to finely point the beam toward the aerial platform.

8. The system of claim 1, further comprising a ground terminal antenna with at least two apertures, with at least one aperture pointing toward lower elevation angles, and at least a second aperture pointing toward higher elevation angles, the at least two apertures installed on a rotating structure in azimuth direction, and each aperture having electronic beam forming capability in azimuth and elevation to finely point the beam toward the aerial platform.

9. The system of claim 7, wherein the aperture has elements that steer beams electronically only in elevation, and azimuth beam steering is achieved only by mechanical rotation of the aperture.

10. The system of claim 7, where the antenna aperture has no electronic beam steering capability, and beam steering in azimuth and elevation is achieved by mechanically rotating the aperture in azimuth and elevation axes toward a aerial platform.

11. The system of claim 1, further comprising:

a ground terminal antenna having a plurality of apertures with each aperture facing a different direction in azimuth or elevation; and

,

means for determining which of the plurality of apertures has the highest gain toward a aerial platform, and for switching the transmitter and receiver to the aperture providing highest gain.

12. The system of claim 1, further comprising:

means for storing a list of aerial platforms surrounding the ground terminal, so called aerial platform neighbor list, according to aerial platforms'"'"' pilot strength, storing the aerial platforms'"'"' locations, and pointing the ground terminal antenna toward a aerial platform on the aerial platform neighbor list; and

the ground terminal detecting the pilot signal from the aerial platform, to estimate the pilot signal quality, and to compare the measured signal quality to a configured value to determine the aerial platform from which the ground terminal receives the strongest signal.

13. The system of claim 1, wherein the one or more aerial platforms send pilot signals in each beam and the ground terminals divide angular space around the terminal into angular cones and search each angular cone for aerial platform pilot signals and the ground terminals choose an angular cone with strongest aerial platform pilot signal and select a corresponding aerial platform as the best aerial platform.

14. The system of claim 13 wherein the ground terminals send messages to a aerial platform to register with the aerial platform network, to send the ground terminal'"'"'s position information and other configuration parameters to the aerial platform, and to inform the network of the identity of the aerial platform the ground terminal intends to communicate with.

15. The system of claim 14 wherein the aerial platform periodically sends its position location coordinates and orientation to the terminals in all beams.

16. The system of claim 15, wherein the ground terminals using the aerial platform position location coordinates and orientation to maintain the terminal antenna beam pointed on the aerial platform as the aerial platform changes position or orientation.

17. The system of claim 1 wherein the ground terminal antenna sub-system makes small perturbations to its beam'"'"'s bore sight, and the terminal radio sub-system makes aerial platform pilot signal measurements for each terminal beam position perturbation;

the ground terminal radio sub-system uses the aerial platform pilot strength measurements from different terminal beam perturbation positions; and

the terminal antenna sub-system points its beam toward the direction of the beam perturbation with highest pilot strength measurement.

18. The system of claim 1, further comprising:

means for forming at least one aerial platform beam to cover the foot print of the aerial platform;

means for transmitting at least one frequency channel from aerial platform in each beam; and

means for receiving at least one frequency channel from ground terminals in each beam.

19. The system of claim 18, further comprising:

means for dividing the foot print of the aerial platform into a fixed set of contiguous virtual aerial platform beams;

means for turning a number of the virtual aerial platform beams on and the remaining virtual beams off depending on location of ground terminals during one time interval; and

, means for changing the set of beams that are on during different time intervals.

20. The system of claim 18 wherein a number of non-overlapping aerial platform beams are formed with adjustable beam centers.

21. In the system of claim 1, a method of calibrating the transmit antenna elements of the aerial platform antenna, comprising steps of:

transmitting a pilot signal from the aerial platform antenna through one antenna aperture of one aerial platform antenna fixture toward a reference ground terminal;

measuring at least one signal quality metric of the pilot signal received from the aerial platform with the ground terminal,

sending the measured aerial platform pilot signal quality to the aerial platform; and

updating the coefficients of the transmit antenna elements with the aerial platform using pilot signal quality measurements received from the ground terminal to optimize at least one signal quality metric of the pilot signal received at the ground terminal from the aerial platform.

22. In the system of claim 1, a method of calibrating the transmit antenna elements of the aerial platform antenna, comprising steps of:

transmitting a pilot signal on each element of the antenna aperture of the aerial platform antenna, one element a time, toward a reference ground terminal;

measuring the amplitude and phase of the pilot signal received from the aerial platform with the ground terminal, and sending the measured aerial platform pilot signal amplitude and phase to the aerial platform; and

using the amplitude and phase information received from the ground terminal with the aerial platform to calibrate the transmit antenna elements.

23. In the system of claim 1, a method of calibrating the receive antenna elements of the aerial platform antenna, comprising steps of:

receiving a signal from the ground terminal by the aerial platform, and measuring at least one signal quality metric of the received signal; and

updating the receive antenna element coefficients based on an optimization criterion.

24. In the system of claim 1, a method of calibrating the transmit antenna elements of the ground terminal antenna, comprising steps of:

transmitting a pilot signal through one antenna aperture of one ground terminal antenna fixture toward a aerial platform;

measuring at least one signal quality metric of the pilot signal received from the ground terminal with the aerial platform, and sending the measured aerial platform pilot signal quality to the ground terminal; and

updating the coefficients of the ground terminal transmit antenna elements using pilot signal quality measurements received from the aerial platform to optimize at least one signal quality aspect of the pilot signal received at the aerial platform from the ground terminal.

25. In the system of claim 1, a method of calibrating the transmit antenna elements of the ground terminal antenna, comprising steps of:

transmitting a pilot signal through each element of the ground terminal antenna aperture, one element a time, toward a reference aerial platform;

measuring the amplitude and phase of the pilot signal received from the ground terminal by the aerial platform, and sending the measured aerial platform pilot signal amplitude and phase to the ground terminal; and

using the amplitude and phase information received from the aerial platform by the ground terminal to calibrate the transmit antenna elements.

26. In the system of claim 1, a method of calibrating the receive antenna elements of the ground terminal, comprising steps of:

receiving a signal from the aerial platform by the ground terminal, and measuring at least one signal quality metric of the received signal; and

updating the receive antenna element coefficients based on an optimization criterion.

27. In the system of claim 1, a method of the aerial platform to modulate a waveform to transmit to ground terminals comprising steps of:

dividing the waveform into time into slots, and assigning some of the time slots for signaling messages and the remaining time slots for data transmission; and

inserting a pilot signal in each time slot for signal quality measurement by the ground terminals.

28. In the system of claim 1, a method of the ground terminals to divide the available uplink spectrum into a number of frequency channels, comprising steps of:

modulating a waveform for each frequency channel, to assign some of the frequency channels for sending signal messages to aerial platforms using a random multiple access scheme, and to assign the remaining channels for sending data to aerial platforms; and

inserting a pilot signal in each time slot for signal quality measurement by the aerial platform.

29. A method of claim 28, further comprising the step of synchronizing the uplink transmission to arrive at the aerial platform time aligned.

30. In the system of claim 1, a method of the ground terminal to modulate a single waveform on the whole uplink spectrum to transmit to aerial platforms, comprising steps of:

dividing the waveform into time into slots, and assigning some of the time slots for signaling messages and remaining time slots for data transmission; and

inserting a pilot signal in each time slot for signal quality measurement by the aerial platforms.

31. A method of claim 30, further comprising the steps of:

estimating a signal quality metric on the uplink signal received from ground terminals such as SINR by the aerial platform, to determine the highest data rate the ground terminal may transmit, and the aerial platform radio sub-system to decode correctly with high probability; and

sending the index of the determined data rate to the ground terminals on the downlink channel.

32. A method of claim 27, further comprising steps of:

estimating a signal quality metric on the downlink signal received from the aerial platform such as SINR by the ground terminal, to determine the highest data rate the aerial platform may transmit, and the ground terminal radio sub-system to decode correctly with high probability; and

sending the index of the determined data rate to the ground terminals on the uplink channels.