Accelerated satellite acquisition scheme
A user terminal includes a reconfigurable phased array antenna having a plurality of antenna elements. The user terminal is operable for: broadening a field of regard of the reconfigurable phased array antenna; receiving signals from a plurality of satellites within the field of regard using the reconfigurable phased array antenna; determining one or more attributes of the received signals for each of the satellites; and selecting one of the plurality of satellites for communication based on the attributes of the received signals. After the satellite has been selected, the user terminal is configured for: switching to a directional mode for the reconfigurable phased array antenna; establishing the communication with the selected satellite using the reconfigurable phased array antenna; and tracking the selected satellite. Ephemeris data broadcast by the satellites is used by the user terminal to track the satellites and to perform handovers between satellites.
1 . An apparatus for establishing communication with a satellite, comprising:
a user terminal including a reconfigurable phased array antenna, having a plurality of antenna elements, and a processor, wherein the processor is configured to control user terminal operations for:
broadening a field of regard, in acquisition mode after being turned on, perceivable by the reconfigurable phased array antenna at a particular time instant, by spreading a beam width using a spoiled beam,
wherein the spoiled beam is based on changing a phase or an amplitude for a subset of antenna elements of the plurality of antenna elements, to introduce a phase difference that alters a coherence of received signals to spread the beam width, and to increase a receiving area for an increased signal-to-noise ratio, and
wherein the reconfigurable phased array antenna is slewed to establish an initial pointing vector comprised of an azimuth and elevation prior to selecting the broadened field of regard, and the reconfigurable phased array antenna is not slewed once the broadened field of regard is selected;
receiving pilot signals from one or more satellites within the broadened field of regard using the reconfigurable phased array antenna;
selecting one of the one or more satellites based on a proximity, of the received pilot signals, to other signals, before terminating communication with a current satellite, of the one or more satellites, that has a communication established,
wherein the selected one of the one or more satellites is different from the current satellite;
switching to a directional mode for the reconfigurable phased array antenna,
wherein the reconfigurable phased array antenna is reconfigured to be directional towards the selected satellite by beamforming and to provide a higher gain; and
establishing communication with the selected one of the one or more satellites using the reconfigurable phased array antenna in the directional mode, for completing a satellite-to-satellite handover process.
2 . The apparatus of claim 1 , wherein the field of regard of the reconfigurable phased array antenna is broadened using the spoiled beam by selecting a sub-array of two or more antenna elements of the reconfigurable phased array antenna to spread the beam width.
3 . The apparatus of claim 1 , wherein the processor is further configured to control the user terminal operations for tracking the selected one of the one or more satellites by determining an initial pointing vector comprised of an azimuth and elevation and an initial tracking vector comprised of a flight path for the selected one of the one or more satellites relative to a current terrestrial or airborne location of the user terminal based on satellite ephemeris data for the selected one of the one or more satellites.
4 . The apparatus of claim 1 , wherein the reconfigurable phased array antenna is stationary prior to broadening the field of regard.
5 . The apparatus of claim 1 , wherein the processor is further configured to control the user terminal operations for broadening the field of regard by spreading the beam width using a single antenna element of the plurality of antenna elements.
6 . The apparatus of claim 1 , wherein the processor is further configured to control the user terminal operations for broadening the field of regard by spreading the beam width, using the spoiled beam, with all of the antenna elements of the plurality of antenna elements.
7 . The apparatus of claim 6 , wherein the spoiled beam broadens the field of regard with higher antenna directivity at an edge of a beamwidth in comparison to a beam that uses a single antenna element.
8 . The apparatus of claim 1 , wherein the one or more satellites are selected further based on a signal strength or a signal quality of the received pilot signals.
9 . The apparatus of claim 1 , wherein ephemeris data broadcast by the one or more satellites is used to at least one of slew the antenna or point the reconfigurable phased array antenna at a particular satellite.
10 . The apparatus of claim 1 , wherein the pilot signals are received from one or more satellites within the broadened field of regard using only the subset of antenna elements, and
wherein switching to the directional mode is performed after the beam being spread.
11 . A method of establishing communication with a satellite, comprising:
providing a user terminal including a reconfigurable phased array antenna, having a plurality of antenna elements, and a processor, wherein the processor is configured to control the user terminal for:
in acquisition mode after being turned on, broadening a field of regard, perceivable by the reconfigurable phased array antenna at a particular time instant, by spreading a beam width using a spoiled beam,
wherein the spoiled beam is based on changing a phase or an amplitude for a subset of antenna elements, of the plurality of antenna elements, to introduce a phase difference that alters a coherence of received signals to spread the beam width, and to increase a receiving area for an increased signal-to-noise ratio, and
wherein the reconfigurable phased array antenna is slewed to establish an initial pointing vector comprised of an azimuth and elevation prior to selecting the broadened field of regard, and the reconfigurable phased array antenna is not slewed once the broadened field of regard is selected;
receiving pilot signals from one or more satellites within the broadened field of regard using the reconfigurable phased array antenna;
selecting one of the one or more satellites based on a proximity, of the received pilot signals, to other signals, before terminating communication with a current satellite, of the one or more satellites, that has a communication established,
wherein the selected one of the one or more satellites is different from the current satellite;
switching to a directional mode for the reconfigurable phased array antenna,
wherein the reconfigurable phased array antenna is reconfigured to be directional towards the selected satellite by beamforming and to provide a higher gain; and
establishing communication with the selected one of the one or more satellites using the reconfigurable phased array antenna in the directional mode, for completing a satellite-to-satellite handover process.
12 . The method of claim 11 , wherein the field of regard of the reconfigurable phased array antenna is broadened using the spoiled beam by selecting a sub-array of two or more antenna elements of the reconfigurable phased array antenna to spread the beam width.
13 . The method of claim 11 , wherein the processor is further configured to control the user terminal for tracking the selected one of the one or more satellites by determining an initial pointing vector comprised of an azimuth and elevation and an initial tracking vector comprised of a flight path for the selected one of the one or more satellites relative to a current terrestrial or airborne location of the user terminal based on satellite ephemeris data for the selected one of the one or more satellites.
14 . The method of claim 11 , wherein the reconfigurable phased array antenna is stationary prior to broadening the field of regard.
15 . The method of claim 11 , wherein the processor is further configured to control the user terminal for broadening the field of regard by spreading the beam width using a single antenna element of the plurality of antenna elements.
16 . The method of claim 11 , wherein the pilot signals are received from one or more satellites within the broadened field of regard using only the subset of antenna elements, and
wherein switching to the directional mode is performed after the beam being spread.
17 . An apparatus for establishing communication with a signal source, comprising:
a reconfigurable phased array antenna, having a plurality of antenna elements; and
a processor configured to cause the apparatus to:
broaden, in acquisition mode after being turned on, a field of regard, perceivable by the reconfigurable phased array antenna at a particular time instant, by spreading a beam width using a spoiled beam,
wherein the spoiled beam is based on changing a phase or an amplitude for a subset of antenna elements, of the plurality of antenna elements, to introduce a phase difference that alters a coherence of received signals to spread the beam width, and to increase a receiving area for an increased signal-to-noise ratio, and
wherein the reconfigurable phased array antenna is slewed to establish an initial pointing vector comprised of an azimuth and elevation prior to selecting the broadened field of regard, and the reconfigurable phased array antenna is not slewed once the broadened field of regard is selected;
receive pilot signals from one or more satellites within the broadened field of regard using the reconfigurable phased array antenna;
select one of the one or more satellites based on a proximity, of the received pilot signals, to other signals, before terminating communication with a current satellite, of the one or more satellites, that has a communication established,
wherein the selected one of the one or more satellites is different from the current satellite;
switch to a directional mode for the reconfigurable phased array antenna,
wherein the reconfigurable phased array antenna is reconfigured to be directional towards the selected satellite by beamforming and to provide a higher gain; and
establish communication with the selected one of the one or more satellites using the reconfigurable phased array antenna in the directional mode, for completing a satellite-to-satellite handover process.
18 . The apparatus of claim 17 , wherein the field of regard of the reconfigurable phased array antenna is broadened using the spoiled beam by selecting a sub-array of two or more antenna elements of the reconfigurable phased array antenna to spread the beam width.
19 . The apparatus of claim 17 , wherein the selected one of the one or more satellites are tracked by determining an initial pointing vector comprised of an azimuth and elevation and an initial tracking vector comprised of a flight path for the selected one of the one or more satellites relative to a current terrestrial or airborne location of the apparatus based on satellite ephemeris data for the selected one of the one or more satellites.
20 . The apparatus of claim 17 , wherein the pilot signals are received from one or more satellites within the broadened field of regard using only the subset of antenna elements, and
wherein switching to the directional mode is performed after the beam being spread.