Satellite radio access network (SAT RAN) beam and gateway seamless handover
A LEO satellite communication system is in communication with a first setting satellite having a first field of view including a first plurality of cells, and a second rising satellite having a second field of view including a second plurality of cells. The first and second satellites have an overlapping field of view having an overlapping plurality of cells located therein. A first processing device has a first communication port communicating with a first cell of the first plurality of cells via said first antenna over a first beam, and a second communication port communicating with an overlapping cell of the overlapping plurality of cells via said second antenna over a second beam. Said first processing device switches from said first communication port to said second communication port in response to the first cell of the first plurality of cells moving into the overlapping field of view.
1. A satellite communication handover system configured for communication with a first setting satellite having a first field of view including a first plurality of cells in which an active User Equipment (UE) is located that is in direct communication with the first setting satellite, and also configured for communication with a second rising satellite having a second field of view, the first and second satellites having an overlapping field of view where the first field of view overlaps with the second field of view, and an overlapping plurality of cells located in the overlapping field of view, the overlapping plurality of cells including a cell in which the active UE is located, the satellite communication handover system comprising:
a first feeder link and a first tracking antenna configured to communicate with the active UE via the first setting satellite directly serving the first plurality of cells and a second feeder link and a second tracking antenna configured to communicate with the second rising satellite serving the active UE directly in the second plurality of cells;
a processing device configured to communicate with the active UE to control the active UE to communicate directly with the second rising satellite; and
a gateway configured to perform delay normalization so that a UE at a cell center has its timing advance (TA) equal to a midpoint TA value.
2. The satellite communication handover system of claim 1 , wherein the processing device is configured to start or end beam handover in response to an instruction signal from at least one of the first setting satellite and the second rising satellite.
3. The satellite communication handover system of claim 1 , wherein:
the active UE is able to communicate directly with the first setting satellite over a first service link beam; and
the active UE is able to communicate directly with the second rising satellite over a second service link beam.
4. The satellite communication handover system of claim 3 , wherein:
the first antenna is configured to communicate with the first setting satellite over a first feeder link beam; and
the second antenna is configured to communicate with the second rising satellite over a second feeder link beam.
5. The satellite communication handover system of claim 1 , wherein the processing device is further configured to control the active UE to cease communicating with the first setting satellite.
6. The satellite communication handover system of claim 4 , wherein the first antenna is configured to stop communicating with the first setting satellite.
7. The satellite communication handover system of claim 1 , wherein the processing device is configured to:
communicate with the active UE with a first physical cell ID (PCI) and via the first setting satellite; and
communicate with the active UE with a second PCI and via the second rising satellite, when the active UE becomes visible in the overlapping field of view.
8. The satellite communication handover system of claim 1 , wherein the first feeder link and first tracking antenna are part of a base station, and wherein one to one mapping of the base station with a serving cell is kept via tracking of fixed cells while either the first or the second satellite passes the fixed cells dynamically at a speed of between 7-8 km/s.
9. The satellite communication handover system of claim 1 , further comprising:
a gateway configured to perform delay normalization and Doppler compensation to the center of each cell dynamically.
10. The satellite communication handover system of claim 1 , the first feeder link and the first tracking antenna being at a base station, the system being configured to:
perform seamless beam handover with two physical cell identities (PCIs) assigned to two radio-frequency (RF) ports that serve as first and second communication ports respectively,
generate two radio-frequency (RF) downlink signals, each carrying one of the two PCIs assigned, and
form two beams and overlay the two beams on an overlapping cell for beam or cell handover, via the first setting satellite and the second rising satellite, wherein:
two PCIs are selected so that they are orthogonal to each other, to avoid interference, and MIMO principles apply so that the two overlapping handover beams work together without interfering with each other; and
the two PCIs are PCIs for the same or different cell bandwidth, so that beam handover with the same and different cell bandwidth are both supported.
11. The satellite communication handover system of claim 1 , wherein the satellite communication handover system:
is configured to relay 3GPP downlink and uplink signal between the first feeder link and first tracking antenna; and
is configured to provide 3GPP RAN coverage to a remote place that is not covered by a constellation of LEO satellites.
12. The satellite communication handover system of claim 1 , wherein the satellite communication handover system achieves beam handover for serving the active UE by a 3GPP handover process without any modification on the active UE.
13. The satellite communication handover system of claim 1 , wherein the first feeder link and the first tracking antenna are at a base station, and the base station includes at least one of a BTS, an eNodeB, or a gNodeB.
14. The satellite communication handover system of claim 1 , further comprising the first settling satellite and the second rising satellite, wherein each of the first setting satellite and the second rising satellite has a large phase array that is configured to form at least one hundred electronically steerable beams in order to serve at least one hundred cells.
15. The satellite communication handover system of claim 1 , wherein the satellite communication handover system is configured to perform delay and Doppler compensation for each beam to normalize delay to a constant amount.
16. The satellite communication handover system of claim 1 , wherein the satellite communication handover system further includes a satellite network control center (NCC) that is configured to orchestrate communication operations of a base station, a ground gateway site, and the first and second satellites and wherein satellite radio access network (RAN) base station receive (Rx) scheduling is modifiable with a delay.
17. A satellite communication handover system configured for communication with a first setting satellite having a first field of view including a first plurality of cells in which an active User Equipment (UE) is located that is in direct communication with the first setting satellite, and also configured for communication with a second rising satellite having a second field of view, the first and second satellites having an overlapping field of view where the first field of view overlaps with the second field of view, and an overlapping plurality of cells located in the overlapping field of view, the overlapping plurality of cells including a cell in which the active UE is located, the satellite communication handover system comprising:
a first feeder link and a first tracking antenna configured to communicate with the active UE via the first setting satellite directly serving the first plurality of cells and a second feeder link and a second tracking antenna configured to communicate with the second rising satellite serving the active UE directly in the second plurality of cells; and
a processing device configured to communicate with the active UE to control the active UE to communicate directly with the second rising satellite;
wherein the first setting satellite and the second rising satellite are transparent and configured to directly communicate with a modified base-station low PHY and un-modified standard 3GPP compliant UEs.
18. A satellite communication handover system configured for communication with a first setting satellite having a first field of view including a first plurality of cells in which an active User Equipment (UE) is located that is in direct communication with the first setting satellite, and also configured for communication with a second rising satellite having a second field of view, the first and second satellites having an overlapping field of view where the first field of view overlaps with the second field of view, and an overlapping plurality of cells located in the overlapping field of view, the overlapping plurality of cells including a cell in which the active UE is located, the satellite communication handover system comprising:
a first feeder link and a first tracking antenna configured to communicate with the active UE via the first setting satellite directly serving the first plurality of cells and a second feeder link and a second tracking antenna configured to communicate with the second rising satellite serving the active UE directly in the second plurality of cells; and
a processing device configured to communicate with the active UE to control the active UE to communicate directly with the second rising satellite;
wherein the system is configured to support a configurable fixed round trip latency, and to set one or more timers accordingly related to a long RF path delay.
19. A satellite communication handover system configured for communication with a first setting satellite having a first field of view including a first plurality of cells in which an active User Equipment (UE) is located that is in direct communication with the first setting satellite, and also configured for communication with a second rising satellite having a second field of view, the first and second satellites having an overlapping field of view where the first field of view overlaps with the second field of view, and an overlapping plurality of cells located in the overlapping field of view, the overlapping plurality of cells including a cell in which the active UE is located, the satellite communication handover system comprising:
a first feeder link and a first tracking antenna configured to communicate with the active UE via the first setting satellite directly serving the first plurality of cells and a second feeder link and a second tracking antenna configured to communicate with the second rising satellite serving the active UE directly in the second plurality of cells;
a processing device configured to communicate with the active UE to control the active UE to communicate directly with the second rising satellite; and
a long distance fronthaul that is configured to uses a fiber link to enable gateway site diversity and enlarge gateway field of view and footprint; and
wherein fiber latency is encapsulated into delay compensation.