In-flight cellular communications system coverage of mobile communications equipment located in aircraft

Patent metadata

Field	Value
Publication number	US-9813969-B2
Application number	US-201514931057-A
Country	US
Kind code	B2
Filing date	Nov 3, 2015
Priority date	Nov 3, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A network node of a terrestrial cellular system provides telecommunications service to a user equipment (UE) in an airborne aircraft. Navigation information transmitted from the aircraft is periodically acquired, including aircraft identity, position, altitude, and a time of determining aircraft position. A link is maintained between the network node and the UE by transmitting beam steered, Doppler shift compensated downlink signals, and by performing beam steered reception of uplink signals. Beam steering is directed toward the aircraft based on the navigation information. Doppler shift compensation is adapted to compensate for a Doppler shift such that the UE experiences a nominal carrier frequency when receiving transmissions from the antenna nodes. Handover from a first to a second coverage area includes using a same cell identifier and a same frequency allocation in the second coverage area as are used in the first.

First claim

What is claimed is:

1. A method of providing cellular telecommunications system service to a user equipment situated in a first aircraft that is in-flight, wherein the method is performed by a first network node of a terrestrial cellular telecommunications system, the method comprising:
periodically acquiring, via an aircraft navigation broadcast receiver, acquired navigation information transmitted from the first aircraft, wherein the acquired navigation information comprises:
an identity of the first aircraft;
a position of the first aircraft;
an altitude of the first aircraft; and
a time value indicating when the position of the first aircraft was determined;

maintaining a first link between the first network node and the user equipment by transmitting beam steered, Doppler shift compensated downlink signals, and by performing beam steered reception of uplink signals, wherein beam steering is directed toward the first aircraft based on the periodically acquired navigation information, and wherein Doppler shift compensation is based on one or more determinations of relative velocity between the first aircraft and one or more first antenna nodes associated with the first network node, and is adapted to compensate for a Doppler shift experienced by the user equipment such that the user equipment experiences a nominal carrier frequency when receiving transmissions from the one or more first antenna nodes;
detecting that the first aircraft will be leaving a first coverage area that is served by the one or more first antenna nodes and will be entering a second coverage area that is served by one or more second antenna nodes, and responding by causing the one or more second antenna nodes to provide a second link between the user equipment and the one or more second antenna nodes using a same cell identifier and a same frequency allocation to the user equipment as are being used for the first link so that handover from the one or more first antenna nodes to the one or more second antenna nodes is carried out without informing the user equipment.

2. The method of claim 1 , comprising:
fine-tuning beam-forming for downlink transmissions by using two partially overlapping beams for uplink reception and determining therefrom whether accuracy of prediction of position and altitude of the first aircraft can be improved.

3. The method of claim 1 , comprising:
fine-tuning beam-forming for downlink transmissions by perturbing a present prediction of position and altitude of the first aircraft in a controlled manner and detecting whether uplink reception improves or degrades, and adjusting a beam-forming prediction model based on said detecting.

4. The method of claim 1 , comprising:
serving, via a third link, a second user equipment situated in a second aircraft that is in-flight, wherein the third link is supported by a beam of downlink transmissions and beam-steered reception of uplink transmissions, all directed at the second aircraft, and
wherein the third link uses a different cell identifier than is being used for the first link.

5. The method of claim 4 , comprising:
in response to the beam of downlink transmissions and beam-steered reception of uplink transmissions directed at the second aircraft being oriented in a same direction as a beam of downlink transmissions and beam-steered reception of uplink transmissions directed at the first aircraft, employing carrier aggregation techniques in which:
the beam of downlink transmissions and beam-steered reception of uplink transmissions directed at the first aircraft is associated with a first set of spectral resources;
the beam of downlink transmissions and beam-steered reception of uplink transmissions directed at the second aircraft is associated with a second set of spectral resources, different from the first set of spectral resources;
the first set of spectral resources are allocated as primary cell resources to the user equipment aboard the first aircraft and are allocated as secondary cell resources to the user equipment aboard the second aircraft; and
the second set of spectral resources are allocated as primary cell resources to user equipment aboard the second aircraft and are allocated as secondary cell resources to user equipment aboard the first aircraft.

6. The method of claim 1 , comprising:
prior to activating transmission of beam steered, Doppler shift compensated downlink signals, periodically acquiring, via the aircraft navigation broadcast receiver, initially acquired navigation information transmitted from the first aircraft;
predicting, from the initially acquired navigation information, that the aircraft will, at a predicted time, enter an outer perimeter of the coverage area that is under control of the network node; and
activating the maintaining of the first link at the predicted time.

7. The method of claim 6 , wherein activating the maintaining of the first link at the predicted time comprises:
using the identity of the first aircraft to determine whether the first aircraft is to be served when crossing the outer perimeter of the coverage area that is under control of the network node.

8. The method of claim 1 , comprising:
determining, from the relative velocity of the first aircraft towards the one or more first antenna nodes, a Doppler shift predicted to be experienced by the one or more first antenna nodes when receiving signals transmitted by the user equipment; and
applying Doppler shift compensation to a random access preamble received from the user equipment, wherein the applied Doppler shift compensation is based on the Doppler shift predicted to be experienced by the one or more first antenna nodes when receiving signals transmitted by the user equipment.

9. The method of claim 1 , comprising:
detecting an amount of Doppler shift in a random access preamble received from the user equipment; and
applying Doppler shift compensation to the random access preamble received from the user equipment, wherein the applied Doppler shift compensation is based on the detected amount of Doppler shift in the random access preamble received from the user equipment.

10. The method of claim 1 , comprising:
ceasing maintenance of the first link in response to one or more of:
the first network node detecting that the first aircraft has left the outer perimeter of the coverage area that is under control of the first network node; and
the first network node no longer receiving navigation information from the aircraft.

11. The method of claim 1 , comprising:
serving, via a second link, a second user equipment situated in a second aircraft that is in-flight, wherein the second link is supported by a beam of downlink transmissions and beam-steered reception of uplink transmissions, all directed at the second aircraft, and
wherein:
the beam of downlink transmissions and beam-steered reception of uplink transmissions, all directed at the second aircraft does not overlap with a beam of downlink transmissions and beam-steered reception of uplink transmissions directed at the first aircraft; and
a cell identifier used for the first link is the same as a cell identifier used for the second link.

12. An apparatus for providing cellular telecommunications system service by a first network node of a terrestrial cellular telecommunications system to a user equipment situated in a first aircraft that is in-flight, the apparatus comprising:
circuitry configured to periodically acquire, via an aircraft navigation broadcast receiver, acquired navigation information transmitted from the first aircraft, wherein the acquired navigation information comprises:
an identity of the first aircraft;
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Assignees

• Ericsson Telefon Ab L M
• ERICSSON TELEFON AB L M (publ)

Inventors

• Axmon Joakim
• Alriksson Peter
• Ekelund Bjorn
• Lindoff Bengt

Classifications

• H04W72/20

  Control channels or signalling for resource management · CPC title

• H04W4/42

  for mass transport vehicles, e.g. buses, trains or aircraft · CPC title

• H04W84/06

  Airborne or Satellite Networks (space-based or airborne stations H04B7/185) · CPC title

• H04W16/28

  using beam steering · CPC title

• H04B7/18506 Primary

  Communications with or from aircraft, i.e. aeronautical mobile service · CPC title