Communication system for aircrafts with altitude based antenna type selection

Abstract

A system and method for providing wireless data communication between a wireless communication system in an aircraft and a stationary communication server outside the aircraft are disclosed. The wireless communication system includes a plurality of antennas, and a router in the aircraft configured to transmit and receive wireless data communication to and from a stationary communication server outside the aircraft through at least one ground base station via at least one of the plurality of antennas. The plurality of antennas includes at least one omnidirectional antenna and at least one directional antenna. The router includes a control unit configured to restrict the wireless data communication to solely occur through the at least one directional antenna the when the current altitude of the aircraft is determined to be above a predefined altitude threshold value.

Claims

1. A wireless communication system for an aircraft, said wireless communication system comprising: a router connected to a plurality of antennas, wherein the router is configured to transmit and receive wireless data communication to and from a stationary communication server outside said aircraft through at least one ground base station via at least one antenna out of the plurality of antennas; an altitude determining unit configured to determine a current altitude of said aircraft; and a control unit, wherein said plurality of antennas comprises at least one omnidirectional antenna and at least one directional antenna; and wherein said control unit is operably connected to said altitude determining unit, said control unit being configured to restrict or disable the wireless data communication through said at least one omnidirectional antenna when the current altitude of said aircraft is above a certain altitude.

2. The wireless system of claim 1, wherein said router comprises the control unit configured to restrict said wireless data communication to solely occur through said at least one directional antenna when said current altitude of said aircraft is above a predefined altitude threshold value.

3. The wireless system according to claim 1, wherein the control unit is further configured to: evaluate a data link quality between said at least one ground base station and said at least one omnidirectional antenna; and disable or restrict said at least one omnidirectional antenna when said data link quality is below a predefined quality threshold value.

4. The wireless communication system according to claim 1, wherein said plurality of antennas are mounted to an external surface of said aircraft.

5. The wireless communication system according to claim 1, wherein said plurality of antennas are integrated in an external surface of said aircraft.

6. The wireless communication system according to claim 1, wherein said certain altitude is in the range of 200-5000 m.

7. The wireless communication system according to claim 1, wherein said certain altitude is a first altitude threshold value; and the control unit being further configured to: receive and store a second altitude threshold value which is lower than said first altitude threshold value, to restrict said wireless data communication to solely occur through said at least one omnidirectional antenna when the current altitude is determined to be below said second altitude threshold value.

8. The wireless communication system according to claim 1, wherein said plurality of antennas comprises at least two groups of directional antennas, each group comprising at least one directional antenna and each group being arranged to radiate and/or receive radio waves to and/or from sectors of a ground surface below the aircraft, the sectors being at least mostly non-overlapping.

9. The wireless communication system according to claim 1, wherein said aircraft comprises a first axis and a second axis transverse to said first axis, said first axis and second axis extending in a common horizontal plane and together define four sectors of the ground surface when projected onto the ground surface below the aircraft; wherein the plurality of antennas comprises four groups of directional antennas, each group comprising at least one directional antenna and each group being oriented to radiate and/or receive radio waves towards/from a separate sector, the sectors being at least mostly non-overlapping.

10. The wireless communication system according to claim 1, wherein said aircraft comprises a roll axis and a pitch axis which define four separate quadrant sectors when projected onto a ground surface below the aircraft; and wherein the plurality of antennas comprises four groups of directional antennas, each group comprising at least one directional antenna and each group being oriented to radiate and/or receive radio waves towards/from a separate quadrant sector.

11. The wireless communication system according to claim 1, wherein the plurality of antennas comprises at least two omnidirectional antennas distributed along a length of the aircraft.

12. The wireless communication system according to claim 1, wherein at least some of the antennas are orthogonal pair antennas.

13. The wireless communication system according to claim 12, wherein said orthogonal pair antennas are antenna pairs with orthogonal polarization.

14. A wireless communication system for an aircraft, said wireless communication system comprising: a router connected to a plurality of antennas, wherein the router is configured to transmit and receive wireless data communication to and from a stationary communication server outside said aircraft through at least one ground base station via at least one antenna out of the plurality of antennas, wherein said plurality of antennas comprises at least one omnidirectional antenna and at least one directional antenna; and wherein said wireless communication system is configured to restrict the wireless data communication through said at least one omnidirectional antenna when a current altitude of said aircraft is above a certain altitude, wherein said aircraft comprises a first axis and a second axis transverse to said first axis, said first axis and second axis extending in a common horizontal plane and together define four sectors of the ground surface when projected onto the ground surface below the aircraft, wherein the plurality of antennas comprises four groups of directional antennas, each group comprising at least one directional antenna and each group being oriented to radiate and/or receive radio waves towards/from a separate sector, the sectors being at least mostly non-overlapping, wherein said aircraft further comprises a vertical axis, a roll axis, and a pitch axis, and wherein said roll axis and vertical axis together define a first vertical plane, and wherein said pitch axis and vertical axis together define a second vertical plane intersecting said first vertical plane, wherein said first vertical plane and said second vertical plane together define four separate portions of a fuselage of the aircraft, and wherein said four groups of directional antennas are arranged at separate portions of said fuselage.

15. A method for wireless data communication between a wireless communication system in an aircraft and a stationary communication server outside the aircraft, said method comprising: providing a router within the aircraft, the router being connected to a plurality of antennas and configured to transmit and receive wireless data communication to and from the stationary communication server outside the aircraft through at least one ground base station via at least one antenna out of the plurality of antennas, wherein the plurality of antennas comprises at least one omnidirectional antenna and at least one directional antenna; providing the wireless communication system with an altitude determining unit configured to determine a current altitude of said aircraft, and a control unit; determining the current altitude of the aircraft using the altitude determining unit; and restricting or disabling, using the control unit, the wireless data communication through said at least one omnidirectional antenna when the current altitude of said aircraft is above a certain altitude.

16. The method of claim 15, wherein said restricting restricts said wireless data communication to solely occur through said at least one directional antenna when said current altitude of the aircraft is above a predefined altitude threshold value.

17. The method according to claim 15 further comprising: disabling wireless data communication via said at least one omnidirectional antennas when the current altitude is determined to be above said certain altitude.

18. The method according to claim 15, wherein said certain altitude is a first altitude threshold value, and wherein said method further comprises: disabling wireless data communication via said at least one directional antennas when the current altitude threshold value is below a second altitude threshold value, said second altitude threshold value being lower than said first altitude threshold value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

(2) FIG. 1 is a schematic side-view illustration of an aircraft having a wireless communication system in accordance with an embodiment of the present invention;

(3) FIG. 2 is a schematic side-view illustration of an aircraft having a wireless communication system, the aircraft being at an altitude below some predefined altitude threshold, in accordance with an embodiment of the present invention;

(4) FIG. 3a is a schematic side-view illustration of an aircraft having a wireless communication system, the aircraft being at an altitude above some predefined altitude threshold, in accordance with an embodiment of the present invention;

(5) FIG. 3b is a schematic top-view illustration of the aircraft in FIG. 3a;

(6) FIG. 4 is a schematic side-view illustration of an aircraft having a wireless communication system, the aircraft being at an altitude between two predefined altitude thresholds, in accordance with an embodiment of the present invention;

(7) FIG. 5 is a schematic flow chart representation of a method for wireless data communication in accordance with an embodiment of the present invention; and

(8) FIG. 6 is a schematic flow chart representation of a method for wireless data communication in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION

(9) In the following detailed description, preferred embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention. In the detailed embodiments described in the following are related to helicopters. However, it is to be acknowledged by the skilled reader that the method and system are correspondingly useable on other aircrafts, such as airplanes and the like.

(10) FIG. 1 is a schematic illustration of an aircraft 10, here in the form of a helicopter, having a wireless communication system 1 in accordance with an embodiment of the invention. The wireless communication system 1 has a data communication router 3 and a plurality of antennas 2a, 2b, 2c connected to the router 3. The router 3 is configured to receive and transmit data between an internal local area network (LAN) 15, and one or several external wide area networks (WANs). The external wide area networks are preferably cellular networks provided by one or more ground base stations (see e.g. ref. 6a, 6b, 6c in FIGS. 2-4).

(11) The system 1 comprises a plurality of antennas 2a-2c such as at least one omnidirectional antenna 2a (three in the illustrated embodiment), at least one directional antenna 2b (twelve in the illustrated embodiment) and optionally one or more satellite antennas 2c (one in the illustrated embodiment). The omnidirectional antennas 2a may for example be passive antennas such as e.g. omni monopole antennas or omni dipole antennas. The directional antennas 2b may for example be passive beam forming arrays having various polarizations. Moreover, each antenna 2a-2c may be realized as an antenna orthogonal pair by e.g. using a dual polarized antenna setup with a 90-degree angle between two linear polarizations or using circular left- and right handed polarizations. However, in alternative embodiments spatial diversity may be utilized to achieve orthogonal antenna diversity.

(12) The antennas 2a-2c may be mounted to an external surface of the aircraft 10, such as e.g. to the aircraft's 10 fuselage 11. However, the antennas 2a-2c may also be integrated in the external surface of the aircraft 10. A combination of these two is also feasible.

(13) The router 3 further has a plurality of modems 9, where each antenna 2a-2c, or each antenna orthogonal pair, preferably is assigned and connected to a separate modem 9. In case of the latter each modem 9 is preferably provided with 2 antenna ports for connection to each orthogonal antenna pair. However, each modem may also be provided four or more ports for compliance with MIMO (Multiple Input Multiple Output) systems. Even though only 3 modems are shown in the illustration it is apparent for the skilled reader that the router 3 may include a larger number of modems 9, and that this was avoided in order to avoid cluttering in the drawings. More specifically, in the embodiment illustrated in FIG. 1 with 3 omnidirectional antennas 2a, 12 directional antennas 2b and 1 satellite antenna 2c the router preferably comprises 15 modems.

(14) Further, the router 3 has a control unit 8 (e.g. a microprocessor) configured to restrict the wireless data communication to solely occur through the directional antennas 2b, when a current altitude of the aircraft 10 is above a predefined altitude threshold value (see e.g. FIG. 3a). The control unit 8 is preferably realized as a software controlled processor. However, the control unit 8 may alternatively be realized wholly or partly in hardware. Further, the control unit 8 may for example be configured to evaluate a data link quality between the ground base station(s) and each omnidirectional antenna 2a. If the data link quality is too poor and below a predefined quality threshold, e.g. due to high signal interference, the control unit is configured to disable the omnidirectional antennas 2a (e.g. by disabling the modems 9 associated with the omnidirectional antennas 2a) and thereby restrict the communication to occur solely through the directional antennas 2b.

(15) However, the router 3 may alternatively be provided with an altitude determining unit 7 configured to determine a current altitude of the aircraft 10. The altitude determining unit 7 is preferably configured to continuously monitor and determine the altitude of the aircraft, and may for example be a Global Navigation Satellite System, GNSS, provided within the router 3, such as e.g. GPS, GLONASS, Galileo system, BeiDou system, etc. By providing a GNSS internally within the router 3, installation of the wireless communication system 1 is facilitated as there is no need for establishing an operational connection between the aircraft's 10 internal altimeter (not shown) and the router. Moreover, the inventive system 1 may thereby easily be retrofitted into existing aircrafts 10. Thus, the control unit 8 may accordingly be connected to the altitude determining unit 7, and configured to disable wireless data communication with the omnidirectional antennas 2a when the current altitude of the aircraft 10 is determined to be above a predefined altitude threshold value.

(16) The altitude threshold value may be any value in the range of 500 m to 1500 m, such as for example, 600 m, 700 m, 800 m, 900 m, 1000 m, 1100 m, 1200 m, 1300 m or 1400 m. In particular, it is preferred that the height at which the communication through the omnidirectional antenna(s) is restricted or disabled is in the range of 200-5000 m, and preferably 500-3000 m, and most preferably 500-1500 m.

(17) However, the control unit 8 may be configured to store a plurality of altitude threshold values. In more detail, the control unit 8 may be configured to receive two altitude threshold values, a first altitude threshold value (e.g. 1000 m) above which, the wireless data communication solely occurs through the directional antennas 2a (see e.g. FIGS. 3a-3b), and a second altitude threshold value (e.g. 500 m) below which, the wireless data communication solely occurs through the omnidirectional antennas 2a (see e.g. FIG. 2). Moreover, the control unit 8 may be configured to allow wireless data communication to occur through any suitable antenna 2a-2b, if the current altitude of the aircraft 10 is determined to be between the aforementioned two threshold values, as e.g. illustrated in FIG. 4.

(18) FIG. 2 schematically illustrates an aircraft 10 from a side-view perspective, having a wireless communication system 1 according to an embodiment of the invention. In more detail, the control unit 8 has determined that the current altitude is below a predefined threshold value (e.g. by means of the altitude determining unit 7 or radio link evaluation) and therefore disabled the directional antennas 2b, in order to restrict the wireless data communication between the router and the ground base stations 6a-6c to solely occur through the omnidirectional antennas 2a. The “radio wave beams” for the omnidirectional antennas 2a are schematically indicated by the broken lines 21a-21c.

(19) In each of the embodiments illustrated in FIGS. 2, 3a, 3b and 4, the system 1 is arranged to be compatible with three different cellular network operators which are represented by a corresponding ground base station 6a, 6b and 6c respectively. Therefore, each system 1 in these embodiments comprises three omnidirectional antennas 2a, and each group of directional antennas 2b has three directional antennas 2b. Further, the plurality of omnidirectional antennas 2a are preferably distributed along a length of the aircraft, and the directional antennas 2b are preferably arranged in individual groups in order to target non-overlapping sectors of the ground surface below the aircraft 10.

(20) FIG. 3a schematically illustrates the aircraft 10 from FIG. 2b, however, at a higher altitude. More specifically, it serves to illustrate how the wireless communication system 1 operates when the aircraft 10 is determined to be above a predefined altitude threshold (illustratively indicated by the meter in the altitude determining unit 7). Here, the omnidirectional antennas 2a have been disabled, or more specifically, wireless data communication via the omnidirectional antennas 2a has been disabled. Thus, the wireless data communication is restricted to solely occur through the directional antennas 2b, as schematically indicated by the “radio wave beams” 22.

(21) Moreover, the directional antennas 2b are arranged in separate groups 12a-12d in order to target specific sectors of the ground surface below the aircraft 10. In more detail, the wireless communication system 1 comprises four groups 12a-12d of directional antennas 2b, each group being arranged or oriented to radiate and/or receive radio waves to and/or from non-overlapping sectors of the ground surface below the aircraft 10.

(22) As is more clearly illustrated in FIG. 3b, the aircraft comprises a first axis 101 (roll axis) and a second axis 102 which is transverse to the first axis 101. The two axes 101, 102 both extend in a common horizontal plane and together define four non-overlapping sectors 31a-31d of the ground surface below the aircraft 10. Accordingly, each group 12a-12d of directional antennas 2b is arranged or oriented to radiate and/or receive radio wave towards/from a respective non-overlapping sector 31a-31d. In the illustrated embodiment, the second axis 102 is perpendicular to the first axis 101 and may be construed as a pitch axis, however, the skilled reader realizes that the second axis 102 need to be perfectly perpendicular to the first axis 101 in order to achieve the desired effect.

(23) Moreover, the aircraft 10 further has a vertical axis (not shown) which together with the first axis 101 defines a first vertical plane, and together with the second axis 102 defines a second vertical plane which intersects the first vertical plane. The two planes effectively define four separate portions of the aircraft's fuselage 11. Each group 12a-12d of directional antennas 2b is arranged at a respective portion of the aircraft's fuselage 11 in order to provide sufficient separation between different antenna groups and utilize the fuselage 11 to reduce the chance of beams 22 overlapping between different groups 12a-12d.

(24) FIG. 5 is a schematic flow chart representation of a method for wireless data communication between a wireless communication system in an aircraft and a stationary communication server outside the aircraft, in accordance with an embodiment of the invention.

(25) Firstly, a router is provided within the aircraft. The router may be any router according to any of the above discussed embodiments of the inventive wireless communication system. The router is connected to a plurality of antennas and configured to transmit and receive wireless data communication to and from the stationary communication server outside the aircraft through at least one ground base station via at least one of the antennas. Moreover, the plurality of antennas comprises one or more omnidirectional antennas and one or more directional antennas.

(26) Next, an altitude of the aircraft is monitored/determined, S401. When the current altitude is determined by an altitude determining unit or any control unit of the router, a check is performed, S402, to see whether the determined altitude of the aircraft is above or below a predefined altitude threshold value. If it is determined that the altitude of the aircraft is above the predefined altitude threshold value, the omnidirectional antenna(s) is/are disabled, S403, in order to restrict the wireless data communication to solely occur through the directional antenna(s).

(27) However, if it would have been determined that the altitude of the aircraft was below the predefined altitude threshold value, a check is performed, S404, to see if the omnidirectional antenna(s) is/are enabled. If all the statement is true, then one goes back to monitoring/determining, S401, the altitude of the aircraft, if the omnidirectional antenna(s) is/are disabled, one preferably enables all of the available omnidirectional antennas, S405, and then returns back to monitoring/determining, S401, the altitude of the aircraft.

(28) In FIG. 6 another flow chart representation of a method for wireless data communication in accordance with another embodiment of the present invention is illustrated. In this particular embodiment, there are two different altitude threshold values provided in order to make the method more dynamic and agile. More specifically, the method illustrated in FIG. 6 enables for better utilization of the specific advantageous characteristics of the two different antenna types as they differ in performance at different altitudes. Similar to the method described in reference to FIG. 5, a router according to any of the previously discussed embodiments of the invention is provided, and the altitude of the aircraft is monitored/determined, S501 (e.g. by an altitude determining unit).

(29) Further, a check is performed, S502a, to see if the altitude of the aircraft is above or below a first altitude threshold value (e.g. above 1300 m). If it is determined that the aircraft's altitude is above the first altitude threshold (i.e. the aircraft is currently at high altitude), the omnidirectional antenna(s) is/are disabled, S504, or at least they are not available for receiving and transmitting radio signals.

(30) However, if it would have been determined that the aircraft's altitude was below the first threshold, the method includes a step of determining, S502b, if the altitude of the aircraft is above or below a second altitude threshold level (e.g. above or below 600 m). If it is determined to be below the second altitude threshold value (i.e. the aircraft is currently at low altitude) then the directional antenna(s) is/are disabled.

(31) Further, if it would have been determined/concluded that the aircraft's altitude was above the second altitude threshold (i.e. the aircraft is currently at mid altitude), then the method preferably comprises a step of checking, S505, if all antennas are enabled. If all antennas are enabled, go back to monitoring/determining, S501, the altitude, if not, then all antennas are enabled or at least made available for wireless data communication between the aircraft the external ground base stations.

(32) The invention has now been described with reference to specific embodiments. However, several variations of the communication system are feasible. For example, the control unit may restrict communication to certain frequency bands at certain altitude ranges, the number of modems may vary, and so on. Such and other obvious modifications must be considered to be within the scope of the present invention, as it is defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word “comprising” does not exclude the presence of other elements or steps than those listed in the claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.