Method and apparatus for interacting with a communications system using radiated power adjusted according to an estimation of link-loss

• US 20060030350A1
• Filed: 07/20/2004
• Published: 02/09/2006
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Mitchell, James P.
• Granted Patent: US 7,865,132 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal

Abstract

Disclosed are a method and apparatus for interacting with a communications system. Interaction with the communications system occurs by identifying an access point. An estimate of link-loss from a mobile node to the access point is then determined. Also determined is an allowable power density limit proximate to the access point. A communications signal that is suitable for interacting with the communications system is generated. The level of the communications signal is adjusted according to the estimated link-loss and also according to the allowable power density limit. The level adjusted signal is then directed to the access point.

Claims

1. A method for interacting with a communications system from a mobile node comprising:

identifying an access point included in the communications system;

estimating a link-loss from the mobile node to the access point;

determining a power density limit proximate to the access point;

generating a communications signal for interacting with the communications system;

adjusting the power of the communications signal according to the power density limit and further according to the estimated link-loss; and

directing the power adjusted communications signal to the access point.

2. The method of claim 1 wherein identifying an access point comprises:

determining the location of the mobile node; and

selecting an access point from an enumeration of known access points according to the location of the mobile node.

3. The method of claim 1 wherein identifying an access point comprises:

determining a current location of the mobile node;

determining the speed and bearing of the mobile node;

projecting a first future location of the mobile node according to the speed and bearing; and

selecting a first access point from an enumeration of known access points according to the projected first future location of the mobile node.

4. The method of claim 3 further comprising:

projecting a second future location of the mobile node according to the speed and bearing;

selecting a second access point from an enumeration of known access points according to the second future location of the mobile node; and

conveying hand-off information to the second selected access point.

5. The method of claim 1 wherein estimating a link-loss comprises:

determining the location of the mobile node;

determining the location of the access point;

determining the distance from the mobile node to the access point according to the determined location of the mobile node and the determined location of the access point; and

calculating a link-loss according to the determined distance.

6. The method of claim 5 wherein determining the location of the mobile node comprises receiving a positioning-satellite position report.

7. The method of claim 5 wherein determining the location of the access point comprises consulting a-priori knowledge pertaining to the position of the access point.

8. The method of claim 5 further comprising:

ascertaining the existence of a degradation factor between the mobile node and the access point; and

adjusting the calculated link-loss according to the degradation factor.

9. The method of claim 5 further comprising:

receiving a received power indicator from the access point; and

adjusting the calculated link-loss according to the received power indicator.

10. The method of claim 1 wherein determining a power density limit proximate to the access point comprises at least one of receiving a power density limit indicator from the access point and consulting an a priori power density limit for the access point.

11. The method of claim 1 wherein directing the communications signal to the access point comprises:

determining a vector from the mobile node to the access point; and

steering the power adjusted communications signal according to the vector.

12. The method of claim 11 further comprising conveying mobile node location information to the access point.

13. A mobile node comprising:

access point selector capable of generating an access point identifier that represents a selected access point;

link-loss estimation unit capable of accepting the access point identifier and further capable of generating a link-loss signal that represents an estimate of link-loss between the mobile node and a selected access point;

power density determination unit capable of generating a maximum power density signal according to the access point identifier;

amplifier control unit capable of generating an amplifier control signal according to the link-loss signal and according to the maximum power density signal;

signal generator capable of generating a communications signal for interacting with an access point;

amplifier capable of adjusting the level of the communications signal according to the amplifier control signal; and

beam director capable of directing the level adjusted communications signal to an access point.

14. The mobile node of claim 13 wherein the access point selector comprises:

location interface capable of receiving a location indicator representative of a current location of the mobile node; and

access point table capable of providing an identifier for an access point according to a received current mobile node location indicator.

15. The mobile node of claim 13 wherein the access point selector comprises:

location interface capable of receiving a location indicator representative of a current location of the mobile node;

speed and bearing unit capable of generating a speed indicator and a bearing indicator for the mobile node according to two or more received current mobile node location indicators;

projection unit capable of generating a first future location indicator for the mobile node according to the speed and bearing indicators; and

access point table capable of generating a location indicator for an access point according to the first future location indicator.

16. The mobile node of claim 15 wherein the projection unit is further capable of generating a second future location indicator for the mobile node according to the speed and bearing indicators and wherein the access point table if further capable of generating a location indicator for an access point according to the second future location indicator.

17. The mobile node of claim 13 wherein the link-loss estimation unit comprises:

mobile node location interface capable of receiving a mobile node location indicator;

access point location unit capable of generating an access point location indicator according to an access point identifier received from the access point selector;

distance unit capable of generating a distance signal according to the mobile node location indicator and the access point location indicator; and

link-loss calculator capable of generating a link-loss signal according to the distance signal.

18. The mobile node of claim 17 wherein the mobile node position interface is capable of receiving a mobile node location indicator in the form of a positioning-satellite position report.

19. The mobile node of claim 17 wherein the access point location unit includes an access point table that is capable of storing a priori location indicators for a plurality of access points.

20. The mobile node of claim 17 wherein link-loss estimation unit further comprises a degradation identification unit capable of receiving a degradation factor report and selecting a degradation factor report according to the mobile node location indicator and the access point location indicator and wherein the link-loss calculator is further capable of adjusting the link-loss signal according to the degradation factor report.

21. The mobile node of claim 17 further comprising a feedback receiver capable of receiving a received-power indicator and wherein the link-loss calculator if further capable of adjusting the link-loss signal according to the received-power indicator.

22. The mobile node of claim 13 wherein the power density determination unit comprises at least one of a power-density limit receiver that is capable of generating a power density limit signal according to a received power-density limit indicator and a power-density limit table that is capable of storing a priori values of maximum power density for a plurality of access points and is further capable of generating a power density limit signal according to a value stored in the table and further according to an access point identifier received from the access point selector.

23. The mobile node of claim 13 wherein the beam director comprises:

mobile node location interface capable of receiving a mobile node location indicator;

access point location unit capable of generating an access point location indicator according to an access point identifier received from the access point selector;

vector unit capable of generating a vector signal according to the mobile node location indicator and the access point location indicator; and

steerable antenna capable of directing the level adjusted signal according to the vector signal.

24. The mobile node of claim 13 further comprising a position transponder capable of conveying the location of a location for the mobile node to an access point.