Hierarchical set of frequency reuse patterns allowing cellular air and land communication

• US 5,848,359 A
• Filed: 11/03/1997
• Issued: 12/08/1998
• Est. Priority Date: 09/08/1995
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Furtaw, Robert W.
• Primary Examiner(s): Hudspeth, David R.
• Assistant Examiner(s): ABEBE, DANIEL DEMELASH
• Application Number:
  US08/963,323
• Time in Patent Office: 400 Days
• Field of Search: 455/447, 455/446, 455/428, 455/422, 455/431
• US Class Current: 455/447
• CPC Class Codes: H04B 7/18506 Communications with or from aircraft, i.e. aeronautical mobile service
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

A cellular system (FIG. 4) is expanded to allow communication between mobile ground-based units (70 and 72) and mobile air-based units (80 and 78) where the air base units (e.g., a unit in airplane 78) operate above a threshold elevation. Mobile units below the threshold elevation level use local conventional cellular service area and cells whereas mobile units above the threshold are transferred to a frequency reuse pattern having a higher altitude of service and a larger service surface area. Switching between the air cells (41a-41g) and the land cells (26) is performed by determining if two land cell controllers operate at a same frequency both are receiving transmission from the mobile unit. If two land cells of the same frequency receive the same mobile unit transmission, then the mobile unit is above the threshold elevation and assigned to an air cell, else a land cell is used.

Claims

1. A method for using an appropriate frequency reuse pattern based upon altitude, the method comprising the steps of:

receiving a first message from a first source containing control information in a first cell within a service area;

monitoring the first cell and a second cell, the first cell and the second cell being non-adjacent and operating at the same frequency, to determine if the first message is received by both the first cell and the second cell, wherein the first source is operating above a predetermined elevation when the first message is received by both the first cell and the second cell; and

transmitting a second message to the first source informing the first source to change frequency to a new frequency which is part of a new reuse pattern.

2. The method of claim 1 wherein the step of transmitting comprises:

transferring a handling of a communication from the source from the first cell to a second cell wherein the first and second cells have different service area.

3. The method of claim 2 wherein the step of transferring comprises:

transferring the handling of the communication from the source from the first cell to a second cell wherein the second cell has a service area larger than the service area of the first cell.

4. The method of claim 1 wherein the step of transmitting comprises:

transferring a handling of a communication from the first source from the first cell to a third cell wherein the first and third cells operate at a different frequency.

5. The method of claim 4 wherein the step of transmitting comprises:

providing a plurality of cells which surround the third cell, the plurality of cells operating at a frequency different from the third cell and having service areas larger than the first and second cells.

6. The method of claim 5 wherein the step of providing comprises:

switching from the third cell to a fourth cell which is within the plurality of cells, the fourth cell being adjacent the third cell and having a service area which is larger than the service area of either the first or second cell.

7. The method of claim 4 wherein the step of transmitting comprises:

switching from the first cell to the third cell in the communication system so that the source located on an airplane can converse with a cellular phone located at a location other than the airplane.

8. The method of claim 1 wherein the step of transmitting comprises:

transferring a handling of a communication from the first source to a second cell wherein the first cell controls transmissions when the transmissions are originated from below the predetermined elevation and the second cell controls transmissions when the transmissions are originated from above the predetermined elevation.

9. The method of claim 1 wherein the step of communicating comprises:

communicating between the first and second cells wherein the first and second cells are part of a larger plurality of cells which use many different frequencies for processing transmissions, each cell in the plurality of cells which uses the same frequency being adjacent no other cell using the same frequency but instead being surrounded by cells having a different frequency.

10. A method for assigning a handling of a transmission to one network node within a plurality of network nodes in a communication system, the method comprising the steps of:

receiving at least a portion of the transmission in a first network node of the communication system, the first network node having a first area of transmission coverage;

determining if a second non-adjacent network node having the same frequency as the first network node detects the transmission simultaneously with the first network node; and

transferring, when the second network node and the first network node detect the transmission, the handling of the transmission from the first network node to a third network node wherein the third network node has a second area of transmission coverage which is greater in area than the first area of transmission coverage.

11. The method of claim 10 wherein the step of determining comprises:

providing first and second network nodes which operate at a same frequency.

12. The method of claim 11 wherein the step of providing comprises:

providing first and second network nodes which are physically separated by a fourth network node wherein the fourth network node operates at a frequency different from the first and second network nodes.

13. The method of claim 10 wherein the step of receiving at least a portion of the transmission in a first network node comprises:

receiving the transmission in a first network node wherein the first and second network nodes are positioned in a first frequency reuse pattern wherein the communication system contains several nodes, including the first and second nodes, which operate at a same frequency wherein no two nodes operating on the same frequency are directly adjacent one another.

14. The method of claim 13 wherein the step of transferring comprises:

transferring to the third network node wherein the third network node is located within a second frequency reuse pattern having a larger total reuse coverage area than the first frequency reuse area.

15. The method of claim 10 wherein the step of transferring comprises:

transferring to the third network node wherein the third network node is located within a first frequency reuse pattern wherein the communication system contains several nodes, which includes the third node, which operate at a same frequency wherein no two nodes operating on the same frequency are directly adjacent one another and all nodes operating on the same frequency are adjacent at least one different node operating at a different frequency.

16. The method of claim 10 wherein the step of transferring comprises:

transferring to the third network node wherein the third network node handles transmission originating above a certain altitude and the first and second nodes handle transmission originating below the certain altitude.

17. The method of claim 10 wherein the step of transferring comprises:

communicating control signals to a source of the transmission to inform the source to change frequencies so that communication can occur between the third network node and the source.

18. A method for dynamically routing control of a transmission between a plurality of network nodes in a communication system, the method comprising the steps of:

receiving the transmission from a source and initially processing a first portion of the transmission through a first network node of the communication system;

determining when the source exceeds a predetermined elevation by detecting wherein two cell receivers receive a common signal to determine when the source of the transmission rises above a certain altitude; and

transferring, when the source rises above the certain altitude, the transmission to a second network node in the plurality of network nodes wherein the second network node handles a second portion of the transmission which follows the first portion of the transmission.

19. The method of claim 18 further comprising the steps of:

further monitoring the elevation of the source after the source has risen above the certain altitude, the further monitoring being used to detect when the source of the transmission is received by two receiving cells having the same frequency; and

transferring, when the source falls below the certain altitude, the transmission to a second network node in the plurality of network nodes wherein the second network node handles a second portion of the transmission which follows the first portion of the transmission.