System and methods for controlling access to digital wireless network in a dual mode wireless system

• US 6,246,886 B1
• Filed: 12/21/1998
• Issued: 06/12/2001
• Est. Priority Date: 12/21/1998
• Status: Expired due to Term

• Current Assignee: Bell Atlantic Mobile Systems Incorporated (Verizon Communications Inc.)
• Original Assignee: Bell Atlantic Mobile (Verizon Communications Inc.)
• Inventors: Oliva, Eugene A.
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/217,247
• Time in Patent Office: 904 Days
• Field of Search: 455/552, 455/553, 455/453, 455/450, 455/454, 455/426, 455/436, 455/443, 455/502, 455/509, 455/422, 455/69, 455/68, 370/329, 370/335, 370/342
• US Class Current: 455/426.1
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 74/00 Wireless channel access
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: H04W 99/00 Subject matter not provided for in other groups of this subclass

Abstract

A dual-mode wireless communication system, having a AMPS-based wireless system and a CDMA-based wireless communication system is configured for transmitting digital wireless telephone signals by selectively transmitting a sync channel into a selected propagation region at a power level that is undetectable by digital telephones located within the selected propagation region. The transmission of the sync channel signal at the undetectable power level causes the dual-mode digital telephone to search for the alternative AMPS-based analog system, limiting access by the dual-mode digital telephones. Hence, the dual-mode wireless communication system can limit access to the digital communication system, for example, to prevent the occurrence of hard handoff with an adjacent analog system, or to reduce usage in a congested sector.

Claims

1. A method of establishing a dual mode wireless telephone system adjacent to another wireless telephone system having a prescribed wireless protocol, the method comprising:

establishing a first wireless telephone system in prescribed coverage areas using the prescribed wireless protocol for communication with dual mode wireless telephones in the prescribed coverage areas according to the prescribed wireless protocol; and

establishing a digital wireless system, overlying the prescribed coverage areas of the first wireless system, for communication with the dual mode wireless telephones according to a prescribed digital wireless protocol, including;

(1) transmitting a sync channel signal into a first region of the prescribed coverage areas according to the prescribed digital wireless protocol and at a first power level sufficient for detection by a first of the dual mode wireless telephones in the first region, and

(2) transmitting the sync channel signal into a second region of the prescribed coverage areas, having a boundary between the prescribed coverage areas and the another wireless telephone system, according to the prescribed digital wireless protocol and at a reduced power level that renders the sync channel signal undetectable by a second of the dual mode wireless telephones located substantially at the boundary.

2. The method of claim 1, wherein the step of transmitting the sync channel signal in the first region comprises:

sending a first command from an executive call processor, configured for controlling transmission of the sync channel signal into the prescribed coverage areas, specifying the first power level to a first channel element configured for controlling transmission of the sync channel signal into the first region; and

controlling by the first channel element a first base station transceiver for transmission of the sync channel signal into the first region at the first power level.

3. The method of claim 2, wherein the step of transmitting the sync channel signal into the second region comprises:

sending a second command from the executive call processor specifying the second power level to a second channel element configured for controlling transmission of the sync channel signal into the second region; and

controlling by the second channel element a second base station transceiver for transmission of the sync channel signal into the second region at the second power level.

4. The method of claim 3, further comprising setting the second power level in the executive call processor via a maintenance terminal in communication with the executive call processor.

5. The method of claim 3, wherein the step of transmitting the sync channel signal into the second region further includes transmitting the sync channel signal into a prescribed sector of a cell in a cellular system, the prescribed sector corresponding to the second region.

6. The method of claim 1, wherein the step of transmitting the sync channel signal into the first region includes reducing the transmitted power level from the first power level based on a detected traffic condition in the first region.

7. The method of claim 6, further comprising detecting the traffic condition as a percentage of total power in a base station transmitter amplifier, configured for amplifying wireless telephone signals for transmission into the first region, exceeding a prescribed threshold.

8. A dual mode wireless telephone communications system, comprising:

a first wireless telephone communications system configured for communication with dual mode wireless telephones in prescribed coverage areas according to a prescribed wireless protocol of an adjacent wireless telephone system; and

a digital wireless telephone communications system configured for communication with the dual mode wireless telephones in the prescribed coverage areas according to a prescribed digital wireless protocol, the digital wireless communications system comprising;

(1) first and second base station transceivers for transmitting sync channel signals according to the prescribed digital wireless protocol into first and second propagation regions at first and second power levels, respectively, the second propagation region having a boundary with the adjacent wireless telephone system, and

(2) a controller configured for controlling the first and second power levels, the controller setting the first power level sufficient for detection by a first of the dual mode wireless telephones within the first propagation region the controller setting the second power level to a level undetectable by a second of the dual mode wireless telephones located substantially at the boundary.

9. The system of claim 8, wherein the digital wireless telephone communications system further comprises first and second channel elements configured for controlling the transmission of the sync channel signals by the first and second base station transceivers in response to first and second control commands from the controller specifying the first and second power levels, respectively.

10. The system of claim 9, wherein the first and second base station transceivers each comprises a base station transmitter amplifier configured for amplifying the sync channel signal according to the corresponding power level, the controller monitoring a percentage of total power in each of the base station transmitter amplifier as a traffic load of the corresponding propagation region.

11. The system of claim 10, wherein the controller outputs a third control command specifying a third power level, undetectable by the first of the dual mode wireless telephones within at least a portion of the first propagation region, in response to the percentage of total power corresponding to the first propagation region exceeding a prescribed threshold, the first base station transceiver in response reducing the sync channel signal transmitted into the first propagation region.

12. The system of claim 10, further comprising a maintenance terminal configured for setting the first and second power levels in the controller.

13. The system of claim 8, wherein the prescribed digital wireless protocol is IS-95.

14. A dual mode wireless telephone communications system, comprising:

a first wireless telephone communications system configured for communication with dual mode wireless telephones in prescribed coverage areas according to a prescribed wireless protocol of an adjacent wireless telephone system; and

a digital wireless telephone communications system configured for communication with the dual mode wireless telephones in the prescribed coverage areas according to a prescribed digital wireless protocol, the digital wireless communications system comprising;

(1) first and second base station transceivers for transmitting sync channel signals according to the prescribed digital wireless protocol into first and second propagation regions at first and second power levels, respectively, the second propagation region having a boundary with the adjacent wireless telephone system, and

(2) a controller configured for controlling the first and second power levels, the controller setting the first power level sufficient for detection by a first of the dual mode wireless telephones within the first propagation region, the controller setting the second power level to a level undetectable by a second of the dual mode wireless telephones located in at least a portion of the second propagation region based on a detected condition in the second propagation region.

15. The system of claim 14, wherein the controller sets the second power level based on a detected power level for a traffic channel transmitted by the second base station transceiver exceeding a prescribed threshold.