Topology verification process for controlling a personal communication services system

• US 5,711,000 A
• Filed: 08/31/1995
• Issued: 01/20/1998
• Est. Priority Date: 08/31/1995
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Ploeg, David Charles, Reinink, Kasper, Onsy, Sammy John
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): WYCHE, MYRON
• Application Number:
  US08/521,848
• Time in Patent Office: 873 Days
• Field of Search: 379/58, 379/59, 455/33.1, 455/67.1, 455/403, 455/422, 455/423, 455/446, 455/502
• US Class Current: 455/423
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

A topology verification process for controlling a Personal Communication Services (PCS) system which includes a plurality of Cordless Fixed Parts (CFP)s. The process includes mapping the spatial relationships of the CFPs utilizing Received Signal Strength Indication (RSSI) vectors resulting from test signals transmitted between the CFPs, to establish the topology of the system; repeating the mapping process after any disruption of power to the system, and comparing the results. Any significant change in the results, would be highly indicative of a potential change in the geographic area of operation of the system, and can be used to initiate disablement of the system operation.

Claims

1. A topology verification process for a Personal Communication Services (PCS) system which includes a plurality of Cordless Fixed Parts (CFP)s each for transmitting and receiving signals therefrom, comprising the steps of:

a) transmitting a test signal from a selected one of the plurality of CFPs;

b) measuring the Received Signal Strength Indication (RSSI) of the transmitted test signal received by each of the other CFPs to provide a RSSI vector for each CFP;

c) selecting other ones of the plurality of CFPs and repeating steps a) and b);

d) mapping the spatial relationships of the CFPs relative to each other from the RSSI vector measurements;

e) repeating steps a) to d) in response to selected criteria; and

f) comparing the most recent mapped spatial relationships with the initial mapped spatial relationships, to detect changes in the topology of the CFPs in the system, which is highly indicative of a change in geographic area of operation of the PCS system.

2. A process as defined in claim 1, further comprising the step of:

g) disabling operation of the CFPs when predetermined changes in the topology of the PCS system are detected.

3. A process as defined in claim 2, in which the PCS system further includes a Central Controller Unit (CCU) for enabling operation of the CFPs only after entry of a password into the CCU, further comprising the step of:

h) after disabling operation of the CFPs in step g), reenabling operation of the CFPs only after entry of an alternate password into the CCU.

4. A process as defined in claim 2, in which the PCS system further includes a Central Controller Unit (CCU) for configuring the PCS system, further comprising the steps of:

h) recording the mapped spatial relationships of the CFPs in the CCU.

5. A process as defined on claim 4 in which the PCS system further comprises the steps of:

i) recording the results of the initial mapped spectral relationships of up to a maximum sample number of CFPs as a RSSI Signature;

j) recording the results of the most recent mapped spectral relationships of the same CFPs as a RSSI Test Signature; and

k) comparing the two Signatures, to detect the changes in the topology of the system.

6. A process as defined in claim 2, in which the PCS system further includes a plurality of Cordless Portable Parts (CPP)s, further comprising the steps of:

h) inhibiting signal transmission from any CPP that is not receiving control signals from one of the CFPs; and

i) inhibiting signal transmission from any CFP that is not receiving control signals from the CCU.

7. A method for controlling disablement of a Personal Communication Services system, which includes a plurality of base stations that communicate with a plurality of portable handsets, the method comprising the steps of:

a) measuring and recording the received signal strength of test signals transmitted in turn by each base station, that is received by the other base stations;

b) repeating the measuring and recording step in response to selected criteria; and

c) comparing earlier recorded received signal strengths with the most recent recorded received signal strengths; and

d) disabling operation of the Personal Communications Services system when predetermined differences in the recorded received signal strengths are detected.