Automated quality assessment system for cellular networks by using DTMF signals

• US 5,644,623 A
• Filed: 01/31/1996
• Issued: 07/01/1997
• Est. Priority Date: 03/01/1994
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Safco Technologies, Inc. (Agilent Technologies, Inc.)
• Inventors: Gulledge, Kenneth G.
• Primary Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US08/594,583
• Time in Patent Office: 517 Days
• Field of Search: 379/59, 379/32, 379/34, 379/27, 379/29-22, 379/24, 379/416, 455/33.1, 455/67.1, 455/67.4, 455/54.2
• US Class Current: 455/423
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

An automated system that assesses the quality of service provided by a cellular radiotelephone system. The system uses apparatus located at a mobile station that remotely controls apparatus located at a fixed station. A cellular radiotelephone call is placed from the mobile station which is received at the fixed station. When the connection is established, commands are sent from the mobile station to the fixed station that configure and control the operation of the fixed station. Many calls between the mobile station and the fixed station are placed and received by the mobile station each under control of the mobile station. During each call, recordings are made of the progress of the call and the audio quality measurements obtained during the call from both the mobile and fixed stations perspectives. Audio quality measurements are made utilizing enhanced audio quality measurement techniques that allows simultaneous measurements of audio quality in both the uplink and downlink channels of a cellular radiotelephone call utilizing two test tones instead of the single test tone that is normally used. The results of a number of cellular radiotelephone calls are later combined to form a set of statistical indicators that effectively represent the quality of service provided by a cellular radiotelephone system. The system provides means for comparing the quality of service provided by competing cellular radiotelephone service providers and for comparing the quality of service provided by differing cellular radiotelephone technology types.

Claims

1. A method for the establishment of reliable remote operational control over one or more communication channels of a first measurement station by a second control station by transmitting control messages each of which includes a sequence of start, control command, checksum and stop digits utilizing Dual Tone Multiple Frequency (DTMF) tones for each digit comprising the steps of,

converting at the second control station the control command which comprises one or more sequentially transmitted DTMF digits into a control message by appending a checksum DTMF digit which is determined by an analysis of all of the digits of the control command to the end of the control command and then inserting a unique start DTMF digit before the first digit of the control command and appending the control command with a unique stop DTMF digit after the previously added checksum DTMF digit,

transmitting the command message as a sequence of DTMF digits beginning with the start DTMF digit and ending with the stop DTMF digit from the second control station to the first measurement station,

receiving at the first measurement station the command message sent by the second control station by waiting for the unique start DTMF digit and collecting DTMF digits until after the unique stop DTMF digit is received,

verifying at the first measurement station the command message sent from the second control station by removing the start DTMF digit, the end DTMF digit and the checksum DTMF digit and comparing the received checksum digit against an analysis of all of the remaining DTMF digits which form the received control command,

sending a positive acknowledgment from the first measurement station to the second control station if the received checksum DTMF digit is equal to the calculated checksum, or sending a negative acknowledgment from the first measurement station to the second control station if the checksum is not equal to the calculated checksum, and

resending the command message if the second control station receives a negative acknowledgment from the first measurement station or accepting as reliable by the second control station the transmission of the command message if the second control station receives a positive acknowledgment from the first measurement station.

2. The method of claim 1 in which a communication channel utilized for transmission and reception by the first control station is a public switched telephone network and a communication channel utilized for transmission and reception by the second measurement station is a cellular radio telephone network.

3. The method of claim 1 in which a communication channel utilized for transmission and reception by the first control station is a cellular radio telephone network and a communication channel utilized for transmission and reception by the second measurement station is a public switched telephone network.

4. The method of claim 1 in which a communication channel utilized for transmission and reception by both the first control station and the second measurement station is a public switched telephone network.

5. The method of claim 1 in which the communication channel utilized for transmission and reception by both the first control station and the second measurement station is a cellular radio telephone network.

6. The method of claim 1 in which the first station and the second station each performs the functions of a control station and a measurement station.

7. The method of claim 1 in which the checksum analysis is performed by a Module 10 addition of all of the digits of the control command.

8. The method of claim 1 in which the first measuring station performs an analysis of the quality of service provided by a communication channel after reliable receipt of one or more control commands.

9. The method of claim 6 in which both measuring stations perform an analysis of the quality of service provided by a communication channel after reliable receipt of one or more control commands.