Mobile station link supervision utilizing digital voice color codes

• US 5,008,953 A
• Filed: 01/10/1990
• Issued: 04/16/1991
• Est. Priority Date: 06/26/1989
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Dahlin, Steinar J. E. A., Ghisler, Walter
• Primary Examiner(s): Kuntz, Curtis
• Application Number:
  US07/463,305
• Time in Patent Office: 461 Days
• Field of Search: 455/33, 455/34, 455/38, 455/53, 455/54, 455/56, 455/67, 455/185, 455/186, 370/95.1, 375/5, 371/37.1, 371/38.1, 371/39.1, 371/44, 371/45, 379/59, 379/60, 379/63
• US Class Current: 455/423
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04L 25/0216 with estimation of channel length
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

A method and apparatus are disclosed for supervising a communication link in a cellular mobile radio system between a base station and a mobile station on a digital voice channel by utilizing digital voice color codes. The base station transmits bursts of communication data, which have an associated digital voice color code, to the mobile station. The mobile station, upon receiving the bursts and decoding the digital voice color code, compares the digital voice color code with a reference digital voice color code received during a call setup or handoff operation. A timer is initiated to time out the communication link after a predetermined period of time in response to the reference digital voice color code not being equivalent to a first predetermined number of the digital voice color codes received with the bursts. The timer is reset and deactuated in response to the reference digital voice color code being equivalent to the first predetermined number of consecutively received digital voice color codes of the bursts received by the mobile station. The communication link is disconnected when the reference digital voice color code is not equivalent to the first predetermined number of consecutive digital voice color codes received during the predetermined period of time clocked by the timer. After the timer is reset and deactivated, the received digital voice color codes are again compared with the stored digital voice color code. In the event that a second predetermined number of consecutively received digital voice color codes are not equivalent to the stored digital voice color code, the timer will be initiated again to possibly time out the communication link as described above.

Claims

1. In a mobile radio telecommunications system of the type in which digitally-encoded information is transmitted between a base station and mobile stations in bursts over digital radio channels, and at least some of the bursts of information transmitted over the digital radio channels contain digital voice color codes, a method for supervising the quality of a connection between the base station and a mobile station comprising the steps of:

(a) transmitting a digital voice color code from said base station and storing said digital voice color code at a mobile station during the establishment of a connection between said base station and said mobile station over a designated digital communication channel;

(b) transmitting bursts of information between said base station and said mobile station, with at least some of said bursts of information containing said digital voice color code;

(c) initiating a timer to count a predetermined period of time;

(d) comparing a digital voice color code contained in a burst of information received at said mobile station with said stored code to determine whether the received code matches the stored code;

(e) detecting whether a first predetermined number of digital voice color codes which match said stored code are received at said mobile station during said predetermined period of time; and

(f) terminating said connection if said first predetermined number of digital voice color codes which match said stored code are not received at said mobile station during said predetermined period of time.

2. The method of claim 1, wherein said detecting step includes the step of determining whether said first predetermined number of digital voice color codes which match said stored code are consecutive codes received at said mobile station over said channel.

3. The method of claim 1, further comprising the step of:

(g) deactivating said timer in response to detecting that said first predetermined number of digital voice color codes received at said mobile station during said predetermined period of time match said stored code.

4. The method of claim 3, further comprising the steps of:

(h) comparing a digital voice color code contained in a burst of information received at said mobile station, after said timer is deactivated, with said stored code to determine whether the received code matches the stored code;

(i) detecting whether a second predetermined number of digital voice color codes which do not match said stored code are received at said mobile station; and

(j) returning to step (c) of said method to initiate said timer to count said predetermined period of time and continuing with the subsequent steps of said method in response to detecting that said second predetermined number of digital voice color codes received at said mobile station do not match stored code.

5. The method of claim 4, wherein said detecting step includes the step of determining whether said second predetermined number of digital voice color codes which do not match said stored code are consecutive codes received at said mobile station over said channel.

6. The method of claim 1, wherein said digital voice color code is contained in at least every other burst of information transmitted from said base station to said mobile station over said channel.

7. The method of claim 6, wherein said digital voice color code is contained in every burst of information transmitted from said base station to said mobile station over said channel.

8. A mobile station for use in a mobile radio communication system of the type in which digitally encoded information is transmitted between a base station and the mobile station in bursts over a digital communication channel, with at least some of the bursts of information containing digital voice color codes, said mobile station comprising:

a memory for storing a digital voice color code;

means for initiating a timer for counting a predetermined period of time;

a receiver for receiving bursts of information transmitted from said base station to said mobile station during a connection between said stations on a designated digital communication channel;

a decoder for detecting any digital voice color codes contained in bursts of information received over said designated channel during a connection;

means for determining whether a first predetermined number of digital voice color codes which match the digital voice color code stored in said memory are received during the predetermined time counted by said timer; and

means for terminating said connection if said first predetermined number of codes are not received during said period of time.

9. The mobile station of claim 8, wherein said determining means determines whether said first predetermined number of digital voice color codes which match said stored code are consecutively received during said period of time.

10. The mobile station of claim 8, further comprising means for deactivating said timer in response to said determining means determining that said first predetermined number of channel designation codes received at said mobile station during said predetermined period of time match said stored code.

11. The mobile station of claim 10, further comprising:

means for comparing a digital voice color code contained in a burst of information received at said mobile station, after said timer is deactivated, with said stored code to determine whether the received code matches the stored code;

means for detecting whether a second predetermined number of digital voice color codes which do not match said stored code are received at said mobile station; and

means for reinitiating said timer to count said predetermined period of time in response to said detecting means detecting that said second predetermined number of digital voice color codes received at said mobile station do not match said stored code.

12. The mobile station of claim 11, wherein said detecting means detects whether said second predetermined number of digital voice color codes which do not match said stored code are consecutive codes received at said mobile station over said channel.

13. The mobile station of claim 8, further including:

means for receiving analog-modulated information transmitted from said base station to said mobile station during a connection over an analog communication channel, and

means for detecting whether a supervisory audio tone transmitted with said analog-modulated information over said analog channel is received with said predetermined period of time counted by said timer, and wherein said terminating means is responsive to said detecting means to terminate a connection over said analog communications channel when a supervisory audio tone is not received within said period of time.

14. A method for supervising a call connection in a cellular mobile radio system, said call connection being established between a base station and a mobile station on a digital voice channel, comprising the steps of:

(a) transmitting from said base station to said mobile station a digital voice color code at a time of establishment of said call connection;

(b) receiving said digital voice color code at said mobile station and storing said code;

(c) transmitting bursts of communication data from said base station to said mobile station, specified bursts of communication data having a digital voice color code associated therewith;

(d) initiating a timer to clock a predetermined period of time;

(e) comparing each transmitted code that is received by said mobile station with said code being stored at said mobile station;

(f) deactivating said timer in response to said stored code being equivalent to at least two received codes received at said mobile station which are associated with bursts of communication data from said base station; and

(g) disconnecting said call connection in response to said stored code not being equivalent to at least two consecutively received codes received during said predetermined period of time.

15. A method according to claim 14, wherein said timer utilized in said initiating step is also utilized for timing out call connections between said base station and said mobile station made on an analog voice channel.

16. A method according to claim 14, wherein communication between said base station and said mobile station on said digital voice channel is carried out at a designated radio frequency range and during a designated multiplexed time slot of said digital channel.

17. A method according to claim 14, wherein said call connection between said base station and said mobile station is established during a call setup operation.

18. A method according to claim 14, wherein said call connection between said base station and said mobile station is established during a handoff operation.

19. A method according to claim 14, further comprising the steps of:

(h) comparing a digital voice color code associated with a burst of communication data received at said mobile station, after said timer is deactivated, with said stored code to determine whether the received code is equivalent to the stored code;

(i) detecting whether a predetermined number of consecutively received digital voice color codes at said mobile station are not equivalent to said stored code; and

(j) returning to step (d) of said method to initiate said timer to clock said predetermined period of time and continuing with the subsequent steps of said method in response to detecting that the predetermined number of consecutively received digital voice color codes are not equivalent to said stored code.

20. A cellular mobile radio communication system, comprising:

a base station including;

(a) means for establishing a communication link on an analog or digital channel,

(b) means for generating a digital voice color code,

(c) means for providing that said digital voice color code be associated with predetermined bursts of communication data to be transmitted on said digital channel, and

(d) means for transmitting bursts of communication data, including said predetermined bursts with said associated digital voice color code, on said digital channel; and

a mobile station including;

(a) means for storing said digital voice color code received on said digital channel during establishment of said communication link with said base station,

(b) means for receiving said bursts of communication data transmitted on said digital channel,

(c) means for decoding the digital voice color code that is associated with said bursts received on said digital channel,

(d) means for initiating a timer for timing a predetermined period of time,

(e) means for comparing said stored digital voice color code with digital voice color codes associated with said predetermined bursts,

(f) means for deactivating said timer in response to said stored digital voice color code being equivalent to a first predetermined number of received digital voice color codes associated with consecutively received predetermined bursts from said base station, and

(g) means for disconnecting said communication link in response to said stored digital voice color code not being equivalent to said first predetermined number of received digital voice color codes associated with corresponding predetermined bursts received during said predetermined period of time.

21. A system according to claim 20, wherein said means for providing comprises a modulo two adder which adds said digital code bit-by-bit modulo two to said predetermined bursts of communication data.

22. A system according to claim 21, wherein said means for decoding comprises a modulo two adder.

23. A system according to claim 20, wherein said means for generating produces a (12, 8) Hamming code of which eight bits are utilized for said digital voice color code.

24. A system according to claim 20, wherein said means for timing is also utilized for timing out communication links between said base station and said mobile station which are made on an analog voice channel.

25. A system according to claim 20, wherein said communication link established on said digital channel is established by a call setup operation.

26. A system according to claim 20, wherein said communication link established on said digital channel is established by a handoff operation.

27. A system according to claim 20, wherein said mobile station further includes:

means for comparing digital voice color codes associated with predetermined bursts received at said mobile station after said timer is reset and deactivated with said stored code to determine whether the received codes are equivalent to the stored code;

means for detecting whether a second predetermined number of consecutively received digital voice color codes at said mobile station are not equivalent to said stored code; and

means for reinitiating said timer to time said predetermined period of time in response to said detecting means detecting that said second predetermined number of consecutively received digital voice color codes are not equivalent to said stored code.