System for TDMA mobile-to-mobile VSELP CODEC bypass

• US 6,185,424 B1
• Filed: 06/12/1998
• Issued: 02/06/2001
• Est. Priority Date: 12/19/1994
• Status: Expired due to Term

• Current Assignee: Blackberry Limited
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Chu, Chung-Cheung, Pon, Hermon, Rabipour, Rafi
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): WYCHE, MYRON
• Application Number:
  US09/096,192
• Time in Patent Office: 970 Days
• Field of Search: 455/445, 455/436, 455/550, 455/522
• US Class Current: 455/445
• CPC Class Codes: H04M 2207/18 wireless networks
• CPC Class Codes: H04M 2207/20 hybrid systems
• CPC Class Codes: H04M 3/002 Applications of echo suppressors or cancellers in telephonic connections in two-way loud-speaking telephone systems H04M9/08, echo suppressors or cancellers per se H04B3/20
• CPC Class Codes: H04M 3/40 Applications of speech amplifiers
• CPC Class Codes: H04M 7/12 for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal
• CPC Class Codes: H04Q 2213/13031 Pulse code modulation, PCM
• CPC Class Codes: H04Q 2213/13034 A/D conversion, code compression/expansion
• CPC Class Codes: H04Q 2213/13098 Mobile subscriber
• CPC Class Codes: H04Q 2213/1319 Amplifier, attenuation circuit, echo suppressor
• CPC Class Codes: H04Q 2213/13292 Time division multiplexing, TDM
• CPC Class Codes: H04W 88/181 Transcoding devices; Rate adaptation devices

Abstract

In a TDMA mobile-to-mobile connection, the end-to-end audio signal quality as well as system performance can be improved by providing digital signal processors the capability to automatically switch configuration such that each digital signal processor in a mobile-to-mobile communication connection can automatically identify a TDMA mobile-to-mobile connection and bypass the speech encoding and decoding processes within the digital signal processors. The two digital signal processors are virtually connected at the channel codecs.

Claims

1. A transmission system, comprising:

a first signal processor;

a second signal processor; and

a transmission facility linking said first signal processor to said second signal processor;

said first signal processor being operable to convert a traffic signal from a first signal format to a second signal format for transmission on said transmission facility to said second signal processor;

said second signal processor being operable to reconvert said traffic signal from said second signal format to said first signal format;

said first signal processor further being operable to transmit a control signal to said second signal processor;

said second signal processor being responsive to said control signal transmitted by said first signal processor to send a control signal to said first signal processor; and

said first signal processor being responsive to said control signal transmitted by said second signal processor to transmit said traffic signal to said second signal processor in said first signal format.

2. A transmission system as defined in claim 1, wherein the second signal processor is operable to:

recognize that the first signal processor is transmitting the traffic signal in the first signal format; and

in response to recognition that the first signal processor is transmitting the traffic signal ion the first signal format, to pass the traffic signal in the first signal format.

3. A transmission system as defined in claim 2, wherein:

the first signal processor is operable to transmit a control signal to the second signal processor when the first signal processor begins transmitting the traffic signal in the first signal format; and

the second signal processor is operable to recognize on receipt of the control signal that the first signal processor is transmitting the traffic signal in the first signal format.

4. A signal processor, comprising:

a signal format converter for converting a traffic signal from a first signal format to a second signal format;

a message transmitter for transmitting control signals;

a message receiver for receiving control signals;

a controller for controlling said signal format converter and said message transmitter, said controller operating said message transmitter to transmit a control signal when said signal format converter is enabled to convert said traffic signal from said first signal format to said second signal format and, in response to receipt of a control signal by said message receiver, to enable said signal format converter to pass said traffic signal in said first signal format.

5. A signal processor comprising:

a signal format converter for converting a traffic signal from a second signal format to a first signal format;

a message transmitter for transmitting control signals;

a controller for controlling said signal format converter and said message transmitter;

to transmit a control signal on receipt of a control signal;

to recognize that the traffic signal is being received in the first signal format; and

in response to recognition that the traffic signal is being

received in the first signal format, to pass the traffic signal in the first signal format.

6. A signal processor as defined in claim 5, wherein the controller is operable to recognize that the first signal processor is transmitting the traffic signal in the first signal format on receipt of a control signal.

7. A method for operating a transmission system, comprising:

providing a first signal processor, a second signal processor and a transmission facility linking the first signal processor to the second signal processor, the first signal processor being operable to convert a traffic signal from a first signal format to a second signal format for transmission on the transmission facility to the second signal processor, and the second signal processor being operable to reconvert the traffic signal from the second signal format to the first signal format;

transmitting a control signal from the first signal processor to the second signal processor;

in response to receipt of the control signal transmitted by the first signal processor at the second signal processor, transmitting a control signal from the second signal processor to the first signal processor; and

in response to receipt of the control signal transmitted by the second signal processor at the first signal processor, the first signal processor transmitting the traffic signal to the second signal processor in the first signal format.

8. A method as defined in claim 7, further comprising:

recognizing at the second signal processor that the first signal processor is transmitting the traffic signal in the first signal format; and

in response to recognition at the second signal processor that the first signal processor is transmitting the traffic signal in the first signal format, passing the traffic signal in the first signal format at the second signal processor.

9. A method as defined in claim 8, further comprising transmitting a control signal from the first signal processor to the second signal processor when the first signal processor begins transmitting the traffic signal in the first signal format, wherein the step of recognizing at the second signal processor that the first signal processor is transmitting the traffic signal in the first signal format comprises recognizing said control signal at said second signal processor.

10. A method for operating a signal processor, comprising:

providing a signal format converter for converting a traffic signal from a first signal format to a second signal format, a message transmitter for transmitting control signals, a message receiver for receiving control signals, and a controller for controlling the signal format converter and the message transmitter;

when the signal format converter is enabled to convert the traffic signal from the first signal format to the second signal format, transmitting a control signal via the message transmitter; and

in response to receipt of a control signal by the message receiver, enabling the signal format converter to pass the traffic signal in the first signal format.

11. A method of operating a signal processor comprising:

converting a received signal from a second signal format to a first signal format;

transmitting a control signal on receipt of a control signal;

recognizing that the traffic signal is being received in the first signal format; and

in response to recognition that the traffic signal is being received in the first signal format, passing the traffic signal in the first signal format.

12. A method of operating a signal processor as defined in claim 11, wherein the step of recognizing that the traffic signal is being received in the first signal format comprises receiving and recognizing a control signal.

13. A transmission system, comprising a first signal processor, a second signal processor and a transmission facility linking the first signal processor to the second signal processor;

the first signal processor being operable to convert a traffic signal from a first signal format to a second signal format for transmission on the transmission facility to the second signal processor;

the second signal processor being operable to reconvert the traffic signal from the second signal format to the first signal format;

the first signal processor further being operable to transmit a first control signal to the second signal processor;

the second signal processor being responsive to the first control signal to send a second control signal to the first signal processor;

characterized in that;

the first signal processor is responsive to the second control signal to interrupt conversion of the traffic signal from the first signal format to the second signal format so that the traffic signal is transmitted from the first signal processor to the second signal processor in the first signal format and to transmit a third control signal to the second signal processor; and

the second signal processor is responsive to the third control signal to interrupt reconversion of the traffic signal from second signal format to the first signal format.

14. A transmission system as defined in claim 13, wherein:

the transmission facility supports bi-directional transmission between the first signal processor and the second signal processor;

the second signal processor is operable to convert another traffic signal from the first signal format for transmission on the transmission facility to the first signal processor;

the first signal processor is operable to reconvert the other transmitted traffic signal from the second signal format to the first signal format;

the second signal processor is operable to transmit the first control signal to the first signal processor;

the first signal processor is responsive to the first control signal to send the second control signal to the second signal processor;

the second signal processor is responsive to the second control signal to interrupt conversion of the other traffic signal from the first signal format to the second signal format so that the traffic signal is transmitted from the second signal processor to the first signal processor in the first signal format and to transmit the third control signal to the first signal processor; and

the first signal processor is responsive to the third control signal to interrupt reconversion of the other traffic signal from the second signal format to the first signal format.

15. A transmission system as defined in claim 13, wherein the first, second and third control signals are in-band signals transmitted via the transmission facility.

16. A signal processor comprising:

a signal format converter for converting a traffic signal from a first signal format to a second signal format;

a message transmitter for transmitting control signals;

a message receiver for receiving control signals; and

a controller for controlling the signal format converter and the message transmitter;

characterized in that the controller operates the message transmitter to transmit a first control signal when the signal format converter is enabled to convert the traffic signal from the first signal format to the second signal format and, in response to receipt of a second control signal by the message receiver, to disable the signal format converter and to operate the message transmitter to transmit a third control signal.

17. A signal processor as defined in claim 16 having:

a first state in which it transmits the first control signal and converts the traffic signal from the first signal format to the second signal format;

a second state in which it transmits the second control signal and converts the traffic signal from the first signal format to the second signal format; and

a third state in which it transmits the third control signal and does not convert the traffic signal from the first signal format to the second signal format;

the signal processor being;

responsive to receipt of the first control signal to change from the first state to the second state; and

responsive to receipt of the second control signal to change from the second state to the third state.

18. A signal processor as defined in claim 17, being responsive, when in the first state, to receipt of the second control signal to change from the first state to the second state.

19. A signal processor as defined in claim 18, wherein:

the signal format converter is also operable to convert another traffic signal from the second signal format to the first signal format in the first state, the second state and the third state of the signal processor;

the signal processor has a fourth state in which it transmits the third control signal, does not convert the traffic signal from the first signal format to the second signal format, and does not convert the other traffic signal from the second signal format to the first signal format; and

the signal processor is responsive, when in the third state, to receipt of the third control signal to change from the third state to the fourth state.

20. A signal processor as defined in claim 19, being responsive, when in the second state, to receipt of the third control signal to change from the second state to the fourth state.

21. A signal processor as defined in claim 17, being responsive, when in the third state, to receipt of the first control signal to change from the third state to the first state.

22. A signal processor as defined in claim 19, being responsive, when in the fourth state, to receipt of one of the first control signal and the second control signal to change from the fourth state to the first state.

23. A signal processor as defined in claim 17, being responsive to receipt of no control signal to revert to the first state.

24. A method for operating a transmission system, the transmission system comprising a first signal processor, a second signal processor and a transmission facility linking the first signal processor to the second signal processor, the first signal processor being operable to convert a traffic signal from a first signal format to a second signal format for transmission on the transmission facility to the second signal processor and the second signal processor being operable to reconvert the traffic signal from the second signal format to the first signal format, the method comprising:

transmitting a first control signal from the first signal processor to the second signal processor;

in response to receipt of the first control signal by the second signal processor, transmitting a second control signal from the second signal processor to the first signal processor;

characterized in that.

in response to receipt of the second control signal by the first signal processor, the first signal processor interrupts conversion of the traffic signal from the first signal format to the second signal format so that the traffic signal is transmitted from the first signal processor to the second signal processor in the first signal format and transmits a third control signal to the second signal processor; and

in response to receipt of the third control signal by the second signal processor, the second signal processor is interrupts reconversion of the traffic signal from second signal format to the first signal format.

25. A method as defined in claim 24, wherein:

the transmission facility supports bi-directional transmission between the first signal processor and the second signal processor, the second signal processor is operable to convert another traffic signal from the first signal format for transmission on the transmission facility to the first signal processor, and the first signal processor is operable to reconvert the other transmitted traffic signal from the second signal format to the first signal format;

the second signal processor transmits the first control signal to the first signal processor;

in response to receipt of the first control signal by the first signal processor, the first signal processor sends the second control signal to the second signal processor;

in response to receipt of the second control signal by the second signal processor, the second signal processor interrupts conversion of the other traffic signal from the first signal format to the second signal format so that the traffic signal is transmitted from the second signal processor to the first signal processor in the first signal format and the second signal processor transmits the third control signal to the first signal processor; and

in response to receipt of the third control signal by the first signal processor, the first signal processor interrupts reconversion of the other traffic signal from the second signal format to the first signal format.

26. A method as defined in claim 24, wherein the first, second and third control signals are in-band signals transmitted via the transmission facility.

27. A method for operating a signal processor, comprising a signal format converter for converting a traffic signal from a first signal format to a second signal format, a message transmitter for transmitting control signals, a message receiver for receiving control signals, and a controller for controlling the signal format converter and the message transmitter,

the method characterized in that the controller operates the message transmitter to transmit a first control signal when the signal format converter is enabled to convert the traffic signal from the first signal format to the second signal format and, in response to receipt of a second control signal by the message receiver, to disable the signal format converter and to operate the message transmitter to transmit a third control signal.

28. A method as defined in claim 27, wherein the signal processor has a first state in which it transmits the first control signal and converts the traffic signal from the first signal format to the second signal format, a second state in which it transmits the second control signal and converts the traffic signal from the first signal format to the second signal format, and a third state in which it transmits the third control signal and does not convert the traffic signal from the first signal format to the second signal format, comprising:

changing the signal processor from the first state to the second state in response to receipt of the first control signal; and

changing the signal processor from the second state to the third state in response to receipt of the second control signal.

29. A method as defined in claim 28, comprising changing the signal processor from the first state to the second state in response to receipt of the second control signal when in the first state.

30. A method as defined in claim 29, wherein the signal format converter is also operable to convert another traffic signal from the second signal format to the first signal format in the first state, the second state and the third state of the signal processor and the signal processor has a fourth state in which it transmits the third control signal, does not convert the traffic signal from the first signal format to the second signal format, and does not convert the other traffic signal from the second signal format to the first signal format, comprising:

changing the signal processor from the third state to the fourth state in response to receipt of the third control signal when in the third state.

31. A method as defined in claim 30, comprising changing the signal processor from the second state to the fourth state in response to receipt of the third control signal when in the second state.

32. A method as defined in claim 28, comprising changing the signal processor from the third state to the first state in response to receipt of the first control signal when in the third state.

33. A method as defined in claim 30, comprising changing the signal processor from the fourth state to the first state in response to receiving one of the first control signal and the second control signal when in the fourth state.

34. A method as defined in claim 28, comprising reverting to the first state in response to receiving no control signal.