Wireless communication device capable to transmit/receive TTY/TDD messages with variable data rate, embedded into audio data frames

• US 6,628,967 B1
• Filed: 12/30/1999
• Issued: 09/30/2003
• Est. Priority Date: 12/30/1999
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Yue, Peter P.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): BEAMER, TEMICA M
• Application Number:
  US09/475,043
• Time in Patent Office: 1,370 Days
• Field of Search: 455/552, 455/553, 455/557, 455/556, 379/52, 370/342, 370/465, 370/466, 370/467, 370/468, 375/246, 375/251, 375/253, 375/259
• US Class Current: 455/557
• CPC Class Codes: H04M 1/7243 with interactive means for internal management of messages
• CPC Class Codes: H04M 1/72478 for hearing-impaired users
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A wireless communication device capable to transmit and receive TTY/TDD characters. The wireless communication device includes a receiver and a transmitter to allow for a full duplex communication. The receiver is responsive to the reception of a data frame including a TTY/TDD silence message to switch to lower data rate operative state where the receiver expects to receive and process data frames at a lower data rate. At the same time the receiver causes the transmitter to switch to a lower data rate operative state and also to return to the remote site with which the wireless communication device communicates a TTY/TDD silence message. The purpose of this TTY/TDD silence message is to set the receiver at the remote site at the lower data rate operative state.

Claims

1. A wireless communication device capable to receive and transmit TTY/TDD messages, said wireless communication device having a receiver that includes:

an input for receiving an RF signal from a remote site containing a succession of data frames transporting speech sound information or a TTY/TDD message;

said receiver being operative for processing the data frames, said receiver capable to selectively acquire a TTY/TDD active mode when the data frames convey a TTY/TDD message and a TTY/TDD inactive mode when the data frames convey speech sound information, when in said TTY/TDD active mode said receiver capable to acquire either one of a first operative state in which said receiver is operative to process the data frames at a first data rate and a second operative state in which said receiver is operative to process data frames at a second data rate that is lower than the first data rate, when in said TTY/TDD active mode said receiver processing the data frames to generate an output signal conveying successive characters of the TTY/TDD message;

an output for releasing the output signal;

said receiver, when in said TTY/TDD active mode, being responsive to a TTY/TDD silence message contained in at least one data frame directing said receiver to blank the output signal from any TTY/TDD character, to acquire said second operative state.

2. A wireless communication device is defined in claim 1, wherein a data frame includes a pitch lag field, said receiver in said TTY/TDD active mode being operative to derive a TTY/TDD character from a bit sequence contained in the pitch lag field.

3. A wireless communication device as defined in claim 2, wherein the bit sequence includes a header portion and a character information portion.

4. A wireless communication device as defined in claim 2, wherein said wireless communication device has a transmitter for sending to the remote site data frames, said receiver when in said TTY/TDD active mode, being responsive to a TTY/TDD silence message contained in at least one data frame for causing said transmitter to send a TTY/TDD silence message to the remote site.

5. A wireless communication device as defined in claim 4, wherein said transmitter being capable to acquire either one of a first operative state in which said transmitter is operative to transmit the data frames at the first data rate and a second operative state in which said transmitter is operative to transmit data frames at a second data rate that is lower than the data rate during the first operative state of the transmitter.

6. A wireless communication device as defined in claim 5, wherein said receiver when in said TTY/TDD active mode, being responsive to a TTY/TDD silence message contained in at least one data frame for causing said transmitter to acquire the second operative state.

7. A wireless communication device as defined in claim 3, wherein the second data rate corresponds approximately to one half of the first data rate.

8. A wireless communication device as defined in claim 2, wherein a data frame includes an adaptive codebook gain field, a data frame containing a TTY/TDD silence control message contains a value in the adaptive codebook gain field that would signal a no gain condition to said receiver if said receiver is in said TTY/TDD inactive mode.

9. A wireless communication device as defined in claim 2, wherein said receiver includes a CELP decoder.

10. A wireless communication device as defined in claim 2, wherein said transmitter includes an CELP encoder.

11. A wireless communication device as defined in claim 2, wherein said transmitter includes an input for receiving a signal containing PCM samples.

12. A wireless communication device as defined in claim 11, wherein said transmitter includes a TTY/TDD detector coupled to said input for sensing a presence of Baudot tones in the signal of PCM sample.

13. A wireless communication device as defined in claim 12, wherein said TTY/TDD detector includes an output for releasing a signal indicative of logical values contained in the signal of PCM samples when the signal of PCM samples contains Baudot tones.

14. A wireless communication device as defined in claim 13, wherein said transmitter includes a TTY/TDD character classifier coupled to said TTY/TDD detector for receiving the signal indicative of logical values.

15. A wireless communication device as defined in claim 14, wherein said TTY/TDD character classifier is operative to process the signal indicative of logical values to extract TTY/TDD characters conveyed by the logical values in the signal of logical values.

16. A wireless communication device as defined in claim 2, wherein said wireless communication device is a base station of a cellular network.

17. A wireless communication device as defined in claim 2, wherein said wireless communication device is cellular telephone.

18. A wireless communication device as defined in claim 2, wherein the RF signal is sent according to a CDMA technique.

19. A wireless communication device as defined in claim 2, wherein the output signal converting successive characters of the TTY/TDD message contains tones.

20. A method for processing an RF signal, comprising:

receiving the RF signal from a remote site, the RF signal containing a succession of data frames transporting speech sound information or a TTY/TDD message;

supplying the data frames to a receiver, said receive capable to selectively acquire a TTY/TDD active mode when the data frames convey a TTY/TDD message and a TTY/TDD inactive mode when the data frames convey speech sound information, when in said TTY/TDD active mode said receiver being capable to acquire either one of a first operative state in which said receiver is operative to process the data frames at a first data rate and a second operative state in which said receiver is operative to process data frames at a second data rate that is lower than the first data rate, when in said TTY/TDD active mode said receiver processing the data frames to generate an output signal conveying successive characters of the TTY/TDD message;

when said receiver is in said TTY/TDD active mode, and when at least one data frame is received that conveys a TTY/TDD silence message causing said receiver to blank of output signal from any character of a TTY/TDD message, switching said receiver to said second operative state.

21. A wireless communication device capable to receive and transmit TTY/TDD messages, said wireless communication device having a receiver that includes:

input means for receiving an RF signal from a remote site containing a succession of data frames transporting speech sound information or a TTY/TDD message;

said receiver capable to selectively acquire a TTY/TDD active mode when the data frames convey a TTY/TDD message and a TTY/TDD inactive mode when the data frames convey speech around information, when in said TTY/TDD active mode said receiver being capable to acquire either one of a first operative state in which said receiver is operative to process the data frames at a first data rate and a second operative state in which said receiver is operative to process data frames at a second data rate that is lower than first data rate, when in said TTY/TDD active mode said receiver processing the data frames to generate an output signal conveying successive characters of the TTY/TDD message;

output means coupled to said receiver for releasing the output signal;

said receiver, when in said TTY/TDD active mode, being responsive to a silence control message contained in at least one data frame directing said receiver a blank the output signal from any character of a TTY/TDD message, to acquire said second operative state.

22. A wireless communication device capable to receive and transmit TTY/TDD messages, said wireless communication device comprising:

a transmitter for transmitting an RF signal to a remote site containing a succession of data frames transporting speech sound information or a TTY/TDD message;

a receiver that includes;

a) an input for receiving an RF signal from the remote site containing a succession of data frames transporting speech sound information or a TTY/TDD message;

b) said receiver being capable to acquire either one of a first operative state in which said receiver is operative to process the data frames at a first data rate and a second operative state in which said receiver is operative to process data frames at a second data rate that is lower than the first data rate;

c) an output for releasing an output signal from said receiver;

d) said receiver being respective to a TTY/TDD silence message contained in at least one data frame directing said receiver to blank the output signal from an TTY/TDD character to;

i) acquire and second operative state;

ii) cause said transmitter to issue toward the remote site a TTY/TDD silence message.