Telephone apparatus for multiplexing digital speech samples and data signals using variable rate speech coding

• US 5,754,554 A
• Filed: 10/30/1995
• Issued: 05/19/1998
• Est. Priority Date: 10/28/1994
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Nakahara, Toru
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US08/550,106
• Time in Patent Office: 932 Days
• Field of Search: 370/528, 370/435, 370/498, 370/334, 370/336, 370/418, 370/471, 379/56, 379/57, 379/58, 379/59, 379/63, 395/2, 395/2.21
• US Class Current: 370/498
• CPC Class Codes: H04J 3/1682 Allocation of channels according to the instantaneous demands of the users, e.g. concentrated multiplexers, statistical multiplexers
• CPC Class Codes: H04J 3/22 in which the sources have different rates or codes simultaneous speech and digital data or video transmission H04M11/06; see provisional also H04J3/16
• CPC Class Codes: H04M 11/064 Data transmission during pauses in telephone conversation

Abstract

In a mobile telephone set, a speech coder is provided for converting an analog speech signal to a digital speech signal. A voice activity sensor determining whether the analog speech signal is present or not. A storage level detector determines the amount of a data signal waiting for transmission from a non-telephonic communications apparatus. A switching control logic determines the rate for the speech coder according to the outputs of the voice activity sensor and the storage level detector. When the analog speech signal is present and the amount of the waiting data signal is zero, the data rate is set at a high rate and a digital speech signal from the speech coder is transmitted along with an indication of the high data rate. When the analog speech signal is present and the amount of the waiting data signal is non-zero, the data rate of the speech coder is set at a rate which is lower than the high data rate and is variable in accordance with the amount of the waiting data signal and the digital speech signal from the speech coder and the data signal from the non-telephonic communications apparatus are transmitted along with an indication of the variable data rate. When the analog speech signal is absent and the amount of the waiting data signal is non-zero, the data signal from the apparatus is exclusively transmitted.

Claims

1. A method for transmitting a digital speech signal and a data signal from a telephone set, the telephone set including a speech coder which produces said digital speech signal at a variable rate from an analog speech signal, the method comprising the steps of:

a) determining whether a data request is present or absent, said data request indicating that a non-telephonic communications apparatus has said data signal to transmit;

b) determining whether said analog speech signal is present or absent;

c) if said data request is determined to be absent and said analog speech signal is determined to be present, operating said speech coder exclusively at a high data rate, and exclusively transmitting said digital speech signal to a destination along with an indication of the high data rate;

d) if said data request and said analog speech signal are determined to be simultaneously present, operating said speech coder at a low data rate and interleaving said digital speech signal and said data signal and transmitting the interleaved signals to said destination along with an indication of the low data rate; and

e) if said data request is determined to be present and said analog speech signal is determined to be absent, exclusively transmitting said data signal to said destination.

2. A method for transmitting a digital speech signal and a data signal from a telephone set, the telephone set including a speech coder which produces said digital speech signal at a variable rate from an analog speech signal, said telephone set being adapted to be coupled to a non-telephonic communications apparatus which produces a data signal, the method comprising the steps of:

a) determining an amount of said data signal waiting for transmission;

b) determining whether said analog speech signal is present or absent;

c) if the amount of said data signal is determined to be zero and said analog speech signal is determined to be present, operating said speech coder exclusively at a high data rate and exclusively transmitting said digital speech signal to a destination along with an indication of the high data rate;

d) if the amount of said data signal is determined to be non-zero and said analog speech signal is determined to be present, operating said speech coder at a data rate variable in accordance with the determined amount of said data signal, interleaving said digital speech signal and said data signal and transmitting the interleaved signals to said destination along with an indication of the variable data rate; and

e) if the amount of said data signal is determined to be non-zero and said analog speech signal is determined to be absent, exclusively transmitting said data signal to said destination.

3. A communication method for a telephone set, the telephone set including a variable rate speech coder for converting an analog speech signal to a digital speech signal at a variable data rate and a variable rate speech decoder, the method of comprising the steps of:

a) determining whether a data request is present or absent, said data request indicating that a non-telephonic communications apparatus has said data signal to transmit;

b) determining whether said analog speech signal is present or absent;

c) storing the digital speech signal in a speech buffer;

d) storing said data signal from said non-telephonic communications apparatus in a data buffer;

e) if said analog speech signal is determined to be present and said data request is determined to be absent, operating said speech coder exclusively at a high data rate, exclusively reading said digital speech signal from the speech buffer, and transmitting to a destination a speech burst containing the read digital speech signal and an indication of said high data rate;

f) if said analog speech signal is determined to be present and said data request is determined to be present, operating said speech coder at a low data rate, reading said digital speech signal and a data signal from the speech and data buffers, transmitting to said destination a speech burst containing the read digital speech signal and an indication of said low data rate and a data burst containing the read data signal interleaved with the speech burst, said variable data rate being lower than said high data rate;

g) if said analog speech signal is determined by step (b) to be absent and said data request is determined to be present, exclusively reading said data signal from the data buffer and transmitting to said destination said data burst containing the read data signal; and

h) receiving said data burst from the destination and identifying the received burst as a speech burst or a data burst, and supplying said digital speech signal contained in the speech burst to the speech decoder and operating the speech decoder at a rate corresponding to the data rate indication contained in the speech burst, and supplying said data signal contained in the data burst to said non-telephonic communications apparatus.

4. A communication method for a telephone set, the telephone set including a variable rate speech coder for converting an analog speech signal to a digital speech signal at a variable rate and a variable rate speech decoder, said telephone set being adapted for connection for a non-telephonic communications apparatus having a data signal to transmit, the method comprising the steps of:

a) determining whether said analog speech signal is present or absent;

b) storing digital speech signals in a speech buffer;

c) storing data signals from said non-telephonic communications apparatus in a data buffer;

d) determining an amount of said data signals stored in said data buffer and producing a stored data signal indicative thereof;

e) if said analog speech signal is determined to be present and the amount of the stored data signal is determined to be zero, operating said speech coder exclusively at a high data rate, reading the digital speech signal from the speech buffer and transmitting to a destination a speech burst containing the read digital speech signal and an indication of said high data rate;

f) if said analog speech signal is determined to be present and the amount of said stored data signal is determined to be non-zero, operating said speech coder at a variable data rate according to the amount of said stored data signal, reading said digital speech signals and said data signals from the speech and data buffers, transmitting to said destination a speech burst containing the read digital speech signal and an indication of the variable data rate and a data burst containing the read data signal interleaved with the speech burst, said variable data rate being lower than said high data rate;

g) if said analog speech signal is determined to be absent and the amount of said stored data is determined to be non-zero, exclusively reading the data signal from the data buffer and transmitting to said destination a data burst containing the read data signal; and

h) receiving a burst from the destination and identifying the received burst as a speech burst or a data burst, and supplying said digital speech signal contained in the speech burst to the speech decoder and operating the speech decoder at a rate corresponding to the data rate indication contained in the speech burst, and supplying said data signals contained in the data burst to said non-telephonic communications apparatus.

5. A telephone set comprising:

a data input terminal and a data output terminal to which a non-telephonic communications apparatus is adapted to be connected;

entry means for entering a data request when said apparatus has a data signal to transmit;

a speech coder for converting an analog speech signal to a digital speech signal at a variable rate;

a voice activity sensor for determining whether said analog speech signal is present or absent; and

control means for (a) operating said speech coder exclusively at a high data rate when said analog speech signal is determined to be present while no data request is entered through said entry means and exclusively transmitting the digital speech signal from the speech coder along with an indication of the high data rate, (b) operating said speech coder at a low data rate when said analog speech signal is determined to be present while a data request is entered through said entry means, transmitting the digital speech signal from the speech coder and said data signal from the non-telephonic communications apparatus along with an indication of the low data rate, and (c) exclusively transmitting the data signal from said apparatus when said analog speech signal is determined to be absent.

6. A telephone set comprising:

a data input terminal and a data output terminal to which a non-telephonic communications apparatus is adapted to be connected;

a speech coder for converting an analog speech signal to a digital speech signal at a variable rate;

a voice activity sensor for determining whether said analog speech signal is present or absent;

a storage level detector for determining an amount of a data signal waiting for transmission from said non-telephonic communications apparatus; and

control means for (a) operating said speech coder exclusively at a high data rate when said analog speech signal is determined to be present and the detected amount of said data signal is zero and exclusively transmitting said digital speech signal from the speech coder along with an indication of the high data rate, (b) operating said speech coder at a variable data rate lower than said high data rate in accordance with the detected amount of said data signal when said analog speech signal is determined to be present and said detected amount of the data signal is non-zero, transmitting the digital speech signal from the speech coder and the data signal from the non-telephonic communications apparatus along with an indication of the variable data rate, and (c) exclusively transmitting the data signal from said apparatus when said analog speech signal is determined to be absent and said detected amount of the data signal is non-zero.

7. A telephone set for a mobile communications system, comprising:

a data input terminal and a data output terminal to which a non-telephonic communications apparatus is adapted to be connected;

entry means for entering a data request when said apparatus has a data signal to transmit;

a speech coder for converting an analog speech signal to a digital speech signal at a variable rate;

a voice activity sensor for determining whether said analog speech signal is present or absent;

a speech buffer for storing digital speech signals supplied from said speech coder;

a data buffer for storing data signals from said data input terminal;

receiver means for detecting a burst from a base station;

timing control means for determining frame intervals from the burst detected by the receiver means;

switching control means for (a) operating said speech coder exclusively at a high data rate when said analog speech signal is determined to be present simultaneously while no data request is entered through said entry means and exclusively reading digital speech signals from the speech buffer, (b) operating said speech coder at a low data rate when said analog speech signal is determined to be present while said data request is entered through said entry means and selectively reading said digital speech signal and said data signal from the speech and data buffers (c) exclusively reading said data signals from the data buffer when said analog speech signal is determined to be absent;

burst formatting means for producing, at the determined frame intervals, a speech burst from said digital speech signal and a data burst from said data signal respectively read by said switching control means, said speech burst containing an indication of the data rate of said speech coder;

transmitter means for transmitting the speech and data bursts to said base station;

a speech decoder for converting said digital speech signal to an analog speech signal at a variable rate; and

burst deformatting means for identifying the burst detected by the receiver means as said speech burst or said data burst, supplying said digital speech signal contained in the speech burst to the speech decoder and operating the speech decoder at a rate corresponding to the data rate indication contained in the speech burst, and supplying said data signal contained in the data burst to said data output terminal.

8. The telephone set as claimed in claim 7, further comprising a storage level detector for detecting an amount of said data signals stored in the data buffer and producing an output signal indicative of the detected amount, wherein said switching control means is responsive to the output signal of the storage level detector for operating said speech coder at a rate variable in accordance with the detected amount of said data signals stored in said data buffer.

9. A telephone set for a mobile communications system, comprising:

a data input terminal and a data output terminal to which a non-telephonic communications apparatus is adapted to be connected;

a speech coder for converting an analog speech signal to a digital speech signal at a variable rate;

a voice activity sensor for determining whether said analog speech signal is present or absent;

a speech buffer for storing digital speech signals supplied from said speech coder;

a data buffer for storing data signals from said data input terminal;

receiver means for detecting a burst from a base station;

timing control means for determining frame intervals from the burst detected by the receiver means;

a storage level detector for detecting an amount of the data signals stored in the data buffer;

switching control means for (a) operating said speech coder exclusively at a high data rate when said analog speech signal is determined to be present and the detected amount of the data signals is zero and exclusively reading digital speech signals from the speech buffer, (b) operating said speech coder at a variable data rate lower than said high data rate depending on the detected amount of the data signals when said analog speech signal is determined to be present and the detected amount of the data signals is non-zero, and reading said digital speech signal and said data signals from the speech and data buffers at different frame intervals in accordance with said lower variable data rate, and (c) exclusively reading the data signals from the data buffer when said analog speech signal is determined to be absent and the detected amount of the data signals is non-zero;

burst formatting means for producing, at the determined frame intervals, a speech burst from a digital speech signal and a data burst from data signals respectively read by said switching control means, said speech burst containing a data rate indication indicating the rate at which said speech coder is operated;

transmitter means for transmitting the speech and data bursts to said base station;

a speech decoder for converting said digital speech to said analog speech signal at a variable rate; and

burst deformatting means for identifying the burst detected by the receiver means as a speech burst or a data burst, supplying said digital speech signal contained in said speech burst to the speech decoder and operating the speech decoder at a rate corresponding to the data rate indication contained in the speech burst, and supplying said data signals contained in the data burst to said data output terminal.