Automatic echo cancellation for an integrated services digital network interface

• US 6,430,162 B1
• Filed: 06/24/1999
• Issued: 08/06/2002
• Est. Priority Date: 10/04/1994
• Status: Expired due to Term

• Current Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Original Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Inventors: Bielsker, Barry, Reese, Charles A.
• Primary Examiner(s): Vincent, David
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US09/339,613
• Time in Patent Office: 1,139 Days
• Field of Search: 370/286, 370/287, 370/289, 370/252, 370/254, 370/264, 370/265, 370/268, 370/269, 370/270, 370/465, 370/493, 370/494, 370/495, 379/87, 379/88.04, 379/88.07, 379/88.08, 379/100.05, 379/158, 379/282, 379/93.01, 379/406.01, 379/406.03, 379/406.05, 379/406.06
• US Class Current: 370/286
• 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: H04Q 11/0428 Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
• CPC Class Codes: H04Q 11/0464 Primary rate access circuits
• CPC Class Codes: H04Q 2213/13003 Constructional details of switching devices
• CPC Class Codes: H04Q 2213/1302 Relay switches
• CPC Class Codes: H04Q 2213/13034 A/D conversion, code compression/expansion
• CPC Class Codes: H04Q 2213/1304 Coordinate switches, crossbar, 4/2 with relays, coupling field
• CPC Class Codes: H04Q 2213/1307 Call setup
• CPC Class Codes: H04Q 2213/13176 Common channel signaling, CCS7
• CPC Class Codes: H04Q 2213/1319 Amplifier, attenuation circuit, echo suppressor
• CPC Class Codes: H04Q 2213/13202 Network termination [NT]
• CPC Class Codes: H04Q 2213/13204 Protocols
• CPC Class Codes: H04Q 2213/13205 Primary rate access, PRI
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/1327 Release and resetting of connection
• CPC Class Codes: H04Q 2213/1332 Logic circuits
• CPC Class Codes: H04Q 2213/13386 Line concentrator

Abstract

An echo canceler is connected to an ISDN Primary Rate Interface. The echo canceler is provided with an activation processor for monitoring call control messages on the D-channel and for selectively enabling or disabling echo cancellation on any of the B-channels in response to information contained within the call control messages. In particular, the activation processor decides whether to enable cancellation depending upon the Information Transfer Capability and Protocol Identification fields of the Bearer Capability portion of a call SETUP message. Additionally, the Channel Identification field of the SETUP message is used to identify the B-channel or channels affected by the SETUP message. When a channel is released, the activation processor maintains enabled echo cancellation as the default condition of the released channel. Other signal processing functions can be controlled by the activation processor in a similar manner.

Claims

1. A method of processing telecommunications signals on a digital communication link having a plurality of communication channels, comprising the steps of:

detecting a request message on a first channel of the link to establish a requested call to be conducted on a second channel of the link;

determining on the basis of information in the request message, and prior to establishment of the requested call, whether the requested call is to communicate digital information of a predetermined type designated for an audio signal processing function to be applied to signals communicated during the call;

applying said audio signal processing function to the signals communicated during the call;

storing an outcome of said determining step prior to establishing the requested call; and

retrieving said outcome when the requested call is established to effect selective application of said audio signal processing function.

2. An echo canceler that provides echo cancellation for two-way communication channels that carry digitized signals on first and second transmission channels, echo signals on the second transmission channel, digital signals carried on the first transmission channel, the echo canceler comprising:

an input terminal for receiving the first and second transmission channels;

means for minimizing the magnitude of the echo signals on the second transmission channel;

means for monitoring digitized control information associated with the establishment of communications over the two-way communication channels;

means coupled to the monitoring means for determining a type of digitized information to be carried by the two-way communication channels, prior to the establishment of a call connection along either of the channels;

means, responsive to said determining means and coupled to said minimizing means, for automatically controlling whether said minimizing means minimizes echo signals on the two-way communication channels based on the type of digitized information determined to be carried on the respective two-way communication channels, whereby echo cancellation for each communication channel is automatically controlled based on the type of digitized information to be carried by each communication channel; and

an output terminal for transmitting the the first and second communication channel signals on which echo signals have been selectively minimized by the minimizing means.

3. The echo canceler according to claim 2, wherein said monitoring means monitors first control messages associated with the establishment of communications on said two-way communication channels, said first control messages containing a first data field which identifies the type of digitized information to be carried, said monitoring means reading said first data field and said determining means making a type determination based on the first data field.

4. The echo canceler according to claim 3, wherein said monitoring means comprises means for sensing an initial request message for the establishment of a communication channel, and means for sensing an acknowledgment message in response to the initial request message, the acknowledgment message indicating whether a communication channel will be allocated in response to the initial request message;

said controlling means automatically controlling whether said minimizing means minimizes echo signals on a two-way communication channel based on the type of digitized information determined to be carried and, based on whether a corresponding acknowledgment message has indicated that a corresponding communication channel will be allocated.

5. The echo canceler according to claim 2, wherein said controlling means comprises means for generating control signals based on the type of digitized information determined to be carried on said two-way communication channels and transmitting said control signals to the minimizing means, said minimizing means comprising means responsive to the control signals for enabling and disabling the cancellation of echo signals based on the control signals.

6. The echo canceler according to claim 5, wherein the digitized signals are carried in packets, the monitoring means monitoring the first control messages which are also carried in packets.

7. In an echo canceler that provides echo cancellation for two-way communication channels that carry digitized signals on first and second transmission channels, echo signals on the second transmission channel being an undesired replica of digital signals carried on the first transmission channel, a method comprising the steps of:

receiving the two-way communication channels at an input terminal;

monitoring digitized control information associated with the establishment of communications over the two-way communication channels, prior to the establishment of call connections along each of the channels;

determining, based on the control information monitored, a type of digitized information to be carried on the two-way communication channels during a subsequent call connection to be made after receipt of the digitized control information;

automatically controlling whether minimization of the echo signals will be enabled on each of the two-way communication channels based on the type of digitized information ascertained by the determining step;

minimizing echo signals along a communication channel during a call connection made subsequent to receipt of the control information; and

transmitting signals along said communications channels after said minimizing step.

8. The method according to claim 7, wherein said monitoring step monitors first control messages associated with the establishment of communications on said two-way communication channels, said first control messages containing a first data field which identifies the type of digitized information to be carried, said monitoring step reading said first data field and said determining step making a type determination based on the first data field.

9. The method according to claim 8, wherein said controlling step comprises the steps of generating control signals based on the type of digitized information determined to be carried on said two-way communication channels, said minimizing step selectably minimizing cancellation of echo signals based on the control signals.

10. The method according to claim 9 wherein the digital signals are carried in transmission frames, the monitoring step monitoring the first control messages which are also carried in transmission frames.

11. The method according to claim 8, wherein the monitoring step further comprises the steps of sensing an initial request message for the establishment of a control channel and sensing an acknowledgment message in response to the initial request message, the acknowledgment message indicating whether a communication channel will be allocated in response to the initial request message;

the controlling step controlling whether the echo signals will be minimized on a two-way communication channel based on the type of digitized information determined and based on whether a corresponding acknowledgment message has indicated a communication channel will be allocated.

12. An echo canceler that provides echo cancellation for two-way communication channels that carry digitized signals on first and second transmission channels, echo signals on the second transmission channel being an undesired replica of digital signals carried on the first transmission channel, the echo canceler comprising:

a canceling circuit that selectably minimizes the magnitude of the echo signals on the second channel;

a controller coupled to the canceling circuit, the controller comprising;

a monitor that monitors digitized control information associated with the establishment of communications over the two-way communication channels, prior to call connections being established over the two-way communication channels;

a decoder coupled to the monitor for determining a type of digitized information to be carried on the two-way communication channels;

the controller, responsive to said decoder, automatically controlling whether said canceling circuit subsequently minimizes echo signals on each of the two-way communication channels based on the type of digitized information determined to be carried on the respective two-way communication channels prior to connection of a call, whereby echo cancellation is automatically controlled based on the type of digitized information to be carried by each channel, and whereby such control is effective simultaneously with connection of a call.

13. The echo canceler according to claim 12 wherein the controller further comprises means for sensing an initial request message for the establishment of a communication channel, and means for sensing an acknowledgment message in response to the initial request message, the acknowledgment message indicating whether a communication channel will be allocated in response to the initial request message;

the controller automatically controlling whether the canceling circuit minimizes echo signals on a two-way communication channel based on the type of digitized information determined and based on whether the corresponding acknowledgment message indicated a communication channel will be allocated.

14. The echo canceler according to claim 12 wherein said monitor monitors first control messages associated with the establishment of communications on said two-way communication channels, said first control messages containing a first data field which identifies the type of digitized information to be carried, said decoder reading said first data field and determining a type determination based on the first data field.

15. The echo canceler according to claim 12 wherein said controller generates control signals based on the type of digitized information determined to be carried on said two-way communication channels and transmits said control signals to the canceling circuit which responds to the control signals by selecting whether or not to minimize cancellation of echo signals on a per channel basis based on the control signals.

16. The echo canceler according to claim 12 wherein the digitized signals are carried in transmission frames, and the monitoring means monitors the first control messages which are also carried in transmission frames.