Integrated voice/data network

• US 4,665,514 A
• Filed: 08/02/1985
• Issued: 05/12/1987
• Est. Priority Date: 08/02/1985
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Huang, Nian-Chyi, Ching, Yau-Chau, Tomcik, James D.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Kuntz, Curtis
• Application Number:
  US06/762,131
• Time in Patent Office: 648 Days
• Field of Search: 370/60, 370/94, 370/85, 370/111, 370/109, 179/2 EB
• US Class Current: 370/392
• CPC Class Codes: H04J 3/1688 the demands of the users being taken into account after redundancy removal, e.g. by predictive coding, by variable sampling reducing bandwidth of signals in general H04B1/66; in PCM-systems H04B14/046; removal of redundancy in telegraph communication H03M7/30
• CPC Class Codes: H04L 12/64 Hybrid switching systems

Abstract

Circuits at a remote transmission site receive digitized voice and data samples from incoming channels. The voice samples are compressed. The samples are formatted into fixed-size data blocks with signaling and control information for transmission to a switching node. Additional bits of the voice samples are dynamically dropped, if necessary, to fit the data into the fixed-sized blocks. The signaling and control information allows receiving circuits at the switching node to determine the number of bits allocated to each sample. These receiving circuits form packets for individual channels by attaching switch routing packet headers to the individual channel data. Packet receiving circuits on the output side of the switch reformat the received packets into fixed-size nonpacket data blocks for transmission.

Claims

1. A data switching network comprising

at least one packet switching node containing a packet switch,

at least one remote transmission site and data transmission means between the remote site and switching node, said remote site having

means for receiving digitized voice and data samples from a plurality of incoming digital channels on each recursive scan of the channels,

means responsive to the receiving means for detecting active and idle data intervals on the incoming channels,

means responsive to the detecting means for dynamically compressing the digitized voice samples in an instant scan of samples so that the instant data samples and compressed voice samples fit into a fixed size data block, each data block containing logical channel numbers for the digitized voice and data samples assigned to each incoming channel at the beginning of an active interval, and the samples,

means for transmitting the data blocks to said switching node, said packet switching node further comprising

means at an input side (R section of LTI) of the switching node for receiving the data blocks and containing

means for separating the samples associated with different logical channel numbers,

means for attaching packet headers containing a switch routing address to the separated samples to form packets,

means for transmitting the packets to the switch,

a plurality of means at an output side (T section of LTI) of the switch for receiving packets from the switch, and containing

means for stripping away the packet headers,

means for reformatting the digitized voice and data samples into said fixed-size data blocks, and

means for transmitting the data blocks to another switching node or remote transmission node.

2. The invention of claim 1 wherein the switch comprises

a digital sorting network for sorting the packets in accordance with the switch routing address, and

a banyan network having expanded routing paths to provide a prescribed number of separate paths through the banyan network to each receiving means on the output side of the switch.

3. The invention of claim 1 wherein the receiving means at the input side of the switch further comprises

means for storing switch routing addresses in association with logical channel numbers to enable generation of the packet headers.

4. The invention of claim 1 wherein the fixed-size data block generating means at a remote transmission site further comprises

means for classifying incoming call samples on established calls as digitized voice samples or digital data,

means for generating an active signaling word or an idle signaling word when a respective beginning or ending of an active data interval is detected on a call,

means responsive to the classifying means and to the active/idle signaling words for calculating the space of the fixed-size data blocks required to transmit signaling and control information, and

means responsive to the calculating means for dropping one or more of the least significant bits of the call samples classified as digitized voice samples so that all samples and signaling and control information fit within the fixed-size data block.

5. The invention of claim 4 wherein the calculating means further comprises

means for determining a number of the digitized voice samples which may be allocated an extra bit after the initial bit-dropping calculation and still have all the samples and signaling and control information fit within the fixed-size data block.

6. The invention of claim 1 wherein the generating means at the remote transmission site further comprises

means for including in the signaling and control information for each call entry an active/idle indication, a digitized voice/non-digitized voice indication, a logical channel number assigned to the call, and an indication of the number of call entries present in the data block.

7. The invention of claim 1 wherein the generating means at the remote transmission site further comprises

means for detecting call originations and terminations, and

means responsive to the detection of a call origination or a termination for generating a call entry having a prescribed logical channel number reserved for control functions.

8. The invention of claim 7 wherein each switching node further comprises

a central processing unit connected to a port of the switch corresponding to the prescribed logical channel number reserved for control functions, so that packets generated by an input receiving means having the precribed logical channel number are directed to the central processing unit.

9. The invention of claim 8 wherein the central processing unit is a means for determining an appropriate route through the switch in response to a call origination packet from an input receiving means and for generating a packet containing a destination output receiving means and for returning the generated packet through the switch to the input receiving means.

10. The invention of claim 9 wherein the input receiving means further comprises

means for storing the identity of the destination output receiving means.

11. The invention of claim 10 wherein the input receiving means further comprises

means for storing the active/idle indications and the digitized voice/non-digitized voice indications from the remote transmission site in association with the corresponding logical channel numbers.

12. The invention of claim 11 wherein the input receiving means further comprises

means responsive to the active/idle and the digitized/non-digitized voice indications for determining the number of bits allocated to samples of each channel in each data block from the remote transmission site,

means for collecting samples for each call into packets,

means for attaching packet headers containing an address of an appropriate output receiving means, and

means for transmitting the packets to the switch.

13. A data switch network comprising

one or more packet switching nodes, each having a packet switch self-routing based on address information contained in headers of packets,

a plurality of input trunk interface means connected to the switch at a switching node,

a plurality of output trunk interface means connected to the switch at a switching node,

a central processing unit connected to the switch at a switching node,

a plurality of remote transmission nodes,

transmission links connecting the remote transmission nodes to ones of the input trunk interface means for the transmission of digital signals pertaining to individual calls in non-packet format, and wherein each of the input trunk interface means further comprises

means addressed by relative addresses assigned to the individual calls and contained in the digital signals for storing addresses of ones of the output trunk interface means,

means for accumulating a prescribed number of the digital signals for each call into individual data segments,

means for appending a header to each segment to create a packet, each header including an address of an output trunk interface means taken from the storing means,

means for transmitting the packets to the packet switch, and wherein the output trunk interface means comprises

means for reformatting data received in the packets for output transmission in nonpacket format.

14. The invention of claim 13 wherein each remote transmission node further comprises

means for packing call samples and signaling information pertaining to calls in progress into blocks of fixed size for transmission on a said transmission link to a packet switching node.

15. The invention of claim 14 wherein the means for packing further comprises

means for classifying incoming call samples on established calls as digitized voice samples or digital data,

means for detecting dataspurts and talkspurts on the established incoming calls,

means for generating an active signaling word during dataspurts or talkspurts of each call or an idle signaling word when an ending of a dataspurt or talkspurt is detected on a call,

means responsive to the classifying means and to the active/idle signals for calculating the space of the fixed-size transmission blocks required to transmit the signaling and control information on this pass for established calls, and

means responsive to the calculating means for further compressing the present call samples classified as digitized voice samples to fit with the signaling and control information in the fixed-size transmission block.

16. The invention of claim 15 in which the means for further compressing the digitized voice samples comprises means for dropping one or two of the least significant bits of each of the digitized voice samples in accordance with the results from the calculating means.

17. The invention of claim 16 wherein the calculating means further comprises

means for determining a number of the digitized voice samples which may be allocated an extra bit after the initial bit-dropping calculation and still have the signaling and control information and samples fit within the fixed-size transmission block.

18. The invention of claim 17 wherein each remote transmission node further comprises

means for including in the signaling and control information for each call entry an active/idle indication, a digitized voice/non-digitized voice indication, a logical channel number assigned to the call and an end of signaling and control field indication in the last such entry.

19. The invention of claim 18 wherein each remote transmission node further comprises

means for detecting call originations and terminations and for generating a signaling and control field entry having a prescribed logical channel number reserved for control functions in response thereto.

20. The invention of claim 19 wherein the central processing unit is connected to the switching fabric at a port corresponding to the prescribed logical channel number reserved for control functions, so that packets generated by an input trunk interface means having the prescribed logical channel number are directed to the central processing unit.

21. The invention of claim 20 wherein the central processing unit is a means for determining an appropriate route through the switching fabric in response to a call origination packet from an input trunk interface means and for generating a packet containing a destination output trunk interface means and for returning the generated packet through the switch fabric to the input trunk interface means.

22. The invention of claim 21 wherein the input trunk interface means further comprises

means for storing the identity of the destination output trunk interface means.

23. The invention of claim 22 wherein the input trunk interface means further comprises

means for storing the active/idle indications and the digitized voice/non-digitized voice indications from the remote trunk interface means in association with the corresponding logical channel numbers.

24. The invention of of claim 23 wherein the input trunk interface means further comprises

means responsive to the active/idle and the digitized/non-digitized voice indications for determining the number of bits allocated to samples of each cell,

means for collecting samples for each cell into packets,

means for attaching packet headers containing an address of an appropriate output trunk interface means, and

means for transmitting the packets to the switch.

25. The invention of claim 24 wherein the switch comprises

a sorting network having N inputs for receiving packets from N input trunk interface means and N outputs, the sorting network being operable to arrange the incoming packets in numerical order on the N outputs according to the addresses of the output trunk interface means contained in the packet headers, and an expanded banyan network having N times K paths through the network wherein K is the number of connections from the switch to each output trunk interface means, and log₂ (N times K)-Log₂ (K) binary switching stages.