Packet-switched communications network for efficiently switching non-burst signals

• US 4,815,071 A
• Filed: 08/14/1987
• Issued: 03/21/1989
• Est. Priority Date: 08/14/1986
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Shimizu, Hiroshi
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Scutch, III, Frank M.
• Application Number:
  US07/085,574
• Time in Patent Office: 585 Days
• Field of Search: 370/85, 370/86, 370/89, 370/60, 370/94, 340/825.05, 340/825.5
• US Class Current: 370/352
• CPC Class Codes: H04L 12/43 with synchronous transmission, e.g. time division multiplex [TDM], slotted rings
• CPC Class Codes: H04L 12/64 Hybrid switching systems

Abstract

In a packet-switched communications network, each of a plurality of node stations is responsive to a request for a circuit-switched call from a source user terminal and transmits a control packet and a message packet in succession to the other node stations. The control packet contains a source address, a destination address, a unique address and a time slot number identifying the time slot in which the circuit-switched call is to be carried. The message packet contains the same unique address as that sent with the preceding control packet and a plurality of time slots identified by the time slot numbers containing in various control packets. On receiving a message packet having the same unique address as that sent with a previous control packet, a destination station extracts an information signal from the message packet using the time slot number contained in the previous control packet and supplies the extracted signal to a user terminal identified by the destination address.

Claims

1. A method for communication for a packet-switched communications network in which a plurality of stations are interconnected by a transmission medium and each station services a plurality of user terminals, comprising:

communicating a unique address and first and second time slot numbers from a source station to one or more destination stations, the combination of said unique address and said first time slot number identifying a first circuit-switched call from a first source terminal of said source station to a first destination terminal and the combination of said unique address and said second time slot number identifying a second circuit-switched call from a second source terminal of said source station to a second destination terminal, said first and second destination terminals being serviced by said one or more destination stations; and

transmitting first and second circuit-switched signals from said first and second source user terminals respectively on first and second time slots of a single packet along with said unique address from said source station to said transmission medium to allow said one or more destination stations to extract said first and second circuit-switched signals from the first and second time slots in accordance with said first and second time slot numbers, respectively, and apply the extracted signals to said first and second destination terminals when said unique address contained in said packet coincides with the previously communicated unique address.

2. A method for communication for a packet-switched communications network in which a plurality of stations are interconnected by a transmission medium and each station services a plurality of user terminals, comprising:

selecting a unique address from among a plurality of specific addresses of said network smaller in number than the number of said stations;

communicating the selected unique address from a designated station to a source station;

communicating said selected unique address and first and second time slot numbers from the source station to one or more destination stations, the combination of said unique address and said first time slot number identifying a first circuit-switched call from a first source terminal of said source station to a first destination terminal and the combination of said unique address and said second time slot number identifying a second circuit-switched call from a second source terminal of said source station to a second destination terminal, said first and second destination terminals being serviced by said one or more destination stations; and

transmitting first and second circuit-switched signals from said first and second source user terminals respectively on first and second time slots of a single packet along with said unique address from said source station to said transmission medium to allow said one or more destination stations to extract said first and second circuit-switched signals from the first and second time slots in accordance with said first and second time slot numbers, respectively, and apply the extracted signals to said first and second destination terminals when said unique address contained in said packet coincides with the previously communicated unique address.

3. A packet-switched communications network having a plurality of node stations and a transmission medium of interconnecting said node stations, each of said node stations serving one or more user terminals, wherein each of said node stations comprises:

first transmit means responsive to a request for a circuit-switched call from a source user terminal of the own station for transmitting to said transmission medium a control packet containing a source address identifying said source user terminal, a destination address identifying a destination user terminal of another node station, a unique address and a time slot number identifying the position of a time slot in which a circuit-switched signal from said source user terminal is to be contained;

second transmit means for transmitting to said transmission medium a message packet containing said unique address and a plurality of time slots one of which is identified by said time slot number, said identified time slot containing said circuit-switched signal;

first receive means for receiving g said control packet through the transmission medium when the destination address contained therein coincides with the address of a user terminal serviced by the own station; and

second receive means for receiving the message packet through the transmission medium if the unique address contained therein coincides with the unique address contained in the received control packet, extracting the circuit-switched signal from the time slot of the received message packet in accordance with the time slot number contained in said received control packet and applying the extracted signal to said user terminal identified by said destination address.

4. A packet-switched communications network having a plurality of node stations and a transmission medium for interconnecting said node stations, each of said node stations serving one or more user terminals, wherein each of said node stations comprises:

means responsive to a request for a circuit-switched call from a source user terminal of the own station for transmitting to said transmission medium a control packet including a source address identifying said source user terminal, a destination address identifying a destination user terminal of another node station, a unique address and a time slot number identifying the position of a circuit-switched signal from said source user terminal;

means for receiving said control packet when the destination address contained therein coincides with the address of a user terminal serviced by the own station;

a transmit buffer having a plurality of memory cells;

transmit buffer read/write control means for writing said unique address and a plurality of circuit-switched signals from one or more source user terminals into the memory cells of said transmit buffer to compose a message packet, the memory cells storing said circuit-switched signals being identified by the respective time slot numbers contained in a plurality of said control packets, and reading said message packet out of said transmit buffer onto said transmission medium;

a receive buffer having a plurality of memory cells; and

receive buffer read/write control means for receiving the message packet through the transmission medium, detecting the unique address in said received message packet, generating a memory address in response to the detection of said unique address, establishing a relationship between the destination address, unique address and time slot number contained in each of a plurality of said received control packets and the unique address contained in the received message packet and said memory address, writing the circuit-switched signals contained in the received message packet into the memory cells of said receive buffer in accordance with said established relationship, and sequentially reading the circuit-switched signals out of said receive buffer to a plurality of destination user terminals having the same destination addresses as those contained in a plurality of said control packets.

5. A packet-switched communications network as claimed in claim 4, wherein said relationship is established by a control memory and means for writing data associated with said destination address into a cell of said control memory which is addressable as a function of the unique address and time slot number contained in the received control packet and reading said stored data out of said control memory as a function of the unique address contained in said received message packet and said incremental address into said receive buffer as a write address pointer.

6. A packet-switched communications network having a transmitting station and a receiving station interconnected by a transmission medium, each of said stations servicing a plurality of user terminals, wherein:

said transmitting station comprises means for transmitting to said receiving station a control packet in response to a request for a circuit-switched call from a source user terminal of the transmitting station, said control packet including a source address identifying said source user terminal, a destination address identifying a destination user terminal of the receiving station, a unique address and a time slot number, and a message packet including said unique address and a plurality of time slots which are identified by the time slot numbers contained in a plurality of said control packets, said time slots containing circuit-switched signals from one or more of said source user terminals; and

said receiving station comprises means for receiving said control packet when the destination address coincides with the address of a user terminal of the receiving station, receiving the message packet when the unique address contained therein coincides with the unique address contained in said received control packet, extracting the circuit-switched signals from the received message packet in accordance with the time slot numbers contained in a plurality of said control packets and applying the extracted signals to the user terminals identified by the destination addresses contained in said plurality of control packets of the receiving station.

7. A packet-switched communications network having a transmitting station and a receiving station interconnected by a transmission medium, each of said stations servicing a plurality of user terminals:

wherein said transmitting station comprises;

means responsive to a request for a circuit-switched call from a source user terminal of the own station for transmitting to said transmission medium a control packet including a source address identifying said source user terminal, a destination address identifying a destination user terminal of another node station, a unique address and a time slot number identifying the position of a time slot in which a circuit-switched signal from said source user terminal is to be contained;

a transmit buffer having a plurality of memory cells; and

transmit buffer read/write control means for writing said unique address and a plurality of circuit-switched signals from one or more source user terminals into the memory cells of said transmit buffer to compose a message packet, the memory cells storing said circuit-switched signals being identified by the respective time slot numbers contained in a plurality of said control packets, and reading said message packet out of said transmit buffer onto said transmission medium;

wherein said receiving station comprises;

means for receiving said control packet when the destination address contained therein coincides with the address of a user terminal of the receiving station;

a receive buffer having a plurality of memory cells; and

receive buffer read/write control means for receiving the message packet through the transmission medium, detecting the unique address in said received message packet, generating a memory address in response to the detection of said unique address, establishing a relationship between the destination address, unique address and time slot number contained in each of a plurality of said received control packets and the unique address contained in the received message packet and said memory address, writing the circuit-switched signals contained in the received message packet into the memory cells of said receive buffer in accordance with said established relationship, and sequentially reading the circuit-switched signals out of said receive buffer to a plurality of destination user terminals having the same destination addresses as those contained in a plurality of said control packets.

8. A packet-switched communications network as claimed in claim 7, wherein said relationship is established by a control memory and means for writing data associated with said destination address into a cell of said control memory which is addressable as a function of the unique address and time slot number contained in the received control packet and reading said stored data out of said control memory as a function of the unique address contained in said received message packet and said incremental address into said receive buffer as a write address pointer.

9. A packet-switched communications network having a first station and a plurality of second stations and a transmission medium for interconnecting said first station and said second stations, each of said second stations serving one or more user terminals and including means for transmitting a request for a circuit-switched call to said transmission medium, wherein said first station comprises:

means for selecting a unique address from among a plurality of unique addresses smaller in number than the number of said second stations, assigning the selected unique address to a circuit-switched call request transmitted from one of said second stations and transmitting said assigned unique address to said transmission medium, and wherein said second station which transmits said call request comprises;

first receive means for receiving said assigned unique address through said transmission medium;

first transmit means for transmitting to said transmission medium a control packet containing a source address identifying a source user terminal of the own station, a destination address identifying a destination user terminal of another station, said received unique address and a time slot number identifying the position of a time slot in which a circuit-switched signal from said source user terminal is to be contained;

second transmit means for transmitting to said transmission medium a message packet containing said unique address and a plurality of time slots one of which is identified by said time slot number, sad identified time slot containing said circuit-switched signal;

said first receive means receiving the control packet through the transmission medium when the destination address contained therein coincides with the address of a user terminal serviced by the own station; and

second receive means for receiving the message packet through the transmission medium when the unique address contained therein coincides with the unique address contained in the received control packet, extracting the circuit-switched signal from the time slot of the received message packet in accordance with the time slot number contained in said received control packet and applying the extracted signal to the user terminal identified by said destination address.

10. A packet-switched communications network as claimed in claim 9, wherein said second transmit means comprises:

a transmit buffer having a plurality of memory cells; and

transmit buffer read/write control means for writing said received unique address and a plurality of circuit-switched signals from one or more source user terminals into the memory cells of said transmit buffer to compose said message packet, the memory cells storing said circuit-switched signals being identified by the. respective time slot numbers contained in a plurality of said control packets, and reading said message packet out of said transmit buffer onto said transmission medium, wherein said second receive means comprises;

a receive buffer having a plurality cells; and

receive buffer read/write control means for receiving the message packet through the transmission medium, detecting the unique address in said received message packet, generating a memory address in response to the detection of said unique address, establishing a relationship between the destination address, unique address and time slot number contained in each of a plurality of said received control packets and the unique address contained in the received message packet and said memory address, writing the circuit-switched signals contained in the received message packet into the memory cells of said receive buffer in accordance with said established relationship, and sequentially reading the circuit-switched signals out of said receive buffer to a plurality of destination user terminals having the same destination addresses as those contained in a plurality of said control packets.