Optical telecommunication package switching system using asynchronous techniques

• US 4,845,702 A
• Filed: 02/23/1988
• Issued: 07/04/1989
• Est. Priority Date: 03/12/1987
• Status: Expired due to Fees

• Current Assignee: Cselt - Centro Studi E Laboratori Telecommunicazioni SPA
• Original Assignee: Cselt - Centro Studi E Laboratori Telecommunicazioni SPA
• Inventors: Melindo, Flavio
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Van Beek, Leslie
• Application Number:
  US07/159,215
• Time in Patent Office: 497 Days
• Field of Search: 455/606, 455/607, 455/612, 455/616, 455/617, 455/619, 455/600, 370/1, 370/34
• US Class Current: 398/54
• CPC Class Codes: C03C 14/00 Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed in a glass matrix devitrified glass ceramics C03C10/00
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5605 Fibre
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 49/106 using space switching, e.g. crossbar or matrix
• CPC Class Codes: H04L 49/1553 Interconnection of ATM switching modules, e.g. ATM switching fabrics
• CPC Class Codes: H04L 49/3081 ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04L 49/405 Physical details, e.g. power supply, mechanical construction or backplane of ATM switches
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 2011/0011 using wavelength conversion
• CPC Class Codes: H04Q 2011/0039 Electrical control

Abstract

An optical switching system, wherein the input channels carrying packetized data are switched one-by-one at high bit rate to output channels through an optical switching network. The packets of a generic input channel are time compressed, converted into optical signals and, at suitable instants, sent to an optical switching network to be switched to the desired output channel, they are then reconverted into electrical signals and expanded to their original duration. A centralized processor controls the channel switching through the switching network by means of a driving circuit.

Claims

1. An optical switching system, comprising:

a multiplicity of input channels receiving packetized data to be switched packet-by-packet to a multiplicity of output channels;

respective time compressors connected to said input channels;

means for converting electrical signals at outputs of said time compressors into respective optical signals;

an optical switching network receiving said optical signals corresponding to the electrical signals at the outputs of said time compressors for switching said optical signals to respective optical outputs of said switching network, each assigned to a respective one of said optical channels;

means for converting optical signals appearing at each of said optical outputs into respective output electrical signals assigned to each of said output channels;

a respective time expander connected to receive each of said output electrical signals for expanding it to a duration corresponding to the duration of the original packet switched to the said output channel, whereby an output of each time expander forms the respective output channel; and

a driving circuit connected to said optical switching network and controlled by a centralized processor for controlling said optical switching network to switch the optical signals corresponding to each packet at a respective time compressor to the respective optical output and the corresponding output channel,

said optical switching network comprising a plurality of parallel optical guides crossed by two guides forming a small angle (β

) and an angle (180°

-β

) supplementary to the said small angle with the parallel guides, crosspoints of said guides being provided with electrode pairs to which a voltage difference is applied to generate an electrical field for the deviation of the light signal from the parallel guides to the crossing guides and from the crossing guides to the parallel guides,

said time compressors each comprise a FIFO memory wherein octets forming said packets are progressively stored at their arrival together with a presence bit and at suitable instants are sent to a parallel-to-serial converter to be transformed into serial packets at high bit-rate and then to be transformed into optical packets by an electro-optical transducer and sent through an optical fiber to the switching network;

said driving circuit comprising a decoder for decoding packet destination address and comprises for each input channel

a SET RESET flip-flop whose reset input is enabled by octet absence in said FIFO memory, through said presence bit, and by a signal with the meaning of a busy switching network, while the set input is enabled by octet presence in the memory, by a signal of packet writing end in the memory, supplied by said centralized processor, by a scanning periodic signal with a period dependent on the desired transfer speed, and by the absence of the signal with the meaning of the busy switching network, the signal at the output of this flip-flop being used to enable an associated time compressor and time expander;

a gate whose input is connected to the flip-flop output and whose output drives a line on which a signal relevant to switching network availability is present;

a register, which stores destination addresses of the packets forming the input channel and two bits with the meaning of order number of the input channel greater than that of the output one and vice versa under the control of said centralized processor, the transfer to the output of said data being enabled by the signal at the output of the flip-flop; and

a combinational circuit having two outputs are alternatively active as a function of the two bits with the meaning of order number of the input channel greater or smaller than that of the output one when enabled by the signal at the output of the flip-flop or when enabled by the signal supplied by said decoder, one of the two outputs of the combinational circuit being used to drive an electrode pair of said switching network,

said time expanders each having an optical fiber connected to the switching network wherefrom high bit-rate packets are extracted for an opto-electrical transducer, which sends them to a serial-to-parallel converter apt to drive a FIFO memory, wherefrom the orignal packetized signal is extracted, the opto-electrical transducer, the serial-to-parallel converter and the FIFO memory being enabled by a signal supplied by said flip-flop.

2. An optical switching system, comprising:

a multiplicity of input channels receiving packetized data to be switched packet-by-packet to a multiplicity of output channels;

respective time compressors connected to said input channels;

means for converting electrical signals at outputs of said time compressors into respective optical signals;

an optical switching network receiving said optical signals corresponding to the electrical signals at the outputs of said time compressors for switching said optical signals to respective optical outputs of said switching network, each assigned to a respective one of said optical channels;

means for converting optical signals appearing at each of said optical outputs into respective output electrical signals assigned to each of said output channels;

a respective time expander connected to receive each of said output electrical signals for expanding it to a duration corresponding to the duration of the original packet switched to the said output channel, whereby an output of each time expander forms the respective output channel; and

a driving circuit connected to said optical switching network and controlled by a centralized processor for controlling said optical switching network to switch the optical signals corresponding to each packet at a respective time compressor to the respective optical output and the corresponding output channel,

said optical switching network comprising a plurality of parallel optical guides crossed by two guides forming a small angle (β

) and an angle (180°

-β

) supplementary to the said small angle with the parallel guides, crosspoints of said guides being provided with electrode pairs to which a voltage difference is applied to generate an electrical field for the deviation of the light signal form the parallel guides to the crossing guides and from the crossing guides to the parallel guides.

3. An optical switching system, comprising:

a multiplicity of input channels receiving packetized data to be switched packet-by-packet to a multiplicity of output channels;

respective time compressors connected to said input channels;

means for converting electrical signals at outputs of said time compressors into respective optical signals;

an optical switching network receiving said optical signals corresponding to the electrical signals at the outputs of said time compressors for switching said optical signals to respective optical outputs of said switching network, each assigned to a respective one of said optical channels;

means for converting optical signals appearing at each of said optical outputs into respective output electrical signals assigned to each of said output channels;

a respective time expander connected to receive each of said output electrical signals for expanding it to a duration corresponding to the duration of the original packet switched to the said output channel, whereby an output of each time expander forms the respective output channel; and

a driving circuit connected to said optical switching network and controlled by a centralized processor for controlling said optical switching network to switch the optical signals corresponding to each packet at a respective time compressor to the respective optical output and the corresponding output channel, said time compressors each comprising a FIFO memory wherein octets forming said packets are progressively stored at their arrival together with a presence bit and at suitable instants are sent to a parallel-to-serial converter to be transformed into serial packets at high bit-rate and then to be transformed into optical packets by an electro-optical transducer and sent through an optical fiber to the switching network.

4. An optical switching system, comprising;

a multiplicity of input channels receiving packetized data to be switched pack-by-packet to a multiplicity of output channels,

respective time compressors connected to said input channels;

means for converting electrical signals at outputs of said time compressors into respective optical signals;

an optical switching network receiving said optical signals corresponding to the electrical signals at the outputs of said time compressors for switching said optical signals to respective optical outputs of said switching network, each assigned to a respective one of said optical channels;

means for converting optical signals appearing at each of said optical outputs into respective output electrical signals assigned to each of said output channels;

a respective time expander connected to receive each of said output electrical signals for expanding it to a duration corresponding to the duration of the original packet switched to the said output channel, whereby an output of each time expander forms the respective output channel; and

a driving circuit connected to said optical switching network and controlled by a centralized processor for controlling said optical switching network to switch the optical signals corresponding to each packet at a respective time compressor to the respective optical output and the corresponding output channel, said driving circuit comprising a decoder for decoding packet destination address and comprises for each input channel,

a SET RESET flip-flop whose reset input is enabled by octet absence in said FIFO memory through said presence bit, and by a signal with the meaning of a busy switching network, while the set input is enabled by octet presence in the memory, by a signal of packet writing end in the memory, supplied by said centralized processor, by a scanning periodic signal with a period dependent on the desired transfer speed, and by the absence of the signal with the meaning of the busy switching network, the signal at the output of this flip flop being used to enable an associated time compressor and time expander;

a gate whose input is connected to the flip-flop output and whose output drives a line on which a signal relevant to switching network availability is present;

a register, which stores destination addresses of the packets forming the input channel and two bits with the meaning of order number of the input channel greater than that of the output one and vice versa under the control of said centralized processor, the transfer to the output of said data being enabled by the signal at the output of the flip-flop; and

a combinational circuit having two outputs are alternatively active as a function of the two bits with the meaning of order number of the input channel greater or smaller than that of the output one when enabled by the signal at the output of the flip-flop or when enabled by the signal supplied by said decoder, one of the two outputs of the combinational circuit being used to drive an electrode pair of said switching network.

5. An optical switching system, comprising:

a multiplicity of input channels receiving packetized data to be switched packet-by-packet to a multiplicity of output channels;

respective time compressors connected to said input channels;

means for converting electrical signals at outputs of said time compressors into respective optical signals;

an optical switching network receiving said optical signals corresponding to the electrical signals at the outputs of said time compressors for switching said optical signals to respective optical outputs of said switching network, each assigned to a respective one of said optical channels;

means for converting optical signals appearing at each of said optical outputs into respective output electrical signals assigned to each of said output channels;

a respective time expander connected to receive each of said output electrical signals for expanding it to a duration corresponding to the duration of the original packet switched to the said output channel, whereby an output of each time expander forms the respective output channel; and

a driving circuit connected to said optical switching network and controlled by a centralized processor for controlling said optical switching network to switch the optical signals corresponding to each packet at a respective time compressor to the respective optical output and the corresponding output channel, wherein said time expanders each having an optical fiber connected to the switching network wherefrom high bit-rate packets are extracted for an opto-electrical transducer, which send them to a serial-to-parallel converter apt to drive a FIFO memory, wherefrom the original packetized signal is extracted, the opto-electrical transducer, the serial-to-parallel converter and the FIFO memory being enabled by a signal supplied by said flip-flop.