US3838222A
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US
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Pathfinding logic for multistage time division multiplex switching network
Assignee: AT&T Inc
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Filing: 1973-03-06
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Granted: 1974-09-24
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Expires: 1993-03-06
Abstract
Abstract Pathfinding logic is described for a time division multiplex switching network of the type which includes alternate stages of time slot interchangers and mass series-parallel converters. Multiple network blocks are included in each stage of the network, and these blocks are cross-connected by grid networks at several different stages in order to provide complete access for each network input highway to any of the network output highways with a relatively low blocking probability. Logic circuits are provided for NORing time slot busy-bit signals of calling block output lines which correspond to called block input lines. The results of the NOR function comprise signals that identify a calling block output line number and time slot number which uniquely define an available time-space path between a calling highway and time slot and a called highway and time slot which are to be placed into communication with one another.
Inventors
- 👤 R Krupp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 01:49
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/04; H04Q11/08
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
164 words
In a multistage time division multiplex switching network for communicating time slot signals in successive signal frames, a plurality of input lines including a calling path, a plurality of output lines including a called path, at least one network interstage interface including a plurality of signal paths, said interface paths including a path connectible by means of said network to said calling and called paths, means for producing a signal indication at an identifiable time in response to a coincidence of predetermined signal states at inputs thereof, said coincident states indicating, respectively, a free calling path time slot, a free called path time slot, and a free one of said interface paths, means for coupling signals from said calling path to at least one input of said producing means, means for coupling signals from said called path to at least one input of said producing means, and means for coupling signals from said interface paths to at least one input of said producing means.
Claim 2
Dependent Claim
164 words
In a multistage time division multiplex switching network for communicating time slot signals in successive signal frames, a plurality of input lines including a calling path, a plurality of output lines including a called path, at least one network interstage interface including a plurality of signal paths, said interface paths including a path connectible by means of said network to said calling and called paths, means for producing a signal indication at an identifiable time in response to a coincidence of predetermined signal states at inputs thereof, said coincident states indicating, respectively, a free calling path time slot, a free called path time slot, and a free one of said interface paths, means for coupling signals from said calling path to at least one input of said producing means, means for coupling signals from said called path to at least one input of said producing means, and means for coupling signals from said interface paths to at least one input of said producing means.
Claim 3
Dependent Claim
109 words
The network in accordance with claim 1 in which said producing means comprises a coincidence gate, and means responsive to coincident-signal actuation of said gate for producing a signal transition at the time of actuation of such gate, said means for coupling calling path signals includes means for applying such signals to a first input of said gate, said means for coupling interface path signals includes means for applying such signals to a second input of said gate in different time slots for each of said interface paths, and said means for coupling calling path signals includes means for applying such signals to a third input of said gate.
Claim 4
Dependent Claim
141 words
The network in accordance with claim 1 in which said producing means comprises a plurality of coincidence gates, means responsive to coincident-signal actuation of one of said gates for producing a signal transition at the time of actuation thereof, and means responsive to coincident-signal actuation of one of said gates for producing a signal transition at a time indicative of which one of said gates was actuated, said means for coupling calling path signals includes means for applying such signals to an input of each of said gates, said means for coupling interface path signals includes means for applying such signals to inputs of different ones of said gates, respectively, and said means for coupling called path signals includes means for applying such signals to an input of a different one of said gates in each time slot of a frame.
Claim 5
Dependent Claim
71 words
The network in accordance with claim 3 in which said means for applying called path signals comprises a mass series-parallel converter having a plurality of input connections and a plurality of output connections, means for coupling each of said called path signals in multiple to all of said converter input connections, and means for coupling each of said converter output connections to an input of a different one of said gates.
Claim 6
Dependent Claim
85 words
The network in accordance with claim 3 in which said interface signal applying means comprises a mass series-parallel converter having plural input connections and plural output connections, means for coupling said interface signals from said interface paths to said converter input connections, respectively, and means for coupling said converter output connections to inputs of different ones of said gates, respectively, and said means for applying called path signals includes means for coupling said called path signals in multiple to all of said converter input connections.
Claim 7
Dependent Claim
162 words
For a multistage time division multiplex switching network in which switching is accomplished by cascaded stages of time slot intErchanging functions, a plurality of switching blocks are included at each stage, and interstage line grid networks cross-connect said blocks at predetermined stages, means for identifying a time slot number and a line number at a predetermined network stage for defining an unused time-space path through at least a part of said network, and means for coupling said identifying means across said part of said network, which part includes at least one of said grid networks, said coupling means comprising, first means for connecting an input of said identifying means to receive signals on lines at the output of a selectable block including a calling input highway of said switching network, and means for connecting said identifying means to receive signals from network lines at inputs of a selectable block including a called highway which is to be interconnected with said calling highway.
Claim 8
Dependent Claim
162 words
For a multistage time division multiplex switching network in which switching is accomplished by cascaded stages of time slot intErchanging functions, a plurality of switching blocks are included at each stage, and interstage line grid networks cross-connect said blocks at predetermined stages, means for identifying a time slot number and a line number at a predetermined network stage for defining an unused time-space path through at least a part of said network, and means for coupling said identifying means across said part of said network, which part includes at least one of said grid networks, said coupling means comprising, first means for connecting an input of said identifying means to receive signals on lines at the output of a selectable block including a calling input highway of said switching network, and means for connecting said identifying means to receive signals from network lines at inputs of a selectable block including a called highway which is to be interconnected with said calling highway.
Claim 9
Dependent Claim
63 words
The switching network in accordance with claim 6 in which an odd number of said interchanger stages are provided and an even number of mass series-parallel converter stages are interleaved with said interchanger stages, and an odd number of said grid networks are provided in a stage location pattern that is nonsymmetrical with respect to a centrally located one of said interchanger stages.
Claim 10
Dependent Claim
144 words
The switching network in accordance with claim 6 in which said identifying means includes a mass series-parallel converter, means for connecting inputs of said converter to respective output lines of said calling block, a plurality of gating means responsive to a coincidence of inputs of a predetermined signal state for producing a detectable output signal, said gating means each having input from a different output of said converter for enabling such gating means in response to an available time slot at an output of said calling block, means for connecting each of said input lines of said called block to enable a different one of said gating means in response to an available time slot at a corresponding input of said called block, and means for inhibiting said gating means in time intervals corresponding to busy time slots of said calling and called highways.
Claim 11
Dependent Claim
96 words
The switching network in accordance with claim 6 in which said identifying means includes a mass series-parallel converter, means for connecting inputs of said converter to respective output lines of said calling block, a plurality of NOR gates each having an enabling input connected to a different output of said converter, means for connecting each of said input lines of said called block to an enabling input of a different one of said NOR gates, and means for inhibiting said NOR gates in time intervals corresponding to busy time slots of said calling and called highways.
Claim 12
Dependent Claim
69 words
The network in accordance with claim 9 in which said inhibiting means comprises means for inhibiting all of said NOR gates during each calling highway time interval which includes a binary ONE signal, and means for coupling to all of said converter inputs in parallel a signal having a binary ZERO state during only those time intervals corresponding to busy-bit intervals of unused time slots on said called highway.
Claim 13
Dependent Claim
195 words
The network in accordance with claim 9 wherein said identifying means further comprises a shift register, means for coupling an output of each of said NOR gates to an input of a different stage of said shift register, means for operating said shift register at the time slot rate of time division signals in said network, and in a direction such that the final shift register stage, in the sequence of propagation, is the stage which receives the output from the one of said NOR gates which corresponds to the first occurring time slot of a frame in the time slot sequence of time division signal propagation, means for marking the occurrence time of a first output signal from said shift register so that such time corresponds to The summation of said line and time slot numbers at said predetermined stages, means for marking the occurrence time of a first output from one of said NOR gates to indicate, with respect to a network time base, a magnitude corresponding to said line number at the output of said calling block, and means for inhibiting said NOR gates for the duration of the last-mentioned marking signal.
Claim 14
Dependent Claim
161 words
For a multistage time division switching network having alterante stages of time slot interchangers and mass series-parallel converters and including multiple network blocks at each of said stages, which blocks are cross-connected at predetermined network stages, said network being adapted for the transmission of time division signals including a busy bit interval in periodically recurring time slot signal intervals, means for NORing time slot signals of corresponding lines of calling and called blocks of said network, which lines have the same line-number-time-slot-number product for any call connection utilizing such blocks, means for inhibiting said NORing means in busy-bit intervals of time slots on said calling highway for an existing call connection through said network, and means for inhibiting for a frame time interval any part of said NORing means corresponding to a called block line in the busy-bit time of each time slot of a frame including and following a busy time slot on a called highway for said call connection.
Claim 15
Dependent Claim
161 words
For a multistage time division switching network having alterante stages of time slot interchangers and mass series-parallel converters and including multiple network blocks at each of said stages, which blocks are cross-connected at predetermined network stages, said network being adapted for the transmission of time division signals including a busy bit interval in periodically recurring time slot signal intervals, means for NORing time slot signals of corresponding lines of calling and called blocks of said network, which lines have the same line-number-time-slot-number product for any call connection utilizing such blocks, means for inhibiting said NORing means in busy-bit intervals of time slots on said calling highway for an existing call connection through said network, and means for inhibiting for a frame time interval any part of said NORing means corresponding to a called block line in the busy-bit time of each time slot of a frame including and following a busy time slot on a called highway for said call connection.
Claim 16
Independent Claim
223 words
The method for identifying an available time-space signal path through a multistage time division multiplex switching network between a calling highway and a called highway, in which highways each time slot of a frame contains a busy bit signal indicating the use or nonuse of the time slot, and hich network includes plural switch blocks at each network stage and plural grid networks for cross-connecting those blocks at predetermined stages, said path being defined by time slot number and path number parameters of a path portion through said grid networks, said method comprising the steps of comparing corresponding busy bit signals from calling and called blocks at different networks stages, which stages enclose all of said grid networks, and which signals are for time slots that can be used in a call connection portion between said different stages, such comparison producing a match indication including both a time factor and a space factor that correspond to a time-space path between said different stages, inhibiting said comparing step in time slots which are occupied by existing call connections on either said calling highway or said called highway, and identifying, in response to said match indication, the time slot number of a signal match in the comparing step and the number of the grid network path between said different stages for which the match occurred.
Claim 17
Independent Claim
223 words
The method for identifying an available time-space signal path through a multistage time division multiplex switching network between a calling highway and a called highway, in which highways each time slot of a frame contains a busy bit signal indicating the use or nonuse of the time slot, and hich network includes plural switch blocks at each network stage and plural grid networks for cross-connecting those blocks at predetermined stages, said path being defined by time slot number and path number parameters of a path portion through said grid networks, said method comprising the steps of comparing corresponding busy bit signals from calling and called blocks at different networks stages, which stages enclose all of said grid networks, and which signals are for time slots that can be used in a call connection portion between said different stages, such comparison producing a match indication including both a time factor and a space factor that correspond to a time-space path between said different stages, inhibiting said comparing step in time slots which are occupied by existing call connections on either said calling highway or said called highway, and identifying, in response to said match indication, the time slot number of a signal match in the comparing step and the number of the grid network path between said different stages for which the match occurred.
Claim 18
Dependent Claim
164 words
The switching network in accordance with claim 1 in which a plurality of said interstage interfaces are included in the network, said producing means comprises a plurality of coincidence gates, said interface signal coupling means comprises a mass series-parallel converter having plural input connections and plural output connections, means for coupling said interface signals of a first one of said interfaces in the tandem sequence of stages of said network to said converter input connections, respectively, and means for coupling said converter output connections to inputs of different ones of said gates, respectively, means for coupling said interface signals of a second one of said interfaces in the tandem sequence of stages of said network to inputs of said coincidence gates, respectively, said means for coupling calling path signals includes means for applying such signals to inputs of said gates in parallel, and said means for coupling called path signals includes means for applying such signals to all inputs of said converter in parallel.
Claim 19
Dependent Claim
80 words
The switching netWork in accordance with claim 14 in which each stage of said network includes a plurality of switching blocks, and interstage line grid networks cross-connect said blocks between at least two of said stages, and said first and second interfaces are located, respectively, at the output of the last of said stages in said tandem sequence before said grid networks and at the input of the first of said stages after said grid networks in said tandem sequence.
Claim 20
Dependent Claim
88 words
The switching network in accordance with claim 1 in which each of said time slot signals includes a busy bit interval for a binary signal which indicates by the binary state thereof whether or not the time slot in which it is located is in use in a call connection through said network, and means, including said means for coupling calling, called, and interface path signals, are provided for inhibiting said producing means in response to a busy bit signal indicating a time slot in use as aforesaid.
Claim 21
Dependent Claim
68 words
The switching network in accordance with claim 1 in which each of said time slot signals includes a busy bit interval or a binary signal which indicates by the binary state thereof whether or not the time slot in which it is located is in use in a call connection through said network, and means are provided for enabling said producing means only during said busy bit intervals.
Claim 22
Dependent Claim
165 words
The switching network in accordance with claim 1 in which each stage of said network includes a plurality of switching blocks and there are provided interstage line grid circuits cross-connecting said blocks between the stages of adjacent predetermined pairs of said stages in said tandem sequence, said producing means comprises a coincidence gate, said interface signal coupling means comprises a mass series-parallel converter having plural input connections and plural output connections, means for coupling said interface signals from said interface paths to said converter input connections, respectively, and means for coupling a selectable one of said converter output connections to an input of said coincidence gate, said selectable output connection corresponding to a block of said network input lines including said calling path, said means for coupling said calling path signals includes means for applying such signals to another input of said gate, and said means for coupling said called path signals includes means for applying such signals to yet another input of said gate.
Claim 23
Dependent Claim
116 words
The switching network in accordance with claim 1 in which a plurality of coincidence gates are provided, said interface signal coupling means comprises means for applying signals of respective ones of said interface paths to inputs of different ones of said gates, respectively, said means for coupling said called path signals comprises a mass series-parallel converter having plural input connections and plural output connections, means for applying signals from said called path to all of said converter input connections simultaneously, and means for coupling said converter output connections to different ones of said gates, respectively, and said means for coupling said calling path signals comprises means for applying such signals to all of said gates simultaneously.
References Cited (Backward Citations)
US3718769A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |