Stochastic time division multiplexing
First Claim
1. A method of multiplexing a plurality of N data packets selected from M possible data packets where M>
- N, comprising the steps of;
arranging M possible data packet locations and M flag words into a frame, each flag word being identical to the other flag words, each flag word and each packet location being associated with a predetermined one of said M possible packets so that each said flag word is also associated with a predetermined one of said packet locations, and each said flag word preceding its associated packet location;
filling N of said M packet location with said N packets so that each of said N packets fills its associated packet location leaving (M-N) unfilled packet locations in said frame; and
omitting each of said (M-N) unfilled packet location so that no packet location is reserved for packets not included in said N packet locations associated with said N packets.
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Accused Products
Abstract
Stochastic Time Division Multiplexing (STOTDM) is disclosed. in STOTDM data packets are preceded by a flag word. Each data packet appears in a frame of data packets in a predetermined order. If there is no data to be placed in the packet location, only the flag is transmitted and the data location is allocated to other data. By using a fixed length frame, synchronous data packets can be placed near the beginning of the frame and packets which are not timing sensitive may follow them. A variable length frame may also be used wherein data from a plurality of sources are once again ordered and preceded by a flag word or bit. The flag may be used to indicate whether or not the packet location is filled or this may be determined by control packets. Variable length frames may be accommodated as long as the average bandwidth required to transmit the data does not exceed the channel bandwidth.
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Citations
14 Claims
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1. A method of multiplexing a plurality of N data packets selected from M possible data packets where M>
- N, comprising the steps of;
arranging M possible data packet locations and M flag words into a frame, each flag word being identical to the other flag words, each flag word and each packet location being associated with a predetermined one of said M possible packets so that each said flag word is also associated with a predetermined one of said packet locations, and each said flag word preceding its associated packet location; filling N of said M packet location with said N packets so that each of said N packets fills its associated packet location leaving (M-N) unfilled packet locations in said frame; and omitting each of said (M-N) unfilled packet location so that no packet location is reserved for packets not included in said N packet locations associated with said N packets.
- N, comprising the steps of;
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2. A method of demultiplexing a frame of STOTDM multiplexed data packets, wherein said frame includes a plurality of sequentially arranged flags, each of which may precede one of said packets or may precede the next successive flag in the absence of a packet, the method comprising the ordered steps of:
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(a) locating a first flag within said frame; (b) determining, by inspection of information following said first flag, if said first flag is followed by a second flag or a first packet; and (c) routing said first packet if it follows said first flag. - View Dependent Claims (3, 4)
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5. A method of demultiplexing a frame of STOTDM multiplexed data packets, wherein said frame includes a plurality of identical sequentially arranged flags, each of which may precede one of said packets or may precede the next successive flag in the absence of a packet, the method comprising the ordered steps of:
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(a) locating a first flag within said frame; (b) looking for a second flag after said first flag; (c) routing a first packet if said second flag is not found in step (b); and (d) looking for said second flag after said first packet is routed if said second flag is not found in step (b).
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6. A method of demultiplexing a frame of STOTDM multiplexed data packets, wherein said frame includes a plurality of identical sequentially arranged flags, each of which may precede one of said packets or may precede the next successive flag in the absence of a packet, the method comprising the ordered steps of:
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(a) reading a first flag and determining by inspecting information following said first flag whether or not a first packet follows said first flag; (b) reading a second flag after step (a) if said first packet does not follow said first flag; and (c) routing said first packet after step (a) if said first packet does follow said first flag.
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7. An apparatus for demultiplexing a stochastic time division multiplexed frame of data packets, comprising:
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detecting means for detecting a predetermined flag pattern within said frame of data packets; counting means for counting the number of flag patterns detected by said detecting means; and routing means, responsive to said counting means, for routing a data packet in accordance with said number of flag patterns. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification