ATM communications system and method
AssigneeNortel Networks Limited
InventorsSimon Daniel Brueckheimer, David John Stacey
Life of this patent
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Abstract
The invention relates to a method and apparatus for multiplexing traffic from a plurality of fixed bit rate sources over an ATM network. The traffic from the fixed bit rate users is multiplexed to form a TDM trunk group which is assembled into AAL2 minicells prior to being converted to ATM cells for transmission on the ATM network. By combining the fixed rate traffic sources into a TDM trunk group and then mapping the trunk group into AAL2 minicells, it is possible to improve efficiency of fixed bit rate traffic transmission using the ATM protocol.
Claims10
A method of communication user traffic of a plurality of low bit rate users over an asynchronous transfer mode (ATM) communications network, said method comprising the steps of;
- multiplexing traffic from each of said plurality of low bit rate users to from a trunk group;
- mapping said trunk group into ATM minicells;
- and
- assembling said minicells into ATM cells for transmission over said ATM network,
- wherein the trunk group size is varied dynamically to accommodate a change in the number of users;
- and
- an in-band chance in a trunk group size is indicated though a combination in a minicell of a change indication (CI) flag which provides a permanent change within the minicells change pulse (CP) flag which provides a position of the change within the minicells.
Apparatus for communicating user traffic of a plurality of low bit rate users over an a synchronous transfer (ATM) communications network, comprising:
- a multiplexor to multiplex traffic said plurality of low bit rate users to from a trunk group;
- an ATM mapper to map said trunk group into ATM minicells;
- and
- an assembling said minicells into ATM cells for transmission over the ATM network,
- wherein said multiplexor is arranged to dynamically vary the trunk group size to accommodate a change in the number of users and said assemble includes means for setting a change indication (CI) flag and a change pulse (CP) flag in a service specific convergence sub-layer (SSCS) control field (SCF) of a minicell in order to indicate an in-band charge in a TDM trunk group size, said CI flag providing a permanent change indication of an in-band change of said trunk group size and said CP flag providing a position of the change in said trunk group size within the minicell.
Apparatus for recovering user traffic of a plurality of low bit rate users from received ATM cells comprises:
- means for disassembling ATM cells into minicells;
- means for recovering a trunk group from said minicells;
- and
- a demultiplexer for demultiplxing said trunk group to recover said user traffic of said plurality of low bit rate users, wherein
- said disassembler includes means for determining an in-band change in a trunk group size from a combination of a change indication (CI) flag and a change pulse (CP) flag in a service specific convergence sub-layer (SSCS) of a received minicell where said CP flag provides a permanent change indication of an in-band change in said trunk group size and said CP flag provides a position of the change in aid trunk group size within the minicell.
Dependencies are inferred from the claim text.