# US 6,721,326 B1 · Cell multiplexing system and method for an ATM network

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- Number: US 6,721,326 B1
- Document ID: US6721326B1
- Status: Granted
- Kind: B1
- Application number: 09/524,321
- Filed: 2000-03-13
- Granted: 2004-04-13
- Earliest claimed: 1999-05-31
- Assignees: Fujitsu Limited
- Inventors: Kenji Shibata
- Web page: https://patentgrep.com/patent/US6721326B1

## CPC

- H04L 49/3081: {ATM peripheral units, e.g. policing, insertion or extraction}
- H04L 12/5601: {Transfer mode dependent, e.g. ATM}
- H04L 2012/5615: {Network termination, e.g. NT1, NT2, PBX}
- H04L 2012/5656: {using the AAL2}
- H04L 2012/5672: {Multiplexing, e.g. coding, scrambling}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A multiplexing system in an ATM network is disclosed. The system produces low deviation in generation timing of a standard ATM cell and low transmission delay to realize high transmission efficiency. A cell multiplexing means is provided for assembling data received from a plurality of terminal lines into a short cell to be multiplexed into a standard ATM cell. A short cell is selected from a plurality of short cells to define a reference line. The short cell generation timing of the reference line is used as the reference timing to generate short cells for other lines so as to synchronize the generation timing. The short cells thus generated are then multiplexed into a standard ATM cell.

## Claims

### Claim 1

A cell multiplexing method for multiplexing short cells into a standard ATM cell, said short cells being generated by assembling data received from a plurality of terminal lines, the method comprising the steps of:
defining a short cell from a plurality of short cells as a reference line generating short cells for other lines using a short cell generation timing of said reference line as a reference timing; and,
multiplexing said short cells thus generated into a standard ATM cell.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the step of defining the short cell as reference line includes the steps of;
deciding whether a line or lines having been in receiving state exists;
in the case no lines exist having been in receiving state, determining a line having any timing as a reference line;
in the case a line having been in receiving state exists, further deciding whether a line having the same receiving timing exists;
in the case a line having the same timing exists, determining said line as a reference line; and,
in the case any line having the same timing does not exist, determining a line having the longest timing as a reference line.
3.The method according to claim 1, further comprising the steps of;
deciding whether the amount of data having been received from a terminal line is larger than received data from a reference line; and,
in the case the received data from said terminal line is larger than that from the reference line, discarding said received data to enable an interruption of data reception from said terminal line.

### Claim 4 (depends on 1)

The method according to claim 1, wherein effective data lengths of said multiplexed short cells are informed to equipment connected on the opposite side using other route than that used for transmitting the standard cell.

### Claim 5 (depends on 4)

The method according to claim 4, wherein each predetermined effective data length for each terminal is stored in ATM switching equipment, said effective data length for a terminal being read out at the time of activating a line corresponding to said terminal.

### Claim 6

A cell multiplexing system which multiplexes short cells into a standard ATM cell, said short cells being generated by assembling data received from a plurality of terminal lines, said system comprising:
a plurality of terminal line packages each accommodating a terminal line and assembling data received on the terminal line into a short cell;
a time-division multiplexing bus for transmitting a plurality of short cells, each being assembled by a corresponding terminal line package, in time division;
an ATM cell bus for transmitting an ATM cell; and
a standard cell assembling controller provided in either one of said plurality of terminal line packages, for multiplexing the plurality of short cells assembled by the terminal line packages, as making a terminal line package in which the standard cell assembling controller is provided as a reference line, and transmitting the multiplexed short cells into the ATM cell bus.

### Claim 7 (depends on 6)

The system according to claim 6, wherein a payload of said short cell is variable in length to adjust cell assembling delay.

### Claim 8 (depends on 6)

The system according to claim 6, further comprising information transfer means for transferring the effective data length of each multiplexed short cell to equipment connected on the opposite side, by means of a route different from a route used for the standard ATM cell.

### Claim 9 (depends on 8)

The system according to claim 8, further comprising a database to specify the effective data length of short cells, said data length for a terminal being read out at the time a line corresponding to said terminal is activated for data reception.