System and method for creating N-times bandwidth from N separate physical lines

• US 5,923,667 A
• Filed: 02/27/1997
• Issued: 07/13/1999
• Est. Priority Date: 06/28/1996
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Teleoglou, Spiros, Suffern, Edward, Poiraud, Clement
• Primary Examiner(s): VU, HUY DUY
• Application Number:
  US08/807,496
• Time in Patent Office: 866 Days
• Field of Search: 370/536, 370/535, 370/537, 370/539, 370/540, 370/542, 370/544, 370/503, 370/506, 370/509, 370/510, 370/511, 370/515, 370/512, 370/514, 370/516, 370/517, 370/518, 370/519 , 370/484, 375/354, 375/359, 375/362, 375/365, 375/367, 375/366, 375/368, 375/371
• US Class Current: 370/515
• CPC Class Codes: H04J 3/0611 PN codes H04J3/0608 takes precedence
• CPC Class Codes: H04J 3/0626 plesiochronous multiplexing systems, e.g. plesiochronous digital hierarchy [PDH], jitter attenuators
• CPC Class Codes: H04J 3/1641 Hierarchical systems
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver

Abstract

A method and system aggregate data on multiple physically separate lower-speed E1/J1 channels of a communications network to generate higher bandwidth. A high speed data stream is first divided into lower bandwidth channels and transmitted through the network. The data arrives with varying delays depending on the physical characteristics of the network. Low bandwidth channels are aggregated together into a high bandwidth channel by determining the different geographical delay parameters among the lower speed channels, adjusting the transmission delays by alignment circuitry, and then combining the lower speed signals into one high bandwidth channel for the user. The transmission delay adjustment consists in adding a pseudo-random noise pattern to each of the lower bandwidth channels, measuring the time difference among all the channels, and then adjusting the time differences in the received data stream so that the combination of the signals produces a coherent higher bandwidth data stream. Because of the enhanced delay compensation mechanism, there is virtually no distance limitation in the transmission of data and if one of the lower physical telecommunication lines becomes inoperative, bandwidth recovery is provided.

Claims

1. A method in a communication network for assembling a relatively high bandwidth data stream from a plurality of relatively low bandwidth data streams each having a plurality of data frames, which are received from a respective plurality of relatively low bandwidth telecommunications channels, comprising the steps of:

(a) equalizing transmission time delay among said plurality of low bandwidth data streams by equalizing time delay among the associated plurality of low bandwidth telecommunications channels;

wherein said equalizing step comprises the steps of;

(i) receiving a plurality of data frames concurrently transmitted across each of said low bandwidth channels;

(ii) extracting an alignment signal concurrently inserted in each corresponding data frame of each of said low bandwidth data streams, said alignment signal being a pseudo-random noise bit, said bit being in the same bit position in each data frame and in particular in the first bit position;

(iii) detecting a pre-determined alignment pattern in each of said plurality of low bandwidth data streams, said pre-determined alignment pattern being made up of consecutive alignment signals in data frames of each of said plurality of low bandwidth datastreams;

(iv) measuring time delay differences among said detected pre-determined alignment patterns at each of said low bandwidth channels;

(v) adding time delay to each low bandwidth channel corresponding to the measured time delay difference for the associated low bandwidth channel; and

(b) combining the plurality of time delay equalized datastreams into a single high bandwidth datastream.

2. The method of claim 1 wherein the alignment pattern is repeatedly and concurrently inserted into each of said low bandwidth datastreams.

3. The method of claim 2 wherein the alignment pattern has a length of at least twice a maximum anticipated transmission time delay difference across said plurality of low bandwidth channels.

4. The method of claim 3 further comprising the step of:

determining if all data streams have obtained frame alignment by detection of the alignment pattern from the network data stream in frame and superframe patterns.

5. The method of claim 4 further comprising the step of:

searching for a frame synchronization bit after all data streams have been aligned.

6. The method of claim 5 wherein each of said low bandwidth telecommunication channel comprises a data communication channel and wherein said step of inserting an alignment signal comprises the further step of concurrently inserting a channel frame synchronization pattern in each of said channels.

7. The method of claim 6 wherein each of said low bandwidth telecommunication channel comprises a data communication channel and the further step of counting and holding the delay value in each of said channels.

8. A system for disassembling a relatively high bandwidth datastream into a plurality of relatively low bandwidth datastreams, each data stream having a plurality of data frames, and recombining the plurality of low bandwidth data streams into the high bandwidth data stream for rate serving purposes on a communication network, comprising:

means for inserting an alignment signal into each corresponding data frame of each of said low bandwidth datastreams, said alignment signal being a pseudo-random noise bit, said bit being in the same bit position in each data frame and in particular in the first bit position, the consecutive alignment signals in data frames of each of said low bandwidth data streams constituting a predetermined alignment pattern;

means for transmitting a respective one of said low bandwidth datastreams, including the concurrently inserted alignment signal on a respective one of said low bandwidth channels;

means for equalizing transmission time delay among said plurality of low bandwidth datastreams by equalizing time delay among the associated plurality of low bandwidth telecommunications channels;

means for combining the plurality of time delay equalized datastreams into the single high bandwidth datastream;

means for extracting the alignment signal concurrently inserted in each corresponding data frame of each of said low bandwidth datastreams;

means for detecting a predetermined alignment pattern in each of said plurality of low bandwidth datastreams, said predetermined alignment pattern being made up of consecutive alignment signals in data frames of each of said plurality of low bandwidth datastreams;

means for measuring time delay differences among said detected predetermined alignment patterns at each of said low bandwidth channels; and

means for adding time delay to each low bandwidth channel corresponding to the measured time delay difference for the associated low bandwidth channel.

9. The system of claim 8 wherein the alignment pattern has a length of at least twice a maximum anticipated transmission time delay difference across said plurality of low bandwidth channels.

10. The system of claim 9 further comprising means for clocking a delay buffer on each low bandwidth channel until all buffers contain the pseudo-random noise bit at their respective outputs.

11. The system of claim 10 further comprising means for compensating for the different delays in the low bandwidth channels.