US 5,461,622 AGranted

Method and apparatus for using SONET overheat to align multiple inverse multiplexed data streams

AssigneeBell Communications Research, Inc.

InventorsWerner H. Bleickardt, John O. Eaves, Joseph C. Lau

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Abstract

A super-rate signal is split (213) by an inverse multiplexer (200) into plural SONET STS-1 signals for transmission over separate facilities. At the receiver (500) the plural received signals are likely to have misaligned frames and payloads within the frames. In order to realign the plural signals so that they can be properly recombined to reform the original super-rate signals, the SONET A1 and A2 framing bytes together with the H1 and H2 pointer bytes are extracted (506) and used to determine (507) from where in plural buffers (508) stored frames of each received signal should be read out so that the read out signals are properly aligned. If misalignment of greater than one frame is to be corrected, plural frames of each received signal are stored and the SONET J1 byte is used in conjunction with the framing and pointer bytes to properly align the signals.

Claims18

Dependent claims

In a system which splits a super-rate signal into plural lower-rate SONET signals and separately transmits those plural SONET signals to a receiver which combines the separately received SONET signals to reform the super-rate signal, each SONET signal being in a frame format having a fixed number of bytes per frame and each frame having a fixed number of transport overhead (TOH) bytes and a Synchronous Payload Envelope (SPE) which contains a fixed number of path overhead (POH) bytes and a fixed number of payload bytes, the beginning of the SPE of the frame being slidably locatable at a plurality of byte locations, the TOH bytes including framing bytes (A1 and A2) which define the beginning of each frame and pointer bytes (H1 and H2) which point to the location of the beginning of the SPE in the frame, the beginning of the SPE of the frame being locatable at a plurality of byte locations relative to the H1 and H2 pointer bytes, the first byte in the SPE being a multiframe reference byte (J1) in the POH which repeats a predetermined pattern every fixed number of frames, a method for combining the plural received SONET signals to reform said super-rate signal comprising the steps of:

extracting the A1 and A2 framing bytes and the H1 and H2 pointer bytes in each of the plural received SONET signals;
determining the beginning of each frame from the extracted A1 and A2 framing bytes and the beginning of the SPE in each frame from the extracted H1 and H2 pointer bytes in each of the plural received SONET signals;
separately storing a fixed number of bytes of the payload from each of the plural received SONET signals;
using the extracted A1 and A2 framing bytes and H1 and H2 pointer bytes from each received SONET signal to determine byte storage locations from where the stored payloads of each of the plural received SONET signals are read-out so that the read out payloads of all of the plural received SONET signals are aligned in time;
and
reading out the stored payloads of each of the plural received SONET signals from the determined byte storage locations;
combining the aligned read-out payloads of each of the plural received SONET signals to reform the super-rate signal.

4 more elements

In a system which splits a super-rate signal into plural lower-rate SONET signals and separately transmits those plural SONET signals to a receiver which combines the separately received SONET signals to reform the super-rate signal, each SONET signal being in a frame format having a fixed number of bytes per frame and each frame having a fixed number of transport overhead (TOH) bytes and a Synchronous Payload Envelope (SPE) which contains a fixed number of path overhead (POH) bytes and a fixed number of payload bytes, the beginning of the SPE of the frame being slidably locatable at a plurality of byte locations, the TOH bytes including framing bytes (A1 and A2) which define the beginning of each frame and pointer bytes (H1 and H2) which point to the location of the beginning of the SPE in the frame, the beginning of the SPE of the frame being locatable at a plurality of byte locations relative to the H1 and H2 pointer bytes, the first byte in the SPE being a multiframe reference byte (J1) in the POH which repeats a predetermined pattern every fixed number of frames, the receiver for combining the plural received SONET signals to reform said super-rate signal comprising:

plural receiving means each for receiving an associated one of the separately transmitted SONET signals;
plural extracting means each for extracting the A1 and A2 framing bytes and the H1 and H2 pointer bytes in an associated one of the plural received SONET signals;
plural determining means each for determining the beginning of each frame from the extracted A1 and A2 framing bytes and the beginning of the SPE in each frame from the extracted H1 and H2 pointer bytes in an associated one of the plural received SONET signals;
plural storage means each for separately storing in byte storage locations a fixed number of bytes of the payload from an associated one of the plural received SONET signals;
control means responsive to the determined beginning of each frame and the beginning of each SPE in each of the plural received SONET signals for determining from which byte storage locations in each of the plural storage means the stored payloads of each of the plural received SONET signals are read-out, said control means causing each of the plural storage means to be read out from the determined byte storage locations so that the read out payloads of each of the plural received SONET signals are aligned in time;
and
means for combining the aligned read-out payloads of each of the plural received SONET signal to reform the super-rate signal.

4 more elements

Dependencies are inferred from the claim text.