Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1997-06-23
2002-05-07
Marcelo, Melvin (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S514000
Reexamination Certificate
active
06385213
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a frame synchronous pattern processing apparatus and a frame synchronous pattern detection apparatus and a method for detecting frame synchronous pattern, and more particularly to the frame synchronous pattern processing apparatus and frame synchronous pattern detection apparatus and the method for detecting frame synchronous pattern which may be used advantageously for the synchronized digital signal transmission network including SDH (Synchronous Digital Hierarchy) or SONET (Synchronous Optical Network).
(2) Description of the Related Art
(A) Brief Description of SDH Transmission System
As it is well known, for the realization of B-ISDN, ITU-T is now standardizing SDH as an internationally however unified digital hierarchy (however, North America standardizes the above-mentioned SONET as its original hierarchy).
This SDH (or SONET) adopts a multiplexing method for multiplexing by adding an overhead containing information for maintenance and operation to a plurality of signals of lower group level and, therefore, the multiplexed frame comprises a format including a plenty of maintenance and operation information for respective speed as described in the item (B) below.
The overhead includes, normally, section overhead (SOH) for transmission line and path overhead (POH) for path, for multiplexing generally by adding POH to signal of lower group side (lower group level) and finally SOH is added.
(B) Description of SDH (SONET) transmission network
FIG. 40
is a block diagram showing an example of SDH (SONET) transmission network and, in this
FIG. 40
,
301
indicates subscriber terminal,
302
line terminal apparatus (NT),
303
and
306
transmission terminal station equipment (LT) respectively,
304
switch gear (SW),
305
multiplexer (MUX) and
307
relay transmission line.
In SDH (SONET) transmission network shown in this
FIG. 40
, lower group level data from a plurality of subscriber terminals
301
is byte multiplexed in the multiplexer
305
to be stacked into STM-N (STS-M) frame (wherein N and M represent multiplexing factor and N=1,4,16,64, . . . : M=3,12,48,192, . . . ), processed by overhead (SOH, POH) termination/replacement processing or AU/TU pointer termination/replacement processing in the transmission terminal station apparatus
306
before being transmitted through the relay transmission line
307
to the corresponding subscriber terminal
301
side.
By the way, STM-
1
(STS-
3
) frame constituting the basic multiplexed frame in the SDH (SONET) includes, as shown in
FIG. 41
, a format represented by two-dimensional byte array of 9 rows×270 bytes wherein the leading 9 rows×9 bytes are composed of a section overhead (SOH)
231
and AU (AU-
4
) pointer
232
and the following 9 rows×261 bytes are called payload (SPE: Synchronous Payload Envelope)
233
containing multiplexed information (VC: lower group level data).
Moreover, the section overhead
231
includes, as shown in
FIG. 42
, basically, a relay section overhead (RSOH: Regenerator-SOH)
231
A and a terminal station section overhead (MSOH: Multiplex-SOH)
231
B. The relay section overhead
231
A is used for signal maintenance/operation in the relay section [mutually between repeaters (existing on the relay transmission line
307
: not illustrated) and between the repeater and the transmission terminal station apparatus
306
] and composed of a frame synchronous pattern (A
1
, A
2
byte) and B
1
byte for coding error monitoring in the relay section and the like.
On the other hand, the terminal station section overhead
231
B is used for signal maintenance/operation in the terminal station section (between transmission terminal station apparatuses
306
), and composed of B
2
byte for coding error monitoring in the terminal station section and of K
1
, K
2
byte [APS (Automatic Protection Switch) byte] used for supplying/receiving signal for controlling a system switching between the transmission terminal station apparatuses
306
and used for a display of an in alarm state in respect of the trouble of the repeaters and the relay transmission line
307
.
AU
4
pointer
232
is used for indicating a containing position (frame leading position) of VC(VC
4
) in the payload
233
and composed of H
1
-H
3
bytes, and these H
1
-H
3
bytes are used for the pointer value updating or the phase adjustment in clock switching (positive staff
egative staff) or the like.
Here, in
FIG. 42
, two bytes marked by*and X following C
1
byte are respectively bytes not scrambled upon the transmission, each byte marked by X is respectively reserved for domestic use and each blank byte is reserved for future international standardization.
STM-
4
(STS-
12
) frame is built up by byte multiplexing 4 frames (in the multiplexer
305
) of STM-
1
(STS-
3
) comprising the above-mentioned format, then, STM-
16
(STS-
48
) is built up by byte multiplexing 4 frames of STM-
4
(STS-
12
) and similarly STM-N (STS-M) frame is built up sequentially by byte multiplexing lower group side frames by 4 frames.
In consequence, for instance, the section overhead
231
of an STM-
4
frame is composed of, as shown in
FIG. 43
, 9 rows×144 bytes wherein section overhead
231
shown in
FIG. 42
is byte multiplexed by four and the section overhead
231
of STM-
64
(STS-
192
) frame is composed of 9 rows×576 bytes.
Next,
FIG. 44
is a block diagram showing the composition example of the essential part of the transmission terminal station apparatus
306
. As shown in this
FIG. 44
, the transmission terminal station apparatus
306
comprises a current system
403
A and a standby system
403
B including respectively, for instance, a SOH termination processing section
404
, an AU pointer processing section
405
, a TU pointer processing section
406
, an elastic memory (ES) section
407
, a POH termination processing section (POH termination processor)
408
and a path switch alarm insertion section
409
.
410
indicates a microcomputer (&mgr;-COM) and
411
a cross connect apparatus (XC).
Here, the SOH termination processing section
404
executes an SOH termination processing such as a frame synchronization establishment, a coding error monitoring and so on based on the section overhead
231
of a received multiplexed frame (STM-N/STS-M), and the AU pointer processing section
405
extracts a TU signal by recognizing the frame leading position of TU level contained in the payload
233
based on the AU pointer
232
included in the AU
4
signal removed of RSOH231A and MSOH231B by the termination processing.
The TU pointer processing section
406
, extracts a signal of VC level contained in the TU signal (decomposition of the TU signal into a VC signal) based on the TU pointer included in the TU signal extracted in the AU pointer processing section
405
, the ES section
407
executes clock switching process of the VC signal and the POH termination processing section
408
performs, through the monitoring of the path overhead which is the overhead of the VC signal, a BIP (Bit Interleaved Parity) operation or a UNEQ (Unequipped: indicates that VC signal does not contain the payload
233
) alarm detection and other.
The path switch alarm insertion section
409
inserts a path switch alarm as a control information
25
for indicating the switching process of current system
403
A/standby system
403
B to the VC signal according to the setting by the microcomputer
410
.
Thus, in the transmission termination apparatus
306
, first, in the SOH termination processing section
404
, the frame synchronization is established by detecting the frame synchronous pattern through the detection of a given bit pattern of A
1
, A
2
byte contained in the section overhead
231
of the received multiplexed frame, the BIP operation in respect of B
1
byte or other various types of termination processing are performed to break down the received multiplexed frame into the AU
4
signal.
Next, the AU
4
signal is broken
Nakamura Yoshinori
Takatsu Kazuo
Fujitsu Limited
Marcelo Melvin
Nguyen Phuoychau Ba
Rosenman & Colin LLP
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