Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
2000-01-07
2003-07-01
Negash, Kinfe-Michael (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200
Reexamination Certificate
active
06587236
ABSTRACT:
RELATED APPLICATIONS
Not applicable
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
MICROFICHE APPENDIX
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is related to the field of fiber optic communication systems, and in particular, to fiber optic systems that provide errorless switching.
2. Description of the Prior Art
FIG. 1
depicts the current system of switching used in fiber optic networks. A first node
101
connects to a second node
102
via a first optical fiber
150
and a second optical fiber
160
. The second node
102
is comprised of a first optical-to-electrical converter
120
, a second optical-to-electrical converter
121
, a first fault detector
130
, a second fault detector
131
, and a switching system
140
. The first optical-to-electrical converter
120
connects to the first node
101
via the first optical fiber
150
. The first optical-to-electrical converter
120
connects to the first fault detector
130
via electrical data line
151
. The first fault detector
130
connects to the switching system
140
via electrical data line
153
and electrical control line
152
.
The second optical-to-electrical converter
121
connects to the first node
101
via the second optical fiber
160
. The second optical-to-electrical converter
121
connects to the second fault detector
131
via electrical data line
161
. The second fault detector
131
connects to the switching system
140
via electrical data line
163
and electrical control line
162
.
In operation, the first node
101
transmits a first data signal over the first optical fiber
150
. The first optical-to-electrical converter
120
receives the first data signal and converts it from an optical signal to an electrical signal. The first optical-to-electrical converter
120
transfers the first data signal to the first fault detector
130
via electrical data line
151
. The first fault detector
130
determines if an error has occurred in the transmission of the first data signal and generates a first error instruction if an error has occurred. The first fault detector
130
transfers the first data signal to the switching system
140
via electrical data line
153
. The first fault detector
130
transfers any first error instructions to the switching system
140
via electrical control line
152
.
The first node
101
transmits a second data signal over the second optical fiber
160
. The second optical-to-electrical converter
121
receives the second data signal and converts it from an optical signal to an electrical signal. The second optical-to-electrical converter
121
transfers the second data signal to the second fault detector
131
via electrical data line
161
. The second fault detector
131
determines if an error has occurred in the transmission of the second data signal and generates a second error instruction if an error has occurred. The second fault detector
131
transfers the second data signal to the switching system
140
via electrical data line
163
. The second fault detector
131
transfers any second error instructions to the switching system
140
via electrical control line
162
.
The switching system
140
receives the first data signal, the second data signal, and any first or second error instructions. The switching system
140
transfers either the first data signal or the second data signal. The signal that gets transferred depends on the first error instruction and the second error instruction. For example, if an error occurs on the first data signal, the first error instruction instructs the switching system
140
to transfer the second data signal and not the first data signal. If an error occurs on the second data signal, the second error instruction instructs the switching system
140
to transfer the first data signal and not the second data signal.
Two problems exist with the system in FIG.
1
. One problem is that duplicate data can be transferred in the switching process. For example, consider the situation where the second data signal lags behind the first data signal. The lag in the second data signal causes the signals to be mis-aligned at the switching system
140
. Assume for this example that the second data signal lags the first data signal by ten blocks of data. When the switching system
140
changes from transferring the first data signal to transferring the second data signal, those ten blocks of data have already been transferred on the first data signal. After the switching system
140
, the ten blocks of data will again be transferred on the second data signal. The amount of duplicated data depends on how far the second data signal lagged behind the first data signal.
Another problem is that data can be lost in the switching process. Consider the other situation where the first data signal lags behind the second data signal. The lag in the first data signal causes the data to be mis-aligned at the switching system
140
. Assume for this example that the first data signal lags the second data signal by ten blocks of data. When the switching system
140
changes from transferring the first data signal to transferring the second data signal, ten blocks of data will have been missed. The amount of data lost depends on how far the first data signal lags behind the second data signal.
Errorless switching exists in other communications networks such as microwave communication networks, but doesn't exist in fiber optic systems. Fiber optic communication networks traditionally utilize Synchronous Optical Network (SONET) rings to provide two transmission paths to switch between. These fiber optic communication networks do not provide for errorless switching. By today's standards, switching resulting in duplicate or lost data is not acceptable.
SUMMARY OF THE SOLUTION
The invention solves the above problem by aligning the first data signal with the second data signal in the optic node before switching occurs. Data is not lost or duplicated in the switching process.
The errorless switching system is comprised of a first fault detector, a second fault detector, a synchronization system, and a switching system. The synchronization system aligns the first data signal with the second data signal. The fault detectors detect errors in the data signals and instruct the switching system to transfer the first data signal or the second data signal to avoid transferring erroneous data. No data is lost or duplicated because the data signals are aligned at the switching system.
REFERENCES:
patent: 5051979 (1991-09-01), Chaudhuri et al.
patent: 5285441 (1994-02-01), Bansal et al.
patent: 5506956 (1996-04-01), Cohen
patent: 5577196 (1996-11-01), Peer
patent: 5745476 (1998-04-01), Chaudhuri
patent: 5809406 (1998-09-01), Taki et al.
“DCN 212,” p. 1, (Jul. 26, 1999). See website “http://www.oneplusonetech.com/DCN212.htm”.
Butler Robert
Jones Mark Loyd
Szeto William C.
Ball Harley R.
Funk Steven J.
Negash Kinfe-Michael
Robb Kevin D.
Sprint Communications Company L.P.
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