System and method for inverse multiplexing using transcoding and frame alignment markers
View Patent ↗A system and method are provided for framing messages in a data streams encoded with redundant information for transmission and recovering the messages at a receiver. The transmission method accepts an energy waveform representing N words at a first bit rate, encoded with redundant information, where each word includes P number of bits. The N words are transformed, creating N transcoded words, where each transcoded word includes Q number of bits, and where Q<P. The N transcoded words are mapped into M lanes in a buffer memory, where M>1 and each lane receives a frame of N/M transcoded words. A frame alignment marker is generated and mapped into each frame. Each frame is represented as an energy waveform that is transmitted on a corresponding physical lane at the first bit rate divided by M.
1. In a communications transmitter, a method for disinterleaving and framing messages in a data stream encoded with redundant information, the method comprising:
accepting an energy waveform representing N words at a first bit rate, encoded with redundant information, each word including P number of bits;
transforming the N words, creating N transcoded words, where each transcoded word includes Q number of bits, and where Q<P;
mapping the N transcoded words into M lanes in a buffer memory, where M>1 and each lane receives a frame of N/M transcoded words;
generating a frame alignment marker for each frame;
mapping a frame alignment marker into each frame in the buffer memory; and,
transmitting energy waveforms representing each frame on a corresponding physical lane at the first bit rate divided by M.
2. The method of claim 1 wherein generating the frame alignment marker for each frame includes generating each frame alignment marker with (N/M)·(Q−P) bits.
3. The method of claim 2 wherein mapping the frame alignment marker into each frame includes mapping the frame alignment marker as an S·(Q−P)-bit word interposed between every Sth word in the frame.
4. The method of claim 1 wherein generating the frame alignment marker for each frame includes generating a frame alignment marker with a pattern selected from a group consisting a fixed-bit value, a sequence of predefined bit values, and a counting sequence.
5. The method of claim 4 wherein generating a frame alignment counting sequence includes generating a frame alignment counting sequence that increments in consecutive frames.
6. The method of claim 1 wherein accepting N words at the first bit rate includes accepting N 64 B/66 B encoded words, where P=66; and,
wherein transcoding the N words includes creating N transcoded words, where Q=65.
7. The method of claim 1 wherein mapping the N transcoded words into M lanes includes mapping the N transcoded words into 2 lanes (M=2), where each lane receives a frame of N/2 transcoded words; and,
wherein generating the frame alignment marker for each frame includes generating each frame alignment marker with N·(P−Q)/2 bits.
8. In a communications receiver, a method for re-interleaving messages from multiple physical lanes, the method comprising:
receiving energy waveforms representing M frames, via M corresponding physical lanes at a combined first bit rate, where M>1;
detecting a frame alignment marker in each frame, where each frame includes N/M words of Q bits each;
mapping the M frames into a single frame of N words in a buffer memory;
transforming the N words into N transcoded words of P bits, where Q<P; and,
supplying an energy waveform representing the N transcoded words with redundant encoded information at the first bit rate.
9. The method of claim 8 wherein detecting the frame alignment marker in each frame includes detecting a frame alignment marker with (N/M)·(Q−P) bits in each frame.
10. The method of claim 9 wherein detecting the frame alignment marker in each frame includes detecting the frame alignment marker as an S·(Q−P)-bit word interposed between every Sth word in the frame.
11. In a communications network, a system for framing messages in a data streams encoded with redundant information, the system comprising:
a reduction recoding module having an input to accept an energy waveform representing N words at a first bit rate encoded with redundant information, where each word includes P number of bits, the reduction recoding module transforming the N words and supplying N transcoded words at an output, where each transcoded word includes Q number of bits, where Q<P;
a framer having an input to accept the N transcoded words, the framer mapping the N transcoded words into M lanes, where M>1 and each lane receives a frame of N/M transcoded words, the framer generating a frame alignment marker for each frame and mapping a frame alignment marker into each frame; and,
a buffer memory having an input to accept the mapped frames and an output to supply M frames; and,
M physical lane interfaces, each physical lane interface having an input to accept a frame from the buffer memory, and output to supply an energy waveform representing the frame at the first bit rate divided by M.
12. The system of claim 11 wherein the framer generates each frame alignment marker with (N/M)·(Q−P) bits.
13. The system of claim 12 wherein the framer maps the frame alignment marker as an S·(Q−P)-bit word interposed between every Sth word in the frame.
14. The system of claim 11 wherein the framer generates a frame alignment marker with a pattern selected from a group-consisting a fixed-bit value, a sequence of predefined bit values, and a counting sequence.
15. The system of claim 14 wherein the framer generates a frame alignment counting sequence that increments in consecutive frames.
16. The system of claim 11 wherein the reduction recoding module accepts N 64B/66B encoded words, where P=66, and creates N transcoded words, where Q=65.
17. The system of claim 11 wherein the framer maps the N transcoded words into 2 lanes (M=2), where each lane receives a frame of N/2 transcoded words, and generates each frame alignment marker with N·(P−Q)/2 bits.
18. In a communications network, a system for re-interleaving messages from multiple physical lanes, the system comprising:
M physical lane interfaces, where M>1 and each physical lane interface has an input to accept an energy waveform representing a frame at a first data rate divided by M, and an output to supply the frame;
a deframer having an input to accept the M frames from the first buffer memory, where each frame includes N/M words of Q bits each word, the deframer detecting a frame alignment marker in each frame, and mapping the M frames into a single frame of N words, in a first buffer memory;
a buffer memory to buffer the mapped single frame; and,
a encoding module having an input to accept the single frame of N words from the buffer memory, the encoding module transforming the N words into N transcoded words encoded with redundant information, and supplying an energy waveform representing the N transcoded words at the first bit rate, where each transcoded word includes P number of bits, and Q<P.
19. The system of claim 18 wherein the deframer detects each frame alignment marker with (N/M)·(Q−P) bits.
20. The system of claim 19 wherein the deframer detects each frame alignment marker as an S·(Q−P)-bit word interposed between every Sth word in the frame.