# US 10,374,750 B2 · Apparatus and method for communicating data over an optical channel

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- Number: US 10,374,750 B2
- Document ID: US10374750B2
- Status: Granted
- Kind: B2
- Application number: 16/155,610
- Filed: 2018-10-09
- Published: 2019-02-07
- Granted: 2019-08-06
- Earliest claimed: 2015-12-21
- Assignees: Inphi Corporation
- Applicants: Inphi Corporation
- Inventors: Benjamin P. Smith; Arash Farhoodfar
- Web page: https://patentgrep.com/patent/US10374750B2

## CPC

- H04L 1/0044: {specially adapted for power saving}
- H03M 13/256: {with trellis coding, e.g. with convolutional codes and TCM}
- H03M 13/2906: {using block codes (H03M13/2957 takes precedence)}
- H04B 10/50: Transmitters
- H04B 10/516: Details of coding or modulation
- H04B 10/5161: {Combination of different modulation schemes}
- H04B 10/532: Polarisation modulation
- H04B 10/541: {Digital intensity or amplitude modulation}
- H04B 10/697: {Arrangements for reducing noise and distortion}
- H04L 1/004: {by using forward error control (H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00)}
- H04L 1/0041: {Arrangements at the transmitter end}
- H04L 1/0045: {Arrangements at the receiver end}
- H04L 1/0058: {Block-coded modulation}
- H04L 1/006: {Trellis-coded modulation}
- H04L 1/0065: {Serial concatenated codes}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- H04B: TRANSMISSION

## Abstract

An optical module processes first FEC (Forward Error Correction) encoded data produced by a first FEC encoder. The optical module has a second FEC encoder for further coding a subset of the first FEC encoded data to produce second FEC encoded data. The optical module also has an optical modulator for modulating, based on a combination of the second FEC encoded data and a remaining portion of the first FEC encoded data that is not further coded, an optical signal for transmission over an optical channel. The second FEC encoder is an encoder for an FEC code that has a bit-level trellis representation with a number of states in any section of the bit-level trellis representation being less than or equal to 64 states. In this manner, the second FEC encoder has relatively low complexity (e.g. relatively low transistor count) that can reduce power consumption for the optical module.

## Claims

### Claim 1

A transmitting apparatus comprising:
a host card configured to generate first FEC encoded data using a first forward error correction (FEC) encoder;
an optical module configured to encode a subset of the first FEC encoded data to produce second FEC encoded data using a second FEC encoder, the optical module further being configured to modulate, based on a combination of the second FEC encoded data and a remaining portion of the first FEC encoded data that is not further coded, an optical signal for transmission over an optical channel;
wherein the second FEC encoder is an encoder for an FEC code that has a bit-level trellis representation with a number of states.

### Claim 2 (depends on 1)

The transmitting apparatus of claim 1, wherein the number of states in any section of the bit-level trellis representation is 16 states.

### Claim 3 (depends on 1)

The transmitting apparatus of claim 1, wherein the second FEC encoder implements an extended Hamming code or a convolutional code.

### Claim 4 (depends on 1)

The transmitting apparatus of claim 1 further comprising:
a demultiplexer configured for splitting the first FEC encoded data into an LSB (Least Significant Bit) sequence and an MSB (Most Significant Bit) sequence;
wherein the LSB sequence is the subset of the first FEC encoded data that is further coded by the second FEC encoder to produce the second FEC encoded data.

### Claim 5 (depends on 4)

The transmitting apparatus of claim 4, further comprising:
a symbol mapper configured for combining, into symbols, the second FEC encoded data and the MSB sequence of the first FEC encoded data;
wherein the optical modulator modulates the optical signal based on the symbols.

### Claim 6 (depends on 5)

The transmitting apparatus of claim 5, wherein:
the second FEC encoded data is a stream of set-partitioning bits for symbols of a DP-DQPSK (Dual-Polarization Differential Quadrature-Phase-Shift-Keying) constellation.

### Claim 7 (depends on 5)

The transmitting apparatus of claim 5, wherein:
the second FEC encoded data is a stream of set-partitioning bits for symbols of a PAM-M (Pulse-Amplitude Modulation) constellation.

### Claim 8 (depends on 7)

The transmitting apparatus of claim 7, wherein the symbol mapper comprises:
a first symbol mapper for generating PAM-M symbols; and
a second symbol mapper for mapping pairs of the PAM-M symbols into QAM-M2 (Quadrature-Amplitude Modulation) symbols.

### Claim 9

A method generating and transmitting an optical signal, the method comprising:
coding first forward error correction (FEC) encoded data;
coding a subset of the first FEC encoded data using a second FEC encoder to produce second FEC encoded data; and
modulating, based on a combination of the second FEC encoded data and a remaining portion of the first FEC encoded data that is not further coded, the optical signal for transmission over an optical channel;
wherein the second FEC encoder is an encoder for an FEC code that has a bit-level trellis representation with a number of states.

### Claim 10 (depends on 9)

The method of claim 9, wherein the number of states in any section of the bit-level trellis representation is 16 states.

### Claim 11 (depends on 9)

The method of claim 9, wherein the second FEC encoder implements an extended Hamming code or a convolutional code.

### Claim 12 (depends on 9)

The method of claim 9, further comprising:
splitting the first FEC encoded data into an LSB (Least Significant Bit) sequence and an MSB (Most Significant Bit) sequence;
wherein the LSB sequence is the subset of the first FEC encoded data that is further coded by the second FEC encoder to produce the second FEC encoded data.

### Claim 13

A transmitting apparatus comprising:
a transport circuit comprising a first FEC (Forward Error Correction) for coding data to produce first FEC encoded data; and
an optical module comprising:
an interface for receiving the first FEC encoded data;
a second FEC encoder for further coding a subset of the first FEC encoded data to produce second FEC encoded data; and
an optical modulator for modulating, based on a combination of the second FEC encoded data and a remaining portion of the first FEC encoded data that is not further coded, an optical signal for transmission over an optical channel;
wherein the second FEC encoder is an encoder for an FEC code that has a bit-level trellis representation with a number of states.

### Claim 14 (depends on 13)

The transmitting apparatus of claim 13, wherein the number of states in any section of the bit-level trellis representation is 16 states.

### Claim 15 (depends on 13)

The transmitting apparatus of claim 13, wherein the first FEC encoder implements a G.975.1/G.709-compliant FEC code.

### Claim 16 (depends on 13)

The transmitting apparatus of claim 13, wherein the second FEC encoder implements an extended Hamming code or a convolutional code.

### Claim 17 (depends on 13)

The transmitting apparatus of claim 13, further comprising:
a demultiplexer configured for splitting the first FEC encoded data into an LSB (Least Significant Bit) sequence and an MSB (Most Significant Bit) sequence;
wherein the LSB sequence is the subset of the first FEC encoded data that is further coded by the second FEC encoder to produce the second FEC encoded data.

### Claim 18 (depends on 13)

The transmitting apparatus of claim 13 further comprising an error decorelator for processing the first FEC encoded data.

### Claim 19 (depends on 13)

The transmitting apparatus of claim 13 wherein the interface comprises an optical channel transport lane interface.

### Claim 20 (depends on 17)

The transmitting apparatus of claim 17 further comprising:
a symbol mapper configured for combining, into symbols, the second FEC encoded data and the MSB sequence of the first FEC encoded data;
wherein the optical modulator modulates the optical signal based on the symbols.