Robust low rate data channel in LPI mode for energy-efficient ethernet applications

Patent metadata

Field	Value
Publication number	US-9577787-B2
Application number	US-201514627539-A
Country	US
Kind code	B2
Filing date	Feb 20, 2015
Priority date	Jan 8, 2015
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A communication technique for energy efficient Ethernet (EEE) employs a systematic block forward error correcting code (FEC). The technique aligns a low power idle (LPI) refresh signal with the FEC frame. The refresh signal includes a known reference sequence, FEC systematic symbols, and FEC parity symbols. The technique may apply shortened FEC encoding and decoding on the partial data symbols and the parity symbols.

First claim

What is claimed is:

1. A system comprising:
a physical layer interface; and
media access control circuitry coupled to the physical layer interface, the media access control circuitry configured to:
determine when a low power mode of operation is active;
determine to send a hybrid refresh signal while the low power mode of operation is active; and
send the hybrid refresh signal through the physical layer interface by sending:
a known reference sequence;
systematic symbols representing data to be transmitted to a link partner; and
forward error correcting (FEC) parity symbols determined from the systematic symbols.

2. The system of claim 1 , where:
the low power mode is defined by a specific communication protocol;
the specific communication protocol defines a specific protocol refresh signal to send when the low power mode of operation is active; and
the hybrid refresh signal differs from the specific protocol refresh signal.

3. The system of claim 2 , where:
the known reference sequence of the hybrid refresh signal comprises a selected portion of a known reference sequence defined by the specific communication protocol.

4. The system of claim 3 , where the selected portion comprises an initial portion of the known reference sequence defined by the specific communication protocol.

5. The system of claim 1 , where the media access control circuitry is further configured to:
determine an FEC frame boundary for an FEC frame communicated when the low power mode is inactive; and
align the hybrid refresh signal with the FEC frame boundary.

6. The system of claim 5 , where the FEC frame comprises a FEC parity field;
and where the FEC parity symbols in the hybrid refresh signal are aligned with the FEC parity field.

7. The system of claim 6 , where the FEC parity field in the FEC frame and the FEC parity symbols in the hybrid refresh signal are aligned by ending at the FEC frame boundary.

8. The system of claim 1 , further comprising a shortened FEC encoder configured to:
pass through general purpose data unchanged to form the systematic symbols representing the data to be transmitted to the link partner; and
determined the forward error correcting (FEC) parity symbols.

9. A method comprising:
determining to transmit a hybrid refresh signal from a communication device to a link partner of the communication device; and
transmitting the hybrid refresh signal by:
transmitting a known reference sequence;
transmitting general purpose data for the link partner, following the known reference sequence; and
transmitting parity symbols for the general purpose data.

10. The method of claim 9 , where the general purpose data immediately follows the known reference sequence, and the parity symbols immediately follow the general purpose data.

11. The method of claim 10 , where:
the known reference sequence comprises a subsection of a known reference signal defined in a specific communication standard for predefined refresh signal.

12. The method of claim 11 , where the hybrid refresh signal is transmitted instead of the predefined refresh signal.

13. The method of claim 9 , where transmitting the hybrid refresh signal further comprises:
aligning the hybrid refresh signal to FEC parity symbol timing of an FEC frame.

14. The method of claim 13 , where aligning further comprises:
aligning completion of the parity symbols of the hybrid refresh signal to an FEC frame boundary of the FEC frame located where parity symbols for the FEC frame end.

15. The method of claim 9 , where determining comprises:
determining that a low power mode is active;
determining to transmit the hybrid refresh signal to facilitate synchronization with the link partner; and
transmitting IDLE characters when no general purpose data are present.

16. The method of claim 9 , further comprising:
determining that the general purpose data is available to send to the link partner; and
transmitting the hybrid refresh signal in order to transmit the general purpose data.

17. The method of claim 9 , where determining comprises:
determining that a low power mode is active.

18. A system comprising:
a physical layer interface operable to communicate with a link partner; and
transceiver circuitry coupled to the physical layer interface, the transceiver comprising:
transmitter circuitry operable to:
when low power mode is inactive, transmit an outgoing FEC frame comprising FEC frame data symbols and FEC frame parity symbols that end at an FEC frame boundary;
when low power mode is active, determine to transmit an outgoing hybrid refresh signal to the link partner for synchronization when no general purpose data is available to transmit to the link partner, and in response transmit:
a known reference sequence;
IDLE characters following the known reference sequence; and
forward error correcting (FEC) parity symbols for the IDLE characters, following the IDLE characters;

when low power mode is active, determine to transmit an outgoing hybrid refresh signal to the link partner when general purpose data is available to transmit to the link partner, and in response transmit:
a known reference sequence;
systematic symbols representing the general purpose data, following the known reference sequence; and
forward error correcting (FEC) parity symbols for the systematic symbols, following the systematic symbols;

receiver circuitry operable to:
when low power mode is inactive, receive an incoming FEC frame comprising data symbols and parity symbols that end at an FEC frame boundary;
when low power mode is active, receive an incoming hybrid refresh signal from the link partner, the incoming hybrid refresh signal comprising:
a known reference sequence;
systematic symbols following the known reference sequence; and
forward error correcting (FEC) parity symbols for the systematic symbols, following the systematic symbols.

19. The system of claim 18 , where the transmitter comprises:
a shortened FEC encoder configured to generate the systematic symbols and the FEC parity symbols for the outgoing hybrid refresh signals.

20. The system of claim 18 , where the transmitter is further configured to:
transmit the FEC parity symbols of the hybrid refresh signal aligned to the FEC frame boundary.

21. The system of claim 20 , where completion of the FEC parity symbols of the hybrid refresh signal aligns to the FEC frame boundary.

Assignees

• Broadcom Corp

Inventors

• Tu Chung Ming
• Graba James
• Wang Peiqing
• Chini Ahmad
• Chen Yencheng
• Shen Ba-Zhong
• Tazebay Mehmet Vakif

Classifications

• H04L12/12

  Arrangements for remote connection or disconnection of substations or of equipment thereof · CPC title

• H04L1/0045

  Arrangements at the receiver end · CPC title

• G06F11/10

  Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's · CPC title

• H04L1/0041 Primary

  Arrangements at the transmitter end · CPC title

• H04L1/0057

  Block codes (H04L1/0061, H04L1/0064 take precedence) · CPC title