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Re: [802.3_OMEGA] D1.0 comment #52

Hi Ruben,

I noticed a typo in your text below.  

Everywhere you have "65-bits blocks", it should be "65-bit blocks".

See this example from IEEE 802.3-2018:

1.2.5 Hexadecimal notation
Numerical values designated by the 0x prefix indicate a hexadecimal interpretation of the corresponding
number. For example: 0x0F represents an 8-bit hexadecimal value of the decimal number 15; 0x00000000
represents a 32-bit hexadecimal value of the decimal number 0; etc.


Natalie Wienckowski
General Motors

From: Rubén Pérez-Aranda <rubenpda@xxxxxxxxx>
Sent: Monday, March 29, 2021 7:00 AM
To: STDS-802-3-OMEGA@xxxxxxxxxxxxxxxxx <STDS-802-3-OMEGA@xxxxxxxxxxxxxxxxx>
Subject: [802.3_OMEGA] D1.0 comment #52

Dear Luisma, all,

I've been working on a proposal for the PCS introductory paragraph, per comment 52. I realize that Bob already made a proposal in his comment 184, and I used it as a baseline, modifying the adopted nomenclature approved per comment 59. By the way, in case that this comment resolution is accepted, comments 54, 189, 191, 192 and 195 are also resolved, because the commented text has been replaced.

The proposal is the following:

"The BASE-AU PCS manages interleaving of xMII data streams with physical layer control information. The fixed-length Transmit Block provides the structure for time division multiplexing these two streams of information. A frame from the xMII can be contained in one or more Transmit Blocks, and xMII frame boundaries have no correlation to Transmit Block boundaries.  
On the transmit path, the PCS repeatedly encodes 64-bits (8 octets) of the xMII data stream into 65-bits blocks using 64B/65B encoding (see The encoded xMII data stream is also referred to as the payload. 
The physical layer control is organized into a 224-bit long block called Physical Header Data (PHD) (See Table 166-2). The PHD is followed by the result of CRC16 calculation. The resulting 240-bit block is encoded using an interleaved Three Repetition Code (TRC) (See, which generates a 720-bit sequence called encoded PHD.
The encoded PHD is divided into a series of 20-bit long encoded PHD sub-blocks.  Each 20-bit encoded PHD sub-block is placed in the Transmit Block after 80 65-bits blocks of payload. Each sequence of 80 65-bits blocks followed by a 20-bit encoded PHD sub-block is processed by a systematic RS-FEC (544, 522) code over Galois Field 2^10, which appends a 220-bit parity, producing  5440-bit RS-FEC code-words. A Transmit Block holds 36 RS-FEC codewords.
A Transmit Block is scrambled with an additive scrambler before transmission. The scrambler uses an LFSR that is initialized to a pre-defined value at the beginning of each Transmit Block.

On the receive path, the BASE-AU PCS performs the additive de-scrambling, decodes received RS-FEC codewords, and separates the payload from the control information.  The received payload is 64B/65B decoded to create the xMII receive data stream.  A series of received 20-bit PHD sub-blocks are concatenated and TRC decoded to reconstruct the PHD followed by a CRC16 (see PHD information reliability is checked by CRC calculation and, if it is correct, then it is fed to state diagrams. PHD information exchange with the link partner provides bi-directional link monitoring, PHY control, capabilities announcement, and BASE-AU OAM message communication. (See Table 166-2)."

Kind Regards, 


Rubén Pérez-Aranda 

Knowledge Development for POF, S.L.
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