[SI-LIST] Tolerating bit errors in 10GBASE-KR DME training frames

From: "Bond, David" <David.Bond@xxxxxxx>
To: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
Date: Fri, 7 Sep 2012 13:54:45 +0000

Hi Experts,
802.3 10GBASE-KR specifies a DME encoding for communicating emphasis commands 
and transmitter status across the channel while the equalization process is 
being performed.   I assume that the use of DME encoding which drops the bit 
rate by a factor of 8 is used so that the communication is tolerant of bit 
errors because it is really looking for edges.  My question is, in a typical 
application, how tolerant is the receiver of shifts in those edges?  0 UI, +/-1 
UI or more?
It seems to me that tolerating shifts of +/-1 is prudent, but +/-2 may lead to 
problems because of the non-DME encoded training pattern.  Any comments?

For example, 0b1100 would be encoded as (with "_" between DME cells)
_11110000_11110000_11111111_00000000_
Should a receiver decode patterns like this as the same 0b1100
11111001111110011111111110000000, or
11100000011000000111111011111111, etc.

Or essentially
_x11xx00x_x11xx00x_x111111x_x000000x_  where the "x" are don't care values.


David C. Bond
Director, Technical Staff
IDT Canada Inc.

Address: 603 March Road, Ottawa, ON K2K 2M5 Canada
Phone:     613.592.0859 x1711


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[SI-LIST] Tolerating bit errors in 10GBASE-KR DME training frames

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