Re: [STDS-802-3-EPOC] Burst Markers
The map approach is what is used in some wireless protocols as well. It can
be very effective when there are a wide range of frequencies (channels) in
use and the allocations of services across them changes over time.
The gate can be thought of as a two dimensional means (time and LLID), the
map is really a three dimensional gate, time, channel, LLID. In this way,
the map is performing the same function as a gate.
In other words, it's only adding one more parameter to the gate to make a
map.
-Victor
From: Ed (Edward) Boyd [mailto:ed.boyd@xxxxxxxxxxxx]
Sent: Monday, February 18, 2013 1:44 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-3-EPOC] Burst Markers
Hi Raanan
Thanks for the email. It is certainly possible to build and send MAPs as
done in other standards. This type of solution is far from the current
Ethernet/EPON standard. The PHY doesn't process the GATE frames in the
current standard and there isn't burst information signaled from the MAC to
the PHY. The GATEs are sent unicast with delay compensation in the start
time. It would challenging to have a PHY rewrite the frames and figure out
the boundaries of the GATEs so it could construct the MAP.
While laser ON/OFF doesn't exist in EPoC, other burst overheads do exist. I
would like EPoC to have the same or less burst overhead than EPON so I use
the laser on/off and sync time from EPON as a reference point for
comparison.
In short, The MAP is an option for a new standard but it really isn't for an
EPON over Coax. I think the marker will be simple and allow full
compatibility with the EPON standard and layering.
On the overhead, I think that it can be low based on discussions with our
PHY team. It could be just a few symbols in a small number of carriers. We
are working proposals on the details and are open to suggestions. I think
that the shortened last code word will be the largest burst overhead for
EPoC.
Hope that helps
Ed
Sent from my iPhone
On Feb 18, 2013, at 8:01 AM, "Raanan Ivry" <raanan.ivry@xxxxxxxxxxxx> wrote:
Hi Ed,
In your presentation you suggested the use of Burst Markers.
There is another option: All the information (a full map) about teh burst
timing and frequencies can be sent in a Gate message by the CLT.
There are differences between EPON and EPoC which may permit such attitude:
1. Symbol size (EPoC) >> bit size (EPON)
2. There is no such thing as laser on/off time in EPoC
3. CLT-CNU synchronization is not a problem
We need to understand:
1. Why we need those Burst Markers
2. What the penalty (overhead) we are going to pay is.
Raanan
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