[SLS-OPT] O3K channel model

Tue Apr 28 15:33:02 UTC 2020

Dear All, 

Thanks a lot to Dirk and Géraldine for the very useful contribution.
In the past we used the "ampère model" (in slide 7 from Géraldine), and, 
as Géraldine correctly pointed out, it's just a matter of scaling to move 
from that to the "photons per bit model" (slide 8). So for ESA it's fine 
either way.

I think that the last details that we need to agree upon before running 
the new simulation campaign concern the fading and the interleaver 
dimensioning. In our opinion it is important to include them both in the 
assessment, since in past meetings it was shown that there is an 
intertwined relationship between the code, the channel, and the 
interleaver. 
For simplicity we propose to use fading A from the DLR, leaving the 
performance assessment with the other time series for the green book. On 
the interleaver dimensioning, since it depends both on the symbol rate and 
the fading, I think that we should pick 3 different (N,B) values. 
Honestly, I don't think we have the time (nor the need) for an accurate 
optimization of these parameters, so we might well live with a 
rule-of-thumb dimensioning.

Finally, concerning Géraldine's request for the mutual information, we 
still don't think that such investigation would be worth the required 
effort. This applies in particular to fading channels, where the 
computation of the mutual information is not as straightforward as on the 
AWGN channel, especially when the fading is not generated according to a 
given statistical model but numerically by means of a time series. Also, 
including the interleaver would further complicate the analysis. On top of 
this, we are not using Matlab for our simulations, and including the 
mutual information in our simulator would inevitably delay the delivery of 
the results of the new simulation campaign.

Kind regards,

Modis for ESA - European Space Agency 

Nicolò Mazzali, PhD 
Communication Systems & Technologies Engineer 

Telecommunications Section (TEC-ESC) 
Radio Frequency Systems Division (TEC-ES)
Directorate of Technology, Engineering & Quality (D/TEC)

ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
nicolo.mazzali at esa.int | www.esa.int
T +31 71 56 53215

From:   <Dirk.Giggenbach at dlr.de>
To:     <Jon.Hamkins at jpl.caltech.edu>
Cc:     SLS-OPT at mailman.ccsds.org
Date:   23/04/2020 20:04
Subject:        Re: [SLS-OPT] O3K channel model
Sent by:        "SLS-OPT" <sls-opt-bounces at mailman.ccsds.org>

Hi Jon,

we do not have data APD-RFEs for that low rate which we could 
test/measure.
I checked some datasheets, the one coming closest to 1.22Mbps is the 
LaserComponents IAG350H1D –APD Receiver with 1MHz Bandwidth and 350µm APD. 
 They don’t show dark current in the DS.

These values seem close to best compared to other receivers:
Responsivity=94MV/W  ,  I guess that includes Amplification of M=10, so 
TIA would be ~9MOhm 
NEP=32fW/sqrt(Hz)   -   referred noise density of 0.3E-12 A/sqrt(Hz)  or 
3µV/sqrt(Hz) 
https://www.lasercomponents.com/de-en/product/apd-receivers/ 

Hope that helps,

Dirk

Von: SLS-OPT [mailto:sls-opt-bounces at mailman.ccsds.org] Im Auftrag von Jon 
Hamkins via SLS-OPT
Gesendet: Mittwoch, 15. April 2020 17:20
An: SLS-OPT at mailman.ccsds.org
Betreff: [SLS-OPT] O3K channel model

Attached is the O3K channel model we discussed yesterday.  It also 
contains a suggestion for how to state the O3K coding performance.  I 
welcome your comments.  If we can agree to the model in the next week or 
so, each agency may be able to begin simulating with it and discuss some 
initial results at the May teleconferences.
A few notes:
I am suggesting we study 10 Gsps, 78.125 Msps, and 1.22 Mbps, since those 
include the highest and lowest data rates and one in the middle.
I don't have a good suggestion for the TIA noise density at 1.22 Msps. 
Dirk, would you be able to supply a number?
I have algebraically simplified the expressions for the means and 
variances.  You can compare the model to the expressions Dariush presented 
on yesterday (p. 5), and check my algebra.
I have included the fading parameter as well.  Just set rho=1 if you want 
no fading.
     ----Jon
-- 
Jon Hamkins
Lead Technologist
33   |   Communications, Tracking, and Radar Division
O 818-354-4764   |   M 626-658-6220 

JPL   |   jpl.nasa.gov 
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