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Comtech carrier in carrier CnC ?

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Ex Member

Mar 26th, 2008 at 4:35pm  

I want  use Comtech  for GSM backhall, but I want reduce my opex, so I was thinking of using carrier in carrier from Comtech.  

Does anyone have idea or exprience in this technology?  
Is this technogy is adaptable for GSM  backhaulling ?

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« Last Edit: May 9th, 2008 at 6:17pm by Admin1 »  
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Eric Johnston
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Reply #1 - Mar 26th, 2008 at 10:15pm  
The carrier in carrier idea works if:

Both carriers are in a directly looped back transponder, i.e. both earth station sites are in the same beam.  Each site must be able to see its own transmit carrier, as well as the received carrier from the other site.

It works best with two carriers of the same size. i.e. similar bandwidth in each direction.

It helps if you have larger dishes than normal.
Read more here:

Consider also using much larger dishes and using 16QAM 7/8 turbo.  It halves the opex compared with QPSK 7/8 turbo, provided you make it so you don't need more satellite power - so use a big dish at each end, also nice linear BUCs/HPAs, rated generously, at least 3 dB above the operating power, assuming single carrier, and smooth DC power supplies.
Best regards, Eric.
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« Last Edit: Feb 24th, 2015 at 10:44am by Admin1 »  
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Ex Member

Reply #2 - May 9th, 2008 at 1:53pm  
Comtech CnC is a tested technology for GSM Ater/Abis backhauling. We have deployed a large network of E1s covering whole transponders at Ku band but with 3.8 meter antennas (7.1m shared hub) and high capacity RFTs (as Eric has suggested).

The tests yielded excellent voice quality.  

CnC has 2-3 dBs of more power requirements than normal using the same SR (mod /fec).

Using Memotec Abis/Ater optimization from Memotec (a subsidiary of comtech) will further reduce opex.

All this adds up to the capex so you should carefully evaluate your  Return on Investment (ROI)
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« Last Edit: May 9th, 2008 at 6:17pm by Admin1 »  
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Ex Member

Reply #3 - Mar 25th, 2009 at 2:03am  

i have tried to build an GSM backhaull using comtech625 with CNC feature and 3,8 meter dish. i think it took too long for CNC to getting up, about 30 to 60 minute. and while the CNC up, the GSM station is still down. i'm already tired to try, may be any one could give me any idea, may be something wrong with my CDM configuration.

regards, gan.
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Ex Member

Reply #4 - Feb 3rd, 2012 at 7:36pm  
Instead of using CnC, you could use different network design with the same bandwidth savings
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Maxim Usatov
Ex Member

Reply #5 - Feb 8th, 2012 at 11:09am  
Gan, shoot me an e-mail with your current modem configs and we can take a look on what's wrong.
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