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Frizz
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Channel reuse on the same site

Wed Mar 07, 2007 1:59 am

We need to able to reuse the same channel on a single site to support much more subscribers thus improving economics.

I see in this forum many users need this feature but are proposing a solution to channel reuse that many other vendors in the industry (ex Motorola canopy or skypilot) have taken: synchronize the radios with GPS so that they do not interfere with each other.

Transmit GPS synchronization is difficult on a polled protocol like Nstreme while it is trivial on time slotted protocols like canopy use.


However, we have a very simple solution to channel reuse that should be very easy and fast to implement on Nstreme if the atheros driver allows it:

--being able to choose 2 different channels for transmitting and receiving on the same single radio card

for example, on the AP
tx on channel 1 while rx on channel 2
on the subcribers CPEs
tx on channel 2 while rx on channel 1

Using sectorial antennas with good F/B ratio would allow to reuse the same channel many times over the same site, (depending on antennas radio pattern even 3-4 times) since transmitting APs will not interfere with receiving APs on the same site.

Of course I'm talking about PmP Nstreme with a single radio card, since Nstreme2 PtP already has this feature even though using 2 different radio cards.


Furthermore, using different channels for transmitting and receiving is also handy to get around interference on crowded rf environments.


Hope I made myself clear. Any thoughts?

Normis, any comments on feasibility?
 
cmit
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Wed Mar 07, 2007 1:14 pm

I really doubt this would work.
As a standard wireless interface only has ONE RF unit in it, it can only on one frequency at the same time.
So while it should be possible to switch frequencies and do what you propose: While the wireless interface is in "TX mode" on frequency A, it won't receive any data that might come in on frequency B from a CPE.

This could probably be fought by doing some form of time synchronisation, but then you're effectively back to the first solution you quoted.

So in short: I don't think this is technically sensible.

(Open for being proven wrong ;) )

Best regards,
Christian Meis
 
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Hammy
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Thu Mar 29, 2007 7:35 pm

I don't know much about how polling operates, but couldn't the AP instruct the CPE when to send and when to listen?
 
babyface
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Tue Apr 03, 2007 12:31 pm

To reuse the same channel you can try canging the polarization
 
sten
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Tue Apr 03, 2007 5:14 pm

Have you guys considered that synchronizing channel usage would also reduce throughput. But using different polarity would definitely open a window opportunity.
Move along. Nothing to see here.
 
sten
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Tue Apr 03, 2007 5:15 pm

Have you guys considered that synchronizing channel usage would also reduce throughput. But using different polarity would definitely open a window opportunity.
Move along. Nothing to see here.
 
sten
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Tue Apr 03, 2007 6:34 pm

Have you guys considered that synchronizing channel usage would also reduce throughput. But using different polarity would definitely open a window opportunity.
Move along. Nothing to see here.
 
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Hammy
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Tue Apr 03, 2007 10:35 pm

Have you guys considered that synchronizing channel usage would also reduce throughput. But using different polarity would definitely open a window opportunity.
How would it reduce throughput?

Polarity usage is greatly dependant on what's already in the air.
 
sten
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Tue Apr 03, 2007 10:55 pm

Have you guys considered that synchronizing channel usage would also reduce throughput. But using different polarity would definitely open a window opportunity.
How would it reduce throughput?
By "it" you mean changing polarity or trying to synchronize transmission?
Polarity usage is greatly dependant on what's already in the air.
Yes, for instance, if something uses the same frequency and the same polarity then it would not be such a great idea.
Move along. Nothing to see here.
 
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janisk
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Wed Apr 04, 2007 7:46 am

if it is same area, same polarity same channel - i doubt that anything will help you but changing polarity, channel

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