superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
 ·WaveCrazy.Net
| reply to davesims
Re: Migrating from FHSS to OFDM
said by davesims  :Is it conceivable that an OFDM network could coexist with a FHSS network? What would give the best chance of success from a design prospective? Dave Yes, I am living proof that it will work. I have towers right now that have both FHSS and OFDM/DSSS radios working together.
When I started in 2001, the only options for any kind of decent outdoor gear were Breezecom and Raylink, with Raylink being much cheaper. As time went on and things changed, more and more OEM's began selling better outdoor gear for DSSS and then later on OFDM stuff.
At this point, I am phasing out all of my FHSS deployments and replacing them with newer faster 802.11b/g gear. It is cheaper, has better throughput and IMHO, has about as much interference resistance as the older FHSS stuff in most cases. 
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davesims
join:2004-10-09
Roseburg, OR
| superdog, thanks for the input. Did you experiment with physical spacing of the antennas old vs new? If so how far apart did you end up needing to separate them?
Also, did your FHSS network have both backhaul and ptmp using FHSS? If so have you upgraded both to OFDM?
Dave |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
·WaveCrazy.Net
| said by davesims :superdog, thanks for the input. Did you experiment with physical spacing of the antennas old vs new? If so how far apart did you end up needing to separate them? I didn't have enough space to change the distance, although the antennas were already at least 5ft apart and that seemed to work just fine. Keep in mind that I only EVER ran 3 sectors on each PoP at once and I would just replace one sector at a time with the AP and then run around and change out all of the CPE's in the following day or two.
I think you will get some very poor results if you try and deploy another 3 120 degree sectors using 802.11b/g and still try and use and/or keep the FHSS units in place. It may work out better if you try and get at LEAST 20ft between each group of antennas AND you use opposite polarity on each group.
said by davesims :Also, did your FHSS network have both backhaul and ptmp using FHSS? If so have you upgraded both to OFDM? Dave My backhauls have always been 802.11A except for one time I used an 802.11b backhaul while using FHSS AP's.
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davesims
join:2004-10-09
Roseburg, OR
| I can't imagine replacing one sector at time and then running around quickly and changing CPE's. How many clients were on a sector? I would think the clients would not be too happy with being down for a day or two.
This has been my delema. I am afraid that I will have to put the new gear to close to the old FHSS gear because of space constraints on the towers.
One thought I have is that it will "work" but the performance of the new gear will be poor while I am converting. In other words if I change a sector at a time and use opposite polarity that possibly the links to the customers will be maintained with poor performance. This because the FHSS hops through the frequencies.
It may also be possible that I could use a small spread, say 5mhz, that doesn't compete with the FHSS.
Dave |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
·WaveCrazy.Net
edit:
May 8th, @05:56PM
| said by davesims :I can't imagine replacing one sector at time and then running around quickly and changing CPE's. How many clients were on a sector? We had 3 guys doing this at once, and we got it done in 2 days. All of the Raylink CPE's already had CAT5 runs to the radio, so it was just a matter of doing some preconfig on the new radios and then reinstalling an end on the CAT5 at each location. On most swaps, I was in and out in less than 30 minutes.
Oh Yea, about 20 subs per AP.
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