Charles,
Your point is well demonstrated, except....
6' Dish: +34 dBi
Not sure what dishes you are talking about, You can get 34 dbi out of
an Andrews 3 footer.
With 6 foot you should be able to get > 37 dbi.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
*From:* Charles Wu <mailto:[EMAIL PROTECTED]>
*To:* 'WISPA General List' <mailto:wireless@wispa.org>
*Sent:* Saturday, March 18, 2006 5:25 PM
*Subject:* RE: [WISPA] Licensed Backhaul options
The Spectra would be around $20k with external antennas. A
licensed product is going to be at least that, and probably $5k more.
Sit back and actually think for a second about this comparison,
and you'll realize that a similarly performing "unlicensed"
solution will cost MUCH MORE (and be much riskier) relative to the
licensed solution
The main difference is that the spectra requires 30 Mhz of
ABSOLUTELY CLEAN SPECTRUM in both the vertical and horizontal
polarities (150 Mb "Air Rate" transmits on V-pol & 150 Mb "Air
Rate" transmits on H-pol -- cut off 1 polarity, you halve throughput)
In addition, the Rx sensitivity of the Spectra at the 300 Mb data
rate (256 QAM) is -59 dB with an output power of +18 (so you'll
need HUGE dishes to guarantee the link budget)
So, lets do a "theoretical" path calc / comparison (15 miles)
11 Ghz Licensed Link (100 Mb Full Duplex)
Rx Sensitivity: -76 dBm
Tx Power: +21 dBm
4' Dish: +39 dBi
Expected RSSI: -42.9 (>30 dB of fade margin = ROCK SOLID LINK =)
5 GHz Spectra
Rx Sensitivity: -59 dB
Tx Power: +18
6' Dish: +34 dBi
Expected RSSI: -49.4 (~10 dB of fade margin w/ 2' more of each dish)
Then there's all sort of "real-world" performance issues that
occur with higher-order modulation schemes and license-exempt
operation
-Charles
-------------------------------------------
WiNOG Austin, TX
March 13-15, 2006
http://www.winog.com <http://www.winog.com/>
-----Original Message-----
*From:* [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] *On Behalf Of *Travis Johnson
*Sent:* Friday, March 17, 2006 10:03 PM
*To:* WISPA General List
*Subject:* Re: [WISPA] Licensed Backhaul options
Travis
Microserv
Charles Wu wrote:
You don't need licensed to high throughput backhaul. For example,
Orthogon's Spectra provides 300Mbps aggregate at a price point generally
Less than 45Mbps licensed.
Hi Matt,
I am curious to see where / what you got those numbers for the Orthogon
Spectra?
-Charles
-------------------------------------------
WiNOG Austin, TX
March 13-15, 2006
http://www.winog.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Matt Liotta
Sent: Thursday, March 16, 2006 1:28 PM
To: WISPA General List
Subject: Re: [WISPA] Licensed Backhaul options
-Matt
Bobby Burrow wrote:
I'm looking at moving to a licensed solution to increase throughput
across one of out backhaul links that spans 5 hops. Distances between
hops range anywhere from 7 to 19 miles.
We are currently using the dual nstreme Mikrotik solution and it is
working very well, however the WRAP/RB532 solutions are only yielding
~25Mb per hop.
Can anyone recommend a licensed radio manufacturer that should net us
50Mb-100Mb per hop?
Thanks,
Bobby Burrow
East Texas Rural Net
www.etxrn.com
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