Title: Message

Charles you make a good point, but I’m going to throw a “but” in here:

 

but the Orthogon / Canopy 300 radio’s will run also run at:

 

64 QAM .92 dual          -62 receive sensitivity              +18 output     (252.9 throughput)

64 QAM .75 dual          -68 receive sensitivity              +18 output    (206.7 throughput)

16 QAM .87 dual          -71 receive sensitivity              +20 output    (160.8 throughput)  

 

In an attenuated lab setup, running TCP (w/ Iperf), we see the following results with the Spectra @ the 300 Mbps data rate

 

1 Way TCP Max: 143 Mbps

2 Way BiDirectional TCP Max: 98.1 / 105 Mbps

 

Based on this data (and adding in timing degradation that a link would sustain when traveling over a longer distance), in order to acheive true "wire-speed" full-duplex 100 Mb Ethernet on the radio, I would guess that you would need to maintain the full-order modulation in order to keep the "apples-to-apples" comparison with a licensed 100 Mb radio link (e.g., Ceragon, Dragonwave, MNI).

 

Full list can be found in the release notes and if you do the math on those modulations you can get some very good performance.  I do agree with you that the licensed links would make more sense, but hanging 4 foot dishes on towers becomes a very expensive task or if you have to do a non-penetrating roof mount skid, the cost difference between the sleds is big.  So we have to take in more than the cost of the radio’s, licenses, leases and dishes but put together the total cost because if you are hanging BIG dishes you’re going to dig deeper into your pocket.

 

if he has clean spectrum to "spare" and doesn't need full 100 Mb wire speed performance, than the Spectra does make more economical sense -- but I would argue that you would need similarly (if not larger) sized dishes on the Spectra (4' & 6' dishes) due to 5 GHz spectrum congestion "risks" and the need/desire to minimize Rf beamwidths

 

-Charles

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dustin Jurman
Sent: Sunday, March 19, 2006 5:47 PM
To: 'WISPA General List'
Subject: RE: [WISPA] Licensed Backhaul options

 

Dustin Jurman

 

 


From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Charles Wu
Sent: Saturday, March 18, 2006 5:26 PM
To: 'WISPA General List'
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

-----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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