Re: 3.6GHz WiMAX - Does this make any sense??

Hi Tyler,

According to Redline's data sheet
<http://www.redlinecommunications.com/news/resourcecenter/productinfo/Redmax_an100u.pdf>, 
their WiMAX products are based on 802.16-2004 (fixed OFDM-PHY, the older
standard), which does in fact  only support 3.5 and 7Mhz channels.  The
newer mobile WiMAX protocol (802.16e-2005 OFDMA-PHY) supports a wider
variety of channel widths.  Further reading here.
<http://www.mobilehandsetdesignline.com/howto/201500260;jsessionid=VTSLBTHBTRKGSQSNDLQCKH0CJUNN2JVN?pgno=2>
The WiMAX proponents say that narrow channels are good because WiMAX has
higher "spectral efficiency" (meaning: it can push more bits) and
narrower channels provide better range and lower power consumption.

Also,  don't forget that 3650-3700 in the US is an FCC licensed "shared"
spectrum, meaning that you have the pleasure of filing with the FCC and
coordinating the bottom 25Mhz of the spectrum with every other current
and future licensee in your area of deployment, assuming you are not in
an exclusion zone (see the last PTP thread about this issue). 
Is that really worth it for fixed PtP links? If you're looking at
strictly at non-mobile PtP links, why not look at the Motorola PtP600? 
They can push some insane bandwidth over unlicensed frequencies, if you
can afford them.

Regarding max EIRP, that does sound a bit low to those of us in the WiFi
world who are used to pushing output limits to compensate for all the
noise, but maybe life is a little nicer in protected spectrum land. 
(Maybe they really can get 12 miles with such low output power, when
marketers dream :)  The 1W EIRP statement does jive with Redline's FCC
filing, see "Antenna vs. Gain"
<http://fjallfoss.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=549096&fcc_id=%27QC8-AN100UA%27>.  
Has anyone found FCC text to support this?

cheers,
-Irving

PS.   Rick Lindahl knows a bit more than me on this subject, he can
double check my answers if he has time.



Tyler van Houwelingen wrote:
> We were very excited about 3.6GHz until I got of the phone last week with Redline, trying to order their newly approved 3.6GHz 802.16 PtP product.
>
> The problem, according to them, is with the power limits of Wimax at 3.6GHz.  They said that, although the FCC set the max at 1W/1MHz, with a maximum of 25W for fixed products at 3.6GHz, the reality is that no products will ever ship that have more than 1Watt EIRP with antenna (28.4dB total to be exact) and mobile products will be much less.  The reason is that the maximum channel width for WiMAX is 7MHz and the 1W/MHz is MAXIMUM, and not typical.  Typical operating Tx power is much less then that.   So the total for their product Tx + Antenna is only 28.4dB - Less than 1W.
>
> This makes no sense to me, but they insisted.  I thought that WiMAX can have 20Mhz channels and Max Tx + Antenna power is the EIRP, just like the max EIRP for WiFi is 4Watts, 36dB.    Can anyone shed any light on this?  Is Redline just blowing smoke or do you think this a real problem for 3.6GHz.   
>
> Clearly 1W EIRP vs 20W EIRP dramatically changes any 3.6GHz WiMAX plans.
> tyler
>
> -------
>
> Tyler van Houwelingen
> Founder & CEO
> Azulstar, Inc. 
> 1051 Jackson, Grand Haven, MI 49417
> Main:  1-877-AZULSTAR
> Fax:  616-842-1104
> www.azulstar.com 
>   


-- 
-Irving Popovetsky                         Principal Consultant
ProStructure Consulting             http://www.prostructure.com
Network and Security Consulting      phone: (503) 288-1566 x201
            "Crafting Connectivity that Matters"

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