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

Thanks for the inputs.

If all Fixed WiMax flavors are limited to 7MHz channels then redline is correct and 3.6GHz is worthless for WiMAX.  Even though mobile wimax supports up to 20MHz channels, the power limits that the FCC set here for mobile devices at 3.6GHz are much lower than for fixed - 2Watt EIRP max in fact, down from 25W.

We were hoping to upgrade our muni WiFi networks to WiMAX, but that appears impossible now.   The FCC claims that 3.6GHz will bring WiMAX to middle america - what a sham.    WiMAX will only be about the big carriers and billion dollar spectrum.   What has Kevin Martin done for small ISPs or groups like PTP - Absolutely nothing in my opinion.   Reading the FCC notes on 3.6GHz, the only one that thought the power limits were adequate was Sprint.  Imagine that.   

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 
  ----- Original Message ----- 
  From: Irving Popovetsky 
  To: Tyler van Houwelingen 
  Cc: PTP General list 
  Sent: Wednesday, December 26, 2007 7:34 PM
  Subject: Re: [ptp-general] 3.6GHz WiMAX - Does this make any sense??


  Hi Tyler, 

  According to Redline's data sheet,  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. 
  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".   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
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