Tom,

802.16d implementations can and do support diversity antennas on the  
AUs.

I don't know the definitive answer to the rest of the question. But I  
do know that:

(1) Clients in 802.16e can and do support diversity

(2) The clients are supposed to be interoperable

(3) I know of no clients that support diversity in 802.16d

So, speculatively, the point might that 802.16e clients support  
diversity and interoperate.

You pick up at least a few db with client diversity antennas-though  
not nearly enough to make up for the lower power regime you have to  
operate in.

Chuck



On Sep 11, 2009, at 7:12 PM, Tom DeReggi wrote:

> Patrick,
>
> Always great to see your list posts filled with good info. Responses
> inline...
>
>> The E standard does enable use of diversity, but it comes at a high  
>> cost
>> and is of limited benefit for rural operators. The truth is that
>> diversity is designed to increase link budgets to support self- 
>> install.
>
> Can you clarify? Are you saying D Spec does not support Diversity?
> Or that most D vendors focusing on price chose not to include  
> implementation
> of it?
>
> Even most Wifi chipsets supports diversity.
>
> My understanding was D supported diversity, because the early Pre- 
> Wimax
> Aperto supported all types of Diversity.
> Please clarify.
>
> I'd like to add... I'd like to see more FIXED products support  
> Diversity at
> the AP.
> Trials have shown that Polarity diversity yielded much better  
> results than
> Spacial diversity for NLOS. BUT, that data does not consider spectrum
> availabilty and congestion.
> Many Metro deployments can't afford to waste a polarity, with limited
> spectrum and lots of noise, and forced to abandon the idea of Polarity
> diversity.
> Spacial Diversity at teh AP is an enhancement that can be used  
> without any
> trade-off other than Colo fees if can't avoid paying colo per antenna.
> Actually in newer MIMO designs Spacial Diversity on its own showed
> signficant improvements in range.
> This could becaome even more important in 3.65 with few channels.
>
>> Basically, each standard has its place, E is for people in 2.5 GHz  
>> doing
>> self-install, like Clearwire, and we all know the low service
>> (especially low upstream) packages offered in Clearwire's service.  
>> D is
>> better and cheaper for rural fixed operators, and especially for  
>> public
>> safety video type networks and definitely for voice-centric users.  
>> D is
>> better for enterprise, where many users sit behind the CPE. E is  
>> better
>> for roaming individual users with modest expectations.
>
> I'd agree. And I'd agree "D" is most appropriate for most WISPs.
>
> I think the biggest factor in deciding though isn't technology specs?
> People want to pick the technology with the longest life span.
> Many WISPs might prefer D, but are afraid D might be discontinued  
> sooner,
> since the big dollar might have followed E.
> Just like is happening right now.
> I think the number one factor that will lead WISPs to pick D is
> acknowledgement that Vendors understand and see the long term  
> potential and
> MArket for D, so we can be confident about our vendors.
> So far, I think the primary vendors have done a good job showing their
> supprot for D.
>
> The other number 1 barrier to WiMax is price, so once again many  
> have chosen
> D for price reasons.
> But that is a fake benefit, because technically there is no reason  
> that E
> product couldn't be sold just as Cheap if it came down to it.
> If anything, E has the potential to drop to lower prices, because of  
> economy
> of scale and diverse use for WiMax chipsets.
>
> So what I'm saying is... Wimax E is killing themselves by pricing  
> their
> products to high. Right now D has the potential to regain its market  
> share
> because its price advantage.
> However, one good way for E to protect its market share is to try and
> influence the discontinuation of D.
> Thus important to support the continued development of D.
>
> Tom DeReggi
> RapidDSL & Wireless, Inc
>
>> We'd like to hear your opinions, and if you like to discuss this  
>> with us
>> while at 4G World, please drop me a note.
>>
>> Regards,
>>
>> Patrick Leary
>> Aperto Networks
>>
>>
>> Patrick Leary
>> Aperto Networks
>> 813.426.4230 mobile
>>
>>
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--------------
Chuck Bartosch
Clarity Connect, Inc.
200 Pleasant Grove Road
Ithaca, NY 14850
(607) 257-8268

"When the stars threw down their spears,
and water'd heaven with their tears,
Did He smile, His work to see?
Did He who made the Lamb make thee?"

 From William Blake's Tiger!, Tiger!





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