WiMax 'ruins satellite reception'

[Tee Emm]

From http://tinyurl.com/3yat7n:
--
Tariq Mustafa         MSN:t...@hotmail.com
Industry Blog: http://pakng.wordpress.com

WiMax 'ruins satellite reception'
Chris Forrester

A technical study has confirmed that WiMax signals can cause "severe interference" to satellite reception.

WiMax, the so-called 4G wireless system, has already suffered criticism from some countries for causing interference on satellite reception. Satellite operations in places including Australia, Bolivia, Fiji, Hong Kong, Indonesia, Pakistan and sub-Saharan Africa have already been negatively affected. The main problem occurs where telcos implement 3G or 4G Broadband Wireless Access (BWA) systems in or close to C-Band satellite transmissions (in the 3.4GHz-4.2GHz bands). At an emergency meeting in Washington earlier this year it was decided to conduct independent tests to conclude the precise scale of the problem.

A report submitted to the World Radiocommunications Conference in Geneva this week says that the tests have proved interference is probable. "To eliminate this harmful interference, operators of satellite earth stations and users of satellite communications services have united to communicate their positions and technical requirements to national and international telecommunications regulators. Regulators and radio frequency managers need to allocate spectrum in ways that recognize the reality of harmful interference and validate the right of incumbent operators to operate, and their customers to enjoy their services, without disruption by new users," says the report.

The report points out that the problem is in essence caused by satellite services and their weak signals being drowned out by the much more powerful terrestrial signals. "Terrestrial wireless applications are by definition ubiquitous and increasingly mobile/nomadic. Mobile and base stations for terrestrial wireless applications emit signals from many locations, in all directions, simultaneously that are powerful enough to saturate the sensitive C-band satellite receiving systems, causing a potential for total loss of service in the C-band. Recent operating experience in Australia, Fiji and Indonesia, and field trials in Hong Kong have confirmed this interference. As an example, in the Hong Kong experiments, television signals feeding 300,000,000 households throughout Asia were inadvertently knocked off the air." - (c) Rapid TV News 2007

[Shaheer Khan]

I wonder what's going to be the case here.

But it's C-Band. Most of the channels now transmit on KU-band,
probably due to the greater frequency range (I think...)

On Oct 26, 10:05 am, "Tee Emm" <tariq.must...@gmail.com> wrote:
> Fromhttp://tinyurl.com/3yat7n:

[Salman Ansari]

This is for Satellite communications (not just TV) which is both on the C-
an Ku- bands. The problem with the Ku-band is that there is limited capacity
and the footprints over Pakistan have a low EIRP as such are very prone to
rain fade as well as external noise like the one being stated about WiMAX.

Salman

[Rakesh Kumar]

@Salman: The typical radio engineer's dilemma. I want low enough frequencies and high enough power to get an optimum throughput for my application.

@Original Article: I fail to understand though that even if there is a lot of power and it is being radiated out of 'many locations', what about the WiMAX' radio plan then? Doesn't the standard have some standard radiation suppression for out-of-band frequencies? and where did all the guard bands go? Don't tell me please that the C band's frequencies used by Satellite channels are same as those used by WiMAX services?!

And coming back to the point: Does anyone in Pakistan observes this problem YET? Any reports whatsoever. The article mentions Hong Kong field trials and some Oceania's countries... Is our frequency allocation exactly the same as theirs?

--
Rakesh.
http://gopchandani.wordpress.com

[Shakeel Ahmad]

I yet have to see how it affects C-band link - i have a full duplex circuit to Hong Kong via Asia Sat and at a pretty central location in Lahore i.e. Aiwane-Iqbal complex. We haven't faced any problem at all from WiMAX towers - there are quite a few towers around us - and one on the same roof operating in 3.5 Ghz.

[Shaheer Khan]

I don't think it's got any issue. WiMax is another frequency,
satellite is another frequency. Wimax is radio waves in spectrum
(radio-waves, and most-likely have a larger wavelength so that they
can cover a greater distance), whereas satellites are direction-based,
have a greater intensity (hence smaller wavelength) and most likely,
higher amplitude.

On Oct 27, 11:14 pm, "Shakeel Ahmad" <shakeelah...@gmail.com> wrote:
> I yet have to see how it affects C-band link - i have a full duplex circuit
> to Hong Kong via Asia Sat and at a pretty central location in Lahore i.e.
> Aiwane-Iqbal complex. We haven't faced any problem at all from WiMAX towers
> - there are quite a few towers around us - and one on the same roof
> operating in 3.5 Ghz.
>

[Salman Ansari]

I made this out to help the non-satellite pros to appreciate the issue

 

Regards

 

Salman

 

---

Rakesh.
http://gopchandani.wordpress.com<br

[Rakesh Kumar]

But even if two standards operate on different frequencies there is a possibility they could interfere reasoned due to the inadequate suppression of higher harmonics or in some cases caused by the multi-path fades resulting in overlapped frequency products.

 

We don't know which particular equipment in Hong Kong those tests were conducted on... maybe the equipment fails to supress those harmonics and results in interference. I would feel fishy about it and make sure what the precise reason can be.
 

--
Rakesh.
http://gopchandani.wordpress.com

[Rakesh Kumar]

Shakeel,

You may want to check the attached files though. The PDF runs a news item containing some more details on the problems WiMax may pose and the .ppt is by SUIRG (Satellite Users Interference Research Group).

The issues is running hot and it is apparently bigger than interference here. It has become more of a spectrum fight like many others. The so-called 'C' band is being planned by national regulators to be 'given away' to broadband services like WiMAX and 802.11e. The google also presents some links of marketing plans detailing on co-existence of both and on how WiMAX is opportunity to Satellite services rather than just a threat.


Cool Stuff. :-)


Rakesh.

--
Rakesh.
http://gopchandani.wordpress.com

[ptcl_engr]

We had a similar problem in PTCL WLL. But it was interference from
Cable operators receivers/transmitters in our frequency range.When we
contacted PTA for this, they called a meeting of Cable operators and
PTCL,.In that meeting the Cable operators said that if their equipment
bothers PTCL, then it should buy them more expensive equipment at PTCL
cost.They are not going to replace their equipment.

On Oct 29, 10:37 pm, "Rakesh Kumar" <gopchand...@gmail.com> wrote:
> Shakeel,
>
> You may want to check the attached files though. The PDF runs a news item
> containing some more details on the problems WiMax may pose and the .ppt is
> by SUIRG (Satellite Users Interference Research Group).
>
> The issues is running hot and it is apparently bigger than interference
> here. It has become more of a spectrum fight like many others. The so-called
> 'C' band is being planned by national regulators to be 'given away' to
> broadband services like WiMAX and 802.11e. The google also presents some
> links of marketing plans detailing on co-existence of both and on how WiMAX
> is opportunity to Satellite services rather than just a threat.
>
> Cool Stuff. :-)
>
> Rakesh.
>

> On 10/27/07, Shakeel Ahmad <shakeelah...@gmail.com> wrote:
>
>
>
>
>
>
>
> > I yet have to see how it affects C-band link - i have a full duplex
> > circuit to Hong Kong via Asia Sat and at a pretty central location in Lahore
> > i.e. Aiwane-Iqbal complex. We haven't faced any problem at all from WiMAX
> > towers - there are quite a few towers around us - and one on the same roof
> > operating in 3.5 Ghz.
>

> Ames_NSMA2007.ppt
> 1030KDownload
>
> vol3.4.1.pdf
> 372KDownload- Hide quoted text -
>
> - Show quoted text -

[Basking Devil]

I was a member in that meeting from CAP Balochistan there are certain channels which still interfere in PTCLs frequency range and due to the poor budget Cable Operators have they decided not to do anything about it. Because you had to replace some 15 modulators and get higher frequency ones which were again a problem as most of the customer end equipment i.e. ( No hi Fi gadget Just a TV set) would not have supported the higher frequencies resulting in channel loss for the operator and customer.
 
Cheers!
 
Arzak  
> From: invisible....@gmail.com
> To: telecom-gr...@googlegroups.com

> Subject: Re: WiMax 'ruins satellite reception'

> Date: Tue, 30 Oct 2007 10:26:40 -0700

[kay]

I live in islamabad , Pakistan and facing the wimax problem.As i can't
receive even a single channel on my solid dish from last few
months .Before this i had mesh dish i changed it with solid but
problem was not resolved, then after august i lost all channels on C
band.Through some sources i come to know that PTCL(FAB) is aware of
this problem and its because of wimax (3.6----4.2 GHZ) alloted to
wimax and there r complaints in some areas of islamabad.Even our cable
operator had problem in receiving some channels.All news channels r
banned on cable and i having the system can't watch these channels.

[Masud]

What we've recently done at the Nayatel headend is to replace the LNBs
with newer LNBs that filter out the Wimax band.

Results have been amazing and the interference from Mobilink Alcatel-
Lucent test equipment doesn't affect our C-band recievers.

Masud
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> > knocked off the air." - (c) Rapid TV News 2007- Hide quoted text -