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<br>
Here is an extract of a September Techjournal article I wrote in regards
to EIRP limits for OFDM devices. I hope it helps<br><br>
<font face="Times New Roman, Times" size=3><b>Changes to Australian
Standards<br>
</b>The ACA has just recently gazetted amendments to the
Radio-communications (Low Interference Potential Devices) Class Licence
2000. These changes have incorporated OFDM (Orthogonal Frequency Division
Multiplexing) IEEE 802.11 ‘a’ and ‘g’ devices within its scope.
<br><br>
Interestingly, these legislative changes were made to the 'LIPD Class
Licence' <i>(Radiocommunications (Low Interference Potential Devices)
Class Licence 2000)</i> and not the 'Spread Spectrum Class Licence'
<i>(Radio-communications (Spread Spectrum Devices) Class Licence
2002)</i>. This is despite the fact that 802.11 'a' and 'g' devices
both use spread spectrum techniques. The changes to the LIPD
Licence now allow greatly increased power output, IF the transmitter is
using OFDM.<br><br>
<b>Table of Amendments to the LIPD Class Licence:<br><br>
</font><div align="center"><font size=1>Item<x-tab> </x-tab>Class
Of Transmitter<x-tab> </x-tab>Operating Freq.Band
(Mhz)<x-tab> </x-tab>Max.
EIRP<x-tab> </x-tab>Limits (see
notes below)<br>
</b>45<x-tab> </x-tab>Digital
Modulation<x-tab> </x-tab>915-928<x-tab> </x-tab>1W<x-tab> </x-tab>1,
2<br>
45A<x-tab> </x-tab>Digital
Modulation<x-tab> </x-tab>2400-2483.5<x-tab> </x-tab>4W<x-tab> </x-tab>1,
2<br>
45B<x-tab> </x-tab>Digital
Modulation<x-tab> </x-tab>5725-5850<x-tab> </x-tab>4W<x-tab> </x-tab>1,
2<br>
</font></div>
<font face="Times New Roman, Times" size=2>Limits:<br>
</font>1)<font face="Times New Roman, Times" size=2>The radiated peak
power spectral density in any 3kHz is limited to 25mW per 3Khz, and<br>
</font>2)<font face="Times New Roman, Times" size=2>The minimum 6dB
bandwidth must be at least 500kHz.<br><br>
</font><font face="Times New Roman, Times" size=3>Last year the Federal
Communications Commission (FCC) of the USA made changes to FCC Rule
15.247 to allow a device that uses digital modulation to be considered a
spread spectrum device under a <u>new</u> category. This change was made
to incorporate the (then) soon to be ratified IEEE 802.11g industry
standard, where devices would use OFDM transmission in the 2400-2483.5MHz
band.<br><br>
There are possibly two reasons why the ACA modified the LIPD licence in
this way.<br><br>
The Australian Spread Spectrum Class Licence typically recognises devices
complying with the FCC Ruling. The ACA deemed that since these new
digital modulation transmitters don’t fit in the definition of spread
spectrum, and changes would <u>not</u> be made to the Spread Spectrum
Class Licence. The ACA had already made amendments to the LIPD Class
Licence in 2000 to allow the use of RLAN (Radio Local Area Network)
transmitters in the 5GHz bands. In August 2003 the LIPD Class
Licence was amended to accommodate digital modulation transmitters
(including OFDM transmitters) operating in the 915-928MHz, 2400-2483.5MHz
and 5725-5850MHz bands.<br><br>
<b>What does this all mean?<br>
</b>Up until these changes, transmissions in the 5.8GHz spectrum in
Australia were limited to only 1W. Now they can transmit at 4W.
This is great news for businesses who want the higher broadband speeds of
5.8GHz, and need that extra distance. <br><br>
</font>Regards,<br><br>
At 12:58 AM 20/02/2004 +1030, you wrote:<br><br>
<blockquote type=cite class=cite cite>Hi,<br><br>
On Thu, 19 Feb 2004, Jamie Moir wrote:<br>
><br>
> <br>
> IIRC they are/were addressing OFDM ATM, Proxim were pretty keen
to<br>
> see both the Quickbridge 60, and MP.11a addressed.<br><br>
From memory, there was an additional determination recently which
covers<br>
both the 2.4 and 5.8 GHz ISM bands. Now there is a classification
for<br>
Digital Modulation Devices, which would cover OFDM, with a limit of
4<br>
Watts EIRP in both 2.4 GHz and 5.8 GHz.<br><br>
Regards<br><br>
Jamie<br><br>
--<br>
Jamie Lovick <-> IT
Consultant <-> +614 1479 1681<br>
Hobby :
Doof.org
-> jalovick@doof.org<br>
Director : Drastic Solutions Pty Ltd ->
jalovick@drasticsolutions.com.au<br><br>
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<font size=2>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
</font><font face="verdana" color="#000080"><b>Michael R McDermott BEng
(Comp. Eng.), MACS, IEEE<br>
</font><font face="verdana">Wireless Systems Engineer<br>
</b></font><font face="verdana" size=2 color="#0000FF"><u>michael@veritechcorp.com.au</u></font><font face="arial">
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