[MLB-WIRELESS] Wireless connection -1200m apart

[Michael McDermott]

Here is an extract of a September Techjournal article I wrote in regards to 
EIRP limits for OFDM devices. I hope it helps

Changes to Australian Standards
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.

Interestingly, these legislative changes were made to the 'LIPD Class 
Licence' (Radiocommunications (Low Interference Potential Devices) Class 
Licence 2000) and not the 'Spread Spectrum Class Licence' 
(Radio-communications (Spread Spectrum Devices) Class Licence 2002).  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.

Table of Amendments to the LIPD Class Licence:

Item    Class Of Transmitter    Operating Freq.Band (Mhz)       Max. 
EIRP       Limits (see notes below)
45      Digital Modulation      915-928 1W      1, 2
45A     Digital Modulation      2400-2483.5     4W      1, 2
45B     Digital Modulation      5725-5850       4W      1, 2
Limits:
1)The radiated peak power spectral density in any 3kHz is limited to 25mW 
per 3Khz, and
2)The minimum 6dB bandwidth must be at least 500kHz.

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 new 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.

There are possibly two reasons why the ACA modified the LIPD licence in 
this way.

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 not 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.

What does this all mean?
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.

Regards,

At 12:58 AM 20/02/2004 +1030, you wrote:

>Hi,
>
>On Thu, 19 Feb 2004, Jamie Moir wrote:
> >
> >
> > IIRC they are/were addressing OFDM ATM, Proxim were pretty keen to
> > see both the Quickbridge 60, and MP.11a addressed.
>
> From memory, there was an additional determination recently which covers
>both the 2.4 and 5.8 GHz ISM bands. Now there is a classification for
>Digital Modulation Devices, which would cover OFDM, with a limit of 4
>Watts EIRP in both 2.4 GHz and 5.8 GHz.
>
>Regards
>
>Jamie
>
>--
>Jamie Lovick    <->  IT Consultant    <-> +614 1479 1681
>Hobby     : Doof.org                   -> jalovick at doof.org
>Director  : Drastic Solutions Pty Ltd  -> jalovick at drasticsolutions.com.au
>
>
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Michael R McDermott BEng (Comp. Eng.), MACS, IEEE
Wireless Systems Engineer
michael at veritechcorp.com.au
Veritech Corporation Pty Ltd
Phone: +61 2 6964 5377 Fax: +61 2 6964 5378
Mobile: 0414 522 593
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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