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TCP-group 1995

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FCC 2402-2417 Ruling

IMHO, that there was no change in the status of 2402-2417 MHz was not because
of anything we said, but because of what IEEE 802.11 said: removing access to
18% of the ISM band (currently 2400-2483.5 MHz) planned for a hoard of Wireless
LAN devices would have severe financial impact nationally. The major
corporations are already working the Washington political arena, in case the
FCC filing didn't work.

The objective is to build very low cost, low power consumption, simple radios.
Narrow deviation (+/- 110 KHz deviation) GFSK is used to smash 1 mb/s into
1 MHz channels. 4-level GFSK is used to get 2 mb/s, when signal quality
permits. They slow-hop using 79 channels set on 1 MHz centers, staying at one
frequency no longer than 0.4 second. Acceptable receiver sensitivity is -75 dBm
for 10E-5 BER. Receivers have Eb/N0's of approximatley 16 dB (22 dB for
4-level). Transmitter power levels fall in the range of 1 mW to 1 W, divided
into 4 classes. One step of power reduction is requred for transmitters
producing more that 100 mW. A Direct-Sequence system is also being
standardized, which spreads the transmitted energy over 22 MHz, and uses
DQPSK to get spectral efficiency and throughput; it is significantly more
complex. There are at least 10 companies participating in the Committee whose
interests are in the FH system for each 1 interested in DS.

The 1-MHz wide frequency hoppers will contaminate the spectrum anywhere they
are used. Regardless of the filing, we always did share this spectrum with
ISM. The unlicensed folks plan to use it heavily. The ruling on 2390-2400
was definately a loss, as unlicensed PCS is likely to populate the spectrum
with signals much like those of Wireless LAN. This just means we will have
to be significantly more clever in avoiding the intereference. So much for
"clean" spectrum.

best regards/bob K6KGS

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