stds-802-16-tg4: RE: REGS/ RE: 5GHz Fixed Wireless Access in danger !
John and all,
If you look at the current rules as proposed by the FCC, the transmit power
is only limited to 1 W and to 3 dBm/3 kHz as shown in the following quotes:
(3) For systems using digital modulation in the 902 - 928 MHz, 2400 -
2483.5 MHz, and 5725 - 5780 MHz bands: 1 Watt.
(d) For direct sequence spread spectrum and digitally
modulated systems, the peak power spectral density conducted from the
intentional radiator to the antenna shall not be greater than 8 dBm in any 3
kHz band during any time interval of continuous transmission.
Just using those rules, one can send a signal of not more than 480 kHz with
1 W, because 10*log(480/3)= ~22 dB and (20+8) = 30 dBm.
So, nobody needs to use the hopping rules anymore. The band will just be
filled with baseband transmitter and then the band is really transferred
into a junk band.
Where is the protection we originally got from the much lower power density
required by the spread spectrum rules?
The position taken by the group on the Tele-conference (proposed by me) was
that we needed to protect the mobile applications in the band. To reach
their required coverage area, 100 mW is more than ample. Anything more would
drain their battery much faster.
With the rules proposed (10 dBm/MHz and 100 mW total power) OFDM is well
possible for the mobile application.
See also my comment in context below.
Regards
---------------
Vic Hayes
Agere Systems Nederland B.V., formerly Lucent Technologies
Zadelstede 1-10
3431 JZ Nieuwegein, the Netherlands
Phone: +31 30 609 7528 (Time Zone UTC + 2)
FAX: +31 30 609 7498
e-mail: vichayes@agere.com
http://www.orinocowireless.com/
> ----------
> From: Liebetreu, John[SMTP:jliebetr@intersil.com]
> Sent: 13 June 2001 0:34 AM
> To: stds-802-regs@ieee.org
> Cc: stds-802-16-tg4@ieee.org
> Subject: REGS/ RE: 5GHz Fixed Wireless Access in danger !
>
>
>
> Vic,
>
> I understand the question before us to be the following:
>
> The new NPRM basically proposes to treat digital modulations the same as
> DSSS
> modulations, subject to the same constraints on peak power, EIRP and peak
> power
> density, respectively. However, they "invite comment as to whether the
> flexibility we are allowing for digitally modulated systems warrants a
> reduction
> in permitted power levels to reduce the likelihood of any adverse impact
> on
> other systems operating in this spectrum. . ." (from the NPRM).
>
> Also, in the report "Tentative Report of Radio Regulations
> Tele-conference, held
> June 1, 2001" (doc.:IEEE802.11-01/366-r0), it is noted that "Vic proposes
> to use
> 10 dBm/MHz" and further, that "... the general idea was to support a 100
> mW max
> power rule."
>
> With this background, let me add my thoughts on the question of
> appropriate
> sharing in part 15.247 :
>
> The current FCC regulation permits much higher transmit power (up to 1W);
>
VH--> already now there is a signal raised by the Primary users that they
see the background noise increase beyond the level they can tolerate. I
believe that 1 W is much too high.
> it
> seems ill-conceived to recommend that the transmit power be reduced from
> that
> currently defined by the regulatory body. Doing so can only serve to
> hamper the
> performance of MANs and LANs in the mixed-use environment. By definition,
> PAN
> devices operating in the same band as MAN / LAN systems (and more than
> likely at
> lower power due to the economic requirements for PANs) will always prevail
> in
> the near-far scenario. Even with a reduction in allowable transmit power,
> moving PAN devices closer together will always enable the link to be
> established. On the other hand, reducing the allowable transmit power in
> MAN
> and LAN systems will dramatically reduce their range and utility. This
> will
> place a severe economic burden on MANs and LANs operating under part
> 15.247,
> stunting, if not strangling, the growth and viability of these industries.
VH--> LANs as they are now deployed transmit some 17 dBm. Some even reduce
the power to as low as 1 dBm. What is wrong with those LANs? With a good
antenna, even MANs can become useful.
> Viewed in the broader context of the NPRM, the proposed power limitation
> looks
> even more ill-advised. The FCC is proposing to eliminate the requirement
> that
> systems operating in part 15.247 have 10 dB processing gain. In theory,
> this
> will allow new systems to increase the data rate by a factor of 10, but
> only if
> they have 10 dB more power to support the higher rate.
VH--> please explain why you need more power to get higher data rates.
> The proposal under
> discussion to limit the power to 100 mW appears to mock the intent of the
> NPRM
> by reducing the power by 10 dB, instead of increasing it. I fear that, if
> we
> advance the 100 mW recommendation, we are closing the door to further
> progress
> in our industry.
>
>
>
> John M. Liebetreu, Ph.D.
> Senior Scientist
> Office of Technology Development
> Broadband Wireless Access
> Intersil Corporation
>
> tel: 480-607-4830
> fax:480-607-4806
>