stds-802-16-tg4: 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); 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.
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. 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