[FADCA] re: 802.11b/g Operations

[Paul J. Toth-NA4AR]

Rick and all....

The HSMM is working on a number of different aspects of using DSSS
technology above 900 MHz for digital networking and communications.  The
hardware group is currently working on developing a recommended Hardware
List for Radio Amateurs to build their systems around.  The software group
is focusing on networking issues, applications and insuring the security and
integrity of the system while being in compliance with Part 97.  ?The
massive proliferation of 802.11b devices operating under Part 15 offers a
particularly interesting challenge for Amateur Radio that we seldom see in
any of our other bands.  There are also legal and regulatory issues to deal
with to make this effort whole.

Based on some experience in the commercial broadcast industry, I think the
range estimates Rick offered are a little optimistic, particuarly here in
Florida with all dense foliage and Summertime sub-tropical downpours.
Getting the antenna above the treeline is paramount for any microwave
signal.  "If you can see it, you can make the shot" was the philosophy we
lived by in my Broadcast News days.  I believe we will be lucky to achieve a
five mile (5 mi) footprint radius in many areas for local access (User to
Access Point).  This stuff just does not like trees!  It is also worth
noting the commercial WISPs are using cellular-like antenna arrays at their
Access Points rather than omni-directional antennas.  Better gain and
rejection of unwanted signals.  Point to point with two foot parabolic
dishes, I look for fifteen miles.  Using separate RX and TX antennas (which
is possible with some Access Points, like Linksys, may enhance the hop
distance a little.  The key on the Point-to-Point stuff will be to get the
antennas (and antenna-mounted ampifiers) up in the air between 170' and
300'.  The 5.7 GHz band may actually be better for backbone operations as
802.11a will support connectivity up to 54 MBps.

While there is still some room for Part 97 in the 2.4 GHz band, I believe
Amateur Radio's real future is in the 3.3 GHz band.  There is virtually no
Part 15 activity there at the present time to trashup the band.  If we can
stake a claim first, our ability to use some power (>100mW) may help deter
Part 15 activity.  The 2.4 GHz band is seeing so much activity in many
metropilitan areas and Californai it's hard to squeeze a signal in edgewise.
In fact, a 2.4 GHz Amateur Radio voice repeater in California was recently
turned off because it couldn't deal with the interference from a nearby
802.11b Access Point.  The ARRL is investigating this situation.

One other point worth noting.  In my presentation last Saturday at Orlando,
I noted a third potential area for development and activity...the 'Last
Mile" for EComm (or EmComm, if you prefer).  These high speed links offer us
the ability to do voice, video and data simultaneously, if we have the right
equipment on both ends of the link.  That means a Red Cross Field Operation
could have their telephones and computer data routed over the same link.
This is something to look at for supporting hospitals during a disaster.

Thanks to Doug-KN4YT for his comments this morning about ESATCOM.  Tying all
this together with satellite links is the ultimate high speed wireless
solution.  Until then, bring on the HF Pactor station that can route
messages to gateway stations.

73 de Paul-NA4AR
ARRL HSMM Working Group