PA-ComNet Meeting Feb. 27, 2002

The meeting began at 7:45 AM at the Terman library. The topic was introduced
with a brief discussion of the features and characteristics of fixed fiber and
wireless data transmittal. Advantages of fixed fiber include faster data
transfer, much greater security, and a direct connection to the Internet that
is not limited to line-of sight or distance.  Wireless provides many valuable
access options quickly and cheaply, but with much lower security and data
transfer speeds.  It is limited to line-of-sight connections and relatively
short distances. Fiber access is better for high bandwidth and security.
Wireless can be faster than commercially available services, and is much
cheaper and easier to deploy and run.

Paul Gregg described his background and experience.  He has been in Palo Alto
since coming here to work in 1999. In the summer of 2001 he was laid off from
SGI (Silicon Graphics, Inc.), and since November he has been working with the
Linux-based wireless setup.  He set up a station at the Thai City restaurant on
El Camino Real.  The result is called Palo Alto Freenet, since there is no
charge presently to use it.  It has traffic shaping and firewalls to give
priority to certain packets in order to keep interference down.  There are 7
users so far, some using it every day. The Linux Firewall/Shaper has separate
Ethernet cards for different functions to provide better security and
operation. 

The Wi-Fi network is separated from his LAN to provide better security. Speeds
are 3-4 Mbps each way.  Since there is no scrambling of the network data it
should be treated as open. Assume that anything sent can be read by anybody,
like a party phone line. WEP encryption doesn't work well and shouldn't be
depended upon.  Exposure to the Internet is the same as DSL, phone, or cable
modems.  Users should have a personal firewall for system and data security.
Users should also use crypto technologies like SSH, SSL, PGP, etc.

There was a question about the various acronyms that were being used. Paul
noted that dict.org gives names for these acronyms. 

There are 3 access points operating on channels 1, 6 & 11 , one of which is on
the roof of Thai City restaurant (http://www.thaicity.com), set up initially to
provide wireless service to the entire nearby neighborhood, now an access point
is located inside the restaurant for patron use.

The modulation scheme is a form of spread spectrum that is 25 MHz wide, at
2400-2475 MHz.  Channel 1 is very busy. Channel 6 is quiet.

The 3 access points are wired to a single 6-port hub and then to a Linux
server connected to the Internet.  Access point power output level is 50
milliwatts.  The equipment is cheap and readily available at places like Fry's
and e-Bay. Coverage area is about 300 meters, but signals can be sent and
received farther. Signal level is low, so any loss is significant.  The coax
cable (LMR-400) used gives a 3.3dB of loss per 50’, or 50% of initial signal
strength.  The antenna has 12dB of gain, putting out 100 milliwatts ERP
(effective radiated power), which serves one local neighborhood, within about
300 meters.

Nearby access points can be created with an antenna and SMC 2652W bridge using
Linux firmware to talk to each other wirelessly. There is back station talking
and configuration (802.1d Spanning Tree) from station to station to keep the
data traffic moving and the network cohesive. The system can eventually be
setup with each neighborhood having a separate channel.

Software ties the nodes and points together for each frequency. As the number
of users grows, speeds will slow as all the users need to go through the same
Internet access point. As the network grows, new Internet access
points will be needed to handle the added users and keep speeds up. It is
basically a store and forward system.

Cost of the access point was about $200 including a simple antenna. One
difficult item is an SRAM card at 3.3v which costs about $200 which is needed
to program the access point. Paul now has one with the Linux firmware loaded on
it. Contact him to meet to have your access point flashed with Linux.

The system needs an antenna height of about 50', which has to be above trees.

It is unclear if formal city permission is needed to install such an antenna.
Users should consider it to be like ham radio with minimal regulation.  We just
need a number of antennas on tall buildings with power to the antennas in order
to set up an area wide network. 

The existing restaurant setup has a turn off after closing feature, to keep
people from hanging around well after closing working with the Internet at
least inside the building.

This wireless Freenet isn't intended to be a broadband delivery system.

It's  intended for web browsing, e-mail, and ease of connection, at a low cost
for the hardware.  Speeds are fast, latency is low and it corrects errors and
fallouts very fast.  It can be set up so that paying users get priority and
higher speeds. 

Anyone that wants to offer to help should contact Paul Gregg at
kd4idr@yahoo.com, or http://www.geocities.com/kd4idr/pafreenet/

The meeting adjourned at 8:43 AM.  Respectfully submitted, Bob Moss