From: Roger Watt <rwwatt@watserv1.uwaterloo.ca>
Subject: Re: Info on wireless ethernet link needed
Followup-To: comp.dcom.lans
Keywords: wireless ethernet bridging
Organization: Computing Services, University of Waterloo
Distribution: na
Date: Mon, 4 Jan 1993 21:22:07 GMT

> My office at Virginia Tech in Blacksburg, Virginia would like to establish
> a wireless ethernet connection with another office building that is across
> a busy street somewhere between a quarter mile and a half mile away,
> clearly visible via line of sight. The university refuses to trench
> between the two for various reasons including cost and disruption of
> traffic. Hence we'd like to know all there is to know about wireless
> ethernet products...
 
I don't know beans about microwave, but we use something that perhaps
others might find interesting. It is an "ARLAN 620" SPREAD-SPECTRUM RADIO
matched pair of Ethernet bridges. Cost for the pair, CA$9000. Speed is
1Mbps. Requires line-of-sight path between two "yagi" antennae, which we
mount on masts on roof (or equivalent bolted to side of building). Max
distance is 8km with antennae that have 16m line-of-sight clearance. We
put a pair of these in service in Jan92. The weather has cooperated nicely
to let us verify that transmission is not fazed by fog, drizzle, rain, or
snowstorm. Made by a Canadian company in the Toronto area called
Telesystems SLW, distributed by another Toronto-area company called Brak
Systems. Spread-spectrum radio operates way below the level that requires
licensing in Canada (don't know about regulations in other countries). 

We have one antenna on a 3m mast on our Library building, from which one
can see the top of every other building on campus, and have put the other
antenna in interesting places ... such as on a microphone stand in an
office in a just-moved-into building about 500m away; it worked fine ...
except for the day the occupant closed the venetian blinds. 


                     *  ////////////////////////  *
                     |                            |
                     |                            |
                     |                            |
            .--------+-.                        .-+--------.
            | ARLAN 620|                        |ARLAN 620 |
            '-----+----'                        '-----+----'
coax Ethernet     |                                   |     coax Ethernet
==================+==                               ==+==================

There is a second and less expensive member of the product family, called
the ARLAN 650/610, which is a "headend" unit that can communicate with
multiple card-in-PC "clients"; all of the clients contend for the 1Mbps
bandwidth. CA$2900 for the headend and CA$1400 for each client card. We
are currently using a 650/610 pair to connect to a rented building about
300m off campus, across a city street (fibre would have cost us
CA$20K). We are using them in the same concept as a 620 pair ... we have
the card-in-PC unit at the on-campus side, using the PC as a router
(running PCroute routing software), and the "headend" unit connected to
the Ethernet backbone in the off-campus building. 
           
Our contact is:
   Brak Systems Inc
   Mississagua, Ontario
   416-272-3076