The planned uses for the link is sharing of a broadband wireless
connection that caps out at around 1.5 mbps, remote file sharing, most
likely using terminal services, between point A & B, and I'd like the
ability to occassionally monitor 3 different wired IP-based cameras in
real time and at decent resolution, preferably at the same time. I
realize that the file sharing, and any incident file transfers as well
as sharing of the broadband connection would be more than adequate at
the estimated throughput of a poorer-grade "b" link. The terminal
server and IP cameras are located at site B, and the broadband
connection based at site A. Through a gift of geography, the
broadband link is unavailable at site B, and will likely always remain
so. If I were able to get the wireless broadband at both sites, I
could try tunneling between the sites via the broadband ISP, but this
would still likely not suit streaming video since the upload speeds
are capped at 400kbps, but I rarely ever see better than 200 kbps, and
only in brief bursts. I've discussed the idea of a repeater installed
by them at my expense that would get around the obstructions between
site B and the broadband provider's sector array, but they have no
interest as I would be the only potential customer that would
benefit/come onboard as the result of such a repeater, and yes, I
realize that said repeater would further drop the link speed, unless
the provider upped the BW for that link on their end.
I need to do a more detailed analysis of the network traffic at site
B. I have seen prolonged periods of overall network activity at
around 15-20 mbps on that network when the only significant activity I
can identify is a user monitoring multiple cams (and there is a lot of
activity in the camera fields). That system is secure, currently has
no internet connection available, and there are no unknown users wired
in, and no local wifi equipment. When the IP cams are fully shut
down, the general network activity is what you would expect on a small
network with minimal file sharing and mild to moderate printing to 4
different shared printers (with rarely more than one printer running
at any given time). I realize I need to break down the network
activity per IP, but haven't had the opportunity, and strongly suspect
the IP cams the source of that activity. My needs in terms of the cam
monitoring would likely be lower since at the times I would be
interested in monitoring the cams via the link, there would be little
expected activity in view.
KB, I appreciate your efforts to answer my question, which is whether
or not I could expect to be able to establish some grade of "g" link
at this distance. Your dBm figures closely correspond to those I had
obtained independently.
I appreciate all the time that Valentin's considered responses must
have taken, and want him to know that I "got" it before I ever posted,
and was part of the reason I posted in the first place. As a ham with
over 30 years of active participation, including some microwave work
"in the dark ages", I do have at least a little appreciation of RF
propagation. I'll be the first to admit that I have no experience
with 802.11 equipment, and thus the reason I came to this group. You
are correct in one point - I do consider this a hobby and learning
experience, just as I have computers and wired networking. My
livelihood has no connection with computing, other than using
computers as data management and billing tools. I'm sure that with
your fund of knowledge you'll be the second to get wifi out past
Jupiter (think NASA's BTDT). It's a shame that you would prefer to
dissuade and chest-pound rather than sharing that knowledge.
Regards
On 9 Apr 2004 14:41:53 -0700,
(E-Mail Removed) (K Bloch) wrote:
>What he asked for is what else he may need. For 802.11b speeds the
>distance/loss/antenna combo is more then adequate. Adding amplifiers
>as others suggested usually causes more problems then its worth.
>Unless the Amp is very very good it cannot switch fast enough from TX
>to RX in the presence of noise to operate well.
>
>Now a link speed of 11 mbits per second should be able to yield about
>5 to 6 mbits of total throughput. For most home and business users
>this is a more then adequate link speed. The questions is still what
>is the link going to be used for. If it is to provide internet and
>email access on a netowrk with a T1 to the internet it should be more
>then adequate. If you are trying to use it for VOIP services it will
>probably have trouble being that it is a half duplex media with a high
>rate of packet retries (anything above 1/1000 is high in my opinion)
>
>Valentín Guillén <(E-Mail Removed)> wrote in message news:<(E-Mail Removed) >...
>> On Thu, 08 Apr 2004 18:22:16 -0500, Bubba wrote:
>>
>> > Per specs at D-Link's site, this AP is supposed to give 54mbps at - 66
>> > dBm. Assuming I am able to achieve something close to the calculated
>> > -51.6 dBm with my installation, should the additional 15 dBm handle
>> > "average" rain fade, etc., or am I nuts trying for more than "B"
>> > speeds on this link?
>> >
>> > Thanks,
>>
>> With all due respect, I think you *still* don't get it!
>>
>> Regardless of what's "doable in theory", if you're not willing to spend to
>> do it right, you'll regret spending the money you DO spend.
>>
>> What about wind-loading factors; rain-fade; equipment aging and frequency
>> drifting; moisture infiltration into cables; and perhaps the bigest bugabo
>> of all -- signal inferference? If you're not using dedicated frequencies,
>> but instead are using the ISM band, you HAVE NO FREQENCY &
>> FREQENCY-INTERFERENCE PROTECTION!!
>>
>> Now I should be perfectly clear here: I'm NOT saying you shouldn't do it,
>> nor am I saying it can't be done. What I'm saying is to eveluate with the
>> principles involved, exactly how important the link IS. If you're still
>> insistent that YOU can do it, hire a professional consultant to design the
>> system. You probably won't get a written guarantee of performance unless
>> they purchase and install!
>>
>> The most likely outcome here is that you'll insist upon doing it, it will
>> underperform/not perform, and we'll see your posts here in a month with
>> pleas for assistance. Are you both an RF AND networking engineer? Leave
>> it to the professionals, unless this link is nothing more than a hobby and
>> a learning experience. In the latter case, have at it!
>>
>> I regularly shoot WiFi 802.11x signals in excess of ten miles, but I'm
>> both an RF and networking engineer, and I know what I'm doing. So I'm not
>> saying that this is not doable. I'm saying to sit back with decision and
>> budget makers, and decide how vital this link is. Then proceed in the
>> appropriate manner.......
>>
>> Best Regards,
>>
>> vg