| Geoffrey S. Mendelson 2007-09-26, 4:33 am |
| Scott wrote:
> Um, no. Any commercially available consumer pipeline will crawl with 20
> connections. Anything above that will cost more than enought to
> eliminate the thought sharing it for free.
It depends upon what you are doing with it. If people are "surfing
the web", it can be very fast. Web page data generaly comes down in
large blocks which means lower overhead per block. People don't notice
small differences in latency. If it takes a half a second for a packet
to arrive from a server to your screen, you won't care, as long as they
keep coming.
VoIP requires a latency of 150ms or less. Go over it and the connection
starts to "stutter" and fail. The same with videoconferencing. Latency is
not a problem with streaming audio and video, but consistency is.
Once you start to demand consitency and low latency for long periods
of time (more than a second), you find out why consumer connections
are just not viable for commercial use.
Since most people don't use 100%, or probably even 10% of their available
bandwidth over a 24 hour period, it seems logical that you could share
the other 90% and not miss it. It does not work that way, no one wants
to make phone calls at 3am Sunday because the latency is low then.
QOS (Quality of service) routing does not really help. It makes big
packets wait for small ones, but eventually the big ones go through
anyway and it slows things down.
The other problem with WiFi networks is that since it is a bus type
architechture, performance degrades as more people use it.
You can see it in shared channel cellular phones, the D-AMPS system
(aka TDMA) assigns time slots as needed to improve efficency and
conversations on crowded channels have dropouts because no slot
is available when needed. The GSM system assigns slots for the length
of a connection, so there are no dropouts, but less effiecency.
The CDMA system works differently and acts more like WiFi and crowded
CDMA systems tend to work better if lightly loaded, but everyone suffers
when a channel becomes crowded.
Offering free WiFi from your home, once you get past the security and
ISP problems, is fine for people getting email on their handhelds,
reading the news, etc. Once your "customers" get into high demand,
low latency applications, things fall apart.
As an aside, a friend needs a WiFi SIP handset for making VoIP calls.
I found that Linksys sells a unit that retails for $120 in the U.S.
There are similarly priced SKYPE units available.
If you don't care about using other people's bandwidth without permission,
as long as people stil don't know/care about securing their access,
you could wander around a large city and use it instead of a cell phone.
Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/
|