Any suggestion of buy a wireless pci card?

[Keith Lofstrom]

Richy <eric1i at 163.com> writes:

> I plan to use wireless network with my Fedora Core 1 at home. I got two
> PC in my home, one used by my wife is a laptop with winxp, the other
> desktop with fedora used by myself. I want to install a wireless LAN in
> my home and connect to internet by ADSL.
>
> So, it seems that I need a wireless access point with ADSL and a
> wireless pci card. Is there any suggestion about purchase a wireless pci
> card for my fedora? I usually find buy a hardware for linux need more
> attention.

First, find the book "Drive by Wifi" by Jeff Duntemann.  It introduces
some basic concepts.  The main concept about wireless you need to know
is that "physics is more important than architecture".  Also, look at
the websites for seattlewireless.net and personaltelco.net ; a lot of
good Linux stuff.

In most cases, an antenna on the back of a metal case PC, near the 
floor, is not a good idea.  The 2.4GHz (or 5GHz) radio waves are
not broadcast where you need them.  Thus, a PCI card is probably
not what you want.  Cable to a seperate antenna?  Every connector
loses about 1dB = 15% of your range, and cable losses to a
separately-mounted antenna are very high unless you use expensive,
hard-to-find cable.  The antenna wants to be next to the access point,
and the access point wants to be mounted up high with a clear line of
sight to the likely locations the laptop will be used.  High gain
antennas just re-arrange the coverage areas, so they do not compensate
for cable losses unless you can get by with lots of dead spots.

So, you want to use a discrete and separate access point (WAP),
fed by ethernet and wall-transformer power, so you can mount the
device wherever you want, with a couple of low-frequency cables
(100BT is low frequency!) running to it.  WAP's run their own
internal software, typically do DHCP and firewall and WEP security
and a lot of other stuff, and are configured by a web browser,
independently of any operating system.  I am running a cheap
Siemens Speedstream SS2624, but I have set up a couple of
Linksys BEFW11S4's for others and prefer those.  Some people
are running Linksys WRT54G's, which run Linux inside the box
and are capable of much fancy reprogramming, but you may not
need another hobby.  With only an ADSL connection to the net,
802.11b is more robust (though slower) than the faster but
more fragile (and expensive) 802.11g . 

The one place you may need speed is for network backups.  That
probably requires a hard connection anyway.  So sometimes your
wife will be plugging the laptop into a 100BT ethernet cable
connected to the backup server - any form of wireless will be
too slow for this.

Security and WEP is too big a subject to fit into an email. WEP
isn't perfect but a lot better than nothing.  Look at Duntemann.  

If your wife will someday move from Windoze to Linux, you will
want a PCMCIA card with good Linux drivers.  The best right now
are the Senao 200mW Prism-2 based cards. These are rebranded with
many names - the seattlewireless site has good pointers.  The best
in the near future will probably be the Atheros chipset - a lot of
good open-source people working on drivers for that.  Some chipsets
are hard to find good Linux drivers for, and unfortunately some
companies frequently change chipsets without changing model numbers
(sadly, Dlink and Netgear and Siemens do this a lot - avoid!).  

For the rest of you running a prism chipset under Linux, use the
hostap drivers in client mode - these are (from experience) more
usable than the wlan-ng drivers.

I hope that helps.  You will find plenty of opposing opinions,
especially about the usefulness of PCI cards.  

Keith

-- 
Keith Lofstrom           keithl at ieee.org         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs