What are the requirements for a PC to accept a wireless card?
What are the requirements for a PC to accept a wireless card?. Discuss What are the requirements for a PC to accept a wireless card?, on Wireless Forums.
What are the requirements for a PC to accept a wireless card?
Hey!
I am looking into buy a desktop. I want to make sure it is able to
take a wireless card. What should I look for when shopping for a pc?
Thanks so much
Re: What are the requirements for a PC to accept a wireless card?
newcompgirl wrote:
> Hey!
> I am looking into buy a desktop. I want to make sure it is able to
> take a wireless card. What should I look for when shopping for a pc?
> Thanks so much
>
Either a PCI slot (for internal) or a USB port for external. Basically
any relatively recent machine will go wireless. I have 2 new machines
on my wireless network (Dell 5100's), a homebuilt machine (6 months old)
and a pentium 3 machine(Dell optiplex). The new Dells connect with Dell
USB branded dongles, my machine connects with a PCI card, as does the
old optiplex.
Re: What are the requirements for a PC to accept a wireless card?
[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
In <uv0em19f7je6gkpvt32ir8lb8q7kh68140@4ax.com> on Tue, 01 Nov 2005 06:39:00
GMT, Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>On Tue, 01 Nov 2005 00:21:10 GMT, John Navas
><spamfilter0@navasgroup.com> wrote:
>
>>In <1130799972.916708.324320@g44g2000cwa.googlegroups .com> on 31 Oct 2005
>>15:06:12 -0800, "newcompgirl" <lburicks@hotmail.com> wrote:
>>
>>>I am looking into buy a desktop. I want to make sure it is able to
>>>take a wireless card. What should I look for when shopping for a pc?
>
>>An open PCI slot or USB port.
>
>Ummm... if your USB port is USB 1.1, then you'll be limited to 802.11b
>speeds (11Mbits/sec maximum). With USB 2.0, 802.11g speeds are
>possible (54Mbits/sec).
Ummm... those are raw speeds. Real throughput is more like 5 Mbps for
802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
connection is within USB 1.1. Thus USB 1.1 won't slow Internet access (the
most likely use), and probably won't even have all that much effect on
computer-to-computer networking, particularly if there's more than one
simultaneous wireless transaction.
--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>
Re: What are the requirements for a PC to accept a wireless card?
On Tue, 01 Nov 2005 00:21:10 GMT, John Navas
<spamfilter0@navasgroup.com> wrote:
>[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
>
>In <1130799972.916708.324320@g44g2000cwa.googlegroups .com> on 31 Oct 2005
>15:06:12 -0800, "newcompgirl" <lburicks@hotmail.com> wrote:
>
>>I am looking into buy a desktop. I want to make sure it is able to
>>take a wireless card. What should I look for when shopping for a pc?
Re: What are the requirements for a PC to accept a wireless card?
On Tue, 01 Nov 2005 06:13:31 GMT, John Navas
<spamfilter0@navasgroup.com> wrote:
>[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
>
>In <uv0em19f7je6gkpvt32ir8lb8q7kh68140@4ax.com> on Tue, 01 Nov 2005 06:39:00
>GMT, Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>
>>On Tue, 01 Nov 2005 00:21:10 GMT, John Navas
>><spamfilter0@navasgroup.com> wrote:
>>
>>>In <1130799972.916708.324320@g44g2000cwa.googlegroups .com> on 31 Oct 2005
>>>15:06:12 -0800, "newcompgirl" <lburicks@hotmail.com> wrote:
>>>
>>>>I am looking into buy a desktop. I want to make sure it is able to
>>>>take a wireless card. What should I look for when shopping for a pc?
>>
>>>An open PCI slot or USB port.
>>
>>Ummm... if your USB port is USB 1.1, then you'll be limited to 802.11b
>>speeds (11Mbits/sec maximum). With USB 2.0, 802.11g speeds are
>>possible (54Mbits/sec).
>Ummm... those are raw speeds. Real throughput is more like 5 Mbps for
>802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
>connection is within USB 1.1. Thus USB 1.1 won't slow Internet access (the
>most likely use), and probably won't even have all that much effect on
>computer-to-computer networking, particularly if there's more than one
>simultaneous wireless transaction.
I beg to differ somewhat. You're correct on the thruput. A 5Mbit/sec
thruput is not going to be a bottleneck for a 1.5 or 3.0Mbits/sec DSL
line. However, it will be too slow for a 6Mbit/sec DSL or cable
modem.
Also, the serial interface (USB) has to go faster than the raw
wireless speed or the system will bottleneck. To the best of my
limited experience, all 802.11g USB wireless devices have a feature
where the driver sets the maximum speed to 11Mbits/sec if it's plugged
into a USB 1.1 port. I just verified that with a Dlink DWL-G120.
11mbits/sec maximum association speed when connected to my WRT54G
v1.1.
Incidentally, I try to refer to connection "speed" as the raw wireless
data rate and use the term "thruput" for the actual transfer speeds.
Re: What are the requirements for a PC to accept a wireless card?
"newcompgirl" <lburicks@hotmail.com> wrote in message
news:1130799972.916708.324320@g44g2000cwa.googlegr oups.com...
> Hey!
> I am looking into buy a desktop. I want to make sure it is able to
> take a wireless card. What should I look for when shopping for a pc?
> Thanks so much
As John says, either a spare PCI slot *inside* the PC, or a spare USB port
on the *outside*.
My personal preference is the former; this just involves undoing a couple of
screws on the side panel of the PC, removing the panel, taking out a
blanking plate on the back of the PC so that the PCI card antenna can poke
out, then just slotting the WiFI card in to a vacant slot. There's only one
size slot the card will fit in. -ut the panel back. WIll take 5 mins tops.
With the PCI option however, you will have the WiFi antenna poking out the
back of the PC, which if your PC is shoved under a desk in a corner of the
room, will not help signal strengths. The advantage of the USB dongle is
that it will be more readily positionable. For my PCI WiFi card, I bought a
more 'powerful' antenna, and a 1m extension cable. Through a floor and
doors, I still get maximum signal strength from the router.
Either way, make sure that you buy a WiF 802.11g capable card, not 802.11b.
You will also need access to a WiFi access point (AP) attached to your
internet connection, this to transmit the data to/from your new WiFi
desktop. E.g. I have broadband cable modem connected to a Linksys WRT54G
router/AP. One of my PCs is connected to this router/AP by cable, and one
by WiFi.
Re: What are the requirements for a PC to accept a wireless card?
[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
In <b53em115gkn8dt01357srj0uvl29q1bpg7@4ax.com> on Tue, 01 Nov 2005 06:48:31
GMT, Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>On Tue, 01 Nov 2005 06:13:31 GMT, John Navas
><spamfilter0@navasgroup.com> wrote:
>
>>In <uv0em19f7je6gkpvt32ir8lb8q7kh68140@4ax.com> on Tue, 01 Nov 2005 06:39:00
>>GMT, Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>>>Ummm... if your USB port is USB 1.1, then you'll be limited to 802.11b
>>>speeds (11Mbits/sec maximum). With USB 2.0, 802.11g speeds are
>>>possible (54Mbits/sec).
>
>>Ummm... those are raw speeds. Real throughput is more like 5 Mbps for
>>802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
>>connection is within USB 1.1. Thus USB 1.1 won't slow Internet access (the
>>most likely use), and probably won't even have all that much effect on
>>computer-to-computer networking, particularly if there's more than one
>>simultaneous wireless transaction.
>
>I beg to differ somewhat. You're correct on the thruput. A 5Mbit/sec
>thruput is not going to be a bottleneck for a 1.5 or 3.0Mbits/sec DSL
>line. However, it will be too slow for a 6Mbit/sec DSL or cable
>modem.
With all due respect, such speeds are very rare in practice -- that really
isn't going to be an issue.
>Also, the serial interface (USB) has to go faster than the raw
>wireless speed or the system will bottleneck. To the best of my
>limited experience, all 802.11g USB wireless devices have a feature
>where the driver sets the maximum speed to 11Mbits/sec if it's plugged
>into a USB 1.1 port. I just verified that with a Dlink DWL-G120.
>11mbits/sec maximum association speed when connected to my WRT54G
>v1.1.
Crappy design, but I'll take your word for it.
--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>
Re: What are the requirements for a PC to accept a wireless card?
> 802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
> connection is within USB 1.1. Thus USB 1.1 won't slow Internet access (the
I disagree. My broadband connection is to be upgraded to 10Mbps by the
year end and there are a lot of ISP's in the UK that are offering 8Mbps
and even 24Mbps for about $40 a month.
That's going to start to present issues for even 802.11g for people that
aren't damn close to the AP.
Re: What are the requirements for a PC to accept a wireless card?
Jeff Liebermann wrote:
> On Tue, 01 Nov 2005 06:13:31 GMT, John Navas
> <spamfilter0@navasgroup.com> wrote:
>
>>Ummm... those are raw speeds. Real throughput is more like 5 Mbps for
>>802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
>>connection is within USB 1.1. Thus USB 1.1 won't slow Internet access
>>(the most likely use), and probably won't even have all that much effect
>>on computer-to-computer networking, particularly if there's more than one
>>simultaneous wireless transaction.
>
> I beg to differ somewhat. You're correct on the thruput. A 5Mbit/sec
> thruput is not going to be a bottleneck for a 1.5 or 3.0Mbits/sec DSL
> line. However, it will be too slow for a 6Mbit/sec DSL or cable
> modem.
I tend to agree with John. How much throughput do you really get on a
6-10Mbps cable/DSL connection? I've variously seen the 'real' speed of the
Internet calculated at 1-2Mbps. I can rarely get much more than that off
my T1-LAN connected desktop machine. Right now, numion.com says it's
256Kbps and DSLreports.com says 738Kbps - but it's a busy period with 1000
or so computers on this LAN.
If you're just using the connection for Internet access, USB 1.1 isn't going
to make much difference. If you have local file sharing, it's going to be
significant - not least because aiui a single USB 1.1 connection is going
to force your whole WLAN to use 802.11b.
--
derek
Re: What are the requirements for a PC to accept a wireless card?
[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
In <MPG.1dd148d33a3362ea989ef7@news.cable.ntlworld.co m> on Tue, 01 Nov 2005
09:38:52 GMT, David Taylor <djtaylor@bigfoot.com> wrote:
>> 802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
>> connection is within USB 1.1. Thus USB 1.1 won't slow Internet access (the
>
>I disagree. My broadband connection is to be upgraded to 10Mbps by the
>year end and there are a lot of ISP's in the UK that are offering 8Mbps
>and even 24Mbps for about $40 a month.
Even your connection isn't going to be running at more than USB 1.1 speeds
except in rare circumstances.
--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>
Re: What are the requirements for a PC to accept a wireless card?
David Taylor wrote:
>>802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
>>connection is within USB 1.1. Thus USB 1.1 won't slow Internet access (the
>
>
> I disagree. My broadband connection is to be upgraded to 10Mbps by the
> year end and there are a lot of ISP's in the UK that are offering 8Mbps
> and even 24Mbps for about $40 a month.
>
> That's going to start to present issues for even 802.11g for people that
> aren't damn close to the AP.
>
> David.
Hi,
Bear in mind the line is 10 or 24Mbps capable. It's not going to run at
that speed all the time every time. So I won't worry about it.
Tony
Re: What are the requirements for a PC to accept a wireless card?
> Even your connection isn't going to be running at more than USB 1.1 speeds
> except in rare circumstances.
I'll let you know but USB1.1 isn't the bottleneck here, it will be the
radios. 802.11b will be inadequate and even g will drop back quickly to
a speed that will be too low for these higher speeds once the signal
drops.
Flat out at 54Mbps, throughput can only be half that at best and then
the lower rates will again be potentially too low.
Re: What are the requirements for a PC to accept a wireless card?
> Bear in mind the line is 10 or 24Mbps capable. It's not going to run at
> that speed all the time every time. So I won't worry about it.
> Tony
No but when a download is trundling down from a well hosted site (or
several downloads at once, we don't all just view web pages), things
will start to struggle.
Re: What are the requirements for a PC to accept a wireless card?
On Tue, 01 Nov 2005 09:48:03 -0400, Derek Broughton
<news@pointerstop.ca> wrote:
>Jeff Liebermann wrote:
>
>> On Tue, 01 Nov 2005 06:13:31 GMT, John Navas
>> <spamfilter0@navasgroup.com> wrote:
>>
>>>Ummm... those are raw speeds. Real throughput is more like 5 Mbps for
>>>802.11b, and more like 20 Mbps for 802.11g, and pretty much any broadband
>>>connection is within USB 1.1. Thus USB 1.1 won't slow Internet access
>>>(the most likely use), and probably won't even have all that much effect
>>>on computer-to-computer networking, particularly if there's more than one
>>>simultaneous wireless transaction.
>>
>> I beg to differ somewhat. You're correct on the thruput. A 5Mbit/sec
>> thruput is not going to be a bottleneck for a 1.5 or 3.0Mbits/sec DSL
>> line. However, it will be too slow for a 6Mbit/sec DSL or cable
>> modem.
>I tend to agree with John. How much throughput do you really get on a
>6-10Mbps cable/DSL connection?
I have 2 customers with 6000/512 DSL from SBC. They get about
4.3Mbits/sec sustained thruput. Both have been up for about year at
this speed. Sometimes, usually in the middle of the night, the speed
tests dribble up to about 5Mbits/sec.
Favorite speed test site: http://nitro.ucsc.edu/
or other NDT test sites (see bottom of page).
Looking at the speed test results from DSLReports.com at: http://www.dslreports.com/archive
I see 4.4Mbits/sec is about typical for the higher speed cable and DSL
connections. Ignore the reports that appear to be symmetrical speeds
as those are probably directly from the ISP's. Hmmm.... Canada is
getting faster speeds than the US.
In the past, I was proclaiming that I could get about 5Mbits/sec
thruput on an 11Mbit/sec 802.11b connections. Well, that's true in
the lab but not true in any reflection or interfence infested
environment. More typically, I get about 3.5-4.0Mbits/sec max from
802.11b (WRT54G v1.1 and Orinoco Classic Silver). That would not be
enough to keep up in speed with a higher speed cable or DSL
connection.
>I've variously seen the 'real' speed of the
>Internet calculated at 1-2Mbps. I can rarely get much more than that off
>my T1-LAN connected desktop machine.
A T1 is rate limited to 1.544Mbits/sec. You'll see a thruput of about
1.2Mbits/sec in both directions.
>Right now, numion.com says it's
>256Kbps and DSLreports.com says 738Kbps - but it's a busy period with 1000
>or so computers on this LAN.
Only 256Kbits/sec upstream on a T1? You must be running servers
through the T1.
>If you're just using the connection for Internet access, USB 1.1 isn't going
>to make much difference. If you have local file sharing, it's going to be
>significant - not least because aiui a single USB 1.1 connection is going
>to force your whole WLAN to use 802.11b.
I agree for a T1 at 1.5Mbits/sec.
I also agree for a common DSL and slow cable connection at 1.5 or
3.0Mbits/sec.
I don't agree for a high speed 6Mbit/sec DSL or similar cable modem
speed.
Drivel: DSLReports.com speed test results that show broken routers
with high packet loss but probably also shows lossy DSL, cable modem,
and wireless connections. http://www.dslreports.com/badrouters
>
> Favorite speed test site:
> http://nitro.ucsc.edu/
> or other NDT test sites (see bottom of page).
Interesting speed test site you listed as your favorite. I noted it
says: "Systems behind firewalls must permit TCP ports 3001, 3002, and
3003." Are these normally open? I have a Linksys BEFW11s4 which
functions as a firewall and Zone Alarm. The test seemed to work just fine.
On Tue, 01 Nov 2005 11:33:17 -0600, Bob Alston
<tulsaalstonsNOSPAM@cox.net> wrote:
>Jeff Liebermann wrote:
>> Favorite speed test site:
>> http://nitro.ucsc.edu/
>> or other NDT test sites (see bottom of page).
>Interesting speed test site you listed as your favorite. I noted it
>says: "Systems behind firewalls must permit TCP ports 3001, 3002, and
>3003." Are these normally open? I have a Linksys BEFW11s4 which
>functions as a firewall and Zone Alarm. The test seemed to work just fine.
Try the diagnostics output under more details. Lots of numbers in
there. Sometimes, I get a suprise.
I have no clue what they mean by having 3001-3003 open. It seems to
use those for OUTGOING connections, not incoming. I guess if the
firewall were a proxy server, that would be a problem. However, for
conventional wireless routers, that permit outgoing connections on
literally any port number, it should not be an issue.
Re: What are the requirements for a PC to accept a wireless card?
[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
In <MPG.1dd1a88677546c7f989ef9@news.cable.ntlworld.co m> on Tue, 01 Nov 2005
16:27:40 GMT, David Taylor <djtaylor@bigfoot.com> wrote:
>> Bear in mind the line is 10 or 24Mbps capable. It's not going to run at
>> that speed all the time every time. So I won't worry about it.
>> Tony
>
>No but when a download is trundling down from a well hosted site (or
>several downloads at once, we don't all just view web pages), things
>will start to struggle.
It doesn't actually "struggle" -- TCP/IP throttles back gracefully to whatever
the link can handle.
--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>
Re: What are the requirements for a PC to accept a wireless card?
On Tue, 01 Nov 2005 07:11:15 GMT, John Navas
<spamfilter0@navasgroup.com> wrote:
>>Also, the serial interface (USB) has to go faster than the raw
>>wireless speed or the system will bottleneck. To the best of my
>>limited experience, all 802.11g USB wireless devices have a feature
>>where the driver sets the maximum speed to 11Mbits/sec if it's plugged
>>into a USB 1.1 port. I just verified that with a Dlink DWL-G120.
>>11mbits/sec maximum association speed when connected to my WRT54G
>>v1.1.
>Crappy design, but I'll take your word for it.
May I humbly suggest you reconsider your opinion. Dialup external
modems so the same thing. If you set the serial port data rate to
19.2Kbits/sec, it will set the maximum connect speed to 14.4Kbits/sec.
To get 56K speeds, you need 57Kbits/sec or faster SIO speeds.
Admittedly, you can force the modem to connect at a higher speed, but
that will just eventually overflow the modem buffer.
The same thing applies to USB which is just a fancy name for a serial
port with a weird connector. Max data rate for USB 1.1 is
12Mbits/sec. It makes no sense for the wireless to go any faster as
the driver buffer will overflow. So, they limit the speed to
11Mbits/sec.
I would call this "defensive design" as I really would not want to
explain to customers why their USB wireless is eating packets due to
an inability for the USB/SIO interface to keep up with the wireless
data rate.
Re: What are the requirements for a PC to accept a wireless card?
[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
In <bnrfm1pjb87m4n0ec7j5o21slc9de8ds9s@4ax.com> on Tue, 01 Nov 2005 23:34:06
GMT, Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>On Tue, 01 Nov 2005 07:11:15 GMT, John Navas
><spamfilter0@navasgroup.com> wrote:
>
>>>Also, the serial interface (USB) has to go faster than the raw
>>>wireless speed or the system will bottleneck. To the best of my
>>>limited experience, all 802.11g USB wireless devices have a feature
>>>where the driver sets the maximum speed to 11Mbits/sec if it's plugged
>>>into a USB 1.1 port. I just verified that with a Dlink DWL-G120.
>>>11mbits/sec maximum association speed when connected to my WRT54G
>>>v1.1.
>
>>Crappy design, but I'll take your word for it.
>
>May I humbly suggest you reconsider your opinion. Dialup external
>modems so the same thing. If you set the serial port data rate to
>19.2Kbits/sec, it will set the maximum connect speed to 14.4Kbits/sec.
>To get 56K speeds, you need 57Kbits/sec or faster SIO speeds.
Some, but not all.
>Admittedly, you can force the modem to connect at a higher speed, but
>that will just eventually overflow the modem buffer.
Error control (e.g., V.42) and TCP/IP actually handle that (congestion)
gracefully.
>The same thing applies to USB which is just a fancy name for a serial
>port with a weird connector. Max data rate for USB 1.1 is
>12Mbits/sec. It makes no sense for the wireless to go any faster as
>the driver buffer will overflow. So, they limit the speed to
>11Mbits/sec.
>
>I would call this "defensive design"
I would call this "dumb design" because it sacrifices speed in typical cases
(bursty data) in order to simplify worst case operation.
>as I really would not want to
>explain to customers why their USB wireless is eating packets due to
>an inability for the USB/SIO interface to keep up with the wireless
>data rate.
Again, TCP/IP will actually handle that (congestion) gracefully. Otherwise,
you could never interconnect a faster network to a slower network. See RFC
2001 and 2581.
--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>
Re: What are the requirements for a PC to accept a wireless card?
On Wed, 02 Nov 2005 12:22:11 GMT, John Navas
<spamfilter0@navasgroup.com> wrote:
>>May I humbly suggest you reconsider your opinion. Dialup external
>>modems so the same thing. If you set the serial port data rate to
>>19.2Kbits/sec, it will set the maximum connect speed to 14.4Kbits/sec.
>>To get 56K speeds, you need 57Kbits/sec or faster SIO speeds.
>Some, but not all.
Almost all that I've ever played with. Multitech, Supra, Hayes, USR,
etc. I used LOTS of these modems on Unix boxes for modem pools and
got to know their idiocyncracies and bad habits intimiately. Very old
photo of Cruzio with various Portmasters, USR modems, and lots of
cables: http://www.LearnByDestroying.com/crud/cruzio.htm
The only ones that would run with a faster SIO rate than connect rate
out of the box were the early Telebit T2000 modems and that was later
fixed with a firmware update.
>>Admittedly, you can force the modem to connect at a higher speed, but
>>that will just eventually overflow the modem buffer.
>Error control (e.g., V.42) and TCP/IP actually handle that (congestion)
>gracefully.
True. You could set it up to run that way if you wanted. If the
initial connect was at 33.6 and the line conditions sucked, the modem
would slow down. However, if you setup the SIO for 9600 baud, you
could never go faster than V.32 at 9600 unless you forced the connect
speed to some specific rate. It was also specifically warned against
in the manuals to always keep the SIO rate faster than the connect
speeds. It could be done, but that was NOT normal or desireable
operation.
The same applies to USB 1.1 versus 2.0 for wireless. You can run an
802.11g wireless devices with a USB 1.1 port, but that is NOT normal
or desireable operation.
>>The same thing applies to USB which is just a fancy name for a serial
>>port with a weird connector. Max data rate for USB 1.1 is
>>12Mbits/sec. It makes no sense for the wireless to go any faster as
>>the driver buffer will overflow. So, they limit the speed to
>>11Mbits/sec.
>>
>>I would call this "defensive design"
>I would call this "dumb design" because it sacrifices speed in typical cases
>(bursty data) in order to simplify worst case operation.
Running it that way assumes that:
1. There's a hardware flow control mechanism that works. It can't be
in the PC's driver code because the flow problem is between the
wireless bridge side and the USB interface. That puts it inside the
USB device. Got RAM? Got money? How many seconds of bursty traffic
do you want to buffer?
2. CTS/RTS flow control is functional to prevent excessive
repetitious packets when the PC drops incoming packets because the USB
1.1 interface can't handle them. This will drop thruput somewhat.
3. The TCP layer can handle it. A basic wireless rule-of-thumb is to
NEVER transmit a packet if you know it will be dropped. Resends are
very bad for thruput. The 802.11g MAC layer will also reduce the
connection speed or the TCP layer will delay sending packets to deal
with the excessive NACK's. Anything to eliminate retransmissions.
The high speed bursty traffic does have one advantage. It clears the
air faster than a slower connection speed. This gives other devices
on the system more air time to transmit. However, it won't take too
many retransmissions to ruin any benifits offered by this improvement.
In my never humble opinion, it's much easier to just back off the
wireless connect speed and let the sending wireless device control the
traffic. Given the requirements for running at faster wireless speeds
versus just rate limiting the wireless connection, methinks this was
an acceptable compromise.
>>as I really would not want to
>>explain to customers why their USB wireless is eating packets due to
>>an inability for the USB/SIO interface to keep up with the wireless
>>data rate.
>Again, TCP/IP will actually handle that (congestion) gracefully. Otherwise,
>you could never interconnect a faster network to a slower network. See RFC
>2001 and 2581.
Sure, I use this for bandwidth management all the time. So, what's
the difference in design? Letting the wireless run as fast as
possible and dropping packets at the USB interface will eventually
result in the TCP layer noticing and slowing down sending packets. The
result would be something like 54Mbit/sec connection speeds, but the
thruput controlled by the slowest device (USB 1.1 or 12Mbits/sec). You
get all the problems of running at higher speeds (short range, low
noise immunity, interference potential), with no benifit in thruput
over 802.11b (11Mbits/sec). Same issue as the modem analogy. You
could run it this way, but there's no real benifit.
Re: What are the requirements for a PC to accept a wireless card?
[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]
In <56rhm1hpadk5vpfo76h3jq6r4l92drq6bc@4ax.com> on Wed, 02 Nov 2005 09:14:07
-0800, Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>On Wed, 02 Nov 2005 12:22:11 GMT, John Navas
><spamfilter0@navasgroup.com> wrote:
>
>>>May I humbly suggest you reconsider your opinion. Dialup external
>>>modems so the same thing. If you set the serial port data rate to
>>>19.2Kbits/sec, it will set the maximum connect speed to 14.4Kbits/sec.
>>>To get 56K speeds, you need 57Kbits/sec or faster SIO speeds.
>
>>Some, but not all.
>
>Almost all that I've ever played with. Multitech, Supra, Hayes, USR,
>etc. I used LOTS of these modems on Unix boxes for modem pools and
>got to know their idiocyncracies and bad habits intimiately. Very old
>photo of Cruzio with various Portmasters, USR modems, and lots of
>cables:
> http://www.LearnByDestroying.com/crud/cruzio.htm
>The only ones that would run with a faster SIO rate than connect rate
>out of the box were the early Telebit T2000 modems and that was later
>fixed with a firmware update.
There were also USR, Hayes, and Multitech modems that would do that.
>>>The same thing applies to USB which is just a fancy name for a serial
>>>port with a weird connector. Max data rate for USB 1.1 is
>>>12Mbits/sec. It makes no sense for the wireless to go any faster as
>>>the driver buffer will overflow. So, they limit the speed to
>>>11Mbits/sec.
>>>
>>>I would call this "defensive design"
>
>>I would call this "dumb design" because it sacrifices speed in typical cases
>>(bursty data) in order to simplify worst case operation.
>
>Running it that way assumes that:
>1. There's a hardware flow control mechanism that works. It can't be
>in the PC's driver code because the flow problem is between the
>wireless bridge side and the USB interface. That puts it inside the
>USB device. Got RAM? Got money? How many seconds of bursty traffic
>do you want to buffer?
>2. CTS/RTS flow control is functional to prevent excessive
>repetitious packets when the PC drops incoming packets because the USB
>1.1 interface can't handle them. This will drop thruput somewhat.
Sending flow control must be supported by the driver and the hardware, because
they can't just assume that they can spew data as fast as USB 1.1 can go,
since the wireless link may well have shifted down to a lower speed. Setting
the max speed of the wireless to 11 Mbps doesn't solve the problem of a speed
shift down to (say) 1 Mbps. I'd be willing to bet that receive flow control
exists as well, since there can be cases when the host isn't able to receive
data.
>3. The TCP layer can handle it. A basic wireless rule-of-thumb is to
>NEVER transmit a packet if you know it will be dropped. Resends are
>very bad for thruput. The 802.11g MAC layer will also reduce the
>connection speed or the TCP layer will delay sending packets to deal
>with the excessive NACK's. Anything to eliminate retransmissions.
With all due respect, I think that's an exaggeration -- collisions are a fact
of life with 802.11, and a fairly significant percentage of lost packets is
normal. Regardless, TCP/IP will automatically throttle to whatever throughput
is possible.
>In my never humble opinion, it's much easier to just back off the
>wireless connect speed and let the sending wireless device control the
>traffic. Given the requirements for running at faster wireless speeds
>versus just rate limiting the wireless connection, methinks this was
>an acceptable compromise.
We'll just to disagree on this one.
>>Again, TCP/IP will actually handle that (congestion) gracefully. Otherwise,
>>you could never interconnect a faster network to a slower network. See RFC
>>2001 and 2581.
>
>Sure, I use this for bandwidth management all the time. So, what's
>the difference in design? Letting the wireless run as fast as
>possible and dropping packets at the USB interface will eventually
>result in the TCP layer noticing and slowing down sending packets.
It's not just a matter of packet loss.
>The
>result would be something like 54Mbit/sec connection speeds, but the
>thruput controlled by the slowest device (USB 1.1 or 12Mbits/sec). You
>get all the problems of running at higher speeds (short range, low
>noise immunity, interference potential), with no benifit in thruput
>over 802.11b (11Mbits/sec). Same issue as the modem analogy. You
>could run it this way, but there's no real benifit.
Again, I disagree. Letting each protocol optimize throughput will almost
certainly produce better results than crude throttling.
--
Best regards, HELP FOR CINGULAR GSM & SONY ERICSSON PHONES:
John Navas <http://navasgrp.home.att.net/#Cingular>
What are the requirements for a PC to accept a wireless card? 
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