Wireless G CF cards?

Tommyboyprime · 08-23-03, 07:23 AM

:exc: I just received email replies to queries I made to Liksys, D-link and Socket. They all told me the same thing: they have 802.11g CF cards in the developement stage and expect them out November/December. Can't wait.

Oblox · 08-25-03, 05:01 AM

If you transfer alot of files back and forth i can see the reason for your excitement but for normal web browsing/email/instant messaging there would be no difference in the speed between a g and b wireless card.

Still its good for those that havent got a wireless CF yet.

deftech · 08-25-03, 10:31 AM

Weird that they're actually developing them. The bottleneck will be the CF slot.....it won't be able to handle full 802.11g speeds in the first place.

humba · 08-25-03, 11:16 AM

deftech: I've experienced similar things, but on the other hand I don't know the actual physical limitations on a CF slot and what this implies for data rates. However, I know that my USB2 CF reader is able to transfer data significantly faster than the CF "reader" on my Axim, which leads me to believe that CF slots are able to handle faster datarates than they currently do on PDAs. For instance, there are CF memory card that can do about 4-5MB/s in reading, or 40MBit at best, which is considerably beyond what 802.11b can do, so even if a CF slot won't be able to handle 54MBit/s, considering that the actual data rate will be considerably lower due to physical overhead and MAC overhead, the CF slot should be able to offer the full speed a 802.11g connection can offer.

deftech · 08-25-03, 11:19 AM

I'm not sure of the exact specs right now, nor do I have time at this moment to look for them. All I'm saying is that I'll be surprised if there is a big difference for PDAs.....much less having it hit 40Mb/s. Guess we'll wait and see though. :)

humba · 08-25-03, 11:35 AM

Considering the performance I have experienced on my Axim I have to agree that it's unlikely we'll see much fo a performance impact. But that only applies to the Axim. Other PDAs might have faster CF slots. In fact, it didn't took long to find the official CF site: http://www.compactflash.org
I didn't bother to register to download the specs, but the frontpage already mentions that CF 1.x defines a 8 MB/s data transfer rate on the interface, or in other words, 64 MBit/s, which is more than enough. In other words, 802.11g CF cards make sense, but you can only fully use them if your PDA is able to serve the CF slot at the full speed defined in the standard. Plus, since CF is based on PC Card, it's not too much work to adapt a PC Card adapter to CF, the main challenge is size. The components used are largely the same (and that's the main reason why PDA WLAN cards use that much power... my TM card increases the power drain from 0.15A to 0.30A. Once real low power components are used, like they are for Bluetooth, WLAN cards will no longer be the power hogs they are today).

I also see a more practical use: New cards will more likely be equipped with WPA, and operating a WPA encrypted, G-only network is a lot safer than your usual 802.11b, WEP encrypted network (in fact, my PDA is the only reason preventing my WLAN to operate in g-only, WPA mode). So, if a g card with WPA support is released at the end of the year, I'm in for an upgrade, even though I might not get much of a performance improvement.

08-26-03, 04:46 AM

A pcmcia 11g card can get around 22mbps thruput

deftech · 08-26-03, 09:15 AM

Quote:

Originally posted by Planet-II
A pcmcia 11g card can get around 22mbps thruput

Actually, I think you are just slightly mistaken on that spec.

The Enhanced 802.11b that some companies offer are the cards that have a max throughput of around 22Mbps.

The 802.11g cards actually do have a max throughput of around 54Mbps.

Here is a link to a 3Com 802.11g PCMCIA card specs: Click Here

humba · 08-26-03, 09:39 AM

@deftech: I think he was refering to the "real world" speed 802.11g equipment can achieve. I thought it was supposed to be around 24mbit, but if anybody has the specs, he can calculate the exact value for the best case. I'd do it, but 802.11 standards are only published free of charge 6 months after their ratification and currently I don't need the g specs so I'm not willing to shell out any money for them.

08-26-03, 08:25 PM

Yes real world thruput, not specs http://www.tomshardware.com/network/...belkin-07.html

pananza · 08-28-03, 02:16 AM

Another reason to get 802.11g cards is that in a mixed environmet with both 802.11b and 802.11g card the performance will decrease for the g users.

08-28-03, 02:22 AM

Quote:

Originally posted by pananza
Another reason to get 802.11g cards is that in a mixed environmet with both 802.11b and 802.11g card the performance will decrease for the g users.

yes, true.

HeyBigBoy · 08-28-03, 05:45 AM

It's not only throughput. The way I understand it. The G protocol will have enhanced security as well.

Tommyboyprime · 08-28-03, 06:33 AM

According to Lou Dolinar , a columnist for LI Newsday, whohas actually tested these things, not just heard about them fromothers: tHROUGHPUT ON 802.11b IS ABOUT 5-6m AT 30 METERS,
WITH 802.11g at the same distance it's about 22-24 MB , and that's with no intervening walls, good location of antenna etc
PS excuse my spelling. It's 0 dark :30 im the AM and I just got up.

humba · 08-28-03, 07:46 AM

Quote:

The way I understand it. The G protocol will have enhanced security as well.

is not true unless you consider a g-only environment enhanced security. WPA and future protection mechanisms (802.11i) are independent of 802.11(a/b/g).
However, the throughput question is an interesting one. I have (as part of my research for my master's thesis) read some scientific evaluations of 802.11(a/b) throughput under various conditions. As you might know, 802.11b has 4 different speed modes, and the lower your bitrate, the higher your range. Now, using a > 11mbit OFD modulation as in 802.11a/g, you can achieve lower bit error rates at the same distance from the AP as when using 802.11's CCK modulation. So, while you won't get anywhere near 54mbit due to the overhead of PHY and MAC layer (which is considerable), you can get further from the AP at a given speed (or conversely get a higher speed at the same range).

Either way, I hope that manufacturers won't simply adapt the PC Card design but really do something to cut down the power usage. Currently, CF WLAN Cards are real power hogs, activating the WLAN card on my Axim increases the power drain by a factor of two and while the standard isn't very energy efficient, there is still potential for improvement on the hardware side.