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View Full Version : Tom's Networking: WiFi PDAs' Dirty Little Secret


Pat Logsdon
05-21-2004, 12:00 AM
<div class='os_post_top_link'><a href='http://www.tomsnetworking.com/Sections-article82-page1.php' target='_blank'>http://www.tomsnetworking.com/Secti...cle82-page1.php</a><br /><br /></div>"I first stumbled upon low WiFi throughput in PDAs last fall, when testing SanDisk's SD WiFi card in an HP H2210 iPAQ running Pocket PC 2003. The tests for that review yielded best case average throughput of only about <b>350kbps</b>. Both SanDisk and SyChip (who makes the card for SanDisk) said that the main factors in the low speed were software and hardware issues in the H2210's SDIO interface. What I found after a little digging seems to confirm the SanDisk / SyChip story, though there is some conflicting info. The SD interface on Intel's PXA255 XScale processor used in the H2210 (and in many current PocketPCs) is actually an <b>MMC interface</b> capable of supporting only the 1 bit transfer mode at a maximium 20MHz clock rate(1).<br /><br /><img src="http://www.pocketpcthoughts.com/images/web/2003/logsdon_20040520_tomswifi.jpg" /><br /><br />Even though it's not an SD interface per se...the MMC 1 bit mode is theoretically capable of supporting a 2.5MB/s (20Mbps) transfer rate. This should be plenty fast to support 802.11b's full 11Mbps raw data rate, as long as software overhead isn't a significant factor. But my experience with some of the PXA255-based PDAs that I tested yielded WLAN transfer rates far below what you'd expect for such relatively fast raw bus speeds. So it would appear that there are some software or other issues at play that limit wireless throughput."<br /><br />As always, Tom's has done an excellent job of dissection and testing. The tests in this article are done with an HP 2210 with a SanDisk SD WiFi card, a Dell Axim X5 Advanced with a SanDisk WiFi card, an Asus A716, and a Palm Tungsten C. All of these devices use the 400MHz Intel PXA255 processor (except the Axim, which uses the PXA263 chip), but they all use different methods of getting the signal to the CPU. The device with the highest throughput had a speed almost <b>three times faster</b> than the next closest device. To find out which device "won", you'll need to read the article. <br />Hint: :mecry:

mscdex
05-21-2004, 12:13 AM
So this article only refers to using the SD Wireless card right? I'd get normal speeds if I used a CF wireless card, correct? Or no?

orol
05-21-2004, 12:19 AM
wow, tungsten C achieved 3 times better results then the best PPC.
actually on my UX50 I get around 250 KB/sec when using VFSFTP+

btw UX50 uses SyChip wifi chip used in the SD card :-) it's the same one :-)

Janak Parekh
05-21-2004, 12:22 AM
You know, I was reading this and wondered if PIE could also be part of the problem. Has anyone else FTPed large files with a different program?

Nevertheless, I hope OEMs start to realize that as the rest of the device gets faster, this is something they need to optimize.

--janak

c38b2
05-21-2004, 12:24 AM
This just goes to show that when Palm does something, they do it right.

Janak Parekh
05-21-2004, 12:24 AM
So this article only refers to using the SD Wireless card right? I'd get normal speeds if I used a CF wireless card, correct? Or no?
CF may be faster, but it's not clear how it'll compare to the devices reviewed -- one of the was an Asus A716 with built-in WiFi.

This just goes to show that when Palm does something, they do it right.
Generic assertions like this aren't really productive. :? I hardly think things like the PalmOS category/memo pad limits were "done right" to start with. But before we go any further: let's avoid a generic PalmOS-Pocket PC flame war in here.

--janak

c38b2
05-21-2004, 12:29 AM
This just goes to show that when Palm does something, they do it right.
Generic assertions like this aren't really productive. :? I hardly think things like the PalmOS category/memo pad limits were "done right" to start with. But before we go any further: let's avoid a generic PalmOS-Pocket PC flame war in here
OK, let's keep it specific to the thread.

This just goes to show that when Palm does WiFi, they do it right.

Blue Zero
05-21-2004, 12:36 AM
Oh man Hp took a big hit on that chart.. :lol:

Janak Parekh
05-21-2004, 12:36 AM
This just goes to show that when Palm does WiFi, they do it right.
OK, I'll allow that -- maybe. :lol: Now, what I want to know is why they haven't released a WiFi device since... I've heard that the T|C's WiFi power management is second to none, and that the amount of useable WiFi surfing time trumps any other device out there, including both other Palm and Pocket PC OEMs.

--janak

R K
05-21-2004, 12:42 AM
OK, let's keep it specific to the thread.

This just goes to show that when Palm does WiFi, they do it right.

I don't want to disagree with you but I'm not necessarily agreeing with you either.
Though the article goes in depth to some degree, this is not anywhere near a full comparison between Palm OS and Pocket PC.

One Palm OS device was used, and three Pocket PCs were used.
The Tungsten could possibly just be the fastest Palm OS device for WiFi. Who knows whether the other PalmOS devices are on the same level with Pocket PC?
For that matter, who knows whether other Pocket PCs would be faster? Maybe the HP iPAQ H5555, the Dell Axim X3i, or Toshiba e800 would have surpassed the Tungsten if they were used in the article.

Sorry c38b2, but all that was said to come to this point. Phrases like...
This just goes to show that when Palm does WiFi, they do it right.

...at this point are just acting as flame bait.

c38b2
05-21-2004, 12:50 AM
OK, let's keep it specific to the thread.

This just goes to show that when Palm does WiFi, they do it right.

I don't want to disagree with you but I'm not necessarily agreeing with you either.
Though the article goes in depth to some degree, this is not anywhere near a full comparison between Palm OS and Pocket PC.

One Palm OS device was used, and three Pocket PCs were used.
The Tungsten could possibly just be the fastest Palm OS device for WiFi. Who knows whether the other PalmOS devices are on the same level with Pocket PC?
This is part of the Palm mentality - if you need WiFi, get a device capable of delivering it well, hence the T|C. You think it's coincidence that there are no SD WiFi cards for Palm OS?

Sorry c38b2, but all that was said to come to this point. Phrases like...
This just goes to show that when Palm does WiFi, they do it right.

...at this point are just acting as flame bait.
Yes they are. I never miss an opportunity to stick it to PPC. At this point you should wonder why you are accepting subpar performance, because I have a feeling that the WiFi isn't the only performance gap between Palm and PPC.

Gremmie
05-21-2004, 12:55 AM
This should be plenty fast to support 802.11b's full 11Mbps raw data rate, as long as software overhead isn't a significant factor.

Isn't it half-duplex, so a benchmark would only show 5.5 max?

R K
05-21-2004, 01:16 AM
Isn't it half-duplex, so a benchmark would only show 5.5 max?

It is fairly well-known that 802.11b WiFi speeds don't necessarily meet their 11Mbps rating, but I think the point of the article was that the PDAs tested weren't meeting anything close to even 5Mbps.

It's a pretty interesting article, and I think it really brings back the whole 1 bit vs 4 bit SDIO interface dilemna that was a big rage a couple years ago.
It's also pretty interesting to see how manufacturers are getting around the SDIO dilemna by using other connections to interface to the WiFi chip. I know that a few iPAQs use a USB type interface for their WiFi implementations.

Zack Mahdavi
05-21-2004, 01:50 AM
Now, what I want to know is why they haven't released a WiFi device since... I've heard that the T|C's WiFi power management is second to none, and that the amount of useable WiFi surfing time trumps any other device out there, including both other Palm and Pocket PC OEMs.

--janak

That's what I've been wondering since December when I was looking for a new PDA. I had been a loyal Palm user and was really wanting to stick with the OS. I read so many good things about the Tungsten C's implementation of WiFi, and I was thoroughly impressed. However, I wanted WiFi and Bluetooth in a Tungsten T3 style.

Nothing like that available from Palm. In fact, there are ZERO devices from Palm with both Bluetooth and WiFi. Sure, Sony has the UX series, but I don't want to pay $600 for a PDA.

Anyway, that's why I bought an iPaq.

Has anyone else FTPed large files with a different program?

I FTP large files (like movies and music) from my Mac to my Pocket PC using Resco File Explorer all the time. The speed seems fast enough, although I've never bothered to time it.

that_kid
05-21-2004, 02:41 AM
So this article only refers to using the SD Wireless card right? I'd get normal speeds if I used a CF wireless card, correct? Or no?

I used resco's ftp program to ftp some things over wifi and throughput was good. Only thing is that I was doing this at a school so i'm not sure how much bandwidth I was allowed.

I've also noticed that my 5555 gets much much better throughput than my 4150 and 4350.

Gremmie
05-21-2004, 02:48 AM
It's also pretty interesting to see how manufacturers are getting around the SDIO dilemna by using other connections to interface to the WiFi chip. I know that a few iPAQs use a USB type interface for their WiFi implementations.

I also remember the battle. If I remember correctly, the 3900 used the 4-bit while the 3800 was introduced with a 1-bit. I remember opening was SLOW. I always assumed they kept the 4-bit past the 39xx.

R K
05-21-2004, 03:08 AM
I've also noticed that my 5555 gets much much better throughput than my 4150 and 4350.

I don't know what your settings are, but I think you can get better throughput results with the iPAQ H4155/H4355 if you turn off Power Saving Mode.

mcsouth
05-21-2004, 03:18 AM
Interesting article that, in my mind anyways, raises more questions than it answers. I thought I understood that these SDIO slots were being certified as meeting some SD org's spec - how can that be true if they only have a 1 bit interface, v. the supposed 4 bit SD standard? That was supposedly one of the big differences between MMC and SD, but this article seems to bring this issue into question somewhat. Reminds me of some of the conversations surrounding the fact that the Casio EM-500's supposedly had a 9 pin interface (SD std v. 7pin for MMC), but were billed as MMC only - there was a lot of speculation that a driver update could turn the slot into an SD-compliant slot, if I remember correctly. Now, this article would seem to question the SDIO interface - in the end, I wonder just what exactly is an MMC-spec slot v. SD-spec slot........

I end up feeling like this is another example of unclear specs and standards being bantered about, and in the end, the real story will come out well after the damage with the consuming public has happened. Who can you trust to tell the truth......?

that_kid
05-21-2004, 03:20 AM
I don't know what your settings are, but I think you can get better throughput results with the iPAQ H4155/H4355 if you turn off Power Saving Mode.

Power savings mode was off on all the tests(actually I always leave it off). I was able to transfer more files in a shorter time with my 5555 than my 4350 or 4150.

WyattEarp
05-21-2004, 07:04 AM
This just goes to show that when Palm does WiFi, they do it right.
OK, I'll allow that -- maybe. :lol: Now, what I want to know is why they haven't released a WiFi device since... I've heard that the T|C's WiFi power management is second to none, and that the amount of useable WiFi surfing time trumps any other device out there, including both other Palm and Pocket PC OEMs.

--janak

Why make another device when no one else comes close to the first one. I prefer the longer turn around time since real progress can be made and not inundated by cardboard cutouts.




I don't know what your settings are, but I think you can get better throughput results with the iPAQ H4155/H4355 if you turn off Power Saving Mode.

Power savings mode was off on all the tests(actually I always leave it off). I was able to transfer more files in a shorter time with my 5555 than my 4350 or 4150.

I'd have to agree the h5555 transfers files very quickly; even more so with that last ROM update.

ricksfiona
05-21-2004, 08:43 AM
My iPAQ 5550 has pretty fast WiFi performance in my opinion. I can download a 100 messages in seconds. Now for an e-mail client that can handle HTML...

Jonathan1
05-21-2004, 12:57 PM
My iPAQ 5550 has pretty fast WiFi performance in my opinion. I can download a 100 messages in seconds. Now for an e-mail client that can handle HTML...

http://www.pocketinformant.com/p_webismail.php

mattp
05-21-2004, 01:28 PM
Disclaimer: I don't really know a whole lot about how PIE isn't optimized or anything like that and consider myself lucky that I was able to hit my wi-fi router with my A716 without much troubleshooting (the A716 pretty much figured out the settings itself, fortunately).

FWIW, I ran a speed test using what is pretty much a stock A716 and the result was 320 kb/sec.

Speed tests on my primary PC, 2.8G Athlon, 512 RAM, "hard wired" to the router typically achieves speeds approaching and occasionally surpassing 3 mb/sec. I haven't run speed tests on the other PC on the network, which uses a USB wi-fi connection, it's also pretty fast but noticeably slower than the primary (I don't recall its hardware specs, but they're way less than the primary).

I will add this:

-the A716's signal strength and link quality are way higher than the USB-connected computer sitting side-by-side. In fact, I get very good signal strength at the end of my driveway, which is about 100 feet and two brick walls from my router.

-As stated a few posts above, my e-mail downloads in seconds including attachments.

-I reserve any "heavy" downloading for the PC.

-Why do you have a high-speed connection in the first place? Sure, web pages download faster, but surfing isn't THAT bad on a phone line connection. You have it because you can download e-mail attachments way faster, which is important and the PPC does this well. Additionally, you have it because of the bells and whistles like streaming media.

I was blown away with WMP 9 on the PPC -- put that in your Kinoma and smoke it.

Pat Logsdon
05-21-2004, 04:13 PM
This is part of the Palm mentality - if you need WiFi, get a device capable of delivering it well, hence the T|C. You think it's coincidence that there are no SD WiFi cards for Palm OS?
You might want to read this article. (http://www.theregister.co.uk/2003/12/11/sandisk_blames_palmsource_pda_vendors/)

Len M.
05-21-2004, 05:34 PM
When testing CF and SD memory cards, we've seen maximum write rates of roughly 1.2 MB/second for the SD card slot (on a h2215), and 1.6 MB on the CF card (h5100-series using dual PCMCIA expansion pack).

It's likely that's as fast as any hardware will transfer data via the slots and expansion packs on current iPAQs.


Len Moskowitz
Core Sound
www.core-sound.com

mv
05-21-2004, 05:44 PM
[quote="R K"][quote=c38b2]OK, let's keep it specific to the thread.

This just goes to show that when Palm does WiFi, they do it right.

This is part of the Palm mentality - if you need WiFi, get a device capable of delivering it well, hence the T|C. You think it's coincidence that there are no SD WiFi cards for Palm OS?
[quote]


Itīs no coincidence. They just have not been able to write the proper drivers. Sandisk has been trying for a long time, and delayed the project over and over again.

Janak Parekh
05-21-2004, 10:48 PM
Why make another device when no one else comes close to the first one. I prefer the longer turn around time since real progress can be made and not inundated by cardboard cutouts.
Because the T|C is long in the tooth (IMHO) and could benefit from concrete improvements? How about Bluetooth or 320x480 support?

--janak

tw
05-24-2004, 06:15 PM
I also remember the battle. If I remember correctly, the 3900 used the 4-bit while the 3800 was introduced with a 1-bit. I remember opening was SLOW. I always assumed they kept the 4-bit past the 39xx.

Yes and that is true while the author of the Tom's Hardware article got it wrong. He just assumed that the iPAQ 2210 uses the XScale's built-in MMC controller for the SD slot and therefore would only support only 1-bit mode.

But if he had used Google before posting his article he would have found that the iPAQ 2210 has a separate ASIC chip, a Samsung HAMCOP chip, which among other things provides the SD/SDIO controller supporting 4-bit mode for the 2210. Details about the 2210 hardware architecure can be found at http://www.handhelds.org

Also no PPC with built-in Wi-Fi uses the SDIO bus for connecting it but other means (CF, internal USB or GPIO-Pins, etc.) So you can pretty much ignore his conclusions about Wi-Fi and PPC.

Menneisyys
01-25-2005, 01:49 PM
So this article only refers to using the SD Wireless card right? I'd get normal speeds if I used a CF wireless card, correct? Or no?
CF may be faster, but it's not clear how it'll compare to the devices reviewed -- one of the was an Asus A716 with built-in WiFi.

CF is MUCH faster. See e.g. http://www.pocketpcthoughts.com/forums/viewtopic.php?t=35119 .

Menneisyys
01-25-2005, 01:51 PM
When testing CF and SD memory cards, we've seen maximum write rates of roughly 1.2 MB/second for the SD card slot (on a h2215), and 1.6 MB on the CF card (h5100-series using dual PCMCIA expansion pack).

It's likely that's as fast as any hardware will transfer data via the slots and expansion packs on current iPAQs.


Len Moskowitz
Core Sound
www.core-sound.com

But not the SanDisk (or, for that matter, any current SD-based Wi-Fi cards). See e.g. http://www.pocketpcthoughts.com/forums/viewtopic.php?t=36254

Len M.
01-25-2005, 03:00 PM
Menneisyys wrote:

But not the SanDisk (or, for that matter, any current SD-based Wi-Fi cards). See e.g. http://www.pocketpcthoughts.com/forums/viewtopic.php?t=36254

What it seems you're saying is that SD WiFi cards are very slow (30 KB/s).
That doesn't say anything at all about SD flash memory or the speed of the SDIO interface itself.

We've seen maximum write rates to the Dell X50v's SDIO card slot of almost 2 MB/s. The HP h2215's maximum rate is around 1.3 MB/s. See the benchmark results here:

http://www.core-sound.com/CF-and-SD-mass-storage-comparison.html

This would point to some other source for WiFi crummy performance on PDAs.


Len Moskowitz
Core Sound
www.core-sound.com
Home of PDAudio

Menneisyys
01-25-2005, 03:05 PM
Menneisyys wrote:

But not the SanDisk (or, for that matter, any current SD-based Wi-Fi cards). See e.g. http://www.pocketpcthoughts.com/forums/viewtopic.php?t=36254

What it seems you're saying is that SD WiFi cards are very slow (30 KB/s).
That doesn't say anything at all about SD flash memory or the speed of the SDIO interface itself.

We've seen maximum write rates to the Dell X50v's SDIO card slot of almost 2 MB/s. The HP h2215's maximum rate is around 1.3 MB/s. See the benchmark results here:

http://www.core-sound.com/CF-and-SD-mass-storage-comparison.html


Yeah, I only wanted to say that the two throughput values are completely unrelated - I mean while SD memory cards are of almost the same speed in current PDA's than CF's, the same doesn't apply to current Wi-Fi SD cards.