Wi-Fi Speed
 

Hi.

I am wondering if the Wi-Fi connection for the N800 is 802.11G compatible? I am asking because the file transfer speed tops around 5-6 Mbps via Wi-Fi within the intranet. That's more like 802.11B.

I have a 100 Mbps wired router at home. File transfer between my server and desktop PC is usually fairly quick at around 75-80 Mbps. I don't expect the wireless connection to be nearly that fast, but 5-6 Mbps is way too slow for 802.11G.

Any idea?

TIA,
Dai

Re: Wi-Fi Speed
 

Try running the top command in xterm and watching to see if the transfer is consuming all of any given resource. I've seen it written that the tablet's hardware, probably cpu, can bottleneck the data transfer speed.

Re: Wi-Fi Speed
 

Unless the N800 is the ONLY device connected to the wi-fi AP then don't expect the full 802.11g throughput.
You also have to take into account data moving to/from whatever media you're using as well.

Re: Wi-Fi Speed
 

Thanks for the tips. I am now converting another mp4 file to AVI for transfer. I will check the "top" output when I transfer this file over the my N800.

Thanks for the input, too. Yes, the N800 is the only device currently connected to my wireless access point. (I have a Wii downstairs, but it's off now.) It can be the SDHC card I'm using. It is a SanDisk 4GB SDHC card. A quick googling shows the data tansfer speed to be 2+ MB/sec. It's still much faster than 5-6 Mbps, but this and the CPU bottleneck together may be the culprit.

I'll keep you guys updated.

Dai

Re: Wi-Fi Speed
 

I ran "top" while transferring this 500+ MB file from my desktop to the N800 (via ssh). The ssh process took about 40-45% of the CPU time, with scp taking up about 5 percent, meaning it's roughly 45-50 percent. How should I interpret the result? Does it mean the CPU isn't the bottleneck?

Re: Wi-Fi Speed
 

Both the 770 and N800 are 11b/11g compatible, however they both top out on WiFi transfers at about 600Kbytes/sec.

Re: Wi-Fi Speed
 

I think the bottleneck was mentioned to be the speed of (SPI) bus between OMAP and Wi-fi chip. You can't expect real G speeds with current Nokia tablets (practical maximum tends to be one half of 54Mbits i.e. something like 2.5MB/s) but still having G networking is very useful for battery life. With G speeds less time is spent on actual radio transmitting so the power is consumed for shorter time.

Re: Wi-Fi Speed
 

It makes me wonder what the value of "802.11G compatibility" is when the transfer speed tops out around 600-650 KB/s (roughly 5 Mbps)? That's about the realistic speed of 802.11B. :(

Re: Wi-Fi Speed
 

The "value" is that it won't cause your 802.11g network to crap itself when it sees an 802.11b node. Thus, your N800 won't cause other devices on the same network (e.g., your laptop) to suffer a network performance hit when it attaches to the access point.

(When an 802.11b node associates with an access point, the access point enables various features to ensure the b and g nodes can interoperate, such as CTS/RTS for every frame. So your g nodes take a huge performance hit the moment a single b node associates.)

Also, as I believe someone else already mentioned, in g mode, the radio takes less time to send a frame, therefor the device uses less overall power since the time spent powering the transmit antenna is reduced. This extends your battery life. (At least for devices like the N800 that never have to worry about sustaining full bandwidth wireless transfers...)

Re: Wi-Fi Speed
 

Aah, I see. I apparently did not realize that the "G" designation was not just about speed, and that access points worked like you explained. So when an access point services both B and G devices, then the G devices suffer a performance hit... I'll keep that in mind.

Thanks!
Dai

Re: Wi-Fi Speed
 

While there are technical advantages to supporting g, as already mentioned, I suspect the real reason Nokia included b/g, despite the inability to realize full wireless speeds, probably boils down to two things:

1) Marketing: "b/g" is a checkbox/buzzword/whatever you want to call it. Saying you only support "b" would look bad.

2) I suspect that the OEM wireless chipset manufacturers have all switched to b/g chips, so getting a b-only chipset is now probably not cost effective, if even possible.

These two reasons combined are also probably why all the new cellphones that have WiFi are also b/g devices, even though they have even less capability to saturate a wireless link than the tablet has.