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Slow local WiFi transfer rate

D

dissolve

macrumors 6502a
Original poster
Aug 23, 2009
546
0
I'm running a 2010 MP and have recently upgraded to a Cisco E3200 802.11n router. Doing an Option-click on the Airport menubar icon shows a Transmit Rate of 54 consistently; sometimes lower briefly. I have a MBA sitting right next to the MP reporting a Transmit Rate of 108 (still slower than expected on an N-network). Doing a wireless transfer between machines maintains a steady 3.4 MBps (~27 Mbps) throughout.

I've tried multiple configurations of wireless security, channel frequencies, and bonding. None can get the MP above a rate of 54 Mbps. System Profiler reports 300 Mbps link speed, so it's recognizing that it's on an N network (I know the real speed is much lower, but it should be faster than I'm getting). Any suggestions? Thank you very much.

EDIT: sorry, I should have stated that it's a dual-band router and neither 2.4 GHz or 5 GHz improve matters much.
 
Plug in an ethernet cable to the Mac Pro and transfer only to the higher bandwidth "air". What are your numbers then? It is possible your router is not so good. It is possible the Mac Pro card is not so good. Also shut off the 2.4GHz spectrum if you can and only try 5GHz. Maybe the dual-ness is confused as 54 is "g" and above is "n". As stated link numbers and real numbers rarely are the same.
 
derbothaus said:
Plug in an ethernet cable to the Mac Pro and transfer only to the higher bandwidth "air". What are your numbers then? It is possible your router is not so good. It is possible the Mac Pro card is not so good. Also shut off the 2.4GHz spectrum if you can and only try 5GHz. Maybe the dual-ness is confused as 54 is "g" and above is "n". As stated link numbers and real numbers rarely are the same.
Click to expand...

Thanks for the input. Due to the setup I have, I can't immediately hook the MP up to the router, but I'll try that when possible. I noticed today that the MBA gets a ~270 Mbps transmit rate when within about 5 feet from the router. The MP is a few walls away. On the 2.4GHz network, the MP gets ~130 transmit rate. I've read that the 5GHz network is more fragile when it comes to boundaries/walls in the way, but I'm still surprised that the MBA can get twice the transmit rate when placed next to the MP.
 
The Mac Pro has an older card in it. Even if its a 2010 Mac Pro, the card has been the same since 2007. The fastest speeds you'll get with it are 270Mbps. Another thing, the Air's WiFi has much better antenna than the Mac Pro. There have been many complaints about the Mac Pro's poor WiFi/Bluetooth reception over the years.
 
Intell said:
The Mac Pro has an older card in it. Even if its a 2010 Mac Pro, the card has been the same since 2007. The fastest speeds you'll get with it are 270Mbps. Another thing, the Air's WiFi has much better antenna than the Mac Pro. There have been many complaints about the Mac Pro's poor WiFi/Bluetooth reception over the years.
Click to expand...

That's too bad. If that's the cause, I suppose it's just a coincidence that the transmit rate is sitting at 54 Mbps? If it truly were transmitting at 802.11g speeds, it'd likely be lower than that anyways, right? Thanks both for the insight and help.
 
Because its at 54 and rather far from the router, I'd say its on N. But because its a far, it can only muster up that speed.
 
Any suggestions for a good PCIe wifi card? In general, are they all supported by OS X without additional drivers or software?
 
Due to the 802.11 protocols and RF in general you will not obtain true data transfer speeds as indicated with the wireless link connect speed. Really only a fraction of the link speed! And:

  • 802.11n will only obtain full speed if it can use both 2.4 GHz (b/g) and the 5 Ghz (a) radios. Your CISCO router does support dual radios. Make sure it is setup correctly
  • 802.11n uses multiple channels to achieve speed.
  • 802.11n will gearshift down to 54Mb link speed if 802.11g is in use
  • 802.11n will gearshift down to 54Mb link speed if security is set to WEP or WPA/TKIP. Only WPA2 AES gets you real n link speed. But at a price. AES takes a bunch of WiFi processor time to encrypt and de-encrypt
 
dansmac said:
  • 802.11n will only obtain full speed if it can use both 2.4 GHz (b/g) and the 5 Ghz (a) radios. Your CISCO router does support dual radios. Make sure it is setup correctly
  • 802.11n uses multiple channels to achieve speed.
  • 802.11n will gearshift down to 54Mb link speed if 802.11g is in use
  • 802.11n will gearshift down to 54Mb link speed if security is set to WEP or WPA/TKIP. Only WPA2 AES gets you real n link speed. But at a price. AES takes a bunch of WiFi processor time to encrypt and de-encrypt
Click to expand...

N can get its full speed with one radio and one frequency.

N does not always use multiple channels to achieve maximum speed. In a properly setup 20Mhz, one channel, network it can achieve N speeds.

In a network that is being broadcasted by a 2x2 or greater access point, the wireless network will not drop to G speeds when a G or B device connects. Apple's 3rd generation Airport Extreme and newer do not suffer from this because they use a 2x2 or greater setup.

AES encryption is not dependent on a CPU's processing power, nor does it use the CPU's power to encrypt or decrypt data. AES, like all other forms of wireless encryption, uses the WiFi card's on-board WiFi chip to process the data.
 
I had the same issue exactly, right down to watching my MBA work flawlessly while the Pro next to it lagged. I checked forums all over the net, spent a few hours on the phone with Apple, and installed a couple of Airport Express as extenders, all to no avail.

Forget 5 GHz trying to go through a couple of walls. It won't happen. The other issue is the card/antenna inside the Pro. It sucks, plain and simple. Try 2.4 GHz via a Premiertek PL-18N USB wireless adapter (RaLink). It sort of looks like a futuristic TV rabbit ear antenna. I went from minimal signal strength and speeds, when I could connect at all, to picking up over a dozen routers near me, with my own at 100 percent and triple digit speeds. Less than forty bucks spent at Newegg solved the problem for me.
 
Intell said:
N can get its full speed with one radio and one frequency.

N does not always use multiple channels to achieve maximum speed. In a properly setup 20Mhz, one channel, network it can achieve N speeds.

In a network that is being broadcasted by a 2x2 or greater access point, the wireless network will not drop to G speeds when a G or B device connects. Apple's 3rd generation Airport Extreme and newer do not suffer from this because they use a 2x2 or greater setup.

AES encryption is not dependent on a CPU's processing power, nor does it use the CPU's power to encrypt or decrypt data. AES, like all other forms of wireless encryption, uses the WiFi card's on-board WiFi chip to process the data.
Click to expand...

I hear ya. … And, many suppliers of wireless systems, including CISCO, push the 802.11 standards to achieve crazy results. However Apple does not. So by “by the book” n will get you great results only when configured correctly

Assuming 2 antennas (2x2) in the 2.4Ghz space, n has an option to pair-up channels to occupy twice the spectrum bandwidth and double the speed because of that. That's 2/3 of the whole 2.4GHz band. A bandwidth hog. Thus, most won't bond a pair (including most Apple configurations) if any nearby systems are g and in use.

Two antennas at each end (2X2) double the throughput, three antennas at each end triple it, and four quadruple it. 2X2 permits two simultaneous 72.2 Mbps streams, yielding a total throughput of 144.4 Mbs. The maximum allowed with both g and a is 4 antennas yielding a total throughput of 288.9 Mbps using the 20 MHz channel bandwidth. Again some have found ways to claim up to 600 Mbps with 40 MHz channel bandwidth. The latest Apple Airport Extreme does this and on my setup I achieve a consistent 400 Mbps link speed and reported on my Dell laptops and Denon theater system.

….yep….the AES encryption is handled in the WiFi chipset as mentioned in my first post (on newer hardware)…but it does take valuable time and although you can achieve super fast link speeds the actual data throughput is affected with all kinds of wireless overhead including how fast it can disassemble the data packets, de-encrypt, check for link and data errors, retry if needed, and so on.
 
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