In light on the recent feedbacks regarding the slow network speed reported when using our Wireless N Dongle, I would like to advise users on the actual throughput of a 802.11n network.

Wireless Networking has all the complexity of traditional wired networking with the additional complications of signal strength issues such as radio interference and barriers, as well as additional overhead related to wireless transmission that commonly halves its real world throughput over the theoretical raw data rate.

As such,
- 802.11b has a theoretical speed maximum of 11 Mbits/sec with a typical transfer rate of around 4.5 Mbits/sec (0.5 MB/sec) with an ideal signal.
- 802.11g has a theoretical speed maximum of 54 Mbits/sec, with a typical transfer rate of around 23 Mbits/sec (2.5 MB/sec) with an ideal signal.
- 802.11n has a theoretical speed maximum of 300 Mbits/sec, with a typical transfer rate of around 74 Mbits/sec (9.25 MB/sec) with an ideal signal.

Fast Ethernet has a theoretical speed of 100 Mbits/sec (12 MB/sec)
Gigabit Ethernet has a theoretical speed of 1000 Mbits/sec (120 MB/sec)

Users can also read up on more information via wiki at this location,
http://en.wikipedia.org/wiki/IEEE_802.11

Please note that the max net bit brate of 600Mbits/sec is based on the finalised 802.11n standards with a throughput of 144Mbits/sec.

Back to our wireless N dongle specifications, it supports MIMO (Multi-Input Multi-Output) technology with 1 Transmit and 2 Receive, which translates to a maximum of 150Mbits/sec transmit and 300Mbits/sec receive in theory.

Now with reference to the above transfer rate for 802.11n (300Mbits/sec), a typical transfer rate of around 74Mbits/sec (9.25MB/sec) with an ideal signal, our wireless N dongle should be able to have a transfer rate of approximately 40Mbits/sec which is around 5MB/sec (1Mbit/sec = 0.125MB/sec)
Reference: http://en.wikipedia.org/wiki/Megabit_per_second#Megabit_per_second

Please note that you will not get a wireless N transfer rates if you connect to a wireless G router or neither if you connect to a wireless N router with WEP or TKIP security.

5 Ways To Fix Slow 802.11n Speed
http://www.smallnetbuilder.com/content/view/30664/228/
1. Use the Correct Measure
2. Use Draft 11n Clients
3. Don't Connect Draft 11n and 11b/g clients to the same router
4. Use WPA2/AES
5. Don't use Channel Bonding

Some test results with iperf. You can also download iperf and run it on a command prompt, I'm using the following parameters, iperf -c IPADDRESS -i 1 -t 180 -w 200K, you can also type iperf --help to see the available parameters. I will try to provide more test results when I am back to work on the 29th. I'm actually on vacation now...

Average transfer rate of 4.59MB/sec in NONE security mode


Average transfer rate of 4.52MB/sec in WPA-AES security mode


Average transfer rate of 2.47MB/sec in WEP or TKIP security mode


The above test is performed with our wireless N dongle on the Playon!HD over a TP-LINK TL-WR841N wireless router.

Based on the test report, users should be able to transfer at rates of approximately 5MB/sec and above, depending on the network environment and configuration.

Please take note that this article remains as a guide to our wireless N dongle transfer rate. Should you have any problem arising with your networking speed, please email to our tech team at tech@acryan.com with your network configuration and transfer rate attained, we will try our best to look into it.

Hope this article helps.

Eugene,

Nice work, well done.

Will we get pics from your holiday as well

Eugene,
I'll bug you again when you're back from HK

still getting 150-200KB/s when file copying wirelessly into the POHD NAS,
Signal strength: Medium
Wireless Adaptor POHD : 802.11n
Wireless Router : 802.11g
Source PC : Wired
Security : WPA2-AES

54 --> 23 = 43%
300 --> 74 = 25%
Apparently the efficiency of 'g' is much better than the efficiency of 'n'. So be it.


The step from 74 to 40 Mbits/s I missed... What's the reason for loosing another 46% transmission capacity?


Knowing that many factors come into play when streaming video, can you give us a ballpark figure of the maximum (wireless) transmission capacity that the POHD is able to reach when streaming an HD video file?

I'm back to my desk but sorry no pics from my vacation. It's more of a visit the in laws trip instead...

The 74Mbits/sec is the typical transfer rate for a theory connection rate of 300Mbits/sec, I roughly halved it to 40Mbits/sec throughput for our 1T (150MBits/sec) 2R (300MBits/sec) Wireless N Dongle.



I have made some transfer tests which you can refer to in a later thread reply. Streaming a HD video will ultimately depends on both the audio/video bitrate. For some uber high quality videos, it may be necessary to stream using an Ethernet connection instead, as the wireless N bandwidth may still be insufficient to stream these videos. But of course, we would recommend playing of these high quality videos to be made via the internal HDD or an attached external HDD.

As promised, more network transfer result screenshots.
This time round the test was carried out with
- Linksys WGA160N Wireless N ADSL2+ Gateway/Router (Router)
- My NEC Versa E6300 Notebook with our Wireless N Dongle (NB)
- Playon!HD with our Wireless N Dongle (POHD)

Test #1: NB (Wireless N) -> Router -> POHD (Wireless N)
Running IPERF in Server mode on POHD and Client mode on NB
Results: ~4.5385MBytes/sec


Test #2: POHD (Wireless N) -> Router -> NB (Wireless N)
Running IPERF in Server mode on NB and Client mode on POHD
Results: ~2.415MBytes/sec


Test #3: NB (Ethernet) -> Router -> POHD (Ethernet)
Running IPERF in Server mode on POHD and Client mode on NB
Results: ~10.93MBytes/sec


Test #4: POHD (Ethernet) -> Router -> NB (Ethernet)
Running IPERF in Server mode on NB and Client mode on POHD
Results: ~7.766MBytes/sec


Test #5: NB (Ethernet) -> Router -> POHD (Wireless N)
Running IPERF in Server mode on POHD and Client mode on NB
Results: ~5.3645MBytes/sec


Test #6: POHD (Wireless N) -> Router -> NB (Ethernet)
Running IPERF in Server mode on NB and Client mode on POHD
Results: ~1.972MBytes/sec


Test #7: NB (Wireless N) -> Router -> POHD (Ethernet)
Running IPERF in Server mode on POHD and Client mode on NB
Results: ~7.674MBytes/sec


Test #8: POHD (Ethernet) -> Router -> NB (Wireless N)
Running IPERF in Server mode on NB and Client mode on POHD
Results: ~7.142MBytes/sec

That looks promising, but still there is no write speed above 5 MB/s possible.

Could this be because the POHD internal HDD is connected through USB? At least it looks like this in the mount output (Found this by telnetting to the POHD and issuing the mount command).

Furthermore the filesystem is NTFS, which could be troublesome because the (userspace) driver is slower than ext2 or ext3.

And last, because the file transfer protocol is smb, which is also not the fastest protocol.

Other possibility is the NIC itself, which uses too much CPU resources. I haven't figured out the brand, but cheaper NIC's have less throughput compared to Intel NIC's for example.

Yesterday I took a look at the processes, running on the POHD when playing movies. When playing a 4 GB DVD, the MIPS CPU was idle for around 90% of the time, both when streaming via ethernet and via 802.11n. When playing a 20 GB m2ts file via ethernet, the CPU idel time averaged at some 50%. It varies between 40% and 75%, depending on the movies bit-rate. The m2ts file played well.

When I played the 20 GB m2ts file via 802.11n, the CPU idle time dropped to between 10% and 20%. The movie played in stop-and-go-mode.

The 'top' program showed that the CIFS daemon is very busy, showing that file data processing takes quite some time / processing power. My personal experience is that when the CPU gets idle for less than 30%, you'll probably get hiccups.

My opinion is that, while the actual throughput is definitely less than the theoretical throughput (Eugene, thanks for the measurements), it's even worse when the data actually is being processed on a CPU. When people complain about lack of network throughput, they can have a look at what's happening by running 'realtop' on the POHD (set TERM to ansi...). When the CPU is idle for less than 20%, the 400 MHz MIPS CPU probably is the bottleneck.

Eugene, can you test with the SingTel 2Wire MioBox (802.11g) with the POHD adaptor-n

copying to the POHD (802.11g) from my PC (wired), i only get around 200KB/s

copying to my laptop (802.11g) from my PC (wired), i get around 1.4MB/s (laptop next to POHD)