This is a quick and dirty test setup as a special favour for one of our blog commentors. We compare the two TP-Link Nano Wifi adapters versions, and their respective throughput rates.
One notebook as a web server, with a Samsung 840 Pro SSD harddrive, 8 GB RAM. Connected to Gigabit switch (over Gigabit Ethernet), which in turn is connected to TP-Link TL-WR1043ND over Gigabit Ethernet.
The router is running on DD-WRT. WiFi is set to N only (2.4 Ghz). (Expect worse performance on mixed networks!)
Distance between the router and the TP-Link Wifi adapter: ~ 15 m – located on the same floor.
Measuring is done with iftop (to install: aptitude install iftop )
iftop -b -n -i wlan0
This will show the throughput rates in bits/s, not bytes/s (divide by 8 if you need them, or use the appropriate command line switch).
The wlan0 is the only network on the Raspberry, eth0 is disconnected.
The load is generated by wgetting a large file (raspbian Image) from the web server, and writing it to /dev/null (otherwise the SD card’s speed will have an impact). For even faster performance, the log is also written to /dev/null .
wget -o /dev/null -O /dev/null 192.168.1.16/raspbian.img
If you want to try this yourself, replace the IP adress with your host (name or IP).
Remember, this is the Raspberry – general purpose processing power is at a premium and needs to be factored in. iftop will also take it’s toll, the real throughput in the test setup will be a bit higher.
In a real scenario, though, you want to run other utilities, applications, etc, so throughput will most likely be lower.
Sensitivity to orientation
As the throughput is very sensitive to the orientation of the dongle, we have tried to optimize the positioning of the Raspberry and the dongle in these measurements.
TP-LINK v 2
This is the result for version 2 of the TP-Link WiFi Adapter, using a custom driver (none included with the official distro).
The total network throughput we measure here is (peak) ~ 28 Mb/s, or > 3 MB/s.
TP-LINK v 1
This is the result for version 1 of the TP-Link WiFi Adapter, using the stock driver
Total network throughput is ca. 21 Mb/s or slightly more than 2.5 MB/s.
LogiLink Ultra Nano Wireless N 150 Mbps USB Adapter
This is “WL0084B” or 98 71 33 Wireless N 150 Mbps Adapter by LogiLink. This is most probably the adapter we will be shipping with our kits when we have no TP-Link adapters left anymore.
This adapter works out of the box for us, we’ve also tested it on Raspbmc. Apparently you can also use it to set up a WiFi access point, as the chipset supports that mode.
Peak throughput seems to be at about 20 Mb/s = 2.5 MB/s (with a lot of orientation fiddling).
The WiFI adapters are highly orientation sensitive. Consider the following two screenshots (TP-Link hardware). the Only difference is the orientation of the Raspberry Pi (and with it the TP-Link WiFi USB dongle)
To reach the optimal rates we measured here, you need to orient your nano dongle. A good idea would be to use a passive USB extension to allow for a greater degree of freedom in the orientation.