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True Speed of Powerline (HomePlug) Adapters

August 14th, 2014

After long research of the market options, I finally upgraded to Powerline adapters at home. I got mine from Amazon. One detail that got my attention was the officially declared Powerline adapter’s speed. I believe this aspect is confusing for other people as well.

Performance of Powerline adapters

What is Powerline (HomePlug)?

It’s data transfer technology which uses existing powerlines in your flat or house without running separate cabling.
Thus, using these adapters is quite convenient especially in  cases, when you are renting a flat and you are not allowed to make any changes to the cabling.

Powerline adapters use an adaptive modulation in the frequency spectrum ranging from a few MHz up to ~70MHz (depends on the standard). 

Existing standards, compatibility and declared speed

The 1st HomePlug standard regulating Powerline adapters was released in 2001 with a declared speed of up to 14 Mbps. Later on, newer generations of the adapters were designed with the speeds up to: 85 Mbps, 200 Mbps and 500 Mbps, 500+ and 600 Mbps. However, the declared speed is some kind of theoretical speed  which includes the technical data of the Powerline protocol itself and the Ethernet speed of the network devices. 

Thus, the sum of the “LAN speed” and the modulation overhead would equal the aforementioned declared speeds.

Personally, I am more interested in the speed which would show the  data transfer between network devices on LAN. For instance, the media player and the network attached storage (NAS)  are inter-connected by the Powerline adapters. Of course, this “LAN speed” may depend on which data transfer protocol is used and many other details.

Different Powerline adapters of 200, 500, 500+ and 600Mbps are compatible between each other except first two  standards of 14 & 85Mbps. Here is a TP-Link powerline adapters compatibility matrix. Another aspect, which should be taken into account, is that some vendors make their Powerline adapters compatible only with other their company devices.

Of course, if your Powerline is mixed from different generation adapters, you will not get the highest performance matching the newest adapter.

You can have a few Powerline networks sharing the same power lines at the same time. However, they would compete for the frequency spectrum and this would negatively impact the performance (the same as a network hub principle).

Results of my Powerline upgrade to AV500

Two of my adapters, which are shown in the photo above, have declared speeds of 85Mbps and 500Mbps . The 1st one is Targa brand (rebranded Devolo?) and 2nd is TP-LINK TL-PA4010 (sold as part of TL-PA4010KIT). Both of them have 10/100Mbps compatible Ethernet interfaces which means that the real Ethernet speed should not ‘spike’ more than 100Mbps 😀

Few technical details related  to my test environment:

  • As far as I know, all power wires in my place are made from copper (Copper is supposed to be better compared to the aluminium wires).
  • I have a 100 Mbps speed from my ISP. A very close value of that is reachable straight after the router using a wired connection.
  • Only one pair of Powerline adapters were used during testing.

The TP-Link utility allows you to monitor the speed between the Powerline adapters (not the Ethernet speed):

Performance of Powerline adapters

I used SpeedTest, a Linux command iperf and a TP-Link utility to perform a few tests:

  1. I run SpeedTest with my selected server while my laptop was directly connected to my router.
  2. The adapters were connected to nearby installed power sockets (perfect conditions).
  3. The adapters were connected to different power sockets in the same room.
  4. The 1st adapter was left in the ground floor, while a 2nd adapter was moved to the 1st floor.
  5. The 1st adapter was left in the ground floor, while the 2nd adapter was moved to a 2nd floor.
  6. I used a command iperf to perform the test between my Sony Vaio (Ubuntu OS) and D-Link 320L (Debian OS), the setup was the same as in Step 2.

Here are the results of my test for TP-LINK TL-PA4010. The 1st value was measured by SpeedTest (#1-#5), iperf (#6) and the 2nd value (in the brackets) was found by using TP-Link utility :

  1. 89 Mbps
  2. 80 Mbps (337 Mbps)
  3. 61 Mbps (137 Mbps)
  4. 76 Mbps (140 Mbps)
  5. 59 Mbps (103 Mbps)
  6. 45 Mbps (103 Mbps)

The scenario #5 illustrates non so rare situation in the flat, when the powerlines (used by the adapters) go through couple floors. The TP-Link Powerline adapter TL-PA4010 performed reasonably well for this scenario by reaching 59 Mbps performance between different floors, what is enough to watch couple HD video streams, play online games etc. You can see from the figures the difference between a declared and measured speed values.

Do you wonder what would be the case with the older generation adapter like my Targa  PL-8505 (85Mbps)? Well, I know that the difference between them is two generations, but still I will provide the figures only for curiosity:

  1. 89 Mbps
  2. 18 Mbps (85 Mbps)
  3. 20 Mbps (42 Mbps)
  4. 10 Mbps (48 Mbps)
  5. 17 Mbps (36 Mbps)

For gear of such age, it performs quite well.

Const and Pros of using Powerline vs WiFi

As you can see, Powerline adapters have some limitations and the Ethernet speed depends mainly on:

  • the distance between the powerline adapters itself,
  • the noise level in your power sockets depends on connected devices and quality of their power supplies (e.g. microwaves etc.),
  • copper or aluminium wires have some influence on the performance,
  • the Powerline adapters have to be connected to the same phase,
  • they should not go through the circuit board and the breaker.

But at the same time, it is really easy to install the adapters and their configuration is minimal.

Another alternative to the Powerline adapters could be WiFi. However, its performance has implications as well.

Few of them are:

  • the interference with neighbors access points,
  • there are only few non-overlapping Wi-Fi channels for 2.4GHz,
  • the data is send to only one host per time,
  • quite bad penetration through the solid walls.

All these details need to be taken into account before deciding which technology to choose and build your home network. A mix of both gives the most in terms of the flexibility and the speed.

Hope, this post helped you better understand pros and cons of Powerline adapters 😉