Powerline Ethernet Adapters VDSL2 REIN Interference

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Powerline Ethernet Adapters VDSL2 REIN Interference

Postby embleton » Mon Aug 10, 2015 9:04 am

Do Powerline Ethernet Adapters, Ethernet homeplugs, cause interference with hybrid fibre VDSL2 signals? For a start, the operating frequency of AV2 homeplugs is 1.8Mhz to 86Mhz and VDSL2 operates up to 17Mhz, so the operating frequencies of the two do overlap and there is the potential for high-frequency interference between the two systems.

To this end three test was run over a three month period to monitor the impact of Powerline adapters on VDSL2 signals on a hybrid fibre VDSL2 connection running at the maximum synchronisation speed of 80/20Mbps with an attenuation of 12.8dB on the hybrid fibre to the fibre to the cabinet (FTTC) box and 11.8dB noise margin, as reported on a SR102 Sky Hub VDSL2 incorporated modem. The throughput is 74.8Mbps throughout a month period on average without any Powerline adapters in the circuit.

The round trip distance to London from Plymouth is approximately 500 miles (820 kilometers), and the round trip delay with VDSL2 to the cabinet and beyond to London is 10.6ms on average as measured by the SamKnows whitebox (4.7ms per a thousand kilometres of fibre, so the VDSL2 connection is on fastpath with little interleaving; at that distance round trip to London is 3.854ms on fibre (820km * 0.0047ms = 3.854ms) and 6.746ms with interleaving return trip to the FTTC box, as every connection to the cabinet has a percentage of interleaving on its connection, fastpath is usually considered running on a VDSL2 broadband line when the latency is below 10ms to the cabinet, of which my connection is below that figure.

Three test environments were used:- 1. no Powerline adapters connected at all, as a baseline. 2. Powerline Adapters connected at a distance of 1 meter separating from the VDSL2 modem, 3. Powerline adapters connected at a distance exceeding 2 meters and beyond from the VDSL2 modem. The setups were monitored by a SamKnows Whitebox to establish the overall impact on packet loss, latency and throughput speed throughout a month period on each setup, and the findings are reported below.

When homeplugs are less than a meter from the VDSL2 modem or cable going to an NTE5 MK2 VDSL prefiltered faceplate it always has an impact on all three measurements; packet loss, latency and throughput, and usually in my experience causes instability with the FTTC VDSL2 hybrid fibre connection, so one thing for sure is the Powerline adapters must be separated by more than a meter away from the VDSL2 modem and cable going to the NTE5 master telephone socket, but what impact does it have at a meter the usual minimum distance recommended by most individuals?

At 1 meter from the VDSL2 modem and cable going to the NTE5 master telephone socket the findings are interesting, to say the least, at this distance it does have an impact on throughput and latency, my findings found that the throughput dropped by 800Kbps over the month averaged and the latency increased by 0.2ms round trip to the FTTC box; so at this distance it is causing interference and errors on the VDSL2 signals. Even though the connection did not drop the impact on interleaving was approximately just above 1% performance degradation on the hybrid fibre connection to the cabinet. At 2 meters and beyond the impact on the VDSL2 signals was zero, disproving that Powerline adapters cause interference throughout the mains ring around the premises.

My recommendations for near to zero impact on the FTTC signals is separate the homeplugs by a distance exceeding 2 meters from the VDSL2 modem and cabling, and that it is safe to use this method of extending Ethernet around a home with AV2 homeplugs, and that they will not cause interference beyond this distance to either your broadband connection or neighbours VDSL2 FTTC hybrid fibre connection when following this recommendation concerning distance separation of 2 meters and beyond.
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