What is Bi-PON?

What is Bi-PON?

This year the GreenTouch initiative, an alliance dedicated to improving the energy efficiency of ICT networks by a factor of 1,000, released a prototype for reducing energy consumption in fibre networks.


The Bit-Interleaved Passive Optical Network (Bi-PON) is specifically designed to produce energy savings in FTTH access networks, which are a significant contributor to the total power consumption of the overall communications infrastructure.

Its construction came about through the re-architecture of FTTH optical network units to squeeze as much energy expenditure out of the network as possible.

The development of Bi-PON was led by Peter Vetter, principal research engineer at Alcatel-Lucent Bell Labs, who heads GreenTouch’s Wireline Access Group. Other contributors include INRIA, IMEC and France Telecom-Orange.

How does Bi-PON reduce energy consumption in fibre networks?

Bi-PON is built around a new protocol which significantly simplifies electronic circuitry by using a selective data processing technique that is designed to reduce energy consumption.

It is aimed at being more efficient than existing optical network units which, according to GreenTouch, discard 99% of all processed data without ever using it. Bit-Interleaving works by simplifying the process in which subscribers consume data.

Today’s passive optical networks broadcast data in packets to distribute to homes but the optical network has to post significantly more incoming traffic in order to select the relevant data that users want. This means that even if only 10Mbps is required on a system then 10Gbps will be sent, resulting in more than 90% of unnecessary processes.

The Bit-Interleaving system is able to select the relevant data much closer to the receiver so that less power is consumed.

In a demonstration, GreenTouch compared the power consumption of a traditional 10G optical network and a Bit-Interleaved 10G optical network when providing connectivity to central office and customer premise ONUs from video servers. The same video content was streamed through both systems and its power consumption was monitored.

The traditional system was measured in sleep mode with power consumption standing at approximately 2.5 watts, whereas power consumption for the Bit-Interleaved system measured approximately 60 milliwatts.

The Bit-Interleaved system also consumed 50% less power when there was no traffic being transmitted, compared to the traditional system which consumed the same amount.

What could be the potential savings for carriers?

Bi-PON is estimated to enable a power reduction of at least 30 times over current technologies and is also claimed to improve performance and reduce costs.

Another advantage of the system is that it only consumes power when bandwidth is being used as opposed to traditional systems that require the same amount of power regardless of their usage.

With FTTH subscribers expected to double over the next five years, reaching 142 million globally by 2016 according to ABI Research, it is calculated that replacing traditional systems with Bi-PON could have the same reduction on carbon footprint as taking half a million cars off the roads. This is the equivalent of all the cars in a city the size of San Francisco being removed.

Through lower power use carriers can reduce their opex and gain floor space due to not having to house as much power supply and back-up battery equipment.

GreenTouch says that it expects Bi-PON technology to be a necessity as electronic processing increases in future 40G PON systems and sees it as an important application for both FTTH and backhaul.

How essential is energy efficiency to future networks?

Bi-PON is part of a larger initiative by GreenTouch’s Wireline Access Group to produce energy efficiency gains of 500 times over systems being used today.

Another project being lead by the group is Low-Energy Architecture, which aims to identify the access solution with the lowest possible energy consumption for both a scenario with existing PON-based fibre infrastructure and greenfield sites.

While the Virtual Home Gateway project aims to analyse and identify the most energy-efficient distribution of home gateway functionality in the access and home network. Other savings are hoped to be achieved through technologies such as power shedding, sleep mode, transparent CPE, lower power optics and low power electronics.

France Telecom-Orange has expressed an interest in testing the Bi-PON system this year which should bring the technology closer to an actual field deployment, and may even lead to more efficiency savings being discovered.

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