Comparing Active and Passive Optical Networks

FTTH (Fiber to the Home) access networks are widely deployed in homes across many countries. Today, more and more subscribers are using optical fibers rather than copper lines for broadband Internet access. FTTH is the most advanced form of fiber-optic communication which you can avail of in your living room or working area. These fibers run from a central location to living or working space of the subscriber. There are two types of systems that are widely used in FTTH networks: PON (passive optical network) and AON (active optical network).

Active Optical Network (AON)

Active Optical Networks are also referred to as point-to-point network. They make use of switching equipment like routers and switch aggregator, which are electrically powered for managing signal distribution and transmitting direct signals to certain subscribers. The switch is capable of opening and closing a number of different ways which allows it to direct incoming and outgoing signals to the appropriate places. You can have a dedicated fiber running to your house if you choose an AON.

Passive Optical Network (PON)

PON or Passive Optical Network is not the same as AON as it does not have any electrically powered switching equipment. PON makes use of fiber optic splitters for directing traffic signals of different wavelengths. The optical splitters used in PON are capable of separating and collecting optical signals as they are transmitted through the network. You will need electrically charged equipment only at the source of the signal and at the receiving end of the signal. PON networks are capable of directing signals to 16, 32 and 64 customers at a time.

AON vs. PON

All systems have their own specific advantages and disadvantages. Those who subscribe to AON can benefit from the fact that bandwidth in each port is dedicated for each subscriber and they don’t need to share the bandwidth with anyone. So you can have a much higher bandwidth per port through AON than with PON. Also, it is much simpler to identify defects in the AON. The drawback with the AON system is that it needs active equipment for managing signal transmission. So the electricity costs can be high.

Signal Distribution

As a subscriber to an AON network you can have a dedicated fiber optic strand. This means each person who subscribes to AON gets dedicated bandwidth which isn’t shared. Users of PON can share the fiber optic strands for a part of the network. Since you have different structures for PON, the results will also be different. So if there is an issue with the PON network, you won’t be able to find the source of the problem. This is not an issue with AON.

Equipment

AON directs optical signals by making use of electrically powered equipment. There is no powered equipment used in PON except for those used to guide signals to the two ends of the system. The biggest ongoing expense in a network is the cost of the powering equipment and the maintenance. PON makes use of passive components that require less maintenance, but no power. So PON is less expensive than AON.

AON networks are long range and can cover a distance of 100 km. PON are short range networks that can up to no more than 20 km. For running PON, subscribers have to be nearby the central source of the data. AON and PON are two different solutions for FTTH networks. Both systems are widely used these days because of the huge demand for more bandwidth.