Contents

	Welcome Note
	Future Proof Your Network
	NGF Frames for Telcos
	Optical Connector Identification System: TracerLight
	Central Office Implications in FTTP deployment

Central Office Implications in FTTP deployment

A flexible, cost effective FTTP network required thoughtful decisions regarding all segments of the network, from optical line terminal (OLT) in the central office to the optical network terminal (ONT) attached to each home and everything in between. While much attention is focused on the distribution and access elements within the outside (OSP) network, it’s also important to consider the implications of FTTP architectures within the central office (CO).

Before specific product selections can be made, some critical network architecture decisions are necessary. These key decisions involve connection strategies, flexibility in terms of test access points and WDM positioning. Deciding on CO network architecture for FTTP networks requires many considerations. The goal in any network is to minimize capital expenses and long term operational expenses while achieving the highest possible levels of flexibility within the network. The basic function of an FTTP network in the central office is to connect the OLT equipment to the OSP fibres deploying WDM somewhere in the middle to enable voice and data signals to be combined with video signals.

Since equipment cost in any network is directly related to the number of connector interfaces, one way to reduce capital expenditure is to eliminate or reduce the number of connector interfaces wherever possible. Maintaining flexible access to and use of the OSP network in the CO will be critical for long-term operations. Many people assume that FTTP network will remain static and can therefore be hard spliced or direct connected to save short-term capital expenditures. But in reality, this will result in significant long-term operational expense and flexibility issues. Therefore the traditional cross connect architecture in the CO is recommended which allow the most flexible use of OSP fibres deployed in an FTTP network and enable the easiest implementation of OLT equipment changes.

Another very critical architectural decision is where to place the video WDM (Wavelength Division Multiplexer). In an FTTP network, a video WDM is used to combine voice/data signals with video signals onto a single fiber. This is necessary since most FTTP networks today use a single fiber to each subscriber for voice, data and video. Since the OLT for voice and data differ from those used for video services, the signals must be combined onto the single fiber at some point in the CO. There are two choices for video WDM placement. First option is to place this at the OLT frame and second option to placing it within the FDF.

Better approach to place the video WDM is to place it in the FDF line-up. This method offers many advantages to an FTTP network. Placing the video WDM in the cross connect FDF line-up in the equipment frame provides the lowest overall cost, the minimum number of optical connectors and the best network flexibility. Since the video WDM is located at the FDF and all OLT patchcords are routed directly to the FDF, greater flexibility is provided regarding how the OLTs are combined and configured. Any OLT can be easily combined with any other OLT, regardless of its location in the CO.

Next discussion point is the incoming OSP fibre counts. The incoming OSP cables used for the FTTP network will have large fibre counts for accessing as many homes as possible. Since a major expense to any network is burying the OSP cable in the ground, any OSP cable installed should be sized for future service needs. OSP cables will likely pass several areas including businesses providing more opportunities over the same cable being used for FTTP network. Potential business customers that can be serviced over the same cable can not be overlooked. Therefore, back in the CO, each fibre needs to be easily accessible by all areas of the network, not just the FTTP designated equipment.

Due to the large fiber counts in CO and floor space availability issues, FTTP networks will require high density fibre distribution frames that enable the maximum number of termination within the least possible space. While a high-density FDF system may be important for reducing physical space required for FTTP deployments, the density gain cannot be achieved at the sacrifice of fiber cable management within the frame.

Any high density fibre distribution frame must be functionally designed to accommodate large number of incoming fibers and the maximum number of terminations associated with FTTP infrastructure. There are four key aspects of cable management to consider when evaluating any FDF: bend radius protection, connector access, cable routing paths and physical protection.

FTTP networks require similar if not more stringent cable management attributes as any OSP network that comes into the CO. Flexibility and accessibility are particularly important since although FTTP may be the application of the day, non-FTTP applications cannot be overlooked as additional revenue sources over the same fibre.

Designing FTTP networks with proper care and planning will provide added benefits to the carriers- maximum efficiency, easy access, high  flexibility and lower cost.

This is an abstract from the book authored by ADC KRONE. ‘The book on FTTX: From Design to Deployment- A practical guide to FTTX Infrastructure’.

Go to http://www.adc.com/productsandservices/productsolutions/fttp/ to read full article or know more about FTTX solutions.