Spatial Extension of Access Networks – a Technical Analysis (No. 493) © Photo Credit: Robert Kneschke -

Spatial Extension of Access Networks – a Technical Analysis (No. 493)

What are the technical determinants of the range of line length in access networks? And what conclusions can be drawn from this for the spatial enlargement of access networks? This paper analyses the technologies xDSL, PON and PtP Ethernet.


The application of a scorched node methodology has been common practice of National regulatory Authorities (NRAs) for the purposes of regulatory costing and pricing. According to this concept, the shape and demarcation of the SMP operator’s access areas has been taken for granted by NRAs. With the availability of fibre-based access network technologies, the technical restrictions regarding the range of length of access lines have changed significantly and open up the possibility of spatially enlarging access networks further than was possible in pure copper networks by deploying fibre optics.

In this study, we analyse the capabilities of fibre-based access network technologies with regard to spatial extension of individual access lines and thus spatial enlargement of access networks. The technical characteristics of signal transmission, interference and attenuation are compared depending on the medium used - copper twisted pair or fibre optics. It is shown that fibre-based technologies hardly face relevant limitations with regard to access line lengths. The quality of splices and connectors as well as the use of high-performance SFP modules are decisive for this.

With regard to the spatial extension of fibre-based access networks from the end-user to the MPoP, a significant expansion of access areas is possible not only for fibre-only technologies but also for hybrid solutions. Differences between fibre optic technologies only come into play with PON architectures compared to FTTH PtP Ethernet technologies. Due to the relevant attenuation properties of splitters, PON architectures show a significantly shorter range of access line lengths in comparison.

Although the findings confirm the technical capabilities of fibre base access networks regarding relevant spatial enlargement, we have to emphasise that there is a need for an examination of the economic interrelationships, in order to identify the limitations of the spatial extension of fibre based access areas. This is examined in the WIK-Discussion Paper 494 “Spatial Extension of Access Networks – an Economic Analysis”.