Project Number: FP6-IST-507554 Project Title: BROADBAND in ...

7.2.2 Cable
7.2.2.1 Introduction
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FP6-IST-507554/JCP/R/Pub/D2.2-3.2
Cable networks have so far been utilised mostly for broadcast TV applications in Europe, but high HFC network
installation and maintenance cost make it hardly competitive with satellite if used for broadcast services only. A
cable network is an ideal medium for converged services delivery as it can convey broadcast, multicast and
single-cast services. Broadband access via cable has approximately a rough 40% world-wide market share, and
has now the challenge to remain a viable alternative to other access technologies.
7.2.2.2 State of the art / current Technologies
7.2.2.2.1 Cable networks current architecture
The view below (Figure 9) summarises the architecture of a modern HFC (Hybrid Fibre Coaxial network).
Many variants can exist but in general the architecture includes several levels:
• A Main Head-end (Central Node) where all broadcast services are aggregated. The main HE feeds the
secondary Nodes (or Local Nodes), generally through secured fiber optic links.
• The local nodes feed medium size cities or small regions; many variants like shown in Figure 9 can
apply. The local node serves a number of coaxial areas via fiber links using usually analogue
transmission. The boundary node between fiber and each coaxial area is called a Fiber Node. The
coaxial area size will determine the ultimate traffic capacity available per user.
• The coaxial area architecture can be either a star network with different levels, or more commonly a
tree and branch network; this part becomes critical when very high bit rates have to be conveyed
Figure 9: Example of HFC architecture
The HFC specific part of the network begins at the Local node (the MAN or WAN between the DN and the LNs
not being specific to HFC); optical transport is usually analogue, transmitting transparently the upstream and
downstream spectrum.