Overbuilding

Written on 2:32 PM by ooe

Overbuilding refers to the situation where a new network is being provided in addition to established infrastructures such as twisted pair for telephony and coaxial cable for cable TV services. The incumbent networks may be old and the ability or will to deliver broadband data services is weak. The opportunity for the over-builder is to offer broadband data as an alternative or in addition to the other services. New-entrant operators are introducing point-to-point Ethernet systems to satisfy the demand for data in both residential and small to medium sized business sectors.

The standard PON is based upon ITU G983 series and is capable of delivering 622 Mbit/s symmetrical services by circuit emulation, or with ATM or Ethernet interfaces. These PONs are currently focused on the business market but work is in progress to widen the service set to include telephony and cable TV services for residential green field applications. The cost of fibre access is high, so it is a challenge for any fibre access solution to be profitable in the residential overbuilding scenario. A data-only solution is likely to be simpler and cost less than a full service access network but has fewer revenue streams available to pay for its introduction.

A data-centric approach is possible using point-to-point fibre and LAN technology to connect buildings and apartment blocks to service providers. An active node such as a hub, switch or router at the fibre entry point to the building is used to connect individual offices or residences via category 5 cable (one twisted pair for each direction of transmission). This type of network is gaining popularity but will struggle to deliver high quality telephony and real time video for residential applications because of the absence of circuits. Contention for bandwidth in such networks is difficult to control if the access protocol remains IP.

The G983 series PONs are able to deliver data-only services and multiple line digital telephony by circuit emulation. These systems can be considered as an alternative to SDH and PDH point-to-point rings for overbuilding in a business community where demand for telephony in blocks of up to 24 (T1) or 30 (E1) channels are commonly found.