Tài liệu Broadband Powerline Communications Networks Network Design - Halid Hrasnica Abdelfatteh Haidine Ralf

During the last decades, the usage of telecommunications systems has increased rapidly.
Because of a permanent necessity for new telecommunications services and additional
transmission capacities, there is also a need for the development of new telecommunications
networks and transmission technologies. From the economic point of view,
telecommunications promise big revenues, motivating large investments in this area.
Therefore, there are a large number of communications enterprises that are building up
high-speed networks, ensuring the realization of various telecommunications services that
can be used worldwide. However, the investments are mainly provided for transport networks
that connect various communications nodes of different network providers, but do
not reach the end customers. The connection of the end customers to a transport network,
as part of a global communications system, is realized over distribution and access networks
(Fig. 1.1). The distribution networks cover larger geographical areas and realize
connection between access and transport networks, whereas the access networks cover
relatively smaller areas.
The direct connection of the customers/subscribers is realized over the access networks,
realizing access of a number of subscribers situated within a radius of several hundreds
of meters. However, the costs for realization, installation and maintenance of the access
networks are very high. It is usually calculated that about 50% of all network investments
belongs to the access area. On the other hand, a longer time is needed for paying back the
invested capital because of the relatively high costs of the access networks, calculated per
connected subscriber. Therefore, the network providers try to realize the access network
with possibly low costs.
After the deregulation of the telecommunications market in a large number of countries,
the access networks are still the property of incumbent network providers (former
monopolistic telephone companies). Because of this, the new network providers try to find
a solution to offer their own access network. An alternative solution for the realization
of the access networks is offered by the PLC (PowerLine Communications) technology
using the power supply grids for communications. Thus, for the realization of the PLC
networks, there is no need for the laying of new communications cables. Therefore, application
of PLC in low-voltage supply networks seems to be a cost-effective solution for
so-called “last mile” communications networks, belonging to the access area