ABSTRACT
The rapid growth of Internet content and media streaming options, coupled with increasing bandwidth of broadband access (AC) technologies, has created an ecosystem of products and services that creates a demand for media in the home. Bottlenecks are the connection into the home and inside the home, wherein the data are forwarded to a gateway or router that has to distribute to various media sinks like televisions, smartphones, tablets, digital video recorders and cable set-top boxes. Wireless distribution is an obvious solution but faces many challenges like spotty whole-home coverage, high latency and jitter and difficult-to-maintain quality of service for multimedia streams. Coaxial cables are an alternative, but are not always conveniently located; there are usually only a few in a home, and running new cables is expensive and disruptive. Thus, in-home (IH) distribution of multimedia remains a challenge. An ubiquitous feature of all homes is the presence of electrical wiring. The electrical power line provides a large number of potential locations for media sinks. Thus, much effort has been invested in using power lines as a viable medium for IH data and multimedia distribution. Unlike a dedicated medium, for example, coaxial cables, the power line channel faces many unique challenges. Some of these challenges include the following:
It is a pre-existing medium that was not designed for communication. Power line technology should be able to work in any configuration or topology of wiring that may exist in a house or on power/utility company lines.
As network topology can change dynamically, the technology should be able to adapt. For example, turning on and off circuits/switches causes changes in loads and impedances which in turn changes the reflection properties, attenuation and noise characteristics of the channel (see Chapters 4 and 5).
The network may lack full connectivity, creating hidden node issues.
Power line communication signals are unprotected from other signals that may be using the medium.
The power line is a shared medium, and this creates challenges when there are neighbouring networks in multi-dwelling units.
The power line has asymmetric transmission properties and it is also time varying.
The power line suffers from narrowband interference, coloured-noise and impulse noise.
