5 Broadband PLC systems for data transmission
5.1 BPL options in practice

Transmission it the distribution network can be considered in two types of BPL systems.

The mechanism of signal propagation using power lines is getting more and more difficult and confusing, if the signal frequency is higher, and therefore the relevant wavelength is comparable with the geometric lengths of the sub-sections (e.g. branches). Parallel and serial resonance emerges very often. Furthermore, besides the inhomogeneities of particular sections, it is necessary to consider in transmission parameters, caused by configuration changes and instantaneous changes of the load, and, of course, by relatively high level of noise generated by different sources. It is also necessary to consider transmission properties of the splitters and junctions.

To successfully solve problems in aggressive environment of power lines, one could use experiences that telecommunications equipment manufacturers have gathered during development and operation of cable television and modern radio communication systems. That is why specific solutions for BPL systems use the latest modulation and access methods. A current development of PLC is focused on two types of modulation: Direct Sequence Spread Spectrum Modulation (DSSSM) and OFDM (Orthogonal Frequency Division Multiplex).