Modeling the indoor power line channel: new results and modem design considerations

Considerable effort has recently been devoted to the determination of accurate channel models for the power line (PL) environment, for both the indoor and outdoor cases. The common denominator (and limitation) of the known and previously published models is the particular type of approach followed. In fact, until now, the PL channel (PLC) has been treated from a mere phenomenological or statistical point of view. This allows us to describe the channel only partially, e.g., as dominated by multipath-like effects, and prevents us from unveiling any of its particular properties. We report results about a new approach to the modeling of the PLC based on multiconductor transmission line (MTL) theory. The need for an MTL approach arises from the fact that indoor power cables consist of three conductors, and not just two as for classical twisted-pair and coaxial cable cases. This approach allows us to include wiring and grounding practices dictated by the United States National Electric Code (NEC). On the basis of this modeling, we reveal that the PLC is a more deterministic medium than commonly believed. Moreover, it is also possible to prove an interesting symmetry property of the PLC that was previously unknown: the PLC, regardless of its topology, exhibits the same transfer function when driven from either side, provided that the source and load impedances are the same.