Systems and methods for building, transmitting, and receiving frame structures in power line communications (PLC) are described. Various techniques described herein provide a preamble design using one or more symbols based on a chirp signal that yields a low peak-to-average power ratio (PAPR). According to some techniques, the preamble may be constructed with one or more different types and/or number of symbols configured to identify a PLC domain operating in close physical proximity to another PLC domain. According to other techniques, one or more preamble symbols may be interspersed within a header portion of a PLC frame to facilitate estimation of a frame boundary and/or sampling frequency offset, for example, in the presence of impulsive noise. According to yet other techniques, a PLC detector may be capable of receiving and decoding two or more types of PLC frames (e.g., using different PLC standards).