Physical layer security analyses for low-bit-rate hybrid PLC/WLC and broadband plc systems

Abstract

This Doctoral thesis focuses on the physical layer security (PLS) aspects of power line communication (PLC) systems. In this way, it addresses how a malicious device can overhear private signals traveling over and radiating from electric power grids. Also, it discusses the PLS issues related to the parallel combination of PLC and wireless communication (WLC) systems for accomplishing one-hop transmission. Given these aims, a general discussion on important issues related to PLC systems is presented. First, PLS issues associated to the distinct voltage levels in electric power systems are detailed. Second, the types of eavesdroppers that can breach the security of PLC systems are listed. Focusing on the PLS of in-home broadband PLC systems, this thesis investigates to which extent malicious and passive PLC or WLC devices can be capable of breaching the security of PLC systems in the physical layer level. To this end, secrecy outage probability, effective secrecy throughput, and wiretap code rates are numerically evaluated with the use of real data sets composed of channel estimates and measured additive noises. These data sets were obtained from distinct measurement campaigns carried out in several Brazilian houses. The numerical results quantitatively show, in practice, the level of vulnerability of in-home broadband PLC systems in terms of PLS and offer the wiretap code rates to deal with the presence of PLC and WLC eavesdroppers. Furthermore, the investigation of the benefits of the existing diversity in the parallel use of both PLC and WLC channels by low-bit-rate hybrid PLC/WLC systems to improve PLS is provided. In this regard, mathematical formulations of the ergodic achievable secrecy rate and the secrecy outage probability are developed for the hybrid PLC/WLC wiretap channel model and its incomplete versions. The numerical results show that the hybrid PLC/WLC systems can provide remarkable benefits in terms of PLS for low-bit-rate applications when the eavesdropper makes use of only one data communication interface.