Research On Lightweight Physical Layer Assist Authentication Technique In Smart Grid

Millions of smart metering devices are deployed in smart grid to deliver on a wide variety of capabilities, including adjusting real-time power pricing information, and performing automatic control on smart appliances through wireless communication. However, compared with wired networks, wireless communications lack a physical boundary due to the broadcasting nature of wireless transmissions, which can cause message eavesdropping and tampering, malicious node attacks and denial of service attacks. Providing security for smart grid system is a necessary task in order to guarantee safe and secure grid operation. Authentication of the messages is an effective approach to countermeasure against most of the possible attacks, which can ensure the integrity and authenticity of the message. However, traditional authentication mechanism based on PKI and symmetric encryption is resource-consuming due to the intensive computation involved in encryption and decryption. This imposes a serious burden on smart meters which usually have limited memory and computational capacity.Physical layer authentication takes advantage of temporal and spatial uniqueness in physical layer channel responses. The comparison of the currently detected channel response and the previously saved one only takes hardware operation, which achieves a fast and light weight authentication compared with any other traditional upper layer authentication schemes. Therefore, PLA is a solution to the continuous real time message authentication in smart grid. This thesis puts emphasis on the application of physical layer authentication in smart grid. The major work of this paper is as follows:1. The common interpolation algorithms of LS channel estimation are studied. ILS algorithm is selected to extract the channel response by comparing the simulation performance.2. Physical layer authentication technology based on hypothesis test is studied. Firstly, an improved normalized LRT statistic calculation scheme is proposed, which simplifies the solution of the threshold. Secondly, a novel physical layer authentication scheme based on SPRT statistic is proposed based on the analysis of the existing schames based on LRT. The performance of the proposed scheme is measured by simulating with MATLAB under IEEE802.15.4g standard, the simulation result shows that the proposed SPRT scheme outperforms the original LRT scheme about 2dB.3. The one-way and mutual cross layer authentication mechanisms are proposed by integrating the traditional message authentication schemes and the physical layer authentication mechanism.4. The centralized broadcast and distributed randomized multicast clone node and Sybil node detection schemes are proposed by considering the channel responses between communication smart meters as a form of fingerprint with spatial and temporal uniqueness. The centralized malicious node detection scheme with low cost, high detection rate, but the central node becomes a single point of failure. The distributed malicious node detection scheme avoids single point of failure by increasing communication and storage overhead. Simulation results under IEEE 802.15.4g standard with MATLAB illustrate that the proposed malicious node detection schemes achieve approximately 100% detection rate, assuming that the central node is reliable or the number of witness nodes is sufficient for the detection.