  A novel time synchronization attack (TSA) on wide area monitoring systems in
smart grid has been identified in the first part of this paper. A cross layer
detection mechanism is proposed to combat TSA in part II of this paper. In the
physical layer, we propose a GPS carrier signal noise ratio (C/No) based
spoofing detection technique. In addition, a patch-monopole hybrid antenna is
applied to receive GPS signal. By computing the standard deviation of the C/No
difference from two GPS receivers, a priori probability of spoofing detection
is fed to the upper layer, where power system state is estimated and
controlled. A trustworthiness based evaluation method is applied to identify
the PMU being under TSA. Both the physical layer and upper layer algorithms are
integrated to detect the TSA, thus forming a cross layer mechanism. Experiment
is carried out to verify the effectiveness of the proposed TSA detection
algorithm.

Cryptography and Security