Energy-efficient replica voting mechanisms for secure real-time embedded systems

The paper employs majority voting among replica processes to move correct data from the environment to the end-user entity in a secure real-time application setting. The replicas may be wireless computation nodes deployed in a power-constrained environment, and the data may be quite large in size with nonnumeric and non-exact contents (e.g., imaging devices in a geographic terrain). The voting protocol is made energy-efficient by reducing the amount of data processing and network-level message exchanges required in delivering data to the user. Our optimization takes into account: (i) processing cycles expended in comparing data; (ii) amount of replica data movement required; (iii) number of control messages generated. We consider two types of voting protocol: a 'centralized' scheme where replica data are collected at a secure power-abundant site to carry out the data comparisons for voting; a 'decentralized' scheme where each replica compares its locally computed data with a candidate data to send its consent/dissent message to a central vote collating site. The paper develops a performance model that considers the (i)-(iii) tradeoffs to determine the energy consumption levels in the centralized and decentralized voting schemes. Our model allows the voting apparatus to select an energy-optimal scheme, given the timeliness parameters and the network and processing bandwidths.