A Combinatorial Key Predistribution Scheme for Two-Layer Hierarchical Wireless Sensor Networks

Because of comprehensive and simple structures, various types of combinatorial designs are used to construct key predistribution schemes for wireless sensor networks. However, these schemes are typically concentrated on networks, where all sensor nodes are same in terms of capabilities. In this paper, we propose a key predistribution scheme based on combinatorial designs for two-layer hierarchical wireless sensor networks, where a small percentage of sensor nodes have more capabilities such as storage, communication range and battery power and so on. In this scheme, we use an orthogonal array to construct a key predistribution scheme. Then we assign keys associated with a block to a more capable node and keys associated with a random subset of a block to a less capable node. General formulas for metrics of the proposed scheme are obtained and these metrics are evaluated in some different network models. It is found that the resulting scheme has better resilience and tradeoff than some probabilistic schemes.