Energy minimization and lifetime enhancement in Cognitive Radio Sensor Networks via relaying under interference constraints

This paper considers Cognitive Radio Sensor Networks (CRSN). The aim of this paper is twofold: First, we analyze the problem of total energy minimization in CRSN by choosing the best relay for each cognitive sensor node in the network. A node either sends its data packet directly to the Base Station (BS) or forwards to another node; and the latter, in turn, sends both packets to the BS. The proposed optimization problem is a multiple choice knapsack optimization problem that chooses the best path for each node targeting minimizing the total energy consumption in the network under interference constraints and with the aim of satisfying a specific Bit Error Rate (BER) for the CR system. The second aim of the paper targets increasing the lifetime in CRSN. This target is important in several applications as considering energy minimization only affects the network lifetime. Consequently, another knapsack optimization problem has been formulated and solved to choose the best scenario for each node, either by sending directly to the BS or by relaying via another node, with the aim of enhancing network lifetime under interference constraints and BER requirement for the CR system.