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—In underlay cognitive radio, a secondary user transmits in the transmission band of a primary user without serious degradation in the performance of the primary user. This paper proposes a method of underlay cognitive radio where the secondary pair listens to the primary ARQ feedback to glean information about the primary channel. The secondary transmitter(More)
In this paper, we propose a new multiple-level power allocation strategy for the secondary user (SU) in cognitive radio (CR) networks. Different from the conventional strategies, where SU either stays silent or transmit with a constant/binary power depending on the busy/idle status of the primary user (PU), the proposed strategy allows SU to choose(More)
We address a lifetime maximization problem for a single-hop wireless sensor system (also known as a Gaussian sensor network) where multiple sensors encode and communicate their measurements of a Gaussian random source to a fusion center (FC). The FC is required to reconstruct the source within a prescribed distortion threshold. The lifetime optimization(More)
—In this paper, we consider a pair of cognitive radio (CR) users co-existing with a pair of ARQ-based primary users (PU). The secondary user (SU) overhears the ACK/NACK feedback sent from the receiver of the primary system, and then decides to access the spectrum or not. An opportunistic sharing scheme, referred to as Spectrum sHaring with ARQ(More)