  Cognitive Radio (CR) promises an efficient utilization of radio spectrum
resources by enabling dynamic spectrum access to overcome the spectrum scarcity
problem. Cognitive Radio Sensor Networks (CRSNs) are one type of Wireless
Sensor Networks (WSNs) equipped with CR capabilities. CRSN nodes need to
operate energy-efficiently to extend network lifetime due to their limited
battery capacity. In this paper, for the first time in literature, we formulate
the problem of finding a common energy-efficient transmission range and
transmission duration for all CRSN nodes and network deployment that would
minimize the energy consumed per goodput per meter toward the sink in a greedy
forwarding scenario. Results reveal non-trivial relations for energy-efficient
CRSN transmission range and duration as a function of nine critical network
parameters such as primary user activity levels. These relations provide
valuable insights for detailed CRSN designs prior to deployment.
