To AND or To OR: How shall the fusion center rule in energy-constrained cognitive radio networks?

Abstract

Abstract-Distributed spectrum sensing enhances the detection reliability of a cognitive radio network. However, this comes at the price of a higher energy consumption. To solve this problem, a combined censoring and sleeping scheme is considered where the cognitive radios switch off their sensing module with a specific sleeping rate in each sensing period. The awake cognitive radios send their local decisions to the fusion center only if it is deemed to be informative. The fusion center either employs the OR or the AND rule to make the final decision about the presence or absence of the primary user. This paper investigates which rule performs better in terms of energy efficiency under various conditions. The underlying sensing parameters are derived by minimizing the maximum average energy consumption per sensor subject to a constraint on the probabilities of false alarm and detection. This way, it can be ensured that the spectrum opportunities are utilized efficiently while the primary users are not interfered with. A case study based on IEEE 802.15.4/ZigBee is considered for performance evaluation. It is shown that significant energy savings can be obtained by employing combined censoring and sleeping.

Energy-Efficient Cooperative Spectrum Sensing Using Machine Learning Algorithm

“…As an illustration, Ref. [ 30 ] evaluated the issue using the ‘OR’ rule, and [ 10 ] evaluated the issue using both the ‘OR’ rule and the ‘AND’ rule. There is a joint sensing and decision node selection strategy taken into account in [ 31 ], whose network energy consumption is minimized subject to a detection performance limitation described in [ 30 ].…”

“…Based on the above discussion, we decide, in order to reduce the energy consumption as well as the computational burden of the CSS system, to adopt the hard-decision fusion rule with the sleeping and censoring scheme discussed in [ 9 ]. In [ 10 , 11 ], the authors implemented the combined sleep and censor scheme under ‘OR’ and ‘AND’ fusion rules in CSS, assuming that all sensors enjoy the same average SNR. As such, they are able to formulate the energy efficiency as a joint optimization problem and derive the optimal decision thresholds and sleeping rates which reduce the average energy consumption of each sensor.…”

“…Previous works have shown that under the constraints of global detection probability and global false alarm probability [ 9 ], the energy efficiency of the system can be formulated as a joint optimization problem, i.e., finding the optimal values of decision threshold and sleeping rates consuming the least energy, which does reduce the energy consumption of the whole CSS system [ 10 , 11 ]. Due to the complexity of the joint optimization problem, certain assumptions, such as a flat-fading environment with all sensors having equal SNR, are needed in order to reduce the size of numerical searches in finding the optimal solution.…”

To AND or To OR: On Energy-Efficient Distributed Spectrum Sensing With Combined Censoring and Sleeping

“…This work is supported in part by the NWO-STW under the VICI program (project 10382), the National Research Fund, Luxembourg under the projects SeMIGod, SATSENT and the European FP7 Project CoRaSat. Parts of this paper has been presented at ICC 2014, Sydney, Australia [41].…”