Abstract
We propose a spectral and energy efficient cooperative spectrum sharing scheme with the primary user (PU) capable of harvesting wireless energy. Along with an access point (AP) transferring wireless power to PU, a secondary source (SS) and a secondary relay (SR) can cooperatively transmit data to a secondary destination (SD) using the amplify-and-forward protocol. The interference from secondary transmissions can boost the amount of harvested energy at PU. After the wireless power transfer phase, PU transmits data to AP using the harvested energy, and meanwhile SS transmits data to SD. The SR could simultaneously forward the data of both systems to improve their communication qualities. With the energy and data cooperations from SS and SR, more energy can be harvested by PU and the data reception at AP becomes more reliable, so the throughput performance of primary system can be satisfied more easily. As a result, a fraction of spectrum could be enough for the primary system and the remaining spectrum is released to the secondary system. The optimal time and bandwidth factors are determined to maximize the throughput of secondary system under the performance constraint of primary system. The numerical results show that our proposed scheme significantly outperforms the non-cooperative scheme in terms of system throughput.
Highlights
Spectrum sharing in cognitive radio networks (CRN) is a promising solution to increase the spectrum utilization efficiency by allowing secondary users (SUs) to opportunistically access the spectrum unused by primary users (PUs) [1]
The cooperation from SUs can enhance the reliability of primary system by introducing the space diversity, as a result the whole spectrum can be accessed by SUs in a separate time [2], or a fraction of disjoint bandwidth can be allocated to the secondary system [3], or SUs can simultaneously access the spectrum with PUs [4]
We study the cooperative spectrum sharing with PUs capable of harvesting energy
Summary
Spectrum sharing in cognitive radio networks (CRN) is a promising solution to increase the spectrum utilization efficiency by allowing secondary users (SUs) to opportunistically access the spectrum unused by primary users (PUs) [1]. To further enhance the energy and spectral efficiency, a full-duplex EH relay can be adopted to simultaneously receive and transmit signals from source and towards destination and recycle the radiated energy [20] If both the source and relay operate with EH, an access point (AP) can transfer power to them for the uplink data transmission [21], [22] or both the source and relay can harvest energy from each other [23]. To further enhance the spectral efficiency, SUs can cooperatively transmit data using the DF protocol along with the WPT of primary system, so PUs will harvest more energy and transmit with higher powers, which can tolerate more interference from the SUs’ spectrum access [40].
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