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In this paper, we propose a cognitive interference management approach, called fractional frequency donation, to alleviate co-channel interference among selfish femtocells. In such networks, our approach allows each femtocell to access all available bands but requires good femtocells with high throughput to "donate" some bands to poor ones. When the donors and the corresponding donated bands...
Cooperative spectrum sensing improves detection performance over fading and shadowing channels by using multiple cognitive radio (CR) users. Compared with local spectrum sensing with individual CR user, it can either reduce sensitivity requirements for each CR user or shorten the overall sensing duration. These advantages are from spatial diversity when all cooperative users sense a common primary...
Most of existing works on spectrum sensing detect primary transmitters while the purpose of spectrum sensing is to avoid interfering with primary receivers (PRs). Therefore, it is more important to detect PRs. In this paper, we propose a proactive spectrum sensing method that detects whether a PR is within the coverage or the interference range of a CR transmitter by exploiting the close-loop power...
In this paper, we propose a relay-assisted transmission scheme in cognitive radio (CR) to exploit spatial spectrum holes, which are generated by relay techniques. The proposed scheme enables CR users to coexist with primary users at the same time in the same geographic area and spectrum band. Compared to conventional schemes, a higher spectrum efficiency is achieved by our method. We further analyze...
In this paper, we propose a cognitive radio (CR) transmission scheme, which enables secondary users to coexist with primary users by exploiting spatial spectrum holes (SSHs) through directional antennas or antenna arrays with beamforming. To ensure reliable CR links and avoid interference to primary users, some CR users may act as relays . We investigate successful communication probability of CR...
To take advantage of time-varying spectrum opportunities, a cognitive radio (CR) user continuously monitors the dynamic usage of the licensed frequency band and is allowed to utilize the spectrum resource when it does not cause unacceptable interference with licensed users. In this paper, the transmit power control scheme for each data transmission between periodic spectrum sensing activities is proposed...
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