• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.21-27
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• 2013

This paper proposes an adaptive modulation based incremental hop selection scheme which improves network coverage in half-duplex multi-hop networks. The proposed scheme guarantees wide coverage through the operation of multi-hop network while preventing spectral efficiency loss due to the usage of multiple time phases in the half-duplex protocol. Also, we evaluate the average spectral efficiency performance over Nakagami-m fading channel. The simulation results show that the proposed scheme outperforms the existing schemes and the derived evaluation is valid.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.924-944
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• 2014

This paper investigates the power allocation and outage performance of MIMO full-duplex relaying (MFDR), based on orthogonal space-time block codes (OSTBC), in cognitive radio systems. OSTBC transmission is used as a simple means to achieve multi-antenna diversity gain. Cognitive MFDR systems not only have the advantage of increasing spectral efficiency through spectrum sharing, but they can also extend coverage through the use of relays. In cognitive MFDR systems, the primary user experiences interference from the secondary source and relay simultaneously, owing to full duplexing. It is therefore necessary to optimize the transmission powers at the secondary source and relay. In this paper, we propose an optimal power allocation (OPA) scheme based on minimizing the outage probability in cognitive MFDR systems. We also analyse the outage probability of the secondary user in noise-limited and interference-limited environments in Nakagami-m fading channels. Simulation results show that the proposed schemes achieve performance improvements in terms of reducing outage probability.