Abstract
With the rapid development of cognitive radio
technologies, spectrum sharing becomes a promising
approach to improving the efficiency of spectrum
utilization and mitigating the spectrum scarcity problem.
Previous research on cognitive networks argues that
secondary users can only work under a low-transmission
power in an underlay spectrum sharing model, especially
when the primary transmitter is far away from the primary
receiver. Motivated by the idea of cooperative
communications, in this paper, we propose a cooperative
framework in which a primary transmitter, being aware of
the existence of the secondary network, may select a
secondary user that is not in transmitting or receiving
mode to relay its traffic. The feasible relay location
region and optimal power ratio between the primary
network and the secondary network are derived in the
underlay spectrum sharing model. Based on the optimal
power ratio, we derive the maximum achievable
transmission capacity of the secondary network under the
outage constraints from both the primary and the
secondary network with or without cooperative relaying.
Numerical results indicate that secondary users can
achieve a higher transmission capacity with cooperative
relaying, and that the capacity gain of the cooperative
network is significantly affected by the location of the
relay and the network system parameters.
Original language | English |
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Number of pages | 15 |
Journal | EURASIP Journal on Wireless Communications and Networking |
Volume | 2015 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2015 |
MoE publication type | A1 Journal article-refereed |
Keywords
- achievable transmission capacity
- cognitive radio networks
- cooperative relaying
- outage constraints