TITLE:
Throughput Maximization Based on Optimal Access Probabilities in Cognitive Radio System
AUTHORS:
Mohamed Elalem, Lian Zhao
KEYWORDS:
Cognitive Radio; Access Probability; Underlay/Overlay Schemes; Marckov Model
JOURNAL NAME:
Communications and Network,
Vol.5 No.3,
August
2,
2013
ABSTRACT: Well-established
fact shows that the fixed spectrum allocation policy conveys to the low
spectrum utilization. The cognitive radio technique promises to improve the low
efficiency. This paper proposes an optimized access strategy combining overlay
scheme and underlay scheme for the cognitive radio. We model the service state
of the system as a continuous-time Markov model. Based on the service state,
the overlay manner or/and the underlay manner is/are used by the secondary
users. When the primary user is not transmitting and only one secondary user
has the requirement to transmit, the secondary system adopts the overlay
scheme. When the primary user is transmitting and the secondary users want to
transmit simultaneously, an underlay scheme with an access probability is
adopted. We obtain the optimal access probability in a closed form which
maximizes the overall system throughput.