3 research outputs found
Cooperation and Underlay Mode Selection in Cognitive Radio Network
In this research, we proposes a new method for cooperation and underlay mode
selection in cognitive radio networks. We characterize the maximum achievable
throughput of our proposed method of hybrid spectrum sharing. Hybrid spectrum
sharing is assumed where the Secondary User (SU) can access the Primary User
(PU) channel in two modes, underlay mode or cooperative mode with admission
control. In addition to access the channel in the overlay mode, secondary user
is allowed to occupy the channel currently occupied by the primary user but
with small transmission power. Adding the underlay access modes attains more
opportunities to the secondary user to transmit data. It is proposed that the
secondary user can only exploits the underlay access when the channel of the
primary user direct link is good or predicted to be in non-outage state.
Therefore, the secondary user could switch between underlay spectrum sharing
and cooperation with the primary user. Hybrid access is regulated through
monitoring the state of the primary link. By observing the simulation results,
the proposed model attains noticeable improvement in the system performance in
terms of maximum secondary user throughput than the conventional cooperation
and non-cooperation schemes
Protocol Design and Stability Analysis of Cooperative Cognitive Radio Users
A single cognitive radio transmitter--receiver pair shares the spectrum with
two primary users communicating with their respective receivers. Each primary
user has a local traffic queue, whereas the cognitive user has three queues;
one storing its own traffic while the other two are relaying queues used to
store primary relayed packets admitted from the two primary users. A new
cooperative cognitive medium access control protocol for the described network
is proposed, where the cognitive user exploits the idle periods of the primary
spectrum bands. Traffic arrival to each relaying queue is controlled using a
tuneable admittance factor, while relaying queues service scheduling is
controlled via channel access probabilities assigned to each queue based on the
band of operation. The stability region of the proposed protocol is
characterized shedding light on its maximum expected throughput. Numerical
results demonstrate the performance gains of the proposed cooperative cognitive
protocol.Comment: Accepted in WCNC 201