861 research outputs found
Design and Optimal Configuration of Full-Duplex MAC Protocol for Cognitive Radio Networks Considering Self-Interference
In this paper, we propose an adaptive Medium Access Control (MAC) protocol
for full-duplex (FD) cognitive radio networks in which FD secondary users (SUs)
perform channel contention followed by concurrent spectrum sensing and
transmission, and transmission only with maximum power in two different stages
(called the FD sensing and transmission stages, respectively) in each
contention and access cycle. The proposed FD cognitive MAC (FDC-MAC) protocol
does not require synchronization among SUs and it efficiently utilizes the
spectrum and mitigates the self-interference in the FD transceiver. We then
develop a mathematical model to analyze the throughput performance of the
FDC-MAC protocol where both half-duplex (HD) transmission (HDTx) and FD
transmission (FDTx) modes are considered in the transmission stage. Then, we
study the FDC-MAC configuration optimization through adaptively controlling the
spectrum sensing duration and transmit power level in the FD sensing stage
where we prove that there exists optimal sensing time and transmit power to
achieve the maximum throughput and we develop an algorithm to configure the
proposed FDC-MAC protocol. Extensive numerical results are presented to
illustrate the characteristic of the optimal FDC-MAC configuration and the
impacts of protocol parameters and the self-interference cancellation quality
on the throughput performance. Moreover, we demonstrate the significant
throughput gains of the FDC-MAC protocol with respect to existing half-duplex
MAC (HD MAC) and single-stage FD MAC protocols.Comment: To Appear, IEEE Access, 201
Energy-Efficient Cooperative Cognitive Relaying Schemes for Cognitive Radio Networks
We investigate a cognitive radio network in which a primary user (PU) may
cooperate with a cognitive radio user (i.e., a secondary user (SU)) for
transmissions of its data packets. The PU is assumed to be a buffered node
operating in a time-slotted fashion where the time is partitioned into
equal-length slots. We develop two schemes which involve cooperation between
primary and secondary users. To satisfy certain quality of service (QoS)
requirements, users share time slot duration and channel frequency bandwidth.
Moreover, the SU may leverage the primary feedback message to further increase
both its data rate and satisfy the PU QoS requirements. The proposed
cooperative schemes are designed such that the SU data rate is maximized under
the constraint that the PU average queueing delay is maintained less than the
average queueing delay in case of non-cooperative PU. In addition, the proposed
schemes guarantee the stability of the PU queue and maintain the average energy
emitted by the SU below a certain value. The proposed schemes also provide more
robust and potentially continuous service for SUs compared to the conventional
practice in cognitive networks where SUs transmit in the spectrum holes and
silence sessions of the PUs. We include primary source burstiness, sensing
errors, and feedback decoding errors to the analysis of our proposed
cooperative schemes. The optimization problems are solved offline and require a
simple 2-dimensional grid-based search over the optimization variables.
Numerical results show the beneficial gains of the cooperative schemes in terms
of SU data rate and PU throughput, average PU queueing delay, and average PU
energy savings
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