6 research outputs found
On the Stable Throughput of Cooperative Cognitive Radio Networks with Finite Relaying Buffer
In this paper, we study the problem of cooperative communications in
cognitive radio systems where the secondary user has limited relaying room for
the overheard primary packets. More specifically, we characterize the stable
throughput region of a cognitive radio network with a finite relaying buffer at
the secondary user. Towards this objective, we formulate a constrained
optimization problem for maximizing the secondary user throughput while
guaranteeing the stability of the primary user queue. We consider a general
cooperation policy where the packet admission and queue selection
probabilities, at the secondary user, are both dependent on the state (length)
of the finite relaying buffer. Despite the sheer complexity of the optimization
problem, attributed to its non-convexity, we transform it to a linear program.
Our numerical results reveal a number of valuable insights, e.g., it is always
mutually beneficial to cooperate in delivering the primary packets in terms of
expanding the stable throughput region. In addition, the stable throughput
region of the system, compared to the case of infinite relaying queue capacity,
marginally shrinks for limited relaying queue capacity.Comment: 5 pages, IEEE PIMRC 201
On the Stable Throughput of Cooperative Cognitive Radio Networks with Finite Relaying Buffer
Abstract-In this paper, we study the problem of cooperative communications in cognitive radio systems where the secondary user has limited relaying room for the overheard primary packets. More specifically, we characterize the stable throughput region of a cognitive radio network with a finite relaying buffer at the secondary user. Towards this objective, we formulate a constrained optimization problem for maximizing the secondary user throughput while guaranteeing the stability of the primary user queue. We consider a general cooperation policy where the packet admission and queue selection probabilities, at the secondary user, are both dependent on the state (length) of the finite relaying buffer. Despite the sheer complexity of the optimization problem, attributed to its non-convexity, we transform it to a linear program. Our numerical results reveal a number of valuable insights, e.g., it is always mutually beneficial to cooperate in delivering the primary packets in terms of expanding the stable throughput region. In addition, the stable throughput region of the system, compared to the case of infinite relaying queue capacity, marginally shrinks for limited relaying queue capacity
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