414 Industrial Electronics and Engineering
WIT Transactions on Engineering Sciences, Vol. 93, © 2014 WIT Press
www.witpress.com, ISSN 1743-3533 (on-line)
Cognitive users utilize spectrum detection algorithm to research idle spectrum,
meanwhile, analyze the throughput of cognitive users in cognitive radio networks
(CRN) to avoid interrupting primary users [2]. In CRN without center, cognitive
users are lack of cooperation, thus the result of spectrum detection often has a
low precision rate so that the collision would be happen between users when
transporting data. The existing papers pay less attention to this topic [3].
In [4], a cloud server-assisted media access control (MAC) protocol for
infrastructure-based CRN was presented. When multi-SU detect the same
spectrum of PU, SUs report channel qualities to cloud servers by CR access
points. Based on the collected information, cloud servers could estimate how
much time SUs should spend on sensing a data channel. Then the collision
probability could be reduced. In [5], an improved MAC protocol based on the
minimum sampling time (MST) was presented. It’s useful for improving reliable
transmission and data throughput of SUs.
With the rapid development of cloud computing, a new concept of cognitive
wireless communication systems, “Cognitive Wireless Clouds (CWC)” was
proposed in [6]. It’s composed of huge number of networks and terminals, the
CWC will make it possible to utilize spectrum very efficiently. In this system, the
CWC could optimize CR technique in the matter of cognitive spectrum access,
resource utilization, fast reconfiguration [7,8]. It’s hard to reduce the collision
probability of SUs in CRN without center. However, based on cloud computing,
the CWC could estimate PU’s status, analyze the SUs’ traffic, and control the
behavior of SU. Making use of the scalability and the vast storage and computing
capacity of the cloud, cooperative spectrum sensing and resource scheduling can
be efficiently implemented [9]. Cognitive cloud network based on cloud
computing could control the behavior of SUs timely and efficiently. Instead of
completing complex computation for cognitive users, it reduces the collusion
probability. Thereby cloud computing promotes the progress of cognitive radio.
This paper utilizes the powerful computation capability of cloud to solve the
problem of collision between cognitive users while transporting data in cognitive
radio network. We analyzed the traffic λ of all users (include PUs and SUs) in
CRN and derived unreliable detection probability of cognitive users as objective
function, then controlled the data transmission time of cognitive users so as to
reduce the collision probability and enhance throughput of cognitive users.
The rest of this paper is organized as follows. System model is presented in the
next section. The unreliable detection area is worked out in Section 3. Section 4
introduces the prioritization scheme about optimizing the adaptive data
transmission time. Section 5 presents and discusses the simulation results, while
Section 6 concludes the paper.
2 System model
The system model is cognitive radio network based on cloud computing which is
discussed in [10], as shown in Figure 1. It includes cloud server, cognitive
network access point (AP), primary user (PU), and secondary user (SU). Besides,
cloud servers are used to support the computation overhead of PUs’ location and