Abstract
In this paper, we introduce a four-dimensional continuous-time Markov chain model to evaluate the performance of cognitive radio networks. In such networks, secondary (unlicensed) users may opportunistically use the frequency channels not currently occupied by primary (licensed) users in order to increase the utilization of the wireless spectrum. Secondary users perform channel sensing before as well as during transmission in order not to interfere with primary users. The proposed model assumes that primary users arrive according to a bursty arrival process and moreover takes the possible occurrence of sensing errors (false alarms and misdetections) into account. Several performance measures including the collision rate between primary and secondary users, the blocking probabilities of primary or secondary users, and the mean delay of secondary users are derived and illustrated through numerical examples. The results show that the system performance strongly depends on the degree of burstiness in the arrival process of primary users. It is also observed that the quality of service of the primary network can be seriously compromised due to misdetection by secondary users.
Highlights
IntroductionIn case of a misdetection of a primary users (PUs), a secondary users (SUs) fails to detect the actual presence of a PU, which results in a collision between the PU and the SU and the loss of both users
Cognitive radio networks (CRNs) are an efficient paradigm to address the scarcity of the wireless spectrum [1, 2]
Two types of networks operate simultaneously. e first type is a primary network that owns the spectrum and coordinates the access of primary users (PUs) to individual channels. e second type is a secondary network where secondary users (SUs) are allowed to make use of the channels not occupied by PUs. e sole purpose of the secondary network is to increase the utilization of the underutilized spectrum
Summary
In case of a misdetection of a PU, a SU fails to detect the actual presence of a PU, which results in a collision between the PU and the SU and the loss of both users Both kinds of SU sensing errors can occur before and during a SU transmission. Mathematical Problems in Engineering by a PU, and class-B misdetection occurs when a transmitting SU fails to detect the arrival of a PU on the channel In this paper, both kinds of sensing errors are considered.
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