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In this paper, the 3-D Markov analytical model for cognitive radio networks of [1] are replaced by out proposed new 2-D Markov analytical model with considerable low complexity to evaluate the performance of Ad-Hoc Cognitive Radio Networks, and the theory mistakes of [1] are corrected. Compared with the existing 3-D Markov analytical model for cognitive radio networks, our approach has achieved the...
Cognitive radio (CR) systems can enhance the licensed spectrum efficiency by finding and allocating the underutilized channels of the primary users to the secondary users. After scanning a wide range of spectrum. A general CR system needs to utilize all the available channels of various bandwidths. Whenever the active primary users appear, the secondary users shall return the borrowed channels, causing...
We study the cooperative spectrum sensing in cognitive radio networks using hidden Markov model (HMM) for opportunistic spectrum access (OSA). We assume that the primary channel is operating in a TDMA manner. Thus, the spectrum sensing is operating in a slot-by-slot basis. A HMM is used for studying the cooperative spectrum sensing. In contrast to the conventional Bayesian update using only one observation...
In this paper, we investigate the random access for an energy harvesting secondary user (SU) in a cognitive radio system, in which the SU harvests energy from radio frequency (RF) radiation of the primary user (PU). With multipacket reception channel model, the SU can increase its throughput through not only utilizing the idle periods of the PU, but also opportunistically sharing the PU spectrum with...
This paper investigates the resource allocation problem in a relay-aided cognitive radio (CR) system under the orthogonal frequency division multiplexing (OFDM) transmission. Different from the conventional CR resource allocation problem, the relay node here is capable of performing subcarrier permutation over two hops such that the signal received over a particular subcarrier is forwarded on a different...
Spectrum sensing is adopted to detect the presence of primary users in cognitive radio networks. Considering the sensing overhead, it is not always a good choice that the secondary user senses the channel all the time. In this paper, we propose an opportunistic spectrum sensing decision method according to the primary user's traffic. First, the traffic of primary user is observed and estimated. For...
This paper investigates how to characterize the effect of multiple spectrum handoff delay on the extended data delivery time of the secondary users' connections in cognitive radio (CR) networks. Whenever a primary user appears, the spectrum handoff procedures are initiated for the interrupted secondary users. Through spectrum sensing, the secondary user can reactively decide the target channel for...
One of the most challenging issues in cognitive radio networks is when and how often to sense the availability of licensed spectrum. Adopting the fixed sensing period to detect signals, the conventional periodic spectrum sensing method is inefficient or even not able to satisfy the various demands of secondary users. In this paper, we propose a non-periodic sensing (NPS) mechanism, which reduces the...
Channel allocation in cognitive radio networks completely determines the realizability and efficiency of cognitive radio since it is the final step before the cognitive subscribers can use the spectrum holes. In this paper, we consider channel allocation in cognitive radio networks as a resource allocation problem under the circumstance that the allocation of transmission rate, link and transmission...
In cognitive radio networks, multiple spectrum opportunities can be used together to satisfy the service requirement by spectrum aggregation. In this paper, an admission control algorithm and a spectrum assignment strategy are proposed in order for both increasing the spectrum aggregation aware access capacity and decreasing the channel switch times when the channel states change. Considering different...
In this paper, we discuss the spectrum management technologies including spectrum sensing, spectrum decision, spectrum sharing, and spectrum handoff schemes in cognitive radio (CR) networks. In order to evaluate performance of different spectrum management schemes, the preemptive resume priority (PRP) M/G/1 queuing model is suggested to characterize the spectrum usage behavior between the primary...
In this paper, an optimal resource allocation scheme is proposed for multi-user multi-channel cognitive radio networks under imperfect spectrum sensing. The channel dynamic model and the sensing errors are considered together to derive the metric of mean delay for each user-channel combination based on the vacation queueing model. Finally, the optimal resource allocation is determined according to...
Aiming at the power control in cognitive radio, a power control game algorithm based on interference temperature is discussed, and non-cooperative power control game which is created by David Goodman is used. The efficiency function was mended, and we also designed a new pricing function with interference temperature. Compared with other power control game models, the simulation shows that the NPG-ITLP...
Recent studies have been conducted to indicate the ineffective usage of licensed bands due to the static spectrum allocation. In order to improve the spectrum utilization, the cognitive radio is therefore suggested to dynamically exploit the opportunistic primary frequency spectrums. The interference from the secondary users to the primary user consequently draws the attention to the spectrum and...
In this paper, we consider a noncooperative cognitive radio network with M selfish secondary users (SUs) opportunistically access N licensed channels. Every SU chooses one channel to sense and subsequently compete to access (based on the sensing outcome) to obtain the channel utility. Different channels may have different utilities. Each SU selfishly makes a sensing decision to maximize its obtained...
Cognitive radio makes it possible for an unlicensed user to access a licensed spectrum opportunistically on the basis of non-interfering. This paper addresses the problem of joint route selection and resource allocation in OFDMA-based multihop cognitive radio networks, in the objective of optimizing different types of end-to-end performance. Aiming to solve it optimally, we first show that this problem...
A cognitive OFDM-based relay network is considered in this paper. Communication between any node pair occurs on a spectrum pool of OFDM subcarriers where the subcarriers are not used by primary users. Therefore, the available spectrum for different transmitter-receiver pairs is distinct due to their location difference and so on. To satisfy different traffic demand and improve system performance,...
As the first step in the basic cognitive cycle, spectrum sensing is a vital part of cognitive radio to become reliant and swift. And due to excellent detection performance, cooperative spectrum sensing has been applied more and more frequently. However, in cooperative spectrum sensing, the detection results of the secondary users (SUs) have a great degree of uncertainty. In this paper, in order to...
Spectrum sharing is of special significance among all the key technologies in cognitive radio (CR), such as spectrum sensing, spectrum management and power allocation etc. Since all the efforts in CR directly aim at enhancing spectrum utilization and spectrum sharing is the final step of all these key technologies, spectrum sharing completely determines whether CR is just a theoretical topic or a...
In this paper, we study the spectrum selection problem in cognitive radio network with emphasis on resolving the channel contention and the spectrum sharing issues of multiple secondary users. For the traditional channel selection methods, the secondary users select their operating channels based on various criteria. However, these methods neglect the effect that multiple secondary users may content...
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