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We consider a cognitive radio network of nodes with full duplex capability where Self-Interference Suppression (SIS) is not perfect. We have proposed a new scheme for sensing and transmission of Secondary Users (SUs) with two modes of operation; Cooperative Sensing (CS) mode and Full Duplex Transmit and Receive (FDTR) mode. Cooperative sensing is applied to reduce misdetection probability and to avoid...
At present, spectrum scarcity is a major concern in the field of mobile communication. The necessity of spectrum is increasing gradually because the usage of wireless communication is rising tremendously. Cognitive radio (CR) is capable of dealing with this problem. This is referred to as an intelligent and reconfigurable radio which enables efficient usage of unused spectrum while avoiding any kind...
Secondary User (SU) has a responsibility to seek opportunities of spectrum access through spectrum sensing continuously. Spectrum sensing is a main task in Cognitive Radio (CR) that must be performed to avoid collision with Primary User (PU) and having seamlessly data transmission via license channel. To achieve sensing outcome correctly with tolerable error rate, SU requires sufficient time for sensing...
Opportunistic spectrum access (OSA) is a promising reform paradigm envisioned to address the issue of spectrum scarcity in cognitive radio networks (CRNs). While current models consider various aspects of the OSA scheme, the impact of retrial phenomenon in multi-channel CRNs has not yet been analyzed. In this work, we present a continuous-time Markov chain (CTMC) model in which the blocked/preempted...
Due to the demand of emerging Cognitive Radio (CR) technology to permits using the unused licensed spectrum parts by cognitive users (CUs) to provide opportunistic and efficient utilisation of the white spaces. This requires deploying a CR MAC with the required characteristics to coordinate the spectrum access among CUs. Therefore, this paper presents the design and implementation of a novel Medium...
In this paper, we propose a technique for cooperation and underlay mode selection in cognitive radio networks. 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. Overlay spectrum sharing allows the SU to occupy the spectrum only when the PU is idle. Cooperation (collaboration)...
Cognitive radio sensor network (CRSN) is a novel wireless sensor network, which can effectively alleviate the scarcity of spectrum resource by equipping the cognitive technology. Usually, CRSN deploys numerous sensor nodes around the monitoring area. But the energy and storage of those nodes are both limited. Compared with the centralized CRSN, we focus more on a decentralized situation without the...
The required time for spectrum sensing is critical issue in cognitive radio (CR). Secondary User (SU) must sense license spectrum to seek opportunities as quick as possible. However, quick sensing decreases the fidelity of sensing outcome. Sensing time has a significant impact to the throughput performance. This paper studies the impact of sensing time to the throughput performance at low signal to...
In this paper, we have exploited the novel hybrid-cum-improved spectrum access strategy to significant improvement in the throughput and data-loss rate. This proposed strategy is comprise of hybrid spectrum access and improved frame structure strategies for the cognitive radio communication system. In addition to this, the mathematical expressions of throughput for these approaches are also presented...
An important advantage of cognitive radio is its ability to use the licensed frequency spectrum which is being utilized by the primary users. CR has two major roles viz. sensing and throughput optimization. In contrary to conventional methods of sensing viz. cyclostationarity, matched filter detection, maximum to minimum eigen value method etc., spectrum sensing has been improved by implementing Peak...
Recently there have been numerous studies exploring the benefits of the coalition formation in a cognitive radio network and it has been shown that coalition formation tends to improve the performance of cognitive radio networks. In this paper, we use the concepts from matching theory to form coalitions of varying size among cognitive radio users for cooperative spectrum sensing under target detection...
In this paper we consider distributed cognitive radio networks (CRNs) with channel aggregation (CA) scheme where there are multiple wireless channels and multiple secondary users (SUs). SUs in CRNs with CA can transmit bits of data through more than one idle channels which are not used by primary users (PUs). SUs decide whether to access idle channels or not based on the access probability (AP), and...
The novel method for increasing the data transmission throughput in OFDMA based Cognitive Radio system was proposed. The vacant spectrum which the primary OFDMA user is not using consists of even or odd subcarriers in IFFT. If the secondary user transmits data set using only even or odd subcarriers of vacant IFFT subcarriers, such a generated OFDMA symbol has symmetrical waveform. It is possible to...
In this paper, a distributed fair algorithm is proposed to address the resource allocation problem in the cognitive femtocell network. The cognitive functionalities equipped in femtocells enable us to effectively identify the qualified resource blocks (RBs), thus we can mitigate inter-cell interference. By exploiting the satisfaction degree and the channel state difference, the proposed distributed...
One of the major challenges in Dynamic Spectrum Access (DSA) systems is to guarantee a required level of Quality of Service (QoS) to secondary users of the spectrum. In this paper, we propose efficient algorithms for deriving optimal policies for the sensing / transmitting trade-off in hardware-constrained DSA systems. Unlike previous approaches which seek to maximize mean data rate for the secondary...
One of the approaches in cognitive radio is the opportunistic spectrum access (OSA), which enables secondary users (SUs) to access the licensed frequency bands that are detected to be idle. Though there have been a few updates on the throughput aspects of SUs in OSA not much work has been done taking into account the sensing errors, spectrum occupancy probabilities as well as the transmission frame...
Spectrum sharing has gained traction in recent years due to the fast reduction of spectrum availability and the growth in the variety of applications that rely on wireless connectivity. This paper presents a novel, database-assisted Medium Access Control (MAC) protocol that allows an Incumbent operator to share its spectrum with a Licensee operator under agreed rules. To facilitate this, the Incumbent...
In this paper artificial neural network (ANN) based cascaded learning for stochastic resonance (SR) noise driven spectrum sensing is proposed for cognitive radio (CR). In the first phase of a two-stage cascaded learning system Backpropagation gradient ascent learning is used to estimate optimal noise standard deviation which has an outstanding performance improvement for the discovery of the existence...
We consider a two-hop underlay cognitive radio network (CRN) in which the secondary relay (SR) harvests energy from the secondary source (SS) before commencing two-hop transmission. During the energy harvesting phase, energy is transmitted in packets of small size followed by a silent intervals in which the relay provides a one-bit feedback. Without any need to pass channel estimates to a central...
All users in Cognitive radio networks (CRN) try to occupy the vacant channels sharing with the primary users and other users in CRN under limited channel utilization. Each selfish user can independently choose his strategy to maximize his own payoff at the Nash equilibrium (NE) state. In this work, we analyze the channel allocation problem of multiple CR users in the presence of interference of Primary...
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