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In this work we investigate an auction mechanism for sharing available wireless bandwidth among competing cognitive radios. The bandwidth under consideration may be either in an unlicensed spectrum or in an unused licensed band. Spectrum sharing is achieved via a mechanism in which a cognitive radio acting as the auctioneer advertises spectrum availability to bidding cognitive radios and defines a...
The high peak to average power ratio (PAPR) and large spectrum sidelobe power are the two major limitations at the transmitter side of the NC-OFDM based Cognitive Radio (CR) system, which may significantly reduce the power efficiency and performance of the system. There are many techniques in the literature to reduce high PAPR and large spectrum sidelobe power. In this paper, we present a new optimization...
Cognitive radio (CR) allows unauthorized users to access authorized band without interfering the authorized user, thereby improving the bandwidth efficiency. In addition, cooperative communications with relay stations (RSs) can be used to improve throughput performance of 4G downlink network. In this study a cognitive radio assisted cooperation (CRAC), which combines advantages of CR and cooperative...
In this paper, we propose an anti-interference cooperative spectrum sharing strategy based on fairness secondary users selection where the secondary system can gain spectrum access to the primary system. Specifically, secondary user STb and STq are selected to transmit the primary and secondary signal by using different bandwidth in the second transmission slot which occupies a part of the whole transmission...
In this paper, we propose a new cooperative spectrum sensing scheme for cooperative energy detection, named multi-selective scheme. The proposed cooperative sensing scheme is based on order statistics of the reporting links between the cooperative nodes and fusion center where the links with high signal-to-noise ratios (SNRs) are selected as reliable reporting links. The performance of the proposed...
In this paper, we investigate the achievable rate and the average sum capacity of an underlay cognitive radio (CR) (also known as a secondary) system. We consider single user (SU) and multiple users (MU) secondary systems that deploy spread spectrum as the signaling technique which utilizes the whole available spectrum. The objective is to maximize the achievable rate and the average sum capacity...
In this paper, a new dynamic access scheme is proposed which differentiates secondary users (SUs) on the basis of their type: voice or data call. A voice call is preferred over a data call in the paper. If a primary user (PU) wants to access the spectrum, then a SU with data call will be placed in buffer. If no SU with data call is accessing the spectrum, then one of the SU with voice call will give...
Research about multimedia streaming in cognitive radio network has become a hot issue recently. In order to enhance the throughput of real-time multimedia streaming and maximize the utility, we proposes a dynamic spectrum allocation strategy based on Qos-layering and auction theory (QLAS). In this strategy, we classify the secondary users according to the feature of data stream, and choose the optimal...
Among the many problems faced in the world of wireless Technology, the most significant one is spectrum scarcity. In terms of pure facts, the TRAI auction of spectrum bands scheduled in 2016 will generate a base price of 5.36 Lakh crores which is more than twice the revenue of major telecom providers which is around 2.5 lakh crores. This Paper proposes an algorithm which guides efficient utilization...
In a cognitive radio network (CRN), allocating spectrum resources to terminals is a fundamental problem due to dynamic characteristics of wireless spectrum. However, distributed spectrum allocation schemes are usually sub-optimal due to lack of global information, and existing centralized schemes merely assume the existence of global information collection method without implementing the protocol...
Rapid growth of new wireless devices and application increases demand of wireless radio spectrum. Static spectrum allocation is unable to fulfill users' demands which result in bottleneck condition. Cognitive radio provides efficient solution over bottleneck condition which arrived due to fixed spectrum assignment policy. Dynamic spectrum management is promising technique of cognitive radio to fulfill...
Accurate sensing of the spectrum is one of the prime requirements for efficient functioning of cognitive Radio systems. But accurate sensing is a complex process, as signals of different modulations, coding methods and power levels along with fading and noise are present in the given radio environment. Collaborative sensing techniques can help to improve the sensing accuracy. One such collaborative...
Cognitive radio networks play a vital role in solving the problem of underutilization of spectrum by identifying unused licensed radio spectrum. They solve the problem by distributing this unused spectrum among unlicensed users in an intelligent fashion without interfering with existing users. In this paper, using the conflict graph and graph colouring concepts, a Graph Colouring based Dynamic Channel...
Adjacent channel interference (ACI) is often not considered when spectrum sharing schemes are designed for cognitive radio networks (CRNs). In practice, it is necessary to avoid interference by deploying guard bands between two distinct receptions. However, using guard bands typically reduces spectrum efficiency. In this work, we study the impact of guard bands on spectrum efficiency under different...
Dynamic spectrum sensing and opportunistic access in cognitive communications enable secondary users to recognize and utilize the white spaces of the licensed bandwidth. Our prior work proposed a non-uniform scheme of bandwidth partition and traffic allocation with the aim of regularizing the primary user's (PU's) bandwidth occupancy pattern, which was able to improve the performance of the secondary...
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...
A cognitive radio system coexisting with various systems must perform a spectrum sensing for finding a white space (WS). In this paper, we propose a new two-stage spectrum sensing method using an energy detection (ED) based on fast Fourier transform (FFT). In the case that an unknown signal is present the FFT band, false signals are detected in the surrounding FFT bins of the received signal due to...
A cognitive radio system coexisting with various systems must perform a spectrum sensing for finding a white space (WS). In this paper, we propose a new two-stage spectrum sensing method using an energy detection (ED) based on fast Fourier transform (FFT). In the case that an unknown signal is present the FFT band, false signals are detected in the surrounding FFT bins of the received signal due to...
This paper focuses on the quantization of soft decision based cooperative spectrum sensing (CSS). The soft data fusion CSS schemes in previous research works provide considerable enhancement in the probability of detection, but at the expense of increased bandwidth required for transmitting the sensing measurements to the Fusion Center (FC). In this paper, Maximum likelihood Estimation (MLE) statistics...
The benefits of network layer cooperation cognitiveradio networks have been gradually recognized in recent years. In this paper we consider the network layer cooperation incognitive radio network, whereby primary users select somesecondary users to relay packets, in return for more favourablespectrum access rules for secondary users. Under this cooperationscheme, we investigate how to enlarge the...
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