Cognitive Radio Networks

Chen, Kwang‐Cheng; Prasad, Ramjee

doi:10.1002/9780470742020

Cited by 167 publications

(94 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Therefore, the spectrum sharing type of CR is a dynamic spectrum access (DSA) system [4]. In DSA systems, when the wireless terminal (master) attempts to establish a new communication link, the other terminal (slave) may not catch the signal from the master due to access channel mismatch [5]. The rendezvous channel scheme can be used to eliminate this mismatch.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optimization of Learning Time for Learning-Assisted Rendezvous Channel in Cognitive Radio System

Takyu

Takayuki

Fujii

et al. 2015

IEICE Trans. Commun.

View full text Add to dashboard Cite

SUMMARYThis paper derives the optimal learning time for the learning-assisted rendezvous channel. One problem with the dynamic spectrum access system of cognitive radio is access channel mismatch between two wireless terminals. In the learning-assisted rendezvous channel, before exchanging packets for link connection, the rate of channel occupancy by the other system is estimated within the learning time; it is referred to as the channel occupancy rate (COR). High speed packet exchange is made possible by selecting a low COR channel. However, the optimal learning time and the impact of COR estimation errors have not been clarified yet. This paper analyzes the time to rendezvous channel (TTR), where TTR is the time needed to complete the rendezvous with a certain probability. The results indicate that the learning time and TTR have a concave relationship which means that the optimal learning time can be determined.

show abstract

Section: Introductionmentioning

confidence: 99%

“…The rendezvous channel scheme can be used to eliminate this mismatch. The rendezvous channel scheme is the initial connection protocol for finding one another in multiple frequency channels [5].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Learning Time for Learning-Assisted Rendezvous Channel in Cognitive Radio System

Takyu

Takayuki

Fujii

et al. 2015

IEICE Trans. Commun.

View full text Add to dashboard Cite

show abstract

“…The output of Parameter Estimator block is fed to adaptive beamforming where a digital signal processor (DSP) uses cost (error) function for calculating the optimum filter weights using adaptive algorithm (Least Mean Square (LMS)) that generates an array factor for an optimal Signal-to-Interference Ratio (SIR). Specifically, this results in an array pattern, where ideally the maximum of the pattern is placed towards the intended user (SoI) while nulling or attenuating the interfering users (SonI) [1], [3].…”

Section: Background On Sdma Using Sasmentioning

confidence: 99%

“…Efficient source and channel coding as well as reduction in transmission power, transmission bandwidth or both are significantly contributing to this challenging issue. With the advances in digital techniques, the frequency efficiency can be improved by Multiple Access Technique (MAT), which improves mobile users' access to the scarce resources of base station and hence improves the system's capacity [1]. By adding a new parameter of 'space' or 'angle' to the existing family of Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) schemes, a new MAT known as 'Space Division Multiple Access' (SDMA) is established [2].…”

Section: Introductionmentioning

confidence: 99%

Comparison of DoA Estimation Algorithms in SDMA System

2013

View full text Add to dashboard Cite

Original scientific paperWith Space Division Multiple Access (SDMA) schemes employing digital signal processing algorithms in its smart antenna systems, it is possible to improve the system capacity of modern wireless communication systems by enabling user's angular separation. Angular separation ability enhances reception in Signal-of-Interest direction and minimizes interference in Signal-of-Not-Interest direction. Direction of Arrival (DoA) algorithms are used for estimation of a number of incident plane waves on the antenna array and their incidence angles. This paper compares performance of three DoA algorithms: MUSIC, root-MUSIC and Capon applied on the uniform linear array in the presence of uncorrelated white noise. The simulation results show that MUSIC outperformed root-MUSIC and Capon in both required number of snapshots and number of array elements as well as in signal-to-noise ratio requirements.Key words: Capon, DoA estimation, MUSIC, root-MUSIC, MVDR Usporedba algoritama procjene smjera dolaska u sustavima prostorno raspodjeljenog višestrukog pristupa. Korištenjem digitalnih sustava obradbe signala u inteligentnim antenama za sustave prostorno raspodjeljenog višestrukog pristupa, moguće je, ostvarivanjem razlučivanja korisnika po kutu, unaprijediti ukupni kapacitet sustava suvremenih bežičnih komunikacijskih sustava. Mogućnost razdvajanja po kutu pojačava prijam u smjeru korisnog signala i minimizira smetnju iz smjerova smetajućih signala. Algoritmi procjene smjera dolaska se koriste za procjenu broja planarnih valova koji upadaju na antenski niz, te za procjenu njihovih upadnih kutova. Ovaj rad usporeduje kakvoću tri algoritama procjene kuta upada: MUSIC, root-MUSIC i Capon, primijenjenih za uniformni antenski niz u prisustvu nekoreliranog bijelog šuma. Rezultati simulacija pokazuju da je MUSIC algoritam davao najbolje rezultate, u smislu minimalnog potrebnog broja uzoraka, minimalnog broja potrebnih elemenata niza, te u smislu minimalnih potreba odnosa signal-šum.

show abstract

“…The current spectrum allocation regulations assign specific bands to particular services, and grant licensed band access to licensed users only. In a CR network following the hierarchical access model [2], the intelligent radio part allows unlicensed users (secondary users) to access spectrum bands licensed to primary users, while avoiding interference with them. In this model, two approaches to spectrum sharing between primary and secondary users have been considered: spectrum underlay and spectrum overlay.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable Filter Antennas for Pulse Adaptation in Uwb Cognitive Radio Systems

Al‐Husseini¹,

Safatly²,

Ramadan³

et al. 2012

PIER B

View full text Add to dashboard Cite

Abstract-The design of filter antennas with reconfigurable band stops is proposed. They are meant for employment in ultrawideband cognitive radio (UWB-CR) systems, where unlicensed users communicate using adaptive pulses that have nulls in the bands used by licensed users. Neural networks or circuits implementing the Parks-McClellan algorithm can generate such pulses. With filter antennas, reconfigurable bandstop filters are first designed, to induce adaptive nulls in UWB pulses, and are then integrated in the feed line of a UWB antenna. The advantages of this combination are discussed. The filters are based on split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs). The relationship between the SRR and CSRR parameters and the stop band is also studied.

show abstract

Cognitive Radio Networks

Cited by 167 publications

References 0 publications

Optimization of Learning Time for Learning-Assisted Rendezvous Channel in Cognitive Radio System

Optimization of Learning Time for Learning-Assisted Rendezvous Channel in Cognitive Radio System

Comparison of DoA Estimation Algorithms in SDMA System

Reconfigurable Filter Antennas for Pulse Adaptation in Uwb Cognitive Radio Systems

Contact Info

Product

Resources

About