Browsing by Author "Erküçük, Serhat"

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Citation - WoS: 7
Citation - Scopus: 9
Detection of Interdependent Primary Systems Using Wideband Cognitive Radios
(Elsevier GMBH Urban & Fischer Verlag, 2013) Yılmaz, Burak; Erküçük, Serhat
Cognitive radios (CRs) may be sharing multiple frequency bands with primary systems if the CR is a wideband or an ultra wideband (UWB) system. In that case the CR should ensure all the coexisting primary systems in these bands are detected before it can start data transmission. In this work we study the primary system detection performance of a wideband CR assuming that there are multiple coexisting primary systems and that these primary systems may be jointly active. Accordingly we consider the implementation of energy detection scheme in multiple bands followed by two detection methods: (i) a maximum-a-posteriori (MAP) based detection (i.e. joint detection) that takes into account the statistics of simultaneously operating systems in independent bands and (ii) a Neyman-Pearson (NP) test based detection that optimizes the threshold values independently in each band (i.e. independent detection). For a simpler implementation of the independent detection we show that the threshold values obtained from joint detection can be used in order to achieve the optimum NP test based independent detection results. In addition to quantifying the gain of joint detection over independent detection in terms of probabilities of false alarm and detection for practical scenarios we also present the operation capability of CRs in terms of the fractions of time the CR can access the channel without interfering with the primary systems. The results are important for the practical implementation of multiband detection when the primary systems are known to be interdependent. (C) 2013 Elsevier GmbH. All rights reserved.
Citation - WoS: 5
Citation - Scopus: 6
Code Shift Keying Impulse Modulation for Uwb Communications
(IEEE-INST Electrical Electronics Engineers Inc, 2008) Erküçük, Serhat; Kim, Dong In; Kwak, Kyung Sup
In this paper the system performance of M-ary code shift keying (MCSK) impulse modulation is studied in detail and compared to M-ary pulse position modulation (MPPM) under single- and multi-user scenarios. For that bounds on the semi-analytic symbol-error rate (SER) expressions are derived and simulation studies are conducted. When practical implementations of MCSK and MPPM are considered it is shown that MCSK can provide about 2 dB performance gain over MPPM as it reduces the effects of multipath delays on the decision variables by randomizing locations of the transmit pulse.
Coexistence of Cognitive Radio Based Networks in Tv White Space
(Kadir Has Üniversitesi, 2016) Karatalay, Onur; Erküçük, Serhat
Due to increasing data rates in enhancing wireless communications RF spectrum which is one of the most crucial natural sources has become more valuable. in order to utilize the limited spectrum e_ciently and solve the scarcity problem regulatory agencies granted unlicensed networks or secondary users (SUs) access to licensed bands for wireless communication with the condition that they should not cause harmful interference to primary users (SUs). Cognitive radio (CR) technology enables devices to access the spectrum opportunistically. Using CR based networks licensed bands can be utilized more e_ectively for wireless communications. TV White Space (TVWS) refers to portions of the RF spectrum that was reserved only for licensed terrestrial TV broadcasting and is opened to unlicensed use under regulatory conditions. While regulations protect licensed systems in TVWS from harmful interference interference prevention among unlicensed systems is left mainly to manufacturers. Consequently there is a need to develop new coexistence approaches between TVWS networks. Busy tone broadcasting is a coexistence method which can be used by TVWS networks to announce that the selected frequency band is occupied. in this dissertation a busy tone based coexistence algorithm is proposed for wireless local area networks (WLANs) operating in TVWS (i.e. iEEE 802.11af based networks) where wireless regional area network (WRAN) (i.e. iEEE 802.22 based network) is assumed to be the busy tone broadcaster. The proposed algorithm is analyzed in detail considering the e_ects of log-normal shadowing client distribution around the access point and the number of clients where exact interfering packet rate and successful packet transmission rate expressions are obtained and validated by simulations for di_erent scenarios. The results show that with the proposed coexistence approach a WLAN can reliably detect the busy tone signal to change its frequency band and can reduce interference to WRAN. Even if there is no available frequency band for the WLAN the WRAN still maintains its enhanced successful packet transmission performance. The deployment of the proposed algorithm is important for successful coexistence between cognitive wireless regional and local area networks where interference among networks is not regulated such as in TVWS bands.
Citation - WoS: 1
Busy Tone Implementation for Coexistence of Ieee 802.22 and 802.11 Af Systems
(IEEE, 2015) Karatalay, Onur; Erküçük, Serhat; Baykaş, Tunçer
In this paper a new algorithm based on busy tone approach has been proposed for the coexistence of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier study in addition to 802.11af access points listening to the busy tone signal their clients also listen to the busy tone and let the access points know once they hear it. Accordingly interference caused to 802.22 systems has been reduced. This study quantifies the improved system performance in terms of interfering packet rate for different hearing regions considering the communication parameters and channel models adapted for the standards.
Citation - WoS: 3
Citation - Scopus: 3
Bayesian Compressive Sensing for Ultra-Wideband Channel Estimation: Algorithm and Performance Analysis
(Springer, 2015) Özgör, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
Due to the sparse structure of ultra-wideband (UWB) channels compressive sensing (CS) is suitable for UWB channel estimation. Among various implementations of CS the inclusion of Bayesian framework has shown potential to improve signal recovery as statistical information related to signal parameters is considered. In this paper we study the channel estimation performance of Bayesian CS (BCS) for various UWB channel models and noise conditions. Specifically we investigate the effects of (i) sparse structure of standardized IEEE 802.15.4a channel models (ii) signal-to-noise ratio (SNR) regions and (iii) number of measurements on the BCS channel estimation performance and compare them to the results of -norm minimization based estimation which is widely used for sparse channel estimation. We also provide a lower bound on mean-square error (MSE) for the biased BCS estimator and compare it with the MSE performance of implemented BCS estimator. Moreover we study the computation efficiencies of BCS and -norm minimization in terms of computation time by making use of the big- notation. The study shows that BCS exhibits superior performance at higher SNR regions for adequate number of measurements and sparser channel models (e.g. CM-1 and CM-2). Based on the results of this study the BCS method or the -norm minimization method can be preferred over the other one for different system implementation conditions.
Realistic Performance Considerations for Combinational Cooperative Detection Method
(Kadir Has Üniversitesi, 2016) Samo, Rameez Ahmed; Erküçük, Serhat
Combinational cooperative detection (CCD) method is different from the conventional cooperative detection method in the sense that each user may reach a different decision for the activity of the primary user. in the CCD method the locations of the secondary users (SUs) were fixed and selected near the border points of the communication area. The detection performance for SUs at random locations was not considered earlier. The CCD method’s practical implementation was explained with observing different system parameter’s effects on the detection performance for those fixed locations. Carrying previous work done forward in this thesis some realistic performance considerations for the CCD method are assessed. in accordance with that firstly the effect of SUs random locations on the detection performance is considered and compared with the performance for fixed locations. Secondly the effect of distance variations between master and primary user is tested. Finally the effect of different propagation environments on the detection performance of CCD is examined. The results are important to assess the realistic performance of the CCD method.
Citation - Scopus: 1
Busy Tone Based Power Control For Coordination Of Ieee 802.11af And 802.22 System [ıeee 802.11af ve 802.22 Sistemlerinin Uyumlu Çalışmaları için Meşgul Ton Tabanlı Güç Kontrolü]
(Institute of Electrical and Electronics Engineers Inc., 2017) Ulgen, Oguz; Erküçük, Serhat; Karatalay, Onur; Baykaş, Tunçer
In this paper a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies in addition to both 802.11af access point and clients listening to the busy tone they also adjust their communication power according to the location information and use hopping for communication if needed. Acccordingly interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards. © 2017 IEEE.
Effect of Inter-Block Region on Compressed Sensing Based Channel Estimation in Tds-Ofdm Systems
(IEEE, 2016) Başaran, Mehmet; Erküçük, Serhat; Şenol, Habib; Cirpan, Hakan Ali
Time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) is the basis technology for digital television standard (DTV) employed in some countries thanks to its high spectral efficiency when compared to traditional cyclic prefix OFDM. Moreover it does not require pilot usage in frequency domain channel estimation. Instead of data usage as cyclic prefix pseudo-noise (PN) sequences are transmitted in guard intervals. Due to interference from the previous OFDM data symbol the received signal in guard interval can be decomposed into a small-sized signal that contains only PN sequences utilizing the inter-block-interference (IBI)-free region in the convolution matrix. Due to sparsity multipath fading channel can be obtained by the application of compressed sensing (CS) technique to reconstruct the high-dimensional sparse channel from the decreased-size of received signal through the known PN sequence matrix. In this study the effect of the size of IBI-free region on CS and Bayesian CS (BCS) based channel estimation is investigated. Accordingly reconstruction error performances of basis pursuit (BP) and BCS are compared. Simulation results show that the channel estimation can be improved by trading-off the length of the IBI-free region. However an increase in IBI-free region leads to decreased energy efficiency at both the transmitter and receiver side.
Citation - WoS: 52
Citation - Scopus: 55
Joint Communication and Computing Resource Allocation in 5g Cloud Radio Access Networks
(IEEE-Inst Electrical Electronics Engineers Inc, 2019) Ferdouse, Lilatul; Anpalagan, Alagan; Erküçük, Serhat
Cloud-radio access network (C-RAN) is regarded as a promising solution to manage heterogeneity and scalability of future wireless networks. The centralized cooperative resource allocation and interference cancellation methods in C-RAN significantly reduce the interference levels to provide high data rates. However, the centralized solution is not scalable due to the dense deployment of small cells with fractional frequency reuse, causing severe inter-tier and inter-cell interference turning the resource allocation and user association into a more challenging problem. In this paper, we investigate joint communication and computing resource allocation along with user association, and baseband unit (BBU) and remote radio head (RRH) mapping in C-RANs. We initially establish a queueing model in C-RAN, followed by formulation of two optimization problems for communication [e.g., resource blocks (RBs) and power] and computing [e.g., virtual machines (VMs)] resources allocation with the aim to minimize mean response time. User association along with the RB allocation, interference, and queueing stability constraints are considered in the communication resource optimization problem. The computing resource optimization problem considers BBU-RRH mapping and VM allocation for small cells, constrained to BBU server capacity and queueing stability. To solve the communication and computing resource optimization problem, we propose a joint resource allocation solution that considers a double-sided auction based distributed resource allocation (DS-ADRA) method, where small cell base stations and users jointly participate using the concept of auction theory. The proposed method is evaluated via simulations by considering the effect of bandwidth utilization percentage, signal-to-interference ratio threshold value and the number of users. The results show that the proposed method can be successfully implemented for 5G C-RANs.
Citation - Scopus: 1
The Effect Of Channel Resolution On Compressed Sensing Based Ultra-wideband Channel Estimation [kanal Çözünürlü?ünün Sıkıştırılmış Algılama Tabanlı Ultra Geni?ş Bantlı Kanal Kesti?ri?mi?ne Etki?si?]
(2011) Başaran, Mehmet; Erküçük, Serhat; Cirpan, Hakan Ali
Ultra short pulses are transmitted in Ultra-Wideband (UWB) communications. As a result of this pulses at the receiver can be resolved individually due to the sparse structure of the channel. Due to these properties the UWB channel can be estimated by using a compressed sensing based channel estimation method. The performance of channel estimation depends on the sparsity of the channel. In this work the effect of channel resolution which directly affects the sparsity is examined. It is shown that the channel becomes more sparse and the channel estimation performance is improved with increased channel resolution. Also the system performances of practically used selective-Rake receivers with estimated channels are found to be close to the perfect channel estimation case. © 2011 IEEE.
Enerji Verimli İletişim Sistemlerinin Tasarımı için Sıkıştırılmış Algılama Tabanlı Yaklaşımlar
(2016) Erküçük, Serhat; Çırpan, Hakan Ali
Sıkıstırılmıs Algılama (Compressed Sensing, CS) teorisi, isaretin seyrek bölgede tanımlanabildigi durumlarda Nyquist hızından çok daha düsük hızlarda örneklenen isaretin basarılı bir sekilde geri kazanılabilecegi gerçegine dayanır. Bu dogrultuda gelisen genis bandlı spektrum algılama ve kanal kestirimi arastırma alanları, CS teorisinin iletisim arastırmalarında iki önemli uygulama alanı olmustur. Literatürde önerilmis CS tabanlı spektrum algılama çalısmalarının birçogu, enerji sezimini gerçeklestirebilmek için genis bandlı birincil kullanıcının isaretini, alt-örneklenmis örneklerinden yararlanarak yeniden elde etmek üzerine yogunlasır. Isaretin yeniden elde edilmesi, alıcı karmasıklıgını ve hesaplama süresini arttırabilir ki bu da enerji verimliliginin düsmesine neden olur. Diger taraftan literatürde önerilmis çesitli CS tabanlı kanal kestirim yaklasımları bulunmasına ragmen, yapılan çalısmaların birçogu kanal seyrekliginin ve kanal ortamı yapısının etkileriyle ilgilenmemistir. Gerçekten de seyreklik ve kanal parametrelerinin dagılımı, kanal kestirim performansını etkileyen en önemli faktörlerdendir. Bu durumları dikkate alarak, bu projede (i) genis bandlı birincil isaretin varlıgını, isaretin sıkıstırılmıs örneklerinden yararlanarak kestirmeye çalısan CS tabanlı spektrum algılamanın gerçeklemesine, ve (ii) kanal seyrekliginin ve kanal parametrelerinin etkilerini dikkate alan CS tabanlı kanal kestirim yöntemlerine odaklanılmıstır. CS tabanlı algılamada dogru sezme ve yanlıs alarm analizi gerçeklestirmek ve seyreklik ön bilgisi kullanarak kanal kestirimi gerçeklestirmek mevcut durumu iyilestiren özgün yaklasımlardır. Spektrum algılamada Bayesian sıkıstırılmıs algılama (Bayesian compressed sensing, BCS) teknigi genis band spektrum algılama için uygulanmıstır. Birincil kullanıcının sezim performansı isaret kestirim hatası ile sezim olasılıgı terimleriyle degerlendirilmistir. Geleneksel taban arayısı (basis pursuit, BP) teknigine ek olarak teorik alt sınırlar BCRB ve DL-MSE ile karsılastırılmıs ve üstünlügü ortaya konulmustur. Kanal kestiriminde seyrek ve sembolden sembole degisen kanallarda zamanda eszamanlanmıs OFDM (time domain synchronous OFDM, TDS-OFDM) sistemlerinin semboller arası girisim (inter-block-interference, IBI) içermeyen bölgeleri incelenerek kanal kestirim performansları iyilestirilmistir. Seyrek ve anlık degisen kanallarda ise Uzay Degisimli Genellestirilmis Beklenti-En Büyük Sonsal Olasılık (Space Alternating Generalized Expectation Maximization-Maximum a Posteriori, SAGEMAP) tabanlı algoritma gelistirilmis ve kanal katsayılarının ve çoklu yolların anlık degisimlerinin basarıyla takip edildigi ortaya konulmustur. Ayrıca, enerji verimliligi açısından, CS tabanlı algoritmalar (BP ve açgözlü algoritmalar) teorik alt sınırlarla ve birbirleriyle karsılastırılarak performans ve hesaplama süresi ödünlesimleri sunulmustur.
Citation - WoS: 5
Citation - Scopus: 6
Comparison of Compressed Sensing Based Algorithms for Sparse Signal Reconstruction
(IEEE, 2016) Çelik, Safa; Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
Compressed sensing theory shows that any signal which is defined as sparse in a given domain can be reconstructed using fewer linear projections instead of using all Nyquist-rate samples. In this paper we investigate basis pursuit matching pursuit orthogonal matching pursuit and compressive sampling matching pursuit algorithms which are basic compressed sensing based algorithms and present performance curves in terms of mean squared error for various parameters including signal-tonoise ratio sparsity and number of measurements with regard to mean squared error. In addition accuracy of estimation performances has been supported with theoretical lower bounds (Cramer-Rao lower bound and deterministic lower mean squared error). Considering estimation performances compressive sampling matching pursuit yields the best results unless the signal has a non-sparse structure.
Citation - Scopus: 2
Detection of Multiple Primary Systems Using Daa Uwb-Irs
(IEEE, 2009) Erküçük, Serhat; Lampe, Lutz; Schober, Robert
Underlay ultra wideband (UWB) systems have to be able to detect the presence of primary systems operating in the same band for detect-and-avoid (DAA) operation. In this paper the performances of joint and independent detection of multiple primary systems are investigated assuming that the primary systems are potentially dependent (e.g. frequency division duplex uplink-downlink communications). Joint detection is performed based on generating the maximum a posteriori (MAP) decision variables at the receiver where some bias terms are used with these variables in order to achieve a desired trade-off between the detection and false alarm probabilities. Independent detection is performed based on the Neyman-Pearson (NP) test which optimizes system threshold values individually in order to achieve the best detection probability for a given false alarm probability value. When the two detection schemes are compared it is shown that the gain of joint detection depends on the joint system activity values and the considered receiver operating characteristic (ROC) region where the complementary ROC curves illustrate the trade-off between missdetection and false alarm probabilities.
Citation - WoS: 18
Citation - Scopus: 20
Joint Wavelet-Based Spectrum Sensing and Fbmc Modulation for Cognitive Mmwave Small Cell Networks
(Inst Engineering Technology-IET, 2016) Hosseini, Haleh; Anpalagan, Alagan; Raahemifar, Kaamran; Erküçük, Serhat; Habib, Salman
Millimetre-wave (mmWave) 5G communications is an emerging technology to enhance the capacity of existing systems by thousand-fold improvement. Heterogeneous networks employing densely distributed small cells can optimise the available coverage and throughput of 5G systems. Efficiently utilising the spectrum bands by small cells is one of the approaches that will considerably increase the available data rate and capacity of the heterogeneous networks. This challenging task can be achieved by spectrum sensing capability of cognitive radios and new modulation techniques for data transmission. In this study a wavelet-based filter bank is proposed for spectrum sensing and modulation in 5G heterogeneous networks. The proposed technique can mitigate the spectral leakage and interference by adapting the subcarriers according to cognitive information provided by wavelet packet based spectrum sensing (WPSS) and lowering sidelobes using wavelet-based filter bank multicarrier modulation. The performance improvement of WPSS compared with Fourier-based spectrum sensing is verified in terms of power spectral density comparison and probabilities of detection and false alarm. Meanwhile the bit error rate performance demonstrates the superiority of the proposed wavelet-based system compared with its Fourier-based counterpart over the 60 GHz mmWave channel.
Citation - WoS: 1
Citation - Scopus: 1
Performance of Ieee 802.15.4a Systems in the Presence of Narrowband Interference
(IEEE, 2011) Fındıklı, Çağlar; Erküçük, Serhat; Çelebi, Mehmet Ertuğrul
The regulatory agencies in Europe and Japan require the implementation of avoidance techniques in some bands to reduce interference to licensed systems. Accordingly ultra-wideband impulse radio (UWB-IR) based Wireless Personal Area Network (WPAN) standard IEEE 802.15.4a has suggested using linear combination of pulses to reduce interference to coexisting primary systems. In this paper we consider the implementation of linear combination of pulses for a peaceful coexistence and assess the UWB-IR system performance in the presence of an active narrowband system. For that we study the possible transmitter and receiver structures that can be adapted for the physical layer of the IEEE 802.15.4a standard. The study shows that while the bit-error rate (BER) performances of coherent and noncoherent receiving structures may be slightly degraded with the use of linear combination of pulses when there is no active primary system the performances can be significantly improved with appropriate filtering techniques at the receiver when the primary system is active.
Citation - WoS: 3
Citation - Scopus: 4
Busy Tone Based Coexistence Algorithm for Wran and Wlan Systems in Tv White Space
(Inst Engineering Technology-IET, 2018) Karatalay, Onur; Erküçük, Serhat; Baykaş, Tunçer
TV White Space (TVWS) refers to frequency band reserved only for licensed terrestrial TV broadcasting and is opened to unlicensed use under regulatory conditions. While regulations protect licensed systems from interference interference among unlicensed systems is left mainly to manufacturers. Consequently there is a need to develop new coexistence approaches between TVWS networks. Busy tone broadcasting is a coexistence method which can be used by TVWS networks to announce the selected frequency band is occupied. In this paper a busy tone based coexistence algorithm is proposed for IEEE 802.11af and IEEE 802.22 networks and analyzed by considering different client distributions experiencing log-normal shadowing where the exact interfering packet rate and successful packet transmission rate expressions are obtained and validated by simulations for different scenarios. The results show that with the proposed coexistence approach a WLAN can reliably detect the busy tone signal to change its frequency band and can reduce interference to WRAN. Even if there is no available frequency band for the WLAN the WRAN still maintains its enhanced successful packet transmission performance. The deployment of the proposed algorithm is important for successful coexistence between cognitive wireless networks where interference is not regulated such as in TVWS bands.
5g ve Ötesi Hücresel Ağlarda Makineler Arası Haberleşme için Radyo Kaynak Ayırma
(2022) Aldemir, Sümeyra; Bayman, İrem Özgür; Erküçük, Serhat; Çağan, Yağız Can; Demirci, Senanur; Şadi, Yalçın
Bu proje çerçevesinde, 5G ve ötesi hücresel sistemlerde önceki nesil hücresel sistemlerin aksine makineler arası haberleşmenin birincil olarak desteklenmesi hedefiyle spektral verimliliği yüksek radyo kaynak ayırma çözümleri üzerinde çalışılmıştır. İlk olarak, sabit nümerolojinin kullanıldığı fiziksel katman yapısı dikkate alınarak bant genişliği minimizasyonu problemi dikgen ve dikgen olmayan senaryolarda tanımlanmış ve matematiksel olarak formüle edilmiştir. Bu optimizasyon problemleri için polinom zamanlı kaynak ayırma yöntemleri önerilmiş ve bunların performansı simülasyon çalışmalarıyla gösterilmiştir. Daha sonra, 5G ve ötesi ağlar için tanımlanan Yeni Radyo baz alınarak çoklu nümeroloji kullanımını merkeze alan esnek fiziksel katman yapısı ele alınmıştır. Esnek fiziksel katman yapısı için bant-genişliği minimizasyonu problemi iki varyant olarak tanımlanmış ve matematiksel olarak formüle edilmiştir. Bunlar, sırasıyla bölümlenmemiş ve bölümlenmiş bant yapısını kullanan formülasyonlardır. Her iki optimizasyon problemi için optimal nümeroloji seçimi ve bantların maksimum kullanımı aşamalarından oluşan kaynak ayırma algoritmaları önerilmiştir. Bu algoritmaların performansı incelendiğinde, spektral verimliliği dikgen ve AGTI tabanlı algoritmalara göre önemli ölçüde artırdığı gözlemlenmiştir.
Citation - Scopus: 1
Ieee 802.15.4a Based Ultra Wideband Systems for Coexistence With Primary Users
(IEEE, 2015) Fındıklı, Çağlar; Erküçük, Serhat; Çelebi, Mehmet Ertuğrul
Peaceful coexistence is a major implementation issue for both cognitive radios and ultra wideband (UWB) systems. Accordingly the UWB impulse radio (UWB-IR) based Wireless Personal Area Network (WPAN) standard IEEE 802.15.4a has suggested using linear combination of pulses to limit interference to coexisting primary systems. In this paper motivated by implementing the IEEE 802.15.4a based UWB-IR systems for peaceful coexistence we consider the implementation of linear combination of pulses as suggested by the standard. Accordingly we (I) design linearly combined pulses that conform to the standard requirements and (ii) study the UWB-IR system performance in the presence of orthogonal frequency division multiplexing (OFDM) based wideband primary systems with various bandwidths and subcarriers. The study shows that the UWB-IR system performance can be significantly improved by selecting suitable pulses for transmission and employing appropriate filtering techniques at the receiver when the primary system is active. The results are important for the practical implementation of IEEE 802.15.4a based UWB systems coexisting with licensed systems.
Performance of Combinational Cooperative Detection Method Under Realistic Conditions
(IEEE Computer Society, 2020) Samo, Rameez Ahmed; Başaran, Mehmet; Erküçük, Serhat
Combinational cooperative detection (CCD) is a method where signal energies from multiple secondary users (SUs) are gathered in different combinations in order to reach a unique decision for each secondary user regarding the activity of the primary user. In earlier implementations of the CCD method, the locations of the SUs have been assumed to be fixed and selected near the border points of the communication area, and the detection performance has been studied for different parameters. In this paper, the performance of the CCD method has been studied under realistic conditions. Initially, the effect of random locations of SUs on the detection performance is considered and compared with the performance for fixed locations. Then, the effect of distance variations between the master and the user is investigated. Finally, the effect of different propagation environments on the detection performance is studied. The results presented are important to assess the performance of the CCD method under realistic conditions.
Citation - WoS: 6
Citation - Scopus: 9
The Effect of Channel Models on Compressed Sensing Based Uwb Channel Estimation
(IEEE, 2011) Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
Ultra-wideband (UWB) multipath channels are assumed to have a sparse structure as the received consecutive pulses arrive with a considerable time delay and can be resolved individually at the receiver. Due to this sparse structure there has been a significant amount of interest in applying the compressive sensing (CS) theory to UWB channel estimation. There are various implementations of the CS theory for the UWB channel estimation based on the assumption that the UWB channels are sparse. However the sparsity of a UWB channel mainly depends on the channel environment. Motivated by this in this study we investigate the effect of UWB channel environments on the CS based UWB channel estimation. Particularly we consider the standardized IEEE 802.15.4a UWB channel models and study the channel estimation performance from a practical implementation point of view. The study shows that while UWB channel models for residential environments (e. g. CM1 and CM2) exhibit a sparse structure yielding a reasonable channel estimation performance channel models for industrial environments (e. g. CM8) may not be treated as having a sparse structure due to multipaths arriving densely. The results of this study are important as it determines the suitability of different channel models to be used with the CS theory.