Yazar "Bilim, Mehmet" seçeneğine göre listele

Listeleniyor 1 - 20 / 41
  • [ X ]
    Öğe
    A comprehensive analytical perspective of ASEP for Beaulieu-Xie fading channels
    (Wiley, 2022) Bilim, Mehmet
    This study presents the average symbol error probability (ASEP) performance of a single-input single-output communication with imperfect phase error (IPE) and without IPE over the Beaulieu-Xie fading channels. The Beaulieu-Xie fading model is proposed recently and it is a popular characterization for the line-of-sight and non-line-of-sight environments. The proposed theoretical analysis, which is based on the probability density function, is enough general and applicable in some real-life scenarios. For both cases, closed-form exact, approximate, and asymptotic expressions are derived for the ASEP of different modulation types. Finally, exact simulations have been introduced to confirm the accuracy of the theoretical findings obtained and present insights into the considered scheme performance.
  • [ X ]
    Öğe
    A framework for Gaussian Q approximation with BSA and its application to RIS-assisted systems
    (Elsevier Gmbh, 2024) Bilim, Mehmet; Kabalci, Yasin
    This paper proposes a novel and improved Chiani approximation for the Gaussian Q-function by employing the backtracking search optimization algorithm (BSA). The proposed approximation includes only exponential terms which are comfortable for the mathematical functionality. Then, a wireless communication application of reconfigurable intelligent surface (RIS) structures, which are anticipated to play a crucial role in integrated sensing and communication (ISAC), has been presented. In the considered wireless communication scenario, the link between the source and RIS node is Nakagami-m fading, while the link between RIS node and the destination is Rayleigh fading. The received probability density function (PDF) expression of instantaneous signal to noise ratio for this system has been derived analytically. Using this derived PDF, the error expression (Pe) for the RISassisted communication system employing the rectangular quadrature amplitude modulation (RQAM) technique has been obtained with the assistance of the proposed improved Chiani approximation in this study. The obtained RQAM error figures are presented comparatively, and the results clearly show that the Pe expression by obtained the proposed approximation with BSA for the RIS-assisted communication system, which is an important aspect for ISAC, is in excellent agreement with computer simulations.
  • [ X ]
    Öğe
    A performance study on diversity receivers over ?-? shadowed fading channels
    (Elsevier Gmbh, 2019) Bilim, Mehmet
    In this study, N-branch selection combining (SC), dual-branch SC and dual-branch maximal ratio combining (MRC) receivers over kappa-mu shadowed fading channels are investigated in terms of average bit error probability (BEP), outage probability (OP) and channel capacity (CC). Firstly, a cumulative distribution function (CDF) expression for instantaneous signal-to-noise ratio (SNR) at the output of the N-branch SC system over a kappa-mu shadowed fading channel is derived. Based on the proposed CDF expression of output SNR for N-branch SC receiver, OP and approximate average BEP expressions are obtained. Secondly, the probability density function (PDF) expression for a dual-branch SC system over kappa-mu shadowed channels is derived. Then, two different CC expressions of a dual-branch SC receiver are obtained by using the proposed PDF expression. Thirdly, a PDF expression for a dual-branch MRC system under kappa-mu shadowed conditions is proposed and its CC expression with channel inversion with fixed rate for is derived. Effects of the fading parameters and the total number of branches on the system performance are examined with different scenarios. Finally, the obtained results from OP, average BEP and CC expressions are verified with numerical simulations. (C) 2019 Elsevier GmbH. All rights reserved.
  • [ X ]
    Öğe
    A study on the error probability of digital modulations over ?-?/gamma mixed fading environments
    (Pamukkale Univ, 2020) Bilim, Mehmet
    In this study, performance analysis of eta-mu/Gamma mixed fading channels of communication systems using noncoherent frequency shift keying and differential phase shift keying digital modulation types is presented. The analysis is based on probability density function and contains mathematically basic functions. For this reason, the proposed analysis is quite simple and understandable from a mathematical point of view. As a result of the analyzes, the closed form average error probability expression is derived. The numerical results obtained by using the derived error expression are compared with the simulation results and the accuracy of the derived expression is shown.
  • [ X ]
    Öğe
    Alternatif Rician sönümlenmesi için genelleştirilmiş Gauss gürültüsünün hataanalizi
    (2021) Bilim, Mehmet
    Bu çalışmada bir tek-giriş tek-çıkışlı sistemin alternatif Rician sönümlenmesi durumunda genelleştirilmiş Gauss gürültüsü ile birlikte hata olasılığı analizi sunulmaktadır. Yapılan analizlerde olasılık yoğunluk fonksiyonu temelli yaklaşım kullanılmıştır. Önerilen analitik ifadelere ek olarak, literatürdeki matematiksel çalışmalardaki gibi asimptotik analiz de sunulmuştur. Bu sayede ele alınan sistem modelinin orta ve yüksek ortalama işaret gürültü oranı şartlarındaki davranışları gösterilmiştir. Yapılan performans çalışmalarında farklı modülasyon türlerinin, gölgeleme parametre değerlerinin, Rician faktörü değerlerinin ve gürültü tiplerinin etkileri gözlemlenmiştir. Son olarak, yapılan analitik çalışmaların doğruluğu tam nümerik simülasyon sonuçları ile kıyaslanarak onaylanmıştır.
  • [ X ]
    Öğe
    Analysis of a RIS-Assisted Wireless Communication System with AWGGN
    (IEEE, 2022) Gumus, Damla; Bilim, Mehmet
    Reconfigurable intelligent surfaces (RIS)-assisted wireless communication networks are predicted to play a promising role for next generation communication systems. In this study, error analysis of a RIS-assisted system was carried out in the presence of additive white generalized Gaussian noise (AWGGN). As a result of the analysis, alternative error expressions were obtained by using different special functions such as parabolic cylinder, hypergeometric, erfc, etc. Using the solution containing the parabolic cylinder function from the derived expressions, the results of different smart cell number, modulation type and noise types are presented. It has been observed that the analytical and simulation (exact) results are in good agreement in these results.
  • [ X ]
    Öğe
    Analysis of analytical capacity for Fisher-Snedecor F fading channels with different transmission schemes
    (Wiley, 2019) Kapucu, N.; Bilim, Mehmet
    This Letter presents capacity analysis of Fisher-Snedecor F fading channels under different transmission strategies. To this end, novel analytical expressions are proposed for optimal rate adaptation with constant transmit power, channel inversion with a fixed rate and truncated channel inversion with fixed rate schemes in this Letter. Then, analytical results are illustrated for different fading and shadowing parameter values.
  • [ X ]
    Öğe
    Approximate ASER analysis of MIMO TAS/MRC networks over Weibull fading channels
    (Springer International Publishing Ag, 2021) Bilim, Mehmet
    In this paper, the average symbol error rate (ASER) evaluation of multiple-input-multiple-output (MIMO) systems with transmit antenna selection (TAS) and maximal ratio combining (MRC) are analysed under Weibull fading conditions. The impact of additive white Gaussian noise (AWGN) and additive white generalized Gaussian noise (AWGGN) on the ASER evaluation of the MIMO TAS/MRC networks are considered. Closed form approximate and asymptotic ASER expressions of the considered network with AWGN for different quadrature amplitude modulation techniques are derived based on the probability density function approach. The closed-form approximate and asymptotic ASER expressions for the AWGGN case are also obtained. In addition, a comprehensive analysis of the ASER performance for the MIMO TAS/MRC networks is demonstrated by varying the fading parameter values, numbers of transmitter-receiver antennas and constellation size. Finally, the obtained theoretical results are confirmed through the exact simulation results.
  • [ X ]
    Öğe
    Approximate Error Probability Analysis of L-Branch MRC System over ?-? Fading Environments
    (IEEE, 2024) Mutlu, Ural; Bilim, Mehmet; Kabalci, Yasin
    The increase in research conducted on next-generation communication systems has directed research interest toward new modulation schemes, channel models, and diversity techniques that promise enhanced efficiency. Recently, new analytical channel models capable of better modeling the wireless communication environment have been developed. In this study, the approximate error performance of hexagonal quadrature amplitude modulation (HQAM) in lambda - mu fading channels for multi-branch single-input multiple-output (SIMO) systems is investigated. An analytical expression for the error probability of the considered system is derived using the Prony approximation for the Gaussian Q function. Subsequently, an error probability expression for the considered system is proposed. Comparative results between the approximate results obtained from the derived expression and the exact simulation results are presented. Different scenarios are evaluated to analyze the effects of channel fading parameters, the number of transmission branches, and modulation levels, resulting in numerical outcomes. Ultimately, it was observed that the approximate results obtained from the proposed expression closely matched the exact simulation results, confirming the accuracy of the proposed analytical expression.
  • [ X ]
    Öğe
    Average Symbol Error Rate Analysis of QAM Schemes Over Millimeter Wave Fluctuating Two-Ray Fading Channels
    (Ieee-Inst Electrical Electronics Engineers Inc, 2019) Bilim, Mehmet; Kapucu, Nuri
    In this study, analytical expressions are derived by using probability density function approach over millimeter wave fluctuating two-ray (FTR) fading channels for average symbol error rate (ASER) of rectangular quadrature amplitude modulation (RQAM) and cross quadrature amplitude modulation (XQAM) schemes. First, an exact ASER expression for RQAM over millimeter wave FTR fading channels is derived. Second, two different upper bound ASER expressions of RQAM scheme under millimeter wave FTR fading conditions are obtained by using Chernoff and Chiani approximations of Gaussian Q-function. In addition to this, an asymptotic ASER expression for RQAM is also proposed. Then, an analytical formulation is presented for XQAM signaling over millimeter wave FTR fading channels in terms of infinite series representations which rapidly converge. Finally, the numerical results of the proposed analytical expressions are compared with the simulation results in order to validate the analytical findings in this work.
  • [ X ]
    Öğe
    Beaulieu-Xie Gölgelemeli Sönümlü Kanallar İçin Efektif Kanal Kapasite İfadesinin Kuramsal Türetimi
    (2022) Bilim, Mehmet; Kabalcı, Yasin
    Bu çalışma, alıcı-verici arasındaki hattın tek ve Beaulieu-Xie gölgelemeli (BX-shadowed, BX-S) sönümlenmeye sahip olduğu bir sistem için efektif kanal kapasitesi (effective channel capacity, Ceff) analizini sunmaktadır. Çalışmada Ceff ifadesi kuramsal olarak türetilmekte, türetimler için BX-S sönümlenmesine ait olasılık yoğunluk fonksiyonundan (probability density function, PDF) yararlanılmaktadır. Ceff ifadesinin doğruluğu bilgisayar benzetimleri ile gösterilmeye çalışılmakta, farklı parametre değişimleri ile çeşitli senaryolar incelenmektedir.
  • [ X ]
    Öğe
    Capacity and amount of fading analysis for SIMO communications over ?-? and ?-? fading channels
    (Academic Press Inc Elsevier Science, 2021) Bilim, Mehmet
    This study evaluates the performance of single-input multiple-output (SIMO) wireless networks or dual-branch (DB) SIMO scenarios over the eta-mu and the lambda-mu fading links. First, the probability density functions (PDFs) of the instantaneous signal to noise ratio for a DB SIMO system in the eta-mu and the lambda-mu fading conditions. Then, the closed-form expressions of the effective rate (ER or effective capacity) for a SIMO network are derived. In addition to this, asymptotic ER expressions for the considered SIMO network are proposed. The analytical capacity expressions with different transmission policies such as optimal rate adaptation with constant transmit power, optimal simultaneous power and rate adaptation, channel inversion with fixed-rate (CIFR), and truncated channel inversion with fixed-rate are obtained for the SIMO network. Furthermore, the capacity expressions with CIFR policy for DB SIMO communications over the eta-mu and the lambda-mu fading channels are derived by using the proposed PDFs. Finally, the amount of fading expressions for SIMO networks over the eta-mu and the lambda-mu fading links are proposed by employing the elementary functions. The proposed analytical expressions provide to establish different radio propagation scenarios by adjusting eta, lambda or mu parameter. To confirm the accuracy of our analysis, the proposed analytical expressions are verified via exact simulations. (C) 2020 Elsevier Inc. All rights reserved.
  • [ X ]
    Öğe
    Cascaded double fading channels: A case of ?-? shadowing
    (Elsevier, 2022) Bilim, Mehmet
    In this study, the cascaded double kappa -mu shadowed fading model is mathematically introduced. A novel expression is obtained for the cumulative distribution function (CDF) of the cascaded double kappa - mu shadowed fading channels by using Meijer's G function and Laplace transform. Based on the obtained CDF expression, the exact and asymptotic expressions are derived for the outage probability (OP), the average bit error rate (BER) for various modulations of the considered channel model. The OP and the average BER curves with exact simulations obtained by the proposed expressions are presented for different parameters and modulation schemes of the considered channel model. Finally, the accuracy of the derived OP and the average BER expressions is confirmed with exact simulations.(C) 2022 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    Different QAM schemes analyses for ARS fading channels
    (Wiley, 2021) Bilim, Mehmet
    Quadrature amplitude modulation (QAM) techniques are employed for various communication systems due to its advantages such as efficient bandwidth and high rate. In this paper, the average symbol error rate (ASER) performances of single-input single-output networks are investigated to address the different QAM schemes combined use. The link in the network experiences the alternate Rician shadowed (ARS) fading which has the benefit of contributing left or right-sided bimodality. Four different QAM schemes such as rectangular QAM, cross-QAM, hexagonal QAM, and square QAM are used for the considered network. Under these assumptions, new closed-form expressions for the ASER in terms of elementary functions and Meijer'sGfunctions are derived. The derived ASER expressions are obtained by employing the Prony approximation with two terms which has fractional coefficients to provide precise results. Based on the second-order exponential function approximation for GaussianQ-function, the ASER expressions of the considered system are also proposed. Additionally, we provide other important engineering insights based on the high signal-to-noise-ratio analysis of the ASER performance over ARS fading channels. Finally, all our theoretical results are confirmed with simulations.
  • [ X ]
    Öğe
    Dual-branch SC wireless systems with HQAM for beyond 5G over ?-? fading channels
    (Springer, 2021) Bilim, Mehmet
    In this study, the performance of hexagonal quadrature amplitude modulation (HQAM) for a dual-branch selection combining (SC) receiver for beyond fifth-generation (B5G) is analyzed in detail. For general applicability, the links are modeled with eta-mu fading channels. In this context, analytical expressions of error probability (EP) are derived in terms of the Chernoff, Chiani, Prony (2 and 3 terms), and Trapezoidal approximations for Gaussian Q-function. For the high signal to noise ratio (SNR) analysis, asymptotic EP expression is also derived by using the Chernoff approximation. Further, for the comparison, the analytical EP expressions with rectangular QAM and quadrature phase-shift keying modulation schemes are obtained by using the Chiani approximation. Moreover, a comprehensive work of various modulation schemes is presented and the effects of fading parameters, type of GaussianQ-function approximations, and average SNR values of first and second links are highlighted on the EP performance. Finally, to show the accuracy of the proposed analytical derivations, some results for the exact simulations and numerical results are demonstrated.
  • [ X ]
    Öğe
    Dual-hop communications over PLC/?-? and PLC/?-? fading channels
    (Taylor & Francis Ltd, 2023) Bilim, Mehmet
    In this study, the performance analysis of dual-hop power line communication (PLC)/$$\eta -\mu $$eta-mu and PLC/$$\lambda -\mu $$lambda-mu L-branch systems by using the decode-and-forward (DF) protocol is presented in detail. The introduced work provides novel closed-form expressions of the probability density function (PDF) of the instantaneous signal-to-noise ratio (SNR) of the considered systems. Taking the proposed PDFs into account, we also derive closed-form expressions of the error rate and channel capacity (CC) performance for the dual-hop PLC/$$\eta -\mu $$eta-mu and PLC/$$\lambda -\mu $$lambda-mu L-branch DF systems. Furthermore, an exhaustive comparative study of different modulation types such as non-coherent M-ary frequency-shift keying, square quadrature amplitude modulation (SQAM), and cross quadrature amplitude modulation (xQAM) is presented by using the proposed closed-form error rate expressions. Also, the exact expressions for the CC with channel inversion with a fixed-rate (CIFR) transmission policy are proposed. Finally, all the theoretical findings are confirmed through numerical results obtained by using the exact expressions.
  • [ X ]
    Öğe
    Effective throughput of alternate rician shadowed fading links
    (Wiley, 2020) Bilim, Mehmet
    The performance of effective throughput (ET) over alternate Rician-shadowed fading channels is analyzed. A novel expression for the exact ET is obtained in terms of the Meijer's G function. Moreover, an asymptotic ET expression at the high signal-to-noise ratio regime is also derived to gain more insight. In order to prove the correctness of our analytical derivations, some comparisons between the exact simulations and numerical results are presented. The results demonstrate that increasing the value of m shadowing fading is more dominant than the value of K-i (i is an element of {1, 2}) Rician parameters since this means a weak shadowing condition. (c) 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
  • [ X ]
    Öğe
    Error Analysis of Dual-Branch SIMO Systems Over ? - ? Fading Channels
    (IEEE, 2020) Bilim, Mehmet; Kapucu, Nuri
    In this work, error performance of dual-branch single-input multiple-output (SIMO) systems is analyzed over lambda-mu fading channels. An analytical expression is derived by using Chernoff approximation for the error probability of the considered system. Then, an asymptotic error expression is also proposed for the considered system. The results obtained from the derived expression are presented in comparison with exact results. Numerical results are shown for different configurations in order to analyze the effects of different values of fading parameter, antenna number and modulation type. In conclusion, it is observed that the approximate results are close to the exact results.
  • [ X ]
    Öğe
    Error Analysis of Dual-Branch SIMO Systems over ?-? Fading Channels
    (Institute of Electrical and Electronics Engineers Inc., 2020) Bilim, Mehmet; Kapucu, Nuri
    In this work, error performance of dual-branch single-input multiple-output (SIMO) systems is analyzed over -u fading channels. An analytical expression is derived by using Chernoff approximation for the error probability of the considered system. Then, an asymptotic error expression is also proposed for the considered system. The results obtained from the derived expression are presented in comparison with exact results. Numerical results are shown for different configurations in order to analyze the effects of different values of fading parameter, antenna number and modulation type. In conclusion, it is observed that the approximate results are close to the exact results. © 2020 IEEE.
  • [ X ]
    Öğe
    Error analysis of SISO and dual-branch communications with generalized Gaussian noise over FTR fading channels br
    (Tubitak Scientific & Technological Research Council Turkey, 2022) Bilim, Mehmet
    In this paper, we present error probability analysis for single-input single-output (SISO) and asymmetric dual-branch networks with additive white generalized Gaussian noise (AWGGN) over millimeter-wave (mmW) fluctuating two-ray (FTR) fading channels. Then, we examine the error probability evaluation of a SISO system with imperfect phase errors over mmW FTR fading channels. The probability density function (PDF) approach is employed for the error probability performance evaluation and the novel PDF of the asymmetric dual-branch system over Nakagami-m/mmW FTR fading channels is obtained. Specifically, closed-form expressions are derived for the error probability of the SISO and asymmetric dual-branch networks. The derived error expressions facilitate in effectively evaluating the performance of considered networks in the presence of AWGGN and imperfect phase noise with optimal fading parameters and modulation type. The theoretical derivations are extensively confirmed through exact simulations.