• Journal of the Korea Society of Computer and Information
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• v.6 no.3
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• pp.78-83
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• 2001

In this paper, we are considered Nakagami-m fading, which can model variable multipath mobile radio communication channel, in DS-CDMA system. System modeling using nakagami -m fading is suited for urban mobile communication channel with multipath. We used adaptive serial search PN code acquisition scheme and derived the detection probability($P_D$) and false alarm probability($P_FA$) which have influence on code acquisition time, over Nakagami-m fading. Detection probability($P_D$) and false alarm probability($P_FA$) are detection variable to decide PN code acquisition time and should use to calculate mean and variance. of acquisition time. From computer simulation, we analyzed mean and variance about PN code acquisition of fading channel. Then we can apply it to the H/W design of mobile communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1202-1207
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• 2006

In this paper we analyze the performance improvement of the M-ary FSK systems for low power and low data rate applications. This contribution presents a unified analysis of its MRC diversity, uncoded and performance in A WGN, m=2, m=3, Rayleigh and one sided Gaussian fading channels using optimum noncoherent demodulation with Reed-Solomon(RS) codes. The results of this paper should be useful as benchmarks of obtainable performance and as a reference for validating the results of simulation studies when slow fading models are applicable.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2416-2432
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• 2017

In this paper, we investigate the security performance for cooperative networks over Nakagami-m fading channels. Based on whether the channel state information (CSI) of wiretap link is available or not, optimal relay selection (ORS) and suboptimal relay selection (SRS) schemes are considered. Also, multiple relays combining (MRC) scheme is considered for comparison purpose. The exact and asymptotic closed-form expressions for secrecy outage probability (SOP) are derived and simulations are presented to validate the accuracy of our proposed analytical results. The numerical results illustrate that the ORS is the best scheme and SRS scheme is better than MRC scheme in some special scenarios such as when the destination is far away from the relays. Furthermore, through asymptotic analysis, we obtain the closed-form expressions for the secrecy diversity order and secrecy array gain for the three different selection schemes. The secrecy diversity order is closely related to the number of relays and fading parameter between relay and destination.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.182-189
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• 2016

The focus in this paper is on obtaining tight, simple algebraic-form bounds and invertible expressions for the average symbol error probability (ASEP) of M-ary phase shift keying (MPSK) in a class of composite fading channels. We employ the mixture gamma (MG) distribution to approximate the signal-to-noise ratio (SNR) distributions of fading models, which include Nakagami-m, Generalized-K ($K_G$), and Nakagami-lognormal fading as specific examples. Our approach involves using the tight upper and lower bounds that we recently derived on the Gaussian Q-function, which can easily be averaged over the general MG distribution. First, algebraic-form upper bounds are derived on the ASEP of MPSK for M > 2, based on the union upper bound on the symbol error probability (SEP) of MPSK in additive white Gaussian noise (AWGN) given by a single Gaussian Q-function. By comparison with the exact ASEP results obtained by numerical integration, we show that these upper bounds are extremely tight for all SNR values of practical interest. These bounds can be employed as accurate approximations that are invertible for high SNR. For the special case of binary phase shift keying (BPSK) (M = 2), where the exact SEP in the AWGN channel is given as one Gaussian Q-function, upper and lower bounds on the exact ASEP are obtained. The bounds can be made arbitrarily tight by adjusting the parameters in our Gaussian bounds. The average of the upper and lower bounds gives a very accurate approximation of the exact ASEP. Moreover, the arbitrarily accurate approximations for all three of the fading models we consider become invertible for reasonably high SNR.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.213-214
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• 2008

In this paper, we analyze the performance of a cooperative communication wireless network over independent and identically distributed (IID) Nakagami-m fading channels. A simple transmission scheme is considered where the relay is operating in amplify-forward (AF) mode. A closed-form expression for symbol error rate (SER) is obtained using the moment generating function (MGF) of the total signal to noise ratio (SNR) of the transmitted signal with binary phase shift keying (BPSK).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.635-639
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• 2000

The average bit error rate (BER) performance of 2D-RAKE receiver, operating in a correlated Nakagami fading channel, is analyzed. The analysis assumes correlated fading between the array elements with identical fading parameters but with unbalanced average signal-to-noise ratio (SNR). And independent but non-identically distributed frequency-selective fading channel with different fading parameters is assumed. The analyses show that fading correlation, delay profile, average SNR distribution, and fading parameters of combined branches affect the overall performance of 2D-RAKE receiver.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.162-171
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• 2014

Spectrum sensing is a key technical challenge for cognitive radio (CR). It is well known that multicycle cyclostationarity (MC) detection is a powerful method for spectrum sensing. However, a conventional MC detector is difficult to implement because of its high computational complexity. This paper considers reducing computational complexity by simplifying the test statistic of a conventional MC detector. On the basis of this simplification process, an improved MC detector is proposed. Compared with the conventional detector, the proposed detector has low-computational complexity and high-accuracy sensing performance. Subsequently, the sensing performance is further investigated for the cases of Rayleigh, Nakagami-m, Rician, and Rayleigh fading and lognormal shadowing channels. Furthermore, square-law combining (SLC) is introduced to improve the detection capability in fading and shadowing environments. The corresponding closed-form expressions of average detection probability are derived for each case by the moment generation function (MGF) and contour integral approaches. Finally, illustrative and analytical results show the efficiency and reliability of the proposed detector and the improvement in sensing performance by SLC in multipath fading and lognormal shadowing environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3003-3017
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• 2013

In this paper, we investigate the outage performance of a cognitive relay network. We consider mutual interference in an independent, non-identically distributed Nakagmai-m fading environment. We first derive the close-form outage probability expression, which provides an efficient means to evaluate the effects of several parameters. This allows us to study the impact of several parameters on the network's performance. We then derive the asymptotic expression and reveal that the diversity order is strictly determined by the fading severity of the cognitive system. It is not affected by the primary network. Moreover, the primary network only affects the coding gain of the cognitive system. Finally, Monte Carlo simulations are provided, which corroborate the analytical results.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.2
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• pp.136-140
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• 2009

The performances of M-ary signals using L-branch maximum ratio combining (MRC) diversity reception in correlated Nakagami fading channels are derived theoretically. The coherent reception of M-ary differential phase shift keying (MDPSK), phase shift keying (MPSK), and quadrature amplitude modulation (MQAM) is considered. It is assumed that the fading parameters in each diversity branch are identical. The general formula for evaluating symbol error rate (SER) of M-ary signals in the independent branch diversity system is presented using the integral-form expressions. Until now, results did not extend to the various M-ary case for a coherent reception. The numerical results presented in this paper are expected to provide information for the design of radio system using M-ary modulation method for above mentioned channel environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.810-816
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• 2001

This paper proposes a Truncated Type-II Hybrid ARQ scheme using an adaptive modulation system to achieve high throughput data transmission systems for mobile communication systems. In this paper, the adaptive modulation system analyzed in Nakagami (m-distribution) fading channel environment. The adaptive modulation system controls the modulation level and symbol rate according to the Nakagami fading parameter(m). When the received $E_bN_0$ is high or the Nakagami fading parameter m is high, the propose system selects higher modulation level and higher symbol rate to increase throughput. On the other hand, this system selects lower modulation level and lower symbol rate to prevent throughput performance degradation when the received $E_bN_0$ is low. The modulation method have been adopted QPSK(Quadrature Phase Shift Keying), 16 QAM(Quadrature Amplitude Modulation), 64 QAM, 256 QAM. Therefore, Adaptive Modulation Systems with Truncated Type-II Hybrid ARQ Scheme is proper for mobile and radio for mobile and radio data communication system that require high reliability and delay-limited applications.