• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1053-1062
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• 2008

This paper provides a general and compact expression for the probability density function (pdf) and the moment-generating function (MGF) of the maximal ratio combiner output over Rayleigh fading channels. It is then used to derive closed form expression bit error rate (BER) for M-PSK, M-PAM and M-QAM, respectively. A variety of simulations is performed and shows that they match exactly with analytic ones.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1071-1088
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• 2017

For dual-hop multiple-input multiple-output (MIMO) decode-and-forward relaying systems, we propose a selective relaying scheme that uses orthogonal space-time block code (OSTBC) and transmit antenna selection with maximal-ratio combining (TAS/MRC) or vice versa at the first and second hops, respectively. The aim is to achieve an asymptotically identical performance to the dual-hop relaying system with only TAS/MRC, while requiring lower feedback overhead. In particular, we give the selection criteria based on the antenna configurations and the average channel powers for the first and second hops, assuming Rayleigh fading channels. Also, the numerical results are shown for the outage performance comparison between the dual-hop DF relaying systems with the proposed scheme, only TAS/MRC, and only OSTBC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.102-122
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• 2017

Nanotechnology has provided a set of tools that the engineers can use to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. One of the main hurdles for nano devices has been the amount of power that it can generate for transmission of data. In this paper, we proposed cooperative nano communication in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage probability (OP) performances for the proposed cooperative nano communication networks in the THz band (0.1 - 10THz) have been evaluated for the following scenarios; A) A single decode-and-forward (DF) relay over independent identically distributed (i.i.d.) Rayleigh fading channels, B) DF multi-relay network with best relay selection (BRS) over i.i.d. Rayleigh fading channels, and C) DF multi-relay network with multiple hops with BRS over i.i.d. Rayleigh fading channels. The results show that the transmission distance can be improved significantly by employing DF relays. Also, it is shown that by increasing the number of hops in a relay the OP performance is marginally degraded. The analytical results have been verified by Monte-Carlo simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.321-328
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• 2010

A Rayleigh fading channel simulator that realizes given correlation properties between two channels such as downlink/uplink is described. We propose an improved channel simulator that provides more accurate match between reference correlation and simulated one. The proposed channel simulator is based on a sum-of-sinusoids (SOS) method that handles finite sums of weighted sinusoid functions. SOS method is widely accepted in generating fading signals and obtain the exact match with the reference model if infinite number of weighted sinusoids are used. The proposed channel simulator minimizes mean-square-error (MSE) to obtain a close matched correlation properties.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.1-9
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• 2010

This paper offers performance analysis of selection decode and forward (DF) networks with differential modulation/demodulation for an arbitrary number of relays in independent but not identically distributed Rayleigh fading channels. We have shown that the selection DF protocol with differential modulation can achieve full diversity in both independent identically distributed (i.i.d.) and independent but not identically distributed (i.n.d.) Rayleigh fading channels, and the performance loss due to using non-coherent detection is not substantial. Furthermore, we study the impact of combining techniques on the performance of the system by comparing a system that uses selection combining (SC) to one that uses maximum ratio combining (MRC). Simulations are performed and show that they match exactly with analytic ones in high SNR regime.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.5
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• pp.416-425
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• 2013

A hybrid PN code phase acquisition system based on a least-mean-square adaptive filter, interpreted as a channel estimator is proposed and analyzed for direct-sequence spread-spectrum systems under frequency selective Rayleigh fading channels. Closed form expressions are derived for the filter tap weights and detection/false alarm probabilities. Compared to previously proposed systems, the proposed system achieves smaller mean acquisition times, is more robust to the operating signal-to-noise ratio and allows for multiplication free tap weight updates.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.780-783
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• 1999

This paper gives channel estimation of W-CDMA reverse link using 2-point second-order algorithm over Rayleigh fading channels. The proposed algorithm is compared with the existing interpolation algorithms, i.e., WMSA, linear and second-order Gaussian interpolation, by obtaining HER performance through computer simulations. The BER performance of 2-point second-order interpolation is superior to other algorithms in fading channels. The proposed algorithm also has relatively-simple structure and similar processing delay in comparison to the existing algorithm, Therefore, this algorithm is more suitable for high speed mobile communication environments.

• Journal of Communications and Networks
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• v.11 no.5
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• pp.480-488
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• 2009

Cooperative transmission is an effective solution to improve the performance of wireless communications over fading channels without the need for physical co-located antenna arrays. In this paper, selection combining is used at the destination instead of maximal ratio combing to optimize the structure of destination and to reduce power consumption in selective decode-and-forward relaying networks. For an arbitrary number of relays, an exact and closed-form expression of the bit error rate (BER) is derived for M-PAM, M-QAM, and M-PSK, respectively, in both independent identically distributed and independent but not identically distributed Rayleigh fading channels. A variety of simulations are performed and show that they match exactly with analytic ones. In addition, our results show that the optimum number of relays depend not only on channel conditions (operating SNRs) but also on modulation schemes which to be used.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.1910-1917
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• 1989

This paper shows the performances of asynchronous binary direct-sequence spread-spectrum multiple access communication systems with Rayleigh fading and White Gaussian noise. The performance measures considered are worst-case bit error probability and average SNR depending on code sequences and chip waveforms. The code sequences used are m-sequence and Gold sequence with period 31.The chip waveforms employed are rectangular, sinusoidal and something other chip waveforms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.91-98
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• 2009

This paper provides new exact-closed form expressions for average SER and average BER as well as outage probability for M-PSK signaling with selection combining over independent but non-identically distributed Rayleigh fading paths. The validity of these expressions is verified by the Monte-Carlo simulations. All of numerical results are in excellent agreement with simulation results.