• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.757-763
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• 2018

It is very difficult to achieve sufficient data rate and required quality of service due to the time-varying nature of the radio channel and various jammers such as path loss, delay, Doppler, shadowing and interference. Especially, the propagation path between the transmitting antenna and the tracking antenna mounted on the fuselage during the test and evaluation of the projectile system considered in this paper is based on the rapid movement of the projectile, the interference due to multipath fading due to the terrain, The propagation path may be blocked. In order to effectively improve the multipath fading occurring in the wireless communication system, a diversity combiner technique is required. In this paper, to derive the design and improvement schemes for the space diversity combiner technique among the diversity combiner schemes, the BER performance of maximum ratio combining (MRC) and selection combining (SC) In an adaptive SC / MRC diversity combiner that operates with MRC when it is lower than the specified threshold criterion when comparing the SNR between two signals received from the channel and operates with SC at high and combines the two received signals The BER performance of the system was compared and analyzed.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.13-19
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• 2012

In this paper, we investigate cooperative transmission in one-dimensional random wireless networks. In this scheme, a stationary source communicates with a stationary destination with the help of N relays, which are randomly placed in a one-dimensional network. We derive exact and approximate expressions of the average outage probability over Rayleigh fading channels. Various Monte-Carlo simulations are presented to verify the accuracy of our analyses.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.5
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• pp.384-393
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• 2015

This paper proposes an optimized classifier based on feature elimination (OCFE) for gene selection with combining two feature elimination methods, ReliefF and SVM-RFE. ReliefF algorithm is filter feature selection which rank the data by the importance of the data. SVM-RFE algorithm is a wrapper feature selection which wrapped the data and rank the data based on the weight of feature. With combining these two methods we get less error rate average, 0.3016138 for OCFE and 0.3096779 for SVM-RFE. The proposed method also get better accuracy with 70% for OCFE and 69% for SVM-RFE.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4623-4643
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• 2015

This paper considers physical-layer security protocols in multicast cognitive radio (CR) networks. In particular, we propose dual-hop cooperative decode-and-forward (DF) and randomize-and-forward (RF) schemes using partial relay selection method to enhance secrecy performance for secondary networks. In the DF protocol, the secondary relay would use same codebook with the secondary source to forward the source's signals to the secondary destination. Hence, the secondary eavesdropper can employ either maximal-ratio combining (MRC) or selection combining (SC) to combine signals received from the source and the selected relay. In RF protocol, different codebooks are used by the source and the relay to forward the source message secretly. For each scheme, we derive exact and asymptotic closed-form expressions of secrecy outage probability (SOP), non-zero secrecy capacity probability (NzSCP) in both independent and identically distributed (i.i.d.) and independent but non-identically distributed (i.n.i.d.) networks. Moreover, we also give a unified formula in an integral form for average secrecy capacity (ASC). Finally, our derivations are then validated by Monte-Carlo simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.305-310
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• 2012

This paper proposes a selection combined hybrid sequential deconvolution and single carrier modulation with a zero forcing frequency domain equalizer for single carrier transmission system in order to enhance performance. Selection combining method is an algorithm of antenna space diversities, the receiver can choose the best channel environment only with the increase of the number of antennas, but a baseband structure is the same as the traditional receiver architecture. Simulation results show that the proposed algorithm has a better performance rather than the traditional single carrier transmission with a frequency domain equalizer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2696-2705
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• 1997

An exact experssion for the average symbol error rate(SER) of L-order selection diversity for MPSK signals in a frequency-nonselective slowy m-distributed Nakagami fading and additive white Gaussian noise(AWGN) is determs of finite sums is obtained. To derive the SER of MPSK signals with selection combining, the new expression of pdf is introduced and many other mathmatical methods are used. When fading index m is 1, the derived exppression lead to those of MPSK with selection combining in Rayleight fading channels. The results show that the error probability decreases as the order of diversity increases.

• ETRI Journal
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• v.46 no.3
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• pp.446-460
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• 2024

In this paper, we mathematically investigate a downlink non-orthogonal multiple access (NOMA) system for short-packet communications (SPC) in which the near users are used as full-duplex (FD) relays to forward intended signals from the source to a far user. In addition, partial relay selection is employed to enhance the performance of the FD relays under the impact of imperfect interference cancellation. At the far user, selection combining (SC) or maximal ratio combining (MRC) is employed to combine the signals received from the source and the selected FD relay. The analytical expressions for the average block error rate (BLER) of two users over flat Rayleigh fading channels are derived. Furthermore, closed-form asymptotic expressions of the average BLERs at the near and far users in high signal-to-noise ratio (SNR) regimes are obtained. The numerical results show that the analytical BLERs of the near user and far user closely match the simulation results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.5
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• pp.1588-1603
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• 2014

In space diversity combining, conventional methods such as maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SC) are commonly used to improve the output signal-to-noise ratio (SNR) provided that the channel is perfectly estimated at the receiver. However, in practice, channel estimation is often imperfect and this indeed deteriorates the system performance. In this paper, diversity combining techniques based on two evolutionary algorithms, namely genetic algorithm (GA) and particle swarm optimization (PSO) are proposed and compared. Numerical results indicate that the proposed methods outperform the conventional MRC, EGC and SC methods when the channel estimation is imperfect while it shows similar performance as that of MRC when the channel is perfectly estimated.

• Journal of Sericultural and Entomological Science
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• v.37 no.1
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• pp.10-15
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• 1995

Genetic characterization of Sri Lankan silkworm bivoltine population has not been at-tempted so far, since its sporadic introduction of bivoltine strains into the island, starting from the 1950's. Genetic structure of Sri Lankan population of mulberry silkworm Bombyx mori was investigated through estimation of general (GCA) and specific combining ability(SCA) and heritability(${h^2}_B$), on the economic quantitative characters from leading 8 inbreds and their 28 F1's in a half diallel cross, in an attempt to utilize the estimates in determination of future breeding methods and to predict the breeding value over the phenotypic value. It was found that the breeding population of the bivoltine silkworm in Sri Lanka has still maintained considerable amounts of additive gene action as well as nonadditive. For some time in the future, both breeding strategies of "selection without inbreeding" and also "inbreeding followed by crossing" should therefore be effective in genetic improvement of economic characters investigated. In addition, superior combiners in general and in specific F1′s were identified for each of 6 economic characters, to be immediately utilized in selection and also in cross breeding programs in Sri Lanka.

• Journal of Korea Multimedia Society
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• v.21 no.4
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• pp.493-498
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• 2018

In this paper, we provide the performance analyses of a dual-hop amplify-and-forward(AF) relay transmission composed of asymmetric radio-frequence(RF) and free-space optical(FSO) links. In the mixed RF/FSO system, a relay is equipped with two receive antennas for RF signals and one additional transmit antenna for FSO signals. In order to improve a performance of RF link, a switch-and-stay (SSC) diversity technique is applied at the relay which can provide a proper link performance with a low complexity. Specifically, we offer the performance analyses of the proposed system in terms of outage probability and secrecy outage probability. In numerical examples, we compare the system performances with no diversity and selection combining systems and verify our analytical results via computer-based Monte-Carlo simulations.