• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.1
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• pp.1-6
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• 2002

A new closed-form expressions to calculate frequency-dependent distributed inductance and the associated distributed series resistance of single interconnect on a lossy silicon substrate (CMOS technology) are presented. The proposed analytic model for series impedance is based on a self-consistent field method and the vector magnetic potential equation. It is shown that the calculated frequency-dependent distributed inductance and the associated resistance are in good agreement with the results obtained from rigorous full wave solutions and CAD-oriented equivalent-circuit modeling approach.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2177-2182
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• 2016

Using the existing exact but quite complicated symbol error rate (SER) expressions for M-ary phase shift keying (M-PSK) and M-ary differential phase shift keying (M-DPSK), we derive effective and concise closed-form asymptotic SER formulas especially in Rician-Nakagami fading channels. The derived formulas can be utilized to efficiently verify the achievable error rate performances of M-PSK and M-DPSK systems for the Rician-Nakagami fading environments. In addition, by exploiting the modulation gains directly obtained from the asymptotic SER formulas, we also theoretically demonstrate that M-DPSK suffers an asymptotic SER performance loss of 3.01dB with respect to M-PSK for a given M in Rician-Nakagami fading channels at high signal-to-noise ratio (SNR).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7A
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• pp.523-529
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• 2009

This paper provides closed form expressions for the evaluation of the end-to-end outage probability, symbol error rate, bit error rate and average capacity of the partial-based Decode-and-Forward (DF) relay selection scheme with an arbitrary number of relays. In a comparison with the performance of systems that exploit Amplify-and-Forward (AF), it can be seen that the performance of our proposed protocol converges to that of partial-based AF relay selection in high SNR regime. We also perform Monte-Carlo simulations to validate the analysis.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.257-266
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• 2006

The powerful benefits of multi-antenna systems can be obtained by cooperative communications among users in multiple access environments without the need for physical arrays. This paper studies a novel cooperative signaling strategy that achieves high performance and low implementation complexity for synchronous code division multiple access (CDMA) wireless mobile networks. The validity of the proposed strategy under slow flat Rayleigh fading channel plus additive white Gaussian noise (AWGN) is verified through closed-form error probability expressions and MonteCarlo simulations. A variety of analytical results reveal that the new cooperative strategy significantly outperforms direct transmission subject to the same spectral efficiency and transmit power constraint.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.538-546
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• 2010

This paper presents an overview of position-based routing algorithms. We analyze performances of routing algorithms such as Hybrid Opportunistic Forwarding (HOF), Opportunistic multi-hop routing (ExOR), Location based Geocasting and Forwarding (LGF), and Greedy Forwarding in nearest with forward Progress (GFP) routing algorithms to find the best one in terms of packet error rate and throughput efficiency over effects of fading and noise variance in wireless networks. The analyses in closed form expressions are confirmed by the simulation results, which fully agree to analysis results. Additionally, the simulation results indicate significant differences among algorithms when varying the average SNR or the number of relays.

• Structural Engineering and Mechanics
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• v.59 no.1
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• pp.1-14
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• 2016

In this paper, an alternative analytical method is presented to evaluate the nonlinear vibration behavior of single and double tapered cantilever beams. The admissible lateral displacement function satisfying the geometric boundary conditions of a single or double tapered cantilever beam is derived by using Rayleigh-Ritz method. Based on the Lagrange method and the Newton Harmonic Balance (NHB) method, analytical approximate solutions in closed and explicit form are obtained. These approximate solutions show excellent agreement with those of numeric method for small as well as large amplitude. Moreover, due to brevity of expressions, the present analytical approximate solutions are convenient to investigate effects of various parameters on the large amplitude vibration response of tapered beams.

• Current Optics and Photonics
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• v.3 no.4
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• pp.311-319
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• 2019

A hybrid free-space-optical/radio-frequency (FSO/RF) communication system is considered, with the help of amplify-and-forward (AF) relaying. We consider various weather conditions to investigate their effects on the system's performance. We begin by obtaining the cumulative distribution function and probability density function of the end-to-end signal-to-noise ratio for the AF dual-hop FSO communication system with RF backup link. Then, these results are used to derive closed-form expressions for the outage probability, average bit-error rate, and average ergodic capacity. The results show that the considered system efficiently employs the complementary nature of FSO and RF links, resulting in impressive performance improvements compared to non-hybrid systems.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.34-41
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• 2021

Recently, a lossless non-successive interference cancellation (SIC) non-orthogonal multiple access (NOMA) implementation has been proposed. Such lossless NOMA without SIC is achieved via correlated superposition coding (SC), in comparison with conventional independent SC. However, only high-correlated SC was investigated in the lossless non-SIC NOMA implementation. Thus, this paper investigates low-correlated SC, especially a lossless interval, owing to low-correlation between signals. First, for the low-correlated SC scheme, we derive the closed-form expressions for the two roots with which the lossless interval is defined. Then, simulations demonstrate that the lossless interval of low-correlated SC NOMA is enlarged, with a degraded middle interval, compared to that of high-correlated SC NOMA. Moreover, we also show that such tendency becomes stronger as the value of the correlation coefficient varies. As a result, the proposed low-correlated SC scheme could be considered as a promising correlated SC scheme, with the enlarged lossless interval in NOMA toward the future sixth-generation (6G) ultra-reliable low-latency communications (URLLC).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.9
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• pp.3124-3137
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• 2022

We propose a spectral-efficient coordinated direct and relayed transmission (CDRT) scheme for a relay-assisted downlink system with two users. The proposed scheme is based on backscatter communication (BC) and non-orthogonal multiple access (NOMA) technique. With the proposed BC-NOMA-CDRT scheme, both users can receive one packet within one time slot. In contrast, in existing NOMA-CDRT schemes, the far user is only able to receive one packet in two time slots due to the half-duplex operation of the relay. We investigate the outage of the BC-NOMA-CDRT scheme, and derive the outage probability expressions in closed-form based on Gamma distribution approximation and Gaussian approximation. Numerical results show that the analytical results are accurate and the BC-NOMA-CDRT scheme outperforms the conventional NOMA-CDRT significantly.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.307-314
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• 2021

Recently, positively asymmetric binary pulse amplitude modulation (2PAM) has been proposed to improve the bit error rate (BER) performance of the weak channel gain user, with a tolerable BER loss of the strong channel gain user, for non-orthogonal multiple access (NOMA). However, the BER loss of the stronger channel gain user is inevitable in such positively asymmetric 2PAM NOMA scheme. Thus, we propose the negatively asymmetric 2PAM NOMA scheme. First, we derive closed-form expressions for the BERs of the negatively asymmetric 2PAM NOMA. Then, simulations demonstrate that for the stronger channel gain user, the BER of the proposed negatively asymmetric 2PAM NOMA improves, compared to that of the conventional positively asymmetric 2PAM NOMA. Moreover, we also show that for the weaker channel gain user, the BER of the proposed negatively asymmetric 2PAM NOMA is comparable to that of the conventional positively asymmetric 2PAM NOMA, over the power allocation range less than about 10 %.