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        • KCI등재

          How can Perfect SIC NOMA Be Implemented?

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.8

          Currently, the perfect successive interference cancellation (SIC) implementation has not been reported in the literature of non-orthogonal multiple access (NOMA). However, NOMA capacity is derived with the assumption of the perfect SIC. We try to find how to achieve the perfect SIC NOMA capacity and performance, under the practical modulation, such as the binary phase shift keying (BPSK) modulation. One possible way to achieve the near perfect SIC capacity/performance NOMA, proposed in this paper, is the dynamic superposition coding (DSC), which is a combination of the normal superposition coding (NSC) and the symmetric superposition coding (SSC), based on the power allocation factor.

        • KCI등재

          Non-SIC NOMA: Gaussian Mixture Channel Capacity under BPSK and QPSK Modulations

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.4

          We propose non-orthogonal multiple access (NOMA) without the successive interference cancelation (SIC). This paper compares the channel capacity of the non-SIC NOMA to that of the standard NOMA. It is shown that the channel capacity of the non-SIC NOMA is almost the same as that of the standard NOMA for the operating range of the power allocation factor less than 20 % or greater than 80 %. In result, the non-SIC NOMA could be one of promising schemes, without the SIC complexity.

        • 영양원 변화가 Kerosene 분해율 및 분해균주 성장에 미치는 영향

          정규혁 성균관대학교 약학연구소 1999 成均藥硏論文集 Vol.11 No.-

          Bioremediation is the technology to harness nature's biodegradative capabilities to remove or detoxify pollutions that threaten public health as environmental contaminants. Composting may become one of major bioremediation technologies for treating soils contaminated with petroleum if the fate of contaminants during composting is better understood Most composting research of petroleum was primarily focused on removing contaminant by optimizing composting conditions. Accordingly, laboratory feasibility studies may be useful to establish a realistic basis in co-composting complex substrate such as petroleum hydrocarbons. The purpose of this study was to assess the optimal conditions of kerosene biodegradation following supplementation with nutrient amendments under simulated composting conditions. Although it increased the growth of bacterial consortium, addition of co-substrates 0.5%(w/v) such as acetic acid, citric acid, glucose, and malic acid was not beneficial. Combination of nitrogen and phosphorous source enhanced kerosene biodegradation and reduced VOC evolution. These results showed that kerosene was able to utilize in bioremediation technology.

        • KCI등재

          Performance Analysis on Non-Perfect SIC in NOMA

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.5

          We present non-orthogonal multiple access (NOMA) with non-perfect successive interference cancellation (SIC). It is shown that the performance of non-perfect SIC NOMA is almost the same as that of perfect SIC NOMA for the power allocation factor less than 20 %. However, the performance of non-perfect SIC NOMA becomes worse than that of perfect SIC NOMA for the power allocation factor greater than 20 %. Consequently, NOMA should be designed to take into account non-perfect SIC.

        • KCI등재

          Performance Analysis on Non-SIC ML Receiver for NOMA Strong Channel User

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.3

          We analyze the performance of the maximum likelihood (ML) receiver for the stronger channel user of non-orthogonal multiple access (NOMA), when no successive interference cancelation (SIC) is performed. This paper compares the non-SIC ML receiver to the standard receiver with the SIC. It is shown that the performance of the non-SIC ML receiver is almost the same as that of the standard receiver with the SIC for the operating range of the power allocation factor less than 20 %. In result, the non-SIC ML receiver could be a promising scheme for the NOMA stronger channel user, reducing the SIC complexity.

        • KCI등재

          Impact of Fast Fading CCI on Performance of Optimum Combining in DF Relaying

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.1

          We present the effect of fast fading co-channel interference (CCI) on the performance of decode-and-forward (DF) relaying. This paper derives closed-form expressions for the average symbol error rate (SER) with optimum combining (OC) in the presence of fast fading CCI. It is shown that the average SER performance of fast fading CCI is worse than that of slow fading CCI, which is the previous research assumption. In result, DF relaying systems should be designed with consideration of fast fading CCI.

        • KCI등재

          On BER for M-User NOMA with Symmetric SC

          정규혁 한국통신학회 2020 韓國通信學會論文誌 Vol.45 No.10

          In non-orthogonal multiple access (NOMA), the ideal perfect successive interference cancellation (SIC) is validated theoretically by the random channel coding, practically such as low-density parity-check (LDPC) codes or turbo codes. Recently, symmetric superposition coding (SSC) has been shown to achieve the ideal perfect SIC bit-error rate (BER) performance by simulations with as many as three users, while the authors of this letter derived the analytical expression for BER, only for to a two-user scenario. In this letter, the derivation of the closed-form BER expression for M users is reported. It is shown that the SSC NOMA achieves near-perfect SIC BER performance. This is possible for with two reasons; one is the power allocation of the user fairness, and the other is the optimal maximum-likelihood (ML) detection.

        • KCI등재

          Channel Capacity for NOMA under BPSK Modulation

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.2

          We present the channel capacity for non-orthogonal multiple access (NOMA). This paper considers the binary phase shift keying (BPSK) modulation, compared to the ideal signal modulation. It is shown that the channel capacity of the BPSK modulation is different from that of the ideal signal modulation. In result, the power should be allocated effectively, based on the channel capacity of the BPSK modulation.

        • KCI등재

          SSC NOMA Capacity:Zero Capacity Bit to Symbol Mappingover Gaussian Mixture Channel

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.6

          Recently, the symmetric superposition coding (SSC)[6] is proposed for a solution for the error propagation (EP) due to the non-perfect successive interference cancellation (SIC) in non-orthogonal multiple access (NOMA). This paper calculates the channel capacity of NOMA with the SSC. First, we prove that the channel capacity of the strong channel user in the SSC NOMA is zero, if the perfect SIC is assumed. However, it is shown that if this zero capacity bit to symbol mapping is sent over Gaussian mixture channel, the SSC NOMA capacity is greater than that of NOMA with the normal superposition coding (NSC) for the power allocation factor greater than about 20 % or less than about 80 %. We also show that the capacityof the SSC NOMA is the same as that of the NSC NOMA for the power allocation factor less than about 20 %, and the SSC NOMA capacity is worse than the NSC NOMA capacity for the power allocation factor greater than about 80 %. As a result, the SSC should be used to take into account the power allocation.

        • KCI등재

          Performance Comparison of NOMA to Cooperative NOMA

          정규혁 한국통신학회 2019 韓國通信學會論文誌 Vol.44 No.6

          Recently, a newly deployed communications paradigm, cooperative communications, such as decode-and-forward (DF) relaying, have been one of promising candidates for the fifth generation (5G) mobile network. Another strong candidate for 5G radio access is non-orthogonal multiple access (NOMA). In NOMA, successive interference cancellation (SIC) is performed on the strong channel user to compensate for small power allocation. Then as the by-product of SIC, DF relaying can be easily implemented in NOMA. This paper compares NOMA to DF NOMA. We show how much DF NOMA is better than NOMA. This DF NOMA gain is due to the use of the additional time slot resource. In order to compare the two schemes fairly, we assume that NOMA retransmits the information one more time with the additional time slot resource. The contributions of this paper, opposed to the existing researches based on the channel capacity, is that the analytical expressions for the bit error rate (BER) performance are derived and with the use of such analytical expressions, the performance comparisons can be made intensively and flexibly for various system scenarios and channel conditions under the fair conditions.

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