Channel Capacity for NOMA Weak Channel User and Capacity Region for NOMA with Gaussian Mixture Interference

정규혁 한국전기전자학회 2019 전기전자학회논문지 Vol.23 No.1

Non-orthogonal multiple access (NOMA) has been considered for the fifth generation (5G) mobile networks toprovide high system capacity and low latency. We calculate the channel capacity for the weak channel user inNOMA and the channel capacity region for NOMA. In this paper, Gaussian mixture channel is compared to theadditive white Gaussian noise (AWGN) channel. Gaussian mixture channel is modeled when we assume thepractical signal modulation for the inter user interference, such as the binary phase shift keying (BPSK)modulation. It is shown that the channel capacity with BPSK inter user interference is better than that withGaussian inter user interference. We also show that the channel capacity region with BPSK inter user interferenceis larger than that with Gaussian inter user interference. As a result, NOMA could perform better in the practicalenvironments.

Additional Condition on CSCG Random Vectors for I/Q Channels: With Application to CIS in NOMA

정규혁 한국통신학회 2021 韓國通信學會論文誌 Vol.46 No.5

Circularly-symmetric complex Gaussian (CSCG) random vectors (Rvecs) are often used to model practical in-phase and quadrature (I/Q) channels in communication systems. However, we know that CSCG Rvecs do not completely encompass practical I/Q channels. Thus, in this study, we propose an additional condition for CSCG Rvecs to be valid over I/Q channels, namely, a purely-real complex correlation coefficient (CCC). We then investigate the effects of an invalid CCC on the achievable data rate of non-orthogonal multiple access (NOMA) with correlated information sources. Results revealed that a purely-real CCC constraint should be imposed on CSCG Rvecs, when considering practical I/Q channels.

On Sufficient Condition for Power Allocation Range of BER for M- User NOMA

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

Recently, the bit-error rate (BER) for non-orthogonal multiple access (NOMA) with M - user has been derived. However, the ranges of the power allocation coefficients, for which the BER expression holds, are provided as a necessary condition. In this letter, the authors derive a sufficient condition for the power allocation ranges for the BER expression. Such ranges are significant, for each user to avoid the severe performance degradation. In result, the user fairness could be established with the power allocation within the derived ranges.

A Comparison of BER Performance for Receivers of NOMA in 5G Mobile Communication System

정규혁 중소기업융합학회 2020 융합정보논문지 Vol.10 No.8

In the fifth generation (5G) mobile networks, the mobile services require 100 times faster connections. One of the promising 5G technologies is non-orthogonal multiple access (NOMA). In NOMA, the users share the channel resources, so that the more users can be served simultaneously. There are several advantages offered by NOMA, such as higher spectrum efficiency and low transmission latency, compared to orthogonal multiple access (OMA), which is usually used in the fourth generation (4G) mobile networks, for example, long term evolution (LTE). In this paper, we compare the receivers for NOMA. The standard NOMA receiver, the non-SIC NOMA receiver, and the symmetric superposition coding (SC) NOMA receiver are compared. Specifically, it is shown that the performance of the standard receiver is the best, whereas the performances of the non-SIC receiver and symmetric SC receiver are dependent on the power allocation.

Performance Analysis of NOMA with Symmetric Superposition Coding

정규혁 한국전기전자학회 2019 전기전자학회논문지 Vol.23 No.1

Recently, the symmetric superposition coding (SSC) [3] is proposed for a solution for the error propagation (EP)due to the non-perfect successive interference cancelation (SIC) in non-orthogonal multiple access (NOMA). Weanalyze the performance of NOMA with the SSC. It is shown that the performance of the SSC NOMA is the sameas that of NOMA with the normal superposition coding (NSC) for the power allocation factor less than 20%, theSSC NOMA performance is better than the NSC NOMA performance up to the power allocation factor 80%, and theSSC NOMA performs worse than the NSC NOMA for the power allocation factor greater than 80%. As a result, theSSC should be used with consideration of the power allocation.

Microbioassay에 의한 환경독성 평가

정규혁 환경독성보건학회 2000 한국독성학회 심포지움 및 학술발표회 Vol.- No.-

Numerical Analysis of Sufficient Condition on Larger Rate Volume of CIS/non-SIC over IIS/SIC in 3-User NOMA

정규혁,Chung, Kyuhyuk Convergence Society for SMB 2021 융합정보논문지 Vol.11 No.8

Since a sufficient condition on the larger rate volume of 3-user correlated information sources (CIS)/non-successive interference cancellation (SIC) non-orthogonal multiple access (NOMA) over independent information sources (IIS)/SIC NOMA has not been investigated, this paper analyzes such a sufficient condition. First, we demonstrates that the rate volume of 3-user CIS/SIC NOMA is the same as a portion of the rate volume of 3-user IIS/SIC NOMA. Then, by identifying a dominant rate region, we calculate the sufficient condition on the larger rate volume of 3-user CIS/non-SIC NOMA over 3-user IIS/SIC NOMA. We also show that with such condition, the rate volume of 3-user CIS/non-SIC NOMA can be larger than that of 3-user IIS/SIC NOMA.

Damping 요소를 첨가한 매칭 퍼슈잇 정현파 모델링

정규혁,김종학,임정우,주기호,이인성,Jeong, Gyu-Hyeok,Kim, Jong-Hark,Lim, Joung-Woo,Joo, Gi-Ho,Lee, In-Sung 대한전자공학회 2007 電子工學會論文誌-SP (Signal processing) Vol.44 No.1

본 논문은 정현파 모델 기반의 코덱을 위한 매칭 퍼슈잇(Matching Pursuit)의 성능을 개선시킨 새로운 정현파 모델링을 제안한다. 제안하는 damping 요소를 첨가한 매칭 퍼슈잇 정현파 모델링은 과거와 현재 프레임에서 파라미터들간의 상관성을 이용하여 damping 요소를 정의하고 현재 프레임에서 보다 정확한 정현파 파라미터를 damping 요소에 따라 매칭 퍼슈잇 방법으로 추출한 후 합성한다. 따라서 인접 프레임과의 보간 없이 현재 프레임에서의 정현파 파라미터만으로 효율적인 모델링이 가능하다. 제안한 모델링 방법은 보간법을 사용한 일반적인 정현파 모델과 달리 추가지연을 가지지 않으면서 유성음 구간 신호뿐만 아니라 모든 구간에서 개선된 음질을 보인다. 제안한 모델링 방법의 성능을 SNR, MOS값, LR(Itakura-Saito likelihood ratio), CD(cepstral distance)를 통해 보간법을 사용한 매칭 퍼슈잇과 비교 평가한다. In this paper, we propose the matching pursuit with damping factors, a new sinusoidal model improving the matching pursuit, for the codecs based on sinusoidal model. The proposed model defines damping factors by using a correlativity of parameters between the current and adjacent frame, and estimates sinusoidal parameters more accurately in analysis frame by using the matching pursuit according to damping factor, and synthesizes the final signal. Then it is possible to model efficiently without interpolation schemes. The proposed sinusoidal model shows a better speech quality without an additional delay than the conventional sinusoidal model with interpolation methods. Through the SNR(signal to noise ratio), the MOS(Mean Opinion Score), LR(Itakura-Saito likelihood ratio), and CD(cepstral distance), we compare the performance of our model with that of matching pursuit using interpolation methods.

A Study on Improved Sum Rate of Cross-Correlated SC NOMA toward 6G URLLC

정규혁,Chung, Kyuhyuk Convergence Society for SMB 2021 융합정보논문지 Vol.11 No.9

Since recently only an auto-correlated superposition coding (SC) scheme for non-orthogonal multiple access(NOMA) has been investigated, this paper proposes a cross-correlated SC scheme for NOMA. First, we derive the closed-form expression of the sum rate of the proposed cross-correlated SC scheme. Then, numerical analyses demonstrate that the sum rate of the proposed cross-correlated SC scheme is larger than that of the conventional auto-correlated SC scheme. We also show that for the stronger channel gain user, the signal-to-noise ratio (SNR) gain of the proposed cross-correlated SC scheme is about 15, compared with the conventional auto-correlated SC scheme. As a result, the proposed cross-correlated SC scheme could be a promising technology for 6G ultra-reliable low-latency communications (URLLC).

Impact of Channel Estimation Errors on SIC Performance of NOMA in 5G Systems

정규혁,Chung, Kyuhyuk Convergence Society for SMB 2020 융합정보논문지 Vol.10 No.9

In the fifth generation (5G) networks, the mobile services require much faster connections than in the fourth generation (4G) mobile networks. Recently, as one of the promising 5G technologies, non-orthogonal multiple access (NOMA) has been drawing attention. In NOMA, the users share the frequency and time, so that the more users can be served simultaneously. NOMA has several superiorites over orthogonal multiple access (OMA) of long term evolution (LTE), such as higher system capacity and low transmission latency. In this paper, we investigate impact of channel estimation errors on successive interference cancellation (SIC) performance of NOMA. First, the closed-form expression of the bit-error rate (BER) with channel estimation errors is derived, And then the BER with channel estimation errors is compared to that with the perfect channel estimation. In addition, the signal-to-noise (SNR) loss due to channel estimation errors is analyzed.