• 한국통신학회논문지
• /
• 제39A권9호
• /
• pp.508-513
• /
• 2014

자기기록 장치의 저장 밀도 향상을 위해 인접한 트랙을 겹쳐서 쓰는 방식이 사용되고 있다. 따라서 인접한 트랙간 간섭으로 인한 성능 저하를 방지하기 위한 많은 연구가 진행되어 왔다. 본 논문에서는 인접한 트랙간 간섭을 해결하기 위해 인접 트랙간 간섭을 제거하는 모델을 제안하였다. 트랙간 겹치는 정도가 10% 이상인 경우 본 논문에서 제안한 모델이 좋은 성능을 보인다.

• 분석과학
• /
• 제34권5호
• /
• pp.225-230
• /
• 2021

Currently, most photoluminescence reagents used in forensic science have short stokes shift, making it difficult to observe strong photoluminescence due to scattering light from forensic light sources when using filters that are not shieldable. However interference filters can be observed near monochromatic light, making them a better alternative to absorption filters. To verify practical applicability of interference filters, interference filters and three other types of previously frequently used absorption filters were observed using a variety of light source products, and transmission light was cross-compared. Interference filters have a lower slope value than absorption filters, and selectively show only the photoluminescence of reagents, regardless of the type of product from the forensic light source. In addition, tilting the angle of the filter surface for observation lowered the λ_cut-on, which could replace various types of absorption filters with a single interference filter.

• IEIE Transactions on Smart Processing and Computing
• /
• 제3권4호
• /
• pp.181-190
• /
• 2014

This paper reports a cognitive radio network architecture based on overloaded multicarrier direct sequence code division multiple access (O-MC-DS-CDMA). The O-MC-DSCDMA technique combines CDMA with a multicarrier modulation technique to overcome the channel fading effects. In this technique, secondary users are enabled to share the available bandwidth with the existing primary users. Two sets of orthogonal Gold codes are used to support the primary and secondary users simultaneously. The orthogonality between the spreading codes is lost due to the non-zero cross correlation between the codes and the timing synchronization error in the uplink transmission, which causes interference between primary and secondary users. This paper proposes two modified hybrid parallel/successive interference cancellation techniques for primary and secondary user base station receivers with multiple antennas to suppress the interference among users. Interference among the same group of users is cancelled by parallel interference cancellation and the interference among groups is cancelled using successive interference cancellation. The simulation results confirmed that the proposed modified interference cancellation techniques show better BER performance over conventional interference cancellation techniques.

• Journal of Information Processing Systems
• /
• 제17권5호
• /
• pp.933-946
• /
• 2021

In the non-orthogonal multiple access (NOMA) system, multiple user signals on the single carrier are superimposed in a non-orthogonal manner, which results in the interference between non-orthogonal users and noise interference in the channel. To solve this problem, an improved algorithm combining regularized zero-forcing (RZF) precoding with minimum mean square error-serial interference cancellation (MMSE-SIC) detection is proposed. The algorithm uses RZF precoding combined with successive over-relaxation (SOR) method at the base station to preprocess the source signal, which can balance the effects of non-orthogonal inter-user interference and noise interference, and generate a precoded signal suitable for transmission in the channel. At the receiver, the MMSE-SIC detection algorithm is used to further eliminate the interference in the signal for the received superimposed signal, and reduce the calculation complexity through the QR decomposition of the matrix. The simulation results show that the proposed joint detection algorithm has good applicability to eliminate the interference of non-orthogonal users, and it has low complexity and fast convergence speed. Compared with other traditional method, the improved method has lower error rate under different signal-to-interference and noise ratio (SINR).

• 조명전기설비학회논문지
• /
• 제18권4호
• /
• pp.149-154
• /
• 2004

본 논문에서는, 구내용 저간섭 무선통신설비용 시스템으로서 이진 2m(zero-correlation duration) 확산코드를 이용한 저간섭 CDMA(code division multiple access)시스템을 제시하였다. 이진 ZCD확산코드는 확산코드의 주기가 N인 경우 그 값이 4부터 2의 배수로 계속 확장이 가능하기 때문에 코드발생기의 구현이 용이함과 동시에 ZCD 특성을 가짐으로 인해서, CDMA무선통신 시스템을 구내용 무선설비로 사용할 경우에 발생되는 다중접속 및 다중 경로로 인한 간섭문제를 확산코딩기법을 이용하여 근원적으로 해결해주는 역할을 한다. 본 논문에서는 제안한 이진 ZCD확산코드기반의 구내용 저간섭 CDMA시스템의 간섭완화 성능을 확인하기 위하여, AWGN(additive white gaussian noise) 및 MAI(multiple access interference), MPI(multi path interference)와 같은 잡음 및 다양한 간섭 환경 하에서의 BER(bit error rate)특성을 정량적으로 분석하고, 모의실험을 통해 제안시스템의 간섭완화 능력을 입증하였다.

• 한국통신학회논문지
• /
• 제28권8C호
• /
• pp.771-778
• /
• 2003

인접 기지국의 송신 신호는 단말기에서 볼 때 간섭 신호로 작용한다. 이러한 간섭 신호로 인하여 순방향 링크 용량이 줄어든다. 인접 기지국의 파일럿 간섭 신호를 제거함으로써 BER 성능을 개선할 수 있으며 순방향 링크 용량을 개선할 수 있다. 본 논문에서는 순방향 링크 용량을 개선할 수 있도록 인접 기지국에서 송신하는 파일럿 간섭 신호를 제거할 수 있는 복조기 구조를 제안하였다. 모의 실험 결과 인접 기지국의 파일럿 간섭 신호를 제거할 때 BER = 10-2를 얻기 위한 Eb/No 값이 간섭신호를 제거하지 않을 때에 비하여 3㏈ 감소하였다.

• ETRI Journal
• /
• 제34권3호
• /
• pp.297-307
• /
• 2012

A femtocell is a small cellular base station, typically designed for use in a home or small business. The random deployment of a femtocell has a critical effect on the performance of a macrocell network due to co-channel interference. Utilizing the advantage of a multiple-input multiple-output system, each femto base station (FBS) is able to form a cluster and generates a precoding matrix, which is a modified version of conventional single-cell block diagonalization, in a cooperative manner. Since interference from clustered-FBSs located at the nearby macro user equipment (MUE) is the dominant interference contributor to the coexisting networks, each cluster generates a precoding matrix considering the effects of interference on nearby MUEs. Through simulation, we verify that the proposed algorithm shows better performance respective to both MUE and femto user equipment, in terms of capacity.

• 인터넷정보학회논문지
• /
• 제2권3호
• /
• pp.27-36
• /
• 2001

Recently much attention has been paid for interference mitigation technique for the COMA system, since more capacity is available with same bandwidth. In this paper, we introduces a novel adaptive interference suppression techniques for the CDMA system with narrow band interference. The proposed interference rejection scheme employs the adaptive linear prediction techniques in the subband. In each subband, we can more easily find and cancel the narrow band signal as compared to the full band. Thus, the proposed interference rejection can be classified as another time-frequency techniques for the narrow band interference rejection(10). Computer simulation is conducted for the 3-G COMA system with IF band sampling techniques, yielding better interference rejection and bit error rate performance as compared to conventional one. Also, optimum filter is analyzed and from the analysis, it can be shown the subband prediction techniques can suppress narrow band interference more efficiently.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제3권1호
• /
• pp.26-51
• /
• 2009

In this paper, we propose an empirical framework for modeling and emulating interference in multi-hop wireless ad-hoc networks. Wireless interference causes wide variation in the frame delivery rate at a link, and thus we cannot represent the state of the link with only two states, connected state and disconnected state, as in wired networks. We first investigate wireless interference in detail, in order to accurately calibrate the interference and identify its underlying attributes, and then we simulate the diverse occurrences and effects of interference, after incorporating the scheme into a simulation tool. Based on these observations, we devise a modeling and simulation framework with several control parameters, and perform an extensive set of simulation studies. The simulation results indicate that the proposed framework enables us to examine various attributes of wireless interferences and their effects on wireless network protocols and systems.

• Wind and Structures
• /
• 제8권3호
• /
• pp.163-178
• /
• 2005

Wind-induced mean and dynamic interference effects of tall buildings are studied in detail by a series of wind tunnel tests in this paper. Interference excitations of several types of upwind structures of different sizes in different upwind terrains are considered. Comprehensive interference characteristics are investigated by artificial neural networks and correlation analysis. Mechanism of the wakes vortex-induced resonance is discussed, too. Measured results show significant correlations exist in the distributions of the interference factors of different configurations and upwind terrains and, therefore, a series of relevant regression equations are proposed to simplify the complexity of the multi-parameter wind induced interference effects between two tall buildings.