Earticle

본 논문에서는 항재밍 GPS(Global Positioning System) 시스템을 위한 선형 어레이 안테나(linear array antenna) 시뮬레이터 (simulator)를 설계하고 시뮬레이션을 통해 다양한 성능 평가를 수행하였다. 먼저 GPS 위성의 신호 구조 분석을 통해 모의 송신 신호를 발생시키고, 선형 어레이 안테나 고려시 잡음 환경하에서의 어레이 수에 따른 SNR(Signal to Noise power Ratio) 성능을 분석하였다. 또한 MMSE(Minimum Mean Square Error) 방식의 신호처리 시스템을 통해 재머(jammer) 수에 따른 항재밍 빔패턴 (beam pattern) 성능을 분석하였으며, 안테나 칼리브레이션(calibration) 문제를 고려하여 어레이간 지연이 존재하는 경우에서의 항 재밍 성능을 분석하였다.

In this paper, I design a linear array antenna simulator for anti-jamming GPS systems and perform various performance analysis by simulation. First, I generate simulated transmission signals through the analysis of GPS satellite signal structure, and analyze SNR(Signal to Noise power Ratio) performance of linear array antenna according to number of arrays under noise environments. In addition, I analyze the performance of the anti-jamming beam pattern using MMSE(Minimum Mean Square Error) signal processing method, and also analyze the anti-jamming performance considering antenna calibration problem when there are different delays between arrays.

본 논문에서는 적응형 배열 안테나에 적용되는 대표적 항재밍 기술로 알려진 STAP 및 SFAP 신호처리 방식의 시뮬레이션 성능을 비교 분석하였다. 시뮬레이션을 위해 두 방식의 가중 벡터(weighting vector)를 추정하는 방법으로 공통적으로 MMSE(Minimum Mean Square Error) 알고리즘을 사용하여 다양한 재밍환경에서 시뮬레이션을 통한 성능을 제시하였다. 특히, 재밍 전력 J/S(Jamming to Signal Power Ratio)에 따른 STAP 및 SFAP 성능 비교 분석, 신호대역에 대한 재밍 대역의 비율에 따른 성능 비교 분석 및 두 방식간 BER 성능을 비교하여 재밍 환경에 따른 항재밍 성능을 분석하였다.

In this paper, a comparative studies on the STAP and SFAP were performed, which are known as representative anti-jamming technology for adaptive array antenna. As a method of estimating the weighting vector for simulation, MMSE(Minimum Mean Square Error) algorithm was commonly used and the analyses of the simulation performance in various jamming environments were presented. Especially, performance comparison between STAP and SFAP according to the jamming power J/S(Jamming to Signal Power Ratio), performance comparison in the ratio of jamming bandwidth to signal bandwidth, and performance comparison of BER between STAP and SFAP were presented.

무선전력전송은 별도의 전송선로 없이 에너지를 전달하는 기법으로, 기존의 무선통신에서의 신호가 아닌 에너지 자체의 전달을 목적으로 한다. 원거리 마이크로파 전력송수신기는 RF 발진회로, 고이득 안테나, 정류회로 등으로 구성되는데, 상용화를 위해서는 저렴한 고출력 발진회로 및 설치가 용이한 안테나 설계의 어려움이 해결되어야할 과제이다. 이것 때문에 발진회로와 개별 안테나가각각 연결된 에너이로 구성된 시스템 채택이 예상된다. 본 고찰는 무선전력 송수신기의 전력계통의 영향 분석 일환으로 수행하였다.

Wireless power transmission (WPT) is a technology using free space as a conductor for transmitting electric power, whichaims to transfer not just the transmission signal but also the electrical energy itself. This paper takes issue with themicrowave wireless transmission technology utilizing in long-distance transmission. To construct the WPT system, severalcomponents are needed, such as RF Oscillator which converts AC power to RF through DC status, high gain antenna andRF rectifier that converts RF back to DC. The array topology is good a candidate for wide use. The objective of this researchis to study the efect of the WPT systmem on electric power system.

본 논문에서는 ITS 서비스 구성 요소 중의 하나인 BIS(Bus Information System)의 기지국용 전방향성 안테나를 설계 및 제작하고 그 특성을 측정하였다. 제작된 BIS 기지국용 안테나는 전주시 도심의 주요 교차로의 신호등 gantry에 설치된다. 통신 영역이 차선의 개수와 교차로 크기, 도로의 방향에 따라 상이한 경우에도 요구된 통신 성능을 얻기 위해 최대 loom 통신 영역을 화보하기 위해 10dBi 정도의 고 이득이 요구된다. 이를 위해 OMA(Omni-directional Planar Microstrip Antenna)를 배열한 구조를 적용하였다. 제작된 안테나의 동작 중심 주파수는 5.8GHz이고, 반사손실은 -10 dB를 기준으로 640MHz 이상, 이득은 10.3dBi를 얻었으며, 빔 패턴은 전방향성으로 시뮬레이션 결과와 측정 결과가 유사하게 나타나고 있다.

This paper describes the design, fabrication, and measurement of a omni-directional beam pattern antenna for base station of the BIS which is one of the ITS services. The antenna is installed on the signal lamp of important crossroad and provides the wireless communication link between vehicles and RSE(Road Side Equipment). The required characteristics of BIS base station antenna are omni-directional beam pattern and specific beam pattern by the road and install environment and installed place of OBU. To get omni-directional beam pattern of antenna, Array configuration and OMA are applied. The measured results of fabricated antenna are as follows; return loss of 640MHz by -10 dB, and a gain of 10.3dBi. It is found that the measured beam patterns are similar to design results

본 논문에서는 ITS 서비스 구성 요소 중의 하나인 ETCS(Electronic Toll Collection tsystem)에서 RSE(Road Side Equipment) 기지국 gantry에 장착되어 이동체와 무선 통신 링크를 연결해 주는 ETCS 기지국유 안테나를 설계 및 제작하고 그 특성을 측정하였다. ETCS 기지국용 안테나 특성은 적은 부엽 특성과 도로 상황과 이동체 탑재되는 OBU 위치에 따라 특정 형태의 빔 패턴이 요구된다. 또한 반사에 의한 multipath 신호 영향을 최소화하기 위해 원형편파 특성이 요구된다. 저 부엽의 빔 패턴을 얻기 위해 배열 패치 구조와 Taylor distribution에 의한 방사요소의 전류 weighting factor를 적용하였다. 제작된 안테나의 동작 중심 주파수는 5.8GHz이고, 반사손실은 -10 dB를 기준으로 130 MHz, 10MHa사용 대역내에서 축비 2.6 dB이하의 RHCP 편파 특성과 17 dBi 이득을 얻었으며, 빔 패턴은 시뮬레이션 결과와 측정 결과가 잘 일치하고 있음을 보여주었다.

This paper describes the design, fabrication, and measurement of a low side lobe antenna for RSE base station of the ETCS which is one of the ITS services. The antenna is installed on the gantry of road side and provides the wireless communication lint between vehicles and RSE. The required characteristics of ETCS base station antenna are low sidelobe and specific beam pattern by the road and install environment and installed place of OBU. To minimize the affects of multipath signal by reflection, Circular polarization is required. To get low sidelobe of antenna, array configuration and weighting factor by Taylor distribution in radiator elements are applied. The measured results of fabricated antenna are as follows; return loss of 130MHz by -10dB, an axial ratio of 2.6dB, and a gain of 17dBi. It is found that the measured beam patterns are similar to design results.

This paper considers a broadband multicell system with key characteristics that base-stations and relays employ beamforming via large antenna arrays, as well as in-band full duplex relay operation. The signal to interference plus noise ratio gain (which is in excess of the maximum required for such a system) could be exploited either for reducing self-interference or the backhaul and access link transmitted powers. The presented results indicate that with a moderate front-to-back-ratio scenario for the antenna array, “small” antenna arrays with 8 elements can lower the requirement of full duplex self-interference cancellation by up to 55 dB, while large antenna arrays of 1024 elements will produce 100 dB reduction. Alternatively, for the same scenario, both the backhaul and access transmitted powers could be reduced by ∼55 dB and ∼25 dB with 1024 elements.

Steering vector and covariance matrix estimation mismatch along with moving jammer/platform, can affect the performance of null-steering beamformer. In this paper, by utilizing null-widening, null-deepening and diagonal loading shrinkage in space?time adaptive processing (STAP) structure, two methods for nullifying GNSS (global navigation satellite system) jamming/interference in cruise moving platforms are introduced. The enhanced performance of the proposed methods is investigated through numerical simulations. The results indicate improvement in the number of acquired GNSS satellites, in heavy jamming (GNSS denied) scenario, by reconstructing and acquiring at least 87% of satellites.

This paper provides a space temporal interference cancellation method for ultra wide-band (UWB) communication systems based on combination of tapped delay line array antenna and orthogonal matched filter. In order to reduce the interference from the other system using overlapping frequency band, space domain signal processing such as an array antenna has been proposed. However, principal array antenna cannot be applied to impulse radio (IR) UWB because IR-UWB does not have carrier signal. In this paper, we propose a novel tapped delay line array antenna combined with orthogonal matched filter detector. From the numerical evaluation, we show that the proposed system can make null direction to face to the interference signal direction. Additionally, we show that the proposed system can reduce interference signal even if the interference signal has equivalent pulse shape and equivalent incoming direction.

Since most studies for estimating an angle-of-arrival (AOA) based on the antenna array have considered the antenna array with a single configuration, they are not proper to simultaneously estimate AOAs of multiple signals with various frequencies. In this paper, we introduce a cascade AOA estimation technique consisting of CAPON and Beamspace Multiple Signal Classification (MUSIC), based on a Combined Array Antenna (CAA) with Uniform Rectangular Frame Array (URFA) and Uniform Circular Array (UCA), for enhancing the above problem. In addition, we provide the computational complexity analysis for showing the low computational complexity of this technique comparing to the conventional technique.

This paper newly proposes a direct antenna array control approach to reduce channel spatial correlation for multiuser spatial multiplexing. Conventional rectangular arrays can form three dimensional beams and have superior signal separation performance compared to linear arrays. However, when the arrival angles of some signals are close, the signal separation (interference cancellation) performance deteriorates since the projection points onto horizontal/vertical axes of several antenna elements overlap and spatial resolution along each axis is degenerated. The key proposal is to improve signal separation performance by mechanically changing the positional relationship of antenna elements. The proposed scheme can achieve better Bit Error Rate (BER) performance by searching the optimal antenna rotation angle.

Adaptive smart antenna arrays are used for cellular communication. This paper presents a comparative study of beamforming techniques for adaptive smart antenna using hybrid algorithms like Simple Matrix Inversion with Recursive Least Square (SMI-RLS) and Least Mean Square with Recursive Least Square (LMS-RLS) algorithm. The results are compared on the basis of null depth and error plot for different signal –to-noise (SNR) values, ranging from high to low values of SNR for heavily faded case..

위성방송수신 및 위성 양방향 인터넷, VSAT 등의 위성통신서비스를 차량 이동 시에도 이용할 수 있기 위해서는 차량에 탑재하기 용이하도록 소형이며 높이가 낮은 안테나 구조가 요구된다. 또한 중위도 지역에서 평면 안테나 상태로 45도 틸트 특성을 갖고, Ku 밴드의 위성통신용으로 충분한 고이득을 얻기 위해, 빔폭이 좁고 사이드로브가 적으며 저손실 구조의 배열안테나 개발이 필요하다. 본 논문에서는 이러한 성능을 만족시키기 위해, 진행파형 누설파 모드를 기초로 한 수직 편파로 동작하는 도파관 종방향 슬롯 배열안테나를 제안하였다. 16개 누설파 소자의 배열안테나 이득은 30 dBi 이었으며, 빔폭은 4.9도, 사이드로브 레벨은 -20 dB 이하, 중심주파수에서 빔틸트 각도는 45도를 얻었다. 급전선로는 도파관의 병렬급전 방식으로 설계하여 광대역, 저손실 특성을 얻을 수 있었다.

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ku-band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. An array antenna consisting of 16 leaky-wave elements is showing 30 dBi of gain, 4.9 degree of beamwidth, below than -20 dB of sidelobe level, 45 degree of beam tilt angle in center frequency. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.

The structure of MMSE receiver front-ended by CMA(Constant Modulus Array) array working in CDMA forward link which is applicable to LEO spread spectrum satellite communication system is proposed. By using the despreaded pilot signal of forward link as a reference signal, the CMA array can capture multi-path signals securely even in severely faded LEO satellite channel. The remaining MAI (Multiple Access Interference) is cancelled by the cascaded MMSE receiver. Besides theoretical development, through relevant computer simulation, it is proved that the proposed system shows much better BER performance than any other possible candidate systems. As a spatio-temporal receiver mounted on a mobile vehicle, the proposed system also reduces implemental cost and complexity by adopting the simplest algorithm for its spatial and temporal domain processing.