• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.227-228
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• 2008

A diagnosis based on EM is composed of multi-channel transceiver, antennas in illumination tank, liquid and image reconstruction algorithm for solving inverse scattering problem. The antennas in diagnosis were fabricated and measured in lossy liquid. The 10dB impedance bandwidth of the antenna is 600MHz - 3.5GHz

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.51-56
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• 2007

Unitary matrix modulation (UMM) is investigated in multiple antennas system that is called unitary space-time modulation (USTM). When we consider only diagonal components of UMM with splitting over the coherence bandwidth, the system can obtain frequency diversity in a single antenna system. In Rayleigh fading channel, we compared USTM/OFDM with 2Tx-antenna with UMM-S/OFDM with 1Tx-antenna, conventional multi-level OFDM and UMM-S/OFDM with changing bit rate per Hz. Also, we analyzed SNR for between multi-level modulation STBC/OFDM and multi-level modulation UMM-S/OFDM with changing transmission rate. When it was adaptive multi-level modulation to improve SNR, we did the UMM-S/OFDM system performance analysis of N-ary PSK and M-ary QAM.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.24-30
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• 2014

A digital RDA(Retrodirective Antenna) system is a retransmit system that received signal without prior information turn back by estimated phase of the signal to received direction. The RDA can decrease consumption of power by increase of directivity because signal concentrates on received direction compare to omni-direction antenna which transmit power all direction. Generally, the RDA is known to show better performance than the single-antenna system in multi-path environment. However, the RDA occurs performance degradation in serious ISI channel. In this paper, to solve this problem, we propose retrodirective antenna combined with turbo equalizer combined which can compensate serious ISI channel, we increase the BER performance through proposed retrodirective antenna combined with turbo equalizer in serious ISI channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.362-374
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• 2000

In this paper, trellis coded 16 QAM Multi-Carrior CDMA system is proposed, Using the equivalent signal-to-noise plus interference Power ratio (SNIR) of Multi-Carrier CDMA system in the reverse link, capacity and BER performance of trellis coded 16 QAM Multi-Carrier CDMA system are analyzed taking into account the number of multi-carrier, the number of multiple access user, the number of SC/MRC diversity branch, and Rician fading parameter in multiuser interference and Rician fading channel. And the capacity and the BER performance of trellis coded 16 QAM Multi-Carrier CDMA system using selection combining (SC) and maximal ratio cabining (MRC) diversity are numerically compared. Obtained results show that the capacity of proposed system depends on the number of multi-carrier. ti is found that the trellis coded 16 QAM Multi-Carrier CDMA system with SC/MRC antenna diversity scheme is efficient to combat multipath fading and to increase the maximum number of users in high speed data communication. With the results of analysis. MRC diversity technique provides the performance fro high speed data communications. Finally, we present a numerical approach to derive the capacity and the BER performance and to find the maximum number of multiple access user for Multi-Carrier system in multiuser interference and Rician fading channel.

• ETRI Journal
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• v.43 no.3
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• pp.400-413
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• 2021

This paper theoretically and empirically explores the reliability gain that can be obtained by installing multiple antennas in on-vehicle broadcasting receivers. Analytical derivations reveal that maximal-ratio-combining-based diversity allows a multi-antenna receiver (MR) to achieve significantly better coverage probability than a single-antenna receiver (SR). In particular, the notable MR gains for low-power reception and high-throughput services are highlighted. We also discuss various aspects of mobile MRs, including geometric coverage, volume of the users served, and impact of receiver velocity. To examine the feasibility of MRs in the real world, extensive field experiments were conducted, particularly with on-air ATSC 3.0 broadcast transmissions. Relying on the celebrated erroneous second ratio criterion, MRs with two and four antennas were verified to achieve notable reliability gains over SRs in practice. Furthermore, our results also prove that layered-division multiplexing can cope better with receiver mobility than traditional time-division multiplexing when multiple services are intended in the same radio frequency channel.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.173-178
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• 2006

In this paper, a channel estimation based on the time-domain windowing and its imperfectness in OFDM-based multiple-antenna transmission systems are analyzed with an emphasis on a preamble design for multi-channel separation, From the computer simulation results, the OFDM-CDMA system applying a space-time-frequency diversity with a full-rate full diversity code can give the diversity of D = 4 and D = 8 for both multi-user cases of maximum user and half user capacities, respectively

• Journal of Communications and Networks
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• v.9 no.2
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• pp.150-158
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• 2007

We consider channel-coded multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) transmission and obtain a condition on its signal for it to attain the maximum diversity and coding gain. As this condition may not be realizable, we propose a suboptimal design that employs an orthogonal transform and a space-frequency interleaver between the channel coder and the multi-antenna OFDM transmitter. We propose a corresponding receiving method based on block turbo equalization. Attention is paid to some detailed design of the transmitter and the receiver to curtail the computational complexity and yet deliver good performance. Simulation results demonstrate that the proposed transmission technique can outperform the conventional coded MIMO OFDM and the MIMO block single-carrier transmission with cyclic prefixing.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.85-92
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• 2019

This paper presents a SDR-based Long Term Evolution Advanced (LTE-A) Physical Downlink Shared Channel (PDSCH) decoder using a multicore Digital Signal Processor (DSP). For decoder implementation, multicore DSP TMS320C6670 is used, which provides various hardware accelerators such as turbo decoder, fast Fourier transformer and Bit Rate Coprocessors. The TMS320C6670 is a DSP specialized in implementing base station platforms and is not an optimized platform for implementing mobile terminal platform. Accordingly, in this paper, the hardware accelerator was changed to the terminal implementation to implement the LTE-A PDSCH decoder supporting the multi-antenna and the functions not provided by the hardware accelerator were implemented through core programming. Also pipeline using multicore was implemented to meet the transmission time interval. To confirm the feasibility of the proposed implementation, we verified the real-time decoding capability of the PDSCH decoder implemented using the LTE-A Reference Measurement Channel (RMC) waveform about transmission mode 2 and 3.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.4
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• pp.28-34
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• 1975

텔레비젼 수신용 안테나로써 가장 널리 사용되고있는 Yagi안테나는 구조가 간단하고 지향성 이득등이 좋으나 방사주파수에 대한 반파장길이의 소자를 사용하므로 칫수가 커지고 주파수대역이 좁다. 따라서 설치 취급등에 불편을 느낄 경우가 많다. 한편 최근 일반적으로 아무곳에서나 용이하계 설치할 수 있을만큼 소형이면서 화질이 좋은 수상이 가능한 수신안테나에 대한 요망이 커지고 있는데 본 연구에서는 그 파장에 비해서 소형인 폴디드·다이폴 안테나 소자 2개를 좁은 간격으로 배열하고 이들을 이상결합하므로써 VHF텔레비젼전파의 고채널 주파수대에서 비교적 양한 단일지향성을 얻고 있다. 본 안테나에 능동소자를 이용한 저잡음광대역증폭기를 삽입한다면 다소자 Yagi안테나에 비나될 전후방비를 갖는위에 그의 이득도 크게 증가되어 일반수상안테나로 뿐만 아니라 고우스트 방지용실내안테나로서 상당한 기여틀 할것으로 생각된다. The Yagi antenna, which is most widely used for television receiving, has simple form and good directiyity as well as high gain, but it must be made with linear elements of half wave length. Therefore, the dimension of multi-element Yagi antenna becomes bulky and so a(ten it is inconvenient to install and handle, because of its big size. Moreover the frequency band width of the Yagi antenna is usually not broad enough to cover the total frequency range of VHF TV channels in our country. Recently, the aemand for an antenna which is not only small enough to install it easily anywhere but also assures good quality of pictures is generally increasing. In this study 2 elements o( folded dipole, which is small compared to its electrical ways length, are fixed parallel to each other with a narrow distance and the emfs induced in them are made to get together with some phase difference. This new phased array antenna has shown a relatively good unidirectivity through over the high channel VHF television frequency hand as well as the good PIB ratio which is comparable to that of multielements Yagi antenna. As a result this new antenna will be used as a VHF high channel TV receiving antenna and it may become better antighost antenna when used inside the room than other room antennas.

• Journal of Communications and Networks
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• v.10 no.2
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• pp.127-136
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• 2008

For mobile wireless systems with full frequency reuse, co-channel interference near the cell coverage boundaries has a significant impact on the signal reception performance. This paper addresses an approach to efficiently mitigate the effect of downlink co-channel interference when multi-antenna terminals are used in cellular environments, by proposing a signal detection strategy combined with a system-level coordination for dynamic frequency reuse. We demonstrate the utilization of multi-antennas to perform spatial demultiplexing of both the desired signal and interfering signals from adjacent cells results in significant improvement of spectral efficiency compared to the maximal ratio combining (MRC) performance, especially when an appropriate frequency reuse based on the traffic loading condition is coordinated among cells. Both analytic expressions for the capacity and experimental results using the adaptive modulation and coding (AMC) are used to confirm the performance gain. The robustness of the proposed scheme against varying operational conditions such as the channel estimation error and shadowing effects are also verified by simulation results.