• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.410-418
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• 2022

Channel reliability estimation for iterative codes such as turbo codes is very important factor in time varying underwater acoustic channel, an incorrect estimation of channel reliability induced performance degradation. Therefore, this paper presents an optimal channel reliability estimation method for turbo coded FSK signal with rate of 1/3. The estimated BER algorithm is a method that can estimate the reliability of received data by comparing received data and decoded data, and we determine optimal channel reliability by using the method. In order to analyze the performance, the experiment was conducted on a lake in Munkyeong city by moving in the range of 300 m to 500 m. At the result of applying presented method to failed decoding packets, we confirm all packets are decoded successfully.

• Journal of Digital Convergence
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• v.20 no.1
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• pp.185-190
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• 2022

Bluetooth is a common wireless technology that is widely used as a connection medium between various consumer electronic devices. The Bluetooth receiver usually adopts a Viterbi algorithm to improve signal-to-noise ratio performance, but requires complex hardware and calculations for continuous search and estimation for the irrational modulation indexes at the transmission. This paper proposes a non-coherent maximum estimation based 8-State Viterbi FSM to solve these complexity problems. The proposed optimal Viterbi FSM can detect Gaussian frequency-shfit keying symbol without any prior information and estimation for the modulation indexes. The HV1/HV2 packets are used for the estimation of the proposed algorithm and the simulation results have shown performance improvements with about 2dB for 10^-3 BER compared to other ideal approaches such as decision direct method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.265-271
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• 2023

Recently, location information services are gradually expanding due to the development of information and communication technology. RSSI is widely used to extract indoor and outdoor locations. The indoor and outdoor location estimation methods using RSSI are less accurate due to the influence of radio wave paths, interference, and surrounding wireless devices. In order to improve this problem, a distance estimation method that takes into account the wireless propagation environment is necessary. Therefore, in this study, we propose a distance estimation algorithm that takes into account the radio wave environment. The proposed method estimates the distance by learning RSSI input and output considering the RBF neural network and the propagation environment. To evaluate the performance of the proposed method, the performance of estimating the location of the receiver within a range of up to 55[m] using a BLE beacon transmitter and receiver was compared with the average filter and Kalman filter. As a result, the distance estimation accuracy of the proposed method was 6.7 times higher than that of the average filter and Kalman filter. As shown in the results of this performance evaluation, if the method of this study is applied to location services, more accurate location estimation will be possible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7C
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• pp.946-953
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• 2004

Fast search and conventional boolean matching motion estimation algorithms reduce computational complexity and data processing time but this algorithms have disadvantages that is difficult of implementation of hardware because of high control overhead and that is less performance than Full search Algorithm(FA). This paper present new all binary block matching algorithm, called Bit Converted All Binary Block Matching(BC-ABBM). Proposed algorithm have performance closed to the FA by boolean only block matching that may be very efficiently implemented in hardware for low bit rate video communication. Simulation results show that the PSNR of the proposed algorithm is about 0.04dB loss than FA but is about 0.6 ∼ 1.4dB gain than fast search algorithm and conventional boolean matching algorithm.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.204-210
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• 2012

In this paper, we study the method of estimating direction of departure(DOD) and direction of arrival(DOA) using estimation of signal parameters via rotational invariant techniques (ESPRIT) in uniform linear array MIMO radar system. While it is possible to improve the resolution by increasing the numbers of physical antennas and snapshots after matched filtering, such methods generally give rise to increase in complexity. In this paper, we propose to improve the resolution by optimally allocating the number of transmit and receive antennas. In particular, we show that the performance is optimized when the number of the receive antennas is approximately twice that of transmit antennas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.760-770
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• 2002

Transmit diversity is an efficient diversity technique to improve performance and spectrum efficiency in wireless communication . Coding scheme designed for the transmit diversity is called space-time coding. In this paper, we propose a training structure to apply the transmit diversity to improve the performance of IEEE802.11a OFDM systems. Based on this training structure, we propose a channel estimation scheme using curve fitting. Also we compare and evaluate the performance of space-time codes. The performance of both diversity using space-time codes and channel estimation scheme is investigated by computer simulation in quasi-static 2-ray rayleigh fading environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2643-2648
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• 2012

In the RFID Sytem, When leaders recognize the tag, a anti-collision scheme is an important factor in the performance of the system. Probabilistic-based anti-collision scheme using the slot status is a technique to estimate the number of tags. the schemes to quickly and accurately estimate the number of tags has been a lot of research. However, A initial number tag are not considering in the number of tags unknown environment. In the paper, estimation scheme for the initial number of tag is proposed to solve the problems. we analyze the performance by the initial number of tag and the proposed scheme.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.52-57
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• 2001

The passive ranging estimation techniques using a focused beamformer have been studied under the water. It is well known that the passive ranging estimation method using a focused beamformer is excellently evaluated. Among these, the passive ranging sonar is known to have a good performance under low signal-to-noise. ratio. However, its performance is degraded in multi-source environments. In this paper, we proposed the technique using dual focused beamformers to estimate the range. And when the sampling frequency is low, it is very difficult to steer the focused beam to the desired direction, as a result of this, the low performance occurs because of a distorted beam pattern. In this paper, we study the effect of sampling rate on passive ranging by using focused beamformer. And we verified the performance of the proposed method via computer simulation.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.87-90
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• 2000

Differential channel 정보를 feedback 하는 close loop Tx diversity를 제안한다. 본 Tx diversity는 기존의 channel feedback Tx diversity 보다 W-CDMA의 forward link와 reverse link channel 용량을 더 많이 늘린다. Differential channel 정보를 estimation 하는 방법을 제안한다. 부가적으로 보내는 정보 없이 W-CDMA의 forward power control 에 사용하는 dedicated pilot 심볼을 이용해 differential channel 정보를 estimation한다. 기존에 제안된 channel feedback Tx diversity들과 성능을 비교한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7B
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• pp.1194-1203
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• 2000

본 논문에서는 신호대 간섭비(SIR)의 추정에 채널 추정 값을 이용하지 않는 방식을 제시한다. 제시된 SIR 추정방법은 기존의 방법에 비해 계산의 복잡도 면에서 다소 우수한면서도, 같은 SIR의 추정 값을 가진다. 한편, 전력제어를 수반한 시스템에서는 페이딩 채널의 통계적인 특성이 달라지게 되므로 이에 적합한 채널 추정 방법을 제시하고 그 성능을 분석하였다. 그 결과 도플러 주파수가 증가할수록 제안된 채널 추정 알고리즘이 성능이 우수함을 알 수 있었다.