• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.43-49
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• 2014

In this paper, we consider the performance evaluation of space time block code (STBC)) with coordinate interleaved orthogonal design (CIOD) over time selective channel. In case of quasi static channel, STBC-CIOD satisfies full rate and full diversity (FRFD) property with the single symbol decoding. However in the time selective channel, the symbol interference degrades the system performance when we employ the single symbol decoding. We derive the union bound of the symbol error probability by evaluating the pairwise error probability in the first order Markov channel. We also present simulation results of STBC-CIOD with QPSK.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.205-211
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• 2006

This paper considers the maximum likelihood (ML) detection of 16-ary differential amplitude and phase shift keying (DAPSK) in Rayleigh fading channels. Based on the conditional likelihood function, two new receiver structures, namely ML symbol-by-symbol receiver and ML sequence receiver, are proposed. For the symbol-by-symbol detection, the conventional DAPSK detector is shown to be sub-optimum due to the complete separation in the phase and amplitude detection, but it results in very close performance to the ML detector provided that its circular amplitude decision thresholds are optimized. For the sequence detection, a simple Viterbi algorithm with only two states are adopted to provide an SNR gain around 1 dB on the amplitude bit detection compared with the conventional detector.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.4
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• pp.39-46
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• 1994

In this paper, the idea of using a multiple symbol obervation interval to improve error probability performance is applied to differential detection of MTCM(multiple trellis code modulation) with ${\Pi}$/4 shift QPSK, 8DPSK and 16DPSK. We propose two types of sliding multiple symbol differential detection algorithm, type 1 and type 2. The two types of sliding detection scheme are examined and compared with conventional(symbol-by-symbol) detection and bolck detection with these modulation formats in an additive white Gaussian noise(AWGN) using the Monte Carlo simulation. We show that the amount of improvement over conventional and block detection depends on the number of phases and the number of additional symbol intervals added to the observation. Computer simulagtion results are presented for 2,4,8 states in AWGN channel.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.34-40
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• 2019

In spatial modulation (SM), both the signal symbol and spatial symbol, i.e., the index of the antenna from which signal symbol is transmitted, carry information. To increase the number of bits carried by spatial symbols, more transmit antennas are required. In the generalized SM (GSM), the same signal symbol is transmitted from a combination of antennas, resulting in a reduction in the number of antennas required to achieve a given spectral efficiency. In this paper, we propose a rotated-symbol GSM (RGSM), in which the signal symbol is rotated with an angle corresponding to the position of the antenna index within the combination. This increases the number of spatial symbols by a factor equivalent to the length of the antenna combinations of the GSM. Numerically, SM, GSM and RGSM require 128, 17 and 12 transmit antennas to convey seven bits through the spatial symbols. Simulation results show that RGSM performs relatively close to GSM, and in several system settings, their error performances coincide.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.513-519
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• 2018

OFDM modulation has been used for a transmission scheme in 4G LTE (Long Term Evolution) and Wi-Fi systems to mitigate the effects of frequency selective fading channels. An OFDM modulation is a block transmission scheme because an OFDM symbol consists of multiple subcarriers with narrow bandwidth. Therefore, all OFDM symbols in a frame should be filled out with data and padding bits. Depending on the amount of data, more padding bits than information bits can occupy the last OFDM symbol. Such inefficiency causes the loss of throughput. To overcome this problem, an efficiency padding method is proposed by using the property of DFT (Discrete Fourier Transform). In the proposed method, symbol duration of the last symbol is changed depending on the number used data subcarriers in the last symbol. With numerical evaluation, it is examined that throughput enhancement achieved by the proposed method can be about 20% depending a transmission scheme and data length.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.671-678
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• 2005

This paper proposed symbol rate method which does not require a priori knowledge on the symbol rate and simplified modulation identification method to classify BPSK, QPSK, 8PSK signal. In order to estimate the unknown symbol rate, sliding FFT and simple moving average to estimate the spectrum of the signals is utilized, and sliding window and decimation, LPF blcok to estimate the proper symbol rate is used. Although conventional modulation ID method must use SNR value as the test statistics, the receiver cannot estimate the SNR value since the receiver cannot know the modulation type at the start of communication, and bit resolution is high due to using nonlinear function such as log, cosh. Therefore, we proposed the simplified fixed SNR value method. The performance of symbol rate estimation and modulation ID is shown using Monte Carlo computer simulation. This paper show that symbol rate estimation also has good performance in low SNR, and proposed simplified fixed SNR method has almost equivalent performance compared to conventional method.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.2
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• pp.168-174
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• 2012

This paper describes a novel global on-chip interconnect scheme, in which a one UI-delayed symbol as well as the current symbol is sent for easing the sensing operation at receiver end. With this approach, the voltage swing on the channel for reliable sensing can be reduced, resulting in performance improvement in terms of power consumption, peak current, and delay spread due to PVT variations, as compared to the conventional repeater insertion schemes. Evaluation for on-chip interconnects having various lengths in a 130 nm CMOS process indicated that the proposed on-chip interconnect scheme achieved a power reduction of up to 71.3%. The peak current during data transmission and the delay spread due to PVT variations were also reduced by as much as 52.1% and 65.3%, respectively.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.27-33
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• 2013

In this paper, we propose a pilot based channel estimation technique in two-way relay networks. We propose to transmit a pilot symbol together with the data symbol during transmission. In absence of Channel State Information (CSI), destination uses the pilot symbol to estimate the channel. In this system, the relay amplifies the pilot and the data symbol then forward them to the destination using amplify and forward (AF) protocol. We assume that the relay gain is fixed, so the relay does not need to estimate the channel, the destination only estimate the channel. We apply well-known Least-square (LS) and minimum mean-square error (MMSE) channel estimation methods to estimate the channel.

• Archives of design research
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• no.18
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• pp.63-73
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• 1996

In the confusion of communication, the monogram is the very important symbol of information communication as the visual language for the identity, which have became gradually the important role as the most excellent competence of the visual message. By study the nature, function and symbolism of a monogram in formative element of symbol design, we have the aims in this study to help the design study groups in this country to develop the korean monogram with a correct understanding of mooogram in the present state of korean monogram.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.3
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• pp.305-314
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• 2001

In this paper, we construct an automatic evaluation system of psychological feeling for corporate identity (CI) symbol mark based on a fuzzy neural network technique. The system is modelled by trainable fuzzy inference rules with several input variables (qualitative and quantitative design components of CI symbol mark) and a single output variable (consumer's feeling). The back propagation learning algorithm, which is a conventional learning method of multilayer feedforward neural networks, is used for parameter identification of the fuzzy inference system. The learning ability to train data and the generalization ability to test data are evaluated for the proposed evaluation system by computer simulations.