• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.428-438
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• 2021

For long-range communication in deep water, low carrier frequency is efficient due to a decrease in transmission loss. However, there is a limitation in that the data rate decreases due to a narrow bandwith. In order to increase the data rate in an environment with a limited bandwidth, it is necessary to design a higher-order modulation scheme. This paper analyzes the long-range communication data modulated by higher-order modulation schemes. The long-range communication experiment (23 km ~) was conducted in East Sea in October 2020. During the experiment, a vertical line array was utilized and communication sequences were modulated by Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM) schemes and transmitted by a towed source. In more detail, PSK modulation consists of quadrature PSK and 8PSK, QAM modulation consists of 8QAM and 16QAM. Time reversal processing is applied to mitigate inter-symbol interference by utilizing the correlation between received signals and channel impulse responses. All modulation schemes show successful results at 23 km range, demonstrating the feasibility of higher-order modulation in long-range communication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.399-401
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• 2013

In this paper, we present the method to impove the performance by using iterative decoding in LDPC codes with 8-PSK modulation. Iterative decoding is the technique that improve the performance after the input signals of receiver are re-calculated by using the soft decision output of decoder. DVB-S2 system with 8-PSK modulation based on iterative decoding had a better performance than DVB-S2 with 8-PSK modulation over Gaussian channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11C
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• pp.682-693
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• 2011

Energy spreading transform (EST) based modulation is an effective technique to combat frequency-selective fading in broadband wireless communication. It performs close to the inter-symbol interference (ISI)-free matched filter bound (MFB) only at the complexity of a linear detector. Originally, EST-based modulation has been proposed for QPSK. However, to fully utilize the capacity of multipath fading channels, higher-order modulations are also necessary. In this paper, we review the EST based modulation that has originally been proposed for QPSK and discuss its extension to 8 PSK and 16 QAM. The performance of the extended system is verified through simulation in Proakis B and 8-tap fading channel. The EST based modulation for 8 PSK shows the performance which is very close to MFB and the EST based modulation for 16 QAM shows the performance gap between its receiver and MFB.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.211-216
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• 2014

In this paper, high throughput method is studied to provide floating objects with broadband service as ship by using satellite. In recent, satellite broadcastings standard is based on DVB-S3 for communication service using wireless device on navigation communication by satellite. LDPC codes are iterative coding algorithm proposed in DVB-S3. In this paper, FTN technique is applied to LDPC codes with 8-PSK modulation and then present the method to alleviate performance degradation due to FTN through BICM-ID. BICM-ID is the method to improve performance by calculating a new LLR from hard-decision value of decoder output. DVB-S2 system with 8-PSK modulation and FTN technique based on iterative decoding had a better performance than DVB-S2 with 8-PSK modulation and FTN technique over Gaussian channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.843-850
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• 2016

This paper introduces a novel modulation scheme for vehicular communication in taking advantage of existing LED lights available on a car. Our proposed 2-Phase Shift Keying (2-PSK) is a spatial modulation approach in which a pair of LED light sources in a car (either rear LEDs or front LEDs) is used as a transmitter. A typical camera (i.e. low frame rate at no greater than 30fps) that either a global shutter camera or a rolling shutter camera can be used as a receiver. The modulation scheme is a part of our Image Sensor Communication proposal submitted to IEEE 802.15.7r1 (TG7r1) recently. Also, a neural network approach is applied to improve the performance of LEDs detection and decoding under the noisy situation. Later, some analysis and experiment results are presented to indicate the performance of our system

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.752-759
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• 2010

The low power consumption is the most important design factor for the In-Body communication system of WBAN. The conventional PSSK (Phase-Silence-Shift-keying) modulation technique can be regarded as an extension from PSK modulation. And this PSSK has better power efficiency than PSK modulation, and higher spectral efficiency than FSK modulation. PSSK modulation is to transmit two orthogonal symbols. The transmission power can be lowered because the symbol rate in signal period becomes half. BER performance is improved because transmission power is lower and the modulation symbol distance is widened. In addition, PSSK preserve the low-power and increase the data rate than FSK. In this paper, we analyzed existing PSSK and like to propose a new PSPM (Phase-Shift-Position-Modulation) modulation scheme. This PSPM is evaluated in terms of considered bandwidth efficiency and BER performance, compared with the PSSK. This PSPM modulation method transmits the information data by both PSK symbol data and symbol position data, so that we can significantly improve the power efficiency. New proposed PSPM method could be very useful for the In-body communication that requires the most power efficient system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.12
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• pp.1792-1799
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• 1990

Two cases of block coded phase/frequncy modulations are investigated. minimum Euclidean distances are calculated as the function of modulation index h and rotation angle \ulcorner in the cases of 2-FSK/4-PSK and 2-FSK/8-PSK. Method of signal set partitioning is described, especially for the case of 2-FSK/8-PSK. The results are compared with S.I. Sayegh's work and shown better performance. For example, with simple parity check and repetition codes, we can get coding gain of 3 dB in the case of 2-FSK/4-PSK with block length n=4. We get 5.33 dB in the case of 2-FSK/8-PSK with n=4. And it is believed that we can get higher coding gain with proper combinations of block code and n-FSK/m-PSK type channel signal constellations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1769-1776
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• 2000

In this paper a new method is proposed to identify a modulation method in the case of unknown digitally modulated input signals. The proposed identification method is implemented with an artificial neural network which is based on characteristic feature extracted from the instantaneous amplitude the instantaneous phase and the instantaneous frequency of the input signals. The proposed method was simulated with 9 type signals (ASK2, FSK2, FSK4, PSK2, PSK4, PSK8, QAM8, QAM16) in a noisy communication environment. The results show that the artificial neural network can accurately recognize all kinds of patterns.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.784-789
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• 2006

In this paper, we propose a bitwise information decomposition algorithm for an M-PSK signal based on the Max-Log-MAP algorithm. In order to obtain the algorithm, we use a coordinate transformation from M-PSK to M-PAM signal space. Using the proposed algorithm, we analyze the performance of a Turbo iterative decoding method. The proposed algorithm can be applicable not only for a communication with PSK and iterative decoding method but for adaptive modulation and coding system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.10
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• pp.1147-1156
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• 1992

In this paper, in order to apply the $\pi/4$ shift QPSK to TCM, we propose the $\pi/8$ shift 8PSK modulation technique and the trellis-coded $\pi/8$ shift 8PSK performing signal set expansion and partition by phase difference. In addition, the Viterbi decoder with branch metrics of the squared Euclidean distance of the first phase difference as well as the Lth phase different is introduced in order to improve the bit error rate(BER) performance in differential detection of the trellis-coded $\pi/8$ shift 8PSK. The proposed Viterbi decoder is conceptually the same as the sliding multiple detection by using the branch metric with first and Lth order phase difference. We investigate the performance of the uncoded $\pi/4$ shift QPSK and the trellis-coded $\pi/8$ shift 8PSK with or without the Lth phase difference metric in an additive white Gaussian noise (AWGN) using the Monte Carlo simulation. The study shows that the $\pi/4$ shift QPSK with the Trellis-code i.e. the trellis-coded $\pi/8$ shift 8PSK is an attractive scheme for power and bandlimited systems and especially, the Viterbi decoder with first and Lth phase difference metrics improves BER performance. Also, the nest proposed algorithm can be used in the TC $\pi/8$ shift 8PSK as well as TCMDPSK.