• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.7C
• /
• pp.624-632
• /
• 2005

We consider an adaptive bit-loading technique for bit interleaved coded modulation-orthogonal frequency division multiplexing(BICM-OFDM) systems. By adjusting transmission parameter of each subcarrier adaptively depending on the subchannel state, the performance of OFDM system can be improved dramatically. In this paper, the number of bits for each subcarrier is allocated to minimize bit error rate keeping the constant throughput for the adaptive transmission technique of BICM-OFDM system which can be applied to real time transmission. Also, We use the discrete Lagrange multiplier method to get the optimum solution under the integer bit allocation constraint. Simulation results show that computational amount of the proposed bit allocation technique is not high and BICM-OfDM system using the proposed technique can get the SNR gain by 2$\~$3 dB over nonadaptive one.

• Journal of Satellite, Information and Communications
• /
• v.5 no.1
• /
• pp.6-16
• /
• 2010

Since OFDM system suffers from high peak-to average power ratio(PAPR) drawbacks, more energy has been converted to seek for a new substitutable system which can maintain OFDM system's inherent virtues while avoid its defects. Consequently, a new multicarrier system called as CI/OFDM system has been proposed which applied carrier interferometry(CI) code to OFDM system. Due to its low PAPR advantage and orthogonal property, it has received more and more attention. Simultaneously, an old technique called single carrier(SC) system has retaken its attractions for the same purposes. This paper analyzes two cyclic prefixed transmission schemes variants of OFDM system: 1.carrier interferometry-Orthogonal Frequency-Division Multiplexing (CI/OFDM); 2. Cyclic prefixed single carrie(CP-SC) with frequency domain equalization. We compare the achievable bit rate transmission of the two systems in terms of signal to noise ratio(SNR) by mathematical derivation. We demonstrated that CI/OFDM achieves a bit higher transmission bit rate to that of the CP-SC with frequency domain equalizer.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.5
• /
• pp.462-466
• /
• 2007

This paper proposes an automatic bandwidth control method for the performance improvement of Binary Amplitude Shift Keying (BASK) system for Giga-Bit Modem in millimeter band. In order to improve the performance of the BASK system with a fixed bandwidth, the proposed method is to adjust a bandwidth of low pass filter in receiver using the fuzzy system. The BASK system consists of a high speed shutter of the transmitter and a counter and a repeater of receiver. The repeater consists of four stage converters, and a converter is constructed with a low pass filter and a limiter. The inputs to the fuzzy system are the reminder and integral of remainder of counter, and output is a bandwidth. We used a Viterbi algorithm to find the optimum detection from the output of the counter. Simulation results showed that the proposed system improves the performance compared to the fixed bandwidth.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.6
• /
• pp.33-36
• /
• 1983

This paper briefly describes the hardware side of "Development of a 16 bit computer system, " one of the national projects in which Samsung Semiconductor Telecommunication Inc. '||'&'||' KIET combined their efforts to develop a 16 bit microcomputer system based on IEEE 796 hardware bus structure. In the project CPU, memory and I/O controller boards were developed, tested and integrated into a complete system.m.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.8 no.2
• /
• pp.76-81
• /
• 1983

PCM-NRZ/FM Telemetry system is constructed on the basis of RF link with FM modulatedand NRZ-L binary coded PCM data are assumed to transmit through 5th-order Bessel filter. Upon demodulated by the limiter-discriminator at the receiver, the probability of bit error, which is important for performance estimation of digital system, is analyzed against SNR. The analysis based on the following parameters, that is bit rate 140kHz, frequency of pre-modulation filter f-100kHz, maximum frequency deviation of transmitter 2f=300kHz, was performed. As a result, when the telemetry system with the parameters above is designed, the probability of bit error is obtained as 10 along with fT=0.7 and h=2, T=2.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.194-197
• /
• 2003

We proposed Binary ASK system for 1Giga bit Modem. The Binary ASK system has a high speed shutter transmitter and no IF receiver only by symbol synchronization. The advantage of proposed system is that circuitry is very simple without IF process. The disadvantage of proposed system are that line spectrum occurs unordinary interference to other channels, and enhancement to 4-level system is impossible due to its large SNR degradation.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2007.02a
• /
• pp.35-39
• /
• 2007

We applied digital image processing about BitMap file structure in this research and studied about digital communication system. digital record saving devices can express 'High' and 'Low' as all data. Only, digital technique that two expression methods is used into several expenditures. People and communication that are far away by development of digital technology, became smooth. We wished to make communication system taking advantage of digi-tech. This system was made for communication with disabled and normal person specially. To communication method that we are studied such BitMap file handling image communication system. The goal of this contribution is to present the overview of basic algorithms for image processing using BitMap.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.2 no.3
• /
• pp.129-137
• /
• 2007

MPEG-4 FGS is one of scalable video coding schemes specified In ISO/IEC 14496-2 Amendment 2, and particularly standardized as a scheme for providing fine granular quality and temporal scalabilities. In this paper, we propose a sign-bit reduction technique in embedded bit-plane coding to enhance the coding efficiency of MPEG-4 FGS system. The general structure of the FGS system for the proposed scheme is based on the standard MPEG-4 FGS system. The proposed FGS enhancement-layer encoder takes as input the difference between the original DCT coefficient and the decision level of the quantizer instead of the difference between the original DCT coefficient and its reconstruction level. By this approach, the sign information of the enhancement-layer DCT coefficients can be the same as that of the base-layer ones at the same frequency index in DCT domain. Thus, overhead bits required for coding a lot of sign information of the enhancement-layer DCT coefficients in embedded bit-plane coding can be removed from the generated bitstream. It is shown by simulations that the proposed FGS coding system provides better coding performance, compared to the MPEG-4 FGS system in terms of compression efficiency.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1993.06a
• /
• pp.1313-1316
• /
• 1993

This paper presents a fuzzy system that estimates the optimal bit allocation matrices for the spatially active subimage classes of adaptive transform image coding in noisy channels. Transform image coding is good for image data compression but it requires a transmission error protection scheme to maintain the performance since the channel noise degrades its performance. The fuzzy system provides a simple way of estimating the bit allocation matrices from the optimal bit map computed by the method of minimizing the mean square error between the transform coefficients of the original and the reconstructed images.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.35-38
• /
• 2004

In this paper, we aim to implement the embedded VoIP Phone based on EISC core Microcontroller. EISC is recently new microprocessor architecture, which contains both advantage of RISC and CISC. This advantages are desirably resulted in high code density, high performance and 16/32/64bit scalable instruction length. Also, we select the embedded system which can be guaranteed performance and economical efficiency for implementation that system. As the step of this research, we first study basic system for implementation of target system. Next, we construct the structure of embedded VoIP Phone based on 32bit EISC MCU efficiently. And then we realize that constructed system and verify the performance of that realized system by the test of voice communication in field.