• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.10 no.1
• /
• pp.17-30
• /
• 1985

The error rate performances of digital modulation systems in fluenced by impulsive noise have been investigated and discussed in the enviroment of electromagnetic interference(EMI). Using the derived equations for the probabilities of error of L-level ASK, M-ary PSK, MSK, QAM, and APK signals, the error rate performance of each system has been evaluated and compared each other. The results show that, in the case of gaussian noise enviornment, PSK system is superior to the other systems and the digital amplitude modulation systems are inferior on the contrary. In the environment of impulsive noise, the MSK at low interfere level shows the best error rate performance but in the high level interferer environment, the PSK shows the best error rate performance. Also it is known that the digital amplitude modulation systems are scarcely influenced by the variation of interfere level.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.10
• /
• pp.1831-1836
• /
• 2016

Phase noise spectrum distributions of signal generators for next-generation VSAT satellite system based on DVB-RCS2 were analyzed in this paper. The forward link of VSAT system utilizes the APSK higher-order modulation methods based on the DVB-S2 ACM, the modulation methods of the return link utilizes the higher-order PSK and QAM based on the DVB-RCS2. In digital satellite system using the higher-order modulation techniques, the phase noise have an effect on transmission performance, the transmission performance is dominantly degraded by the phase noise of signal generators in the transmission system. The phase noise spectrum distribution of signal generators are analyzed by considering the ACM conditions that adopts the modulation techniques and data rates due to satellite transmission environment. The proper phase noise spectrum distribution for next-generation VSAT system based on DVB-RCS2 are proposed from the analyzed phase noise spectrum characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.9
• /
• pp.2131-2139
• /
• 2014

In this paper, a binary-coded physical-layer network coding (PNC) is considered when high-order modulation techniques are used at source nodes in wireless communication environments. In the conventional PNC schemes, tight power control and phase compensation are required at a relay node. However, they may not be feasible in practical wireless communication environments. Thus, we do not assume the pre-equalization in this paper, and we only utilize the channel state information at receiver (CSIR). We propose a signal detection method for the binary-coded PNC with high-order modulation, such as QPSK and 16QAM, at the source nodes, while the conventional scheme only consider the BPSK at source nodes. We also analyze the bit-error performance of the proposed technique in both uncoded and coded cases.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2003.05b
• /
• pp.1337-1340
• /
• 2003

차세대 이동통신에서는 multi-media 서비스를 제공해야 하는데, 이는 다양한 종류의 고품질 데이터를 전송해야 함을 의미한다. 이를 위한 여러 방식들 중 OFDM 전송 방식은 고속 전송 뿐 만 아니라 ISI(Inter-symbol interference)에도 강한 특성을 가지기 때문에 4 세대 광대역 이동통신을 위한 변조방식중의 하나로 주목 받고 있다. 본 논문에서는 이런 OFDM 의 특징에 single modulation(OFDM 과 QPSK, OFDM 과 16QA), rnulti-modulation(OFDM과(QPSK+16QAM))을 결합하여 시뮬레이션을 통해 성능을 비교하였으며, 전송하고자 하는 데이터 종류와 채널환경에 따른 multi-modulation 방식을 제안 분석하였다.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.2089-2094
• /
• 2010

The importance of broadband wireless communication implemented at subway tunnels is growing up. At 18GHz wireless video transmission system, the transmitter requires a digital modulation method. At subway tunnel, A 18GHz's influence of the multi-pass padding is strong. OFDM digital modulation that is strong for multi-pass padding is recommended. In this paper, Suitable to a subway wireless video transmission OFDM receiver is designed. OFDM receiver system has 6dB gaion because uses diversity of space diversity and MRC(Maximum Ratio Combining) diversity. The transmitter system use C&ITechnologies's transmitter board. IF frequency of receiver is 480MHz. OFDM modulation parameter is as follow, The bandwidth is 8MHz, The numuber of carrier if 2,000, The modulation methode is QAM16, The guard interval is 1/32.

• Proceedings of the Korea Contents Association Conference
• /
• 2005.11a
• /
• pp.596-600
• /
• 2005

In High-speed Portable Internet system to improve performance of whole system, adaptive modulation and coding technology is used, this technology changes modulation and encoding techniques depending on wireless channel environment. Modulation technology that is used in High-speed Portable Internet system is BPSK, QPSK, 16QAMs and 64QAMs. If terminal is distant from base station transceiver system, BPSK or QPSK technology Is used and 16QAMs or 64QAM technology is used if is near in the base station transceiver system. In this paper, number of sub-channel in each modulation technology minimized total transmitting number of PDU is analyzed for efficient radio resources usage. For this, simulation is conducted and the results are presented at High-speed Portable Internet system environments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.7
• /
• pp.747-749
• /
• 2016

We consider a time-division multiple-access relay channel (MARC), in which two source nodes (SNs) transmit data with different data rate to a destination node (DN) with the help of a relay node (RN) using network coding (NC). However, due to its asymmetric data rate, the RN cannot combine the received bits by XOR NC. In this paper, we compare with the problem of asymmetric data rates by using zero padding and hierarchical 16QAM.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.6C
• /
• pp.562-571
• /
• 2010

Forward error correction (FEC) coding schemes using iterative soft decision detection (SDD) information are mandatory in most of the next generation wireless communication system, in order to combat inevitable channel imparirnents. At the same time, space-time block coding (STBC) schemes are used for the diversity gain. Therefore, SDD information has to be fed into FEC decoder. In this paper, we propose efficient SDD methods for turbo-coded STBC system using high order modulation such as QAM. We present simulation results of various SDD schemes for turbo-coded STBC systems, and show that the proposed methods can provide almost approximating performance to maximum likelihood detection with much less computational load.

• Journal of Broadcast Engineering
• /
• v.23 no.2
• /
• pp.293-301
• /
• 2018

In ISDB-T, which is Japanese digital terrestrial TV specification based on OFDM technology, 6MHz bandwidth is divided into 13 segments. Twelve segments (full-seg) are used for high definition broadcasting for fixed receivers and one segment (one-seg) for mobile receivers. Though one-seg supports high speed mobility by using QPSK modulation, it is not suitable for large display mobile devices because of its low data rate. Full-seg using 64QAM modulation also suffers from its low mobile performance. In this paper, mobile performance of ISDB-T full-seg receiver is evaluated by applying sub-carrier interference removing scheme, high speed mobile channel estimation scheme and antenna diversity scheme.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.7 no.4
• /
• pp.76-85
• /
• 2008

In this paper, a 800 MHz 1 W cartesian feedback linearized power amplifier is designed and fabricated for TETRA handset application. For amplification of TETRA signal with 200 kHz narrow bandwidth, amplifier linearization performance of more than 30 dBc is improved through the cartesian feedback linearizer at the offset Sequency of ${\pm}25$ kHz. It is clear that the linearization performance is affected by imbalance of gain and phase between I/Q signals and also DC offset. The linearization performance can be maximized by the compensation of those influences. Cartesian feedback is suitable for a liearization technique of narrow band signal with QAM and another modulation signals, as well.