• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.211-214
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• 2008

본 논문에서는 다중부호 신호(multi-code signal)를 정진폭으로 전송하는 정진폭 다중 부호 트랜스 이진직교 변조방식에서 사용될 수 있는 오류 제어 부호를 제안한다. 격자부호를 사용하여 시스템의 비트오율 성능을 높이는 방식이 정진폭 다중 부호 트랜스 이진직교 변조 방식에 적합함을 보인다. 정진폭다중 부호 트랜스 이진직교 변조방식에서는 정진폭을 유지하기 위해 세로축의 패리티 비트를 사용하여 신호를 부호화 하게 된다. 제안된 시스템에서는 정진폭을 유지하기 위해 사용되는 세로축의 패리티비트외에 추가적으로 부호화를 수행하여 가로축의 패리티 비트를 부가하되 격자구조가 되도록 하여 비트오율 성능의 개선을 최대화 한다. 제안된 시스템은 시스템 복잡도의 증가가 거의 없으며 복호기도 매우 간단하게 구현될 수 있다. 실험결과에 의하면 제안된 시스템은 격자구조를 사용하지 않은 시스템에 비해 성능의 개선이 있음을 알 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.522-527
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• 2007

In this paper, we propose an error control coding scheme for constant-amplitude multicode-biorthogonal modulation. The product code is appropriate to the constant-amplitude multicode-biorthogonal modulation for the bit error rate performance improvement. In the constant-amplitude multicode-biorthogonal modulation, the vertical redundant bits are used for the constant amplitude coding. The proposed product code can be constructed by using the additional horizontal redundant bits. The hardware complexity of the encoder/decoder pair is very low. The simulation results show that the bit error rate performance of the proposed coding scheme is improve

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.93-99
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• 2008

In this paper, we propose new modulation schemes using the conventional CACB modulation with constant amplitude property. Also the proposed modulation schemes supports high transmission data rate by increasing the spectral efficiency. In order to obtain the high spectral efficiency, the $Q^2$PSK and CA-$Q^2$PSK are used. We explain the simplest combining modulation scheme of CACB and $Q^2$PSK (i.e., CACB-$Q^2$PSK). However, this modulation scheme cannot support the constant amplitude property. Hence the first CACB-CA-$Q^2$PSK (or CACB-CA-$Q^2$PSK I) modulation scheme is proposed for the constant amplitude property. In the modulation scheme, the redundant constant amplitude encoding (spectral efficiency decrease) is required. Therefore, the second CACB-CA-$Q^2$PSK (or CACB-CA-$Q^2$PSK II) modulation scheme is proposed retaining the constant amplitude and the spectral efficiency. Computer simulations show that the proposed CACB-CA-$Q^2$PSK II is the efficient modulation scheme.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.21-32
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• 2008

In this paper, we propose new modulation schemes using the conventional CACB (Constant Amplitude Coded Multicode Biorthogonal) modulation with constant amplitude property. Also the proposed modulation schemes supports high transmission data rate by increasing the spectral efficiency, In order to obtain the high spectral efficiency, the $Q^2$AM (Quadrature-Quadrature Amplitude Modulation) and CA-$Q^2$AM (Constant Amplitude-$Q^2$AM) are used. We explain the simplest combining modulation scheme of CACB and $Q^2$AM (i.e., CACB-$Q^2$AM). However, this modulation scheme cannot support the constant amplitude property. Hence the first CACB-CA-$Q^2$AM (or CACB-CA-$Q^2$AM I) modulation scheme is proposed for the constant amplitude property. In the modulation scheme, the redundant constant amplitude encoding (spectral efficiency decrease) is required. Therefore, the second CACB-CA-$Q^2$AM (or CACB-CA-$Q^2$AM II) modulation scheme is proposed retaining the constant amplitude and the spectral efficiency. Computer simulations show that the proposed CACB-CA-$Q^2$AM II is the efficient modulation scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.493-499
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• 2011

To improve the bandwidth efficiency of conventional orthogonal modulation, the MCTO(Multi-Code Trans-Orthogonal) modulation, which is modified orthogonal modulation, was proposed. However, the RF(Radio Frequency) power amplifier for the MCTO modulation is too complex to reject the amplitude distortion due to the non-constant amplitude property of the MCTO. Therefore, in this paper, CAMCTO(constant-amplitude multi-code trans-orthogonal) modulation is proposed by using the constant-amplitude encoding algorithm for multi-code signal. Additionally, the performance of the proposed CAMCTO modulation is compared with those of the orthogonal modulation and the MCTO modulation by using the computer simulation. The computer simulations show that the bandwidth efficiency of the proposed CAMCTO modulation is better than that of the conventional orthogonal modulation.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1990.10a
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• pp.47-51
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• 1990

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.343-351
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• 2008

In this paper, we investigate the design of the QAM(Quadrature Amplitude Modulation) method for the CACB(Constant Amplitude Coded Multicode Biorthogonal) scheme. The modulation method fan improve the transmission data rate by increasing the BE(Bandwidth Efficiency). Additionally, we can improve the system performance by using the QAM SD(Soft Decision) method with the MDSA(Minimum Distance Selection Algorithm). Finally, the DFE(Decision Feedback Equalizer) for the CACB-QAM is simulated under the MPF(MultiPath Fading) channel for real implementation. The proposed scheme can be used for the PHY(PHYsical layer) standard of the WPAN(Wireless Personal Area Network) requiring high rate data transmission.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.505-505
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• 2006

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.7
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• pp.12-22
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• 2012

The main drawback of the multi-code spread spectrum communication system, which spreads data bits stream by the multiplexed orthogonal codes, is the need for the highly linear amplifier. Several constant amplitude precoding schemes have been proposed for the Walsh code or the extended $m$-sequence based multi-code spread spectrum systems. In the constant amplitude spread spectrum systems the accompany code is transmitted together with orthogonal codes to maintain the transmitter output in a constant level. In this paper we propose the use of the accompany in the receiver to improve the BER performance. The proposed receiver has the capability to correct the code detection error(up to one code error). We carried out simulations to verify the validity of the proposed algorithm. BER performance improvement was noticed compared with the conventional receiver.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.8
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• pp.1-11
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• 2012

The multi-code spread spectrum communication system, which spreads data bit stream by multiplexing orthogonal codes, can transmit data in high rate. However it needs the high-cost good linear amplifier because of the multi-level output signal. In order to overcome this drawback several systems making the amplitude of output signal constant with Walsh codes have been proposed. Recently constant amplitude pre-coded multi-code spread spectrum systems using extended m-sequence have been proposed. In this paper we consider an extended m-sequence based constant amplitude multi-code spread spectrum system with code set partitioning. By grouping the orthogonal codes into 4 subsets, not only is the computational complexity of the transceiver reduced but BER performance also improves. It has been shown that parity checking on four detected codes at the receiver can correct code detection error and result in BER performance enhancement. In this paper we propose a improved parity check receiver. We carried out computer simulation to verify feasibility of the proposed algorithm.