• Title/Summary/Keyword: Quadrature Amplitude Modulation

Search Result 161, Processing Time 0.026 seconds

A New Design of Signal Constellation of the Spiral Quadrature Amplitude Modulation (나선 직교진폭변조 신호성상도의 새로운 설계)

  • Li, Shuang;Kang, Seog Geun
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.24 no.3
    • /
    • pp.398-404
    • /
    • 2020
  • In this paper, we propose a new design method of signal constellation of the spiral quadrature amplitude modulation (QAM) exploiting a modified gradient descent search algorithm and its binary mapping rule. Unlike the conventional method, the new method, which uses and the constellation optimization algorithm and the maximum number of iterations as a parameter for the iterative design, is more robust to phase noise. And the proposed binary mapping rule significantly reduces the average Hamming distance of the spiral constellation. As a result, the proposed spiral QAM constellation has much improved error performance compared to the conventional ones even in a very severe phase noise environment. It is, therefore, considered that the proposed QAM may be a useful modulation format for coherent optical communication systems and orthogonal frequency division multiplexing (OFDM) systems.

BER Performance Analysis of Linear Orthogonal Space-Time Block Codes with Quadrature Amplitude Modulation in Quasi Static Rayleigh Fading Channel (QAM 변조방식을 갖는 선형 직교 시공간 블록 부호의 준정지 레일리 페이딩 채널에서의 비트 오율 성능 분석)

  • Kim Sang-Hyo;Yang Jae-Dong;No Jong-Seon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.31 no.6C
    • /
    • pp.575-581
    • /
    • 2006
  • In this paper, we first define one-dimensional component symbol error function (ODSEF) from the exact expression of the pairwise error probability of orthogonal space-time block codes (OSTBC). Using the ODSEF and the general bit error probability (BEP) expression for quadrature amplitude modulation (QAM) introduced by Cho and Yoon, the exact closed form expressions for the BEP of linear OSTBCs with QAM in slow-varying Rayleigh fading channel are derived.

A Study on QAM Transmission Schemes for Constant Amplitude Coded Multicode Biorthogonal Modulation (정진폭 부호화된 다중부호 이진직교 변조의 QAM 전송방식에 대한 연구)

  • Hong, Dae-Ki;Kim, Sun-Hee;Kim, Young-Sung;Lim, Seung-Ok;Cho, Jin-Woong;Kang, Sung-Jin
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.12 no.2
    • /
    • pp.343-351
    • /
    • 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.

Improving the performance of turbo code by optimizing QAM constellation points (QAM 변조방식의 성상도 최적화를 통한 터보 부호의 성능 개선 연구)

  • Lee, Keun-Hyung;Kang, Dong-Hoon;Lee, Ji-Yeon;Oh, Wang-Rok
    • Proceedings of the IEEK Conference
    • /
    • 2009.05a
    • /
    • pp.9-11
    • /
    • 2009
  • It is well-known that the performance of turbo codes can be improved by allocating different energies per code symbol. In this paper, based on this observation, we propose a joint encoding and modulation scheme for quadrature amplitude modulated turbo code systems. In the proposed scheme, the amount of energy difference between the turbo coded symbols is optimized by optimizing the constellation of quadrature amplitude modulation(QAM). The proposed scheme offers better coding gain compared to the conventional combination of binary turbo code and QAM at the bit error rate of $10^{-5}$.

  • PDF

Linear Diversity Analysis for M-ary Square Quadrature Amplitude Modulation over Nakagami Fading Channels

  • Yoon, Dong-Weon;Chang, Dae-Ig;Kim, Nae-Soo;Woo, Hoon-Shik
    • ETRI Journal
    • /
    • v.25 no.4
    • /
    • pp.231-237
    • /
    • 2003
  • We derive and analyze the exact closed-form expression for the average bit error probability (BEP) of M-ary square quadrature amplitude modulation (QAM) for diversity reception in frequency-nonselective Nakagami fading. A maximal ratio combining (MRC) diversity technique with independent or correlated fading cases are considered. Numerical results demonstrate error performance improvement with the use of MRC diversity reception. The presented new expressions offer a convenient way to evaluate the performance of M-ary square QAM with an MRC diversity combiner for various cases of practical interest.

  • PDF

Cross-Correlated Quadrature Amplitude Modulation for Non-Orthogonal Multiple Access in 5G Systems

  • Chung, Kyuhyuk
    • International Journal of Advanced Culture Technology
    • /
    • v.9 no.3
    • /
    • pp.283-290
    • /
    • 2021
  • Recently, correlated superposition coding (CSC) has been proposed to implement non-orthogonal multiple access (NOMA) without successive interference cancellation (SIC), without loss of spectral efficiency, in contrast to conventional independent superposition coding (ISC). However, correlation between signals has reduced the average total allocated power, which results in degraded performance. Thus, in order to avoid the reduction of the average total allocated power owing to correlation between signals, this paper proposes a cross-correlated quadrature amplitude modulation (QAM) NOMA scheme under Rayleigh fading channel surroundings. First, we design the cross-correlated QAM NOMA scheme. Then, simulations demonstrate that for the weaker channel gain's user, the symbol error rate (SER) performance of the proposed cross-correlated QAM NOMA improves largely, whereas for the stronger channel gain's user, the SER performance of the proposed cross-correlated QAM CSM NOMA degrades little, compared to that of the conventional QAM NOMA.

A Study on The Modulation for Transmitting Different Information Simultaneously (독립적인 정보 동시 전송용 변조방식에 관한 연구)

  • Kang, Hee-Hoon;Lee, Won-Seok;Lee, Sung-Paik
    • Journal of the Institute of Electronics Engineers of Korea TE
    • /
    • v.37 no.1
    • /
    • pp.58-62
    • /
    • 2000
  • We Propose modulation scheme using I-Q modulation for transmitting different information simultaneously. For transmitting 1bit of each information, we apply QPSK scheme, for more bits, MAPSK. At the second modulation stage, We mix PN wavefoms with APSK waveforms for spreading bandwith. BER(Bit Error Rate) of each Information of the proposed scheme is analyzed on computer simulation. Finally we show power spectrum before and after spreading bandwidth.

  • PDF

SER Performance Analysis of Optimal 64-ary QAM Signal Constellation (최적 신호점 배치를 갖는 64-ary QAM의 SER 성능 분석)

  • Yin, Jiming;Jang, Yeonsoo;Hong, Heejin;Yoon, Dongweon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2014.10a
    • /
    • pp.715-717
    • /
    • 2014
  • In recent wireless communication systems such as Long Term Evolution-Advanced (LTE-A) system, to transmit large multimedia data, high order modulations including 64-ary quadrature amplitude modulation (QAM) are adopted. However, performance of the modulation depends on the signal constellation in the same modulation order. Therefore, a symbol error rate (SER) expression of optimal performance is necessary for analyzing the SER performance of various signal constellation. The optimal signal constellation based on error bound has been previously described, but an exact SER expression has not been derived. In this paper, we propose an exact SER expression of optimal signal constellation for 64-ary QAM.

  • PDF

Quadrature-detection-error Compensation in a Sinusoidally Modulated Optical Interferometer Using Digital Signal Processing

  • Hwang, Jeong-hwan;Park, Chang-Soo
    • Current Optics and Photonics
    • /
    • v.3 no.3
    • /
    • pp.204-209
    • /
    • 2019
  • In an optical interferometer that uses sinusoidal modulation and quadrature detection, the amplitude and offset of the interference signal vary with time, even without considering system noise. As a result, the circular Lissajous figure becomes elliptical, with wide lines. We propose and experimentally demonstrate a method for compensating quadrature detection error, based on digital signal processing to deal with scaling and fitting. In scaling, fluctuations in the amplitudes of in-phase and quadrature signals are compensated, and the scaled signals are fitted to a Lissajous unit circle. To do so, we scale the average fluctuation, remove the offset, and fit the ellipse to a unit circle. Our measurements of a target moving with uniform velocity show that we reduce quadrature detection error from 5 to 2 nanometers.

Improving The Performance of Turbo Code by Optimizing QAM Constellation (QAM 변조방식의 성상도 최적화를 통한 이진 터보 부호의 성능 개선)

  • Lee, Keun-Hyung;Lee, Ji-Yeon;Kang, Dong-Hoon;Oh, Wang-Rok
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.46 no.7
    • /
    • pp.39-44
    • /
    • 2009
  • It is well-known that the performance of turbo codes can be improved by allocating different energies per code symbol. In this paper, based on this observation, we propose a joint encoding and modulation scheme for quadrature amplitude modulated turbo code systems. In the proposed scheme, the amount of energy difference between the turbo coded symbols is optimized by optimizing the constellation of quadrature amplitude modulation (QAM). The proposed scheme offers better coding gain compared to the conventional combination of binary turbo code and QAM at the bit error rate of 10$^{-5}$. Also, the performance of binary turbo codes with the proposed QAM constellation for various code symbol mapping strategies are verified.