• Title/Summary/Keyword: Quadrature Amplitude Modulation

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Phase Noise Influence on SER of MQAM, DPSK, OFDM-MQAM, OFDM-DPSK (MQAM, DPSK, OFDM-MQAM과 OFDM-DPSK의 위상 잡음 영향 연구)

  • Kwon, Joh-Ann;Kim, Ihn-Seok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.2 s.117
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    • pp.219-226
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    • 2007
  • In this paper, we report phase noise effects on SER(Symbol Error Rate) of MQAM(M-ary Quadrature Amplitude Modulation), DPSK(Differential Phase Shift Keying), OFDM(Orthogonal frequency Division Multiplex)-MQAM and OFDM-DPSK. SER of each modulation method has been quantified at the various offset frequencies of the local oscillator and compared with phase noise effects with the ideal cases, which have no phase noise, through the MATLAB simulation. And the ratio of modulation bandwidths to the SERs at the various frequency offsets for the above modulation methods have been analyzed for the system requirement of minimum phase noise characteristics.

Priority-based Unequal Error Protection Scheme of Data partitioned H.264 video with Hierarchical QAM

  • Chen, Rui;Wu, Minghu;Yang, Jie;Rui, Xiongli
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.11
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    • pp.4189-4202
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    • 2014
  • In this paper, we propose a priority-based unequal error protection scheme of data partitioned H.264/AVC video with hierarchical quadrature amplitude modulation. In order to map data with higher priority onto the most significant bits of QAM constellation points, a priority sorting method categorizes different data partitions according to the unequal importance factor of encoded video data in one group of pictures by evaluated the average distortion. Then we propose a hierarchical quadrature amplitude modulation arrangement with adaptive constellation distances, which takes into account the unequal importance of encoded video data and the channel status. Simulation results show that the proposed scheme improves the received video quality by about 2 dB in PSNR comparing with the state-of-the-art unequal error protection scheme, and outperforms EEP scheme by up to 5 dB when the average channel SNR is low.

Exact BER Expressions for Decode-and-Forward Relaying in Rayleigh Fading Channels (레일레이 페이딩 채널에서 디코팅 후 전달 중계방식에 대한 비트 오차율 분석)

  • Lee, In-Ho;Kim, Dong-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.12A
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    • pp.1244-1250
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    • 2007
  • User cooperation provides high reliability in wireless communication systems by employing relay nodes to transmit the same information. In this paper, a bit error rate (BER) study is presented for decode-and-forward (DF) relaying for user cooperation in independent and identically distributed Rayleigh fading channels. For an arbitrary number of relays, exact and closed-form expressions of the BER are proposed for M-ary PAM (Pulse Amplitude Modulation), QAM (Quadrature Amplitude Modulation) and PSK (Phase Shift Keying), respectively. It is also shown that the analytic results are perfectly matched with the simulated ones.

Priority Based Blind Equalization for Hierarchical Modulation Systems (계층변조 시스템에서 신호의 우선순위를 이용한 블라인드 등화)

  • Choi, Un-Rak;Seo, Bo-Seok
    • The Journal of the Korea Contents Association
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    • v.7 no.12
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    • pp.254-261
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    • 2007
  • In this paper, we propose a blind equalization method for advanced terrestrial digital multimedia broadcasting (AT-DMB) systems which use hierarchical modulation. The AT-DMB system adopts hierarchical 16-ary quadrature amplitude modulation (16-QAM) to ensure backward-compatibly with the differential quadrature phase shift keying (DQPSK) signal of the legacy terrestrial digital multimedia broadcasting (T-DMB) systems and to support higher transmission rate. Due to the hierarchical modulation, the conventional T-DMB signal and the additional signal have different error rate at same signal to noise ratio (SNR). By weighting the decided symbols differently according to the reliability of the symbols, i.e., high priority symbol with low error rate and low priority symbol with high error rate, we can improve the channel estimation accuracy. In this paper, we analyze SNR loss by hierarchical modulation and confirm it through simulations. Moreover, through simulations, we verify that the proposed weighting method improve BER compared to the no-weighting method.

Cyclic Prefix Reconstruction and Equalization for EST based Modulation (EST기반 변조에서 Cyclic Prefix 복원 및 등화기법)

  • Kwun, Soon-Ik;Kwon, Byung-Uk;Hwang, Tea-Won
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.9A
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    • pp.835-843
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    • 2010
  • Energy spreading transform (EST) based equalization is a very effective technique to remove inter symbol interference (ISI) in frequency selective channel. EST based system uses cyclic prefix (CP) similar to orthogonal frequency division multiplexing (OFDM) system. Since CP is a redundancy, it degrades the data transmission rate. RISIC is an algorithm that removes an inter block interference (IBI) caused by insufficient CP length and reconstructs CP. In this paper, we propose a system that combines the existing EST system with quadrature phase shift keying (QPSK) modulation and RISIC algorithm to enhance the efficiency of the transmission. Also we extend the proposed system to 16 quadrature amplitude modulation (QAM) modulation. The proposed system is shown to performance close to matched filter bound (MFB) even with insufficient CP.

Effects on Phase Noise of QSPK, MQAM, OFDM-QPSK, OFDM-MQAM, and 8-VSB Modulations (QPSK, MQAM, OFDM-QPSK, OFDM-MQAM 및 8-VSB 변조방식에 대한 위상잡음의 영향)

  • Kwon, Joh-Ann;Kim, Ihn-Seok
    • Journal of Advanced Navigation Technology
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    • v.10 no.3
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    • pp.235-249
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    • 2006
  • In this paper, SER(Symbol Error Rate) variation and effects on SER by phase noise at various frequency offset of the local oscillator in digital communication systems are gerneralyzed for QPSK(Quadrature Phase Shift Keying), MQAM(M-ary Quadrature Amplitude Modulation), OFDM(Orthogonal Frequency Division Multiplex)-MQAM, OFDM-QPSK and 8-VSB(Vestigal Side Bands) modulation methods and compared those with the ideal cases, which have no phase noise, through the MATLAB simulation. And the ration between modulation bandwidths and the SER on the various frequency offsets on the above modulation methods have been analyzed for the system requirement of minimum phase noise characteristics. From this study, we have confirmed that the most sensitive modulation method on the phase noise is OFDM-MQAM and that the relatively insensitive method 8-VSB.

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Quadrature Correlated Superposition Modulation: Practical Perspective of Correlated Superposition Coding

  • Chung, Kyuhyuk
    • International Journal of Internet, Broadcasting and Communication
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    • v.13 no.3
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    • pp.17-24
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    • 2021
  • Recently, a lossless non-orthogonal multiple access (NOMA) implementation without successive interference cancellation (SIC) has been proposed in the literature of NOMA. This lossless non-SIC NOMA was achieved via correlated superposition coding (CSC), in contrast to conventional independent superposition coding (ISC). However, only the achievable data rates for CSC NOMA were investigated. Thus, this paper proposes a practical CSC NOMA scheme under Rayleigh fading channel environments. First, we design the practical CSC NOMA scheme, namely quadrature correlated superposition modulation (CSM) NOMA, without channel coding, i.e., uncoded systems. In addition, we calculate the symbol error rates (SERs) for this quadrature CSM NOMA scheme. Then, simulations demonstrate that for the weak channel gain's user, the SER performance of the proposed quadrature CSM NOMA is shown to be improved greatly, compared to that of the conventional quadrature amplitude modulation (QAM) NOMA, whereas for the strong channel gain's user, the SER performance of the proposed quadrature CSM NOMA degrades a little, compared to that of the conventional QAM NOMA. As a result, the proposed quadrature CSM NOMA scheme could be considered as a practical NOMA scheme for CSC NOMA schemes toward the fifth-generation (5G) and next generation communications.

Performance and Operating Characteristics Analysis of the 16-APSK Modulation over Nonlinear Channels (16-APSK 변조 방식의 성능 및 비선형 채널에서의 동작 특성 분석)

  • Kang, Seok-Heon;Kim, Sang-Tae;Sung, Won-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.4C
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    • pp.362-369
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    • 2007
  • APSK (Amplitude Phase Shift Keying) digital modulation is characterized by the circular positioning of the transmission symbols in the constellation diagram. Due to such structural characteristics, the peak-to-average power ratio of the APSK modulation is lower than that of the QAM (Quadrature Amplitude Modulation), and the amount of performance degradation over nonlinear channels can be mitigated. The APSK modulation scheme has recently been adopted as satellite communication system standards including the DVB-S2 (Digital Video Broadcasting - Satellite, Version 2). In this paper, a BER (Bit Error Rate) upper bound approximation formula is derived using the channel model with the output power saturation characteristics, and its accuracy is demonstrated. Using the derived formula, the input power level that minimizes the BER is determined. The optimized performance based on the radii ratio of the 16APSK constellation and the channel saturation level is also presented.

Performance Analysis of Adaptive System Using MPSK and MQAM for Rayleigh Fading Channel (레일리 페이딩 채널에서 MPSK와 MQAM을 이용한 적응적 시스템의 성능 분석)

  • 문재경;김재원;최송인;하영호;김수중
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6A
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    • pp.782-790
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    • 1999
  • In this paper, we propose an adaptive trellis-coded Multiple Quadrature Amplitude Modulation(ATCMQAM) applying MQAM as the modulation scheme in the conventional ATCMPSK (Adaptive trellis-Coded Multiple Phase Shift Keying) for slowly varying Rayleigh fading channels. The proposed system adaptively controls the coding rate combined with modulation level of pragmatic approach to trellis-coded modulation according to the instantaneous fading channel conditions, and employs MQAM as modulation scheme.Results by computer simulation show that the proposed adaptive model using MQAM can realize higher quality transmission with the improvement more than 0.5 ~ 1bit in average bit rate. And there is a coding gain of 2-5dB, depending on the high SNR value, compared with the conventional adaptive model employing MPSK.

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CACB-Q2PSK Modulation for Efficient Bandwidth Utilization and Constant Amplitude Signal Transmission (효율적인 대역폭 이용과 정진폭 신호 전송을 위한 CACB-Q2PSK 변조)

  • Hong, Dae-Ki
    • 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.