• Title/Summary/Keyword: hierarchical modulation

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Normalization Factor for Three-Level Hierarchical 64QAM Scheme (3-level 계층 64QAM 기법의 정규화 인수)

  • You, Dongho;Kim, Dong Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.1
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    • pp.77-79
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    • 2016
  • In this paper, we consider hierarchical modulation (HM), which has been widely exploited in digital broadcasting systems. In HM, each independent data stream is mapped to the modulation symbol with different transmission power and normalization factors of conventional M-QAM cannot be used. In this paper, we derive the method and formula for exact normalization factor of three-level hierarchical 64QAM.

A Study on the SNR Estimation Performance of Hierarchical 16QAM (계층 16QAM의 SNR 추정 성능에 대한 연구)

  • Kwak, Jae-Min
    • Journal of Advanced Navigation Technology
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    • v.16 no.6
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    • pp.975-981
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    • 2012
  • The SNR estimation performance of hierarchical 16QAM system, which is adopted to simultaneous transmission or efficient image transmission system, is analyzed. Hierarchical 16QAM is modulation system which has different constellation shape from conventional QAM and can provide users with high quality and low quality of data services simultaneously by controlling hierarchical modulation parameter. Assuming AWGN channel, SNR estimation performance characteristics are investigated considering hierarchical modulation parameter and type of constellation points. From simulation results, it is found that constellation point showing superior SNR estimation performance relative to other points is exist. Also, it is known that according to hierarchical modulation parameter, SNR estimation range with more accurate estimation performance is divided.

Transmission Performance Analysis for Terrestrial Digital Broadcast Systems According to Hierarchical Modulation Factor(α) (계층변조 지수(α)에 따른 지상파 디지털 방송 시스템의 전송성능 분석)

  • Lee, Sungyoon;Kim, Jae-Kil;Lee, Jewon;Yun, Seonhui;Ahn, Jae Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37A no.9
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    • pp.728-737
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    • 2012
  • An analytical method for identifying terrestrial broadcasting coverages is proposed for a terrestrial broadcasting transmission system adopting a hierarchical modulation technique. Bit Error Rates(BERs) are derived for hierarchically modulated non-uniform QAM constellations based on the Q-function analysis in AWGN environments. The derived BERs depend on the hierarchical modulation factor ${\alpha}$(HMF) and could be mapped to the broadcasting coverages according to the link budget analysis based on the log-distance path loss model. Finally the broadcasting coverage ratios for high priority(HP) streams and low priority(LP) streams are calculated and presented for the determination of the HMF.

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.

Hierarchical Modulation Scheme for Capacity Enhancement in the Satellite DMB System (위성 DMB에서 채널 용량 향상을 위한 계층변조 방식)

  • Song, Jeong-Ik;Lee, Gyeong-Tak;Son, Seong-Hwan;Kim, Jae-Myeong
    • Journal of Satellite, Information and Communications
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    • v.1 no.2
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    • pp.83-88
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    • 2006
  • Future communication systems are to be designed to support and serve multimedia and multipledata transmission. Nowadays, requirement of mobile subscribers for the various information such as movie, GPS(Global Positioning System) information, news-is increasing significantly. However, due to practical reasons, the capacity and number of capable channels are limited. To solve this problem, a large number of methods and schemes have been proposed and are under research. In this paper, we demonstrate how satellite DMB (Digital Multimedia Broadcasting) system works with hierarchical modulation scheme. By using hierarchical modulation, we can analyze the capacity. Meanwhile, system performance os evaluated and compared to conventional DMB system without using hierarchical modulation.

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Transmit Scheme Study for OFDM Based Fixed Relay System with Hierarchical Modulation (직교주파수다중화변조 기반 계층변조 릴레이 시스템의 전송방식 연구)

  • Xu, Jian;Kang, Woo-Seok;Seo, Jong-Soo
    • Journal of Advanced Navigation Technology
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    • v.12 no.6
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    • pp.598-603
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    • 2008
  • Relay system is a promising technique for the high downlink throughput or coverage extension in the next generation wireless systems. In this paper, the transmit scheme for orthogonal frequency division multiplexing (OFDM) based relay system with hierarchical modulation is designed. Without using much power from the base station, the proposed scheme can guarantee the cell edge users to get high data rates as the inner cell users. In the simulation, the performance of proposed scheme was compared with the conventional one in which there is no hierarchical modulation. Numerical results show that the proposed scheme can save much power whether the unicast case or multicast case.

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Error Performance Analysis of Concatenated Codes in advanced T-DMB System with Hierarchical Modulation (계층 변조를 포함한 개선된 지상파 DMB 시스템에서 연접 부호들의 오류 성능 분석)

  • Lim, Hyung-Taek;Lee, Sang-Hoon;Kim, Jeong-Goo;Joo, Eon-Kyeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.1
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    • pp.10-17
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    • 2007
  • Hierarchical modulation technology which can make the advanced T-DMB(terrestrial-digital multimedia broadcasting) system backward compatible with the conventional T-DMB system and provide high-rate and high-quality services is introduced in this paper. As additional data streams are embedded within the conventional data streams by the hierarchical modulation, the advanced T-DMB system can provide high-quality video service and more broadcasting service channels. In order to guarantee the quality of both the conventional and additional services powerful error correcting scheme is required. The error performance of advanced T-DMB system with hierarchical modulation is investigated and analyzed according to the various error correcting schemes in this paper.

Performance Enhancement using Hierarchical Modulation in Distributed Relaying Systems (분산 릴레이 시스템에서 계층적 변조를 이용한 성능 향상)

  • Choi, Du-Hwan;Kang, Dong-Kwan;Park, Jae-Hyun;Kim, Duk-Kyung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.1A
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    • pp.18-26
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    • 2009
  • Various relay technologies have been considered in wireless communication systems to enlarge the coverage and to enhance the system throughput. However, the coverage is limited by its modulation levels and additional time slot(s) is required for relaying. In the paper, by applying the hierarchical modulation to two-relay systems, two-hop relaying can be implemented instead of three hops, and both throughput and coverage can be enhanced. Throughout simulation analysis, the coverage extension is evaluated for different modulation levels and the total throughput is increased by up to two times.

Adaptive Dual-Hop Transmission Based On Hierarchical Modulation in UWB System (초광대역 시스템의 계층변조 기반 적응적 듀얼 홉 전송 기법)

  • Kim, Dae-Hwan;Song, Hyoung-Kyu;Cho, We-Duke
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.7C
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    • pp.443-450
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    • 2011
  • Recently, various transmission techniques for communication and broadcasting systems have been developed to meet the dramatically increasing requirement of consumers. Because UWB (Ultra-Wideband) is a wireless communication technique that supports high data rate with low power, it can satisfy the requirement and can be applied to various wireless communication services. The multi-band orthogonal frequency division multiplexing (MB-OFDM) system, one of UWB system, is the wireless communication system that satisfies the transmission characteristic for UWB and so it can be used for various wireless communication services. In this paper, we propose a scheme that uses hierarchical modulation which is applied in digital video broadcasting system at the source and adaptive modulation based on the channel quality at the relays. The simulation results have shown that the proposed scheme has both the advantages of the increased throughput by 33% and similar BER performance to conventional scheme.

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.