• Title/Summary/Keyword: M-ary transmission

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Symbol Error Rate Analysis for Fixed Multi-User Superposition Transmission in Rayleigh Fading Channels (레일레이 페이딩 채널에서 고정적 다중사용자 중첩 전송에 대한 심벌 오차율 성능 분석)

  • Lee, In-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.10
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    • pp.1379-1385
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    • 2018
  • In the conventional multi-user superposition transmission, the power allocation coefficients of data symbols and the received signal processing of users are determined by the condition of instantaneous channel powers. However, the use of instantaneous channel powers can increase the system complexity. Hence, we consider fixed multi-user superposition transmission using average channel powers. The fixed multi-user superposition transmission can reduce the system complexity because it uses the condition of average channel powers that slowly change over time in order to decide the power allocation coefficients and the received signal processing. In this paper, we analyze the average symbol error rate for the fixed multi-user superposition transmission. In particular, an expression for the average symbol error rate of M-ary Quadrature Amplitude Modulation is derived assuming Rayleigh fading channels. In addition, through the numerical results, we show that the conventional and fixed multi-user superposition transmissions achieve the similar average symbol error rate performances at the user in the severe channel condition.

Performance of OFDM M-ary QAM System in the presence of Carrier Frequency Offset (반송파 주파수 옵셋에 따른 OFDM M-ary QAM 시스템의 성능 분석)

  • 계선형;유형석;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1024-1031
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    • 1999
  • In order to transmit high-speed wide band signals efficiently in multipath fading environments, M-ary QAM signalling combined with OFDM transmission technique is applied. In this paper, the effect of synchronization error caused by carrier frequency offset and SER(Symbol Error Rate) performance of OFDM-16QAM and OFDM-64QAM are theoretically analyzed. Our result shows that as the number of sub-carrier in OFDM system increases the frequency-offset caused inter-channel interference(ICI) increases significantly, and that an error floor occurs even at high SNR of OFDM system. For OFDM-64QAM, the error floor occurs at SER=1$\times$10-7 when a normalized frequency-offset is 0.001, in which the SNR degradation is much greater than that of OFDM-16QAM. From this study the maximum allowable frequency-offset of OFDM-16QAM and OFDM-64QAM systems can be determined to meet the specific SER requirement.

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A Study on the Transmission Performance for Multimedia Communication (멀티미디어 통신을 위한 OFDM의 전송 성능에 관한 연구)

  • 김남성;강희조;이권현
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.449-453
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    • 2004
  • 본 연구에서는 고속 광대역의 정보신호를 다중경로 페이딩 환경에서 효율적으로 전송하기 위한 M-ary QAM신호와 OFDM전송방식을 사용할 때 반송파의 주파수 옵셋이 발생하는 동기오차가 수신시스템에 미치는 영향으로 인한 수신 성능을 분석하였다.

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Performance Analysis of M-ary Multiple Access UWB System Using Modified Hermite Polynomial Pulses (Modified Hermite Polynomial 펄스들을 사용하는 M진 다중접속 UWB 시스템의 성능 분석)

  • Hwang, Jun-Hyeok;Kim, Suk-Chan;Park, Dong-Chan;Kim, Byoung-Chul
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.9A
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    • pp.909-916
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    • 2008
  • In this paper, we propose and analyze M-ary pulse order time hopping multiple access ultra wideband (PO-THMA UWB) system using modified Hermite polynomial (MHP). The MHP pulses have a mutually orthogonal property between different ordered pulses and that property makes simultaneous transmission at the same time slot regardless of collision in the THMA-UWB system. Therefore, we derive the cross-correlation furlction of MHP pulses and analyze the BER of the proposed system and show that the BER performance and the transmission capacity are improved dramatically when compared with those of conventional THMA-UWB system.

Performance Analysis of the M-PPAM DS-UWB Communication systems (M-PPAM DS-UWB 통신시스템의 성능해석)

  • Cho, Kyung-Ryong;Park, Jang-Woo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.8
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    • pp.1656-1662
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    • 2005
  • This paper introduces M-PPAM(M-ary Pulse Position and Amplitude Modulation) architecture, combined PPM(Pulse Position Modulation) with PAM(Pulse Amplitude Modulation). Since M-PPAM can transmit several bits using one pulse, it is mon effective than PPM or PAM. Also, to obtain the same data transmission rate with PPM or PAM, M-PPAM can use a long pulse repetition period. This method will be able to use in the multi-path fading environment such as indoor condition. To accomodate multiple users, direct sequence technique is used. This paper has provided the modeling method of the M-PPAM DS-UWB receiver covering multi-user interference(MUI) with the Standard Gaussian Approximation under Gaussian channel. The performance of the receiver is simulated.

Performance Analysis of UMM-S/OFDM with Multi-level Modulation in the Rayleigh Fading Channel (Rayleigh 페이딩 환경에서 다중레벨 변조방식을 고려한UMM-S/OFDM의 성능분석)

  • Kim, Nam-Soo;Cho, Sung-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.1A
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    • pp.51-56
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    • 2007
  • Unitary matrix modulation (UMM) is investigated in multiple antennas system that is called unitary space-time modulation (USTM). When we consider only diagonal components of UMM with splitting over the coherence bandwidth, the system can obtain frequency diversity in a single antenna system. In Rayleigh fading channel, we compared USTM/OFDM with 2Tx-antenna with UMM-S/OFDM with 1Tx-antenna, conventional multi-level OFDM and UMM-S/OFDM with changing bit rate per Hz. Also, we analyzed SNR for between multi-level modulation STBC/OFDM and multi-level modulation UMM-S/OFDM with changing transmission rate. When it was adaptive multi-level modulation to improve SNR, we did the UMM-S/OFDM system performance analysis of N-ary PSK and M-ary QAM.

New M-ary Differential-Frequency Shift Keying Modulation Enhancing Acoustic Modem's Synchronization For Ubiquitous Communication (Ubiquitous 통신을 위한 Acoustic 모뎀의 동기부 성능을 개선하는 새로운 M진 상태천이 주파수 쉬프트 키잉 변조 기법)

  • Kim, En-Ki;Kim, Young-Ju;Lee, In-Sung
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.1 s.343
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    • pp.25-32
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    • 2006
  • We propose a new M-ary state-transition FSK modulator technique for enhancing demodulator's symbol timing recovery which can be applied to acoustic MODEM. In the previous technique, the demodulator's symbol timing performance can degrade when the sequences of same symbols are transmitted. This proposed method, because the transmission symbol changes in every single symbol period, increases the synchronization performance dramatically and has a simple MODEM and frame structure. On the one hand, we improve modulation-derived synchronization(MDS) which is M-ary FSK's symbol timing recovery scheme, then analyze it. Finally the proposed method is analyzed from the viewpoint of frequency efficiency, which proves this method is appropriate for acoustic MODEM.

Adaptive RFID anti-collision scheme using collision information and m-bit identification (충돌 정보와 m-bit인식을 이용한 적응형 RFID 충돌 방지 기법)

  • Lee, Je-Yul;Shin, Jongmin;Yang, Dongmin
    • Journal of Internet Computing and Services
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    • v.14 no.5
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    • pp.1-10
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    • 2013
  • RFID(Radio Frequency Identification) system is non-contact identification technology. A basic RFID system consists of a reader, and a set of tags. RFID tags can be divided into active and passive tags. Active tags with power source allows their own operation execution and passive tags are small and low-cost. So passive tags are more suitable for distribution industry than active tags. A reader processes the information receiving from tags. RFID system achieves a fast identification of multiple tags using radio frequency. RFID systems has been applied into a variety of fields such as distribution, logistics, transportation, inventory management, access control, finance and etc. To encourage the introduction of RFID systems, several problems (price, size, power consumption, security) should be resolved. In this paper, we proposed an algorithm to significantly alleviate the collision problem caused by simultaneous responses of multiple tags. In the RFID systems, in anti-collision schemes, there are three methods: probabilistic, deterministic, and hybrid. In this paper, we introduce ALOHA-based protocol as a probabilistic method, and Tree-based protocol as a deterministic one. In Aloha-based protocols, time is divided into multiple slots. Tags randomly select their own IDs and transmit it. But Aloha-based protocol cannot guarantee that all tags are identified because they are probabilistic methods. In contrast, Tree-based protocols guarantee that a reader identifies all tags within the transmission range of the reader. In Tree-based protocols, a reader sends a query, and tags respond it with their own IDs. When a reader sends a query and two or more tags respond, a collision occurs. Then the reader makes and sends a new query. Frequent collisions make the identification performance degrade. Therefore, to identify tags quickly, it is necessary to reduce collisions efficiently. Each RFID tag has an ID of 96bit EPC(Electronic Product Code). The tags in a company or manufacturer have similar tag IDs with the same prefix. Unnecessary collisions occur while identifying multiple tags using Query Tree protocol. It results in growth of query-responses and idle time, which the identification time significantly increases. To solve this problem, Collision Tree protocol and M-ary Query Tree protocol have been proposed. However, in Collision Tree protocol and Query Tree protocol, only one bit is identified during one query-response. And, when similar tag IDs exist, M-ary Query Tree Protocol generates unnecessary query-responses. In this paper, we propose Adaptive M-ary Query Tree protocol that improves the identification performance using m-bit recognition, collision information of tag IDs, and prediction technique. We compare our proposed scheme with other Tree-based protocols under the same conditions. We show that our proposed scheme outperforms others in terms of identification time and identification efficiency.

A Novel Dual-Layer Differential Equal Gain Transmission Technique Using M-PSK Constellations (M-PSK 성운을 이용한 새로운 이중계층 차분 동 이득 전송 기술)

  • Kim, Young-Ju;Seo, Chang-Won
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.7
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    • pp.627-635
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    • 2015
  • We propose a dual-layer differential equal-gain codebook design methodology for LTE-Advanced(LTE-A), IEEE802.ac, and radar system having multiple transmit and receive antennas, and make computer simulations to evaluate its link-level performaces. M-ary phase shift keying constellation is used as its codeword elements to utilize low-cost power amplifiers at mobile stations. Especially, the proposed codebook can meet radar systems requirement for the high-powered equal-gain transmission property. Due to the temporal correlation of the adjacent channel, the proposed differential codebook can quantize only the differential information of the channel instead of the whole channel subspace, which virtually increase the codebook size to realize more accurate quantization of the channel. The proposed codebook has the same properties of LTE codebook that is, constant modulus, complexity reduction, and nested property. Computer simulations show that the proposed codebook performs better than the conventional 8-ary codebooks with the same amount of feedback information.

Coherent detection scheme for DS-CDMA system with M-ary orthogofnal signaling (M진 직교 신호화를 적용한 DS-CDMA 시스템의 동기 검파 기법)

  • 김기준;권순일;김호준;황금찬
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.23 no.4
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    • pp.1016-1023
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    • 1998
  • DS-CDMA system requeires a power-efficient transmission and reception scheme to increase capacity. In this paper, coherent detection of DS-CDMA system with M-ary orthogonal signaling is considered, and multistage decision-directed channel estimator is proposed. The multistage decision-directed channel estimator is based on the fact that better channel estimation can be obtained by using the final decisions of the detector with a conventional decision-directed channel estimator. In this scheme, symbol detector and channel estimator operate algernaely. by simulation, it is shown that the proposed method achieves performance gain capare to conventional method, specially at low signal to noise ratio over fast time-variant channel with diversity.

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