• Title/Summary/Keyword: Multi-level modulation

Search Result 144, Processing Time 0.025 seconds

Performance of multi-level QAM transceiver with adaptive power control in fixed wireless channel

  • Lee, Seong-Choon;Lee, Yong-Hwan
    • Proceedings of the IEEK Conference
    • /
    • 2000.09a
    • /
    • pp.533-536
    • /
    • 2000
  • We consider the design of quadrature amplitude modulation (QAM) transceivers f3r fixed wireless communications. The use of adaptive power control in the transmitter (Tx) can provide BER performance robust to fading and improved BER performance. The BER performance is evaluated by analytical and simulation results when multi-level QAM transceiver employing power control in the Tx is applied to fixed wireless channel with flat fading and frequency selective fading. The effect of power control parameters such as power control range and power control step size is investigated

  • PDF

A Novel Method of the Harmonic Analysis by Using the Multi-Carrier PWM Techniques in the Multi-Level Inverter (멀티 레벨 인버터에서 멀티 캐리어 PWM 방법을 사용한 고조파 분석의 새로운 방법)

  • Kim June-Sung;Kim Tae-Jin;Kang Dae-Wook;Hyun Dong-Seok
    • Proceedings of the KIPE Conference
    • /
    • 2002.11a
    • /
    • pp.171-174
    • /
    • 2002
  • This paper deals with a novel method in order to analyze the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components is different according to the carrier PWM techniques, modulation Index(Mi), and the level of multi-level inverter The previous papers analyzed the harmonic characteristics from the viewpoint of the space vector. Hence, the calculation of the harmonic vector becomes difficult and complex in 4-level or more than S-level. However, the proposed method of this paper reduced an amount of calculation and simplified the process of calculation by using the relationship between reference voltage and output phase voltage to load neutral. This paper analyzed the harmonic and it is applied to the multi-carrier PWM techniques in 5- level and other-level of cascaded inverter system.

  • PDF

Analysis and Optimization of the Cross-Modulation Noise in Multi-Band CDMA Handset (멀티밴드 CDMA 단말기에서 Cross-Modulation 잡음에 의한 영향 분석 및 최적화)

  • Kwack, Jun-Ho;Joung, In-Gun;You, Chee-Hwan;You, Jung-Ho;Kim, Hak-Sun
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.32 no.1A
    • /
    • pp.1-8
    • /
    • 2007
  • In this paper, we have derived the Noise-Equation to determine the level of cross-modulation noise that is required for designing multi-band CDMA handset from IS-98 standard. From this Noise-Equation, also we were able to determine each component's specification and forecast the performance(or margin) of designing handset. In conclusion, we have designed and implemented the multi-band CDMA handset of Qualcomm's Zero-IF structure and verified validity of the Noise-Equation. In result, we have got the result of ${\pm}0.5dB$ error between Noise-Equation and actual measurement. Therefore, this paper will give a guideline for design of the Multi-Band CDMA handset.

The Analysis of Conduction and Switching Losses in Multi-Level Inverter System (멀티레벨 인버터 시스템의 전도손실과 스위칭손실 해석)

  • 金 兌 珍;姜 岱 旭;;玄 東 石
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.7 no.2
    • /
    • pp.111-120
    • /
    • 2002
  • The multi-level inverter system is very promising in ac drives, when both reduced harmonic contents and high power are required. In case of multi-level inverter system, the loss of switch devices cannot be analyzed by conventional methods. The reason is that the loss of each the switch device is different from one another unlike 2-level. In this paper, a simple and accurate method of computing conduction and switching loss is proposed for multi-level inverter system. The validity of the proposed method is proven for 3-level and 4-revel diode clamped inverter system.

A Multi-hop OFDM Frame Structure for Short-Range Underwater Acoustic Communication Networks

  • Yu, HaiFeng;Kim, Woon;Chang, KyungHi
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.40 no.5
    • /
    • pp.809-811
    • /
    • 2015
  • In this paper, for the purpose of providing high data rate services, the multi-hop frame structure is designed for the underwater acoustic (UWA) short-range system which is proposed as a part of ocean surveillance and tracking network (OSTN). Under the measured underwater channel environment, the link-level system performance are also evaluated. Simulation results show not only the packet error rate (PER) comparisons, but the optimal modulation and coding scheme (MCS) levels for the orthogonal frequency division multiplexing (OFDM) based short-range UWA communications network.

Performance Analysis of Holographic Data Storage Depending on the Number of Levels Per Pixel of the Code Rate 1/2 Modulation Codes (부호율 1/2인 변조부호의 픽셀당 레벨 수에 따른 홀로그래픽 데이터 저장장치 성능 분석)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.52 no.10
    • /
    • pp.16-20
    • /
    • 2015
  • We propose three multi-level modulation codes of the code rate 1/2 for holographic data storage considered as a promising candidate for next generation storage systems. Since a pixel with multi-levels can represent more than 1 bit, it is possible to increase the storage capacity and have many codewords. Thus, we can choose a code that the minimum distance is as far as possible. When we compare the codes with the code rate 1/2, the performance of the code with small number of levels is better than that of large number of levels.

New symbol timming algorithm for multi-level modulation scheme

  • 송재철;최형진
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.23 no.5
    • /
    • pp.1291-1298
    • /
    • 1998
  • In this paper, a simple algorithm for detection of timing error of a synchronous, band-limited, multi-level data stream is proposed. The proposed algorithm can be applied to multi-level PAM, M-ary PSK, or M-ary QAM. The proposed algorithm for M-ary PSK requires only two samples per symbol for its operation, and it is based on the concept of transition logic table and transition level table. In orer to prove the steady-state operation of the proposed algorithm, its performance is evaluated and compared to BECM by Monte Carlo simulation method under Gaussian noise and fading noise channel environments. The comparison results confirm that the perforance of proposed algorithm is superior to that of BECM in jitter characteristics.

  • PDF

Study on The Development of MMC(Multi-level Converter) Topology and Control Algorithm (MMC(Modular Multi-level Converter) Topology 및 제어알고리즘 개발에 관한 연구)

  • Jeong, Jong-Kyou;Hong, Jung-Won;Han, Byung-Moon;Park, Yong-hee
    • Proceedings of the KIPE Conference
    • /
    • 2012.07a
    • /
    • pp.351-352
    • /
    • 2012
  • 본 논문에서는 최근 직류송전용 컨버터로 많은 관심이 집중되고 있는 MMC(Modular Multi-level Converter)에 대해서 소개하고 있다. 대용량 전압원 컨버터로 MMC가 적합한 이유에 대해서 설명하고, MMC의 동작원리, SM(Sub-Module) dc capacitor voltage balancing 기술, 전체 제어 시스템에 대해 자세하게 설명하고 있다. 제안하는 MMC는 Staircase Modulation 방식으로 사인파형에 가까운 출력전압을 형성하고, Sorting 알고리즘을 구현하여 개별 SM의 커패시터 전압이 균등하게 일정 값을 유지하도록 하였다. 제안하는 MMC의 성능평가를 위하여 PSCAD/EMTDC 프로그램을 이용하여 3상 11-level MMC를 모의하였다.

  • PDF

Improved Pre-charging Method for MMC-Based HVDC Systems Operated in Nearest Level Control

  • Kim, Kyo-Min;Kim, Jae-Hyuk;Kim, Do-Hyun;Han, Byung-Moon;Lee, Jun-Young
    • Journal of Power Electronics
    • /
    • v.17 no.1
    • /
    • pp.127-135
    • /
    • 2017
  • Recently the researches on modular multi-level converter (MMC) are being highlighted because high quality and efficient power transmission have become key issues in high voltage direct current (HVDC) systems. This paper proposes an improved pre-charging method for the sub-module (SM) capacitor of MMC-based HVDC systems, which operates in the nearest level control (NLC) modulation and does not need additional circuits or pulse width modulation (PWM) techniques. The feasibility of the proposed method was verified through computer simulations for a scaled 3-phase 10kVA MMC with 12 SMs per each arm. Hardware experiments with a scaled prototype have also been performed in the lab to confirm the simulation results.

Deadbeat and Hierarchical Predictive Control with Space-Vector Modulation for Three-Phase Five-Level Nested Neutral Point Piloted Converters

  • Li, Junjie;Chang, Xiangyu;Yang, Dirui;Liu, Yunlong;Jiang, Jianguo
    • Journal of Power Electronics
    • /
    • v.18 no.6
    • /
    • pp.1791-1804
    • /
    • 2018
  • To achieve a fast dynamic response and to solve the multi-objective control problems of the output currents, capacitor voltages and system constraints, this paper proposes a deadbeat and hierarchical predictive control with space-vector modulation (DB-HPC-SVM) for five-level nested neutral point piloted (NNPP) converters. First, deadbeat control (DBC) is adopted to track the reference currents by calculating the deadbeat reference voltage vector (DB-RVV). After that, all of the candidate switching sequences that synthesize the DB-RVV are obtained by using the fast SVM principle. Furthermore, according to the redundancies of the switch combination and switching sequence, a hierarchical model predictive control (MPC) is presented to select the optimal switch combination (OSC) and optimal switching sequence (OSS). The proposed DB-HPC-SVM maintains the advantages of DBC and SVM, such as fast dynamic response, zero steady-state error and fixed switching frequency, and combines the characteristics of MPC, such as multi-objective control and simple inclusion of constraints. Finally, comparative simulation and experimental results of a five-level NNPP converter verify the correctness of the proposed DB-HPC-SVM.