DOCSLIB.ORG

Iterative Intersymbol Interference Cancellation in Vestigial Sideband Nyquist–Subcarrier Modulation System

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Iterative Intersymbol Interference Cancellation in Vestigial Sideband Nyquist–Subcarrier Modulation System Iterative intersymbol interference cancellation in vestigial sideband Nyquist–subcarrier modulation system Na Liu Xue Chen Cheng Ju Rongqing Hui Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 10/26/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 53(11), 116109 (November 2014) Iterative intersymbol interference cancellation in vestigial sideband Nyquist–subcarrier modulation system Na Liu,a,* Xue Chen,a Cheng Ju,a and Rongqing Huib aBeijing University of Posts and Telecommunications, State Key Lab of Information Photonics and Optical Communications, P.O. Box 128, #10 XiTuCheng Road, HaiDian District, Beijing 100876, China bUniversity of Kansas, Department of Electrical Engineering and Computer Science, 3026 Eaton Hall, 1520 W. 15th Street, Lawrence, Kansas 66045, United States Abstract. The intersymbol interference caused by dispersion, chirp, and a vestigial sideband filter in intensity modulation and a direct detection single carrier system is analyzed theoretically and numerically. An iterative nonlinear intersymbol interference cancellation technique is proposed and experimentally demonstrated in a 40- Gbps 16-QAM Mach-Zehnder modulator-based vestigial sideband intensity modulation and direct detection half- cycle Nyquist–subcarrier modulation system over a 100-km uncompensated standard single-mode fiber trans- mission for the first time. The experimental results show that 2.2-dB receiver sensitivity improvement is obtained at the forward error correction limit by using the iterative technique. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.53.11.116109] Keywords: intensity modulation; direct detection; vestigial sideband; intersymbol interference. Paper 141412 received Sep. 11, 2014; accepted for publication Oct. 17, 2014; published online Nov. 12, 2014. 1 Introduction Compared with SQRT and NL-FFE-DFE, a better perfor- The increasing demand to achieve both higher bit rates and mance can be obtained by using an MLSE with a higher spectral efficiency using cost-effective systems is especially complexity. 14 strong in short-range communication. Intensity modulation In this paper, a theoretical model is first established to and direct detection (IMDD) based optical communication investigate the dispersion-, chirp, VSB filter-induced ISI in a systems with high-order modulation formats have continued VSB-IMDD single carrier system. In more detail, the ISI to attract attention because of the low cost and simple imple- can be divided into two parts, namely the linear part and mentation, such as a half-cycle Nyquist–subcarrier modula- the nonlinear part. A conventional electrical dispersion com- 8 tion (SCM).1,2 For a double sideband (DSB) signal, the pensation method, overlap FDE (O-FDE), is used to compen- dispersion power penalty caused by dispersive transmission sate the linear distortion. An iterative distortion cancellation with direct detection limits the transmission distance.3 technique used in an orthogonal frequency division multiplex- – Without an expensive optical dispersion compensator, opti- ing system15 17 is introduced to mitigate the nonlinear ISI. cal vestigial sideband (VSB) filtering is a more practical and Furthermore, we have experimentally demonstrated a 40- desirable method for improving the chromatic dispersion tol- Gbps 16-quadrature amplitude modulation (QAM) Mach- erance4,5 and the spectral efficiency of a dense wavelength Zehnder modulator (MZM)-based VSB-IMDD half-cycle division multiplexing system.6 However, the square-law Nyquist-SCM system transmission over a 100-km uncom- detection of the VSB signal still induces intersymbol inter- pensated standard single-mode fiber (SSMF) with iterative ference (ISI), which degrades the transmission performance. nonlinear ISI cancellation. A cost-effective fiber Bragg gra- Electrical equalization methods have been widely ting (FBG) optical filter is used to realize the VSB filter. The explored to suppress the ISI generated by chromatic experimental results show that 2.2-dB receiver sensitivity is dispersion, such as feed-forward equalizers (FFE), decision improved at the forward error correction (FEC) limit. The feedback equalizers (DFE),7 and frequency-domain equali- iterative nonlinear ISI cancellation in a VSB-IMDD half- zation (FDE).8,9 But they cannot fully compensate the distor- cycle Nyquist-SCM system can effectively suppress the tions because the absolute square-law detection of the destructive effect of the nonlinear ISI. photodiode (PD) is the fundamental reason why the perfor- mance of conventional linear equalizer is degraded. A non- linear equalizer is used to further enhance the system 2 Theoretical Model performance, such as a mathematical square root operator The principle of a VSB-IMDD half-cycle Nyquist-SCM 10 11 (SQRT), nonlinear FFE-DFE (NL-FFE-DFE), and maxi- system is shown in Fig. 1. The optical transmitter is a 12,13 mum-likelihood sequence estimation (MLSE). SQRT conventional half-cycle 16-QAM Nyquist-SCM modulation can linearize the receiver before equalization, but this cannot scheme.1 A VSB filter is placed after the intensity modu- change the fact that the phase information introduced by lator to achieve vestigial sideband transmission. At the dispersion is lost even after the square root operation. receiver, O-FDE is carried out after downconversion to com- NL-FFE-DFE can be considered to be an extension from pensate the linear distortion based on the block-to-block the normal DFE with both an FFE filter and a DFE filter. operation.8 *Address all correspondence to: Na Liu, E-mail: [email protected] 0091-3286/2014/$25.00 © 2014 SPIE Optical Engineering 116109-1 November 2014 • Vol. 53(11) Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 10/26/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Liu et al.: Iterative intersymbol interference cancellation in vestigial sideband Nyquist–subcarrier modulation system Power Optical Transmitter Signal with linear ISI Optical Receiver Nonlinear ISI Freq. Power Cos[2pi(Fs/2)t] Cos[2pi(Fs/2)t] Spectrum after VSB filter Q Nyquist Freq. Up AM I LD I O/E Equ Pulse D Cut samp I e F A FFT VSB F cis Ma Shaping i a D l [0 Fs/2] FT ou t liz C e IM i on pping r li t e ng SSMF Nyquist r Pulse Q Shaping Q [0 Fs/2] One block t ... D0 D1 D2 ... DM-1 ... FDE weight -Sin[2pi(Fs/2)t] -Sin[2pi(Fs/2)t] estimation One symbol Fig. 1 Principle of vestigial sideband intensity modulation and direct detection (VSB-IMDD) half-cycle Nyquist–subcarrier modulation (SCM) system. 2 H n ejn θD θ β Lω2∕ In this section, a theoretical model is built to analyze the be expressed as CDð Þ¼ ,where D ¼ 2 2. causes of ISI in a VSB-IMDD single carrier system. In this Thus, if Θf·g represents a signal after dispersive transmis- M D ;D :::D model, continuous symbols, ½ 0 1 M−1, combine sion, then as a block, as shown in Fig. 1. The block before the intensity modulator can be expanded into a Fourier series, XN P 1 2 N jnωt jnωt jn θD V ¼ Rf vne g, where ω is the first-order harmonic, ΘfX ; g¼ r H ðnÞvne e n¼1 1 VSB 2 USB vn is the complex information of the n’th-order harmonic, N n¼1 is the index of the highest-order harmonic, and Rf·g repre- XN 1 −jnωt jn2θ sents the real part. Assuming the intensity modulator is a lin- þ r H ðnÞvne e D ; 2 LSB ear electro-optic system with a constant chirp parameter α, n¼1 the normalized optical power envelop canP be written as P X X R X X r N v ejnωt r ¼ 1 þ 1, where 1 ¼ f ng, n ¼ n n . X2N ¼1 1 ˜ 2 jðnωtþθnÞ jn θD is a scaling constant used to set an appropriate optical ΘfX ; g¼ H ðnÞx˜ne e pPffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 VSB 2 USB r N v 2 18 n¼1 modulation index (OMI), where OMI ¼ n¼1 j nj . Accordingly, the normalized envelope of the optical field X2N 1 ˜ 2 1−jα α2 H n x˜ e−jðnωtþθnÞejn θD can be approximated as E 1 X − 1þ X , where þ LSBð Þ n . ¼ þ 2 1 8 2 2 X X X2 R X X n¼1 2 is the second-order term, 2 ¼ 1 ¼ f 2ng, 2n ¼ P ˜ 2N x˜ ejðnωtþθnÞ 14 v n¼1 n , and the higher-order terms of n are dis- Accordingly, the optical field becomes regarded. After the VSB filter, the first- and second-order pffiffiffiffiffiffiffiffiffiffiffiffi 2 2 terms can be expressed as 1 þ α −jθ 1 þ α E ¼ Hð0Þþ e α ΘfX ; g − ΘfX ; g: CD 2 1 VSB 8 2 VSB XN XN X 1r H n v ejnωt 1r H n v e−jnωt (2) 1;VSB ¼ USBð Þ n þ LSBð Þ n 2 n 2 n ¼1 ¼1 The received signal after square-law photodetection is and R ¼jE j2 CD pffiffiffiffiffiffiffiffiffiffiffiffiffi X2N 1 ˜ 2 2 −jθα jðnωtþθnÞ ≅ H α H R e Θ X X ; ¼ H ðnÞx˜ne ½ ð0Þ þ 1 þ ð0Þ ½ ð 1;VSBÞ 2 VSB 2 USB n¼1 1 α2 þ Θ X 2 − H R Θ X : X2N þ fj ð 1;VSBÞj ð0Þ ½ ð 2;VSBÞg (3) 1 ˜ 4 −jðnωtþθnÞ þ H ðnÞ x˜ne ; 2 LSB n¼1 The first term in Eq. (3) is the direct current component, H H the second term contains the desired block signal, and the where USB and LSB are the frequency responses of the third term represents the nonlinear distortion of block signal. VSB filter in the upper sideband and lower sideband. From Eq. (3), without the VSB filter, that is Hð0Þ¼ Then the optical field can be expressed as HUSB n HLSB n VSBð Þ¼ VSBð Þ¼1, the second term can be written as ffiffiffiffiffiffiffiffiffiffiffiffi p pffiffiffiffiffiffiffiffiffiffiffiffi N 1 α2 1 α2 X þ −jθα þ 2 2 2 E ¼ Hð0Þþ e X ; − X ; ; (1) 1 þ α r cosðn ω β L∕2 − θαÞjvnjcosðnωt þ φnÞ; VSB 2 1 VSB 8 2 VSB 2 n¼1 −1 v φ where θα ¼ tan α,andHð0Þ denotes the frequency response where j nj and n are the amplitude and phase of the jφ of the VSB filter at the optical carrier.
Load more

Recommended publications
  • Protection of Data Transmission Systems from the Influence of Intersymbol Interference of Signals
    59 Protection of data transmission systems from the influence of intersymbol interference of signals © Volodymyr Yartsev 1 and © Dmitry Gololobov 2 1 State University of Telecommunications, Kyiv, Ukraine 2 Taras Shevchenko National University of Kyiv, Ukraine [email protected], [email protected] Abstract. The problems of creating a regenerator of an optical system for trans- mitting discrete messages with the aim of protecting against the influence of in- tersymbol interference of signals using the methods of statistical theory for a mixture of probability distributions are considered. A demodulator adaptation model that calculates the weighted sum of 4 samples of the input signal and com- pares the resulting sum with a threshold value has been created and studied. The main operations for adaptation of the regenerator during demodulation of signals distorted by intersymbol interference are assigned under certain transmission conditions, which are formulated as the task of evaluating some parameters of the probability distribution of the mixture. A block diagram of a regenerating optical signal in which an algorithm for digital processing of a mixture is imple- mented is proposed. The analysis is carried out and the requirements for the pa- rameters of the analog-to-digital converter used in the regenerator are deter- mined. The results of modeling digital processing of a discrete test message to verify the process of adaptation of the device to the influence of intersymbol dis- tortions of signals are presented. The block diagram of a digital processing device is substantiated, in which high-speed nodes that perform real-time processing are combined with a microprocessor, which implements an algorithm for adapting the regenerator to specific message transmission conditions.
    [Show full text]
  • Pulse Shape Filtering in Wireless Communication-A Critical Analysis
    (IJACSA) International Journal of Advanced Computer Science and Applications, Vol. 2, No.3, March 2011 Pulse Shape Filtering in Wireless Communication-A Critical Analysis A. S Kang Vishal Sharma Assistant Professor, Deptt of Electronics and Assistant Professor, Deptt of Electronics and Communication Engg Communication Engg SSG Panjab University Regional Centre University Institute of Engineering and Technology Hoshiarpur, Punjab, INDIA Panjab University Chandigarh - 160014, INDIA [email protected] [email protected] Abstract—The goal for the Third Generation (3G) of mobile networks. The standard that has emerged is based on ETSI's communications system is to seamlessly integrate a wide variety Universal Mobile Telecommunication System (UMTS) and is of communication services. The rapidly increasing popularity of commonly known as UMTS Terrestrial Radio Access (UTRA) mobile radio services has created a series of technological [1]. The access scheme for UTRA is Direct Sequence Code challenges. One of this is the need for power and spectrally Division Multiple Access (DSCDMA). The information is efficient modulation schemes to meet the spectral requirements of spread over a band of approximately 5 MHz. This wide mobile communications. Pulse shaping plays a crucial role in bandwidth has given rise to the name Wideband CDMA or spectral shaping in the modern wireless communication to reduce WCDMA.[8-9] the spectral bandwidth. Pulse shaping is a spectral processing technique by which fractional out of band power is reduced for The future mobile systems should support multimedia low cost, reliable , power and spectrally efficient mobile radio services. WCDMA systems have higher capacity, better communication systems. It is clear that the pulse shaping filter properties for combating multipath fading, and greater not only reduces inter-symbol interference (ISI), but it also flexibility in providing multimedia services with defferent reduces adjacent channel interference.
    [Show full text]
  • Iterative Methods for Cancellation of Intercarrier Interference in OFDM Systems
    MITSUBISHI ELECTRIC RESEARCH LABORATORIES http://www.merl.com Iterative Methods for Cancellation of Intercarrier Interference in OFDM Systems Andreas Molisch, Martin Toeltsch, Sameer Vermani TR2007-096 August 2008 Abstract We consider orthogonal frequency-division multiplexing systems with intercarrier interference (ICI) due to insufficient cyclic prefix and/or temporal variations. Intersymbol interference (ISI) and ICI lead to an error floor in conventional receivers. We suggest two techniques for the equalization of ICI. The first, called ”operator-perturbation technique” is an iterative technique for the inversion of a linear system of equations. Alternatively, we show that serial or parallel interference cancellation can be used to drastically reduce the error floor. Simulations show that, depending on the SNR and the origin of the ICI, one of the schemes performs best. In all cases our schemes lead to a drastic reduction of the bit error rate. IEEE Transactions on Vehicular Technology, 2007 This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Copyright c Mitsubishi Electric Research Laboratories, Inc., 2008 201 Broadway, Cambridge, Massachusetts 02139 MERLCoverPageSide2 2158 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL.
    [Show full text]
  • Digital Phase Modulation: a Review of Basic Concepts
    Digital Phase Modulation: A Review of Basic Concepts James E. Gilley Chief Scientist Transcrypt International, Inc. [email protected] August , Introduction The fundamental concept of digital communication is to move digital information from one point to another over an analog channel. More specifically, passband dig- ital communication involves modulating the amplitude, phase or frequency of an analog carrier signal with a baseband information-bearing signal. By definition, fre- quency is the time derivative of phase; therefore, we may generalize phase modula- tion to include frequency modulation. Ordinarily, the carrier frequency is much greater than the symbol rate of the modulation, though this is not always so. In many digital communications systems, the analog carrier is at a radio frequency (RF), hundreds or thousands of MHz, with information symbol rates of many megabaud. In other systems, the carrier may be at an audio frequency, with symbol rates of a few hundred to a few thousand baud. Although this paper primarily relies on examples from the latter case, the concepts are applicable to the former case as well. Given a sinusoidal carrier with frequency: fc , we may express a digitally-modulated passband signal, S(t), as: S(t) A(t)cos(2πf t θ(t)), () = c + where A(t) is a time-varying amplitude modulation and θ(t) is a time-varying phase modulation. For digital phase modulation, we only modulate the phase of the car- rier, θ(t), leaving the amplitude, A(t), constant. BPSK We will begin our discussion of digital phase modulation with a review of the fun- damentals of binary phase shift keying (BPSK), the simplest form of digital phase modulation.
    [Show full text]
  • Digital Transmission Over Baseband Channels
    Principles of Communications Chapter 5: Digital Transmission through Bandlimited Channels Selected from Chapter 9.1-9.4 of Fundamentals of Communications Systems, Pearson Prentice Hall 2005, by Proakis & Salehi Meixia Tao @ SJTU 1 Topics to be Covered A/D D/A Source Channel Detector User converter converter . Digital waveforms over bandlimited baseband channels . Band-limited channel and Inter-symbol interference . Signal design for band-limited channels . System design . Channel equalization Meixia Tao @ SJTU 2 Bandlimited Channel 5MHz, 10MHz 20MHz 15MHz, 20MHz . Modeled as a linear filter with frequency response limited to certain frequency range Meixia Tao @ SJTU 3 Baseband Signalling Waveforms . To send the encoded digital data over a baseband channel, we require the use of format or waveform for representing the data . System requirement on digital waveforms . Easy to synchronize . High spectrum utilization efficiency . Good noise immunity . No dc component and little low frequency component . Self-error-correction capability . … Meixia Tao @ SJTU 4 Basic Waveforms . Many formats available. Some examples: . On-off or unipolar signaling . Polar signaling . Return-to-zero signaling . Bipolar signaling – useful because no dc . Split-phase or Manchester code – no dc Meixia Tao @ SJTU 5 0 1 1 0 1 0 0 0 1 1 On-off (unipolar) polar Return to zero bipolar Manchester Meixia Tao @ SJTU 6 Spectra of Baseband Signals . Consider a random binary sequence g0(t) - 0，g1(t) - 1 . The pulses g0(t）g1(t）occur independently with probabilities given by p and 1-p，respectively. The duration of each pulse is given by Ts. s(t) gt0 (+ 2) TS gt1(− 2) TS ∞ Ts s(t) = ∑ sn (t) n=−∞ g0 ( t− nTs ), with prob.
    [Show full text]
  • Symbol-Based Multi-Layer Iterative Successive Interference
    1 Symbol-Based Multi-Layer Iterative Successive Interference Cancellation for Faster-Than-Nyquist Signaling Qiang Li12, Feng-Kui Gong12, Pei-Yang Song1 and Sheng-Hua Zhai34 1 State Key Laboratory of Integrated Service Networks (ISN), Xidian University, Shaanxi, Xi’an 710071, China 2 Collaborative innovation center of information sensing and understanding, Shaanxi, Xi’an 710071, China 3 School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China 4 CAST-Xi’an Institute of Space Radio Technology, Xi’an 710071, China Abstract—A symbol-based multi-layer iterative successive in- interference (ISI). Nevertheless, the orthogonality of Nyquist terference cancellation (MLISIC) algorithm is proposed to elim- signaling is at the cost of sacrificing the spectrum efficiency. inate the inter-symbol interference (ISI) for faster-than-Nyquist By deliberately introducing ISI, higher transmission rate and (FTN) signaling. The computational complexity of the proposed MLISIC algorithm is much lower than most existing block-based spectrum efficiency can be supported in the FTN system. estimation algorithms. By comparison with existing symbol-based Besides, FTN transmission can moderate the need for high- algorithms, the proposed MLISIC algorithm has higher estima- order modulations and low rolling factors. Thus, the adverse tion accuracy. Furthermore, by means of utilizing more accurate effect of the phase noise distortion and the timing error can symbols and elaborate length of successive interference cancella- be mitigated.
    [Show full text]
  • Predicting Microwave Digital Signal Integrity James F
    280 IEEE TRANSACTIONS ON ADVANCED PACKAGING, VOL. 32, NO. 2, MAY 2009 Predicting Microwave Digital Signal Integrity James F. Buckwalter, Member, IEEE Abstract—High-speed digital signal integrity at data rates above of one link to the next and depends on a large number of fac- 6 Gb/s is an obstacle to reliable serial link operation. Two signal tors including the substrate material, packaging, and routing of integrity challenges include dispersion due to frequency-depen- signals. Therefore, optimization of link performance requires dent losses and reflections created at impedance mismatches. Signal integrity analysis relies on time-domain simulation of predictive modeling techniques for digital signal integrity that pseudo-random data patterns. This paper explores a predictive verify experimental results. method for interconnect eye closure caused by reflections at the Above 6 Gb/s, ISI and DDJ result from a combination of low transmitter and receiver and does not require extensive time do- channel bandwidth and signal reflections. This paper provides main simulation. Worst-case bounds on intersymbol interference and data-dependent jitter aid prediction for link budgets under an analytical method for estimating eye closure based on both channel variations. This method is applied to the design of a of these impairments and is intended to limit the amount of passive equalizer. time-domain simulation. A frequency-domain description of Index Terms—Data dependent jitter, interconnect modeling, in- an impedance discontinuity characterizes the step response tersymbol interference, jitter, signal integrity. of the reflected signal [13]. The step response characteristics are directly related to eye height and width. Predicting signal integrity from the step response behavior can avoid extensive I.
    [Show full text]
  • Rake Reception for Uwb Communication Systems with Intersymbol Interference
    RAKE RECEPTION FOR UWB COMMUNICATION SYSTEMS WITH INTERSYMBOL INTERFERENCE A.G. Klein†, D.R. Brown III‡, D.L. Goeckel§, and C.R. Johnson, Jr.† † Cornell University, School of Electrical and Computer Engineering, Ithaca, NY 14853 ‡ Worcester Polytechnic Inst., Dept. of Electrical and Computer Engineering, Worcester, MA 01609 § University of Mass., Dept. of Electrical and Computer Engineering, Amherst, MA 01003 ABSTRACT have demonstrated delay spreads far beyond 30 ns [2][3], which indicate that significant intersymbol interference (ISI) Recently, ultra wideband (UWB) technology has been pro- is unavoidable. A RAKE receiver, the preferred structure posed for use in wireless personal area networks (WPANs). for collecting multipath energy in UWB systems, does not Under the conditions where such transceivers are expected combat ISI. The vast majority of published results on UWB to operate, intersymbol interference (ISI) will become a sig- have overlooked this fact as most performance analyses em- nificant performance limitation, and improvements to con- ploy a RAKE receiver under the assumption that channel ventional RAKE reception will be necessary. We propose a delay spreads are much less than the pulse repetition period modified RAKE receiver that finds an optimal balance be- [4]. In this paper, the RAKE structure is modified to one tween the goal of gathering multipath signal energy, avoid- that considers ISI and narrowband interference. By mini- ing ISI, and suppressing narrowband interference. For fixed mizing the mean squared error (MSE), we arrive at a choice RAKE finger delays, we develop a closed-form expression of RAKE delays and combining weights that yield supe- for the minimum mean squared error (MMSE) combining rior performance when compared to maximal ratio combin- weights that account for ISI.
    [Show full text]
  • TR 101 190 V1.3.2 (2011-05) Technical Report
    ETSI TR 101 190 V1.3.2 (2011-05) Technical Report Digital Video Broadcasting (DVB); Implementation guidelines for DVB terrestrial services; Transmission aspects 2 ETSI TR 101 190 V1.3.2 (2011-05) Reference RTR/JTC-DVB-304 Keywords broadcasting, digital, DVB, MPEG, TV, video ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 Important notice Individual copies of the present document can be downloaded from: http://www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at http://portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http://portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media.
    [Show full text]
  • Orthogonal Frequency Division Multiplexing and Its Applications
    International Journal of Science and Research (IJSR), India Online ISSN: 2319-7064 Orthogonal Frequency Division Multiplexing and its Applications Beena R. Ballal1, Ankit Chadha2, Neha Satam3 1Assistant Professor, Electronics and Telecommunication, VIT, Wadala Mumbai, India [email protected] 2Student, Electronics and Telecommunication, VIT, Wadala Mumbai, India [email protected] 3Student, Electronics and Telecommunication, VIT, Wadala Mumbai, India [email protected] Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technique which is very much popular in new wireless networks of IEEE standard, digital television, audio broadcasting and 4G mobile communications. The main benefit of OFDM over single-carrier schemes is its ability to cope with severe channel conditions without complex equalization filters. It has improved the quality of long-distance communication by eliminating InterSymbol Interference (ISI) and improving Signal-to-Noise ratio (SNR). The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset. This paper gives an overview of OFDM, its applications in various systems such as IEEE 802.11a, Digital Audio Broadcasting (DAB) and Digital Broadcast Services to Handheld Devices (DVB-H) along with its advantages and disadvantages. Keywords: OFDM, Multipath Fading, Time-Slicing, Spectral Efficiency, ISI. 1. Introduction 802.20. OFDM converts a frequency-selective channel into a During the last few decades, growth rate of wireless parallel collection of frequency flat sub channels [2].Though technology has been accelerated to such a level that it has it is derived from frequency division multiplexing (FDM), become ubiquitous. Progress in fiber-optics with assurance OFDM provides many advantages over this conventional of almost limitless bandwidth and predictions of universal technique.
    [Show full text]
  • Multipath Propagation Bandlimited Channels
    What is Intersymbol Interference? Intersymbol interference is a signal distortion in telecommunication. One or more symbols can interfere with other symbols causing noise or a less reliable signal. The main causes of intersymbol interference are multipath propagation or non-linear frequency in channels. This has the effect of a blur or mixture of symbols, which can reduce signal clarity. If intersymbol interference occurs within a system, the receiver output becomes erroneous at the decision device. This is an unfavorable result that should be reduced to the most minimal amount possible. Error rates from intersymbol interference are minimized through the use of adaptive equalization techniques and error correcting codes. Multipath Propagation Multipath propagation causes intersymbol interference when a wireless signal being transmitted reaches a receiver through different paths. This commonly occurs when reflected signals bounce off of surfaces, when the wireless signal refracts through obstacles, and because of atmospheric conditions. These paths have different lengths before reaching the receiver, thus creating different versions that reach at different time intervals. The delay in symbol transmission will interfere with correct symbol detection. The amplitude and or phase of the signal can be distorted when the different paths are received for additional interference. Bandlimited Channels A bandlimited channel is cut off past certain frequency ranges. This results in a zero response when the signal is below or above the frequency range that the receiver allows. Whenever thissignal type goes out of range, frequency components that are removed are then an incomplete signal. The channel with missing information, therefore, cannot use the attenuated frequency. This occurs because the receiver’s filtration collects the pulse’s shape differently.
    [Show full text]
  • An Introduction to Orthogonal Frequency-Division Multiplexing
    !N INTRODUCTION TO ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING /VE %DFORS -AGNUS 3ANDELL *AN *AAP VAN DE "EEK $ANIEL ,ANDSTR¶M &RANK 3J¶BERG 3EPTEMBER !BSTRACT 4HIS REPORT IS AN INTRODUCTION TO ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING /&$- 4HE FOCUS IS ON SIGNAL PROCESSING AREAS PURSUED BY OUR RESEARCH GROUP AT ,ULE¥ 5NIVERSITY OF 4ECHNOLOGY 7E PRESENT AN HISTORICAL BACKGROUND AND SOME FREQUENTLY USED SYSTEM MODELS 4YPICAL AREAS OF APPLICATIONS ARE ALSO DESCRIBED BOTH WIRELESS AND WIRED )N ADDITION TO THE GENERAL OVERVIEW THE ADDRESSED AREAS INCLUDE SYNCHRONIZATION CHANNEL ESTIMATION AND CHANNEL CODING "OTH TIME AND FREQUENCY SYNCHRONIZATION ARE DESCRIBED AND THE EdECTS OF SYNCHRONIZATION ERRORS ARE PRESENTED $IdERENT TYPES OF CHANNEL ESTIMATORS ARE DESCRIBED WHERE THE FOCUS IS ON LOW COMPLEXITY ALGORITHMS AND IN THIS CONTEXT ADVANTAGES AND DISADVANTAGES OF COHERENT AND DIdERENTIAL MODULATION ARE ALSO DISCUSSED #HANNEL CODING IS DESCRIBED BOTH FOR WIRELESS AND WIRED SYSTEMS AND POINTERS ARE INCLUDED TO EVALUATION TOOLS AND BITLOADING ALGORITHMS !N EXTENSIVE BIBLIOGRAPHY IS ALSO INCLUDED #ONTENTS )NTRODUCTION 3YSTEM MODELS #ONTINUOUS TIMEMODEL $ISCRETE TIMEMODEL ! TIME FREQUENCY INTERPRETATION )MPERFECTIONS 3YSTEM ENVIRONMENTS 7IRELESSSYSTEMS $OWNLINK 5PLINK 7IREDSYSTEMS 3UBSCRIBER LINE TRANSFER FUNCTION .OISE AND CROSSTALK 3YNCHRONIZATION 3YMBOLSYNCHRONIZATION 4IMING ERRORS #ARRIER PHASE NOISE 3AMPLING FREQUENCY SYNCHRONIZATION #ARRIER FREQUENCY SYNCHRONIZATION &REQUENCY ERRORS &REQUENCY
    [Show full text]