theory of spread spectrum

... capture, Spread spectrum Trang 5Fundamentals of Spread Spectrum Modulation 1 1 Introduction 1 2 Review of Basic Digital Modulation Techniques 3 3 Types of Spread Spectrum Modulation 7 4 Spreading ... example, descriptions of two generic spread spectrum modulationtechniques—QPSK spreading and frequency-hop spread spectrum Trang 174 SPREADING CODESAn important component of any spread spectrum system ... One run of ones and one run of zeros of length r – 2. r Two runs of ones and two runs of zeros of length r – 3. r Four runs of ones and four runs of zeros of length r – 4. r . r 2r−3runs of ones

Ngày tải lên: 27/06/2014, 09:20

... features of a spread spectrum modulation system The type of spread spectrum system shown in Fig 1 is known as binary direct sequence (DS) spread spectrum modulation, because a data bit 1 (of duration ... with the use of forward error correction coding The presentation ends with consideration of spread spectrum systems in the presence of other users For more complete treatments of spread spectrum, ... military applications of spread spectrum communications is classified A notable application of spread spectrum to civilian uses was to cellular radio in the 1990s with the publication of interim standard

Ngày tải lên: 07/08/2014, 21:20

... 3 TYPES OF SPREAD SPECTRUM MODULATION The two mostcommon types ofspread spectrum modulationare direct-sequence andfrequency- hop spread spectrum (FHSS). A binary direct-sequence spread spectrum ... descriptions of two generic spread spectrum modulation techniques—QPSK spreading and frequency-hop spread spectrum. book Mobk087 August 3, 2007 13:15 FUNDAMENTALS OF SPREAD SPECTRUM MODULATION 11 4 SPREADING ... run of zeros of length r–1. r One run of ones and one run of zeros of length r–2. r Two runs of ones and two runs of zeros of length r–3. r Four runs of ones and four runs of zeros of length r–4.

Ngày tải lên: 07/08/2014, 21:20

... 1 = 4; r One run of 1s and one run of 0s of length r − 2 = 3; r Two runs of 1s and two runs of 0s of length r− 3 = 2; r Four runs of 1s and four runs of 0s of length r − 4 = 1 (property 4) Property ... exception of 00000 (property 3) Close examination of the sequence b shows that there are the following runs: r One run of 1s of length r = 5; r One run of 0s of length r − 1 = 4; r One run of 1s ... preferred pair of Example 3 can be generated by using different initial loads of the shift registers of Fig 9 g D = +D +D ( ) 2 3 4 5 FIGURE 9: Circuit for generation of a family of Gold codes of length

Ngày tải lên: 07/08/2014, 21:20

... )−1R z=1. (5.25) Using the result of (5.18), the average time to reject an incorrect phase cell is the sum of the elements of the first row of the final matrix of (5.25) Since incorrect phase cells ... advantage of matched filter acquisition in terms of acquisition time is clear Trang 10FIGURE 17: Digital implementation of a noncoherent matched filter for acquisition [1].5.3 Tracking in Spread Spectrum ... acquisition time by a factor of roughly K Matched filter acquisition is often implemented digitally If N is the number of samples taken per chip, then for an initial code uncertainty of M chips it can

Ngày tải lên: 07/08/2014, 21:20

... implementation of the hardware is decidedly different OPERATING IN JAMMING—NO CODING The performance of a spread spectrum communication system in the presence of AWGN is the same as the system without spread ... single-sided bandwidth of the spread spectrum signal For direct sequence BPSK spreading, B s s ≈ 2/T c Hz, where T c is the chip duration Thus, the bit error probability of a BPSK spread communication ... same band being used by the spread spectrum system in order to raise its error probability to an unacceptable level Another possible source of interference in spread spectrum systems is multiple-access

Ngày tải lên: 07/08/2014, 21:20

... space can exist simultaneously in a spread spectrum system if their respective spreading codes have low cross-correlation between them. This property of spread spectrum systems is called code-division ... improve performance of FH/DPSK in optimized tone jamming. capability of spread spectrum systems, consider the simplified block diagram of Fig. 37, which represents a baseband version of K simultaneous ... FUNDAMENTALS OF SPREAD SPECTRUM MODULATION r For a linear code the sum of any two codewords is also a codeword. This means that we can characterize the error-correction capability of a linear

Ngày tải lên: 07/08/2014, 21:20

... Outage probability of a DS/FH system; Impact of the number of interferers, the number of antenna elementsM = 2, processing gainG DS =50, the number of usersK =40, duty cycles of interferes areρ1= ... impact of the number of hopping channels, the number of antenna elements M =2, processing gainG DS =50, the number of usersK =40, the number of interferers isJ1 =1, J2 =2, J3 =3, duty cycles of interferes ... 12: Outage probability of a DS/FH system, impact of the number of multipath, the number of antenna elementsM = 2, processing gainGDS=50, the number of usersK =40, the number of interferers isJ1

Ngày tải lên: 21/06/2014, 19:20

... CORRELATION ANALYSIS OF SEQUENCES DESIGNED FOR SPREAD SPECTRUM WATERMARKING Nguyen Le Cuong* Abstract: In this paper, some concepts of correlation analysis which is mandatory in spread spectrum (SS) ... Watermarking, Spread spectrum, Correlation analysis 1 INTRODUCTION Along with the digitalization of media assets, the rapid growth of the Internet, and the speed of file transfers, the danger of intellectual ... out the maximum value According to [11] spread spectrum watermarking technique offers robustness Spread spectrum embedding is resistant against number of attacks, especially highly resistant

Ngày tải lên: 10/02/2020, 00:45

... GENERATION AND SELECTION OF SEQUENCES FOR SPREAD SPECTRUM WATERMARK AND STEGANOGRAPHY Nguyen Le Cuong* Abstract: In this contribution, criteria for the sequences employed in spread spectrum (SS) watermarking ... rights These hidden messages consist of a group of bits giving information about the author of the signal or the signal itself In the last decade, the spread spectrum communications (CDMA, HSPA) ... Steganography 1 INTRODUCTION Along with the digitalization of media assets, the rapid growth of the Internet, and the speed of file transfers, the danger of intellectual right violation become obvious

Ngày tải lên: 10/02/2020, 02:37

... propagation in terms of a wavevector spectrum Rather, it is morecommon to use an angle spectrum which represents the angle-of-arrival of multipath power.While use of an angle spectrum is common, ... Limiting Behavior 1174.B.4 Preservation of the Second Moment 1175The Angle Spectrum1185.1 Angle Spectrum Concepts 1195.1.1 Definition of the Angle Spectrum 1195.1.2 Mapping Angles to ... thisconcept are often ignored.Chapter 5 rigorously defines the angle spectrum, describing the exact class of channelmodels for which this spectrum is valid Furthermore, this chapter introduces one of themost

Ngày tải lên: 20/11/2012, 11:36

... multi-carrier, spread spectrum and multi-carrier spreadspectrum systems We hope that this book will contribute to a better understanding of the principles of multi-carrier and spread spectrum and ... transmission is introduced In addition, a generaloverview of the spread spectrum technique, especially of DS-CDMA, is given Examples of applications of OFDM and DS-CDMA for broadcast, WLAN, and cellular ... understanding of the idea behind the combination of OFDM withthe spread spectrum technique, which is briefly introduced in the last part of this chapter Understanding the characteristics of the communications

Ngày tải lên: 02/03/2013, 16:58

... revision of the proof of the law of conservation of angular momentum in relativistic mechanics, and also a more detailed discussion of the question of symmetry of the Christoffel symbols in the theory ... transformation of velocities They describe the law of composition of velocities in the theory of relativity In the limiting case of c > ©, they go over into the formulas v; = Ví + V, Vy, = Vj, Ve = V of ... mechanics the law of conservation of mass does not hold: the mass of a composite body is not equal to the sum of the masses of its parts Instead only the law of conservation of energy, in which

Ngày tải lên: 30/12/2013, 10:45

... 2Chapter XX Quantum theory of light§ 1 Blackbody radiation Planck’s theory of radiation § 2 Photoelectric effect Einstein’s theory of light § 3 Compton scattering Trang 3At the end of the 19-th century, ... quantum theory of light:To overcome the difficulty of classical physics, Albert Einstein introducedthe quantum theory of light, and developed the correct analysis of the 2.2.2 Analysis of the ... variation of the radiation of a filament of electric lampwhen the electric current varies) • Observation of the spectrum emitted by a solid shows that the radiationextends over a continous range of

Ngày tải lên: 24/01/2014, 07:20

... Trang 1 Theory of the-radio channels Theory of the radio channels Dr.-Eng Van Duc Nguyen Trang 2 Back ground of stastistical theory Definition of autocorrelation function of a Trang ... is commonly used Trang 25 Power Delay Profile of the-Channel >» Definition of power delay profile of the channel: >» The power delay profile of the channel can be obtained from the autocorrelation ... (CFT) is the Fourier transform of CIR: Trang 11€oherence:Bandwidth:of:the Channel: * Coherence bandwidth (A/),= ye is a measure of the frequency selectivity of a channel (A/) * Non-frequency

Ngày tải lên: 27/01/2014, 08:20

... operator description of the theory. In fact, the Gromov-Witten theory of P 1 may be viewed as a more funda- mental object than the Gromov-Witten theory of a point. Indeed, the theory of P 1 has a simpler ... nonequivariant theory. Via the nonequivariant limit, the full nonequivariant theory of P 1 is captured by the equivariant theory. The equivariant Gromov-Witten theory of P 1 is the subject of the present paper. ... structure. The theory of P 1 is not based on the theory of a point. Rather, the point theory is perhaps best understood as a certain special large degree limit case of the P 1 theory; see [23]. 0.1.5.

Ngày tải lên: 16/02/2014, 06:20

... dùng cho thông tin vệ tinh trong CDMA. Trải phổ nhảy tần Frequency Hopping Spread Spectrum  Frequency Hopping Spread Spectrum (FHSS)  Được phát minh bởi nữ diễn viên Hollywood Hedy Lamarr, ... thu và máy phát đều có bộ tạo mã PN gồm k chíp mã tương ứng với 1 từ tần số Direct Sequence Spread Spectrum Transmitter Vídụ CDMA Các ưu nhược điểm FHSS  Ưu điểm :  Giảm fading đa đường do ... phát hiện Nhảy tần nhanh (Fast FHSS) (M=4, k=2) Điều chế và giải điều chế Direct Sequence Spread Spectrum Transmitter Trải phổ nhảy tần  Dẫy PN dùng để điều khiển (xác định) mẫu nhảy. Tốc...

Ngày tải lên: 13/09/2012, 11:16

... 43 OFDM February 2005 Copyright 2005 All Rights Reserved 3 Spread Spectrum ● Spread spectrum is a communication technique that spreads a narrowband communication signal over a wide range of ... which employs OFDM in the 2.4 GHz range February 2005 Copyright 2005 All Rights Reserved 6 Spread Spectrum Use ● In the 1980s FCC implemented a set of rules making Spread Spectrum available ... the imaginary or quadrature axis of the complex plane. February 2005 Copyright 2005 All Rights Reserved 4 Narrowband vs Spread Spectrum Frequency Power Spread Spectrum (Low Peak Power) Narrowband (High...

Ngày tải lên: 13/09/2012, 11:16

... which are seen as a form of market imperfection. The mainstream theory of the firm evolved under the paradigm of the agency theory and the transaction costs theory as a theory of economic organization rather ... amendment of the existing theory of financial intermediation. The structure of this paper is as follows. First, we introduce the foundations of the modern literature of financial intermediation theory. ... review the doctrines of the theory of financial intermediation. 2 These are specifications, relevant to the financial services industry, of the agency theory, and the theory of imperfect or asymmetric...

Ngày tải lên: 24/10/2012, 09:11