1 / 33

Principles of Communications 通訊原理

Principles of Communications 通訊原理. Textbook : Communication Systems , 4 th Edition by Simon Haykin John Wiley & Sons , Inc 歐亞書局代理 Midterm 45% Final 45% Homework 10% http://cc.ee.ntu.edu.tw/~wujsh/. Contents. Background and Preview

kreeli
Download Presentation

Principles of Communications 通訊原理

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Principles of Communications通訊原理 Textbook : Communication Systems , 4th Edition by Simon Haykin John Wiley & Sons , Inc 歐亞書局代理 Midterm 45% Final 45% Homework 10% http://cc.ee.ntu.edu.tw/~wujsh/

  2. Contents Background and Preview · Communication Process (Sender, receiver, point- to-point, broadcasting) · Communication Networks (packet switching, circuit switching) (layer architecture) · Channels (AWGN, fading channel) · Modulation Process (C.W. modulation, PCM, Passband digital Trans.) · Analog and Digital Communications · A Digital Communication Problem ( ) · Historical Notes

  3. Chapter 1 Random Process · Mathematical Definition of a Random Process · Stationary Processes · Mean , Correlation , and Covariance Functions · Ergodic Processes · Linear Time-Invariant Filter ( System ) · Power Spectral Density ( PSD ) · Gaussian Process · Noise · Narrowband Noise · Representation of Narrowband Noise (I,Q, Envelope and phase ) · Sinusoidal Wave Plus Narrowband Noise

  4. Chapter 2 Continuous-Wave ( CW ) Modulation · Amplitude Modulation (AM) · Linear Modulation Schemes( ) (DSB-SC, SSB, VSB) · Frequency–Division Multiplexing ( FDM ) · Angle Modulation · Frequency Modulation ( FM ) · Nonlinear Effects in FM Systems · Superheterodyne Receiver (RF, Mixer, IF, detection, estimation) · Noise in CW Systems ( Coherent Detection and Envelope Detection in AM , Filtering in FM )

  5. Chapter 3 Pulse Modulation · Sampling Process (sampling theorem, ) · Pulse-Amplitude Modulation (PAM) · Other Forms of Pulse Modulation (PPM,PDM) · Bandwidth-Noise Trade-off · Quantization (preparation for digitization) · Pulse-Code Modulation (PCM) · Noise in PCM System (Channel noise, Quantization noise) · Time-Division Multiplexing (TDM) · Virtues , Limitations , and Modifications of PCM · Delta Modulation (±Δ) · Linear Prediction · Differential PCM (DPCM) , Adaptive DPCM (ADPCM)

  6. Chapter 4 Baseband Pulse Transmission · Matched Filter (matched to the signal) · Bit Error Rate ( BER ) Due to Noise · Intersymbol Interference ( ISI ) · Nyquist’s Criterion for Distortionless Baseband Binary Transmission (No ISI 沒有noise時) · Correlative-Level Coding ( Partial-Response) (N bits/symbol) · Adaptive Equalization

  7. Chapter 5 Signal-Space Analysis · Geometric Representation of Signals (Vector representation) · Conversion of the Continuous AWGN Channel into a Vector Channel · Likelihood Functions · Coherent Detection of Signal in Noise: Maximum Likelihood Decoding · Correlation Receiver · Probability of Error (BER)

  8. Chapter 6 Passband Transmission · Passband Transmission Model( · Coherent Phase-Shift Keying (PSK) · Quadrature-Amplitude Modulation (QAM) · Coherent Frequency-Shift Keying (FSK) · Detection of Signals with Unknown Phase (Non-coherent detection) · Noncoherent Orthogonal Modulation (Orthogonal Frequency Carriers) · Noncoherent Binary FSK · Comparison of Digital Modulation Schemes Using a Single Carrier

  9. Background And Preview 0.1 The Communication Process (Statistical) - Communication anywhere , anytime , involving transmission of information from one point to other places, (Broadcasting , Point-to-point) generation and description of signals, encoding, transmission, decoding and recovering.

  10. 0.2 Primary Communication Resources • transmitted power (power limited) • channel bandwidth (bandwidth limited) Due to noise , the ratio of the average signal power to the average noise power (SNR) is an important system parameter (in terms dB) , but not the only one (ISI, jitter) (error free second)

  11. 0.3 Sources of Information - Speech production , propagation , perception - Music melodic structure 旋律 harmonic structure 音調和諧 - Picture

  12. 0.4 Communication Networks

  13. - Open Systems Interconnection (OSI) Reference Model

  14. Internet A specific worldwide internet. A machine is on the Internet if it runs the TCP/IP protocol stack , has an IP address, and has the ability to send and receive IP packets to all the other machines on the Internet. The network technology is decoupled from the applications. · The applications are carried out independently of the technology · The network technology is capable of evolving without affecting the applications

  15. Broadband Networks Driving forces : demand for new services(video , multimedia ) and enabling technologies (optical fibers, packet digital switches ) ATM, SONET, SDH, PDH (Plesiochronous Digital Hierarchy )

  16. 0.5 Communication Channels - Guided Propagation a. Telephone Channels (twisted pair of wires)

  17. b.Coaxial Channel ( 50Ω ,75Ω ) c.Optical Fiber (single mode, multimode) 125 μm cladding 8 μm core ·Enormous potential bandwidth (70 x 1012 Hz ) ·Low transmission losses (0.158 db/km at 1.55μm ) ·Immunity to electromagnetic interference ·Small size and weight · Ruggedness and flexibility

  18. d. Wireless broadcast channels (AM,FM,TV) superheterodyne receivers e. Mobile radio channels multipath fading , dispersive f. Satellite channels (geosynchronous , low orbit) Broad-area coverage, reliable transmission lines,wide transmission bandwidth Classification of channels • Linear, nonlinear (e.g. satellite) (Power Amplifier) • Time invariant, time variant • Bandwidth limited (e.g. telephone channel) Power limited (e.g. satellite)

  19. 0.6 Modulation and Demodulation Processes a. Continuous-Wave (CW) modulation - amplitude modulation ( AM ) - frequency modulation ( FM ) - phase modulation ( PM ) b. Pulse modulation - pulse-amplitude modulation ( PAM ) - pulse-duration modulation ( PDM ) - pulse-positive modulation ( PPM )

  20. c. Pulse-code modulation ( PCM,digital ) - Sampling , quantization , coding - Properties of PCM · Robustness in noisy environments · Flexible operation · Integration of diverse sources into a common format (0.1) · Security of information 0.7 Multiplexing a. Frequency-division multiplexing ( FDM ) b. Time-division multiplexing ( TDM ) c. Code-division multiplexing ( CDM )

  21. 0.8 Analog and Digital Types of Communications a. Guidelines of designing the transmitter and the receiver - Encode/modulate the signal,transmit it over the channel and produce an ’’estimate” of the original signal at the receiver output that satisfies the requirements - Do all of this at an affordable cost b. The design of an analog communication system is conceptually simple but difficult to implement

  22. c. The digital communication system - Source encoder-decoder (remove redundant information) - Channel encoder-decoder (controlled redundancy, FEC, Error detection) - Modulator-demodulator

  23. 0.9 Shannon’s Information Capacity Theorem C = B· log2(1+SNR) b/s (1) C : Channel capacity B : Channel bandwidth SNR : Signal-to-noise ratio

  24. Efficiency of a digital communication system = R/C R: actual signaling rate Equation 1 provides a basis for the trade-off between B and SNR and an idealized framework for comparing modulation schemes

  25. 0.10 A Digital Communication Problem (band pass)

  26. (2) The random signal m(t) consists of symbols 1 and 0 with duration T. For PSK, s(t)= -Ac cos(2fct+m(t) ) where 0 t T , the carrier frequency fc= , k=integer, Ac is the amplitude. Assume the channel is distortionless but noising , the received signal x(t) is x(t)=s(t)+w(t) (3) where w(t) is the additive channel noise (e.g., AWGN). The output of the correlator is Decision rule : If yT 0 output symbol=1 yT 0 output symbol=0 (4) for m (t) =1 (5) = for m (t) = 0

  27. Important Issues a. time-bandwidth product of a pulse signal is constant, e.g., the bandwidth of a rectangular pulse of duration T is inversely proportional to T (Fourier Transform) b. frequency shifting (Fourier Transform) ( shifts spectral to ± ) c. signal rate on d. justification of the receiver structure e. relation between wT and w(t) ( ) f. BER(modulation,channel,noise,demodulation) g. choice of modulation schemes, coding, synchronization

  28. 0.11 Historical Notes 1837 Morse, Telegraph , Morse Code 1875 Baudot, Fixed length code (five elements) 1864 Maxwell, EM theory 1887 Hertz, Radio wave 1894 Lodge, Wireless communication 1901 Marconi, Long distance radio communication 1875 Bell, Telephone 1897 Stowger, Step-by-step switch 1904 Fleming, Vacuum tube diode 1906 Lee de Forest, Vacuum tube triode

  29. 1918 Armstrong ,Superheterdyne radio receiver 1936 Armstrong, Frequency modulation 1928 Nyquist, Nyquist’s criteria (No ISI) 1937 Reeves, Pulse-code modulation ( PCM ) 1947 Kotel’nikov, Representation of signals 1948 Shannon, Information Theory 1949 Golay, Error-correcting codes 1950 Hamming, Hamming codes 1948 Brattain, Bardeen, and Schockley,Transistor 1958 Noyce, IC 1962 Bell Labs, TI carrier system 1946 Univ. of Penn, Computer 1976 ARPA, Computer networks (Packet switching) 1955 Pierce, Satellite communication 1966 K.C. Kao and Hockham, Fibers

More Related