Carrier Aggregation
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2018/3/1 EE140 Introduction to Communication Systems Lecture 1 Instructor: Prof. Xiliang Luo ShanghaiTech University, Spring 2018 1 Contents • Course information • Introduction to communication systems 2 1 2018/3/1 Course Information (I) • Course title: – Introduction to Communication Systems • Course pre-requisites: – Probability; Linear algebra; Signal and systems •Objective – Establish basic knowledge about digital signaling, coding, digital transmission and reception • Reference textbook 1. S. Haykin, Communication Systems, 5th edition, Wiley. 2. David Tse, Fundamentals of Wireless Communication, Cambridge University Press. 3. 樊昌信，通信原理，第7版，国防工业出版社 3 Course Information (II) • Instructor: – Prof. Xiliang Luo ([email protected]) •TA: – Xuanfeng Li([email protected]) • Office hours – Tuesday, Thursday 10:30~12:00pm – SIST 1C-403A • Rules in classroom – Questions, discussions and suggestions are always welcome – Turn-off your mobile phones, no food in classroom 4 2 2018/3/1 Course Information (III) •Grading – Homework: (biweekly) 40% – Midterm: 30% – Final: 30% • Homework: – Biweekly, due before Tuesday classes (hard deadline) • Honor code: – Plagiarism, zero tolerance •Website http://sist.shanghaitech.edu.cn/faculty/luoxl/class/2018Spr_ EE140/IntroComm.htm 5 Course Information (IV) • Syllabus (first half) Content Hours Introduction 2 Deterministic signals and spectra (waveform, FT, 3 Spectra) Random process and noises 5 Analog modulation 4 Quantization (ADC, DTFT, Aliasing) 6 Source coding (information theory) 8 Review 1 2 6 3 2018/3/1 Course Information (V) • Syllabus (second half) Content Hours Channel (response, ISI, est. and equalization) 4 Digital modulation 4 Detection 6 Coding 4 Multiple Access 2 Wireless communications 8 Review 2 2 7 Course Information (VI) • Some of the slides information was taken from our colleagues and from the internet, we would like to declare and acknowledge here – Fundamentals of Communication Systems, Second Edition, John G. Proakis, Masoud Salehi, Pearson Prentice Hall, 2005 – Digital Communications, 5th Edition, John G. Proakis, Masoud Salehi, McGraw-Hill, 2007 – Course slides by R. Gallager, Massachusetts Institute of Technology (6.450 Principles of Digital Communications I, Fall 2006. MIT OpenCourseWare) – Course slides by Meixia Tao, Shanghai Jiaotong University (ES311 通信原理 http://iwct.sjtu.edu.cn/personal/mxtao/teaching1.html) – Course slides by Wei Chen, Tsinghua University (通信原理、高等数字通信) 8 4 2018/3/1 Before we start • Some suggestions – Keep your ambition in mind and be active in class – Remember the concepts – Know their physical meanings and the relationships – Pay attention to the assumptions and conditions – Grasp all the examples given in the lecture notes – Understand the homework problems and solutions – Read references when necessary – Methods are more important than results – Learn to evaluate others’ work 9 Contents • Course information • Introduction to communication systems – What is communication? – History of communication systems – Basic architecture – Fundamental questions 10 5 2018/3/1 What is Communication? • Communication – From Wikipedia – from Latin commūnicāre, meaning "to share" – the act of conveying intended meanings from one entity or group to another through the use of mutually understood signs and semiotic rules 11 Examples of Modern Communication Systems 12 6 2018/3/1 Contents • Course information • Introduction to communication systems – What is communication? – History of communication systems – Basic architecture – Fundamental questions 13 Historical Review • 1791: Semaphore (Claude Chappe) Napoleon’s secret weapon 14 7 2018/3/1 Historical Review • 1838: telegraph (Samuel Morse) 15 Historical Review • 1870: telegraph cable Hong Kong, 20 October 1870 Shanghai, 8 December 1870 16 8 2018/3/1 Historical Review • 1910: telegraph station Shanghai, 1910 Shanghai, 1930 17 Historical Review • 1876: Telephone (Alexander Bell) 18 9 2018/3/1 Historical Review • 1895: Radio (Guglielmo Marconi) 1909 19 Historical Review • 1928: Sampling Theorem (Harry Nyquist) – "Certain topics in telegraph transmission theory", Trans. AIEE, vol. 47, pp.617–644, Apr. 1928 Continuous- Discrete- time time 20 10 2018/3/1 Historical Review • 1948: Information Theory (Claude Shannon) – “A Mathematical Theory of Communication”, Bell Syst. Tech. Journal, V27, 1948, 379-423, 623-656 – Provide fundamental limits of source compression rate and channel transmission rate Analog communication Digital communication 21 Historical Review • 1966: Optical Fiber (Charles Kuen Kao) – PhD Thesis: Quasi-Optical Waveguides – 90% of all voice and data traffic in the world is now carried by optical fibers 2009 22 11 2018/3/1 Contents • Course information • Introduction to communication systems – What is communication? – History of communication systems – Basic architecture – Fundamental questions 23 Architecture of a (Digital) Communication System Transmitter A/D Source Channel Source Modulator converter encoder encoder Absent if source is Noise Channel digital Source Channel User D/A Detector converter decoder decoder Receiver 24 12 2018/3/1 Standardized Interfaces and Layering •A standardized Input interface allows Input Input ... Input module i Module i‐1 module 1 the user or equipment on one Interface Interface side of the i to i‐1 i‐1 to i‐2 interface to ignore all details about Layer i Layer i‐1 Layer 1 channel the other side of the interface Interface Interface except for certain i‐1 to i i‐2 to i‐1 specified interface output Input Input Input characteristics. ... module i Module i‐1 module 1 • The idea of layering in communication systems is to break up communication functions into a string of separate layers. Each layer consists of an input module at the input end of a communication system and a ‘peer’ output module at the other end. 25 Source Information • Message: generated by source • Information: the unpredictable part in a message • Signal: a function that conveys information about the behavior or attributes of some phenomenon Analog signal vs. digital signal Transducer: convert sensing signal to electric signal 26 13 2018/3/1 Source Coding • Source coding (data compression): to reduce space for the data stream. – Sampling (discretize) – Quantization (discretize in amplitude) – Source coding (bits or symbols) • Source coding example – Speech coding • human voice, 20 Hz~20 kHz, quantization raw data rate >1 Mbps • Standard PCM coding, 3.4kbps 27 Encryption (Not Shown in the Diagram) • Encryption: to encrypt information for security purpose. • Cryptography example: Caesar cipher – ABCDEFGHIJKLMNOPQRSTUVWXYZ –Key = 3 – DEFGHIJKLMNOPQRSTUVWXYZABC •Example – Plaintext: OLINCOLLEGE – Ciphertext: ROLQFROOHJH – Decryption: Shift backwards by KEY = 3 28 14 2018/3/1 Channel Coding • Channel coding (error control): to encode a signal so that error occurred can be detected and possibly corrected. – Protection is achieved by adding redundancy! • Source coding example: – Repetition code: (3, 1) repetition code • Message bits: 101001 •Coded bits: 111000111000000111 • Decoder: majority logic Wireless comm. (Repetition, RS, CC, LDPC, Turbo…) 29 Modulation • Modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted. • Example: baseband message signal passband RF signal 30 15 2018/3/1 Channel • Channel: a transmission medium used to convey information • Common characteristics – Attenuation – Distortion –Noise – Wireless channels • Multipath, fading 31 Channel Model • AWGN channel • Linear channel 32 16 2018/3/1 Noise •Noise – random and unpredictable electrical signals produced by natural processes both internal and external to the system. – Should be modeled probabilistically. The noise is a priori unknown, but can be expected to behave in statistically predictable ways. – Additive, uncorrelated with the input signal – Multiplicative, correlated with the input signal • Distortion – waveform perturbation caused by imperfect response of the system to the transmitted signal itself. • Interference – contamination by extraneous signals from other transmitters, switching circuits, etc. 33 Analog vs. Digital •Robustnessto channel noise and external Interference •Securityof information during its transmission from source to destination •Integrationof diverse sources information into a common format • Low cost DSP chips by very cheap VLSI designs 34 17 2018/3/1 Duplex Transmission •Simplex – one-way transmission only, e.g. broadcast systems • Half-duplex – two-way transmission, but the common channel is alternately used for transmission in opposite direction, e.g. interphone systems installed on taxies • Full-duplex – simultaneous two-way transmission, e.g. public telephone systems 35 Multiplexing • Multiplexing – multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share an expensive resource. •Type – Frequency-division –Time-division – Code-division – Space-division – Polarization-division (e.g., in optical fiber) – Orbital angular momentum (OAM, 轨道角动量多址，光子纠缠，2013) 36 18 2018/3/1 Contents • Course information • Introduction to communication systems – What is communication? – History of communication systems – Basic architecture – Fundamental questions 37 Course Objective • We focus on the fundamental system aspects of modern digital communication systems – provide analytical tools for determining the performance of particular systems