EE558 - Digital Communications

Transcription

1 EE558 - Digial Communicaions Lecure 1: Inroducion & Overview Dr. Duy Nguyen

2 Ouline 1 Course Informaion 2 Inroducion o Digial Communicaions Course Informaion 2

3 Adminisraion Hours and Locaion Lecures: TTH 12:3 13:45 Locaion: SH-127 Office hours: Tue 14: 16: or by appoinmen Course webpage: hp://engineering.sdsu.edu/ nguyen/ee558/index.hml Insrucor: Dr. Duy Nguyen Office: ENG-48 Phone: (619) Webpage: hp://engineering.sdsu.edu/ nguyen Grader: Ms.Srilakshmi Alla Course Informaion 3

4 Syllabus Prerequisie EE 458 Analog and Pulse Communicaion Sysems Knowledge of MATLAB programming References 1. B. Sklar, Digial Communicaions: Fundamenals and Applicaions, 2nd Ed., Prenice Hall, J. Proakis, Digial Communicaions, 4h Ed., McGraw-Hill, 2. Homeworks: Bi-weekly, Toal: 7 (6 bes will be chosen). Lae submission: maximum 1 day, 2% score deduced Assessmens: only exbooks, slides and lecure noes are allowed in Quizzes and Exams Homeworks: 2% 3 Quizzes: 15% (25-minue each) 2 Miderm Exams: 3% (1-hour and 15-minue each) Final Exam: 35% (2-hour) Course Informaion 4

5 Syllabus Week Day Task Week Day Task 1 TU Firs day of class 9 TU Aug 29 TH Oc 24 TH Quiz 2 2 TU HW1 ou 1 TU HW5 ou, HW4 due Sep 5 TH Oc 31 TH 3 TU 11 TU Sep 12 TH Nov 7 TH Miderm Exam 2 4 TU HW2 ou, HW1 due 12 TU HW6 ou, HW5 due Sep 19 TH Nov 14 TH 5 TU 13 TU Sep 26 TH Quiz 1 Nov 21 TH Thanksgiving 6 TU HW3 ou, HW2 due 14 TU HW7 ou, HW6 due Oc 3 TH Nov 28 TH Quiz 3 7 TU 15 TU Oc 1 TH Miderm Exam 1 Dec 5 TH 8 TU HW4 ou, HW3 due 16 TU HW7 due Oc 17 TH Dec 12 TH Course Summary Course Informaion 5

6 Topics o Cover Relaed Background Signals and sysems Probabiliy and random processes Sampling and quanizaion echniques Noise figures and noise emperaure of sysems Communicaion link analysis and link budges Baseband binary modulaion echniques Opimum receiver design and performance Communicaion over band-limied channels (if ime permis) Equalizaion and muli-carrier ransmission (if ime permis) Course Informaion 6

7 Ouline 1 Course Informaion 2 Inroducion o Digial Communicaions Inroducion o Digial Communicaions 7

8 Analog and Digial Ampliude Modulaions Analog message AM signal Digial message BASK signal Inroducion o Digial Communicaions 8

9 Wha is Digial Communicaion? x() x() (a) (b) x() x() T s T s (c) (d) Inroducion o Digial Communicaions 9

10 Transmied AM Received AM Transmied BASK Received BASK 1 Why Digial Communicaions? Inroducion o Digial Communicaions 1

11 Transmied AM Received AM Transmied BASK Received BASK 1 Why Digial Communicaions? Inroducion o Digial Communicaions 11

12 Regeneraive Repeaer in Digial Communicaions Original pulse Some disorion Degraded Severely degraded Regeneraed Propagaion disance Digial communicaions: Transmied signals belong o a finie se of waveforms The disored signal can be recovered o is ideal shape, hence removing all he noise Analog communicaions: Transmied signals are analog waveforms, which can ake infinie variey of shapes Once he analog signal is disored, he disorion canno be removed Inroducion o Digial Communicaions 12

13 Block Diagram of a Communicaion Sysem Synchronizaion Source (User) Transmier Channel Receiver Sink (User) (a) Transmier Receiver Source Encoder Channel Encoder Modulaor Demodulaor Channel Decoder Source Decoder Noe: Synchronizaion block is only presen in a digial sysem (b) Inroducion o Digial Communicaions 13

14 Advanages: Digial vs. Analog Digial signals are much easier o be regeneraed Digial circuis are less subjec o disorion and inerference Digial circuis are more reliable and can be produced a a lower cos han analog circuis I is more flexible o implemen digial hardware han analog hardware Digial signals are beneficial from digial signal processing (DSP) echniques Disadvanages: Heavy signal processing Synchronizaion is crucial Larger ransmission bandwidh Non-graceful degradaion Inroducion o Digial Communicaions 14

15 Digial Communicaions Communicaion Sysem Source of informaion Message signal Transmier Transmied signal Channel Receiver Received signal Esimae of message signal User of informaion The main objecive of a communicaion sysem is he ransfer of informaion over a channel Digial communicaion: ransmied signals belong o a finie se of waveforms Esimae of message signal: decision-making regarding he digial meaning of ha waveform Performance is usually expressed as bi-error-rae (BER) Inroducion o Digial Communicaions 15

16 Terminologies Informaion source Characer and alphabe Bi and bi sream Symbol Baud Digial waveform Daa rae BER Inroducion o Digial Communicaions 16