EC Talk. Asst. Prof. Dr. Prapun Suksompong.

Transcription

1 EC Talk Asst. Prof. Dr. Prapun Suksompong 1 Office Hours: (BKD ) Wednesday 9:30-11:30 Wednesday 16:00-17:00 Thursday 14:40-16:00

2 Outline Courses ECS 452: Digital Communication Systems ECS 455: Mobile Communications ECS 456, 477 Senior projects 2

3 Courses: General Information Annotated lecture notes and slides from previous years are available at prapun.com Tentative grading policy Assignments 5% Class Participation and Quizzes 15% Midterm Examination 40% Final Examination 40% No project 3

4 Mobile Communications ECS 455 Asst. Prof. Dr. Prapun Suksompong Course Introduction 4 Office Hours: (BKD ) Wednesday 9:30-11:30 Wednesday 16:00-17:00 Thursday 14:40-16:00

5 Marty Cooper: Cellphone Inventor 1973 Motorola DynaTAC prototype Weighed nearly two kilos Cost approximately $1 million for Motorola to produce. 20 minutes battery life Not a problem because you could not hold it up for twenty minutes; it was so heavy. [ 5

6 iphone 5s Teardown Qualcomm MDM9615M LTE Modem 6 Qualcomm WTR1605L LTE/HSPA+/CDMA2K/TDSCDMA/EDGE/GPS transceiver

7 iphone 5s Spec Cellular: GSM 7

8 ECS455: Topics 1. Wireless Communications: Problems and Solutions. 2. Cellular Communications: Motivation and Analysis. 3. Multiple Access Schemes: How can many users share communication resources? 4. Spread Spectrum Communications including CDMA (2G- 3G) 5. OFDM systems (3.5-4G) 6. Communication techniques in GSM, GPRS, EDGE, UMTS (W-CDMA), WiMAX (OFDMA), LTE (SC-FDMA) 8

9 Digital Communication Systems ECS 452 Asst. Prof. Dr. Prapun Suksompong Course Introduction 9 Office Hours: (BKD ) Wednesday 9:30-11:30 Wednesday 16:00-17:00 Thursday 14:40-16:00

10 The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point. Shannon, Claude. A Mathematical Theory Of Communication. (1948) 10

11 Basic elements of communication Information Source Message Transmitter Transmitted Signal Channel Received Signal Receiver Message Destination Noise Source 11

12 Binary Interface Digital Communication Binary data stream (sequence of data) without meaning (from channel viewpoint). Waveform sequence symbols bits Take the bits from one place to another. Input Source Encoder Know the probabilistic structure of the input source Channel Encoder Channel Output Source Decoder Channel Decoder + noise & interference 12 This is the major layering of all digital communication systems.

13 General Ideas Extension of Principles of Communications (ECS332) and Probability and Random Processes (ECS315) Focus more on performance analysis (bit error rates), optimal receivers, and limits (information theoretic capacity). 13

14 ECS 452 Topics Random noise process Optimal Receivers Digital modulation techniques and their performance Source coding and entropy Information theory (capacity) Channel coding Wireless communications MIMO: Multiple-Input Multiple-Output OFDM: Orthogonal-Frequency Division Multiplexing 14

15 ECS456: Optical Communication Prerequisite: ECS233 (Electromagnetics) Description: Characteristics of lightwave propagation in optical fibers. Types of optical fibers. Optical transmitters and receivers. Optical filters and amplifiers. Optical components: optical divider and combiner, coupler, lens switches. Optical communication systems. Coding, multiplexing, demultiplexing, switching, and wavelength conversion. Optical network architectures. Type: Lecture 80% Project 20% Note: Good for better job opportunity 15

16 ECS477 Signal Processing for Communication Systems 16 Prerequisite: ECS472 (DSP) Description: Project-Based Speech coding and decoding image coding and decoding filter banks and multi-rate signal processing channel estimation/ equalization/ synchronization array processing and power spectral estimation adaptive filtering Type: Lecture 50% Project 50% Note: MATLAB programming intensive, good for graduate study.

17 Senior Projects Assoc. Prof. Dr. Chalie Charoenlarpnopparut Asst. Prof. Dr. Prapun Suksompong 17

18 At a glance MATLAB Simulations Wireless Communications 1. OFDM, MIMO, Multi-User Techniques 2. Visible light communication (VLC) GHz Communication 4. Game theory in wireless and communication networks 5. RFID Localization 18

19 19 WiFi: IEEE

20 : PHY Data Rates

21 Wireless Digital Comm. System Transmitter (Tx) Receiver (Rx) Encoder Decoder Wireless Channel (SISO) 21

22 MIMO: n (Multiple Input Multiple Output) Encoder x Wireless Channel (MIMO) y Decoder y Hx z 22 Channel Matrix Noise

23 MIMO/SDM Advantage: Space-division multiplexing (SDM) Transmit multiple independent data streams or spatial streams on different antennas Encoder x y Decoder Problem: Solution: Interference among transmitting antennas Pre-process (pre-code) the transmitted signals 23 (SU-MIMO)

24 agn: 54 Mb/s to 600 Mb/s

25 ac PHY Data Rates

26 Multiple Users: Downlink MU-MIMO (in the bedroom) To: STA Encoder Encoder To: STA2 s s 1 2 x 1 y 2 y STA1 STA2 (in the living room) (2,2) System y y H H x x z z

27 At a glance MATLAB Simulations Wireless Communications 1. OFDM, MIMO, Multi-User Techniques 2. Visible light communication (VLC) GHz Communication 4. Game theory in wireless and communication networks 5. RFID Localization 27

28 [ Radio-frequency spectrum Commercially exploited bands m/s c f Frequency Wavelength Note that the freq. bands are given in decades; the VHF band has 10 times as much frequency space as the HF band.

29 29

30 Thailand Freq. Allocations Chart 30

31 Thailand 2.1GHz Auction 4.5bn baht per license (freq chunk) 1 license (chunk) = 5 MHz (UL) + 5 MHz (DL) 450 million baht per MHz 30 million baht per MHz per year 31

32 Limitations/constraints of RF Communications Radio wave resource Limited (bandwidth), Scarce, Expensive, Regulated Capacity: We are simply running out of spectrum. Can t keep up with the demand of wireless data transmissions Interference with other products/systems Have to switch off your mobile phone during flights. Mobile phones and WiFi s are undesirable in certain parts of hospitals, especially around MRI scanners and in operating rooms. Security Radio waves penetrate through walls. They can be intercepted. 32

33 33 י ה י או ר said, And God

34 VLC and LEDs Visible Light Spectrum (VLC) Widespread deployment of Light-Emitting Diodes (LEDs) for energy conservation in general lighting. Substitute of conventional incandescent and fluorescent lamp due to its lower power consumption, high efficiency and longer lifetime. Information can be modulated (at high-speed) into the instantaneous optical intensity. Provide a data channel in addition to the illumination, which is provided by the average signal level. Convergence of illumination and communications. VLC is now regarded as one of the most important green communication technologies. 34

35 VLC: Advantages Huge bandwidth 10,000 times larger than the radio waves spectrum. Unregulated, license-free operation. No licensing fees. High communication security. Easy to block. No interference with sensitive electronic systems. Safe Light has been around for many millions of years. It has created us, has created life, has created all the stuff of life. So it's inherently safe to use. Availability: the existing lighting infrastructure can be used Billions of light bulbs already installed. Low-cost front-end devices 35

36 36 Possible Applications

37 37 Possible Applications

38 At a glance MATLAB Simulations Wireless Communications 1. OFDM, MIMO, Multi-User Techniques 2. Visible light communication (VLC) GHz Communication 4. Game theory in wireless and communication networks 5. RFID Localization 38

39 60 GHz Wireless Communications Millimeter-wave (mm-wave) technology Unlicensed band One of the largest being allocated At least 5 GHz of continuous bandwidth worldwide Small form factor Can be conveniently integrated into consumer electronic products. Huge path loss Enables higher-frequency reuse in each indoor environment. 39

40 Cognitive radios: Motivation Back to radio-frequency spectrum Traditional Rule: Allow predetermined licensed users the right to transmit at given frequencies. Frequency bands were sold at auction, bringing considerable revenue to the government. Unlicensed users are regarded as harmful interference. Radio-frequency resources are not fully utilized There exists a large number of frequency bands that have considerable, and sometimes periodic, idle time intervals. For example, some TV stations do not work at night. Spectrum holes. 40

41 Cognitive radios A revolutionary communication paradigm that can utilize the existing wireless spectrum resources more efficiently. New Assumption: Users are intelligent and have the ability to observe, learn, and act to optimize their performance. Game theory has been recognized as an important tool in studying, modeling, and analyzing the cognitive interaction process. 41

42 Game Theory A branch of applied mathematics as well as of applied sciences. A formal framework with a set of mathematical tools To study the complex interactions analyze competition and cooperation among interdependent rational players (having individual selfinterests.) For more than half a century, game theory has led to revolutionary changes in economics. Three Nobel Prizes have been given in the economic sciences for work primarily in game theory. 42

43 RFID Positioning and Localization RFID = Radio Frequency Identification Want to link identification information to location The strength (and its changes) of RF signals could be utilized to locate and hence track objects. 43