Wireless Communication: Foundations and Frontiers

1. Wireless Communication:Foundations and Frontiers Dr. Dennis Martinez Vice President, Technology M/A-COM Wireless Systems

2. How many of these wireless devices will you use today? • Cell phone • Cordless phone • Wireless LAN • AM/FM radio • Television • Garage door opener • Remote control device • Automobile remote key entry

3. How We Experience the World Around Us • The 5 Senses – Taste, Smell, Feel, Hearing, Sight • We have learned how to remotely experience only 2 of them – why? • Wireless communication is now one of our primary means of delivering this remote experience • Started with broadcast radio and television – one-way experience • Today cell phones and wireless LAN provide for feature-rich two-way communication

4. Our Remote Experience • Remote experience involves communication • Communication involves • A source that provides the content • A medium over which the content is delivered • A destination that receives the content

5. Wireless Communication Key Events • 1864 Maxwell unifies electromagnetic theory • 1895 Marconi sends wireless messages over 1 mile • 1907 First wireless voice transmissions • 1927 First wireless television transmission demonstrated • 1939 FM radio broadcasts begin • 1947 Shockley et. al. invent the transistor • 1948 Shannon formalizes digital communication theory • 1959 Invention of the Integrated Circuit • 1976 First satellite-to-the-home television service • 1978 First trial cellular telephone system operates in Chicago • 1997 802.11 Wireless LAN standard is created • 1998 Satellite radio services began

6. Electromagnetic Theory • Maxwell’s Equations – (1864) • Faraday’s law of induction: • Electric fields are induced by time varying magnetic fields • Ampere’s law: • Magnetic fields are induced by time varying electric fields • Like a perpetual motion machine, Electric and magnetic fields perpetuate each other as an electromagnetic wave • These waves travel at the speed of light and carry energy from one point to another James Clerk Maxwell Scottish physicist and mathematician 1831-1879

7. N S Faraday’s Law • Time varying magnetic fields induce electric fields • Today this is our primary means of generating electricity • The electric field is measured by the meter

8. Ampere’s Law • Static currents induce magnetic fields • This is how electromagnets work • Time varying electric fields also induce magnetic fields Current Magnetic Field + + + + ~ ~ - - - - Electric Field Magnetic Field

9. Electromagnetic Waves • Generated by accelerating electrons on the surface of an antenna • Electric and Magnetic fields are perpendicular to each other and to the direction of motion

10. Electromagnetic Propagation • Radio waves propagate outwards from the source • Since they transmit energy, they obey the conservation of energy principle • When radio waves encounter matter, energy can be absorbed, reflected and scattered In free space energy density (energy per unit area) decays as 1/r2 Antenna’s have apertures that capture this energy r Surface area = 4r2 In the real environment energy density decays much faster than 1/r2

11. At the turn of the 20th century • Devices existed that could generate and receive radio waves • These radio waves could be modulated by keying transmitters on and off – Morse Code • Shortly after, Amplitude and Frequency Modulation was possible to transmit sound and pictures • By 1950 Analog radio and television was widely available • This laid the ground work for the advent of digital communication

12. Information Theory • Mathematical Theory of Communication (1948) • Forms the basis for modern digital communication • Information = Randomness • Entropy is a measure of randomness • Information Sources & Source Coding • Information sources are characterized by their Entropy • Source Coding removes the redundancy of an information source • Channel Capacity • Bandwidth and noise only limit the rate that we can communicate, not the accuracy • Rate Distortion • Coding with a fidelity criterion Claude Shannon Research Mathematician 1916-2001 Channel Introduces Noise Information Source Source Coder Waveform Coder Receiver Source Decoder Waveforms Symbols Symbols

13. Source Coding Example • Lossless coding • Doesn’t depend on information source or content • Achieve limited compression • Coding with a fidelity critieron • Achieve much greater compression • Requires a lot of domain knowledge about source and the perception of distortion 213 K .zip File 1.6 to 1 Lossless Coding 11 to 1 Coding with loss 352 K .bmp File 24 Bit Color, 300 x 400 Resolution 32 K .jpg File

14. Waveform Coding • How we turn bits into radio waves • Modulators take groups of bits and select an appropriate waveform to transmit • Demodulators compare the received waveform and decide which waveform was transmitted and hence the bits that were sent Compare Transmitted Waveform 00 10 00 11 01 01 01 01 2-bit Symbols 10 T Baud Rate 2 bits/T 11

15. Distance and Data Rate • A radio link has a useable range • Towers have a usable coverage area • Handoff occurs as radios leave one coverage area and enter another Cell Boundaries Coverage Area Usable Range Noise limit Received Signal Power Distance Types of Noise Thermal Man-Made Atmospheric Solar Cosmic Quantum Handoff

16. Computers & Semiconductors • 1948 William Shockley leads team that invents the transistor • 1958-1959 Jack Kilby and Robert Noyce independently invent the Integrated Circuit • Enabling wireless communication • General purpose processors • Digital signal processors • Microcontrollers • Application Specific IC’s • Radio Frequency IC’s • Many others William Shockley Physicist 1910 - 1989 Jack Kilby Engineer 1923 - 2005 Robert Noyce Physicist 1927 - 1990

17. Processor Speed (MIPS) 1000 100 10 1 0.1 0.01 1970 1975 1980 1985 1990 2000 Chip Density Transistors per die) 100,000,000 10,000,000 1,000,000 100,000 10,000 1000 100 10 1 1970 1975 1980 1985 1990 2000 Semiconductor Advances • Processor Speed • More complex coding and waveform schemes = more bits/sec/Hz • Larger bandwidths • Chip Density • Reduces the size • Increases battery life • Reduces the cost

18. Technology Frontiers • Wireless Technology • Cognitive Radio • Radios that sense & adapt to the RF environment • Software defined radio • Replacing analog & RF with digital processors • Broadband • Moving all multi-media services to packet switching • Ubiquitous networks • Cordless Phones  Cell Phones • WiFi Wireless LAN  WiMax Wireless Wide Area Networks • Enabling Technologies • Information & Software • Networks & protocols • Semiconductors & Computing • Materials, circuits, architectures, & systems • Quantum computing, bio-computing, DNA computers • Energy Sources (Batteries)

19. Emerging Technologies for Wide Area Broadband • Network Processing • 900 MHz 32 Bit RISC Processor • (4) 900 MHz Micro-engines • (2) 200 MHz Network Processors • Digital Signal Processing • (308) 160 MHz RISC Processors • (14) 160 MHz Function Accelerators • 197 GIPS • RF Processing • 4.9 GHz Transceiver • 5 MHz channels • 256 subcarriers • 13 Mbps data rate

20. Challenges - Spectrum • Spectrum – A scarce natural resource The band from 100 MHz to 10 GHz is the most important for wireless communication today

21. Application Frontiers • Applications – Increasing our experience of the world around us • Increasing the intensity of our experience • From Hi-FI to High Definition • Increasing the interactivity of our experience • From broadcast to n-way • Increasing the mobility of our experience • The ubiquitous network AM Radio – 10 kHz FM Radio – 200 kHz Television – 6 MHz Which picture do you prefer? Why?

22. Thank you!Questions?