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

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

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

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

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

Electromagnetic Theory Maxwell’s Equations – (1864) 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

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

Ampere’s Law Static currents induce magnetic fields Static currents induce magnetic fields –This is how electromagnets work Time varying electric fields also induce magnetic fields Time varying electric fields also induce magnetic fields ~~ Electric Field Magnetic Field Current Magnetic Field ~~

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

Electromagnetic Propagation Radio waves propagate outwards from the source Radio waves propagate outwards from the source Since they transmit energy, they obey the conservation of energy principle Since they transmit energy, they obey the conservation of energy principle When radio waves encounter matter, energy can be absorbed, reflected and scattered When radio waves encounter matter, energy can be absorbed, reflected and scattered r Surface area = 4  r 2 In free space energy density (energy per unit area) decays as 1/r 2 In the real environment energy density decays much faster than 1/r 2 Antenna’s have apertures that capture this energy

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

Information Theory Mathematical Theory of Communication (1948) 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 Source Coder Waveform Coder Receiver Source Decoder Information Source Symbols Channel Introduces Noise Waveforms Symbols

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

Compare Waveform Coding How we turn bits into radio waves 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 Transmitted Waveform 2-bit Symbols T Baud Rate 2 bits/T

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

Computers & Semiconductors 1948 William Shockley leads team that invents the transistor 1948 William Shockley leads team that invents the transistor Jack Kilby and Robert Noyce independently invent the Integrated Circuit Jack Kilby and Robert Noyce independently invent the Integrated Circuit Enabling wireless communication Enabling wireless communication –General purpose processors –Digital signal processors –Microcontrollers –Application Specific IC’s –Radio Frequency IC’s –Many others William Shockley Physicist Jack Kilby Engineer Robert Noyce Physicist

Semiconductor Advances Processor Speed (MIPS) , ,000 1,000,000 10,000, ,000,000 Chip Density Transistors per die) Processor Speed Processor Speed –More complex coding and waveform schemes = more bits/sec/Hz –Larger bandwidths Chip Density Chip Density –Reduces the size –Increases battery life –Reduces the cost

Technology Frontiers Wireless Technology 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 Enabling Technologies –Information & Software  Networks & protocols –Semiconductors & Computing  Materials, circuits, architectures, & systems  Quantum computing, bio-computing, DNA computers –Energy Sources (Batteries)

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

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

Application Frontiers Applications – Increasing our experience of the world around us 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 Which picture do you prefer? Why? AM Radio – 10 kHz FM Radio – 200 kHz Television – 6 MHz

Thank you! Questions?