From Analog to Software Defined: A History of the Radio Dr. Roland Kempter

Organization 1.The History of Radio Communication (incomplete) 2.Important Concepts: Filtering and Modulation 3.Background: Fourier Series Expansion 4.SIMULINK Demo 5.From Analog to Digital: Software Defined Radio 6.Programming Software Defined Radios

History of the Radio: James C. Maxwell : James Clerk Maxwell experiments with electromagnetic waves 1873: describes the propagation of electromagnetic waves in his paper “A Dynamical Theory of the Electromagnetic Field”

Wireless Radio Begins: Nikola Tesla 1893: Tesla gives public demonstration of wireless radio communication at St. Louis, Missouri. He describes in detail the principles of radio communication.

Wireless Radio Begins: Guglielmo Marconi and K. F. Braun 1896: G. Marconi is awarded a patent for radio: Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for 1897: Marconi establishes a radio station on the Isle of Wight (England) 1909: Marconi and Karl Ferdinand Braun win Nobel Prize in Physics for "contributions to the development of wireless telegraphy"

The History of the Radio

Better Sound Quality: FM Radio 1933: Edwin H. Armstrong patents FM radio (better quality than AM) 1940s: analog television transmissions start in North America and Europe.

The History of the Radio: the 21st century Internet radio Streaming Internet connection, no RF, IF, etc. Digital Audio Broadcasting (DAB) alternative to FM Satellite Radio XM Radio, Sirius Satellite Radio etc… Going from analog “payload” to digital “payload” However, radio itself still “analog” up to the decoder stage

The Fundamental Blocks in a Radio Move signal from RF to baseband (original signal) HOW? Remove frequency components HOW? Increase amplitude of signal multiply by constant Fourier Series Expansion

The Theory Behind Radio Technology: Fourier Series Jean Baptiste Joseph Fourier ( ) French mathematician and physicist Idea: “any” periodic function can be decomposed into an (infinite) sum of sines and cosines Fourier applied it to to problems of heat flow. 1824: gases in the atmosphere increase the surface temperature of the Earth. Fourier described the greenhouse effect!

Fourier Series describes the frequency content of periodic signals The Theory Behind Radio Technology: Fourier Series Different Time Domain signals have different harmonics (# and magnitude)

Example: Square Pulse, infinite # harmonics! With 250 harmonics: Gibbs phenomenon at discontinuity

Example: Sawtooth Wave

Example: Triangle Wave Some TD signals are suited better for transmission than others (less harmonics) Rect-wave: poor TD quality with 25 harmonics Sawtooth-wave: poor TD quality with 25 harmonics Triangle-wave: pretty good TD quality with 10 harmonics

Example: Fourier Transform Courtesy of Thomas F. Weiss Massachusetts Institute of Technology (right) logarithm of the magnitude of the FT of Fourier

What is Modulation Modulation: multiplication of baseband signal by a carrier wave Periodic signal can be expanded into series of sine + cosine  apply the above expression to every single one of those. Move arbitrary baseband signal into higher bands

Fundamental Blocks: Why is Modulation Necessary? At least 2 reasons: 1.different signals from different systems do not interfere Example: - broad band cable services - Public TV and Radio (wireless services) 2.move the payload signal to frequency where it can be transmitted most easily Problem: - signal attenuation in wires - free space signal attenuation

What is Filtering? Input Signal Filter Response Output Signal

Modulation and Demodulation Demodulate: x fc Modulate: x fc Filter:

Fourier Series: Continuous and Discrete Nice, but all of this was for continuous signals, What about discrete (digital) samples? Fourier works in digital, too: Discrete Fourier Transform

SIMULINK DEMO BPSK Radio

A Radio?

A Conventional Radio: all in Analog

New Paradigm: Software Defined Radio (SDR) RX Signals are digitized immediately after the LNA and then processed entirely in software, flexible TX vice versa Software Defined Radio:

A Radio!

SDR is Real! 23 November 2004: FCC approves the first SDR device in the United States. If radio changes behavior, no more re-approval necessary! VANU Inc., ANYWAVE cellular base station: HP proliant server, ADC/DAC, running Linux, can act as a GSM, CDMA and UMTS basestation through software updates

Programming Software Defined Radios: Download? Trinity: Operator, I need a pilot program for a V-212 helicopter! Various manufacturers of SDR boards  various flavors of hardware, on-the-fly reconfiguration requires specific configuration files! Infeasible! Different people have different brains! Different Hardware, simple downloads won’t work! But Describe to the target (brain) what to do: Give presentations instead of.exe files

Programming Software Defined Radios: Now and Future “Classical” way: VERILOG Problem: hardware (board) specific, rewrite for different boards State-of-the-art: SCA, Software Communication Architecture CORBA, XML with Object Request Broker (ORB) middleware Future: Ontology-based programming languages, “describe” to the board what to do, board (compiler) figures out how and if possible 1.Easier board programming, do it once for different architectures 2.Enable reconfiguration “on-the-fly”, download of new policies Benefits:

SDR with Ontology Language SDR to Operator: I’ve been an AM radio all my life, I want to become an FM radio! Operator: You’ll need to reconfigure your demodulator. SDR: How do I do that? Operator: You need 15 multipliers and 20 adders, do you have that? SDR: Yes. Operator: Now connect….

About us: SDR at the Wireless Communications Lab 2 Laptops running the GNU radio software, modified to work as 4 by 4 MIMO system, progam PHY In January: upgrade to 3 boards that feature VIRTEX 4 + ARM 9 + DSP, running real-time OS, program PHY, MAC and Network layers Now:

Why all that? WE WANT YOU FOR SOFTWARE DEFINED RADIO