1 Software-Defined Radio Chang Chung-Liang

2 Content Why is “Soft Radio”? What is “Software Radio”? Software Radio Architecture Benefits of Software Radio Technology Challenge Speakeasy Project Conclusions

3 Software-Defined Radio History 1970`s lateICNIAU.S.A.F 1983Grenada Conflict 1991Desert Storm 1992Speakeasy Phase I 1995Speakeasy Phase II 1996MMITS

4 Evolution of Wireless Standards

5 Panacea for All Standards? CDMA2000 PACS GSM DECT AMPS WCDMA PHS

6

7 Hardware/Software Mixture

8 What is Software Radio? A radio that is substantially defined in software and whose physical layer behavior can be significantly altered through changes to its software Convergence of digital radio and software technology Dynamic radio equipment reconfiguration by downloadable software A device with  Multi-band antenna(s) and RF conversion  Wideband A/D and D/A  Digital signal processing(using software )

9 Function Definition of Software Radio Transmit  characterize the available transmission  probe propagation path  construct an appropriate channel modulation  electronically steers its transmit beam in the right direction  select the appropriate power level  transmit

10 Function Definition of Software Radio Receiver  characterize the energy distribution in channel and adjacent channel  recognizes the mode of the incoming transmission  adaptively nulls interferers  estimates the dynamic properties of the desired- signal multipath  coherently combines desired-signal multipath  decodes the channel modulation  corrects residual errors via forward error control (FEC) decoding to receive the signal with lowest possible BER.

11 The Evolution of Software Radio Terminal Structure Processing Channel Coding and Source Coding by Software Processing Channel Coding, Source Coding and Baseband MODEM by Software Processing Channel Coding, Source Coding, Baseband MODEM and IF(RF) by Software

12 Software Radio Architecture RF conversion Wideband A/D/A High-Speed DSP

13 Wideband Software Transmitter Architecture Baseband Processing Channel 1 Channel 2 Channel M Digital Channelization Single DAC RF-IF upconverter Wideband transmit filter HPA N Frequency Operator’s Licensed Band

14 Wideband Software Receiver Architecture Baseband Processing Channel 1 Channel 2 Channel M Digital Channeliztion Single ADC RF-IF down converter Wideband receive filter LNA N Frequency Operator’s Licensed Band Received PSD

15 RF conversion and A/D RF-BF LNA LO LF-BF A/D Architecture 1:

16 RF-BF LNA LO LF-BF A/D RF-BF LNA LF-BF A/D RF-BF LNA LF-BF A/D Architecture 2:

17 RF-BF LNA RF-BF A/D RF-BF LNA Architecture 3:

18 Evolution of RF Transceiver Architecture source:TI semiconductor

19 High-Speed Digital Signal Processor Number Controlled Oscillator Low-pass Decimating Filter Digital Signal Processor (Demodulation) Typical DSP Function: I Q sincos Error signal

20 Phase I RF Front End Analog IF Processing A/D D/A Baseband MODEM Processing Bitstream Processing (MUX, De-MUX, FEC Data terminal I/F CODEC Control MMI D/A A/D (Dedicated digital HW) Software processing (DSP, CPU, Programmable logic) Can introduce new functions into the same system easily

21 Phase II RF Front End Analog IF Processing A/D D/A Baseband MODEM Processing Bitstream Processing (MUX, De-MUX, FEC Data terminal I/F CODEC Control MMI D/A A/D (Dedicated digital HW) Software processing (DSP, CPU, Programmable logic) Can realize adaptive modulation and adaptive reception scheme etc.

22 Phase III( Ideal Soft Radio) Wideband RF Front End Digital IF Processing A/D D/A Baseband MODEM Processing Bitstream Processing (MUX, De-MUX, FEC Data terminal I/F CODEC Control MMI D/A A/D (Dedicated digital HW) Software processing (DSP, CPU, Programmable logic) Will enable single terminal to adapt to multiple air interface standards Software Reconfigure a radio by changing software

23 Smart Antenna

24 Smart Antenna Technology- Precursors Sectorization Microcell Diversity More antennas provide increased ability to control power

25 Smart Antenna To increase the user capacity is the key motivation of smart antenna development. That is to enhance the voice channel in a given coverage area Technical requirement: an array to increase C/I  Create gain on the array in the intended direction using antenna aperture.  Minimize the effects of destructive specular multipath combining to recover the fading margin.  The identification and nulling of interference Few cell sites required More efficient use of licensed RF spectrum

26 Benefits of Software Radio Manufacturer –One hardware platform for all markets –Portability of software between platforms. Operator –Upgrade of terminals –Addition of new services –Correction of software bugs in terminals Consumer –Connect to any network and world wide roaming –Support for new services

27 Benefits of Software Radio Flexibility: multi-band, multi-mode, multi-protocol Adaptability: Change modulation schemes for different environment. Upgradability: Change for new emerging standards. Universal accessibility: GSM, CDMA, IS-136, PDC, PHS, PACS, DECT, CDPD, Mobitex, GPS... Cost Scalability:Silicon-based DSP implementation allows aggressive cost reduction Feasibility: Radio functions can be implemented that cannot be implemented in analog hardware, ex. FIR filter, sharp rolloff & linear phase Stability: Radio functions implemented with DSP don’t require tuning or tweaking typically required in analog hardware

28 Technology Challenges Common baseband (BB) and RF hardware for several different systems Higher integration level Parameterized BB modules Configurable RF architecture Architecture Challenges Module level Challenges

29 Technology Challenges Architecture challenges  Partitioning between analog and digital  Partitioning between DSP/RSIC, PGA etc.  SW architecture: modularity  Dynamic processing capacity allocation between similar  (and different) units  Required duplication of frequency-dependent parts

30 Transceiver Architecture Sampling at 1st IF  Filtering easier when divided to several stages  IF filters hard to integrate Direct Conversion  No large IF filters  Spurious leakage and DC offset Direct Sampling  Highest digitalization level  Extreme Requirement for RF filtering and DSP processing

31 RF Hardware Challenges Broadband, Multi-mode, Smart antennas Broadband, Low-distortion, high efficiency HPA  Cartesian feedback  Digital predistortion  Feedforward  Accuracy and linearization requirement extremely high for multilevel modulation, multicarrier and CDMA systems RF/IF filtering - different bands, different bandwidths  Configurable (tunable/switched) filters Wide dynamic range AGC in IF or RF Wide operation range synthesizers and VCOs Frequency-elimination duplexer to allow both FDD and TDD operation Low power consumption and small size

32 Base Band Challenges High Speed Signal Processing Most Challenging  High speed instruction processor DSP  DSP plus multiple ASIC’s one for each service  DSP plus parameterized ASIC accelerators  Reconfigurable Logic Multiple bandwidth A/D’s

33 Speakeasy Project Speakeasy Phase I  Objects  Robust Electronic Counter-Counter Measures(ECCM)  Low Probability of Intercept(LPI) Waveform  Open architecture Modular, Reprogrammable, Modem  Develop The Addition of New Waveform

34 Speakeasy Project Speakeasy Phase I  Advance Designs  Fast fourier Transform(FFT)  ADC High-Speed Sampling and Large Dynamic Range  A Quad-DSP Module  RF Up- and Downconversion with instantaneous bandwidth  A Programmable Information Security(INFOSEC)

35 Speakeasy Project Speakeasy Phase I  Results  Four Channel  High-Speed Frequency-Hopped  Pseudorandom Spread-Spectrum Waveforms  Over The Military HF, VHF, UHF Bands  Unfortunate  Modem Software  User Interface  Waveform Development Enviroment  Only Midband 30 to 400MHz Demonstration

36 Speakeasy Project Speakeasy Phase II  Objects  Expand The Modem to The Entire Radio System Open, Modular, Reprogrammable  Lower Life-Cycle Costs  Emphasized Commercial Off-The-Shelf(COTS)  Commercial Communication Standards  Coverage from 2MHz to 2GHz

37 Ext RF TX/ RX Ref Gen Cellular A/D D/A Pre- Proc Wave -form Proc INFO- SEC Multi- media Router I/O Control Proc GPS MMI Speakeasy Phase II Architecture RF FRONT ENDMODEMINFOSECNETWORKING MMI/ CONTROL

38 Speakeasy Phase II Air Force Tactical Air Control Parties HAVE QUICK(UHF) Voice and data SINCGARS(VHF) SDR LMR California Arizona wire HAVE QUICK(UHF) Voice and data

39 Conclusion Software Radio concepts are being rapidly accepted for communication system There are still many bottlenecks having to be overcome to realize Software Radio, such as RF technology, DSP and Protocol Software Radio provides a very wide area for the playing of researchers.manufacturers, service providers in the future