1. SDR Technology Implementation for the Cognitive Radio
Bruce Fette PhD
Chief Scientist
General Dynamics Decision Systems
It is important to note that SDR is not really a new technology or term. Software defined radio or SDR was originally coined by Dr. Joe Mitola in 1991to signal the shift from dedicated single-purpose, hardware intensive radios of the 1980’s to the multi-band, multi-mode software defined radios that began to appear in the military in the 1990s. In fact, IEEE first published SDR technology in its IEEE Transactions on Communications in 1992.
In 1995, the SDR Forum was organized to begin to develop standards for SDR. The SDR Forum is a completely voluntary, interdisciplinary consortium that includes corporations and technologists from around the world.

2. Cognitive Radio* is Built on SDR*
We must start with a Software Defined Radio as a basic platform on which to build a Cognitive Radio
Cognitive Radio can provide the spectral awareness technology to support FCC initiatives in Spectral Use
Before Explaining Cognitive Radio and its capabilities, we need to provide background about what an SDR is, because an SDR platform serves as the basis upon which a Cognitive Radio is built.
*SDR and Cognitive Radio are terms coined by Dr. Joe Mitola - see appendices for references

3. Definition of SDR
From FCC NPRM*: “We view software defined radios as the result of an evolutionary process from purely hardware-based equipment to fully software-based equipment. In this regard, the process can be roughly described in three stages
1. Hardware driven radios: Transmit frequencies, modulation type and other radio frequency (RF) parameters are determined by hardware and cannot be changed without hardware changes.
2. Digital radios: A digital radio performs part of the signal processing or transmission digitally, but is not programmable in the field
3. Software Defined Radios:. All functions, modes and applications can be configured and reconfigured by software.
As you may already know, in August of 2000 a Notice of Proposed Rule Making or NPRM was issued. In this notice, the FCC created the case for SDR as the next operating standard for radio and related RF communications.
Under point 1: the transmit frequencies, modulation type and other radio frequency (RF) parameters are determined by hardware and cannot be changed.
Under point 2: Processing may be done by digital signal processors, by fixed programs stored as firmware, or by dedicated hardware such as application-specific integrated circuits or ASICs. These systems do not have forward flexibility to implement future protocols.
Under Point 3: A software radio can do something new after it is shipped, that was not specifically designed by the factory at time of manufacture.
Under Point 5
-Standardized hardware interface
-Standardize operating Environment (OS equivalent)
-Standardized Interface from Waveform applications to Operating Environment
-Standardized hardware/RF services
-Multiple capabilities in a single platform
I can’t go into the full details of the standardized hardware and software architectures, however, in the appendices, there is a detailed diagram of just what SDR means in real world applications.
*Notice of Proposed Rule Making (NPRM) 8/12/00

4. Definition of SDR - Continued
SDR Forum:
4. SW defines all waveform properties, cryptography and applications, is re-programmable, and may be upgraded in the field with new capabilities
Importance of Standards (APIs)
5. HW Interfaces, RF services, Operating Environment, Application to Radio Interfaces
As you may already know, in August of 2000 a Notice of Proposed Rule Making or NPRM was issued. In this notice, the FCC created the case for SDR as the next operating standard for radio and related RF communications.
Under point 1: the transmit frequencies, modulation type and other radio frequency (RF) parameters are determined by hardware and cannot be changed.
Under point 2: Processing may be done by digital signal processors, by fixed programs stored as firmware, or by dedicated hardware such as application-specific integrated circuits or ASICs. These systems do not have forward flexibility to implement future protocols.
Under Point 3: A software radio can do something new after it is shipped, that was not specifically designed by the factory at time of manufacture.
Under Point 5
-Standardized hardware interface
-Standardize operating Environment (OS equivalent)
-Standardized Interface from Waveform applications to Operating Environment
-Standardized hardware/RF services
-Multiple capabilities in a single platform
I can’t go into the full details of the standardized hardware and software architectures, however, in the appendices, there is a detailed diagram of just what SDR means in real world applications.

5. SDR Technology Technology fundamentals:
Digital Signal Processors (DSPs) provide virtually infinite programmability
All modulation, cryptography, protocols, and source coding (voice, data, imagery) are established using software
Many types of modulation can be accomplished over a broad range of frequencies, thereby an SDR is capable of servicing more than one class of service
Field serviceable, when requirements change, upgrades and modifications are relatively easy to execute
Standardized software interfaces enable software portability to multiple hardware architectures.
SDR Forum software standards/processes define operating environment and resource management in a way that is similar in concept to an OS.
Then, the hardware abstraction Layer (HALWG) defines API interfaces for external equipment interfaced to SDR software drivers as well as API interfaces for standard internal hardware interfaces.
SDR isn’t ‘smoke and mirrors’ either, software defined radios are operational and available today
GD-DS has deployed software defined radios such as the DMR and PRC112G to US DoD, UK MOD
Harris currently ships the PRC117F to DoD
Airnet uses SDR technology for its GSM basestation
And many more announced SDR products are in development:
Vanu, JTRS Cluster 1, etc
with many new commercial products scheduled for release in the next 3 years

6. SDR Standardized Architecture Supports Both Current and Future Applications
FDMA, TDMA, CDMA, TDD
AM, FM, MFSK, MPSK, MQAM, CPM, SSB, DSSS …
DES, 3DES, AES, MeXe
Trunked Radio, APCO-25, GSM, Iridium,
Tone Coded Squelch, CVSD, LPC, VSELP, AMBE, ….
It’s just a matter of software!
It is the equivalent to the PC that replaced the typewriter and the internet that replaced the teletype, the capability to mold your available resources to meet your needs.

7. Building the Cognitive Radio using SDR Technology - The SDR Radio is Available Now!
SDR drives the Cognitive Radio concept that will provide the spectral awareness technology supporting the FCC’s Spectral Use initiatives
SDR is a proven, flexible, COTS technology platform
SDR Technology is in Production and Available Now
At this point it is important to see that SDR is a product of Technological “Natural Selection”. It is an obvious and AVAILABLE, technological “next step”.
New
Announcements
Coming
Soon

8. Cognitive Radio Means “Smart” and “Alert”
It knows where it is
It knows what services are available, for example, it can identify then use empty spectrum to communicate more efficiently
It knows what services interest the user, and knows how to find them
It knows the current degree of needs and future likelihood of needs of its user
Learns and recognizes usage patterns from the user
Applies “Model Based Reasoning” about user needs, local content, environmental context
An extension of SDR employs “model based reasoning about user needs, local content and environmental context…
Think of it as a PDA with a radio that is so smart that it solves simple stuff on its own
round peg - round hole;

9. How Does a Cognitive Radio Get So Smart?
External
Intelligence
Sources
Orient
Establish Priority
Plan
Normal
Generate Alternatives
(Program Generation)
Evaluate Alternatives
Register to Current Time
Decide
Alternate Resources
Initiate Process(es)
(Isochronism Is Key)
Act
Learn
Save Global
States
Set Display
Send a Message
Observe
Receive a Message
Read Buttons
Outside
World
New
The Cognition Cycle
Prior
Pre-process
Parse
Immediate
Urgent
Infer on Context Hierarchy
Mechanisms for flexible pooling of radio spectrum using a new class of protocols “formal radio etiquette”
The radio learns.
As we learn important etiquettes and plug them into an SDR, along with enough smarts to choose the proper etiquette for the proper circumstances.
The degree of sophistication is practical where the radio architecture provides sufficient resources to support the protocols.
Mitola, “Cognitive Radio for Flexible Mobile Multimedia Communications”, IEEE Mobile Multimedia Conference, 1999, pp3-10

10. Example Spectral Awareness Etiquette That Can Be Implemented on Existing SDR / Cognitive Radio
Infrastructure Based Approaches
Possible Infrastructure Reuse - spread economic support base
Existing examples of Spectrum sharing Protocols
A) Trunked radio
B) Cellular spectrum borrowing
C) Demand Assigned Multiple Access (DAMA)(demand assigned time sharing)
Infrastructure Supports wide Range of Spectrum Management Policies
Match Requirements, Priorities, Spectral Mask of Owners
Many Commercial applications already have support infrastructure, and the support infrastructure allows a high degree of sophistication in spectral awareness, protocol - etiquette, and responsiveness to policies of the spectral owner.
Within this context, spectrum sharing domains include:
Trunked Radio is a valuable example of the success of TASI sharing - 20X demonstrated or more where user community is aggregated to the 50 Erlang level or more
Public Safety - Be sure that priority and preemption provide high QoS to public safety
Cellular - service sharing can provide expanded coverage for both cellular, public safety, and federal services in regions where neither is economical on a stand alone basis
TV - great opportunities in T-F-C-S sharing

11. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Cognitive Radios can adopt new etiquettes for new standards
Possible Demonstrations using existing SDRs
Spectrum rental transactions
Spectral Availability (Borrow) Beacon
Local Spectrum Utilization Database Server (time, freq, code, space, power, modulation)
• Distributed techniques - Possible Demonstrations
Spectral Noise temperature (Kolodzy, 2002)
RTS - CTS handshake (handshake includes local spectral activity model at each end of link, as well as BW, packet size, TX PWR for APC). Minimizes hidden node problem
Underlay, Overlay, Interweave
Infrastructure Based Approaches:
Existing examples of Spectrum sharing Protocols
A) trunked radio
B) Cellular spectrum borrowing
C) DAMA demand assigned multiple access (demand assigned Time sharing)
Cognitive Radios can adopt new etiquettes for new standards
Possible Demonstrations using existing SDRs
A) Spectrum rental transactions
B) Spectral Availability (Borrow) Beacon
C) Local Spectrum Utilization Database Server (time, freq, code, space, power, modulation)

12. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency

13. SDR Finds Frequency - Time Opportunities Spectral Awareness Etiquette
Deployed waveforms
Existing Signals
Our SDR can search the spectrum, gather activity statistics, modulation properties, and choose frequencies that can be used for additional spectral use.
Detailed Signal Parameters

14. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user

15. Opportunities for Spectral Reuse Amongst Periodic Signals
Even in active Spectrum there is great opportunity to use the spectrum, providing that waveforms are selected for orthogonal properties and that cross purpose interference is managed through antenna beam forming.

16. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user
Spatial - Beam steering and Null Steering

17. Time - Frequency - Space
Each Domain has Opportunities for Spectral Reuse
Transmitter forms Beam Toward Intended Recipient
Receiver forms Null Toward Interference Sources
R1,R4 T2 T1
Interfering
Signal Placed
In Null
R3,T4 T3 R3

18. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user
Spatial - Beam steering and Null Steering
Adaptive Bit Loading onto OFDM carriers based on SNR

19. OFDM Interference Avoidance1 2 3
0.5
1.5
2.5
x 10 6
-100
-80
-60
-40
-20
Transmission Number
Frequency (Hz)
Power Spectrum Magnitude (dB)
-140
-120
Tx Spectrum
Rcv Spectrum
-90
-70
-50
-30
-10
Shaped 128 kbps
QPSK Interference Spectrum
Normal
Survive

20. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user
Spatial - Beam steering and Null Steering
Adaptive Bit Loading onto OFDM carriers based on SNR
OFDM techniques where small spectral holes can be filled by one or
a few carriers that fit the time - frequency hole

21. OFDM Carriers Selected for Use That Fall into Available Spectrum
Spectral Adaptation Waveforms T I M E
Frequency

22. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user
Spatial - Beam steering and Null Steering
Adaptive Bit Loading onto OFDM carriers based on SNR
OFDM techniques where small spectral holes can be filled by one or
a few carriers that fit the time - frequency hole
Interference Suppression & MultiUser Decomposition

23. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user
Spatial - Beam steering and Null Steering
Adaptive Bit Loading onto OFDM carriers based on SNR
OFDM techniques where small spectral holes can be filled by one or
a few carriers that fit the time - frequency hole
Interference Suppression & MultiUser Decomposition
Importance of Adaptive Power Control
AD Hoc Networking (shortest hop routing w APC)

24. Transmitting from A -> Z : AdHoc Networking
Node Z
Node A

25. Example Spectral Awareness Etiquette Can Be Implemented on Existing SDR/Cognitive Radio (continued)
Waveform Orthogonality: Time - Freq - Code - Hop/Chirp - Spatial Usually Involves some form of CSMA sensing for high priority user
Adaptive Frequency - find a frequency
Adaptive TDMA - find an unused time slot in between a periodic user
Spatial - Beam steering and Null Steering
Adaptive Bit Loading onto OFDM carriers based on SNR
OFDM techniques where small spectral holes can be filled by one or
a few carriers that fit the time - frequency hole
Interference Suppression & MultiUser Decomposition
Importance of Adaptive Power Control
AD Hoc Networking (shortest hop routing w APC)

26. Timeline: SDR’s to have Cognitive Capabilities
2003
2004
2005
2006
2007
2008
5 years for
etiquettes
to be formally
standardized
Commercial
viability
exploration &
commercial
analysis under
existing
agreements
Viability
demonstrated
for commercial
purposes
within 2 year
DARPA’s
Demonstrations
within 1 year
SDR Forum can
initiate early work
and insert into
standards bodies as
work matures
The FCC’s cognitive radio is fully realizable using today’s SDR technology.
2003
2004
2005
2006
2007
2008

27. In Conclusion SDR Products and Technology are a Reality Today
SDR Standards are Actively Being Worked today by Standards Bodies and Organizations
Cognitive Radios have the Ability to Implement Protocols and Policies Beyond Traditional Communications.
New Realms of Knowledge and Information Transfer are Achievable with Cognitive/SDR Radio as the Underlying Technology Enabler

28. Appendix SCA Reference Architecture
Radio Services for Application Portability
SDR Forum Standardized Hardware Architecture
Reference Publications

29. SCA Reference Architecture

30. Radio Services For Application Portability
JTR Set
Operating
Environment
(Ext)
(Int)
(Int)
(Ext)
Radio
Services
(Int)
Devices WF
Apps
(Int)
(Int)
(Ext)
Radio Systems
Applications
(Ext)
Middleware
Services

31. SDR Forum* Standardized Hardware Architecture
BB / IF
Real/
Complex
Digital/
Analog
BITS
Cypher T
ext
Flow Contl
Plain T
Aux
Key
Fill
Representative
Information
Flow
Formats
AIR
I/O C I
CONTROL
MSG
PROCESS
& I/O
Routing
Common
System
Equipment
Clock/Strobe
Ref, Power
Multimedia
Voice
Data
Flow Control
Network
Ext. Ref
Remote Control/
Display
User Control
(HMI)
Aux: Special Purpose
I/O for
Antenna Diversity
Co-site Mitigation, etc.
I: Information
BB: Baseband
C: Control/Status
SEC I/O
LINK
PROC
(Black)
INFOSEC
MODEM
ANTENNA
(A)
(R)
(M)
(C)
(S)
(L)
Video
From Programmable Modular Communications System (PMCS) Guidance Document, 1997
*SDR Forum was established as an Industry Organization to address SDR technology on 1995

32. Reference Publications
Mitola, “Cognitive Radio for Flexible Mobile Multimedia Communications”, IEEE Mobile Multimedia Conference, 1999, pp3-10
Mitola, “Future of Signal Processing - Cognitive Radio”, Keynote, IEEE ICASSP, May 1999
Mitola, Maguire, “Cognitive Radio: Making SW Radios More Personal”, IEEE Personal Communications, August 1999, pp13-18
Mitola, “SDR Architecture Refinement for JTRS”, Milcom 2000, pp
Mitola, “Software Radio Architecture: A Mathematical Perspective”, IEEE J on Selected Areas in Comms, April 1999, pp
Margulies, Mitola, “Software Defined Radio: A Technical Challenge and a Migration Strategy”, 1998, pp