Transcript Document 7494400

Software Radio
-Abhishek
Banerjee
-Vivek Gaddipati
Agenda
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Problem – Solution
Software Radio Defined
SDR History
Why we need Software Radio
Applications
SDR Architecture
Architecture & Programmability
Technological Challenges
Security Implications
Advantages and Disadvantages
Conclusions
References and Further Reading
Quiz
Vivek
Abhishek
The Problem - Interoperability
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Northern Iraq:
US Navy jets mistakenly attacked a Kurdish convoy led by US
Special Operation Forces. Caused by a simple mix-up: the radios
carried by the SOF were compatible only with USAF aircraft but not
with US Navy jets which had attacked them!
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September 11:
Hundreds of firefighters and police officers rushed into the World
Trade Center. Helicopters circling overhead noticed the buildings
starting to glow and relayed to incident commanders on the ground
that the buildings may collapse. The police officers were given the
order to evacuate --- all but 80 escaped. The firefighters never got
the word --- 121 of them, most within striking distance of safety,
never got the word
The Solution: Software Defined Radio
What is Software Radio?
•Software radio is the art and science of building radios
using software.
•The idea is to get the software as close to the antenna as
is feasible
•By radio, I mean any kind of device that intentionally
transmits or receives signals in the radio frequency (RF)
part of the electromagnetic spectrum.
Examples:-phones and cordless phones, Garage door openers, Car door
openers, Wireless internet cards (WiFi / 802.11), pagers, GPS, the list goes
on and on.
SDR - History
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increased attention during second part of 1990-ies
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MMITS formed by US government, for converging the
multiple radio interfaces and systems in defense area
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MMITS changed name and scope to SDR Forum
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In Europe, the CEC took several initiatives to
promote and boost SDR development.
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Standard architecture (SCA)
Published by Joint Tactical Radio System
(JTRS) Joint Program Office (JPO)
The SDR Forum
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Open, non-profit corporation created in 1996, to develop technical
specifications and standards requirements that meet the diverse
requirements for commercial wireless, defense, and civil government
applications of SDR
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International membership and alliances, over 70 organizations:
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service providers/ network operators
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equipment manufacturers (infrastructure and user terminals)
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component manufacturers
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hardware and software developers
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regulatory agencies
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academic and research organizations
Permanent staff established March 2000 to support growing level of
participation from predominantly commercial members
Why we need Software Radio 1/2
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Enables the creation of open APIs for the radio interface and
reduces the number of radio components.
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This is very useful to increase the battery life and make the
seamless operations simpler. Intelligent terminals may benefit a
lot of the multimode features.
For ex: there is no reason to deliver High Quality TV picture via
Cellular networks if TV broadcasting can be utilized.
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They can be quickly and easily upgraded with enhanced
features.
Why we need Software Radio 2/2
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They can be reconfigured "on-the-fly". That is, depending on what you
need, your universal communication device would reconfigure itself
appropriately for your environment.
Example:-It could be a cordless phone one minute, a cell phone the
next, a wireless internet gadget the next, and a GPS receiver another.
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Smart radios or cognitive radios can look at the utilization of the RF
spectrum in their immediate neighborhood, and configure themselves
for best performance
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Software radio makes it feasible to implement many of the
complementary advances in wireless technology that have occurred in
recent years, including smart antennas, adaptive power management,
or new modulation and signal processing techniques.
Present Scenario
Future with Software Radio
Value added to the chain
Where can we use SDR ?
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Base Stations
 Weak constraints on power and area
 Support several hundred subscribers
 Will be commercialized first
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Wireless terminals
 Tight constraints on power and area.
 Will be commercialized next
Applications
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The military has been interested in software radio for some time,
and not surprisingly, some of the first implementations have been
in military applications.
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Telematics (i.e. use of computing and communications in vehicles)
will be one of the earliest commercial applications of software
radio.
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Wireless service operators and equipment manufacturers are also
interested in software radio.
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Software radios hold great promise for wireless consumer devices
because they can facilitate meeting form factor and convenience
goals
SDR in military applications 1/2
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Goals:
– To enable and improve the efficiency of joint
operations (co-operation between separate
troops)
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Interoperability (connections between different
systems).
– Implementation of new features and systems
without the need to purchase new equipment.
– Reduce the number of radios. US armed
forces has 25 – 30 radio families in use.
– Flexible services (adaptive waveforms).
SDR in military applications 2/2
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Joint tactical radio systems – JTRS
– US military software radio program.
– Family of common Radios and Waveforms
built around a standard open architecture.
– New radios of US armed forces must fulfill
JTRS requirements.
• Radios must be based on SCAarchitecture.
SDR in civil applications
 State of software radio:
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– The role of software radio in civil applications is not
clear yet.
Some possible applications:
Next generation multimedia satellites
Only (economical) way to introduce new services or
systems to orbiting satellites.
Implementation of 4G-terminals.
The same terminal or base station can operate in several
different systems.
Reconfigurable multi-standard terminal for
heterogeneous networks.
Emerging SDR uses
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Personal communication devices
 Cellular
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/ Paging / Wireless LAN(s)
PC based “generic transceiver”
 Radio
/ TV
 Emerging unlicensed RF band apps
SDR Generic Architecture
•Common Hardware / Open Architecture
•Commercial Level Cryptography
•SEI/SCA Based Software Architecture
OSIL/CORBA implementation
Multiple functionality and performance in the presence of
failures
HW/SW Thread View
Software Design Approach
Software Common Architecture (SCA) Approach
􀂋 Well defined Interfaces enable the independence of SW
modules.
􀂋 Operating System Isolation Layer (OSIL)
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Modifications to SCA approach based on routing of
secure data
Isolation of key data Paths
No multi-tasking of processors to ensure security
measures are implemented
HW/SW Processing View
SCA
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1/4
The Software Communications Architecture (SCA) specification
establishes an implementation independent framework with baseline
requirements for the development of software configurable radios.
• These requirements are comprised of interface specifications,
application program interfaces (APIs), behavioral specifications, and
rules.
• The goal of this specification is to ensure the portability and
configurability of the software and hardware and to ensure
interoperability of products developed using the SCA.
• Open standard.
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Currently the most advanced (and only) open standard developed
for the software radio.
SCA 2/4
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Bus Layer (Board Support Package):
– The Software Architecture is capable of operating on
commercial bus architectures. Possible buses include
VME, PCI, CompactPCI, Firewire (IEEE-1394), and
Ethernet.
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Network & Serial Interface Services:
– The Software Architecture relies on commercial
components to support multiple unique serial and
network interfaces.
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Possible serial and network physical interfaces include
RS-232, RS-422,RS-423, RS-485, Ethernet, and 802.x.
SCA
3/4
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Operating System Layer:
– The Software Architecture includes real-time
embedded operating system functions to provide multithreaded support for applications. The architecture
requires a standard operating system interface for
operating system services in order to facilitate portability
of applications. Specification defines a minimal POSIX
profile to meet SCA requirements.
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Core Framework:
– The CF is the essential (“core”) set of open
application-layer interfaces and services to provide an
abstraction of the underlying software and hardware
layers for software application designers.
SCA
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4/4
CORBA Middleware:
– CORBA is used in the CF as the message passing
technique for the distributed processing environment:
Application Layer:
– Applications perform user communication functions
that include modem-level digital signal processing, linklevel protocol processing, network-level protocol
processing, routing, external (I/O) access, security, and
embedded utilities. Applications are required to use the
CF interfaces and services.
Hardware view of Software Radio
SDR Architecture Advantages
Common Assets capable of performing any
of the functions in the radio
􀂋 Common hardware
􀂋 Open Architecture
􀂋 Software Modularity
􀂋 Graceful Degradation in failure conditions
􀂋 Open Architecture features allow additional
functionality to be added with minimal impact
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Programmability 1/3
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Programmable components:
– General purpose processors
– DSP-processors
– FPGAs
– ASSP-processors (e.g. in filtering)
– Tunable RF-circuits
Modular design.
Plug and play modules to add new HW resources or to
replace old ones with more capacity.
Programmability 2/3
Hardware radio
 no software changes
Software controlled radio
 in PDR, BB operations and link layer protocols are
implemented in software.
Software defined radio
 SDR system is one in which the BB processing as well
as DDC/DUC modules are programmable.
PDR - programmable digital radio
DDC/DUC, digital BB, baseband down/up converter
Programmability 3/3
Ideal software radio
 programmability is extended to the RF
section
Ultimate software radio
 in a single chip, no external antenna and
no restrictions on operating frequency
 intended for comparison purposes only
What is GNU Radio?
It’s a free software defined radio
 A platform for experimenting with digital
communications
 A platform for signal processing on
commodity hardware
 Transmit and receive any signal
 Create a practical environment for
experimentation & product delivery
 Expand the “free software ethic” into
what were previously hardware intensive
arenas
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Software Radio Networking
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Software radios acting as nodes in a network.
Software radios acting as gateways or bridges
between networks.
Software Radio Network is in the nature of a Adhoc, Multi-Hop, Self-organizing Network.
OSI protocol architecture includes layers :
Physical, Data Link, Network, Transport and
Application.
Issues are :
Scalability
Security
Support for different protocols.
Technological challenges 1/3
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Data converters are one of the key enabling technologies.
 Dynamic range of wideband, high-speed A/D-converters is
perhaps the most limiting factor in software radio
implementation.
 Superconductor technology can be used to improve A/Dconverter performance
 With current technology it is possible to produce over 20
effective bit A/D-converters that operate at 2 GHz center
frequency and have bandwidth of 60 MHz.
 Converter with 400 MHz bandwidth at 5 GHz center frequency
and 10 –12 bit resolution is under development.
 Need for low temperatures, 5 K cooler will require about 500
cubic inches and 100 –150 W.
Technological challenges 2/3
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In portable devices power consumption is a critical issue.
 Fast data converters and powerful (high clock
frequency) processors need more power than slower
ones.
 Applications (e.g. image processing) need processing
capacity.
 A/D-processing at low IF-frequency or at base band.
 Analog down conversion and filtering.
 Multi-band, multi-signal operation by integrating
separate RF-chains into a chip, MEMS-technology
can be used to implement filter banks and tunable
circuits.
Technological challenges 3/3
Other challenges -DSP
 Several simultaneous connections.
•Different sample rates needed for different systems.
 Implementation of new features and new systems
 All signal processing with programmable components
•DSP vs. FPGA.
 Need of computation resources
•How much is enough?
•How to reckon with future computation needs?
 Allocation of computation resources between applications
•Dynamic allocation in changing situation.
•How to ascertain that all applications have enough computing
resources?
Software issues
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Software components
 Operating system
 DSP-function/algorithm library
 Network function/algorithm library
 Applications/interfaces to applications
 User interface
Addition of new features
Software reuse
 Same software in different equipments
Development of general architecture requires modeling of the
architecture using some formal method
 Comparison between alternatives
 Design and testing of control structures
 Administration of updates
SDR Security 1/3
SDR’s used will require at least
commercial cryptography to prevent
the networks from penetration
􀂋 Anti Hi-Jack
􀂋 Anti Spoofing
􀂋 Positive Identification of participants
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SDR
Security
2/3
The SDR Forum classifies the collection of software for SDR as follows:
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Radio Operating Environment - consists of the core framework, the
operating system, device drivers, middleware, installer and any
other software fundamental to the operation of the radio platform.
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Radio Applications - software which controls the behavior of the RF
function of the radio. This includes any software defining the air
interface and the modulation and communication protocols. It also
includes used to manage or control the radio in a network
environment.
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Service Provider Applications - software used to support network
and other service provider support for the user of the radio. It
includes voice telephone calls, data delivery, paging, instant
messaging service, video pictures, emergency assistance, and
geolocation.
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User Applications - application software not falling into any of the
above categories.
SDR Security 3/3
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Security threats from programmability of RF
parameters such as modulation, frequency and
power.
Unauthorized modification of radio function can
be avoided by ensuring separate processes,
trusted and policy driven configuration.
Protect memory access by software based fault
isolation techniques.
Advantages of SDRs
Communicators across the globe are now in a position to enjoy the
advantages of SDRs. Desirable characteristics include, but are not
limited to:
a) the ability to receive and transmit various modulation methods using
a common set of hardware;
b) the ability to alter functionality by downloading and running new
software at will.
c) the possibility of adaptively choosing an operating frequency and a
mode best suited for prevailing conditions;
d) the opportunity to recognize and avoid interference with other
communications channels;
e) elimination of analog hardware and its cost, resulting in simplification
of radio architectures and improved performance; and
f) the chance for new experimentation.
Disadvantages of SDRs
While SDRs offer benefits as outlined above, a few obstacles remain to their
universal acceptance. Those include:
a) the difficulty of writing software for various target systems,
b) the need for interfaces to digital signals and algorithms,
c) poor dynamic range in some SDR designs, and
d) a lack of understanding among designers as to what is required.
e) Complex Networking protocols required
f) Huge efforts in standardization and regulation
g) Opens up great security implications.
Conclusions
SDR contains large number of areas that require significant research
Hardware
 Improving functionality to support additional flexibility
Operating Environment
 Standardize functionality and interfacing to support problems directly
relevant to radio design
 Power sensitive environments
Network
 Develop applications that can break the previous approaches for the
management of resources and take full advantage of capabilities of SDR
References & Further Reading
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[1]www.sdrforum.org
[2]Reed J. H., Software Radio: A Modern Approach to Radio Engineering,
Prentice Hall, 2002
[3]Tuttlebee W. (Ed.), Software Defined Radio: Origins, Drivers and
International Perspectives, John Wiley & Sons, Ltd., 2002
[4]Brederlow R., Weber W., Sauerer J., Donnay S., Wambacq P., Vertregt
M., A Mixed-Signal Design Roadmap, IEEE Design & Test of Computers,
November-December 2001.
[5] Software Communications Architecture Specification, MSRC-5000SCA
V2.2, November 17, 2001
TuttlebeeW. (Ed.), Software DefinedRadio: EnablingTechnologies, John
Wiley& Sons, Ltd., 2002.
DillingerM., MadaniK., AlonistiotiN. (Editors), Software DefinedRadio:
Architectures, Systemsand Functions, John Wiley& Sons, Ltd., 2003.
MitolaJ., Software Radio Architecture: Object-OrientedApproachesto
WirelessSystemsEngineering. John Wiley& Sons, Ltd., 2000.
Quiz
Define Software Radio.
 What are the advantages of Software
Radio technology?
 What are the disadvantages of Software
Radio technology?
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