Software Radio

1
Software Radio

• Abhishek Banerjee
• Vivek Gaddipati

2
Agenda

• 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
3
The Problem - Interoperability

• 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!
• 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

4
The Solution Software Defined Radio
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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.

6
SDR - History

• increased attention during second part of
  1990-ies
• MMITS formed by US government, for converging the
  multiple radio interfaces and systems in defense
  area
• MMITS changed name and scope to SDR Forum
• In Europe, the CEC took several initiatives to
  promote and boost SDR development.
• Standard architecture (SCA)
• Published by Joint Tactical Radio System
  (JTRS) Joint Program Office (JPO)

7
The SDR Forum

• 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
• International membership and alliances, over 70
  organizations
• service providers/ network operators
• equipment manufacturers (infrastructure and user
  terminals)
• component manufacturers
• hardware and software developers
• regulatory agencies
• academic and research organizations
• Permanent staff established March 2000 to support
  growing level of participation from predominantly
  commercial members

8
Why we need Software Radio 1/2

• Enables the creation of open APIs for the radio
  interface and reduces the number of radio
  components.
• 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.
• They can be quickly and easily upgraded with
  enhanced features.

9
Why we need Software Radio 2/2

• 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.
• Smart radios or cognitive radios can look at the
  utilization of the RF spectrum in their immediate
  neighborhood, and configure themselves for best
  performance
• 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.

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Present Scenario
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Future with Software Radio
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Value added to the chain
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Where can we use SDR ?

• Base Stations
• Weak constraints on power and area
• Support several hundred subscribers
• Will be commercialized first
• Wireless terminals
• Tight constraints on power and area.
• Will be commercialized next

14
Applications

• The military has been interested in software
  radio for some time, and not surprisingly, some
  of the first implementations have been in
  military applications.
• Telematics (i.e. use of computing and
  communications in vehicles) will be one of the
  earliest commercial applications of software
  radio.
• Wireless service operators and equipment
  manufacturers are also interested in software
  radio.
• Software radios hold great promise for wireless
  consumer devices because they can facilitate
  meeting form factor and convenience goals

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SDR in military applications 1/2

• Goals
• To enable and improve the efficiency of
  joint operations (co-operation between separate
  troops)
• 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).

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SDR in military applications 2/2

• 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
  SCA-architecture.

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SDR in civil applications

• State of software radio
• 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.

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Emerging SDR uses

• Personal communication devices
• Cellular / Paging / Wireless LAN(s)
• PC based generic transceiver
• Radio / TV
• Emerging unlicensed RF band apps

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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

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HW/SW Thread View
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Software Design Approach

• Software Common Architecture (SCA) Approach
• ?? Well defined Interfaces enable the
  independence of SW modules.
• ?? Operating System Isolation Layer (OSIL)
• 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

22
HW/SW Processing View
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SCA 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.
• Currently the most advanced (and only) open
  standard developed for the software radio.

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SCA 2/4

• 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.
• Network Serial Interface Services
• The Software Architecture relies on
  commercial components to support multiple unique
  serial and network interfaces.
• Possible serial and network physical interfaces
  include RS-232, RS-422,RS-423, RS-485, Ethernet,
  and 802.x.

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SCA 3/4

• Operating System Layer
• The Software Architecture includes
  real-time embedded operating system functions to
  provide multi-threaded 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.
• 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.

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SCA 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, link-level 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.

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Hardware view of Software Radio
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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

• 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.

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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

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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

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What is GNU Radio?

• Its 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

34
Software Radio Networking

• 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
  Ad-hoc, 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.

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Technological challenges 1/3

• 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/D-converter 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.

36
Technological challenges 2/3

• 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.

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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?

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Software issues

• 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

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SDR Security 1/3

• SDRs 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
• 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.
• 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.
• 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.
• User Applications - application software not
  falling into any of the above categories.

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SDR Security 3/3

• 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.

42
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.

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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.

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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

45
References Further Reading

• 1www.sdrforum.org
• 2Reed J. H., Software Radio A Modern Approach
  to Radio Engineering, Prentice Hall, 2002
• 3Tuttlebee W. (Ed.), Software Defined Radio
  Origins, Drivers and International Perspectives,
  John Wiley Sons, Ltd., 2002
• 4Brederlow 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 WirelessSystemsEnginee
  ring. John Wiley Sons, Ltd., 2000.

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Quiz

• Define Software Radio.
• What are the advantages of Software Radio
  technology?
• What are the disadvantages of Software Radio
  technology?