Software Defined RadiosSoftware Defined Radios

The future of wireless The future of wireless technologytechnology

By Zac LessardBy Zac Lessard

Software Defined Radios what are Software Defined Radios what are they??they??

A radio in which some or all of the A radio in which some or all of the physical layer functions are software physical layer functions are software defined.defined.

This is contrasted with older radios This is contrasted with older radios where all of their functionality is where all of their functionality is determined by hardware. determined by hardware.

Five Tiers of SDR technologyFive Tiers of SDR technology

Tier 0 – Pure hardware radiosTier 0 – Pure hardware radios Tier 1 – Software “controlled radiosTier 1 – Software “controlled radios Tier 2 - modulation methods, band Tier 2 - modulation methods, band

selection between wide or narrow, selection between wide or narrow, security mechanisms and controls security mechanisms and controls such as hopping pattern such as hopping pattern management, and wave form management, and wave form selection are all handled by softwareselection are all handled by software

Four Tiers Cont.Four Tiers Cont.

Tier 3 – fully programmable radios.Tier 3 – fully programmable radios. Tier 4 - radios are the absolute model of Tier 4 - radios are the absolute model of

perfection, and they exist only on paper. perfection, and they exist only on paper. They are the absolute pinnacle of anything They are the absolute pinnacle of anything wireless technology could ever even begin wireless technology could ever even begin to approach. These radios are capable of to approach. These radios are capable of anything a user can imagine, from storing anything a user can imagine, from storing money transfer information on smart money transfer information on smart cards, to receiving satellite transmissions cards, to receiving satellite transmissions in real time. in real time.

The history of SDRThe history of SDR SPEAKeasy phase ISPEAKeasy phase I A government program with the following goals: A government program with the following goals: to develop a radio that could function to develop a radio that could function

anywhere between 2 Mhz and 2 Ghz,anywhere between 2 Mhz and 2 Ghz,to be able to communicate with the radios used by to be able to communicate with the radios used by

ground forces as well as air force and naval ground forces as well as air force and naval radios in addition to satellites radios in addition to satellites

to develop a new signal format within 2 weeks with to develop a new signal format within 2 weeks with no prior preparation no prior preparation

To use parts and software from multiple contractors To use parts and software from multiple contractors at once at once

SPEAKeasy Phase ISPEAKeasy Phase I

When the project was tested at When the project was tested at TF-XXI Advanced Warfighting Exercise it was deemed a success. it was deemed a success.

One problem was that the One problem was that the cryptography engine could not keep cryptography engine could not keep up well enough to maintain several up well enough to maintain several connections at once.connections at once.

SPEAKEasy Phase IISPEAKEasy Phase II

Phase II made use of an open architecture Phase II made use of an open architecture known as Software communication known as Software communication architecture.architecture.

This phase of the project was focused on This phase of the project was focused on refining the phase one project for use in the refining the phase one project for use in the field, minimizing the device form factor and field, minimizing the device form factor and getting the system ready for use in the field.getting the system ready for use in the field.

15 months since the start of the project a 15 months since the start of the project a fully functioning radio was produced.fully functioning radio was produced.

It was so successful that no further It was so successful that no further development was needed.development was needed.

Phase II ContPhase II Cont

This radio only had a range between 4 This radio only had a range between 4 MHz and 400 MHz MHz and 400 MHz

data rates between 75 bps and 10 data rates between 75 bps and 10 Mbps. Mbps.

22 different wave forms in addition to 22 different wave forms in addition to GPS and cellular communications. GPS and cellular communications.

four channels programmed into it at four channels programmed into it at once as well as cellular and GPS at the once as well as cellular and GPS at the same time. same time.

A final contributor Joint Tactical A final contributor Joint Tactical Radio SystemRadio System

Unlike the other projects that ran from 1992-Unlike the other projects that ran from 1992-1995, JTRS was started in 1998.1995, JTRS was started in 1998.

Goals: to create a radio that will work in Goals: to create a radio that will work in harmony with many different other radios, harmony with many different other radios, both civilian and military, built in encryption, both civilian and military, built in encryption, and wideband networking software to allow and wideband networking software to allow the system to form ad hoc wireless networks. the system to form ad hoc wireless networks.

The key architecture used in this projected is The key architecture used in this projected is the Software Communications the Software Communications Architecture(SCA). Architecture(SCA).

Software Communications Software Communications ArchitectureArchitecture

SDR What does it take to make SDR What does it take to make one?one?

Software Defined Radios are made Software Defined Radios are made up of: up of:

programmable gate arrays programmable gate arrays Digital Signal processorsDigital Signal processors General processorsGeneral processors An antennaAn antenna A digital to analog converter and an A digital to analog converter and an

analog to digital converteranalog to digital converter

How do they work?How do they work? In the case of a receiverIn the case of a receiver The antenna receives a signal and passes The antenna receives a signal and passes

it through the analog to digital converter.it through the analog to digital converter. The result from the converter is passed to The result from the converter is passed to

the digital signal processors.the digital signal processors. The software is left in charge of every The software is left in charge of every

other function for establishing and other function for establishing and maintaining a connection, such as maintaining a connection, such as modulation/demodulation, frequency modulation/demodulation, frequency selection, and encryption. selection, and encryption.

A transmitter simply works opposite to the A transmitter simply works opposite to the way a receiver does. way a receiver does.

One ExampleOne Example

SDR, Why Use It?SDR, Why Use It?

FlexibilityFlexibility Can be updated on the flyCan be updated on the fly InteroperabilityInteroperability Easier to upgrade by a non-technician Easier to upgrade by a non-technician

using an update bundle.using an update bundle. Minimal infrastructure requirements for Minimal infrastructure requirements for

use in the fielduse in the field Effective for setting up ad-hoc networksEffective for setting up ad-hoc networks

SDR the downsidesSDR the downsides

SDR is often referred to as a silver bullet to SDR is often referred to as a silver bullet to many networking problems without any many networking problems without any attention being paid to the effort involved.attention being paid to the effort involved.

For example, the problem with trying to set For example, the problem with trying to set up a single unifying network.up a single unifying network.

The competitor’s paradox. The competitor’s paradox. The potential for knocking out other networks The potential for knocking out other networks

with accidental misconfiguration by a user.with accidental misconfiguration by a user. Problems with multiple service levels, and Problems with multiple service levels, and

fraud.fraud.

Downside ContDownside Cont

Security Issues in:Security Issues in: AuthenticationAuthentication AuthorizationAuthorization MisuseMisuse Verification of validity of software Verification of validity of software

updatesupdates

Downsides ContDownsides Cont

Implementation and switchover Implementation and switchover costs:costs:

The upfront unit costs are higher The upfront unit costs are higher than with ordinary hardware radios.than with ordinary hardware radios.

Sometimes customers pay for more Sometimes customers pay for more flexibility than they actually need.flexibility than they actually need.

The sunk cost associated with legacy The sunk cost associated with legacy equipment that is no longer usedequipment that is no longer used

Limited advancementLimited advancement

Even with Software Defined Radio Even with Software Defined Radio technology advancing rapidly, many technology advancing rapidly, many of the technologies it is built upon of the technologies it is built upon are not advancing nearly as quickly.are not advancing nearly as quickly.

Moore’s law has helped immensely Moore’s law has helped immensely with processing and memory.with processing and memory.

Limits on front-end technologies and Limits on front-end technologies and RF capabilities.RF capabilities.

Where could SDR technology Where could SDR technology Lead? Lead?

• The ultimate potential of SDR technology is realized within The ultimate potential of SDR technology is realized within adaptive array antennas. adaptive array antennas.

• These intelligent antennas first must detect which direction These intelligent antennas first must detect which direction a signal is coming from, and then adapt its radiation pattern a signal is coming from, and then adapt its radiation pattern to allow for optimum communication conditions through the to allow for optimum communication conditions through the use of beam forming.use of beam forming.

• Beam forming is using several antennas together to utilize Beam forming is using several antennas together to utilize constructive interference to generate an approprate constructive interference to generate an approprate radiation patternradiation pattern

• SDR technology allows a radio to be controlled entirely by SDR technology allows a radio to be controlled entirely by software, from this point, system learning and algorithms software, from this point, system learning and algorithms can be introduced into the radios using methods already can be introduced into the radios using methods already applied in artificial intelligenceapplied in artificial intelligence

MIMOMIMO

Multiple Input Multiple Output devices.Multiple Input Multiple Output devices. These are a class of intelligent antenna.These are a class of intelligent antenna. This type of device uses an array of This type of device uses an array of

intelligent antennas at both ends of the intelligent antennas at both ends of the link. This will allow both the sender and link. This will allow both the sender and the receiver to adapt to changing the receiver to adapt to changing environmental conditions and environmental conditions and ultimately to create the optimum ultimately to create the optimum communication environment.communication environment.

In ConclusionIn Conclusion Software Defined Radios employ a technology that will Software Defined Radios employ a technology that will

ultimately bring a great deal of flexibility and adaptability to ultimately bring a great deal of flexibility and adaptability to the networks of the future.the networks of the future.

As many benefits as they provide, the technology still has a As many benefits as they provide, the technology still has a long way to go before it finds its way into cellular handsets long way to go before it finds its way into cellular handsets that can exploit the absolute potential of SDR.that can exploit the absolute potential of SDR.

SDR serves as an enabling technology for intelligent radios SDR serves as an enabling technology for intelligent radios and MIMO devices.and MIMO devices.

Any Questions?Any Questions?

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