Introducing Adaptive and Cognitive Radios

8/6/2019 Introducing Adaptive and Cognitive Radios

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First presentation of Research


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Introducing Adaptive and Cognitive Radios

Joe Mitola of Mitre Corporation and Wayne Bonser of Air ForceResearch Labs were the visionaries who started this organizationand brought the industry together to work these hard designproblems, and to begin establishing the new standards it wouldrequire.

He recognized that it is feasible for a radio to become aware of itsuser, aware of its network (choices and features), and aware of itsspectral environment.

In fact, it could then be adaptive, and ultimately could have thesoftware to learn various adaptations to its current environment that

are desirable support to the user, network, operators, spectrumowners, and regulators.

Dr. Mitola introduced the terms aware, adaptive, and idealCognitive

Radio (iCR) to reflect the different levels of cognitive capability.


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Cognitive and adoptive radio

the cognitive meaning which is related to thinking, reasoning,

and remembering

is a smart radio that has the ability to sense the external

environment, learn from the history, and make intelligent

decisions to adjust its transmission parameters according to thecurrent state of the environment.

It is important to remark that a CR is not what in the literature is

called adaptative radio. A CR can not only adapt to the best

spectrum settings but also store past data, learn, and positively

evolve. Indeed, adaptation is a subset of CR characteristics, andan adaptative radio is not necessarily cognitive at all.


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Cognitive radio..

Two main accepted characteristics

(1) Cognitive capability, which refers to

sense the information from its radio

environment and identify the best andmore appropriate spectrum and

operating parameters and

(2) Reconfigurabilitythat enables the

radio components to be dynamicallyprogrammed according to cognitive

decisions.


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Cognitive radio network

is a network made up of CRs

by extending the radio link

features to network layer

function and above. By means

of CRs cooperation, the

network is able to sense its

environment, learn from the

history, and accordingly decide

the best spectrum settings.


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Simple scenario


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Support for the Network

Radios, just like computer networks, generally have a full protocol

stack running from the physical layer to the application.

Of these layers, only the physical and MAC layers are intimately

designed and specific to radio/wireless protocols.

the physical layer and MAC layer are very specific to radio/wirelessapplications, and optimization of these layers as a real time activity

based on measurements of local spectrum is the dominant part of

Cognitive Radio research and design at this time.

The radio can also select the most appropriate network for the

service requests of the user. For example, the radio can select a

Bluetooth network access for a local printer, rather than using the

WiFi access point, while using the WiFi access point for internet

database searches. Similarly, voice or video traffic can be provided

through the most appropriately resourced network.


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Support for the Network Operator

Some network operators have recognized the benefit of

convergence of wireless services delivered through multiple access

networks. Thus, cellular, WiFi, WiMAX, Bluetooth, broadcast digital

audio, and video are bundled so that the service provider selects

which resource is most efficiently able to accommodate a userscurrent needs, and that the transition across different network

access is both seamless and economical for the user and for the

network operator


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Support for the Regulatory Organization

Nearly 200 different countries has different regulatory rules andprocedures for designing radios, defining spectral mask of eachradio application waveform, manufacturing radios, and acquiringrights to use various parts of spectrum.

Cognitive radios include a policy engine. The policy engines role isto be aware of the utilization rules for all countries where theequipment is licensed, and to assure that the radio only operates inthose allowed modes in those geographic regions.

Other policies: network usage policy, network operator policy, andeven manufacturer policy.


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Support for the Spectrum Owner & Users

Measurements suggest that cognitive radio systems should be ableto increase traffic density at ratios between 7:1 and over 20:1

In addition to supporting significant increase in users, use ofspectrum awareness and adaptation techniques can also indicateinterference properties, multipath properties, signal strength, and inturn, these real time measurements can guide adaptation of thetransmission waveforms to be more robust, providing the userimproved quality of service in multiple dimensions.

Cellular connectivity may swap with WiFi or WiMax connectivity asthe user moves about his activities.

Since the availability, range, throughput, and economics are vastlydifferent models, users will come to expect the system to make costeffective and performance sensitive decisions. Eventually users willexpect these decisions to be automatic.


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Economics of Cognitive Radio

Many things are technically possible, but what justifies

the time and effort to advance various degrees of

cognitive functionality into the radio network, either in

subscriber equipment or in the network infrastructure is

the economics


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Value ofSpectrum

Spectrum is the lifeblood of communication systems. The telecommunications industry is now a 1 Trillion(1012) dollar per

year industry,6 and the wireless part is growing very rapidly, while

the wired telecommunication services are experiencing a relatively

flat business.

in many rural areas, a single broadcast TV source may be nearly

200 miles away and there is little or no local TV service) there are

significant opportunities to provide internet and telecommunication

services using this under-utilized spectrum

.


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Smart Antennas

One way to get enhanced spectral density and user density is withsmart antennas.

Smart antennas can provide narrow beam patterns for eithertransmitter or for receiver or both. In the Industrial Scientific andMedical (ISM) band frequencies of 2.4 GHz, practical narrow beamantennas can provide 9 dB of gain, and reduce interference to othercommunication activity off the sidelobes of the antenna beampatterns

Smart antenna techniques may be economically costly for certainapplications, and may be impractical for certain form factors


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MIMO

Multi-Input Multi-Output (MIMO) is a communication technique inwhich the multipath properties of the channel are utilized to supportgreater data throughput

In a MIMO system, the transmitter transmits multiple channels ofdata traffic through multiple antennas; the receiver learns thechannel behavior between the transmitters multiple antennas andthe receivers multiple antennas, and uses signal processing tocompute what waveform was transmitted by each transmittingantenna, and the corresponding data stream.

In this way, the same frequency is reused in the same geographicregion to deliver greater amounts of data traffic than could beexpected from a single transmitting and receiving antenna (SISO)system. Some MIMO systems also have the ability to learn tosuppress interference from unrelated transmitters, further enhancingnetwork performance.


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Spectrum Subleasing, Sharing

In dense urban applications, there is opportunity to sublease

spectrum from spectrum owners whose loading is temporarily light.

Such owners can define access rules, and economics of such

transactions, as well as rules to take back spectrum should demand

or emergency arise. SDR Forum, IEEE, and others are working to establish standardized

protocols to enable such transactions.


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Architecture of a cognitive radio.

includes a cognitive function to

analyze existing spectrum

users, and measure properties

of its own communication

channels, and a set of rules expressed

through a policy engine which

define what the radio is

allowed to do, and what it is

not allowed to do..


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Scenario

Cognitive radios are aware of their surroundings and

bandwidth availability and are able to dynamically tune

the spectrum usage based on location, nearby radios,

time of day and other factors. This provides for a moreefficient use of the spectrum as well as reducing power

consumption, and enabling high priority communications

to take precedence if needed.


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Varied devices will be

able to detect other

radios around them andwork together to

optimize the use of

spectrum, allocate

resources and moreeasily communicate to

their peers.

Introducing Adaptive and Cognitive Radios

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