23-08-2012, 12:43 PM
Cogniitiive Radiio: Generall Concepts and 802..22
[attachment=32495][attachment=32495]
The Concept
wiirelless communiicatiion iin whiich the transmiissiion or
receptiion parameters are changed to communiicate
effiiciientlly wiithout iinterfferiing wiith lliicensed users
parameter changes are based on the actiive moniitoriing
off severall ffactors iin the radiio enviironment (e..g.. radiio
ffrequency spectrum)
thiis approach iis enablled by sofftware-deffiined radiio
Background
most off the radiio ffrequency spectrum iineffiiciientlly
utiilliized
– cellullar network bands vs.. amateur radiio bands
spectrum utiilliizatiion depends stronglly on tiime and pllace
ffiixed spectrum allocatiion wastes resources
iimproved effiiciiency by allowiing unlliicensed users to
explloiit spectrum whenever iit woulld not cause
iinterfference to lliicensed users
Spectrum Sensiing 1/2
in order to avoid interference the spectrum
holes need to be sensed
– priimary user detectiion the most effiiciient way
spectrum sensing techniques are divided into
three categories
– transmiitter detectiion
– cooperatiive detectiion
– iinterfference based detectiion
Spectrum Management
needed to capture the best avaiillablle spectrum to meet
user communiicatiion requiirements
cogniitiive radiios shoulld deciide on the best spectrum
band to meet the QoS requiirements over all avaiillablle
spectrum bands
management ffunctiions cllassiiffiied as
– spectrum analysis
– spectrum detection
Spectrum Mobiilliity
the process where a cogniitiive radiio user exchanges iits
ffrequency off operatiion
target to use the spectrum iin a dynamiic manner by
allowiing the radiio termiinalls to operate iin the best
avaiillablle ffrequency band
seamlless communiicatiion requiirements duriing the
transiitiion to better spectrum must be maiintaiined
802..22 - Introductiion
IEEE workiing group aiimiing at constructiing Wiirelless
Regiionall Area Network (WRAN) workiing utiilliiziing whiite
spaces iin TV bands
the ffiirst standard based on cogniitiive radiios
diifferent approaches proposed
– centralized servers provide information on available channels in
the area of Access Point (AP)
– local spectrum sensing only, where the AP would decide
independently which channels are available
– combination of the previous approaches
802..22 - MAC Layer 2/3
no pre-determined channel (frequency, time,
code) for CPE to look for BS
at start-up CPE scans the TV channels and
builds a spectrum occupancy map
this information may be later sent to BS and is
also used by the CPE to determine where to
look for BS
[attachment=32495][attachment=32495]
The Concept
wiirelless communiicatiion iin whiich the transmiissiion or
receptiion parameters are changed to communiicate
effiiciientlly wiithout iinterfferiing wiith lliicensed users
parameter changes are based on the actiive moniitoriing
off severall ffactors iin the radiio enviironment (e..g.. radiio
ffrequency spectrum)
thiis approach iis enablled by sofftware-deffiined radiio
Background
most off the radiio ffrequency spectrum iineffiiciientlly
utiilliized
– cellullar network bands vs.. amateur radiio bands
spectrum utiilliizatiion depends stronglly on tiime and pllace
ffiixed spectrum allocatiion wastes resources
iimproved effiiciiency by allowiing unlliicensed users to
explloiit spectrum whenever iit woulld not cause
iinterfference to lliicensed users
Spectrum Sensiing 1/2
in order to avoid interference the spectrum
holes need to be sensed
– priimary user detectiion the most effiiciient way
spectrum sensing techniques are divided into
three categories
– transmiitter detectiion
– cooperatiive detectiion
– iinterfference based detectiion
Spectrum Management
needed to capture the best avaiillablle spectrum to meet
user communiicatiion requiirements
cogniitiive radiios shoulld deciide on the best spectrum
band to meet the QoS requiirements over all avaiillablle
spectrum bands
management ffunctiions cllassiiffiied as
– spectrum analysis
– spectrum detection
Spectrum Mobiilliity
the process where a cogniitiive radiio user exchanges iits
ffrequency off operatiion
target to use the spectrum iin a dynamiic manner by
allowiing the radiio termiinalls to operate iin the best
avaiillablle ffrequency band
seamlless communiicatiion requiirements duriing the
transiitiion to better spectrum must be maiintaiined
802..22 - Introductiion
IEEE workiing group aiimiing at constructiing Wiirelless
Regiionall Area Network (WRAN) workiing utiilliiziing whiite
spaces iin TV bands
the ffiirst standard based on cogniitiive radiios
diifferent approaches proposed
– centralized servers provide information on available channels in
the area of Access Point (AP)
– local spectrum sensing only, where the AP would decide
independently which channels are available
– combination of the previous approaches
802..22 - MAC Layer 2/3
no pre-determined channel (frequency, time,
code) for CPE to look for BS
at start-up CPE scans the TV channels and
builds a spectrum occupancy map
this information may be later sent to BS and is
also used by the CPE to determine where to
look for BS