channel management in ieee 802.22 wran systems
TRANSCRIPT
Cognitive Radio Networks
Praseetha KR
Channel management in IEEE 802.22 WRAN Systems
A paradigm for wireless communication
Avoid interference with licensed or unlicensed users
Transmission or reception parameters are changed by either a network or a wireless node
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Full Cognitive
Radio (Every
possible observabl
e paramete
r)
Spectrum Sensing
Cognitive Radio
(only RF spectrum
)
Licensed Band Cognitive Radioeg: IEEE 802.22
WRAN which will operate in
unused television channels
Unlicensed Band Cognitive
Radioeg: IEEE 802.15
Task group 2 specification
which focuses on the
coexistence of IEEE 802.11
and Bluetooth
Depending on the parts of the spectrum available
Depending on the set of parameters
Channel management in IEEE 802.22 WRAN Systems
Share the geographically unused TV
spectrum in a rural environment to provide
Broadband access
Channel management in IEEE 802.22 WRAN Systems
Specify both PHY & MAC layer functionalities Infrastructure based Broadband access BS (base station) controls CPE (consumer
premises equipment) Operates in TV band Dynamic channel management is the key
feature
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Resource utilization
QoS (Quality of Service)
Incumbent monitoring
Channel management in IEEE 802.22 WRAN Systems
In US,
Communication between BS and CPE
Available for TV
Broadcast
BS
Up to 255 CPE
units
TV channel 6-8Mhz, 17-30 km ,Half –duplex,
TDMA1.5 Mbps
downstream384 kbps upstream
VHF
UHF
10 channels54-216 MHz
37 channels470-758 MHz
Channel management in IEEE 802.22 WRAN Systems
Types of incumbent user operations in TV band:
• Analog TV• Digital TV• Wireless microphone
Guard bands
User protection rules by Regulatory bodies
Channel management in IEEE 802.22 WRAN Systems
Geo-Location Database
Incumbent Database
Spectrum Sensing
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
The geographic location of the BS and CPE has to be known to determine the permissible channels at a given location
Devices find their location through Global Positioning System
Channel management in IEEE 802.22 WRAN Systems
Maintained by Regulatory bodies in different places to keep information of licensed users
Should be available at no operational cost
Incumbent Database
REQUEST(Current location of BS
and CPE)
List of available TV channels + max
Radiation power of CPE
802.22 WRAN
To detect presence of incumbent users
Both BS and CPE scans TV channels independently
SSF tunes channels & reports to SM
Channel management in IEEE 802.22 WRAN Systems
Spectrum Manager uses a two-step channel decision process
Channel management in IEEE 802.22 WRAN Systems
Channel classification start
Incumbent DB
exist?
Available channels
Is channel sensed?
Decision considerations:-Empty or not-own WRAN cell used-WMP used-TV used-Other WRAN cells used-Cumulative empty time-History-Local regulatory
end
Disallowed
Operating
Backup
Candidate
Protected Unclassified
Unavailable channels
Incumbent protection
requirements
Channel availabilit
y?No
No
No
Yes
Yes
Yes
SM
Incumbent db
Channel Classification Procedure
Protected
Operating
Backup
Candidate
Disallowed
Unclassified
channels in which incumbent users or WRAN operations has been detected
The channel currently in operation for WRAN
channels that have been cleared to become the operating channel
channels that are candidates to become a backup channel
Channels precluded by the operator due to operational or local regulatory constraints
Channels that have not yet been sensed
Infrequent
Every 2s
Every 6s
Infrequent
Channels CharacteristicsRe-sensing
time interval
Channel management in IEEE 802.22 WRAN Systems
The BS and CPE should maintain same list of backup channels
WRAN system provides various channel list exchange information elements in the form of MAC Management messages
Channel management in IEEE 802.22 WRAN Systems
BS CPE Embedded mode:
downstream channel descriptor (DCD) message Explicit mode:
►Channel terminate request/response (CHT-REQ/RSP)
►Channel switch request/response (CHS-REQ/RSP)
►Channel quiet request/response (CHQ-REQ/RSP)
►Channel occupancy update (CHO-UPD)
Between BSs
Using Coexistence Beacon Protocol (CBP)
Channel management in IEEE 802.22 WRAN Systems
1st international standard that uses Cognitive Radio technology is IEEE 802.22 WRAN standard, which is used to provide broadband access in rural areas from unused TV bands
The key features of WRAN are Incumbent protection and Dynamic channel management
Channel Classification using geo-location information, incumbent database and by spectrum sensing
For coexistence, channel information should be exchanged & updated between BSs and between BS & CPE
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems
Channel management in IEEE 802.22 WRAN Systems