30-06-2012, 02:32 PM
COGNITIVE RADIO
[attachment=26307]
WHAT IS COGNITIVE RADIO
Cognitive radio is a paradigm for wireless communication
In which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently avoiding interference with licensed or unlicensed users.
This alteration of parameters is based on the active monitoring several factors in the external and internal radio environment such as,
Radio spectrum
user behaviour and network state.
SPECTRUM SENSING
In order to avoid interference the spectrum
holes need to be sensed
primary user detection, the most efficient way
Spectrum sensing techniques are divided into three categories
transmitter detection
cooperative detection
interference based detection
Transmitter Detection
signal from a primary transmitter is
locally present in a certain spectrum or not
three different approaches
– matched filter detection
– energy detection
– cyclostationary detection
Spectrum Management
capture the best available spectrum to meet user communication requirements
cognitive radios should decide on the best spectrum band to meet the QoS requirements over all available spectrum bands
management functions classified as
– spectrum analysis
– spectrum detection
Spectrum Sharing
providing the fair spectrum scheduling method
sharing is a major challenge in open spectrum usage
corresponds to MAC problems in existing systems
[attachment=26307]
WHAT IS COGNITIVE RADIO
Cognitive radio is a paradigm for wireless communication
In which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently avoiding interference with licensed or unlicensed users.
This alteration of parameters is based on the active monitoring several factors in the external and internal radio environment such as,
Radio spectrum
user behaviour and network state.
SPECTRUM SENSING
In order to avoid interference the spectrum
holes need to be sensed
primary user detection, the most efficient way
Spectrum sensing techniques are divided into three categories
transmitter detection
cooperative detection
interference based detection
Transmitter Detection
signal from a primary transmitter is
locally present in a certain spectrum or not
three different approaches
– matched filter detection
– energy detection
– cyclostationary detection
Spectrum Management
capture the best available spectrum to meet user communication requirements
cognitive radios should decide on the best spectrum band to meet the QoS requirements over all available spectrum bands
management functions classified as
– spectrum analysis
– spectrum detection
Spectrum Sharing
providing the fair spectrum scheduling method
sharing is a major challenge in open spectrum usage
corresponds to MAC problems in existing systems