Cogniitiive Radiio:

Cognitive RadioGuided by:ADITI TOKDAR

:

SUBMITTEDBY:

SOHAG MAJEE*(13000312139)SOURA MONDAL*(13000312145)LAXMI DAS*(13000313118)NIHAL SINGH RATHORE*(13000312095)

INTRODUCTION: Cognitive radio is one of the most promising solutions to spectrum-scarcity problem. In cognitive radio networks, the most important requirement is to avoid interference between the primary and secondary users. However, different primary users require different levels of protection. Moreover, the extent of interference that a primary user can tolerate may change over time. Therefore, a secondary should adapt its operating parameters according to a primary user's changing requirements.

TYPES OF COGNITIVE RADIO:Two main approach:

Full Cognitive Radio (“Mitola Radio”) every possible parameter taken into account.

Spectrum Sensing Cognitive Radio only radio frequency spectrum considered Also division based on frequency spectrum

Licensed Band Cognitive Radio

Unlicensed Band Cognitive Radio

Main Functions

• Spectrum sensing• Spectrum

management• Spectrum mobility• Spectrum sharing

Spectrum Sensing: In order to avoid interference the spectrumholes need to be sensed– primary user detection the most efficient way spectrum sensing techniques are divided intothree categories transmitter detection cooperative detection interference based detection

Spectrum ManagementIt is needed to capture the best available spectrum to meetuser communication requirements cognitive radios should decide on the best spectrumband to meet the QoS requirements over all availablespectrum bands management functions classified as spectrum analysis spectrum detection

Spectrum Mobility:The process where a cognitive radio user exchanges itsfrequency of operation target to use the spectrum in a dynamic manner by allowing the radio terminals to operate in the bestavailable frequency band.

Spectrum Sharing. providing the fair spectrum scheduling method. . sharing is a major challenge in open spectrumusage.. corresponds to MAC(Media access control) problems in existingSystems.

3650-3700 MHz: unlicensed operation of high power, contention based protocols below 900 MHz: unlicensed opportunistic operation in the TV broadcast bands

5470-5725 MHz: adding 255 MHz to the U-NII band

902-928 MHz: ISM band

2400-2483,5 MHz: ISM band

5150-5350 MHz: U-NII band

5725-5825 MHz: U-NII band

1900-1920 MHz: unlicensed PCS

(1-5)GHz: LAN & WAN

FREQUENCIES:

APPLICATIONS:

Noise UncertaintyThe detection sensitivity can be defined as the minimum SNR at which the primary signal can beaccurately (e.g. with a probability of 0.99) detected by the cognitive radio and is given by ,

γ =Where N = the noise power, Pp = transmitted power of the primary user, D = the interference range of the secondary user, and R = maximum distance between primary transmitter and its corresponding receiver.

Block dia of SDR(Software defined Radio) & CR(Cognitive Radio)

MAC(MEDIA ACCESS CONTROL) LAYER: based on cognitive radio technology consists off two structures:1) FRAME

2) SUPER FRAME: Superframes are sent through every vacant TV channel.

WORKING PRINCIPLE: 1)No pre-determined channel (frequency, time,code) for CPE to look for BS. 2)At start-up CPE scans the TV channels andbuilds a spectrum occupancy map. 3)This information may be later sent to BS and isalso used by the CPE to determine where tolook for BS.

1)MAC layer will perform sensing in either in-band or out-of-bandMeasurements.

2) Both of these are further divided into: fast sensing (under 1ms per channel). fine sensing (about 25 ms per channel)

is done if the BS feels thatmore detailed sensing is needed.

SUPERFRAME

COGNITIVE RADIO

3.1.2. Open Sharing Model:

Open sharing model is also known as open spectrum model, which has beensuccessfully applied for wireless services .There are three types of spectrum commons: UNCONTROLLED-COMMONS: When a spectrum

band is managed and uses theuncontrolled commons model, no entity has exclusive license to the spectrum band.

MANAGED-COMMONS: Managed-commons represent an effort to avoid the tragedy of commons by imposing a limited form of structure of spectrum access. This is a resource which is owned or controlled by a group of individuals or entities and it is characterized by restrictions on when and how the resource is used.

Hierarchical Access Model:In hierarchical access model, SUs use the primary resources such that the interference to the PU islimited. There are three approaches under this model: INTERWEAVE:The inter-weave model is based on the idea of on

opportunistic re-use the spectrum in the spatial domain i.e., the primary spectrum is utilized by CRs in the geographical area where primary activity is absent. UNDERLAY: Simultaneous cognitive and non cognitive transmissions

are allowed as long as the interference level at the primary user side remains acceptable. Exceeding the predefined tolerable interference threshold may degrade dramatically the primary signal.

OVERLAY: non cognitive users share knowledge of their signal codebooks and messages with the cognitive users. Thus, the cognitive devices may enhance and assist the non cognitive transmission rather than vying for spectrum access.

Fig. shows where “CR 1” can ideally serve some of the SUs because no PU activity is

present in its proximity.

THANK YOU