Cognitive Radio Thesis for Research Scholars.

Challenges Faced in Cognitive Radio.

Cognitive Radio Thesis can be framed based on following challenges faced in cognitive radio networks. We help to improve implementation process for cognitive radio thesis modules.

• Detection, false alarm and miss detection probability.
• Topology changes, Layer attack..
• Clustering.
• Manufacturing costs.
• Scalability.
• Channel allocation, Cooperative sensing.
• Fault tolerance, Handoff.
• QoS.
• Power consumption.
• Security, Sensing technique.

Dynamic Spectrum Access in Cognitive Radio.

Once the spectrum sensing is over the process of DSA is enabled. Bandwidth can be expanded and the unused spectral band is reduced.

Approaches of DSA:

• Command and control model.
• Exclusive use model.
• Open sharing model.
• Common access model.

Command and Control Model: Spectrum users can get spectrum in abundant. As the rule of spectrum access is in control this model.

Long Term Exclusive Use Model: It is used to decide who gets to own spectrum and the time duration of their usage. It also controls speed, frequency and bandwidth of spectrum. It is further divided into fixed and flexible use type.

• Fixed Use Type: the license type of primary users is fixed in this type.
• Flexible Use Type: in this type the license type can be changed.

Exclusive Use Model: Licensed and unlicensed user policy can be regulated by this model. There are two different models which gives efficient spectrum allocation and usages. They are long term exclusive use model and dynamic exclusive use model.

Dynamic Exclusive Use Model: It maintains the scale of time, space, frequency and dimension. It is further classified into three types that are used to manage marketing information.

• Secondary Market: It is also known as spectrum leasing. The rights of spectrum usage from primary user can be transmitted to secondary user.

• Homogeneous Multi Operator Sharing Via Real-Time Secondary Market: This model allows the primary user to share their spectrum with secondary users. The main positive aspect of this method is to assign client system and base station by making use of current technologies.

• Heterogeneous Multi Operator Sharing Via Real Time Secondary Market: Service providers like radio, cellular and TV broadcasting can share their spectrum through this model. It also gives guarantee for spectrum usage and allocation.