Dear Jannat,

welcome,

Cognitive radio is used for efficiently use of available wireless communication bandwidth where there is primary users and secondary users. The primary users are licenced users while the secondary users are only allowed to use such bandwidth when it is empty. So the secondary users has to sense the wireless activity and find out a vacant bandwidth in order to transmit there signals.

If in a region there is only one type of users such as wsn one do not need to sue cognitive radio except that this region may have other active users in the same bandwidth. The use of connective radio may be to avoid interference.

Concerning the reduction of the power consumption in wsn it is achieved by making the hop as short as possible. In addition to increasing the bandwidth of the communication channels.

This can be conceptually understood by considering the Shanon theory of the communication channel:

C= B log2(1+S/N ),

For the same C in order to reduce S, one has to increase B, and since S= the sent power multiplied by the path loss , one has to decrease the path loss by decreasing the hop distance. One can also reduce S by decreasing the noise N which means increasing the receiver sensitivity.

Best wishes

Dear Jannat :

Cognitive radio can be integrated with wireless sensors, it can overcome the many challenges of the current WSNs. CR has the ability to know the unutilized spectrum in a license and unlicensed spectrum band, and utilize the unused spectrum opportunistically. The primary users (PU) have the right to use the spectrum anytime, whereas secondary users (SU) can utilize the spectrum only when the PU is not using it.

This nature of CR gives potential advantages to WSNs by:

1- increasing the communication reliability.

2- improving the energy efficiency (power waste reduction).

3- packet loss reduction.

4- high degree of buffer management.

regards.

thanks a lot prof. Abdelhalim Zekry and dr. Ali Adnan

your answers clarify the idea of cognitive radio to me.