Why Primary users (PUs) accept to share their own spectrum with secondary users (SUs)?
Dear Fatima,
welcome,
I will try to give a conceptual answer.
It is so that the frequency spectrum in certain area is limited. There is is only one frequency spectrum. The licensed users have full right to use the frequency band agreed upon. If the primary user utilizes this frequency spectrum with low efficiency, this will be great loss for this precious resources which must be utilized with the highest efficiency possible.
The primary users have spectrum holes in their utilization that can be exploited by other users which are the secondary users. If the technological facilities exist that enable the secondary users to exploit the frequency gaps of the primary users then why not. This is necessary for the
well fare of the society.
Now the technology exists which enable the coexistance of the primary and secondary users wit hoot interfering each other.
This technology is the cognetive radio. Connective radio senses the environment and determine the frequency gaps and exploit them without interfering with the existing active primary users.
It the demand growth on communication bandwidth which dictates to increase the utilization efficiency of the bandwidth.
Best wishes
Thank you Dr. Zekry for your response,
I would like to understand the charge policy defined to share that spectrum.
The PUs paid for the spectrum license and have the priority to access to the spectrum anytime. The SUs can access to that spectrum when it is not used.
So, the SUs take advantages from using a spectrum for free while the Pus paid the regulator. I did not get what will Pus gain from this collaboration? Otherwise all the users can be secondary.
Thank you
Dear Fatima,
welcome again!
I my self do not know what type of agreement between the primary and secondary users and how much is the compensation paid for the spectrum use. But one has to consider that the primary user is the ruling user and can communicate at any time any where covered by the licence.
It is an interesting point raised by your question and by search the web i found an interesting link:Conference Paper Auction-based spectrum sharing for multiple primary and seco...
Wish you success
Regulatory domain plays a vital role in the deployment of CR technologies and the foremost priority is that PUs should not get any kind of interference.
There can be some advantage for PU depending upon scenario...for instance think that PU want to send its data to a destination beyond it reach. SUs can act like a relay and in return can use the PUs spectrum share meeting the interference constraint.
So usually a win-win situation for PUs.
Thank you Dr. Alam Khan for your reply. The relay idea is an interesting point as nothing is for free.
It started from low utilization of TV band. TV band has a nice RF propagation characteristics, therefore, everyone would love to use it. Sporadic utilisation of TV band by primary users (licensed users) led researchers and regulatory organisation to devise a techinque that could exploit underlitlised TV band to reduce the loss of spectrum. All the modern day wireless networks that shall employ cognitive radio shall be based on some reward mechanism.
Thank you for yur answer,
yes, right, my concerns are about these reward mechanisms.
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