Cognitive Radio Spectrum Sensing

Under the guidance of : Mr. Sandeep Sharma Designation : Research/Faculty Associate

ANUPAM K YADAV 11/IEC/021Gautam Buddha University

CONTENTS• Introduction• Application• Architecture for CRC Network• Types of spectrum Sensing• Energy Detection Mathematical model• Algorithm Used for Detection of spectrum Holes• Results and simulations• References

Cognitive Radio : It’s a Radio technique that aims to utilize Radio Spectrum more efficiently by Intelligently exploiting licensed spectrum.

Need to exploit spectrum :

There is increasing number of smartphones & laptops every year which have different QoS requirements :

• Web browsing• Faster Internet• Multimedia downloads

Applications

In CR Network we provide services to all users at same time :

• Use of VACANT bandwidth :• STs can use those spectrums which are

not occupied by (primary receivers) PRs.

• SHARING of bandwidth :• STs can share spectrum as long as they do

not interfere with PRs

There are two types of Radio resources in CR –Network : 1. Radio resource ( licensed band )RR Small bandwidth, Hight Tx power, High reliability.

2. Cognitive Radio resource ( Unlicensed Band) CRRBroad Bandwidth, low Tx Power, low reliability.

Challenge : Is to jointly utilize both the bands to increase system performance.

Non-Cooperative Architecture (standalone )There are two different interfaces operating at licensed and unlicensed band.

• Power limited C-RR is used for Users near the MACRO Cell BS, while it uses licensed RR for users who are further away.

• Small Cell they use CRR to cover traffic hotspots and bridges the coverage gaps.

They offer High capacity

Cooperative architectureAlso uses both licensed and CRR .Have longer range of communication as compared to non cooperative.

• Relay is deployed for better coverage & capacity. It can communicate with BS using licensed RR & can provide local coverage using CRR. It works in duplex way.

• It also uses the Cognitive RR to form Virtual Antenna Array.

Types of spectrum Sensing

Energy Detection mathematical Model• We calculate energy of receiving signal to find the presence of primary user.

• In spectrum the primary user is present when calculated level of incoming energy level is more than threshold energy level.

• Also we compare the output of energy detector with a threshold which depends on noise floor and signal is detected.

• Energy detection is a non-coherent detection technique which do not need prior knowledge about primary user as required by other filters, so it has relatively less complexity as compared to other spectrum sensing.

Algorithm Used for Detection of spectrum Holes

• In this paper PSD is used for detection of spectrum holes. Here we can compare values of PSD for different channels and can estimate spectrum holes.

• PSD is also used for modulation of incoming input signals at different channel with different carrier frequencies.

• Then this modulated signal is multiplexed where noise may or may not corrupt the signals. At the receiver end, PSD from different channels is calculated.

• And lastly, the threshold power level is compared with calculated power for the presence of primary user.

Results and Simulations

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References• Juan Andrés Bazerque, Georgios B. Giannakis, “Distributed SpectrumSensing For

Cognitive Radio Networks By Exploiting Sparsity”, IEEETransactions On Signal Processing, Vol. 58, No. 3, March 2010.

• S.Haykin, “Cognitive Radio: Brain-Enpowered Wireless Communications,” IEEE JSAC, vol. 23, no. 2, Feb. 2005,pp. 201–20.

• Spectrum Sensing for Cognitive Radio. By Simon Haykin, Life Fellow IEEE, David J. Thomson, Fellow IEEE, and Jeffrey H. Reed, Fellow IEEE

• Takeshi Ikuma and Mort Naraghi-Pour (2008), “A Comparison of Three Classes of SpectrumSensing Techniques”, IEEE GLOBECOM proceedings.

• F. F. Digham, M. S Alouini and M.K Simon, “On the energy detection of unknown signals over fading channels”, in Proc. IEEE International Conference on Communication (ICC003), pp. 3575-3579, May 2003.

THANK YOU