Cognitive Radio System Analysis Using MATLAB

8/10/2019 Cognitive Radio System Analysis Using MATLAB

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 4, Issue 3, March 2014)

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Cognitive Radio System Analysis Using MATLABTushar D. Mohite1, Dr. M. S. Gaikwad2, Prof. S. B. Gholap3

1,2,3Dept. of Electronics and Telecommunication Engineering STESs Sinhgad Institute of Technology, Lonavala,

University of Pune, India

Abstract Demand of wireless communication is

increasing day by day, this increasing demand put so many

limitations on the use of radio spectrum. Spectrum

utilization survey shows that entire spectrum is not used so

many times. Because of this radio spectrum is underutilized.

This underutilization can be minimized by using Cognitive

radio (CR). Spectrum sensing in cognitive radio helps to

find out this underutilized bands of spectrum (spectrum

holes). With the help of cognitive radio technology spectrumutilization can be increased efficiently. A conventional radio

always operates in particular communications mode always

follows the similar procedure and either succeeds or fails at

a task given to it. In contrast, a cognitive radio, can use

knowledge of radio technology and other related factors to

reason about a failed attempt to satisfy a goal and attempt

alternate courses of action depending upon the situations.

Cognitive radio (CR) development will change the world of

wireless communication. In the field of cognitive radio to

study the roles of knowledge representation and reasoning

technologies we have generated experimental cognitive

radio model using MATLAB. In this paper, we studied the

idea of simulating a cognitive radio system to recycle vacant

spectrum to increase capacity of the system. Cognitive radio

(CR) development will change the world of wireless

communication.

I ndex Terms Radio spectrum, Spectrum sensing,

Spectrum utilization, Spectrum holes, Cognitive radio (CR),

MATLAB.

I.INTRODUCTION

The Federal Communications Commission (FCC) has

stated that, depending on space (geographical location)

and time, most of the licensed bands are underutilized.

Subsequently, due to the always growing need for

wireless communication, cognitive radio systems have

been established to increase the spectrum utilizationefficiency by allowing access of empty frequency bands

to secondary users. The presence and absence of primary

user is decided by core function behind the access which

is proficient by spectrum sensing.

Now a days almost radio systems are operate in

specific frequency band. And they are not aware of their

radio spectrum environment.

Survey of spectrum utilization shows that all the

spectrum in space or time is not utilized [1]. Therefore an

intelligent radio is required that can sense and understand

its spectrum environment, identify temporarily emptyspectrum and use it, provides higher bandwidth services

and increase efficiency of spectrum [2].

We can achieve all of this with the help of cognitive

radio. This cognitive radio is able to sense the spectrum

to find the spectrum holes and this can take quick

decision about accessing spectrum. Cognitive radios havethe potential to access un-used spectrum gaps to increase

efficiency of spectrum and to provide wideband services.

Figure 1. Graph of spectrum utilization at Berkeley Wireless

Research Center

II.BACKGROUND

A basic cognitive cycle consist of following three

basic tasks

Spectrum Sensing- Spectrum sensing is the skill to

measure, sense and be aware of the parameters associatedto the characteristics of radio channel, availability of

spectrum and transmit power, interference and noise,

operating environment of radio, application and

requirements of user etc. This is done through Time,

Space (geographical) and Frequency [3].

Spectrum Analysis- Spectrum Analysis is related tospectrum sensing which is analysing the condition of

numerous factor inside and outside of the radio

environment such as frequency spectrum use by nearby

devices, user activities and network state and discovering

the best communication protocol and altering channel orfrequency consequently [5].


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Figure 2. Cognitive Cycle

Decision making- Spectrum Decision Making calls for

reconfiguration for the channel and protocol required for

constantly adapting to mobile changing environments

and adjustment of output power or make alteration oftransmission parameters (such as modulation formats)

and characteristics by the Cognitive radio devices.

A.Why Cognitive Radio

Cognitive radios are built on software-defined radio(SDR) technology [1]. Which involves authorities in

digital communication, wireless networks, and so manyother fields. While providing greater flexibility and

access to the spectrum the SDR system also respect the

rights of the obligatory license holders. For revolutionize

the telecommunications industry, Dynamic Spectrum

Access (DSA) networks employing cognitive radios is

the key by the given request for more bandwidth and the

quantity of underutilized spectrum. Apart of which we

use spectrum resources, to design wireless systems and

services.

III.

KEY BENEFITSCR offers optimal variety in coding, frequency,

modulation, power, time, space, polarization and so onwhich leads to

Efficiency of spectrum- This will allow upcoming

demand for spectrum to be encountered and is the basic

purpose behind implementation of CR.

High bandwidth service- Demand of wireless serviceis continuously increasing which will be fulfilled by the

implementation of CR.

Graceful Degradation of Services - When conditions

are not ideal, a graceful degradation of service is

provided, as opposed to the less desirable complete and

sudden loss of service.

This feature of CR is very important in providing

services to the users especially when they are mobile andthe base stations in contact are constantly changing.

Quality of Service improvement- availability and

reliability of wireless services will improve from theusers point of view.

Benefits to the Service Provider- Because of increased

information transfer rates more customers attracts

towards the services.

Future-proofed product- A CR is able to modify

services, protocols, modulation, spectrum etc. without the

need for a user or manufacturer to upgrading to device.

Common hardware platform-Manufacturers does not

need to build several hardware variants, instead using a

single common platform to run a wide range of software.Emergency communication services- At the time of

major incidents joint operations would greatly beneficial

to police, fire, ambulance could be linked together in one

radio.

Benefits to the Licensee- IN this licensees would be

allowed to rent a portion of their spectrum rights to other

parties and make money.

IV.TECHNIQUE

We explained the idea of simulating a cognitive radio

system to recycle unused spectrum to increase the total

system capability. At the time of work, we tried nearly all

the available simulation procedures but unluckily no one

had revealed the precise technique and maximum of thesimulations based on some specific hardware platforms.

Previously available simulation techniques, simulated

only some particular parts of cognitive radio technology

like MIMO techniques, spectrum sensing, spectrum

scanning etc. We have implemented basic cognitive radio

(CR) using MATLAB model. There is no other simple

technique available to implement CR system using

MATLAB.

A.Simulation Procedure

Initialization- Initialize the 5 Carrier Frequency

Bands for Users and also initialize MessageFrequency and the Sampling Frequency.

Modulation- Modulates user data over the

respective frequency band using amplitude

modulation

Adder- Addition of all the modulated signals to

produce a carrier signal

Periodogram-For estimation of the power spectral

density.

Allocation of unoccupied slot- When a new User

arrives he is allotted to the first spectral hole.

Emptying a slot-If all the slots are engaged ask user

to empty a specific slot. Addition of noise-Amount of Noise to be added.

Attenuation-Percentage of Attenuation Required


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B.Applications of cognitive radio

There are various new generation wireless applications

and services in which we can add CR capabilities. Some

of this applications are as follows

Future (upcoming) internet services- upcoming

internet services supporting wide band, high data rates,

and seamless quality of service guarantee for various

multimedia and other applications.

Multimedia downloads in mobile- To download music,

video and other files in portable player, requires

moderate data rates and good coverage.

Communication during emergency services- we

require localized coverage and moderate data rates at the

time of emergency for communication. (Military,

surveillance etc.)

Wireless multimedia services- For audio, video

distribution using wireless system requires higher data

rates.

V.MATLAB SIMULATION RESULTS

Here, suppose 1st, 3

rd and 5

th primary users are

present and 2nd

and 3rd

primary users are not present

as shown in figure 3.

After that the CR system will search for the

Spectrum holes in the spectrum and automatically

assign it to the secondary users one by one, as

shown in figure 4 and 5. If all the spectrum holes occupied by the secondary

users then all the Spectrum bands are in use asshown in figure 5.

After that we take Signal to noise ratio (SNR) is

10dB, and the result is shown in figure 6.

Finally we attenuate the received signal by 15% and

the result is shown in figure 7.

Figure 3. Used bands and unused bands

Figure 4. 2ndunused band assigned to the secondary user 1


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Figure 5. 3rdunused band assigned to the secondary user 2

Figure 6. Signal to noise ratio (SNR) = 10 dB

Figure 7. Attenuation of received signal by 15%

VI.CONCLUSION

CR technology proposed to increase spectrum

utilization by allowing dynamic spectrum access at a run

time. By using spectrum sensing cognitive radio find out

the spectrum holes and secondary users are allowed touse that spectrum holes as long as it does not interfere by

primary (licensed) users. In this paper idea of simulating

a cognitive radio system to recycle unused spectrum to

increase the total system capability is explored by using

MATLAB. Simulation results shows that how cognitive

radio works.

REFERENCES

[1] J. Mitola and G.Q. Maguire, Cognitive radio: making softwareradios more personal, IEEE Personal. Communication

[2] S. Haykin, Cognitive radio: Brain-empowered wireless

communications, IEEE J. Select. Areas Commun., Feb. 2005

[3] Pedram Paysarvi-Hoseini, Norman C. Beaulieu Optimal

Wideband Spectrum Sensing Framework for Cognitive RadioSystems IEEE Transaction on Signal Processing, March 2011

[4] Ahmad Ali Tabassam, Muhammad Uzair Suleman, Sumit Kalsait

and Sheheryar Khan Building Cognitive Radios in MATLABSimulink A Step Towards Future Wireless Technology IEEE

2011 Wireless Advance[5] Danijela Cabric, Shridhar Mubaraq Mishra, Robert W. Brodersen

Implementation Issues in Spectrum Sensing for Cognitive

Radios Berkeley Wireless Research Center, University ofCalifornia, Berkeley

[6] Majid S. Naghmash, Mohd Fadzil and Ain Chye Yin Hui FPGAImplementation of Software Defined Radio Model based

16QAM European Journal of Scientific Research

Cognitive Radio System Analysis Using MATLAB

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