Evaluation of Channel Assembling Strategies with Single-Class Users in Cognitive Radio

Networks

Ebenezer Esenogho

Supervised by Dr. Tom Walingo

Discipline of Electrical, Electronic and Computer Engineering.

University Of KwaZulu-Natal.

Centre for Radio Access and Rural Technologies

OUTLINE

INTRODUCTION Cognitive Radio. Cognitive Radio Network. Channel Assembling. CHANNEL ASSEMBLING STRATEGIES & RELATED WORK MOTIVATION SYSTEM MODEL/ARCHITECTURE ALGORITHMS RESULTS AND DISCUSSIONS CONCLUSION FUTURE WORK

INTRODUCTION

Cognitive Radio. Cognitive Radio Network. Channel Assembling.

RELATED WORK AND PROPOSED CHANNEL ASSEMBLING STRATEGIES

RELATED WORK Lei Jiao, Frank Y. Li, and Vicent Pla “Dynamic Channel Aggregation

Strategies in Cognitive Radio Networks with Spectrum Adaptation” IEEE Globecom 2011 proceedings. 2011 pp.1-6 (Static and Dynamic)

Proposed Channel Assembling Strategies vs No- Assembling (NA)

Immediate Blocking Strategy (IBS) Reassignment Based Strategy (RBS)

MOTIVATION

Channel assembling (CA) strategies to : Consider the varying nature of a wireless link and mitigate schemes like

adaptive modulation and coding (AMC) Consider homogeneous traffic class (real time or non-real time users)

SYSTEM MODEL FOR HOMOGENEOUS USERS

Fig. 1 Network Model/Architecture (FCFS -Regime)

Primary User (TV)

Primary User (TV)

PU TV mast

Secodary User

Secodary User

CRBS

Secodary User

Primary User (TV)

class 0

Primary User (TV)

class 0

PU TV mast

SU class 1

SU class 1

CRBS

SU class 1

SU class 1

WIRELESS CHANNEL MODEL AND AMC

SNR Partitioning

Outage R2R1 R3

Bad Moderate Good

Fig.2 SNR Partitioning

OFF Frame

DurationCh 1/ PU1

Ch 1/ PU2

Ch 1/ PU3

Ch 1/ PU1

:::::::::

Ch M/PU M

PU ON PU OFF

Slo1………………………………………………………...S

ON frame OFF frame (Tf)

Fig. 3 Wireless frame utilization

CONT.

Fig. 4. The ON-OFF channel usage model for primary users

The PU’s slot capacity, is given as

Where, Note that is the channel utilization ratio. The SU system capacity (slot capacity/OFF capacity) is given by

ON(Buzy)

OFF(Idle)

ALGORITHM FOR IBS

• CRBs check wireless link ; % cognitive radio base station checks wireless link state (SNR)

• CRBs check ; % cognitive radio base station checks available recourse for SUs

• ; % test for resources

• Admit = true; % admit , but first by the principle of FCFS and assemble with a probability

• else

• Admit =false; % block due to insufficiently resources.

• % PU arrival, pre-empt (no-spectrum adaptation)

• = true; % f

• end if % terminates if no events

• Go to start % repeat the process

ALGORITHM FOR RBS

• CRBs check wireless link ; % cognitive radio base station checks wireless link state (SNR)

• CRBs check ; % cognitive radio base station checks available recourse for SUs

• ; % test for resources

• Admit = true; % admit

• else• % test for new arrival or PU arrival

• do ++ j: % adjusting and iterate over user resources • Admit = true; % admit and assemble for both users

• Else • Admit = false; % b since no free channel-slot or insufficient • Else• if all condition can not be meet• = true; % d • end if ; %start the process

RESULTS AND DISCUSSIONS

SU service rate0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Bloc

king

Pro

babi

lity

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

NAIBS StrategyRBS Strategy

0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.210

-3

10-2

10-1

100

PU arrival rate

SU

Blo

ckin

g P

roba

bilit

y

NAIBSRBS

PU arrival0 0.2 0.4 0.6 0.8 1 1.2 1.4

SU Th

rough

put

0

0.5

1

1.5

2

2.5

3

RBSIBSNA

0 0.2 0.4 0.6 0.8 10

0.5

1

1.5

2

2.5

SU service rate

SU

Thr

ough

put

NA

IBS

RBS

=1.4, =0.2=0.3=0.9

CONT.

0 0.2 0.4 0.6 0.8 10.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

SU service rate

SU

cap

acity

NAIBSRBS

0 5 10 15 200

0.5

1

1.5

2

2.5

SU SNR [dB]

SU

Cap

acity

NA

IBSRBS

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.810

-2

10-1

100

101

PU arrival

SU

For

ced

term

inat

ion

prob

abilit

y

IBSNARBS

SU service rate0 1 2 3 4 5 6 7

SU F

orce

d te

rmina

tion

Prob

abilit

y

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.50.55

0.60.65

NARBS StrategyIBS Strategy

CONCLUSION

• In this work, compared the performance of two channel assembling strategies with No-Assembling for cognitive radio network considering the dynamics of a wireless link with AMC in a single-class SU traffic.

• The result obtained from our simulation shows that; the RBS scheme outperformed the IBS and NA scheme amidst homogeneous SU class in the sense that, lower blocking and force termination probabilities are observed.

• It demonstrates that AMC with CA is a robust approach in improving dynamic channel allocation schemes.

FUTURE WORK

Our future work will be focus in two folds: • The selection of a traffic type from a SU with two traffic running

simultaneously. • The affect PER/BER especially in a dynamic wireless link. • Integrating queuing discipline into the proposed policies

MAIN REFERENCES

Lei Jiao, Frank Y. Li, and Vicent Pla “Dynamic Channel Aggregation Strategies in Cognitive Radio Networks with Spectrum Adaptation” IEEE Globecom 2011 proceedings. 2011 pp.1-6

L. Jiao, F. Y. Li, and V. Pla, “Modelling and performance analysis of channel assembling in multi-channel cognitive radio networks with spectrum adaptation,” IEEE Trans. Veh. Technol., vol. 61, no. 6, pp.2686–2697, July 2012

THANK YOU