a performance analysis of fixed and dynamic channel allocation schemes in cellular networks author...

A Performance Analysis A Performance Analysis of of

Fixed and Dynamic Channel Fixed and Dynamic Channel Allocation Schemes Allocation Schemes

in in Cellular NetworksCellular Networks

Author Author Muhammad EmranMuhammad Emran

Co-authorsCo-authorsSyed Asad Hussain, Saqib HussainSyed Asad Hussain, Saqib HussainDepartment of Computer SciencesDepartment of Computer Sciences

COMSATS Institute of Information Technology, LahoreCOMSATS Institute of Information Technology, [email protected]@ciitlahore.edu.pk

The 4th International Workshop on Frontiers of Information Technology

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Overview of PresentationOverview of Presentation Overview of Cellular Network ArchitectureOverview of Cellular Network Architecture IntroductionIntroduction Channel Allocation TechniquesChannel Allocation Techniques My ContributionMy Contribution Dynamic Channel Allocation Scheme (DCA)Dynamic Channel Allocation Scheme (DCA) Standard Cellular Network Model in OPNET Standard Cellular Network Model in OPNET ModelerModeler Simulation StatisticsSimulation Statistics Simulation ResultsSimulation Results Results ComparisonsResults Comparisons ConclusionConclusion


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Overview of Cellular Network Architecture


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IntroductionIntroduction Mobile networks, a rapidly growing cellular Mobile networks, a rapidly growing cellular

technologytechnology An efficient method for channel allocation is An efficient method for channel allocation is

required to entertain maximum usersrequired to entertain maximum users


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What is Channel Allocation?What is Channel Allocation? Channel Allocation Techniques:Channel Allocation Techniques:

Fixed Channel Allocation (FCA)Fixed Channel Allocation (FCA)

Fixed number of channels are allocatedFixed number of channels are allocated Dynamic Channel Allocation (DCA)Dynamic Channel Allocation (DCA)

Dynamic Pool of channels is definedDynamic Pool of channels is defined Hybrid Channel Allocation (HCA)Hybrid Channel Allocation (HCA)

Mixture of FCA and DCAMixture of FCA and DCA

Channel Allocation in Cellular Channel Allocation in Cellular NetworksNetworks


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Fixed Channel AllocationFixed Channel Allocation Static allocation of frequency channels Static allocation of frequency channels Frequency Reuse Frequency Reuse

Co-Channel CellsCo-Channel Cells Co-Channel Reuse DistanceCo-Channel Reuse Distance

Advantage of Frequency ReuseAdvantage of Frequency Reuse To deal with massive number of callsTo deal with massive number of calls Huge Coverage AreaHuge Coverage Area

Unchangeable allocationUnchangeable allocation


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Fixed Channel Allocation (Contd.)Fixed Channel Allocation (Contd.) Uniform Channel AllocationUniform Channel Allocation

Uniform trafficUniform traffic Equal number of nominal channels in each cellEqual number of nominal channels in each cell

Non Uniform Channel AllocationNon Uniform Channel Allocation Non uniform trafficNon uniform traffic Allocation on the basis of expected trafficAllocation on the basis of expected traffic Reduction of call blocking probabilityReduction of call blocking probability DisadvantagesDisadvantages

Non deterministic traffic at different time slotsNon deterministic traffic at different time slots Improper use of BandwidthImproper use of Bandwidth


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Dynamic Channel AllocationDynamic Channel Allocation Why do we need it?Why do we need it?

To deal with the non uniform traffic To deal with the non uniform traffic

No particular relation among channels and cellsNo particular relation among channels and cells Channels are part of a pool of resourcesChannels are part of a pool of resources Frequency Reuse constraintFrequency Reuse constraint Co-channel interference considerationCo-channel interference consideration

TypesTypes Centralized DCACentralized DCA Distributed DCADistributed DCA


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Dynamic Channel Allocation (contd.)Dynamic Channel Allocation (contd.)

Centralized DCACentralized DCA Channel allocation through centralized authority Channel allocation through centralized authority

(MTSO/MSC)(MTSO/MSC) Distributed DCADistributed DCA

Channel allocation through base stationChannel allocation through base station DisadvantageDisadvantage

Intensive computation for DCA algorithmsIntensive computation for DCA algorithms


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Hybrid Channel AllocationHybrid Channel Allocation

An amalgam of FCA and DCA SchemesAn amalgam of FCA and DCA Schemes

Channel BorrowingChannel Borrowing Statically allocated channelsStatically allocated channels A pool of reserved channels for borrowingA pool of reserved channels for borrowing

DisadvantagesDisadvantages Frequency reuse constraintsFrequency reuse constraints Call blockingCall blocking Complex algorithms to reduce call blockingComplex algorithms to reduce call blocking


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Contribution of Research work Contribution of Research work

To exploit the role of channel allocation schemes To exploit the role of channel allocation schemes (FCA & DCA) to perform load balancing (FCA & DCA) to perform load balancing

Implementation of Dynamic Channel Allocation Implementation of Dynamic Channel Allocation (DCA) in OPNET Modeler (DCA) in OPNET Modeler

OPNET Simulations and Results Comparisons for OPNET Simulations and Results Comparisons for FCA and DCA schemesFCA and DCA schemes


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Standard Cellular Network Model in Standard Cellular Network Model in OPNET ModelerOPNET Modeler


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Dynamic Channel Allocation Scheme Dynamic Channel Allocation Scheme (DCA)(DCA)

Based upon Centralized DCA algorithmBased upon Centralized DCA algorithm Channel manager of MTSO controls dynamic pool Channel manager of MTSO controls dynamic pool

of channelsof channels On request free channel allocationOn request free channel allocation After termination of a call the assigned channel is After termination of a call the assigned channel is

returned to the poolreturned to the pool


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Simulation StatisticsSimulation Statistics

Duration of Simulation Duration of Simulation 1 Hour1 HourValues per Statistics Values per Statistics 100100Call Generation DistributionCall Generation Distribution ExponentialExponentialCall Generation Rate Call Generation Rate 10, 50 & 100 10, 50 & 100 Calls Calls

per Hourper HourCall Length Call Length 3 Minute per Call3 Minute per CallCall Length Distribution Call Length Distribution ExponentialExponentialFoliage Density Foliage Density No FoliageNo FoliageSetting Type Setting Type UrbanUrbanSeed Seed 128128


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ImplementationImplementation► In In Header Block,Header Block, we have made the following amendments. we have made the following amendments.

Declare an integer Declare an integer total_channels_free total_channels_free */ Declaration of free channel */ Declaration of free channel variable/*variable/*Initialize Initialize total_channels_free total_channels_free with with 5656 */Declaration of pool of free channel/**/Declaration of pool of free channel/*

Channel Assignment Code:Channel Assignment Code:if (total_channels_free > 0) if (total_channels_free > 0) */Checking availability of even a single free channel/**/Checking availability of even a single free channel/*

Get the call request packetGet the call request packetPull all meaningful info off of the requestPull all meaningful info off of the requestSend response back to call initiator Send response back to call initiator

DecrementDecrement total_channels_free total_channels_free byby 1 1 */After allocation of a channel decrement */After allocation of a channel decrement “1” from the pool of free channels/*“1” from the pool of free channels/*

Inc globalInc global


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Channel Assignment CodeChannel Assignment Code

elseelseSend blocked response to call initiatorSend blocked response to call initiatorPull all meaningful info off of the requestPull all meaningful info off of the requestSend response back to call initiatorSend response back to call initiatorUpdate necessary statisticsUpdate necessary statisticsInc global Inc global

Write out statsWrite out statsWrite the global out statsWrite the global out stats

Channel Free Code: Channel Free Code: Increment Increment total_channels_free total_channels_free byby 1 1*/Upon call termination, the free channel is returned back to the pool */Upon call termination, the free channel is returned back to the pool of free channels/*of free channels/*


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For 10 calls per hour per mobile userFor 10 calls per hour per mobile user

Simulation ResultsSimulation Results

Comparison of Serviced and Blocked calls in FCA and DCA based Cellular SystemsComparison of Serviced and Blocked calls in FCA and DCA based Cellular Systems

Percentage of Serviced Calls in Networks

0

0.2

0.4

0.6

0.8

1

1.2

0.6 6 11.4 16.8 22.2 27.6 33 38.4 43.8 49.2 54.6 60

Time in Minutes

Per

cent

age

of S

ervi

ced

Cal

ls

Percentage of Calls Serviced in FCA based System

Percentage of Calls Serviced in DCA based System

Percentage of Blocked Calls in Network

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.6 6 11.4 16.8 22.2 27.6 33 38.4 43.8 49.2 54.6 60

Time in MinutesP

erce

ntag

e of

Blo

cked

Cal

ls

Percentage of Calls Blocked in FCA based System

Percentage of Calls Blocked in DCA based System


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Results ComparisonResults Comparison

Calls RequestedCalls Requested Calls Serviced Calls Serviced Serviced Calls (%) Serviced Calls (%) Calls Blocked Calls Blocked Blocked Calls (%) Blocked Calls (%)

FCAFCA DCA DCA FCAFCA DCA DCA FCAFCA DCA DCA FCAFCA DCA DCA FCAFCA DCA DCA

410 410 390390 265265 385385 7070 9999 145145 55 3030 11

Table 1 Comparison of Global Statistics of FCA and DCA channel allocation schemes


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Simulation Results (Contd.)Simulation Results (Contd.)


Percentage of Serviced Calls in Network

0

0.2

0.4

0.6

0.8

1

1.2

0.6 5.4 10.2 15 19.8 24.6 29.4 34.2 39 43.8 48.6 53.4 58.2

Time in Minutes

Per

cent

age

of S

ervi

ced

Cal

ls




0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.6 4.8 9 13.2 17.4 21.6 25.8 30 34.2 38.4 42.6 46.8 51 55.2 59.4

Time in MinutesP

erce

ntag

e of

Blo

cked

Cal

ls




20




20402040 14311431 386386 596596 2424 4848 16541654 835835 7676 5252


Results Comparison (Contd.)Results Comparison (Contd.)


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Simulation Results (Contd.)Simulation Results (Contd.)


Percentage of Serviced Calls in Network

0

0.2

0.4

0.6

0.8

1

1.2

0.6 5.4 10.2 15 19.8 24.6 29.4 34.2 39 43.8 48.6 53.4 58.2

Time in Minutes

Per

cent

age

of S

ervi

ced

Cal

ls




0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.6 4.8 9 13.2 17.4 21.6 25.8 30 34.2 38.4 42.6 46.8 51 55.2 59.4

Time in MinutesP

erce

ntag

e of

Blo

cked

Cal

ls




22




36523652 24642464 424424 579579 1414 2929 32273227 18851885 8686 7171


Results Comparison (Contd.)Results Comparison (Contd.)


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ConclusionConclusion After the careful analysis of Dynamic Channel After the careful analysis of Dynamic Channel

Allocation (DCA) strategy using OPNET simulation, Allocation (DCA) strategy using OPNET simulation, and comparing these results with the Fixed Channel and comparing these results with the Fixed Channel Allocation (FCA) scheme, it is concluded that DCA Allocation (FCA) scheme, it is concluded that DCA performs much better than FCA. performs much better than FCA.

It has been proved that static channel allocation It has been proved that static channel allocation performs badly to handle the congestion in the performs badly to handle the congestion in the network. network.

In a less congested network DCA scheme served 99% In a less congested network DCA scheme served 99% of the requested calls whereas FCA handled only of the requested calls whereas FCA handled only 70% calls. 70% calls.

In a more congested network, DCA entertained 48% In a more congested network, DCA entertained 48% of requested calls where as FCA served 24% of total of requested calls where as FCA served 24% of total requests. requests.


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Conclusion (Contd.)Conclusion (Contd.) In case of severe congestion in network, DCA catered In case of severe congestion in network, DCA catered

29% of requested calls on the other hand FCA could 29% of requested calls on the other hand FCA could hardly accommodate 14% of the requested calls. hardly accommodate 14% of the requested calls.

One tradeoff of this research is either to overburden One tradeoff of this research is either to overburden the MTSO by implementing DCA or bear the the MTSO by implementing DCA or bear the blockage of 30% by applying FCA in situations of blockage of 30% by applying FCA in situations of less congestion in the network.less congestion in the network.

As long as the load gets increased over the network, As long as the load gets increased over the network, DCA performs two times better than FCA, in spite of DCA performs two times better than FCA, in spite of some overhead on MTSO.some overhead on MTSO.


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Future WorkFuture Work

HandoffsHandoffs Frequency Reuse ConsiderationsFrequency Reuse Considerations


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Questions?Questions?

a performance analysis of fixed and dynamic channel allocation schemes in cellular networks author...

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