Load Distribution and Channel Assignment in IEEE 802.11 Wireless Local Area Networks Ph.D. Dissertation Defense Presented by Mohamad Haidar Department.

Load Distribution and Load Distribution and Channel Assignment in IEEE Channel Assignment in IEEE 802.11 Wireless Local Area 802.11 Wireless Local Area

NetworksNetworks

Ph.D. Dissertation DefensePh.D. Dissertation Defense

Presented by Presented by Mohamad HaidarMohamad HaidarDepartment of Applied ScienceDepartment of Applied Science

George W. Donaghey College of Engineering and George W. Donaghey College of Engineering and

Information Technology,Information Technology, University of Arkansas at Little RockUniversity of Arkansas at Little Rock

November 9, 2007November 9, 2007

11/09/200711/09/2007 Ph.D. DefensePh.D. Defense 22

Presentation OutlinePresentation Outline IntroductionIntroduction

Wireless Local Area Networks (WLANs)Wireless Local Area Networks (WLANs) Access Points (APs) CongestionAccess Points (APs) Congestion Channel AssignmentChannel Assignment

Related WorkRelated Work ContributionsContributions Problems StatementsProblems Statements

1. Congestion Problem1. Congestion Problem Proposed SolutionProposed Solution Problem FormulationProblem Formulation AlgorithmAlgorithm Numerical Analysis and ResultsNumerical Analysis and Results Simulations (OPNET)Simulations (OPNET)


Presentation Outline Presentation Outline (Cont’d)(Cont’d)

2. Channel Assignment Problem2. Channel Assignment Problem Proposed SolutionProposed Solution Problem FormulationProblem Formulation AlgorithmAlgorithm Numerical Analysis and ResultsNumerical Analysis and Results Simulations (OPNET)Simulations (OPNET)

Dynamic ModelDynamic Model Scenario 1 (variable data rate)Scenario 1 (variable data rate) Scenario 2 (dynamic user distribution)Scenario 2 (dynamic user distribution)

ConclusionConclusion Future WorkFuture Work


IntroductionIntroduction

Wireless Local Area Wireless Local Area Networks (WLANs)Networks (WLANs) AirportsAirports HotelsHotels CampusesCampuses

WLANs are divided WLANs are divided into 3 categories:into 3 categories: IEEE 802.11a in the 5 IEEE 802.11a in the 5

GHz band (54 Mbps)GHz band (54 Mbps) IEEE 802.11b in the 2 IEEE 802.11b in the 2

GHz band (11 Mbps)GHz band (11 Mbps) IEEE 802.11g in the 2 IEEE 802.11g in the 2

GHz band (54 Mbps)GHz band (54 Mbps) Example of WLAN


Introduction (Cont’d)Introduction (Cont’d) What is Access Point (AP) What is Access Point (AP)

congestion?congestion? Some times referred to as “Hot Some times referred to as “Hot

Spot”Spot”

CCAPAP= (R= (R11+ R+ R2+..+ 2+..+ RRNN)/BW)/BW

CCAPAP: Congestion at AP: Congestion at APR : Data rate of a user connected to R : Data rate of a user connected to

the APthe APBW: Bandwidth (11 Mbps for IEEE BW: Bandwidth (11 Mbps for IEEE

802.11b)802.11b)

Channel AssignmentChannel Assignment Minimize interferenceMinimize interference

To improve QoS (less delay and To improve QoS (less delay and higher throughput)higher throughput)

3 non-overlapping channels in 3 non-overlapping channels in IEEE 802.11b/g (1, 6, and 11)IEEE 802.11b/g (1, 6, and 11)

Frequency Spectrum for IEEE 802.11b/g


Limitation of Previous Limitation of Previous ResearchResearch

AP PlacementAP Placement The main objective was to use a minimum number of APs The main objective was to use a minimum number of APs

for adequate coverage of the desired area.for adequate coverage of the desired area. Did not account for channel assignment and/or load Did not account for channel assignment and/or load

distributiondistribution.. Channel AssignmentChannel Assignment

Based on minimizing co-channel interference.Based on minimizing co-channel interference. Limited to Limited to eithereither minimizing total interference between minimizing total interference between

APs APs oror maximizing the sum of interference at a given AP. maximizing the sum of interference at a given AP. When integrated and applied simultaneously with AP When integrated and applied simultaneously with AP

placement, better results were achieved than dealing with placement, better results were achieved than dealing with them sequentially.them sequentially.

User distribution was User distribution was notnot accounted for in the channel accounted for in the channel assignment.assignment.


(Cont’d)(Cont’d) Load Balancing/DistributionLoad Balancing/Distribution

Balancing the load based on the number of active Balancing the load based on the number of active users users

performs poorly because the data rate of users was performs poorly because the data rate of users was not taken into consideration.not taken into consideration.

Minimizing the congestion at the most congested Minimizing the congestion at the most congested AP by redistributing users.AP by redistributing users.

Improves the load ONLY at the MCAP.Improves the load ONLY at the MCAP. Load balanced agents installed at the APs that Load balanced agents installed at the APs that

broadcast periodically their load. APs are either broadcast periodically their load. APs are either under-loaded, balanced, or overloaded.under-loaded, balanced, or overloaded.

Static user distribution and no power management.Static user distribution and no power management. All APs involved should be equipped with the LBA All APs involved should be equipped with the LBA

software.software. Cell breathing technique used to reduce the cell Cell breathing technique used to reduce the cell

size to achieve a better load distribution.size to achieve a better load distribution. Connects to the next higher RSSI: is not always the Connects to the next higher RSSI: is not always the

best choice.best choice. Static user distribution.Static user distribution. No channel assignment was considered. Interference No channel assignment was considered. Interference

was not accounted for.was not accounted for.

Contributions of the Current Research

A new Load Balancing scheme based on Power Management. As long as the received power exceeds a

certain threshold, that AP is a potential for association.

Channel Assignment based on Maximizing the SIR at the users. Users involved in the assignment of channels. Different user distributions will lead to different

channel assignment.

11/09/200711/09/2007 Ph.D. defensePh.D. defense 99

(Cont’d) Combining both load balancing based on

power management and the channel assignment based on SIR: A Novel Scheme.

Verified the performance predicted from optimization versus realistic OPNET-based network simulations: New contribution

Developed a realistic dynamic model approach that accounts for variable users’ data rates and users’ behavior: New contribution


A New Heuristic AlgorithmInitial Channel Assignment

Users enter to network

Load Balancing based on PM

Re-Assign channels based on SIR

Sort arriving users and departing users in ascending order in a list

Check list

Arrive Depart

Add user to list Remove user from listResults

End of list


11stst Problem Problem

AP Congestion ProblemAP Congestion Problem Degrades network throughputDegrades network throughput

Slowest station will make other stations wait Slowest station will make other stations wait longer.longer.

Unfair load distribution over the network Unfair load distribution over the network causes bottlenecks at hot spots.causes bottlenecks at hot spots.

Inefficient bandwidth utilization of the Inefficient bandwidth utilization of the network.network.


Proposed SolutionProposed Solution

Reduce congestion at the hot spots by Reduce congestion at the hot spots by decrementing the power transmitted by the Most decrementing the power transmitted by the Most Congested AP (MCAP) in discrete steps until one Congested AP (MCAP) in discrete steps until one or more users can no longer associate with any or more users can no longer associate with any AP or their data rate can no longer be AP or their data rate can no longer be accommodated.accommodated.

The final transmitted power of each AP is set to The final transmitted power of each AP is set to the best balance index, the best balance index, , achieved., achieved.

Advantages:Advantages: Load is fairly distributed.Load is fairly distributed. Increase in data rate throughput per user.Increase in data rate throughput per user. Less adjacent and co-channel interference.Less adjacent and co-channel interference.

2

2

( )

( * )

j

j

T

n T


Problem FormulationProblem Formulation MCAP NLIP formulation MCAP NLIP formulation

minijx

1 2max{ , ,..., }MC C C1 i M 1 j N

1

1N

ij

i

x

1

M

i ij

j

j

U x

CjBW

for j= 1,…, M

for i= 1,…,N


AlgorithmAlgorithm Compute Received Signal Strength Indicator Compute Received Signal Strength Indicator

(RSSI) at each user.(RSSI) at each user. Generate a binary matrix that assigns “1” if a Generate a binary matrix that assigns “1” if a

user’s RSSI exceeds the threshold value or user’s RSSI exceeds the threshold value or “0” otherwise.“0” otherwise.

Invoke LINGO to solve the NLIP.Invoke LINGO to solve the NLIP. Identify the MCAP and compute Identify the MCAP and compute .. Decrement its transmitted power by 1 dBm.Decrement its transmitted power by 1 dBm. Repeat previous steps until one or more user Repeat previous steps until one or more user

can no longer associate with an AP or their can no longer associate with an AP or their data rate can no longer be accommodated.data rate can no longer be accommodated.

Observe the power levels at each AP and the Observe the power levels at each AP and the best user’s association at the best best user’s association at the best ..


Numerical Analysis and Numerical Analysis and ResultsResults

User User NumberNumber

AP1AP1 AP2AP2 AP3AP3 AP4AP4

11 11 11 11 00

22 00 00 11 00

33 00 00 00 11

44 00 00 00 11

55 11 11 11 11

66 11 11 00 00

77 00 11 00 00

88 00 00 11 11

99 00 00 11 00

1010 00 11 00 11

Receiver Sensitivity at the Receiver Sensitivity at the user is -90 dBmuser is -90 dBm

Transmitted Power at each Transmitted Power at each AP is 20 dbmAP is 20 dbm

4

1

2

User-AP candidate association


Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)

Service Area Map

Traffic is randomly generated between 1 Traffic is randomly generated between 1 Mbps and 6 Mbps for each userMbps and 6 Mbps for each userUser NumberUser Number Traffic (Kbps)Traffic (Kbps)

11 17521752

22 56985698

33 42654265

44 19941994

55 35583558

66 31763176

77 53195319

88 15591559

99 29822982

1010 22632263

Data rate of users



Each user is associated to Each user is associated to one and one and ONLYONLY one AP. one AP.

User User NumberNumber

AP1AP1 AP2AP2 AP3AP3 AP4AP4

11 00 11 00 00

22 00 00 11 00

33 00 00 00 11

44 00 00 00 11

55 00 11 00 00

66 11 00 00 00

77 00 11 00 00

88 00 00 00 11

99 00 00 11 00

1010 00 11 00 00

1

1

1

Optimal user-AP association



Initial Congestion factor:

(No Power Mgmt)

Congestion factor solution according to [2]

Congestion factor with Power Mgmt

AP1 0.6319 0.5234 0.3793

AP2 0.4100 0.4100 0.3617

AP3 0.2117 0.2117 0.3167

AP4 0.2026 0.3110 0.3985

81.15% 90.84% 99.31%

Congestion Factor comparison

Load is distributed fairly among APs.Load is distributed fairly among APs. Final transmitted power levels at each AP is: 12 Final transmitted power levels at each AP is: 12

dBm, 18 dBm, 20 dBm and 17 dBm, respectively.dBm, 18 dBm, 20 dBm and 17 dBm, respectively.



Different radii sizes Different radii sizes after power after power adjustmentadjustment

Users do Users do NOTNOT always associate to always associate to the closest AP.the closest AP.

Service area map after Power Mgmt

11/09/200711/09/2007*published at IEEE Sarnoff Conference *published at IEEE Sarnoff Conference

May'07May'07 2020


Congestion Factor Comparison

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

AP1 AP2 AP3 AP4

AP number

Initial CongestionFactor: No PowerManagement

Congestion Factoraccording to [2]

Congestion Factorwith PowerManagement

4 APs

Comparison between Congestion Factors

0.0000

0.10000.2000

0.30000.4000

0.50000.6000

AP number

Initial CongestionFactor, NPM

Congestion Factorbased on [2]

Congestion Factorbased on PowerManagement

9 APs

Congestion Factor Comparison (16 APs)

0.00000.05000.10000.15000.2000

0.25000.30000.35000.40000.4500

AP number

Initial congestion factor: NPM

Congestion Factor based on [2]

Congestion factor with power Management

16 APs

11/09/200711/09/2007 *Not published yet*Not published yet 2121

Simulation Scenarios Simulation Scenarios (OPNET)(OPNET)

Unbalanced Load v.s. Unbalanced Load v.s. Balanced LoadBalanced Load 20 dBm Transmitted power20 dBm Transmitted power -90 dBm Receiver -90 dBm Receiver

thresholdthreshold FTP clients and APs FTP clients and APs

are stationaryare stationary File of 50 Kbytes uploaded File of 50 Kbytes uploaded

continuously.continuously. Simulation time is 40 minsSimulation time is 40 mins Steady state after 15 minsSteady state after 15 mins

WLAN scenario in OPNET, 4 APs and 20 Users


Simulation Results (OPNET)Simulation Results (OPNET)

Overall load on the Overall load on the network was reduced by network was reduced by “load balancing”“load balancing” Reduced overall Reduced overall congestioncongestion

After applying load After applying load balancing, balancing, client 9client 9 associated with associated with BSS2BSS2, and , and improved its throughput.improved its throughput.

Overall load at the network

Throughput of FTP client 9


22ndnd Problem Problem

Channel AssignmentChannel Assignment Careful consideration must be given to Careful consideration must be given to

assigning channels to APs. Otherwise the assigning channels to APs. Otherwise the followings may result:followings may result:

High interference between APs’ overlapping High interference between APs’ overlapping zones.zones.

Users in the overlapping region of two or more Users in the overlapping region of two or more interfering APs will suffer:interfering APs will suffer:

DelayDelay Low data rates Low data rates

This is due to the huge increased requests by the user in retransmitting damaged/unsuccessful packets.


Proposed SolutionProposed Solution

Two folds:Two folds: Assign channels at the design stage (no Assign channels at the design stage (no

users) with the objective to minimize the users) with the objective to minimize the total sumtotal sum of interference between of interference between neighboring APs.neighboring APs.

Re-Assign channels when users exist on Re-Assign channels when users exist on the network.the network.

11/09/200711/09/2007 *Formulation not yet published*Formulation not yet published 2525

Problem Formulation (initial Problem Formulation (initial stage)stage)

ObjectiveObjective

Subject toSubject to

1,

1

max for each min { }MAX iji

M M

SUM ij

i jjW I iW I j

( )

ij jij

ij

w PI

PL d

1 |Ch Ch | 0.2, for 0 where =

0 otherwise

i j ijij

ww

i = 1, …, Mj = 1,…, Mi j

, {1,.., }

{1,..,11}

j kCh Ch K

K


Problem Formulation (with Problem Formulation (with users)users)

ObjectiveObjective

Subject Subject to to

1 1

( )N M

iji j

Max SIR k

1

( ),M

ij ij jk

j

I P w j k

1 |Ch Ch | 0.2, for 0

where = 0 otherwise

i j ijij

ww

( ) ,ik

ijij

PSIR k i j

I

, {1,.., }j k M

{1,.. }i N

, {1,.., }

{1,..,11}

j kCh Ch K

K


Heuristic AlgorithmHeuristic Algorithm Apply initial channel assignment Apply initial channel assignment Users enter the networkUsers enter the network

Apply load balancing algorithm based on Apply load balancing algorithm based on power management.power management.

Save final transmitted powers at APs.Save final transmitted powers at APs. Re-compute received signal at users.Re-compute received signal at users. Compute SIR.Compute SIR. Apply Channel Assignment algorithm Apply Channel Assignment algorithm

based on SIR.based on SIR.


Numerical Analysis and ResultsNumerical Analysis and Results Initial Approach (based Initial Approach (based

on min AP interference)on min AP interference)

AP Number FCA: Equal PowerFCA: Power Management

AP1 1 7

AP2 8 1

AP3 3 11

AP4 11 3

Interference (dB) -21.17 -22.02

Scenario 1: 4 APs (12, 18, 20, 17 (dBm))


AP1 11 11

AP2 1 1

AP3 8 7

AP4 4 5

AP5 11 2

AP6 1 10

Interference (dB) -19.15 -25.49

Scenario2: 6 APS (16, 16, 11, 6, 6, 1 (dBm))

AP3AP2

AP1 AP4

4 APs

AP1 AP4 AP5

AP2 AP3 AP6

6 APs

4%

33%

11/09/200711/09/2007* Published at IEEE PIMRC conference * Published at IEEE PIMRC conference

Jun'07Jun'07 2929

Numerical Analysis and ResultsNumerical Analysis and Results Initial Approach (Cont’d)Initial Approach (Cont’d)

Scenario 3: 9 APs (4, 12, 20, 16, 20, 16, 17, 8, 19 (dBm))


AP1 11 11

AP2 4 1

AP3 8 6

AP4 1 1

AP5 11 10

AP6 4 1

AP7 11 11

AP8 1 1

AP9 11 11

Interference (dB) -17 -19.86

9 APs

AP7 AP8 AP9

AP6AP3AP2

AP1 AP4 AP5

* Published at IEEE ICSPC conference Nov’07

17%



Second Approach (based on max Second Approach (based on max SIR at users)SIR at users)

Two special cases:Two special cases: Many users in the overlapping zoneMany users in the overlapping zone

Users are not in the overlapping Users are not in the overlapping zonezone

11/09/200711/09/2007*Submitted to IEEE WCNC conference *Submitted to IEEE WCNC conference

Apr'08Apr'08 3131


AP NumberFCA: No Users

(minimize interference between APs)

FCA: With Users (Maximize SIR at the Users)

AP1 1 6

AP2 8 11

AP3 3 2

AP4 11 1

Avg. SIR (dB) 6.51 7.66

AP Number FCA: No users FCA: with users

AP1 11 2

AP2 1 11

AP3 8 6

AP4 4 6

AP5 11 8

AP6 1 1

Avg. SIR (dB) 4.22 4.47AP Number FCA: No users FCA: With Users

AP1 11 6

AP2 4 1

AP3 8 11

AP4 1 8

AP5 11 11

AP6 4 4

AP7 11 6

AP8 1 8

AP9 11 11

Avg. SIR (dB) 0.44 2.86

Scenario 1: 4 APs (12, 18, 20, 17 (dBm))Scenario2: 6 APS (16, 16, 11, 6, 6, 1 (dBm))

Scenario 3: 9 APs (4, 12, 20, 16, 20, 16, 17, 8, 19 (dBm))

17%

6%

540%


Simulation Scenarios Simulation Scenarios (OPNET)(OPNET)

4-AP WLAN4-AP WLAN

4-AP WLAN

Scenario 1

Scenario 2

Scenario 3

Scenario 4

AP1 1 1 1 6

AP2 2 6 8 11

AP3 3 1 3 2

AP4 4 11 11 1

Summary of the 4 Scenarios

11/09/200711/09/2007 *Results not yet published*Results not yet published 3333

Simulation Results (OPNET) Simulation Results (OPNET)

Same assumptions from the load balancing Same assumptions from the load balancing scenarios apply scenarios apply EXCEPTEXCEPT for the channel for the channel assignment.assignment.

Zoomed in ViewOverall Upload Response Time

Overall Throughput


Dynamic ModelDynamic Model BackgroundBackground

No such application of a dynamic user behavior No such application of a dynamic user behavior model on a full scale dynamic network. model on a full scale dynamic network.

Published work related to user behavior Published work related to user behavior reported the user behavior through monitoring reported the user behavior through monitoring network traffic and behavior for long periods of network traffic and behavior for long periods of time (10 months or more).time (10 months or more).

Such a model is significant for future Such a model is significant for future researchers in the WLAN field or industry researchers in the WLAN field or industry where load distribution and channel where load distribution and channel assignment algorithms can be implemented assignment algorithms can be implemented and tested on a dynamic scale . and tested on a dynamic scale .


Dynamic Scenario 1Dynamic Scenario 1

Scenario 1Scenario 1: Varying data rate with time: Varying data rate with time 4 APs and 20 users.4 APs and 20 users. Data rate of users vary with time according to a normal Data rate of users vary with time according to a normal

distribution (distribution (= 4 Mbps, = 4 Mbps, = 2 Mbps). = 2 Mbps). Data rate is captured every 5 minutes.Data rate is captured every 5 minutes.

All users are continuously active.All users are continuously active. All APs and users are stationary.All APs and users are stationary. Default AP transmitted power is 20 dBm.Default AP transmitted power is 20 dBm. Receiver’s threshold is -90 dBm.Receiver’s threshold is -90 dBm. Simulation period is 2 hours.Simulation period is 2 hours.


Numerical Analysis and ResultsNumerical Analysis and Results

Initial user-AP association

Initial CF Final CF

Final transmitted

power (dBm)

Final FCA

AP1 0.2563 0.2464 16 1

AP2 0.0669 0.2721 20 6

AP3 0.3752 0.2502 12 11

AP4 0.3445 0.2741 11 11

82.49% 99.77%

Iteration 1

Initial CF Final CF

Final transmitted

power (dBm)

Final FCA

AP1 0.2454 0.3023 20 1

AP2 0.1275 0.3979 16 6

AP3 0.7240 0.3968 5 6

AP4 0.3703 0.3703 18 11

72.94% 98.89%

Last iteration

Final user-AP association


Dynamic Scenario 2Dynamic Scenario 2 Scenario 2:Scenario 2: Dynamic User Behavior Dynamic User Behavior

Same assumptions as before apply Same assumptions as before apply EXCEPTEXCEPT that that the the data ratedata rate now is now is fixedfixed over simulation time. over simulation time.

Users arrive to the WLAN according to a Poisson Users arrive to the WLAN according to a Poisson distribution with an arrival rate of distribution with an arrival rate of ..

varies with time. However, in this scenario varies with time. However, in this scenario has a has a constant value over the simulation period (2 hours).constant value over the simulation period (2 hours).

Pr( )!

nen

n


Dynamic Scenario 2 Dynamic Scenario 2 (Cont’d)(Cont’d)

Session lengths of each user is Session lengths of each user is characterized by a Bi-Pareto distribution.characterized by a Bi-Pareto distribution.

When a user’s session is over, the user is When a user’s session is over, the user is assumed as either no longer active or left assumed as either no longer active or left the network.the network.

i.e. the user no longer has a data rate i.e. the user no longer has a data rate it does it does not constitute any load at its AP.not constitute any load at its AP.

( 1) 1( ) (1 ) ( ) ( ),P x k c x x kc x kc x k


Numerical Analysis and ResultsNumerical Analysis and Results = 4 = 4

User Number Arrival times(hrs)Departure Time(hrs)

21 0.10

22 0.15

23 0.70

24 0.76

25 1.13

26 1.42

10 1.62

27 1.66

3 1.93

28 1.87

29 2.00

Arrival and Departure time Table

4 APs, 20 Users



FCA: Arrive 4

FCA: Arrive 5

FCA: Arrive 6

FCA: Leave 1

Final Tx Power (dBm): Arrive 4

Final Tx Power (dBm:

Arrive 5


Final Tx Power (dBm): Leave 1

AP1 1 1 1 1 17 20 15 18

AP2 6 6 6 6 11 14 19 18

AP3 11 11 11 11 12 5 19 12

AP4 6 6 1 1 15 13 13 13

98.75% 99.14% 96.89% 99.62%

Avg. SIR (dB)

6.46 6.27 6.08 6.05

FCA and Load Balancing results




FCA: Arrive 7

FCA: Leave 2

FCA: Arrive 8

FCA: Arrive 9


Final Tx Power (dBm):

Leave 2



AP1 1 1 1 1 20 19 20 18

AP2 6 6 6 6 18 17 15 18

AP3 11 11 11 11 8 15 16 15

AP4 6 6 1 1 10 18 11 9

99.01% 97.69% 98.92% 99.42%

Total SIR (dB)

5.92 5.94 5.77 5.71




-- Added users-- Removed users-- Existing users


ConclusionConclusion A new load balancing algorithm based on A new load balancing algorithm based on

power management was developed.power management was developed. A new channel assignment algorithm based A new channel assignment algorithm based

on maximizing SIR was developed.on maximizing SIR was developed. Results were validated using OPNET Results were validated using OPNET

simulation to show the effectiveness of the simulation to show the effectiveness of the developed algorithms.developed algorithms.

Dynamic data rate and user behavior were Dynamic data rate and user behavior were introduced to verify the ability of the introduced to verify the ability of the developed models to adapt to these developed models to adapt to these dynamic behaviors.dynamic behaviors.


Future WorkFuture Work

Extension of the dynamic model to Extension of the dynamic model to combine both variable data rate and combine both variable data rate and users’ behavior.users’ behavior.

Application of this work to WiMAX Application of this work to WiMAX (IEEE 802.16).(IEEE 802.16).

Integration of smart antenna Integration of smart antenna technology at the AP.technology at the AP.

Expand developed work to larger Expand developed work to larger WLANs.WLANs.


Special ThanksSpecial Thanks Ph.D. Advising Ph.D. Advising

Committee:Committee: Dr.. Hussain Al-Rizzo Dr.. Hussain Al-Rizzo

(Advisor)(Advisor) Dr. Robert AklDr. Robert Akl Dr. Yupo ChanDr. Yupo Chan Dr. Hassan El-SalloukhDr. Hassan El-Salloukh Dr. Seshadri MohanDr. Seshadri Mohan Dr. Haydar AlshukriDr. Haydar Alshukri

Ph.D. CandidatesPh.D. Candidates Rami AdadaRami Adada Rabindra GhimireRabindra Ghimire

Graduate StudentGraduate Student TJ CalvinTJ Calvin

Network AdministratorNetwork Administrator Greg BrowningGreg Browning

OPNET Technical OPNET Technical SupportSupport

LINGO Technical LINGO Technical SupportSupport

Load Distribution and Channel Assignment in IEEE 802.11 Wireless Local Area Networks Ph.D. Dissertation Defense Presented by Mohamad Haidar Department.

Documents

better load distribution

channel assignmentbased

static user distribution

cochannel interference

load balanced agents

minimum number of aps

congested ap

given ap