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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
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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)
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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
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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
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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
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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.
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(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.
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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.
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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
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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
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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.
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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
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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
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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 ..
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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
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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
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Numerical Analysis and Numerical Analysis and ResultsResults
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
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Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)
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.
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11/09/200711/09/2007 Ph.D. DefensePh.D. Defense 1919
Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)
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
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11/09/200711/09/2007*published at IEEE Sarnoff Conference *published at IEEE Sarnoff Conference
May'07May'07 2020
Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)
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
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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
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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
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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.
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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.
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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
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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
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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.
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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))
AP Number FCA: Equal PowerFCA: Power Management
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%
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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))
AP Number FCA: Equal PowerFCA: Power Management
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%
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11/09/200711/09/2007 Ph.D. DefensePh.D. Defense 3030
Numerical Analysis and Numerical Analysis and ResultsResults
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
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11/09/200711/09/2007*Submitted to IEEE WCNC conference *Submitted to IEEE WCNC conference
Apr'08Apr'08 3131
Numerical Analysis and Numerical Analysis and ResultsResults
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%
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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
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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
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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 .
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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.
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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
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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
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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
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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
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Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)
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): Arrive 6
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
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Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)
FCA and Load Balancing results
FCA: Arrive 7
FCA: Leave 2
FCA: Arrive 8
FCA: Arrive 9
Final Tx Power (dBm): Arrive 7
Final Tx Power (dBm):
Leave 2
Final Tx Power (dBm): Arrive 8
Final Tx Power (dBm): Arrive 9
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
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Numerical Analysis and Results Numerical Analysis and Results (Cont’d)(Cont’d)
FCA and Load Balancing results
-- Added users-- Removed users-- Existing users
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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.
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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.
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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