A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA Deepti Singhal and Naresh Jotwani The First International Conference on COMmunication Systems and NETworkS (COMSNETS) January 9, 2009
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A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
A Fair Downlink Packet Scheduling Approachto Support QoS in HSDPA
Deepti Singhal and Naresh Jotwani
The First International Conference on COMmunication Systems and NETworkS(COMSNETS)
January 9, 2009
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Contents
1 Introduction
2 Problem Statement3 Other Proposed Scheduling Algorithms
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Introduction
Introduction
• In the present scenarios, the high-speed demands aregrowing rapidly specially in wireless networks.
• In order to satisfy fast-growing demands in downlink, theconcept of High Speed Downlink Packet Access has beenproposed.
• Packet scheduler in HSDPA controls the allocation ofshared resources to users.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Problem Statement
Problem Statement
• The objective of the paper is to design and evaluate adownlink-scheduling algorithm for HSDPA based UMTSnetworks.
• The resulting algorithm should ensure better channelutilization and fairness among users.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Other Proposed Scheduling Algorithms
Other Proposed Scheduling Algorithms
• Maximum Carrier to Interference Ratio Scheduling [1]:
j = maxi ri (k) (1)
Where ri (k) is instantaneous C/I ratio
• Proportional Fair Scheduling [1, 2]:According to PF, user j is selected, if
j = maxiri
Ri, i = 1, 2, ..., N. (2)
Ri is the average received rate for user i
• DRC Exponent Rule [3]
j = maxi
rin
Ri, i = 1, 2, ..., N. (3)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Other Proposed Scheduling Algorithms
Other Proposed Scheduling Algorithms
• Maximum Carrier to Interference Ratio Scheduling [1]:
j = maxi ri (k) (1)
Where ri (k) is instantaneous C/I ratio
• Proportional Fair Scheduling [1, 2]:According to PF, user j is selected, if
j = maxiri
Ri, i = 1, 2, ..., N. (2)
Ri is the average received rate for user i
• DRC Exponent Rule [3]
j = maxi
rin
Ri, i = 1, 2, ..., N. (3)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Other Proposed Scheduling Algorithms
Other Proposed Scheduling Algorithms
• Maximum Carrier to Interference Ratio Scheduling [1]:
j = maxi ri (k) (1)
Where ri (k) is instantaneous C/I ratio
• Proportional Fair Scheduling [1, 2]:According to PF, user j is selected, if
j = maxiri
Ri, i = 1, 2, ..., N. (2)
Ri is the average received rate for user i
• DRC Exponent Rule [3]
j = maxi
rin
Ri, i = 1, 2, ..., N. (3)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Other Proposed Scheduling Algorithms
Other Proposed Scheduling Algorithms
• Maximum Carrier to Interference Ratio Scheduling [1]:
j = maxi ri (k) (1)
Where ri (k) is instantaneous C/I ratio
• Proportional Fair Scheduling [1, 2]:According to PF, user j is selected, if
j = maxiri
Ri, i = 1, 2, ..., N. (2)
Ri is the average received rate for user i
• DRC Exponent Rule [3]
j = maxi
rin
Ri, i = 1, 2, ..., N. (3)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Other Proposed Scheduling Algorithms
Other Proposed Scheduling Algorithms Contd...
• Adaptive Proportional Fair Scheduling [4]:In APF, the user selection criterion is given by
j = maxir cii
Ri∗ RTi , i = 1, 2, ..., N, (4)
ci are updated with
ci = ci + ∆c, if(
RiRTi
− 1N
∑Nj=1
Rj
RTj
)
< −ε
ci = ci − ∆c, if(
RiRTi
− 1N
∑Nj=1
Rj
RTj
)
> ε. (5)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Other Proposed Scheduling Algorithms
Other Proposed Scheduling Algorithms Contd...
• Adaptive Proportional Fair Scheduling [4]:In APF, the user selection criterion is given by
j = maxir cii
Ri∗ RTi , i = 1, 2, ..., N, (4)
ci are updated with
ci = ci + ∆c, if(
RiRTi
− 1N
∑Nj=1
Rj
RTj
)
< −ε
ci = ci − ∆c, if(
RiRTi
− 1N
∑Nj=1
Rj
RTj
)
> ε. (5)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Proposed Solution Approach
Proposed Solution ApproachFramework for developing Wireless Fair Scheduling Algorithm [5]
Select user i accordingto
Error free Model
Is
leading ??
slot ??relinquish this
should
Select user jaccording to
Compensation Model
Is i = j ??
Update the lead/lagparameterof user i & j
(Lead Lag Model)
Yes
Yes
No
badchannel ??
No
Yes
No
Yes Schedule user i
Schedule user j
Main components of frameworkare:
• Error Free Service Model
• Compensation Model
• Lead and Lag Model
The proposed solution approach isbased on the framework discussedand it replaces Internal working ofModel of this framework.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Proposed Solution Approach
Wireless Fair - High Speed Scheduling
• Proportion Fair Service Model:This model selects a user with
maxiri
R′
i∗ RTi (6)
• Compensation Model:The maximum limit of lead after which user will relinquishes itsslot is given by
max_li =RTi ∗ TTIduration
mean_channal_ratei(7)
This model is also responsible for selecting user afterrelinquishing. Among the lagging users who perceives goodchannel will be scheduled.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Proposed Solution Approach
Wireless Fair - High Speed Scheduling
• Proportion Fair Service Model:This model selects a user with
maxiri
R′
i∗ RTi (6)
• Compensation Model:The maximum limit of lead after which user will relinquishes itsslot is given by
max_li =RTi ∗ TTIduration
mean_channal_ratei(7)
This model is also responsible for selecting user afterrelinquishing. Among the lagging users who perceives goodchannel will be scheduled.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Proposed Solution Approach
Wireless Fair - High Speed Scheduling Contd...
• Lead and Lag Model:if user i gives its slot to user j then lead-lag parameter is updatedwith
li = li − max(
TTIduration,PacketSizei
RTi
)
(8)
lj =
lj +PacketSizej
RTj, if not lagging
min(
0.0, lj +PacketSizej
RTj
)
, if lagging(9)
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Performance Measure
Performance Measure
• Link Utilization:
Measured by Mean System Throughput (MAC-hs)• User Level Fairness
Long-term Fairness:Measured by FI by [6]
(
∑Ni=1 xi
)2
N∑N
i=1 xi2
, xi ≥ 0, ∀ i (10)
Here xi is taken as RiRTi
and N is the number of users
Short-term Fairness:For short-term fairness CDF of waiting time at Node B isused.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Simulation Environment
Simulation Environment
• Simulation ToolsNetwork Simulator-2 [7] and Enhanced UMTS Radio AccessNetwork Extensions to NS2 [8]
• Simulation Topology
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UE N
UE 2
UE 1
NODE B SGSNRNC GGSN
622 Mb 15 ms
622 Mb 10 ms
node 1
node 2
node N
10 Mb15 ms
622 Mb 0.4 ms
EURANE Support
Figure: Topology used in simulation
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Simulation Environment
Simulation Environment
• Simulation ParametersParameters ValueCell Radius 600 mNumber of codes used 15Link Adaptation Delay 6 msHARQ Cycle 6 TTINode B Transmission Power 38 dBmNode B Antenna Gain 17 dBShadowing Standard Deviation 3 dBMax. number of HARQ transmission 3Number of parallel HARQ processes 6RLC Acknowledgement Mode AMRLC Buffer Level 500 PDU’sMAC Buffer Level 250 PDU’s
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Simulation Results
Simulation ResultsSimulation Scenarios
• Web Traffic ScenarioAverage Load Distribution Scenario - Users are uniformlydistributed in the cell areaWorst Load Distribution Scenario - High requirement usersare in bad channel condition
• FTP-Web Traffic Scenario
• Load Analysis
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Simulation Results
Web-Traffic Scenario
Simulation Results - Web-TrafficPedestrian Environments - Users are uniformly distributed in the cell area
Figure: System Parameters by varying load on system
End to End Throughput Vehicular Results
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Summary & Conclusion
Summary
• In averagely distributed load, both APF and WF-HSSalgorithm provides good balance between link utilizationand long-term fairness.
• In worst load conditions, WF-HSS provide betterperformance in terms of link utilization in comparison toAPF algorithm.
• CDF of waiting time at Node B shows that WF-HSSalgorithm provides short-term fairness among users for alltraffic scenarios, while APF algorithm fails to do so.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Summary & Conclusion
Summary Contd....
• WF-HSS scheduling provides benefits of TCP windowresizing to the FTP users without affecting performance ofother users, while APF algorithm doesn’t do so.
• In comparison to APF algorithm, WF-HSS provides betterlink utilization without affecting fairness among users inheavy load conditions.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Summary & Conclusion
Conclusion
WF-HSS algorithm ensures long as well as short time scalefairness among users, according to their QoS requirements,while seeking to maximize link utilization.
A Fair Downlink Packet Scheduling Approach to Support QoS in HSDPA
Thank You
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Comparisons of link-adaptation-based Scheduling algorithms for the WCDMA system with high-speeddownlink packet access.Canadian Journal of Electrical and Computer Engineering (CJECE), Vol. 29:109 – 116, 2004.
R. Pankaj A. Jalali, R. Padovani.
Data Throughput of CDMA-HDR a High Efficiency-High Data Rate Personal Communication WireressSystem.IEEE, VTC, 2000.
J.M. Holtzman.
Asymptotic Analysis of Proportional Fair Algorithm.in Proc. PIMRC, pages 33–37, 2001.
Ghassane Aniba and Sonia Aissa.
Adaptive Proportional Fairness for Packet Scheduling in HSDPA.IEEE Communications Society Globecom, 2004.