1. Modelling Interfernce for Wireless LTE
networks in OPNET
Studienarbeit Kick off Presentation
Vivek Tyagi (21152475)
vivek.tyagi@tu-harburg.de

2. Agenda
• Background and Impulse towards topic
• Project Description
• Milestones planning
• Progress So far
• Further Enhancements (TBD)
• Discussion
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3. Background and Impulse towards
topic
Any wireless signal is usually affected from
• Attenuation over distance
• Doppler shift
• Multipath fading
• Interference (Missing)
All are required for analysis and optimization
of the performance of wireless networks
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4. Background and Impulse towards
topic
• LTE advanced – Frequency reuse factor 1
• All frequency resources used in all eNBs
• Leads to high amount of Interference
• Interference based coordination /scheduling
required.
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5. Arbeit Description
• Modeling of interference in ComNets LTE model
for performance analysis of simple scenario.
• Scenario:-
– Two eNBs
– One UE per Base station
– Square topology
– Both Base stations uses same band (100%)
• Without user mobility
• With user mobility
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6. Arbeit Description
• Modules affected
– Mobility Model : For Topology and movement
design
• SINR calculation
• RPL(others) is missing
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7. Arbeit Description
– MAC Scheduler : For performance analysis of
various current scheduling algorithms
• Blind Equal Throughput
• Maximum Throughput
• Proportional Fair
• Optimized Service Aware
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8. Arbeit Description
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9. Progress So Far
• Understanding of OPNET simulator
• Understanding of Mobility Model
• Understanding of MAC scheduler
• Proposal for changes in Mobility Model
– For topology
– For mobility
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10. Milestones TBD
March • 15th March : Code implementation of 2 eNB scenario
• 30th March : Code validation and Test Runs
April
• 15th April : Collection of Results
• 20th April : First Interim Report Discussion
• 30th April : Calibration/Enhancement of Model
• 15th-30th April : Parallel Report Writing
• 7th May : Comparison of results to a standard model(3GPP)
May • 15th May : Detailed Analysis and additional Enhancements
• 22th May : Further Result collection (if required)
• 30th May: Final Presentation of project and Report Submission
• May : Parallel report writing
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11. Further Discussions
• Interference coordinated MAC scheduling
• Multi UE scenarios
• Multi Base Station scenarios
– With User mobility
– Without User mobility
Open ended discussion
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12. A Distributed Interference-aware Load balancing
Algorithm for LTE Multi-Cell Networks
• Problem formulation
– Concave utility function, s.t. constrains
– Convex program with a concave objective function
• Lagrangian relaxation (duality)
– Decompose into subproblems by relaxing the constrains (load
distribution, BS assignment, bandwidth allocation)
• Solution for Lagrangian relaxation
– Solving the subproblems
– Optimal solution
– Ascent methods (several steps), cover the integer constrains
• Cellular network aspects (each step)
– Distributed algorithm for the optimal LB, considering e.g. HO user
pair, HO criterion, candidate user sets…
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13. Utility-Based Resource Allocation for Mixed
Traffic in Wireless Networks
• Utility function
– QoS users: Sigmoid function (convex, concave)
– BE users: Concave function
• Solution
– Lagrangian method with Karush-Kuhn-Tucker condition (KKT)
– Sufficient conditions for optimal allocation derived
• Algorithms
– I. QoS users only
– II. BE users only
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14. Institute of Communication Network
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