Random Acces Channel Self-Tuning in LTE Blanca GONZÁLEZ Francisco MICÓ
SUMMARY
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Introduction
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Random access in LTE Self Optimizing Networks
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Case study: Self-tuning of random access
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Conclusion
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Looking for synchronization !
Random access uses: •
Connected UE, not uplink-synchronized – Send new data or control information – Hand-over process – ACK/NACK message in the uplink – Positioning purposes.
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Transitions from Idle state to Connected Recovering from radio failure Exceptionally, to send a Scheduling Request if no other uplink resource is allocated.
Contention resolution !
Random access procedure:
A wide range of parameters !
PRACH design Duration
Banswidth
Preamble
Length
Sequence
Format
CP Cyclic shift GT
PRACH
Load Resource configuration Interferences
What is SON? Rising expectations on QoS, coverage and capacity
Goals !Reduce OPEX (Operational Expenditures) by automating funcionality currently performed manually !Reduce CAPEX (Capital Expenditures) by optimized use of network elements
Source: Self-Organizing Networks (SON) in 3GPP Long Term Evolution.
SON use cases !
Revenues of Mobile network depend (++) on its operational efficiency! reduce OPEX
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Self-Optimization!select and adjust proper algorithms and system parameters to achieve optimal system capacity and service coverage
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8 use cases: » 1. Automatic Neighbor Relation (ANR) » 2. Coverage and Capacity Optimization » 3. Energy Saving » 4. Interference Reduction » 5. Physical Cell ID Automatic Configuration » 6. Mobility Robust Optimization » 7. Mobility Load Balancing Optimization » 8. RACH (Random Access Channel) Optimization
RACH Optimization !
Role of RACH •
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Necessity for RACH optimization •
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Initial network access without user data Performance of RACH influences the capacity of whole mobile network
Possible RACH optimization algorithm •
Phy resources
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Preambule allocation
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Persistence level
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Transmission power control
Key performance metrics !
Acces Probability (AP)
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Detection Miss Probability (DMP)
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Detection Miss Ratio (DMR)
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Contention Ratio (CR)
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Access Ratio (AR)
Experiments !
Effects of Varying PUSCH Load
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Effects of Varying Power Control Parameters
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Effects of Varying RACH Load and Configuration
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Interference on PUSCH by Random Access Preambles
CONCLUSION Performance: heavily affected by the choice of design parameters ! LTE possibilities !
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Self Optimizing Networks : a hot research topic nowadays Encouragement and potential
References [1] Towards Random Access Channel Self-Tuning in LTE. Mehdi Amirijoo, Pål Frenger, Fredrik Gunnarsson, Johan Moe, Kristina Zetterberg Wireless Access Networks, Ericsson Research, Ericsson AB, Sweden [2] Self-Configuration and Self-Optimization for LTE Networks. Honglin Hu and Jian Zhang, Chinese Academy of Sciences Xiaoying Zheng, Chinese Academy of Sciences and Southeast University Yang Yang, Chinese Academy of Sciences and University Col lege London Ping Wu, Uppsala University [3] Challenges in mobile network operation: Towards Self-Optimizing Networks. Martin Döttling1, Ingo Viering2 1: Nokia Siemens Networks GmbH & Co. KG, Munich, Germany 2: Nomor Research GmbH, Munich, Germany [4] Random Access Channel (RACH) Parameters Optimization in WCDMA Systems. Juan Reig, Oscar López-Jiménez, Lorenzo Rubio and Narcis Cardona Departamento de Comunicaciones Universidad Politécnica de Valencia, España. [5] Self Organization Network. “NEC’s proposals for next-generation radio network management”. White paper. [6] LTE. The UMTS Long Term Evolution. From theory to practice. Sesia, Toufik & Baker. Ed: Wiley, second edition.
