ra self tuning on lte
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Random Acces Channel Self-Tuning in LTE
Blanca GONZÁLEZ Francisco MICÓ
SUMMARY
• Introduction • Random access in LTE • Self Optimizing Networks • Case study: Self-tuning of random access • Conclusion
page 1 Summary
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.
• Transitions from Idle state to Connected • Recovering from radio failure • Exceptionally, to send a Scheduling Request if no
other uplink resource is allocated.
page 2 What is RA?
Contention resolution
page 3 How works RA?
¢ Random access procedure:
A wide range of parameters
¢ PRACH design
page 4 Inside PRACH
PRACH
Format
Sequence
Duration
Preamble
Banswidth
Length
Cyclic shift
CP
GT
Resource configuration
Load
Interferences
page 5
What is SON?
RACH Self-Tuning Introduction to SON
Source: Self-Organizing Networks (SON) in 3GPP Long Term Evolution. Sujuan Feng, Eiko Seidel Nomor Research GmbH, Munich, Germany 20th of May 2008
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
page 6
SON use cases ¢ Revenues of Mobile network depend (++) on its operational
efficiencyà reduce OPEX ¢ Self-Optimizationàselect and adjust proper algorithms and
system parameters to achieve optimal system capacity and service coverage
¢ 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
Source: 3GPP TR36.902
RACH Self-Tuning Link between RACH and Self-Optimization
page 7
RACH Optimization
¢ Role of RACH • Initial network access without user data
¢ Necessity for RACH optimization • Performance of RACH influences the capacity of
whole mobile network ¢ Possible RACH optimization algorithm • Phy resources • Preambule allocation • Persistence level • Transmission power control
RACH Self-Tuning Role of RACH and optimization necessity
page 8
Key performance metrics
¢ Acces Probability (AP) ¢ Detection Miss Probability (DMP)
¢ Detection Miss Ratio (DMR) ¢ Contention Ratio (CR)
¢ Access Ratio (AR)
RACH Self-Tuning Metrics and Modeling of RA
page 9
Experiments
RACH Self-Tuning tuneables parametres, performance and interferences
¢ Effects of Varying PUSCH Load ¢ Effects of Varying Power Control Parameters ¢ Effects of Varying RACH Load and Configuration ¢ Interference on PUSCH by Random Access
Preambles
CONCLUSION
page 10 RACH Self-Tuning
¢ Performance: heavily affected by the choice of design parameters
¢ LTE possibilities ¢ Self Optimizing Networks : a hot research topic
nowadays ¢ Encouragement and potential
page 11
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 College 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.
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