Effectiveness of Cell Outage Compensation in LTE Networks Mehdi Amirijoo, Ericsson, Sweden Ljupco Jorguseski, TNO, The Netherlands CCNC ‘11 Remco Litjens, TNO, The Netherlands January 10, 2011 Renato do Nascimento, Alcatel-Lucent, Portugal Las Vegas, USA
OUTLINE • INTRODUCTION • ASSESSMENT APPROACH • NUMERICAL RESULTS • CONCLUDING REMARKS
OUTLINE • INTRODUCTION • ASSESSMENT APPROACH • NUMERICAL RESULTS • CONCLUDING REMARKS
INTRODUCTION • LTE • Mobile cellular network technology 2011 LTE • E-UTRAN, a.k.a. ‘Long Term Evolution’ • Standardised by 3GPP R8-… 2006 + HSPA + HSDPA + HSDPA • 3.9G successor to UMTS • Key features 2003 UMTS UMTS UMTS • OFDM • MIMO 2001 • SON + GPRS • … 1994 GSM 1989 NMT 900 1985 NMT 450 1980 OBLB
INTRODUCTION • Cell outage management / self-healing • Automatic detection and compensation of ‘outages’ • eNodeB failure, cell failure, Control physical signal/channel failure parameters • Enhances robustness/resilience Operator policy: Coverage, QoS Compensation -70 2000 -80 1500 -90 1000 -100 500 -110 0 -120 Measurements -130 Detection -500 -140 -1000 -150 -1500 Coverage/QoS -160 -2000 -170 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 map estimation
INTRODUCTION • Cell outage management / self-healing • Control parameters • Transmit power settings • Antenna downtilt • Azimuth/beamforming • Scheduler’s fairness parameter • Intra/inter-RAT handover parameters, load balancing • Neighbour cell lists • …
INTRODUCTION • Cell outage management / self-healing • Control parameters • Transmit power settings DOWNLINK UPLINK • P 0 ≡ target received power density (per RB) • P MAX = P PILOT + P DATA = fixed • Raising P PILOT increases coverage, • Reducing P 0 lowers inter-cell interference but decreases P DATA and hence the levels and hence increases coverage traffic handling capacity/quality • Reducing P 0 lowers the achievable MCS • An increased coverage also implies and hence throughput/QoS per RB more absorbed traffic, hence more • An increased coverage also implies resource sharing and less per-user QoS more absorbed traffic, hence more resource sharing and less per-user QoS
INTRODUCTION • Cell outage management / self-healing • Control parameters • Antenna downtilt • Raising TILT increases coverage, but also increases inter-cell interference • An increased coverage also implies more absorbed traffic, hence more resource sharing and less per-user QoS
INTRODUCTION • Objective TO ASSESS THE EFFECTIVENESS OF P PILOT , P 0 AND TILT IN MITIGATING THE EFFECTS OF CELL OUTAGES IN DIFFERENT SCENARIOS
OUTLINE • INTRODUCTION • ASSESSMENT APPROACH • NUMERICAL RESULTS • CONCLUDING REMARKS
ASSESSMENT APPROACH • Scenarios • Diverse aspects are of potential interest … • Site density • Traffic load • Service mix • Spatial traffic distribution • User mobility • Propagation environment • …
ASSESSMENT APPROACH • Scenarios • COV L Coverage-oriented network layout with low traffic load • CAP L Capacity -oriented network layout with low traffic load • CAP M Capacity -oriented network layout with medium traffic load • CAP H Capacity -oriented network layout with high traffic load Capacity-driven layout Coverage-driven layout Inter-site distance 500 m 2200 m 15 o 5 o Antenna downtilt System bandwidth 10 MHz P MAX,BS , P RS , P MAX,UE 46 dBm, 33 dBm, 25 dBm Path loss 128.1 + 37.6 log 10 r , with r in km σ = 8 dB, inter-site correlation of ½, decorrel. Shadowing distance = inter-site distance / 15 Antenna model 3GPP 3D model Noise level -199 dBW/Hz in DL, -195 dBW/Hz in UL Generic elastic data service with a requested Service throughput of 1 Mb/s (DL) & 250 kb/s (UL)
ASSESSMENT APPROACH • Performance metrics • Coverage probability • Uplink/downlink user throughput • Fraction of satisfied users, where ‘satisfied’ is … • Covered • Uplink throughput ≥ α × 250 kb/s • Downlink throughput ≥ α × 1 Mb/s • ... and α reflects the operator policy in that it expresses the relative importance of coverage and quality • When applicable, metrics are assessed over first tier of tells surrouding the outage area
OUTLINE • INTRODUCTION • ASSESSMENT APPROACH • NUMERICAL RESULTS • CONCLUDING REMARKS
NUMERICAL RESULTS PRE-OUTAGE SITUATION PRE-OUTAGE SITUATION PRE-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION WITHOUT COMPENSATION WITHOUT COMPENSATION WITHOUT COMPENSATION WITH OPTIMISED P PILOT WITH OPTIMISED P PILOT WITH OPTIMISED P PILOT PROBABILITY PROBABILITY PROBABILITY COVERAGE COVERAGE COVERAGE THROUGHPUT THROUGHPUT THROUGHPUT UPLINK USER UPLINK USER UPLINK USER DOWNLINK USER DOWNLINK USER DOWNLINK USER THROUGHPUT THROUGHPUT THROUGHPUT
NUMERICAL RESULTS PRE-OUTAGE SITUATION PRE-OUTAGE SITUATION PRE-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION WITHOUT COMPENSATION WITHOUT COMPENSATION WITHOUT COMPENSATION WITH OPTIMISED P 0 WITH OPTIMISED P 0 WITH OPTIMISED P 0 PROBABILITY PROBABILITY PROBABILITY COVERAGE COVERAGE COVERAGE THROUGHPUT THROUGHPUT THROUGHPUT UPLINK USER UPLINK USER UPLINK USER DOWNLINK USER DOWNLINK USER DOWNLINK USER THROUGHPUT THROUGHPUT THROUGHPUT
NUMERICAL RESULTS PRE-OUTAGE SITUATION PRE-OUTAGE SITUATION PRE-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION POST-OUTAGE SITUATION WITHOUT COMPENSATION WITHOUT COMPENSATION WITHOUT COMPENSATION WITH OPTIMISED TILT WITH OPTIMISED TILT WITH OPTIMISED TILT PROBABILITY PROBABILITY PROBABILITY COVERAGE COVERAGE COVERAGE THROUGHPUT THROUGHPUT THROUGHPUT UPLINK USER UPLINK USER UPLINK USER DOWNLINK USER DOWNLINK USER DOWNLINK USER THROUGHPUT THROUGHPUT THROUGHPUT
NUMERICAL RESULTS COVERAGE-DRIVEN LAYOUT (LOW LOAD) COVERAGE-DRIVEN LAYOUT (LOW LOAD) CAPACITY-DRIVEN LAYOUT (LOW LOAD) CAPACITY-DRIVEN LAYOUT (LOW LOAD) 1 1 1 1 0.8 0.8 0.8 0.8 FRACTION OF SATISFIED USERS FRACTION OF SATISFIED USERS FRACTION OF SATISFIED USERS FRACTION OF SATISFIED USERS 0.6 0.6 0.6 0.6 0.4 0.4 0.4 0.4 0.2 0.2 0.2 0.2 0 0 0 0 pre-outage (reference) pre-outage (reference) post-outage (no post-outage (no post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised pre-outage (reference) pre-outage (reference) post-outage (no post-outage (no post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised PRE-OUTAGE PRE-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE PRE-OUTAGE PRE-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE compensation) compensation) tilt) tilt) P_0) P_0) P_RS) P_RS) compensation) compensation) tilt) tilt) P_0) P_0) P_RS) P_RS) (REFERENCE) (REFERENCE) (NO COMPENSATION) (NO COMPENSATION) (OPTIMISED TILT) (OPTIMISED TILT) (OPTIMISED P 0 ) (OPTIMISED P 0 ) (OPTIMISED P PILOT ) (OPTIMISED P PILOT ) (REFERENCE) (REFERENCE) (NO COMPENSATION) (NO COMPENSATION) (OPTIMISED TILT) (OPTIMISED TILT) (OPTIMISED P 0 ) (OPTIMISED P 0 ) (OPTIMISED P PILOT ) (OPTIMISED P PILOT ) CAPACITY-DRIVEN LAYOUT (MEDIUM LOAD) CAPACITY-DRIVEN LAYOUT (MEDIUM LOAD) CAPACITY-DRIVEN LAYOUT (HIGH LOAD) CAPACITY-DRIVEN LAYOUT (HIGH LOAD) 1 1 1 1 0.8 0.8 0.8 0.8 FRACTION OF SATISFIED USERS FRACTION OF SATISFIED USERS FRACTION OF SATISFIED USERS FRACTION OF SATISFIED USERS 0.6 0.6 0.6 0.6 0.4 0.4 0.4 0.4 0.2 0.2 0.2 0.2 0 0 0 0 pre-outage (reference) pre-outage (reference) post-outage (no post-outage (no post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised pre-outage (reference) pre-outage (reference) post-outage (no post-outage (no post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised post-outage (optimised PRE-OUTAGE PRE-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE PRE-OUTAGE PRE-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE POST-OUTAGE compensation) compensation) tilt) tilt) P_0) P_0) P_RS) P_RS) compensation) compensation) tilt) tilt) P_0) P_0) P_RS) P_RS) (REFERENCE) (REFERENCE) (NO COMPENSATION) (NO COMPENSATION) (OPTIMISED TILT) (OPTIMISED TILT) (OPTIMISED P 0 ) (OPTIMISED P 0 ) (OPTIMISED P PILOT ) (OPTIMISED P PILOT ) (REFERENCE) (REFERENCE) (NO COMPENSATION) (NO COMPENSATION) (OPTIMISED TILT) (OPTIMISED TILT) (OPTIMISED P 0 ) (OPTIMISED P 0 ) (OPTIMISED P PILOT ) (OPTIMISED P PILOT )
OUTLINE • INTRODUCTION • ASSESSMENT APPROACH • NUMERICAL RESULTS • CONCLUDING REMARKS
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