LTE/LTE-A SON     (for Femtocells)                                                                 Mischa Dohler          ...
System Degrees of Freedom [1/2]      Degrees of Freedom (DOF) / Area:               new system DOF = old system DOF     ...
System Degrees of Freedom [2/2] With femtocells, the DOF  increases significantly!                                        ...
Likelihood of Failure/Outage     Important High‐Level Insides:               DOF/area increases  failures/outages incre...
Importance of SON      Previously Manual Processes:               reduce manual intervention for deployment savings     ...
Elements of SON      Important Elements:               elements of “autonomous”               elements of “distributed”...
SON in Cellular Networks                                                            Automated                             ...
Presentation Overview     1. SON in NGMN & 3GPP LTE     2. SON Architectural Elements     3. 3GPP SON Features     4. 3GPP...
1. SON in NGMN & 3GPP LTECopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved   9
NGMN’s Input To SON     Next Generation Mobile Networks       (NGMN) Alliance:               created in 2006 by group of...
3GPP High‐Level Structure                                                                                                 ...
SON in 3GPP LTE Release 8     3GPP R8 is about eNB self‐configuration:               automatic neighbor relation        ...
SON in 3GPP LTE Release 9     3GPP R9 is about network optimization procedures:               mobility robustness and ha...
SON in 3GPP LTE‐A Release 10     3GPP R10 is about overlaid networks:               coverage & capacity optimization    ...
SON in 3GPP LTE‐A Release 11     3GPP R11 will be about heterogeneous networks:               automated network manageme...
3GPP SON Status                  Rel8                                                 Rel9                                ...
2. SON Architectural ElementsCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved   17
SON Architecture Approaches [1/2] Levels of SON Execution:      localised: autonomous SON                               ...
SON Architecture Approaches [2/2]            centralized           distributed                                         loc...
Key Time Intervals      For Centralised SON, timing is important:               Collection Interval: time period during ...
Important SON Trade‐Offs                   faster & less prone to “single point of failure”                               ...
Coordinated SON Model  very difficult to standardise:                                                                    ...
BeFEMTO HeNB Architecture       Management       Functions         Perform.          Mgmt                                 ...
3. 3GPP SON FeaturesCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved   24
SON in Cellular Networks                                                            Automated                             ...
SON Functions (NGMN & 3GPP)                                                   Automated                                   ...
Automated Planning      From “trial & error” to “planning automation”:                                                   ...
Self‐Configuration      Important Self‐Configuration Functions:               authentication               address allo...
Self‐Optimisation             3GPP             • Automatic Neighbour Relation             • Mobility Robustness/Handover O...
Self‐Healing   Important Self‐Configuration Functions:           failure recovery           cell outage compensation Co...
4. 3GPP SON Functional DetailsCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved   31
eNB Self‐Configuration (Rel. 8)  Benefits:            reduction of manual labour           faster and cheaper network d...
Benefits:              keeping centralized neighborhood tables is impossible             automating this is one of the ...
PCI Selection (Rel 8/9)     Planned/Centralised PCI               direct value is assigned (3 x 168 = 504 in total only!...
PCI Selection ‐ Collisions PCI collision probability depends on the number of PCIs  available for such cells PCI reporte...
MRO (Rel‐9, ext Rel‐10)Mobility Robustness Optimization (MRO) because …… Handovers (HOs) between same (intra) and differ...
MRO (Rel‐9, ext Rel‐10)   Mobility Robustness Optimization           detect radio link connection failures due to being ...
MRO (Rel‐9, ext Rel‐10)                                                             OAM                                   ...
MLB (Rel‐9) Mobility Load Balancing           Distribute cell load evenly among cells or           Transfer part of tra...
MLB – Active Mode LB                                                                                       OAM            ...
RACH optimisation (Rel 9)  Optimises the (P)RACH configuration access to internal    measurements and access to feedback ...
Min. Drive Tests (R10 procedure)   Performs logging of available measurements together with     location and time for log...
Coverage and Capacity Opt (Rel‐10) Coverage definition         “coverage hole” (should cover UL also)                  ...
Energy Saving   Optimise energy consumption: a cell providing additional capacity can be     switched off when its capaci...
5. ConclusionsCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved   45
SON Conclusions Benefits of SON:            reduction of human intervention           real‐time optimization of network...
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LTE/LTE-A SON (for Femtocells)

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Transcript of "LTE/LTE-A SON (for Femtocells)"

  1. 1. LTE/LTE-A SON (for Femtocells) Mischa Dohler CTTC, Spain Manuel Palmowski & Dimitri Marandin mimoOn, GermanyCopyright © 2009 BeFEMTO– Broadband Evolved FEMTO Network. All Rights reservedCopyright © 2009  BeFEMTO–Broadband Evolved FEMTO Network. All Rights reserved. 1
  2. 2. System Degrees of Freedom [1/2] Degrees of Freedom (DOF) / Area:  new system DOF = old system DOF                x 20‐30  new system density = old system density     x 4  new DOF/km2 = old DOF/km2                       x 100 1E+12 1E+10 00000000 1000000 CELLULAR + WIFI + FEMTO CELLULAR + WIFI 10000 CELLULAR 100 1 GSM EDGE UMTS HSPA LTE LTE‐A Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 2
  3. 3. System Degrees of Freedom [2/2] With femtocells, the DOF  increases significantly! [presented by Interdigital: Globecom’11 – IWM2M, Houston] Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 3
  4. 4. Likelihood of Failure/Outage Important High‐Level Insides:  DOF/area increases  failures/outages increase: [© http://www.sciencedirect.com/science/article/pii/S0951832004000031]  loss in revenue if nothing done, and/or  very costly if addressed by human labour Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 4
  5. 5. Importance of SON  Previously Manual Processes:  reduce manual intervention for deployment savings  automate repetitive processes  examples: automatic planning & self‐configuration  Too Fast/Complex Processes:  improve run‐time operation based on real‐time data  automate optimization of critical network elements  example: self‐optimization & self‐healing  SON automation, however, is not new but rather a  further evolution of prior automation efforts Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 5
  6. 6. Elements of SON  Important Elements:  elements of “autonomous”  elements of “distributed”  elements of “intelligent/cognitive”  elements of “optimality”  SON ≠ SON:  despite large DOF, SON has to be (close to) optimal  since it makes no sense to have a system with amazing  components which however underperforms due to poor  “management” Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 6
  7. 7. SON in Cellular Networks Automated  Planning Planning Self  Configuration Deployment Self  Optimisation/ Optimisation Maintenance Self        Healing Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 7
  8. 8. Presentation Overview 1. SON in NGMN & 3GPP LTE 2. SON Architectural Elements 3. 3GPP SON Features 4. 3GPP SON Functional Details 5. Conclusions Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 8
  9. 9. 1. SON in NGMN & 3GPP LTECopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 9
  10. 10. NGMN’s Input To SON Next Generation Mobile Networks  (NGMN) Alliance:  created in 2006 by group of operators  business requirements driven  often based on use‐cases of daily  networking routines  NGMN and SON:  SON input to 3GPP since 2006  10 SON use cases have been defined  (see right) which input to 3GPP Rx  QoS SON is likely to appear shortly Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 10
  11. 11. 3GPP High‐Level Structure Management!  maintenance/  maintenance/  system   CN interfaces,  development development architecture, service  protocols,  of GSM/GPRS/ of UMTS/HSPA/ capabilities, codecs  interworking, IMS,  EDGE RAN LTE RAN (inc. EPC)  terminals, SIM   Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 11
  12. 12. SON in 3GPP LTE Release 8 3GPP R8 is about eNB self‐configuration:  automatic neighbor relation  automatic physical cell ID (PCI) assignment  automatic inventory  automatic software download Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 12
  13. 13. SON in 3GPP LTE Release 9 3GPP R9 is about network optimization procedures:  mobility robustness and handover optimization  RACH optimization  load balancing optimization  inter‐cell interference coordination (ICIC) Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 13
  14. 14. SON in 3GPP LTE‐A Release 10 3GPP R10 is about overlaid networks:  coverage & capacity optimization  enhanced ICIC  cell outage detection and compensation  self‐healing functions  minimize drive test  energy savings Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 14
  15. 15. SON in 3GPP LTE‐A Release 11 3GPP R11 will be about heterogeneous networks:  automated network management  troubleshooting   multi‐layer, multi‐RAT heterogeneous networks  among other issues Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 15
  16. 16. 3GPP SON Status Rel8 Rel9 Rel10 ANR PCI_Sel. MLB, MRO, RACH MLB, MRO,CCO RAN Energy Saving (ES) Minimize Drive Test (MDT) PCI_Selection Energy Saving SA5 MDTANR = Automatic Neighbor RelationPCI  = Physical Cell IDMLB = Mobile Load Balancing Self‐HealingMRO = Mobility Robustness Opt.RACH = Random Access Channel SON MgmtCCO = Capacity & Coverage Opt. Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 16
  17. 17. 2. SON Architectural ElementsCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 17
  18. 18. SON Architecture Approaches [1/2] Levels of SON Execution:  localised: autonomous SON  NM SON execution based on purely local  information at (H)eNB & UE  distributed: autonomous SON  DM/EM DM/EM execution based on information  exchanged with neighbouring  SON SON (H)eNB (eg via X2 interface)  centralized: decision taking  based on (fairly complete)  system information (eg at  NM/DM/EM levels) X2 SON SON  hybrid: any mixture of above NM = Network Management DM = Device Management EM = Element Management Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 18
  19. 19. SON Architecture Approaches [2/2] centralized           distributed  localised hybridKPI = Key Performance Indicator Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 19
  20. 20. Key Time Intervals  For Centralised SON, timing is important:  Collection Interval: time period during which statistics  and data are collected; limited by vendor’s OAM  bandwidth; typical 5min (i.e. not at scheduling level!)  Analysis Interval: time period needed to draw decision;  typically several collection intervals (filtering effect by  considering also prior data history)  Change Interval: time period between executing the  changes in the network; typically limited by system’s  operational constraints Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 20
  21. 21. Important SON Trade‐Offs faster & less prone to “single point of failure” info from number of cells/RATs Centralised Distributed Localised multiple cells normally  ca. 2 cells adv. RRM long term statistics uses X2 small impact on ncells uses OAM  short term statistics multi‐vendor/multi‐ multi‐vendor (X2)  RAT self‐configuration handover opt. scheduler opt coverage optimisation load balancing Link adapt. opt (load balancing) RACH opt RACH opt Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 21
  22. 22. Coordinated SON Model  very difficult to standardise: management  lots of different ways to  implement a SON function are  possible  e.g. load balancing (LB) done  at NM level but handover (HO)  optimization done at eNB level  and both want to adjust the same  parameter in eNB decision taking feedback  practical way around today:  if function at NM level,  “configure” is standardised execution  at eNB level not standardised  currently primary & secondary  targets are defined [based on S5‐102029] Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 22
  23. 23. BeFEMTO HeNB Architecture Management Functions Perform. Mgmt SON Enabling Functions Fault Diag. Coverage  Network  Context Positioning Probe Estimation Sync Learning … Security network users SO-RRIM Local Netw Radio SON  Sub-functions Elem Agent Coordinator EAP‐ Energy SOAP  AKA Saving RPC Network SO‐RRIM S1AP/ Mobility  Functions HTTPS IKEv2 RRC X2AP Control GTP‐U PDCP Load Local TCP/ Balancing Location TCP SCTP UDP Mgmt. UDP RLC Admission Control IP/IPsec MAC Scheduler Routing … Geo Sublayer BB MAC PHY NMM PHY RF S1 / X2 / Type 1C / Rt /Lm  interfaces Uu / Un interfaces Network /Mgmt Functions Protocol Stacks Radio Functions Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 23
  24. 24. 3. 3GPP SON FeaturesCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 24
  25. 25. SON in Cellular Networks Automated  Planning Planning Self  Configuration Deployment Self  Optimisation/ Optimisation Maintenance Self        Healing Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 25
  26. 26. SON Functions (NGMN & 3GPP) Automated  Self‐Optimisation Planning Self‐ Configuration Self‐Healing Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 26
  27. 27. Automated Planning  From “trial & error” to “planning automation”: [© ICT MOMENTUM] Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 27
  28. 28. Self‐Configuration  Important Self‐Configuration Functions:  authentication  address allocation  secure OAM tunnel setup  SW installation  inventory management  transport parameters setup  radio parameters setup  self‐test Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 28
  29. 29. Self‐Optimisation 3GPP • Automatic Neighbour Relation • Mobility Robustness/Handover Optimisation • (Mobility) Load Balancing • RACH Optimisation • Coverage and Capacity Optimisation • Energy Saving • Interference Coordination • HeNB SON additional from Socrates/NGMN (not discus) • QoS Optimisation (advanced RRM) • Scheduler • admission control • congestion control • link level/L2/HARQ re‐tx/MIMO parameters Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 29
  30. 30. Self‐Healing  Important Self‐Configuration Functions:  failure recovery  cell outage compensation Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 30
  31. 31. 4. 3GPP SON Functional DetailsCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 31
  32. 32. eNB Self‐Configuration (Rel. 8) Benefits:   reduction of manual labour  faster and cheaper network deployment Description:   detect transport link & establish connection  download & upgrade software  set up initial configuration parameters  perform self‐test  go into “operational” mode Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 32
  33. 33. Benefits:   keeping centralized neighborhood tables is impossible  automating this is one of the most important SON features Description:   keep updated neighborcell (ncell) table through UE  obtain ECGI & IP via MME  to communicate to target eNBECGI = E‐UTRAN Cell Global IdentifierOAM = Operating Administration & MaintenanceMME = Mobility Management EntityRRC = Radio Resource ControlerTCI = Target Cell Identifier Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 33
  34. 34. PCI Selection (Rel 8/9) Planned/Centralised PCI  direct value is assigned (3 x 168 = 504 in total only!) SON/Distributed PCI selection  a range of PCIs is given eNB will not select cell IDs that are reported by UEs reported over the X2 interface (not for HeNB as of now) acquired through NW listen mode (will not catch all) select PCI value randomly from the remaining PCIs PCI collisions: >1 eNB seeing each other choose same IDPCI = Physical Cell ID Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 34
  35. 35. PCI Selection ‐ Collisions PCI collision probability depends on the number of PCIs  available for such cells PCI reported belongs to two different ECGI Collision recovery 500 non‐macro eNBs (e.g. HeNBs) dropped randomly in each macro eNB [R3‐091018] Number of PCIs Percentage of UEs Percentage of UEs Percentage of UEs available for observing collision of observing collision of PCIs observing collision of PCIs non-macro eNBs PCIs with random PCI with random PCI with random PCI allocation allocation allocation plus downlink plus downlink receiver receiver (sensitivity at -6 (sensitivity at -8 dB) dB) 10 15.2% 12.2% 11.7% 50 3.3% 2.6% 2.4% 100 1.7% 1.3% 1.2% 200 0.9% 0.7% 0.6% Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 35
  36. 36. MRO (Rel‐9, ext Rel‐10)Mobility Robustness Optimization (MRO) because …… Handovers (HOs) between same (intra) and different  (inter) radio access technologies (RATs) can go very wrong: too late handover (HO): too early intra‐RAT HO: wrong cell intra‐RAT HO: Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 36
  37. 37. MRO (Rel‐9, ext Rel‐10)  Mobility Robustness Optimization  detect radio link connection failures due to being too early, too late handovers or handover to wrong cells  caused by not optimised intra/inter‐RAT handover parameters  also used for optimising idle mode cell reselection parameters  UE sends Radio Link Failure (RLF) measurement report to eNB where UE did re‐establishment  Optimised for Rel‐10 to use also ConnectionRequest too early handover Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 37
  38. 38. MRO (Rel‐9, ext Rel‐10) OAM monitor KPIs, alarms: config target: Nr of HO events Rate of failures related to  Nr of HO failures HO Nr of too early HO eNB RRM config examples: MRO Trigger Threshold Time‐to‐Trigger Hysteresis against Ping‐Pong Mobility Speed & Neighbour Param. Control Electric Antenna Tilt Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 38
  39. 39. MLB (Rel‐9) Mobility Load Balancing   Distribute cell load evenly among cells or   Transfer part of traffic to other cells so that radio resources remain highly  utilized   Optimisation of mobility parameters or handover actions  Also includes setting of cell reselection mode for idle mode balancing Load Reporting  the radio resource usage (UL / DL PRB usage)  HW and TNL load indicator (UL/DL load: low, mid, high, overload)  a cell capacity class indicator and capacity value (UL / DL) PRB  = Physical Resource BlockTNL = Transport Network LayerHW = HardwareUL = uplinkDL = DownlinkRAB = Radio Access Bearer (next slide) Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 39
  40. 40. MLB – Active Mode LB OAM config target: monitor KPIs, alarms: ‐ RAB setup failure rate due to load Nr RAB setup failure due to load ‐ Rate of failures related to HO Total nr of RAB setup failureTarget  Serving eNB RRM configeNB LOAD INFO HO Trigger MOBILITY CHANGE MLB ‐/+ 10dB   target cell is informed (incr/reduce   proposed source cell  time until HO  decision) change Mobility  proposal for target cell  change Control Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 40
  41. 41. RACH optimisation (Rel 9)  Optimises the (P)RACH configuration access to internal  measurements and access to feedback from UEs (via RRC) and  from other (H)eNBs  The setting of RACH parameters that can be optimized are:   RACH configuration (resource unit allocation), preamble groups split,  backoff, power control  UEs which receive UEInformationRequest shall feedback: Number of RACH preambles sent until the successful RACH  completion (indication of quality of link) Contention resolution failure (indication of cell load)  X2 allows to exchange RACH config between eNBs  Rel 10 OAM policy targets: Access Probability and Access Delay  Probability Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 41
  42. 42. Min. Drive Tests (R10 procedure)  Performs logging of available measurements together with  location and time for logged measurement configured UEs  Types: Immediate and logged measurements  Immediate measurements (UE optional FFS) Reuses normal measurements with addition of location  Enhancement of RLF Report to include location  Idle mode logged measurements (UE optional) Input: duration, interval, cell ids and/or tracking areas Time, Location, Cell id, scell/ncell RSRP/Q  Add. eNB meas: eNB RIP and CQI under disc, + PHR and UL SINR  MDT activation via OAM per cell/region (not reused at HO)  S1 UE specific trace activation (can be cont. on HO) Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 42
  43. 43. Coverage and Capacity Opt (Rel‐10) Coverage definition “coverage hole” (should cover UL also) unsuccessful RX of DL control channels and signalling radio bearers different control channels have to be optimised jointly “weak coverage”: cell‐edge users, minimum service rate  not reached Types of coverage holes other RATs/no radio, coverage too small/too large CCO detection using MDT/MRO  Inputs: UE measurements, Performance measurements,  alarms  Outputs: power control, antenna tilt, azimuth  Capacity & Coverage improvements Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 43
  44. 44. Energy Saving  Optimise energy consumption: a cell providing additional capacity can be  switched off when its capacity is no longer needed and to be re‐activated  when needed  The decision typically based on cell load information  Peer eNBs are about the switch‐off over the X2 interface (eNB  Configuration Update procedure)  Informed eNBs keep the cell config when a cell is off and may request re‐ activation if needed (X2: Cell Activation procedure)  How to select to correct cell to switch‐on?  The operators can configure ES function:  enable/disable ES  OAM policies for switch‐off and reactivation  open   interRAT, overlaid inter‐eNB savings  solutions to capacity limited scenario of inter‐eNB energy saving  ES in network sharing Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 44
  45. 45. 5. ConclusionsCopyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 45
  46. 46. SON Conclusions Benefits of SON:   reduction of human intervention  real‐time optimization of network  significant CAPEX & OPEX savings! NGMN & 3GPP:   important SON features standardised from R8‐R11  focus shifting from auto‐planning & self‐configuration towards self‐optimization and self‐healing  most important SON features have been discussed in this presentation  whereas concrete embodiments of SON comes later today Copyright © 2009  BeFEMTO– Broadband Evolved FEMTO Network. All Rights reserved 46

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