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8/16/2019 03 Performance Monitoring
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1 © NSN Siemens Networks RN31573EN30GLA0
Performance Monitoring
3G RANOP RU30
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Course Content
KPI definition
Performance monitoring
Air interface optimization
Traffic monitoring
Capacity enhancement
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Module Objectives
At the end of the module you will be able to:
• Describe 3G RAN performance monitoring hierarchy
• Describe the mechanisms for call analysis related to• Busy hour
• Paging, RRC and RAB setup and access failure
• Session setup failure for NRT and HSPA
• SHO, ISHO, relocation and SCC failure
• RAB, DCH, radio link and HSPA drop• List possible reasons for failures and improvement activities
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KPI analysis hierarchies
Call setup (busy hour, paging, RRC, RAB, PS session)
Call drop (RAB, DCH, radio link)Mobility (SHO, ISHO, relocation)
HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
Performance Monitoring
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Available data can be classified as in the figure below
There is no point to look at detailed data if the “bigger picture” is not clear
More details
More
understandingMore
complexity
More cost and
time in
acquisition
KPIs (e.g. CSSR, CDR by Traffica)
Service level
(RRC / RAB / PS session)
SHO SCC IFHO ISHO
Signalling (RRC, NBAP, RNSAP, RANAP)
Subscriber trace, ICSU logs (NSN internal use only)
Cell resource (TCP, RTWP, codes)
BTS / Iub / RNC resources
Interface trace and probe statistics
KPI analysis hierarchyPerformance data hierarchy
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Availability of neighbour cell
Missing adjacency has impact both
on serving and neighbouring cell
Iub
WBTS
KPIs and counters
detect faults at different layers
- Handover performance
- Traffic
- Cell resources
- Iub signalling
- Cell availability
- Failures due to Radio, BTS, transport
KPI analysis hierarchyCell and cluster specific performance
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Complexity of performance data increases with number of cells in the network
Almost all data have to be analysed at cell or WBTS level
But evaluation over time and comparison between large areas (cities, RNCs)still required
• Cell Availability
• Failures due to Radio, to BTS, to transport
• Handover Performance• Traffic
• Cell Resources
• Iub Signalling
Some data better analysed at RNC level
Here only time evolution and RNC comparison are useful
• Failures due the RNC, Iu, Iur
• NAS and relocation signalling
KPI analysis hierarchyCell and cluster specific performance
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• Too big lists of results will irritate consultants
• Main impacts must be visible and manageable for hands on task• Different tables of different data warehouse must be verifiable
• Data / KPI benchmark should be easy
List top 10-20 worst cells
E.g. those of highest CDR
KPI analysis hierarchyAnalysis priority
Cell ID CDR/%
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Few bad cells (here 3 of 90)
cause already about ¼ of all
drops
Quick fault diagnostics due to priority of worst cells
KPI analysis hierarchyHighest analysis priority for cells of highest failure rate
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Either total number of failures or failure rate (%) can be used
• Total number of failures directly proportional to loss ofincome for operator
• Cell with high failure rate might not have high priority, iftotal traffic is low
To reach more uniform performance
• Consider statistics with some periodicity large enough (e.g.per month)
• Consider filter requesting minimum number of attempts /failures per cell depending on network traffic (reducestatistical fluctuations)
KPI analysis hierarchyHighest analysis priority for cells of highest failure rate
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KPI analysis hierarchies
Call setup (busy hour, paging, RRC, RAB, PS session)
Call drop (RAB, DCH, radio link)Mobility (SHO, ISHO, relocation)
HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
Performance Monitoring
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MAX (CS_VOICE_CALL_DL + CS_DATA_CALL_CONV_DL +
CS_DATA_CALL_STREAM_DL + PS_DATA_CALL_CONV_DL +PS_DATA_STREAM_DL + PS_DATA_CALL_INTERA_DL +
PS_DATA_CALL_BACKG_DL)
Busy hour on the basis of traffic sum
RT and NRT summed every hour
Each counter represents product bit rate * allocation duration
Hour with maximum value taken as BH
0 24 h12 h
Traffic sum RT / NRT
e.g. by NetAct
1 h
1 h
1 h
1 h
BH
CSSR
CDR
Call setup – busy hour
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Busy hour on the basis of data volume (example on RNC level)
Call setup – busy hour
Time / h
Data volume / GByte
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Voice, R99 NRT and HSPA peak traffic can happen at different times
Blocking of specific service not necessarily happening during BH based ontraffic sum
• In loaded networks CSSR taken at weekly BH is relevant
• Failures originate mostly from congestion (Iub, BTS HW (CEs), radio)
• Target call blocking probability designed for BH
• In unloaded networks CSSR taken at weekly BH may not yield the hour with
highest blocking (NRT traffic is taken into account as well as RT one)
On cell level needed to compute BH statistic based on absolute time period(e.g. 16-18h every day)
Daily data may not be accurate enough due to big variations of results(ongoing operation, system failures, sleeping cells, alarms etc.)
Busy hour daily or weekly
Call setup – busy hour
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IuB
Air Interface WBTS HW Resources Transport
UL interference
DL transmisson power
DL Codes
FSP/ WSP capacity (N*) E1 capacity / AAL2 or IP
RLC/MAC
DSP processing
RNC
During call setup (RRC, RAB, PS session)
several resource areas are checked and
physical / logical resources allocated
Resource checks
Call setup – bottlenecks
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UE BS RNC CN
PagingPaging type 1
RRC connection request
Paging types
Call setup – paging
UE in RRC idleE.g. incoming RT or NRT call
Paging
Paging type 1
RRC cell update
Paging
Paging type 2
RRC cell update
UE in Cell_PCH or URA_PCH
E.g. inactive NRT RAB andincoming voice call
UE in Cell_FACH or Cell_DCH
E.g. active NRT RAB andincoming voice call
Incoming dataPaging type 1
RRC cell update
UE in Cell_PCH or URA_PCH
NRT RAB inactive, but still dataarriving from core network
RNC pages UE to take the data
C
N i
n i t i a t e d
R N C i
n i t i a t e d
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Paging channels
Call setup – paging
• PCH with 8 Kbit/s
• Standard implementation
• With 80 bit per page message up to 100 pages / s supported per cell
• Has SF256
• Default power setting 5 dB below CPICH (28 dBm = 0.63 W, 3% of
maximum power of 20 W cell)
• PCH with 24 Kbit/s
• Optionally available since RU20
• With 80 bit per page message up to 300 pages / s supported per cell
• Has SF128 → Maximum of 14 codes for HSDPA, if additionally HSUPA
with 2ms TTI in use
• Default power setting 2 dB below CPICH (31 dBm = 1.26 W, 6% of
maximum power of 20 W cell)
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Code tree with 24K PCH
Call setup – paging
Cch,256,0
Cch,256,1
Cch,256,2
Cch,256,3
Cch,128,4
Cch,128,5
CPICH
P-CCPCH
AICH
PICHCch,64,1
Cch,256,14
S-CCPCH 1 FACH
E-AGCH 10 ms
HS-SCCH
E-HICH & E-RGCH
S-CCPCH 2 PCH with 24 K
Cch,128,6
Cch,16,0
Cch,256,15
E-AGCH 2 ms
HSUPA with 2ms TTI requiresadditionally fractional DPCH
For F-DPCH no place on firstsub-tree any more
But loss of 1 HSDPA code notcritical
Probability, that air interfaceallowes 15 codes, usually lessthan 1:1000
Loss of 3% of maximum cellpower by 24K PCH much moresignificant
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Paging monitoring
Call setup – paging
Check number of pagemessages forwarded to PCH
(M1006)
Paging Type 1 Att CN Orig
Messages originating fromcore network
Paging Type 1 Att RNC Orig
Messages originating fromRNC
Check number of pagestransmitted by PCH
(M1000)
Ave PCH Throughput /
PCH Throughput Denom 0 =
Throughput on PCH
Throughput / 80 Bit =
Number of pages per second
Difference
Pages lost by PCH blocking
Check number of responsesto paging
(M1006)
Difference
Low air interface performance
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RRC connection setupRAN resources reserved forsignaling connection between UEand RNC
RRC accessConnection between UE and RRC
RRC active UE has RRC connection
If dropped, also active RAB dropped
RAB setup Attempts to start call
RAB setup access
Connection between UE and core
RAB active phaseUE has RAB connection
CSSR affected if any of the following
events takes place
• RRC Connection Setup Fail
• RRC Connection Access Fail• RAB Setup Fail
• RAB Setup Access Fail
Setup
Complete
Access
Complete
Active
Complete
Setup Access Active
A t t e m p t s
Setup failures(blocking)
Access failures
A c c
e s s Active
Release
Active
FailuresRRCDrop
S u c c e s s
Phase:
RRC and RAB
Call setup - phases
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[RACH] RRC Connection Request
UE Node B RNC
ALCAP ERQ
NBAP RL Setup Request
[DCH] RRC Connection Setup Complete
L1 Synchronisation
Start TX/RX
Start TX/RX
[FACH] RRC: RRC Connection Setup
NBAP RL Setup Response
AC to check to acceptor reject RRC
Connection Request
ALCAP ECF
NBAP Synchronization Indication
RRC Connection Setup
phase
RRC Connection
Access phase
RRC Connection Active phase
Allocation of UTRAN
resources
Waiting for UE reply
M1001C0
Counter
M1001C1
M1001C8
Three phase for RRC
Call setup – successful RRC establishmentSignalling and trigger
M1001C8
M1001C0
= successful RRC
establishment
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BTSUE RNC CN
RRC connection Request
RRC connection Setup
RRC SETUP phase
(Resource Reservation in RNC)
RRC ACCESS phase
(RNC waits for Reply from UE)
RRC connection Setup Complete
RRC: Initial Direct Transfer
RANAP: Initial UE Message
RANAP: Iu Release Command
UE-CN Signalling
(E.g. RAB Establishment and Release)
RRC: RRC connection Release
RRC: RRC connection Release Complete
Release RRC resources in RNC, BTS,
Transport
RRC ACTIVE phase
RRC ACCESS fails if
UE does not reply to RRC CONNECTION SETUP message with RRC
CONNECTION SETUP COMPLETE message within given time
BTS reports radio link synchronisation failureRNC internal failure occurs
RRC SETUP fails if some of needed resources (RNC, BTS, air,
transport) are not available
When RRC setup failure occurs the RNC sends RRC CONNECTION
REJECT message to UE
RRC ACTIVE fails when an interface related (Iu, Iur , Iub, or radio) or
RNC internal failure occurs, and the failure causes the release of the
RRC Connection
When an RRC active failure occurs, the RNC send RANAP IU
RELEASE REQUEST to all involved CNs and waits for RANAP IU
RELEASE COMMAND message(s)
RRC ACTIVE release cause NOT indicating a drop can be either
Normal release
IFHO / ISHO
Relocation
Pre-emption
Call setup – failure of RRC establishmentFailure causes
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C ll t f il
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RRC or RAB setup failure can be due to
• Coverage or interference• Capacity
– AC for radio capacity issues (UL load, DL load, DL spreading codes)
– BTS for channel element (FSM or WSP) capacity issues
– TRANS for Iub capacity issues
• RNC problem – RNC fault – Failure of incoming relocation
Call setup failureFailure overview
C ll t RRC t f il
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Call setup – RRC setup failureFailure cause example
Dominating failure causeduring RRC setup due to
BTS
Check e.g. channel cards
RRC t f il l i
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RRC_CONN_STP_FAIL_AC
• Check UL interference, DL power and code occupancy (M1000)
• UL power spikes → Disable UL admission control if number of failures is critical
RRC_CONN_STP_FAIL_BTS
• Evaluate NBAP counters (radio link setup failures) for troubleshooting BTS resources (M1005)
• Check BTS configuration in terms of WAM and CE allocation – use channel element counters in
order to evaluate lack of channel elements (M5001)
• Expand the capacity or decrease the traffic offered to the site
• In case BTS is not responding delete and re-create COCO
RRC setup failure analysis
RRC set p fail re anal sis
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RRC_CONN_STP_FAIL_TRANS
• Evaluate number of reconfiguration failures due the transmission
• Check COCO configuration
• Use AAL2 Mux in case of two WAM
• Expand the capacity or decrease the traffic offered to the site
RRC_CONN_STP_FAIL_RNTI ALLO FAIL
• RNC decides to reject RRC connection request due to RNTI allocation
failure caused by RRMU overload
RRC_CONN_STP_FAIL_RNC
• Typically RNC fault or incoming SRNC relocation failure• Requires ICSU log tracing if no RNC fault or SRNC relocation problem
RRC setup failure analysis
Call setup RRC setup optimization
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• Network access of UE via Cell_FACH
• RACH and FACH transport channels used for call setup
• Call setup on CCH is faster than on DCH
• All time consuming procedures move to Cell_DCH
• Depending on Ec/Io and CCH load/power status, UE moves to Cell_DCH
RRC Idle RRC Idle
• no UE Location
Information
in UTRAN
• only LAI / RAI
in CN
• no data transfer
possible
• RRC Connectionestablishment via
RACH/FACH
signaling
New
Establish
/ Release
RRC
Connection
Cell_PCH
• UE’s cell known• UE to be paged (DRX functionality PICH)
Cell_FACH• common channel
allocated (FACH,RACH, CPCH, DSCH)
• UE’s cell known
Cell_DCH• DCH allocated
• UE’s cell known
URA_PCH• similar to Cell_PCH
• no Cell Update, but URA Update
Connect ion mode Connect ion mode
With I-phone
not possible
Quicker access
via RACH/FACH
for UE
Common channel setup
Call setup – RRC setup optimization
Call setup RRC setup optimization
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UE BS RNC CN
CM service request
RAB ass. req.
Radio Bearer Setup
Radio Bearer Setup Complete
RAB ass. resp.
RAB SETUP PHASE
RAB ACCESS PHASE
Common channel setup
Call setup – RRC setup optimization
RRC Connection RequestRRC Connection Setup
RRC Connection Setup Compete
Security procedures
RRC SETUP PHASERRC ACCESS PHASE
No RL setup
No CAC
No AAL setup
No RL setup
No CAC
No AAL setup
• Cell_FACH state used for subsequent signaling
• UE enters Cell_FACH e.g. for pure signaling procedure like LA update
• Traffic Volume Measurements performed in Cell_FACH state
• Cell_DCH used once channel type switching selected DCH or HSPA transport channel
Call setup RRC setup optimization
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• Allocation of RACH / FACH or DCH based on establishment cause
received from UE (22 causes)
• Available SRB bit rate on DCH 3.4 kbps or 13.6 kbps configurable
by parameter
• RACH and FACH load continuously monitored in RNC (too highload prevents common channel setup – default = 75% load)
• Air interface quality (CPICH Ec/Io) criteria has impact on common
channel allocation (default Ec/Io ≥ -8 dB required)
Common channel setup
Call setup – RRC setup optimization
Call setup RRC access failure
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L1 Synchronisation
NBAP: Synchronisation Indication
RRC Connection Setup Complete X
UE BTS RNC
XNo L1 synchronization
Failure due to radio
L1 Synchronisation
XUE BTS RNC
No response from UE
Failure due to UE
Cell reselection or directed RRC
setup (no error)
Call setup – RRC access failureFailure definitions
NBAP: Synchronisation Indication
RRC Connection Setup Complete
Call setup – RRC access failure
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Call setup – RRC access failureFailure cause example
Dominating failure cause for RRC access due to radio
But for a few days dominating failure due to RNC
Check e.g. ICSU and DSPs
RRC access failure analysis
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RRC_CONN_ACC_FAIL_RADIO
• Dominant failure cause
• Perform drive test to detect if lack of UL or DL coverage
• UL coverage → tune cell dominance if cause is UL interference
• DL coverage → tune S-CCPCH power if UE does not receive RRC connection setup message
RRC_CONN_ACC_FAIL_MS
• UL coverage → tune cell dominance (CPICH) in order to balance UL and DL (if UL interference not the cause
RRC access failure analysis
Call setup – RRC access optimization
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• Quicker access due to post verification of QoS
• If CPHY-Sync-IND primitive quality sufficiently
good, UE starts 70 ms quicker
• Faults due to radio will decrease, faults due to
UE (post verification) will increase
Node B starts transmitting
Post verificationcheck
40 ms window
UE starts transmittingwith Post Veri f icat ion
UE starts receiving,
mobile is listing on FACH
UE stops transmitting ifverification check fails
10 ms radioframes
UE L1 col lects 40 ms
of qual i ty
measurements
The total delay before UE starts UL
transmiss ion is reduced by 70 ms .
40 ms window
50 ms window
UE starts transmitting
with out Post Veri f icat ion
40 ms window
40 ms window
40 ms window
RRC Connection Access phase
[RRC Connection Setup (FACH)
Fast Layer 1 synchronization
Call setup RRC access optimization
Call setup – successful RAB establishment
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Call setup successful RAB establishmentSignalling and trigger
UE BS RNC CN
CM service request
RAB ass. req.
RL rec. prepare
RL rec. ready
AC
RNC Iub internalresources
AAL2
CACAAL2 sig. ERQ
RAB_STP_ATTEMPTS
Radio Bearer Setup
Radio Bearer Setup Complete
AAL2 sig. ERQ
AAL2 sig. ECF
RAB ass. resp. (success)
RAB_STP_COMPLETE
RAB SETUP PHASE
RAB_ACC_COMPLETE
RAB ACCESS PHASE
Iu CS
RNC internalresources
AAL2
CAC
AAL2 sig. ECF
RAB ass. resp. (failure cause,if resources missing)
Exception: release of the RAB duringSETUP or ACCESSE phase
M1001C66 RAB STP ATT
M1001C115 RAB ACC CPL
RL rec. commit M1001C73 RAB STP CPL
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RAB setup failure analysis
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RAB_STP_FAIL_XXX_AC (not done in case of NRT RAB)
• Check UL interference, DL power and code occupancy
• Evaluate AMR voice and PS 64K code congestion
RAB_STP_FAIL_XXX_BTS
• Evaluate NBAP counters (radio link reconfiguration failures) for troubleshooting BTS resources(M1005)
• Check BTS configuration in terms of WAM and CE allocation – use channel element counters inorder to evaluate lack of channel elements (M5001)
• Expand capacity or decrease traffic offered to the site
• In case BTS is not responding delete and re-create COCO
RAB setup failure analysis
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RAB access failure analysis
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RAB_ACC_FAIL_XXX_MS
• Evaluate cell resources TCP and RTWP (for example high uplink interference)
• Check radio bearer reconfiguration failure ratio
RAB_ACC_FAIL_XXX_RNC
• Typically RNC fault or incoming SRNC relocation failure
• Requires ICSU log tracing if no RNC fault or SRNC relocation problem
y
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Call setup – PS session setup failure
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Failure cause example
Fault analysis completely analog to RRC and RAB
Many PS RAB setup failure causes
due to UE and AC
Performance Monitoring
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KPI analysis hierarchies
Call setup (busy hour, paging, RRC, RAB, PS session)
Call drop (RAB, DCH, radio link)
Mobility (SHO, ISHO, relocation)
HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
Call drop – analysis process
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Top (N) drops
Serving and neighbourcells availabilityAlarms/Tickets
Configuration andparameter audit
SHOSuccess
Rate < 90%?
Conf OK ?
Site OK ?
ISHOFailures
Iurperformance Investigation Iur
Audit adjacent sites for
alarms, availability,configuration and capacity
TrafficNeighbour performance(use SHO success per adjacency
counters to identify badlyperforming neighbours) and map
3G Cell atRNC
border?
NO
YES
New site ?
Analyse last detailedradio measurements
RF and IFHO neighbouroptimisation
No cellfound ratio
>40 %
ISHOSuccess
Rate < 90%
RF and ISHO neighbouroptimisation
3G cellcovers over acoverage hole
?
3G cell atinter-RNCborder ?
Wrong reference clock(10MHz tuning)
No cell foundratio > 90 %and enough
ADJG
2G Cell Doctor
2G InvestigationTCH blocking or
TCH seizure failure(interference)
NO
YES
YES
YES
NO
YES
NO
YES
YES
SHO
ISHO
Flow chart for RAB
Call drop analysis
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Failure cause example for voice
Many CS RAB drop causes due
to radio and transmission
Call drop analysis
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Failure cause example for PS
Many PS RAB drop causes
due to UE and radio
Call drop analysis
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1. Check high call drop cells and its neighbouring cells for any fault alarms
2. Generate call drop root cause distribution and check for main contributors (radio, BTS,Iub, Iur, RNC, Iu, MS)
3. Check SHO if success rate < 90% (leads to radio link failure) – Check if cells are at RNC border (check Iur capacity and SRNC relocation problem)
– Detect badly performing neighbours using SHO success rate per adjacency counters (M1013)
– High incoming HO failure rate from all adjacencies – check sync alarms
– Assess neighbor list plan and do visualization check with map
– Evaluate HO control parameters and trigger thresholds
4. Check ISHO KPI if RT ISHO < 90% or NRT < 80% (leads to radio failure)
Check missing neighbours (M1015)
Check GSM frequency plan, RNC and MSC database consistency
Check alarm of reference clock in 3G or in 2G
Check 2G TCH congestion
Check RRC drop during ISHO RT / NRT
Call drop analysis
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5. Look for DL or UL path loss problem if RAB drop due to radio dominates
Check UE lost counters (active L1 synchronization failure) to check UL/DL path loss problem
Check active set update failure rate (with cause no response from UE)
Map radio failures with RL power and CPICH related parameters (CPICHToRefRABOffset, PTxDPCHMax)
Check call reestablishment timer (T315)
Check Ec/Io distribution for bad coverage issue (M1007)
6. Check core network parameter setting if RAB drop due to Iu
Check SCCP signaling (MSC / SGSN, RNC, IuCS / IuPS)
7. If high RAB drop due to BTS
Check for any BTS faulty alarm (e.g. 7653 cell faulty alarm)
If no alarms, COCO detach/attach
8. If high RAB drop due to MS
Check physical channel reconfiguration failure rate (IFHO, ISHO, code optimization)
Call drop analysisE l f t f i di id l d d ll
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Example for trace of individual dropped call
UE does not find SHO neighbor
Event 1F due to RSCP
UE enters compressed mode
But does not find GSM neighboreither
RT and NRT
Soft drop - DCH
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• RT
• If communication between UE and network interrupted, this will
trigger RAB drop
• NRT
• Interrupted communication between UE and network will not trigger
immediately RAB drop
• Network tries to shift UE to Cell_FACH state, i.e. tries to keep RAB
running
RT and NRT
Failure cause example
Soft drop - DCH
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Failure cause example
Two drop cause counters only
Radio
Other
Majority of DCH drops still
due to radio
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Soft drop - radio link failureFailure example – RL deletion by SRNC and DRNC
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Failure example – RL deletion by SRNC and DRNC
> 50 % abnormal deletions
< 20 % abnormal deletions Each point represents one cell
Black = RL deletion by SRNC
Red = RL deletion by DRNC
High number of
abnormal radio link
deletions by DRNC
KPI analysis hierarchies
Performance Monitoring
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KPI analysis hierarchies
Call setup (busy hour, paging, RRC, RAB, PS session)
Call drop (RAB, DCH, radio link)
Mobility (SHO, ISHO, relocation)
HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
SHO – successful softer HOSignalling and trigger
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Signalling and trigger
UE BS RNC
Measurement report 1A or 1C
RL addition request
RL addition response
AC
BTS resources needed
But no Iub resources(no CAC)
Active set update
Active set update complete
SETUP PHASE
ACCESS PHASE
If problem, check radio linkaddition failure causes (M1005)
If problem, check air interface
performance
SHO – successful soft HOSignalling and trigger
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Signalling and trigger
UE BS RNC
Measurement report 1A or 1C
RL setup request
RL setup response
AC
Active set update
Active set update complete
SETUP PHASE
ACCESS PHASE
AAL2 sig. ERQ
AAL2 sig. ECF
BTS resources needed
And Iub resourcesneeded (CAC)
If problem, check radio linksetup failure causes (M1005)
If problem, check air interface
performance
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SHO – OverheadConcept and counters
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Call setup in cell A.
Cell A Cell B
Cell A Cell BCell A Cell B
Cell A Cell BCell A Cell B
After 40sec Event 1A (addition): Active Set has changed.
(CellA) ONE_CELL_IN_ACTIVE_SET incremented + 40sec
After 60sec Event 1B (deletion): Active Set has changed.
(Cell A) TWO_CELL_IN_ACTIVE_SET incremented +60sec
(Cell B) TWO_CELL_IN_ACTIVE_SET incremented +60sec
Cell A Cell BCell A Cell B
After 20sec Call release.
(Cell B) ONE_CELL_IN_ACTIVE_SET incremented + 20sec
p
SHO – OverheadCell level
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cell A
cell B
NRT RT SET ACT IN CELLTHREE
NRT RT SET ACT IN CELLTWO
NRT RT SET ACT IN CELLONE
NRT RT SET ACT IN CELLTHREE
NRT RT SET ACT IN CELLTWO
NRT RT FORSET ACT IN CELLONE
/ _ _ _ _ _
/ _ _ _ _ _
/ _ _ _ _ _
3/ _ _ _ _ _
2/ _ _ _ _ _
/ _ _ _ _ _ _
Factors 1/2/3
= number of
radio links
Total time during which all calls are
running with different AS size
E1A CPICH E1B CPICH
Offset 4dB Offset 6dB
SHO
area
KPI shall give average
number of radio linksduring a call
Total time of
all calls
SHO – OverheadCell level
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Example: RNC area with 3 cells A, B and C
Cell A: 20 s active alone, 10 s with B, 10 s with C, 5 s with B + C
(20 s alone, 20 s with 2 cells, 5 s with 3 cells)
Cell B: 30 s active alone, 10 s with A, 5 s with C, 5 s with A + C
(30 s alone, 15 s with 2 cells, 5 s with 3 cells)
Cell C: 25 s active alone. 10 s with A, 5 s with B, 5 s with A + B
(25 s alone, 15 s with 2 cells, 5 s with 3 cells)
Cell level results
Cell A: Average AS size = (20x1 + 20x2 + 5x3) / (20 + 20 + 5) = 1.67 (67% overhead)
Cell B: Average AS size = (30x1 + 15x2 + 5x3) / (30 + 15 + 5) = 1.50 (50% overhead)
Cell C: Average AS size = (25x1 + 15x2 + 5x3) / (25 + 15 + 5) = 1.56 (56% overhead)
Too big SHO overhead indicated
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SHO – OverheadRNC level
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cell A
cell B
3// _ _ _ _ _
2// _ _ _ _ _
/ _ _ _ _ _
/ _ _ _ _ _
/ _ _ _ _ _
/ _ _ _ _ _ _
NRT RT SET ACT IN CELLTHREE
NRT RT SET ACT IN CELLTWO
NRT RT SET ACT IN CELLONE
NRT RT SET ACT IN CELLTHREE
NRT RT SET ACT IN CELLTWO
NRT RT FORSET ACT IN CELLONE
KPI compares effectivenumber of calls with
number of radio links
Call belongs
to cell A only
Call belongs half tocell A and half to cell B
Denominators 1/2/3:
Call with 1 radio linkBelongs completely to its single
active cell
Cell with 2 radio links
Half the call belongs to each
active cell
Cell with 3 radio links
One third of the call belongs toeach active cell
SHO – OverheadRNC level
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Example: RNC area with 3 cells A, B and C
Cell A: 20 s active alone, 10 s with B, 10 s with C, 5 s with B + C
Cell B: 30 s active alone, 10 s with A, 5 s with C, 5 s with A + C
Cell C: 25 s active alone. 10 s with A, 5 s with B, 5 s with A + B
RNC level results
Cell A, B and C altogether
75 s active alone
50 s with second cell
15 s with third cell
Average AS size = (75 + 50 + 15) / (75/1 + 50/2 + 15/3) = 1.33 (33% overhead)
RNC level KPI gives about half the overhead only than the cell level KPI!!
Realistic SHO overhead indicated
SHO – OverheadRNC level example
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Typical target for SHO overhead 40%
SHO per adjacencyConcept and counters
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• SHO attempts per adjacency
• No attempts to distant cell → might be removed from neighbor list
• No attempts to nearby cell → check whether SC of ADJS is declared correctly
in RNC data base
• No attempts to inter-RNC cell → check whether RNC data bases are consistent
with each other (e.g. SC declarations)
• Very few attempts to nearby cell → check user distribution and propagationconditions
• Very few attempts in general → check addition window setting
• Too many attempts to specific neighbor → check user distribution and pilot
pollution
• Too many attempts in general → check addition window setting
SHO per adjacencyConcept and counters
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HO_ATTTRA_FREQ_SSHO_ADJ_IN
HO_COMPLTRA_FREQ_SSHO_ADJ_IN _RNCs_per_ADJSSHO_succes
• SHO success per adjacency
• High failure rate (several 10%) → besides RL setup / addition failures and air
interface performance check for SC clash
• 100% failure rate to intra-RNC cell → check for HW faults
• 100% failure rate to inter-RNC cell → check for inconsistency between RNC and
core network data base (e.g. CI, LAC and RAC declarations)
• Attempt and success per adjacency monitored by AutoDef SHO
counters (M1013)
ISHO – successful procedureSignalling and trigger
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UE
RRC: Measurement Report (Event 1F)
RRC: Physical Channel Reconfiguration
RRC: Physical Channel Reconfiguration Complete
BTS RNC
UE put intocompressed mode
RRC: Measurement Control
RRC: Measurement Report
RxLevmeasurements
RRC: Measurement Control
RRC: Measurement Report
BSIC verification
MSC
RANAP Relocation required
RANAP Relocation command
RRC: HO from UTRAN Command
ISHOexecution
NBAP: RL reconfig. prepare
NBAP: RL reconfig. ready
NBAP: RL reconfig. commit
NBAP: CM command
NBAP: CM command
RANAP Iu release request
ISHO – analysisFlow chart
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Top N cells
Too low success
rateNo action
needed
No
Missing ADJG or
Bad Neighbor
planning ?
Wrong 2G Ncell
Parameter (BSIC)
Or BSIC collision
No
Yes
Yes
No
Too low ISHO triggering
threshold or
Too strict ADJG
minimum threshold
Non-optimum
Compressed mode
parameter set
Low ISHO
Success ?
Low ISHO
Measurement
success ?
Missing or wrong 2G
parameter in 2G MSC
or SGSN (BCCH, LAC,
CellID)
2G Ncell
CongestionHalf Rate in 2G
Ncell ?
Poor GSM
Coverage
CM Start
Not
Possible?
Yes
Check admission
control rejection
TCP and RTWP
Yes
No
ISHO – analysisISHO cause example
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Blue = RSCP triggered
Red = Ec/Io triggered
Black = DL RL power triggered
UE power triggered = 0
UL SIR target triggered = 0
HHO mostly triggered by
event 1F
Event 1F again mostly due to
low coverage, but not quality
ISHO – analysisISHO cause example – RSCP under 1F conditions
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Usually very low coverageunder event 1F conditions
Consistent with counterstatistics
ISHO – analysisISHO cause example – Ec/Io under 1F conditions
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Usually acceptable Ec/Io evenunder event 1F conditions
Consistent with counterstatistics
ISHO - analysisISHO failure example – no target cell found
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100% target cell found
Each point represents one cell
80% target cell found
ISHO - analysisISHO failure example – no target cell found
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In several source cells oftenfailure to find target cell
ISHO - analysisISHO failure example – target cell not accessed
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Much less critical to accesstarget cell
ISHO per adjacencyConcept and counters
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_ATTER_SYS_HHOHO_ADJ_INT
_COMPLER_SYS_HHOHO_ADJ_INTG_RNCss_per_ADJISHO_succe
• ISHO attempts per adjacency
• No attempts to distant cell → might be removed from neighbor list
• No attempts to nearby cell → check whether BCCH frequency and BSIC is
declared correctly in RNC data base
• ISHO success per adjacency
• High failure rate (several 10%) → besides air interface performance check for
BCCH-BSIC clash
• 100% failure rate → check for inconsistency between RNC, BSC and corenetwork data bases (e.g. CI, LAC and RAC declarations)
• Attempt and success per adjacency monitored by AutoDef SHO
counters (M1015)
3GPP options to
Inter-RNC mobilityRelocation and anchoring
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CN
RNCRNC
Iu Iu
Iur
CN
RNCRNC
Iu Iu
Iur
CN
D-RNCS-RNC
Iu Iu
Iur
CN
RNCRNC
Iu Iu
Iur
SRNS relocation SRNC anchoring
SRNC Anchoring not as suchstandardised mobility method
Can lead to limited mobility at the borderbetween RNCs of different vendors
But can be implemented by applyingundefined set of standardised features
SRNS Relocation standardisedmobility method
3GPP options touse MM
Anchoring supported inNokia SRNC only for CS RTand PS NRT services within
Cell_DCH
Keep Iur resourcesuntil release of the
call
Release Iur resourcesafter drop of lastsource RNC cell
R l ti d d f il d t t d diff tl b t
Inter-RNC mobilityIncoming and outgoing relocation
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• Relocation procedure and failure detected differently betweensource and target RNC
• Target RNC – Target RNC sees relocation as incoming RRC connection setup with cause SRNC
relocation
– Setup, access and active counters incremented both for RRC and RAB
– In case of failures, corresponding setup and access failure counters are incrementedboth for RRC and RAB (failure due to RNC)
• Source RNC
– Source RNC starts relocation procedure and releases finally RRC connection withcause SRNC relocation
– Active release counters incremented both for RRC and RAB
– In case of failures, corresponding active failure counters are incremented both forRRC and RAB (drop due to RNC)
Signalling and trigger
Inter-RNC mobility – successful relocation
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RNCSource
RANAP Relocation required
Core RNCTarget
RRC UTRAN mobility info
UE
RNSAP Relocation commit
RANAP Relocation request
RANAP Relocation request ACK
SETUP PHASE
RRC setup attempt
RRC setup failure due to RNC
ACCESS PHASE
RRC setup complete
RRC access failure due toradio or RNC
RANAP Relocation command
RANAP Relocation detect
RRC UTRAN mobility info confirm
RANAP Relocation complete
RANAP Iu release
RANAP Iu release complete
ACTIVE PHASERRC release due to relocation
• Target RNC does not respond to RANAP relocation request orRNSAP relocation commit (internal RNC or Iu problem)
Inter-RNC mobility – possible failures
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RNSAP relocation commit (internal RNC or Iu problem)
• Target RNC responds with RANAP relocation request NACK (noresource available in target RAN)
• Synchronization failure on Iur (transmission problem)
• UE does not respond to RRC UTRAN mobility info (air interface orUE problem)
• Synchronization failure on radio link (air interface problem)
KPI analysis hierarchies
Call setup (busy hour paging RRC RAB PS session)
Performance Monitoring
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Call setup (busy hour, paging, RRC, RAB, PS session)
Call drop (RAB, DCH, radio link)
Mobility (SHO, ISHO, relocation)
HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
HSDPA setup – successful session establishmentSignalling and trigger
UE BS RNC
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Capacity request
RL rec. prepare
RL rec. ready
AAL2 sig. ERQ
Radio Bearer Reconfig.
Radio Bearer Reconfig. Complete
AAL2 sig. ECF
RL rec. commit
session SETUP PHASE
session ACCESS PHASE
AAL2 sig. ERQ
AAL2 sig. ECF
HS-DSCH capacity request
HS-DSCH capacity allocation
After RRC establishment two furtherAAL links are needed for HSDPA
HSDPA setup – analysis processFlow chart
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Top N cellsSetup Fail
BTS
High setup
failure rate
Setup Fail UL
return
Channel
Setup Fail Iub
TransportSetup Fail UE
Setup Fail
RNC internal
Setup Fail Too
Many Users
No action
needed
Check CE
resource usage
at BH
UL powercongestion
?
Check AAL2
Iub resource
congestion
Check RB
reconfiguration
Failure rate
Check RNC
Unit load(DMPG) and
faulty alarms
Check number of
simultaneousHSDPA users
No
Yes
Yes Yes Yes Yes Yes Yes
No No NoNo
No
Lack of CE mainly problem for UL return DCH
For HSDPA CE reserved per scheduler
For associated DCH on DL just 1 CE per user
No
Failure cause example
HSDPA setup – analysis process
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Many HSDPA setup failure causes
due to UE, Iub and UE
1. Identify main failure contributor
2 If too many HSDPA users
HSDPA setup – analysis process
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2. If too many HSDPA users
• Use licence for more users
• Use dedicated instead of shared scheduler
3. If due to UL DCH
• Monitor UL load
• Check PrxTarget and PrxNoise settings
• Check for intermodulation
4. If due to UE• Check RB reconfiguration failure rate
• Check air interface performance
• Check ICSU log for UE type troubleshooting
5. If due to BTS
Lack of UL channel resources
HSDPA setup – analysis process
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Lack of UL channel resources
Check for SHO overhead (all branches must have enough CE capacity if UE is in SHO when HS-DSCH shallbe allocated)
6. If due to Iub transport
Evaluate number of reconfiguration failure due the transmission
Check for SHO overhead (all inter-BTS branches must have enough capacity for associated DCH)
Check for number of individual AAL connections
Check for frame delay or even frame loss due to congestion
With RU20 HSPA transport channels can be allocated directly to users in
Direct resource allocation
HSDPA setup – optimization
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Cell_FACH or Cell_DCH, without waiting for capacity request
• UE must support HSDPA and HSUPA transport channels
• HSDPA and HSUPA must be enabled in cell
• Direct resource allocation always used when F-DPCH allocated to UE
Prior to RU20 for NRT user allocation of DCH 0/0 by AC
• After receiving capacity request, RNC selects channel type
• If no capacity request received by RNC, UE moved to Cell FACH
KPI analysis hierarchies
Call setup (busy hour, paging, RRC, RAB, PS session)
Performance Monitoring
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Call drop (RAB, DCH, radio link)
Mobility (SHO, ISHO, relocation)HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
HSDPA drop – analysis processFlow chart
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Top N cells
Pre-emption
High drop
ratio
Transition to
DCH due to
mobility
Transition to DCH
due to other
reason (e.g. type
of RAB)
Drop due to
radio
No action
needed
Normal Release(No action
needed)
Normal Release(No action
needed)
Normal Release(No action
needed)
High SCC Failure
Rate
No
Yes
Yes Yes Yes Yes
No NoNo
Check CQI distribution
and Ec/Io distribution for
coverage issue
Check HSDPA mobility
settings (SHO and SCC
parameter)
No
Drop due to
other reason
No
Check RB reconfiguration failure
rate (UE response with failure or
no response at all)
Check ICSU log (UE type)
Yes
Yes
HSDPA drop = soft drop
RNC tries to shift UE to Cell_FACH
RNC tries to keep RAB running
Failure cause example
HSDPA drop – analysis process
Majority of DCH drops due
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to radio
KPI analysis hierarchies
Call setup (busy hour, paging, RRC, RAB, PS session)
Performance Monitoring
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Call drop (RAB, DCH, radio link)
Mobility (SHO, ISHO, relocation)HSPA setup
HSPA drop
HSPA mobility (SCC, HSUPA SHO)
UE BTSS
BTST t
RNC
Serving Cell Change SCC – successful procedureSignalling and trigger for inter BTS SCC
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RRC: Measurement Report (e.g. Ec/Io)
NBAP: Radio Link Reconfiguration Prepare
Source Target
RRC: Radio Bearer Reconfiguration
RRC: Radio Bearer Reconfiguration Complete
NBAP: Radio Link Reconfiguration Ready
NBAP: Radio Link Reconfiguration Prepare
NBAP: Radio Link Reconfiguration Ready
ALCAP: Establish Request
ALCAP: Establish Confirm
NBAP: Radio Link Reconfiguration Commit
NBAP: Radio Link Reconfiguration Commit
UE BTSS
RNC
SCC – successful procedureSignalling and trigger for intra-BTS SCC
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RRC: Measurement Report (e.g. Ec/Io)
NBAP: Radio Link Reconfiguration Prepare
Source
RRC: Radio Bearer Reconfiguration
RRC: Radio Bearer Reconfiguration Complete
NBAP: Radio Link Reconfiguration Ready
ALCAP: Establish Request
ALCAP: Establish Confirm
NBAP: Radio Link Reconfiguration Commit
Setup of transport resourcesonly needed in case of inter-
WAM mobility
SCC – window settingsSCC with associated DCH
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Addition
window
4dB
CPICH 1 R99
CPICH 2 R5/6
EC /I0
timeSHO for A-
DCH initiated
Periodic
reports
Serving cell change
initiated
periodic reports as
long UE in SHO area
HSDPAServCell Window
RNC, 0..6, 0.5, 2 dB
Addition Time
Drop
window
6dB
CPICH 2 activeCPICH 1 no t
act ive anym ore
HSDPAS C llWi d
SCC – window settingsSCC with F-DPCH
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Addition
window
CPICH 1
CPICH 2
EC /I0
timeJust periodic
reports
Serving cell change AND
active set update initiated
periodic reports aslong UE in SHO areaAddition Time
HSDPASRBWindow
RNC, 0..6, 0.5, 1 dB
HSDPAServCell Window RNC, 0..6, 0.5, 2 dB
CPICH 2 NOT
act ive yet
CPICH 2 active
together with SCC
Modified (smaller) SCC
window used, as no SHOwith event 1A yet
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SCC – analysis processFailure cause example
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HSPA started
Many serving cell change failure
causes due to AC
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5. If high SCC failure rate due to UE
• Check RB reconfiguration failure rate
Ch k i i t f f
SCC – analysis process
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• Check air interface performance
• Check ICSU log for UE type monitoring6. If high SCC failure rate due to transport
• Evaluate number of reconfiguration failure due the transmission
• Check for number of individual AAL connections
• Check for frame delay or even frame loss due to congestion
7. If high SCC failure due to other reason• Check RNC internal transport resources usage (DMPG)
• Requires ICSU troubleshooting
RU20 (standard feature)
• In SHO area HS UE sends periodic measurement reports to RNC
• RNC evaluates reports to decide about serving cell change
SCC – RU30 Enhancements
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• Problems
• High signaling traffic due to periodic reporting• If F-DPCH used, serving cell change command of RNC might not be decoded by UE, as SRB on
HS-PDSCH less robust than on DPDCH
RU30 (enhanced feature)
• No periodic reporting in SHO area any more, but serving cell change triggered by event1D
• Better robustness for SRB on HS-PDSCH
• RNC sends pre-information about potential target cells during active set update already
• Serving cell change commands transmitted both in source and target cell
Pre-configuration
• Serving cell change command transmitted both in source and target cell
• In source cell via HS-PDSCH
SCC – RU30 Enhancements
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• In target cell via HS-SCCH
• UE informed during active set update about• Codes used for HS-SCCH in target cell
• Activation time offset (time to monitor target cell after sending event 1D report)
UE Source Node B Target Node B SRNC
RRC: Measurement Report (event 1a or 1c)
RRC: Active Set Update Complete
RRC: Active Set Update (Pre-configuration Info)
NBAP: Radio Link Setup (Pre-configuration Info)
RRC: Measurement Control
Execution
• Serving cell change initiated by UE with event 1D report (then UE starts to monitor targetcell)
Aft b th d t t ll d f i ll h t th UE t
SCC – RU30 Enhancements
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• After both source and target cell are prepared for serving cell change, to the UE are sent
• RRC radio bearer configuration from RNC as usual (via HS-PDSCH in source cell)
• HS-SCCH order from target Node B (via HS-SCCH in target cell)
• If UE detects HS-SCCH order only, it still goes to target cell
• The UE informs the RNC about the completion of the process with RRC radio bearerreconfiguration complete
UE Source Node B Target Node B SRNC
SCC Evaluation
RRC: Measurement Report (event 1d CFN)
SCC – RU30 Enhancements
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RRC: Measurement Report (event 1d, CFN)
SCC Decision
NBAP: Radio Link Reconfiguration Preparation
NBAP: Radio Link Reconfiguration Preparation
NBAP: Radio Link Reconfiguration Commit
NBAP: Radio Link Reconfiguration Commit
L1: HS-SCCH Order
RRC: Radio Bearer Reconfiguration
UE moves to Target Cell
RRC: Radio Bearer Reconfiguration Complete
RNC re-directs application data
Event 1D
• UE uses event 1D to inform RNC that there has been a change of the best cell in the activeset
• Event 1D triggered if following equation satisfied during time interval defined by time to
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• Event 1D triggered if following equation satisfied during time interval defined by time-to-trigger
MeasNotBest + CIONotBest ≥ MeasBest + CIOBest + Hyst / 2
• If equation simultaneously fulfilled for more than one primary CPICH, UE reports only oneevent 1D, triggered by best primary CPICH
CPICH 1
CPICH 2
Measured EC /I0
timeEvent 1Dreport
Hyst / 2
Serving cellchange executed
Time to tr igger Cell indiv idualoffset CIO
Event 2D and 2F
• Usually events 1F and 1E to initiate and cancel HHO process due to lack of RSCP or EC /I0
• With SHO events and events 1F and 1E already maximum number of intra-frequency eventsallowed by 3GPP achieved, so that event 1D cannot be offered any more
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allowed by 3GPP achieved, so that event 1D cannot be offered any more
• Events 1F and 1E therefore replaced by events 2D and 2F
• Events 2D and 2F triggered by intra-frequency measurements, but nevertheless classifiedas inter-frequency events
• Event 2d: Estimated Quality of the current RF carrier is below a Threshold
• Event 2f: Estimated Quality of the current RF carrier is above a Threshold
Measured EC /I0
time
Event 2D
ALL active cells bad
Enter compressed mode
2F thresho ld
2D threshold
Event 2F
One active cell acceptable again
Leave compressed mode
SCC – User data over IurPrevious releases up to RU10
• Inter-RNC HS-DSCH serving cell change and relocation at the same time
• No flow of user data over Iur
• Switch back to DCH not required but nevertheless interruption of HSDPA service by the
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RNC
RNC
A
B
C
AS={A,B,C}
Normal SHOfor A-DCH
AS={A,B,C}
C= best cell,HS-DSCH dataover Iur
AS={C}
Triggerrelocation
Switch back to DCH not required, but nevertheless interruption of HSDPA service by themobility procedures
Since RU20
• First inter-RNC serving cell change, then relocation
• Flow of user data over Iur, when inter-RNC neighbour becomes new serving cell
• HSDPA service not interrupted by the mobility procedures
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