Download - Informacion 3G
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1 © Nokia Siemens Networks Presentation / Author / Date
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Telefónica Perú
Capacity Management 3G Network
2 © Nokia Siemens Networks Presentation / Author / Date
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Outline
• Introduction
• Capacity Areas in UTRAN1. Air Interface
2. WBTS HW Resourses
3. RNC
4. Transport IuB
• Iu Monitoring• Iu-CS
• Iu-PS
• Iu-R
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Introduction
WCDMA network interfaces and internal resources should be monitored
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Introduction
• The various measurement were used to identify the capacity issues and their negative impact on accessibility (CSSR) of the various RABs:
1. CS speech (AMR)
2. PS data (R99)
3. HSPA data
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Capacity Areas in UTRAN
• Essential to monitor the available resources in UTRAN
– Capacity from initial dimensioning phase may no be sufficient in some cases
– Marketing campaigns lead to higher resource utilization
• Capacity bottlenecks impact the call setup success rates (CSSR)
– Mobile user perceives poor setup success rates directly
• With these measurements, network capacity can be monitored in a proactive mode
– Capacity upgrades can be triggered taking into account existing lead times HW units, internal procedures like planning or implementation
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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
Capacity Areas in UTRAN
RLC/MAC
During call set-up [RRC, RAB] several resource areas are checked and
physical / logical resources allocated.
DSP processing
RNC
1 – Radio resources
1a – Code resources
2 – WBTS resources (Channel Elements)
3 – DMCU
allocation
4 – Iub resources(transmission)
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Call Setup Success Rate - CSSR
CSSR for a specific service is calculated the following way:
For RAB setup & access phase we can distinguish various failure causes:
CSSR any service = RRC connection setup & access X RAB setup & access any service
RRC part RAB part
SETUP PHASE:
• due to AC
• due to BTS
• due to Transport
• due to RNC
• due to Frozen BTS
• due to AAL2 iuB, License, AAL2 IuCS, anchoring, UE
capabilities, not supp. params
ACCESS PHASE:
• due to UE
• due to RNC
Failures due to UE
• are not related to capacity issues in the
network
• related to UE problems
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Decision criteria
Accesibility < 99%
Cell OK
No
Yes
Additional KPI check & optimization (if necessary)
• AMR accessibility
• PS R99 accessibility
• HSPA accessibility
Radio
resourcesChannel
elements
Transport
resources
RNC internal
resources
Lack of
Radio Resoures
Lack of
Channel Elements
Lack of
Iub resourcesLack of
RNC resources
Failures due to
AC >1%
Failures due to
BTS >1%
Failures due to
TRANS >1%
Failures due to
RNC >1%
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RAB setup failures1. Admission Control (AC) failures – RADIO
• Indicates lack of radio resources:– DL power
▪ Measurement of PtxTotal, transmission power of NonHSDPA, HSDPA etc.
– UL interference
▪ Measurement of RSSI
▪ Measurement of PrxTotal and PrxNoise
– DL channelization codes:
▪ Channelization code occupancy (min, max, avg)
▪ Channelization code blocking rate
▪ HSDPA code usage
▪ HSDPA code downgrades
– Rejection rate in downlink and uplink (SRB, AMR, CS data, PS data) due to congestion
– Common channel load (RACH, FACH, PCH) – typically not a problem
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RAB setup failures1. Admission Control (AC) failures – RADIO
Posible to
reduce the
code usage?
Upgrade
BTS power
High UL
interference/loadPosible to reduce
R99 usage?
High non-
HSPA load
High non-
HSPA load
Posible to
optimize
throughput?
Upgrade
to 2nd carrier
‘
DL power
Marginal Load Time Share DL > 50%
Overload Time Share DL> 2%
Average DL R99 Load > PtxTarget
Marginal Load Time Share UL > 50%
Overload Time Share UL> 2%
Average UL R99 Load > PrxTarget
Noise floor of the System
>-90dBm
High DL load
Failures due to
AC >1%
R99 power >> HSDPA power
No
Yes
Yes
No
UL interference
Spread. Code Blocking Rate in DL
>5%;
SFxx Blocking Rate high
Max_Code Occupancy >95%;
Avg_Code Occupancy >80%
Channelization
codes
High chan. Code
utilization
No
• AMR accessibility
• PS R99 accessibility
Yes
External
Interference
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RAB setup failures1a. HSDPA accessibility
• Indicates problems for access of HS-DSCH (HSDPA access failure rate):
1. Due to UL DCH
• Problems of return UL return channel
• Related to R99 radio resources
2. Due to TOO MANY HSDPA USERS
• Licence limit – 48 users HSDPA license upgrade to 64 users
• R99 is selected, which can cause capacity problem in use of radio resources Check radio resources for R99
• If licence upgrade is not sufficient, the Dedicated HSDPA scheduler is an option
3. Due to BTS (channel elements)
4. Due to Iub (transmission)
5. Due to RNC
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RAB setup failures1a. HSDPA accesibility
HSDPA
accessibilit
y < 99%
Go to
RADIO
Resoures
Go to
BTS failures
Go to
RNC failures
Go to
TRANSPORT
failures
1. HSDPA 64 users
License upgrade
Problem in
R99 ?
2. HSDPA Dedicated
Scheduler upgrade
HSDPA Access FR
due to UL DCH
HSDPA Access
FR due to RNC
HSDPA Access
FR due to BTS
HSDPA Access
FR due to Iub
OR LATER
Radio related issues
Others
DCH Selected
due to too many
HSDPA users
> 0.5%
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RAB setup failures2. BTS failures
• Indicates lack of WBTS baseband resources = channel elements (CE):
– Measurement of available CEs (min, max, avg)
– Measurement of usage of CEs:
▪ In UL, DL (min, max, avg)
▪ Per service
WBTS HW upgrade
(system module)
CE usage
can be
reduced?
No
Yes
Fast Failures due to
BTS >1%
AVG_CE_USAGE > 80%
MAX_CE_USAGE >95%
High CE utilization
CE utilization
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RAB setup failures3. RNC failures
• Indicates lack of RNC internal resources
– DSP Service Statistics Measurement
– DSP Resource Utilisation Measurements
– DSP State Change Measurements
– DSP Load Measurements
– Iub, IuCS, IuPS throughput measurement at RNC
RNC HW upgrade
Fast
RNC Interface
capacity upgrade
Failures due to
RNC >1%
High DSP load
RNC_Unit Load:
AVG_Load >80%
MAX_Load >95%
DSP load
RNC_Traffic Load:
Iub Traffic Load
IuCS Traffic Load
IuPS Traffic Load
High Iu Traffic
Traffic load
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RAB setup failures4. Transport failures
• Indicates lack of transport resources
– Traffic load measurements
▪ Average VCC Ingress/Egress utilisation
▪ Average VPC Ingress/Egress utilisation
– CAC reservations
▪ Allocated Average Capacity of CBR VCC
▪ Allocated Capacity per ATM VCC (cps)
▪ AAL2 connection reservation success rate
– Number of AAL2 Connections
▪ Average AAL2 connection utilisation
▪ Max_AAL2_connections (248 max)
▪ Max_AAL2_connections_HSPDA
– Shared HSDPA AAL2 allocation utilisation Iub upgrade
Posible to
reduce Iub
utilization?
Yes
No
Yes
Fast Failures due to
TRANS/AAL2 Iub >1%
AVG_UP_CAC Reservation > 80%
Peak_UP_CAC Reservation >90%
High Iub load
Iub Reservations
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Additional tasks
• Even if all the capacity issues would be resolved, the 100% accessibility can not be expected
• RF optimization (e.g. overshooting cells)
– Propagation delay measurements
– CQI measurements
– RSCP, Ec/Io measurements
• Mobility optimization
– Soft handover
– Inter-system handover
• Failures due to UEs can not be avoid
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Iu Monitoring
• The scope of this presentation is RNC interfaces monitoring using measurements in the RNC and in the BTS
Iu-CS
Iu-PS
Iur
RNC BTS
RNC
MGW
SGSN
Iub
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Content
1. ATM load measurements
2. AAL2 CAC measurements
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ATM Load Measurements - Overview
ATM Load Measurements in RNC
• Virtual Path Connection (VPC)
• Virtual Circuit Connection (VCC)
• ATM interfaceA
TM
inte
rface
Virtual path
Virtual path
Virtual channel
AAL2
connection
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ATM VPC and VCC Measurements
• ATM VPC/VCC measurements count cells per VPC/VCC during measurement period
• Up to 1024 VPCs and all VCCs (RU10 onwards) can be measured per RNC at the same time
• Enables calculating average throughput over the measurement period
Configured capacity
Measurement period
Cells/period
Actual traffic
Measured average traffic
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ATM VPC and VCC Measurements
• Iu-CS, Iu-PS and Iur can be measured as well
• Use of ingress and egress counters
– Iub in downlink direction is measured using egress counters
– Iu-PS in downlink direction is measured using ingress counters
Iu-CS
Iu-PS
Iur
RNC BTS
RNC
MGW
SGSN
Iub
Egress
directionIngress
direction
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ATM Interface Measurement
• ATM interface utilization and traffic per service category CBR, UBR and UBR+
• The ATM interface level measurement is relevant if you have unshaped VPCs with UBR+ VCCs inside and the sum of VCC PCRs exceeds the interface capacity
– Otherwise the ATM CAC and/or VCC/VPC configuration will prevent overload possibility
• Potentially useful for Iu if IuPS and IuCS are on their own NIS cards.
AT
M inte
rface
Virtual path
Virtual path
Virtual channel
AAL2
connection
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Content
1. ATM load measurements
2. AAL2 CAC measurements
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RNC AAL2 Connection Admission Control
• Bandwidth requirement is affected by
– ALC parameters, ALC set (for DCCH), Activity factors
– Delay requirement, loss tolerance
– Done for common channels, SRB, RT DCH, NRT DCH, Streaming HSDPA and SharedHSDPAAllocation
– VCC bundle is a special case
ATM
VCC
PCRAAL2 reservation
for existing
connections
New
connection
requiring
this much
capacity
would be
blocked
New
connection
up to this
capacity
would fit in
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Summary
RAN capacity monitoring processes are focused on the following interfaces and network elements:
• Radio Interface capacity – WBTS power, code tree
• Iub capacity – Transmission capacity
• Node B capacity –WBTS Base band processing capacity
• RNC processing capacity
• Iu-CS, Iu-PS and Iur traffic
RNC Capacity
-RNC traffic load
-Unit load
-Setup failure due to RNC
Proactive Monitoring
Reactive Monitoring
-BTS power DL/UL
-Channelisation code utilisation
-S-CCPCH & PRACH load
-Setup failure due to AC
-Service rejection ratio
-Code blocking
-RB downgrade/release
Monitoring / Interface Air Interface Iub Interface HW Channel Element
-Setup failure due to
transmission
-Resource reservation success
rate
-Iub traffic load
-Resource reservation -CE utilisation
-Setup failure due to BTS
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26 © Nokia Siemens Networks Presentation / Author / Date
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Thank You!