Advance Network Optimization Solution Findings NPO Refresher Course July, 1st to 3rd 2010 Vodafone MS – RoB
Jignesh Parmar
[email protected] Nokia Siemens Networks National NPO, Ahmedabad, India NSN Internal Document 1 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance Optimization - Introduction Typical performance problems which have to be improved Indoor coverage problems
CS / PS Capacity problems Downlink coverage problems Downlink interference problems Uplink Signaling (access) problems
NSN Internal Document 2 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance optimization - basic CS/PS flows Paging Optimization
SDCCH Optimization
TCH Optimization
• Accessibility
• Accessibility • Signaling
• Retainability • Quality • Traffic / TSLs allocation • Data rates
CS – Basic Call Flow PCH AGCH RACH
Get SDCCH
Establish SDCCH connection
Get TCH
Establish TCH connection
Call phase
Release phase
Requested TSLs to Allocate
TBF Session
Release phase
PS – MO Uplink TBF Ready State
Send RACH
NSN Internal Document 3 © Nokia Siemens Networks
Establish immediate assignment
Get PDCH
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance optimization Performance optimization will include here:
CS
PS
• Accessibility
• MM and SM Signaling
• Signaling problems
• Retainability • TCH Dropped calls
•GPRS Attach •PDP Context activatios
• RLC/MAC TSL data rate •TBF Failure
• Quality
• E2E Data Rate
• interference
•Throughput
• Traffic • Traffic handling
• Multislot usage •Territory downgrades/upgrades •PS Blocking
• Mobility NSN Internal Document 4 © Nokia Siemens Networks
•Cell reselection Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance optimization – Accessibility Signaling
CS
If problems with RACH, AGCH, PCH capacity • Check if combined signaling is existing. If it is existing, it should be removed Here is combined sdcch in TSL0 Should be TSL0 = BCCH TSL1= SDCCH
• Check if TRXSIG is big enough, default value for TRXSIG is 32k.If lots of SMS traffic + HR is used 64k should be used. • Check if there are any bad interference problems – Bad interference problem can cause lot of repetitions => more blocking • Check CCCH related parameters • Check if location areas are optimized – Sizes – Borders NSN Internal Document 5 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance optimization – Retainability TCH drop
CS
Most Common TCH drop reasons can be seen here Drop Reason TCH radio fail call TCH radio fail old TCH tc fail call TCH tc fail old Lapd fail BTS fail user act BCSU reset cnfg act Act fail call Abis fail call Abis fail old A if fail call A if fail old
NSN Internal Document 6 © Nokia Siemens Networks
Counter c1013 c1014 c1029 c1030 c1046 c1047 c1048 c1049 c1050 c1081 c1084 c1085 c1087 c1088
Description Transactions ended due to radio failure. Transactions ended due to old channel failure in HO. Transaction failures due to transcoder failure. Transaction failures due to transcoder failure on old channel during HO. Transaction failures due to Lapd problems. Transaction failures due to BTS problems. Transaction failures due to user actions. Transaction failures due to BCSU reset. Transaction failures due to radio network Channel activation failures during call. Abis failures during call. Abis failures on old channel during TCH HO. A if failures during call. A if failures on old channel during TCH HO.
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance optimization – Retainability TCH drop
CS
TCH DROP Distribution
Excersise What can be typical reason for TCH radio drops? NSN Internal Document 7 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Performance optimization – Quality RX Quality – Level Distribution Rx Quality x Rx Level
CS
NOTE! Same level – quality distribution for both UL and DL HW Problem: Bad Quality
Good Quality
for all Rx Levels Coverage Problem: Bad quality and Low Rx Level
HW Problem All samples below 100dBm CL10 territory not big enough. If possible, add more dedicated timeslots
• Transmission problems – EDAP congestion – Gg congestion
NSN Internal Document 21 © Nokia Siemens Networks
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Performance optimization – Multislot Usage
PS
Territory downgrade and upgrade • Territory downgrade due to CSW traffic rise (c1179) – CS traffic handling • Territory downgrade due to less PSW traffic(c1181) – Territory optimization, territory is perhaps not big enough – CS Traffic handling • Territory upgrade request rejection beyond default territory – Upgrade request beyond Default territory for additional resources (c1174), which can be rejected because of: 1. No (E)GPRS capable resource left (No (E)GPRS enable TRX or the maximum (E)GPRS capacity reached) 2. PCU and EDAP capacity limitation (256 Abis TSL per PCU) 3. High CSW load 0
1
Default territory
2
3
1174
4
5 1179
1181 1180
NSN Internal Document 22 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
6
7
Performance optimization – PS Blocking
PS
• Hard blocking – no resources available – More TSLs for data must be available Check unavailability in the cell More dedicated timeslots for data Amount of CS traffic must be reduced (traffic handling with features) – RF optimization => better throughput => less blocking
• Sof blocking – TSL allocation problems – Check parameters Territory parameters, CDED, CDEF Check also also (E)GPRS parameters Check also timers • Too much delays => more blocking
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Performance optimization – Cell Reselection PS Typical main causes: • Bad overshooting – Dominance areas are not clear – Too much cell reselections
• Link balance problems – UL / DL
• Cell reselection parameters are not properly planned – Check C1,C2, NCCR parameters – Check IFP, TFP parameters
• BSC / PCU area optimization is not properly done – Delays will be increased if areas are not properly planned NSN Internal Document 24 © Nokia Siemens Networks
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Traffic and Capacity Optimization
NSN Internal Document 25 © Nokia Siemens Networks
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Traffic and Capacity Optimization GSM Architecture Traffic and Capacity Optimization levels • • • • • •
Ater, Transcoder (TC), A-interface BSC level Site level TRX level Timeslot level TC Signaling
MSC
A Ater Air interface
BTS 2G
BS C
Abis
NSN Internal Document 26 © Nokia Siemens Networks
BC S U
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Gb
SGSN
Traffic and Capacity Optimization Introduction • Ater, TC, A – Capacity and pools
• BSC – BSC Type, BSC load, Gb links – BCSU, capacity – EDAP/PCU Type, Load
• Site – Antennas, BTS HW/SW BTS configuration, Dual band, CBCCH, SDCCH traffic etc
• TRX – Where capacity will be needed • Timeslot – FR/HR, AMR FR/HR, territory, CMAX, SDCCH traffic • Signaling – CCCH, TRXSIG, SS7 links NSN Internal Document 27 © Nokia Siemens Networks
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Traffic and Capacity Optimization Ater, TC, A Abis interfaces
Ater Interface •All traffic from BSC must be transferred to transcoders. Number of E1’s in Ater / Asub interface is depending on: • TCH Traffic from all abis IF’s • CCS7 traffics • O&M links • Utilization rate
•1 PCM timeslot in Ater/Asub interface: • 64Kbit/s •1 PCM timeslot in Abis interface : • FR= 16 kbit/s • HR = 8 kbit/s => 4 or 8 PCM timeslots in abis = 1 PCM timeslot in Ater NSN Internal Document 28 © Nokia Siemens Networks
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Traffic and Capacity Optimization Ater, TC, A Required transcoding (TC) capacity is derived from • Total number of required Ater Channels. • Number of Ater channels is based on total Erlangs in BSC and blocking in A-interface • Configuration options for TCSM3i for standalone installations can be seen below TCSM3i units (capacity step) ETSI channels ANSI channels
1 2 3 4 5 6 7 8 9 10 11 NSN Internal Document 12 29
© Nokia Siemens Networks
960 1920 2880 3840 4800 5760 6720 7680 8640 9600 10560 11520
760 1520 2280 3040 3800 4560 5320 6080 6840 7600 8360 9120
ET 16
ET 16
(16 E1 PCMs)-1 BSC
(16 E1 PCMs) several BSCs
3 5 8 10 13 15 18 20 23 25 28 30
3 6 9 12 15 18 21 24 27 30 33 36
TR3E
8 16 24 32 40 48 56 64 72 80 88 96
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Note. In some solution Transcoder can be implemented to Media Gateway MGW
Traffic and Capacity Optimization Ater, TC, A A Interface Number of required A- Interface PCMs is derived from total number of required Ater Channels. 4:1 multiplexing 1 : 120
For Example • Total Erlangs in BSC = 3920 Erl • Blocking in A-interface =0.1% → ErlangB table(3920,0.1QoS ) → 4042 Ater Channels
→ Ater Interface PCMs → A interface PCMs(1:4) NSN Internal Document 30 © Nokia Siemens Networks
ETSI Channels 960 1920 2880 3840 4800 5760 6720 7680 8640 9600 10560 11520
4:1
Ater interface PCMs 8 16 24 32 40 48 56 64 72 80 88 96
A interface PCMs (4:1)
= 4042(ETSI) / 120 = 34 = 34*4 = 136
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32 64 96 128 160 192 224 256 288 320 352 384
Traffic and Capacity Optimization BSC • Example of BSC capacity evolution Static limits # TRX #BTS #BCF #BSCU #SS7L #LAPD # (logical) PCU # abis 16k channels #E1/T1 lines Erlangs
BSC2i
BSC3i 660
512 512 248 6 16 992 16 4096 144 3040
660 660 504 6 16 1236 24 6144 256 3920
BSC3i 1000/2000 1 cab 2 cab 1000 2000 1000 2000 1000 2000 5 10 16 16 2240 4480 50 100 12800 25600 384 800 5940 11880
BSC3i 3000 3000 3000 3000 6 16 5760 30 30720 800 17820
How Erlangs are calculated? • This depends on used traffic profile • Different traffic profile => different results Example, How to calculate BH call attempts = (Total_Erl x 3600s) / mean_holding_time(s) NSN Internal Document 31 © Nokia Siemens Networks
Traffic Profile example Mean holding time Mobile originated calls (MO) Mobile terminated calls (MT) Handovers per call Location updated per call IMSI detach per call Paging response SMS (req(subs/1 hour) Terminated SMS 80% QoS
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120s 70% 30% 1.5 2 0.1 63% 1 80% 2%
Traffic and Capacity Optimization BSC - Example of Utilization BSC Utilization • TRX Usage • TCH Usage
Actual TRX utilization Actual TCH Utilization
If utilization values are too high => BCS Capacity optimization will be needed
Utilization analysis can be used for long term BSC optimization Capacity management vs. configuration optimization NSN Internal Document 32 © Nokia Siemens Networks
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Traffic and Capacity Optimization BSC - EDAP / PCU / Gb
• EDAP capacity can be optimized based on KPI values – – – – – –
DL / UL MCS selection limited by EDAP (dap_7a, dap_8c) DL / UL MCS selection limited by PCU (dap_9, dap_10) Peak DL EDAP usage (c76004) Peak UL EDAP usage (c76005) Territory upgrade rejection due to lack of PCU capacity (blck_32) Not too much capacity nor too less capacity
• EDAP / PCU performance can be decreased due to Gb link size – UL/ DL Gb load: frl_7a/ frl_8a – This should be checked always with EDAP / PCU optimization
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Traffic and Capacity Optimization BSC - EDAP / PCU
• EDAP blocking – If EDAP utilization is below 100 => increasing EDAP does not provide any help => PCU optimization needed – As a rule of thumb the following estimation may be used to calculate number of E1’s. Nbr of TRX
Amount of E1s
12 TRX GSM / GPRS
1 E1
9 TRX GSM / EGPRS 6 TRX GSM / Heavy EGPRS 18 TRX GSM / GPRS
1.5 E1
15 TRX GSM / EGPRS 12 TRX GSM / Heavy EGPRS 24 TRX GSM / GPRS
2 E1
21 TRX GSM / EGPRS 18 TRX GSM / Heavy EGPRS
NSN Internal Document 34 © Nokia Siemens Networks
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Note! Can be used also T1s E1:32 channel T1:24 channel
Traffic and Capacity Optimization BSC - Gb
• Gb utilization – If values near thresholds, it is recommended to increase Gb link size OR Implement Gb over IP Maximum received load % ( DL )
NSN Internal Document 35 © Nokia Siemens Networks
Gb bandwidth [kbps]
Restricting Gb link utilisation [%]
128
25
256
61
384
68
512
68
640
70
768
75
896
85
1024
90
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Traffic and Capacity Optimization Site - Indoor solution Indoor solutions Before
4 TRX, 20Erl
After
2 TRX, 5Erl
Indoor Site 4TRX, 15Erl
Note! Indoor solution is collecting traffic inside (heavy traffic) office => Less frequencies is needed outside the building
NSN Internal Document 36 © Nokia Siemens Networks
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Traffic and Capacity Optimization Site - Dual Band Network Before
GSM 900 layer (4TRX:24Erl (Bad blocking), GSM 900 layer (2TRX:2Erl)
Actions:
After GSM 900 layer (2TRX:7Erl (no blocking) GSM 1800 layer (4TRX:21Erl)
• • • •
1800 layer was added From 900 layer traffic to 1800 layer 3 TRX was removed from 900 layers Total traffic was increased
GSM 900 layer (1TRX:1,5Erl
Note! Dual band layers can be also GSM 900 and WCDMA
NSN Internal Document 37 © Nokia Siemens Networks
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Traffic and Capacity Optimization Site – Traffic layers Traffic layers
3G Layers • 2100 Macro • 2100 Micro • 2100 Indoor
2G Layers • • • •
Note! Traffic between layers can be handled by parameters NSN Internal Document 38 © Nokia Siemens Networks
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900 Macro 1800 Macro 900/1800 Micro 900/1800 Indoor
Traffic and Capacity Optimization TRX – capacity where it is needed Site configuration 2+2+2 in all sites Bad Blocking area 8Erl 5Erl
3Erl
• More capacity is needed
9Erl 2Erl
1Erl
4Erl 5Erl 5Erl
6Erl
1Erl
4Erl
1Erl
Extra capacity 4Erl 3Erl NSN Internal Document 39 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
• 2 trx / cell is too much •=> TRX can be transferred to the cells where these are more needed
Traffic and Capacity Optimization Timeslot – AMR FR/HR Half rate (HR) is recommended to use when: • More capacity will be needed but additional TRXs can not be added – Interference problems, Frequency reuse – HW limitations
• Temporary needs for additional capacity – Special events – Due to daily traffic profile, additional capacity will be needed just for short time • Big cruise is passing by, tens of calls during short time
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Traffic and Capacity Optimization Timeslot – AMR FR/HR • Channel Mode Adaptation is an HO algorithm that aims at select the correct channel rate (FR or HR). • The selection of the channel rate depends on 2 main factors: load and quality Codec Good Quality
load
AMR FR
AMR FR
packing unpacking
AMR HR
AMR HR
Bad Quality NSN Internal Document 41 © Nokia Siemens Networks
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Traffic and Capacity Optimization Timeslot – FR/HR & PS territory
Strategy – which timeslots for data and which for speech? • BFG –parameter • Whether the BCCH TRX or other TRXs are preferred in GPRS channel allocation .
• FRL –parameter • With this parameter the percentage of full rate TCH resources that must be available for traffic channel allocation is defined.
• FRU –parameter • With this parameter the percentage of full rate TCH resources that must be available for traffic channel allocation is defined.
• Note! Territory and dual rate in same TRX(HR just after territory) => not good, should be changed TRX1
tsl0
tsl1
bcch
sdcch
tsl0
tsl1
NSN InternalTRX2 Document 42 © Nokia Siemens Networks
tsl2
tsl2
tsl3
tsl3
tsl4
tsl4
tsl5
tsl5
tsl6
tsl6
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tsl7
tsl7
How to allocate CS and PS channels?
Traffic and Capacity Optimization – AMR and PS interworking, CS TCH Allocation Calculation CS TCH allocation calculation (CTC) •
Defines how the GPRS territory is seen when calculating FR resources.
EGPRS used/default
MBCCHC
x
x
x
x
x
TCHD
TCHD
TCHD
TCHD
TCHD
TCHD
5 CS calls CTC 0
CTC1
CTC2
1
1
2
Working FR TCH resources 6
7
7
% of free FR resources
16.7%
14.3%
28.6%
HR Preferred?
N
Y
N
Free FR TCH resources
x EGPRS downgraded
MBCCHC
TCHD
x
x
TCHD
TCHD
x TCHD
x
CTC Value 0 = Only CSW used RTSLs are used to calculate CDEF resources 1 = CSW and PSW used RTSLs are used. PSW used RTSLs are seen as occupied resource when calculating Territory downgrade due to PSW RTSLs CS traffic 2 = CSW used and PSW used RTSLs are used. PSW used RTSLs are seen as idle resource when calculating resources
x
TCHD
TCHD
downgrad ed
6 CS calls
FRL = relative amounts of free FR TCH resources in proportion to working FR TCH resources FRL = 15% in this example
Free FR TCH resources
1
1
1
Working FR TCH resources 7
7
7
% of free FR resources
14.3%
14.3%
14.3%
HR Preferred?
Y
Y
Y
NSN Internal Document 43 © Nokia Siemens Networks
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Traffic and Capacity Optimization Timeslot – AMR FR/HR HR will be allocated when there are few free FR TCHs available. • The purpose is to avoid congestion / blocking • HR => FR when there are again enough free FR TCHs • Thresholds are set by parameters (FRL, FRU) Free FR TCHs Upper limit for free FR TCHs
Lower limit for free FR TCHs
Time No packing of FR calls
NSN Internal Document 44 © Nokia Siemens Networks
Packing of FR calls
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No packing of FR calls
Traffic and Capacity Optimization signaling -paging Paging TRXSIG can be dimensioning based on following table: • After implementation paging capacity KPIs and occurrence of LAPD overload must be checked TRXSIG
Comments
16k
Can be used if 32k is not possible to use
32k
Default value. Must be used if HR is used or high SMS traffic Must be used if HR is used and high SMS traffic
64 k
Note! If the cell is part of the large location area, high paging load is expected. Thus small signaling links (16kbps) shall be avoided. NSN Internal Document 45 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Traffic and Capacity Optimization signaling -sdcch • Capacity of SDCCH in the cell is depending on the amount of TRX’s in the cell • Capacity of SDCCH in the cell is also depending heavily on Traffic profile, for example amount of SMS’s Number of TRX in the cell 1 2 3 4 5
Number of SDCCH in the cell SDCCH Traffic (Erl) Erl mErl/subs subs 1 sms/subs/hour 5 sms/subs/hour 10 sms/subs/hour 1 sms/subs/hour 5 sms/subs/hour 10 sms/subs/hour 2.2 25 88 0.4 0.8 1.3 1 1 1 8.2 25 328 1.6 3.1 4.9 1 2 2 14.9 25 596 3.0 5.6 8.9 1 2 3 21 25 840 4.2 7.9 12.6 2 2 3 27 25 1080 5.4 10.2 16.2 2 3 4
• SDCCH blocking KPIs should be monitored & avoided – And reason for blocking, SMS, LU, paging etc should be known.
• Note! Exceptions are cells that cover ports of entry, such as airports, where a large number of subscriber location updates are expected NSN Internal Document 46 © Nokia Siemens Networks
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Traffic and Capacity Optimization signaling - sdcch Increased Dynamic SDCCH • SDCCH resources are used for call • •
• •
establishment, location updates and short messages (SMS) Dynamic SDCCH allocation feature configures additional SDCCH resources according to the traffic situation in a cell When a BTS needs temporarily larger SDCCH capacity, then idle TCH resources are configured for the SDCCH use When the congestion situation is over extra SDCCH resources are configured immediately back to TCH resources By using Increased Dynamic SDCCH Capacity, you can use up to 32 SDCCHs per non-BCCH TRX and 24 per BCCH TRX
NSN Internal Document 47 © Nokia Siemens Networks
BCCH SDCCH/8 TCH
TCH
TCH
TCH
TCH
TCH
BCCH SDCCH/8SDCCH/8
TCH
TCH
TCH
TCH
TCH
• In case of S DC C H congestion, one free traffic channel can be changed dynamically to S DC C H/8 • When S DC C H/8 is no longer needed it is changed dynamically back to TC H
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Coverage Optimization
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Solution finding – coverage optimization
20 km away from site • Signal level -95dBm? • Are both cases critical ones? • Are both cases coverage problem
20km
cases? Bad coverage – what does it mean? 20km
NSN Internal Document 49 © Nokia Siemens Networks
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SiteA
Solution finding – coverage optimization Signal level – quality distribution 12478 samples • signal level < -100dBm • Quality 7 => UL coverage problem?
251992 samples • signal level < -100dBm • Quality 0 => UL coverage problem?
Exercise How we should here optimize coverage? • Any problems? SIGNAL LEVEL
QUALITY
UL DL
NSN Internal Document 50 © Nokia Siemens Networks
-100dBm -95dBm -90dBm -80dBm -70dBm -47dBm
UL_q0 251992 123653 62938 27005 2831 751
UL_q1 30668 1151 247 51 3 0
UL_q2 20552 403 144 65 9 4
UL_q3 18417 692 288 149 28 10
UL_q4 18156 519 353 177 87 25
UL_q5 18286 351 129 82 10 1
UL_q6 16983 221 62 40 6 0
UL_q7 12478 72 29 16 0 0
-100dBm -95dBm -90dBm -80dBm -70dBm -47dBm
DL_q0 27862 89094 142228 222462 44504 5994
DL_q1 5537 4236 2732 1523 91 49
DL_q2 5529 3853 2550 1355 123 17
DL_q3 6069 3576 2356 1552 151 17
DL_q4 6109 2893 1510 716 81 12
DL_q5 6107 2264 1114 812 101 29
DL_q6 5389 1372 774 1081 191 65
DL_q7 4119 584 404 343 88 10
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Solution finding – coverage optimization Signal level UL coverage should be improved
SIGNAL LEVEL
QUALITY
UL DL
-100dBm -95dBm -90dBm -80dBm -70dBm -47dBm
UL_q0 251992 123653 62938 27005 2831 751
UL_q1 30668 1151 247 51 3 0
UL_q2 20552 403 144 65 9 4
UL_q3 18417 692 288 149 28 10
UL_q4 18156 519 353 177 87 25
UL_q5 18286 351 129 82 10 1
UL_q6 16983 221 62 40 6 0
UL_q7 12478 72 29 16 0 0
-100dBm -95dBm -90dBm -80dBm -70dBm -47dBm
DL_q0 27862 89094 142228 222462 44504 5994
DL_q1 5537 4236 2732 1523 91 49
DL_q2 5529 3853 2550 1355 123 17
DL_q3 6069 3576 2356 1552 151 17
DL_q4 6109 2893 1510 716 81 12
DL_q5 6107 2264 1114 812 101 29
DL_q6 5389 1372 774 1081 191 65
DL_q7 4119 584 404 343 88 10
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Solution finding – coverage optimization Solutions to improve coverage • Antenna changes Tilting Adding antenna with bigger gain
• New cell / site Costly
• DL /UL amplifiers DL, boosters UL, Mast head amplifier (MHA)
• Diversity UL
• Reducing losses Combiner types Feeder types
900MHz
• Better site / antenna place NSN Internal Document 52 © Nokia Siemens Networks
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Solution finding – coverage optimization indoor coverage •Many networks have insufficient indoor coverage due to high building penetration loss. This includes subways, under ground facilities and tunnels. •Outdoor coverage is normally ok in urban and city area. Interference is more an issue for outdoor users. •Micro cell and Indoor cell are good solution to improve indoor coverage and network quality. – Antenna location is main factor for successful indoor coverage planning
Indoor BTS Indoor Panel Antenna
Optical Fiber
Remote Unit NSN Internal Document 53 © Nokia Siemens Networks
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Master Unit
RF Cable
Solution finding – coverage optimization indoor coverage Other features can be also used for coverage optimization • Extended cell • Smart radio concept • Antenna hopping
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Examples of wrong parameter set impact on network operation/performance – call setup, qual, bands
1. No calls happening in a cell • Cell Barred • Non existent (LAC, Cell ID) in MSC • DMAX = 0
2. Very few calls happening in a cell • RxLevAccesMin • Wrong MNC, MCC, LAC declaration
3. Very low traffic in a cell • msTxPwrMax = 0, bsTxPwrMax = 30
4. Bad quality in UL after rehoming 5. Few traffic in 1800 layer of a dual band 900/1800 network
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Example 1a No calls happening in a cell: • The cell has been barred Handover
C all S etup SY S (C IN ell FO Ba rrA 3 (B ye cc CC s) es H s= )
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Example 1b No calls happening in a cell: • CI different between MSC and BSC or non existent (LAC, Cell ID) in MSC
NSN Internal Document 57 © Nokia Siemens Networks
MSC does not find (LAC, CI) in its database Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Example 1c No calls happening in a cell: • MsMaxDistanceInCallSetup (DMAX) = 0 Despite the coverage of the cell, no calls will be established!
DMAX = 0
NSN Internal Document 58 © Nokia Siemens Networks
Call Setup
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RxLevel = -70 dBm
Example 2a Very few calls happening in a cell: • RxLevAccesMin Mapping
OSS database
BSS MML
Lowest range
0
-110 dBm
1
-109 dBm
...
...
62
-48 dBm
63
-47 dBm
Highest range
Be careful when setting parameter through xml or dat file! OSS database unit should be used to specify parameter value!
Cell coverage
RxLevAccessMin = -47 dBm
NSN Internal Document 59 © Nokia Siemens Networks
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Example 2b Very few calls happening in a cell: • Wrong MNC, MCC, LAC declaration in network - MNC: 01 ≠ 1 !!! (In OSS correct value)
Note! Be careful when setting parameter through xml or dat file! OSS database unit should be used to specify parameter value!
NSN Internal Document 60 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Example 3 Very low traffic in a cell: •msTxPwrMax = 0, bsTxPwrMax = 30
lta e ∆D
Parameter
bsTxPwrMax bsTxPwrMin minMsTxPower msTxPwrMax
Value_______
0 … 30 dB 0 … 30 dB 0 … 36 dBm 0 … 36 dBm
Attenuation Values (dB) BTS Max Power = BTS Power – (bsTxPwrMax = 0 dB) BTS Min Power = BTS Power – (bsTxPwrMin = 30 dB)
te u l so b A
Power Values (dBm) MS Max Power = (msTxPwrMax = 33 dB) MS Min Power = (minMsTxPower = 13 dB)
NSN Internal Document 61 © Nokia Siemens Networks
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Default value
0 dB 30 dB 0 dB
Example 4 Bad quality in UL after rehoming: • DiversityUsed parameter not set to yes anymore
After rehoming RDIV parameter was set to default value (No) and UL quality was affected.
RDIV = Y
Uplink Diversity improves quality of signal received.
NSN Internal Document 62 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Example 5 Few traffic in 1800 layer of a dual band 900/1800 network: • Idle Mode: C2 parameters not set properly (temporaryOffset, penaltyTime) • Idle / dedicated mode parameters should be according to strategy
BCCH BCCH
slow moving mobile 1800: micro-Layer NSN Internal Document 63 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
fast moving mobile 900: macro-layer
Frequency Optimization
NSN Internal Document 64 © Nokia Siemens Networks
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Solution finding – frequency optimization GSM network is based on good frequency planning Bad frequency planning is causing high interference levels • Lots of drop calls • CS/PS quality is bad • Features are not working properly • Maybe new sites are built due to bad interference problems • Lots of customer complaints • Finally less customers => Frequency plan should be properly done
NSN Internal Document 65 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Basic Theory How to analyze my frequency plan • Frequency reuse distance • Frequency allocation reuse • Frequency load • Effective frequency load
NSN Internal Document 66 © Nokia Siemens Networks
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Solution finding – frequency optimization Theory, Effective reuse • Since the frequency band is always limited, the frequencies have to be reused in the network. • As the reuse distance becomes smaller, there are more frequencies available for each cell, so more capacity can be provided. • The effective reuse is essentially the same as the conventional frequency reuse distance.
Reff =
N freqsTOT N TRXave
where: Reff = effective reuse NfreqsTOT = total number of used frequencies NTRXave = average number of TRXs in a cell
Note! The smaller the effective reuse, the higher the capacity in terms of the number of TCHs provided by one frequency in the network. NSN Internal Document 67 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Theory, Frequency Allocation Reuse RF Hopping only •
Frequency allocation reuse indicates how closely the frequencies are actually reused in a network.
FAR =
N freqsTOT N freqs/ MA
where: FAR = frequency allocation reuse NfreqsTOT = total number of used frequencies Nfreqs/MA = average number of frequencies in MA-lists
• •
It indicates the severity of a worst case C/I in the cell border. If the network doesn’t utilize fractional loading, the frequency allocation reuse is the same as the effective reuse.
NSN Internal Document 68 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Theory, Frequency load • The C/I is low when frequency collisions occur. – In order to guarantee an adequate quality, the collision probability has to be made low. – The collision probability depends on the load of the hopping frequencies called a frequency load.
• The frequency load describes the probability that a frequency channel is used for transmission at one cell at one time. • The frequency load is a product of two other loads: – hard blocking load (the average busy hour TCH occupancy in most of the cases) – fractional load
L freq = LHW ⋅ L frac where: Lfreq = frequency load LHW = the busy hour average hard blocking load (see next slides) Lfrac = fractional load (see next slides) NSN Internal Document 69 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Theory, Hard blocking load • The hard blocking load is calculated as
LHW =
ThopTCH N hopTCH
where: LHW = hard blocking load ThopTCH = average number of used TCHs in the busy hour NhopTCH = total number of TCHs in the hopping TRXs
NSN Internal Document 70 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Theory, Fractional load • Fractional load means that the cell has been allocated more frequencies than TRXs. This is only possible for RF hopping TRXs. • The fractional load is very useful when the number of TRXs is low. By utilizing fractional load, it is possible to provide enough frequencies to hop over (to get FH gain) to even a cell with just one hopping TRX.
L frac
NTRX = N freqs/cell
where: Lfrac = fractional load NTRX = number of TRXs in a cell Nfreqs/cell = number of frequencies allocated to a cell (MA-list length) NSN Internal Document 71 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Theory, Frequency Load,HW and fractional load 75 %
•“HW •“HWload” load”isis75% 75% •Fractional load •Fractional loadFL FLisis 33TRX TRX/ /55FF==0.6 0.6==60% 60% •“Frequency load” is •“Frequency load” is HWL HWL* *FL FL==45% 45%
25 %
TRX-1
BCCH
1
2
3
4
5
6
7
f1
TRX-2
0
1
2
3
4
5
6
7
f2, f3, f4, f5, f6
TRX-3
0
1
2
3
4
5
6
7
f3, f4, f5, f6, f2
TRX-4
0
1
2
3
4
5
6
7
f4, f5, f6, f2, f3
Active Activeslots slots
NSN Internal Document 72 © Nokia Siemens Networks
Empty Emptyslots slots
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS is on the BCCH layer in this case
Solution finding – frequency optimization Theory, Effective Frequency Load • Coverage limited network has low EFL • Interference limited network has high EFL • It is calculated by the equation mentioned below:
NSN Internal Document 73 © Nokia Siemens Networks
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Solution finding – frequency optimization Visual BCCH Plan Inspection
584 re-used close together
584 re-used close together
Heavy re-use of 582
NSN Internal Document 74 © Nokia Siemens Networks
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Solution finding – frequency optimization BCCH Carrier Utilisation Channel distribution
60
Occurrences
50 40 30 20
C arriers also used in MA List
NSN Internal Document 75 © Nokia Siemens Networks
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584
583
582
581
580
579
578
577
576
575
574
573
571
570
522
521
520
519
518
517
516
515
514
513
0
572
10
Solution finding – frequency optimization BSIC Utilization BSIC allocation distribution • As can be seen from the figure, amount of BSIC combinations are not spread smoothly • BSIC planning is not properly done => risks to double BCCH+BSIC combinations is increased
Note! Good radio network is based on properly done BSIC + BCCH Planning NSN Internal Document 76 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Same color = same frequency
Signal level is good, but quality is bad => Frequency plan is not properly done
NSN Internal Document 77 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Different frequency planning methods
Exercise How these planning methods differs from each other? • Based on Prediction tools – Planning Tools with propagation models
• Based on Interference matrix – Optimizer
• Mapinfo – Visualization
Any other methods? NSN Internal Document 78 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Frequency Hopping Network capacity and performance is typically limited by co-channel interference, multipath fading, delay spread and noise
Interference
Interference Diversity
F1
F3
F1
F1
Frequency Hopping benefits are based on: Interference Diversity • where interference is averaged over multiple frequencies Frequency Diversity • which reduces the needed fading margins
average
F2 F2 F3
F2 F 3
MS_1
Signal Level
MS_2
MS_3
Frequency Diversity F1 F2
Interference averaging and reduced immunity to signal fading gives the possibility to reduce the C/I margins and tighten the frequency reuse schemes
F3
MS Location
Distance
Bursts sent on frequency F2 may be degraded or lost, but the initial signal is still be reconstructed from the bursts on frequencies F1 and F3.
NSN Internal Document 79 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization Frequency Hopping Baseband Hopping 0 TRX 1
1 2
7 Timeslot f1
BC CH
TRX 2
f2
TRX 3
f3
TRX 4
f4
HSN1 Timeslot 0 hops over TRXs 2-4 only BCCH does not hop HSN2 Timeslots 1-7 hop over all TRXs
RF Hopping 0 TRX 1
1
2
BC CH
7
Timeslot
f1 – no hopping
TRX 2 TRX 3 TRX 4 NSN Internal Document 80 © Nokia Siemens Networks
f2,f3..fn – hopping according mobile allocation list One hopping sequence number only Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – frequency optimization DFCA – (Dynamic frequency & channel allocation) Random FH TRX 1
BCCH
TRX 2
Random FH over a fixed frequency list
TRX 3 TRX 4
DFCA TRX 1 TRX 2 TRX 3 TRX 4
NSN Internal Document 81 © Nokia Siemens Networks
•• Loose Looseinterference interferencecontrol control •• Relies Relieson onrandom randomspreading spreadingofofthe the interference interference
BCCH Cyclic FH over individually selected frequency lists and MAIOs for each connection
C/I > C/I target
•• Accurate Accurateinterference interferencecontrol control(C/I (C/Iestimations) estimations) •• Each Eachconnection connectionisisassigned assignedwith withthe themost mostsuitable suitable radio channel (MA list, MAIO, TSL) radio channel (MA list, MAIO, TSL) Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Frequency optimization– Consistency check Cells with co-channel and adj-channel frequencies
A
Cell A
-6dB -9dB
Cell B B
F R E Q =10
F R E Q =9,10,11
• Co-channel frequencies: HO is not possible in case of co-BCCH • Adj-channel frequencies: Ho is possible but might fail due to interference. • If Co / Adj-channel frequencies are existing, these must be removed
NSN Internal Document 82 © Nokia Siemens Networks
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Frequency optimization– Consistency check Check BCCH-BSIC and BCCH reuse distance Small distances may be dangerous!
FRE Q = 234 BS IC = 42
FRE Q = 234
FRE Q = 234 BS IC = 42
R euse 4/12 NSN Internal Document 83 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Frequency optimization– Consistency check Other Checks • • • • •
Neighbors with co-channel frequencies Neighbors with adj-channel frequencies Neighbors of a same cell with co-BSIC, co-BCCH Neighbors from other Vendor Frequencies / co-BSICs near the country border ( if available)
NSN Internal Document 84 © Nokia Siemens Networks
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Examples of wrong parameter set impact on network operation/performance – frequencies
1. Drop call rate increase after new frequency plan implementation •
Double BA List activated
2. Impossibility to unlock some BTS after a RF-frequency hopping implementation 3. Impossibility to unlock some BTS after a frequency retune • •
NON-EDGE TRX, with GTRX = Y TRX, with GTRX = Y, not attached to any EDAP pool
NSN Internal Document 85 © Nokia Siemens Networks
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Example 1 Drop call rate increase after new frequency plan implementation: • In the meantime, measurementBcchAllocation has been changed to idle and MA list defined with old BCCH frequency band O LD MA List BCCH
TCH
TCH
BCCH
TCH
OLD FREQUENCY PLAN
NE W FREQUENCY PLAN
These BCCH frequencies will not be measured by old MA List These TCH frequencies will be wrongly measured
NSN Internal Document 86 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Example 2 Not possible to unlock some BTS after a RF-frequency hopping implementation:
• After frequency hopping retune, some BCCH frequency equal to TRX frequency of non-BCCH TRXs • After changing TRX frequency, verify BSIC and TSC (Training Sequence Code) is changed accordingly.
NSN Internal Document 87 © Nokia Siemens Networks
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Example 3a Impossibility to unlock some BTS after a frequency retune: • NON-EDGE TRX, with GTRX = Y, in a cell with EGENA set to yes SEG EGENA = Y
B
BTS
(E)GPRS territory GTRX = Y GTRX = Y
NSN Internal Document 88 © Nokia Siemens Networks
SEG EDGE TRX(s) NONEDGE TRX(s)
EGENA = Y
B
BTS
(E)GPRS territory EDGE TRX(s) GTRX = Y GTRX = N
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
NONEDGE TRX(s)
Example 3b Impossibility to unlock some BTS after a frequency retune: • TRX, with GTRX = Y, not attached to any EDAP pool in a cell with EGENA set to yes SEG EGENA = Y 1
B
2
BTS
(E)GPRS territory EDGE TRX(s) GTRX = Y GTRX = N
NONEDGE TRX(s)
Add TRX-1 to EDAP pool
NSN Internal Document 89 © Nokia Siemens Networks
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EDAP pool
Neighbor Optimization
NSN Internal Document 90 © Nokia Siemens Networks
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Solution finding – neighbor optimization • Keep the neighbor list in order. – Note! If lots of overshooting => dominance areas are not clear => neighbor list are getting bigger. – Bad overshooting should be avoided – Missing neighbors – the worst situation
• Use the Handover Adjacency Statistics to identify and remove neighbors – Bad overshooting cells can cause problems
• ISHO optimization Avoid: • neighbor definitions that are co-BCCH and co-BSIC or Adj-BCCH and co-BSIC that can lead to wrong neighbor reporting • One-way neighbors
NSN Internal Document 91 © Nokia Siemens Networks
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Solution finding – neighbor optimization
GREEN = source RED =neighbor cell BLUE = no neighbor
As can be seen, neighbors are not fully optimized. There are missing neighbors and on the other hand, some far away cells are neighbors NSN Internal Document 92 © Nokia Siemens Networks
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Solution finding – neighbor optimization
GREEN = source RED =neighbor cell BLUE = no neighbor
NSN Internal Document 93 © Nokia Siemens Networks
Overshooting cells => added to neighbor list. Neighbor planning is more difficult to do, if lots of overshooting cells
In this area there might be big problems due to unoptimized neighbors Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – neighbor optimization Challenges • Sites by the sea • Dominance areas are reaching far away => neighbor cells can be far away SEA
• Indoor solutions • Signal levels from outdoor cells near windows can be high
• High buildings • Lots of cells can be heart near the window
• 3G cells • Limited amount of neighbors NSN Internal Document 94 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Only few neighbor cells => in the sea there will be problems
Solution finding – neighbor optimization Neighbor optimization based on statistics • HO attempts, blocking and fails can be analyzed as source or target cells • Neighbor removing can be done based on stats
In case Number of HO Attempts is very low to a certain cell, consider removing this cell from Adjacency list.
NSN Internal Document 95 © Nokia Siemens Networks
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Neighbor Planning – Consistency check Non symmetrical adjacencies Find all non symmetrical adjacencies : • cell B is neighbour of Cell A • cell A is not neighbour of Cell B
Cell A
Cell B
• If there are non symmetrical adjacencies, these must be changed to symmetrical adjacencies NSN Internal Document 96 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Neighbor Planning– Consistency check Neighbours with co-channel and adj-channel frequencies or co-BSIC, co-BCCH Cell B f=10
f=10, BSIC=2,2
Cell A f=24
Cell C
f=9,10,11
f=10, BSIC=2,2
Neighbours with co-BSIC, co-BCCH: • Might generate ghost-access and HO drop calls. • High sdcch abis failure and high handover failure could be indicators for this case. NSN Internal Document 97 © Nokia Siemens Networks
f=24
Neighbours with co-channel or adjacent channel frequencies: •Will cause interference between neighbour cells
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – neighbor optimization Different methods Exercise How these planning methods differs from each other? 1.Add maximum nbr of neighbors and after 2 weeks remove extra neighbors based on HO statistic 2.First only nearest (dominance area) and if problems, add more neighbors In neighbor optimization following selection methods can be used • Based on Optimizer • Based on Map • Based on OSS Statistics
NSN Internal Document 98 © Nokia Siemens Networks
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Neighbor planning– Consistency check Other Checks • • • • •
Check cells in MSC vs cells in BSC Check external adjacencies in MSC Non symmetrical adjacencies Neighbors of a same cell with co-BSIC, co-BCCH 3G neighbors
NSN Internal Document 99 © Nokia Siemens Networks
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Handover Optimization
NSN Internal Document 100 © Nokia Siemens Networks
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Solution finding – HO optimization HO Strategies – Traffic handling (900-1800 layers)
PBGT, quality, level
1800 layer
Umbrella Traffic Reason IUO PBGT, quality, level
900 layer
NSN Internal Document 101 © Nokia Siemens Networks
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Solution finding – HO optimization Optimizing HOs, Reduce unnecessary HOs old
• DL Level HO typically (-94dB) • Quality HO 3dB • HO Level margin 2dB => if Cell1 -98dBm => Cell2 >-96dBm => HO => might be HO fail if for example some imbalance
new ⇒ HO level margin => 24dBm (=disabled in this case) ⇒ Quality HO 3dB (HO is done only if quality problems) ⇒ No HO, AMR is used => no drops and quality is OK ⇒ PBGT is still working. Value can be decreased if problems)
Unnecessary HO is prevented in this area
-100dBm Cell1
Cell2
route -100dBm
NSN Internal Document 102 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – HO optimization Optimizing HOs, HO parameters • Umbrella ( AUCL parameter) • AMR FR/HR – Packing, unpacking parameters • Interference / quality HO – If interference level -75dB => interference problems in good signal level – Rest are quality HOs => bad quality can be also due decreased signal level. – This difference is good to know
• Level / PBGT – If margin is same as PBGT, the only difference is level, See example in previous slide where Level HO disabled. – It is useful to know if overlapping in good signal level and bad signal level Can be noticed if overshooting If no Level HOs => real coverage problems without overlapping NSN Internal Document 103 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – HO optimization AMR + Power Control & HO control co-ordination in UL Quality (BER) (PxNx:6/16)
UURF
0
Packing of the call
Power down quality (PxNx:4/6)
IHRF
1
No action (PxNx: 2/3)
LURF
3
Power up quality IHRH
4
(PxNx: 4/6)
(PxNx:1/1)
(PxNx:1/1)
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
RxLevel Power down level
NSN Internal Document 104 © Nokia Siemens Networks
UUR (POC) -70
(AMR) Qual HO HYS -6dB
Handover trigger
-110dBm
LUR (POC) -95
Handover trigger
Power up level
5
LUR (HOC) -95
QURF
(PxNx: 1/1)
Unpacking the call
-47dBm
HO Optimization – Consistency check Synchronized handover Non-synchronized Handover – MS sends access bursts (HO_ACCESS) (with varying TA) until it receives PHYSICAL_INFO Synchronized Handover – MS sends a few access bursts (HO_ACCESS) and then starts transmission with previous TA Non-synchronised handover leads to a longer communication interruption than synchronised handover (200ms vs. 100ms) Synchronized HO should be activated between sectors of the same site. If activated on inter-site adjacencies the handover can fail Synchronized HO
Non- Synchronized HO
Site A NSN Internal Document 105 © Nokia Siemens Networks
Site B
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Solution finding – HO optimization Different methods Exercise 1 In which case the network is working better? (theoretical) • All handovers are quality handovers • All handovers are level handovers Exercise 2 How these differs from each other? • Quality HO vs. Interference HO • PBGT vs. Level HO • Traffic handling : decreased power 2 dB vs. decreased HO margin 2dB
NSN Internal Document 106 © Nokia Siemens Networks
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HO planning– Consistency check Other Checks • • • • • •
Check cells in MSC vs cells in BSC Check external adjacencies in MSC Neighbors with co-channel frequencies Neighbors with adj-channel frequencies Neighbors of a same cell with co-BSIC, co-BCCH Check site with same MA List in different sectors and different HSN • Check site with same MA List in different sectors and MAIO collision
NSN Internal Document 107 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Examples of wrong parameter set impact on network operation/performance – Handover
1. No handover from a cell towards all its neighbours •
PLMN permitted = No
2. High Handover failures after implementation of new adjacency plan •
SYNC = YES
3. No handover happening from an interfered cell •
hoMarginQual set to 0
4. 100% of handover failures in an adjacency relation •
Co-BSIC co-BCCH declarati
5. High number of handovers •
hoThresholdsLevUL = hoThresholdsLevDL
6. Handover not happening when DL signal level of neighbour much greater than serving cell •
POC DL activated
NSN Internal Document 108 © Nokia Siemens Networks
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Example 1 No handover from a cell towards all its neighbours: • PLMN permitted not set properly. MML Default value is the NCC of the BTS. So HOs will not happen towards neighbours with different NCC. No Measurement reports of Cell B are sent to BSC. So no HOs occur from Cell A to Cell B
Plmn permitted 0 = No …. Plmn permitted 3 = Yes Plmn permitted 4 = No …
Cell A NCC 3
Cell B NCC 4
Set Plmn permitted 4 = Yes
Plmn permitted 7 = No
PLMN permitted parameter consists actually of 8 parameters (0 …7) related to the NCC part of the BSICs of neighbour cells. MS only reports measurements of cells with NCC permitted (plmn permitted = YES).
NSN Internal Document 109 © Nokia Siemens Networks
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Example 2 High Handover failures after implementation of new adjacency plan • All adjacencies have been implemented with synchronised parameter set to yes. HOs between cells of different sites will probably fail. Synchronized Handover MS
NETWORK ACTIVE CALL HANDO CMD HANDO ACC
x
PHYS INFO
Old Channel, Old Cell
Set SYNC = YES only between sectors of the same site. SYNC = NO
New Channel, New Cell
HANDO COM ACTIVE CALL
NSN Internal Document 110 © Nokia Siemens Networks
Recommendation is to have Sync HO within BTSs in the same BCF and Non Sync HO between BTSs in different BCFs. Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
SYNC = YES
Example 3 No handover happening from an interfered cell • hoMarginQual set to 0 A
Ho Margin Qual = -4
PBGT margin = 6dB
B Ho Margin Qual = 0 (MML Default)
In an interfered cell, despite high signal strength, quality is not good. So HO Margin Qual should permit HO to a cell that despite it’s lower signal strength, may have a better quality. NSN Internal Document 111 © Nokia Siemens Networks
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Example 4 100% of handover failures in an adjacency relation • Co-BCCH declaration (Co-BSIC)
Cell A
NSN Internal Document 112 © Nokia Siemens Networks
Cell B
F R E Q =10
F R E Q =10
BS IC = 33
BS IC = 33
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Example 5 High number of handovers. hoThresholdsLevUL = hoThresholdsLevDL Quality
0
1
hoThresholdsLevUL , high thresholds will anticipate HO s: -95 -> -100
Level Ho
2
No Action Needed
3
4
5
hoThresholdsLevDL :
Interference Ho
6
HoThresholdInterferenceUL/DL HoThresholdLevUL
NSN Internal Document 113 © Nokia Siemens Networks
HoThresholdLevDL
HoThresholdLevUL/ DL Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
-50
-52
-54
-56
-58
-60
-62
-64
-66
-68
-70
-72
-74
-76
-78
-80
-82
-84
-86
-88
-90
-92
-94
-96
-98
-100
-102
-104
-106
-108
7 -110
-95 -> -90
Quality Ho
dBm
Example 6 Handover not happening when DL signal level of neighbour much greater than serving cell • Power control DL activated
A Power Control -6dB B -3dB
NSN Internal Document 114 © Nokia Siemens Networks
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-9dB
(E)GPRS Optimization
NSN Internal Document 115 © Nokia Siemens Networks
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Objectives After PS optimization module learning • You know the impact of GSM performance on (E)GPRS performance • You know the main assessment activities • You know how the signaling, throughput and mobility can be optimized
NSN Internal Document 116 © Nokia Siemens Networks
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GSM Network as the physical layer of (E)GPRS The optimal GSM network from PSW services point of view has: 1. As high signal level as possible
It means that even the indoor signal level should be high enough to have MCS9 for getting the highest data rate on RLC/MAC layer.
2. As low interference as possible
The aim of having high C/I is to avoid throughput reduction based on interference.
3. Enough capacity
Enough BSS hardware capacity (interface and connectivity) is needed to provide the required capacity for PSW services in time. Both CSW and PSW traffic management should be harmonized with the layer structure and long term plans.
4. As few cell re-selection as possible
The dominant cell coverage is important to avoid unnecessary cell-reselections in mobility. The prudent PCU allocation can help to reduce the inter PCU cell reselections. Dominant cell structure can help to maximize the signal level and reduce the interference, too.
5. Features
All the features should be used which can improve the PSW service coverage, capacity and quality in general.
6. The GSM network is the physical layer of (E)GPRS, so the optimization of GSM network can improve the performance of (E)GPRS, too. NSN Internal Document 117 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS Optimization– TSL data rate optimization Timeslot optimization is based on basic optimization – Interference optimization – Coverage optimization RLC/MAC Data Rate (FTP Download on 2 TSLs) 120 100 80 kbps
Data rate is heavily depending on network quality • Better quality ⇒ Better throughput ⇒ Less blocking
No Interference C/I 25 dB
60
C/I 20 dB C/I 15 dB
40 20 0 -65
-70
-75
-80
-85
-90
Signal level (dBm) NSN Internal Document 118 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
-95
-100
-105
(E)GPRS Optimization – Network Element and Configuration Assessment HLR
BSS
BTS • GPRS territory
• PCU variant & dimensioning
• BTS HW considerations (TRX & BB-card)
• PCU strategy in mixed configuration
• BTS SW (EPCR)
• BSS SW and features
• QoS profile TC
TCSM
HLR/ AC/ EIR MSC/VLR
• GPRS settings
SGSN • Unit capacity (PAPU etc.) • BSS Gb Flow control
MS/Client parameters Gs
• GPRS/EDGE capability and release
IP/MPLS/IPoATM backbone GGSN
•Multislot support RF
BTS
BSC Abis
Gb
2G SGSN
Gn Gi Application Applicatio Servers n Servers (colocated
RF interface • Coverage Gb interface
•C/I • Capacity
Abis interface
• Traffic volume
• EDAP size / dimensioning
• Mobility
• Bearer size • IP v.s. FR • Dimensioning
• # of E1/T1s • GPRS/EDGE traffic NSN Internal Document 119 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Server • load • settings (Linux/Win)
(E)GPRS Optimization - Introduction (E)GPRS Network Optimization
• Signaling capacity & resource allocation improvement • Data Rate – Connectivity Capacity (MS-SGSN) – Multiplexing and multislot usage maximization
• Mobility improvement
NSN Internal Document 120 © Nokia Siemens Networks
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(E)GPRS Optimization - Signaling Capacity & Resource Allocation improvement • Signaling – PCH, AGCH, RACH and SDCCH (NMOII)
• Resource Allocation – Cell (re)-selection – BTS selection – Scheduling
NSN Internal Document 121 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS Optimization - RF Signaling Paging Measurements (NMO I) Traffic Volume • •
cs_paging_msg_sent (c3058) (CS pagings from Gb) ps_paging_msg_sent (c3057) (PS pagings from Gb)
Congestion (CS + PS) •
max_paging_gb_buf (003050)
Paging success ratio on CS •
PAC_PAG_REQ_FOR_CS_PAG (c72083) / (cs_paging_msg_sent) (c3000)
Success ratio of Paging on Gs interface (2G SGSN) sum(DL_MESSAGES_DISCARDED_IN_GS(11000)) Sgsn_961a = ----------------------------------------------------------------------- * 100 sum(CS_PAGING_MSGS + DL_TOM_MSGS)
Solution for reducing PCH rejection and load • • •
Usage of combined structure, modifying MFR and PER parameters LA/RA re-planning Cell splitting
NSN Internal Document 122 © Nokia Siemens Networks
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(E)GPRS Optimization - RF Signaling AGCH Measurements Immediate Assignment Traffic Volume (with Rejection) • imm_assgn_sent (c3001) - Imm Assign) • imm_assgn_rej (c3002) - Imm Assign Rejected • packet_immed_ass_msg (c72084) - P-Imm Assign
• packet_immed_ass_rej_msg (c72087) - P-Imm Assign Congestion blck_21b =
packet_immed_ass_nack_msg ------------------------------------------------------------------------packet_immed_ass_nack_msg + packet_immed_ass_ack_msg
Solution for reducing AGCH rejection and load • Usage of combined structure, modifying AG and CALC parameters • Immediate Assignment messages are shared between PCH and AGCH • PBCCH implementation (in case of high (E)GPRS signaling traffic)
NSN Internal Document 123 © Nokia Siemens Networks
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(E)GPRS Optimization - RF Signaling RACH Measurements Traffic Volume PACKET_CH_REQ (c072082) (PSW) CH_REQ_MSG_REC (c003004) (CSW)
Load RACH_4 = 100 * avg(ave_rach_busy(C3014)/res_acc_denom3(c3015)) avg(ave_rach_slot(c3006)/res_acc_denom1(c3007))
Repetitions of PS channel requests (load and quality) RACH_9 = UL_TBF_WITH_RETRY_BIT_SET (c072020) / PACKET_CH_REQ (c072082)
Solution for reducing RACH rejection and load • Usage of non combined structure, modifying RET parameter • PBCCH implementation (in case of high (E)GPRS signaling traffic) • Reducing high UL interference (and DL interference if the repetition is too high) NSN Internal Document 124 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS Optimization - RF Signaling SDCCH Measurements (NMO II with LA Update) Traffic Volume – SDCCH seizure attempts (c1000) – Average available SDCCH (ava_45a)
Congestion – Blocking on SDCCH, before FCS (blck_5) – Time congestion on SDCCH (cngt_2)
Solution for reducing SDCCH load – Increase of Periodic RA update timer (PRAU) / MS Reachable timer (MSRT) Drawback: more PAPU capacity is needed and more paging will be generated, if the MS is out of service
– – – –
More SDCCH TSL allocation and/or Dynamic SDCCH feature usage Combined RAU (NMO-I with Gs for (E)GPRS) (Resume feature decreases the amount of RAUs) LA and border re-planning
NSN Internal Document 125 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS Optimization - Resource Allocation Introduction RLC/MAC Basic Allocation related Topics • PSW Activation • Territory settings • Channel pref. Cell-(re)selection • C1, C2 • C31/C32 • NCCR
Provide enough capacity to PSW traffic in general (find balance between CSW and PSW)
Allocate the traffic to the most appropriate resource
BTS Selection • MultiBCF and CBCCH • PCU algorithm
Separate GPRS and EGPRS and share the resources
User Channel Scheduling • Priority based QoS
NSN Internal Document 126 © Nokia Siemens Networks
Service and user prioritization
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS Optimization– GPRS Territory • Circuit Switched traffic has priority outside dedicated territory • GPRS dedicated time slots (% of total cell capacity) can be defined. Only (E)GPRS can use, no CSW • Dedicated TSL is subset of Default TSL • Territories consists of consecutive timeslots • GPRS can be set to favour the BCCH Transceiver -> minimum interference Default GPRS capacity threshold
Extra GPRS capacity TRX 1
BCCH
TS
TS
TS
TS
TS
TS
TS
TRX 2
TS
TS
TS
TS
TS
TS
TS
TS
Free time slots in Circuit Switched territory Territory upgrade in interval of Territory Upgrade Guard Time
NSN Internal Document 127 © Nokia Siemens Networks
Default GPRS Capacity (%) Territory downgrade forced by the Circuit Switched traffic
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Dedicated GPRS Capacity (%)
Circuit Switched Territory Circuit / Packet Switched Territory
(E)GPRS – Cell (re) -Optimization selection Cell (re) - Selection
NSN Internal Document 128 © Nokia Siemens Networks
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(E)GPRS Optimization – BTS Selection and TSL Allocation BTS selection and TSL allocation is Segment Initial BTS Selection Reallocation of TBFs among the BTS 1. BTS Load reallocation 2. Uplink Rx level reallocation 3. Downlink Rx level reallocation 4. Downlink RX level received first time reallocation
NSN Internal Document 129 © Nokia Siemens Networks
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(E)GPRS Optimization – Resource Allocation - Priority based QoS TBF1 with SSS=6 TBF2 with SSS=1
1
2
127 12 7
8
Latest Service Time = Current Time + Scheduling Step Size
3
4
5
6
12
12
12
12
11
12
9
10
7
8
13 12
18 13
10 11 (time) 12
9 18 14
18 15
18 18 16
17
Latest service time
t
i 52 TDMA frames = 240 ms= 12 blocks
NSN Internal Document 130 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
t
The scheduling is done based on latest service time, one TBF at a time is served by the RTSL
i
(E)GPRS - Throughput optimization • Connectivity Capacity (MS-SGSN) • TSL data rate improvement and multislot usage maximization (BSS) • E2E data rate (applications)
NSN Internal Document 131 © Nokia Siemens Networks
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(E)GPRS Optimization Connectivity Planning – Maximized Capacity • The connectivity optimization for maximum capacity is based on the proper set of CDEF and DAP size. • To provide enough capacity for territory upgrade the 75 % utilization in the connectivity limits is recommended by NSN • PCU Connectivity capacity limits can be seen below Outputs Abis channles (radio TSLs) EDAP pools BTS (cell, segment) TRXs
Max limit* 256 16 64 128
Utilization 75% 75% 75% 75%
*PCU & PCU-S handle 128 radio TSLs only with S11.5 *PBCCH is not implemented
NSN Internal Document 132 © Nokia Siemens Networks
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Limit 192 12 48 96
unit TSLs pcs pcs pcs
(E)GPRS Optimization Connectivity in different PCUs PCU variant PCU
PCU-S
BTS
64
64
TRX Radio TSLs Abis 16 kbps channels Gb 64 kbps channels BTS
128 256 256 31 64
128 128 256 31 64
TRX Radio TSLs Abis 16 kbps channels Gb 64 kbps channels BTS TRX Radio TSLs Abis 16 kbps channels Gb 64 kbps channels BTS TRX Radio TSLs Abis 16 kbps channels Gb 64 kbps channels BTS TRX Radio TSLs Abis 16 kbps channels Gb 64 kbps channels BTS TRX Radio TSLs Abis 16 kbps channels Gb 64 kbps channels
128 256 256 31 64 128 256 256 31 N/A N/A N/A N/A N/A 2 x 64 2 x 128 2 x 256 2 x 256 2 x 31 N/A N/A N/A N/A N/A
128 128 256 31 64 128 256 256 31 128 256 256 256 31 2 x 64 2 x 128 2 x 256 2 x 256 2 x 31 2 x 128 2 x 256 2 x 256 2 x 256 2 x 31
BSC Type BSCE, BSC2, BSCi, BSC2i
BSCE, BSC2, BSCi, BSC2i
PCU-T
BSCE, BSC2, BSCi, BSC2i
PCU2-U
BSCE, BSC2, BSCi, BSC2i
PCU-B
BSC3i
PCU2-D
BSC3i
NSN Internal Document 133 © Nokia Siemens Networks
BSS11
BSS11.5 ownwards
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(E)GPRS Optimization Connectivity Planning – Cells / PCU The following configuration types were defined:
The following table shows the number of EGPRS cell / PCU calculations for the different configuration types. EGPRS BSS Configuration Portfolio (ETSI)
extra small (XS)
Extra small Small Medium Large Extra large Data monster
small (S)
lowest cost per EGPRS cell: maximize low cost: high EGPRS cells EGPRS cells per per PCU PCU ratio
Use case
Parameters CDEF DAP
medium (M)
(CDEF→1 RTSL, DAP → 3 TSL) (CDEF → 2 RTSL, DAP → 4 TSL) (CDEF → 4 RTSL, DAP → 6 TSL) (CDEF → 4 RTSL, DAP → 8 TSL) (CDEF → 4 RTSL, DAP → 11 TSL) (CDEF → 4 RTSL, DAP → 16 TSL) large (L)
High data volume Basic EGPRS site EGPRS site
extra large (XL)
Extra high data volume site
data monster monster Data (DM) (DM)
Data hot spot site)
Data hot spot site
1 3
2 4
4 6
4 8
4 11
4 16
# of cells / PCU with utilization cells per DAP #DAPs per PCU #EGPRS cells per PCU PCU Abis ch utilization average cells per DAP #DAPs per PCU #EGPRS cells per PCU PCU Abis ch utilization cells per DAP #DAPs per PCU #EGPRS cells per PCU PCU Abis ch utilization
2 16 32 88% 2.5 15 37 85% 3 15 45 88%
2 11 22 86% 2.5 10 25 82% 3 10 30 86%
2 7 14 88% 2.5 6 15 80% 3 6 18 84%
2 5 10 78% 2.5 5 12 81% 3 5 15 86%
2 4 8 81% 2.5 4 10 84% 3 4 12 88%
2 3 6 84% 2.5 3 7 86% 3 3 9 89%
Performance figures (kbps) (n+n+n) single user peak RLC/MAC (#RTSL in DL) cell peak RLC/MAC (gross)
186 354
237 325
237 597
237 748
237 829
NSN Internal Document 134 © Nokia Siemens Networks notes fo applying
237 373 areas for medium areas for low+ EGPRS traffic, area for low supports 4 & 5 EGPRS traffic, EGPRS traffic, no support 4 RTSL RTSL MS 2010 @ VFmax RoB Advance Network Optimization/JP/NNPO/ 1st to 3rd July performance MS FTP max FTP/HTTP commitments throughput throughput
Hot spot site areas for high EGPRS traffic
areas for extra hot spot site for For EGPRS high EGPRS traffic EGPRS
(E)GPRS Optimization - KPIs • DL MCS selection limited by EDAP (dap_7a) – Similar formula for DL (dap_8c)
Target values: Good: < 75 min/GByte Bad: > 150 min/GByte
– DL_TBFS_WITH_INADEQ_EDAP_RES (c076008) c76008 includes lack of PCU resources (c76020
DL_MCS_LIMITED_BY_PCU ) as one reason. If c76008 is updated but peak EDAP usage is less than 100%, reason is that c76008 has been updated because of lacking PCU resources,
NSN Internal Document 135 © Nokia Siemens Networks
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(E)GPRS Optimization - KPIs • DL MCS selection limited by PCU (dap_9) – Similar formula for UL ( dap_10)
Target values: Good: < 15 min/GByte Bad: > 30 min/GByte
NSN Internal Document 136 © Nokia Siemens Networks
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(E)GPRS Optimization - Multiplexing Channel Allocation Algorithm tends to separate EDGE TBFs and GPRS TBFs on different RTSL to avoid multiplexing, if only one PS Territory exists in the cell or there is high load. • UL GPRS USF on DL EGPRS TBF • TSL sharing - GPRS/EGPRS TBFs’ multiplexing on a TSL The algorithm checks the need for re-allocation every TBF_LOAD_GUARD_THRSHLD, in order to separate sessions. The max amount of TBFs per TSL can be limited:
Parameter Name
Abbreviation
Description
Maximum Number of DL TBF
MNDL
maximum number of TBFs that a radio time slot can have in average, in a GPRS territory, in the downlink direction.
1..9, default:9
Maximum Number of UL TBF
MNUL
maximum number of TBFs that a radio time slot can have in average, in a GPRS territory, in the uplink direction.
1..7, default:7
NSN Internal Document 137 © Nokia Siemens Networks
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Range and Default
(E)GPRS Optimization – Multiplexing – Measurements (KPIs) Amount of TBFs / TSL Uplink TBFs pr timeslot tbf_37d Downlink TBFs pr timeslot tbf_38d GPRS TBF multiplexed with EGPRS TBF 8PSK coding scheme downgrade due to GPRS multiplexing rlc_61 DL EDGE TBFs in GPRS territory tbf_60 UL EDGE TBFs in GPRS territory tbf_59 Ratio of DL GPRS TBFs in EDGE territory tbf_58a Ratio of UL GPRS TBFs in EDGE territory tbf_57a
NSN Internal Document 138 © Nokia Siemens Networks
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(E)GPRS Optimization - Multislot usage Territory Downgrade and Upgrade The territory downgrade heavily depends on the size of dedicated and default territory. • Territory downgrade due to CSW traffic rise •
•
Territory downgrade due to less PSW traffic •
•
Downgrade request below Default territory because of rising CSW (c1179) Downgrade request back to the Default territory when there is no need for additional channels anymore (c1181)
Territory upgrade request rejection beyond default territory •
Upgrade request beyond Default territory for additional resources (c1174), which can be rejected because of: 1. 2. 3.
No (E)GPRS capable resource left (No (E)GPRS enable TRX or the maximum (E)GPRS capacity reached) PCU and EDAP capacity limitation (256 Abis TSL per PCU) High CSW load Default territory
0
1
2
3
1174
4
5 1179
1181 1180
NSN Internal Document 139 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
6
7
(E)GPRS Optimization Free TSL Size (after CS Upgrade and Downgrade) When a downgrade or upgrade procedure is requested following parameters can reduce or increase the border between CSW and PSW territories:
TSL number after CS downgrade TRX number
free TSL for CS downgrade (%) (CSD)
70 95 99
1
2
3
4
5
0
0
0
1
1
1
1
1
2
2
1
1
2
2
3
1 0
2 1
3 1
4 1
5 2
1
2
2
3
4
1
2
3
4
5
2
3
4
5
6
TSL number after CS upgrade TRX number
free TSL for CS upgrade (sec) (CSU)
NSN Internal Document 140 © Nokia Siemens Networks
1 4 7 10
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
(E)GPRS Optimization Multislot Usage – Measurements (KPIs) Actual Territory • ava_44 • Peak PS territory (c2063) Recommendation: Ava_44 and c2063 can be compared with the CDEF settings. If too big difference, then CDEF should perhaps be changed, or more capacity should be added to the cell.
Multislot Blocking • UL / DL multislot allocation blocking – hard (tbf_15a, tbf_16a) • DL multislot blocking – soft (blck_33a) Recommendation: Too much multislot blocking shows that the territory is perhaps not enough. And it is also interesting to see how many timeslots which are requested (helpful in determining the size of the default territories) • Requested timeslots for GPRS TBFs c72039-c72149, c72040-c72150, c72041c72151, c72042-c72152 • Requested timeslots for EDGE TBFs c72149, c72150, c72151, c72152 NSN Internal Document 141 © Nokia Siemens Networks
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(E)GPRS Optimization - Mobility Optimization The aim of mobility optimization is to reduce the cell outage time during cell re-selection. Cell outage can be reduced by • Providing enough signaling capacity for cell re-selection (the RACH, PCH, AGCH and SDCCH channel are not limiting the signaling flow) • Rebalancing BCFs among PCUs properly (the important neighbors are allocated to the same PCU) • Reallocating LA/RA borders properly • Enabling Network Assisted Cell Change (NACC) feature
NSN Internal Document 142 © Nokia Siemens Networks
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(E)GPRS Optimization – Outage Definition Used in Measurements Three delays can be calculated from logs: GERAN
MS
Cell outage: • In one-phase access: the time
between the last EGPRS Packet Downlink Ack/Nack message and the first Packet Uplink Ack/Nack. • In two-phase access: the time between the last EGPRS Packet Downlink Ack/Nack message and the first Packet Uplink Assignment.
Data outage:
Last IP packets E G PR S Packet Downlink Ack/Nack R outing Area Update R equest
Data Outage
Packet Uplink Assignment R outing Area Update Accept R outing Area Update C omplete
the time between the last and the first EGPRS Packet Downlink Ack/Nack message.
E G PR S Packet Downlink Ack/Nack
Application outage: the time between the last and the first successfully received FTPpacket. NSN Internal Document 143 © Nokia Siemens Networks
Application Outage
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
F irst IP packets
Cell Outage
(E)GPRS Optimization Network Assisted Cell Change (NACC) NACC is in Rel 4 of 3GPP GERAN , mandatory for R4 mobiles. Nokia’s S11.5 implementation is based on Rel4. Both, autonomous and network controlled cell reselections are supported. Support is for intra-BSC cell changes (Support of inter-BSC NACC specification is available in Rel 5) NACC support is for MSs in RR Packet Transfer Mode only
NACC shortens the cell reselection in two ways: •
Sending neighbour cell system information on PACCH to MS in packet transfer mode while it is camped on the serving cell
•
By supporting PACKET SI STATUS procedure in a target cell
NSN Internal Document 144 © Nokia Siemens Networks
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(E)GPRS Optimization– CS Traffic vs. PS Traffic
CS and PS peak values at the same time (BSC level data) ⇒ Bad for PS timeslot allocation ⇒ Lots of downgrading
Exercise How to optimize PS performance on area level?
NSN Internal Document 145 © Nokia Siemens Networks
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Alarms
NSN Internal Document 146 © Nokia Siemens Networks
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Alarms - Introduction Alarm analysis is the 1st thing to be done in worst cell troubleshooting! No use optimizing parameters if you have a HW problem! Bad performance of a cell may be caused by faulty equipment. • Check that there are no performance-affecting alarms in the cell monitored and also in neighbour cells! • Alarms are usually transferred to the NetAct database. • Monitoring can be done through MML Commands, Nokia NetAct Top Level User Interface
Note! Constant monitoring is needed in order to avoid critical alarms in any network element.
NSN Internal Document 147 © Nokia Siemens Networks
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Alarms – Groups
Alarm number in:
Notices (NOT ICE)
Disturbance Failure printouts printouts (DIST UR) (ALARMS)
switching equipment 0–799
1000–1799
O&M equipment
800 - 899
1800–1899
900 - 999
1900–1999
transmission equipment diagnosis report number base station/ transmission equipment alarms
Diagnosis reports (DIAGN)
Base station alarms
Numbers T ransmission reserved for equipment possible alarms external alarms
2000–2799 3000–3799 2800–2899 3800–3899 2900–2999 3900–3999
4000–4799 4800–4899 4900–4999 3700–3999 7000–7999
8000–8999
power equipment
5000–5499
external equipment
5500–5999
NSN Internal Document 148 © Nokia Siemens Networks
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Alarms – Printout Fields • Alarm Number • BCF number, BTS number, TRX number, Alarm Object, Unit, Date, Time, Alarm Number • Urgency level
Note:
* L ow Priority ** Med Priority *** High Priority
• Printout type ALARM fault situation CANCEL fault terminated DISTUR disturbance NOTICE notice
The urgency level is output in all alarm printouts except notices (NOTICE). The urgency levels of terminated alarms are indicated by dots (.) instead of asterisks (*).
• Event type COMM communication failure QUAL quality of service PROCES processing failure EQUIPM equipment failure ENVIR environmental failure NSN Internal Document 149 © Nokia Siemens Networks
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Alarms - Alarms in MML Alarms in BSC Level: – ZAHO: PRINT ALARMS CURRENTLY ON – ZAHP: PRINT ALARM HISTORY
Alarms in BTS Level: – ZEOL: LIST ALARMS CURRENTLY ON – ZEOH: LIST ALARM HISTORY
Verify if BCF, SEG, BTS, TRX and RTSL are LOCKED or UNLOCKED; WO (working), BL- USR (blocked by user) or Restarting.
BCF, SEG or BTS configuration and status – ZEEI: OUTPUT RADIO NETWORK CONFIGURATION
TRX and RTSL configuration and status – ZERO: OUTPUT TRANSCEIVER PARAMETERS
NSN Internal Document 150 © Nokia Siemens Networks
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Alarms - Alarms in MML HW Tests: • ZUBK: HANDLE ABIS LOOP TEST (Parameters: BTS, TRX, RTSL, Fixed or Dynamic Abis connection and Abis TSL and Sub-TSL, looping time)
• ZUBS: START TRANSCEIVER TEST (Parameters: BTS, TRX, RTSL, test mode, RTSL,test selection, diversity path selection,test connection, RF test signal attenuation,BTS RX level,STM antenna attenuation,BS TX power attenuation, loop duration)
NSN Internal Document 151 © Nokia Siemens Networks
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Alarms - Examples • 2993: BTS AND TC UNSYNCHRONIZATION CLEAR CALLS ON ABIS INTERFACE – Transcoder and transmission alarm. Abis test is needed.
• 7045: TRX/FU DATA TRANSFER ERROR BETWEEN FU AND CU16 – Base Station alarm. Observed when TCH failure rate is very high. A possible solution can be to change the TRX.
• Example of a BTS alarm printout:
NSN Internal Document 152 © Nokia Siemens Networks
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Alarms - Top Level User interface • The Top-level User Interface contains graphical views of the network, in which network elements are represented hierarchically with symbols • One of the main functions of the Top-level User Interface in network monitoring is to show the alarm situation in all managed objects
NSN Internal Document 153 © Nokia Siemens Networks
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Implementation / Documentation
NSN Internal Document 154 © Nokia Siemens Networks
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Implementation / Documentation • Optimization process is an iterative process, so there is no need to create troublesome final report after every circle. Main items must be still written down after every circle.
• All the activities/ findings should be listed – What should be done and when – “recommendation for the changes to be done" and "working orders".
• All improvements should be shown – Implementation time should be shown with improvements
NSN Internal Document 155 © Nokia Siemens Networks
Network Report Tasks And Results
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Solution Verification
NSN Internal Document 156 © Nokia Siemens Networks
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Solution Verification • The purpose is to check was solution succeed – Is the trend positive or negative after aimplementations – Check that collected data is valid EGPRS RLC Throughput kbit/s/TSL BSC KRASNODAR 60
50
• Parameter changes were done 20.11 • Throughput after changes was improved
30
20
DL 10
UL
.
.
12 4.
1.
12 2.
.1 30
.1
1.
1. 28
1.
.1 26
24
.1
1.
1.
.1 22
.1 20
18
.1
1.
1.
1.
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NSN Internal Document 157 © Nokia Siemens Networks
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Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Monitoring
NSN Internal Document 158 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Monitoring – Introduction The basic idea to monitor network is to see how the optimization project is ongoing and how the network is performing • KPI monitoring • Testing & post processing • Alarm monitoring • Schedule monitoring • Investments checking • Resource monitoring
NSN Internal Document 159 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Monitoring – Reporting Suite
• Before Reporting Suite can be started, connection to NetAct must be done • Reporting Suite can be used for KPI monitoring
NSN Internal Document 160 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Monitoring – Reporting Suite
• Different KPI group can be seen here • Example of final KPI report
NSN Internal Document 161 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Tools to be used
NSN Internal Document 162 © Nokia Siemens Networks
Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Tools to be used
Example of tools to be used in Solution finding Statistics (Reporting Suite, Metrica etc.)
Performance optimization Traffic and Capacity optimization Coverage Optimization Frequency Optimization Neighbor Optimization HO Optimization (E)GPRS Optimization
NSN Internal Document 163 © Nokia Siemens Networks
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Planning tools (NetAct Planner, Asset etc)
Configuration tools (Plan Editor, RAC tools, etc)
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Advance Network Optimization/JP/NNPO/ 1st to 3rd July 2010 @ VF RoB
Optimizer
Drive test tools (Nemo Outdoor. TEMS, Actix etc)
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