Telcel Nokia Siemens Networks
Short Description
Descripción: Telcel Nokia Siemens Networks...
Description
3G RAN Capacity Management workshop Telcel, Mexico City, March 2009 Poul Larsen
Telcel – Nokia Siemens Networks confidential 1 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Agenda
• What is capacity management and why is it needed? • Brief introduction to RAS06 performance monitoring • How to monitor – Air Interface – BTS – Iub – RNC – Iu-CS, Iu-PS, Iur
Not covered: - HSUPA - Advanced Iub configurations - Core network - IP BB - Etc.
Telcel – Nokia Siemens Networks confidential 2 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
What is capacity management and why is it needed?
Telcel – Nokia Siemens Networks confidential 3 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Traffic volumes going up 10 TB/day
5 TB/day
“Worst case”: from 5 TB to 10 TB in 4 months Telcel – Nokia Siemens Networks confidential 4 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Traffic volumes going up HSDPA Subs: • 1Q08: 34,000 • 2Q08: 75,000 • = +119% in 3 mths WCDMA total in 2Q08: • 1.9 M with 33% quarterly growth => Where will the quality of Mobile BB service go without well planned capacity expansion? ~20x traffic growth in only 9 months
Even with sufficient network capacity today, there could be serious congestion within a few months • Does the operator know the situation today? • Does the operator know how to monitor all the possible capacity bottlenecks? • Does the operator have long-term strategies for how to expand capacity?
Telcel – Nokia Siemens Networks confidential 5 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Badly timed capacity upgrade – case example 14000000
2800000
HS-DSCH selections/RNC_614A
HSDPA data volume (MAC-d) at Iub/RNC_608A
HSDPA Subscriber growth
12000000
2400000
..
From 62% market share to 25% in 1 year
i gn
Our case Competitor 1 Competitor 2
8000000
Source: Informa October 15, 2008 1Q07
2Q07
1Q08
2Q08
6000000
g ts p m
4000000
2000000
e nn o C
io ct
n
a
oi
ng
up
e wh
n
n
ew
su
bs
ib cr
s
er
n,
2000000
si
1600000
1200000
HS-DSCH Selections
Data Volume (Mbits)
10000000
t bu
Capacity bottlenecks found 800000 and necessary upgrades done -> normal growth again
tte
...overall data volume is not growing -> end users have s l o w e r services
0
04
/1 0 09 /20 /1 06 0 14 /20 /1 06 0 19 /20 /1 06 0 24 /20 /1 06 0 29 /20 /1 06 0 03 /20 /1 06 1 08 /20 /1 06 1 13 /20 /1 06 1 18 /20 /1 06 1 23 /20 /1 06 1 28 /20 /1 06 1 03 /20 /1 06 2 08 /20 /1 06 2 13 /20 /1 06 2 18 /20 /1 06 2 23 /20 /1 06 2 28 /20 /1 06 2 02 /20 /0 06 1/ 07 20 /0 07 1 12 /20 /0 07 1 17 /20 /0 07 1 22 /20 /0 07 1 27 /20 /0 07 1 01 /20 /0 07 2 06 /20 /0 07 2 11 /20 /0 07 2 16 /20 /0 07 2 21 /20 /0 07 2 26 /20 /0 07 2 03 /20 /0 07 3 08 /20 /0 07 3 13 /20 /0 07 3 18 /20 /0 07 3 23 /20 /0 07 3 28 /20 /0 07 3 02 /20 /0 07 4 06 /20 /0 07 4 11 /20 /0 07 4 16 /20 /0 07 4/ 21 20 /0 07 4 26 /20 /0 07 4 01 /20 /0 07 5 06 /20 /0 07 5 11 /20 /0 07 5 16 /20 /0 07 5/ 20 07
0
400000
This operator lost the Mobile Broadband business leading position and 36% of data revenues in 2 yrs monitoring period Telcel – Nokia Siemens Networks confidential 6 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Why capacity management is needed • Identify real bottlenecks in the network and address most serious issues first, keeping in mind that the network is a system • Ensure efficient utilization of existing capacity • Employ new features in the most efficient way • Identify areas where capacity expansion is needed
Telcel – Nokia Siemens Networks confidential 7 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Identify bottlenecks in the network • The entire RAN
Telcel – Nokia Siemens Networks confidential 8 © Nokia Siemens Networks
UE
IuCS Interface User Plane User Plane
AIR Interface
CE Resource
PRACH FACH-c&u PCH DCH
Scheduling capacity
SS7 (RANAP)
IuB Interface Throughput CNBAP
Connectivity
IuPS Interface
DNBAP AAL2SIG User Plane
Unit Load DSP Usage
User Plane SS7 (RANAP)
Code Capacity User Plane
network needs to be analysed • If e.g. the DSP capacity is reached, it doesn't help to add more carriers! • Packet Core, IP backbone etc. should not be forgotten
RNC
WBTS
3G RAN Capacity / Poul Larsen / March 2009
Iur Interface
Ensure efficient utilization of existing resources • Network resources are not always used in the most efficient manner, so before investing in more resources, the utilization of existing resources should be optimised UL return channel utilization 40% 35% 30% 25% 20% 15% 10% 5% 0% 1 week
• For example, shortage of UL channel elements or UL Iub capacity can be caused by bad utilization of the UL radio bearer • Rather than installing more capacity, features such as "Throughput Based Optimization" or “16 kbps UL return channel” should be used
Telcel – Nokia Siemens Networks confidential 9 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Employ new features in most efficient way • Activating new features are often associated with increased cost for the operator, either directly in terms of license fees or indirectly e.g. if more channel elements are needed • In such cases, the features should only be activated where a performance gain can be expected Average DL Iub utilization
Ratio of empty TTIs 100%
70% 60%
80%
50%
60% 40%
40%
30% 20%
20%
10%
0%
0%
5 days
• In the above example, activating the "HSDPA shared scheduler for basedband efficiency" will increase the air interface capacity dramatically, but that doesn't help so much if the Iub instead becomes the bottleneck
Telcel – Nokia Siemens Networks confidential 10 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Identify areas where capacity expansion is needed • • • • •
Eventually, capacity expansions will be needed Necessary to prioritise sites with regular usage rather than the occasional traffic peak KPI definitions and thresholds needed Tools and processes to be established Decide if all the requested traffic needs to be carried
Telcel – Nokia Siemens Networks confidential 11 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
99% of the downlink traffic is HSDPA), and it can therefore be expected that the utilization (the "Activity Factor") of the UL R99 radio channels is small The RNC does not take the activity factor into account when estimating the load, this has to be done manually in the postprocessing The activity factor from one LAM network has been estimated to 20% by comparing the duration counters in M1002 with the payload counters in M1017 The difference between the fractional load provided by the counters (assuming 100% activity factor) and the real fractional load assuming a 20% activity factor is shown in the table
L fractional =
ρR ρR + W
Where: •ρ is the received Eb/No •R is the service bit rate •W is 3.84 Mbps
Telcel – Nokia Siemens Networks confidential 42 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M1000C24 M1000C25 M1000C26 M1000C27 M1000C28 M1000C29 M1000C30 M1000C31 M1000C32 M1000C33 M1000C34 M1000C35 M1000C36 M1000C37 M1000C38 M1000C39 M1000C40 M1000C41 M1000C42 M1000C43
AVE_LRT_CLASS_0 LRT_DENOM_0 AVE_LRT_CLASS_1 LRT_DENOM_1 AVE_LRT_CLASS_2 LRT_DENOM_2 AVE_LRT_CLASS_3 LRT_DENOM_3 AVE_LRT_CLASS_4 LRT_DENOM_4 AVE_LNRT_CLASS_0 LNRT_DENOM_0 AVE_LNRT_CLASS_1 LNRT_DENOM_1 AVE_LNRT_CLASS_2 LNRT_DENOM_2 AVE_LNRT_CLASS_3 LNRT_DENOM_3 AVE_LNRT_CLASS_4 LNRT_DENOM_4
Load Actual load provided by assuming AF counters of 20% 11.4% 2.5% 20.8% 5.0% 28.8% 7.5% 35.7% 10.0% 41.7% 12.5% 46.9% 15.0% 51.5% 17.5% 55.6% 20.0% 59.2% 22.5% 62.5% 25.0% 65.5% 27.5% 68.2% 30.0% 70.7% 32.5% 72.9% 35.0% 75.0% 37.5% 76.9% 40.0% 78.7% 42.5% 80.4% 45.0% 81.9% 47.5% 83.3% 50.0% 84.7% 52.5% 85.9% 55.0% 87.1% 57.5% 88.2% 60.0% 89.3% 62.5% 90.3% 65.0% 91.2% 67.5% 92.1% 70.0% 92.9% 72.5% 93.8% 75.0% 94.5% 77.5% 95.2% 80.0% 95.9% 82.5% 96.6% 85.0% 97.2% 87.5% 97.8% 90.0% 98.4% 92.5% 99.0% 95.0% 99.5% 97.5%
Noise Rise vs Load Estimation Load based on noise rise, 20:00 - 21:00
Load estimation incl. AF, 20:00 - 21:00
60%
100%
50%
80% 60%
30%
10%
100%
80%
40%
20%
90%
40%
70% 60% 50% 40%
80% 60% 40%
30% 20%
20%
20%
10% 0%
0%
0%
0%
• If the noise rise triggers an investigation, the "load estimation" KPI can be a way to check if the noise rise is caused by traffic or by something else
Telcel – Nokia Siemens Networks confidential 43 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Radio interface KPIs – DL Code reservation A single downlink scrambling code supports an OVSF code tree containing 1020 codes (based upon spreading factors from 4 to 512) SF = 1 SF = 2 SF = 4 SF = 8 SF = 16
Codes for 5 HS-PDSCH's
SF = 32 SF = 64 SF = 128
Code for one HS-SCCH
SF = 256
Codes for the cell common channels
4 codes (SF 128) reserved for the common channels without HSDPA At least 45 codes (SF 128) reserved for the common channels and HSDPA ⇒ Introduction of HSDPA increase possibility of code blocking ⇒ Codes are reserved for HSDPA always when HSDPA is enabled in the cell Telcel – Nokia Siemens Networks confidential 44 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Radio interface KPIs - DL Code reservation •
Code tree occupancy KPI can be used for code blocking. KPI provides an indication of the percentage of codes which are either used or blocked. Channelisation codes assigned to both the common and dedicated downlink channels are included for the KPI
RNC _ 113 a _ Code _ Tree _ occupancy =
sum (CODE _ CAPACITY ) sum (DENOM _ CODE _ CAPACITY
)
x100 [%]
• •
Both counters are updated every 1 s Also counters for min and max occupancy
•
Code Blocking KPI formula could be calculated from counters which are triggered when no codes of SF X (X=4,8,… 256) are available and from counter which is incremented when the code is successfully allocated 256
Code _ Blocking =
∑ NO _ CODES _ AVAILABLE _ SFx x=4
256
NBR _ SUCC _ CODE _ TREE _ ALLO + ∑ NO _ CODES _ AVAILABLE _ SFx
× 100[% ]
x =4
• Code blocking pr spreading factor, e.g. for SF128: NO_CODES_AVAILABLE_SF128 / CHAN_CODE_SF128_REQUEST
Note: These counters are triggered by initial RB setup as well as RB reconfiguration! Telcel – Nokia Siemens Networks confidential 45 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Low HS-DSCH accessibility leads to DL code blocking (more details in the BTS section) 90% 80% 70% 60%
100% 80% 60%
50% 40%
40%
30% 20%
20%
10% 0%
0%
Cells
Requests for DL spreading codes, BTS x
HS-DSCH accessibility, BTS x
Max code blocking, w37
Oct 6 - Oct 19
Max users Iub 384 kbps Iub 128 kbps Iub 64 kbps Iub 16 kbps BTS UE DL Iub RNC AC (UL) Success
70000 60000 50000
30000 20000 10000 0 Oct 6 - Oct 19
Code reservations, BTS x
• Low HS-DSCH accessibility in the site meant that many UEs had to use R99 channels, and this lead to spreading code congestion • Shared HSDPA Scheduler introduced on Oct 13 improved HSDSCH accessibility and therefore less R99 channels were needed • Despite the use of 10 codes for HS-DSCH, overall code blocking almost disappeared => Better to push traffic to HS-DSCH than start to worry about code blocking
CHAN_CODE_SF256_REQUEST CHAN_CODE_SF128_REQUEST CHAN_CODE_SF64_REQUEST CHAN_CODE_SF32_REQUEST CHAN_CODE_SF16_REQUEST CHAN_CODE_SF8_REQUEST
40000
100% 80% NO_CODES_AVAILABLE_SF256 NO_CODES_AVAILABLE_SF128 NO_CODES_AVAILABLE_SF64 NO_CODES_AVAILABLE_SF32 NO_CODES_AVAILABLE_SF16 NO_CODES_AVAILABLE_SF8 NBR_SUCC_CODE_TREE_ALLO
60% 40% 20% 0% Oct 6 - Oct 19
HS-DSCH code availability, BTS x 100% 80%
DURA_HSDPA_10_CODE DURA_HSDPA_9_CODE
60%
DURA_HSDPA_8_CODE DURA_HSDPA_7_CODE
40%
DURA_HSDPA_6_CODE DURA_HSDPA_5_CODE
20% 0%
Telcel – Nokia Siemens Networks confidential 46 © Nokia Siemens Networks
Oct 6 - Oct 19
3G RAN Capacity / Poul Larsen / March 2009
Setup failures due to Admission Control • Admission Control rejects the establishment of a new RRC connection • Due to – UL power – DL power – DL codes • Formula: RRC_CONN_STP_FAIL_AC / RRC_CONN_STP_ATT
RRC setup failures due to AC 0.0750%
0.08% 0.07% 0.06% 0.05% 0.04% 0.03% 0.02% 0.01%
0.0059% 0.0004%
0.00% Network 1
Telcel – Nokia Siemens Networks confidential 47 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Network 2
Network 3
Setup failures due to Admission Control • Admission Control rejects the establishment of a new voice RAB connection • Due to – UL power – DL power – DL codes • Formula: RAB_STP_FAIL_CS_VOICE_AC / RAB_STP_ATT_CS_VOICE
Voice RAB setup failures due to AC 0.0040% 0.0034%
0.0035% 0.0030% 0.0025% 0.0020% 0.0015%
0.0014%
0.0010% 0.0005%
0.0000%
0.0000% Network 1 Telcel – Nokia Siemens Networks confidential 48 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Network 2
Network 3
Setup failures due to Admission Control • Admission Control rejects the establishment of a new HS-DSCH connection (the UL return channel is rejected) • Due to – UL power • Formula: REJ_HS_DSCH_RET_INT + REJ_HS_DSCH_RET_BGR -------------------------------------------------------------------------------------------------------------------------------------------------------ALLO_HS_DSCH_FLOW_INT + ALLO_HS_DSCH_FLOW_BGR + DCH_SEL_MAX_HSDPA_USERS_INT DCH_SEL_MAX_HSDPA_USERS_BGR + REJ_HS_DSCH_RET_INT + REJ_HS_DSCH_RET_BGR SETUP_FAIL_RNC_HS_DSCH_INT + SETUP_FAIL_IUB_HS_TOTAL_INT + SETUP_FAIL_UE_HS_DSCH_INT SETUP_FAIL_BTS_HS_DSCH_INT + SETUP_FAIL_RNC_HS_DSCH_BGR + SETUP_FAIL_IUB_HS_TOTAL_BGR SETUP_FAIL_UE_HS_DSCH_BGR + SETUP_FAIL_BTS_HS_DSCH_BGR
HS-DSCH setup failures due to AC 1.8%
1.6355%
1.6% 1.4% 1.2% 1.0% 0.8% 0.6% 0.4% 0.2%
0.0496%
0.0021%
0.0% Network 1 Telcel – Nokia Siemens Networks confidential 49 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Network 2
Network 3
Setup failures due to Admission Control • Admission Control rejects the establishment of a new PS radio bearer • Request may be for HSUPA, HSDPA or R99. Outcome is nothing • Due to – UL power – DL power – DL codes – Too many users in scheduler • Formula: PS_SETUP_FAIL_AC_INT + PS_SETUP_FAIL_AC_BGR ----------------------------------------------------------------------------------------------------------------------------------------PS_ATT_HSDSCH_EDCH_INT + PS_ATT_HSDSCH_EDCH_BGR + PS_ATT_HSDSCH_DCH_INT PS_ATT_HSDSCH_DCH_BGR + PS_ATT_DCH_DCH_INT + PS_ATT_DCH_DCH_BGR PS setup failures due to AC 8%
9% 8% 7% 6% 5% 4% 3% 2% 1% 0% Network 1 Telcel – Nokia Siemens Networks confidential 50 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Network 2
Network 3
Air interface - HS-DSCH
Telcel – Nokia Siemens Networks confidential 51 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
HSDPA considerations • Whenever HSDPA is used, the maximum available power for HSDPA will be used (in RAS06, RU10 will have power control for HS-DSCH) • This means that a KPI like "Average used HSDPA power" is a bit meaningless • Instead the following methods can be used – TTI (Transmission Time Interval) utilization: Tells if the traffic is so high that the available cell capacity is being used in the time domain – CQI: Tells about the DL radio link quality and therefore how much payload that potentially can be transmitted in a TTI – HSDPA Cell throughput: Tells how payload there actually is transmitted in a TTI
Telcel – Nokia Siemens Networks confidential 52 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
TTI utilization • During 1 hour, there are 500 * 3600 = 1800000 TTIs (Transmission Time Intervals) available for each carrier • Number of used TTIs: HS_SCCH_PWR_DIST_CLASS_0 + HS_SCCH_PWR_DIST_CLASS_1 + HS_SCCH_PWR_DIST_CLASS_2 + HS_SCCH_PWR_DIST_CLASS_3 + HS_SCCH_PWR_DIST_CLASS_4 + HS_SCCH_PWR_DIST_CLASS_5
Telcel – Nokia Siemens Networks confidential 53 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
TTI utilization Max TTI utilization, RNC2, Sep 1 - Sep 7
In case of high TTI utilization: • Increase available TTIs – New carrier – New sector – New site
1800000 1600000 1400000 1200000 1000000 800000 600000 400000 200000 0
• Use existing TTIs more
Cells
efficiently
Used TTIs, cell x
– 10/15 codes – Code multiplexing – Improve CQI – Remove other bottlenecks, e.g. Iub or HLR restrictions, such that the transport blocks can be filled up Telcel – Nokia Siemens Networks confidential 54 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
1800000 1600000 1400000 1200000 1000000 800000 600000 400000 200000 0 Sep 1 - Sep 14
CQI mapping (Cat 7/8) (NSN implementation) • CQI in table is "compensated" CQI • TTI duration is 2 ms, so 500 TTIs pr second • Physical layer throughput is roughly TB size * 500 • DIfference between measured and compensated CQI is ~2 to 3 dB in RAS06 • Depends also on UE capability (equalizer, 2 receivers)
Telcel – Nokia Siemens Networks confidential 55 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Q
Q I_
I_ D
C
Q
D
IS
T_ IS C L I_ T _ C D I _ C 0 (H Q S L_ s I_ T d C D I _C 1 (H pa Q S L_ s w T I_ d ) C D I _C 2 (H pa Q S T L_ s w I_ d ) C D I _C 3 (H pa Q S L_ s w I_ T d ) C D I _ C 4 (H pa Q S T L_ s w I_ d ) C D I _C 5 (H pa Q S L_ s w I_ T d ) C D I _ C 6 (H pa Q S L_ s w C I_D T _C 7 dp ) Q I_ IS L (H aw C D I T _C _8 sdp ) Q S T L (H a I_ s w C D I _C _9 dp ) Q S L_ (H aw I_ T s C D I _ C 10 ( dp ) Q S T L_ H aw I_ s C D I _C 1 1 dp ) Q S L_ (H aw I_ T s C D I _ C 12 ( dp ) Q S L_ H aw I_ T s C D I _C 1 3 dp ) Q S L_ (H aw I_ T s C D I _C 1 4 dp ) Q S T L_ (H aw I_ s C D I _C 15 dp ) Q S L_ (H aw I_ T _ 1 s C D I C 6 ( dp ) Q S L_ H aw I_ T s C D I _C 1 7 dp ) Q S L_ (H aw I_ T _ 1 s C D I C 8 dp ) Q S L_ (H aw I_ T s C D I _C 19 dp ) Q S L_ (H aw I_ T s C D I _C 2 0 dp ) Q S T L_ (H aw I_ s C D I _C 21 dp ) Q S L_ (H aw I_ T s C D I _ C 2 2 ( dp ) Q S L_ H aw I_ T s C D I _C 2 3 dp ) Q S T L_ (H aw I_ s C D I _C 2 4 dp ) Q S L_ (H aw I_ T _ 2 s C D I C 5 dp ) Q S L_ (H aw I_ T s C D I _C 2 6 dp ) Q S L_ (H aw I_ T _ 2 s C D I C 7 dp ) Q S L_ (H a I_ T _ 2 s w ) d D IS C L 8 (H pa T _ _2 s w ) C 9 ( dp L_ H aw 3 0 sd ) (H paw sd ) pa w )
C
C
CQI distribution
Median CQI (of reported values) = 18, which indicates relatively good quality HSDPA network 18.00%
Telcel – Nokia Siemens Networks confidential 56 © Nokia Siemens Networks
120.00%
16.00%
14.00% 100.00%
12.00% 80.00%
10.00% 60.00%
8.00%
6.00% 40.00%
4.00%
2.00% 20.00%
0.00% 0.00%
3G RAN Capacity / Poul Larsen / March 2009
% CDF
I_ CQ DIS I_ T CQ DIS _CL I_ T _0 CQ DIS _CL (H I_ T _1 sdp CQ DIS _CL (H aw I_ T _2 sdp ) CQ DIS _CL (H aw I_ T _3 sdp ) CQ DIS _CL (H aw I_ T _4 sdp ) CQ DIS _CL (H aw I_ T _5 sdp ) CQ DIS _CL (H aw I_ T _6 sdp ) CQ DIS _CL (H aw ) _ s CQ I_D T_C 7 ( dpa I_ IST L_ Hsd w) CQ DIS _C 8 ( pa I_ T L_ Hs w) CQ DIS _CL 9 ( dpa I_ T _1 Hs w) CQ DIS _CL 0 (H dpa I_ T _1 s w) CQ DIS _CL 1 ( dpa I_ T _1 Hs w) CQ DIS _CL 2 (H dpa I_ T _1 s w) CQ DIS _CL 3 ( dpa I_ T _1 Hs w) CQ DIS _CL 4 (H dpa I_ T _1 s w) CQ DIS _CL 5 ( dpa I_ T _1 Hsd w) CQ DIS _CL 6 (H pa I_ T _1 sd w) CQ DIS _CL 7 (H pa I_ T _1 sd w) CQ DIS _CL 8 (H pa I_ T _1 sd w) CQ DIS _CL 9 ( pa I_ T _2 Hs w) CQ DIS _CL 0 ( dpa I_ T _2 Hs w) CQ DIS _CL 1 ( dpa I_ T _2 Hs w) CQ DIS _CL 2 (H dpa I_ T _2 s w) CQ DIS _CL 3 (H dpa I_ T _2 sd w) CQ DIS _CL 4 (H pa I_ T _2 s w) CQ DIS _CL 5 ( dpa I_ T _2 Hs w) CQ DIS _CL 6 (H dpa I_ T _2 s w) CQ DIS _CL 7 ( dpa I_ T_ _2 Hsd w) DI C 8 ( pa ST L_ H w _C 29 sdp ) L_ (H aw 30 sd ) (H paw sd ) pa w)
CQ
CQI distribution Scaled CQI Distribution by +4 dB for 1-rx Equalizer Terminals
18.00%
16.00%
Should the Iub support 50% throughput probability or 70% or 90%? Depends how much is the Iub cost and how much there is traffic that generates revenue
14.00%
12.00%
10.00%
8.00%
6.00%
4.00%
2.00%
0.00%
Telcel – Nokia Siemens Networks confidential 57 © Nokia Siemens Networks 3G RAN Capacity / Poul Larsen / March 2009
CQI distribution CQI distribution 35% 30% 25% RNC1 Worst cell Best cell
20% 15% 10% 5% 0%
• Higher CQI means higher throughput – Increased cell capacity – Increased end-user perception • Low CQI can be caused by – Site is not close to the UEs – UEs are in bad radio coverage – High interference in the area – Etc. Telcel – Nokia Siemens Networks confidential 58 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
UE impact on CQI distribution
• The UE is calculating the CQI it sends to the network • Some differences between UEs - in above chart, the N95 reports ~2 dB better CQI than the datacard • Better RF implementation or just different CQI reporting? Telcel – Nokia Siemens Networks confidential 59 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Code/modulation counters • M5000 family has counters for how the PDUs are sent to the UEs – – – –
Initial transmission, QPSK, 1 - 15 codes (M5000C49 - M5000C53, M5000C86 - M5000C95) Initial transmission, 16QAM, 1 - 15 codes (M5000C54 - M5000C58, M5000C96 - M5000C105) Retransmissions, QPSK, 1 - 15 codes (M5000C59 - M5000C63, M5000C106 - M5000C115) Retransmissions, 16QAM, 1 - 15 codes (M5000C64 - M5000C68, M5000C116 - M5000C125)
• Not impacted by code multiplexing – For example, sending to 2 x Cat 1/6 UEs (UE capability is 5 codes) within same TTI (therefore using 10 codes) will update the 5-code counter twice – Activating code multiplexing will not change these counters
• The 6 - 10 code counters will only be pegged in case of cat 7/8 UEs • The 11 - 15 code counters will only be pegged in case of cat 9/10 UEs • Can be compared with the CQI counters to show how well the quality of the radio interface is used
Telcel – Nokia Siemens Networks confidential 60 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Code/modulation counters vs CQI distribution • From CQI counters and the mapping table between CQI and Transport Block Size, it can be predicted which combination of codes/modulation that will be used • This can then be verified against the actual counters CQI vs actual code usage - cell x 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
CQI - no compensation CQI - 3 dB compensation
10 - 16QAM
10 - QPSK
9 - QPSK
8 - QPSK
7 - QPSK
6 - QPSK
5 - QPSK
4 - QPSK
3 - QPSK
2 - QPSK
1 - QPSK
Actual
• In this case, the radio link quality is not fully used (Iub congestion, HLR limitations, applications?) Telcel – Nokia Siemens Networks confidential 61 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
HSDPA cell throughput • The cell throughput can also be directly measured with rnc_722b – Some relationship with the code/modulation distribution – This formula takes code multiplexing into account • Same issues as with the code/modulation distributions – If data is not arriving fast enough to the BTS buffers, lower number of codes will be used and throughput will be smaller RNC_722b [kbps] = ∑ (M5000C126
RECEIVED_H S_MACD_BIT S - M5000C127 DISCARDED_ HS_MACD_BI TS ) M5000C69 HS_SCCH_PW R_DIST_CLA SS_0 + M5000C70 HS_SCCH_PW R_DIST_CLA SS_1 + M5000C71 HS_SCCH_PW R_DIST_CLA SS_2 + ∑ M5000C72 HS_SCCH_PW R_DIST_CLA SS_ 3 + M5000C73 HS_SCCH_PW R_DIST_CLA SS_4 + M5000C74 HS_SCCH_PW R_DIST_CLA SS_5) 1000 ⋅ 500
• Some dependency between rnc_722b and the applications which are being used
Application FTP DL FTP UL HTTP Browsing WAP Browsing Streaming 160 kbps
Telcel – Nokia Siemens Networks confidential 62 © Nokia Siemens Networks
rnc_722b 5838 420 3558 1213 2816
3G RAN Capacity / Poul Larsen / March 2009
Summary • High TTI utilization => Find more TTIs – New carrier – New sector – New site • Bad CQI (DL radio link quality) => Improve radio link quality – More power (e.g. 20W => 40W) – Better coverage (new site, antenna adjustments, etc.) – Reduce interference (antenna adjustments) • Bad usage of radio link quality => Improve usage – 10/15 codes – Code multiplexing – Remove other bottlenecks
Telcel – Nokia Siemens Networks confidential 63 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Agenda
• What is capacity management and why is it needed? • Brief introduction to RAS06 performance monitoring • How to monitor – Air Interface – BTS – Iub – RNC – Iu-CS, Iu-PS, Iur
Telcel – Nokia Siemens Networks confidential 64 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
BTS resource issues • Are there enough Channel Elements? • Does the HSDPA scheduler have enough capacity?
Telcel – Nokia Siemens Networks confidential 65 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
WBTS KPI – CE Availability • CE Availability Example - FlexiBTS • The FlexBTS with 1+1+1 configuration has licensed capacity 160 CE + 32 CE basic capacity. • Example 1: The configured situation is stable over the measurement period. ▪ M5001C0 MAX_AVAIL_CE= 192 ▪ M5001C1 MIN_AVAIL_CE = 192 ▪ M5001C2 AVE_AVAIL_CE = 192
CE Availability Example
Available Capacity means Licensed CE’s not free CE or installed CE If there are WSPC cards e.g added or blocked during measurement period, it can be seen here
Sampling period is 20 seconds!
Telcel – Nokia Siemens Networks confidential 66 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
WBTS KPIs – CE Availability KPI Average ratio of utilized CE for DL/UL can be used to monitor Channel Element Utilization separately for UL and DL. RNC_730a calculates DL CE utilization RNC _ 730 a _ Average ratio of utilized CE for DL in BTS =
100 * sum ( AVE _ USED _ CE _ DL ) sum ( AVE _ AVAIL _ CE )
RNC_731a calculates UL CE utilization RNC _ 731 a _ Average ratio of utilized CE for UL in BTS =
Telcel – Nokia Siemens Networks confidential 67 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
100 * sum ( AVE _ USED _ CE _ UL ) sum ( AVE _ AVAIL _ CE )
Use of channel elements • Cell Resource measurement (M1000) has counters for what the channel elements are used for • M1000 is on cell level, while CE use only makes sense on BTS level – Each cell within one BTS has same value in the counters listed below – If e.g. aggregation on RNC level is needed: First average cell level to BTS level, then sum to RNC level
• M1000 counters are based on the RNC estimation of used CEs. Not as accurate as M5001 counters Counter id M1000C181 M1000C182 M1000C183 M1000C184 M1000C185 M1000C186 M1000C187 M1000C188 M1000C189 M1000C190 M1000C191 M1000C192 M1000C193 M1000C194 M1000C195
Counter name CE_SAMPLE_AMOUNT AVE_CE_USED_AMR AVE_CE_USED_CS_CONV_64 AVE_CE_USED_CS_STR_14_4 AVE_CE_USED_CS_STR_57_6 AVE_CE_USED_PS_STR_8_UL AVE_CE_USED_PS_STR_16_UL AVE_CE_USED_PS_STR_32_UL AVE_CE_USED_PS_STR_64_UL AVE_CE_USED_PS_STR_128_UL AVE_CE_USED_PS_STR_8_DL AVE_CE_USED_PS_STR_16_DL AVE_CE_USED_PS_STR_32_DL AVE_CE_USED_PS_STR_64_DL AVE_CE_USED_PS_STR_128_DL
Telcel – Nokia Siemens Networks confidential 68 © Nokia Siemens Networks
Counter id M1000C196 M1000C197 M1000C198 M1000C199 M1000C200 M1000C201 M1000C202 M1000C203 M1000C204 M1000C205 M1000C206 M1000C207 M1000C208 M1000C209 M1000C210
Counter name AVE_CE_USED_PS_STR_256_DL AVE_CE_USED_PS_STR_384_DL AVE_CE_USED_PS_INT_8_UL AVE_CE_USED_PS_INT_16_UL AVE_CE_USED_PS_INT_32_UL AVE_CE_USED_PS_INT_64_UL AVE_CE_USED_PS_INT_128_UL AVE_CE_USED_PS_INT_256_UL AVE_CE_USED_PS_INT_384_UL AVE_CE_USED_PS_INT_8_DL AVE_CE_USED_PS_INT_16_DL AVE_CE_USED_PS_INT_32_DL AVE_CE_USED_PS_INT_64_DL AVE_CE_USED_PS_INT_128_DL AVE_CE_USED_PS_INT_256_DL
3G RAN Capacity / Poul Larsen / March 2009
Counter id M1000C211 M1000C212 M1000C213 M1000C214 M1000C215 M1000C216 M1000C217 M1000C218 M1000C219 M1000C220 M1000C221 M1000C222 M1000C223 M1000C224 M1000C225
Counter name AVE_CE_USED_PS_INT_384_DL AVE_CE_USED_PS_BGR_8_UL AVE_CE_USED_PS_BGR_16_UL AVE_CE_USED_PS_BGR_32_UL AVE_CE_USED_PS_BGR_64_UL AVE_CE_USED_PS_BGR_128_UL AVE_CE_USED_PS_BGR_256_UL AVE_CE_USED_PS_BGR_384_UL AVE_CE_USED_PS_BGR_8_DL AVE_CE_USED_PS_BGR_16_DL AVE_CE_USED_PS_BGR_32_DL AVE_CE_USED_PS_BGR_64_DL AVE_CE_USED_PS_BGR_128_DL AVE_CE_USED_PS_BGR_256_DL AVE_CE_USED_PS_BGR_384_DL
Use of channel elements BTS x, DL CE usage (M5001 counters)
BTS x, UL CE usage (M5001 counters)
350
350
300
300
250
AVG_AVAIL_CE MAX_USED_CE_DL MIN_USED_CE_DL AVG_USED_CE_DL
200 150 100
250
AVG_AVAIL_CE MAX_USED_CE_UL MIN_USED_CE_UL AVG_USED_CE_UL
200 150 100
50
50
0
0 Nov 3 - Nov 9
Nov 3 - Nov 9
• As normal for HSDPA-dominated networks, it is usually the UL channel elements that is the bottleneck (due to the UL return channel) • Permanently reserved CEs in this BTS: – Control channels (3 sectors, no extended cell) – Shared HSDPA Baseband Scheduler Telcel – Nokia Siemens Networks confidential 69 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
26 80
Use of channel elements UL CE usage (M1000 counters)
DL CE usage (M1000 counters) 160
160 140
AVE_CE_USED_PS_INT_384_DL
140
120
AVE_CE_USED_PS_INT_256_DL
120
100
AVE_CE_USED_PS_INT_128_DL
100
AVE_CE_USED_PS_INT_64_DL
80
AVE_CE_USED_PS_INT_32_DL
AVE_CE_USED_PS_INT_32_UL
80
60
AVE_CE_USED_PS_INT_16_DL
60
40
AVE_CE_USED_PS_INT_8_DL
40
AVE_CE_USED_AMR
AVE_CE_USED_PS_INT_64_UL
20
20
0
0
AVE_CE_USED_PS_INT_16_UL AVE_CE_USED_AMR
Nov 3 - Nov 9
Nov 3 - Nov 9
• Some CE usage cannot be seen with M1000 counters – Common channels (e.g. 26 in UL & DL) – HSDPA scheduler (e.g. 32 or 80 in UL & DL) – HSDPA signalling channels (1 pr HSDPA user in DL) – CEs reserved for HSUPA Telcel – Nokia Siemens Networks confidential 70 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M1000 vs M5001 • By adding 106 CEs to M1000 counters, they can be compared with M5001 – Good match in UL – In DL, M5001 shows significantly larger values than M1000 - because the CEs used for HSDPA SRBs are not included in M1000 => By comparing UL counters, the number of CEs used "permanently" can be estimated M1000 vs M5001 counters 300 250 200
M1000 DL M5001 DL M1000 UL M5001 UL
150 100 50 0 Nov 3 - Nov 9 Telcel – Nokia Siemens Networks confidential 71 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Use of channel elements UL return channel utilization 40% 35% 30% 25% 20% 15% 10% 5% 0% 1 week
• In HSDPA-dominated networks, it is usually the UL channel elements that is the bottleneck (due to the UL return channel) • However, if R99 traffic is high, the bottleneck can also be in the DL • Before starting to install more CEs, check the utilization - maybe something can be improved Telcel – Nokia Siemens Networks confidential 72 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
WBTS KPI – RRC/RAB Setup Failure Rate The Service level measurements can provide the first indication of BTS HW limitations The relevant KPIs to monitor are • RRC connection setup failure rate resulting from BTS • RAB setup failure rate resulting from BTS PI Expression RRC Connection Setup Failure Rate resulting from BTS RAB Setup Failure Rate resulting from BTS
Threshold to Trigger Time detailed blocking analysis Resolution
100*(RRC_CONN_STP_FAIL_BTS / RRC_CONN_STP_ATT) 100*(RAB_STP_FAIL_X_BTS/ RAB_STP_ATT_X)
1%
1 hour
1%
1 hour
• Also setup failure ratio of UL return channel is relevant to look at SETUP_FAIL_BTS_HS_DSCH_INT + SETUP_FAIL_BTS_HS_DSCH_BGR -----------------------------------------------------------------------------------------------------------ALLO_HS_DSCH_FLOW_INT + ALLO_HS_DSCH_FLOW_BGR + DCH_SEL_MAX_HSDPA_USERS_INT + DCH_SEL_MAX_HSDPA_USERS_BGR + REJ_HS_DSCH_RET_INT + REJ_HS_DSCH_RET_BGR + SETUP_FAIL_RNC_HS_DSCH_INT + SETUP_FAIL_UE_HS_DSCH_INT + SETUP_FAIL_BTS_HS_DSCH_INT + SETUP_FAIL_IUB_HS_TOTAL_INT + SETUP_FAIL_RNC_HS_DSCH_BGR + SETUP_FAIL_UE_HS_DSCH_BGR + SETUP_FAIL_BTS_HS_DSCH_BGR + SETUP_FAIL_IUB_HS_TOTAL_BGR
Telcel – Nokia Siemens Networks confidential 73 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Software bugs? • Note that BTS failures can be caused by lack of CEs as well as many other reasons, e.g. sw bugs • Just a few malfunctioning cells can impact the whole network statistics • Always correlate BTS failures with e.g. maximum used CEs to confirm if it is capacity problems
Site BTS x BTS x BTS x BTS x BTS x BTS x BTS x BTS x BTS x BTS x BTS x Telcel – Nokia Siemens Networks confidential 74 © Nokia Siemens Networks
Day 20080901 20080902 20080903 20080904 20080908 20080909 20080910 20080911 20080912 20080913 20080914
RRC_CONN_STP_ATT 2326 2238 2272 1663 6736 73993 67148 54342 25696 2170 2029
3G RAN Capacity / Poul Larsen / March 2009
RRC_CONN_STP_FAIL_BTS 0 0 0 0 3370 38659 35618 28048 13646 0 0
Setup failures due to BTS, case 1
5000
300
4000
250 RRC_CONN_STP_ATT
200 3000 150
CEs
RRC attempts
BTS failures vs CE usage, BTS x
RRC_CONN_STP_FAIL_BTS AVG_AVAIL_CE MAX_USED_CE_DL
2000 100 1000
MAX_USED_CE_UL
50
0
0 Sep 1 - Sep 14
• In this case, the number of used channel elements are far below the capacity => Try site restart!
Telcel – Nokia Siemens Networks confidential 75 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Setup failures due to BTS, case 2
1400
400
1200
350
1000
300 SETUP_FAIL_BTS_HS_DSCH_INT
250
800
200 600
CEs
Setup failures
BTS failures vs CE usage
150
400
100
200
50
0
AVG_AVAIL_CE MAX_USED_CE_DL MAX_USED_CE_UL
0 Nov 3 - Nov 9
• In this case, BTS setup failures only happen when the CE usage is high => Try optimizating CE usage, otherwise add more!
Telcel – Nokia Siemens Networks confidential 76 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Setup failures due to BTS, case 4 CE utilization vs HS-DSCH BTS setup failures Setup failures due to BTS
192 CEs, Initial bitrate = 128 kbps 100% 80% 60% 40% 20% 0% 0%
20%
40%
60%
80%
100%
120%
Average UL CE utilization
• In this network, having higher CE utilization than 90% on average starts to produce problems
Telcel – Nokia Siemens Networks confidential 77 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Scheduler capacity Several types of HSDPA schedulers available • Basic scheduler in Node B – 16 users pr Node B – Consumes 32 channel elements pr Node B – Only 5 codes can be used • 16 users pr cell – Consumes 32 channel elements pr cell = 96 for a 3-sector Node B – Only 5 codes can be used • Shared HSDPA scheduler for baseband efficiency in Node B (RAN1034) – Can serve up to 3 simultaneous users – 48 users pr Node B (16 or 48 users pr cell, depending on the "48 users pr cell feature" RAN1033) – Consumes 80 channel elements in Node B – 15 codes can be used (if RAN852 is enabled)
• Dedicated Scheduler (e.g. 1 for each cell) – 48 users pr scheduler – Consumes 80 channel elements pr scheduler = 240 for a 3-sector Node B – 15 codes can be used (if RAN852 is enabled) Telcel – Nokia Siemens Networks confidential 78 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Simultaneous users Number of users with HS-DSCH radio bearer is given by: 1.5 * DUR_HSDPA_USERS_1_OR_2 + 3.5 * DUR_HSDPA_USERS_3_OR_4 + 5.5 * DUR_HSDPA_USERS_5_OR_6 + 7.5 * DUR_HSDPA_USERS_7_OR_8 + 9.5 * DUR_HSDPA_USERS_9_OR_10 + 11.5 * DUR_HSDPA_USERS_11_OR_12 + 13.5 * DUR_HSDPA_USERS_13_OR_14 + 15.5 * DUR_HSDPA_USERS_15_OR_16 + 18.5 * DURA_HSDPA_USERS_17_TO_20 + 22.5 * DURA_HSDPA_USERS_21_TO_24 + 26.5 * DURA_HSDPA_USERS_25_TO_28 + 30.5 * DURA_HSDPA_USERS_29_TO_32 + 34.5 * DURA_HSDPA_USERS_33_TO_36 + 38.5 * DURA_HSDPA_USERS_37_TO_40 + 42.5 * DURA_HSDPA_USERS_41_TO_44 + 46.5 * DURA_HSDPA_USERS_45_TO_48 rnc_645b = ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------DUR_HSDPA_NO_USERS + DUR_HSDPA_USERS_1_OR_2 + DUR_HSDPA_USERS_3_OR_4 + DUR_HSDPA_USERS_5_OR_6 + DUR_HSDPA_USERS_7_OR_8 + DUR_HSDPA_USERS_9_OR_10 + DUR_HSDPA_USERS_11_OR_12 + DUR_HSDPA_USERS_13_OR_14 + DUR_HSDPA_USERS_15_OR_16 + DURA_HSDPA_USERS_17_TO_20 + DURA_HSDPA_USERS_21_TO_24 + DURA_HSDPA_USERS_25_TO_28 + DURA_HSDPA_USERS_29_TO_32 + DURA_HSDPA_USERS_33_TO_36 + DURA_HSDPA_USERS_37_TO_40 + DURA_HSDPA_USERS_41_TO_44 + DURA_HSDPA_USERS_45_TO_48
Telcel – Nokia Siemens Networks confidential 79 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Rejection due to too many users If there is no room for more HS-DSCH users, a DCH will be allocated instead: RNC _ 660 a =
rnc_614a =
sum ( DCH _ SEL _ MAX _ HSDPA _ USERS _ INT + DCH _ SEL _ MAX _ HSDPA _ USERS _ BGR ) HSDPA _ ALLOCTIONS ( RNC _ 614 a )
ALLO_HS_DSCH_FLOW_INT + ALLO_HS_DSCH_FLOW_BGR + DCH_SEL_MAX_HSDPA_USERS_INT
+ DCH_SEL_MAX_HSDPA_USERS_BGR + REJ_HS_DSCH_RET_INT + REJ_HS_DSCH_RET_BGR + SETUP_FAIL_RNC_HS_DSCH_INT + SETUP_FAIL_UE_HS_DSCH_INT + SETUP_FAIL_BTS_HS_DSCH_INT + SETUP_FAIL_IUB_HS_TOTAL_INT + SETUP_FAIL_RNC_HS_DSCH_BGR + SETUP_FAIL_UE_HS_DSCH_BGR + SETUP_FAIL_BTS_HS_DSCH_BGR + SETUP_FAIL_IUB_HS_TOTAL_BGR)
Note: the DCH_cel_max_HSDPA_users_int/bgr didn't work correctly in RN3.0 CD1.0: In case the basic scheduler was used (16 users pr BTS), the counters would only be incremented if there were 16 users in one of the sectors, which naturally is an extremely rare event. From CD2.0, these counters work correctly Telcel – Nokia Siemens Networks confidential 80 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Nbr of users vs rejections
Nbr of HS-DSCH users and rejections summarised over all the sectors of a BTS Each dot is one BTS in one hour 1 RNC, 12 days
• Basic scheduler (16 users pr BTS) – Almost no rejections when number of users pr BTS is less than 10 – When number of users reach ~12 (75% of capacity), the rejections starts to increase dramatically
• Shared Scheduler (48 users pr BTS, 48 users pr cell) – Not so much reference data yet – Seems the rejections starts to increase at around 38 users (80% of capacity) Telcel – Nokia Siemens Networks confidential 81 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Shared HSDPA Scheduler Expanding from basic scheduler to Shared Scheduler means:
• • • • •
Number of users increased from 16 pr cell/16 pr BTS to 16 pr cell/48 pr BTS Feature "48 users pr cell" still needed to have more than 16 users pr cell All 15 codes can be used instead of just 5 Up to 3 UEs can be served simultaneously instead of just 1 Needs 80 CEs instead of 32
The following slides show first a single site to better observe the effects on HS-DSCH accessibility, and then a group of 21 sites which got the Shared Scheduler installed
Telcel – Nokia Siemens Networks confidential 82 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Shared HSDPA Scheduler in one high-traffic site Nbr of HS-DSCH RBs, BTS x Shared Scheduler, PrxTarget set to 30 dB
CD1.0 => CD2.4
40 30
BTS Sector 1 Sector 2 Sector 3
20 10 0 Oct 13 - Nov 2
HS-DSCH accessibility, BTS x 100% 80% 60% 40% 20% 0% Oct 13 - Nov 2
• • •
Max users Iub 384 kbps Iub 128 kbps Iub 64 kbps Iub 16 kbps BTS UE DL Iub RNC AC (UL) Success
BTS is heavily congested before Shared Scheduler is installed CD2.0 brings correction to DCH_SEL_MAX_HSDPA_USERS_INT Even the Shared Scheduler (16 users pr cell, 48 users pr BTS) is not enough to remove congestion. "48 users pr cell" feature (48 users pr cell, 48 users pr BTS) is the next step Telcel – Nokia Siemens Networks confidential 83 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Shared HSDPA Scheduler in 21 high-traffic sites Average nbr of HS-DSCH RBs pr BTS CD1.0 => CD2.4
Shared Scheduler, PrxTarget set to 30 dB
40 30 20 10 0 O ct 13 - Nov 2 HS-DSCH a ccessibility
100%
Max users Iub 384 kbp s
80%
Iub 128 kbp s Iub 64 kbps Iub 16 kbps
60% 40%
BTS UE
20%
DL Iub RNC AC (UL)
0% O HS-DSCH c t 13 - N o vRBs 2 Nbr of pr cell
Suc c ess
15 or 16
100%
13 or 14
80%
11 or 12
60%
9 or 10
40%
7 or 8 5 or 6
20%
3 or 4 0%
1 or 2 Oct 13 - Nov 2
• • • •
No users
Before Oct 24, HS-DSCH setup failures are mainly too many users in the scheduler and UL admission control (for the return channel) After Oct 24, UL AC rejections have virtually disappeared and the "too many users" cause has decreased significantly Still, there are cases (>10% of the time in BH) where the 16 users/cell limit is reached => 48 users pr cell is needed Some UL Iub blocking starts to appear => 16 kbps UL return channel is needed
Telcel – Nokia Siemens Networks confidential 84 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Shared HSDPA Scheduler in 21 high-traffic sites Simultaneous transmissions
TTI usage 90% 80%
100%
70% 60%
80%
50% 40%
3 sectors 2 sectors 1 sector
60%
Ratio of active TTIs Ratio of missed TTIs
40%
30% 20%
20%
10% 0%
0% Oct 13 - Nov 2
Oct 13 - Nov 2
Nbr of active HS-DSCH RBs
•
Before the Shared Scheduler, only a bit less than 33% of the TTIs were used in BH, indicating that it is quite common that there are active UEs in all 3 sectors - after the installation of the Shared Scheduler, there will almost always be transmission if any of the UEs in the cell has data waiting
•
After the Shared Scheduler is installed, it transmits to all 3 sectors simultaneously in about 40% of the time in BH
•
60% of the time, the Shared Scheduler is not transmitting to 3 UEs - introduction of code multiplexing will have some benefits
Telcel – Nokia Siemens Networks confidential 85 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
(average pr cell) 3.5 3 2.5 2 1.5 1 0.5 0 Oct 13 - Nov 2
Case study: HSDPA 48 users pr cell • RNC-level feature - requires license • Does not consume more Channel Elements • Increases capacity from "16 users pr cell/48 users pr BTS" to "48 users pr cell/48 users pr BTS"
• Does not require 16 kbps UL return channel
Telcel – Nokia Siemens Networks confidential 86 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
HSDPA 48 users pr cell - single BTS HS-DSCH accessibility, BTS x Shared scheduler
16 kbps UL ret 48 users pr cell
100% 80% 60% 40% 20% 0% Oct 6 Nov 9 RBs, BTS x Number of-HS-DSCH
Max users Iub 384 kbps Iub 128 kbps Iub 64 kbps Iub 16 kbps BTS UE DL Iub RNC AC (UL) Success
50 40 BTS Sector 1 Sector 2 Sector 3
30 20 10 0 Oct 6 - Oct 19
• Shared Scheduler removed most serious bottleneck • 48 users pr cell took care of the rest - but soon 2nd scheduler will be needed Telcel – Nokia Siemens Networks confidential 87 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Agenda
• What is capacity management and why is it needed? • Brief introduction to RAS06 performance monitoring • How to monitor – Air Interface – BTS – Iub – RNC – Iu-CS, Iu-PS, Iur
Telcel – Nokia Siemens Networks confidential 88 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Usage - M530 vs M5106 • Both M530 and M5106 contain counters that allow us to calculate the usage of the Iub links – M530 is optional – M530 covers Iub, Iur, Iu-CS, Iu-PS. M5106 covers Iub only – M530 also has counters that enable us to calculate cell loss in the ATM interfaces – Maximum 1024 VCCs can be monitored by M530 • AAL2 UP, AAL2 SIG, C-NBAP, D-NBAP, O&M VCCs are included in both measurements • Both measurements are needed to investigate Iub from both ends • For M530, separate mapping table between BTS/cell id and interface id is Counter_id Counter name needed Counter_id
M5106C0 M5106C1 Telcel – Nokia Siemens Networks confidential 89 © Nokia Siemens Networks
Counter name period_start_time wbts_id ftm_id vptt_id vcct_id period_duration totCellsIngressVC totCellsEgressVC
3G RAN Capacity / Poul Larsen / March 2009
M530C0 M530C1 M530C2 M530C3 M530C4 M530C5 M530C6 M530C7
rnc_id if_id vpi_id vci_id period_start_time period_duration IN_TOT_CELLS_VC EG_TOT_CELLS_VC IN_REC_CELLS_VC IN_QUEUED_CELLS_VC IN_CAP_VC EG_REC_CELLS_VC EG_QUEUED_CELLS_VC EG_CAP_VC
Iub Interface usage PI Name:
Average VCC Load / Average VCC Utilization
Counter Table:
ATM VCC Measurement
Monitoring Type:
Proactive
PI Expression:
IN_TOT_CELLS_VC/ MEASUREMENT DURATION EG_TOT_CELLS_VC/ MEASUREMENT DURATION 100 * IN_TOT_CELLS_VC/ MEASUREMENT DURATION / IN_CAP_VC 100* EG_TOT_CELLS_VC/ MEASUREMENT DURATION / EG_CAP_VC
Units/Level: cps and % PI Description This measurement reports the cells per VCC during measurement period. VCC measurements enable monitoring of ATM traffic for DNBAP, CNBAP, O&M and user plane VCCs on Iub. Average load in ingress and egress direction can be calculated dividing counter values by the measurement period. VCC Utilization level [%] can be calculated in RAS6 with new counters reporting VCC size. Note: the capacity counters are showing the MDCR in case of UBR+ Note: Iu-cs, Iu-ps and Iur VCCs can be measured as well.
Telcel – Nokia Siemens Networks confidential 90 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
AAL2 User Plane Max Iub utilization, w36, UP = 8197
Max Iub utilization, w36, UP = 3706 100%
100%
80%
80%
60%
DL utilisation UL utilisation
40%
60%
DL utilisation UL utilisation
40%
20%
20%
0%
0% Interface
Interface
• M530 can be used to monitor signalling (C-NBAP, D-NBAP, AAL2SIG, O&M) VCCs as well as User Plane VCCs • This workshop only cover the user plane VCCs • In HSDPA networks, normal that DL utilization is higher than UL • There can still be plenty of failed Iub reservations due to UL congestion!
Telcel – Nokia Siemens Networks confidential 91 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub utilisation thresholds • M530/M529 measurement can be set up with measurement interval of
• 15 minutes • 60 minutes • Usually the used interval is 60 minutes • 15 minutes interval produces quite high amount of measurement data • The VCC load can have quite a lot of variance during the measurement period • The slides below show the variance of minute level data compared to the hourly measurement result
Telcel – Nokia Siemens Networks confidential 92 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub utilisation thresholds E GR Load/Minute
SHARED CBR VCC PCR 10371 cps Highest Average Load (hour)
E GR Load/Hour ING Load/Minute ING Load/Hour
1.40000%
90.000% 80.000%
1.20000%
70.000% EGRESS
50.000%
0.80000%
40.000%
0.60000%
30.000%
INGRESS
1.00000%
60.000%
0.40000%
20.000% 0.20000%
10.000%
0.00000%
0.000% 1
4
7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61
• The minute level load can be more than double of the hourly load • The UL Load is low (< 1.5% ) at all times • The traffic is likely HSDPA • This VCC had the highest average load (M530) of all the Iub VCCs • The minute level results obtained by special arrangements Telcel – Nokia Siemens Networks confidential 93 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub utilisation thresholds Iub Egress Peak to Ave for sites which have > 50% minute level utilisation EGR Load/Minute
80.000%
6
EGR Load/Hour
5
EGR Minute to Hour Ratio
ATM Load
4 60.000% 3 40.000% 2 20.000%
0.000%
Minute / Hour Load Ratio
100.000%
1
0 1 2 3 4 5 6 7 8 91011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071
• The graph shows the peak to average ratio of 71 highest minute ATM load samples to the respective hourly ATM load. • Less than 25% have a value higher than 2.5 => If the hourly average load is 40%, it is unlikely that the minute average load reaches 100% Telcel – Nokia Siemens Networks confidential 94 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub User Plane: AAL2 Path CAC Resource Measurement (M550) • AAL2 connections are allocated and released by ATM Resource Management which will •
•
• • •
check AAL2 reservation using CAC. M550 measurement reports RNC CAC resource usage for Iub AAL2 user plane traffic downlink – There can be more than one user plane VCC, this measurement is per VCC – Dedicated counters also for HSDPA RNC CAC controls resources in downlink direction from RNC to WBTS – Uplink CAC functionality is located in the BTS and in the case of AAL2 multiplexing in AXC – Rejected capacity requests may be followed to certain extend with M800 measurement Useful for monitoring Iub (DL) and Iucs (UL) and Iur load – The VCC counters for HSDPA show zero for VCCs on the Iucs or Iur Maximum of 1600 VCC objects can be measured at the same time The measurements must be configured as per VCI, VPI and ATM interface ID -> statistics are also given for the same combination i.e. NOT as per BTS id or cell id (translation from VPI, VDI and ATM interface ID to BTS/Cell ID is needed - unless optional feature RAN868 "ATM Transport Statistics Reporting in RAN" is available)
Telcel – Nokia Siemens Networks confidential 95 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub User Plane: AAL2 Path CAC Resource Measurement (M550) Counter_id Counter name
Reserved capacity
Connections
Reservation successes/failures
HSDPA
Telcel – Nokia Siemens Networks confidential 96 © Nokia Siemens Networks
M550C0 M550C1 M550C2 M550C3 M550C4 M550C5 M550C6 M550C7 M550C8 M550C9 M550C10 M550C11 M550C12 M550C13 M550C14 M550C15 M550C16 M550C17 M550C18 M550C19
3G RAN Capacity / Poul Larsen / March 2009
rnc_id if_id vpi_id vci_id period_start_time period_duration AAL2_PATH_GUAR_CELL_RATE SUM_RESERVED_CELL_RATE MIN_RESERVED_CELL_RATE MAX_RESERVED_CELL_RATE SUM_AAL2_CONNECTIONS MIN_AAL2_CONNECTIONS MAX_AAL2_CONNECTIONS NBR_SAMPLES AAL2_RM_SUCCEEDED AAL2_CAC_REJECTED AAL2_HW_REJECTED SUM_AAL2_CONNECTIONS_HSDPA MIN_AAL2_CONNECTION_HSDPA MAX_AAL2_CONNECTIONS_HSDPA AAL2_CAC_REJECTED_HSDPA AAL2_HW_REJECTED_HSDPA SHARED_HSDPA_AAL2_ALLOCATION AAL2_RM_SUCCEEDED_HSDPA MIN_SHARED_HSDPA_AAL2_ALLOC MAX_SHARED_HSDPA_AAL2_ALLOC
Capacity bottleneck: Iub capacity M550 counters traffic rate [cells/sec.] Configured PCR of VCC
= sampled value (once per second)
VCC load estimated by CAC
Real traffic load of ATM VCC
Shared HSDPA AAL2 allocation size
Time /sec
Telcel – Nokia Siemens Networks confidential 97 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M550 - reserved capacity Reserved capacity 9000 8000
cps
7000 6000
AAL2_PATH_GUAR_CELL_RATE MIN_RESERVED_CELL_RATE MAX_RESERVED_CELL_RATE SHARED_HSDPA_AAL2_ALLOCATION
5000 4000
Average reserved c ell rate
3000 2000 1000 0 Nov 3 - Nov 9
Telcel – Nokia Siemens Networks confidential 98 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M550: CAC reservation successes/failures Counter id Counter name M550C8 AAL2_RM_SUCCEEDED
M550C9 M550C10
AAL2_CAC_REJECTED AAL2_HW_REJECTED
Description The number of successful AAL2 resource reservations. The connection has successfully passed the AAL2 connection resource reservation stage, but may still fail in the DMPG/TPG resource reservation or in the signalling phase. The total number of rejected connections due to CAC. The number of connection establishments, which are rejected due to failed HW request. This failure can occur after successful CAC resource reservation.
• Counters are only related to RNC CAC, i.e. downlink reservations on Iub (or uplink on Iu-CS or outgoing on Iur) • Failure ratio can be calculated as AAL2_CAC_REJECTED + AAL2_HW_REJECTED ---------------------------------------------------------------------------------------------------------AAL2_RM_SUCCEEDED + AAL2_CAC_REJECTED + AAL2_HW_REJECTED
Telcel – Nokia Siemens Networks confidential 99 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M550 - reserved capacity Reservations vs failure ratio
cps
Failure ratio 10000
50%
8000
40%
6000
30%
4000
20%
2000
10%
0
0% Nov 3 - Nov 9
Telcel – Nokia Siemens Networks confidential 100 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
MAX_RESERVED_CELL_RATE Average reserved cell rate Reservation failure ratio
M530/M550 - utilization vs reservations Utilization vs Reservation 100% 80% 60%
Reservatio n failure ratio Max reservation ratio Average re servation ra tio DL utilizatio n
40% 20% 0% Nov 3 - Nov 9
• Highest average utilization ~70% • Highest average reservation ~90% • Reservation failures start to appear at ~50% utilization
Telcel – Nokia Siemens Networks confidential 101 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M550: Connection ID Usage Max number of CIDs available for connections per VCC is 248 • A single call requires 2 connections, 2 CIDs (e.g. SRB + AMR or SRB + NRT PS) • A multi-RAB call requires one CID per connected RAB in addition to the SRB CID • Per each HSDPA user 3 CIDs (SRB + MAC-d Flow + UL Return Channel) Common channels (four per cell) require their own connections and CIDs as well Measurements for number of connections • Average number of AAL2 connections - includes R99, SRB, HSDPA and return channels SUM_AAL2_CONNECTIONS / NBR_SAMPLES = C4/C7
• Max number of AAL2 connections during measurement period (R99, SRB, HSDPA and return channel) MAX_AAL2_CONNECTIONS = C6
(and MIN_AAL2_CONNECTIONS = C5)
• Average number of AAL2 connections used by HSDPA i.e. number of MAC-d flows (note this does not include SharedHSDPAAllocation reservation) SUM_AAL2_CONNECTIONS_HSDPA / NBR_SAMPLES = C11/C7
• Max number of simultaneous HSDPA connections during the measurement period ( this tells the maximum amount of HSDPA users from Iub VCC point of view) MAX_AAL2_CONNECTIONS_HSDPA = C13 (and MIN_AAL2_CONNECTIONS_HSDPA = C12)
Telcel – Nokia Siemens Networks confidential 102 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M550: Connection ID Usage Max nbr of AAL2 connections, w36 250 200 150 100 50 0 Interface
• Peak number of AAL2 connections was ~150 in the worst link in the most busy hour of the week => no concern about this KPI • If the peak number of AAL2 connections is high, the VCC can be split into two parts
Telcel – Nokia Siemens Networks confidential 103 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
AAL2 Resource Reservation (M800) Ø Ø Ø Ø Ø Ø Ø
M800 is useful for monitoring success of the resource reservation requests M800 collects the statistics per AAL2 user plane VCC object, note that there can be several UP VCCs The object of the measurement is the AAL2 path selected with ATM interface ID/VPI/VCI identifiers Max 500 UP VCCs can be monitored at the same time There are dedicated counters for HSDPA resource reservations when shared user plane VCC is used User Plane on Iub, IuCS and Iur can be monitored Measurement is optional (bundled with M550)
Performance indicators
AAL2 Reservation Success rate HSDPA Reservation Success Rate
Measurement is able to count different type of failures, such as • Lack of Iub bandwidth • Lack of RNC capacity • AAL2 signaling failure
Telcel – Nokia Siemens Networks confidential 104 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
AAL2 Resource Reservation (M800) Counter ID Counter name
Reservation successes/failures
HSDPA reservation successes/failures
Reservation and release of HSDPA resources
Telcel – Nokia Siemens Networks confidential 105 © Nokia Siemens Networks
M800C0 M800C1 M800C2 M800C3 M800C4 M800C5 M800C6 M800C7 M800C8 M800C9 M800C10 M800C11 M800C12 M800C13 M800C14 M800C15 M800C16 M800C17 M800C18 M800C19
3G RAN Capacity / Poul Larsen / March 2009
rnc_id if_id vpi_id vci_id period_start_time period_duration RES_SUCCEEDED RES_EXT_CAP RES_INT_CAP RES_OTHER AAL2_SUCCEEDED AAL2_REJECTED AAL2_SUCCEEDED_HSDPA TRANSPORT_REJECTED_EXT_HSDPA TRANSPORT_REJECTED_INT_HSDPA OTHER_REJECTED_HSDPA ACTIVE_HSDPA_RES_TIME WAITING_HSDPA_RES_TIME RELEASE_TIMER_LENGTH RESERV_REL_DUE_TO_TIMER RESERV_REL_TIMER_STARTED RESERV_REL_TIMER_STOPPED RESERV_REL_DUE_TO_OTHER ACTIVE_TIME_CUMULATIVE WAITING_TIME_CUMULATIVE REJECT_HSDPA_TOO_MANY_USERS
Capacity bottleneck: Iub capacity M800 counters
RNC
BTS
UE
AAL2 SIG
CAC
CAC
AAL2SIG
ATM RM
RRC: connection request
RNC internal transport resource reservation AAL2 connection establishment ERQ (SUGR)
WBTS internal transport resource reservation Response to ERQ; ECF or RLC (cause) AAL2 conn. estab. confirmation RRC:connection setup
Telcel – Nokia Siemens Networks confidential 106 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
RRC
AAL2 Resource Reservation (M800) Downlink reservation failure ratio: RES_EXT_CAP + RES_INT_CAP + RES_OTHER -----------------------------------------------------------------------------------------------RES_SUCCEEDED + RES_EXT_CAP + RES_INT_CAP + RES_OTHER
One week aggregated data:
Uplink reservation failure ratio:
AAL2_REJECTED --------------------------------------------------------AAL2_SUCCEEDED + AAL2_REJECTED
Telcel – Nokia Siemens Networks confidential 107 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Counter RES_SUCCEEDED RES_EXT_CAP RES_INT_CAP RES_OTHER AAL2_SUCCEEDED AAL2_REJECTED DL failure ratio UL failure ratio Overall failure ratio
RNC1 RNC2 RNC3 171513316 106300722 30524518 74010 321017 3394 0 0 0 11871 31108 133 171209452 106264467 30510232 303864 36255 14286 0.05% 0.33% 0.01% 0.18% 0.03% 0.05% 0.23% 0.36% 0.06%
Uplink AAL2 CAC Reservation Load and Failures •
Uplink AAL2 CAC reservation levels are not directly visible through counters • It can be calculated by calculating average loading per bearer type by looking at allocation duration counters in M1002 for different types of DCH
•
Uplink AAL2 CAC failures can be seen in M800C5 • there are some other causes included in the counter but main reason is UL CAC • Can be cross checked against M548C5. • As we can only see the failures the monitoring method is reactive.
Telcel – Nokia Siemens Networks confidential 108 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Using Shared HSDPA Scheduler for baseband efficiency Downlink Iub reservations, BTS x
Overall PS accessibility
100%
100%
80%
80%
60%
60%
PS_SETUP_FAIL_OTHER_INT PS_SETUP_FAIL_UE_INT
Reservation Failure ratio
40%
PS_SETUP_FAIL_TRANS_INT PS_SETUP_FAIL_DMCU_INT PS_SETUP_FAIL_BTS_INT
40%
PS_SETUP_FAIL_AC_INT
20%
20%
0%
0%
Oct 6 - Oct 19
Success
Oct 6 - Oct 19
• Reduction of R99 traffic leads to significant reduction in DL Iub reservation • But still Iub problems in the PS accessibility => Check M800 counters
Telcel – Nokia Siemens Networks confidential 109 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Using Shared HSDPA Scheduler for baseband efficiency Iub reservation failures, BTS x 60% 50% 40% Downlink Uplink
30% 20% 10% 0% Oct 6 - Oct 19
• M800 counters confirm that DL reservation failures have disappeared when the Shared Scheduler was activated on Oct 13 • Instead, UL has become the bottleneck (increased HS-DSCH availability leads to less DL R99 traffic, but probably more or less the same reservations in UL direction) •TelcelTry Transport Bearer Tuning or 16 kbps UL return channel – Nokia Siemens Networks confidential 110
© Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: 16 kbps UL return channel • Exisiting bit rates for UL return channel are 64 kbps, 128 kbps, 384 kbps
• This feature allows to use 16 kbps as well • As the UL return channel normally does not carry much data, it is expected that 16 kbps in many cases will be enough – Less CE usage – Less Iub reservations • In this network, used together with Throughput Based Optimization and Flexible Upgrade • Initial bitrate set to 64 kbps
Telcel – Nokia Siemens Networks confidential 111 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: 16 kbps UL return channel HS-DSCH accessibility, BTS x 100% 80% 60% 40% 20% 0% Oct 6 - Oct 19
Max users Iub 384 kbps Iub 128 kbps Iub 64 kbps Iub 16 kbps BTS UE DL Iub RNC AC (UL) Success
• Some of the sites which had the Shared Baseband Scheduler installed started to suffer from UL Iub congestion • 16 kbps UL return channel activated on RNC level on Oct 20
Telcel – Nokia Siemens Networks confidential 112 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: 16 kbps UL return channel HS-DSCH accessibility, BTS x Shared scheduler
16 kbps UL ret 48 users pr cell
100% 80% 60% 40% 20% 0% Oct 6 - Nov 9
• Some of the sites which had the Shared Baseband Scheduler installed started to suffer from UL Iub congestion • 16 kbps UL return channel activated on RNC level on Oct 20 – Iub failures disappear – Due to RNC s/w instability, Oct 24 - 28 is removed from the following slides Telcel – Nokia Siemens Networks confidential 113 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Max users Iub 384 kbps Iub 128 kbps Iub 64 kbps Iub 16 kbps BTS UE DL Iub RNC AC (UL) Success
Case study: 16 kbps UL return channel Relative duration of UL return channels, BTS x 100% 80% 60%
64 kbps 16 kbps
40% 20% 0% Oct 6 - Oct 23 + Oct 29 - Nov 8
• Before activation of the 16 kbps UL return channel, 100% of the UL return channel duration was 64 kbps • 16 kbps is now used in about 60% of the time in the site
Telcel – Nokia Siemens Networks confidential 114 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: 16 kbps UL return channel Iub reservation failures, BTS x 60% 50% 40% Downlink Uplink
30% 20% 10% 0% Oct 6 - Oct 23 + Oct 29 - Nov 8
• 16 kbps return channel lead to virtual disappearence of the Iub reservation failures • Iub utilization not impacted
Iub utilization 100% 80% 60%
DL Iub utilization UL Iub utilization
40% 20% 0% Oct 6 - Oct 23 + Oct 29 - Nov 8
Telcel – Nokia Siemens Networks confidential 115 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: 16 kbps UL return channel CE usage, BTS x 350 300 250 AVG_AVAIL_CE MAX_USED_CE_DL MAX_USED_CE_UL
200 150 100 50 0 Oct 6 - Oct 23 + Oct 29 - Nov 8
• 16 kbps return channel reduces maximum CE usage from ~300 to ~270
Telcel – Nokia Siemens Networks confidential 116 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub flow control
• Standard 3GPP flow control (between RLC layers in RNC and UE) doesn't take Iub capacity into account • If several active UEs in a Node B, the AAL2 buffers in the A2SUs may overflow, leading to packet losses – This leads to retransmissions on RLC and maybe even on TCP/IP layers • The parameter "InternalHSDPAFCMethodBTS" determines which type of flow control is used – 0: No flow control – 1: Static Flow Control – 2: Dynamic Flow Control (optional feature, RAN324) Telcel – Nokia Siemens Networks confidential 117 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub flow control With 1*E1 and 3 simultaneous HSDPA users the Iub can get overloaded causing RLC layer retransmissions with No Flow Control when the #simultaneous users increases • The end result is fluctuating when #simultaneous users increases as shown in figures on the right • Cell throughput (3 user) throughputs is ~400-600kbps • SHFCA is set close to the VCC UP Size
1 user
2 users
3 users M1017 is optional
Thousands of dropped AAL2 packets and RLC retransmission rate ~1.95 and very large amount of PDUs going through with 5 or more retransmissions
Telcel – Nokia Siemens Networks confidential 118 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub flow control When same test case is done with Static Flow Control the results show very stable throughput as shown on the right and RLC retransmissions and dropped AAL2 packets below • The cell throughput (3 user) is ~900-950kbps Average #transmissions per PDU is 1.000045 and no AAL2 packet drops were detected
Telcel – Nokia Siemens Networks confidential 119 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
1 user
2 users
3 users
Iub flow control When same test case is done with Dynamic Flow Control the results show very stable throughput as shown on the right and RLC retransmissions and dropped AAL2 packets are shown below • The cell throughput (3 user) is ~1.3mbps showing clearly that with Dynamic Flow Control the end user throughput can be maximized i.e. Iub can be utilised more (higher utilisation) • SHFCA is set close to the VCC UP Size Average #transmissions per PDU is 1.000057 and no AAL2 packet drops were detected
Telcel – Nokia Siemens Networks confidential 120 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
1 user
2 users
3 users
Case study: Activation of Dynamic Flow Control - PDU retransmission ratio PDUperPDU
1.14 1.12 1.1
PDUperPDU
1.08 1.06 1.04 1.02 1 0.98 0.96
26 0 9 26 6 9 2 27 1 9 28 9 28 9 3 9 29 18 9 1 30 2 30 9 2 9 30 17 9 1 23 10 2 21 10 2 11 10 1 3 9 10 3 0 1 3 05 10 3 10 10 3 15 10 2 4 2 10 4 3 1 4 0 8 10 4 13 10 4 18 10 2 5 3 10 5 4 1 5 0 9 10 5 14 10 1 6 9 10 6 0 1 6 0 6 10 11
1
9 26
9 25
9
6
12 24
9 23
22
9
20
0.94
Date PDUperPDU Telcel – Nokia Siemens Networks confidential 121 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Telcel – Nokia Siemens Networks confidential 122 © Nokia Siemens Networks 3G RAN Capacity / Poul Larsen / March 2009
Date
RNC_608a/HSDPA data volume (MAC-d) at Iub Mbit 2008/10/05 20
2008/10/05 16
2008/10/05 12
2008/10/05 08
2008/10/05 04
2008/10/05 00
2008/10/04 20
RNCLCN1 - RNC_608a/HSDPA data volume (MAC-d) at Iub Mbit
2008/10/04 16
2008/10/04 12
2008/10/04 08
2008/10/04 04
2008/10/04 00
2008/10/03 20
2008/10/03 16
2008/10/03 12
2008/10/03 08
2008/10/03 04
2008/10/03 00
2008/10/02 20
2008/10/02 16
2008/10/02 12
2008/10/02 08
2008/10/02 04
2008/10/02 00
2008/10/01 20
2008/10/01 16
2008/10/01 12
2008/10/01 08
2008/10/01 04
2008/10/01 00
2008/09/30 20
2008/09/30 16
2008/09/30 12
2008/09/30 08
2008/09/30 04
2008/09/30 00
RNC
2008/09/29 20
2008/09/29 16
2008/09/29 12
2008/09/29 08
2008/09/29 04
2008/09/29 00
Mbit
Case study: Activation of Dynamic Flow Control Feature Activation
350000.00
300000.00
250000.00
200000.00
150000.00
100000.00
50000.00
0.00
Case study: Activation of Dynamic Flow Control - Drive test throughput before change Maximum throughput that the WBTS can give (air interface).
Actual throughput
In some instants the user throughput variation was quite high. Telcel – Nokia Siemens Networks confidential 123 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Activation of Dynamic Flow Control - Drive test throughput after change Maximum throughput that the WBTS can give (air interface).
Actual throughput
After activating the feature the user throughput variation is much less than before. Iub congestion prevents throughput from reaching acceptable values Telcel – Nokia Siemens Networks confidential 124 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Service level monitoring Relevant counters for high-level monitoring of transmission performance: • RRC connection: – RRC_CONN_STP_FAIL_TRANS – RRC_CONN_STP_FAIL_IUB_AAL2 • RAB establishment (Voice, video, streaming - NOT interactive and background) – RAB_STP_FAIL_CS_VOICE_TRANS – RAB_STP_FAIL_CS_V_IUB_AAL2 • HS-DSCH establishment (counters for interactive and background) – SETUP_FAIL_IUB_HS_TOTAL_INT – SETUP_FAIL_IUB_MAC_D_INT – SETUP_FAIL_16_IUB_HSDSCH_INT – SETUP_FAIL_64_IUB_HSDSCH_INT – SETUP_FAIL_128_IUB_HSDSCH_IN – SETUP_FAIL_384_IUB_HSDSCH_IN • PS RB establishment (counters for interactive and background) – PS_SETUP_FAIL_TRANS_INT Telcel – Nokia Siemens Networks confidential 125 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Impact on Iub congestion on radio KPIs • For HSDPA networks with the traditional Iub transport network (X x E1s), it is quite common to have high usage of the DL Iub capacity • This means that the buffers in the BTS cannot be fed as quickly as the BTS can send the data over the radio interface • This in turn means the BTS will select lower modulation/codes than what the radio interface allows in order to avoid padding • The following slides examines how this can look in practice – Basic scheduler is in use (so no more than 5 codes can be used) – Proportional Fair scheduler – Static Flow Control is in use – RAS06, RN3.0 CD1.0, WN4.0 CD1.0
Telcel – Nokia Siemens Networks confidential 126 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Impact on Iub congestion on radio KPIs • All the statistics come from one BTS that initially only used 1 x E1 and was suffering from slight congestion (the utilization exceeded the 40% threshold every day in the busy hour) • On October 1st, the capacity was expanded to 2 x E1 • The following split between signalling and user plane traffic was used Iub UP utilization
CNBAP DNBAP AAL2 SIG UP
1 x E1 158 316 158 3706
2 x E1 158 316 158 8197
100% 80% 60%
Downlink Uplink
40% 20% 0% Sep 22 - Oct 1
Telcel – Nokia Siemens Networks confidential 127 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Impact on Iub congestion on radio KPIs
cps
Iub traffic
Iub UP utilization
9000 8000
100%
7000 6000 5000 4000
80% VCC capacity Downlink Uplink
3000 2000
60%
Downlink Uplink
40% 20%
1000 0
0% Sep 22 - Oct 12
Sep 22 - Oct 12
• After expansion, peak traffic increased from ~2000 cps to ~3000 cps • Peak average utilization is now at 40%
Telcel – Nokia Siemens Networks confidential 128 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Case study: Impact on Iub congestion on radio KPIs
kbps
Cell throughput (rnc_722b)
Efficiency (rnc_607c)
2500
100%
2000
95%
1500
90%
1000
85%
500
80%
0
75% Sep 22 - Oct 12
Sep 22 - Oct 12
Both the HSDPA cell throughput and the efficiency KPIs changed after the expansion • Average HSDPA cell throughput in the 7 days prior to the expansion was 414 kbps. In the 7 days following the expansion, the average throughput went up to 837 kbps • Average efficiency decreased from 97% to 93% – Still above the target of 90%, so still congestion somewhere Telcel – Nokia Siemens Networks confidential 129 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Share of 16QAM capable UEs
Case study: Impact on Iub congestion on radio KPIs
100% 80% 60% 40% 20% 0% Sep 22 - Oct 12
Actual code usage vs CQI based, after
Actual code usage vs CQI based, before 70%
70%
60%
60%
50%
50% Actual Reported CQI Compensated CQI
40% 30%
30%
20%
20%
10%
10%
0%
0% 1-QPSK
• • • • •
Actual Reported CQI Compensated CQI
40%
2-QPSK
3-QPSK
4-QPSK
5-QPSK 5-16QAM
1-QPSK
2-QPSK
3-QPSK
4-QPSK
5-QPSK
With the help of the CQI mapping table, the modulation/code use can be predicted from the CQI values The counters show reported CQI while the mapping table uses compensated CQI In the charts, the prediction is done both based on the reported CQI and on the compensated CQI (assuming 3 dB compensation) Charts show average values from previous 7-day period vs following 7-day period Before the Iub expansion, the actual modulation/code use is much lower than predicted from CQI. After expansion, at least the lower code use is more aligned with the prediction – On average, 96% of the UEs in the BTS support 16QAM
Telcel – Nokia Siemens Networks confidential 130 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
5-16QAM CQI 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
TBS 137 173 233 317 377 461 650 792 931 1262 1483 1742 2279 2583 3319 3565 4189 4664 5287 5887 6554 7168 7168 7168 7168 7168 7168 7168 7168 7168
codes 1 1 1 1 1 1 2 2 2 3 3 3 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
M QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM 16QAM
∆ (dB) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1 -2 -3 -4 -5 -6 -7 -8
Case study: Impact on Iub congestion on radio KPIs Summary • Moderate level of DL Iub congestion was solved with E1 expansion • This resulted in the use of higher modulation/code combinations • In turn, the higher modulation/code combinations doubled the HSDPA cell throughput from 414 kbps to 837 kbps and brought the efficiency closer to the target (97% to 93%)
Telcel – Nokia Siemens Networks confidential 131 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Agenda
• What is capacity management and why is it needed? • Brief introduction to RAS06 performance monitoring • How to monitor – Air Interface – BTS – Iub – RNC – Iu-CS, Iu-PS, Iur
Telcel – Nokia Siemens Networks confidential 132 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Overview of KPIs The following KPIs are normally investigated in order to assess RNC capacity issues • Connectivity – Nbr of WCELLs – Nbr of BTSs – AAL2 User Plane • Traffic – Carried AMR Erlang – Carried PS data – Allocated capacity for PS data ("DMCU load factor") – RRC connected mode users – Nbr of HSDPA users • CPU load – Average load • DSP performance – Call setup success ratio Telcel – Nokia Siemens Networks confidential 133 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Connectivity • The "Cell Resource" table starts to contain the cell id as soon as the cell is defined in the RNC configuration database • RNC1: – 657 cells (57% of the capacity) – 232 BTSs (45% of the capacity)
• The AAL2 User Plane connectivity (Iub, Iur, Iu-CS) can be taken from M550C0 AAL2_PATH_GUAR_CELL_RATE
• UP connectivity (Mbps) = M550C0 * 53 * 8 / 1000000 • RNC1: – AAL2 UP connectivity = 784 Mbps (22%) Note: Same RNC/same period used throughout this section. RNC configuration: RNC450/450 Telcel – Nokia Siemens Networks confidential 134 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
AMR Erlangs Average AMR Erlangs in the measurement period can be measured with the following formula: ∑ DUR_FOR_AMR_12_2_DL_IN_SRNC + DURA_FOR_AMR_12_2_DL_IN_DRNC
All cells over RNC
AMR Usage(E) =
100 ⋅ measurement period [s] SHO OH
Where the SHO overhead is given by SHO OH RT =
∑ ONE_CELL_IN_ACT_SET_FOR_RT + TWO_CELLS_IN_ACT_SET_FOR_RT + THREE_CELLS_IN_ACT_SET_RT
All Cells in RNC
∑
ONE_CELL_I N_ACT_SET_FOR_RT +
All Cells in RNC
TWO_CELLS_IN_ACT_SET_FOR_RT THREE_CELLS_IN_ACT_SET_RT + 2 3
The Erlang capacity (8000 for RNC450/450) can be multiplied with 0.8 to take peak-to-average ratio into account Telcel – Nokia Siemens Networks confidential 135 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
AMR Erlangs AMR Erlang, UMMT1
AMR Erlang, UMMT1 250
8000 7000
200 Erlangs
Erlangs
6000 5000 4000 3000 2000
150 100 50
1000 0
0 Sep 1 - Sep 9
• The RNC is very far from reaching the capacity limit
Telcel – Nokia Siemens Networks confidential 136 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 1 - Sep 9
Iub throughput • Iub throughput is calculated as the PS + CS data throughput • Total throughput is found by using M530 counters and the CS voice contribution is then subtracted – Note that softer HO overhead for CS voice does not appear on Iub, therefore it should not be subtracted DUR_FOR_AM R_12_2_DL_ IN_SRNC All cells over RNC + DURA_FOR_A MR_12_2_DL _IN_DRNC M530C1 ∑ 16.4kbps 44B ⋅ 8b 100 * Softer HO OH All Iub UP VCCs in RNC PS _& _ CS _ Data = ⋅ − ⋅ ⋅VAF measuremen t period [s] measuremen t period [s] 1000 ⋅ 1000 1000
∑
• Where Softer HO overhead is ∑ SOFTER_HO_ DUR_ON_SRN C_FOR_RT = ∑ ONE_CELL_I N_ACT_SET_ FOR_RT + TWO_CELLS_ IN_ACT_SET _FOR + THREE_CELL S_IN_ACT_S ET_RT All Cells in RNC
+1
All Cells in RNC
• The Iub capacity (450 Mbps for RNC450/450) is normally multiplied with 0.8 to take peakto-average ratio into account • Additionally 30 % Dedicated Channel (DCH) traffic in the uplink direction is supported – If UL share of the traffic is higher, more complex formulas are needed Telcel – Nokia Siemens Networks confidential 137 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub throughput Iub Throughput, PS + CS data, UMMT1 450 400
Mbps
350 300 250 200 150 100 50 0 Sep 1 - Sep 9
• The Iub throughput is not yet a capacity problem
Telcel – Nokia Siemens Networks confidential 138 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub load factor • In addition to meeting the Erlang and the Iub throughput limit individually, the following equation must also be satisfied AMR (Erl) PS data (Mbps) CS data (Mbps) + + ≤1 Max AMR (Erl) max Iub throughput (Mbps) max Iub throughput (Mbps)
• Calculation of the numerators is done as shown in previous slides and the denominators are taken from the capacity statement • Again, 0.8 is used to take peak-to-average ratios into account • In addition, the CS data traffic must follow this rule: CS data (Mbps) ≤ 25% max Iub throughput
Telcel – Nokia Siemens Networks confidential 139 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iub load factor Iub throughput load factor, UMMT1 1 0.8 0.6 0.4 0.2 0 Sep 1 - Sep 9
• The Iub load factor is not yet a capacity problem
Telcel – Nokia Siemens Networks confidential 140 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DMCU allocation load • The DMCUs (Diversity and Macro Combining Units) provides RNC related user and control plane functions • The following equation must be valid PS64 (Mbps) PS 128 (Mbps) PS 256 (Mbps) PS 384 (Mbps) HSDPA (Mbps) + + + + ≤1 DMCUmax PS64 (Mbps) DMCUmax PS128 (Mbps) DMCUmax PS256 (Mbps) DMCUmax PS384 (Mbps) max HSDPA (Mbps)
• The numerators are calculated based on counter statistics using the formulas shown on the next slides • The denominators come from the RNC capacity statement
Telcel – Nokia Siemens Networks confidential 141 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DMCU allocation load ∑
(DUR _ PS _ BACKG _ 64 _ DL _ IN _ SRNC + DURA _ FOR _ 64 _ DL _ IN _ DRNC ) ⋅ 69 .5kbps
RNC _ 1065 a _ PS _ Load [64 Mbps ]DL =
AllCellsOv erRNC
RNC _ 1066 a _ PS _ Load [128 Mbps ] DL =
AllCellsOv erRNC
RNC _ 1067 a _ PS _ Load [ 256 Mbps ]DL =
AllCellsOv erRNC
100 ⋅ measuremen t period [s] ⋅ 1000
RNC _ 1068 a _ PS _ Load [384 Mbps ] DL =
H SDPA [Mbps] =
(DUR _ PS _ BACKG
∑
_ 128 _ DL _ IN _ SRNC + DURA _ FOR _ 128 _ DL _ IN _ DRNC ) ⋅ 136 .7 kbps 100 ⋅ measuremen t period [s] ⋅ 1000
∑
(DUR _ PS _ BACKG _ 256 _ DL _ IN _ SRNC + DURA _ FOR _ 256 _ DL _ IN _ DRNC ) ⋅ 273.3kbps 100 ⋅ measuremen t period [s] ⋅ 1000
∑
(DUR _ PS _ BACKG _ 384 _ DL _ IN _ SRNC + DURA _ FOR _ 384 _ DL _ IN _ DR ) ⋅ 407 .7 kbps
AllCellsOv erRNC
100 ⋅ measuremen t period [s] ⋅ 1000
MAC _ D _ PDU _ TOT ⋅ 320 1000 ⋅ 1000 ⋅ measuremen t period [s]
Also the "Interactive" counters should be added to these formulas
Telcel – Nokia Siemens Networks confidential 142 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DMCU allocation load
• Table (taken from RNC capacity statement) shows the max DMCU capacity for different R99 bearers • The max HSDPA capacity is the same as the Iu capacity • Again, 0.8 is used to take peak-to-average ratios into account
Telcel – Nokia Siemens Networks confidential 143 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DMCU load factor DMCU allocation load factor, UMMT1 1 0.8 HSDPA load factor PS384 load factor PS256 load factor PS128 load factor PS64 load factor
0.6 0.4 0.2 0 Sep 1 - Sep 9
• The DMCU load factor is not yet a capacity problem • Note that in this RNC, a large part of the DMCU load is caused by R99 NRT bearers
Telcel – Nokia Siemens Networks confidential 144 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Number of RRC connected mode users Users in RRC connected mode, UMMT1
Nbr of users
4500 4000 3500 3000
cell_PCH cell_FACH cell_DCH
2500 2000 1500 1000 500 0 Sep 1 - Sep 9
• Number of RRC connected mode users can be calculated by: SUM_OPER_TIME_CELL_DCH + SUM_OPER_TIME_CELL_FACH + 10 * SUM_OPER_TIME_CELL_PCH -----------------------------------------------------------------------------------------------------------------------------------------------period_duration * 60
• Current usage is very far from the RNC450/450 limit of 100.000 users Telcel – Nokia Siemens Networks confidential 145 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
RNC CPU load Overview of RNC units: A2SUL (AAL2 Switching Unit) – Packet multiplexing and demultiplexing at the ATM level
DMCU (Data and Macro Diversity Combining Unit) – Provides RNC related user and control plane functions incl. FP processing
ICSU (Interface and Control Signalling Unit) – Handles the signalling over the interfaces – Participates in distributed RRM related tasks
RRMU (Radio Resource Management Unit) – Centralized RRM and call management
RSMU (Resource and Switch Management Unit) – Centralized resource management within RNC e.g. DSP resources – Performs conn
GPTU (GPRS Tunneling Protocol Unit) – Performs UP functions at the Iu-PS
SFU (Switching Fabric Unit) MXU (Multiplexer Unit) OMU (Operations and Maintenance Unit) NIS/NIP (Network Interface Unit) Telcel – Nokia Siemens Networks confidential 146 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Counters to monitor CPU load • The M592 family has counters to measure average and peak CPU load • The unit type ids are according to the following table • Unit ids is a running sequence from 0 up to the amount of units in the RNC capacity step • Units can reach 100% load and still provide stable operation – operator should start to consider expansion when the values in the table below is reached
Telcel – Nokia Siemens Networks confidential 147 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
M592C0 M592C1 1/1
Document Type Author Unit/Dept.
Unit type
utype_id unitid_id AVERAGE_LOAD PEAK_LOAD Document Title Date, Version For internal use
Unit name
Unit type code in report
OMU
Operation and maintenance unit
2
MXU
Multiplexer Unit
268
NIU
Network Interface Unit
301
NIP1
Network Interface Unit PDH
325
NIS1
Network Interface Unit STM-1
326
NIS1P
Protected Network Interface Unit STM-1
271
RSMU
Resource and Switch Management Unit
327
RRMU
Radio Resource Management Unit
328
ICSU
Interface Control and Signalling Unit
329
GTPU
GPRS Tunneling Protocol Unit
330
SFU
Switching Fabric Unit
337
A2SU
AAL2 Switching Unit
1484
DMCU
Data and Macro Diversity Combining Unit
1488
A2SP
AAL2 Switching Processor
324
DMPG
Data and Macro Diversity Processor Group
331
ICSU load ICSU average load 25
ICSU peak load 35 30
20
25 15
20
10
15 10
5
5
0
0 Sep 8 - Sep 14
Sep 8 - Sep 14
• High signalling load (e.g. caused by many SMSs) will increase the ICSU load
Telcel – Nokia Siemens Networks confidential 148 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DMPG load
• In addition to CPU load, the DSP counters can be checked (note: M592 counters are for the Central Processing Unit, not the DSPs inside the DMPG)
Telcel – Nokia Siemens Networks confidential 149 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DMPG load • Each DMPG is either dedicated to R99 traffic or can handle both HSDPA and R99 traffic • Some analysis should be done separately for each type • MML command ZWPI tells what each DMPG is doing – Mapping changes after a restart! DMPG load, RNC1 WPI:U:UNIT=ALL:;
Maximum average value during Sep 8 - Sep 14
UNIT INFORMATION
80 70
UNIT
DMPG POOL SETUP NAME
---------------------------------------------------------------
60 50
DMCU-0 DMPG-0
DCH DMPG
DMCU-0 DMPG-1
HS DMPG
DMCU-0 DMPG-2
DCH DMPG
40 30
DMCU-0 DMPG-3
HS DMPG
20
DMCU-1 DMPG-4
DCH DMPG
10
DMCU-1 DMPG-5
DCH DMPG
0
DMCU-1 DMPG-6
HS DMPG
DMCU-1 DMPG-7
DCH DMPG
DMCU-2 DMPG-8
DCH DMPG
Etc. Telcel – Nokia Siemens Networks confidential 150 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DCH DMPGs HS DMPGs
DMPGs
MXU and SFU load Peak MXU load
Average MXU load 2.5
4.5 4
2
3.5 3
1.5
2.5 2
1 0.5
1.5 1
0
0.5 0 Sep 8 - Sep 14
Sep 8 - Sep 14
Average SFU load, UMMT1 3.5
Peak SFU load, UMMT1 4.5 4
3
3.5 3
2.5 2
2.5 2
1.5
1.5 1
1 0.5
0.5 0
0 Sep 8 - Sep 14
• Load is not a concern Telcel – Nokia Siemens Networks confidential 151 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 8 - Sep 14
GTPU and A2SP load Average GTPU load 16
Peak GTPU load 20
14 15
12 10
10
8 6
5
4 2
0
0
Sep 8 - Sep 14
Sep 8 - Sep 14
Peak A2SP load
Average A2SP load 40
60
35
50
30
40
25 20
30
15
20
10
10
5
0
0 Sep 8 - Sep 14
• Load is not a concern Telcel – Nokia Siemens Networks confidential 152 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 8 - Sep 14
RRMU and RSMU load Average RRMU load
Peak RRMU load
6
16
5
14 12
4
10
3
8
2
6 4
1
2
0
0 Sep 8 - Sep 14
Sep 8 - Sep 14
Average RSMU load
Peak RSMU load
12
70
10
60 50
8
40
6
30 4
20
2
10
0
0 Sep 8 - Sep 14
• Load is not a concern Telcel – Nokia Siemens Networks confidential 153 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 8 - Sep 14
OMU and NIP1 load Average OMU load 18 16
Peak OMU load 100
14 12
80
10 8
60 40
6 4
20
2 0
0 Sep 8 - Sep 14
Sep 8 - Sep 14
Average NIP1 load 10
Peak NIP1 load 12
8
10 8
6
6
4 4
2
2 0
0 Sep 8 - Sep 14
• Load is not a concern Telcel – Nokia Siemens Networks confidential 154 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 8 - Sep 14
NIS1 and NIS1P load Peak NIS1 load
Average NIS1 load 12
4.5 4
10
3.5 3
8
2.5 2
6 4
1.5 1
2
0.5 0
0 Sep 8 - Sep 14
Sep 8 - Sep 14
Peak NIS1P load
Average NIS1P load 6
10
5
8
4
6
3 4 2 2
1 0
0 Sep 8 - Sep 14
• Load is not a concern Telcel – Nokia Siemens Networks confidential 155 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 8 - Sep 14
DMPG Load & DSP Allocation DMPG Load/Occupancy PPC or PQ2 Load => Unit Load Measurements
In RAS06, also RLC AM is in DSP
DSP Allocation => DSP Allocation and DSP Reservation Success Rates Measurements Telcel – Nokia Siemens Networks confidential 156 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DSP Performance Measurements in RNC (613/265H) XX_ALLOCATED_CAPACITY XX_CURRENT_CALLS XX_PEAK_CALLS XX_TOTAL_CALLS XX_FAILED_CALLS
CC - Common channel SC - Dedicated control channel RTD - Real-time data NRTD - Non real-time data RTS - Real-time speech
XX =
RT_PS - Packet switched real-time data HSDPA_COMMON - HSDPA common channel HSDPA_NRTD - HSDPA non-real-time data
Telcel – Nokia Siemens Networks confidential 157 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
KPI formulas for DSP performance DSP allocation failure ratio: XX_FAILED_CALLS ----------------------------------------------------------XX_FAILED_CALLS + XX_TOTAL_CALLS
Telcel – Nokia Siemens Networks confidential 158 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DSP Performance HSDPA calls, RNC1 70
2500
6% 5% 4%
NRT failure ratio HSDPA failure ratio
3% 2% 1% 0%
Peak nbr of calls
7%
60
2000
50 1500
40
1000
30 20
500
10
0
Sep 1 - Sep 14
Allocated capacity & failure ratio
DSP allocation failures, RNC1
0 Sep 1 - Sep 14
• • • •
Only failures related to R99 NRT and HSDPA were occuring in this RNC HSDPA failures seems not to be related to traffic....RNC s/w or h/w problems? R99 NRT failures follows more regular pattern Note that the DSP counters include both initial radio bearer establishment and radio bearer reconfiguration (e.g. upgrade of UL return channel from 64 kbps to 384 kbps) • Check M1022 counters to see if there are any failures in the initial radio bearer establishment: M1022C13 PS_SETUP_FAIL_DMCU_INT M1022C14 PS_SETUP_FAIL_DMCU_BGR
Telcel – Nokia Siemens Networks confidential 159 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Peak calls Allocated capacity Failure ratio x 10
DSP Performance
60
0.004%
50
0.003% 0.003%
40
0.002% 30 0.002% 20
0.001%
10
0.001%
0
0.000%
DMCU failure ratio
DMPG load (%)
DMPG load vs setup failures
Average DMPG load DMCU failure ratio
Oct 20 - Oct 27
• In this case, very, very few (0.003%) radio bearer establishments were prevented due to DMCU issues => The DSP failures shown in previous slide only affects radio bearer reconfigurations
Telcel – Nokia Siemens Networks confidential 160 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
DSP Performance Measurements in RNC (613/265H) RAS06: • M613C2 CC_PEAK_CALLS = Common Channel Services, creation of the cell(s) • M613C7 SC_PEAK_CALLS = Dedicated Control Channel services, number of SRBs • M613C12 RTD_PEAK_CALLS = Real time data service, CS streaming/conversational, incremented once pr call • M613C17 RTS_PEAK_CALLS = Real time speech service (AMR), incremented once pr call • M613C22 NRTD_PEAK_CALLS = Non-real time data, NRT PS, does not include HSDPA uplink, incremented twice pr call • M613C42 RT_PS_PEAK_CALLS = RT PS, same logic as previous • M613C57 HSDPA_NRTD_PEAK_CALLS = Non-real time data, NRT PS using HS-DSCH, incremented twice per call (in RAS05.1: three times per call). Includes HSDPA UL R99 and HSUPA return channel
Telcel – Nokia Siemens Networks confidential 161 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Peak number of simultaneous users Peak nbr of calls, RNC1
Peak nbr of HSDPA users in RNC UMMT1, RNC450/450 2500 6000 2000
Users
5000
AMR NRT PS HSDPA
1500
4000
Peak no of HSDPA calls
3000
CD2 capacity (64 kbps) ED2.0 Capacity (64 kbps)
2000
1000 500
1000 0
0 Sep 1 - Sep 9
Sep 1 - Sep 14
• Number of HSDPA users comfortably below current RNC capacity • ED2.1 will further increase RNC capacity • However, if all R99 NRT users start to use HSDPA (by solving other HSDSCH accessibility problems), there may be capacity problems • Exceeding the threshold for the number of simultaneous users is one of the reasons why SETUP_FAIL_RNC_HS_DSCH_INT/BGR might peg
Telcel – Nokia Siemens Networks confidential 162 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Peak number of simultaneous users HSDSCH rejections due to RNC 1000
100.0%
800
80.0%
600
60.0%
400
40.0%
200
20.0%
0
Rejection ratio
Nbr of users
RNC expansion (RNC450/150 to RNC450/450)
0.0% March 20 - 28 Peak number of users
RNC ratio
• Nice correlation between SETUP_FAIL_RNC_HS_DSCH_INT/BGR and number of HSDPA users in RNC => Capacity issue
Telcel – Nokia Siemens Networks confidential 163 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
HS-DSCH setup failure due to RNC - software stability HS-DSCH setup failures due to RNC 60000 50000 40000 30000 20000 10000
CD1.0
CD2.0
20081019
20081017
20081016
20081014
20081013
20081011
20081010
20081008
20081007
20081005
20081004
20081002
20081001
20080929
20080928
20080926
20080925
20080923
20080922
0
CD2.4
• SETUP_FAIL_RNC_HS_DSCH_INT/BGR disappears after RNC restart => Not capacity issue! Telcel – Nokia Siemens Networks confidential 164 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Agenda
• What is capacity management and why is it needed? • Brief introduction to RAS06 performance monitoring • How to monitor – Air Interface – BTS – Iub – RNC – Iu-CS, Iu-PS, Iur
Telcel – Nokia Siemens Networks confidential 165 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Usage - M530 vs M5106 • Both M530 and M5106 contain counters that allow us to calculate the usage of the Iub links – M530 is optional – M530 covers Iub, Iur, Iu-CS, Iu-PS. M5106 covers Iub only – M530 also has counters that enable us to calculate cell loss in the ATM interfaces – Maximum 1024 VCCs can be monitored by M530 • AAL2 UP, AAL2 SIG, C-NBAP, D-NBAP, O&M VCCs are included in both measurements • For M530, separate mapping table between BTS/cell id and interface id is Counter_id Counter name needed rnc_id
M530C0 M530C1 M530C2 M530C3 M530C4 M530C5 M530C6 M530C7 Telcel – Nokia Siemens Networks confidential 166 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
if_id vpi_id vci_id period_start_time period_duration IN_TOT_CELLS_VC EG_TOT_CELLS_VC IN_REC_CELLS_VC IN_QUEUED_CELLS_VC IN_CAP_VC EG_REC_CELLS_VC EG_QUEUED_CELLS_VC EG_CAP_VC
Iur utilization Iur utilization, RNC1 => RNC2 60% 50% 40% Ingress Egress
30% 20% 10% 0% Sep 16 - Sep 29
Ingress utilization = IN_TOT_CELLS_VC/(period_duration*60) --------------------------------------------------------IN_CAP_VC Telcel – Nokia Siemens Networks confidential 167 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Counters from M550:
Iur reservation/CAC rejections Iur reservation, RNC1 => RNC2
M550C0 M550C1 M550C7 M550C8 M550C9 M550C10
AAL2_PATH_GUAR_CELL_RATE SUM_RESERVED_CELL_RATE NBR_SAMPLES AAL2_RM_SUCCEEDED AAL2_CAC_REJECTED AAL2_HW_REJECTED
Iur utilization vs reservation Sep 16 - Sep 29
80% 60%
Reservation CAC rejection
40% 20%
Average Iur reservation
100% 100% 80% 60% 40% 20% 0% 0%
0%
20%
60%
reservation much higher than utilization – In this particular network, reservation about twice the utilization – Depends on network parameters, e.g. 16 kbps UL return channel usage, Throughput Based Optimization etc.
50%
CAC rejection
– In networks with high share of PS traffic,
3G RAN Capacity / Poul Larsen / March 2009
100%
80%
100%
Sep 16 - Sep 29
reservation in Iur, activity factor of 1 is used
Telcel – Nokia Siemens Networks confidential 168 © Nokia Siemens Networks
80%
Iur reservations vs. CAC rejections
• When NRT PS calls go through the CAC
rejections starts to occur
60%
Average Iur utilization
Sep 16 - Sep 29
• Once average reservation reaches ~60%, CAC
40%
40% 30% 20% 10% 0% 0%
20%
40%
60%
Average Iur reservation
Iur CAC rejections vs SHO failures RNC1 => RNC2
RNC1 => RNC2, Sep 16 - Sep 29
80% 70% 60% Iur reservation failure ratio Drift SHO failure ratio
50% 40% 30% 20% 10%
Drift SHO failure ratio
80% 70% 60% 50% 40% 30% 20% 10% 0% 0%
0%
10%
20%
30%
40%
Iur reservation failure ratio
Sep 16 - Sep 29
• If there is congestion on the Iur interface, Soft Handovers across RNC borders will suffer • By analysing M1013 counters, SHO failure ratio pr adjacency can be calculated, and from this the Drift SHO failure ratio can be found • Good correlation between Iur congestion and Drift SHO failure ratio
Telcel – Nokia Siemens Networks confidential 169 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
50%
Iur CAC rejections vs SHO failures Iur reservation & failures, RNC1 => RNC2 100% 80% Reservation CAC rejection Drift SHO failures
60% 40% 20% 0% Oct 20 - Nov 9
• Sites rehomed from RNC1 to RNC 2 on Oct 30 and on Nov 5 – Less Iur traffic – CAC rejections are now zero – SHO failures across the RNC border reduced significantly
Telcel – Nokia Siemens Networks confidential 170 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iur, nbr of connection ids Nbr of Iur connections, RNC1 250 200 150
Peak Average
100 50 0 Sep 16 - Sep 26
Counters from M550: M550C4 M550C6 M550C7
SUM_AAL2_CONNECTIONS MAX_AAL2_CONNECTIONS NBR_SAMPLES
Telcel – Nokia Siemens Networks confidential 171 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iu-CS user plane Iu-CS User plane reservation, PCR = 3 x 12000 cps
Iu-CS user plane utilization, PCR = 3 x 12000 cps 25%
30%
20%
Ingress 1 Ingress 2 Ingress 3 Egress 1 Egress 2 Egress 3
15% 10% 5% 0%
25% 20%
Reservation, VCC1 Reservation, VCC2 Reservation, VCC3 Failure ratio
15% 10% 5% 0%
Sep 9 - Sep 14
• Pretty good match between utilization and reservation • No failures in this case as the reservation is low • Evenly distribution of load between multiple VCCs
Telcel – Nokia Siemens Networks confidential 172 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Sep 5 - Sep 14
Iu_CS user plane utilization vs reservations When comparing the Utilisation (M530) and CAC reservation (M550) it can be seen that the usage is ~7/8 from reservation The CAC reservation for Iu_CS is a lot closer to the actual usage compared to the Iub, this is due to no PS calls and high concentration of traffic
ATM_Utilisation vs CAC_Reservation
70.00%
60.00%
50.00%
40.00%
30.00%
20.00%
10.00%
0.00% 0.00% 10.00% 20.00% 30.00% Telcel – Nokia Siemens Networks confidential 173 © Nokia Siemens Networks 3G RAN Capacity / Poul Larsen / March 2009
40.00%
50.00%
60.00%
70.00%
80.00%
Iu-CS user plane & Cid Iu-CS, number of connections 250 200
Max, VCC1 Max, VCC2 Max, VCC3 Average, VCC1 Average, VCC2 Average, VCC3
150 100 50 0 Sep 9 - Sep 14
•In this case, clearly below the limit of 248 connections pr VCC • But if only one VCC, the capacity limit would have been reached
Telcel – Nokia Siemens Networks confidential 174 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iu-CS control plane The Iu-CS Control Plane size should be around 6% of the User Plane and general rule is that the Control Plane load should not exceed 20% (higher load can mean delayed RANAP messages and SMSs) • There are two alarms that indicate the status of the control plane load – 0026 SIGNALING LINK LOAD OVER THRESHOLD ▪ If the load is higher than the defined threshold (200 mErl by default) during 5 min measurement period then the alarm is generated (this means that teh alarm is generated in case the load is more than 20%)
– 0016 SIGNALLING LINK CONGESTION LEVEL EXCEEDED ▪ The congestion level defined for the signalling link has been exceeded ▪ Alarm is triggered immediately when certain congestion level has been exceeded (there are three different congestion levels that can be defined)
Telcel – Nokia Siemens Networks confidential 175 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iu-CS control plane Iu-CS signalling utilization, PCR = 4500 cps 6% 5% 4% Ingress Egress
3% 2% 1% 0% Sep 9 - Sep 14
• In this case utilization comfortably lower than the 20% threshold
Telcel – Nokia Siemens Networks confidential 176 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iu-PS • Iu-PS is IP-over-ATM interface, so no need to worry about over• •
•
•
reservation like in Iur Iu-PS utilization can be monitored from M530 or from M801 counters M801 family: M530 measures both User Plane and Control Plane, M801 measures only User Plane M530 measures ATM cells, M801 measures bytes (IP/UDP/GTP headers are excluded) Both measurements are optional
Telcel – Nokia Siemens Networks confidential 177 © Nokia Siemens Networks
Counter_id Counter name rnc_id utype_id unitid_id period_start_time period_duration period_duration_sum M801C0 INPUT_BYTES_TOTAL_UDP M801C1 INPUT_IP_PACKETS_TOTAL M801C2 INPUT_TRAF_BYTES_TC_CONV M801C3 INPUT_TRAF_BYTES_TC_STREAM M801C4 INPUT_TRAF_BYTES_TC_INTERAC M801C5 INPUT_TRAF_BYTES_TC_BACKGR M801C6 OUTPUT_BYTES_TOTAL_UDP M801C7 OUTPUT_IP_PACKETS_TOTAL M801C8 OUTPUT_TRAF_BYTES_TC_CONV M801C9 OUTPUT_TRAF_BYTES_TC_STREAM M801C10 OUTPUT_TRAF_BYTES_TC_INTERAC M801C11 OUTPUT_TRAF_BYTES_TC_BACKGR M801C12 ECHO_REQUEST_RECEIVED M801C13 ECHO_RESPONSE_RECEIVED M801C14 ECHO_RESPONSE_SENT M801C15 ERROR_INDICATIONS_RECEIVED M801C16 ERROR_INDICATIONS_SENT M801C17 EXTENS_HEAD_NOTIF_RECEIVED M801C18 AVERAGE_NBR_OF_GTP_TUNNELS M801C19 MAX_NBR_OF_GTP_TUNNELS
3G RAN Capacity / Poul Larsen / March 2009
Release
RN2.2ED RN2.2ED not supported RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED not supported RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED RN2.2ED
Iu-PS UP usage threshold The peak to average ratio should be taken into account when setting the limits for Iu-PS max usage • Typically average usage of 80% is enough to guerantee peak performance • Peak to average ratio 1.25
Telcel – Nokia Siemens Networks confidential 178 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Iu-PS Iu-PS user plane throughput (M530, 53 bytes/cell), GTPU-1
25
25
20
20
15
Downlink (Mbps) Uplink (Mbps)
10
Mbps
Mbps
Iu-PS user plane throughput (M801, excl. headers), GTPU-1
15
Downlink (Mbps) Uplink (Mbps)
10
5
5
0
0 Sep 15 - Sep 25
Sep 15 - Sep 25
Iu-PS RANAP utilization (M530), ICSU-4 7% 6% 5% 4%
DL load
3%
UL load
2% 1% 0% Sep 15 - Sep 25
Telcel – Nokia Siemens Networks confidential 179 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
Thank you!
Telcel – Nokia Siemens Networks confidential 180 © Nokia Siemens Networks
3G RAN Capacity / Poul Larsen / March 2009
View more...
Comments
