Capacity CCH Load & Paging

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WCDMA RAN Optimisation

CCH Load & Paging Optimisation

Latest version can be found:

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Introduction

•

• This material Covers Uplink and This material Covers Uplink and Downlink common channel monitoring. Paging capacity togetherDownlink common channel monitoring. Paging capacity together

with 24 kbps paging channels is explained.

•

• There is Recorded SVU session available covering part of the materialThere is Recorded SVU session available covering part of the material •

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4 © No© Nokia 201kia 2014 4 --CCH LoCCH Load ad & Pag& Paginging – –v1.2 v1.2 --Kirsi Kirsi TeravTeravaineainen n --D495D495060706077171

Content

Common Channel Load Monitoring

Uplink Channel Monitoring

Downlink Channel Monitoring

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CCH Loa

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Common Channel load monitoring includes:

Common Channel load monitoring includes: •

• RACH pre-ambleRACH pre-amble

•

• RACH-c and RACH-u loadRACH-c and RACH-u load •

• FACH-c and FACH-u loadFACH-c and FACH-u load •

• PCH loadPCH load •

• SCCPCH power loadSCCPCH power load

From efficient traffic scheduling point of view the CCH load of each cell

From efficient traffic scheduling point of view the CCH load of each cell needs to be measured, forneeds to be measured, for

example F

example FACH-c, FACH-c, FACH-u and PCCH transport channeACH-u and PCCH transport channels can be ls can be multiplexed into same SCCPCHmultiplexed into same SCCPCH

which causes some prioritization of the RLC SDUs

which causes some prioritization of the RLC SDUs This prioritization might lead to deletion of other

This prioritization might lead to deletion of other transport channel’s RLC SDUs therefore it istransport channel’s RLC SDUs therefore it is

important to measure the loads of the individual transport channels

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6 © No© Nokia 201kia 2014 4 --CCH LoCCH Load ad & Pag& Paginging – –v1.2 v1.2 --Kirsi Kirsi TeravTeravaineainen n --D495D495060706077171

Content

Common Channel Load Monitoring

Uplink Channel Monitoring

Downlink Channel Monitoring

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Uplink Channel Mapping

• A single RACH transport channel is used for both, control plane signaling and user plane data.

• RACH is mapped to PRACH onto PRACH

physical channel which makes use of contention based access procedure i.e.

there is probability that collisions occur when multiple UE attempt to make use of the

PRACH.

• PRACH is separated in the preamble part

and a message part. Preambles are used to gain access to PRACH message time slot and to ensure that the message is

transmitted with sufficient uplink power. CCCH DTCH RACH EDCH DCH PRACH E-DPDCH E-DPCCH HS-DPCCH DPCCH DPDCH DCCH Logical

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8 © Nokia 2014 - CCH Load & Paging – v1.2 - Kirsi Teravainen - D495060771

Measuring the RACH Channel

Random access channel load (RACH) can be measured at the RACH preamble and transport channel levels.

• WBTS measures the number of acknowledged (ACK/NACK) PRACH preambles per 20 ms RACH

frame, averages over RRI period and sends the measurement to RNC. NOTE: the averaged value

is rounded to closest integer, thus low PRACH load is not measured accurately

• The maximum preamble capacity is 60 preambles per RACH frame of 20 ms (4 signatures * 15 slots)

RNC_978b indicates the preamble load.

• The RACH preamble load and transport channel load are inter-connected.

• Every positively acked preamble will correspond one sent RACH message (RACH-c of RACH-u).

• The BTS can acknowledge in one second 60 * 1/20ms = 3000 preambles/sec.

• BTS can decode RACH_capacity (default = 2) / 10 ms = 200 RACH messages/sec

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Measuring the PRACH Preamble capacity

The number of acknowledged PRACH preambles per 20ms frame during averaged over the RRI period can be calculated based on the counters below

• M1000C176 SUM_RACH_ACK_PREAMBLES

• M1000C177 DENOM_RACH_ACK_PREAMBLES

RNC_978a can be used to measure PRACH message load

• The maximum preamble capacity is 60 preambles per RACH frame of 20 ms

BLES _ACK_PREAM DENOM_RACH LES ACK_PREAMB SUM_RACH_ eLoad RACHMessag b_AverageP 978 RNC_ 

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Measuring the PRACH Preamble capacity

0 % 5 % 10 % 15 % 20 % 25 % 30 % 0 . 0 1 0 . 1 2 0 . 2 4 0 . 3 6 0 . 4 7 0 . 5 9 0 . 7 1 0 . 8 2 0 . 9 4 1 . 0 6 1 . 1 7 1 . 2 9 1 . 4 1 1 . 5 2 1 . 6 4 1 . 7 6 1 . 8 7 1 . 9 9 2 . 1 1 2 . 2 2 2 . 3 4 2 . 4 6 2 . 5 7 2 . 6 9 2 . 8 1 2 . 9 2 3 . 0 4 3 . 1 6 3 . 2 7 3 . 3 9 R A C H m e s s a g e b l o c k i n g

Number of RACH preamles per frame (RNC_978b)

RACH message decoding blocking probability

P(Capacity=2) P(Capacity=3) P(Capacity=4)

The RACH message decoding blocking can be estimated with Erlang B equation (although this is not 100% correct for slotted system like RACH and to system with

re-transmission).

Calculation as function of RACH preample load RNC_978b. It indicated that the level of 1.5 preambles / 20 ms will result in 5% blocking on RACH message decoding. Blocking will cause the BTS to send a negative acknowledgement and UE to apply N300 and T300 for re-transmission. A load of 1 preamble per 20 ms (1/60 =

about 2% preamble load = 30% total RACH message load) can be used as triggering point for RACH_capacity increase.

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Measuring RACH channel

• Both data (RACH-u) and signaling data (RACH-c) throughput can be measured

• The counters are incremented when the MAC-c sends to the RRM an internal message (every 2

seconds, including 4 samples) with the common channel information

• RACH throughput

• RACH-u throughput formula provides RACH transport channel User Plane data throughput

• RACH-c throughput formula provides RACH transport channel Control Plane data throughput

3 M_ RACH_DENO 61 C 1000 M THROUGHPUT AVE_RACH_ 60 C 1000 M throughput RACH _  4 M_ RACH_DENO 63 C 1000 M GHPUT DATA_THROU AVE_RACH_ 62 C 1000 M rouhgput RACH-u th  4 M_ RACH_DENO 63 C 1000 M GHPUT DATA_THROU AVE_RACH_ 62 C 1000 M 3 M_ RACH_DENO 61 C 1000 M THROUGHPUT AVE_RACH_ 60 C 1000 M roughput RACH-c th  

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Measuring the RACH Channel

The Random Access Channel capacity depends on theRACHCapacity parameter

• The RACHCapacity defines the HW capacity reserved for a RACH transport channel in the BTS • RACH Capacity is indicated as the number of decoded RACH messages in a 10 ms radio frame

• Defines also the number of used PRACH preamble signatures used

• Range 1,2,3,4 (messages) and default = 2

For example if theRACHCapacity = 2 (def) then it means that the BTS can decode 2 RACH messages

in every 10ms radio frame and therefore the decoding capacity is 2 RACH PDUs * 45B/10ms = 9kBps = 72kbps i.e. 2 RACH TBs * 360bit/10ms = 72kbps

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Measuring the RACH Channel

Iub capacity is according to the table below, depending on theRACHCapacity parameter (1,2,3,4)

• Note the capacity impact on iub as the capacity above is required as per each cell so there is a clear impact on how many e.g. voice users 1*E1 can support in case capacity for RACH is increased

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Example: RACH-c and RACH-u loading

• Examples of RACH load (TP / TP_max) in high traffic cells (RACH_capacity = 2)

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Measuring the RACH Channel

• The PRACH load is dependent upon the number of UE making use of the RACH transport channel.

The RACH transport channel may be used for the transfer of either user plane or control plane information.

• The PRACH load can be reduced by:

• Increasing the RACH_capacity parameter

• Evaluate whether or not there are large quantities of signaling generated by cell, URA, location area

or routing area updates. If so, consider adjusting the area boundaries

• Evaluate whether or not there is excessive user plane data transfer within CELL_FACH. If so,

consider reducing the RLC buffer thresholds that trigger the transition to CELL_DCH

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Content

Common Channel Load Monitoring

Uplink Channel Monitoring

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Downlink Channel Mapping

P-CCPCH P-CPICH P/S-SCH AICH HS-PDSCH* DPDCH S-CCPCH PICH DPCCH HS-SCCH E-HICH PCH BCH DCH FACH HS-DSCH CTCH DCCH CCCH PCCH BCCH DTCH

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S-CCPCH Configuration 1

• This configuration limits the PCH bit rate to 8 kbps

• The PCH is multiplexed with the FACH-u and FACH-c

• The PCH always has priority

• SF64 is required to transfer the FACH-u and FACH-c bit rates Logical channel Transport channel Physical channel DTCH DCCH CCCH BCCH PCCH FACH-u FACH-c PCH SCCPCH 1 SF 64

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24kbps Paging Channel

• Earlier versions support a PCH bitrate of 8 Kbps

• Transport block size of 80 bits & 10 ms TTI

• PCH bitrate of 8 kbps limits the capacity of paging messages to a single paging record, i.e. single

paging record can be broadcasted per 10 ms TTI

• RU20 support PCH bitrate of 8 and 24 kbps, 24kbps PCH is based upon

- Transport block size of 240 bits & 10 ms TTI

- 24kbps paging channel require activation of second SCCPCH channel

Paging Type 1 message

maxPage = 8 3GPP allows up to 8

paging records per paging message

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S-CCPCH Configuration 2

• PCH24kbpsEnabled is

configured to enabled with this configuration

• Increases the PCH bit rate

to 24 kbps

• The PCH is allocated its own S-CCPCH

• SF128 is allocated to the

PCH to support the increased bit rate

Logical channel Transport channel Physical channel DTCH DCCH CCCH BCCH PCCH FACH-u FACH-c PCH SCCPCH 1 SCCPCH 2 SF 64 SF 128

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• Channelisation code for 24 kbps PCH uses a larger section of the code tree

• HSDPA cannot use 15 HS-PDSCH codes when HSUPA 2 ms

TTI is enabled with 24 kbps PCH

• The transmit power of the S-CCPCH is defined using the

parameters:

• PtxSCCPCH1 (PCH/FACH or only FACH)

• PtxSCCPCH2 (Standalone PCH)

• PtxSCCPCH3 (S-CCPCH for SAB)

• PtxSCCPCH2SF128 (Standalone PCH SF128 / 24kbps)

• The PtxSCCPCH2SF128 parameter defines the transmit

power of the S-CCPCH used to transfer the 24 kbps PCH

• All parameters define the transmit power of the data bits (rather than the transmit power of the TFCI and Pilot bits)

24 paging Channel - Impact to Code and power capacity

S-CCPCH 1 Cch,256,1 Cch,256,2 Cch,256,3 Cch,128,4 Cch,128,5 CPICH P-CCPCH AICH PICH Cch,64,1 Cch,256,14 E-AGCH HS-SCCH E-HICH & E-RGCH

S-CCPCH 2 Cch,128,6

Cch,16, 0

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Common Channel Load - SCCPCH

SCCPCH load is used by PS in downlink channel type selection algorithm

• Average SCCPCH load is given as percentage value (defined as ratio between the SCCPCH transmission power and the CPICH power)

• incremented when the MAC-c sends to the RRM an internal message (every 20 seconds, including 0.5s sampling period) with the common channel information

• SCCPCH load is one criteria for switching from common channel to dedicated channel

• If a single S-CCPCH is configured then this KPI is applicable to that channel

• If two S-CCPCH are configured then this KPI is applicable to the S-CCPCH encapsulating the PCH transport c hannel Both counters are incremented every CCH Load Measurement Period

• Num is incremented by the value received in the measurement • Denom is incremented by the number of measurements

% 0 AD_DENOM_ SCCPCH_LO 65 C 1000 M LOAD H_INC_PCH_ AVE_SCCPC 64 C 1000 M erageLoad a_SCCPCHAv 979 RNC_ 

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SCCPCH Monitoring

_–

FACH-u and FACH-c

• The load of different transport channels (FACH-u, FACH-c and PCH) can be monitored separately

• FACH-u and FACH-c load can be calculated using Formulas below

• RNC_2029b FACH-u Load Ratio provides information about the FACH transport channel User Plane data load,

by dividing the FACH channel throughput by the corresponding transport channel max bit rate to get the load ratio.

• RNC_2030b FACH-c Load Ratio provides information about the FACH transport channel Control Plane data

load, by dividing the FACH channel control data throughput by the corresponding transport channel max bit rate to get the load ratio.







1



36000 100 2029 * OM_ A_TPUT_DEN FACH_U_DAT Sum CPCH DATA_TP_SC AVE_FACH_U Sum * u b_FACH RNC_   33600 1 1 _ _ 100 2030                     

 FACH_U_DAT A_TPUT_DEN OM_

CCPCH) UDATA_TP_S (AVE_FACH_ ENOM_ TOT_TPUT_D FACH_USER_ TPUT TOT SER AVE_FACH_U * b RNC_

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Example: FACH-c and FACH-u loading

• FACH and S-CCPCH load from two high traffic cells

• RACH-c and FACH-c have higher priority, also the user plane allocation is limited when RACH or

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Paging Types and PCH Load

When the network needs to contact a certain user a Paging procedure will take place.

• The paging method used depends on the UE RRC state:

- IDLE: Paging Type 1 - over PCH - LA/RA level - CN originated

- Cell/URA-PCH: Paging Type 1 - over PCH - Cell/URA level - CN/RNC origin. - Cell-DCH/Cell-FACH: Paging Type 2 / over SRB / Cell level

Only Paging Type 1 affects the PCH Load

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Paging Channel capacity(I)

• NSN RAN, until RU10 (RN4.0) sw release, provides an 8 kbps PCH transport channel

on the S-CCPCH.

• The PCH TBS is 80 bits allowing to carry a single paging record per TTI (10ms)



100 paging records per second



a single cell can thus page maximum 100 UEs per second

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Paging Channel capacity(II)

• This capacity could get exhausted due to a combination of reasons (high

traffic, LAC oversize,…). In case of too high Paging Load a considerable

percentage of paging messages could get lost causing a bad user experience

(‘non

-reachability

’ of UEs due to missing pages).

• It should be taken into account that S-CCPCH can be shared with the FACH-c

and FACH-u but PCH always has priority. This means that a high Paging load

has an impact upon FACH capacity when single S-CCPCH is configured.

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MSS/VLR counters for Paging

MSS/VLR counters for Paging attempts (originated by MSC only), successes and failures per LAC in measurement table M353.

• Available in VLR measurement report, paging per LAC (353/161H)

Counter id Counter name Description

M353B3C1 PAGING ATTEMPTS PER LAC Number of initiated Pagings from the VLR to the specific LA.

M353B3C2 SUCCESSFUL PAGINGS PER LAC Number of successf ul Pagings in the VLR in the speci fic LA

M353B3C3 PAGING ATTEMPT WITH IMSI PER LAC,

SUCCESSFUL

The number of paging attempt with IMSI for successful pagings (ATT#(SUCC)) counters show how many paging requests were sent to the A and Iu interfaces (from the MSC) per LAC when the paging was successful.

M353B3C4 PAGING ATTEMPT WITH TMSI PER LAC,

SUCCESSFUL

The number of paging attempt with TMSI for successful pagings (ATT#(SUCC)) counters show how many paging requests were sent to the A and Iu interfaces (from the MSC) per LAC when the paging was successful

M353B3C5 PAGING ATTEMPT WITH IMSI PER LAC,

FAILED

The number of paging attempt with IMSI for failed pagings (ATT#(FAIL)) counters show how many paging requests were sent to the A and Iu interfaces (from the MSC) per LAC when the paging failed.

M353B3C6 PAGING ATTEMPT WITH TMSI PER LAC,

FAILED

The number of paging attempt with TMSI for failed pagings (ATT#(FAIL)) counters show how many paging requests were sent to the A and Iu interfaces (from the MSC) per LAC when the paging failed.

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RNC KPIs for Paging attempts

• The mentioned counters can be used to monitor the number of paging messages per cell:

• In order to count only the amount of pages sent on PCH channel the following KPI can be used

(Paging Type 2 excluded):

_ATT 2 E_ PAGING_TYP 27 C 1006 M RIG _ATT_RNC_O 1 E_ PAGING_TYP 25 C 1006 M IG _ATT_CN_OR 1 E_ PAGING_TYP 25 C 1006 M Cell empts per Paging Att             

_

        RIG _ATT_RNC_O 1 PE_ _PAGING_TY 26 C 1006 M IG _ATT_CN_OR 1 PE_ _PAGING_TY 25 C 1006 M per Cell Attempts 1 e Paging Typ

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RNC KPI for Paging Load

The AVE_PCH_THROUHGPUT counter, divided by the denominator, gives Average PCH throughput

UPDATED: When the RNC/MAC-c sends an internal message with common channel information to the Radio Resource Management in the RNC

MAC-c sends this message at 2-second intervals

Taking into account that the PCH physical limit is 8kbps the Average PCH Throughput can be normalized to this value providing PCH Load in percentage:

 

bps 0 M GHPUT DENO PCH THROU 71 C 1000 M T THROUGHPU AVE PCH 70 C 1000 M ut H Throughp Average PC  Not suitable if 24 kbps paging CH

 

_{ }

% 8000 bps ut H Throughp Average PC 100 a_PCH Load 2031 RNC_   Not suitable if 24 kbps paging CH

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Average PCH throughput daily distribution

• The average PCH Throughput

approaches 7kbps several times per day

• This can be assumed as a clear

symptom of PCH congestion during the traffic peak hour.

PCH physical limit

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Average PCH Load daily distribution

• Average PCH Load equal to

80..90% at RNC≡LAC level

• In a such highly congested

situation a high rate of missing pages is expected and a LAC splitting needs to be planned

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VLR Paging SR vs PCH Thp: congestion

•

The Paging success rate starts to

decrease when PCH throughput exceeds 4-4.5kbps, that is a PCH Load of 50-55% approximately and is below 90% when PCH

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VLR Paging SR vs PCH Thp: no congestion

• Interesting to compare the

correlation shown by a nearly unloaded RNC

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Received Page/s by CN vs PCH Load

• A quasi-linear relation exists up to

45% PCH load and starts to become non-linear at 50% meaning that CN needs to send more paging (i.e. re-paging) because RAN is not able to properly serve them.

• Threshold of 50% PCH Load

confirmed as Rule of Thumb to trigger PCH Load optimization

M1003C36 – Received paging messages from CN (s)

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Paging Load Optimization: LAC splitting

• Enabling a 2nd S-CCPCH without 24 kbps paging channel will not increase the PCH capacity (8kbps),

but only FACH capacity.

• LAC splitting is needed to reduce the Paging Load

• LAC split methodology is based on the number of BH MTCs: the target is to balance BH MTC on hour

level

LAC splitted

Weekend normal traffic decrease

ALL_ATTS MTC_CONV_C M1001C32 TS UNKNOWN_AT MTC_CAUSE_ M1001C60 TTS IOR_SIGN_A MTC_LOW_PR M1001C56 (CS) Pagings Answered   

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Paging Load Optimization: RAN1202 (RU20)

24 kbps Paging Channel

• Provides support to PCH bit rate of 24 kbps

next to 8 kbps

• 24 kbps PCH is based upon a TBS of 240 bits and TTI of 10 ms

• Up to 8 paging records per TTI allowed

(3GPP)  max 8 * (RU10) PCH Capacity

• Requires # S-CCPCH > 1 (PCH is still allocated its own S-CCPCH)

• SF is decreased from 256 to 128 compared to

the 8 kbps configuration in order to support the increased bitrate

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TN148 - PCH throughput increase- 24 kbps PCH

24 kbps Paging Channel feature can increase the paging channel capacity three times higher from the 8 kbps

• Transport block configuration used in the PCH channel have been modified so that larger block size is used if 24 kbps PCH is enabled

• The result of this change is that PCH channel throughput measured by formula

Shows higher values in RU20 than in RU10 even if the amount of paging messages would remain the

same. It’s because the counter is based on measuring physical transport blocks in the Iub interface and those blocks are sent with same size even if there isn't paging messages to fill in all the blocks.

Not suitable if 24 kbps paging CH ) _ _ _ _ ( ) _ _ _ ( _ 0 DENOM THROUGHPUT PCH 71 C 1000 M THROUGHPUT PCH AVE 70 C 1000 M throughput PCH 

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The best way to measure paging channel utilization is based on

These counters tell the amount of paging messages successfully scheduled in the Iub interface -8 kbps PCH can transfer about 100 paging messages per second,

-24 kbps channel capacity is about 400...500 messages per second (depends on paging type). When the amount of paging messages exceeds 50% of the nominal capacity, its good time to start thinking about actions to reduce paging channel load to avoid degradation in paging success rate. • 50 msg/s for 8 kbps PCH • 250 msg/s for 24 kbps PCH

TN148 - PCH throughput increase

_–

24 kbps PCH

        RIG _ATT_RNC_O 1 PE_ _PAGING_TY 26 C 1006 M IG _ATT_CN_OR 1 PE_ _PAGING_TY 25 C 1006 M per Cell Attempts 1 e Paging Typ

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Example: Updating 8 kbps to 24 kbps PCH

Configuration changes

• 08.11.2010

- 24 kbps PCH, 2nd SCCPCH • 09.11.2010

- Inactivity parameter changes (this is not releated to 24 kbps PCH changes)

Object Parameter Name Abbreviated Name Actual value new value RNC Low utilization time to trigger of the MAC-d flow MACdflowutilTimetoTrigger 2 sec 0 sec * RNC Window size of the MAC-d flow throughput measurement MACdflowthroughputAveWin 3 sec 2 sec RNC Low throughput time to trigger of the E-DCH MAC-d flow EDCHMACdFlowThroughputTimetoTrigger 5 sec 1 sec RNC Window size of E-DCH MAC-d flow throughput measurement EDCHMACdFlowThroughputAveWin 3 sec 2 sec RNC Uplink traffic volume measurement low threshold TrafVolThresholdULLow 128 bytes 256 bytes RNC UL/DL activation timer UL_DL_activation_timer 2 sec 1 sec RNC Inactivity timer for uplink 8kbps DCH InactivityTimerUplinkDCH8 5 sec 2 sec RNC Inactivity timer for uplink 16kbps DCH InactivityTimerUplinkDCH16 5 sec 2 sec RNC Inactivity timer for uplink 32kbps DCH InactivityTimerUplinkDCH32 5 sec 2 sec

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PCH Utilisation, TN148 method

• Number of sites per load level with 8 kbps and 24 kbps PCH, using TN148 method

=(PAGING_TYPE_1_ATT_CN_ORIG + PAGING_TYPE_1_ATT_RNC_ORIG)/3600 =(PAGING_TYPE_1_ATT_CN_ORIG + PAGING_TYPE_1_ATT_RNC_ORIG)/3600/4 • 8 kpbs PCH -> 100 pages/s • 24 kbps PCH -> 400-500 pages/s

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PCH utilisation, Nov 5, 8 kbps PCH

Results using old method with 8 kbps PCH

PCH utilisation Nov 5 0 200 400 600 800 1000 1200 1400 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 Utilisation [%] W ce ll ho ur co un t 0 % 20 % 40 % 60 % 80 % 100 % 120 % C D F %

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PCH Utilisation Nov 5, 8 kbps PCH - TN148 method

• Results using TN148

method with 8 kbps PCH

Similar kind of results with both method when 8 kbps PCH in use

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PCH loading and FACH throughput

One SCCPCH and 8 kbps PCH.

•When SCCPCH is heavily loaded there is risk that FACH messages are delayed or even dropped. This may cause reconfiguration process failures and PS RABs drops.

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Example: Average Paging load RNC15

0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0 500.0

Paging Load (Paging per second) RNC15

PPS Max PPS Capacity Preventive action Target

2nd_SCCPCH and 24 kbps PCH activated

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Example: Paging success rate from LAC350 (MSS counters)

90 91 92 93 94 95 96 97 98 99 100 2 0 1 0 / 1 1 / 2 9 2 0 1 0 / 1 1 / 3 0 2 0 1 0 / 1 2 / 0 1 2 0 1 0 / 1 2 / 0 2 2 0 1 0 / 1 2 / 0 3 2 0 1 0 / 1 2 / 0 4 2 0 1 0 / 1 2 / 0 5 2 0 1 0 / 1 2 / 0 6 2 0 1 0 / 1 2 / 0 7 2 0 1 0 / 1 2 / 0 8 2 0 1 0 / 1 2 / 0 9 2 0 1 0 / 1 2 / 1 0 2 0 1 0 / 1 2 / 1 1 2 0 1 0 / 1 2 / 1 2 2 0 1 0 / 1 2 / 1 3 2 0 1 0 / 1 2 / 1 4 2 0 1 0 / 1 2 / 1 5 2 0 1 0 / 1 2 / 1 6 2 0 1 0 / 1 2 / 1 7 2 0 1 0 / 1 2 / 1 8 2 0 1 0 / 1 2 / 1 9

Paging Succesrate per LAC

LAC 350

Improved paging success rate after feature activation 2nd_SCCPCH

and 24 kbps PCH activated

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Example: Paging msg per paging from VLR LAC350

0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00

Pag msg per pag from VLR (%)

Pag msg per pag from VLR MSC_514A

After feature activation less paging messages per paging is send. Hence paging load has decreased and 2nd_SCCPCH

and 24 kbps PCH activated

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Example: PS NRT active failures RNC15, 13 and 18

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 2 0 1 0 - 1 1 - 2 5 2 0 1 0 - 1 1 - 2 6 2 0 1 0 - 1 1 - 2 7 2 0 1 0 - 1 1 - 2 8 2 0 1 0 - 1 1 - 2 9 2 0 1 0 - 1 1 - 3 0 2 0 1 0 - 1 2 - 0 1 2 0 1 0 - 1 2 - 0 2 2 0 1 0 - 1 2 - 0 3 2 0 1 0 - 1 2 - 0 4 2 0 1 0 - 1 2 - 0 5 2 0 1 0 - 1 2 - 0 6 2 0 1 0 - 1 2 - 0 7 2 0 1 0 - 1 2 - 0 8 2 0 1 0 - 1 2 - 0 9 2 0 1 0 - 1 2 - 1 0 2 0 1 0 - 1 2 - 1 1 2 0 1 0 - 1 2 - 1 2 2 0 1 0 - 1 2 - 1 3 2 0 1 0 - 1 2 - 1 4 2 0 1 0 - 1 2 - 1 5 2 0 1 0 - 1 2 - 1 6 2 0 1 0 - 1 2 - 1 7 2 0 1 0 - 1 2 - 1 8 2 0 1 0 - 1 2 - 1 9 2 0 1 0 - 1 2 - 2 0 2 0 1 0 - 1 2 - 2 1 2 0 1 0 - 1 2 - 2 2 2 0 1 0 - 1 2 - 2 3 2 0 1 0 - 1 2 - 2 4 2 0 1 0 - 1 2 - 2 5 2 0 1 0 - 1 2 - 2 6 2 0 1 0 - 1 2 - 2 7 2 0 1 0 - 1 2 - 2 8 2 0 1 0 - 1 2 - 2 9 2 0 1 0 - 1 2 - 3 0 2 0 1 0 - 1 2 - 3 1 2 0 1 1 - 0 1 - 0 1 2 0 1 1 - 0 1 - 0 2 2 0 1 1 - 0 1 - 0 3

RAB active fail PS background RADIO

RNC-13 RNC-15 RNC-18 2nd_{SCCPCH and 24} kbps PCH activated in RNC15 2nd_{SCCPCH and 24} kbps PCH activated in RNC13 and 18

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Conclusion

• Higher Paging Channel TBS reduces PCH load from radio interface point of view. It also

reduces internal processing load of RNC because less internal messages are needed to

serve the same amount of users.

• So less DMPG processing capacity is needed for PCH and it can be used for other

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25/03/2018

RNC Counters to measure the amount of dropped paging records in L2.

• Previously this information was available only in DMPG computer logs

Paging drop counters

_–

RU30 new

Counter id Counter Name Updated

M1006C251 PAGING DROP LOW PRIORITY When the L2 entity of RCN drops low priority paging message due to congestion M1006C252 PAGING DROP HIGH PRIORITY When the L2 entity of RNC drops high priority paging message due the congestion

L3 detects first-time and repeated paging’s for Idle and Connected mode UEs and attaches the information into paging messages sent to the L2.

The first-time paging's are marked as having “high priority” and repeated paging’s as having “low priority”.

L2 prioritises paging records marked as having “high priority” over the ones marked with “low priority” in its scheduling decisions

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Paging drop counters

Paging for UE’s in IDLE state

UE BTS RNC

UE In Idle mode

RRC connection establishment

PICH

(FP/AAL2/PCCH/PCH/S-CCPCH) : PAGING TYPE 1

CN RANAP: PAGING

Paging response

CN (RANAP: PAGING Message received from CN = UE in idle mode) originated paging amount: When RNC sends Paging Type 1 through cells, counter M1006C25 PAGING_TYPE_1_ATT_CN_ORIG

Counter is updated when the RNC L2 entity has successfully scheduled PAGING TYPE 1 message for sending to the BTS and the paging procedure is triggered by the CN.

Paging messages dropped due to overload are not included.

When RNC receives paging message RANAP: Paging from the CN, counter: M1003C36 REC_PAG_MSG is incremented

1

If RNC cannot process the paging messages and forward those to the UE due to high ICSU load, counter M1003C47

DEL_PAG_MSG_ICSU_OVERLOAD is incremented

If RNC cannot process the paging messages and forward those to the UE due to high RRMU load, counter M1003C48

DEL_PAG_MSG_RRMU_OVERLOAD is incremented

M1006C251 PAGING_DROP_LOW_PRIORITY : The number of low priority paging r ecords dropped in L2 scheduling.

Counter is updater when the L2 entity of RNC drops low priority paging message due to congestion.

M1006C252 PAGING_DROP_HIGH_PRIORITY : The number of high priority paging records dropped in L2 scheduling.

Counter is updated when the L2 entity of RNC drops high priority paging message due to congestion.

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25/03/2018

Paging drop counters - RU30 new

Upon receiving of the paging message from Core Network, L3 determines priority of the message

• The idea is that first time paging and paging messages related to system information update would

be given high priority and repetition of an earlier received paging message would be set as low priority

• Prioritisation will be done for both Idle and Connected mode UE related pagings

• L3 passes the paging message to the cell-specific MAC-c entity

• The message includes information of the priority of the paging

• Based on this, the message is placed to the corresponding paging queue to be scheduled at the

appropriate time

• MAC-c schedules the paging messages so that the high priority queue is prioritised over the low

priority queue whenever possible

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Common Channel load Monitoring

RACH throughput >10kbps

Calculate CCH Load i.e. FACH-c + FACH-u, PCH, RACH-c + RACH-u per Cell

No Yes PCH throughput >5kbps FACH throughput >15kbps No No

Increase the Iub reservation for RACH, reduce the FACH timer, Reduce the unnecessary registrations and inter-rat cell reselection, reduce the RACH-u load (lower TrafVolThresholdULow)

Increase the RACH capacity (FACH throughput limited by RACH capacity), Reduce the unnecessary registrations and inter-rat cell reselection and reduce the FACH timer, reduce FACH-u load ( lower TrafVolThresholdDLow), Separate SCCPCH for FACHs and PCH

Yes

Separate SCCPCHs for FACHs and PCH Activate cell_PCH/URA_PCH

Calculate the #pages per LAC,

>65/s No #RL setups/s limiting factor No Yes

Reduce the Common Channel Setup usage Increase the RACH

reservation for Iub / increase the RACHcapacity

Calculate the #pages per LAC, >65/s

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25/03/2018

Implicit Detach (VLR) = 8h

CS_T3212 = 40dh (decihours) = 240min = 4hours TMSI page repetition in voice call = Used

Paging Attempts (AT) = 0 or 1

Repaging Interval (INT) = 3.5 s or 4.5s

UTRAN DRX cycle length = 320 ms IuCS DRX cycle length = 640 ms IuPS2 DRX cycle length = 640 ms

Paging Parameter Recommendations

_–

3G

Parameter Name (Cell level) Def/Current Recommended Value

N300 3 2

T300 2000ms 2000ms (10) Parameter Name (RNC level) Current Recommended Value WaitTimeRRCconversational 3 2 WaitTimeRRCstreaming 3 2 WaitTimeRRCinteractive 5 8 WaitTimeRRCbackground 5 8 WaitTimeRRCsubscribed 3 3 WaitTimeRRCemergency 1 1 WaitTimeRRCinterRATreselection 3 3 WaitTimeRRCregistration 5 5 WaitTimeRRChighPrioritySignalling 1 2 WaitTimeRRClowPrioritySignalling 5 2 WaitTimeRRCunknown 1 2 WaitTimeRRCother 0 2

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Paging Parameter Recommendations

_–

3G

VLR sends to RNC & RNC sends to UE

SMS

UE listens pages and establishes RRC

Voice

Four pages received from RNC Initial Page RRC Connection Request Paging Response 1st_Re-Page ₂nd_Re-Page 3rd _Re-Page

UE listens pages and establishes RRC

Initial Page

Two pages received from RNC

Wait Time 2s Wait Time 2s RRC Connection Request Paging Response 1st_Re-Page Paging interval4. 5s SMS Voice call No Paging Response No Paging Response

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25/03/2018

Paging - Core Network Parameters

• Search procedure is performed only if MS location is not found

- Search is always an IMSI page which will be repeated SCOUNT times with SINTER intervals

AT (MSS) Use of TMSI (VLR) Page Repetition (VLR) Result

0 Yes Yes TMSI+IMSI

0 Yes No TMSI

1 Yes Yes TMSI+TMSI+IMSI+IMSI

2 Yes Yes TMSI+TMSI+TMSI+IMSI+IMSI+IMSI

2 Yes No TMSI+TMSI+TMSI

2 No Yes IMSI+IMSI+IMSI

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