Radio Perf Meast

8/11/2019 Radio Perf Meast

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CME-20 R6 RADIO NETWORK PERFORMANCE MEASUREMENTS

COURSE CONTENTS

1: INTODUCTION

1.1 WHAT ARE RADIO NETWORK PERFORMANCE MEASUREMENTS

1.2 WHY MAKE RADIONETWORK PERFORMANCE MEASUREMENTS

1.3 HOW ARE RADIO NETWORKPERFORMANCE MEASUREMENTS MADE2: KEY PERFORMANCE INDICATORS

2.1 HOW ARE DROPPED CALLS MEASURED?

2.2 HOW IS CALL COMPLETION MEASURED?

2.3 HOW IS TRAFFIC LEVEL MEASURED

2.4 HOW IS CONGESTION MEASURED

2.5 HOW IS HANDOVER PERFORMANCE MEASURED

3: WHERE ARE RADIO PERFORMANCE MEASUREMENTS AVAILABLE

4: COUNTERS AND MEASUREMENTS FOR VARIOUS FUNCTIONS

4.1 COUNTERS AND MEASUREMENTS FOR RANDOM ACCESS CHANNEL

4.2COUNTERS AND MEASUREMENTS FOR SDCCH CHANNEL

4.3 COUNTERS AND MEASUREMENTS FOR TRAFFIC CHANNELS

4.4 COUNTERS AND MEASUREMENTS FOR DROPPED CONNECTION CAUSES

4.5 COUNTERS AND MEASUREMENTS FOR HANDOVERS

4.6 COUNTERS AND MEASUREMENTS FOR LOCATING

4.7 COUNTERS AND MEASUREMENTS FOR ASSIGNMENT TO ANAOTHER CELL4.8 COUNTERS AND MEASUREMENTS FOR INTRA CELL HANDOVER

4.9 COUNTERS AND MEASUREMENTS FOR IDLE CHANNEL MEASUREMENTS

4.10 COUNTERS AND MEASUREMENTS FOR LOAD SHARING

4.11 COUNTERS AND MEASUREMENST FOR OVERLAY/UNDRLAY SUB CELLS

5 USING RADIO NETWORK PERFORMANCE MEASURMENS

5.1 MANAGEMENT OVERVIEW REPORTS

5.2 NETWORK PLANNING

5.3 NETWORK OPTIMISATION

5.4 NETWORK ALARMS


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1.1 WHAT ARE RADIO PERFORMANCE MEASUREMENTS ?

Radio performance measurements are measurements of events of interest

that occur within the GSM Base Station Subsystem of the GSM-XL network

These measurements are derived from counters that are automatically

collected by the Base Station Controllers (BSCs) in the BSS.

There are many events that are counted, that can be used to derive

measurements of such things as traffic level in cells, congestion, hand over

success rate, call completion rate and dropped call rates

This course will describe how these events are counted, then how these

counters are turned into useful information, then what this information

can be used for



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1.2 WHY MAKE RADIO PERFORMANCE MEASUREMENTS ?

MANAGEMENT OVERVIEW AND REPORTING

NETWORK PLANNING

NETWORK OPTIMISATION

DETECTING FAULTY NETWORK ELEMENTS

Radio performance measurements can be used to produce management

overview reports of overall network performance, to ensure that service

level targets are being met

Traffic level measurements can be used for correct and future

dimensioning of network resources, such as radio transceivers

Radio performance measurements are used in the optimization process, asa guideline to which cells need attention from the radio optimization group.

Radio performance measurements can be used to detect faults in the

system by checking for sudden changes in some measurements, or whenother measurements exceed a certain threshold.


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1.3 HOW ARE RADIO PERFORMANCE

MEASUREMENTS MADE?

Software processes inside each BSC step counters for predefined events

usually signaling events between the BSC and BTS or MSC, or internal

signal transfers within the BSC

Counters are transferred every 15 minutes to the IOG-11 in the BSC

The counters are formatted into reports by the IOG-11, and

transferred every hour to the Operational Support System (OSS)

The OSS uses information from the IOG-11 reports, and predefined

user formulas to produce useful measurements. Measurements are

archived in the OSS, and some reports post processed and posted on the

NOC intranet web page

The NOC auto reports system retrieves data from the OSS daily, and

post processes data into other reports ready for users to use


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PERFORMANCEMEASUREMENT COLLECTION PROCESS

BSC

BSC

IOG-11

IOG-11

OSSBTS

BTS

1. Signaling events in the BSS step various counters in the BSCs

2: Counters are transferred every 15 minutes to the IOG-11

3 Counters are processed as reports in the IOG-11

4 Reports are transferred to the OSS every hour

AUTO-reports

5 Reports are postprocessed in the OSS

6: Reports are transferred

daily to NOC auto report

processing system

7: NOC auto report system produces

management and detailed reports forvarious users and management


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2.0 KEY PERFORMANCE INDICATORS

CALL COMPLETION RATE

When a subscriber enters a number on their MS, and presses the send key,

it is useful to know how often this process is successful. A call is defined as

completed when a connection through to the B party is successful, this means

that ringing tone is received from the other end. (And then maybe the person

who has been dialed answers)

PERCEIVED DROPPED CALL RATE

Mobile calls will drop out unexpectedly on occasions due to insufficient

radio signal strength or poor radio conditions preventing a proper

connection between the MS and BTS. Perceived dropped call rate is thenumber of occurrences of this, as function of the total number of calls

established on the network


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DROPPED CONNECTION RATE

Traffic channels (TCH) or signaling channels (SDCCH) on the air interface can

be seized at call set up or due to incoming hand over. The number of call drops

as a function of the number of successful channel seizures is a useful indicator

of a cells performance.

ERLANG DROP CALL RATEThe number of drops as a function of the total TCH or SDCCH traffic

carried by the cell is another useful indicator of BSS performance.

TRAFFIC LEVEL

The amount of traffic that a cell carries is useful to know for network

dimensioning and forward planning, as well as optimization and faultdetection. Optimization efforts should be directed towards cells with high

traffic load. Cells with sudden changes in traffic level may have

developed a fault.


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CONGESTION

As traffic levels increase in the network, attempts to seize a channel will fail

because all resources are already occupied by other users. This is congestion.

Congestion can be expressed as congestion rate or congestion probability.

Congestion rate is the number of failed seizures as a function of total seizure

attempts. Congestion probability, or channel utilization, is calculated by

measuring carried traffic as a function of traffic capacity and grade of service

HANDOVER SUCCESS RATE

For a mobile phone network to be mobile, a method of handing over an

MS from one cell to another as the user moves through the network isrequired. There is always a chance that hand over of an MS from the old

cell to the new cell will fail. The number of successful hand overs as

function of total hand over attempts is a useful performance indicator


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2.1a HOW ARE DROPPED CALLS MEASURED ?

Under normal circumstances, a call is terminated by the mobile user pressing

the end key, resulting in a clear request message being sent to the MSC.Alternatively if the called party hangs up, a clear request from the MSC will be

sent to the MS

This results in all transmission paths being cleared, and the release of radio

channels by the BTS and MS, as well as the termination of call charging

In some circumstances, radio communication between the MS and BTS isinterrupted, due to unfavorable radio conditions. If this results in a complete

signaling failure between the MS and BTS, then no Clear Request message can be

sent or received by the MS. A mechanism for the BTS and the MS to

automatically clear the call, release radio resources, and inform the MSC that the

call has been disconnected, exists.A counter exists in the MS that counts the successful reception of down link

SACCH frames. The counter starts at a value of RLINKT (=20 in GSM-XL), and

is decremented by 1 every time a SACCH frame cannot be decoded, and

incremented by 4 up to a maximum value of RLINKT every time a SACCH

frame is successfully decoded. (A leaky bucket type counter).


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2.1b HOW ARE DROPPED CALLS MEASURED ?

Whenever this counter reaches zero in the MS, an abnormal channel release

message is sent on the up link, the channel released, and the MS returns to idlemode, after sending some form or message such as 3 beeps to the user

A similar leaky bucket counter RLINKUP exists in the BTS, counting the

successful reception of up link SACCH frames being received from the MS. If

this counter reaches zero, an abnormal channel release message is sent to the MS,

and the radio channel released. If the message is not received by the MS, the MS

will stop receiving SACCH frames from the BTS, and its own RLINKT counter

will expire.

Either event results in an abnormal channel release message being sent to the

BSC, informing the BSC that the MS has been lost.

The BSC is informed by the BTS of the timing advance being used by the MS.

If the timing advance reaches a value MAXTA, (=63 for GSM-XL), then the BSC

will clear the call, to prevent the MS interfering with an MS using the next

timeslot.


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2.1c HOW ARE DROPPED CALLS MEASURED ?

Either radio link failure condition, or excessive timing advance, will result in

the BSC sending a clear request to the MSC. (Remember that the Clear requestnormally comes from the MS or the MSC)

This abnormal condition, whereby the BSC sends the clear request, is counted

in the BSC. Counter TNDROP is stepped in the cell where the MS was connected,

and the connection was on a TCH. Counter CNDROP is stepped in the cell where

the MS was connected and the connection was on an SDCCH.


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BTS

BSC MSC

RLINKT

RLINKUP

CLEAR REQUEST

MAXTA

DOWNLINK

UPLINK

HOW ARE DROPPED CALLS COUNTED ?

RLINKT SUPERVISES THE SUCCESSFUL DECODING OF DOWNLINK SACCH FRAMES IN THE MS,

RLINKUP SUPERVISES THE SUCCESSFUL DECODING OF UPLINK SACCH FRAMES IN THE BTS

ABNORMAL

CHANNEL

RELEASE

IF RLINKT REACHES ZERO, THE MS RELEASES THE RADIO

CHANNEL AND RETURNS TO IDLE MODE. RLINKUP WILL

THEN DECREMENT TO ZER0, AS NO MORE UPLINK SACCH

FRAMES ARE BEINGRECEIVED AND DECODED AT THE BTS

WHEN RLINKUP REACHES ZERO, BTS SENDS ABNORMALCHANNEL RELEASE MESSAGE TO THE MS AND BSC, AND

THEN RELEASES THE RADIO CHANNEL

CALL SUPERVISION FUNCTION IN THE BSC WILL SEND CLEAR

REQUEST TO THE MSC TO CLEAR THE CALL WHEN ABNORMAL

CHANNEL RELEASE RECEIVED OR TIMING ADVANCE > MAXTA.DROPPED CALL COUNTER FOR THE CELL IS INCREMENTED.


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2.2a HOW IS CALL COMPLETION MEASURED ?

Call completion means that after pressing the send key, a connection through to

the called party, that results in ring tone being received, is successfullyestablished.

For this to happen, a move from the Random access channel, to the signaling

channel (normally SDCCH, but may be TCH for immediate assignment on TCH

traffic cases) and then on to a TCH in response to an assignment request from the

MSC is required.

Call completion applies to mobile originated as well as mobile terminated calls,

but failed call completion for MT calls are rarely noticed by the subscriber.

Reasons that calls may fail to complete include (but are not limited to )

Failure of the channel request message to get through on the RACCH. The

MS will retry a maximum of MAXRET (=7 for GSM-XL) times before giving

up and declaring a signaling failure condition, resulting in cell re selection.

Failure to set up on the allocated SDCCH after reception of Immediate

Assignment message from the BSC

Dropped call during signaling transfer phase on the SDCCH

Failure to assign a TCH after reception of assignment request from MSCSi nalin or other failure in the transit or terminatin network

CME 20 R6 RADIO NETWORK PERFORMANCE MEASUREMENTS


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BTSBSC MSC

CHANNEL REQUESTCHANNEL REQUIRED

IMMEDIATE ASSIGNMENT

IMMEDIATE ASSIGNMENT

SABM/UA ESTABLISH INDICATIONSCCP REQUEST/CONFIRM

CANNEL REQUEST FROM

UNKNOWN MS RECEIVED

CM + MM SIGNALLING PERFORMED ON THE SDCCH BETWEEN THE MS AND MSC

ASSIGNMENT REQUESTASSIGNMENT COMMAND

THE BSC ALOCATES AN

SDCCH CHANNEL

SABM/UA

ASSIGNMENT COMPLETE ASSIGNMENT COMPLETE ASSIGNMENT COMPLETE

ASSIGNMENT COMMAND

SPEECH/DATA FRAMES EXCHANGED ON THE TCH BETWEEN THE MS AND THE MSC

THE MSC REQUESTS A TCH

FOR SPEECH/DATA TRANSFER

2.2B SIMPLIFIED CALL SET UP DIAGRAM



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2.2C HOW IS CALL COMPLETION MEASURED ?

It is not possible to precisely measure call completion rate, as perceived by

the subscriber, for a number of reasons. Instead SDCCH and TCHcompletion ratio are measured separately.

In theory, call completion rate could be calculated from the total number of

failed random accesses + total number of SDCCH completion failures + total

number of SDCCH drops + total number of TCH completion failures as a

function of total calls set up. There are two problems that prevent this.1: Phase 1 establishment causes are ambiguous, so it is not possible to

determine at the RR signaling level if the channel request and resulting

SDCCH seizure is due to call set up, SMS or location updating.

2: The channel request message is only 8 bits long, so false random access

burst detection, which leads to a failed SDCCH allocation, can be quitecommon, resulting in low SDCCH completion rate, even though this effect is

having no impact on subscriber service.

GSM-XL just use the TCH completion ratio as a measure of call

completion ratio, which yields a somewhat optimistic result.



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2.3A HOW IS TRAFFIC LEVEL MEASURED

The GSM BSS shares limited traffic resources amongst many users, relying

on the fact that all users do not make calls at the same time, and only make

calls of limited duration, typically 1 to 2 minutes. Hence a small number of

traffic channels can be shared amongst many users.

If 1 traffic channel is occupied for 1 hour, this is equal to 1 Erlang of traffic

Hence, the absolute maximum traffic level that a cell can carry in Erlang isequal to the number of traffic channels

Traffic is measured in CME-20 BSS by scanning every cell, once every 10

seconds, and counting how many TCH (or SDCCH) are occupied. The result

is added to the previous result, to form an accumulation. At the end of the

measurement period, this accumulation is divided by the number of scanningoperations performed, to yield the average traffic level over the measurement

period.

Traffic measurements are forwarded to the IOG-11 every 15 minutes.



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2.3 TRAFFIC LEVEL MEASUREMENTS EXAMPLE

BTS

6 TRAFFIC

CHANNEL CELL

CHANNEL STATUS

= IDLE

= SEIZED

T=0

T+10

T+20

T+30

T+70

T+60

T+50

T+40

T+80

1 2

3 7

4 11

6 21

5 17

7 25

9 30

2 5

TIME NUMBER

OF SCANS

8 27

TRAFFIC LEVEL

ACCUMULATOR

AVERAGE TRAFFIC = 30/9 = 3.3 ERLANG



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2.4a HOW IS CONGESTION MEASURED ?

Congestion occurs whenever an attempt to seize a channel fails because all

of the channels in a cell are already occupied. Seizures may be due to call set

up attempts, assignments from other cells or incoming hand over attempts.

Congestion may be measured as congestion ratio, by counting the number

of failed attempts as a function of total attempts, or as congestion probability,

by measuring the actual carried traffic and calculating the congestion

probability as a function of the number of available channels and the

required grade of service.As the amount of traffic carried by a cell increases, the probability that

some seizures will fail due to congestion also increases. This probability is

usually expressed by the Erlang B formula, which yields the traffic carrying

capacity in Erlang of a group of channels, as a function of grade of service

GOS, which is the percentage of seizures that will fail. See appendix AFor example for a 2% GOS, (2 in 100 attempts will fail), 6 channels has a

capacity of 2.2 Erlang, 14 Channels has a capacity of 8.2 Erlang, 22 Channels

has capacity of 14 Erlang and so on. As the GOS is relaxed, more seizures are

allowed to fail and the traffic capacity increases.



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2.4b HOW IS CONGESTION MEASURED ?

Congestion probability is calculated by doing the reverse, measuring the

carried traffic , knowing the number of channels available, and working out

the GOS from the Erlang B formula, which will be the congestion probability

Channel utilization is a similar concept, and is the actual traffic divided by

the traffic capacity for the required GOS. For example a 6 channel cell, for

2% GOS that carries 3.3 Erlang has a channel utilization of 3.3/2.2 = 150%

Fixed wire line networks typically operate with a GOS of 1%. The CME-20

BSS network can operate with larger GOS values for a number of reasons.Call set up failures due to congestion can be saved by function

Assignment to Another Cell for TCH, or Immediate Assignment

on TCH for SDCCH congestion cases.

Incoming hand over attempts that fail due to congestion, will not

normally be noticed by the user. (The BSC does not command a handover to a cell which has no channels available). When a hand over

allocation attempt fails due to congestion, timers in the BSC TALLOC (=

1 second for GSM-XL) for normal hand hovers, or timer TURGEN (=1

second for GSM-XL) for urgency condition hand over will start. When

the timer expires, a new allocation attempt will be made and eventually

hand over to the correct cell will occur.



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2.2c CONGESTION MEASUREMENT EXAMPLE

BTS

FAILED SEIZURES

DUE TO CONGESTION

NUMBER OF SEISURE ATTEMPTS= 1000

NUMBER OF FAILED SEISURE ATTEMPTS= 200

CONGESTION PROBABILITY FROM ERLANG B TABLE

FOR 3.3 ERLANG AND 6 CHANNELS = 0.07 = 7%

NUMBER AVAILABLE CHANNELS= 6

CARRIED TRAFFIC = 3.3 ERLANG

DESIRED GOS = 2%

CONGESTION RATIO = 200/1000 = 20%

CHANNEL UTILISATION = 3.3/2.2 = 150%



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2.5a HOW ARE HAND OVERS MEASURED ?

When ever an SDCCH or TCH is allocated to an MS, a locating individual

is created in the BSC regional processor that controls the cell where the

connection is made.

Locating is the software process in the BSC central processor (CP) and

regional processors (RP) that controls the hand over process, based on

measurement reports being received from each MS. When ever a locating

individual decides that a hand over is required for the MS that is being

supervised, an allocation request is sent to the CP. If resources are availablein the target cell, the CP will execute a hand over to the target cell.

When a hand over is required, the BSC will activate a channel on the new

cell, and send a HANDOVER COMMANDto the MS on the old cell,

instructing the MS to change to the channel and timeslot of the new cell. The

MS then moves, and tries to establish a connection on the new cell. If L2messaging is set up OK, and a SACCH established on the new cell, the MS

sends a HANDOVER COMPLETEmessage to the BSC,and the BSC will then

release the channel on the old cell.



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2.5b HOW ARE HAND OVERS MEASURED ?

If the MS cannot establish a connection on the new cell, after a period of

time (about 250mSec for GSM-XL), the MS will return to the channel and

timeslot of the old cell and attempt to re establish a connection there. If this is

successful, a HANDOVER FAILURE message is sent to the BSC, and the call

continues on the old cell. The BSC will then release the channel on the new

cell.

If the MS cannot re establish the connection on the old cell, the call is lost,

and the dropped call counter of the old cell stepped.The BSC counts the signaling events HANDOVER COMMAND,

HANDOVER COMPLETE and HANDOVER FAILURE, as well as

counting allocation attempts from each RP, even when these fail due to

congestion, as well as the reasons for the allocation, including normal path

loss hand over, normal signal strength hand over and urgency hand oversdue to bad up link or down link quality or excessive timing advance.

Handover counters are made per neighbor relation (n-cell)

There are separate counters for internal n-cells (neighbors between cells on

the same BSC) and external n-cells (neighbors between cells on different

BSCs)



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2.5c NORMAL HAND OVER EXAMPLE

CELL-A CELL-B

BSC

RP RP

CP

2:LOCATING INDIVIDUAL

IN RP PROCESSES REPORTS

AND REQUESTS HANDOVER

FROM CP WHEN REQUIRED

3: CP CHECKS CAPACITY

IN CELL B, ACTIVATES

CHANNEL IN CELL B, AND

HANDOVER REASON

COUNTER IS STEPPED

1: MS SENDS MEASUREMENT

REPORTS TO THE BSC ONTHE SACCH 5: MS ESTABLISHES SACCH ON

CELL B, AND SENDS HANDOVER

COMPLETEMESSAGE TO BSC

6: CP DE-ACTIVATES CHANNEL

IN CELL A, AND HANDOVER

SUCCESS COUNTER IS STEPPED

7: NEW LOCATING

INDIVIDUAL IS CREATED

IN CELL Bs RP

4: HANDOVER COMMAND

MESSAGE IS SENT BY CP

TELLING MS TO SWITCH

TO CELL B, HANDOVER

ATTEMPT COUNTER IS

STEPPED



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2.5d HAND OVER FAILURE EXAMPLE

CELL-A CELL-B

BSC

RP RP

CP

2:LOCATING INDIVIDUAL

IN RP PROCESSES REPORTS

AND REQUESTS HANDOVER

FROM CP WHEN REQUIRED

3: CP CHECKS CAPACITY

IN CELL B, ACTIVATES

CHANNEL IN CELL B, AND

HANDOVER REASON

COUNTER IS STEPPED

1: MS SENDS MEASUREMENTREPORTS TO THE BSC ON

THE SACCH

5: MS ATTEMPTS TO ESTABLISH

CONNECTION WITH CELL B, BUT FAILS

7: CP DE-ACTIVATES CHANNEL

IN CELL B, AND HANDOVER

REVERSION COUNTER IS

STEPPED

8: LOCATING CONTINUES

ON CELL A RP

4: HANDOVER COMM AND

MESSAGE IS SENT BY CP

6:MS RE-ESTABLISHES CONNECTIONON CELL A AND SENDS HANDOVER

FAILUREMESSAGE TO THE BSC



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3.0 WHERE ARE PERFORMANCE MEASUREMENTS AVAILABLE

Performance measurements are available on the NOC Web page, under

detailed statistics : //http/noc4web

NOC AUTO REPORTS also provides detailed statistics

BSC System Reports: Provides various tables of information grouped

by region, or BSC, as well as network summaries

BSC Extension System reports: Provides all information on a per celland per neighbor relation for all cells in the network



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CNROCNT

RAACCFARAEMCAL

RACALRE

RAANPAG

RAOSREQ

RAOTHER

'Channel required' received from BTS in response to Channel req on RACCH

Stepped at message 'Channel required' received from BTS cannot be decodedSuccessfully decoded Random Access w ith cause code Emergency call

Successfully decoded Random Access w ith cause code Call estblishment

Successfully decoded Random Access w ith cause code Answ er to Page

Successfully decoded Random Access for other service request

Successfully decoded Random Access that does not f it above cases

4.1a COUNTERS FOR RANDOM ACCESS MEASUREMENTS

When an MS wants to access the radio network for the first time, for mobile originated or mobile

terminated call set up, SMS transmission or reception, or location updating, a channel requestmessage is sent over the Random Access Control Channel (RACCH

Channel request messages are only 8 bits long, and contain a 3 bit cause code, which gives some

information as to what reason is for requesting the radio channel

When the BTS successfully decodes a channel request message from an MS, a channel required

message is sent to the BSC. Reception of these channel required messages steps various counters in

the BSC as detailed below



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BTS

BSC MSC


CHANNEL ACTIVATION

CHANNEL ACT ACK

IMMEDIATE ASSIGNMENTIMMEDIATE ASSIGNMENT

SABM

UA ESTABLISH INDICATION

SCCP REQUEST

SCCP CONFIRM

CM SERVICE REQUEST

CCALLS

CNROCNT

RAACCFA

RAEMCAL

RACALRE

RAANPAGRAOSREQ

RAOTHER

CMSESTB

4.1b RANDOM ACCESS COUNTERS



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4.1c FORMULAS FOR RANDOM ACCESS CHANEL MEASUREMENTS

RANDOM ACCESS

CHANNEL

MEASUREMENTS FORMULA DESCRIPTION

rach_att CNROCNT Number of random accesses

racch_to_sdcch_ratio (CCALLS / CNROCNT) * 100%

Percentage of random access that lead to an SDCCHseisure

rach_failed_ratio (RAACCFA/CNROCNT) * 100% Percentage of failed random accesses

rach_emergency_rat

io (RAEMCAL/CNROCNT) * 100% Percentage of random accesses for reason emergency call

rach_callreestablish

_ratio (RACALRE/CNROCNT) * 100%

Percentage of random accesses for reason call

establishment

rach_anspaging_rati

o (RAANPAG/CNROCNT) * 100% Percentage of random accesses for reason answer to page

rach_otherservice_r

atio (RAOSREQ/CNROCNT) * 100%

Percentage of random accesses for reason other service

request

rach_othercases_rat

io (RAOTHER/CNROCNT) * 100% Percentage of random accesses for reason other cases

THESE MEASUREMENTS ARE MADE PER CELL



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4.2 a COUNTERS FOR SDCCH CHANNELS IN EACH CELL - OBJECT TYPE CELLSSDCCH

Counter CCALLS is stepped every time an Access Grant message is sent to

allocate an SDCCHCounter CMSESTAB is stepped every time an SDCCH seizure leads to the

successful set up of a signaling connection to the MSC

Counter CCONGS counts failed allocations due to congestion, CTCONGS

is stepped every second that all SDCCH are seized in the cell

Counter CNDROP counts dropped SDCCH connections

Counters CTRALACC and CNSCAN count SDCCH traffic level

Counters CAVAACC and CAVASCAN count SDCCH availability

CCALLS Stepped w hen ever a Channel request message is received from BTS and can be processed

CMSESTAB Stepped at message SCCP CONFIRM received from the MSC

CCONGS Stepped every time an attempt to seize an SDCCH fails due to no SDCCH channels availableCTCONGS Stepped once a second when all SDCCH are se ized and or blocked

CNDROP The number of dropped SDCCH connections

CTRALACC Every 10 seconds, the no. of SDCCH seized in the cell is added to the previous result

CNSCAN Number of times CTRALACC is s tepped in the measurem ent per iod

CNUCHCNT The num ber of SDCCH channels defined in the cell

CAVAACC Every 10 seconds, the no. of SDCCH available (not blocked) is added to the previous resultCAVASCAN Number of times CAVACC is stepped in the measurement period



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BTS

BSC MSC


CHANNEL ACTIVATION

CHANNEL ACT ACK

IMMEDIATE ASSIGNMENTIMMEDIATE ASSIGNMENT

SABM/UA ESTABLISH INDICATIONSCCP REQUEST

SCCP CONFIRM

CCALLS

CMSESTAB

4.2b SDCCH COUNTERS

CLEAR REQUEST (BY BSC)

CNDROP

CTRALACC, CNSCAN

COUNTS TRAFFIC

CAVACC, CAVASCAN

COUNTS AVAILABILITY CCONGS COUNTSCONGESTION EVENTS

CTCONGS COUNTS

CONGESTION TIME

8 X SDCCH CHANS



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SDCCH CHANNEL

MEASUREMENTS FORMULA DESCRIPTION

sdcch_att CCALLS Number of SDCCH seisures

sdcch_suc CMSESTB Number of successful channel establishment on SDCCH

sdcch_suc_ratio (CMSESTB/CCALLS) * 100% Ratio of SDCCH se isures to successful SDCCH channel establishment

sdcch_drop CNDROP Number of dropped SDCCH connections

sdcch_drop_ra tio (CNDROP/CMSESTB) * 100% Droppe d SDCCH in rea ltion to SDCCH cha nnels esta blishe d

sdcch_erldrop_ratio

(CNDROP * CNSCAN * 60) / (CTRALACC *

PLENGTH) Dropped SDCCH in relation to traffic carried

sdcch_traffic CTRALACC/CNSCAN Carried SDCCH traffic in Erlang

sdcch_avail (CAVACC/(CAVASCAN * CNUCHNT)) * 100% SDCCH ava ilability

sdcch_cong_ratio (CCONGS/CCALLS) * 100% SDCCH congestion rate

sdcch_congtime CTCONGS Total time in seconds that all SDCCH were seised

sdcch_congtim_ratio (CTCONGS) / (PLENGTH * 60) *100% % of measurement interval that all SDCCH were seised

sdcch_meanholdtim (CTRALACC/CNSCAN)*60*60/CMESTB Mean holding time of SDCCH

4.2c SDCCH MEASUREMENT FORMULAS



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4.3a COUNTERS FOR TRAFFIC CHANNEL MEASUREMENTS

Counter TCALLS is stepped by internal software signals, every time a TCH is required, including

attempts that fail due to congestion.

TMESTB is stepped every time a TCH is successfully seized, by counting when a signaling channelis successfully established on the SACCH

TASSALL counts assignment requests (of TCH) received from the MSC

TCASSAL counts assignment complete messages at assignment to same cell, or hand over complete,

cause = directed retry, at assignment to another cell

CELLTCH TCH countersTCALLS Stepped every time an attemp is made to se ize a TCH, including at congestion

TMSESTB Stepped w hen a successful RR session established on SACCH, ie TCH seized successfully

TASSALL Stepped at message Assignment Request received from the MSC

TCASSALL Stepped at message Assignment Complete sent to MSC, or Handover Complete for ASWCL

TNDROP Stepped w hen Clear request message sent to MSC by the BSC

TCONGS Stepped every time a TCH seisure fails due to all TCH already being seized or blockedTTONGS Steps every 1 second that all TCH in cell are se ized

TTRALACC Every 10 seconds, the number of seized TCH is added to the previous result

TNSCAN The number of times that TTRALACC is stepped

TNUCHCNT No of TCH defined in cell (may be incorrect if SY hopping used)

TAVAACC Every 10 seconds, the number of available (not blocked) TCH is added to the previous result

TAVASCAN The number of times TAVASCAN is stepped



33/71

BTS

BSC MSC

ASSIGNMENT COMMAND

SABM/UA

ASSIGNMENT COMPLETE ASSIGNMENT COMPLETE

ASSIGNMENT REQUEST

TASSAL

TCASSAL

4.3b TCH COUNTERS FOR NORMAL CALL SET UP

CLEAR REQUEST (BY BSC)

TNDROP

TTRALACC, TNSCAN

COUNTS TRAFFIC

TAVACC, TAVASCAN

COUNTS AVAILABILITY TCONGS COUNTSCONGESTION EVENTS

TTONGS COUNTS

CONGESTION TIME

N x TCH CHANS

ASSIGNMENT COMMAND

ASSIGNMENT COMPLETE

MS MOVES FROM SDCCH TO

TCH AND ESTABLISHES RR

SIGNALING ON THE SACCH

TMSESTB

SIGNALLING CONNECTION ON SDCCH ALREADY ESTABLISHED BETWEEN MS AND MSC

TCALLS IS STEPED

EVERY TIME A

TCH IS WANTED



34/71

4.3c TCH CHANNEL MEASUREMENT FORMULAS

CELLTCH FORMULA DESCRIPTION

tch_att TCALLS The total number of TCH seizure attempts

tch_suc TMSESTB The total number of times a TCH is successfully seized

asg_att TASSAL The total number of "Assignment Command" messages from MSC

asg_suc TCASSAL

The total number of "Assignment Complete" messages for normal call

set up or "handover Complete= directed retry" for ASWCL

tch_suc_ratio (TMSESTB/TCALLS) * 100% Ratio of successful TCH seisures to all TCH seisure attempts

asg_suc_ratio (TCASSAL/TASSAL) *100% Ratio of successful TCH assignments to total assignment attempts

tch_traffic TTRALACC/TNSCAN The traffic carried in the cell in Erlang

tch_drop TNDROP The number of dropped calls

tch_drop_ratio (TNDROP/TMSESTB) * 100% Dropped TCH as a percentage of successful TCH seisures

tch_erldrop_ratio

(TNDROP * TNSCAN * 60) / (TRRALACC *

PLENGTH) Dropped TCH as a percentage of total traffic

tch_drop_asg_ratio (TNDROP/TCASSAL) * 100% Dropped TCH as a percentage of ca ll se t up (assignments)

tch_avail (TAVACC/(TAVASCAN * TNUCHNT)) * 100% The availabi li ty of TCH during the measurement period

tch_meanholdtime (TTRALACC/TNSCAN)*60*60/TMSESTB The mean holding time of TCH in seconds

tch_cong_prob Erlang fuction (tch_traffic+tch_avail)

Congestion calculated as a function of offered traffic vs available

channels

tch_cong_ratio (TCONGS/TCALLS) * 100%

The number of failed seisures due to congestion as a percentage of

seisure a ttempts

tch_congtime TTONGS The time in seconds when all TCH are siezed

tch_congtime_ratio (TCONGS) / (PLENGTH * 60) *100% Percentage of time that a ll TCH are se ized



35/71

4.4a COUNTERS FOR DROPPED CONNECTION REASONS

When ever a connection is established on an SDCCH or TCH, measurement reports are sent

on the SACCH to the BSC and a locating individual is started, so hand over can be invoked

when required.If a connection is dropped, the locating individual can report on the measured radio

environment at the time, so some reason behind the dropped connection can be deduced.

If the filtered down link signal strength of the MS was less than MSRXMIN when the call

dropped, or the estimated up link signal strength was less than BSRXMIN when the call

dropped, then low signal strength reason is declared

If the timing advance reached the value of MAXTA, excessive timing advance reason is

declaredIf the filtered up link quality exceeded QLIMUL or the filtered down link quality exceeded

QLIMDL at the time of the dropped connection, then bad quality reason is declared.

Dropped calls that meet none of the above criteria are bundled in to other reasons

There are separate counters for dropped SDCCH connections and dropped TCH connections

The locating process knows the power capability of the MS, so there are separate dropped

connection due to low signal strength counters for MS power classes 1, 2, 3, 4 and 5

All MS in GSM-XL are class 4



36/71

CELLTCHDR Dropped TCH connecti on reasons

TDISQA Stepped at dropped connection on TCH when Bad Quality urgency condition exists

TDISSS1 Stepped w hen a class 1 MS drops on TCH and meaured s ignal strength < MSRXMIN





TDISTA Stepped at dropped connection on TCH when excessive TA urgency condition exists

CELLCCHDR Dropped SDCCH connecti on reasonsCDISQA Stepped at dropped connection on SDCCH when Bad Quality urgency condition exists

CDISSS1 Stepped when a class 1 MS drops on SDCCH and meaured signal strength < MSRXMIN




CDISSS5 Stepped when a class 5 MS drops on SDCCH and meaured signal strength < MSRXMINCDISTA Stepped at dropped connection on SDCCH when excessive TA urgency condition exis

4.4b COUNTERS FOR DROPPED CONNECTION REASONS



37/71

BTS

MSCCLEAR REQUEST

1: WHEN AN SDCCH OR TCH CONNECTION IS ESTABLISHED, A SACCH IS ESTABLISHED, AND A

LOCATING INDIVIDUAL ON THE CELLS RP BEGINS PROCESSING MEASUREMENT REPORTS FROM MS

ABNORMAL

CHANNEL

RELEASE

BSC

RP

2: IF THE RADIO CONNECTION IS DROPPED, THE BTS AND BSC INITIATE

ABNORMAL CALL DISCONECTION PROCEDURE

3: LOCATING IS STOPPED AT ABNORMAL CHANNEL RELEASE, AND

DROPPED CALL REASONS ARE REPORTED IF APPROPRIATE

CNDROP, TNDROP

CDI SSS,TDISSS

CDI SQA, TDSISQA

CDISTA, TDI STA

4.4c COUNTERS FOR DROPPED CONNECTION REASONS



38/71

4.4d MEASUREMENT FORMULAS FOR DROPPED CONNECTION REASONS

sdcch_drop_ss_ratio

((CDISSS1+CDISS2+CDISS3+CDISS4+CDISS5)/CN

DROP)) * 100% % of SDCCH drops at bad signal strength

sdcch_drop_qa_ratio (CDISQA/CNDROP) * 100% % of SDCCH drops at bad quality urgency

sdcch_drop_ta_ratio (CDISTA/CNDROP) * 100% % of SDCCH drops at excessive timing advance

sdcch_drop_ot_ratio

((CNDROP-CDISSS1-CDISSS2-CDISSS3-CDISSS4-

CDISSS5-CDISQA-CDISTA)/CNDROP) * 100% % of SDCCH drops due to unknown reasons

tch_drop_ss_ratio

((TDISSS1+TDISS2+TDISS3+TDISS4+TDISS5)/TN

DROP)) * 100%

Number of drops at bad signal strength (TDISSS) as a percentage of

number of drops

tch_drop_qa_ratio (TDISQA/TNDROP) * 100%

Number of drops at bad quality (TDISQA) as a percentage of number of

drops

tch_drop_ta_ratio (TDISTA/TNDROP) * 100%

The number of drops at excessive timing advance as a percentage of

number of drops

tch_drop_ot_ratio

((TNDROP-TDISSS1-TDISSS2-TDISSS3-TDISSS4-

TDISSS5-TDISQA-TDISTA)/TNDROP) * 100%

The difference between drops due to (signal strength + quality + timing

advance) and total drops, as a percentage of total drops

Dropped connection reasons are measured separately for SDCCH

and TCH connections



39/71

4.5a COUNTERS FOR HANDOVER EVENTS

Handover events are counted for each neighbor relationship defined in the BSS

There are separate object types, using the same counter names for internal and external

neighbor relationships. Internal N-cells are n-cells between cells on the same BSC, external n-cells are n-cells between cells on different BSCs

NCELLREL In tra BSC handover coun ters, between cel l s on the same BSC (INT)HOVERCNT Stepped at message Handover Commandsent to MS on old cell

HOVERSUC Stepped at message Handover Com pl e tereceived from MS on new cell

HORTTOCH Stepped at message Handover Fa i l u rereceived from MS on old cell

NECELLREL Inter BSC handover counters between cel ls on d i fferent BSCs (EXT)

HOVERCNT Stepped at message Handover Commandsent to MS on old cellHOVERSUC Stepped at message Handover Com pl e tereceived from MS on new cell

HORTTOCH Stepped at message Handover Fa i l u rereceived from MS on old cell



40/71

CELL-A CELL-B

BSC

RP RP

CP

MS SENDS MEASUREMENT

REPORTS TO THE BSC ONTHE SACCH

MS ESTABLISHES SACCH ON

CELL B

HANDOVER COMM AND

4.5b COUNTERS FOR HANDOVER EVENTS, NORMAL HANDOVER

HANDOVER COMPLETE

HOVERCNT

HOVERSUC

LOCATING INDIVIDUAL

IN RP PROCESSES REPORTSAND REQUESTS HANDOVER

FROM CP WHEN REQUIRED,

CP SENDS HANDOVER

COMMAND TO THE MS



41/71

CELL-A CELL-B

BSC

RP RP

CP


REPORTS TO THE BSC ON

THE SACCH

MS ATTEMPTS TO ESATLISH

CONNECTION ON CELL B BUT

FAILS, AND THEN RETURNS

TO THE OLD CHANNELHANDOVER COMM AND

4.5c COUNTERS FOR HANDOVER EVENTS, HANDOVER FAILURE

HOVERCNT

HORTOCH

LOCATING INDIVIDUAL

IN RP PROCESSES REPORTSAND REQUESTS HANDOVER

FROM CP WHEN REQUIRED,

CP SENDS HANDOVER

COMMAND TO THE MS

HANDOVER FAILURE



42/71

4.5d MEASUREMENT FORMULAS FOR HANDOVER EVENTS

PER N-CELL MEASUREMENTS

HANDOVER

MEASUREMENTS FORMULA DESCRIPTION (MEASUREMENTS ARE PER N-CELL)

ttype Ext or Int External for inter BSC and int for intra BSC handovers

HOVERCNT HOVERCNTThe number of handover attempts per n-cell (Handover commandmessages sent)

PER_SUCC (HOVERSUC / HOVERCNT) *100% Percentage of succe ssful ha ndove rs in re lation to handover a tte mpts

PER_REV (HORTOCH / HOVERCNT) * 100%

Percentage of reversions to original channels in relation to handover

attempts

PER_LOST

(HOVERCNT - HORTOCH - HOVERSUC) *100

(HOVERCNT)

Difference between successful handovers and handover reversions in

relation to handover attempts

The number of hand over attempts is counted per n-cell

The percentage of successful hand over attempts, ie hand over commands that lead to hand

over completions is measured

The percentage of hand over reversions is measured ie hand over commands that fail and the

MS reverts back to the old cell

The percentage of hand overs lost is measured, by measuring the difference between handover commands and hand over completions + hand over reversions



43/71

4.5e MEASUREMENT FORMULAS FOR HANDOVER EVENTS

PER CELL MEASUREMENTS

It is useful to sum the hand over performance of all neighbor to a cell together, so hand over

performance on a per cell basis can be seen.

Total incoming and outgoing hand overs are measured, as well as total incoming hand over

reversions and lost, per cell

SCELL is serving (old) cell in the neighbor relation, EXTCELL or INTCELL is the target

(new) cell in the neighbor relation for external and internal neighborsCells with high percentage of incoming hand over reversions need attention !

SUMINCHOATT

SUM HOVERCNT For all INTCELL and EXTCELL =

CELL

The sum of all incoming handover attempts from neighbour internal and

external cells (Handover command messages)

PERINC_SUC

SUM PER_SUCC For all INTCELL and EXTCELL =

CELL

internal and external cells.(Handover Complete) Ie SUM of HOSSUC for

INTCELL and EXTCELL = this cell as a percentage of Sum incoming

PERINC_REV

SUM PER_REV For all INTCELL and EXTCELL =

CELL

The sum of all handover reversions from neighbouring internal and

external cells (Handover failure message)

PERINC_LOST

SUM PER_LOST For all INTCELL and EXTCELL =

CELL

(Sum incoming handover failure) as a percentage of Sum incoming

handover attempt.

SUMOUTHOATT SUM HOVERCNT For all SCELL = CELL

and external cells. Ie sum of HOATT for this cell = SCELL for both

internal and external n-cells



44/71

4.6a COUNTERS FOR LOCATING FUNCTION - HANDOVER REASONSWhenever a locating individual sends a hand over request to the CP for execution, the reason

for the hand over request is counted

These counters are stepped even if the request does not lead to a hand over, due to congestion

in the target cell or other reasonThere are separate counter object types for internal and external neighbors

Counter HODUPFT counts ping pong events. When a normal hand over occurs, if another

normal hand over back to the old cell occurs within 10 seconds, HODPUFT is stepped. This

should not be confused with a hand over failure (reversion), where the MS could not establish a

connection on the new cell and reverts to the old cell

NCELLRXT Handover causes fo r in tra BSC handovers, cel l s on same BSC (INT)HOTOLCL Stepped when handover to better cell, L-cell criterion met

HOTOKCL Stepped when handover to better cell, K-cell criterion met

HOUPLQA Stepped when handover to due to bad uplink quality. BTS(RxQual) > QLIMUL

HODWNQA Stepped w hen handover due to bad dow nlink quality. MS(RXQual) > QLIMDL

HOEXCTA Stepped w hen handover due to excessive timing advance. TA > TALIM

HODUPFT Stepped when a normal handover back to old cell from new cell occurs within 10 secNECELLRXT Handover causes fo r in ter BSC handovers, cel l s on d i f feren t BSC (EXT)

HOTOLCL Stepped when handover to better cell, L-cell criterion met

HOTOKCL Stepped when handover to better cell, K-cell criterion met

HOUPLQA Stepped when handover to due to bad uplink quality. BTS(RxQual) > QLIMUL

HODWNQA Stepped w hen handover due to bad dow nlink quality. MS(RXQual) > QLIMDL

HOEXCTA Stepped w hen handover due to excessive timing advance. TA > TALIMHODUPFT Stepped when a normal handover back to old cell from new cell occurs within 10 sec


4 6b COUNTERS FOR LOCATING HAND OVER REASONS


45/71

CELL-A

BSC

RP

CP


REPORTS TO THE BSC ONTHE SACCH

HANDOVER COMM AND

4.6b COUNTERS FOR LOCATING - HAND OVER REASONS

HOVERCNT

LOCATING INDIVIDUAL

IN RP PROCESSES

REPORTS

AND REQUESTS

HANDOVER

FROM CP WHEN

REQUIRED,

HOTOLCL

HOTOKCL

HOUPLQA

HODWNQA

HOEXTA

RP SENDS HANDOVER

REQUEST TO CP, AND

HAND OVER REASON

COUNTERS ARE STEPPED

TCALLS

TCALLS IS ALSO STEPPED

EVEN IF NO HANDOVERCOMMAND IS SENT BY CP


4 6 COUNTERS FOR LOCATING HAND OVER PING PONG


46/71

CELL-A CELL-B

BSC

RP RP

CP

1: A SUCCESSFUL HANDOVERE IS EXECTUTED FROM CELL A TO CELL B

HANDOVER COMMAND

4.6c COUNTERS FOR LOCATING - HAND OVER PING-PONG

HANDOVER COMPLETE

HODUPFT

2: A TIMER IS STARTED IN THE CP. IF A HAND OVER FROM CELL B TO

CELL A OCCURS WITHIN 10 SECONDS, PING-PONG COUNTER IS STEPPED

HANDOVER COMMANDHANDOVER COMPLETE



47/71

4.6d MEASUREMENT FORMULAS FOR LOCATING : N-CELL MEASUREMENTS

The measurements are made per n-cell

PER_DUPFT is percentage of hand overs that result in a hand back to the old cell within 10

seconds (ping-pong effect_

PER_DECISION is the total number of hand over requests sent to the CP as a function of

actual hand over commands sent. Should be ~100% until cell experiences congestion

Other measurements are hand over reasons. LCL is path loss, KCL is normal signal strength,

UPLQA is up link quality, DWNQA is down link quality, EXCTA is excessive timing advance

HANDOVER


PER_DUPFT (HODUPFT) / (HOVERSUC) * 100%

Ratio of handback to normal cell within 10 seconds to succesful

handovers

PER_DECISIONHOVERCNT * 100%(HOTOLCL+HOTOKCL+HOUPLQA+HODWNQA+HOEXCTA) Ratio of actual handover attempts to total of all handover decisions

PER_LCLHOTOLCL * 100%

(HOTOLCL+HOTOKCL+HOUPLQA+HODWNQA+HOEXCTA)

Ratio of handover decisions due to L cell path loss criterion to sum of all

handover decisions

PER_KCLHOTOKCL * 100%


Ratio of handover decisions due to K cell signal strength criterion to sum

of all handover decisions

PER_UPLQAHOUPLQA * 100%


Ratio of handover decisions due to uplink bad quality urgency criterion

to sum of all handover decisions

PER_DWNQAHODWNQA * 100%


Ratio of handover decisions due to downlink bad quality urgency

criterion to sum of all handover decisions

PER_EXCTAHOEXCTA * 100%


Ratio of handover decisions due to excessive timing advance urgency

criterion to sum of all handover decisions



48/71

4.6e MEASUREMENT FORMULAS FOR LOCATING : CELL MEASUREMENTS

As with hand over events, it is useful to sum hand over reasons together on a per cell basis

Outgoing hand over reasons on a per cell basis can be useful indicators of a cells performance

Cells with large percentage of outgoing urgency hand overs need attention!

PEROUT_DUPFT SUM PER_DUPFT For all SCELL = CELL

Sum of a ll outgoing successful handovers that handback to the serving

cell within 10 seconds as a function of a ll successful outgoing handovers

PEROUT_DECISION SUM PER_DECISION For all SCELL = CELL

Ration of the sum of all outgoing handover attempts to sum of all

outgoing handover decisions

PEROUT_KCL SUM PER_kcl For all SCELL = CELL

Sum of all outgoing handover attempts due to signal strength K cell

criterion as a percentage of Sum outgoing handover.

PEROUT_LCL SUM PER_LCL For all SCELL = CELL

Sum of all outgoing handover attempts due to path loss L cell criterion

as a percentage of Sum outgoing handover

PEROUT_DWNQA SUM PER_DWNQA For all SCELL = CELL

Sum of all outgoing handover attempts due to Down link Quality urgency

condition, as a percentage of Sum outgoing

PEROUT_UPLQA SUM PER_UPLQA For all SCELL = CELL

Sum of all outgoing handover attempts due to Up link Quality urgency

condition, as a percentage of Sum outgoing

PEROUT_EXCTA SUM PER_EXCTA For all SCELL = CELL

Sum of all outgoing handover attempts due to excessive Timing

Advance urgency condition, as a percentage of Sum outgoing

HANDOVER

MEASUREMENTS FORMULA DESCRIPTION (MEASUREMENTS ARE PER CELL)



49/71

4.7a COUNTERS FOR ASSIGNMENT TO ANOTHER CELL

Assignment to another cell occurs when a call is set up on the SDCCH of one cell, and

allocated a TCH on a different cell. The TCH allocation is executed with a HAND OVER

process, as opposed to the ASSIGNMENT process, when the TCH is on the same cell as theSDCCH.

Assignment to another cell can be to a better cell, when locating finds a better cell to connect

to during the signaling phase of the call, when the connection is on the SDCCH.

Assignment to another cell can be to a worse cell, when there is TCH congestion on the serving

cell, which would otherwise result in call set up failure.

Assignment to other cells are collected per neighbor relation, and different object types exist

for internal and external neighbors, as with hand over counters

HOASBCL Stepped w hen assignment to a better cell during call setup is attempted

HOASWCL Stepped when assignment to a worse cell during call setup is attempted

HOSUCBCL Stepped w hen assignment to a better cell during call setup is successful

HOSUCWCL Stepped w hen assignment to a better cell during call setup is successful

HOASBCL Stepped w hen assignment to a better cell during call setup is attempted

HOASWCL Stepped when assignment to a worse cell during call setup is attempted

HOSUCBCL Stepped w hen assignment to a better cell during call setup is successful

HOSUCWCL Stepped w hen assignment to a better cell during call setup is successful

NECELLRXT Handover causes for inter BSC handovers, cells on different BSC (EXT)

NCELLRXT Handover causes for intra BSC handovers, cells on same BSC (INT)


4 7b COUNTERS FOR ASSIGNMENT TO ANOTHER CELL


50/71

BSC MSC

HANDOVER COMMAND

SABM/UA

HANDOVER COMPLETE HANDOVER COMPLETE

(CAUSE= DIRECTED RETRY)

ASSIGNMENT REQUEST

TASSAL

TCASSAL

4.7b COUNTERS FOR ASSIGNMENT TO ANOTHER CELL

HANDOVER COMMAND

HANDOVER COMPLETE

MS MOVES FROM SDCCH ON

CELL A TO THE TCH ON

CELL B

SIGNALLING CONNECTION ON SDCCH ALREADY ESTABLISHED BETWEEN MS AND MSC ON CELL A

CELL-B

CELL-A

HOASBCL,HOASWCL

HOSUCBCL,HOSUCWCL

BSC LOCATING ASSIGNS

CONNECTION TO CELL B



51/71

4.7c MEASUREMENT FORMULAS ASSIGNMENT TO ANOTHER CELL

Assignment attempts to better and worse cell are counted

The success rate of assignment to better or worse cell is measured

Measurements are made per n-cell

The per n-cell measurements are summed for outgoing events for each cell as well

HOASBCL HOASBCL Number of assignment handovers to better cell attempts

PER_SUCBCL (HOSUCBCL / HOASBCL) *100% Success rate of assignment handovers to better cell

HOASWCL HOASWCL Number of assignment handovers to worse cell attempts

PER_SUCWCL (HOSUCWCL / HOASWCL ) * 100% Succe ss ra te of assignment handovers to w orse ce ll

SUMOUT_ASBCL

SUM HOASBCL for all INTCELL & EXTCELL =

CELL Number of assignment attempts to a better cell during call set up

PEROUT_SUCBCL

SUM PER_SUCBCL for al l INTCELL and EXTCELL

= CELL

Number of successful assignment a ttempts to a better ce ll as a

percentage of number of assignments to better cell

SUMOUT_ASWCL

SUM HOASWCL for all INTCELL & EXTCELL =

CELL Number of assignment attempts to a worse cell during call set up

PEROUT_SUCWCL

SUM PER_SUCWCL for all INTCELL and EXTCELL

= CELL

Number of successful assignment a ttempts to a worse cell as a

percentage of number of assignments to worse cell.

HANDOVER


HANDOVER


ttype Ext or Int External for inter BSC and int for intra BSC handovers


4 8 CO S O A C A O


52/71

4.8a COUNTERS FOR INTRA CELL HAND OVER

Intra cell hand over is an auxiliary radio network function, that moves a connection from one

timeslot to a different timeslot within a cell, when conditions of high signal strength and bad

quality exists.An intra cell hand over may be triggered by bad quality on the up link, down link or both

An intra cell hand over is executed by locating sending a request to the CP, and the CP sending

an ASSIGNMENT COMMAND to the MS, telling the MS to move to a different timeslot on the

same cell

If the assignment is unsuccessful, the MS will revert to the old timeslot and send

ASSIGNMENT FAILURE back to the BSC

HOINUQA Stepped when an intra cell handover is attempted due to bad upink qualityHOINDQA Stepped when an intra cell handover is attempted due to bad downlink quality

HOINBQA Stepped when intra cell handover due to both uplink and downlink quality occurs

HOINSUC Stepped w hen intra cell handover is successful

HOINBOCHStepped when intracell handover fails and MS re turns to old channel

CELLEVENT Subcel l change and i ntra cel l handover counters


4 8b COUNTERS FOR INTRA CELL HANDOVER


53/71

CELL-A

BSC

RP

CP


REPORTS TO THE BSC ON

THE SACCH

ASSIGNMENT COMM AND

4.8b COUNTERS FOR INTRA CELL HANDOVER

LOCATING PROCESS

DETECTS BAD QUALITY

AND HIGH SIGNAL

STRENGTH, INTRA CELL

HAND OVER CRITERION

IS MET.

HOINUQA

HOINDQA

HOINBQA

RP SENDS INTRA CELL

HANDOVER REQUEST TO

CP, IHO COUNTERS STEP

CP SENDS ASSIGNMENT

COMMAND TO MS TOMOVE MS TO ANOTHER

TIMESLOT

ASSIGNMENT COMPLETE

ASSIGNMENT FAILURE

HOINSUC

HOINBOCH

MS MOVES TO NEW TIMESLOT AND

SENDS ASSIGNMENT COMPLETE.

IF MS CANNOT ESTABLISH CONNECTIONON NEW TIMESLOT,

IT GOES BACK TO THE OLD TIMELSLOT

AND SENDS ASSIGNMENT FAILURE

TCALLS



54/71

4.8c MEASUREMENT FORMULAS FOR INTRA CELL HAND OVER

The number of successful intra cell hand overs is counted

The percentage of successful intra cell hand overs is measured in relation to total intra cell

hand over attempts

The percentage of reversions to old channel are measured in relation to total iho attempts

The percentage of iho attempts due to up link, down link or both in relation to total iho

attempts is measured.

There is no counter for intra cell hand overs executed, (ASSIGNMENT COMMANDS sent),so

ho_in_lost ratio may be wrong if cell has congestion. This is because an intra cell hand over

request may be denied by the CP if all timeslots are seized.

ho_in_suc HOINSUC Number of successfulintra cell handover attempts performed in the cell

ho_in_suc_ratio

HOINSUC *100%

(HOINUQA+HOINDQA+HOINBQA)

Number of successful intra cell handovers as a percentage of intra cell

handover attempts

ho_in_rev_ratio

HOINBOCH *100%


Number of reversions to old channel as a percentage of intra cell

handover attempts

ho_in_lost_ratio

HOINBOCH) (HOINUQA+HOINDQA+HOINBQA)

*100%

The difference between successful + reverted intra cell handover

attempts as a percentage of intracell handover attempts

ho_in_dwnqa_ratio

HOINDQA *100%


Number of intra cell handover attempts due to Down link quality as a

percentage of number of intra cell handover attempts

ho_in_uplqa_ratio

HOINUQA *100%


Number of intra cell handover attempts due to Up link quality as a

percentage of intra cell handover attempts

ho_in_badqa_ratio

HOINBQA *100%


Number of intra cell handover attempts due to both uplink and downlink

quality as a percentage of intra cell handover attempts

HANDOVER



4 9 COUNTERS FOR IDLE CHANNEL MEASUREMENTS


55/71

4.9a COUNTERS FOR IDLE CHANNEL MEASUREMENTS

Idle channel measurements are measurements made by the BTS of the up link channel. When

a timeslot at the BTS is idle (not seized), measurements of the received power level are made.

This power measured is back ground noise or interference in the up linkMeasurements are averaged over a period of time, and each time slot is placed in an

interference band. When measured power changes from one interference band to another, this

change is reported by the BTS to the BSC. The BSC collects statistics from each BTS, of the

number of times each TS was in each interference band

Separate measurements are made for overlay and underlay sub cells

IDLECH Coun ters for Id le channel m easurem ents

NOACC The total number of idle channel measurements collected

ITOSIB1 The number of idle channel measurements in interference band 1 in the overlaid subcell



ITOSIB4 The number of idle channel measurements in interference band 4 in the overlaid subcellITOSIB5 The number of idle channel measurements in interference band 5 in the overlaid subcell

ITUSIB1 The number of idle channel measurements in interference band 1 in the underlay subcell






4 9b COUNTERS FOR IDLE CHANNEL MEASUREMENTS


56/71

BTS

BSC

RP

CP

4.9b COUNTERS FOR IDLE CHANNEL MEASUREMENTS

I TOSIB1, ITUSIB1

ITOSIB2, ITUSIB2

ITOSIB3, ITUSIB3

ITOSIB4, ITUSIB4

ITOSIB5, ITUSIB5

EVERY FEW SECONDS, THE POWER

LEVEL MEASURED IN IDLE TIMESLOTS

IS MEASURED BY THE BTS. BASED ON

THE POWER MEASURED, EACH TS IS

PLACED IN AN INTERFERENCE BAND

THE CP ACCUMULATES

NUMBER OF ICMMEASUREMENTS IN EACH

BAND FOR EVERY CELL

BAND 1 = -110dBm to -105dBm




BAND 5 = > -83dBm

CHANGES FROM 1 BAND

TO ANOTHER ARE SENT

FROM THE BTS TO BSC



57/71

4.9c MEASUREMENT FORMULAS FOR IDLE CHANNEL MEASUREMENTS

The number of accumulations of idle channel measurements are counted

The number of measurements, and the percentage of total measurements in each band

are measured

Measurements for underlay sub cells only are currently made

idlech_acc_num NOACC Number of 10 second accumulations of idel channel measurements

idlech_itub1 ITUSIB1 Number or measurements in interference band 1

idlech_itub1_ratio

(ITUSIB1) / * 100%

(ITUSIB1+ITUSIB2+ITUSIB3+ITUSIB4+ITUSIB5) % of total measurements in interference band 1


idlech_itub2_ratio

(ITUSIB2) / * 100%



idlech_itub3_ratio

(ITUSIB3) / * 100%



idlech_itub4_ratio

(ITUSIB4) / * 100%



idlech_itub5_ratio

(ITUSIB5) / * 100%



4 10a COUNTERS FOR CELL LOAD SHARING


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4.10a COUNTERS FOR CELL LOAD SHARING

Cell load sharing is a method to reduce temporary congestion on a cell by dynamically

reducing the hand over hysterysis border of a cell when the traffic load in a cell reaches a

certain level. Mobiles located near the borders with surrounding cells will then be handed overto these surrounding cells, thus shedding some of the traffic load on the congested cell.

Counters are collected per cell, from object type CELLEVENT

Hand overs due to load sharing and O+M intervention are counted.

LSTIME Number of times that cell load sharing threshold was met in the cell

TIME Total time in seconds that load sharing threshold was met in the cell

HOATTLS Number of handover attempts from the cell due to load sharingHOSUCLS Number of successful handover attempts from the cell due to load sharing

HOATTBL Number of handover attempts from the cell due to O+M intervention

HOSUCBL Number of successful handover attempts from the cell due to O+M intervention

CELLEVENT Subcel l change and in tr a cel l handover coun ter s


4.10b COUNTERS FOR CELL LOAD SHARING


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BTS

BSC

RP

CP

4.10b COUNTERS FOR CELL LOAD SHARING

LSTIM E, TIM E

HOATTLS, HOSUCLS

HOATTBL, HOSUCBL

1:WHEN THE NUMBER OF IDLE CHANNELS IN THE CELL

FALLS BELOW A SET LIMIT, CELL LOAD SHARING IS

INITIATED

THE CP COUNTS THE

NUMBER OF HAND OVERATTEMPTS DUE TO LOAD

SHARING, AND THE

NUMBER OF SUCCESSFUL

HAND OVERS

2: KHYST AND LHYST ARE GRADUALLY REDUCED TO

OFFLOAD MS LOCATED NEAR CELL BORDERS TO

SURROUNDING CELLS



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4.10c MEASUREMENT FORMULAS CELL LOAD SHARING

The percentage of time that cell load sharing threshold was met or exceeded is measured

The number of load sharing hand overs and the success rate is measured

The number of O+M hand overs and the success rate is measured

lsh_time_ratio (LSTIME/TIME) * 100% Percentage of the time that cell load sharing criterion was met

ho_lsh_att HOATTLS Number of handover attempts due to load sharing

ho_lsh_suc_ratio (HOSUCLS/HOATTLS) * 100% Succe ss ra te of load sha ring ha ndove rs (outgoing)

ho_onm_att HOATTBL Number of handovers due to O + M intervention

ho_onm_suc_ratio (HOSUCBL/HOATTBL) * 100% Success rate of O + M handovers


4.11a COUNTERS FOR OVERLAY/UNDERLAY SUBCELLS


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4.11a COUNTERS FOR OVERLAY/UNDERLAY SUBCELLS

The CME-20 BSS allows for cells to be partitioned into overlay/underlay sub cell structures, to

increase capacity. The overlay sub cell is operated at a lower ERP to allow a tighter frequency

re-use pattern to be utilized. Mobiles that are close to the BTS are handed down to the lowpower overlay sub cell, as mobiles move away from the cell, and the path loss increases, they are

handed back up to the standard underlay cell

Sub cell changes are executed by the BSC sending an ASSIGNMENT COMMAND to the MS

to move the MS from a timeslot on the underlay sub cell, to a timeslot on the overlay sub cell, or

vice versa. The operation is similar to an intra cell hand over. Counters are available to count

such sub cell change events.

There are also counters in object type CELLTCH and CELLSDCCH to count traffic,availability and congestion in the overlay sub cell, where a sub cell exists. The normal SDCCH

and TCH counters by default count traffic in the underlay sub cell, or where no sub cell

structure is defined

Sub cell changes can occur due to timing advance or path loss

CELLEVENT Subcel l ch ange and i ntr a cel l h ando ver coun ter s

HOAATOL Stepped when an assignment from UL to OL is attempted

HOSUCOL Stepped when an assignment from UL to OL is successful

HOAATUL Stepped when an assignment from OL to UL is attempted

HOSUCUL Stepped when an assignment from OL to UL is successful


4.11b COUNTERS FOR OVERLAY/UNDERLAY SUBCELLS


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4.11b COUNTERS FOR OVERLAY/UNDERLAY SUBCELLS

SDCCH AND TCH TRAFFIC, AVAILABILITY AND CONGESTION

CELLSDCCH SDCCH counters

CCALLSSUB As for CCALLS but for overlaid subcell

CMSESTBSUB As for CMSESTB but for overlaid subcell

CCONGSSUB As for CCONGS but for overlaid subcell

CTCONSUB As for CTCONGS but for overlaid subcell

CTRALSUB As for CTRALACC but for overlaid subcellCNUCHSUB As for CNUCHCNT but for overlaid subcell

CAVASUB As for CAVAACC but for overlaid subcell

CELLTCH TCH counters

TCALLSSUB As for TCALLS but in overlaid subcell

TMSESTBSUB As for TMESTB but for overlaid subcell

TCONGSSUB As for TCONGS but in overlaid subcell

TTCONSUB As for TTONGS but for overlaid subcell

TAVASUB As for TAVACC but for overlaid subcell

TTRALSUB As for TTRALACC but for overlaid subcell

TNUCHSUB As for TNUCHCNT but for overlaid subcell

Note: There is no dropped call counter for overlay sub cells


4.11c COUNTERS FOR OVERLAY/UNDERLAY SUB CELLS


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BTS

. c COUN S O OV /UN SU C S

HOAATUL

THE BSC ORDERS A SUB CELL CHANGE FROM

OVERLAY TO UNDERLAY WHEN PATH LOSS

OR TIMING ADVANCE CRITERIA MET

OL UL

BSC

ASSIGMNENT COMMAND ASSIGMNENT COMPLETE

HOSUCUL


4.11d COUNTERS FOR OVERLAY/UNDERLAY SUB CELLS


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BTS

HOAATOL

THE BSC ORDERS A SUB CELL CHANGE FROM

UNDERLAY TO OVERLAY WHEN PATH LOSS

OR TIMING ADVANCE CRITERIA MET

OL UL

BSC

HOSUCOL

ASSIGMNENT COMMANDASSIGMNENT COMPLETE



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4.11e MEASUREMENT FORMULAS FOR OVERLAY/UNDERLAY SUB CELLS

The number of attempts to move from overlay to underlay, and from underlay tooverlay is measured

The percentage successful of each is also measured

Traffic, availability and congestion measurements are not currently produced, but

formulas are the same as for normal cell measurements

ho_tol_att HOAATOL Number of handover attempts from underlaid to overlaid subcell

ho_tol_suc_ratio (HOSUCOL/HOAATOL) * 100% Success rate of UL - OL handovers

ho_tul_att HOAATUL Number of handover attempts from overlaid to underlaid subcell

ho_tul_suc_ratio (HOSUCUL/HOAATUL) * 100% Success rate of OL - UL handovers


5.1a MANAGEMENT OVERVIEW REORTS


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5.1a MANAGEMENT OVERVIEW REORTS

Reports are available that summarize key performance indicators of the network. Cells

are grouped by BSC and by geographical region. KPI reported include:Subscriber perceived dropped call rate

Call completion ratio *

Traffic level

Congestion

Handover Success Rate

* Call completion ratio is measured as assignment success ratio on TCH channels, which

ignores call set up failures due to incomplete or dropped SDCCH seizures, hence this

number is very optimistic.


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5.2a NETWORK PLANNING

Average daily traffic and cell busy hour traffic is measured for each cell. This can be

used to calculate cell utilization. Once a cell reaches a certain utilization level, additionaltransceivers can be added so that congestion in the future, as traffic level grows.

Once the point where no more transceivers can be added is reached, planning can be

made for addition of more macro-cells (cell splitting) or micro cells to provide additional

capacity where required

Cell busy hour is used, not system busy hour. Different cells will be at their busiest at

different times of the day. Some cells will be busy in the morning, others in the afternoon,

and so on

Dropped call rate and dropped call reasons can be used as a justification for more cell

sites. Regions that have high dropped call rate, with most of the drops being due to signal

strength, require more cell sites to increase coverage density


5 3 NETWORK OPTIMIZATION


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5.3a NETWORK OPTIMIZATION

Performance measurements can be used as an aid to network optimization work

Performance measurements complement optimization activities, they are not areplacement for field optimization work

Optimization can be concentrated on areas with high traffic, as this will have the biggest

impact on subscriber quality. Eg a cell that only carries 20 calls a day, of which 10 drop,

will have a dropped call rate of 50%. But why waste time on that cell !

Efforts should be concentrated on cells with the following

High traffic and high Erlang drop call rate

Cells with high level on intra cell hand overs

Cells with low level of incoming hand over success rate

Cells with high level of outgoing hand overs due to urgency conditions

Cells with short mean holding time

Cells with high levels of dropped calls due to quality or unknown reasons


5 3b NETWORK OPTIMIZATION


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5.3b NETWORK OPTIMIZATION

MEASUREMENT IDEA L GOOD NEEDS WORK

SDCCH COMPLETION RATE 100% >85% 97% 97% 90% >80%

SDCCH/TCH DROPS QA 0% 20%

SDCCH/TCH DROPS TA 0% 20%

SDCCH /TCH DROPS OT 0% 20%

CONGESTION RATIO 0% 5% 30%

CONGESTION PROBABILITY 0% 5%

TCH MEAN HOLDING TIME NA >30 SEC 97% 80% 99% >95%

ICM MEASUREMENTS OTHER BAN 0%


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5.4a NETWORK ALARMS

Radio Perf Meast

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