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Course Title Introduction to GSM QoS and traffic load monitoring / B9
Course Number 3FL10491ABAA
Audience
Customer personnel in charge of the radio optimization, quality of service and radio traffic-engineering.
Objectives
During this training, the participant will learn how interpret counters and indicators of the Alcatel BSS System.
By the end of the course, the participant will be able to interpret :
- Global indicators, in order to assess the general quality of the network
- Detailed indicators, in order to detect / identify / locate the main malfunctions
- Handover indicators, in order to quantify efficiency and reason of HO
- Directed retry indicators, in order to quantify efficiency of directed retry
- RMS indicators to ease radio optimisation and fault detection
- Traffic indicators, in order to detect/predict overload and compute adequate cell dimensioning as well as to understand how RTCH resources are used in the network
Prerequisites
In depth knowledge of GSM BSS system architecture
Windows literate
Training Methods
Theory and practice on PC
Language
English - French
Duration
5 days
Location
Alcatel University or Customer Premises
Number of participants
8 maximum
Course content
1 Introduction 1.1 Monitoring the Qos of the BSS
1.2 Monitoring the traffic Load of the BSS
1.3 Information sources available
1.4 Introduction to K1205 PC emulation
2 Global Indicators 2.1 Indicators definition
2.2 Methodological precautions
2.3 Typical call failures
2.4 Description of global indicators
2.5 Traps and restrictions of global indicators
2.6 Global indicators interpretation
3 Detailed Indicators 3.1 Indicator reference name
3.2 Indicators classification
4 HO Indicators 4.1 Intra-cell handover indicators per cell
1- To be able to interpret Global indicators, in order to assess the general quality of the network
2- To be able to interpret Detailed indicators, in order to detect / identify / locate the main malfunctions
3- To be able to interpret Handover indicators, in order to quantify efficiency and reason of HO
4- To be able to interpret Directed retry indicators, in order to quantify efficiency of directed retry
5- To be able to interpret RMS indicators to ease radio optimisation and fault detection
6- To be able to interpret Traffic indicators, in order to detect/predict overload and compute adequate cell dimensioning as well as to understand how RTCH resources are used in the network
Contract number :
Course title :
Client (Company, centre) :
Language : dates from : to :
Number of trainees : Location :
Surname, First name :
Did you meet the following objectives ?
Tick the corresponding box
Please, return this sheet to the trainer at the end of the training
1.2 Monitoring the Traffic Load of the BSS Definition
> Measure the "quantity" of traffic handled by:
• the network
• the BSCs
• the cells
> Analyze traffic characteristics
• call, handover, location update, etc.
> As input for dimensioning/architecture team
> Traffic characteristics used as a "call mix" to dimension or re-dimension the network will be developed in the section Monitoring the Traffic Load of the BSS.
> The main advantage of the A interface is to allow the detection of Call Setup failures either due to the User or to the NSS (or PSTN).
> Some typical user failure causes are: Some typical NSS failure causes are:
IMSI Unknown in VLR Temporary FailureIMSI Unknown in HLR Resource UnavailableIMEI Not Accepted Switching Equipment CongestionPLMN Not Allowed Normal UnspecifiedService Option Not Supported Recovery on Timer ExpiryRequested Service Not Supported Call Reject Unassigned Number InterworkingOperator Determined Barring Protocol ErrorUser Alerting Network FailureFacility Not Subscribed CongestionNo Route to DestinationNormal Call ClearingUser BusyInvalid Number FormatCall RejectInterworkingNormal Unspecified
> CAUTION: In order to assess the QoS of a BSS or some cells of a BSS, all N7 links between this BSC and the MSC must be traced. Indeed, as the N7 signaling load is spread over all N7 links, signaling messages relating to one call can be conveyed on any of the active N7 links.
> K1103 protocol analyzer can trace up to 8 COCs at the same time but on maximum 4 PCM physical links.
> K1205 protocol analyzer can trace up to 32 COCs at the same time but on maximum 16 PCM physical links.
1.3 Information sources available Abis interface trace
INFORMATION SOURCE: EXTERNAL INTERFACE "Abis"
> Capture/decode signaling between BSC and BTS with "protocol analyzer" (Wandel, Tektronix, Gnnettest, etc.)
+ Complete information (message contents, time-stamp)
+ Possible detection of User/MS/BSS/TC/NSS problems
+ Complete radio information thanks to measurement messages
+ Downlink and uplink
- High cost of equipment
- Time consuming, "post mortem" (installation of tool, file analysis)
- Important expertise needed for analysis
- Very low coverage (A few RSLs, a few cell(s))
- Very large amount of data (>> 10 Mbytes/hour/BTS)
> The main advantage of the Abis trace is to allow a detailed and precise assessment of the radioquality of a cell at TRX level. Both DownLink and UpLink paths can be observed and compared.
> BUT from B7 release, the Radio Measurement Statistics (RMS) feature implemented in the BSS provides a good level of information allowing to reduce the number of Abis traces to be done for radio network optimization.
1.3 Information sources available Air interface trace
INFORMATION SOURCE: EXTERNAL INTERFACE "Air"
> Use trace MS to capture signaling and signal characteristics
+ Give precise location (x,y) of problems
+ Give downlink radio information
+ Only way to localize a lack of coverage
+ Only way to monitor competitor
- High cost of equipment
- Very time-consuming
- Difficulty to perform a lot of calls-> number of samples insufficient
-> only a few streets
- No uplink
> The main advantage of the Air trace is to associate a radio quality measurement to a given geographical area of the network.
> Even if the RMS feature will allow to assess the radio quality as perceived by the end user, no location of the radio problems is provided through the RMS.
> Over a complete network, with breakdown per cell/BSC
> SPECIFIC DRAWBACK
• NSS/PSTN/MS/USER problems not seen
> As BSS PM counters are defined in order to provide information to assess the QoS of the BSS and help to detect BSS misbehavior, there is no way to identify QoS problems due to NSS, PSTN or User.
1.3 Information sources available ALCATEL BSS counters
INFORMATION SOURCES: BSS Counters (1/2)
> Performance Management implementation
• Easy and cost-effective way to monitor network and carried traffic
> Principle:
• For a given duration (granularity period= typically 1 hour)
• To count pre-defined events occurring on the Abis or A interface, or internally.
• Counters stored with breakdown per network component (I.e. cell)
> In the BSS B9, around 1000 counters are available (without GPRS).
> Alcatel has chosen to implement PM counters in the BSC and to increment them mostly on Abis interface signaling messages.
> Other suppliers may have chosen to increment them on A interface signaling messages or to implement them in the BTS.
> Therefore caution should be taken when interpreting QoS indicators value since some discrepancies may be observed due to these possible choices.
In order to provide the operators with an easy and cost-effective way to monitor their network and carried traffic, BSS manufacturers have implemented specific software features, called performance management.
The principle is to count for a given duration called granularity period (typically 1 hour) pre-defined events occurring on the Abis or A interface, or internally. These counters are stored for each duration, with breakdown per network component (i.e. cell).
1.3 Information sources available BSS counter characteristics
Collection mechanism
> Cumulative
• The counter is incremented at the occurrence of a specific event
• Abis or A message, or internal event
• At the end of a collection period, the result is the sum of the events
> Inspection
• Every 20 or 10 seconds, a task quantifies an internal resource status (usually a table)
• At the end of a collection period, the result is the mean value
> Observation
• Set of recorded information about a telecom procedure (handover,channel release, UL & DL measurements reporting)
> Main counters are of cumulative type.
> Inspection counters are of gauge type.
> Observation counters are grouped in a Performance Measurement record associated to a particular GSM BSS telecom procedure: SDCCH channel seizure, TCH channel seizure, internal handover, etc.
> The most important types for QoS monitoring and Radio Network Optimization are in bold.
> A standard PM type can be activated for the whole network. It means that the related counters are reported for all the Network Elements they are implemented on (TRX, CELL, N7 link, X25 link, LAPD link, Adjacency).
> A detailed PM type can be activated only on a sub-set of the network. It means that the related counters are reported only for a limited number of Network Elements:
• 40 cells per BSS for PM types 1, 2, 3, 4, 5, 6, 26, 29
• 15 cells per BSS for PM types 10, 12, 13, 14, 15
> The Call Drop rate at network level has to compared to:
• Contractual threshold: can be requested by the operator management to the operational radio team, can be requested by the operator to the provider on swap or network installation
• Quality threshold: fixed internally by radio team management.
> Quality thresholds are usually more tight than contractual ones.
Specific case of Call establishmentfailure:Loss of messages due to LapD congestioncan be follow with a counter (see notes)LapD
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> The SDCCH resource allocation is performed by the BSC. Once allocated the SDCCH channel is activated by the BTS on BSC request.
> T3101 is the guard timer for the SDCCH access from the MS. The Default value is 3 seconds.
> MC8C counts the number of Channels Required received from the MS in a cell.
> MC148 counts the number of SDCCH channels activated (therefore allocated) in a cell.
> MC8B counts the number of time an MS is commanded to access an SDCCH channel in a cell.
> MC02 counts the number of MSs which have successfully accessed an SDCCH in a cell as part of a Mobile Originating (MO) call.
> The SCCP Connection Request message is conveyed on an A interface PCM timeslot chosen by the BSC (called COC).
> The SCCP Connection Confirm message is conveyed on a COC chosen by the MSC which can be located on a different PCM than the one of the COC used by the BSC to send signaling messages to the MSC.
> Take care than, when the BSC is congested on the downlink, some messages are discarded. This may result for example in call establishment failures, loss of paging messages or delay in handover procedures.
> A LapD counter that indicates the time a LapD link is congested is created to analyze the cause of a degraded quality of service. This counter is implemented in type 7 and thus only be available in a detailed measurement campaign.
• Counter: L1.18: TIME_LAPD_CONG
• Definition: Time in seconds during which the LapD link is congested in transmission in the BSC.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> A paging message is broadcast by the MSC to all BSCs controlling cells belonging to the same Location Area as the one of the paged MS.
> In case no MS is accessing the SDCCH channel (T3101 expiry) then the BSC does not repeat the Immediate Assignment since the MS may have accessed an SDCCH in another BSS. It is up to the MSC to repeat Paging if T3113 expires (usually around 7 seconds).
> MC8A counts the number of Paging Command messages sent on a cell.
> MC01 counts the number of MSs which have successfully accessed an SDCCH in a cell as part of a Mobile Terminating (MT) call.
> Caution:
• A paging Request message sent on the Air interface by the BTS may contain several MS identities. 3 Paging Request types can be used:
• in Paging Request Type 1: up to 2 MSs (IMSI1,IMSI2) can be included.
• in Paging Request Type 2: up to 3 MSs (IMSI1,TMSI1,TMSI2) can be included.
• in Paging Request Type 3: up to 4 MSs (TMSI1,TMSI2,TMSI3,TMSI4) can be included.
• On the other hand, a Paging message and a Paging Command message relate to only one MS identity.
2.3 Typical call failures Radio Link Establishment - Paging
RLE > PagingMC8A=C8A
> Normally all cells of the same Location Area must have the same MC8A counter value since all these cells must be paged for an MT call on an MS located in the Location Area they are included in.
> If not: it means that a cell is not declared in the right LA at NSS level.
2.3 Typical call failures Radio Link Establishment - RACH counter
RLE > RACHMC8C=C8C
> Caution: All Channels Required (therefore RACH) are counted in MC8C: valid and invalid causes (see later). Indeed ghost RACHsare also counted.
> The Channel Required content corresponds to the Channel Request message sent by the MS to the BTS.
> This Channel Request message is made up of one byte with 2 Informations Elements (IEs):8 7 6 5 4 3 2 1
+-----------------------------------------------+│ ESTABLISHMENT │ RANDOM ││ + - - - - - - - - + ││ CAUSE │ REFERENCE │+-----------------------------------------------+
> ESTABLISHMENT CAUSEThis information field indicates the reason for requesting the establishment of a connection. This field has a variable length (from 3 bits up to 6 bits).
> RANDOM REFERENCEThis is an unformatted field with a variable length (from 5 bits down to 2 bits).
> Due to the fact that the NECI bit is always set to 1 in Alcatel BSS, Establishment causes can be divided into 2 categories:
• Valid causes: 5 (6 if GPRS)000: Location Update (Normal, Periodic, IMSI Attach)100: Terminating call101: Emergency call 110: Call Re-establishment111: Originating call (not emergency)011: if GPRS is implemented in the cell
• Invalid causes: 3 (2 if GPRS)001: 010: 011: if GPRS is not implemented in the cell
2.3 Typical call failures Radio Link Establishment - OC success counters split
RLE > success MO splitMC02x=C02x
MC02 =MC02A+MC02B+MC02C+…….+MC02G+MC02H+MC02i
MC02A: LU
MC02B: SMS
MC02C: SS
MC02D: LU follow-on
MC02E: CR
MC02F: unknown
MC02G: IMSI Detach
MC02H: EC or NC
MC02i: LCS
> MC02A = Number of SDCCHs successfully seized for Normal or Periodic LU request (IMSI Attach also counted).
> MC02B = Number of SDCCHs successfully seized for Short Message Service.
> MC02C = Number of SDCCHs successfully seized for Supplementary Service.
> MC02D = Number of SDCCHs successfully seized for LU with follow-on bit set to 1 (means that the SDCCH phase will be followed by a TCH assignment for speech call establishment).
> MC02E = Number of SDCCHs successfully seized for Call Re-establishment.
> MC02F = Number of SDCCHs successfully seized in case of L3 Info (within 08.58 ESTABLISH INDICATION) unknown by the BSC but transferred to the MSC.
> MC02G = Number of SDCCHs successfully seized for IMSI Detach.
> MC02H = Number of SDCCHs successfully seized for Normal or Emergency call.
> MC02i = Number of Mobile Originating SDCCH establishments for LCS purpose.
Also, Evaluation of The Mobiles location (see the next slides)
IMM. ASS. REJECT (immediate assignment reject) MC8D, and MC8B<-------------(AGCH)------------
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> In case of Immediate Assignment Reject: T3122 = value of Wait_Indication parameter sent by the BSC to the MS.
> Otherwise T3120 is computed by the MS as a random number of slots between:
• 250 and 250+T-1 for a phase 1 MS where: T=Tx_integer parameter (1 value per cell chosen between 3 to 50 slots)
• S and T+S for a phase 2 MS where: T=Tx_integer parameter (1 value per cell chosen between 3 to 50 slots)S is a parameter depending on the CCCH configuration and on the value of Tx_integer as defined in the following table:
2.3 Typical call failures Radio Link Establishment - SDCCH cong. causes
RLE > SDCCH congestion
MAIN CAUSES
> Too much SDCCH "normal" traffic for cell SDCCH design
• Radio resource capacity not sufficient (too many calls)
• Inadequate LA design (too many LUs)
> "Common Transport Effect"
• Difficult to avoid for small cells
> Abnormal SDCCH traffic
• ”Phantom" channel requests (seen in SDCCH RF failure session)
• Neighboring cell barred
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> SDCCH congestion can be too high because of the subscribers' traffic demand in terms of calls / LU.
• Solution = add a TRX or site / redesign the LA plan
> High SDCCH congestion can be observed at peculiar period of the day due to a peak of LU requests generated by a big group of subscribers entering a new LA at the same time (bus, train, plane).
• Solution = redesign the LA plan or play on radio parameters (CELL_RESELECT_HYSTERESIS, WI_OP)
> High SDCCH congestion can be abnormally observed without real MS traffic in case a high level of noise or the proximity of a non-GSM radio transmitter.
• Solution = change the BCCH frequency or put an RX filter
> High SDCCH congestion can also be abnormally observed in a cell in case one of its neighboring cell is barred.
2.3 Typical call failures Radio Link Establishment - SDCCH cong. Resolution?
RLE > SDCCH congestion
DYNAMIC SDCCH ALLOCATION
> Too many SDCCHs will lead to a lack of TCH resources... and money.
> Too few SDCCH will result in SDCCH congestion. TCH channels cannot be allocated and, once again, the operator 's revenue decreases.
> At OMC-R level, it is possible to configure:
• a set of static SDCCH/x timeslots to handle normal SDCCH traffic;
• a set of dynamic SDCCH/8 timeslots, which can be used for TCH traffic, or for SDCCH traffic depending on the need.
> "Dynamic SDCCH allocation" feature:
• the BSS is automatically looking after varying SDCCH traffic
• adapted to the situations such as: change of LA, change of SMS traffic
> Useful in very dense (hierarchical) networks:
• optimize the SDCCH configuration becomes more important.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> This feature not only improves SDCCH congestion but also successful TCH assignment rates.
> With the "Dynamic SDCCH allocation" feature, the BSS is automatically looking after varying SDCCH traffic and is particularly adapted to the situations such as: change of LA, change of SMS traffic model, SDCCH traffic varying due to LCS.
> This feature is particularly useful in very dense (hierarchical) networks, where the effort to optimize the SDCCH configuration becomes more important.
If allocation was unsuccessful, then reject SDCCH request (possiblyusing the Immediate Assignment Reject procedure).
MC801a&b
MC802a&b
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> SPECIFIC COUNTERS (Type 110 / Cell Level):
• MC800 Average number of available dynamic SDCCH/8 timeslots.
• MC801a Average number of busy dynamic SDCCH/8 timeslots allocated as TCH (FR or HR).
• MC801b Maximum number of busy dynamic SDCCH/8 timeslots allocated as TCH (FR or HR).
• MC802a Average number of busy SDCCH sub-channels allocated on the dynamic SDCCH/8 timeslots.
• MC802b Maximum number of busy SDCCH sub-channels allocated on the dynamic SDCCH/8 timeslots.These four previous counters are”Inspection Counters” ; that means than the resource is checked regulary by the BSC and at the end of the period, an average is done. Example: 3 physical chanels are defined as Dyn SDCCH and the counter give the following indication:MC801a = 1.7 that means sometimes the 3 Dyn SD are allocated as TCH, sometimes only 2 of them, sometimes 1 or 0 and the average is 1.7
> The FOLLOWING COUNTERS ARE IMPACTED BY the Dynamic SDCCH Allocation feature:
• MC28, MC29 The Number of busy radio timeslots in TCH usage takes into account the busy TCH timeslots and the dynamic SDCCH/8 timeslots allocated as TCH.
• C30, MC31 The Number of busy SDCCH sub-channels takes into account the SDCCH sub-channels allocated on the static and dynamic SDCCH/8 timeslots.
• C370a, MC370a, C370b, MC370b The Number of times the radio timeslots are allocated for TCH usage (FR / HR) takes into account the busy TCH timeslots and the dynamic SDCCH/8 timeslots allocated as TCH.
• C/MC380a/b C/MC381a/b The Cumulated time (in second) the radio timeslots are allocated for TCH usage (FR or HR)does not take care whether the TCHs are allocated on the TCH radio timeslot or on the dynamic SDCCH/8 timeslots.
• C39, MC390, C40, MC400 The Number of times or the Cumulated time (in second) the SDCCH sub-channels are busydoes not take care whether the SDCCH sub-channels are allocated on the static or dynamic SDCCH/x timeslot.
• C/MC34 C/MC380 The Cumulated time (in second) all TCHs / SDCCHs in the cell are busydoes not take care whether the TCHs / SDCCHs are allocated on the TCH radio timeslot /SDCCH/x timeslot or on the dynamic SDCCH/8 timeslots.
• C/MC320a/b/c/d/e Free TCH radio timeslotscount the free TCH timeslots and the free dynamic SDCCH/8 timeslots.
2.3 Typical call failures Radio Link Establishment - Ghost RACH (2/7)
RLE > SDCCH RF Failure
Main causes > "Phantom/Ghost/Spurious/Dummy ... RACH"
> Example of a channel required message
> For this Channel Required, the establishment cause is valid (Call re-establishment) but the Access Delay (corresponding to the distance between the MS and the BTS) is high.
> Indeed the Access Delay being equal to the Timing Advance is coded in slot unit representing a distance of 550m. It can take values from 0 (0m) to 63 (35km).
> Thus the Channel Required above is received from an MS located at 19km from the site. It may therefore be rather a ghost RACH than a real MS which wants re-establish a call.
> In Alcatel BSS, there is possibility to filter the Channel Required received from a distance greater than a distance defined as a parameter value: RACH_TA_FILTER tunable on a per cell basis. Caution should be taken since a too low value may reduce the network coverage.
• 3/8 of causes (field of channel request, 5 valid causes over 8) will be unvalid
• Example of induced SDCCH traffic: (5/8*156*T3101 (3 sec))/3600 = 0.08 Erlang SDCCH
> Some tips:
• Dummy Rach load depends on minimum level for decoding configured in Evolium BTS
• During period with low real traffic (night), high rate of dummy RACH
• For dummy RACH, the channel required has a random value of TA
STRUCTURE of the MULTIFRAME in "TIME SLOT" 0STRUCTURE of the MULTIFRAME in "TIME SLOT" 0STRUCTURE of the MULTIFRAME in "TIME SLOT" 0STRUCTURE of the MULTIFRAME in "TIME SLOT" 0
-
R = RACH
DOWNLINKDOWNLINKDOWNLINKDOWNLINKf s b b b b C C C C
31 51 1211 2 3 4 5 6 7 8 9 10 20 41f s f s f s f sC C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C -
(Multiframes of 51 frames)
f = FCCH s = SCH b = BCCH
f s
C C C C = CCCH (PCH or AGCH)
UPLINKUPLINKUPLINKUPLINKR R R RR R R R R R R RR R R R R R R RR R R R R R R RR R R R R R R RR R R RR R R RR R R R R R
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> Statistically a ghost RACH can correspond to any kind of establishment cause: valid and invalid.
> As ghost RACH which corresponds to a GSM valid cause will lead to an SDCCH allocation which will not be seized by an MS, it will lead to the incrementation of MC149 counter and therefore counted as an SDCCH access failure due to radio.
2.3 Typical call failures Radio Link Establishment - indicators
TYPICAL CALL FAILURES: RLE indicators
SDNAFLBN
SDNAFLRNSDNACGNSDNAFSUNSDNAFLR
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS:
> GLOBAL Quality of service INDICATORS > SDCCH > Assignment Phase
• SDNAUR: SDCCH assignment unsuccess rate
• SDNACGR: SDCCH assignment failure rate due to congestion (Global)
• SDNAFLRR: SDCCH assignment failure rate due to radio
• SDNAFLBR: SDCCH assignment failure rate due to BSS problem
> A SDCCH radio access failure due to ghost RACH occurrence is easily observed during low traffic hour (night time) since ghost RACHs are almost the only cause of failure.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> Transparent messages (DTAP) are used in order the NSS performs control procedures to enable the MS to set up a speech call.
> Authentication: Checks that the Mobile Station is the required station and not an intruder.
> Ciphering: All Information (signaling, Speech and Data) is sent in cipher mode, to avoid monitoring and intruders (who could analyze signaling data).
> Setup/Call Processing: call is being processed between the calling Party and the Called Party.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> MC138 counts the number of SDCCH channel drops due to radio problems.
> Radio problems can be due to coverage, interference and sometimes BSS dysfunction which is not detected as a system alarm the by O&M Fault Management application.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> MC137 counts the number of SDCCH channel drops due to BSS problems.
> A BSS problem can be a BTS/BSC hardware or software failure. It can also be due to a problem on the Abis interface (due to Micro Wave transmission for instance).
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> MC746B counts the number of TCH access failures due to radio problems.
> MC746B counter is implemented at TRX level from B7.
> In case of TCH access failure, the MS will try to revert back to the SDCCH channel. Whether it succeeds in reverting to the SDCCH or not the call establishment fails. On the other hand some MSCs may resend the ASSIGNMENT REQUEST again.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> The number of TCH Assignment failures due to BSS Pb can be correctly deduced and distinguished for preparation and execution phases from B8 with the 2 counters MC140a and MC140b.(see the next slide)
– Rate of RTCH seizures failed during the normal assignment procedure because of radio problems in relation to all RTCHs allocated for TCH assignment procedure.
> This will help a lot to detect bad QOS due to TRX hardware related problem.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> MC736 counts the number of TCH channel drops due to radio problems.
> MC736 counter is implemented at TRX level.
> Radio problems can be due to coverage, interference and sometimes BSS dysfunction which is not detected as a system alarm by the O&M Fault Management application.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> MC739 counts the number of TCH channel drops due to BSS problems reported as "remote TransCoder failure".
> MC739 counter is implemented at TRX level.
> It can usually be a bad quality of the transmission on the Abis interface (Micro Wave) or a faulty hardware component in the TransCoder or even sometimes BSS software/hardware problems.
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> QSCDN = call drop
= drop radio + drop TC + drop internal BSS + drop HO + drop Preemption
= MC736 + MC739 + MC14C + MC621 + MC921C
> TCQHCCN = RTCH success end
= assignment success + incoming (HO+DR) success - outgoing HO
= MC718 + (MC717A+MC717B) - MC712
> As MC718, MC717A, MC717B and MC712 are provided per TRX, the “RTCH success end” indicator (TCAHCCN) can be computed per TRX.
> But since only MC736 (drop radio), MC739 (drop TC) and MC621 (drop HO) are provided per TRX, the “call drop rate” indicator (QSCDR) can be computed per CELL only.
> On the other hand the following call drop indicators can be computed per TRX:
• call drop radio rate (QSCDRR) = call drop radio / RTCH success end
• call drop HO rate (QSCDHR) = call drop HO / RTCH success end
• call drop TC rate (QSCDBTR) = call drop TC / RTCH success end
> Note:
• MC718 counts the number of successful TCH assignments.
• MC717A counts the number of successful internal DRs.
• MC717B counts the number of successful incoming internal and external (HOs+DR) as well as the number of intra cell HOs successfully performed.
• MC712 counts the number of successful outgoing internal and external HOs as well as the number of intra cell HOs successfully performed.
IntraIntraIntraIntra----cell HOcell HOcell HOcell HO
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> QSCDN = call drop
= drop radio + drop TC + drop internal BSS + drop HO + drop Preemption
= MC736 + MC739 + MC14C + MC621 + MC921C
> TCAHSUN = RTCH success
= assignment success + incoming (HO+DR) success
= MC718 + (MC717A+MC717B)
> Whereas some call drop rate indicators are defined per TRX and per CELL, TRX RTCH drop rate indicators are defined at TRX level only.
> As MC718, MC717A, MC717B are provided per TRX, the “RTCH success” indicator (TCAHSUN) can be computed per TRX.
> But since only MC736 (drop radio), MC739 (drop TC) and MC621 (drop HO) are provided per TRX, a global“TRX RTCH drop rate” indicator cannot be provided.
> On the other hand, the following TRX RTCH drop indicators can be computed:
• TRX_RTCH_drop_radio_rate (TCAHCDRTR) = call drop radio / RTCH success
• TRX_RTCH_drop_HO_rate (TCHOCDTR) = call drop HO / RTCH success
• TRX_RTCH_drop_BSS_remote_TC_rate (TCTRTCDTR) = call drop TC / RTCH success
> CAUTION: Intra-cell HO being counted in MC717B and not deduced in the RTCH success computation in order to provide the TRX RTCH drop indicators at TRX level then these indicators may be abnormally low (good) if a large amount of intra-cell HOs are performed in the cell (concentric cell,multiband cell).
call stagecall stagecall stagecall stage A interfaceA interfaceA interfaceA interface cause cause cause cause fieldfieldfieldfield related related related related problemproblemproblemproblem
radio radio radio radio linklinklinklinkestablishmentestablishmentestablishmentestablishment
no messageno messageno messageno message ---- SDCCH congestionSDCCH congestionSDCCH congestionSDCCH congestion---- radio radio radio radio problemproblemproblemproblem----Dummy Dummy Dummy Dummy rachrachrachrach
SDCCH phaseSDCCH phaseSDCCH phaseSDCCH phase Clear Clear Clear Clear RequestRequestRequestRequest ---- radio interface radio interface radio interface radio interface failurefailurefailurefailure---- radio interface radio interface radio interface radio interface failurefailurefailurefailure---- O&M interventionO&M interventionO&M interventionO&M intervention
---- radio radio radio radio problemproblemproblemproblem---- BSS system HW/SW BSS system HW/SW BSS system HW/SW BSS system HW/SW pbpbpbpb----recovery/operatorrecovery/operatorrecovery/operatorrecovery/operator
TCH TCH TCH TCH assignmentassignmentassignmentassignment Assignment Assignment Assignment Assignment FailureFailureFailureFailure ---- no radio no radio no radio no radio resource resource resource resource avalaibleavalaibleavalaibleavalaible---- Radio Interface Radio Interface Radio Interface Radio Interface FailureFailureFailureFailure
---- TCH congestionTCH congestionTCH congestionTCH congestion---- Radio Radio Radio Radio problemproblemproblemproblem
Clear Clear Clear Clear RequestRequestRequestRequest ---- radio interface radio interface radio interface radio interface failurefailurefailurefailure---- radio interface message radio interface message radio interface message radio interface message failurefailurefailurefailure----equipment equipment equipment equipment failurefailurefailurefailure---- O&M interventionO&M interventionO&M interventionO&M intervention---- radio interface radio interface radio interface radio interface failurefailurefailurefailure----preemptionpreemptionpreemptionpreemption
---- radio radio radio radio problemproblemproblemproblem---- HO HO HO HO failure failure failure failure w/o w/o w/o w/o reversionreversionreversionreversion---- Transcoder Transcoder Transcoder Transcoder failurefailurefailurefailure----operator operator operator operator action/recoveryaction/recoveryaction/recoveryaction/recovery---- BSS system HW/SW BSS system HW/SW BSS system HW/SW BSS system HW/SW pbpbpbpb----preemptionpreemptionpreemptionpreemption
LAPD counter to analyze the cause of call establishment failures
Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase
> When the BSC is congested on the downlink, some messages are discarded. This may result for example in call establishment failures, loss of paging messages or delay in handover procedures.
A LapD counter that indicates the time a LapD link is congested is created to analyze the cause of a degraded quality of service. This counter is implemented in type 7 and thus is only available in a detailed measurement campaign.
• Counter: L1.18: TIME_LAPD_CONG
• Definition: Time in seconds during which the LapD link is congested in transmission in the BSC.
> In a dense network SDCCH drop rate should be lower than 1%. Indeed the probablity to drop a radio link when the MS is on SDCCH is less than on TCH since the SDCCH phase is shorter (less than 5 seconds) than TCH phase (several tens of seconds).
INDICATOR SDCCH ASSIGN SUCCESS
DEFINITION Total number of SDCCHs successfully seized by mobile during radio link establishmentprocedure
> In a dense network, the TCH assignment unsucess rate should be lower a 1%.
INDICATOR
TCH ASSIGN SUCCESS
DEFINITION Number of TCH successfully seized by MS for normal assignment procedure.
FORMULA B8 Σ TRX (MC718)
THRESHOLD
COMMENT
REF NAME TCNASUN UNIT Number
I N D I C A T O R T C H A S S I G N R E Q U E S T S
D E F I N I T I O N N u m b e r o f T C H s e i z u r e r e q u e s t s f o r n o r m a l a s s i g n m e n t p r o c e d u r e .
F O R M U L A B 8 Σ c e l l M C 1 4 0 a
T H R E S H O L D
C O M M E N T M C 1 4 0 a : n e w c o u n t e r i n t r o d u c e d i n B 8 r e l e a s e .
M C 1 4 0 a ( t y p e 1 1 0 ) : N B _ T C H _ N O R _ A S S _ R E Q t h a t i n d i c a t e s t h e n u m b e r o f n o r m a l a s s i g n m e n t
r e q u e s t s f o r T C H e s t a b l i s h m e n t ( i n H R o r F R u s a g e )
R E F N A M E T C N A R Q N U N I T N u m b e r
I N D I C A T O R T C H A S S I G N R E Q U E S T S
D E F I N I T I O N N u m b e r o f T C H s e i z u r e r e q u e s t s f o r n o r m a l a s s i g n m e n t p r o c e d u r e .
F O R M U L A B 8 Σ c e l l M C 1 4 0 a
T H R E S H O L D
C O M M E N T M C 1 4 0 a : n e w c o u n t e r i n t r o d u c e d i n B 8 r e l e a s e .
M C 1 4 0 a ( t y p e 1 1 0 ) : N B _ T C H _ N O R _ A S S _ R E Q t h a t i n d i c a t e s t h e n u m b e r o f n o r m a l a s s i g n m e n t
r e q u e s t s f o r T C H e s t a b l i s h m e n t ( i n H R o r F R u s a g e )
R E F N A M E T C N A R Q N U N I T N u m b e r
I N D I C A T O RI N D I C A T O R T C H A S S I G N R E Q U E S T ST C H A S S I G N R E Q U E S T ST C H A S S I G N R E Q U E S T S
D E F I N I T I O ND E F I N I T I O N N u m b e r o f T C H s e i z u r e r e q u e s t s f o r n o r m a l a s s i g n m e n t p r o c e d u r e . N u m b e r o f T C H s e i z u r e r e q u e s t s f o r n o r m a l a s s i g n m e n t p r o c e d u r e .
F O R M U L A B 8F O R M U L A B 8 Σ c e l l M C 1 4 0 aΣ c e l l M C 1 4 0 a
T H R E S H O L DT H R E S H O L D
C O M M E N TC O M M E N T M C 1 4 0 a : n e w c o u n t e r i n t r o d u c e d i n B 8 r e l e a s e .
M C 1 4 0 a ( t y p e 1 1 0 ) : N B _ T C H _ N O R _ A S S _ R E Q t h a t i n d i c a t e s t h e n u m b e r o f n o r m a l a s s i g n m e n t
r e q u e s t s f o r T C H e s t a b l i s h m e n t ( i n H R o r F R u s a g e )
M C 1 4 0 a : n e w c o u n t e r i n t r o d u c e d i n B 8 r e l e a s e .
M C 1 4 0 a ( t y p e 1 1 0 ) : N B _ T C H _ N O R _ A S S _ R E Q t h a t i n d i c a t e s t h e n u m b e r o f n o r m a l a s s i g n m e n t
r e q u e s t s f o r T C H e s t a b l i s h m e n t ( i n H R o r F R u s a g e )
R E F N A M ER E F N A M E T C N A R Q NT C N A R Q N U N I TU N I T N u m b e rN u m b e r
2.4 Description of global indicatorsCall setup success rate
> CALL SETUP SUCCESS rate: the second most important indicator
• Used to compare PLMN
• Subscriber: call not established at the first attempt
> Beware: call setup failures due to a lack of coverage are not taken into account in this indicator!!
– No way to quantify them (as there is no initial access)
INDICATOR(G)
CALL SETUP SUCCESS RATE (BSS view)
DEFINITION Rate of calls going until TCH successful assignment, that is not interrupted by SDCCH DROP
neither by Assignment failures
FORMULA (1 – ( SDCCH DROP / SDCCH ASSIGN SUCCESS ) ) * (1 TCH ASSIGN UNSUCCESS RATE)
THRESHOLD > 95%COMMENT SDCCH assignment failures are not considered in CSSR as :
·ghost (spurious) RACH cannot be discriminated from a real access failure· effect of re-attempts performed autonomously by the MS cannot be quantified
REF NAME QSCSSR UNIT %
> Ghost Racks which correspond to a valid establishment cause are not identified by the BSS. Therefore they can lead to a high SDCCH assignment failure rate if they are too numerous.
> As the end user is not impacted by this phenomenon if no SDCCH congestion is induced, the SDCCH assignment phase is not considered in the computation of the Call Setup Success rate provided by Alcatel tools.
> In a dense network, the Call Setup Success Rate should be greater than 98%.
> The SDCCH congestion rate should also be considered to have a complete picture of Call Setup efficiency.
COMMENT This indicator includes preparation and execution.
REF NAME HOORSUR UNIT %
INDICATOR
(G)
EFFICIENCY OF OUTGOING HANDOVER EXECUTION
DEFINITION Rate of successful outgoing external and internal intercell SDCCH and TCH handovers
FORMULA Σcell (MC646 + MC656) / Σcell (MC650 + MC660)
THRESHOLD < 90%
COMMENT This indicator takes into account HO execution only (not ho preparation).
REF NAME HOOREFR UNIT %
>Global Outgoing HO success rate: represents the global efficiency ot the outgoing handovers performed from one cell to any of its neighboring cells (same BSS or not).
> Efficiency of Outgoing HO execution: represents the efficiency of the channel change procedure during outgoing handovers performed from one cell to any of its neighboring cells (same BSS or not). It does not take into account the HO failures that can occur during the preparation phase when the new channel is being selected and activated.
2.4 Description of global indicatorsIncoming handover success rate
> Global success rate of Incoming HO
> Success rate of execution of Incoming HO
INDICATOR
(G)
INCOMING HANDOVER SUCCESS RATE
DEFINITION Rate of successful incoming external and internal intercell SDCCH and TCH handovers.
FORMULA Σcell(MC642 + MC652) / Σcell(MC820 + MC830)
THRESHOLD < 90%
COMMENT
REF NAME HOIRSUR UNIT %
INDICATOR
(G)
EFFICIENCY OF INCOMING HANDOVERS
DEFINITION Rate of successful incoming external and internal intercell SDCCH and TCH HOs
FORMULA Σcell (MC642 + MC652) / Σcell(MC821 + MC831)
THRESHOLD < 90%
COMMENT Excluding congestion failures and BSS preparation failures from requests.
REF NAME HOIREFR UNIT %
> Global Incoming HO success rate: represents the global efficiency of the incoming handovers performed to one cell from any of its neighboring cells (same BSS or not).
> Efficiency of Incoming HO execution: represents the efficiency of the channel change procedure during incoming handovers performed to one cell from any of its neighboring cells (same BSS or not). It does not take into account the HO failures that can occur during the preparation phase when the new channel is being selected and activated.
2.4 Description of global indicatorsCall quality factor absolute
> The highest, the best is the cell
> But the traffic handled is not taken into account
INDICATOR(G)
CELL QUALITY FACTOR ABSOLUTE
DEFINITION Indicator summarizing the cell behavior and allowing the operator to sort out cell for investigation.This indicator is based on failure events. For each part of the indicator,twothresholds are used: Topt and TQoS. TQoS is the QoS warning threshold (e.g. above or belowthe threshold, a warning is generated on the cell. Topt + TQoS is the optimal valuethat should be acheived. Each part as a weighting factor (WF) according to the impact on the subscriber’s point of view.
investigation. This indicator is based on failure events. For each part of the indicator, two
> Normalizing the previous Cell Quality Factor Absolute by the traffic of the cell will allow to compare the QoS of the cell between each other and raise the list of top worst cells candidate for analysis.
> Objective: to be able to use the BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS document in order to get some more detailed indicators of the Alcatel BSS
> The Traffic model section includes indicators for:
– number of SDCCH connection requests and successses (Immediate Assignment, HO).
– distribution of SDCCH connection success (MO and MT connections versus all MO+MT connections, type of MO connections versus all MO connection types).
> The MS penetration rate section includes the indicator for:
– percentage of multiband MS SDCCH access (except LU) versus all MS SDCCH accesses.
> The Resource occupancy section includes indicators for:
– SDCCH traffic in Erlang.
– average duration in seconds of SDCCH channel usage.
>The Assignment phase section includes indicators for the Radio Link Establishment procedure: •global SDCCH access failure rate. •specific SDCCH access failure rate per type of problem (SDCCH congestion, radio, BSS).•specific indicators for Dynamic SDCCH Allocation:
Stored Indicators (see Dynamic SDCCH Allocation in the Global Indicators section)DYTROFN.= MC800DYAHCATAN = MC801aDYAHCATMN = MC801bDYAHCASAN. = MC802aDYAHCASMN.= MC802bDYN = number of Dynamic timeslots (given by configuration file) = Cell_NB_DYNComputed indicatorsDYAHCATAR: average rate of busy TCH (FR of HR) allocated on dynamic SDCCH/8 timeslotsFormula: tdiv* (DYAHCATAN,DYTROFN,0,0)DYAHCATMR: maximum rate of busy TCH (FR of HR) allocated on dynamic SDCCH/8 timeslotsFormula: tdiv (DYAHCATMN,DYTROFN,0,0)DYAHCASAR: average rate of busy SDCCH sub-channels allocated on the dynamic SDCCH/8timeslotsFormula: tdiv (DYAHCASAN,DYTROFN,0,0)Impact on existing Indicators: Apart of modification due to introduction of Dynamic SDCCH/8 timeslot, the general formula of these indicators are redesigned, to be simpler.TCRRDN, TCRROFN, TCAHCGUN, TCAVAR (removed as it is the same as TCTRAR), TCTRAVE, TCTRAR, TCTRTCE, SDAHCGUN, SDAVAR, SDRRDN, SDRROFN, SDTRAVE
>The Handover procedure section includes the indicator for the preparation of the SDCCH HO procedure: •rate of SDCCH HO failure due to SDCCH congestion
>The Established phase section includes indicators for SDCCH Phase: •global SDCCH drop rate.•specific SDCCH drop rate per type of problem (radio, HO, BSS).
* tdiv(A,B,0,0) means that it is equal to A/B if B ≠ 0 or to 0 if B = 0
>The Assignment phase section includes indicators for the TCH Normal Assignment procedure: •global RTCH assignment failure rate (called unsuccess rate).•specific RTCH assignment failure rate per type of problem (RTCH congestion, radio, BSS).•global radio congestion level (number of cells congested in the network).
>The Handover procedure section includes indicators for the global HO procedure (intracell+intercellinternal + intercell external):
•rate of RTCH incoming HO failure due to RTCH congestion.•specific RTCH outgoing HO failure rate per type of problem (congestion, radio - Reversion Old Channel, radio drop, BSS).
>The Call Drop section includes indicators for the TCH Phase: •global call drop rate.•specific call drop rate per type of problem (radio, HO, BSS int., TransCoder, preemption).
>The Call Success section includes indicators for the global call procedure (speech): •rate of call setup success.•rate of call success.•global cell quality factor.
– Fast traffic HO taken into account type of counter for dual band HO
Handover causes
HO causes
All
HO
cause
distribution
Outgoing HO Incoming HO
HO standard
cause
distribution
HO cause
category
distribution
HO causes per Adjacency
HO cause
category
distribution
>The Handover causes section includes indicators of HO causes distribution corresponding to outgoing handovers relating to a cell: •distribution of HO causes taking into account all possible HO causes (quality UL, level DL, distance, power budget, concentric cell cause, micro cell cause, traffic, etc.).•distribution of HO standard causes taking into account only HO standard causes (quality UL, quality DL, level UL, level DL, interference UL, interference DL, distance, power budget).
>The Handover causes per adjacency section includes indicators of HO causes distribution corresponding to outgoing and incoming handovers relating to a couple of serving/target cells:
•distribution of HO cause categories taking into account 3 categories (emergency [quality, level, interference, distance, power budget]), better condition [power budget, capture], traffic, forced directed retry).
C449 (type 6) in type 110 (as MC449) improves the result of all HO cause Indicators: (B8 Introduction)C449 = MC449 = number of handover attempts with cause 28 (Fast traffic handover)The Indicator TOTALHO (HCN) is impacted as well as the following indicators:
type 32 of counter (Change of frequency band measurements) (B8 Introduction)Type 32 is defined as Standard and provides information to observe handovers between different frequency bands.C403a = NB_INC_EXT_TCH_HO_NEW_BAND_ATPT = Number of incoming external TCH (in HR or FR usage) handover attempts including a change of the (TCH) frequency band.C403b = NB_INC_EXT_TCH_HO_NEW_BAND_SUCC = Number of incoming external TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.C404a = NB_OUT_EXT_TCH_HO_NEW_BAND_ATPT = Number of outgoing external TCH (in HR or FR usage) handover attempts including a change ofthe (TCH) frequency band.C404b = NB_OUT_EXT_TCH_HO_NEW_BAND_SUCC = Number of outgoing external TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.C420a = NB_INC_INT_TCH_HO_NEW_BAND_ATPT = Number of incoming internal TCH (in HR or FR usage) handover attempts including a change ofthe (TCH) frequency band.C420b = NB_INC_INT_TCH_HO_NEW_BAND_SUCC = Number of incoming internal TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.C421a NB_OUT_INT_TCH_HO_NEW_BAND_ATPT = Number of outgoing internal TCH (in HR or FR usage) handover attempts including a change of the (TCH) frequency band.C421b NB_OUT_INT_TCH_HO_NEW_BAND_SUCC = Number of outgoing internal TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.
– LAPD counter to analyze the cause of delay in HO procedures
Failure With Reversion
Call Drop Rate
Efficiency
Preparation Success Rate
Intra-BSC
Failure With Reversion
Call Drop Rate
Efficiency
Preparation Success Rate
External
Call Drop Rate
Efficiency
Success Rate
Intra-BSC & External
Outgoing HO
>The Outgoing Intra BSC intercell section includes indicators corresponding to the efficiency of outgoing intercell internal handovers relating to a cell (serving):
•efficiency ot the preparation phase (target TCH allocation) of the outgoing handovers performed from one cell to any of its neighboring cells belonging to the same BSS.•efficiency ot the execution phase (old to new TCH channel change) of the outgoing handovers performed from one cell to any of its neighboring cells belonging to the same BSS.•distribution of outgoing intra BSC intercell HO failures per type of problem (radio drop, radio - Reversion Old Channel, BSS).
>The Outgoing Inter BSC intercell section includes indicators corresponding to the efficiency of outgoing intercell external handovers relating to a cell (serving):
•efficiency ot the preparation phase (target TCH allocation) of the outgoing handovers performed from one cell to any of its neighboring cells not belonging to the same BSS.•efficiency ot the execution phase (old to new TCH channel change) of the outgoing handovers performed from one cell to any of its neighboring cells not belonging to the same BSS.•distribution of outgoing inter BSC intercell HO failures per type of problem (radio drop, radio - Reversion Old Channel, BSS).
>The Outgoing Intra BSC + Inter BSC intercell section includes indicators corresponding to the efficiency of all outgoing intercellhandovers relating to a cell (serving):
•global efficiency ot the outgoing handovers performed from one cell to any of its neighboring cells whether they belong to the same BSS or not•efficiency ot the execution phase (old to new TCH channel change) of the outgoing handovers performed from one cell to any of its neighboring cells whether they belong to the same BSS or not.•outgoing intra BSC + inter BSC intercell HO drop rate per type of problem (radio drop, radio - Reversion Old Channel, BSS).
>When the BSC is congested on the downlink, some messages are discarded. This may result for example in call establishment failures, loss of paging messages or delay in handover procedures.A LapD counter that indicates the time an LapD link is congested is created to analyze the cause of a degraded QoS. This counter is implemented in type 7 and thus is only available in a detailed measurement campaign.
Counter: L1.18: TIME_LAPD_CONGDefinition: Time in seconds during which the LapD link is congested in transmission in the BSC.
>The Incoming Intra BSC intercell section includes indicators corresponding to the efficiency of incoming intercell internal handovers relating to a cell (target):
•efficiency ot the execution phase (old to new TCH channel change) of the incoming handovers performed to one cell from any of its neighboring cells belonging to the same BSS.•distribution of incoming intra BSC intercell HO failures per type of problem (congestion, radio, BSS).
>The Incoming Inter BSC intercell section includes indicators corresponding to the efficiency of incoming intercell external handovers relating to a cell (target):
•efficiency ot the preparation phase (target TCH allocation) of the incoming handovers performed to one cell from any of its neighboring cells not belonging to the same BSS.•distribution of incoming inter BSC intercell HO failures per type of problem (RTCH congestion, TTCH (CIC) congestion, radio, BSS)>Using counters introduced in B8 for 3G to 2G Incoming External Handovers,MC922a: NB_INC_EXT_3G_2G_HO_REQ (REQUESTS)
•4 stored indicators based on the 4 counters: HOIMRQUN= MC922a HOIMSUUN = MC922b HOIMFLRRUN = MC922c HOIMCAUN = MC922d
As existing PM counters related to incoming handovers keep a global view, so consider handovers from 2G cells as well as handovers from 3G cells. The pure 2G-2G results can then be obtained by comparing them with the new introduced counters: •4 stored indicators for incoming external handover 2G -2G only:
> In B9 it was introduced more counters for UMTS to GSM handover monitoring. The new counters were introduced in MC922 family:
• MC922e (type110): NB_INC_EXT_TCH_3G_2G_HO_EMERGENCY_REQ that indicates the number 3G to 2G external inter-cell TCH (in HR or FR) handover requests, with emergency cause.
• MC922f (type 110): NB_INC_EXT_TCH_3G_2G_HO_REQ that indicates the number of 3G to 2G external inter-cell TCH (in HR or FR) handover requests. This counters differs from MC922d by the fact it just count TCH handovers.
• MC922g (type 110): NB_INC_EXT_TCH_3G_2G_HO_PREP_FAIL_3GCONG that indicates the number of 3G to 2G handover failures in preparation phase due to 3G high load in target cell.
• MC922h (type 110): TIME_3G_HOReject_HL that indicates the cumulative time (in seconds) during which the cell is in 3G high load state.
B9
>Using counters introduced in B8 for 3G to 2G Incoming External Handovers,MC922a: NB_INC_EXT_3G_2G_HO_REQ (REQUESTS)MC922b: NB_INC_EXT_3G_2G_HO_SUCC (SUCCESS)MC922c: NB_INC_EXT_3G_2G_HO_EXEC_FAIL_MS_ACC (FAILURES)MC922d: NB_INC_EXT_3G_2G_HO_ATPT (ATTEMPTS)
•4 stored indicators based on the 4 counters: HOIMRQUN= MC922a HOIMSUUN = MC922b HOIMFLRRUN = MC922c HOIMCAUN = MC922d
As existing PM counters related to incoming handovers keep a global view, so consider handovers from 2G cells as well as handovers from 3G cells. The pure 2G-2G results can then be obtained by comparing them with the new introduced counters: •4 stored indicators for incoming external handover 2G -2G only:
>The Intracell section includes indicators corresponding to the efficiency of intracell handovers performed within a cell:
•efficiency ot the execution phase (old to new TCH channel change) of the intracell handovers performed within a cell.•distribution of intracell HO failures per type of problem (congestion, radio drop, radio -Reversion Old Channel, BSS).
3.2 Indicators classificationHandover statistics per couple of cells
> Handover STATISTICS
> Handover statistics per couple of cell
HO Success Distribution
Success Rate
Efficiency
Preparation Success Rate
HO statistics
per Couple of Cell
>The Indicators with counters type 180 section includes indicators corresponding to the efficiency of incoming internal+external intercell SDCCH+TCH handovers performed between two cells (serving/target):
•global efficiency of the incoming intercell handovers performed between two cells (serving/target).•efficiency ot the preparation phase (old to new TCH channel change) of the incoming intercellhandovers performed between two cells (serving/target).•efficiency ot the execution phase (old to new TCH channel change) of the incoming intercellhandovers performed between two cells (serving/target).•distribution per couple of (serving/target) cells of the incoming intercell handovers performed to a cell from any of its neighboring cells whether they belong to the same BSS or not.
> Objective: to be able to explain what are the main Handover counters and indicators provided by the Alcatel BSS in order to monitor the quality of handovers
> The T3107 timer is also used as the guard timer of the channel change procedure during an intra cell handover. The Default value for T3107 is 14 seconds.
MC667PHYSICAL CONTEXT REQUEST (new channel)<-----------------------------------------------------------------PHYSICAL CONTEXT CONFIRM (new channel)----------------------------------------------------------------->
RF CHANNEL RELEASE (new channel)<-----------------------------------------------------------------RF CHANNEL RELEASE ACK (new channel)
<---- CLEAR_COMMAND ------ MC642MC646 Cause : HO_SUCCESSFUL
Release of TCH Stop T8
MC462A
MC462B
MC462C
MC463A
MC463B
MC463C
> Both SDCCH and TCH are counted together.
> From B7, MC645A replaces MC645 of B6.
> MC645a is only counting HANDOVER REQUIRED messages that are linked to a handover trial and not those that are linked to the update of the candidate cell list for handover / directed retry. This is leading to a more accurate computation of the External outgoing HO success rate.Only Outgoing inter PLMN HO is allowed.
> 6 counters provide information for "Inter-PLMN HO" (Incoming and Outgoing) (From B8)
• MC462a (equivalent of MC645A for intra PLMN external HO)Number of inter-PLMN TCH outgoing handovers or directed retry requests: HANDOVER REQUIRED sent to the MSC for an external TCH HO or an external DR triggered towards a cell belonging to a PLMN different from the PLMN of the serving cell.
• MC462b (equivalent of MC650 for intra PLMN external HO)Number of inter-PLMN TCH outgoing handovers or directed retry attempts: HANDOVER COMMAND sent to the MS on Abis for an external TCH HO or an external DR triggered towards a cell belonging to a PLMN different from the PLMN of the serving cell.
• MC462c (equivalent of MC646 for intra PLMN external HO)Number of inter-PLMN TCH outgoing handovers or directed retry successes: CLEAR COMMAND with Cause "Handover successful" received from the MSC for an external TCH HO or an external DR triggered towards a cell belonging to a PLMN different from the PLMN of the serving cell.
• MC463a (equivalent of MC820 for intra PLMN external HO)Number of inter-PLMN TCH incoming handovers or directed retry requests: HANDOVER REQUEST received from the MSC for an external TCH HO or an external DR triggered towards the target cell from a serving cell belonging to a PLMN different from the PLMN of the target cell.
• MC463b (equivalent of MC821 for intra PLMN external HO)Number of inter-PLMN TCH incoming handovers or directed retry attempts: HANDOVER REQUEST ACK sent by the target BSC containing the HANDOVER COMMAND for an external TCH HO or an external DR triggered towards the target cell from a serving cell belonging to a PLMN different from the PLMN of the target cell.
• MC463c (equivalent of MC642 for intra PLMN external HO)Number of inter-PLMN TCH incoming handovers or directed retry successes: HANDOVER COMPLETE received from the MS on Abis for an external TCH HO or an external DR triggered towards the target cell from a serving cell belonging to a PLMN different from the PLMN of the target cell.
> Note than all other (previous) counters related to HO continue to be based on Intra PLMN only.
----------CR (HO_REQUEST) -------------------> MC820<-------- CC --------------------------------------- - CHANNEL_ACT ---------->
<--- CHA_ACT_ACK --------<----- HO_REQUEST_ACK----------------------- Start T9113 (HO-COMMAND) included MC821
<-------------------------- HO_COMMAND ------------------------------------------------Start T8 X --- HO_ACCESS -----
X ---- HO_ACCESS ---------- SABM --------><--- UA ------------- -- ESTABLISH_INDICATION->
----- HO_FAILURE (reversion to old channel) ------------------------------------------>----- CLEAR_COMMAND ----------------------> MC643Radio interface fail : Reversion to old channel
Release of connection
> All incoming external HO failures due to radio problems are counted in the same counter MC643.
> Both radio failures with Reversion Old Channel and radio drop are counted together.
6 Radio Measurement Statistics indicatorsSession presentation
> Objective: to be able to describe the RMS indicators used for radio quality assessment of a TRX or cell and to use them in thedetection of some typical radio problems
6.1 Radio Measurement Statistics objectivesRMS objectives
> Assess the quality of cell coverage
> Assess the radio link quality of a TRX / a cell
> Assess Carrier/Interference ratio of a TRX / a cell
> Estimate of the voice quality of a TRX / a cell
In order to:
• Optimize the neighborhood & frequency planning
• Improve the network coverage
• Detect faulty hardware components responsible for bad QoS
• Help logical parameters fine tuning
> The RMS feature provides statistics on Voice Quality. VQ data are now needed since the Call Drop rate is not sufficient to have a clear picture of the QoS in a network using Slow Frequency Hopping as a densification technique.
> The RMS feature is a "plus" providing additional information to help radio engineer in their Fault detection and Network optimization tasks.
6.1 Radio Measurement Statistics objectivesRMS objectives
> Provide Radio Measurement Statistics
• On all the network elements (all TRXs/cells)
• Permanently through the PM type 31
– RMS results available every day (after a specific period)
In order to
• Reduce the cost of Radio Network Optimization
> Today's solutions for Radio Measurements are limited and very expensive:
• drive tests: provide a mobile user with the perception of the network but cannot be done on the whole network and on an very day basis since:
– they are costly (tool+car+manpower).
– they need to be post-processed.
– they are limited to part of the network.
– they are available on the DownLink path only.
• Abis interface traces: provide a complete Uplink and Downlink radio quality assessment of a cell but cannot be done on the whole network and on an every day basis since:
– they are costly (protocol analyzer+manpower).
– they need to be post-processed.
– they are limited to a few cells at once per analyzer.
> RMS results are reported permanently (once a day) by the BSS as a PM Type 31 counters to the OMC-R
> The RMS job is defined and activated on a per BSS basis
> RMS job parameters are managed through RMS templates
• RMS templates provide means to tune RMS parameters according to Cell Planning (cell profile, cell class)
> The cell profile can be: micro, indoor, multiband, etc.
> The cell class can be: rural, urban, rural rapid (covering express railway), etc.
> Templates parameters define the intervals or Received level, Consecutive frame erasure, Radio link counter, Path balance, C/I …for which RMS counters are provided.
• Call Quality Statistics which qualify calls according to coverage/interference criteria – based on samples corresponding to measurement results averaged
over a number of SACCH multi-frames
• Radio Quality Statistics:– UL/DL level, UL/DL qual
– CFE
– AMR (Analyse the coded values)
– Timing Advance
• C/I Statistics on neighboring freq/MAFA freq– last 2 statistics types based on samples corresponding to
measurement results Annex 1
B9
B9
B9
> The first RMS Statistics type is based on calls.
> The two others are based on TRX/Cell.
> additional information• Measurement results, TRX, BS/MS max power
> MAFA = Mobile Assisted Frequency Allocation is a GSM Phase 2+ feature allowing to request a mobile to measure and report through Extended Measurement Report message a C/I value for each frequency specified in an Extended Measurement Order message.
> CFE: Consecutive Frame Erasure
> 1 SACCH multi-frame (SACCH mfr) corresponds to 4 consecutive sequences of 26 TDMA frames during which, in the uplink, a measurement report message is received by the BTS from the MS.
> The fact that FER measurements are more reliable than RXQUAL ones to assess the VQ is even more true when using Slow Frequency Hopping. In this case RXQUAL values are not anymore correlated to Voice Quality as perceived by the end user.
> FER measurements are available for the uplink path only.
> These RMS indicators are provided on the RNO tool per TRX, per Cell:
• Number of Noisy calls suffering from problem of bad coverage on the uplink pathRMVQULVN = RMS_call_noisy_UL_bad_coverage
• Number of Noisy calls suffering from problem of interference on the uplink pathRMVQUIFN = RMS_call_noisy_UL_interference
• Number of Noisy calls suffering from problem of interference and bad coverage considered together on the uplink pathRMVQUUKN = RMS_call_noisy_UL_undefined
• Rate of Noisy calls suffering from problems of interference or/and bad coverage on the uplink pathRMVQUNOR = RMS_call_noisy_UL_rate
> Note: The 4 indicators above can be provided for Noisy calls suffering from VQ problems on the dowlink path.
• Rate of Noisy calls but with good FER measurements on the uplink pathRMVQFEGR = RMS_call_noisy_good_FER_rate
• Rate of Noisy calls and also with bad FER measurements on the uplink pathRMVQFEBR = RMS_call_noisy_bad_FER_rate
• Rate of calls with fair quality measurements but with bad FER measurements on the uplink pathRMVQFEAR = RMS_call_abnormal_bad_FER_rate
– This last indicator can be used in order to tune the RMS VQ parameters used to characterize a call as Noisy.
> VQ_AVERAGE = Number of consecutive SACCH measurements from which the reported Level and Quality notes (UL and DL) are averaged. The resulting averages represent the level and quality of the corresponding Call Quality Sample, i.e. the portion of the call over which level and quality have been measured.
> AV_RXLEV_xx_VQ = Average xx level measured over a Call Quality Sample (VQ_AVERAGE SACCH)
> AV_RXQUAL_xx_VQ = Average xx quality measured over a Call Quality Sample (VQ_AVERAGE SACCH)
Call Quality Statistics:Parameters used to determine if a call is noisy (according to RXQUAL) and of bad voice quality (according to FER)
> VQ_AVERAGE: averaging window size on measurement results to obtain Call Quality Samples (CQSs) (0 SACCH mfr to 128 Smf)
> VQ_RXLEV: radio level threshold to specify a bad coverage CQS for noisy call statistics (-110 to -65 dBm)
> VQ_RXQUAL: radio quality threshold to specify a bad quality (RXQUAL) CQS for noisy call statistics (0 to 7)
> VQ_RXQUAL_VS_RXFER: radio quality threshold to specify a bad or a good quality CQS correlated to bad or good FER measurements for noisy call statistics (0 to 7)
> All these parameters are included in the RMS PM Type 31 result files as RMS counters:
• RMSpc = PAR_VQ_AVERAGE
• RMSpd = PAR_VQ_RXLEV
• RMSpe = PAR_VQ_RXQUAL
• RMSpf = PAR_VQ_RXQUAL_VS_RXFER
> Call Quality Sample (A CQS) will be qualified as “of bad level” if the Average RxLevel is lower than VQ_RXLEV
> A CQS will be qualified as “of bad quality” if the Average RxQuality is greater than VQ_RXQUAL
> For FER counters, VQ_RXQUAL_VS_RXFER is used instead of VQ_RXQUAL to qualify a CQS as “of bad quality” if the Average FER is also checked (compared to VQ_xx_RXFER).
> Note: For CQS, the averaging process is non-sliding.
> Distribution of samples per RxQual value and RxLev band
> Distribution of samples per RxLev band
6.5.1 Generalities Cell coverage problem
> A coverage problem is observed when a significant amount of the traffic of a cell is suffering from both low level and bad quality (RxQual).
> To confirm the distribution of samples per RXLEV band, should also be considered to know the proportion of calls which are experiencing a low signal level.
> If a lot of samples of low level and bad quality are observed for only a sub-part of the TRXs (can be one only) then a BTS hardware problem or a problem on the aerials should be suspected.
> If all the TRXs are experiencing a lot of samples of low level and bad quality then a coverage problem shall be suspected.
> These RMS indicators are provided on the RNO tool per TRX, per Cell:
• Matrix of Number of Measurement Results per DL RxQual value and per DL RxLev bandRMQLDSAM = RMS_DL_RxQuality_RxLevel_sample
• Vector of Percentage of Samples per DL RxLev bandRMQLDLVDV = RMS_DL_RxLevel_distrib
• Vector of Percentage of Samples per DL RxQual bandRMQLDQUDV = RMS_DL_RxQuality_distrib
– RXLEV_UL is the received signal levels measured by the BTS on the uplink path (in dBm).
– MS_TXPWR is the MS transmitted power converted by the BTS from the MS power level into dBm value according to the frequency band of the TRX.
– BS_TXPWR is the BTS transmitted power offset defined relatively to the maximum absolute output power of the BTS (negative value in dB).
– BTS_MAX_OUTPUT_POWER is the maximum power of the BTS after Combiner (in dBm).
– RXLEV_DL is the received signal levels measured by the MS on the downlink path (in dBm).
> NOTE: Additional asymetric DL loss (external combiner) or UL gain (TMA) are not taken into account in the computation, so they must be considered when interpreting the RMS results.
6.5.2 Radio quality parametersRMS parameters (2/4)
Radio Quality Statistics
> TA_STAT: threshold on the timing advance value defining a priori the range of the cell (0 to 64 bits)
> MEAS_STAT_TA1 to MEAS_STAT_ TA9: 9 thresholds for the timing advance to define 10 TA Bands
> MEAS_STAT_S1 to MEAS_STAT_S9: 9 thresholds on the BTS Radio Link Counter S value defining
10 S bands
0 < MEAS_STAT_S(i) ≤ MEAS_STAT_S(i+1) ≤ 128 SACCH mfr– S: counter managed by the BTS on a per call basis
– S = RADIOLINK_TIMEOUT_BS if good radio conditions
– S decremented if bad radio conditions
– The BSS triggers a call drop when S = 0
B9
B9
> All these parameters are included in the RMS PM Type 31 result files as RMS counters:
• RMSpt3 = TAB_PAR_MEAS_STAT_S = Table of 9 parameters MEAS_STAT_Si
• RMSpb = PAR_TA_STAT
• RMSpt6 = TAB_PAR_MEAS_STAT_TA = Table of value for 9 parameters: MEAS_STAT_TA1 to TA9a threshold on Timing Advance measurement to define bands used for RMS
> Recall on the Uplink Radio Link Supervision procedure:
• For each active dedicated radio channel in a cell, a counter “S” called Radio Link Counter is:
– decremented by 1 by the BTS each time an SACCH measurement from the mobile cannot be decoded
(SACCH_BFI=1).
– incremented by 2 by the BTS each time a valid SACCH measurement is received from the mobile
(SACCH_BFI=0).
• Initial value of S = RADIOLINK_TIMEOUT_BS (cell parameter)
– if S reaches N_BSTXPWR_M, a radio link recovery is triggered (BTS and MS power increased at their
maximum).
– if S reaches 0, a Radio Link Failure is triggered (channel drop).
• Therefore the value of S gives a measure of the “quality” of the radio uplink.
The real number of Measurement Results in which DL The real number of Measurement Results in which DL The real number of Measurement Results in which DL The real number of Measurement Results in which DL RxQualRxQualRxQualRxQual is equal to i and DL is equal to i and DL is equal to i and DL is equal to i and DL RxLevRxLevRxLevRxLev is in RXLEV band j, is in RXLEV band j, is in RXLEV band j, is in RXLEV band j, is equal to:is equal to:is equal to:is equal to:S(RXQUAL i, RXLEV band j) x Max j / 254 S(RXQUAL i, RXLEV band j) x Max j / 254 S(RXQUAL i, RXLEV band j) x Max j / 254 S(RXQUAL i, RXLEV band j) x Max j / 254 TPR_RXQUAL_DL_RXLEV_DL(i,j) x TMR_TPR_RXQUAL_DL_RXLEV_DL(i,j) x TMR_TPR_RXQUAL_DL_RXLEV_DL(i,j) x TMR_TPR_RXQUAL_DL_RXLEV_DL(i,j) x TMR_RXQUAL_DL_RXLEV_DL(j) / 254_DL_RXLEV_DL(j) / 254_DL_RXLEV_DL(j) / 254_DL_RXLEV_DL(j) / 254
> TPR_BFI_RXLEV_UL: matrix of 10x10 elements UL(BFI i, RXLEV band j), each element is made up of:
• the norm of number of SACCH multi-frames in which the number of consecutive speech frames with BFIs set to 1 is in BFI band i and UL RxLev reported in the corresponding measurement results is in RXLEV band j
> TMR_BFI_RXLEV_UL: vector of 10 elements ULBFI(RXLEV band j), each element is made up of:
• the maximum value of the 10 real numbers of SACCH multi-frames in which the number of consecutive speech frames with BFIs set to 1 is in BFI band i (i=0 to 9) and UL RxLev reported in the corresponding measurement results is in RXLEV band j
RMS5a=TPR_BFI_RXLEV_UL RMS5b= TPM_BFI_RXLEV_UL
The real number of Measurement Results in which the number of consecutive speech frames with BFIs set to 1 is in BFI band i and UL RxLev is in RXLEV band j, is equal to: S(BFI i, RXLEV band j) x Max j / 254 TPR_BFI_RXLEV_UL(i,j) x TMR_BFI_RXLEV_UL(j) / 254
6.5.3 Radio quality counters RMS counters for AMR Monitoring (1/4)
Radio Quality Statistics
To provide a better tool to dimensioning the AMR thresholds, B9 introduce a new set of RMS counters to verify the use of different speech codecs: For Full Rate and Uplink:
> AMR_FR_UL_BAD= RMS44a that has 8 cells (1 for each FR codec) with the relative number of bad speech frames received in uplink.
> MAX_AMR_FR_UL_BAD= RMS44b that indicates the maximum number of bad speech frames received in uplink in one FR codec.
6.5.3 Radio quality counters RMS counters for AMR Monitoring (3/4)
Radio Quality Statistics
AMR Table; different speech codecs: For Full Rate, UL & DL
> AMR_FR_UL_RXLEV_UL= RMS46a that has a table (8x10) with relative number of correct speech frames received in uplink in each AMR FR codec (8 codecs) and each level band (10 level bands).
> MAX_AMR_FR_UL_RXLEV_UL= RMS46b that has the 10 maximum results. Each cell Ci of the table indicates the greatest value of the Vikfor a i given in RMS46a.
> AMR_FR_DL_RXLEV_DL= RMS47a that has a table (8x10) with relative number of correct speech frames received in downlink in each AMR FR codec (8 codecs) and each level band (10 level bands).
> MAX_AMR_FR_DL_RXLEV_DL= RMS47b that has a table of 10 maximum results. Each cell Ci of the table indicates the greatest value of the Vik for a i given in RMS47a.
6.5.3 Radio quality counters RMS counters for AMR Monitoring (4/4)
Radio Quality Statistics
AMR Table; different speech codecs: For Half Rate, UL & DL
> AMR_HR_UL_RXLEV_UL= RMS48a that has a table (5x10) with relative number of correct speech frames received in uplink in each AMR HR codec (5 codecs) and each level band (10 level bands).
> MAX_AMR_HR_UL_RXLEV_UL= RMS48b that has a table of 10 maximum results. Each cell Ci of the table indicates the greatest value of the Vik for a i given in RMS48a.
> AMR_HR_DL_RXLEV_DL= RMS49a that has a table (5x10) with relative number of correct speech frames received in downlink in each AMR HR codec (5 codecs) and each level band (10 level bands).
> MAX_AMR_HR_DL_RXLEV_DL= RMS49b that has a table of 10 maximum results. Each cell Ci of the table indicates the greatest value of the Vik for a i given in RMS49a.
6.5.3 Radio quality counters RMS counters for Timing Advance (2/3)
> A new set of RMS counters related with timing advance analysis.TRX Based. (Rxlev for UL and DL)
• TPR_TIMING_ADVANCE= RMS50a that has 10 cells(1 for each timing advance band) with relative number of measurements in each Timing advance band.
• MAX_TIMING_ADVANCE = RMS50b that has the greatest number of measurements in one Timing advance band.
• TPR_UL_RXLEV_TA_BAND= RMS51 that has 10 cells (1 for each timing advance band) with average of uplink rxlev in corresponding timing advance band.
• TPR_DL_RXLEV_TA_BAND= RMS52 that has 10 cells (1 for each timing advance band) with average of downlink rxlev in corresponding timing advance band.
B9
> The distribution of number of measurement reports for which the value of timing advance is in TA band X is described below:
> There are 10 TA bands which are defined through 9 thresholds parameters, tunable on a cell basis, using the RMS_parameters_template :
TA band 1 is defined by: 0 <= TA < Meas_STAT_TA_1
TA band 2 is defined by: MEAS_STAT_TA_1 <= TA < MEAS_STAT_TA_2
• …
TA band 10 is defined by: MEAS_STAT_TA_9 <= TA < 63
> The TRE counts for each TA band the number of measurement results, N1 to N10. To save on the memory resources, these counters are sent to the BSC in a coded format.
6.5.3 Radio quality counters RMS counters for Timing Advance (3/3)
> A new set of RMS counters related with timing advance analysis.
Uplink:
• TPR_UL_RXQUAL_TA_BAND= RMS53: Table of 10 results that has 10 cells (1 for each timing advance band) with average of uplink rxqual in corresponding timing advance band.
Downlink:
• TPR_DL_RXQUAL_TA_BAND= RMS54 Table of 10 results that has 10 cells (1 for each timing advance band) with average of uplink rxqual in corresponding timing advance band.
B9
> TPR_UL_RXQUAL_TA_BAND= RMS53
Table of 10 results; Each cell (i) of the table contains :
average value of UpLink Rxqual of reports in TA band i.
Averaged Rxqual is given with a precision of 2 digits after the comma (step size for coding = 0.01, 0 coded 0, 0.01 coded 1, ...).
i = 1...10
TA band i is defined by : MEAS_STAT_TA_ (i-1)<= Timing Advance < MEAS_STAT_TA_i
6.5.3 Radio quality counters RMS counters for Timing Advance (3/3)
> MAX_POWER_PER_TRXMaximum GMSK TRX power level applied at the BTS antenna output connector in dBm.
• The power takes into account the different losses (cables, internal combiners)
• TRX Based
B9
> MAX_POWER_PER_TRX= RMSPw3
Maximum GMSK TRX power level applied at the BTS antenna output connector in dBm.
The power takes into account the different losses (cables, internal combiners) and the internal/ external leveling but it does not take into account the BS-TXPWR-MAX, attenuation required by the OMC_R.
If the feature “unbalancing TRX output power per BTS sector" is activated (parameter “En-Unbalanced-Output-Power” set to 1), the counter is set by the BTS to the power required by the BSC for the corresponding TRE (i.e. for the TRE on which is mapped that TRX).
– The expression (RXLEV_DL + abs(BS_TXPWR - BS_TXPWR_MAX)) can be seen as a kind of normalized received power level in case the BTS would always have used the maximum allowed transmit power level on the TCH channel.
> For C/I statistics per MAFA frequency:
• The C/I ratio is computed by the BTS from each Extended Measurement Report message in the same way as the C/I ratio per neighboring cell.
> TPR_CIN: vector of 10 elements C/In(C/I band j), each element is made up of:
• the norm of number of measurement result samples for which the computed Carrier/Interference ratio is in C/I band j
> MR_CIN:
• maximum value of the 10 real numbers of samples for which the computed Carrier/Interference ratio is in C/I band j (j=1 to 10)
TPR_CIN and MR_CIN counters are provided for up to 42 neighboringcells
RMS8a=TPR_CIN RMS8b=TMR_CIN
For each reported neighboring cell (BCCH/BSIC): the Real number of Measurement Results for which the computed Carrier/Interference ratio is in C/I band j, is equal to: S(C/I band j) x Max / 254 TPR_CIN(j) x TMR_CIN / 254
For each declared/reported neighboring cell, the identification of this cell shall be done as follows:BCCH_ARFCN and BSIC. The BCCH ARFCN is deduced in the BTS from the BCCH frequency index and the list of indexed frequencies (sent by the BSC at the beginning of the RMS job). The RMS results report shall include all reported neighboring cells. Some of them correspond to known cells at the BSS level (i.e. their BSIC matches what is expected at the BSC side) but some of them are unknown (their BSIC does not match). However, the BTS will handle the same for both cases.The list of frequencies to be monitored by the mobile is limited to 33 but due to ‘resurgence’, the same frequency can be reported several times (each time with a different BSIC). If the number of reported cells is above the dimensioning limit (maximum 42 CI-vectors are reported), the extra new reported frequencies are not taken into account anymore. In the result report, the related overflow indicator is set accordingly.
> TPR_CIF: vector of 10 elements C/If(C/I band j), each element is made up of:
• the norm of number of Extended Measurement Results samples for which the computed Carrier/Interference ratio is in C/I band j
> MR_CIF:
• maximum value of the 10 real numbers of samples for which the computed Carrier/Interference ratio is in C/I band j (j=1 to 10)
TPR_CIF and MR_CIF counters are provided for up to 21 frequencies (serving cell BCCH + 20 MAFA frequencies)
RMS9a=TPR_CIF RMS9b=TMR_CIF
For each reported MAFA frequency (ARFCN): For each reported MAFA frequency (ARFCN): For each reported MAFA frequency (ARFCN): For each reported MAFA frequency (ARFCN): the Real number of Extended Measurement Results for which the cothe Real number of Extended Measurement Results for which the cothe Real number of Extended Measurement Results for which the cothe Real number of Extended Measurement Results for which the computed Carrier/Interference ratio is in mputed Carrier/Interference ratio is in mputed Carrier/Interference ratio is in mputed Carrier/Interference ratio is in C/I band j, is equal to: C/I band j, is equal to: C/I band j, is equal to: C/I band j, is equal to: S(C/I band j) x Max / 254 S(C/I band j) x Max / 254 S(C/I band j) x Max / 254 S(C/I band j) x Max / 254 TPR_CIF(j) x TMR_CIF / 254TPR_CIF(j) x TMR_CIF / 254TPR_CIF(j) x TMR_CIF / 254TPR_CIF(j) x TMR_CIF / 254
For each reported MAFA frequency, the identification of this frequency shall be done as follows: Frequency ARFCN .
In case of a frequency reported via an Extended Measurement Reporting, no BSIC is required: the frequency ARFCN is not directly linked to a BCCH frequency. The ARFCN value of the frequency is deduced in the BTS from the place of the measurement in the EXTENDED_ MEASUREMENT_REPORT and from the ordered frequency list in the Extended Measurement Order. This list is built by the OMC-R and passed via BSC to BTS at the beginning of the RMS job.
The maximum number of frequencies in the order (EMO) is the maximum defined in GSM (=21). Hence the maximum in the report is 21 also. When in exceptional cases, more results are available (future expansion in GSM), only the first 21 are reported.
The BCCH frequency of the serving cell shall always be part of the EMO-frequency list.
> Noisy calls indicators can also be computed from FER measurements
• Noisy calls with bad or good FER
• Calls not detected as noisy but with bad FER
Voice Quality indicators are
based on calls
Noisy calls are associated
with a cause of
bad coverage, interference or
with an undefined cause
> The fact that FER measurements are more reliable than RXQUAL ones to assess the VQ is even more true when using Slow Frequency Hopping. In this case, RXQUAL values are not anymore correlated to Voice Quality as perceived by the end user.
> FER measurements are available for the uplink path only.
> These RMS indicators are provided on the RNO tool per TRX, per Cell:
• Number of Noisy calls suffering from problem of bad coverage on the uplink pathRMVQULVN = RMS_call_noisy_UL_bad_coverage
• Number of Noisy calls suffering from problem of interference on the uplink pathRMVQUIFN = RMS_call_noisy_UL_interference
• Number of Noisy calls suffering from problem of interference and bad coverage considered together on the uplink pathRMVQUUKN = RMS_call_noisy_UL_undefined
• Rate of Noisy calls suffering from problems of interference or/and bad coverage on the uplink pathRMVQUNOR = RMS_call_noisy_UL_rate
> Note: The 4 indicators above can be provided for Noisy calls suffering of VQ problems on the dowlink path.
• Rate of Noisy calls but with good FER measurements on the uplink pathRMVQFEGR = RMS_call_noisy_good_FER_rate
• Rate of Noisy calls and also with bad FER measurements on the uplink pathRMVQFEBR = RMS_call_noisy_bad_FER_rate
• Rate of calls with fair quality measurements but with bad FER measurements on the uplink pathRMVQFEAR = RMS_call_abnormal_bad_FER_rate
– This last indicator can be used in order to tune the RMS VQ parameters used to characterize a call as Noisy.
> Distribution of samples per RxQual value and RxLev band
> Distribution of samples per RxLev band
6.7 RMS indicators usage Cell coverage problem
Not acceptable
coverage limit:
Too low level
Too bad quality
> A coverage problem is observed when a significant amount of the traffic of a cell is suffering from both low level and bad quality (RxQual).
> To confirm the distribution of samples per RXLEV band, should be also considered to know the proportion of calls which are experiencing a low signal level.
> If a lot of samples of low level and bad quality are observed for only a sub-part of the TRXs (can be one only) then a BTS hardware problem or a problem on the aerials should be suspected.
> If all the TRXs are experiencing a lot of samples of low level and bad quality then a coverage problem shall be suspected.
> These RMS indicators are provided on the RNO tool per TRX, per Cell:
• Matrix of Number of Measurement Results per DL RxQual value and per DL RxLev bandRMQLDSAM = RMS_DL_RxQuality_RxLevel_sample
• Vector of Percentage of Samples per DL RxLev bandRMQLDLVDV = RMS_DL_RxLevel_distrib
• Vector of Percentage of Samples per DL RxQual bandRMQLDQUDV = RMS_DL_RxQuality_distrib
> Average TA values per RxQual value and RxLev band
Not acceptable
coverage limit:
Too low level
Too bad quality
Acceptable coverage limit:
Sufficient level and good quality
% of TA value over TA
threshold has also to be
considered
> In order to know if the coverage problem is due to a big amount of traffic at the cell border or rather to indoor calls, the average TA value per RXQUAL value and RXLEV band as well as the Percentage of TA values over the TA threshold should be observed.
• Matrix of Average TA per UL RxQual value and per UL RxLev bandRMQLUTAM = RMS_UL_RxQuality_RxLevel_TimingAdvance
• Rate of Measurements Results whose TA is greater than the TA thresholdRMTAGTR = RMS_TimingAdvance_greater_threshold_rate
• Maximum TA value of all values reported in Measurement Results RMTAMXN = RMS_TimingAdvance_max
> post-processing the RMS results provided per TRX
• TOT_SEIZ_TCH: number of TCH channels successfully seized by the MS
• TOT_MEAS: number of Measurement Results used for RMS
• TOT_MEAS_L1INFO_NOL3INFO: number of Measurement Results used for RMS statistics for which Layer 1 info is present but Layer 3 is missing
• TOT_MEAS_DTX_UL: number of Measurement Results used for RMS statistics for which DTX UL was used in the corresponding SACCH mfr
• TOT_MEAS_DTX_DL: number of Measurement Results used for RMS statistics for which DTX DL was used in the corresponding SACCH mfr
• TOT_EMR: number of Extended Measurement Results used for RMS statistics
> Corresponding RMS counter numbers:
• RMS31 = TOT_SEIZ_TCH
• RMS32 = TOT_MEAS
• RMS33 = TOT_MEAS_L1INFO_NOL3INFO
• RMS34 = TOT_MEAS_DTX_UL
• RMS35 = TOT_MEAS_DTX_DL
• RMS38 = TOT_EMR
> Note:
• If during an SACCH measurement, DTX is applied on the uplink path (DTX_UL =1), the counters on consecutive BFIs (RMS5a, RMS5b) shall not be incremented and the corresponding measurement result shall not be taken into account in these RMS counters.
• If during an SACCH measurement, DTX is applied on the uplink path (DTX_UL = 1), the FER measurement does not take place.
• BS_TX_PWRMAX: effective maximum output power of the BTS on any channel of the TRX as an offset from the maximum absolute output power (in dB)
• MS_TX_PWRMAX: effective maximum output power of the MS using any channel of the TRX (in dBm)
• IND_TRE_OVERLOAD: boolean indicating if the TRE handling the TRX function has experienced a data loss due to a processor overload during the RMS campaign
• IND_RMS_RESTARTED: boolean indicating if the RMS job has been restarted on the concerned TRE during the RMS campaign due to a modification of the RMS parameter values or a TRE reset
> interpreting the C/I RMS results provided per TRX
• IND_CI_PARTIAL_OBSERVATION: made up of 2 booleansindicating that:
– C/In computation has been restarted due to the modification of the list of neighboring cells during the RMS campaign
– C/If computation has been restarted due to the modification of the list of MAFA frequencies during the RMS campaign
• IND_CI_OVERFLOW: boolean indicating that the upper limit of 42 C/I sets of counters has been exceeded (each new reported neighboring cell (BCCH, BSIC) has not been taken into account in RMS statistics)
> Interests of call mix: Input data for dimensioning
• Cell and BSC resources dimensioning
– RTCH, SDCCH, TTCH, BTS, BSC and MSC CPU processor
• Some examples of "risky" call mix
– too many LU/Calls: SDCCH congestion, TCU load, MSC overload
– too many HO/calls: speech quality, call drop, DTC load
– too many calls: TCH congestion
– too many paging: DTC processor load, PCH congestion
> A Call Mix will be used at Radio Network Design and Radio Network Planning stages in order to define the capacity of the network (number of sites, TRXs per site, radio configuration, number of Abis-PCM, A-PCM).
> When the network is in operation, a Call Mix is used in order to anticipate network extension or re-dimensioning.
> Given an Offered traffic, compute the number of TRXs (and SDCCH) needed to carry it => What is the accepted blocking rate?
> default blocking rate
• RTCH: 2 %
• SDCCH: 0.5 %
• (for BSC TTCH: 0.1%)
> The Erlang B law is less relevant for SDCCH dimensioning since SDCCH traffic cannot be modelized like TCH traffic. Indeed SDCCH is not only due to subscriber traffic but also to Location Update, SMS, IMSI Detach, etc.
> For SDCCH dimensioning, some typical configurations are used according to the number of TRXs in the cell, the LA plan.
> MS access types distribution (NA only)Accessibility in type 110 since B8
• TCH requests from FR only MSTCNARQMN= MC701A
• TCH requests from DR MSTCNARQBN= MC701B
• TCH requests from DR+EFR MSTCNARQTN= MC701C
• TCH requests from AMR MSTCNA3RQTN= MC701D
• TCH requests from Data callsTCNARQDN= MC701E
> Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS:
• Traffic Load and Traffic Model > TCH traffic > Speech version and Channel type
• These indicators can only be computed if PM Type 1 is activated in B7.
• From B8, the counters needed for these indicators are added to type 110.
• The following indicators are also computed:
– Ratio of TCH normal assignment requests from FR mobiles over all TCH normal assignment requests from all mobile types = TCNARQMTO = MC701A / (MC701A+MC701B+MC701C+MC701D+MC701E)
– Ratio of TCH normal assignment requests from DR mobiles over all TCH normal assignment requests from all mobile types = TCNARQBTO = MC701B / (MC701A+MC701B+MC701C+MC701D+MC701E)
– Ratio of TCH normal assignment requests from DR+EFR mobiles over all TCH normal assignment requests from all mobile types = TCNARQTTO = MC701C / (MC701A+MC701B+MC701C+MC701D+MC701E)
– Ratio of TCH normal assignment requests from AMR mobiles over all TCH normal assignment requests from all mobile types = TCNA3RQTTO = MC701D / (MC701A+MC701B+MC701C+MC701D+MC701E)
– Ratio of TCH normal assignment requests for Data calls over all TCH normal assignment requests from all mobile types = TCNARQDTO = MC701E / (MC701A+MC701B+MC701C+MC701D+MC701E)
– Number of handover intracell attempts with cause 27: "FR to HR channel adaptation due to a good radio quality" on a TCH channel= HCSTAMFN = MC448B
– Number of handover intracell attempts with cause 26: "HR to FR channel adaptation due to a bad radio quality" on a TCH channel= HCSTAMHN = MC448A
7.3 TCH resource allocation indicators Speech coding version
> Speech coding Version capabilities distribution (NA only)Accessibility in type 110 since B8
• TCH allocations with FR SV1TCNACAFN= MC702A
• TCH allocations with HR SV1 TCNACAHN= MC702B
• TCH allocations with FR SV2 (EFR) TCNACAEN= MC702C
• TCH allocations with FR SV3 (AMR FR) TCNA3CAFN= MC704A
• TCH allocations with HR SV3 (AMR HR) TCNA3CAHN= MC704B
• TCH allocations for data call TCNACADN= MC705
> Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS:
• Traffic Load and Traffic Model > TCH traffic > Speech version and Channel type
• These indicators can only be computed if PM Type 1 is activated in B7.
• From B8, the counters needed for these Indicators are added to type 110.
• The following indicators are also computed:
– Ratio of TCH allocations with FR SV1 over all TCH allocations during normal assignment = TCNACAFTO = MC702A / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
– Ratio of TCH allocations with HR SV1 over all TCH allocations during normal assignment = TCNACAHTO = MC702B / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
– Ratio of TCH allocations with EFR over all TCH allocations during normal assignment = TCNACAETO = MC702C / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
– Ratio of TCH allocations with AMR FR over all TCH allocations during normal assignment = TCNA3CAFTO = MC704A / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
– Ratio of TCH allocations with AMR HR over all TCH allocations during normal assignment = TCNA3CAHTO = MC704A / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
– Ratio of TCH allocations for Data calls over all TCH allocations during normal assignment = TCNACADTO = MC705 / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
– Rate of successful TCH allocations with AMR SV over all AMR MS requests= TCNA3SUR = (MC704A+MC704B) / MC701D
• TCH traffic in ErlangTCTRE= (MC380A+MC380B) / 3600
• TCH mean holding time (TCH average duration)TCTRMHT= (MC380A+MC380B) / (MC370A+MC370B)
• FR TCH traffic in Erlang TCTRE= MC380A / 3600
• FR TCH mean holding timeTCTRFMHT= MC380A/ MC370A
• HR TCH traffic in Erlang TCTRE= MC380B / 3600
• HR TCH mean holding timeTCTRHMHT= MC380B/ MC370B
> Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS:
• Traffic Load and Traffic Model > TCH traffic > Resource occupancy
– MC380A = Cumulated FR TCH duration per TRX
– MC380B = Cumulated HR TCH duration per TRX
• The following indicators can also be computed:
– TCTRME = Multiband MS TCH traffic in Erlang = MC381 / 3600
– TCTRSE = Single band MS TCH traffic in Erlang = ([MC380A+MC380B] - MC381) / 3600
– MC381 = Cumulated (FR+HR) TCH duration of Multiband mobiles per TRX
A split of counters (MC380a and MC380b) is added, in B8, to make the distinction between traffic in different frequency bands: here after the corresponding stored indicators (type 110):
– TCTRFTTGT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the GSM frequency band is busy in FR usage = MC380C
– TCTRHTTGT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the GSM frequency band is busy in HR usage = MC380D
– TCTRFTTDT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the DCS/PCS frequency band is busy in FR usage = MC380E
– TCTRHTTDT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the DCS/PCS frequency band is busy in HR usage = MC380F
• A TCH request with pci=1 and priority level=p1 will preempt an on-going call with pvi=1 and priority level=p2, p2 lower than p1 (whatever pci value)
• the on-going call with the lowest priority level value shall be elected first and if several calls have the same lowest p2 value, one of them with pci bit set to 0 is preferred
> On Preemption capable TCH Request occurrence:
1. The TCH is established through Preemption if a lower priority level on-going call is preemptable. In this case, the on-going call is released and the freed TCH is served to the new request.
2. If no preemption is possible:
– If queuing is possible: the TCH request is queued and either a Directed Retry or a Fast Traffic HO can be performed.
– If queuing is not possible: the TCH request is rejected and an ASSIGNMENT or HANDOVER FAILURE "no radio resource available" message is sent to the MSC.
Introduction to QoS and Traffic Load monitoring / B9Evaluation
> Objective: to be able to interpret:
– Global indicators, in order to assess the general quality of the network
– Detailed indicators, in order to detect / identify / locate the main malfunctions
– Handover indicators, in order to quantify the efficiency and the reason for HO
– Directed retry indicators, in order to quantify the efficiency of a directed retry
– Indicators provided by the new RMS feature to ease radio optimization and fault detection
– Traffic indicators, in order to detect/predict overload and compute adequate cell dimensioning as well as to understand how RTCH resources are used in the network
• L3 info: MEASUREMENT REPORT from the MS. This message contains the downlink measurements and neighboring cell measurements.
• Uplink measurements performed by the BTS.
• BTS power level used.
> SUB frames correspond to the use of DTX
• if the mobile is in DTX, the rxlevsub or rxqualsub is used to avoid measuring the ts where there is nothing to transmit in order not to false measurements.
• else rxlevfull is used that is to say all TSs are measured.
> MS TXPOWER CONF: what is the actual power emitted by the MS.
> TOA is the timing advance.
> SACCH BFI: bad frame indicator; 2 values 0 or 1; 0 means that the BTS succeeded in decoding the measurement report from the MS.
> How the neighboring cells are coded:
• BCCH1 index in BA list /BSIC1; BCCH2 index in BA list/BSIC2. Why? Because when the mobile is connecting to a new cell, it does not receive LAC/CI (too long) but the list of BCCH frequencies of the neighboring cells (in Band Allocation: BA list). When it reports the radio measurements, it gives the index of the BCCH frequency in the BA list instead of BCCH ARFCN due to the length in case of 1800 frequency coding. Besides the mobile may report a BCCH index / BSIC which does not correspond to a neighboring cell. Of course the BSC will not trigger any handover except if this BCCH index / BSIC couple correspond to a neighboring cell.
> The Extended Measurement Reporting is a feature allowing the BSS to request an MS to measure and report up to 21 frequencies of the band that are not included in its BA list
> Such phase 2+ mobiles must support the optional MAFA feature (Mobile Assisted Frequency Allocation)
Extended Measurement Reporting mechanisms• The Extended Measurement
Order includes the MAFA frequencies the MS is asked to measure
• EMO sent once to the MS on SACCH after TCH seizure
• Extended Measurement Results include the average signal level measured on each MAFA frequency over one SACCH mf duration
• EMR received once per call on SACCH
Back
> When the BTS receives a CHANNEL ACTIVATION with the Extended Measurement Order (EMO) included, it shall send this information on the SACCH to the corresponding mobile only once.
> When the BTS has to send this information, it shall replace the sending of system information 5, 5bis, 5ter or 6 by this information. At the next SACCH multi-frame, the BTS shall resume the sending of this system information by the replaced one.
> The EMO shall be sent after 2 complete sets of SYS_INFO5 and 6, i.e. after the 2nd SYSINFO 6 after the reception of SABM. This guarantees the MS has received a complete set.
> Then, the BTS normally receives from the MS an EXTENDED MEASUREMENT RESULT with the level of the frequencies to monitor. The BTS shall make the correlation between these levels and the frequencies contained in the latest EMO information, after having decoded them, according to the order of the ARFCN. The ‘EXTENDED_MEASUREMENT_RESULT’ is NOT forwarded to the BSC, instead a ‘MEASUREMENT_RESULT’ with indication ‘no_MS_results’ is sent to the BSC.
> In particular, the BTS shall identify the level of the BCCH frequency of the serving cell (which shall always be part of the frequencies to monitor) and apply it as the RXLEV_DL in the Radio Measurement Statistics. The other frequencies will be considered in the same way as BCCH frequency of neighboring cells: they will be linked to the neighboring level and C/I statistics.
> The following DR counters are provided in Type 110
• for the target cell:
– MC13A: TCH requests for Normal Assignment that are put into the queue,
– MC153: incoming internal DR requests,
– MC15A: TCH allocations for incoming internal DR,
– MC151: incoming internal DR successes per cell,
– MC717A: incoming internal DR successes per TRX.
• for the serving cell:
– MC144E: outgoing internal DR requests,
– MC142E: outgoing internal DR successes,
– MC607: outgoing internal+external DR attempts.
> The following DR counters are provided in Type 29 (this type becomes a standard type in B8)
• for the target cell:
– C153: incoming internal DR requests,
– C154: incoming internal DR attempts,
– C151: incoming internal DR successes.
• for the serving cell:
– C144A: forced outgoing internal DR requests,
– C144C: normal outgoing internal DR requests,
– C145A: forced outgoing internal DR attempts,
– C145C: normal outgoing internal DR attempts,
– C142A: forced outgoing internal DR successes,
– C142C: normal outgoing internal DR successes.
> All the counters here and in the next slides concerning directed retry and relative to type 29 can be activated for all cells of the BSC at once from B8. (Type 29 becomes a standard type in B8): C142a, C142b, C142c, C142d, C143a, C143b, C143c, C143d, C143e, C143f, C143g, C143h, C144a, C144b, C144c, C144d, C145a, C145b, C145c, C145d, C151, C152,C153, C154, C555
<---- CLEAR_COMMAND ------ MC642MC142F Cause : HO_SUCCESSFUL
Release of SDCCH Stop T8
> The following DR counters are provided in Type 110
• for the serving cell:
– MC144F: outgoing external DR requests,
– MC142F: outgoing external DR successes.
> The following DR counters are provided in Type 29
• for the serving cell:
– C144B: forced outgoing external DR requests,
– C144D: normal outgoing external DR requests,
– C145B: forced outgoing external DR attempts,
– C145D: normal outgoing external DR attempts,
– C142B: forced outgoing external DR successes,
– C142D: normal outgoing external DR successes.
> As for internal DR, external DR Counters are available permanently
> No counter is provided for the target cell for an external DR since an incoming DR cannot always be discriminated from an incoming external HO. Therefore incoming external DRs are counted together with incoming external HOs in the related counters.
> Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS
• Specific indicators for densification techniques > Directed Retry > Outgoing DR
– DROMSUR: global efficiency of outgoing external DR = MC142F/MC144F
• Other indicators can be computed
from Type 29 counters:
– efficiency of the outgoing internal DR preparation = (C145B+C145D)/(C144B+C144D)
– efficiency of the outgoing internal DR execution = (C142B+C142D)/(C145B+C145D)
– rate of outgoing internal DR execution failures due to BSS problems = [(C145B+C145D) - (C143C+C143G+C143D+C143H)] / (C145B+C145D)
– rate of outgoing internal DR execution failures due to radio problems with reversion old channel = (C143C+C143G) / (C145B+C145D)
– rate of outgoing internal DR execution failures due to radio problems with drop = (C143D+C143H) / (C145B+C145D)
• Interesting indicator:
– TCQUSUDSR: rate of outgoing internal and external directed retries (forced + normal) successfully performed over all RTCH requests queued during normal assignment.
• Uses #7 with Signaling Connection Control Part (SCCP) with a new Application Base Station Application Part (BSSAP). BSSAP is divided into Direct Transfer Application Part (DTAP) and Base Station Subsystem Management Application Part (BSSMAP)
• Contains the messages, which are exchanged between the BSC and the MSC and which are evaluated from the BSC.
• In fact all the messages, which are exchanged as RR (Radio Resource Management Services between the MSC, BSC and MS). Also control Information concerning the MSC and BSC.
• Example: Paging, HND_CMD, Reset
> DTAP
• Messages which are exchanged between an NSS and an MS transparent. In this case, the BSC transfers the messages without evaluation transparent. Mainly Messages from Mobility Management (MM) and Call control (CC)
LCS function (linked to MC02i) and other counters …
> LCS allows to access the MS location provided by the BSS.
• On MS request to know its own location (MC02 impacted, see the previous slide)
• On network request (especially during Emergency calls)
• On external request (LCS Client)
> Positioning methods provided can be:
• Cell-ID or Cell-ID + TA (Timing Advance)
• Conventional (standalone) GPS
• Assisted GPS (with the help of A-GPS server to compute location)
– MS based (MB): MS is able to perform a pre computation
– MS assisted (MA): MS sends info, Network computes
> Assisted GPS Method:
• Mobile-based: The MS performs OTD signal measurements and computes its own location estimate. In this case the network provides the MS with the additional information such as BTS coordinates and the RTD values. These assistance data can be either broadcast on the CBCH (using SMSCB function) or provided by the BSS in a point to point connection (either spontaneously or on request from the MS).
• Mobile-assisted: The MS performs and reports OTD signal measurements to the network and the network computes the MS location estimate.
• With
– OTD: Observed Time Difference: the time interval that is observed by an MS between the receptions of signals (bursts) from two different BTSs.
– RTD: Real Time Difference: This means the relative synchronization difference in the network between two BTSs.
> Finally, 4 methods are possible for positioning:
• Cell ID+ TA
• Conventional (MS equipped with GPS System)
• A-GPS MS Based
• A-GPS MS Assisted
> These 4 Methods induce a set of counters (2 per method) to give the average latitude and longitude of mobiles in the cell.
> These counters are located in the MFS and can be used in RNO (cartographic part).
• MC923a NB_LCS_REQ Number of location requests received from the MSC in CS domain.
• MC923b NB_LCS_SUCC Number of successful location requests performed in a BSS.
• MC923c NB_LCS_FAIL_LB Number of location requests rejected by the SMLC.
• MC923d NB_LCS_ABORT Number of location aborts received from the MSC in CS domain.
> Calculated indicators based on BSC counters:
• Number of failures on LCS requests due to BSS problem,
• Rate of LCS requests aborted,
• Rate of successes on LCS requests,
• Rate of failures on LCS requests,
• Rate of SDCCH seizures for Location Services.
> Other counters in SMLC (MFS) provide details by type of positioning (CI+TA, Conventional GPS, MS-Assisted A-GPS,MS-Based A-GPS) and for different Error causes.