06_RN31586EN20GLA0_RAB

RANKPI RU10Signaling Flow and Trigger Points of M1001 counters for voice
Voice/Video KPIs
PS Radio Access Bearer
Signaling Flow and Trigger Points of M1001 counters for PS
PS RAB KPIs
Radio Link Failure and RRCC re-establishment
* © Nokia Siemens Networks RN31586EN20GLA0
Radio Access Bearer setup
RAB and RRC connection
UE indicates in Initial Direct Transfer service type
Security functions triggered from CN follow
CN sends RABAssignmentRequest to RNC to set-up resources
RNC checks and allocates available resources
In parallel there is ISDN signalling for call setup
RRC Connection setup
UE
BS
RNC
CN
AAL2 sig. ERQ
RAB_ACT_COMPLETE
Exception: release of the RAB during the ACTIVE phase
Exception: release of the RAB during the SET UP or ACCESSE phase
Iu rel. req.
Iu rel. conf.
RL rec. commit
RAB phases are:
SET UP resource allocation in the Uu, WTBS and transport layer.
ACCESS resource allocation in the Ue
ACTIVE RAB is active i.e. utilized by the service.
RAB_STP_ATTEMPTS request xxx = services ( CS Voice – CS data – PS data INTERACTIVE , BACKGROUND, STREAMING )
RAB SETUP FAILURES DUE TO AC FOR xxx
RAB SETUP FAILURES DUE TO BTS FOR xxx
RAB SETUP FAILURES DUE TO TRANSPORT FOR xxx
RAB SETUP FAILURES DUE TO RNC FOR xxx
RAB SETUP FAILURES DUE TO IUB AAL2 TRANS FOR xxx
RAB_STP_COMPLETE confirmation
RAB SETUP ACC FAIL FOR xxx DUE TO RNC INTERNAL
RAB_ACC_COMPLETE confirmation
Steps: RAB_STP_ATTEMPTS ,RAB_STP_COMPLETE, RAB_ACC_COMPLETE and finally when the RAB is released for normal event RAB_ACT_COMPLETE.
Once received the RAB assignment request , the RNC starts in this sequence to check the AC in the target WBTS/Cell, it change the configuration of the radio link, perform the digit analysis in order to find the appropriate route and book the cid to use in the transport layer. Finally it start sending the RB parameter to the Ue. Only once the UE has accepted the RB, the RAB ASS: RESP. is sent to the CN. The RAB resources can be now utilized for the traffic.
RAB could drop also during the active phase, for instance because the HO is not possible or something else.
UE
BS
RNC
CN
AAL2 sig. ERQ
AAL2 sig. ECF
RAB Rel Req.
Exception: release of the RAB during the ACTIVE phase
Exception: release of the RAB during the SET UP or ACCESSE phase
Iu rel. req.
Iu rel. conf.
Transport, RNC, Frozen BTS
M1001C619 due to License
M1001C625 due AAL2 IuCS
RAB phases are:
SET UP resource allocation in the Uu, RNC, WTBS and transport layer.
ACCESS resource allocation in the Ue
ACTIVE RAB is active i.e. utilized by the service.
RAB_STP_ATTEMPTS request xxx = services ( CS Voice – CS data – PS data INTERACTIVE , BACKGROUND, STREAMING )
RAB SETUP FAILURES DUE TO AC FOR xxx
RAB SETUP FAILURES DUE TO BTS FOR xxx
RAB SETUP FAILURES DUE TO Frozen BTS FOR xxx (AC blocks RAB Setup to assure high prio call setup
RAB SETUP FAILURES DUE TO TRANSPORT FOR xxx
RAB SETUP FAILURES DUE TO RNC FOR xxx
RAB SETUP FAILURES DUE TO IUB AAL2 TRANS FOR xxx
RAB SETUP FAILURES DUE TO LICENSE FOR xxx
RAB_STP_COMPLETE confirmation
RAB SETUP ACC FAIL FOR xxx DUE TO RNC INTERNAL
RAB_ACC_COMPLETE confirmation
Steps: RAB_STP_ATTEMPTS ,RAB_STP_COMPLETE, RAB_ACC_COMPLETE and finally when the RAB is released for normal event RAB_ACT_COMPLETE.
Once received the RAB assignment request , the RNC starts in this sequence to check the AC in the target WBTS/Cell, it change the configuration of the radio link, perform the digit analysis in order to find the appropriate route and book the cid to use in the transport layer. Finally it start sending the RB parameter to the Ue. Only once the UE has accepted the RB, the RAB ASS: RESP. is sent to the CN. The RAB resources can be now utilized for the traffic.
RAB could drop also during the active phase, for instance because the HO is not possible or something else.
RAB active phase
RU20 also contains counters to follow up events in RAB active phase, broken down to CS voice, CS data and PS calls
M1001C136-138 for normal completion
M1001C145 ff triggered by:
RAB releases
RAB failures
Relocation
Pre-Emption
RLC unrecoverable error
Loss of FP-level synchronisation on one or all RBs of the UE
RAB_ACTIVE_FAIL_UE
Updated in case of:
UE is not responding to an RRC message within a given time
UE is responding with such failure message (e.g. configuration unsupported) that the connection must be released
Poor CSSR could be a result of
Poor coverage or dominance or interference issues in Radio interface
Capacity issues in Radio or Iub interface
Configuration issues in WBTS (parameters or HW)
CSSR covers all the steps from the initial RRC connection request from the UE to the network, through the RRC setup phase and the RAB setup phase, and until user data is starting to get transferred.
The CSSR formulas are for different traffic classes like:
CS voice calls (RNC 565 f)
CS video calls (RNC 566e)
PS RT Streaming Calls (RNC 575 d)
PS NRT Calls (Interactive & Background) (RNC 576d)
CSSR any service = RRC connection setup & access X RAB setup & access any service
RRC part
RAB part
Success rate KPI
CSSR Voice call (RNC_565f – counter names): CSSR Voice call (RNC_565f – counter numbers):
100 *
RRC part
RAB part
Success rate KPI
CSSR Video call (RNC_566e – counter names): CSSR Video call (RNC_566e – counter numbers):
100 *
Call Setup Success Rate UDI CALL (CS 64k video call)
RRC part
RAB part
AMR Drop
Overall figures (less than 0.1% increase) aligned as before RU20 but with different scenario
Call Completion Success Rate - CCSR
CCSR for a specific service is calculated based on RAB Counters:
In NSN Nokia RAN there are negative counters used to get success ratio:
CCSR = 100 % - 100 % *
sum ( RAB failure counters)
RRC: RRC Connection Request Setup
RRC Connection Access phase
RRC: RRC Connection Completed
RANAP: Initial UE Message
RAB Connection Setup phase
RAB Connection Access phase
Call Set-up Success Rate
UE
DIRECT TRANSFER (Call Proceeding)
RANAP: RAB Assignment Request
RRC: Radio Bearer Set-up
RANAP: RAB Assignment Response
RNC196
All KPIs: incoming hard handovers and relocations are not included anymore in RAB Attempts of RU20; Expected influence: slight decrease in RAB Attempts
RNC_231d: New RAB Active failure cause due to transport (RAB Drop) included; in RU10 this failure cause was included in failure due to RNC -> KPI comparable
RAB Setup and Access Ratio better as in RU10 (99,8 -> 99,9)
RU10
WN6.0
Success rate KPI
CCSR Voice call (RNC_231d – counter names): CCSR Voice call (RNC_231c – counter numbers):
100 - 100*
sum( RAB_ACT_REL_CS_VOICE_P_EMP
CCSR Voice call (RNC_selfmade – counter names): CCSR Voice call (RNC_selfmade – counter numbers):
100-100 * SUM (RAB_ACT_REL_CS_CONV_P_EMP
Call Completion Success Rate UDI CALL (CS 64k Video Call)
This KPI is based on RNC_160d – other services than UDI were excluded
UE
BS
RNC
CN
Separated by SRNC and DRNC
Seperated by ADD, MOD, DEL
Including 5 failure reasons
RL Deletions and reconfiguration cancellations by RNC are also counted
Straightforward to define PIs for each phase
(Add/Mod/Del)
Counters incremented when RNC sends RADIO LINK RECONFIGURATION PREPARE message:
M1005C132 REC_PREP_SRNC
1 for each DCH addition requested in the message
1 for each DCH modification requested in the message
1 for each DCH deletion requested in the message
One message could ask for multiple DCHs
Counters incremented when RNC sends RADIO LINK RECONFIGURATION READY message:
M1005C135 REC_PREP_SRNC_READY
M1005C84 RECONF_DCH_ADD_SRNC_RDY
M1005C85 RECONF_DCH_MOD_SRNC_RDY
1 for each DCH addition in the message
1 for each DCH modification in the message
1 for each DCH deletion in the message
M1005C86 RECONF_DCH_DEL_SRNC_RDY
M1005C126 REC_COMM_SYNCH_SRNC
Commit messages are not counted separately for ADD/MOD/DEL
In SRNC
M1005C212 RECONF_ADD_FAIL_SRNC_RNL
M1005C213 RECONF_ADD_FAIL_SRNC_TRL
M1005C214 RECONF_ADD_FAIL_SRNC_PROT
M1005C215 RECONF_ADD_FAIL_SRNC_MISC
M1005C94 RECONF_ADD_FAIL_SRNC_BTS_NR and M1005C112 RECONF_ADD_FAIL_DRNC_BTS_NR
are incremented in case BTS does not respond in time and response supervision timer expires in RNC
Same for PS!
After READY message from BTS(s), RNC's RM may cancel the reconfiguration request (e.g. due to AAL2 setup failure or if all BTSs are not ready for the new configuration) by commanding the RNC's L3 Dedicated NBAP signaling entity to send an NBAP:RADIO LINK RECONFIGURATION CANCEL message to the BTS's L3 Dedicated NBAP signaling entity (instead of COMMIT message):
M1005C128 CANC_SRNC_TRAN_STP_FAIL
AAL2 setup failure
M1005C129 CANC_SRNC_BTS_NOT_READY
UE
BS
RNC
CN
RB Setup Failures due to unsupported configuration are counted separately
M1006C28 RB_SETUP
M1006C135 REC_PREP_SRNC_READY
M1006C76 RB_SETUP_FAIL
M1006C77 RB_SETUP_FAIL_UNS_CONF
Same for PS!
The RB_SETUP_COMPLETE counter is incremented by the RNC whenever it receives an RRC: RADIO BEARER SETUP COMPLETE message.
The RB_SETUP counter is incremented by the RNC whenever it sends an RRC: RADIO BEARER SETUP message.
Network generated KPI and PI are not able to indicate the percentage of RRC: RADIO BEARER SETUP messages received by the UE : Drive test generated PI are required to achieve this.
Soft handover is not allowed during the RAB establishment procedure and in this case does not occur during the radio bearer setup procedure: this makes the UE and Node B particularly sensitive to mobility and dominance.
Timer wf_rb_setup_cpl (6s) is started when the RRC: RADIO BEARER SETUP message is sent to the UE.
The timer is stopped when RRC: RADIO BEARER SETUP COMPLETE message is received.
In case the timer expires, the IU RELEASE REQUEST is sent to the CN and counters:
RRC Active Release due UE is incremented.
RAB Access Fail due UE is incremented.
M1002/M1001: DCH related counters and KPIs, voice call example
Same structure can be build from M1002 counters for any type of DCH service (SRB, Video call, PS …) and Compressed Mode events
Note that PS allocations are done via RB reconfiguration after
allocation of DCH0/0
M1001 counters are always update to the latest best cell
M1002 request counters are updated to all cells in soft HO, i.e. to all cells belonging to different WBTS assuming that soft HO was already established before the DCH request
In softer HO only one cell is updated
If the DCH request is caused by SHO establishment or HHO the counter will only be updated in the new cell
M1002 reject counters are updated to the rejecting cell
M1002 duration counters are updated to all cells in AS that are affected by the release
Request and Successful AC for a CS Voice DCH
Admission Control decision
NOTE:
Failure can happen later in the setup phase (e.g. radio link reconfiguration, or AAL2 connection setup)
RNC
BTS
ALCAP:ERQ
ALCAP:ECF
UE
RNC
BTS
ALCAP:ERQ
ALCAP:ECF
UE
Admission Control decision to setup new radio link
Request and Successful AC for a CS Voice DCH for SHO trigger
NOTE:
Failure can happen later in the setup phase (e.g. radio link setup, or AAL2 connection setup)
M1002C12REQ_CS_VOICE_IN_SRNC
M1002C13 REQ_CS_VOICE_REJ_UL_SRNC
M1002C14 REQ_CS_VOICE_REJ_DL_SRNC
M1002C16 REQ_CS_VOICE_SRNC
M1002C341REQ_CS_VOICE_HHO_SRNC
M1002C17 REQ_CS_VOICE_REJ_SRNC
M1002Cxx ALLO_FOR_AMR_xx_yy_DL_IN_SRNC
UL DCH Reject Rate
CS Voice KPI
This set of KPI is useful to understand if blocking at RAB level for CS Voice is due to UL AC or DL AC.
In case of cell availability problem, these counters are not incremented at all because AC does not even receive the DCH request.
M1002C13/M1002C12
M1002C14/M1002C12
DCH Duration CS Voice KPI
Counter unit 10ms.
The duration KPI gives an indication of the number of Erlang for voice in the cell during the monitored hours.
M1002C41/100
RAB Holding Time
For each traffic class there are counters for RAB Holding time.
They are incremented (denominator also):
when the RAB is released
in the cell that was the reference when the RAB is released
and in the hour in which it was released
RAB duration for CS voice class (measuring the time from RAB Assignment Response to RAB Assignment Response for release (or Iu Release command)) is defined as:
Due to mobility these KPIs are only accurate on network level.
For investigation on cell level use M1001C489-C502 relating to reference cell
M1001C199/M1001C200
Initial reference cell is the cell where the call was set up.
If the reference cell leaves the AS, the reference cell is chosen from the remaining cells in AS based on CPICH EcNo
RAB Setup Time KPI (average)
The result represents the average time to successfully establish a CS voice RAB. A successful RAB is defined as one for which the RNC sends a positive RANAP: RAB ASSIGNMENT RESPONSE message.
The AVG_RAB_SETUP_TM_CS_VOICE counter records the time between the RNC receiving a RANAP: RAB ASSIGNMENT REQUEST and sending a positive RANAP: RAB ASSIGNMENT RESPONSE. The counter sums the times for all successful RAB assignments.
The DENOM_ RAB_SETUP_TM_CS_VOICE is incremented by 1 after every successful RAB assignment.
The factor of 100 appearing within the KPI calculation is a result of NSN internal representation of the counter value. NSN uses a 10 ms unit for the AVG_RAB_SETUP_TM counter.
Same counters and formula is possible for any RAB (CS_VOICE, CS_CONV, PS_INTER, PS_BACKG)
The KPI is meaningful for cell level and on hour basis
Triggering Point X
From RAS06 onwards, maximum setup time for RAB can be measured. It is absolute maximum setup time per measurement period:
M1001C603 RRC SETUP TIME MAX
M1001C604 RAB SETUP TIME MAX CS VOICE
M1001C605 RAB SETUP TIME MAX CD DATA
M1001C608 RAB SETUP TIME MAX PS INTERACTIVE
M1001C609 RAB SETUP TIME MAX PS BACKGROUND
RAB Setup Time KPI (maximum)
Erlang for CS services
The KPI should be generated on a daily and cluster basis (due to the triggering rules of the RAB holding time).
Same KPI for each CS traffic class:
CS_CONV
CS_STREA
M1001C199
Average Time between drop
The KPI represents the average time between abnormal RAB releases during CS voice RAB active phase:
The KPI should be generated on a daily and cluster basis (due to the triggering rules of the RAB holding time).
Same KPI for each traffic class:
CS_CONV
CS_STREA
PS_INTER
Traffic Mix KPIs
The KPI provides an indication of the percentage of CS voice, CD data, PS data RAB establishment attempts relative to the total number of RAB establishment attempts.
The KPI is meaningful for cluster/cell level and on day/hour basis
These KPI are intended to provide a high level indication of the traffic profile loading the network:
CS_VOICE, CS_CONV, CS_STREA
xyz means all traffic classes
UE indicates in Initial Direct Transfer service type
Security functions triggered from CN follow
CN sends RABAssignmentRequest to RNC to set-up resources
RNC allocates DCH0/0 without resource checks and responds with RABAssignmentResponse => easy to have high CSSR
In parallel there is GPRS Mobility Management signalling for packet call setup
After receiving UL or DL CR, RNC checks and allocates available resources
PS terminology
A packet call is a data transfer session that uses DCH, HS-DSCH, or E-DCH channels, starting from a successful capacity allocation (AC, BTS, transmission, RNC-internal) and ending to a dedicated resource release (for example, transfer to FACH/PCH, DCH 0/0, RAB release, outgoing relocation, HHO, ISHO)
Packet calls start from DCH0/0
One RAB can contain multiple packet calls
Packet call sessions are active data transfer periods
Packet call session start from the respective Capacity Request, i.e. establishment of RLC protocol entity
Uu interface IuB interface Iu interface timing
RRC Connection setup
Uu interface IuB interface Iu interface timing
RAB ACCESS PHASE
UE
BS
RNC
no AC
tc = STREAM, INTERA, BACKG
RAB Assignment requests are also counted in M1003 L3 signaling on Iu
Note that RB Reconfiguration signaling is left out of the diagram for simplicity
Act. PDP context request
RAB ass. req. (setup)
AAL2 sig. ERQ
Radio Bearer Setup
M1001C105/110 due to Adm. Ctrl
M1001C107/112 due to RNC
M1001C108/113 due to ANCH
M1001C257 due to not supp Param
M1001C258 due to UE capabilities
M1001C132/134 due to UE
M1001C185/191 due to Iu
M1001C186/192 due to Radio
M1001C187/193 due to BTS
M1001C188/194 due to IuR
M1001C397/298 due to UE
failures in setup phase
failures in access phase
failures in active phase
UE
BS
RNC
SGSN
During the RAB set up & access phase the HO is inhibited ( PS & CS as well ). HO can happen during the active phase, so for that reason measurements handover related have to be taken in consideration.
For PS connection, in order to achieve the MINIMUM ALLOWED bit rate and the MAXIMUM allowed bit rate according to the profile in the HLR or according to the limitation set in the CELL, is necessary to upgrade the DCH from DCH 0/0 to DCH X/Y, or from DCH X/Y to another.
There are TRAFFIC MEASUREMENT in the RNC that can be used for checking the rejected upgrade for each traffic class.
If AC ( AIR interface or Codes ) fails, traffic measurements per traffic class, are triggered in the RNC. The rejection could happen for an DL or UL capacity request.
Name of the counters:
NRT DCH REQ FOR PS CALL xxxxx CLASS REJECT IN xL IN SRNC
The rejection that trigger the counters in question is only AC.
RAB SETUP FAILURES DUE TO Frozen BTS FOR xxx (AC blocks RAB Setup to assure emergency call)
RNC196
All KPIs: incoming hard handovers and relocations are not included anymore in RAB Attempts of RU20; Expected influence: slight decrease in RAB Attempts
RNC_615c, RNC_736b: New RAB Active failure cause due to transport (Drop) included; in RU10 this failure cause was included in failure due to RNC -> KPI comparable
CSSR PS NRT degraded in RU20 (99,9% -> 99,6%)
RAB Success Ratio NRT improved with CD0.0; now close to RU10 level (99,9% -> 99,85%)
RU10
WN6.0
Includes both Interactive and Background PS calls
Counts from RRC request until RAB is established (with 0/0 RB)
Same as CSSR for AMR, except:
Emergency calls not included
Service level evaluations (PS/NRT)
RNC_576e Packet Call Setup Success Ratio [%] over the reporting period.
Includes both Interactive and Background PS calls
Counts from RRC request until RAB is established (with 0/0 RB)
Same as CSSR for AMR, except:
Emergency calls not included
Counters for NRT RAB instead of Voice RAB
In RU10 it was decided that also RRC Connection Establishment requests with 'high priority signaling' are interpreted as Packet Service requests.
RRC part
RAB part
RAB Setups Success Rate
M1001C120/M1001C71
M1001C121/M1001C72
M1001C78/M1001C71
M1001C79/M1001C72
KPI construction - Call Drop Rate
RNC_736b - RAB Success Ratio for NRT Services [%] from user perspective over the reporting period.
Covers RAB Active Phase of a call. Includes both Interactive and Background PS…

Documents

06_RN31586EN20GLA0_RAB