RCA for KPI in GSM Network

KPI (Key Performance Indicator)

TCH Drop: disconnect a unwanted call is known as TCH drop   [TCH Drop = (TNDROP)/TCASSAL*100]

SDCCH Drop Rate = [(CNDROP-CNRELCONG)/ (CMSESTAB)]*100 %

SDCCH Blocking = (CCONGS)\(CCALLS)*100

TASR = (TCASSAL) / (TASSALL) *100

HOSR = (SUMOHSUCC+SUMEOHSUCC)/ (SUMOHOATT+SUMEOHATT)*100

Random Access Success Rate = (CNROCNT)/ (CNROCNT+RAACCFA) * 100

RAACCFA: Failed Random Access

CNROCNT: All accepted Random Access

TCH DROP	HO FAIL	DLQ
Low Signal strength DL & UL	Less,  Many or  Mismatch NBR	BCCH & TCH Frequency Interference
Bad Quality DL & UL	TCH Cong at target cell	Interference or error  on E1
High TA	Low SS or Bad Qual on cell border	Mismatch MAIO & HSN
Bad Parameter regulation	Mismatch HO algorithm	Hardware Issue, faulty or Alarm
High ICM, VSWR or path imbalance	Mismatch HO parameter setting	Antenna Faulty/ feeder
E1 error & Transmission fault	Sector swap	Time-slot Issue
Bad Parameter setting	CO-BCCH / BSIC	Poor Coverage and Spill
Drop call due to Handover	HO Delay	High Utilization (>150%)
Less,  Many or  Mismatch NBR or HO Delay	uncorrected NBR planning	Ater Issue or Ater Circuit Faulty
Suddenly drop	Interference or error  on E1
wrong combing	Hardware fault ( Alarm & Swap)
Bad Antenna installation
Hardware fault ( Alarm & Swap)
Low SACCH multiframe value	TASR	SD & TCH Congetion
Low RLT value	Poor coverage, Weak UL	High utilization
Low ACCMIN Value	High utilization ( FR utilization)>150%	less Half rate
Low RACCH_access_min	Hardware alarm or Trx Faulty	HCS feature
length of timer T3103 is low	abis or A interface congestion or error
length of timer T3109 is low
length of timer T3111 is low
Length of timer T305/T308 is set to great value.
SD DROP	PSR	RACH
Low SS, Bad Qual, and High TA	Parameter of PSR is MFRMS and timer is T3113	Poor BSIC Plan
LAC Boundary	incorrect cell parameter	Poor BCCH Plan
SW congestion	excess paging discard	Poor Coverage and Spill
Due to TCH Congestion	incorrect MSC parameter	Phantom RACCH
Hardware or TS faulty	poor paging streagady	Faulty antenna and cable
Interference or error  on E1	SD congestion	Poor ACCMIN and CRO
drop call due to TCH congestion	combined BCCH	Mismatch MAXRET & TX
	uncorrected LAC dimension
	abis or A interface congestion or error
	decreasing signaling load on CCCH

Ericsson GSM Parameter

MODE	PARAMETER
IDLE MODE	ACCMIN  CCHPWR  CRH  NCCPERM  CBA Or CB   CBQ   CRO  TO  PT  T3212   ATT   MaxRet   ACC   BA List SIMSG
PAGING	AGBLK  MFRMS   MaxRET
RACH PARA	MaxRET  TX
LOCATION UPDATE	ATT  BCCH TYPE T312 CRH
Dynamic Full/ Half Rate Mode	DMQB   DMQBAMR  DMQBNAMR  DMQG DMQGAMR DMQGNAMR DMTHAMR  DMTHNAMR DHA DTHAMR DTHNAMR
HCSBAND LAYER	LAYER   LAYERTHR   LAYERHYST   PSSTEMP   PTIMTEMP   FASTMSREG   CSYSTYPE   MBCR
CELL COMMON DATA	BSPWRB  BSPWRT CGI BSIC BCCH NO. BCCH TPYE  AGBLK FNOFFSET ECSC  MSTXPWR  TSC
LOCATING URGENCY CELL DATA	TALIM  PSSBQ  PSSTA  PTIMBQ  PTIMTA  PSSHF  PTIMHF

Ericsson KPI Formula

KPI	Target	FORMULAE - ERICSSON
Random Access Success Rate %	>=98	100 * CNROCNT / (CNROCNT + RAACCFA)
SDCCH Blocking %	<=0.5	100 * CCONGS / CCALLS
SDCCH Drop %	<=1.2	100 * (CNDROP - CNRELCONG) / CMESTAB
TCH Blocking %	<=1	100 * (CNRELCONG + TFNRELCONG + THNRELCONG) / TASSALL
TCH Time Congestion/Cell	<=50 sec	Cells with Full Rate only: 100 * TFTCONGS / (PERLEN*60) Cells with Half Rate: 100 * THTCONGS / (PERLEN*60)
TCH Assignment Success Rate %	>=97	100 * TCASSALL / TASSALL
TCH Drop %	<=2	100 * TNDROP / TCASSALL
Handover Success Rate %	>=95	100 * HOVERSUC / HOVERCNT
Avg SDCCH Congestion/cell	<=50 sec	100 * CTCONGS / (PERLEN*60)
Avg TCH Congestion/cell	<=200 sec	Cells with Full Rate only: 100 * TFTCONGS / (PERLEN*60) Cells with Half Rate: 100 * THTCONGS / (PERLEN*60)
Network Availability (Radio)%	>=99.90	100 * (No of days * 24 * 60 * Total No of Cells – Summation of Downtime in minutes of Cells) / (No of days * 24 * 60 * Total No of Cells)
SDCCH Congestion <=30 sec	>90	100 * CTCONGS / (PERLEN*60)
% of cells having SQI samples between 16-30 >90%	>90	90% of cells having percentage of Good samples>90%
Peak Processor Load (MSCs/BSCs) %	<=80	ACCLOAD/NSCAN (These counters are available in object type LOAS)
Switch BHCA Utilization (during Switch NBH)	<=80	100*( BHCA/SwitchBHCA Capacity)
Paging Success Rate (24 hrs) %	>=90	100 * (NLAPAG1RESUCC + NLAPAG2RESUCC) / NLAPAG1TOT
Location Update Success Rate (24 hrs) %	>=95	100 * NLALOCSUCC / NLALOCTOT
Successful Call Rate (24 Hrs) %	>=95	(NBANS + NABEFA1 + NABEFA2 + NCAWNOA + NTOBEFA + NBOUT + NBBUSY) / NCALLS
Network Availability (Switch/IN)%	>99.99	100 * (No of days * 24 * 60 * Total No of Nodes – Summation of Downtime in minutes of Nodes) / (No of days * 24 * 60 * Total No of Nodes)
Core Network Availability %	>99.99	100 * (No of days * 24 * 60 * Total No of Nodes – Summation of Downtime in minutes of Nodes) / (No of days * 24 * 60 * Total No of Nodes)
Attach Success Rate excluding Unregistered Subs. %	>=99	100 * [1 - ((gprsMmSgsnUnsuccAttReq - gprsMmSgsnUnsuccAttReqCC7/8/14) / gprsMmSgsnAttReq)]
PDP context activation success rate (Only NW Cause codes) %	>=99	100 * gprsSmSgsnSuccActivations / (gprsSmSgsnSuccActivations + gprsSmSgsnUnsuccActivations)
Round trip time	<=700 ms	Ping either a DNS server or an external Internet server by the MS PING SIZE - 32BYTE
Average UL throughput per TBF	>=20 kbps	ULBGEGTHR / ULBGEGDATA
Average DL throughput per TBF	>=45 kbps	DLBGEGTHR / DLBGEGDATA

Timer Parameter

TIMER PARAMETER

T3103   -           Handover command

T100     -           RLT is the timer for holding of call if SACCH multiframe is not decoded than RLT

                         timer is start and if  RLT is reach is zero than call will disconnected.

                         Default value of this  timer is 28.

T3105     -          Time between repetitions of physical information to MS. Will be repeated NY1 times.

                         Recommend Value 8   (1 = 10MiliSecond)

T3124   -           Handover access

T3212     -         Location Update parameter

T3107     -         Assignment command

T3113     -         This timer is start after PAGING REQUEST and stop before paging response.

T3260    -          The timer is started when AUTHENTICATION REQUEST is sent from MSC.

                        The timer is stopped when AUTHENTICATION RESPONSE is received in MSC.

T3101     -         The BSS allocates a SDCCH, if available, and sends a IMMEDIATE ASSIGNMENT message on the downlink. This message contains the details of allocated SDCCH, TSC, and TA etc.   As soon as the BSS allocates and sends message on the AGCH, it starts a timer T3101.  This timer is set in millisecs.

T3110     -       On the receipt of the channel release, the MS starts internal timer T3110 and disconnects the main signalling link.

T3111      -       When T3111 has expired all RF links are terminated.

AMR (Adaptive Multi Rate)

Adaptive Multi Rate (AMR) is a new speech and channel codec for both half rate and full rate channels. By adapting the codec rate to the radio conditions the speech quality is enhanced. At low C/I, a large amount of channel coding is applied and less speech coding. When the C/I increase the speech coding is increased and the channel coding is decreased.

Both the BTS (uplink) and the MS (downlink) continuously measures the radio quality (C/I) and based on these measurements the codec rate is changed. AMR requires support in all network nodes, i.e. MSC, BSC, BTS and MS and AMR is only supported in cells where all TRUs are AMR capable.

AMR makes it possible to change codec rate during a call. There are 8 different codec rates available in the AMR transcoder: 12.2kbps, 10.2kbps, 7.95kbps, 7.40kbps, 6.70kbps, 5.90kbps, 5.15kbps, and 4.75kbps

According to the standard, 12.2 kbps and 10.2 kbps can only be used in FR channels and the other six can be used in both FR and HR channels, on the air interface.

Frequency Hopping

Frequency Hopping:

                                Frequency Hopping is mechanism in which the system changes the frequency (uplink and downlink) during transmission at regular intervals.  It allows the RF channel used for signaling channel (SDCCH) timeslot or traffic channel (TCH) timeslots, to change frequency every TDMA frame (4.615 ms).  The frequency is changed on a per burst basis, which means that all the bits in a burst are transmitted in the same frequency.  In 1Sec= 217Hopes

Advantages of Frequency Hopping:    Frequency Diversity, Interference Averaging, Increase capacity

There are two types of hopping 1 Base Band FH (BBH) 2 Synthesizer FH (SFH). 

1. Base Band Frequency Hopping: In baseband hopping, each transmitter is assigned with a fixed frequency. At transmission, all bursts, irrespective of which connection, are routed to the appropriate transmitter of the proper frequency. The advantage with this mode is that narrow-band tunable filter combiners can be used.

2. Synthesizer Frequency Hopping (SFH).  Synthesizer hopping means that one transmitter handles all bursts that belong to a specific connection. The bursts are sent "straight on forward" and not routed by the bus. In contrast to baseband hopping, the transmitter tunes to the correct frequency at the transmission of each burst the advantage of this mode is that the number of frequencies that can be used for hopping is not dependent on the number of transmitters. It is possible to hop over a lot of frequencies even if only a few transceivers are installed. A disadvantage with synthesizer hopping is that wide-band hybrid combiners have to be used. This type of combiner has approximately 3 dB loss making more than two combiners in cascade impractical.

Frequency Hopping Parameters

Mobile Allocation (MA): Set of frequencies the mobile is allowed to hop over.  Maximum of 63 frequencies can be defined in the MA list.

Hopping Sequence Number (HSN): Determines the hopping order used in the cell.  It is possible to assign 64 different HSNs.  Setting HSN = 0 provides cyclic hopping sequence and HSN = 1 to 63 provide various pseudo-random hopping sequences. 

Mobile Allocation Index Offset (MAIO): Determines inside the hopping sequence, which frequency the mobile starts do transmit on.  The value of MAIO ranges between 0 to (N-1) where N is the number of frequencies defined in the MA list.  Presently MAIO is set on per carrier basis.

Basic Parameter of WCDMA

Basic Parameters of WCDMA

Frequency Band                                     :           2100 MHz

1920-1980MHz (UL) &2110-2170 MHz (DL)

Duplex Space                                         :           190 MHz

Channel bandwidth                                 :           5 MHz

Coding Spacing                                       :           200 KHz (RASTER)

UARFCN Range                                      :           10562-10838 (Total ARFCN – 276)

Duplex mode                                         :           FDD and TDD

Downlink RF channel structure                :           Direct spread

Chip rate& Chips                                    :           3.84 Mcps& It is pulse of spreading spectrum n 

                                                                        It’s in rectangular shape of +1 & -1

Frame length                                         :           10 ms (38400 chips) = 15Slots, & 1slot = 2650chips

Superframe                                           :           A Superframe has a duration of 720ms and consists

                                                                        Of 72 radio frames. The super frame boundaries are

Defined by the System Frame Number (SFN)

Spreading modulation                             :           Balanced QPSK (downlink)

Dual-channel QPSK (uplink)

Complex spreading circuit

Data modulation                         :           QPSK (downlink) & BPSK (uplink)

Channel coding                                      :           Convolution (Voice) and turbo (data) codes

Coherent detection                                 :           User dedicated time multiplexed pilot (DL and UL), 

Common pilot in the downlink

Channel multiplexing in downlink            :           Data and control channels time multiplexed

Channel multiplexing in uplink                :           Control and pilot channel time multiplexed

I&Q multiplexing for data and control channel

Spreading factors                                   :           4–256 (uplink), 4–512 (uplink)

Power control                                        :           Open and fast closed loop (1.6 kHz)

Power control period                              :           1500Hz

Power control step size                           :           0.5, 1, 1.5 and 2db

Power control range

Handover                                              :           Soft HO, softer HO, Inter frequency and IRAT HO