Introduction to BSS PARAMETER

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Date : Version :Department : File name :

Introduction to BSS PAR (Avea Internal)

23 / 11/ 2011RANOPT

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STRICTLYCONFIDENTIAL FOR INTERNAL USE ONLYDisclosure, copying, distribution of the contents of this document is regulated:refer page 1.

Content

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Following chapters will be included in this study

Parameter Displaying

GSM idle mode and cell (re)-selection

Call setup and resource allocation

DTX and power control

Handover control

AMR

PS features


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3

Display BSS Parameter Structure


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Displaying Parameters-NED

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Displaying Parameters-Netact

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Displaying Parameters-MML

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BTS Object Parameters>>>ZEQO;

BSC Object Parameters>>>ZEEO;


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GSM idle mode and cell (re)-selection

C1 = A max(B,0)

= RLA_C RXLEV_ACCESS_MIN max(MS_TXPWR_MAX_CCH P , 0)

C2 = C1 + cellReselectOffset - temporaryOffset*H(penaltyTime-T)


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GSM idle mode C2 Criteria- TO


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Call setup and resource allocationSignaling


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Call setup and resource allocationTRX Prioritization

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Accessibility and resource allocationDynamic SDCCH

When BTS needs larger SDCCH capacity than the BSC configure

idle traffic channel (TCH) resources for SDCCH use. When SDcongestion is over, the extra SD resources are configured back toTCH.

Dynamic SD signalling is the onlu transmission mode during theconnection to the network. (E.g, SMS & Loc Update in airport)

Configure the min static SD capacity to the BTS sufficient to handlethe normal SD traffic. Extra SD is allocated when actual SDcongestion has start after last free is allocated. When Dynamic SDresource is free again, it is immediately configure to TCH again

With Dynamic SD - 16 SDCCH per TRX, increase dynamic SDcapacity, you can use to 32 SDs per non-BCCH TRX and 24 perBCCH TRX


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Accessibility and resource allocationDirected Retry (DR)

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SD HO starts when normal HO assignment procedure not allow The time is controlled by cell-by-cell with (MIDR), min time limit direct retry

and it controls by BSC. The candidate cells in DR are examined same way as forced HO procedure. Procedure of the criteria for selecting candidate cells

Rx signal level compared to the threshold value, Rx lev min cell (SL)

MS classmark Maximum power level in the cell

DR threshold (DRT) also consider in the candidate cell list where the minthreshold value of Rx signal level.

Normally, DRT > Rx lev min cell (SL) => take DRT. If DRT< Rx lev min cell (SL) => take Rx lev min cell (SL)

SD to TCH => can performed direct retry if SD to SD is forbidden. SD HOdoes not affect DR

Queueing during directed retry also allow the BTS to release TCH resourceand during queueing no call attempt clearing and perform directed retry


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BTS Output Power

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PMAX1 (MS): Max MS PowerPMAX1 (BS): Power Attennuation


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Discontinuous transmission (DTX)

In DL DTX is enabled in the BSC3i by modifying the value of the appropriate PAFILE

parameter, DL DTX is Disabled by Default.

Downlink DTX is controlled by BSC/MSC together. Activated for all BSCs, in Avea.

In UL DTX is configurable via BTS parameter: DTX

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Power Control

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Power Control

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Lower Level Upper Level

Upper Quality

Lower Quality

No action Power decreasedue to level

Power increasedue to qualityPower increasedue to levelor quality

Power increasedue to quality

Power decreasedue to levelor quality

Power increasedue to level

Power decreasedue to quality6 dB

Power increasedue to level


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Power Control Parameters, ZEUO

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Handover Control

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Handover Causes, City

UL Qual

UL Level

DL Qual

DL Level

UL Interference

DL Interference

Power Budget

Handover Causes, Rural Areas

UL Qual

UL Level

DL Qual

DL Level

UL Interference

DL Interference

Power Budget


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Handover Control

BTS Plus Handover Algorithm

Handover algorithm is located in the BSxx - BTS evaluates HO criteria and

triggers HO (generates HO CONDITION INDICATION message with target cell

list)

There is no handover algorithm running in Flexi-BSC (BSC only selects the

candidate from target cell list and allocates channel)

Flexi-BSC can only request BS2xx to start a handover if needed e.g. due tocongestion

Even though Measurement Result (MR) messages are not needed for the HO

purposes the BSC is able to receive them from BTS and update supported

statistics and traces as well as to deliver all needed radio measurement data for

positioning system and real-time road traffic monitoring system just like with

Flexi EDGE BTS.

As HO algorithm is in the BTSplus, the BSC needs to use BTSplusspecific signaling to start intra-and inter-cell HOs.

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Handover controlBetter cell HO (PBGT in BSS)

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HO due to power budget (PBGT) is performed when a neighbor cell offersbetter DL RXLEV conditions than the serving cell. This typically happens

when MS reaches the border

of the currently serving cell and simultaneously enters the coverage area of

a neighbor cell.

In GEMINI due to function split the evaluation algorithm for the handovercriteria is like in BR while BSC handles the evaluation and selection of the

given target cell.


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PBGT Parameters, ZEHO & ZEAO

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Umbrella Handover

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Macro Cell GSM1800

Radio Coverage Layer 4

Umbrella Cell GSM900


Macro Cell GSM900


Micro Cell GSM900


Micro Cell GSM1800


Pico Cell GSM900

Radio Coverage

Layer 1


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Level Handover

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In case the signal level measured in UL or in DL on the air interface is below a

certain limit and power control means are exhausted intercell handover is triggered


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Level Handover

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Level Handover

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Handover controlQuality and Interference HO

Quality HO (intercell HO)

Interference HO (intracell HO)

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TRHO-Traffic reason HO

MSC initiated Traffic Reason HO (TRHO) BSC receives initiation of MSC controlled Traffic Reason HO from the MSC and indicates to

the BTS to start Traffic Reason HO (BTS_DYNAMIC_LOAD_INFO with flag Traffic HO =enabled)

The BSC counts number of performed Traffic Reason HOs and sets the flag to valuedisabled and resends BTS_DYNAMIC_LOAD_INFO instructing BTS to stop forced HOwhen required number of Traffic Reason HOs has been performed.

The BSC does not send to the BTS a HO candidate list received from the MSC. The BSC must response to MSC within 20 sec. The BSC informs BTS about load conditions when there is at least one TRX

up and running in the cell (1 minute interval with latest load information) BSC controlled Traffic Reason HO (TRHO) BSC knows the load of a cell and indicates to the BTSplus HO-algorithm when to start

Traffic reason HO to lower load in a cell. The BSC instructs BTS to start forced HO when the load of a cell is over "AMH upper load

threshold. BTS_DYNAMIC_LOAD_INFO with flag Traffic HO = enabled is sent. The BSC instructs BTS to stop forced HO when load of a cell goes below "AMH upper load

threshold. BTS_DYNAMIC_LOAD_INFO with flag Traffic HO = disabled is sent.

In BSS as well as in GEMINI it's recommended not to enable BSC-initiated Traffic reason HO(AMH feature) and MSC-initiated Traffic reason HO simultaneously

Technically it is possible to use both TRHOs at same time and it's up to operator to usethem simultaneously, two simultaneous and separate TRHO algorithms may work not soreasonable together.

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TRHO

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Handover controlPrevention of back HO and HO fail repetition

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Inter system Cell Reselection/HO

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Inter-System HO from 2G to 3G is Disabled.Cell Reselection is enabled from 2G to 3G or vice versa.

Inter-System HO is Enabled from 3G to 2G


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Inter system Cell Reselection/HOZEQO & ZEAI

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Frequency hopping

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To define a RF-hopping cell the following parameters have to be set in

BSS:BTS hopping mode (HOP) = RFMA-list, MA-list ID and MA-list type must be defined in BSC

If EGPRS is supported, there can be up to 47 frequencies in the MA-listIf EGPRS is not supported, there can be up to 52 frequencies in the MA-list

Hopping sequence number 1 (HSN1) = 0..63 (0 for cyclic hopping and1..63 for random sequences)

MAIO offset = 0..62MAIO step = 0..62MA-list ID used by the BTS = 0..128


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Frequency hopping

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MAIO TRX:

Example:

)1()( nMAIOMAIOMAIO stepoffsetnTRX

Sector TRX # HSN MAIO stepMAIOoffsetl MAIO

1 1 Non-hopping BCCH TRX

2 7 2 0 0

3 2

4 4


2 7 2 6 6

3 84 10


2 7 2 12 12

3 14

4 16

MAIO step indicates the

difference between the MAIOs of

successive TRXs in a cell.

+MAIO step


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Half Rate HR-Channel Allocation

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Free FR TCHs based

on ratio of availableto working FR TCHs

Process is disabled

by setting lower limit

> upper limit

Enabling load

analysis at BTS level

automatically disables

it at a BSC level

To disable at BTS

level must be disabled

at both BTS and BSC

level


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AMR Link Adaptation

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AMR Link Adaptation

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AMRHandover & Power Control Parameters

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AMR HO

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Intra cell Handover process (FR to HR packing) is based upon BTSload, call quality and current codec being used

In case of inter cell HO there are no differences in RXQUALmeasurement method between EFR and AMR EFR call and AMR call in identical location should show identical

RXQUAL measurements In congested cell with no available TS for unpacking, Inter-cell HO

required based on RXQUAL. The following AMR HO parameters are used:

Intra HO threshold Rx Qual for AMR HR Intra HO threshold Rx Qual for AMR FR Current Nx and Px values of RxQual thresholds are used amrConflnHandover

1 = the currently used multirate configuration is preferred 2 = the multirate configuration of target BTS is preferred

amrSetGradesEnablY/N

Y = downgrades and upgrades are applied N = downgrades and upgrades are not applied

If multirate configuration of source and target BTS are the same, these 2parameters has no impact.


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AMRQuality HO

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Parameter Descriptionthreshold ul Rx qual AMR HR

object: BTS

range: < 0.2% (0), 0.2% - 0.4% (1),0.4% - 0.8% (2), 0.8% -1.6% (3),1.6% - 3.2% (4), 3.2% - 6.4% (5),6.4% -12.8% (6), > 12.8% (7)

default: 1.6% - 3.2% (4)

MML command: EHB, EHO

MML Abbreviated Name: QURH

threshold ul Rx qual AMR HR (amrHoHrThrUlRxQual), with this parameter youdefine the threshold level of the signal quality uplink measurements for triggering thehandover. Defined for the default AMR HR set.

In GEMINI it is extracted from Service Group parameters if used; otherwise set todefault

threshold ul Rx qual AMR FR

object: BTS

range: < 0.2% (0), 0.2% - 0.4% (1),0.4% - 0.8% (2), 0.8% -1.6% (3),1.6% - 3.2% (4), 3.2% - 6.4% (5),6.4% -12.8% (6), > 12.8% (7)

default: 1.6% - 3.2% (4)

MML command: EHC, EHB, EHO

MML Abbreviated Name: QURF

threshold ul Rx qual AMR FR (amrHoFrThrUlRxQual), with this parameter youdefine the threshold level of the signal quality uplink measurements for triggering thehandover. Defined for the default AMR FR set.

In GEMINI it is extracted from Service Group parameters if used; otherwise set todefault


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RLT-ARLT

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RLT is based on SACCH deletion. SACCH is though not using a dynamic codec like voice in AMR, whichmeans:

Using the EFR RLT value an AMR customer can have the call dropped because RLT = 0 when still the FER isgood

RLT is not anymore reliable with the same value in AMR than in EFR

Due to the fact that the FER performance is different when comparing AMR calls to EFR calls, the Radio LinkTimeout need to be defined separately for AMR

The Radio Link Timeout parameter for AMR is ARLT, available from S11.5. The principle of ARLT is the samethan in the RLT but it is used only for the AMR capable mobile stations.

With ARLT the maximum value of the radio link counter expressed in SACCH blocks for AMR calls is defined.The values range from 4 to 64 blocks, and can be changed by 4-block steps at a time. The default value forARLT is 20 (SACCH).


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Antenna Hopping Feature AHOP

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BCCH layer has no DL diversity, only one frq transmitting over asingle antenna. The non-hopping TRX (BCCH TRX) loses coveragedue to interference and fading and hopping TRX have a biggercoverage area because the phase diversity (hop one frq to another)where reduces fading and frequency related interference.

Improve DL/link performance of RF or BB hopping on non-hoppingTRX and bridge the gap in between the hopping and non-hoppingTRX. Therefore, improve existing coverage and RSSI level & alsoimprove interference area due to improve link performance.

Min 2 TRX in a BTS. Unable to work when TRX is locked mode.

BCCH TRX Coverage

Hopping TRX Coverage


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PS Features&ParametersAir Interface-Territory Concept

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PS territory is defined per BTS object with three parameters dedicatedgprsCapacity (CDED) - determines the dedicated PS territory size in BTS

(number of radio timeslots reserved for PS traffic only) defaultgprsCapacity (CDEF) - determines the default PS territory size in BTS (number of

radio timeslots used primarily for PS traffic; if CS territory is congested, TSL from default

territory may be allocated to CS connection);

default territory includes dedicated territory.

maxGPRSCapacity (CMAX) - determines the maximum possible PS territory size in BTS(maximum number of radio timeslots which can be used by PS traffic: default territory +

additional territory); default territory may be extended with additional territory (up to CMAX) ifone of the following conditions is fulfilled:

default territory does not allow MS to be allocated the number of channels according to

its Multislot Class;

the average number of TBFs per TSL is more than 1.5 after the allocation of the new

TBF;

GTRX to define TRX which support data service in TRX level, not separate parameter for

EDGE/GPRS these parameters are expressed in percentage of all radio TSLs in a BTS which can be used

as PDCH (timeslots belonging to (E)GPRS enabled TRXs and defined as TCH FR or TCH

DR)

Date serivce support through set GENA = Y in BTS level;

EDGE support through set EGENA=Y and GENA = Y in BTS level


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PS Features&ParametersAir Interface-Territory Concept

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PS territory is a set of contiguous timeslots selection of a TRX for territory creation (the beginning of the territory) is

determined by prefBCCHfreqGPRS parameter (BFG); this parameter defineswhether BCCH TRX or non-BCCH TRX is preferred for PS territory

among TRXs with the same priority, the one with the higher number of

contiguous free TCHF and/or TCHD channels is selected

default territory (including dedicated territory) is always created starting from the

end of TRX (TSL7)


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Abis PlanningDAP Structure

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Abis PlanningDAP Structure


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PS Parameters

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Practice

Please discuss the following cases separately. Try to determine the

related radio parameters. Assume that there is no HW or Specific NW Problem.

Consecutive Handover Attempts/Failure to the same target cell?

Low Power from BTS?

Try to reduce the output power of the BTS.

Pushing traffic to Neighbor Cell (Idle Mode)

Pushing traffic to Neighbor Cell (by Umbrella Handover)

Reducing TCH Congestion. (by Directed Retry)

2G>>3G Cell Reselection is not happening.

Subscriber Complaints regarding Edge download speed?

Introduction to BSS PARAMETER

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