01-br8.0 dma&dma admission control

Dynamic MAIO Allocation & DMA Admission Control

© Siemens Sebastian Lasek/Com SDC NA B1 Jul-06 2

DMA&DMA Admission Control

Slow Frequency Hoppingwell known and widely used feature in GSM networkSFH means that the frequency of radio timeslot is changing burst by burst (frequency remains the same during a burst)significant quality and capacity enhancements due to effects

frequency diversityinterference diversity

following parameters describe the hopping frequency used in each frameMobile Allocation Index Offset (MAIO)Hopping Sequence Number (HSN)

hopping list is given by the mobile allocation (MA) list

General concept



General concept

MA provides the list of hopping frequenciesMA length = 18

HSN defines the hopping sequence to be used (specifies in which order frequencies shall be used)

HSN = 0 - cyclic hopping (frequencies are changed in a consecutive order)HSN = 1…63 - random hopping (frequencies are changed according to a pseudo-random sequence)

MAIO implies a shift defining the start frequency in the FH pattern defined by HSN

MAIO can take as many values as there are frequencies in the MA listMAIO planning prevents co- and adjacent channel interference within cell, between co-sited sectors or synchronized cells when using SFH



BCCH TRX0

MAIO = 4 TRX1

MAIO = 10 TRX2

MAIO = 16 TRX3

BCCH TRX0

MAIO = 2 TRX1

MAIO = 8 TRX2

MAIO = 14 TRX3

General concept

with MAIO planning co-channel (adjacent) channel interference can be avoided

frame number synchronization between cells required

BCCH TRX0

MAIO = 0 TRX1

MAIO = 6 TRX2

MAIO = 12 TRX3

Random Hopping (1, 2, 10, 7, . . . )

Time (TDMA frame)

MA



1/1 reuse pattern deployment

the same MA within sitesall sectors of the site have common frame number (FN) (are FN synchronized) all sectors within site have the same HSN, e.g. HSN =3

General concept

MA, HSN and FN are fixed for the siteintra-site interference can be controlled by allocating appropriate MAIOs

degree of control interference at the site is conditioned by the fractional load

MA

MA

MA

HSN = 3

HSN = 3

HSN = 3



General concept

MA

MA

MA

HSN = 3

HSN = 3

HSN = 3

Static MAIO Allocation, SMA

the set of MAIOs allocated to the site is split into three subsets with different MAIOs for each sector

common practice is to assign equal MAIO values to all the channels of the same TRX

MAIO values must be reused within the site if number of deployed hopping transceivers > number of hopping frequencies

MAIO repetition = continuous intra-site co-channel interference = network quality degradation

MA = f1, f2, f3, f4, f5, f6

if no. TRX per site =< 6

no MAIO repetition

otherwise

MAIO has to be reused

MAIO = 0, 1, 2, 3, 4, 5



General concept

the degree of control of both co-channel and adjacent channel by MAIO management functionality is conditioned by the applied fractional loadAssumption:

consecutive frequencies in the MA list

Fractional Load Intra-site interference MAIO selection

FL ≤ 16.67% no co-channel or adjacent channel interference MAIO distance ≥ 2

16.67% < FL ≤ 33.3% adjacent channel interference between co-sited sectors; no co-channel interference MAIO distance ≥ 1

33.3% < FL ≤ 100%

co-channel interference between co-sited sectors; adjacent interference between co-

sited sectors; adjacent channel interference within the sectors

MAIO distance < 1; reuse of MAIOs necessary

FL = NTRX/#hoppers * 100%



General concept

3 - sector site with 12 hopping frequencies

TRX0

TRX1

TRX2

BCCH

MAIO = 0

MAIO = 3

MAIO = 6

TRX4 MAIO = 9

TRX3

TRX0

TRX1

TRX2

BCCH

MAIO = 2

MAIO = 5

MAIO = 8

TRX4 MAIO = 11

TRX3

TRX0

TRX1

TRX2

BCCH

MAIO = 1

MAIO = 4

MAIO = 7

TRX4 MAIO = 10

TRX3

4 TRX per cell

FL = 33.33%

Maximum carried traffic @2% = 23.72 Erl

# of MAIO = # of hoppers =>maximum number of TRXs per cell is limited by the number of available MAIOs (assuming single MAIO usage)

if additional TRXs required, MAIO already used in a neighbor sectors of the site has to be assigned to new deployed TRXs

introduction of permanent intra-site co-channel interference between certain TRX



General concept

3 - sector site with 6 hopping frequencies



Feature description

Dynamic MAIO Allocation (DMA)

to increase network capacity number of TRX installed per site have to be increased over the number of hopping frequencies

MAIO reuse within site => continuous intra-site co-channel interference and adjacent interference within sector => radio quality degradation

to minimize intra-site interference DMA has been designed to select the best TS/MAIO pair using the common pool of MAIO on site level

list of MAIO values is not divided into subsets for each sector, but it is considered as common resources at site level

benefits of DMA remarkable especially in case of instantaneous inhomogeneous traffic distribution on site sectors



Feature description

Dynamic MAIO Allocation (DMA) algorithm

DMA algorithm inputlist of free time slots of the serving celllist of MAIO available for DMAtable with the number of occurrences of dynamic MAIO values within the site for each TStable with allocation state of dynamic MAIO values within the serving cell for each TS

for each incoming voice callDMA selects a channel on the basis of the current MAIO utilizationstate within the site algorithm operates on the entire TSxMAIO domainall MAIOs can be used and reused in all sectors of the site



Feature description

Dynamic MAIO Allocation (DMA) algorithm

avoids the repetition of MAIO values in the serving cellavoids intra-cell co-channel interference

minimizes the number of MAIO repetitions within the sitenumber of channels affected by intra-site co-channel interference

controls the number of MAIO adjacencies in the serving cellnumber of channels affected by intra-cell adjacent channel interference

controls the number of MAIO adjacencies within the sitenumber of channels affected by intra-site adjacent channel interference



Feature description

Mandatory requirements for DMA:dynamic MAIO Allocation applies to speech calls only (EFR, FR, HR, AMR FR, AMR HR)synthesizer frequency hopping enabledthe same MA within site (1x1 frequency reuse) air interface synchronization among cells of the same site (intra-site synchronization)cells within site must have the same HSNs

the assignment of different HSN in neighbour sites is also mandatory in case of inter-site synchronisation and it is recommended even if sites are not synchronised in order to prevent quality degradation in case of accidental synchronisation

in case of TRXs supporting GPRS, HSCSD - SMA must be appliedwhen multislot configuration is used timeslot must belong to the same frequency hopping law i.e. they must have the same MAIO (also HSN and MA)



Feature description

DMA simulations results

soft-blocked

23.72 TCH Erl/cellhard-blocked

30.5 TCH Erl/cell

ideal network (homogenous) 5 MHz band (12 TCH and 12 BCCH frequencies)voice codec AMR FR 5.9 kbpsno performance of signalling channels considered (SACCH, FACCH)

Quality performance target

hard blocking rate <= 2%

BQP <= 5% BQP is the percentage of samples (voice blocks) with FER greater than 2.5%

for this scenario:

DMA provides 26% capacity gain



Dynamic MAIO Allocation – application scenariosnumber of hopping TRXs per site > number of hopping frequencies in MA list

intra-site co- and adjacent channel interference can be decreased, capacity limits of SMA overcome

number of hopping TRXs per site < number of hopping frequencies in MA list

number of hopping TRXs per site > 0.5 * number of hopping frequencies in MA list

(16.67% < FL ≤ 33.3%)

intra-site adjacent channel interference can be decreased

(E)GPRS, HSCSD on BCCH TRX only

MAIOs considered as common resource at the site level

(E)GPRS, HSCSD on hopping TRX

for TRXs supporting GPRS, HSCSD, SMA must be applied

static MAIO values excluded from list of MAIOs used by DMA

Feature description



Capacity of the system can be limited by

hard blockingsoft blocking

Hard blockingall radio resources in use – due to lack of free TS no more calls can be establishedspecific for loose frequency reuse patterns

Soft blockingcapacity of cell limited by the level of interference (resources still available)

specific for tight reuse patterns

Feature description



in high capacity networks with a high number of TRX installed in each cell and tight reuse patterns

soft blocking happens prior to hard blockinginterference level may exceed the critical (soft blocking) limit at which the speech quality becomes unacceptable before all channels have been allocated

currently Admission Control for CS speech services is based on Hard Blocking

new call request is rejected if all channels accessible for voice are busy

BR8.0 Admission Control (AC) feature is capable to identify the soft blocking limit

AC is applied only to new CS speech service requests on the layer with enabled DMA and to forced intra cell HO (reorganisation, enhanced pairing procedure)all types of inter-cell handovers are handled in the usual way even if the DMA layer(s) of the target cell is (are) soft-blocked

Feature description



Admission Control due to Soft Blocking for CS speech services isbased on both:

Speech QualityBad Quality Probability (BQP) - probability (percentage) of occurrence of speech samples with FER over a certain threshold

BQP = P(FER > FERmax) FERmax – FER threshold defined by operatorQoS criterion related to the speech quality in a cell is met if BQP is below a certain threshold called outage probability

BQP = P(FER > FERmax) ≤ BQPmax

e.g. BQP(FER>2.5%) ≤ 5%

Effective Fractional Loadat low traffic the reliability of BQP relatively low => decision for soft blocking quite unreliable

Feature description

100*_8

___DMAmoballoc

DMABusyChanmeanDMAEFL nn ∗=

nnn DMAHRmeanDMAFRmeanABusyChanDMmean __5.0___ ∗+=



impact of BQP, FER threshold settings on capacity figures (based on simulation scenario - see slide 13)

Feature description

Quality performance target:

BQP <= 10% AND hard blocking rate <= 2%BQP is the percentage of samples with FER > 2.5%, 5%, 10%

Quality performance target:

BQP <= 5% AND hard blocking rate <= 2%BQP is the percentage of samples with FER > 2.5%, 5%, 10%



complete AC procedure comprises following two steps:calculation of mean BQP and EFL on DMA layerevaluation of the Soft-Blocking-Qualifier based on mean BQP and EFL threshold comparison

SBQ evaluation

Feature description

ACLinkType = 0 - both UL BQP samples and DL BQP samples shall be collected; both BQP in UL and BQP in DL shall be estimatedACLinkType = 1 - only UL BQP samples shall be collected; only BQP in UL shall be estimatedACLinkType = 2 - both UL and DL BQP samples shall be collected; a single BQP value representing a common BQP for UL and DL

shall be estimated by merging the UL and DL BQP samples



complete AC procedure comprises following two steps:calculation of mean BQP and EFL on DMA layerevaluation of the Soft-Blocking-Qualifier based on mean BQP and EFL threshold comparison

Feature description

DMAEFL _minDMAEFL _max

adjustable thresholds for the EFL for the DMA layer on a per cell basis

minimum EFL on the DMA layer in percentmaximum EFL on the DMA layer in percent



Feature description

pixel

CI

Interfering Cell Interfered Cell(Victim)

co-channel interference threshold = x dB- number of pixels in the service area: e.g. 400- number of pixels with C/I < x dB: e.g. 23

f1

f1Percentage of Traffic is interfered

Reduced Capacity/Cell

“Soft Blocking”

27 Erlang/site

19 Erlang/site



Interdependencies with other features

DMA and DMA AC can be applied only for CS speech services (e.g. EFR, FR, HR, AMR FR, and AMR HR)

maximum of two DMA layers can be configured in a cell depending on the cell type

in a single band standard cell just one DMA layer is configurablein case of a Dual Band Standard Cell and EXT900 two different DMA layers (one DMA layer per band) are configurable




in an EXT900 or Dual Band Standard Cell, if one DMA layer is soft-blocked, it is be possible to use the second DMA layer

precondition: the latter has been configured and is not soft-blocked at the same time

DMA and DMA AC is not applicable toboth dual band and single band concentric cells

extended cells

AC operates only on the service layer with enabled DMA and is applied for each DMA layer separately

if the DMA layer is soft-blocked, the Resource Management should try to allocate the new CS speech service request on another layer of the same cell

precondition: such a layer has to be configured for this type of service




Network synchronizationDMA requires that sectors within a site are synchronous at frame level and at time slot levelequal Frame Number and Burst Number Offset shall be used for all the sectors of the site



DMA&DMA Admission Control – operator benefits

Dynamic MAIO Allocation

no MAIO planning is necessary (OPEX reduction)

capacity enhancement in 1:1 frequency re-use networks

improved trunking efficiency by considering the radio resources (MAIO) as a common pool available at a site level rather than at a sector level

Admission Control

achievement of maximum capacity at an acceptable quality

based on continuous supervising of both the speech quality and system load in the cell

customer is able to control the perceivable quality in the network by adjusting the relevant thresholds



Objects CFHSY – Common FHSYdefines the DMA hopping law shared by several BTS of the same BTSMtwo per CBTS (configurable in different bands)

CFHSY

BTSM

CFHSY

CBTS

BTS

Object CBTS - Common BTSgroups the attributes shared by several BTS of the same BTSM provides services of DMA enabling/disabling in all BTSs of the same BTSM and all the DMA frequenciesone per BTSM

Database parameters



Attribute Acronym / Attribute Name / Validity range / Default value

CBTS object – attributes:CCALLF <x> [x = 1..63] / commonCellAllocationF / 0..1023 / <NULL>defines radio frequency usable in all BTS of the same BTSM

ENDMA / enableDMA / TRUE, FALSE / FALSEindicates whether the DMA feature is activated or notENDMA – can be set to TRUE if in at least 2 equipped BTS ENDMA attribute is set to TRUE

CFHSY object – attributes:HSN / 0..63describes hopping sequence in use

CMOBALLOC / commonMobileAllocation / CCALLF <x> [x = 1..63]list of absolute frequencies used in hopping sequence: max 63 frequenciesno NULL CCALLFx can be included in CMOBALLOCall frequencies must belong to the same band

Database parameters




CFHSY object – attributes:SUBBAND / subordinateBand / GSM850, PCS1900, DCS1800, BB900, EB900defines the band/sub-band to which CFHSY is applicable

Database parameters




BTS object – new attributes:CCALL / commonCellAllocation / CCALLF<x> / <NULL>defines the list of frequencies inherited from CBTSBCCHFREQ and CALLF<x> cannot use CCALLF<x> frequencies

ENDMA / enableDMA / TRUE, FALSE / FALSEindicates whether the DMA feature is activated or notENDMA can be set to TRUE if HOP=TRUE and HOPMODE=SYNHOPENDMA can not be set to TRUE in extended and concentric cells

TRX object – new/modified attributes:TRXFREQ / carrierFrequency / BCCHFREQ, CALLF <x>, CCALLF<x>attribute is used to assign a constant radio frequency to a transceiverMAIO / maio / 0..63 / <NULL>static MAIO to be applied to all subordinated channels for SMA or when ENDMA=FALSE

Database parameters




TRX object – new/modified attributes:FHSYID / frequencyHoppingID / FHSY[0..10], CFHSY[0..1] / <NULL>parameter represents the frequency hopping system identifier

CHAN object – new/modified attributes:FHSYID / frequencyHoppingID / FHSY[0..10], CFHSY[0..1]default will be assigned by BSC, it depends on FHSYID of superordinate TRX

Database parameters




CHAN object – new/modified attributes:MAIO / maio / 0..63 / <NULL>default will be assigned by BSC, it depends on FHSYID of superordinate TRXno mixed configuration between SMA and SMA are possible between channels of the same TRX

Other remarksDMA instance is active after creation of the corresponding CBTS and CFHSY objects and after the EDMA attribute of the CBTS object has been set to TRUE. The algorithm will use the resources of the cells where ENDMA is TRUE

Database parameters



Attribute Acronym / Attribute Name / Validity range, unit / Default value

BTS object – new attributes:

EAC / enableAc / TRUE, FALSE / <NULL>EAC = TRUE: AC on cell basis is enabledEAC = FALSE: AC on cell basis is disabledAC can be enabled only if DMA is enabled both in the BTS and in the CBTS

ACBQPMAX / acBQPMax / [2.0…10.0], stepsize 1.0, [%] / 5.0%parameter specifies the maximum tolerated Bad Quality Probability (outage probability) in the cell

ACFERMAX / acFERMax / [1.0…10.0], stepsize 0.5 , [%] / 5.0%parameter specifies the maximum tolerated FER for speech samples taken over 4 SACCH periods

Database parameters





ACLNKTYP / acLinkType / {0, 1, 2} / acLinkType =1parameter defines the type of samples to be collected and the way they are used for the estimation of BQPMeaning:

acLinkType =0 UL and DL samples shall be collected and separately evaluated

acLinkType =1 only UL samples shall be collected and evaluated

acLinkType =2 UL and DL samples shall be collected, merged and commonly evaluated

NOTE:ENHANCED MEASUREMENT REPORTING shall be activated if:

acLinkType = 0 or acLinkType = 2

Database parameters





ACPER / acPeriod / [20…400], stepsize 4, [SACCH Periods] / 120parameter specifies the Admission Control Period in SACCH periods

ACBQPFF / acBQPFgtFac / [0.1…1.0], stepsize 0.1 / 0.2to avoid the impact of stochastic fluctuation in BQP on AC decision the BQP values calculated in each ACPeriod are averaged using an exponential filter with adjustable forgetting factor (β)

mean_BQPn = (1- β) * mean_BQPn-1 + β * BQPn

ACEFLFF / acEFLFgtFac / [0.02…0.2], stepsize 0.02 / 0.04to get an estimate of the traffic on the DMA layer of the cell the average number of busy channels is calculated using exponential filter with an adjustable forgetting factor (λ)

mean_ZZ_DMAn = (1- λ) * mean_ZZ_DMAn-1 + λ * ZZ_DMAn (ZZ = FR or HR)

Database parameters





ACMAXEFLDMA / acMaxEFLDMA / [10…100], stepsize 5, [%] / 50parameter specifies the maximum EFL on the DMA layer of the cell

ACMMINEFLDMA / acMinEFLDMA / [5…50], stepsize 5, [%] / 10parameter specifies the minimum EFL on the DMA layer of the cell

Database parameters

01-br8.0 dma&dma admission control

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