01-BR8.0 DMA&DMA Admission Control
description
Transcript of 01-BR8.0 DMA&DMA Admission Control
Dynamic MAIO Allocation & DMA Admission Control
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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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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%
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
General concept
3 - sector site with 6 hopping frequencies
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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)
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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___ ∗+=
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DMA&DMA Admission Control
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%
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
Interdependencies with other features
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
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DMA&DMA Admission Control
Interdependencies with other features
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
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
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DMA&DMA Admission Control
Attribute Acronym / Attribute Name / Validity range / Default value
CFHSY object – attributes:SUBBAND / subordinateBand / GSM850, PCS1900, DCS1800, BB900, EB900defines the band/sub-band to which CFHSY is applicable
Database parameters
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DMA&DMA Admission Control
Attribute Acronym / Attribute Name / Validity range / Default value
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
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DMA&DMA Admission Control
Attribute Acronym / Attribute Name / Validity range / Default value
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
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Attribute Acronym / Attribute Name / Validity range / Default value
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
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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
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Attribute Acronym / Attribute Name / Validity range, unit / Default value
BTS object – new attributes:
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
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DMA&DMA Admission Control
Attribute Acronym / Attribute Name / Validity range, unit / Default value
BTS object – new attributes:
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
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DMA&DMA Admission Control
Attribute Acronym / Attribute Name / Validity range, unit / Default value
BTS object – new attributes:
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