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B03 WCDMA Capacity Dimensioning

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B03 WCDMA Capacity Dimensioning

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  • *WCDMA Capacity Dimensioning

  • Foreword WCDMA is intrinsical Interference limited system

    Coverage and capacity depend on the interference

    WCDMA is a Soft Capacity system

  • Outline Radio Dimensioning Procedure

    Radio Link Budget

    Capacity Dimensioning

    AppendixStochastic Knapsack: Blocking ProbabilityCampbells Dimensioning ProcessInterference Analysis

  • CapacityQualityCoverageDependence among Capacity, Coverage and QualityCapacity-Coverage-Quality

  • Capacity vs. Coverage

    Cell Load Coverage Range Cell Load Subscribers

    Capacity vs. Quality

    BLER Capacity GoS Capacity

    Coverage vs. Quality

    BLER Coverage RangeCapacity-Coverage-Quality

  • Capacity-Coverage-QualityIndependence among Capacity, Coverage and Quality of GSM System

    Capacity: Timeslots and Carriers available and Reuse Mode Coverage Range: transmission Power on Uplink/Downlink (Link Balance)Quality of Call: be ensured by network design to minimize interference

    In GSM system, capacity, coverage and quality requirements can be met by independently analysis and designFrequency Planning is a crucial issue to GSM system

  • Dependency among Capacity, Coverage and Quality of WCDMA SystemWCDMA system is interference-limited. Capacity vs. CoverageIncrease intended system loading will offer more capacity while increasing intra-cell interference and thus reduce coverage range (Application: Cell breathing)Capacity vs. QualitySystem capacity can be achieved by relaxing quality requirement for some connections (Application: Reduce BLER target value by outer-loop power control)Coverage vs. QualityCoverage range can be expanded by relaxing quality requirement for some connections (Application: Slow down data speed by AMRC to accommodate large path loss)CapacityQualityCoverageInterferenceInterference is the dominant concern in capacity analysisCapacity-Coverage-Quality

  • Radio Dimensioning Procedure Network dimensioning is an iterative process Downlink analysis checks whether NodeB power is enough to cover the users

  • Outline Radio Dimensioning Procedure

    Radio Link Budget

    Capacity Dimensioning

    AppendixStochastic Knapsack: Blocking ProbabilityCampbells Dimensioning ProcessInterference Analysis

  • Radio Link Budget: PurposeCalculate the Maximum Path Loss

    EIRPSensitivity of ReceiverMinimum Required Signal Strength

    Calculate the Cell Range

    Propagation ModelMaximum Path LossAntenna HeightCarrier Frequency

  • BS Antenna GainRx&Tx Cable LossPropagation Loss Body Loss Penetration Loss

    Radio Link Budget: SketchTRX

  • Radio Link Budget: Important ParametersEIRPSensitivity of Receiver Minimum Signal StrengthEdge Coverage ProbabilityPropagation ModelMarginGainLoss

  • Radio Link Budget: Margin, Gain, Loss

    Margins

    Interference MarginSlow Fading MarginFast Fading MarginGains

    Antenna GainSHO GainLoss

    Body LossCable Loss Penetration Loss

  • Outline Radio Dimensioning Procedure

    Radio Link Budget

    Capacity Dimensioning

    AppendixStochastic Knapsack: Blocking ProbabilityCampbells Dimensioning ProcessInterference Analysis

  • Capacity Dimensioning: Purpose Estimate Supported Subscribers

    Cell Resource Mixed Services Service Traffic Respective GoSEstimate Site Number

    Site Number (Coverage) Site Number (Capacity)

  • Capacity Dimensioning: Difficulties Cell edge is continuously moving according to the traffic load

    Mixed services: multiple data rates

    Respective GoS Requirement

  • Capacity Dimensioning: main methods Campbells Theorem

    Stochastic Knapsack

    Fractional Load

  • Stochastic Knapsack: What is it ?What is Knapsack ?

    What is in the Knapsack ?

    Knapsack for Uplink = ?

    Knapsack for Downlink = ?

  • Stochastic Knapsack: Where is it from ? a Multi Service Traffic Model

    Used in ATM Multiplexer Dimensioning

    Simulate the Respective GoS of the Supported Services

  • Stochastic Knapsack: Introduced into WCDMA Blocking Probabilities

    Shared Resource

    Simulate actual Traffic Behavior

    Uplink Resource: Cell Load (why)

    Downlink Resource: Power (why)

    Modified to WCDMA Air Interface Dimensioning (why)

  • Stochastic Knapsack: Resource Shared Resource Shared

    TimeConsumed Resource

  • Stochastic Knapsack: Example

    Users States for 2 services Video Phone CallVoice Call Knapsack? What is the user state in the Knapsack? Which call will be blocked? Which call can access the Knapsack?

  • Stochastic Knapsack: Example

    the user state if not calls arrive? the user state if a voice call access? the user state if a video phone call access?

    VoiceVideo PhoneUsers States for 2 services

  • Stochastic Knapsack: Example

    Two ServicesBlocking Prob. for Service 1VoiceVideo Phonethe 4 states will be blocked for voice service. Why?

  • Stochastic Knapsack: Example

    Two ServicesBlocking Prob. for Service 2VoiceVideo Phonethe 7 states will be blocked for video phone service. Why?

  • Stochastic Knapsack: Questions What is the advantage?

    What is the disadvantage?

  • Campbells Theorem

    Virtual ServiceVideo Phone CallVoice Call

  • Campbells Theorem Multi services one Virtual Service Virtual Service Load Virtual Service Traffic How to Calculate? (Appendix)

    One Service Calculation Erlang B Formula

  • Campbells Theorem What is the advantage?

    What is the disadvantage?

  • Fractional Load Traffic for each service Traffic/BH/Sub Supported Subscribers Channels needed for each service GoS requirement Erlang B Fractional Load for each service single link load channels Cell Load for all services accumulate all the fractional load

  • Fractional LoadTimeConsumed Resource

  • Fractional Load What is the advantage?

    What is the disadvantage?

  • Comparison of the Methods Stochastic Knapsack

    Complicated

    actual traffic behavior

    resource shared

    respective GoS for each service

    only one GoS for all services can guarantee all the GoS requirements?

    resource shared

    easy to calculate

    Fractional Load

    Campbells Theorem

    resource not shared

    easy to calculate

  • Comparison of the Methods only one service the same result (why) Fractional Load pessimistic more NodeB sites Campbells Theorem uncertain optimistic e.g. 2% GoS for all services Stochastic Knapsack reasonable

    Dimensioning Result:

  • Contents

    Uplink capacity analysis

    Downlink capacity analysis

  • Uplink capacity analysisSingle CS service Single PS serviceMixed services

  • Single CS serviceTo single CS service, the uplink total received power in BS can be calculated as:

    meet Poisson arrival, and the mean value is:

  • Single CS service

    ThenSo

  • Single CS service

    The number of uplink channel supported by system with corresponding uplink loading is:

  • Single CS service

    Defining: Then the soft-blocking formula based on interference of uplink is

  • Uplink capacity analysisSingle CS service Single PS serviceMixed services

  • Single PS service PS service model

  • Single PS service

    Then the soft-blocking formula based on interference of uplink is

  • Single PS serviceBecause the blocking characteristic of PS service is determined by the acceptable delay, according to ErlangC formula, defining the channel number: the probability of call with delay can be calculated as:

    So the probability with delay exceeding t(s) of any call is:

  • Single PS service

    Mean delay is:

    Mean throughput of Uplink is

    Here:A is the supported total traffic, N is the channel number, H is the average duration per call of the service.

  • Uplink capacity analysisSingle CS service Single PS serviceMixed services

  • mixed service

    First, we assume these following variables :the user number is X,the number of service type is M, the ration of other-cell to own-cell interference is f, is the cell loading.

  • mixed service

    The traffic of specific service can be calculated as:The loading factor of one service per user can be calculated as:

  • mixed service

    We convert all services to one virtual service and introduce two variables C1 and C2: And the loading factor of per virtual service is:

  • mixed service

    Then the total traffic of virtual service that the cell can support is:here:traffic of voice service :traffic of the ith type data service :traffic of the virtual service

  • mixed service

    According to the preconcerted cell loading , the number of virtual service channel N is:Based on ErlangB formulary:Then:Fromwe can get the number of users X.

  • mixed service

    Then we can get the uplink data throughput rate per carry as following formulary:

  • Contents

    Uplink capacity analysis

    Downlink capacity analysis

  • Downlink capacity analysisSingle CS service Single PS serviceMixed services

  • Single CS service

    The total received interference of a specific UE is:here,is non-orthogonal factor, ith UE from jth site. Assuming the ratio of the dedicated power for Then:So:is the total received power of

    UEi to total power is:

  • Single CS service

    Defining:the ratio of other-cell interference is f :then:The following equation must be satisfied: is the power of common channels

    is the corresponding power of RRM congestion threshold.

  • Single CS service

    Then: Defining channel number:Then we can get the downlink soft block traffic soft block Erlang,and the downlink throughput rate per carry is:From formula:

  • Downlink capacity analysisSingle CS service Single PS serviceMixed services

  • Single PS serviceThe method of downlink single PS service capacity analysis is similar with that of uplink:Defining channel number:and:

  • Single PS service

    the probability of call with delay can be calculated by:So the probability with delay exceeding t(s) of any call is:

  • Single PS service

    Mean delay is:

    Mean throughput of Uplink is

    Here: A is the supported total traffic, N is the channel number, H is the average duration per call of the service.

  • Downlink capacity analysisSingle CS service Single PS serviceMixed services

  • mixed service

    First, we assume these following variables :the user number is X,the number of service type is M, is the non-orthogonal factor, the ration of other-cell to own-cell interference is f, is the downlink cell loading.

  • mixed service The traffic of specific service can be calculated as:The loading factor of one service per user can be calculated as:

  • mixed service

    Defining:And the loading factor of per virtual service is:Then the total traffic of virtual service that the cell can support is:

  • mixed service According to the preconcerted cell loading , the number of virtual service channel N is:Based on ErlangB formulary:Then:Fromwe can get the number of users X.

  • mixed service

    Then we can get the downlink data throughput rate per carry as following formulary:

  • According to the demand of traffic and terrain characteristic, distinguish the planning region into different areas, like as dense urban, urban, suburban, rural and so on.

    Different propagation models for areas.

    Different user numbers and traffic models for each area.

    The demands of QOS and GOS for each service and area.The carry demand for each area, one, two or more carriers.

    Capacity dimension input

  • According to the above inputs of capacity dimension, we can get the number of site and site configuration based on capacity demands.

    Comparing the dimension result of capacity with that of coverage, the limited result is proposed .

    Capacity dimension

  • Rough Dimensioning Result a Rough Dimensioning Result

    a flat and homogenous landscape Digital database (Heights, Clutters, Vectors)

    Further Simulation

    homogeneous interference

    the propagation model simple propagation laws

    the actual traffic behavior

    regular hexagon pattern

    traffic growth expectation

    uniform traffic demand

    Simulation Tool Enterprise, etc

  • Outline Radio Dimensioning Procedure

    Radio Link Budget

    Capacity Dimensioning

    Appendix: Stochastic Knapsack: Blocking ProbabilityCampbells Dimensioning ProcessInterference Analysis

  • Stochastic Knapsack: Blocking Probability

    State Probability:: the traffic of service k: the connecting users of service k

  • Stochastic Knapsack: Blocking Probability

    Blocking Probabilities:: the blocking probability for service k: the blocked state for service kBk

  • Campbells TheoremVirtual LoadVirtual Traffic: the load of a single user for service j: busy hour traffic of a single user for service j

  • Campbells TheoremVirtual service channelsTotal Traffic: using Erlang B Formula

  • Campbells TheoremSupported Subscribers in the cell

  • Interference Analysis Uplink Interference Analysis

    Downlink Interference Analysis

  • Uplink Interference AnalysisIown interference caused by users of own cellIotherinterference caused by users of other cellsPN equivalent noise input of the receiver

  • Noise power of receiver: PN

    PN = 10lg(KTW) NF

    K: Boltzmann Constant= 1.3810-23 J/KT: temperature in degrees KelvinW: Bandwidth of signal3.84MHz for WCDMANF: Noise figure of receiverAnd 10lg(KTW) = -108dBm/3.84MHz NF = 3dB (typical value for Marco-cell) PN = 10lg(KTW) + NF = -105dBm/3.84MHzUplink Interference Analysis

  • Iown : Own-cell interference

    Interference should be overcome by each user: ITOT - PjPj : desired signal power from user j received by NodeBWith perfect power control:

    Pj can be estimated by

    Own-cell interference: totally received power from all users of own cell:Uplink Interference Analysis

  • Iother : Other-cell interference

    Difficult to analyze theoretically, and depends on user distribution, cell position, antenna patterns and so on

    Definition of i, the ratio of other-cell to own-cell interferenceUplink Interference Analysis

  • Define:The total interference can be estimated:Uplink Interference Analysis

  • Then: Defining uplink load factor:

    ITOT reaches infinity while load factor equals 1Uplink Interference Analysis

  • Noise Figure defined as follows:

    50% load 3dB60% load 4dB75% load 6dBUplink Interference Analysis

  • Interference AnalysisUplink Interference Analysis

    Downlink Interference Analysis

  • Iown: Interference from BS of own cellIother: Interference form BSs of other cellsPN: Equivalent noise input of the receiverDownlink Interference Analysis

  • Iown : Own-cell interference

    Individual channel distinguished by orthogonal OVSF code. The orthogonality between channels can be achieved in static propagation environment without multipath. Then there is no interference over each other in downlink.In multipath environment, not all paths of signal transmitted for a channel can be applied by RAKE and some energy adds to interference. It can be modeled by the introduction of orthogonal factor :

    in the formula above, PT is the total power transmitted by BS, including power of common channels and dedicated channels

    Downlink Interference Analysis

  • Iother : Other-cell interference

    Signals transmitted by BSs of other cells can cause interference over the target cell. Due to different scrambling codes, these signals are not orthogonal with those of the target cell.

    Assuming uniformly distributed service and equal powers transmitted by all BSs, if there are K of other cells and the path loss from Kth BS to user j is PLk,j, then:Downlink Interference Analysis

  • With perfect power control, there isThe required transmission power of DCH for user j isDownlink Interference Analysis

  • SinceTotal transmission power can be estimated as follows:Downlink Interference Analysis

  • PT can be resolved as follows: ij is the ratio of other-cell to own-cell interference for user j. and it is defined as follows:Downlink Interference Analysis

  • Downlink load factor

    defined in common as the ratio of total transmission power to maximal transmission power of the BS.

    The ratio of PCCH to PMAX is about 20%.

    Downlink Interference Analysis