QoS and QoE Management in UMTS Cellular Networks Part 6

6.Radio NetworkDimensioning andPlanningDr. David Soldani(david.soldani@, tel. +358.50.3633527)S-38.3215 Special Course on Networking Technology for Ph.D. students at TKKOutlineWCDMA radio dimensioning and planning Radio dimensioning aspects for UTRAN FDDA virtual time simulator for UTRAN FDDHSDPA dimensioning(E)GPRS dimensioningProcedure for CS and PS trafficDimensioning with capacity and bite guarantees Dimensioning with QoS guaranteesDimensioning aspects for UTRAN FDD3GPP leaves the engineering process, as planning and dimensioning aspects, to convert traffic demand into needed resources to vendors’and operators’choiceHence, due to the complexity of the system and related expenditures, any practical realization and deployment of new application services needs to be validated a priori by means of analytical approaches, or simulations, depending on the desired level of accuracyNone of the published analytical methods and tools showed enough flexibility for an efficient and effective WCDMA radio interface dimensioningWe propose plain methods for radio interface dimensioning an a simple tool, which supports models for packet and circuit switched services, and processes snapshots of the system status, upon which performance statistics are derivedThe proposed solution is used to analyze the deployment of PoC (Push to talk over Cellular)by means of several case studiesPMCompute total loading for GB servicesand do the admission control Compute probability of a user to be active, generate active users even based and map bearers intoservices Compute load budget for NGB services Allocate bit rates to NGB users, i.e. dopacket schedulingCollect statisticsCompute % of satisfied usersN Print offered and served traffic, throughput and % of satisfied usersN YScan inactive usersScan queueSort queue based onprioritiesScan queueAll iterationdone?% of satisfiedusers < thresholds?Increase number ofusers, the probability of a user to be active is held constantYStartSimulator structureInner loop: The new configuration of active users is repeated to approximate the desired result more closely Inner loop: The new configuration of active users is repeated toapproximate the desired result more closelyOuter loop: To derive the maximum load the cell can offer at a given QoS Outer loop: To derive themaximum load the cell canoffer at a given QoSACPSTGCall generatorSupported traffic modelsCS speech and video callsPS SWIS, PoC, streaming, MMS, WAP and dialup connectionsService (i ) based parametersQoS Profile: TC, THP, bit rates, ARP Mean service time (s): T i Mean arrival rate (s): A iShare of subscription (%): S iProbability P i for service i to be used is:Group factor for PoC in P i computationGeometric distributionMin =1, Max = 25, Mean =4Inner loop: Conditional probability for a user to make other callsOffered traffic in number of subscriptions N i is estimated as:U i = average number of active bearers carrying the service i100ii i i S A T P =iii iT A U N ⋅=RRM and load estimatesGB is blocked if either one of the following in-equation is satisfied:NGB traffic is always admitted, and bit rate allocated based onThe load estimates are based on the fractional load equationswhereOffsetL L L L t Targe GB NGB Total +>+=tyNBGBcapaci t GB GB L L L L −>Δ+Targe ()()Dl k k k k DLi v R WSHO +−+=αρη11)(GB NGB Target NGB L L L PB +−=TxMaxTxTotal k kDL Total P P L ==∑ηPerformance monitoringUser satisfaction criteriaGB services: Speech, video and SWIS calls are satisfied if they do not get blocked NGB services: PoC, streaming, MMS, Dialup and WAP users are satisfied if are not blocked and the average bit rate during the iterations (inner loop) is ≥to 8 (or 16),64, 32, 64 and 32 kb/s, respectivelyMethod 1 (maximum offered load):At a given traffic mix, the offered load is increased till at least one of the following conditions results true:Less than 70%of MMS or WAP users are satisfiedLess than 50%of dialup users are satisfiedLess than 90%of users of any of other services are satisfiedMethod 2 (impact of a new service on the existing subscribers satisfaction):The subscription level is increased gradually for the new service while keeping the input load of the other services constantParameterNumber of iterations (inner loop)Downlink Load target Overload offsetOrthogonality (α)Soft handover overhead (SHO )Other-to-own cell interference ratio (i )Chip rate (W )DL DCH bit ratesE b /N 0Activity (kb/s)(dB)Factor (ν)Speech - CS Conversational (GB)12.2170.67Video - CS Conversational (GB)64261SWIS - Streaming (GB)64361PoC - Interactive THP1 (NGB)0, 8, 16461Streaming - Interactive THP2 (NGB)0, 64570.6WAP/MMS - Interactive THP3 (NGB)0, 64, 128, 144, 256, 38465/5.51/0.6Dialup – Background (NGB)0, 64, 128, 144, 256, 38475.50.8Value 20%0.553.84 Mchip/sOffered services - Traffic class Priority 100070%10%0.5 (ITU Vehicular A)GBNGBOffered service Share ofSubscriptions(%)Mean servicetime(s)Mean arrival intensity(Hz)Speech (CS)100901/4800Video (CS)31201/24000 Streaming106001/(5*3600) MMS10101/(2*3600) SWIS (RTVS)31801/(2*3600) Dialup112001/(2*3600) WAP browsing206001/(4*3600)PoC Varies*601/(2*3600)* The volume is increased from 0 to 100%, whereas the average PoC group size is held constant: 1 user in Case 1 and Case 2, 4 users in Case 3 and Case 4.Case studies on PoC deployment Case 1Maximum allocated bit rate = 8 kb/sAverage PoC group size = 1 (one to one communication)Only different priorities are allocated to distinct servicesMethod 1Case 2Maximum allocated bit rate = 16 kb/sAll other settings as in Case 1Method 1Case 3PoC av. group size in the same cell = 4All other settings as in Case 2Method 1Case 4Method 2500 non-PoC users (held constant)All other settings as in Case 3Served PoC traffic as a function of PoC subscriptionsAverage PoC cell throughput < 50 kb/s≤7% of the total traffic in the cell1020304050600%8%20%40%60%80%100%PoC subscribersC e l l t h r o u g h p u t d u e t o P o C u s e r s (k b /s )123456780%8%20%40%60%80%100%PoC subscribersP o C t r a f f i c i n t h e c e l l (%)Impact of PoC traffic on other servicesInsignificant: Only 7% of the other services would be not satisfactory if all the end users subscribed to PoC20%00%8%40%60%80%100%PoC subscribersM a x . n u m b e r o f s u b s c r i p t i o n sSum of non-PoC subscriptionsPoC subscriptions909192939495969798991000%8%20%40%60%80%100%PoC subscribersV a r i a t i o n o f m a x . n . o f n o n -P o C s u b s c r i p t i o n s (%)Served PoC traffic as a function of PoC subscriptionsAverage PoC cell throughput < 90 kb/s≤13% of the total traffic in the cell1020304050607080901000%8%20%40%60%80%100%PoC subscribersC e l l t h r o u g h p u t d u e t o P o C u s e r s (k b /s )24681012140%8%20%40%60%80%100%PoC subscribersP o C t r a f f i c i n t h e c e l l (%)Impact of PoC traffic on other servicesMore significant than in Case 1: about 13% of the other services would be not satisfactory if all the end users subscribed to PoC100200300400500600700800900100011000%8%20%40%60%80%100%PoC subscribersM a x . n u m b e r o f s u b s c r i p t i o n sSum of non-PoC subscriptionsPoC subscriptions8586878889909192939495969798991000%8%20%40%60%80%100%PoC subscribersV a r i a t i o n o f m a x . n . o f n o n -P o C s u b s c r i p t i o n s (%)Served PoC traffic as a function of PoC subscriptionsAverage PoC cell throughput < 250 kb/s≤1/3 of the total traffic in the cell501001502002500%8%20%40%60%80%100%PoC subscribersC e l l t h r o u g h p u t d u e t o P o C u s e r s (k b /s )51015202530350%8%20%40%60%80%100%PoC subscribersP o C t r a f f i c i n t h e c e l l (%)Impact of PoC traffic on other servicesWorst case: Significant deterioration of the performance of other services if more than 20% of the end users subscribed to PoC10020030040050060070080090010001100PoC subscribersM a x . n u m b e r o f s u b s c r i p t i o n sSum of non-PoC subscriptionsPoC subscriptions4045505560657075808590951000%8%20%40%60%80%100%PoC subscribersV a r i a t i o n o f m a x . n . o f n o n -P o C s u b s c r i p t i o n s (%)Average cell throughput as a function of PoC subscriptionsAs expected, when the PoC traffic increases the NGB load decreases (PoC has higher priority), whereas the load due to GB services remains constant (PoC has no means to affect the AC of GB services)1002003004005006007000%8%20%40%60%80%100%PoC subscribers C e l l t h r o u g h p u t (k b /s )GBNGBPoCImpact of PoC traffic on other servicesSignificant deterioration of WAP performance if more than 50% of the end users subscribed to PoC: Extra capacity needed in the cell1020304050607080901000%8%20%40%60%80%100%PoC subscribersS a t i s f a c t i o n l e v e l (%)SpeechVideoRTVSPoCStreamingMMSDialupWAPVirtual time simulator for UTRAN FDDIn UMTS only a layered bearer service architecture and QoS attributes are defined: Implementation and planning aspects of the actual QoS management functions are left to vendors’and operators’choiceDue to the complexity of the system and infrastructure costs, any practical deployment of radio resources management (RRM) algorithms and offered services in UTRAN needs to bevalidated a priori by means of static or dynamic simulations,depending on the desired level of time resolution and accuracyWe present a virtual time simulator that overcomes the limitations(snap shot of the system status only) and complexity (far too high time resolution) of static and dynamic system level simulatorsSimulator structureModular structure with clear interfaces: Each module is implemented independently so that each entity may be straightforwardly replaced by an alternative solutionSupported functions: Traffic and path loss generators, Admission Control (AC), Load Control (LC), Packet Scheduler (PS), Power Control (PC), Process Calls (PrC) and Performance Monitoring (PM)Mobility effects and SHO gains:may be taken into account by e.g.speed dependent Eb/N0 requirements and SHO conditionDHO branches are processed first followed by the main branches, the bit rate assigned to the radio link set (UE) is the minimum of the bit ratesallocated separately (for each cell) to all radio links of the active setThe maximum resolution of the tool is one radio resource indication period (RRI), i.e. the time needed to receive the power levels from the basestationsTraffic & Path Generate calls/sessions, distribute UEs, allocate RRPs AllMeasure Downlink Total Load (Serve DHO branches followed by main If time spent in the queue > Compute performance Check sessions/calls to be released due to Do system PC and collect For each call take min allocated bit rate over the active set, Process Update buffer levels, All cells PCLoss GeneratorsPMPS & LC (HC)AC (HC)and sort them based on arrival times. Compute path losses, active sets and assign E b /N 0based on UE speed,SHO condition and service typecalls/sessions processed?P Total ) for eachcell and CPICH E c /N 0for each UEIf MaxQueueLength is exceeded, then reject main branches followed by DHO branches, collect accessibility and retainability statisticsbranches based on RRP and arrival time MaxQueuingTime , then reject the branch, if the main one is rejected thenblock call/session and collect statisticsIf P Total < P Target +Offset & P GB +ΔP GB <= P Target –P TxNGBcapacitythen admit the call/session and collect statisticsNYScan queueIf P Target -(P NGB +P GB ) > 0, or P Total >= P Target +Offset then schedule bit rates based on priorities and arrival times Scan queueindicators, e.g. % of satisfied users and spectral efficiencyoutage and collect retainability statistics Scan cellspower based statisticsif time spent in the queue > CRmaxQueuingTime , thenreject CR and collect statisticsCallsgenerate objects, release or move connections to Cell FACH and collect service integritystatisticsprocessed?YNIncrease virtual time:T i+1 = T i + RRISimulation flow chartTraffic modelsCall and session arrivals are generated following a Poisson process, and mapped onto the appropriate QoS profiles, depending on the carried type of trafficCircuit switched (CS) speech and video calls are held for an exponentially distributed service time, and their inter-arrival periods follow exactly the same type of distributionPacket switched services are implemented as an ON/OFF process with truncated distributionsAll calls/sessions (generated at the beginning of each simulation) are subsequently processed (played back) taking into account thecorresponding arrival times, service activities and priorities, hence the name virtual time simulatorPath loss generatorFor each mobile location, the received power levels from all cells are calculated first and then the cells satisfying the SHO conditions are assigned as activePath loss calculations: Imported from other tools or using formulas available in the literature, e.g. Okumura-Hata modelSupported RRM functionsAC, PS and LC with QoS differentiation See Chapter 5 or Lecture 4HCIncluded in PS and AC functionsTerminals not movingPCSystem basedDataFrom Cell_DCH to Cell_FACHDataInactivity Timer(service based)Reading Time (random)Release resourceT inCR(Ares implementation)Note:•FACH bit rate = 32 kb/s•No transmission allowed when the CR is sentTraffic Volume Pending TimeCR(Real implementation)Transmission interruptedCell FACH (e.g. 32 kb/s time division between bearers)Traffic Volume ThresholdTransmission disregardedStart measuring the ASTStart monitoring the UE buffer leveltProcess calls functionAll active calls in the system are processed at once each radio resource indication periodIf the ongoing connection is CS, the simulator collects its throughput, and releases the call in the case it lasted longer then the corresponding call duration periodFor packet switched connections, the ON/OFF state of each session is handled separately: Throughput is collected only if there is data to transmit, and inactive connections are moved to Cell FACH statePower control functionFor each connection during each RRI, we derive the transmission power to attain the required E b /N 0for sufficient quality, i.e.Multi-path fading and SHO effects are taken into account in the serviceE b /N 0requirementLn,i L m,i L n,i BS nBS mMS i,m∑∈+=)(,m I i mc i m m mp pP ()Mm m I i N LP L P R L Wp m i mn n i mi n nm i m i m m m i mi m i m mm ,...,1),(,/1//,,,,=∈ρ=++α−∑≠Symbol Explanation i m Index of a UE served by BS m m,n Indices of BSs I(m) Set of UE indices served by BS mMNumber of cells mi p BS transmitted power for UE i mP m , P n Total transmit power of BS m and BS n mi m L ,Pathloss from BS m to UE i m served by BS m m i n L , Pathloss from BS n to UE i m served by BS m m i RBit rate used by UE i m mi αOrthogonality factor for UE i mm i NNoise power (thermal plus equipment) of UE i m mi ρRequired E b /N 0 for UE i m?QoS and QoE monitoring functionPerformance monitoring% of satisfied users for each serviceSpectral efficiency for mixed service scenarioLink and cell based powers and E c/N0measurementsQoE performance indicators for each service Call block ratio (%)Call drop ratio (%)Capacity request rejection ration (%)Active session throughput (kb/s)Object transfer delay (s)UE buffer level for Streaming, SWIS, and PoC servicesResults available on the mapGains in terms of Spectral EfficiencyDifference between system loads (average cell throughput divided by the bandwidth) where 90% of users of the worse performing service are satisfiedLimit = 90%BS1BS2BS3Gain Traffic volume (kb/s/Hz)Spectral Efficiency % Satisfied usersGains in terms of % of satisfied usersCollect the % of satisfied users for each service: The more users that can be satisfied, at a given offered traffic volume, the more efficiently the spectrum is utilized by the operatorLimit = 90%BS1BS2BS3GainTraffic volume (kb/s)Offered traffic (“Held constant”)% Satisfied usersThe simulation was performed over a period of 2 hours using a time step of 200 ms (RRI period)The traffic mix and the traffic intensity were held constant , i.e. 2 call/session attempts per second. The corresponding offered traffic was about 750 users per cell over the all simulated timeDifferentiated parameter vales:QoS Profile ServiceBit RateRRP Min. All. Bit AC Max.Granted Min.Granted Min.Buffering Inactivity (kb/s)Rate (kb/s)Queuing DCH Alloc.DCH Alloc.Time Delay Timer Time (s)Time (s) in Overload (s)(s)(s)CS-conv.Speech 12.21GB 5-----Video 642GB 10-----PS-stream.SWIS 643GB 10--5--PS-int. THP1PoC 0, 8481515104604THP2Streaming 0, 645641*********THP3WAP/MMS 0, 16, 32, 64, 128, 144, 256, 3846321550.2-1010PS-backg.Dialup 0, 16, 32, 64, 128, 144, 256, 3847161510.2-55CR Max.QueuingTime (s)Most important system based parametersParameter ValueCall/session mean arrival rate 0.5 sRadio resource indication period (RRI) 0.2sSimulation time (s) 7200 sPower target for DL AC 3 dB below BTS total powerOverload offset for DL AC 1 dB above power targetOrthogonality (α) 0.5Period for load control actions 0.2 s (1 RRI)Period for Packet Scheduling 0.2 s (1 RRI)E b/N0 requirementsSpeechSWIS StreamingPoC MMS/WAPDialup 7 dB6 dB6 dB7 dB5/5.5 dB 5.5 dBMaximum BTS Tx power 43 dBmP-CPICH Tx power 33 dBmSum of all other CCH Tx powers 30 dBmLength of AC queue 10 Radio bearers Dedicated NGB capacity 0 dB, i.e. not used Power weight for inactive NGB traffic (k) 0.5Adopted traffic models and mixService Data rate(kb/s) Buffer size(s)Object size(kB)Off time(s)Session length(Objects)Mix(%)PoC 8 1 Exponential6 mean,0.5 min, 40 maxExponential60 mean,1 min, 1200 maxGeometric8 mean,1 min, 30 max18Streaming 64 8 Uniform160 min, 3200 max - 112MMS BestEffort - Exponential20 mean, 3 min, 200 max- 15Dialup BestEffort - Log-normal(μ=5, σ=1.8)0.1 min, 20000 maxPareto(k=2, α=1)2 min, 3600 maxInv. Gaussian(μ=3.8, λ=6)1 min, 50 max15SWIS 64 1 Exponential80 mean, 32 min, 2400 max - 110WAP BestEffort - Log-normal(μ=2, σ=1)0.1 min, 50 maxExponential20 mean,1 min, 600 maxGeometric3 mean,1 min, 50 max13Speech 12.3 - - - Exponential90 s20Video 64 - - - Exponential120 s 7Mapping of services onto QoS profilesRadio Resource Priority / Guaranteed Bit Rate valuesQoS Class RRP/BitRate Signalling9/3.4 kbps Emergency call1/12.2kbpsSpeech 2/12.2kbpsCS – Conversational T Data 3/64kbpsCS - Streaming NT DataQoS ClassARP=1 ARP=2 ARP=3PS - Conversational PS - Streaming 4 (SWIS)THP1 5 (PoC)THP2 6 (Streaming)PS - InteractiveTHP3 7(WAP+MMS)PS - Background8(Dialup)G BN G BNGB: Non Guarante ed Bit Rat eGB: Guara nteed Bit Rate Bearer servicesUser satisfaction: DefinitionSpeech calls and video calls (GB) The user does not get neither blockednor droppedSWIS (GB)The user does not get neither blockednor droppedNo re-buffering occur during the session PoC (NGB)The user does not get neither blockednor droppedNo re-buffering occur during the session Streaming (GB and NGB)The user does not get neither blockednor droppedNo re-buffering occur during the session Dialup (http, emails, ftp) (NGB)The user does not get neither blocked nordroppedActive session throughput >= 64 kb/sWAP (NGB)The user does not get neither blocked nordroppedActive session throughput >= 32 kb/sMMS (NGB)The user does not get neither blocked nordroppedActive session throughput >= 8 kb/sSimulated environmentHelsinki 19 cells: Terminals uniformly randomly distributed, but not on the waterBS1BS2BS3BS4BS5BS6BS7BS8BS9BS10BS11BS12BS13BS14BS15BS16BS17BS18BS19X-coordinate [m]Y -c o o r d i n a t e [m ]6.67426.67466.67506.67546.67586.6762x 1063.8453.8503.8553.8603.865x 105The status of Cell 11 is also investigated separately The status of Cell 11 is also investigated separately05012345678910111213141516171819Cell numberN u m b e r o f C a l l s /S e s s i o n sSpeechVideoStreamingMMSPoCSWISDialupWAPTraffic distribution: Offered load in call arrivalsThe offered load complies with the input traffic mix The offered loadcomplies with the input traffic mix05010015020025030035040012345678910111213141516171819Cell numberA v . C e l l T h r o u g h p u t (k b /s )SpeechVideoStreamingMMSPoCSWISDialupWAPTraffic distribution: Average cell throughputsThe served load reflects the input traffic mix and models The served load reflects the input traffic mix and models246810121460006100620063006400650066006700680069007000Simulation time (s)P o w e r (W )P TxTarget + OffsetP TxTargetP TxTotalSCP GBP NGBPBCell 11: Snapshot of the simulation periodPS, AC, LC, PC work as intended, and power estimates are sufficiently accurate PS, AC, LC, PC work as intended, and power estimates are sufficiently accurate24681012140102030405060708090100Power (W)(.) P TxLink(*) P GB (o) P NGB (+) P TxTotalP TxTarget +OffsetN o r m a l i z e d D i s t r i b u t i o n F u n c t i o n (%)P TxTargetCell 11: Power distribution functionsThe distributions comply with the input parameter values and load status in the cell Thedistributions comply with the input parameter values and load status in the cell010203040506070809010012345678910111213141516171819Cell numberS a t i s f i e d U s e r (%)SpeechVideoStreamingMMSPoCSWISDialupWAPService based indicators for each of the simulated cells: Percentage of satisfied usersThe % of satisfied users reflects exactly the provisioned discrimination between GB and NGB services The % ofsatisfied users reflects exactly theprovisioned discrimination between GB and NGB services05010015020025030035012345678910111213141516171819Cell number10t h P r c t i l e A c t i v e S e s s i o n T h r o u g h p u t (k b /s )SpeechVideoStreamingMMSPoCSWISDialupWAP10th percentile of the average active session throughput during the simulated timeThe monitored AST reflects exactly the NGB service differentiation The monitored AST reflects exactly the NGB service differentiation0.0010.0020.0030.0040.0050.0060.0070.0080.00024681012141618C a p a c i t y R e q u e s t R e j e c t i o n R a t i o (%)Cell numberStreamingMMSPoCDialupWAPCapacity request rejection ratioThe monitored CRRR reflects exactly the NGB service differentiation The monitored CRRR reflects exactly the NGB service differentiation0510152025303540455012345678910111213141516171819R e -B u f f e r i n g R a t i o (%)Cell number StreamingPoCSWISRe-buffering ratioThe re-buffering ratio is correctly higher for streaming The re-buffering ratio is correctly higher for streaming01234512345678910111213141516171819Cell number D e l a y B u f f e r i n g R a t i o (%)StreamingPoCSWISService based performance indicators: Too long time needed for re-buffering ratioThe tolerance of streaming users is higher than for PoC The tolerance of streaming users is higher than for PoC1010101010104102030405060708090100Object Transfer Delay (s)C u m u l a t i v e D i s t r i b u t i o n F u n c t i o n (%)(.-) MMS (-) WAP (--) DialupMMS, WAP and Dialup object transfer delays (system based statistics upon all simulated time)The measured metrics reflect exactly the calculated object delays from the median of AST and object size, hence PrC and PM functions work as intended The measured metrics reflect exactly the calculated object delays from themedian of AST and object size, hence PrC and PMfunctions work as intendedService CBR CDR CRRR RBR DBR Median Median Calculated SU type(%)(%)(%)(%)(%)AST Object Object(%)(kb/s)Size Delay(kB)(s)Speech0.050.00---12.2--99.95 Video0.160.00---64.0--99.84 Streaming0.000.00 1.93 6.350.0563.41682212.291.67 MMS0.000.00 2.29--70.515 1.797.55 PoC0.000.03 1.08 2.490.198.04 4.096.31 SWIS0.320.00-0.000.0064.08911.199.68 Dialup0.000.008.44--51.412018.759.94 WAP0.000.05 2.57--66.048 5.894.24 Note: RBR = Re-Buffering Ratio, DBR = Delay Buffering Ratio; SU = Satisfied UsersConsistent with the provisioned QoS for each of the deployed services Consistent with the provisioned QoS for eachof the deployed servicesDissatisfied users: (*)Dialup,(*) PoC, (*) WAP, (*)Streaming,(*) MMSBS1BS2BS3BS4BS5BS6BS7BS8BS9BS10BS11BS12BS13BS14BS15BS16BS17BS18BS19X-coordinate [m]Y -c o o r d i n a t e [m ]6.67426.67466.67506.67546.67586.67623.8453.8503.8553.8603.865x 105x 106HSDPA dimensioningDL radio dimensioning issue that arises from the introduction of HSDPA in an existing operating WCDMA networkDerives the maximum HSDPA throughput, or the HSDPA power, if the throughput is provided as an input, as a function of the actual cell load (due to dedicated and commonchannels), admission and congestion control thresholdsAlso,the results of this process can be used to find out whether resources already allocated for WCDMA aresufficient for a satisfactory HSDPA service, or it isnecessary to add new carriers or sitesEffects on coverage can be estimated using the proposed changes to the radio link power budget calculation。