Presentation on theme: "Capacity Management By DION"— Presentation transcript:
1 Capacity Management By DION Capacity ManagementBy DION1
2 3G RAN Capacity Management IntroductionEricsson’s RAN Capacity Management solution controls the load in the WCDMA cell. This enables the system to provide the requested Quality of Service (QoS) and coverage for individual connections.The Capacity Management solution consists of three main functions:Dedicated Monitored Resource HandlingAdmission ControlCongestion ControlEricsson ’s WCDMA RAN Capacity Management solution controls the load in the WCDMA cell.This makes it possible for the system to provide the requested QoS and coverage for individual connections. Each cell or group of cells has its own set of Capacity Management functions responsible for monitoring and controlling the resources of that cell.The Capacity Management solution consists of three main functions:- Dedicated Monitored Resource Handling- Admission Control- Congestion Control
3 Overview of Capacity Management 3G RAN Capacity ManagementOverview of Capacity ManagementThe main purpose of WCDMA RAN Capacity Management is to maximize air interface capacity and keep system stability, by handling a number of resources:PowerASEs (Air Speech Equivalent)Codes (DL)DL Channelization usageUplink interferenceThese critical resources are constantly monitored and controlled by Ericsson’s WCDMA RAN Capacity Management solution as shown here.
4 1. Dedicated Monitored Resource Handling 3G RAN Capacity Management1. Dedicated Monitored Resource HandlingUL/DL HWDL codeutilizationCompressed Mode& DL spreadingDL code tree utilization (SF for users and CCH’s)Provides info about # of connections with a certain SF. This adds information about DL channelization usage. Also measure # of connections in compressed mode # of serving HS-DSCH connections.ChannelizationCodes monitorHistogram monitorDL transmittedpowerAir interface Speech Equivalent (ASE)UL received total wideband power (RTWP)DL transmitted carrier power monitorDownlink transmitted power, which is affected by # of users, the type of connections and radio conditions in the cellASE monitorEstimates UL and DL air-interface usage per radio link.Total received UL power, i.e. information about UL interference.MeasuresRTWP monitorMonitorMonitors HW utilization in RBSHW monitorIt is important that the system can distribute the available critical resources among its users and avoid over-allocating resources when possible.Those monitored critical resources are called dedicated monitored resources. The following dedicated monitored resources are considered in the Capacity Management scope:Downlink channelization codes• Histogram monitor (number of radio links in compressed mode in a cell, downlink spreading factor usage, uplink spreading factor usage, number of simultaneous HS-serving radio links in a cell, number of serving cell E-DCH users and number of E-DCH users having the cell as a non-serving cell)• Downlink transmitted carrier power (total non-HS power used in the cell)• Air Interface Speech Equivalents (ASE) in uplink and downlink• Uplink Received Total Wideband Power (RTWP)• RBS hardware utilization in uplink and downlink (expressed in terms of channel elements)The Dedicated Monitored Resource Handling function collects and provides information about the current usage of resources that are critical to the load of the cell. This is done by performing measurements and keeping track of every radio link setup, addition, deletion, and modification in the cell.
5 Capacity limiting resources 3G RAN Capacity ManagementCapacity limiting resourcesA WCDMA RAN system has several different resources that are capacity limiting. Since each user is allocated some of these resources, the usage of these resources increases with the number of connections in the cell.Examples of such resources are :PowerAir Interface Speech Equivalents (ASE)Downlink channelization codesRBS Hardware (CE’s)Monitor counter pmNoReqDeniedAdm:Incremented when radio admits the connection, but some other resource is unavailable. This could be Iub, CE, or some other processing resourcepmNoReqDeniedAdm - Number of RAB establishment and RRC requests denied due to admission.The counter is increased if admission control function denies admission to any UE in this cell. The reason for denial can be power, code utilization limits, ASElimit, or compressed mode limit reached.
6 3G RAN Capacity Management 1. PowerA fundamental property of WCDMA is that coverage can be traded for capacity.DL Tx carrier power – is a resource which is shared among the common and dedicated channels.primaryCpichPower is reference for all channels in the system and is therefore controlling the cell sizeTrade-off:Increasing the CPICH power result in a decrease in capacityDecrease in the CPICH power result in an increase in capacityWhen it comes to consideration of WCDMA network capacity, TCP (Tx Carrier Power) always is an important resource .The available RBS downlink TCP is limited by the MCPA capability (20W, 30W, 40W). Multi Carrier Power AmplifierIt is important to monitor the amount of DL Tx Carrier Power in a cell. In fact, both Admission & Congestion Control monitor usage of non-HS Tx power.The downlink power is a sharable resource, so it is possible to increase or decrease the power allocated to the CPICH. The result of increasing the CPICH is a decrease in capacity while a decrease in the CPICH power will result in an increase in capacity.The cell coverage of a WCDMA system is very dependent on the cell load due to the cell breathing.In cells where capacity is the main concern it should be considered to reduce the pilot power to trade coverage for capacity.In extreme hotspot cases such as office parks, shopping centers, airports, ballparks, etc. it might be possible to sacrifice coverage for capacity gains of up to 10% but generally, it is not recommended to increase the CPICH to more than 8% of total available power.
7 DL Tx carrier power monitor 3G RAN Capacity ManagementDL Tx carrier power monitorThe purpose of the admission check on Tx carrier power is to prevent users from overbooking the RBS.beMarginDlPwr =10pwrAdm =75pwrAdmOffset =10To increase cell capacity it can be considered to increase pwrAdm:However:Congestion resolution actions start laterReduce headroom for HOLess power for HSDPAAdmission rejections due to excessive transmitted carrier power are relatively common, especially in large cells where UEs are distant from the RBS.To reduce blocking and increase cell capacity it can be considered to increase pwrAdm and thus allow admission attempts closer to the MCPA limit.The drawback with such a setting is that congestion resolution actions will start later, leading to an increased risk of exceeding the power capabilities of the MCPA.When this occurs, the code power for all channels (including common channels) is scaled down, which may lead to quality degradation for all connections in the cell.An increase of pwrAdm may also reduce the headroom for handover, which may lead to dropped calls.pwrAdm also affects the amount of power reserved for HSDPA. By increasing pwrAdm less power is reserved for HSDPA users.
8 Performance monitoring 3G RAN Capacity ManagementPerformance monitoringSome useful counters which can help monitor the DL power resources:pmTransmittedCarrierPower: To estimate the utilization of the MCPA with respect to the admission limit.pmNoFailedRabEstAttemptLackDlPwr: To detect admission rejects due to DL power.pmNoOfSwDownNgAdm: To detect soft congestion in the cell. Soft congestion is triggered either due to lack of transmitted carrier power, DL channelization codes or hardware.pmNoOfTermSpeechCong, pmNoOfTermCsCong: To monitor the number of users released due to congestion resolution actionpmNoSystemRabRelease: Dropped call counters can be used to detect quality problems due to overloading of MCPApmNoOfSwDownNgAdm - Number of downswitch requests for non-guaranteed and guaranteed-hs users served by this RNC switched down due to admission control.pmNoOfTermSpeechCong - Number of speech Radio Connections served by this RNC terminated due to congestion.
9 2. DL Channelization Code 3G RAN Capacity Management2. DL Channelization CodeThe monitoring of this resource is based on tracking the amount of the downlink code tree in use and to avoid users overbooking code resourcesbeMarginDlCode =5dlCodeAdm =80Reserving 20% of the code tree for handover legsDL code tree is considered as shared WCDMA resource. The purpose of the admission check of DL channelization codes is to prevent users from overbooking the code tree.The monitoring of this resource is based on tracking the amount of the downlink code tree in use and to avoid users overbooking code resources.To reserve codes for users in handover, there is code blocking for non-handover requests, while requests for handover are not blocked by the downlink channelization code admission policy.- The (Non-guaranteed, non-handover) admission requests can be granted when the resource usage exceeds the dlCodeAdm – beMarginDlCode level, soft-congestion can free up resources and physical resources are available. Otherwise they are blocked when the resource usage exceeds the dlCodeAdm - beMarginDlCode level.- (Guaranteed, non-handover) and (guaranteed-hs, non-handover) admission requests can be granted when the resource usage exceeds the dlCodeAdm level, soft-congestion can free up resources and physical resources are available. Otherwise they are blocked when the resource usage exceeds the dlCodeAdm level.If increasing dlCodeAdm, mobility problems may appear, so the system performance must be monitored closely.Changing dlCodeAdm and beMarginDlCode will further increase the code tree usage and still allow a margin for new soft handover legs. Monitor statistics to verify that the network admission behavior is as expected.
10 Performance monitoring Some useful counters which can help monitor the DL code resources:pmNoFailedRabEstAttemptLackDlChnlCode: To detect admission rejections due to DL channelization codespmNoOfSwDownNgAdm: To detect soft congestion in the cell. Soft congestion is triggered either due to lack of transmitted carrier power, DL channelization codes or hardwarepmNoSystemRabRelease: Dropped call counters can be used to detect quality problems due to overloading of DL channelization code tree.
11 3G RAN Capacity Management 3. RBS HardwareThe available RBS hardware is a limited resource due to, for example, the amount of installed hardware or licensing restrictions.The total number of capacity credits available in the RBS, is the minimum of the amount installed hardware and the amount activated by the software license key.Channel Element (CE) is the required baseband processing capacity and hardware for one speech bearer (AMR12.2 kbps) connection.Ericsson’s definition of a Channel Element is linked to Dedicated Channel (DCH) resources of the RBS. Processing capacity required for common signaling channels and certain radio network functionality is NOT included in the definition of a Channel ElementThe available RBS hardware is a limited resource due to, for example, the amount of installed hardware or licensing restrictions.The total available amount of capacity credits in an RBS depends on the amount of hardware installed in the RBS (expressed in Channel Elements) and/or the licensed amount of RBS capacity.In general, a Channel Element (CE) is the required baseband processing capacity and hardware for one speech bearer (AMR12.2 kbps) connection. The mapping of the CE-definition to the speech bearer has been done to facilitate easy capacity comparison with today’s GSM system, which use a similar user data speed on the speech connectionEricsson’s definition of a Channel Element is linked to Dedicated Channel (DCH) resources of the RBS, i.e. only to the resources required for user data handling for the different RAB types. This definition includes both dedicated data channels and dedicated signaling channels. Processing capacity required for common signaling channels and certain radio network functionality is NOT included in the definition of a Channel Element
12 3G RAN Capacity Management RBS HardwareNormalization of 1 CE:Downlink (DL): One AMR12.2 kbps with SF=128Uplink (UL): One AMR 12.2 kbps with SF=64User data (UL/DL)CE required (UL)CE required (DL)16 kbps/Voice164 kbps42128 kbps8384 kbps1664/128 kbps64/384 kbps128/384 kbpsMapping of the CE-definition to the speech bearer has been done to facilitate easy capacity comparison with today’s GSM system, which use a similar user data speed on the speech connectionDisplayed is the channel element usage per RAB type for UL / DL.When talking about DCH/HS it is worth to remember that PS64/HS consumes 4 UL CE and PS384/HS consumes 16 UL CEChannel element usage per RAB type
13 Performance monitoring Some useful counters which can help monitor the CE resources:pmNoFailedRabEstAttemptLackDlHw: Number of failed RAB establishment attempts due to lack of DL hardware resourcespmNoFailedRabEstAttemptLacUllHw: Number of failed RAB establishment attempts due to lack of UL hardware resourcespmNoFailedRabEstAttemptLackDlHwBest: Number of failed RAB establishment attempts due to lack of DL hardware resources, for the best cell in active setpmNoFailedRabEstAttemptLackUlHwBest: Number of failed RAB establishment attempts due to lack of UL hardware resources, for the best cell in active setpmUlCredits: Total consumed RBS UL creditspmDlCredits: Total consumed RBS DL credits
14 Performance monitoring 3G RAN Capacity ManagementPerformance monitoringCE shortage:Characterised by poor accessibility for all RAB types (usually during busy hour), and equally across all sectors.High count of pmFailedAfterAdmAlarms:UplinkBaseBandPool_UlHwUsageExceedsUlLicenseLevelDownlinkBaseBandPool_DlHwUsageExceedsDlLicenseLevelMonitor CE usage and determine consistent CE utilization above 60%.It is possible to identify sites which suffer from a lack of CE’s by:monitoring accessibility rates for all RAB types. An increased amount of call setup blocking may indicate a need to increase the RBS hardware capacity.Monitoring pmFailedAfterAdm - Incremented when radio admits the connection, but some other resource is unavailableAlarms in OSS – UL/DL Hardware Usage Exceeds license level
15 Capacity ManagementNODE B CAPACITYEach cell has limited resources that have to be shared among the users:- Downlink Power- Codes- Hardware processing resources.To manage the utilization of those resources a capacity management is performed: accept/refuse new call attempts, monitoring resources utilization and detecting/resolving overload situations of those critical resources
16 3G RAN Capacity Management 2. ASEEstimates the air interface resources usage in a cell (both in uplink and downlink)The ASE of a RL is expressed in the equivalent # of speech RBs which generate the same amount of air interface load.The ASE Monitor algorithm monitors ASE usage at cell carrier level in both uplink and downlink.This monitor accounts for the air interface resources usage in a cell (separately for the uplink and downlink), by means of an average static load estimation of the contribution of each radio link in the cell.The ASE of a single radio link depends on the radio connection type and is expressed in terms of the equivalent number of speech radio bearers that generate the same amount of air interface load.Using this definition, a radio link which has, for example, an ASE of three in downlink is expected to generate as much interference in downlink as three speech radio bearers in the cell.The number of ASEs for a radio link per cell in uplink is divided by the number of radio links within the RNC. The principle is that the average uplink interference created by a UE in the respective cell is proportional to the number of cells to which it is connected.
17 3G RAN Capacity Management DL ASEPurpose: to avoid running the system close to the downlink pole capacity and thereby prevent power rushes on the DL.Recommended to disable DL ASE admission control and rely on Tx Carrier Power as it is a better measure of the DL air interface load.Disabling aseDlAdm will decrease the risk for unnecessary admission denials and allow for increased capacity.The purpose of the admission control based on DL ASEs is to avoid running the system close to the downlink pole capacity and thereby prevent power rushes on the downlink.To increase the utilization of the air interface and avoid unnecessary blocking it is recommended to disable the DL ASE admission control and to rely on the admission control based on transmitted carrier power. Transmitted carrier power is a better measure of the downlink air interface load, reflecting the activity and radio conditions for the connections in the cell.The recommendation is to disable DL ASE admission control by setting aseDlAdm = 500. This will decrease the risk for unnecessary admission denials and allow for increased capacity.
18 Performance Monitoring Some useful counters which can help monitor the DL ASE resources:pmSumOfSampAseDl: To estimate how close a cell is to the DL ASE admission limitpmNoFailedRabEstAttemptLackDlAse: To identify cells in which admission rejections due to DL ASEs occurpmFailedDchChSwitch: To detect failed channel switches. This may be an indication of DL ASE shortage
19 3G RAN Capacity Management UL ASEPurpose: to avoid excessive UL load which could lead to inferior coverage and UE power rushes.Increasing aseUlAdm can result in increased capacity. However, should be monitored closely as UL ASE is the only mechanism available for preventing excessive UL noise rise.The purpose of the admission control based on UL ASEs is to avoid excessive UL load which could lead to inferior coverage and UE power rushes.Similar to the DL ASE, the UL ASEs is a rather blunt measure of the air interface load.The UL capacity can be increased by increasing aseUlAdm. This can be done for instance in order to allow for an increased number of simultaneous 384/HS connections. When increasing aseUlAdm, UL performance should be monitored closely since the UL ASE admission control is the only mechanism available for preventing excessive UL noise rise and UE power rushes.
20 Performance monitoring Some useful counters which can help monitor the UL ASE resources:pmSumOfSampAseUl: To estimate how close a cell is to the UL ASE admission limitpmNoFailedRabEstAttemptLackUlAse: To identify cells in which admission rejects due to UL ASEs occurpmAverageRssi: To detect excessive noise rise as a result of an increase of aseUlAdmpmTotNoRrcConnectReqSucc: To detect uplink coverage problems
21 ACTION TO IMPROVE THE CAPACITY Capacity ManagementACTION TO IMPROVE THE CAPACITYImmediate actions to improve the network performance• Main Objective: AccessibilityIf actions done in only worst cells inaccessibility will improve:If actions done in all cells inaccessibility will improve• Second objectives: Retainability and End User ExperienceSeveral Drop Calls are related with unavailability to add a new cellEnd User Experience is also affected due to congestion:Low Speech QualityLow user Throughput• Main blocking reason are analyzed:Downlink CodesDownlink PowerNew processing Hardware needed (Uplink/Downlink Hardware)Transmission CapacityNew site / Carrier / Sector
25 RADIO + BASEBAND CONFIG Capacity ManagementRADIO + BASEBAND CONFIGIn picture show below, radio + baseband configuration diagram for carrier reservation if Dual carrier implement in 1 sitesImproving capacity by adding/Swap RU to higher Power to increase headroom and adding txboard to improve CE DL/UL if any congestion detected before or for traffic forecast
26 3rd carrier (RADIO+BASEBAND CONFIG) Capacity Management3rd carrier (RADIO+BASEBAND CONFIG)If only 1 RU/Sector apply for 3rd carrier, the total RU power will be divided into one third for each carrier.How is 2xRU installed in 1 Sector? For this config, need license FAJ Pre Coder Balancing which will divided total dual RU power into one third of all power