Security Level: LTE Capacity Monitoring HUAWEI TECHNOLOGIES CO., LTD. LTE Capacity Monitoring Summary Monitoring Principle Resource block utilization Measurement Formula DL RB Utilization L.ChMeas.PRB.DL.Used.Avg/L.ChM eas.PRB.DL.Availx100% DL User throughput L.Thrp.bits.DL/L.Thrp.Time.DL/1000 UL RB Utilization L.ChMeas.PRB.UL.Used.Avg/L.ChM eas.PRB.UL.Availx100% UL User throughput L.Thrp.bits.UL/L.Thrp.Time.UL/1000 RRC connected users per cell (BBU board specification) Synchronized User Utilization Preamble usage for random access Control channel element for PDCCH L.Traffic.User.Avg/1200*100% (Max num user handled in a cell for LBBPd is 1200) Monitoring Impact Threshold DL RB Utilization User may failed in >70% & admission or poor user DL User Throughput experience < 2Mbps UL RB Utilization User may failed in >70% & admission or poor user UL User Throughput experience < 512kbps 60% Random Preamble Utilization (L.RA.GrpA.Att+L.RA.GrpB.Att) /3600/N* 100% (N is a value from product design in considering probability of preamble conflict, N is 50.) 75% Dedicated Preamble Utilization L.RA.Dedicate.Att/3600/100*100% 75% CCE Utilization (L.ChMeas.CCE.CommUsed + L.ChMeas.CCE.ULUsed + L.ChMeas.CCE.DLUsed)/L.ChMeas. CCE.Avail 70% HUAWEI TECHNOLOGIES CO., LTD. Poor user experience Proposed solution 1. Add eNodeB 2. Bandwidth expansion 1. Add eNodeB 2. Bandwidth expansion 1. Reduce UE inactivity timer in eNodeB (MOD RRCCONNSTATETIMER). Please note that load in CPU will increase if timer value reduce. 2. Physical tuning by balancing the target serving area for all cells 3. Add cell 1. Enable resource adjustment algo (MOD CELLALGOSWITCH: LocalCellId=xx, RachAlgoSwitch=RachAdjSwitch-1;) Access delayed or failure 2. Enable adaptive backoff function to allow UE retransmit preamble after failure (MOD CELLALGOSWITCH: LocalCellID=xx, RachAlgoSwitch=BackOffSwitch-1;) 1. Enable resource adjustment algo & reuse dedicated preamble Access delayed or failure (MOD CELLALGOSWITCH: LocalCellId=xx, RachAlgoSwitch=RachAdjSwitch-1, RachAlgoSwitch=MakeIdxSwitch;) 1. Add cell Scheduling delayed or poor user experience Page 2 LTE Capacity Monitoring Summary Monitoring Measurement Principle Maximum allowed connected users RRC Connected User per eNodeB Utilization Traffic volume utilization per eNodeB Traffic Volume Utilization Paging message processing capability (eNodeB Paging Utilization specification) Formula Sum (L.Traffic.User.Avg of all cells)/Licensed RRC connected users*100% Sum of (L.Thrp.bits.UL + L.Thrp.bits.DL) all cells / (Traffic License*3600) /(1000*1000)*100% Sum of (L.Paging.S1.Rx) all cells /3600/750 *100% Monitoring Threshold 60% 80% 60% Baseband board Main Control Board Usage VS.BBUBoard.CPULoad.Mean processing capability % of Main Control Board VS.Board.CPULoad.Cumulative Usage exceeed threshold HighloadCount/(3600/5)*100% 60% UL Transmission Utilization VS.FEGE.TxMeanSpeed/Allocat ed bandwidth x 100% 1. Increase license RRC (if CPU board usage <60%) 2. Add eNB (if CPU board usage >60%) Poor user experience 1. Reduce num cells in tracking area list 2. Paging policy (core network) optimization 60% VS.FEGE.RxMeanSpeed/Allocat ed bandwidth x 100% User may failed in admission or poor user experience Proposed solution 1. Increase Traffic volume license Main control board Main Control Board Usage VS.BBUBoard.CPULoad.Mean processing capability % of Main Control Board VS.Board.CPULoad.Cumulative Usage exceeed threshold HighloadCount/(3600/5)*100% Transmission rate DL Transmission at Ethernet port Utilization Impact Poor user experience Poor user experience 5% Poor user experience 5% 1. Physical tuning to achieve load balancing between neighbour (if neighbour is lightly loaded) 2. Change UMPT board (if LMPT is used) 3. Add eNB 1. Add LBBP to share load 2. Move cells or add cells based on num of UEs 3. If already reached 6 LBBPs, add eNB 1. Transmission capacity expansion 70% Poor user experience HUAWEI TECHNOLOGIES CO., LTD. 70% Page 3 ERAN Resource eNodeB Connected user license Traffic Volume License Paging Resource Main-controlboard CPU LBBP CPU cell Physical resource block HUAWEI TECHNOLOGIES CO., LTD. Synchronized user capacity PRACH resource PDCCH resource Page 4 Transport resource group Ethernet port eNode B Resource Resource Meaning Connected user license The connected user license specifies the maximum permissible number of users in RRC_CONNECTED mode. Each connected user consumes radio, device, and transport resources. If there are too many connected users, they cannot be well served by the eNodeB and new services cannot be admitted. Counter L.Traffic.User.Avg : indicates the average number of connected users in a cell. SUM (L.Traffic.User.Avg) indicates the sum of the average number of connected users in all cells in an eNodeB The licensed number of connected users under an eNodeB can be queried by running the following command: DSP LICENSE: FUNCTIONTYPE=eNodeB; In the command output, the value of LLT1ACTU01 in the Allocated column is the licensed number of connected users Monitoring Method Connected user license usage = SUM (L.Traffic.User.Avg)/Licensed number of connected users x 100% Threshold Impact 60% New services cannot be admitted, and experience of admitted users is affected. SW/HW Solution SW If the main-control-board CPU usage is less than 60%, increase the licensed limit. If the main-control-board CPU usage reaches or exceeds 60%, add an eNodeB. HUAWEI TECHNOLOGIES CO., LTD. Page 5 eNode B Resource Resource Meaning Counter Traffic volume license When the traffic volume of an eNodeB reaches or exceeds the licensed volume, the eNodeB performs flow control, which affects user experience and customer income. L.Thrp.bits.UL & L.Thrp.bits.DL: indicate the uplink traffic volume and downlink traffic volume of a cell, respectively. Σ(L.Thrp.bits.UL+L.Thrp.bits.DL) indicates the sum of uplink and downlink traffic volume of all cells under an eNodeB The licensed eNodeB traffic volume can be queried by running the following command: DSP LICENSE: FUNCTIONTYPE=eNodeB; The licensed eNodeB traffic volume is equal to the Allocated parameter value in the record whose License Identifier is LLT1THRUL01. Monitoring Method Threshold Impact SW/HW Solution Traffic volume license usage of an eNodeB = Σ(L.Thrp.bits.UL+L.Thrp.bits.DL)/(Licensed eNodeB traffic volume x 3600) x 100% 80% User experience and customer income are affected. SW Increase the licensed traffic volume. HUAWEI TECHNOLOGIES CO., LTD. Page 6 eNode B Resource Resource Meaning Paging Resource The eNodeB and BTS3202E or BTS3203E LTE can process a maximum of 750 and 500 paging messages per second, respectively. If the number of paging messages exceeds that capacity, paging messages sent from the eNodeB to UEs may be discarded, which leads to a decrease in the call completion rate. Counter L.Paging.S1.Rx :indicates the number of paging messages received over the S1 interface L.Paging.Dis.Num : indicates the number of paging messages discarded over the Uu interface Monitoring Method Percentage of paging messages received over the S1 interface = L.Paging.S1.Rx/3600/Maximum number of paging messages that can be processed per second x 100% Threshold Percentage of paging messages received over the S1>60% (or) L.Pagind.Dis.Num >1500 Impact SW/HW Solution Paging messages may be lost, affecting user experience. SW Decrease the number of cells in the tracking area list (TAL) that the congested cell belongs to. Adjust the paging policy of the core network to reduce signaling overhead. If the core network is provided by Huawei, enable the precise paging function. HUAWEI TECHNOLOGIES CO., LTD. Page 7 eNode B Resource Resource Meaning Main-control-board CPU The CPU usage reflects the busy level of the eNodeB. If the main-control-board CPUs are busy processing control plane or user plane data, signaling-related KPIs may deteriorate, and users may experience a low access success rate, low E-RAB setup success rate, or high service drop rate. Counter VS.Board.CPUload.Mean : indicates the average main-control-board CPU usage VS.Board.CPULoad.CumulativeHighloadCount : indicates the number of times that the main-control-board CPU usage reaches or exceeds a preconfigured threshold. Monitoring Method Percentage of times that the main-control-board CPU usage reaches or exceeds a preconfigured threshold (85%) = VS.Board.CPULoad.CumulativeHighloadCount/(3600/5) x 100% Threshold Percentage of times that the main-control-board CPU usage reaches or exceeds a preconfigured threshold (85%) >5% (or) VS.Board.CPUload.Mean >60% Impact SW/HW Solution KPIs deteriorate. HW If a neighboring eNodeB is lightly loaded, adjust the antenna downtilt angles or decrease the transmit power of the local eNodeB to shrink the coverage area and reduce the CPU load of the local eNodeB. In addition, expand the coverage area of the neighboring eNodeB for load balancing. If the main control board is an LMPT, replace it with a UMPT. Add eNodeBs. HUAWEI TECHNOLOGIES CO., LTD. Page 8 eNode B Resource Resource Meaning LBBP CPU If the eNodeB receives too much traffic volume, which is expressed either in bit/s or packet/s, the LBBP CPU responsible for user plane processing is heavily loaded. As a result, the eNodeB has a low RRC connection setup success rate, low E-RAB setup success rate, low handover success rate, and high service drop rate. Counter VS.Board.CPUload.Mean : indicates the average LBBP CPU usage VS.Board.CPULoad.CumulativeHighloadCount : indicates the number of times that the LBBP CPU usage reaches or exceeds a preconfigured threshold. Monitoring Method Percentage of times that the LBBP CPU usage reaches or exceeds a preconfigured threshold (85%) = VS.Board.CPULoad.CumulativeHighloadCount/(3600/5) x 100% Threshold Percentage of times that theLBBP CPU usage reaches or exceeds a preconfigured threshold (85%) >5% (or) VS.Board.CPUload.Mean >60% Impact SW/HW KPIs deteriorate. HW HUAWEI TECHNOLOGIES CO., LTD. Page 9 eNode B Resource Solution If the LBBP is an LBBPc, replace the LBBPc with an LBBPd Add an LBBP to share the network load, and then determine whether to move existing cells or add new cells based on the number of UEs. The capacity expansion methods are as follows: − If the radio resources are sufficient (that is, the usage of each type of radio resources is lower than the threshold), move cells from the existing LBBP to the new LBBP. - If the radio resources are insufficient, set up new cells on the new LBBP If the eNodeB has multiple LBBPs and one of them is overloaded, move cells from the overloaded LBBP to an LBBP with a lighter load. LBBP load can be indicated by the following: − Average CPU usage − Percentage of times that the CPU usage reaches or exceeds a preconfigured threshold − Number of cells established on an LBBP If the eNodeB already has a maximum of six LBBPs and more LBBPs are required, add an eNodeB. HUAWEI TECHNOLOGIES CO., LTD. Page 10 eNode B Resource Resource Meaning Transport Resource Group A transport resource group carries a set of data streams, which can be local data or forwarded data. Local data is classified into control plane, user plane, operation and maintenance (OM), and IP clock data. Forwarded data is not divided into different types. If a transport resource group is congested, it cannot transmit or forward data, which affects service provision. A transport resource group for user plane data is a monitored object. Counter VS.RscGroup.TxMeanSpeed : indicates the average transmission rate of a transport resource group VS.RscGroup.TxMaxSpeed indicates the maximum transmission rate of a transport resource group The bandwidth configured for a transport resource group can be queried by running the following command: DSP RSCGRP: CN=x, SRN=x, SN=x, BEAR=xx, SBT=xxxx, PT=xxx; In the command output, the value of Tx Bandwidth is the bandwidth configured for the transport resource group. Monitoring Method Threshold Impact SW/HW Solution Proportion of the average transmission rate to the configured bandwidth = VS.RscGroup.TxMeanSpeed/Bandwidth configured for the transport resource group x 100% Proportion of the maximum transmission rate to the configured bandwidth = VS.RscGroup.TxMaxSpeed/Bandwidth configured for the transport resource group x 100% Mean > 80 in 5days a week, Max >90 in 2 days a week Packets may be lost, affecting user experience. SW When a transport resource group is congested, you are advised to expand the bandwidth of the transport resource group HUAWEI TECHNOLOGIES CO., LTD. Page 11 eNode B Resource Resource Meaning Ethernet port The Ethernet port traffic is the channel traffic at the physical layer, including uplink and downlink traffic. The eNodeB Ethernet port traffic reflects the throughput and communication quality of the Ethernet ports on the main control board of the eNodeB. Based on the monitoring results, you can determine whether the transmission capacity allocated by an operator for the S1 and X2 interfaces on the eNodeB meet the requirements for uplink and downlink transmissions. Counter VS.FEGE.TxMeanSpeed : indicates the average transmission rate of an Ethernet port VS.FEGE.TxMaxSpeed indicates the maximum transmission rate of an Ethernet port VS.FEGE.RxMeanSpeed indicates the average reception rate of an Ethernet port VS.FEGE.RxMaxSpeed indicates the maximum reception rate of an Ethernet port. Monitoring Method Proportion of the average uplink transmission rate to the allocated bandwidth = VS.FEGE.TxMeanSpeed/Allocated bandwidth x 100% Proportion of the maximum uplink transmission rate to the allocated bandwidth = VS.FEGE.TxMaxSpeed/Allocated bandwidth x 100% Proportion of the average downlink reception rate to the allocated bandwidth = VS.FEGE.RxMeanSpeed/Allocated bandwidth x 100% Proportion of the maximum downlink reception rate to the allocated bandwidth = VS.FEGE.RxMaxSpeed/Allocated bandwidth x 100% Threshold Impact SW/HW Solution Proportion of average transmission rate to allocated bandwidth ≥ 70% or Proportion of max transmission rate to allocated bandwidth ≥ 85% Packets may be lost, affecting user experience. SW Expand the eNodeB transmission capacity. HUAWEI TECHNOLOGIES CO., LTD. Page 12 ERAN Resource eNodeB Connected user license Traffic Volume License Paging Resource Main-controlboard CPU LBBP CPU cell Physical resource block HUAWEI TECHNOLOGIES CO., LTD. Synchronized user capacity PRACH resource PDCCH resource Page 13 Transport resource group Ethernet port Cell Resource Resource Meaning Physical Resource Block (PRB) Growing traffic leads to a continuous increase in PRB usage. When the PRB usage approaches to 100%, user-perceived rates will decrease. As downlink is a major concern in an LTE network, this document describes only how to monitor downlink user perception. Counter L.ChMeas.PRB.DL.Used.Avg : indicates the average number of used downlink PRBs L.ChMeas.PRB.DL.Avail : indicates the number of available downlink PRBs L.Thrp.bits.DL : indicates the total throughput of downlink data transmitted at the PDCP layer in a cell. L.Thrp.Time.DL indicates the duration for transmitting downlink data at the PDCP layer in a cell Monitoring Method Downlink PRB usage = L.ChMeas.PRB.DL.Used.Avg/L.ChMeas.PRB.DL.Avail x 100% Downlink user-perceived rate (Mbit/s) = L.Thrp.bits.DL/L.Thrp.Time.DL/1000 Threshold Downlink PRB usage ≥ 70% Downlink user-perceived rate < a user-defined threshold (default value: 2 Mbit/s) Impact Users may fail to be admitted, and experience of admitted users is affected. SW/HW Solution SW If the cell spectral efficiency is low, you are advised to increase the cell throughput by optimizing RF performance If the cell spectral efficiency is high, you are advised to: − Add carriers or expand the bandwidth of the existing carrier. − Add eNodeBs. HUAWEI TECHNOLOGIES CO., LTD. Page 14 Cell Resource Resource Meaning Synchronized user capacity When the number of synchronized users in a cell reaches or exceeds a preconfigured threshold, cell KPIs deteriorate. Connected users include synchronized users and users in the out-of-synchronization state. Synchronized users consume air interface resources and the number of synchronized users is approximately equal to the number of connected users by default. Therefore, the number of connected users (instead of synchronized users) is monitored. Counter L.Traffic.User.Avg indicates the average number of connected users in a cell. Monitoring Method Synchronized user capacity usage of a cell = L.Traffic.User.Avg/Maximum number of synchronized users in a cell x 100% Threshold Impact SW/HW Solution 60% User experience is affected. HW Reduce the UE inactivity timer length by running the MOD RRCCONNSTATETIMER command with the UeInactiveTimer parameter specified. This measure lifts signaling overhead and increases CPU usage. If a neighboring cell is lightly loaded, adjust the antenna downtilt angle or decrease the transmit power of the local cell to shrink the coverage area and reduce the number of users in the local cell. In addition, expand the coverage area of the neighboring cell for load balancing. Add cells or expand the cell bandwidth. Split the local cell into multiple cells. HUAWEI TECHNOLOGIES CO., LTD. Page 15 Cell Resource Resource Meaning Physical random access channel (PRACH) resource The PRACH transmits preambles during random access procedures. If the number of contention-based random access attempts in a second reaches or exceeds N, the preamble conflict probability and access delay increase. The values of N are determined during preamble design, considering factors such as that the preamble conflict probability should be less than 1%. If more than 100 non-contention-based random access attempts are initiated per second, dedicated preambles will become insufficient and the eNodeB will instruct the UE to initiate contention-based random access instead, increasing the access delay for the UE. In handover scenarios, the handover procedure is prolonged. Counter L.RA.GrpA.Att indicates the number of times that random preambles in group A are received. L.RA.GrpB.Att indicates the number of times that random preambles in group B are received. L.RA.Dedicate.Att indicates the number of times that dedicated preambles are received Monitoring Method Random preamble usage = (L.RA.GrpA.Att + L.RA.GrpB.Att)/3600/N x 100% Dedicated preamble usage = L.RA.Dedicate.Att/3600/100 x 100% Threshold Usage of preambles for contention-based access ≥ 75% Impact SW/HW Solution Access delays are prolonged, or even access attempts fail. SW - If the random preamble usage reaches or exceeds 75% for X days (three days by default) in a week, enable the adaptive backoff function. If the system bandwidth is 5 MHz or 10 MHz, it is good practice to enable the PRACH resource adjustment algorithm - If the dedicated preamble usage reaches or exceeds 75% for X days (three days by default) in a week, enable the PRACH resource adjustment algorithm and reuse of dedicated preambles HUAWEI TECHNOLOGIES CO., LTD. Page 16 Cell Resource Resource Meaning PDCCH Resource Usage This capacity indicator measures the number of control channel elements (CCEs) that can be used by the PDCCH. In each radio frame, CCEs must be allocated to uplink and downlink UEs to be scheduled and common control signaling. PDCCH CCEs must be properly configured and allocated to minimize downlink control overheads as well as to ensure satisfactory user-plane throughput. Counter L.ChMeas.CCE.CommUsed indicates the number of PDCCH CCEs used for common signaling. L.ChMeas.CCE.ULUsed indicates the number of PDCCH CCEs used for uplink scheduling. L.ChMeas.CCE.DLUsed indicates the number of PDCCH CCEs used for downlink scheduling. L.ChMeas.CCE.Avail indicates the number of available PDCCH CCEs. Monitoring Method CCE usage = (L.ChMeas.CCE.CommUsed + L.ChMeas.CCE.ULUsed + L.ChMeas.CCE.DLUsed)/3600/1000/Max number of PDCCH CCEs x 100% Threshold Impact 80% - If PDCCH symbols are insufficient, CCEs may fail to be allocated to UEs to be scheduled, which will result in a long service delay and unsatisfactory user experience. - If PDCCH symbols are excessive, which indicates that the usage of PDCCH CCEs is low, the resources that can be used by the PDSCH decreases. This will also result in low spectral efficiency. SW/HW Solution SW If the PDCCH Symbol Number Adjust Switch parameter value is Off, you are advised to set this parameter to On If the PDCCH Symbol Number Adjust Switch parameter value is set to On and the uplink or downlink PRB usage reaches or exceeds 70%, you are advised to take one of the following measures: - Add cells or split existing cells. − Optimize RF performance to reduce the interference to PDCCH from neighboring cells. HUAWEI TECHNOLOGIES CO., LTD. Page 17 References - LBBP Antenna Config Board Signalling Antenna Configuration LBBPc 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 3x20 MHz 1T1R 20 MHz 3x20 MHz 1T2R 3x10 MHz 4T4R 3 3x20 MHz 2T2R 1x20 MHz 4T4R LBBPd1 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 3x20 MHz 1T1R 20 MHz 3x20 MHz 1T2R 3 3x20 MHz 2T2R LBBPd2 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 3x20 MHz 1T1R 20 MHz 3x20 MHz 1T2R 3 3x20 MHz 2T2R 3x20 MHz 4T4R LBBPd3 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 6x20 MHz 1T1R 20 MHz 6x20 MHz 1T2R 6 a 6x20 MHz 2T2R a: When a CPRI fiber optic cable is longer than 40 km (24.85 mi), the LBBPd3 board cannot support the 6x20 MHz 2T2R channel. Number of Cells Throughput Board LBBPc LBBPd1 LBBPd2 LBBPd3 LBBPd4 Maximum Throughput Downlink: 300 Mbit/s Uplink: 100 Mbit/s Downlink: 450 Mbit/s Uplink: 225 Mbit/s Downlink: 600 Mbit/s Uplink: 225 Mbit/s Downlink: 600 Mbit/s Uplink: 300 Mbit/s Downlink: 600 Mbit/s Uplink: 225 Mbit/s HUAWEI TECHNOLOGIES CO., LTD. Cell Bandwidth Board LBBPc LBBPd1, LBBPd2, LBBPd3, and LBBPd4 Signaling Specification (CAPS) 30 60 RRC Connected Mode Board LBBPc Cell Bandwidth 1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz LBBPd1/LBBPd2 1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz LBBPd3 1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz Page 18 Maximum Number of UEs in RRC Connected Mode 1008 1800 1800 1800 1800 (in 2R mode) or 1200 (in 4R mode) 1800 (in 2R mode) or 1200 (in 4R mode) 504 1080 1800 3600 3600 3600 1008 2160 3600 3600 3600 3600 References - LBBP PDCCH PRACH RACH algorithm switch Enable Disable Bandwidth 15,20 5,10 5,10 N 100 100 50 HUAWEI TECHNOLOGIES CO., LTD. Page 19 Thank you www.huawei.com Copyright©2011 Huawei Technologies Co., Ltd. All Rights Reserved. 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