Gsm Kpi Optimization Process And Guide 4u3i6q
This document was ed by and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this report form. Report 3b7i
Overview 3e4r5l
& View Gsm Kpi Optimization Process And Guide as PDF for free.
More details w3441
- Words: 5,635
- Pages: 22
GSM KPI Optimization Process and Guide
INTERNAL
GSM KPI Optimization Process and Guide
Huawei Technologies Co., Ltd. All rights reserved
Page 1 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Contents 1 KPI Optimization process Overview ........................................................................................................... 3 2 Main KPIs Optimization Processes ............................................................................................................. 4 3 GSM Timer Optimization.......................................................................................................................... 17 Thanks ................................................................................................................................................. 22
Page 2 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
1
INTERNAL
KPI Optimization process Overview
This document mainly describes the Network Performance Monitoring & Optimization Process We will first check all the main KPIs and how we will do the troubleshooting for them one by one and will check also the environmental effect for each, and the principle for how to check the reasons. And after that we will check the main timers and its relation to the network for both sides MS & NSS side.
Page 3 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
2
Main KPIs Optimization Processes
1. PROCESS for SDCCH Assignment Success Rate Optimization: Definition: When From the MS SDCCH Request is sent to Base Station and if MS Successfully gets the SDCCH in response SDCCH Assignment has done successfully.
PROCESS for Optimization: 1. Identify the Bad performing Cells for SDCCH Assignment Success Rate 2. Take the detailed report showing (Ex. Total SDCCH Assignment Request, Total SDCCH Assignment Successful) 3. Follow the below mentioned Process after Analyzing detailed report... 4. From Report Check whether you have Idle SDCCH available in cell or not for SDCCH Assignment; because the Main factor for lowering SDCCH Assignment success rate is SDCCH congestion. 5. SDCCH Congestion: a. Check The SDCCH Requests (Immediate Assignment Measurement Per Cell Report form M200) b. Ex. Call purpose, SMS, Location Update c. If you find High SDCCH Request and low TCH utilization Check “SDCCH Dynamic Allocation Allow” feature is enabled or not? if not enable this feature. d. If you have very High SDCCH Request for Location Updating; optimize the LAC boundary. e. Only For some exceptional cases you can increase the Static SDCCH Time Slots.
6. Check Hardware/Transmission alarms; Resolve if find any. 7. Audit for any parameters related discrepancies and define as per standard parameters set. 8. RF and Environmental Factors: a. Low Coverage Areas (Try to reduce low coverage patches with physical optimization; New sites) b. Interference/ Bad quality/ UL-DL Imbalance; c. Check the states for TRx on which SDCCH is configured can be issue of TRx
also; Change TRx if you found random behavior of TRx. 9. After all rectification observe the subsequent days report if you still find the problem repeat the same process with due care to Pin Point the actual cause. Fish bone diagram for the root cause analysis high SDCCH congestion rate
Page 4 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
2. PROCESS for SDCCH DROP Rate Optimization: Definition: When MS is already on SDCCH and in-between communication with Base Station SDCCH channel got disconnected abruptly then SDCCH Drop has occurred.
PROCESS for Optimization: 1. Identify the Bad performing Cells for SDCCH Drop Rate 2. Take the detailed report showing (Ex. Total SDCCH Assignment Successful, Total SDCCH Dropped) 3. Follow the below mentioned Process after Analyzing detailed report... 4. The Main Reasons for High SDCCH Drop Rate are improper Parameters Configuration and Bad RF & Environmental factors. 5. First Audit for any parameters related discrepancies and define as per standard parameters set. 6. Check for Neighbor Relations and correct if it is not proper. 7. For counter level analysis refer “Call Drop Measurement per Cell” report from M2000. 8. Low Coverage: Through Drive Test Find out the low coverage patched and try to improve with physical optimization; New site; coverage enhancement features for some cases(Ex. Power Boost Tech, No Combining, TMA/TMB) 9. Interference: Check for interference from repeaters, Intra-Network interference due to aggressive reuse or improper Freq., Inter-Network can also be the case. Find out the actual cause and rectify it. 10. Antenna System: High VSWR due to feeders, Improper antenna configuration(Ex. Sector cable Swap) 11. Check for Hardware Issue and rectify if you found any. 12. After the activity check the subsequent days report and repeat the procedure for pin pointing the actual cause.
Fish bone diagram for the root cause analysis for high SDCCH drop rate
Page 5 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
3. PROCESS for RACH (Random Access Channel) Success Rate Optimization: Definition: Random Access Channel (RACH) is used by the MS on the “uplink” to request for allocation of an SDCCH. This request from the MS on the uplink could either be as a page response (MS being paged by the BSS in response to an incoming call) or due to trying to access the network to establish a call. For all services there will CH REQ (Channel Request) from MS and in the response of CH REQ if MS will get the IMM ASS CMD (Signaling Ch) Access to system is successful. Nature of this Access REQ is random so it is call Random Access Channel Request.
PROCESS for Optimization: 1. Identify the Bad performing Cells for RACH Success Rate 2. Take detailed report and analyze for no of failure of Request and failures. 3. The main reasons for bad RACH success rate could be access from very distant place with very low coverage; Parameters Configuration discrepancies. 4. First Check for Parameters Configuration discrepancies and correct as per standard parameter set. 5. The main parameters to look for Huawei a. “MS MAX Retrans” can set depending upon Traffic and Clutter. b. “Tx-Interger” will reduce the RACH collision and can improve RACH success rate. c. “T3122” waiting time for next network access. d. “RACH Min.Access Level(dbm)” very important parameter for low coverage rural areas. e. “CCCH conf” & “BS_AG_BLKS_RES” check properly defined or not? Because if you have overload with AGCH “IMM ASS” can’t be send in the response of CH REQ. 6. Check for Hardware Issues (Ex. BTS sensitivity has very crucial role to play here) 7. Check for Uplink Interference and quality. 8. Check for UL-DL imbalance and correct if any problem. 9. After the activity check the subsequent days report and repeat the procedure for pin Pointing the actual cause. Fish Bone diagram for the root cause analysis of poor Random Access Success
Page 6 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
4. PROCESS for TCH Assignment Success Rate Optimization: Definition: When From the MS TCH Request is sent to Base Station and if MS successfully gets the TCH in response TCH Assignment has done successfully.
PROCESS for Optimization: 1. Identify the Bad performing Cells for TASR( TCH Assignment Success Rate) 2. Take the detailed report showing (Ex. Total Assignment Request, Total Assignment Successful) 3. Follow the below mentioned Process after Analyzing detailed report... 4. From Report Check whether you have Idle TCH available in cell or not for Assignment and follow the below process. A & B in above Flow chart are measurement Points for TCH Assignment Failures... 5. As per the Above Process If you have already used “Re-Assignment”, “Directed Retry” and “Queuing” features and still you are having issue with TCH Congestion (No Idle TCH)... Try to Decrease Half Rate Triggering Thresholds... 6. Ex. Below Parameters for Huawei System “TCH Busy Traffic Threshold (%)” “AMR TCH/H Prior Allowed” “AMR TCH/H Prior Cell Load Threshold” 7. Check for discrepancies with Parameter Configuration and set as per Standard Parameters set available. 8. If you find Issue is not with High Traffic and Congestion... Check Hardware Issue (Ex. BTS/BSC/MSC hardware / UL-DL Imbalance due to VSWR) resolve if you find any. 9. Transmission Issues at A-bis/A-ter/A links 10. If Hardware is Ok check for Bad RF Environment... (Very low Coverage, High Interference, Bad Quality, Call from Distant Place (TA). 11. Follow below Process for Above Points... You can check the counters Report for Pin Page 7 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
pointing the actual cause. (Ex. Assignment Per Cell Report from M2000)
12. Correct the affected area (Ex. If call is getting originated from High TA and getting failed due improper strength ; Optimize the Site Coverage with Physical Optimization) and check the subsequent days Report; If you still find the issue follow the same flow right from the starting with due care to PIN Point the Actual cause.. 13. TBF Success Rate 14. Average GPRS RLC throughput & Average EDGE RLC Throughput 15. Downlink Multi-slot Assignment Success Rate 16. SDCCH Assignment Success Rate 17. SDCCH DROP Rate 18. ACH (Random Access Channel) Success Rate 19. Assignment Success Rate
5. PROCESS for Rx Quality Optimization: • Definition: Rx Quality is measure of BER of radio link between MS and BTS Poor Speech Quality could be due to • Patchy Coverage ( Gaps) • No Target cell for Handover • Echo , Audio holes, Voice Clipping Interference ---: • Co-channel • Adjacent channel Page 8 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
• • •
External Multipath Noise
Speech Quality Parameters • Rx-QUAL: Measured on the mid-amble. • Indicates poor speech quality due to radio interface impairments • FER : Measured on the basis of BFI ( Ping -Pong effect on speech ) • Preferred under Frequency Hopping situation • Audio holes: Blank period of speech, due to malfunctioning of Trans-coder boards or PCM circuits. • Mean Opinion Score (MOS) : ITU standard for estimating speech quality
PROCESS for Optimization: 1) Physical optimization 2) New cell dependency 3) Overshooting 4) Neighbor list tuning 5) BCCH tuning (Freq plan)
From M2000 extract Rx Quality measurement distribution counters to know the TRX-Cell Wise RX quality. Voice Quality KPIs.xlsx
6. PROCESS for HOSR Optimization: Definition: HO activity is performed to maintain – Call continuity and call quality. The inputs that the BSC uses for making a handover decision, from the received MRs from the MS is the DL signal strength, DL quality, and the signal strength of the six best reported neighbors. From the serving BTS, for the same MS the BSC will use UL signal strength, UL quality and TA.
Handover Process: The GSM handover process uses a mobile assisted technique for accurate and fast Handovers, in order to: - Maintain the connection link quality. - Manage traffic distribution The overall handover process is implemented in the MS, BSS & MSC. Measurement of radio subsystem downlink performance and signal strengths received from surrounding cells, is made in the MS. These measurements are sent to the BSS for assessment. The BSS measures the uplink performance for the MS being served and also assesses the signal strength of interference on its idle traffic channels. Initial assessment of the measurements in conjunction with defined thresholds and
Page 9 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Handover strategy may be performed in the BSS. Assessment requiring measurement Results from other BSS or other information resident in the MSC, may be perform. In the MSC. The MS assists the handover decision process by performing certain measurements. When the MS is engaged in a speech conversation, a portion of the TDMA frame is idle while the rest of the frame is used for uplink (BTS receive) and downlink (BTS transmit) timeslots. During the idle time period of the frame, the MS changes radio channel frequency and monitors and measures the signal level of the six best neighbor cells. Measurements which feed the handover decision algorithm are made at both ends of the radio link.
Classification by Reason: • Emergency HO – Timing advance (TA) Emergency HO – Bad quality (BQ) Emergency HO – Rx Level Drop Emergency HO – Interference emergency HO • load HO • Normal HO – Edge HO – Layer HO – Power budget (PBGT) HO • Fast moving MS HO (Speed-sensitive HO )
PROCESS for Optimization:
Identify the Bad performing Cells for HOSR Take the detailed report showing cause & target cell Check congestion; hardware Alarm; Quality; Rx level Late Handover – Handover margin (like Rx level-Rx Qual etc )need to define properly. Ping-Pong Handover – A proper Hysteresis is used to prevent the Ping Pong effect. This can be caused by fading. Unnecessary Handover – more number of handovers, higher risk of facing quality problem and even in call drop. Missing neighbor – Best server is not in there in neighbor list BCCH Missing Same BCCH & BSIC combination. One way neighbor handover. Neighbor cell in other BSC- need to define correct CGI,BCCHNO,BSIC Congestion on other cell.
Fish bone diagram for the root cause analysis for high handover failure rate
Page 10 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
7. PROCESSE for TCH drop Optimization: Definition: TCH drop (or a dropped call) could be broadly classified into 3 sub classes: 1. Degradation of the links (Uplink and Downlink): either degradation of Signal Strength Which falls near or lower than the sensitivity of the base station (around to -110 dBm) or That of the mobile (around -104dBm) or degradation of quality of the links (Uplink and Downlink) often due to interference. 2. Excess TA (TA>63 or excess path imbalance due to high TA). 3. Other Reasons.
PROCESS for Optimization: Call drops are identified through SACCH messages. A Radio Link Failure Counter value is broadcast on the BCH. The counter value may vary from network to network. At the Establishment of a dedicated channel, the counter is set to the broadcast value (which will be the maximum allowable for the connection). The mobile decrements the counter by 1 for every FER (unrecoverable block of data) detected on the SACCH and increases the counter by 2 for every data block that is correctly received (up to the initial maximum value). If this counter reaches zero, a radio link failure is declared by the mobile and it returns back to the idle mode. If the counter reaches zero when the mobile is on a SDCCH then it is an SDCCH Drop. If it happens on a TCH, it is a TCH drop. Sometimes an attempted handover, which may in itself have been an attempt to prevent a drop, can result in a dropped call. When the quality drops, a mobile is usually commanded to perform a handover. Sometimes, when it attempts to handover, it finds that the target cell is not suitable. When this happens it jumps back to the old cell and sends a Handover Failure message to the old cell. At this stage, if the handover was attempted at the survival threshold, the call may get dropped anyway. If on the other hand the thresholds were somewhat higher, the network can attempt another handover.
Page 11 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
From U2000 extract Call drop Measurements counters to know the cause.
CDR Reason XLS.xls Figure 1: Fish bone diagram for the root cause analysis for high TCH Drop Rate
Figure 2: Fish bone diagram for the root cause analysis for high TCH Drop Rate
Factors That Affect the TCH Call Drop Rate o Hardware Failure Call Drop Due to Imbalance Between Uplink and Downlink & ICM & Trx efficiency (TRX Board Fault). o Transmission Problem ABIS or E1 problems ( or IP Path Problems ( delay) o Version Upgrade(the BSC and BTS Version Upgrade) o Parameter Setting Changing HO or PC parameters to improve CDR% Increase in Call Drop Rate Due to Inactivity of T305 and T308. Increase in Call Drop Rate Due to Change of TR1N on the MSC Side. o Intra-Network and Inter-Network Interference Call Drop Due to Interference( internal Co BCCH or adjacent & External interference) o Coverage Problem Call Drop Due to Coverage ( Gap) o Antenna System Problem o Repeater Problem Call Drop Due to Repeater Problem
Page 12 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
8. PROCESS for Paging Success Rate: Definition: Paging Success rate is the percentage of valid page responses received by the system PSR = ( CC service first paging response number + CC service repeat paging response number+ SMS service first paging response number + SMS service repeat paging response number) / (CC service first send paging number + SMS service first send paging number)*100
PROCESS for Optimization: 1. Removal of non existing Cell site database created in BSCs 2. Correcting the number of LACs per BSC (Minimizing the number of LAC per BSC) 3. Standard template of Cell site database in each BSC. 1 Fish bone diagram for the root cause analysis of poor Paging Success Rate:
Figure 1 : Root Cause for Poor Paging Succ Rate (1)
Figure 2 : Root Cause for Poor Paging Succ Rate (2)
Page 13 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
9. PROCESS for SS7 Signaling Load: Definition: 1. TRANSMITT LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS TRANSMITTED + 6 *(MSU TRANSMITTED + MSU RETRANSMITTED) ) / (248000 * 3600 * 0.2) ) * 100) -----> HSL 2. TRANSMITT LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETSTRANSMITTED + 6 *(MSU TRANSMITTED + MSU RETRANSMITTED) ) / (8000 * 3600 * 0.4) ) * 100) -----> OTHER THAN HSL 3. RECEIVE LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS RECEIVED + 6 *(MSU RECEIVED) ) / (248000 * 3600 * 0.2) ) * 100) -----> HSL 4. RECEIVE LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS RECEIVED + 6 *(MSU RECEIVED) ) / (8000 * 3600 * 0.4) ) * 100) -----> OTHER THAN HSL
PROCESS for Optimization: 1. Identify the signaling links whose utilization is going above 80%. 2. Prepared Plan for additional signaling links as per requirement…
10. PROCESS for TBF Success Rate Optimization: Definition: Temporary Block Flow (TBF) is a physical connection used by the two Radios Resource entities to the unidirectional transfer of PDUs on packet data physical Channels. The TBF is allocated radio resource on one or more PDCHs and comprises a number Of RLC/MAC blocks carrying one or more LLC PDU. TBF Success Rate is when during a Data session, TBFs are successfully established on UL and DL.
PROCESS for Optimization: 1. Identify the Bad performing Cells for TBF Success Rate. 2. Identify the bifurcation of Poor TBF Success Rate: whether UL or DL is poor or it is poor in both directions. 3. Take the detailed report showing (Ex. Total TBF Requests, Total TBF Success, Failure reasons) 4. Identify the failure reasons after analyzing detailed report and follow the below i. Mentioned process. Failure is mainly due to TBF Congestion or MS No response.
5. TBF Congestion: a. b. c.
Check The Static and Dynamic PDCH definition from BSC Configuration data) If you find Zero Static or Dynamic PDCH, define the same. If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell.
6. Check Hardware/TRX alarms; Resolve if find any. 7. Audit for any parameters related discrepancies and define as per standard parameters set. 8. MS No Response: RF and Environmental Factors: a. Low Coverage Areas (Try to reduce low coverage patches with physical optimization; New sites) b. Interference/ Bad quality/ UL-DL Imbalance; c. Check the states for TRx on which PDCH is configured can be issue of TRx also; Change TRx if you found random behavior of TRx. After all rectification observe the subsequent days report if you still find the problem repeat the same process with due care to Pin Point the actual cause.
Page 14 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
11. PROCESS for Optimization of Average GPRS RLC throughput and Average EDGE RLC Throughput: Definition: Throughput is the amount of data ed/ed per unit of time. PROCESS for Optimization: 1. Identify the Bad performing Cells for Poor GPRS/EDGE Throughput. 2. Identify the bifurcation of Poor Throughput: whether UL or DL is poor or it is poor in both directions. 3. Take the detailed report showing (Ex. Total TBF Requests, Coding Scheme Utilization) 4. Identify the cells after analyzing detailed report and follow the below mentioned process. 5. Take the configuration dump of the poor cells: a. Check The Static and Dynamic PDCH definition from BSC Configuration data) b. If you find Zero Static or Dynamic PDCH, define the same. c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. d. Check whether there are enough Idle TS defined at the site. If not, definition to be done. 6. Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive test to analyze the cell in more detail. 7. Check Gb Congestion/Utilization at the BSC/PCU. 8. Check Hardware/TRX alarms; Resolve if find any. 9. Audit for any parameters related discrepancies and define as per standard parameters set. After all rectification observe the subsequent days report if you still find the problem repeat the same process with due care to Pin Point the actual cause.
12. PROCESS for Optimization of Downlink Multi-slot Assignment Success Rate: Definition: timeslot request based on traffic types and MS multi-timeslot capability and the actual timeslot allocated by the system which can also be termed as Downlink Multi-slot Assignment Success rate.
PROCESS for Optimization: 1. Identify the Bad performing Cells for Poor DL Multi-slot Assignment. 2. Take the detailed report showing (Ex. Total TBF Requests, Failure in of TS requests) 3. Identify the cells after analyzing detailed report and follow the below mentioned process. 4. Take the configuration dump of the poor cells: a. Check The Static and Dynamic PDCH definition from BSC Configuration data) b. If you find Zero Static or Dynamic PDCH, define the same. c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF Page 15 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. d. Check the multiplexing thresholds and upgrade/downgrade reports. 5. Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive test to analyze the cell in more detail. 6. Check Gb Congestion/PCU-DSP Utilization. 7. Check Hardware/TRX alarms; Resolve if find any. 8. Audit for any parameters related discrepancies and define as per standard parameters set. After all rectification observe the subsequent days report if you still find the problem repeat the Same process with due care to Pin Point the actual cause.
Page 16 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
3
INTERNAL
GSM Timer Optimization
Like any other wireless technology with a limited pool of resources, GSM resource allocation and termination depends primarily on timers. The functionality and protocols may vary, but the presence of timer based signaling and resource allocation is ubiquitous. Timer implementation is present in each domain of the GSM system from MS to NSS end. And most of the important timers will be introduced below on both the sides (MS&NSS).
And Below we will introduce a summary for the timers which it will be composed of 2 parts: 1. A summarization for the timer message. 2. Most of the timer on both the sides the MS & the NSS respectively.
1. Timer Messages description:
Page 17 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
GSM Timers Summarization:
The below timers will describe the main important timer on each side whether Mobile Station side or the Network side.
Timers on the mobile station side:
T3122: This timer is used during random access, after the receipt of an IMMEDIATE ASSIGN REJECT message. Its value is given by the network in the IMMEDIATE ASSIGN REJECT message.
T3124: This timer is used in the seizure procedure during a hand-over, when the two cells are not synchronized. Its purpose is to detect the lack of answer from the network to the special signal. Its value is set to 675 ms if the channel type of the channel allocated in the HANDOVER COMMAND is an SDCCH (+ SACCH); otherwise its value is set to 320 ms.
T3126:This timer is started either after sending the maximum allowed number of CHANNEL REQUEST messages during an immediate assignment procedure. Or on receipt of an IMMEDIATE ASSIGNMENT REJECT message, whichever occurs first. It is stopped at receipt of an IMMEDIATE ASSIGNMENT message, or an IMMEDIATE ASSIGNMENT EXTENDED message. At its expiry, the immediate assignment procedure is aborted. The minimum value of this timer is equal to the time taken by T+2S slots of the mobile station's RACH. S and T. The maximum value of this timer is 5 seconds.
Page 18 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
T3128: This timer is started when the mobile station starts the uplink investigation procedure and the uplink is busy. It is stopped at receipt of the first UPLINK FREE message. At its expiry, the uplink investigation procedure is aborted. The value of this timer is set to 1 second.
T3130: This timer is started after sending the first UPLINK ACCESS message during a VGCS uplink access procedure. It is stopped at receipt of a VGCS ACCESS GRANT message. At its expiry, the uplink access procedure is aborted. The value of this timer is set to 5 seconds.
T3110: This timer is used to delay the channel deactivation after the receipt of a (full) CHANNEL RELEASE. Its purpose is to let some time for disconnection of the main signaling link. Its value is set to such that the DISC frame is sent twice in case of no answer from the network. (It should be chosen to obtain a good probability of normal termination (i.e. no time out of T3109) of the channel release procedure.)
T3134: This timer is used in the seizure procedure during an RR network commanded cell change order procedure. Its purpose is to detect the lack of answer from the network or the lack of availability of the target cell. Its value is set to 5 seconds.
T3142: The timer is used during packet access on CCCH, after the receipt of an IMMEDIATE ASSIGNMENT REJECT message. Its value is given by the network in the IMMEDIATE ASSIGNMENT REJECT message. T3146:This timer is started either after sending the maximum allowed number of CHANNEL REQUEST messages during a packet access procedure. Or on receipt of an IMMEDIATE ASSIGNMENT REJECT message during a packet access procedure, whichever occurs first. It is stopped at receipt of an IMMEDIATE ASSIGNMENT message, or an IMMEDIATE ASSIGNMENT EXTENDED message. At its expiry, the packet access procedure is aborted. The minimum value of this timer is equal to the time taken by T+2S slots of the mobile station's RACH. S and T are defined in section 3.3.1.2. The maximum value of this timer is 5 Sec. T3164: This timer is used during packet access using CCCH. It is started at the receipt of an IMMEDIATE ASSIGNMENT message. It is stopped at the transmission of a RLC/MAC block on the assigned temporary block flow, see GSM 04.60. At expire, the mobile station returns to the packet idle mode. The value of the timer is 5 seconds.
T3190: The timer is used during packet downlink assignment on CCCH. It is started at the receipt of an IMMEDIATE ASSIGNMENT message or of an PDCH ASSIGNMENT COMMAND message when in dedicated mode. It is stopped at the receipt of a RLC/MAC block on the assigned temporary block flow, see GSM 04.60. At expiry, the mobile station returns to the packet idle mode. The value of the timer is 5 seconds.
T3212 (Location update timer): This timer is related with the termination of MM signaling. It starts with the termination of MM signaling. And it timer stops when the message for the initiation of MM signaling is sent to the MS by the BSS entity. Expiry Event: In case the timer expires, a periodic request is sent for the LU update. The default value for this timer is 60 seconds.
Page 19 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Timers on the network side:
T3101: This timer is started when a channel is allocated with an IMMEDIATE ASSIGNMENT message. It is stopped when the MS has correctly seized the channels. Its value is network dependent. NOTE: It could be higher than the maximum time for a L2 establishment attempt.
T3103: This timer is started by the sending of a HANDOVER message and is normally stopped when the MS has correctly seized the new channel. Its purpose is to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the HANDOVER COMMAND, plus the value of T3124, plus the maximum duration of an attempt to establish a data link in multi-frame mode.)
T3105: This timer is used for the repetition of the PHYSICAL INFORMATION message during the hand-over procedure. Its value is network dependent. NOTE: This timer may be set to such a low value that the message is in fact continuously transmitted.
T3107: This timer is started by the sending of an ASSIGNMENT COMMAND message and is normally stopped when the MS has correctly seized the new channels. Its purpose is to keep the old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the ASSIGNMENT COMMAND message plus twice the maximum duration of an attempt to establish a data link multi-frame mode.
T3109: This timer is started when a lower layer failure is detected by the network, when it is not engaged in a RF procedure. It is also used in the channel release procedure. Its purpose is to release the channels in case of loss of communication. Its value is network dependent. NOTE: Its value should be large enough to ensure that the MS detects a radio link failure.
T3111: This timer is used to delay the channel deactivation after disconnection of the main signaling link. Its purpose is to let some time for possible repetition of the disconnection. Its value is equal to the value of T3110.
T3113: This timer is started when the network has sent a PAGING REQUEST message and is stopped when the network has received the PAGING RESPONSE message. Its value is network dependent. NOTE: The value could allow for repetitions of the Channel Request message and the requirements associated with T3101.
T3115: This timer is used for the repetition of the VGCS UPLINK GRANT message during the uplink access procedure. Its value is network dependent. NOTE: This timer may be set to such a low value that the message is in fact continuously transmitted.
T3117: This timer is started by the sending of a PDCH ASSIGNMENT COMMAND message and is normally stopped when the MS has correctly accessed the target TBF. Its purpose is to keep the
Page 20 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the PDCH ASSIGNMENT COMMAND message plus T3132 plus the maximum duration of an attempt to establish a data link in multi-frame mode.
T3119: This timer is started by the sending of a RR-CELL CHANGE ORDER message and is normally stopped when the MS has correctly accessed the new cell. Its purpose is to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the RR_CELL CHANGE ORDER, plus T3134, plus the maximum duration of an attempt to establish a data link in multi-frame mode. T3141: This timer is started when a temporary block flow is allocated with an IMMEDIATE ASSIGNMENT message during a packet access procedure. It is stopped when the mobile station has correctly seized the temporary block flow. Its value is network dependent.
Page 21 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Thanks
Page 22 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
Huawei Technologies Co., Ltd. All rights reserved
Page 1 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Contents 1 KPI Optimization process Overview ........................................................................................................... 3 2 Main KPIs Optimization Processes ............................................................................................................. 4 3 GSM Timer Optimization.......................................................................................................................... 17 Thanks ................................................................................................................................................. 22
Page 2 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
1
INTERNAL
KPI Optimization process Overview
This document mainly describes the Network Performance Monitoring & Optimization Process We will first check all the main KPIs and how we will do the troubleshooting for them one by one and will check also the environmental effect for each, and the principle for how to check the reasons. And after that we will check the main timers and its relation to the network for both sides MS & NSS side.
Page 3 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
2
Main KPIs Optimization Processes
1. PROCESS for SDCCH Assignment Success Rate Optimization: Definition: When From the MS SDCCH Request is sent to Base Station and if MS Successfully gets the SDCCH in response SDCCH Assignment has done successfully.
PROCESS for Optimization: 1. Identify the Bad performing Cells for SDCCH Assignment Success Rate 2. Take the detailed report showing (Ex. Total SDCCH Assignment Request, Total SDCCH Assignment Successful) 3. Follow the below mentioned Process after Analyzing detailed report... 4. From Report Check whether you have Idle SDCCH available in cell or not for SDCCH Assignment; because the Main factor for lowering SDCCH Assignment success rate is SDCCH congestion. 5. SDCCH Congestion: a. Check The SDCCH Requests (Immediate Assignment Measurement Per Cell Report form M200) b. Ex. Call purpose, SMS, Location Update c. If you find High SDCCH Request and low TCH utilization Check “SDCCH Dynamic Allocation Allow” feature is enabled or not? if not enable this feature. d. If you have very High SDCCH Request for Location Updating; optimize the LAC boundary. e. Only For some exceptional cases you can increase the Static SDCCH Time Slots.
6. Check Hardware/Transmission alarms; Resolve if find any. 7. Audit for any parameters related discrepancies and define as per standard parameters set. 8. RF and Environmental Factors: a. Low Coverage Areas (Try to reduce low coverage patches with physical optimization; New sites) b. Interference/ Bad quality/ UL-DL Imbalance; c. Check the states for TRx on which SDCCH is configured can be issue of TRx
also; Change TRx if you found random behavior of TRx. 9. After all rectification observe the subsequent days report if you still find the problem repeat the same process with due care to Pin Point the actual cause. Fish bone diagram for the root cause analysis high SDCCH congestion rate
Page 4 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
2. PROCESS for SDCCH DROP Rate Optimization: Definition: When MS is already on SDCCH and in-between communication with Base Station SDCCH channel got disconnected abruptly then SDCCH Drop has occurred.
PROCESS for Optimization: 1. Identify the Bad performing Cells for SDCCH Drop Rate 2. Take the detailed report showing (Ex. Total SDCCH Assignment Successful, Total SDCCH Dropped) 3. Follow the below mentioned Process after Analyzing detailed report... 4. The Main Reasons for High SDCCH Drop Rate are improper Parameters Configuration and Bad RF & Environmental factors. 5. First Audit for any parameters related discrepancies and define as per standard parameters set. 6. Check for Neighbor Relations and correct if it is not proper. 7. For counter level analysis refer “Call Drop Measurement per Cell” report from M2000. 8. Low Coverage: Through Drive Test Find out the low coverage patched and try to improve with physical optimization; New site; coverage enhancement features for some cases(Ex. Power Boost Tech, No Combining, TMA/TMB) 9. Interference: Check for interference from repeaters, Intra-Network interference due to aggressive reuse or improper Freq., Inter-Network can also be the case. Find out the actual cause and rectify it. 10. Antenna System: High VSWR due to feeders, Improper antenna configuration(Ex. Sector cable Swap) 11. Check for Hardware Issue and rectify if you found any. 12. After the activity check the subsequent days report and repeat the procedure for pin pointing the actual cause.
Fish bone diagram for the root cause analysis for high SDCCH drop rate
Page 5 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
3. PROCESS for RACH (Random Access Channel) Success Rate Optimization: Definition: Random Access Channel (RACH) is used by the MS on the “uplink” to request for allocation of an SDCCH. This request from the MS on the uplink could either be as a page response (MS being paged by the BSS in response to an incoming call) or due to trying to access the network to establish a call. For all services there will CH REQ (Channel Request) from MS and in the response of CH REQ if MS will get the IMM ASS CMD (Signaling Ch) Access to system is successful. Nature of this Access REQ is random so it is call Random Access Channel Request.
PROCESS for Optimization: 1. Identify the Bad performing Cells for RACH Success Rate 2. Take detailed report and analyze for no of failure of Request and failures. 3. The main reasons for bad RACH success rate could be access from very distant place with very low coverage; Parameters Configuration discrepancies. 4. First Check for Parameters Configuration discrepancies and correct as per standard parameter set. 5. The main parameters to look for Huawei a. “MS MAX Retrans” can set depending upon Traffic and Clutter. b. “Tx-Interger” will reduce the RACH collision and can improve RACH success rate. c. “T3122” waiting time for next network access. d. “RACH Min.Access Level(dbm)” very important parameter for low coverage rural areas. e. “CCCH conf” & “BS_AG_BLKS_RES” check properly defined or not? Because if you have overload with AGCH “IMM ASS” can’t be send in the response of CH REQ. 6. Check for Hardware Issues (Ex. BTS sensitivity has very crucial role to play here) 7. Check for Uplink Interference and quality. 8. Check for UL-DL imbalance and correct if any problem. 9. After the activity check the subsequent days report and repeat the procedure for pin Pointing the actual cause. Fish Bone diagram for the root cause analysis of poor Random Access Success
Page 6 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
4. PROCESS for TCH Assignment Success Rate Optimization: Definition: When From the MS TCH Request is sent to Base Station and if MS successfully gets the TCH in response TCH Assignment has done successfully.
PROCESS for Optimization: 1. Identify the Bad performing Cells for TASR( TCH Assignment Success Rate) 2. Take the detailed report showing (Ex. Total Assignment Request, Total Assignment Successful) 3. Follow the below mentioned Process after Analyzing detailed report... 4. From Report Check whether you have Idle TCH available in cell or not for Assignment and follow the below process. A & B in above Flow chart are measurement Points for TCH Assignment Failures... 5. As per the Above Process If you have already used “Re-Assignment”, “Directed Retry” and “Queuing” features and still you are having issue with TCH Congestion (No Idle TCH)... Try to Decrease Half Rate Triggering Thresholds... 6. Ex. Below Parameters for Huawei System “TCH Busy Traffic Threshold (%)” “AMR TCH/H Prior Allowed” “AMR TCH/H Prior Cell Load Threshold” 7. Check for discrepancies with Parameter Configuration and set as per Standard Parameters set available. 8. If you find Issue is not with High Traffic and Congestion... Check Hardware Issue (Ex. BTS/BSC/MSC hardware / UL-DL Imbalance due to VSWR) resolve if you find any. 9. Transmission Issues at A-bis/A-ter/A links 10. If Hardware is Ok check for Bad RF Environment... (Very low Coverage, High Interference, Bad Quality, Call from Distant Place (TA). 11. Follow below Process for Above Points... You can check the counters Report for Pin Page 7 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
pointing the actual cause. (Ex. Assignment Per Cell Report from M2000)
12. Correct the affected area (Ex. If call is getting originated from High TA and getting failed due improper strength ; Optimize the Site Coverage with Physical Optimization) and check the subsequent days Report; If you still find the issue follow the same flow right from the starting with due care to PIN Point the Actual cause.. 13. TBF Success Rate 14. Average GPRS RLC throughput & Average EDGE RLC Throughput 15. Downlink Multi-slot Assignment Success Rate 16. SDCCH Assignment Success Rate 17. SDCCH DROP Rate 18. ACH (Random Access Channel) Success Rate 19. Assignment Success Rate
5. PROCESS for Rx Quality Optimization: • Definition: Rx Quality is measure of BER of radio link between MS and BTS Poor Speech Quality could be due to • Patchy Coverage ( Gaps) • No Target cell for Handover • Echo , Audio holes, Voice Clipping Interference ---: • Co-channel • Adjacent channel Page 8 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
• • •
External Multipath Noise
Speech Quality Parameters • Rx-QUAL: Measured on the mid-amble. • Indicates poor speech quality due to radio interface impairments • FER : Measured on the basis of BFI ( Ping -Pong effect on speech ) • Preferred under Frequency Hopping situation • Audio holes: Blank period of speech, due to malfunctioning of Trans-coder boards or PCM circuits. • Mean Opinion Score (MOS) : ITU standard for estimating speech quality
PROCESS for Optimization: 1) Physical optimization 2) New cell dependency 3) Overshooting 4) Neighbor list tuning 5) BCCH tuning (Freq plan)
From M2000 extract Rx Quality measurement distribution counters to know the TRX-Cell Wise RX quality. Voice Quality KPIs.xlsx
6. PROCESS for HOSR Optimization: Definition: HO activity is performed to maintain – Call continuity and call quality. The inputs that the BSC uses for making a handover decision, from the received MRs from the MS is the DL signal strength, DL quality, and the signal strength of the six best reported neighbors. From the serving BTS, for the same MS the BSC will use UL signal strength, UL quality and TA.
Handover Process: The GSM handover process uses a mobile assisted technique for accurate and fast Handovers, in order to: - Maintain the connection link quality. - Manage traffic distribution The overall handover process is implemented in the MS, BSS & MSC. Measurement of radio subsystem downlink performance and signal strengths received from surrounding cells, is made in the MS. These measurements are sent to the BSS for assessment. The BSS measures the uplink performance for the MS being served and also assesses the signal strength of interference on its idle traffic channels. Initial assessment of the measurements in conjunction with defined thresholds and
Page 9 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Handover strategy may be performed in the BSS. Assessment requiring measurement Results from other BSS or other information resident in the MSC, may be perform. In the MSC. The MS assists the handover decision process by performing certain measurements. When the MS is engaged in a speech conversation, a portion of the TDMA frame is idle while the rest of the frame is used for uplink (BTS receive) and downlink (BTS transmit) timeslots. During the idle time period of the frame, the MS changes radio channel frequency and monitors and measures the signal level of the six best neighbor cells. Measurements which feed the handover decision algorithm are made at both ends of the radio link.
Classification by Reason: • Emergency HO – Timing advance (TA) Emergency HO – Bad quality (BQ) Emergency HO – Rx Level Drop Emergency HO – Interference emergency HO • load HO • Normal HO – Edge HO – Layer HO – Power budget (PBGT) HO • Fast moving MS HO (Speed-sensitive HO )
PROCESS for Optimization:
Identify the Bad performing Cells for HOSR Take the detailed report showing cause & target cell Check congestion; hardware Alarm; Quality; Rx level Late Handover – Handover margin (like Rx level-Rx Qual etc )need to define properly. Ping-Pong Handover – A proper Hysteresis is used to prevent the Ping Pong effect. This can be caused by fading. Unnecessary Handover – more number of handovers, higher risk of facing quality problem and even in call drop. Missing neighbor – Best server is not in there in neighbor list BCCH Missing Same BCCH & BSIC combination. One way neighbor handover. Neighbor cell in other BSC- need to define correct CGI,BCCHNO,BSIC Congestion on other cell.
Fish bone diagram for the root cause analysis for high handover failure rate
Page 10 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
7. PROCESSE for TCH drop Optimization: Definition: TCH drop (or a dropped call) could be broadly classified into 3 sub classes: 1. Degradation of the links (Uplink and Downlink): either degradation of Signal Strength Which falls near or lower than the sensitivity of the base station (around to -110 dBm) or That of the mobile (around -104dBm) or degradation of quality of the links (Uplink and Downlink) often due to interference. 2. Excess TA (TA>63 or excess path imbalance due to high TA). 3. Other Reasons.
PROCESS for Optimization: Call drops are identified through SACCH messages. A Radio Link Failure Counter value is broadcast on the BCH. The counter value may vary from network to network. At the Establishment of a dedicated channel, the counter is set to the broadcast value (which will be the maximum allowable for the connection). The mobile decrements the counter by 1 for every FER (unrecoverable block of data) detected on the SACCH and increases the counter by 2 for every data block that is correctly received (up to the initial maximum value). If this counter reaches zero, a radio link failure is declared by the mobile and it returns back to the idle mode. If the counter reaches zero when the mobile is on a SDCCH then it is an SDCCH Drop. If it happens on a TCH, it is a TCH drop. Sometimes an attempted handover, which may in itself have been an attempt to prevent a drop, can result in a dropped call. When the quality drops, a mobile is usually commanded to perform a handover. Sometimes, when it attempts to handover, it finds that the target cell is not suitable. When this happens it jumps back to the old cell and sends a Handover Failure message to the old cell. At this stage, if the handover was attempted at the survival threshold, the call may get dropped anyway. If on the other hand the thresholds were somewhat higher, the network can attempt another handover.
Page 11 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
From U2000 extract Call drop Measurements counters to know the cause.
CDR Reason XLS.xls Figure 1: Fish bone diagram for the root cause analysis for high TCH Drop Rate
Figure 2: Fish bone diagram for the root cause analysis for high TCH Drop Rate
Factors That Affect the TCH Call Drop Rate o Hardware Failure Call Drop Due to Imbalance Between Uplink and Downlink & ICM & Trx efficiency (TRX Board Fault). o Transmission Problem ABIS or E1 problems ( or IP Path Problems ( delay) o Version Upgrade(the BSC and BTS Version Upgrade) o Parameter Setting Changing HO or PC parameters to improve CDR% Increase in Call Drop Rate Due to Inactivity of T305 and T308. Increase in Call Drop Rate Due to Change of TR1N on the MSC Side. o Intra-Network and Inter-Network Interference Call Drop Due to Interference( internal Co BCCH or adjacent & External interference) o Coverage Problem Call Drop Due to Coverage ( Gap) o Antenna System Problem o Repeater Problem Call Drop Due to Repeater Problem
Page 12 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
8. PROCESS for Paging Success Rate: Definition: Paging Success rate is the percentage of valid page responses received by the system PSR = ( CC service first paging response number + CC service repeat paging response number+ SMS service first paging response number + SMS service repeat paging response number) / (CC service first send paging number + SMS service first send paging number)*100
PROCESS for Optimization: 1. Removal of non existing Cell site database created in BSCs 2. Correcting the number of LACs per BSC (Minimizing the number of LAC per BSC) 3. Standard template of Cell site database in each BSC. 1 Fish bone diagram for the root cause analysis of poor Paging Success Rate:
Figure 1 : Root Cause for Poor Paging Succ Rate (1)
Figure 2 : Root Cause for Poor Paging Succ Rate (2)
Page 13 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
9. PROCESS for SS7 Signaling Load: Definition: 1. TRANSMITT LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS TRANSMITTED + 6 *(MSU TRANSMITTED + MSU RETRANSMITTED) ) / (248000 * 3600 * 0.2) ) * 100) -----> HSL 2. TRANSMITT LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETSTRANSMITTED + 6 *(MSU TRANSMITTED + MSU RETRANSMITTED) ) / (8000 * 3600 * 0.4) ) * 100) -----> OTHER THAN HSL 3. RECEIVE LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS RECEIVED + 6 *(MSU RECEIVED) ) / (248000 * 3600 * 0.2) ) * 100) -----> HSL 4. RECEIVE LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS RECEIVED + 6 *(MSU RECEIVED) ) / (8000 * 3600 * 0.4) ) * 100) -----> OTHER THAN HSL
PROCESS for Optimization: 1. Identify the signaling links whose utilization is going above 80%. 2. Prepared Plan for additional signaling links as per requirement…
10. PROCESS for TBF Success Rate Optimization: Definition: Temporary Block Flow (TBF) is a physical connection used by the two Radios Resource entities to the unidirectional transfer of PDUs on packet data physical Channels. The TBF is allocated radio resource on one or more PDCHs and comprises a number Of RLC/MAC blocks carrying one or more LLC PDU. TBF Success Rate is when during a Data session, TBFs are successfully established on UL and DL.
PROCESS for Optimization: 1. Identify the Bad performing Cells for TBF Success Rate. 2. Identify the bifurcation of Poor TBF Success Rate: whether UL or DL is poor or it is poor in both directions. 3. Take the detailed report showing (Ex. Total TBF Requests, Total TBF Success, Failure reasons) 4. Identify the failure reasons after analyzing detailed report and follow the below i. Mentioned process. Failure is mainly due to TBF Congestion or MS No response.
5. TBF Congestion: a. b. c.
Check The Static and Dynamic PDCH definition from BSC Configuration data) If you find Zero Static or Dynamic PDCH, define the same. If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell.
6. Check Hardware/TRX alarms; Resolve if find any. 7. Audit for any parameters related discrepancies and define as per standard parameters set. 8. MS No Response: RF and Environmental Factors: a. Low Coverage Areas (Try to reduce low coverage patches with physical optimization; New sites) b. Interference/ Bad quality/ UL-DL Imbalance; c. Check the states for TRx on which PDCH is configured can be issue of TRx also; Change TRx if you found random behavior of TRx. After all rectification observe the subsequent days report if you still find the problem repeat the same process with due care to Pin Point the actual cause.
Page 14 of 22 Huawei Proprietary and Confidential 13-06-2016
INTERNAL
GSM KPI Optimization Process and Guide
11. PROCESS for Optimization of Average GPRS RLC throughput and Average EDGE RLC Throughput: Definition: Throughput is the amount of data ed/ed per unit of time. PROCESS for Optimization: 1. Identify the Bad performing Cells for Poor GPRS/EDGE Throughput. 2. Identify the bifurcation of Poor Throughput: whether UL or DL is poor or it is poor in both directions. 3. Take the detailed report showing (Ex. Total TBF Requests, Coding Scheme Utilization) 4. Identify the cells after analyzing detailed report and follow the below mentioned process. 5. Take the configuration dump of the poor cells: a. Check The Static and Dynamic PDCH definition from BSC Configuration data) b. If you find Zero Static or Dynamic PDCH, define the same. c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. d. Check whether there are enough Idle TS defined at the site. If not, definition to be done. 6. Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive test to analyze the cell in more detail. 7. Check Gb Congestion/Utilization at the BSC/PCU. 8. Check Hardware/TRX alarms; Resolve if find any. 9. Audit for any parameters related discrepancies and define as per standard parameters set. After all rectification observe the subsequent days report if you still find the problem repeat the same process with due care to Pin Point the actual cause.
12. PROCESS for Optimization of Downlink Multi-slot Assignment Success Rate: Definition: timeslot request based on traffic types and MS multi-timeslot capability and the actual timeslot allocated by the system which can also be termed as Downlink Multi-slot Assignment Success rate.
PROCESS for Optimization: 1. Identify the Bad performing Cells for Poor DL Multi-slot Assignment. 2. Take the detailed report showing (Ex. Total TBF Requests, Failure in of TS requests) 3. Identify the cells after analyzing detailed report and follow the below mentioned process. 4. Take the configuration dump of the poor cells: a. Check The Static and Dynamic PDCH definition from BSC Configuration data) b. If you find Zero Static or Dynamic PDCH, define the same. c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF Page 15 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. d. Check the multiplexing thresholds and upgrade/downgrade reports. 5. Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive test to analyze the cell in more detail. 6. Check Gb Congestion/PCU-DSP Utilization. 7. Check Hardware/TRX alarms; Resolve if find any. 8. Audit for any parameters related discrepancies and define as per standard parameters set. After all rectification observe the subsequent days report if you still find the problem repeat the Same process with due care to Pin Point the actual cause.
Page 16 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
3
INTERNAL
GSM Timer Optimization
Like any other wireless technology with a limited pool of resources, GSM resource allocation and termination depends primarily on timers. The functionality and protocols may vary, but the presence of timer based signaling and resource allocation is ubiquitous. Timer implementation is present in each domain of the GSM system from MS to NSS end. And most of the important timers will be introduced below on both the sides (MS&NSS).
And Below we will introduce a summary for the timers which it will be composed of 2 parts: 1. A summarization for the timer message. 2. Most of the timer on both the sides the MS & the NSS respectively.
1. Timer Messages description:
Page 17 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
GSM Timers Summarization:
The below timers will describe the main important timer on each side whether Mobile Station side or the Network side.
Timers on the mobile station side:
T3122: This timer is used during random access, after the receipt of an IMMEDIATE ASSIGN REJECT message. Its value is given by the network in the IMMEDIATE ASSIGN REJECT message.
T3124: This timer is used in the seizure procedure during a hand-over, when the two cells are not synchronized. Its purpose is to detect the lack of answer from the network to the special signal. Its value is set to 675 ms if the channel type of the channel allocated in the HANDOVER COMMAND is an SDCCH (+ SACCH); otherwise its value is set to 320 ms.
T3126:This timer is started either after sending the maximum allowed number of CHANNEL REQUEST messages during an immediate assignment procedure. Or on receipt of an IMMEDIATE ASSIGNMENT REJECT message, whichever occurs first. It is stopped at receipt of an IMMEDIATE ASSIGNMENT message, or an IMMEDIATE ASSIGNMENT EXTENDED message. At its expiry, the immediate assignment procedure is aborted. The minimum value of this timer is equal to the time taken by T+2S slots of the mobile station's RACH. S and T. The maximum value of this timer is 5 seconds.
Page 18 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
T3128: This timer is started when the mobile station starts the uplink investigation procedure and the uplink is busy. It is stopped at receipt of the first UPLINK FREE message. At its expiry, the uplink investigation procedure is aborted. The value of this timer is set to 1 second.
T3130: This timer is started after sending the first UPLINK ACCESS message during a VGCS uplink access procedure. It is stopped at receipt of a VGCS ACCESS GRANT message. At its expiry, the uplink access procedure is aborted. The value of this timer is set to 5 seconds.
T3110: This timer is used to delay the channel deactivation after the receipt of a (full) CHANNEL RELEASE. Its purpose is to let some time for disconnection of the main signaling link. Its value is set to such that the DISC frame is sent twice in case of no answer from the network. (It should be chosen to obtain a good probability of normal termination (i.e. no time out of T3109) of the channel release procedure.)
T3134: This timer is used in the seizure procedure during an RR network commanded cell change order procedure. Its purpose is to detect the lack of answer from the network or the lack of availability of the target cell. Its value is set to 5 seconds.
T3142: The timer is used during packet access on CCCH, after the receipt of an IMMEDIATE ASSIGNMENT REJECT message. Its value is given by the network in the IMMEDIATE ASSIGNMENT REJECT message. T3146:This timer is started either after sending the maximum allowed number of CHANNEL REQUEST messages during a packet access procedure. Or on receipt of an IMMEDIATE ASSIGNMENT REJECT message during a packet access procedure, whichever occurs first. It is stopped at receipt of an IMMEDIATE ASSIGNMENT message, or an IMMEDIATE ASSIGNMENT EXTENDED message. At its expiry, the packet access procedure is aborted. The minimum value of this timer is equal to the time taken by T+2S slots of the mobile station's RACH. S and T are defined in section 3.3.1.2. The maximum value of this timer is 5 Sec. T3164: This timer is used during packet access using CCCH. It is started at the receipt of an IMMEDIATE ASSIGNMENT message. It is stopped at the transmission of a RLC/MAC block on the assigned temporary block flow, see GSM 04.60. At expire, the mobile station returns to the packet idle mode. The value of the timer is 5 seconds.
T3190: The timer is used during packet downlink assignment on CCCH. It is started at the receipt of an IMMEDIATE ASSIGNMENT message or of an PDCH ASSIGNMENT COMMAND message when in dedicated mode. It is stopped at the receipt of a RLC/MAC block on the assigned temporary block flow, see GSM 04.60. At expiry, the mobile station returns to the packet idle mode. The value of the timer is 5 seconds.
T3212 (Location update timer): This timer is related with the termination of MM signaling. It starts with the termination of MM signaling. And it timer stops when the message for the initiation of MM signaling is sent to the MS by the BSS entity. Expiry Event: In case the timer expires, a periodic request is sent for the LU update. The default value for this timer is 60 seconds.
Page 19 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Timers on the network side:
T3101: This timer is started when a channel is allocated with an IMMEDIATE ASSIGNMENT message. It is stopped when the MS has correctly seized the channels. Its value is network dependent. NOTE: It could be higher than the maximum time for a L2 establishment attempt.
T3103: This timer is started by the sending of a HANDOVER message and is normally stopped when the MS has correctly seized the new channel. Its purpose is to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the HANDOVER COMMAND, plus the value of T3124, plus the maximum duration of an attempt to establish a data link in multi-frame mode.)
T3105: This timer is used for the repetition of the PHYSICAL INFORMATION message during the hand-over procedure. Its value is network dependent. NOTE: This timer may be set to such a low value that the message is in fact continuously transmitted.
T3107: This timer is started by the sending of an ASSIGNMENT COMMAND message and is normally stopped when the MS has correctly seized the new channels. Its purpose is to keep the old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the ASSIGNMENT COMMAND message plus twice the maximum duration of an attempt to establish a data link multi-frame mode.
T3109: This timer is started when a lower layer failure is detected by the network, when it is not engaged in a RF procedure. It is also used in the channel release procedure. Its purpose is to release the channels in case of loss of communication. Its value is network dependent. NOTE: Its value should be large enough to ensure that the MS detects a radio link failure.
T3111: This timer is used to delay the channel deactivation after disconnection of the main signaling link. Its purpose is to let some time for possible repetition of the disconnection. Its value is equal to the value of T3110.
T3113: This timer is started when the network has sent a PAGING REQUEST message and is stopped when the network has received the PAGING RESPONSE message. Its value is network dependent. NOTE: The value could allow for repetitions of the Channel Request message and the requirements associated with T3101.
T3115: This timer is used for the repetition of the VGCS UPLINK GRANT message during the uplink access procedure. Its value is network dependent. NOTE: This timer may be set to such a low value that the message is in fact continuously transmitted.
T3117: This timer is started by the sending of a PDCH ASSIGNMENT COMMAND message and is normally stopped when the MS has correctly accessed the target TBF. Its purpose is to keep the
Page 20 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the PDCH ASSIGNMENT COMMAND message plus T3132 plus the maximum duration of an attempt to establish a data link in multi-frame mode.
T3119: This timer is started by the sending of a RR-CELL CHANGE ORDER message and is normally stopped when the MS has correctly accessed the new cell. Its purpose is to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the RR_CELL CHANGE ORDER, plus T3134, plus the maximum duration of an attempt to establish a data link in multi-frame mode. T3141: This timer is started when a temporary block flow is allocated with an IMMEDIATE ASSIGNMENT message during a packet access procedure. It is stopped when the mobile station has correctly seized the temporary block flow. Its value is network dependent.
Page 21 of 22 Huawei Proprietary and Confidential 13-06-2016
GSM KPI Optimization Process and Guide
INTERNAL
Thanks
Page 22 of 22 Huawei Proprietary and Confidential 13-06-2016
Related Documents 3m3m1z
Gsm Kpi Optimization Process And Guide 4u3i6q
November 2019 66
Gsm Kpi Optimization 2e5wk
October 2019 51
Umts Kpi Optimization Analysis Guide V1.1 n1n3y
February 2022 0
Gsm Bss Kpi Analysis.pdf 6y6s27
October 2019 36
Gsm Rf Optimization 6q243g
November 2019 46
Gsm Rf Optimization Guidelines o3x1b
November 2019 48More Documents from "Zouhir El Allaoui" 4e224q
Quidway S3000-ei Series Ethernet Switches Command Manual(v1.04) 6n1s71
August 2021 0
High Rtwp Problem Troubleshooting And Optimization Guide 6a475j
April 2020 20
Gsm Kpi Optimization Process And Guide 4u3i6q
November 2019 66
Convention Fiscale Franco-marocaine 4f3b3t
August 2021 0
6l6m1j
October 2020 0