Network Optimization process involves the following activities: •
FIRST SET THE CRITERION (GOAL) OF OPTIMIZATION PROCESS o BASELINE & TARGET KPI’s. o DELIVERABLES
• • • • •
CONDUCTING A BASELINE PHYSICAL AUDIT REMOVING ALL SERVICE AFFECTING ALARMS IDENTIFYING POOR COVERAGE AREAS IDENTIFYING CAPACITY CONSTRAINTS & OVERUTILIZED CELLS VARIOUS KPIs with Root-Cause-Analysis of problems. o o
Frequency Plan (BCCH & TCH) Neighbor plan
CONDUCTING A GSM SYSTEM PARAMETERS AUDIT Deliverables of an Optimization activity: o o
Baseline Drive test comparison with post implementation results. Statistical comparison of baseline & improved network.
o Parameter Audit report. o Physical parameter inconsistencies. o Frequency & neighbor plan inconsistencies o Recommendations for
Coverage Capacity Physical Optimization Location Area Optimization.
This sections contains information to control & optimize the following w.r.t. Nokia Systems 1. SDCCH Drop 2. SDCCH Blocking (See SD Drop) 3. TCH Drop 4. Handover Failures 5. TCH Blocking (See Handover Failure) 6. Downlink Quality 7. Uplink Quality
Probable Reasons for SD Drop
• • • • • • • • • A bis failure. Path unbalance between DL/UL caused by difference in sensitivity between BTS & MS. Co-BCCH Frequency and BSIC in the nearby BTS Cells in a Coverage area. SDCCH defined on TRX having poor path loss. High Interference level. High SD congestion. Greater Rx level access min. Due to heavy location updates on the cell. Hardware Issues.
SD Drop Check Points
1. A bis failure. a. Check PCM Errors and carry out PCM Checks on regular Basis 2. Path unbalance between DL/UL caused by difference in sensitivity between BTS & MS. 3. Co-BCCH Frequency and BSIC in the nearby BTS Cells in a Coverage area. a. Clearing ZEAT on regular Basis. All Network Effecting Alarms to be monitored for Clearance. 4. SDCCH defined on TRX having poor path loss. a. ND Report 208 – Shift SDCCH from the TRX with Poor Path Loss/Get the Hardware Checked. 5. High Interference level a. ND Report 190 – Get it Checked for any Uplink Interference, SD requires better C/I.
6. SD congestion.
a. Allocate Dynamic SDCCH if needed or increase SD Allocation seeing the TCH Traffic. b. If SDCCH congestions occurs accompanied with High HO Failures, check the LAC of the source cells & its neighbors. Try to avoid many HO to different LAC if cell is not at the boundary f the LAC. If the cell is at the boundary & neighbor definitions are all OK, then you must check if a LAC re-dimensioning of the problem area is required. In addition to LA, you should also be able to visualize your RA(Routing area) boundaries. If there’s significant movement of Data users across this LA/RA boundary then RA need to be dimensioned accordingly. c. SD Congestion could also be caused by certain large quantity SMS user (Banks, stock brokers etc). This congestion would appear only at specific time intervals. Increase the SD in the cell to peak requirements of the cell. 7. Greater Rx level access min. a. Less than -102dBm. MS should Access the Network in good Coverage Area. 8. Due to heavy location updates on the cell. a. Increase Cell Reselect Hysterises up to -10db (Mostly on BSC Location Boundaries). b. Increase location area update timer from 4 to 6 Hrs. 9. BTS Hardware Issues, All Connector Checks to be done for BTS and Antenna Cable Path to be checked till Antenna Port. Any major Alarm on ZEOL to be monitored and Cleared.
Probable Reason for TCH Drop
1. 2. 3. 4. 5. 6. 7. 8. Interference level. Poor coverage. Poor path loss between different TRX. Poor adjacencies definition. Transcoder failure. Abis failure (PCM related faults). BTS Hardware Issues. High TA Value/Calls Originated by far of Areas (Big Coverage Area for respective Cells).
TCH Drop Check Points
1. Interference level a. To reduce CI for the respective Network Cells. Frequency Plan Checks for achieving better...