Factors Affecting Throughput in LTE :- Low mcs, Low sinr, Low rsrq , high prb usage, wrong earfcn Definition, no Carrier aggregation ör missing ca configuration, Pci , Route sequence index collision, Wrong tac planning, gateway security problem, etc. air quality (now sinr, rsrq, etc etc), modulation level. For example, 16QAM, 64QAM, etc. Low Throughput Issue:- 1 - Poor coverage (BLER) 2 - Availability issue 3 - Uplink Interference 4 - A poor RACH decoding SR 5 - High error on S1 link. 6 - Delay on S1 link towards MME & SGW. 7 - Accessibility issue. 8 - Handover failure. 9 - Lack of PRBs. 10 - Problematic UE. 11 - Downlink Interference (Bad CQI) 12 - MIMO Parameters 13 - High VSWR 14 - High radio errors or instability issue. 15 - Maximum number of RRC connections active per cell 16 - Maximum number of users per TTI supported per cell. 17 - Core network, MME/SGW, etc 18 - Transmission instability & bottleneck. 19 - Incorrect parameter setting. 20 - Badly tuned handover parameters...
lets starts todays topic that is Low signal strength analysis
What could be the probable cause of low signal while you drive or optimize.
First see the following flow chat and try to understand the things
Remember that Low Signal strength is one of the reason of drop call. It can be indicated by many calls disconnected at low signal strength by subscriber, drop calls due to excessive TA, poor handover performance and poor call setup performance.
What could be the probable reasons
Probable Reason
- Poor BSC Exchange Property setting
High LOWSSDL & LOWSSUL will give more drop reason due to SS and this might not show the actual drop. It is because drop due to SS is more priority than Quality.
- No dominant cell
Cell might be isolated or standalone.
- Antenna tilt & orientation
Too much downtilt sometimes might not cover a larger area and the subscriber might lose the SS.
- Output Power
Low output power might cause smaller border cell(Power decreased for some specific reason)
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Just try to observed what could be the right cause :-
The following procedure should be performed for low signal strength
analysis:
1:
Identify the baseline requirement of design and BSC exchange property (setting for LOWSSUL/LOWSSDL).
2:
Check the value for LOWSSDL & LOWSSUL. If it is higher than ACCMIN, change the parameter to a reasonable value since the drop reason will be more priority to SS compared to Quality.
3:
Check the site position, antenna direction, position etc. This is to ensure the possible location is open to interference (open water environment) or isolated. Good map is needed for this.
4:
Check if the site is sectorized or Omni. If it is Omni, set the cell into sectorized cell.
5:
Check if the signal strength is uplink or downlink limited. Mostly, It is designed to be downlink limited.
6:
Check the coverage cover expected area from the planet. If it is not, check the antenna tilt and orientation. Change the direction or tilt if it is too much downtilt or pointing to a wrong direction.
7:
Sometime, low output power might cause low SS. Check output power and if it is low, increase the output power.
8:
Check cell whether it has hotspots from drivetests. If found, adding new site is recommend.
9:
In order to check power distribution, run Cell Traffic Recording (CTR) to that particular cell.
10:
Check if the cell has indoor coverage problem. If yes, add micro site instead.
Need Your suggestions and doubts and let me know if problem is still there...
happy learning
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