Low Payload and DL PRB utilization but still Low Throughput

RAN
1

Hello All.

I have 1/3 cells with Payload <1 GB and DL PRB utilization 20 %, but Throughput < 1.5 Mbps in capacity layer.

Coverage layer carrying good Throughputpt and Payload & PRB.

What can be the issue?

2

Are you sure there no hardware faulty over the site ?

Did you make Drive test around the site to check it’s performance?

3

These are the typical symptoms of:

  1. Cell has hardware issue such as VSWR

  2. There is strong interference and hence spectral efficiency is low (SE lower than 1 bit/sec/hz usually means there is DL interference). You can check pusch/pucch SINR and RSSI for UL interference.

3.There is license shortage. For example DL baseband capacity license is not enough and it is not possible to use maximum capacity of the baseband board.

  1. Cell is overshooting such that there are only a handful of cell edge users served by this cell. They will not generate high amount of payload but cause low throughput.

Parameter discrepancy is also a possibility. For example your capacity layer has discrepeancy in MIMO setting and maximum Rank is limitted.

1 Like
4

what will be reason for PRB is 70% , payload <1GB, DL cell thpt < 1.5 mbps ?

those cells what will be reason?

5

Below some points about low throughput issue to be checked:

  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.

  21. High traffic on Cell limit THp

Radio Analysis . Downlink :

  1. CQI (Channel Quality Index) and RI (Rank Indicator) reported from UE.
  2. Transmission Mode: MIMO (tm3) vs. TxD (tm2) vs. SIMO (tm1)
  3. MCS vs. number of assigned PRBs vs. assignable bits in scheduler
  4. UE Scheduling percentage of TTIs (how often is the UE scheduled)
  5. CFI (number of OFDM symbols for PDCCH) vs. MCS vs. % scheduling
  6. HARQ
    28-RLC retransmissions
  7. Another cause of low (or lower than expected) throughput is that the UE is not being scheduled in every TTI.
    –Packet loss can lead to (retransmissions, dropped in RBS, etc)

Radio Analysis – Uplink :

  1. Uplink scheduling overview
  2. BSR (Buffer Status Report)
  3. PHR (Power Headroom Report) – is the UE at maximum power?
  4. Cell bandwidth vs. maximum allowable PRBs
  5. Link Adaptation
  6. MCS available and 16QAM
  7. PDCCH SIB scheduling colliding with UL grant
  8. HARQ (less important, because we can measure SINR)
  9. QPSK cases in UL has increased from ~30% to ~40%. If more QPSK cases then there are more UEs in poor radio conditions

Credits: :point_down:

6

thank you.