What are main reasons of Low Throughput in 4G LTE?

[Crazy_engineer21]

What are main reasons of Low Throughput in 4G?

There are too many Reason is possible

What’s the BW configured in transmission level?

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 - Avaibility issue
3 - Uplink Interference
4 - A poor RACH deconding SR
5 - High error on S1 link.
6 - Delay on S1 link towards MME & SGW.
7 - Accessiblity issue.
8 - Handover failure.
9 - Lack of PRBs.
10 - Problemtic 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 insability & bottleneck.
19 - Incorrect parameter setting.
20 - Badly tuned handover parameters.
21 - High traffic on Cell limit THp
Radio Analysis - Downlink
22 - CQI (Channel Quality Index) and RI (Rank Indicator) reported from UE.
23 - Transmission Mode: MIMO (tm3) vs. TxD (tm2) vs. SIMO (tm1)
24 - MCS vs. number of assigned PRBs vs. assignable bits in scheduler
25 - UE Scheduling percentage of TTIs (how often is the UE scheduled)
26 - CFI (number of OFDM symbols for PDCCH) vs. MCS vs. % scheduling
27 - HARQ
28 - RLC retransmissions
29 - 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
30 - Uplink scheduling overview
31 - BSR (Buffer Status Report)
32 - PHR (Power Headroom Report) – is the UE at maximum power?
33 - Cell bandwidth vs. maximum allowable PRBs
34 - Link Adaptation
35 - MCS available and 16QAM
36 - PDCCH SIB scheduling colliding with UL grant
37 - HARQ (less important, because we can measure SINR)
38 - QPSK cases in UL has increased from ~30% to ~40%. If more QPSK cases then there are more UEs in poor radio conditions

Bad RSRP and RSRQ -
Issue reasons and solutions please

If Rsrp and Rsrq together goes to bad, it means there is weak coverage or weak signalization. Need to check antenna position and which site/cells should serving to there , mostly it is causes by weak coverage… Secondary issue is possible to there is handover problem among cells due to very aggresive handover parameter settings… So handover requests goes to late.
Look at parameter settings

[RFGirl]

This is really great list.

Any update? (new item in list?)

[Edo_Saragih]

Hi everyone,
I have a question. The DT results we did got PDCP Tput below 3mbps but RLC and MAC Tput are good above 30mbps What is the cause?

[rahulkaundal]

Low throughput in LTE networks can be attributed to various factors, both within the network and at the user equipment (UE) level. Here are some common reasons for low throughput in network:

1. Poor Signal Strength: Weak signal strength) can significantly impact throughput. This can occur due to distance from the cell tower or obstacles like buildings or terrain etc.

2. Interference: Interference from neighboring cells, adjacent frequency bands, or other radio sources can degrade signal quality and reduce throughput. Too large overlapping coverage area leads to high RSSI and creates pilot pollution. There are sometimes external interference issues too.

3. Improper Network Settings – Improper setting of key parameters such as modulation (higher modulation not enabled), antenna configuration, transmission mode, bandwidth etc. can lead to low throughput.

4. Hardware/Software issue – Malfunctioning at hardware such as radio, baseband unit along-with CIPRI cable, SFP, outdated SW,

5. Network Congestion: High user demand or congestion in the network can lead to reduced throughput, especially during peak hours or in densely populated areas. This congestion can occur at various network elements such as the radio interface, core network, or backhaul links.

6. Errors over air interface: Errors caused by channel impairments, fading, or environmental conditions can result in retransmissions, reducing overall throughput.

7. Backhaul Limitations: Inadequate backhaul capacity or congestion in the backhaul network can bottleneck data traffic and reduce throughput. Check media provisioning end to end till ISP.

8. Packet Loss and Latency: High packet loss and latency can impact the efficiency of data transmission and reduce overall throughput, especially for real-time applications like video streaming or online gaming.

UE Capability: The capabilities of the user equipment, such as antenna design, processing power, and modem capabilities, can also affect throughput. Older devices or devices with inferior specifications may experience lower throughput compared to newer, more advanced devices.

Addressing low throughput issues in LTE networks typically involves a combination of network optimization techniques, capacity upgrades, spectrum management, interference mitigation strategies, and ensuring optimal UE performance. Continual monitoring, analysis, and optimization are essential to maintain satisfactory throughput levels and ensure a positive user experience in LTE networks.

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