LTE Coverage Optimisation : How to improve coverage in LTE radio network in UL and DL

Summary

This video script delves into LTE Coverage optimisation, crucial from planning to ongoing phases of an LTE network. It covers detection of uplink and downlink coverage issues, imbalances, overshooting, overlapping, and cell border adjustments. The script explains using KPIs and elements like RSRP and power headroom for detection, and discusses techniques to manage overlapping and overshooting. It also addresses DL/UL imbalances, TX imbalances, and the use of specific parameters for coverage extension and adjustment. The goal is to equip viewers with the knowledge to optimize LTE coverage and parameters effectively.

Takeaways

• 📡 Detecting LTE Coverage Issues: RSRP less than -120 dBm indicates a coverage hole, while RSRP less than -105 dBm signifies weak coverage.
• 🔍 Balance Between Coverage and Interference: Optimizing LTE requires a balance to avoid increasing interference with transmission power.
• 🚗 Drive Testing for Coverage Holes: Drive testing can identify handover failures and areas with coverage issues, including IRAT handovers.
• 📶 Uplink Coverage Detection: Power headroom reports from UE to eNodeB can indicate weak uplink coverage when UE is transmitting at maximum power.
• 🔄 Overlapping and Overshooting Problems: Overlapping occurs when there is no dominant server leading to interference, while overshooting is when signals reach unintended areas.
• 🛠️ Adjusting Overlapping: Techniques like azimuth change, E-tilting, height reduction, and power adjustments can control overlapping issues.
• 🔎 Detecting Overshooting: Drive testing and propagation delay matrices can help identify overshooting and its impact on handover failures.
• ⚖️ DL and UL Imbalance Detection: UL imbalance is common, indicated by good DL coverage but poor UL performance, while DL imbalance is the opposite.
• 🔄 TX Imbalance Issues: Different performance between multiple radio transmission elements can point to hardware or cable issues.
• 🌐 Extended Cell Coverage: LTE can extend up to 100km using specific PRACH formats and special subframe configurations, but may face issues like time delay and low SINR.
• 🔄 Cell Border Adjustment: Parameters like qrxlevmin and a2threshold can be adjusted to optimize cell coverage areas based on network requirements.

Q & A

What is the main focus of the video script provided?

The main focus of the video script is LTE Coverage optimisation, covering various aspects from initial planning to ongoing optimisation of an LTE network.

What are the key topics discussed in the script for LTE coverage optimisation?

The key topics discussed include detecting UL and DL coverage problems, imbalance between downlink and uplink, overshooting and overlapping problems, extended coverage, cell border adjustment, and parameters for optimising LTE.

What is considered a coverage hole in terms of RSRP?

In terms of RSRP, a coverage hole is defined as an area where the RSRP is less than -120 dBm.

How can imbalance between downlink and uplink be detected?

Imbalance can be detected through various methods such as observing handover failures, low throughput, and specific KPIs related to IRAT handovers, as well as analyzing power headroom reports and SINR thresholds for Physical Uplink Shared Channels (PUSCH).

What is overshooting in the context of LTE coverage?

Overshooting occurs when signals from the base station reach areas where they are not supposed to, resulting in more coverage than predicted or expected, which can cause issues with handovers.

What are some methods to control overlapping issues in LTE coverage?

Methods to control overlapping issues include azimuth change, E-tilting, height reduction, adjusting the power of the reference signal, and modifying the power used by shared channel, PDCCH, and RS.

How can extended cell coverage be achieved in LTE?

Extended cell coverage can be achieved by using specific PRACH formats and special subframe formats that allow for coverage of different radii, up to the maximum cell radius as per 3GPP standards.

What are the potential issues that can arise from extending cell coverage?

Potential issues include increased time delay, loss of orthogonality of the Zadoff-Chu (ZQ) sequence preamble due to long delays, and low SINR for PRACH and other channels due to large distances.

What parameters are used to adjust cell coverage borders in LTE?

Parameters used to adjust cell coverage borders include qrxlevmin, which is the minimum RSRP required to access an LTE cell, and a2threshold, which is the RSRP threshold after which the LTE UE would switch to WCDMA due to weak LTE coverage.

What is the purpose of PDCCH boost in LTE coverage optimization?

PDCCH boost is used to provide coverage to the Physical Downlink Control Channel (PDCCH) because it does not use beamforming or advanced antenna techniques like the downlink shared channel, resulting in a coverage gap.

What are some of the downlink parameters discussed in the script for LTE coverage optimization?

Some of the downlink parameters discussed include qrxlev, reference signal power, P alpha, P beta, and the parameters for uplink power control such as pnominal PUCCH and pnominal PUSCH.