To improve SINR in 4G, first we must understand what it is and how to measure it. SINR is not specifically defined in 3GPP specifications since the SINR is an internal measurement done by most UEs for drive test tools, hence this value is not reported back directly to the network. Nevertheless the CQI is usually measured based on the SINR. To improve the SINR in 4G, first we must understand A common formula is as follows: SINR = S/(I + N)  where:

• S: Indicates the power of measured usable signals. Reference signals (RS) and physical downlink shared channels (PDSCHs) are mainly involved.
• I: Indicates the power of measured signals or channel interference signals from other cells in the current system and from inter-RAT cells. Ø
• N: Indicates background noise, which is related to measurement bandwidths and receiver noise coefficients.

Signal to Interference plus Noise Ratio (SINR) is measured by UE on Resource Block (RB) basis. UE computes SINR on each RB, converts it to CQI and reports it to eNodeB where it uses to select the most suitable MCS for user data transmission in particular RB. SINR value defines the MCS used for a RB. So SINR defines the ratio of the signal power to the total interference power from the other cells and the background noise.

To improve SINR in 4G, lets review the typical values to consider when performing optimization:

In this post lets review the most basic and important tasks to improve SINR in 4G networks (Signal to Noise Ratio).

• Control coverage of the cluster. All cells should have a coverage as planned. Remove all overshooting cells causing pilot pollution. Each cell should have a clear coverage footprint without overlapping coverage of other sites/cells.
• Analyze the PCI planning. The planning should follow the MOD3 rule (for MIMO cells) so adjacent cells in the same site cannot have PCI with the same MOD3. For SISO cells, you can follow the MOD6 rule.
• Check the ICIC (Inter-Cell Interference Coordination) feature and deploy it only if it works in a test cluster.
• Check the traffic balance between different carriers. Avoid overloading cells by ensuring the right traffic balance. High load cells impact directly into the SINR by increasing the noise level for neighboring cells.
• Check if the compatibility switch is active Tm3Tm4Max4LayerCtrlSwitch.
• Change PA / PB for different power configuration. For better coverage, try PA, PB = -3, 1. For throughput improvement try 0, 0.
• Detect and eliminate external sources of interference. To determine the source, you can use a Frequency scanner in the neighboring area.
• Increase Intra-Freq handover hysteresis and offset to reduce ping pong handovers.

Interesting links:

• https://rfoptima.com/2024/05/01/learn-pci-optimization-to-be-a-4g-rf-expert/
• https://rfoptima.com/2024/05/15/4g-rf-measurement-quantities-you-need-to-know/
• https://rfoptima.com/2024/03/01/4g-rf-optimization-processes/
• https://www.telecomhall.net/t/what-are-the-normal-range-of-kpi-like-sinr-rsrp-and-rsrq-in-a-lte-network-for-a-fair-performance/15091
• https://www.telecomhall.net/t/difference-between-sinr-and-cinr/9464
• https://en.wikipedia.org/wiki/Signal-to-interference-plus-noise_ratio