RSSI Measurement for LTE-LAA Interference Assessment

Solution Overview

Problem

Existing RSSI measurement methods in LTE-LAA systems do not effectively differentiate between desired and undesired signals, leading to skewed measurements that are not useful for determining interference from non-serving cells, which affects cell selection and channel selection processes.

Innovation Solution

Measuring RSSI outside of transmission bursts and using Discovery Reference Signal (DRS) timing information to determine the RSSI of non-serving cells, allowing for more accurate interference assessment and channel selection in LTE-LAA environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If RSSI is measured during an LAA transmission burst, then the measured RSSI includes the desired signal from the serving eNB, but the measurement does not provide useful interference information from non-serving cells

Engineering Contradiction:

Improveinterference information from non-serving cellVSAvoidRSSI measurement accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent segments the RSSI measurement process into two distinct parts: (1) measuring RSSI during transmission bursts to capture desired signal strength, and (2) measuring RSSI outside transmission bursts to capture interference from non-serving cells. This segmentation allows the system to separately evaluate and report both components, resolving the contradiction by providing both desired signal information and interference information through distinct measurement opportunities.

Inventive Principle:

Principle #1Segmentation

2Loss of information

If RSSI is measured outside of transmission bursts, then the measured RSSI primarily reflects interference from non-serving cells, but the measurement excludes the desired signal component

Engineering Contradiction:

Improveinterference information from non-serving cellVSAvoidRSSI measurement accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent segments the RSSI measurement process into two distinct parts: (1) measuring RSSI during transmission bursts to capture desired signal strength, and (2) measuring RSSI outside transmission bursts to capture interference from non-serving cells. This segmentation allows the system to separately evaluate and report both components, resolving the contradiction by providing both desired signal information and interference information through distinct measurement opportunities.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the UE averages RSSI measurements over a long period of time, then the measurement includes both desired and undesired signals, but the averaged value does not provide meaningful interference information

Engineering Contradiction:

Improvemeasurement stabilityVSAvoidinterference information from non-serving cell

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent segments the RSSI measurement process into two distinct parts: (1) measuring RSSI during transmission bursts to capture desired signal strength, and (2) measuring RSSI outside transmission bursts to capture interference from non-serving cells. This segmentation allows the system to separately evaluate and report both components, resolving the contradiction by providing both desired signal information and interference information through distinct measurement opportunities.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic measurement opportunities at specific intervals - both during transmission bursts and outside transmission bursts. This periodic action ensures that the UE can systematically collect both desired signal measurements and interference measurements over time, maintaining measurement reliability while preserving the distinction between signal and interference components through regularly scheduled measurement windows.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10812203B2Received signal strength indicator measurement for licensed assisted access

Publication Date: 2020.10.20 APPLE INC

AI summary

In a Long-Term Evolution Licensed Assisted Access (LTE-LAA) environment, Received Signal Strength Indicator (RSSI) measurements may be taken by a User Equipment (UE) outside of transmission bursts of cells in the LTE-LAA environment. For example, a serving cell may indicate transmission burst timing, of the serving cell, via Radio Resource Control (RRC) signaling. Non-serving cells may align transmission burst timing with the outputting of a Discovery Reference Signal (DRS). The serving cell may provide DRS configuration information, which may indicate the timing of the DRS of the non-serving cells. The UE may use the DRS configuration information to measure the RSSI of the non-serving cells outside of their transmission bursts.