Mitigating Intermodulation Interference in Wireless Carrier Measurements
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Solution Overview
Problem
Wireless communication systems face inaccuracies in mobility measurements due to self-interference caused by intermodulation products when multiple carriers are used for uplink transmissions, leading to degraded performance and mobility issues.
Innovation Solution
The system identifies a carrier for potential uplink communications, determines a measurement configuration to account for expected intermodulation interference by selecting time periods with no scheduled uplink transmissions, reduced transmit power, or specific frequency locations with lower interference, and measures the carrier quality within these configurations, allowing for accurate mobility measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple carriers are used for uplink transmissions, then communication capacity and data rate are improved, but self-interference from intermodulation products degrades measurement accuracy
Solution Approach 1:
The patent segments the measurement process by identifying specific time periods (measurement opportunities) when intermodulation interference is absent or reduced. The UE divides uplink transmission time into measurement periods and non-measurement periods, performing carrier quality measurements only during favorable periods when other UEs are not transmitting, thereby separating the measurement function from the interference-prone transmission function.
Solution Approach 2:
The patent applies preliminary action by having the network configure the UE with measurement configurations in advance, including identification of measurement opportunities, frequency locations, and power thresholds. The UE receives and stores this configuration before actual measurements are performed, allowing it to proactively prepare for accurate measurements during predetermined time windows when interference conditions are favorable.
2Reliability
If uplink transmit power is increased, then signal strength and communication reliability are improved, but intermodulation interference increases causing measurement degradation
Solution Approach 1:
The patent changes the power parameter dynamically by configuring the UE with a power threshold that distinguishes between acceptable and unacceptable interference levels. The measurement configuration includes this threshold to determine whether current transmit power conditions are suitable for accurate measurements, allowing the system to adapt measurement timing based on actual power conditions rather than using fixed measurement schedules.
3Measurement precision
If continuous carrier quality measurements are performed, then mobility decision accuracy is improved, but system complexity and power consumption increase
Solution Approach 1:
The patent implements periodic action by establishing regular measurement opportunities at predetermined time intervals rather than continuous measurements. The network configures periodic measurement occasions where the UE suspends uplink transmissions temporarily to perform measurements, creating a rhythmic pattern of transmit-measure-transmit that reduces complexity while maintaining adequate measurement frequency for mobility decisions.
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A user equipment (UE) may mitigate self-interference and intermodulation products caused by communicating over two carriers in order to improve measurements of a third carrier. The UE may determine a measurement configuration to determine the quality of the third carrier. The measurement configuration may include identifying time periods with no scheduled uplink transmissions, time periods with a transmit power below a power threshold, time periods with frequency locations with an expected lower intermodulation interference, or time periods with a scheduled reference signal transmission (e.g., a synchronization signal (SS) block). The UE may also reduce a transmit power for a time period or drop a scheduled uplink transmission in order to perform more accurate measurements on the third carrier. In some cases, a base station may schedule a measurement gap for the UE to perform the measurements.