Dynamic PIM Cancellation in Wireless Nodes
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Solution Overview
Problem
Wideband wireless communication systems face significant challenges in addressing passive intermodulation (PIM) interference, which degrades receiver sensitivity due to its coupling into the receive band, particularly in systems like LTE and Multi-Standard Radio, as traditional methods such as band planning and engineered PIM sources are inadequate in dynamically tracking and compensating for time-varying interference.
Innovation Solution
A wireless communication node dynamically estimates and cancels PIM interference by using coefficients to model interference generation and coupling, updating these coefficients periodically to reflect changing conditions, and selectively applying cancellation based on error rate feedback or interference statistics, thereby improving receiver performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If band planning and frequency hopping are used to address PIM interference, then PIM interference is reduced in narrowband systems, but these methods are inadequate for wideband systems where PIM components couple directly into the receive band
Solution Approach 1:
The patent implements dynamic PIM cancellation by continuously tracking and estimating PIM interference in real-time, allowing the system to adapt to time-varying interference conditions. The cancellation mechanism is updated periodically to reflect changing interference characteristics, enabling effective operation in wideband systems where static band planning fails.
Solution Approach 2:
The system employs feedback mechanisms to monitor received signals and identify PIM interference components. By analyzing the received signal and comparing it with expected signal characteristics, the system dynamically adjusts cancellation parameters to suppress PIM interference effectively in wideband environments.
2Object-affected harmful factors
If engineered PIM sources are added to statically compensate for PIM, then some PIM cancellation is achieved, but the approach cannot dynamically track time-varying interference
Solution Approach 1:
The patent transforms the static engineered PIM source approach into a dynamic system that continuously tracks interference variations. The cancellation mechanism is periodically updated to reflect real-time interference conditions, enabling the system to adapt to time-varying PIM characteristics that static compensation cannot address.
Solution Approach 2:
The system performs preliminary estimation of PIM interference characteristics during periods when no data transmission occurs, using these estimates to configure cancellation parameters before actual data reception begins. This preliminary action enables the system to be prepared for dynamic interference conditions.
3Object-affected harmful factors
If all PIM components are cancelled, then complete interference suppression is achieved, but computational costs increase significantly
Solution Approach 1:
The patent applies cancellation selectively to the most harmful PIM components, specifically targeting 3rd-order intermodulation products that couple directly into the receive band. By focusing computational resources on the most critical interference components rather than attempting to cancel all PIM components, the system achieves effective interference suppression with reduced computational complexity.
Solution Approach 2:
The system implements partial cancellation by addressing only the dominant PIM components that cause the most significant interference. This partial action approach provides sufficient performance improvement while avoiding the prohibitive computational costs of complete PIM cancellation across all frequency components.
Data Source
AI summary
A wireless communication node (10) dynamically estimates passive intermodulation (PIM) interference coupled into the node's receive path from the transmission of a composite signal through the node's transmit path. The node (10) then cancels the estimated PIM interference in the receive path. In some embodiments, the node dynamically estimates the PIM interference as a function of the composite signal that models PIM interference generation and coupling in the node (10) according to one or more coefficients (30). The coefficients (30) may be determined by transmitting a test signal (34) during a test stage, when the node (10) is not scheduled to receive any signal. Later, when the composite signal (18) is transmitted, the node (10) uses the coefficients (10) to dynamically estimate and cancel the resulting PIM interference.