Adaptive Interference Cancellation for Wireless PDSCH Reception

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In wireless communication systems, user equipment (UE) experiences interference from nearby access nodes broadcasting cell-specific reference signals (CRS) that occupy resource elements of the serving access node's physical downlink shared channel (PDSCH), leading to difficulties in receiving scheduled data transmissions, especially in dynamic spectrum sharing scenarios where multiple access nodes operate on overlapping frequency carriers.

Innovation Solution

The UE detects nearby access nodes with comparable signal strength and CRS occupying its serving access node's PDSCH resource elements, generates a copy of the interfering CRS signal, and subtracts it from received PDSCH transmissions to cancel out interference, adapting this process for multiple interfering cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple access nodes operate on overlapping frequency carriers in dynamic spectrum sharing scenarios, then spectrum utilization efficiency is improved, but CRS interference to PDSCH reception increases

Engineering Contradiction:

Improvespectrum utilization efficiencyVSAvoidCRS interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful CRS interference into a beneficial signal by having the UE detect, generate copies of, and subtract the interfering CRS from received PDSCH transmissions. This transforms the interference problem into a solvable signal processing task, allowing spectrum sharing to continue while mitigating the harmful effects of overlapping CRS transmissions from nearby access nodes

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the parameter of signal processing by introducing adaptive interference cancellation at the UE side. The UE dynamically adjusts its reception processing by generating copies of interfering CRS signals based on detected parameters (PCI, resource element positions) and subtracting them from received signals, thereby adapting to varying interference conditions while maintaining spectrum sharing operations

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the UE receives PDSCH transmissions from the serving access node, then data reception capability is maintained, but interference from nearby access nodes' CRS degrades reception quality

Engineering Contradiction:

Improvedata reception capabilityVSAvoidCRS interference from nearby access nodes

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces an intermediary signal processing step where the UE generates a copy of the interfering CRS signal and uses it as a mediator to cancel the interference. By creating this intermediate representation of the interference signal, the UE can selectively remove only the harmful portions while preserving the desired PDSCH signal

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If the UE detects and cancels interfering CRS signals, then interference reduction is achieved, but processing complexity increases

Engineering Contradiction:

ImproveCRS interference levelVSAvoidsignal processing complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies partial action by having the UE selectively cancel interference from a limited number of detected nearby access nodes rather than attempting to cancel all possible interferers. The UE identifies candidate interferers based on detection criteria and processes only those that meet the thresholds, thereby reducing processing complexity while still achieving significant interference reduction

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent uses copying by having the UE generate copies of the detected CRS signals from nearby access nodes. Instead of directly processing the complex interference cancellation mathematics, the UE creates simplified copies of the interfering signals based on detected parameters and subtracts these copies from the received signal, reducing computational complexity

Inventive Principle:

Principle #26Copying

Data Source

PatentUS11399380B1Adaptive interference cancellation in a wireless communication system

Publication Date: 2022.07.26 SPRINT SPECTRUM LLC

AI summary

An adaptive interference cancellation method is disclosed. In an example, when a UE is served in a first cell by a first access node, the UE detects a second cell provided by a second access node that is not serving the UE. Further, responsive to the detecting, the UE determines that both (i) a broadcast CRS of the second cell occupies air-interface resource elements that the first access node uses as part of a PDSCH of the first cell and (ii) the UE has coverage strength of the second cell that is threshold similar to coverage strength that the UE has from the first access node. And, responsive to the determining, the UE cancels from scheduled PDSCH transmission from the first access node to the UE, potential interference attributable to the broadcast CRS of the detected second cell, such as by reconstructing and subtracting the CRS from the PDSCH transmission.