UE Interference Cancellation for Accurate CSI in Heterogeneous Networks
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Solution Overview
Problem
Existing LTE Rel-8/9 UE measurement frameworks are inadequate for accurately determining interference scenarios in heterogeneous networks, leading to inaccurate RRM, RLM, and CSI measurements, resulting in erratic behaviors, failed connections, and inefficient spectral resource utilization due to interference from femto and macro cells.
Innovation Solution
Implementing enhanced inter-cell interference coordination techniques, including the use of Almost Blank Subframes (ABS) and advanced receiver capabilities such as interference rejection and cancellation, to configure restricted subframe measurement patterns that allow UEs to perform measurements during subframes with minimal interference, and modifying RSRQ and CSI measurements to account for interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing LTE Rel-8/9 UE measurement frameworks are used, then device complexity is maintained at acceptable levels, but measurement precision deteriorates due to interference from femto and macro cells in heterogeneous networks
Solution Approach 1:
The patent applies preliminary action by performing interference cancellation before measurement processes. The receiver cancels out interfering signals from femto and macro cells prior to conducting RRM, RLM, and CSI measurements, thereby improving measurement accuracy without requiring complex post-processing. This pre-processing approach eliminates interference effects that would otherwise degrade measurement precision.
Solution Approach 2:
The patent converts the harmful interference from femto and macro cells into a beneficial measurement process. By implementing interference cancellation techniques, the receiver transforms the presence of interfering signals into an opportunity to characterize and eliminate them, thereby improving measurement accuracy. The interference that would normally degrade measurements is instead used to train cancellation algorithms that enhance measurement precision.
2Reliability
If interference cancellation techniques are implemented, then measurement accuracy improves, but device complexity increases due to advanced receiver capabilities
Solution Approach 1:
The patent performs interference cancellation in advance of connection establishment and measurement processes. By pre-canceling interfering signals, the system ensures more reliable connections without requiring complex real-time processing during critical communication phases. This preliminary interference mitigation improves connection reliability while managing device complexity through staged processing.
Solution Approach 2:
The patent converts harmful interference into improved connection reliability by using interference cancellation techniques. The receiver processes interfering signals to extract and remove their effects, transforming what would be connection-degrading interference into a mechanism that enhances connection stability and reliability in heterogeneous network environments.
3Measurement precision
If measurements are performed during all subframes, then measurement speed is maintained, but measurement precision deteriorates due to interference from non-blank subframes
Solution Approach 1:
The patent extracts and isolates measurements to be performed only during blank subframes, separating them from interfering non-blank subframes. By taking out the measurement process from contaminated time periods and confining it to clean blank subframes, the system improves measurement precision without requiring continuous measurement across all subframes, thereby managing the time loss through selective measurement placement.
Solution Approach 2:
The patent applies local quality by assigning different measurement qualities to different subframe types. Blank subframes are designated as high-quality measurement opportunities with minimal interference, while non-blank subframes are excluded or treated differently. This localized approach to measurement quality ensures high precision during selected subframes while accepting that not all subframes contribute equally to measurement accuracy.
Data Source
AI summary
A wireless communication terminal is disclosed. The terminal includes a transceiver coupled to a processor configured to determine that a subset of a plurality of resource elements (REs) must be excluded from demodulation, the plurality of REs received in a signal from a first base station, to estimate a hypothetical block error rate (BLER) based on the signal received from the first base station by excluding the subset of the plurality of REs, and to estimate channel state information based on the hypothetical BLER.