Downlink Interference Cancellation via Constrained Decoding Hypotheses
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Solution Overview
Problem
Wireless communication systems face significant challenges in mitigating downlink interference, particularly in heterogeneous deployments where user equipment (UE) connects to weaker base stations, leading to increased interference that hampers signal reception and network performance.
Innovation Solution
The approach involves reducing the number of blind hypotheses required for decoding downlink transmissions by constraining the set of available parameters used by interfering base stations, such as scrambling/encoding radio network identifiers and downlink grant resources, allowing wireless devices to process a manageable number of decoding hypotheses and cancel interfering signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If user equipment connects to weaker base stations in heterogeneous deployments, then network coverage and connectivity are improved, but downlink interference increases and signal reception deteriorates
Solution Approach 1:
The patent converts the harmful interfering signal from the interfering base station into a useful signal by decoding and canceling it at the user equipment. The UE decodes the downlink transmission from the interfering base station using constrained parameters, reconstructs the interfering signal, and subtracts it from the received composite signal, thereby eliminating the harmful interference and improving signal reception.
2Adaptability or versatility
If the set of available parameters for decoding is expanded to handle diverse base station transmissions, then adaptability improves, but the number of blind hypotheses and decoding complexity increase exponentially
Solution Approach 1:
The patent applies local quality by constraining the set of parameters to specific local properties that are relevant for interference cancellation. Instead of considering all possible parameters across the entire parameter space, the UE focuses on a constrained set including radio network identifiers, downlink grant resources, and modulation and coding schemes that are locally relevant to the interfering base station's transmission.
Solution Approach 2:
The patent segments the decoding process into distinct stages: first decoding the control channel to obtain downlink grant information, then using this information to constrain the parameter set for data channel decoding. This segmentation breaks down the complex blind decoding problem into manageable steps, reducing overall decoding complexity.
3Measurement precision
If the number of blind decoding hypotheses is increased to cover all possible transmissions, then measurement precision improves, but processing time and computational load increase significantly
Solution Approach 1:
The patent applies preliminary action by first decoding the control channel to obtain downlink grant information before attempting to decode the data channel. This preliminary decoding provides crucial information about the interfering transmission parameters, which constrains the set of hypotheses needed for data channel decoding and significantly reduces the time and computational resources required.
Solution Approach 2:
The patent uses feedback from the control channel decoding results to adjust and constrain the parameter set for data channel decoding. The downlink grant information obtained from the control channel provides feedback that narrows down the possible transmissions, reducing the number of blind hypotheses needed while maintaining detection accuracy.
Data Source
AI summary
A method to mitigate interference in a wireless system is provided. The method includes processing a set of radio network identifiers and limiting a number of hypotheses associated with the radio network identifiers in order to mitigate interference in a wireless network. In another aspect, the method includes processing a set of hypotheses and limiting the set of hypotheses by limiting a number of downlink grants to a common space, limiting the number of downlink grants to a number of instances, or limiting the number of grants to a physical downlink control channel (PDCCH) type. In yet another aspect, the method includes processing a downlink set and generating a target termination level for the downlink data set, the termination level associated with a Hybrid automatic repeat-request.