UE Cooperation via Selective LLR Forwarding for Bandwidth-Limited Decoding
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Solution Overview
Problem
Existing user equipment (UE) cooperation methods in wireless networks require extensive bandwidth for forwarding soft information, such as log-likelihood ratios (LLRs), which is inefficient, especially when not all LLRs are necessary for decoding, and can lead to poor performance when not all UEs can decode the original transmission.
Innovation Solution
Implementing a method where cooperating UEs selectively forward only the most useful LLRs to the target UE, reducing the burden on network resources and improving UE cooperation by exploiting frequency selectivity and quantization to minimize bandwidth usage, using techniques like LLR combining and compressing and forwarding strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all LLRs are forwarded to the target UE, then decoding reliability is improved, but bandwidth consumption increases significantly
Solution Approach 1:
The patent extracts and forwards only the most useful LLRs (those with highest magnitude values representing most reliable bits) to the target UE, rather than forwarding all LLRs. This selective extraction maintains decoding reliability while significantly reducing bandwidth consumption for LLR transmission.
Solution Approach 2:
The patent applies partial action by forwarding only a subset of LLRs (those above a certain threshold or top N LLRs) rather than all LLRs. This partial forwarding is sufficient to achieve reliable decoding while consuming less bandwidth than complete LLR transmission would require.
2Reliability
If extensive bandwidth is allocated for LLR forwarding, then UE cooperation performance is improved, but network resource efficiency deteriorates
Solution Approach 1:
The patent extracts only the essential LLR information needed for effective UE cooperation, forwarding only the most useful LLRs to the target UE. This extraction approach maintains UE cooperation performance while reducing the bandwidth resources consumed, thereby improving overall network resource efficiency.
Solution Approach 2:
The patent changes the parameter of LLR transmission by selecting and forwarding only a subset of LLRs based on their usefulness (magnitude threshold or rank). This parameter change in transmission volume maintains cooperation performance while improving network resource efficiency.
3Reliability
If all UEs attempt to decode the original transmission, then decoding coverage is improved, but system complexity increases
Solution Approach 1:
The patent segments the decoding process into two parts: (1) target UE attempts to decode the original transmission directly, and (2) if decoding fails, the target UE requests and receives selected LLRs from cooperating UEs for soft combining. This segmentation improves decoding coverage while managing system complexity by enabling cooperative decoding only when needed.
Solution Approach 2:
The patent introduces a central controller as an intermediary that coordinates the cooperative decoding process. The controller manages LLR selection, determines which cooperating UEs should forward LLRs, and orchestrates the overall decoding assistance process, thereby improving decoding coverage while controlling system complexity through centralized management.
Data Source
AI summary
An embodiment method includes receiving, by a first user equipment (UE), a message, for a second UE, transmitted over a plurality of resource blocks (RBs) on behalf of a communications controller and determining a plurality of log-likelihood ratios (LLRs) in accordance with the received plurality of RBs. The method also includes transmitting, a subset of the determined LLRs to the second UE.