Wireless Link Adaptation Using BLER-Based ICC Adjustment
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Solution Overview
Problem
Existing link adaptation methods in wireless communication networks face challenges such as high NACK ratios due to UE processing delays, inaccurate channel estimation, and interference from control channels, leading to suboptimal throughput.
Innovation Solution
A method for link adaptation that involves obtaining an initial Information Carrying Capacity (ICC) estimate and measuring Block Error Rate (BLER) per rank, Modulation and Coding Scheme (MCS), and slot, with the ability to adjust the ICC estimate and disable outer loop adjustments based on BLER and ACK/NACK feedback to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional link adaptation algorithms are used with fixed BLER targets, then the system maintains simplicity in implementation, but throughput is reduced due to high NACK ratios caused by UE processing delays and interference
Solution Approach 1:
The patent implements dynamic BLER targets that adapt based on transmission conditions, UE processing capability indicators, and channel state information. Instead of using a fixed BLER target, the system adjusts the target dynamically to match actual channel conditions and UE capabilities, thereby improving throughput while maintaining reliable link adaptation decisions.
Solution Approach 2:
The patent introduces enhanced feedback mechanisms where UEs provide processing capability indicators and detailed channel state information. The base station uses this feedback to adjust BLER targets and link adaptation parameters, creating a closed-loop system that continuously optimizes throughput based on actual system performance and conditions.
2Measurement precision
If outer loop ICC adjustments are continuously applied to meet BLER targets, then link adaptation accuracy is improved, but system complexity and processing overhead increase
Solution Approach 1:
The patent applies outer loop ICC adjustments selectively rather than continuously. Adjustments are triggered only when specific conditions are met, such as when BLER deviations exceed thresholds or when confidence levels in channel estimates are insufficient. This partial application reduces processing complexity while maintaining measurement precision where needed.
Solution Approach 2:
The system uses UE-provided processing capability indicators and channel state information to self-adjust link adaptation parameters. The UE effectively serves the base station by providing the information needed for accurate ICC adjustments, reducing the base station's processing burden while maintaining high measurement precision.
3Productivity
If aggressive MCS and rank reporting is enabled to increase data rates, then throughput potential is improved, but NACK ratios increase due to UE processing delays and errors
Solution Approach 1:
The patent changes the parameter of BLER target based on UE processing capability indicators and channel conditions. When UE processing capabilities are limited or channel conditions are poor, the system adjusts parameters to use more conservative MCS and rank selections, reducing NACK ratios while maintaining optimal throughput. When conditions improve, more aggressive parameters are enabled.
Solution Approach 2:
The system dynamically adjusts MCS and rank selections based on real-time feedback from UEs regarding processing capabilities and channel state. This dynamic adaptation allows the system to maximize data rates when conditions permit while maintaining transmission reliability when UE processing delays or errors are detected.
4Stability of the object's composition
If control channels are transmitted regularly on specific slots to maintain network synchronization, then network coordination is improved, but interference to data channels increases causing high PDSCH BLER
Solution Approach 1:
The patent uses preliminary action by having UEs report channel state information and processing capability indicators before data transmissions. This advance information allows the base station to predict and compensate for interference from upcoming control channels, adjusting link adaptation parameters in advance to maintain both network synchronization and data transmission reliability.
Solution Approach 2:
The system implements feedback mechanisms where UEs report the impact of control channel interference on data reception. The base station uses this feedback to adjust transmission parameters for subsequent data channels, reducing the harmful effects of regular control channel transmissions while maintaining necessary network synchronization.
Data Source
AI summary
A method is performed by a network node for handling link adaptation for a communication between the network node and a User Equipment, UE, in a wireless communications network. The method comprises: obtaining an initial Information Carrying Capacity, ICC, estimate; and establishing a measurement at each Hybrid Automatic Repeat Request, HARQ, feedback on an initial transmission in the communication. The measurement comprises a Block Error Rate, BLER, per: rank, Modulation and Coding Scheme, MCS, and slot. Based on the established measurement it is determining whether or not to adjust the initial ICC estimate, and whether or not to disable outer loop ICC adjustments. The determining is to be used as a basis for the link adaptation of said communication. A corresponding network node is also presented.