Outerloop Link Adaptation Bias Compensation
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Solution Overview
Problem
Outerloop link adaptation (OLLA) in wireless communications faces challenges in converging quickly due to biases in channel state information (CSI) measurements from wireless devices, leading to reduced communication throughput, especially with imperfect device implementations.
Innovation Solution
Modifying the initial value of OLLA to be wireless device-specific by configuring additional CSI measurements that allow the network node to estimate and compensate for biases, using channel and interference components from the same source, and setting an initial OLLA value based on derived bias, thereby reducing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional OLLA with generic initial value is used, then system complexity is low, but convergence speed is slow and communication throughput is reduced due to CSI measurement biases
Solution Approach 1:
The patent applies preliminary action by performing additional CSI measurements (channel component and interference component from same source) before setting the initial OLLA value. The network node estimates bias from these preliminary measurements and uses it to initialize OLLA, enabling faster convergence without increasing ongoing system complexity
Solution Approach 2:
The system applies self-service by having the wireless device perform the additional CSI measurements autonomously based on network configuration. The device self-evaluates its CSI measurement bias and reports it to the network node, eliminating the need for complex network-side calibration equipment
2Measurement precision
If additional CSI measurements are configured for bias estimation, then initial OLLA accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts only the essential bias information from the additional CSI measurements. Instead of transmitting full measurement data, the network node processes the channel and interference components locally to derive bias estimates, extracting only the necessary correction parameter for OLLA initialization
Solution Approach 2:
The bias value acts as an intermediary that bridges the additional CSI measurements and the initial OLLA setting. The measurements serve as input to bias estimation, and bias serves as input to OLLA configuration, reducing direct signaling requirements between device and network
3Productivity
If OLLA converges slowly due to CSI biases, then fewer measurements are needed, but communication throughput is reduced and more transmissions are required
Solution Approach 1:
By performing preliminary bias estimation measurements before OLLA initialization, the system prepares accurate starting conditions that enable faster convergence. This preliminary action reduces the number of iterative transmissions needed to achieve reliable communication, improving overall throughput
Solution Approach 2:
The system uses feedback from the additional CSI measurements to continuously refine the bias estimate and adjust the initial OLLA value. This feedback mechanism ensures that OLLA starts from an accurate baseline, reducing the number of retransmissions needed compared to generic initialization
Data Source
AI summary
According to one or more embodiments, a network node configured to communicate with a wireless device is provided. The network node includes processing circuitry configured to: receive a channel state information, CSI, report indicating a bias of the CSI report; determine the bias of the CSI report based at least on the indication; and set an initial outerloop link adaptation, OLLA, based at least on the determined bias of the CSI report.