MIMO Throughput Prediction Using Excess Path Loss
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Solution Overview
Problem
Current methods for predicting MIMO throughput in LTE downlink radio network planning tools are inadequate, as they fail to accurately account for non-line of sight (NLOS) urban scenarios and require too many unknown input parameters, leading to insufficient prediction of MIMO performance.
Innovation Solution
A method that establishes a functional relation between MIMO throughput and excess path loss, using a look-up table mapping signal to interference plus noise ratio (SINR) and excess path loss, with the excess path loss defined as the difference between actual and free space path loss, to predict MIMO throughput in radio network planning tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross-polarised antennas are used for MIMO transmission, then MIMO performance is improved, but prediction accuracy deteriorates due to polarisation discrimination effects in NLOS urban scenarios
Solution Approach 1:
The patent changes the prediction approach from using orthogonality factor (which fails in NLOS) to using excess path loss as the key parameter. This parameter substitution allows accurate prediction of MIMO throughput in NLOS urban scenarios by capturing the degradation of cross-polarisation discrimination through the empirical relationship with path loss.
2Measurement precision
If comprehensive MIMO channel models are used to account for NLOS scenarios, then prediction accuracy is improved, but device complexity increases due to multiple unknown input parameters
Solution Approach 1:
The patent extracts the essential prediction capability from complex MIMO channel models by identifying excess path loss as the single most important parameter. This extraction simplifies the model by removing unnecessary complexity while retaining the core functionality needed for accurate MIMO throughput prediction in NLOS scenarios.
Solution Approach 2:
The patent performs preliminary empirical analysis to establish the relationship between excess path loss and MIMO throughput before actual network planning. This pre-established empirical model allows direct prediction without requiring complex real-time calculations or multiple input parameters during operation.
3Ease of operation
If distance-based orthogonality factor prediction is used, then simplicity is improved, but prediction accuracy deteriorates in NLOS urban areas with increasing distance
Solution Approach 1:
The patent replaces the distance-based orthogonality factor parameter with excess path loss parameter. This change maintains the simplicity of using a single parameter for prediction while dramatically improving accuracy in NLOS scenarios, as excess path loss directly captures the degradation of MIMO performance due to polarisation discrimination effects.
Data Source
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AI summary
The present invention refers to a method for predicting a MIMO throughput of a LTE downlink in a radio network planning tool, the method applying an excess path loss defined as difference of a computed free space path loss and an actual path loss of an electromagnetic wave at a respective mobile station location, establishing a functional relation between the MIMO throughput and the excess path loss, and using as input a transmission capacity gain due to a dual-stream MIMO system related to a single stream system and a pregiven mapping from a signal to interference plus noise ratio to a transmission capacity of the respective single stream system. Further, the present invention proposes a respective system component and a respective radio planning tool.