Per-UE Signal Fading Simulation for Air Interface Testing
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Solution Overview
Problem
Current signal fading simulation equipment for testing air interface devices in mobile communications networks is typically wideband and expensive, failing to accurately simulate per-UE fast and slow signal fading, which is essential for evaluating device functionality and performance.
Innovation Solution
A network equipment test device with per-UE uplink signal generation processing chains simulates signal fading by varying phases and amplitudes over time for each user equipment (UE), generating time domain signals that undergo Fourier transformation, subcarrier mapping, and inverse Fourier transformation to produce frequency and time domain signals with simulated fading, allowing for accurate per-UE signal fading simulation without the need for expensive wideband equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wideband signal fading simulation equipment is used, then signal fading can be simulated, but the equipment becomes expensive
Solution Approach 1:
The patent divides the wideband signal fading simulation into multiple narrowband processing chains, where each chain handles a specific frequency band and applies independent fading simulation. This segmentation allows using multiple low-cost narrowband processors instead of one expensive wideband processor, resolving the contradiction between simulation accuracy and equipment cost.
Solution Approach 2:
The patent creates multiple copies of narrowband signal processing chains, each copying the fading simulation functionality for a specific UE and frequency band. These copied chains work in parallel to collectively simulate wideband fading effects, achieving accurate per-UE fading simulation without requiring expensive wideband equipment.
2Measurement precision
If per-UE signal fading simulation is implemented, then testing accuracy improves, but system complexity increases
Solution Approach 1:
The patent segments the signal processing system into independent per-UE processing chains, where each chain handles signal generation, fading simulation, and processing for a single UE. This segmentation isolates complexity into manageable modules while maintaining high measurement precision for each UE's fading characteristics.
Solution Approach 2:
The patent changes the processing approach by applying fading simulation in the time domain before Fourier transformation, rather than in the frequency domain. This parameter change in the processing sequence simplifies the system architecture while maintaining per-UE fading accuracy, as fading can be applied as a simple time-domain multiplication operation.
3Productivity
If multiple UEs are processed simultaneously, then testing efficiency improves, but signal processing complexity increases
Solution Approach 1:
The patent implements separate processing chains for each UE, with each chain independently generating and processing signals for one UE. These segmented chains operate in parallel, enabling efficient multi-UE testing while keeping each chain's complexity manageable and modular.
Solution Approach 2:
The patent merges the outputs of multiple independent per-UE processing chains into a combined multi-UE signal for transmission. This merging approach allows efficient simultaneous processing of multiple UEs while maintaining the simplicity and modularity of individual processing chains, resolving the contradiction between testing efficiency and system complexity.
Data Source
AI summary
A network equipment test device includes per-UE uplink signal generation processing chains for generating per-UE time domain uplink signals. Per-UE signal faders simulate per-UE signal fading for the per-UE time domain uplink signals. Different phases and amplitudes are used over time to simulate different signal fading. Fourier transformation units perform Fourier transformation of each of the time domain uplink signals to produce per-UE frequency domain uplink signals with simulated per-UE signal fading. A subcarrier mapping unit performs subcarrier mapping of the per-UE frequency domain uplink signals to produce a frequency domain multi-UE uplink signal with simulated per-UE signal fading. An inverse Fourier transformation unit performs inverse Fourier transformation of the frequency domain multi-UE uplink signal to produce a multi-UE time domain uplink signal with simulated per-UE signal fading. A network interface transmits the time domain multi-UE uplink signal with simulated per-UE signal fading to the DUT.