WLAN Tester Emulating Mobility via Frame Error Injection
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Solution Overview
Problem
Current methods for measuring mobility performance of WLAN equipment are inefficient, labor-intensive, prone to interference, and difficult to control, especially in simulating distance and frame error ratios without being subject to RF noise or manufacturing tolerances.
Innovation Solution
A WLAN tester unit with capabilities to control transmitted data packet power, simulate errors, and emulate RF signal-to-noise issues, using transmit and receive frame error injection logic, MAC logic, and RF up/downconversion functions to simulate mobility effects without actual physical movement or RF attenuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical movement of WLAN equipment is used to simulate mobility, then mobility performance can be measured, but the method requires large floor space, is labor-intensive, and is prone to interference
Solution Approach 1:
The patent replaces the mechanical system of physically moving WLAN equipment with a signal processing system that injects frame errors into the data stream. Instead of mechanically displacing devices to simulate mobility effects, the invention uses error injection logic to directly introduce controlled frame errors, thereby substituting mechanical movement with electronic signal manipulation.
Solution Approach 2:
The patent creates a virtual copy of the mobility effect by injecting frame errors that mimic the statistical characteristics of errors that would occur during actual physical movement. Rather than replicating the physical scenario, the invention copies the essential error patterns and statistical properties of mobility-induced errors through controlled injection into the data stream.
2Measurement precision
If RF attenuators are used to simulate distance effects, then signal strength can be controlled, but the method is subject to manufacturing tolerances and RF noise
Solution Approach 1:
The patent replaces the RF attenuator hardware system with a software-based frame error injection system. Instead of using physical RF components that are subject to manufacturing tolerances and environmental noise, the invention uses logical error injection at the data link layer, which provides deterministic and repeatable control over error rates without the variability inherent in RF hardware.
Solution Approach 2:
The patent introduces frame error injection logic as an intermediary between the physical RF layer and the higher-layer protocols. This intermediary layer allows precise control of error characteristics without directly manipulating the RF signal, thereby avoiding the problems of RF noise and manufacturing tolerances while maintaining measurement accuracy.
3Reliability
If actual distance variation is used to simulate mobility effects, then realistic mobility performance can be measured, but the method is difficult to control and repeatable
Solution Approach 1:
The patent changes the controlling parameter from physical distance to frame error injection rate. Instead of controlling mobility effects through difficult-to-manage physical displacement, the invention allows direct control of error statistics through programmable parameters such as error injection probability and error patterns, making the test highly controllable and repeatable while maintaining measurement validity.
4Ease of operation
If frame error injection is used to simulate distance effects, then controllable error ratios can be achieved, but the method requires specialized test equipment
Solution Approach 1:
The patent designs the WLAN tester unit with multi-functionality, integrating frame error injection logic, MAC logic, and RF signal generation capabilities into a single device. This universal tester can perform both traditional RF-based mobility tests and the new frame error injection method, thereby managing complexity through consolidation rather than requiring separate specialized equipment for each test type.
Data Source
AI summary
Systems and methods enabling the efficient and repeatable simulation of mobility, during performance measurements of wireless data communications equipment are described. These are particularly useful for testing the impact on performance of spatial separation between Wireless Local Area Network (WLAN) devices, clients, relative to their counterparts, access points. In accordance with one or more embodiments of the present invention, the controlled emulation of spatial distance effects by injecting impairments into the transmitted and received wireless data packet streams are disclosed to simulate the impact of distance on properties of signal level, signal to noise ratio, and frame error ratio. Injection of impairments may be accomplished by varying the transmit power, artificially inducing errors into transmitted frames, and withholding acknowledgements for otherwise valid received frames, at levels consonant with the amount of distance to be emulated. This enables various mobility performance measurements to be made on WLAN devices without actually requiring that they be physically separated.