The wlan EMC immunity Testing for Mobile Devices in eu
T. A. Alasuvanto*
* Oulu University of Applied Sciences, School of Engineering, Oulu, Finland
Abstract
The aim of this paper was to find the definition of the European requirements and performance criteria for WLAN EMC verification and testing according the EMC standards. In more detail, the aim was to define the needed of the measurements, the limit values as well as performance criteria. The definition was based on the European Telecommuni-cation Standard Institute (ETSI) EN 301489-17 standard and the Institute of Electrical and Electronics Engineers (IEEE) 802.11 specifications. According to these references the limit values and the performance criteria for minimum setup consist of immunity tests, test site and monitoring of the WLAN data.
Keywords: EMC, EMS, Immunity, susceptibility, EUT.
Introduction
Electromagnetic compatibility (EMC) is the branch of electrical sciences, which studies the unintentional generation, propagation and reception of electro-magnetic energy with reference to the unwanted effects (Electromagnetic Interference, EMI) that such energy may induce. Electromagnetic compatibility requires preventive measures against emission and measures for immunity (Electromagnetic Susceptibility, EMS). In this work, immunity (EMS) aspects are more closely studied such as test cases and performance criteria, but emission will be ruled out. The motivation for this study is that currently there are no ready-made testing systems available, which are dedicated to WLAN EMC testing in a mobile device (EUT) perspective.
This work is needed to have some evidence, that the sentence like "To operate as intended" in mobile device world, means using the equipment in accordance with the manufacturer's instructions in the electromagnetic environment determined by the standards chosen by the manufacturer. The second task is to find out the feasible test solution, which is correctly fitted to WLAN EMC immunity testing needs.
Background
Depending on the type of coupling of electro-magnetic disturbances, the phenomena are divided into two different groups. In the case where the disturbance signal is an air-borne, one speaks of radiated inter-ference, while in the case where the disturbance signals are line-carried, one speaks of conducted interference.
Measurements are divided into two categories as radiated and conducted, which are based on electro-magnetic phenomena, commonly known as electro-magnetic interferences:
· supply voltage interruptions, dips, surges and fluctuations
· fast transient over voltages including spikes and surges on supply, signal and control lines
· radio frequency fields coupled directly into the equipment or onto its connected cables
· electrostatic discharge (ESD) from a charged object or person
Results and Discussion
The WLAN standards do not directly refer to Bit Error Rate (BER) measurements, as in the case of cellular (voice) systems like GSM phones. It is generally known, that the WLAN EMC specifications are not as well harmonized as the other testing requirements. Performance criteria are based on packet error rate (PER) testing. The WLAN systems operate with a positive acknowledgement-based technique. When a frame is sent, it incorporates extra data to allow the receiver to determine the possibility of packet errors.
Based on the literature reviewed, the minimum test requirements for WLAN EMC immunity testing are applicable immunity tests, test place and WLAN data monitoring. This means the measurement of PER in different input levels of the EUT.
Conclusions
The aim of the manufacturing process should be to produce an electric equipment capable of functioning in the predicted or specified electromagnetic environment and that does not interfere with other equipment or unduly pollute the environment. It means the achievement of a proper EMC for WLAN devices. This can be gained by fulfilling applicable standards and using equipment in accordance with the manufacturer's instructions.