The Maximum Average Electromagnetic Radiation Intensity Of Wlan Assessment Research

Compared with the traditional wired Ethernet, due to get rid of the limitation ofthe cable, wireless local area networks (LANs) have the advantages of moreconvenient, flexible and ease of installation, etc. So its development is very rapid inrecent years. It is now extensively covered to businesses, hospitals, schools, shoppingmalls, public transport and other important areas. Wireless LANs have been closelyrelated to people’s work, study and daily life. Wireless LAN brings a variety ofconvenient, but at the same time electromagnetic radiation generated by it has becomea hidden danger of public health. Now，the electromagnetic radiation problem causedby the wireless LAN has attracted more and more attentions of experts and scholars.Currently, the main research in the field of wireless LAN electromagneticradiation is biased towards the worst-case situation of radiation, i.e., the maximuminstantaneous exposure value. In a wireless LAN, due to the schemes which arestipulated by the transmission protocol, such as carrier sensing, channel detection,random backoff, etc, the signal is not transmitted continuously in the data frametransmission cycle. There are a lot of intervals between transmission signal pulses. Asa result, the maximum instantaneous exposure value in worst cases can’t reflect theactual electromagnetic radiation situation of network equipment. Some researchershave proposed using the maximum average electromagnetic radiation intensity toassess the actual electromagnetic radiation situation of wireless LAN. This methodneeds to measure with a specialized device, such as ordinary spectrum analyzer orvector signal analyzer, etc. The parameter settings before measurement and dataprocessing after the measurement are quite cumbersome and complicated. In addition,this method is also lack of theoretical analysis in WLAN’s work principle andtransmission characteristics.Aiming at the shortcomings of the existing research methods, this paper proposesa new method for assessing the maximum average intensity of electromagneticradiation due to wireless LAN. The method is divided into three steps: First, startingfrom the wireless LAN protocol standards, we derive the maximum electromagneticradiation intensity of wireless LAN device under different data transfer rates bymodulation signal’s power spectral density. Second, according to the workingprinciple of wireless LAN and signal’s transmission characteristics, we derive thesignal’s maximum transmission time ratio in different rates. Thirdly, we obtain the maximum average electromagnetic radiation intensity by the product of the maximumelectromagnetic radiation strength value and the square root of the maximumtransmission time ratio. We use the value of maximum average electromagneticradiation intensity to assess the wireless LAN’s actual electromagnetic radiationsituation. The new method proposed in this paper is used to assess the wireless LAN’sactual maximum average electromagnetic radiation strength in different applicationsituations. The traditional measure method is used to do comparative analysis with thenew method. The accuracy and feasibility of the theoretical method presented in thispaper are validated by the consistency of actual measurement results and thetheoretical calculation results. All experiment results are less than emission limitsstipulated by the current domestic and international electro magnetic radiationprevention standards, indicating that the studied devices meet the provisions of therelevant standards and requirements.