(a) Influence of in-home distribution on the exposure
(b) Pulsation in IEEE 802.11a/e (WLAN)
The use of wireless medium for communication purposes is not new for anyone now. Its use is rather increasing day by day with the introduction of new and attractive services such as mobile phones, hand-held devices, digital receivers (radio and TV) etc. When in-home use of the above mentioned services is considered, there is no doubt that they have a dominant influence on the total emitted electro-magnetic field.
In the recent years the effect of immission on human body has become a major theme of discussion. The standardization bodies and the governments are considering it a major task point and try their best to have it researched and reduced as much as possible.
MiniWatt-II is an effort in this regard from the Federal Ministry of Education and Research (BMBF). The predecessor project MiniWatt researched the alternative wireless systems with focus on minimum radiation and now MiniWatt-II is focusing on minimization of immission of the wireless systems named above.
The Chair of Telecommunications at the University of Saarland is investigating the effects of integration of audio visual data streams (e.g. radio, TV, Internet) with wireless LAN infrastructures for in-home distribution.
We can show that the choice of WLAN for in-home distribution reduces the total emitted electro-magnetic field (exposition) and the resulting pulsation in such networks is neglectable. "Pulsation" is the term which describes the power in the lower frequency parts (1 Hz - 1000 Hz) of the ideally commuted RF signal.
The WLAN system under consideration is the IEEE802.11 a/e, operating at 5 GHz with Quality of Service (QoS) enhancements.
Research tools and Results
- Modeling of transmission behaviour (gaps/bursts) with Gilbert-Elliot model
- Spectral analysis by multistage decimation and Fourier-analysis with Matlab