Subject: [NEXTEL-1] Microwave WLANs-> the future ones ?

From: "Juliet" <[email-masked]>
Date: Mon, 18 Nov 2002 23:22:31 -0000

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Examplaric Microwaves Studies on high frequent Microwave bands:
Juliet J. Marie Reisenhofer
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Beside the allocation of frequency bands of the graphical report of 
the FCC, where  Microwaves are situated in the following ranges: 
* 944-960 MHz (page 5), 
* 1850-1910 MHz, 
* 1930-1990 MHz (page 9) for fixed microwaves in personal 
communication systems, whereby the RF devices range in between and 
* 2110-2165 MHz (page 10 of the report). 
Nevertheless a lot of references mention a new spectra for Microwave 
PCS allocating it 
within 5.2- 5.8 MHz or other spectra. 

1.) Parameters for Range Calculation for IEEE-802.11a at 5 GHz in 
Table 1 lists Hiperlan2 

and IEEE 802.11a power and gain [Andelmann 01, p.3].
Furthermore in [Andelmann 01, p.6] is described that the indoor 
coverage area in Europe is 

about 47,4 meters and in the US 57 meters, considering 11 Mbps data 
tranfer rates in a 5Ghz 

wireless LAN.
In his summary he describes finally the benefits of 5Ghz wireless 
LANs over those in the 2.4 

Ghz areas like: "upgrading from an IEEE 802.11b network to an IEEE 
802.11a based network 

will result in no degradation in range performance, or loss of data 
rate, and offers the 

benefits of higher data rates, operation of the wireless link in the 
much cleaner 5GHz 

frequency band, and greater network capacity. Finally, it was seen 
tha t, all else equal, 

the degradation in indoor coverage range due to moving from the 
2.4GHz to the 5GHz
frequency band is 20-25% rather than the 50+% predicted using open-
air models. "

Reference: 
[Adelmann 01] 5 GHz WLAN Indoor Coverage Range: Truths and 
Misconceptions, Dr. Dov Andelman, 

CTO Envara Inc., Israel. (pdf-document in the attachement).  

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2.) At an amateur group in Switzerland they tried several practical 
studies on let's call it 

local area networks, with an restricted radius on 25 meters, with 
Microwaves. Among them 

single person single station produced microwave connection 
constellations and multiperson, 

multistation ones:  
Connection Types used: telegrafie (A1A) und telephony (J3E, F3E 
[G3E]).
Satellites, terrestrial transductors, relais- stations and active 
reflektores are not valued 
Results with "single stations": Microwave connections in the 
frequency bands of normal 

ranges, as well as the following ones: 10 GHz, 24 GHz, 47 GHz, 78 
GHz, 120 GHz, 143 GHz, 246 

GHz.
Some additional information, the circumstances of the experiments can 
be read at:
http://www.surplusparty.ch/contest%20juli%20reglement.htm

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3.) Best come at place 3 ?: The good old HiperLAN studies focused 
already on higher 

frequency too: 
* HiperAccess in 5 GHz ranges (although just as a local loop 
technique), 
* HiperLink in 17 GHz ranges is said or postponed (especially by the 
BRAN people) to become 

the future WLAN connectivity technology.
On the European mainland at the www.cordis.lu projects pages 
intentions and several realised 

case studies are overviewed, but not described in detail how much of 
the inlcuded networks 

or components concerned just on HiperLAN 1, 3, HiperLink or 
HiperAccess connectivity, just 

that the technology was somehow involved.
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4.) ...?...

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I am sure there is a lot more scientific work in terms of higher 
frequency bands in terms of 

Microwave connectivity already done, or in progress. 
Although somehow questions of impacts in ethical terms arises:
*) How much impacts have high frequencies on human beings, human 
minds or childs or special 

sensitive ones ?
*) How much impacts and which ones have they on animals, chemicals or 
other substrats or 

fluids, which are commonly situated in environmental spaces of either 
working areas or 

transmitting areas ?
*) How much impacts and which ones will they have in interrelation 
with other wireless 

network technologies ?
*) Ethical impacts, national and international ones...?

:) Juliet
(worth a reply ?)

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From: Alan Dixon <[email-masked]>
Date: Mon, 18 Nov 2002 21:43:27 -0500

Interesting overview, as well as questions raised.
Cheers, Alan

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