CHANNEL MODEL for INFOSTATIONS Our first measurements Andrej Domazetovic, WINLAB – April, 27

CHANNEL MODEL for INFOSTATIONS

Our first measurements

Andrej Domazetovic,WINLAB – April, 27

OUTLINE

Reminder: Friis free space equation Reminder: Short range 2-ray propagation model Estimation of the Ricean K-factor Measurement 1 - fixed antennas Measurement 2 - one antenna moving

Friis free space equation

Source:

[] Rappaport - Wireless Communications

L

GGd

PdP rttr1

4

2

• The formula is a valid predictor for Pr for d which are in the far-field of the transmitting antenna - Fraunhofer region i.e. when inductive and electrostatic fields become negligible and only radiation field remains

df=2D2/ , df>>D and df>>• For fc = 5.3 GHz and the antenna size D = 7 cm

df=17.31 cm , df >> 7 cm and df>>5.66 cm

ddBLdBGdBGdBPdBP rttr log*20][][][4

log*10][][2

ddBmdBmdBmdBmPr log*2039.4611][ (1)

Short range 2-ray propagation model

Source:

[] Rappaport - Wireless Communications

td

dERt

d

dEtdE ccTOT coscos, 0000

2

ddR

dK

irir

irirR

2

2

||cossin

cossin

)()( tvVtg

Characterize the complex signal path gain of the narrowband wireless channel as

Estimation of the Ricean K factor

Relate the equation to the two moments that can be estimated from the measurements of received power versus time

tVvEtvEVGtrue*22 Re*2)(

The second moment is the rms fluctuation of G about Gtrue.

2*4422 Re*2)( tVvEtvEGGEG truev

Source:

[] Greenstein et. al - Moment method estimation of the Ricean K factor

Estimation of the Ricean K factor

)1(22 VGtrue

Under the assumption that the v(t) is complex Gaussian, zero mean, this can be written as:

)2(2 2242 VGv

Source:

[] Greenstein et. al - Moment method estimation of the Ricean K factor

If we can estimate the left-hand side of 1 and 2 from the data, then we have two equations with two quantities that we need.

222vtrue GGV

2

2

V

K

222vtruetrue GGG

And finally, the Ricean K-factor is:

Measurement 1 - Fixed antennas

Results of measurements



frequencyanalizer

transmitter

v = const.

Measurement 2 - one antenna is moving




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CHANNEL MODEL for INFOSTATIONS Our first measurements Andrej Domazetovic, WINLAB – April, 27