11 09 0553-01-00ad Path Loss Model Development for Tgad Channel Models (1)

8/10/2019 11 09 0553-01-00ad Path Loss Model Development for Tgad Channel Models (1)

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Alexander Maltsev, Intel Corp.Slide 1

Path Loss Model Development for TGad Channel Models

Date:2009-05-11

Authors:

Name Affiliations Address Phone email

Alexander Maltsev Intel Corporation Turgeneva str., 30, NizhnyNovgorod, 603024, Russia

+78314969461 [email protected]

Eldad Perahia Intel Corporation 2111 NE 25th AveHillsboro, OR 97124

503-712-8081 [email protected]

Roman

Maslennikov

Intel Corporation Turgeneva str., 30, NizhnyNovgorod, 603024, Russia


Artyom Lomayev Intel Corporation Turgeneva str., 30, NizhnyNovgorod, 603024, Russia


Alexey Khoryaev Intel Corporation Turgeneva str., 30, NizhnyNovgorod, 603024, Russia


AlexeySevastyanov

Intel Corporation Turgeneva str., 30, NizhnyNovgorod, 603024, Russia +78314969461 [email protected]


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Abstract

This contribution proposes an approach for path loss model development

for TGad channel models


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Development of Path Loss Model

The conference room channel model proposed in [1] provides complexamplitudes of different rays taking into account the attenuation of thesignal between the transmitter and receiver in a real scale. So each rayhas some information about the propagation loss of the channel andsome information about the impulse response.

This is different from the traditional channel modeling approach where

separate models are generated for the path loss and the channelimpulse response.

The reason for using different approaches is a difference inpropagation channel characteristics between the 60 GHz band and thetraditional WLAN bands (2.4 GHz and 5 GHz).

In the 2.4 GHz and 5 GHz bands many channel rays contribute to thetotal received signal power even if multiple antennas are used andspatial signal processing algorithms are applied. Thus the separation

between path loss and impulse response models is possible.

[1] IEEE doc. 802.11-09/0334r0 Channel Models for 60 GHz WLAN Systems


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Development of Path Loss Model (Contd)

In the 60 GHz band the path loss and channel impulse models are more

complexly interrelated.

For example, many beamforming algorithms using directional antennas are

filtering out (in a spatial domain) a single cluster of the propagation channel.

So both the frequency selectivity and propagation loss of the channel will be

only defined by characteristics of a single cluster. Thus for the same TX andRX locations, the propagation loss and channel impulse response may be

significantly different depending on the characteristics of the cluster used for

communications and also directivity properties of antennas and used

beamforming algorithm.

The developed conference room channel model may be directly applicable for

link level simulations where an independent path loss model is not required.

However, the path loss model is important for network (or MAC) simulations

where direct application of the conference room channel model and direct

modeling of the beamforming algorithms may unnecessary complicate the

network simulations.


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Development of Path Loss Model (Contd)

It is possible to derive an independent path loss model if some

assumptions about the 60 GHz WLAN system such as antenna type

and beamforming algorithm are fixed.

In this contribution the path loss model was developed using the basic

steerable directional antenna model from [1] with beamwidths from600 to 100 and the beamforming algorithm adjusting TX and RX

antennas along the ray with maximum power.

The path loss values were obtained for many snapshots of the

conference room channel model. Then the path loss model was

derived.

[1] IEEE doc. 802.11-09/0334r0 Channel Models for 60 GHz WLAN Systems


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Average Path Loss vs. Distance for LOS Scenario

Average path loss vs.

distance curve is plotted for

300antenna beamwidth

It was verified that curves

for other antennabeamwidths in the range

from 600to 100match each

other very closely (within

0.1 dB).

The curve may be well

approximated by the r2law.


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Histogram of Path Loss Realizations for LOS Scenario

It may be seen that for

LOS scenario deviations

of actual path loss values

are very low (because the

most part of the channel

power is the LOS ray)

No shadow fading may be

assumed for LOS scenario.

All LOS realizations of the

channel with the samedistance will have the

same path loss.


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Path Loss Model for LOS Scenario

Based on the obtained simulation results a simple path loss model may be

proposed for LOS scenario based on Friis transmission equation:

WhereALOS

= 32.5 dB, nLOS

= 2.0, fis the carrier frequency in GHz,Ris

the distance between TX and RX in m.

The value of ALOS is specific for the selected type of antenna and

beamforming algorithm.

ALOSdepends on the antenna beamwidth, but for the considered beamwidth

range from 60

0

to 10

0

the variation will be very small (< 0.1 dB) There is no shadowing for the LOS scenario.

RnfAPLLOSLOSLOS 1010

log10log20dB][


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Simulated Average Path Loss and Path Loss Predicted

Using Model for LOS Scenario

The plot shows path

loss curves obtained

from the statistical

conference room

channel model, path

loss model and

several experimental

points

It may be seen that

the path loss model is

well matched to both

the statistical channel

model and

experimental data


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Path Loss Model Development for NLOS

Scenario

The similar assumptions and procedure as for the LOS scenario were

used for the developed of the path loss model for the NLOS scenario

of the conference room channel model.

The basic steerable directional antenna model with beamwidths from

600 to 100 and the beamforming algorithm adjusting TX and RXantennas along the ray with maximum power were used.


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Average Path Loss vs. Distance for NLOS Scenario

Average path loss vs.

distance curves are plotted

for antenna beamwidths

from 600to 100.

The curves for differentbeamwidths are close to

each other (within 1 dB)

All curves have the same

shape and may be

approximated by the r0.6

law.


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Histogram of Path Loss Realizations for NLOS Scenario

It may be seen that for the

NLOS scenario the

dispersion of the path loss

is significant and shadow

fading model should be

introduced.

Normal (Gaussian) in dB

(log-normal in absolute

scale) distribution may be

used in the shadow fading

model because it providesclose matching of the

distribution obtained from

the simulations.


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Standard Deviation of Shadow Fading Model for NLOS

Scenario as Function of Distance

The standard deviation of the

path loss depends on the TX

RX separation but

approximately may be taken

equal to 3.3dB as it followsfrom the left plot.

The dependence of on

antenna beamwidth is very

small because for the

considered range of antenna

beamwidths (600 to 100)

antenna selects only one spatial

cluster for most of the cases


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Path Loss Model for NLOS Scenario

Based on the obtained results an average path loss model may be proposedfor NLOS scenario as:

WhereANLOS

= 51.5 dB, nNLOS

= 0.6, f is the carrier frequency in GHz, R is

the distance between TX and RX in m.

The values of ANLOS andnNLOSare specific for the selected type of antenna

and beamforming algorithm.

ANLOSdepends on the antenna beamwidth, but for the considered beamwidth

range from 600

to 100

the variation will be very small (< 1 dB) Additionally, the shadow fading (SF) model should be applied. The SF

values distribution is normal in dB (log-normal in absolute values) with

standard deviation = 3.3 dB.

RnfAPLNLOSNLOSNLOS 1010

log10log20dB][


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Simulated Average Path Loss and Path Loss Predicted

Using Model for NLOS Scenario

The plot shows path

loss curves obtained

from the statistical

conference room

channel model, pathloss model and several

experimental points.

It may be seen that the

path loss model is well

matched to both thestatistical channel

model and

experimental data


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Path Loss Model Summary

If antenna system parameters and beamforming algorithms are fixed then it ispossible to derive an average path loss model using the standard form:

WhereA and nare parameters specific for the scenario and antenna system,fis

the carrier frequency in GHz,Ris the distance between TX and RX in m.

The normal in dB SF model may be used together with the average path loss

model. SF standard deviation is specific for the scenario and antenna system

parameters.

The path loss model parameters for the conference room scenario, basic

steerable antenna model and maximum ray beamforming algorithm are:

RnfAPL1010

log10log20dB][

Scenario A, dB n SF std. dev., dB

Conference room LOS 32.5 2.0 0

Conference room NLOS 51.5 0.6 3.3


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Conclusion

It is more difficult to decouple path loss and channel impulse response for

the 60 GHz WLAN channel modeling than for 2.4-5 GHz bands.

An independent path loss model may be derived if the type of antenna and

beamforming algorithm are fixed.

The path loss model for the conference room environment was obtained for

LOS and NLOS environments, for system with steerable antennas (with

beamwidths from 100 to 600) and beamforming algorithm selecting the

most powerful ray.

The proposed path loss model development approach may be used for the

development of the path loss models for other TGad scenarios.

The developed path loss model is suitable for system performance

evaluation and network simulations.

11 09 0553-01-00ad Path Loss Model Development for Tgad Channel Models (1)

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