Path loss

Presented By:-Arvind Sahu.

The path loss is the difference (in dB) between the transmitted power and the received power.

Path loss may be due to many effects, such as:- Free space loss. Refraction. Diffraction. Reflection. Absorption.

Path loss

Path loss

Base station antenna located inside building.

Indoor radio channel differs from traditional mobile radio channel in: ◦ Distances covered are much smaller.◦ Variability of the environment is greater for a much

smaller range of T-R separation distances.

It is strongly influenced by specific features such as: ◦ Layout of the building.◦ Construction materials.◦ Building type.

Indoor Propogation Models

1. Empirical path loss model.

2. ITU Model for Indoor Attenuation/ Wall and floor factor model.

3. FRIIS MODEL.

4. Log-distance path loss model.

Models for indoor attenuations

Propagation within buildings. Irregular terrain, like in cities, doesn’t lend

itself to simple analytical path loss models. Empirical path loss models based on

extensive measurements. Okumura Model: Empirical model for

irregular terrain. Hata Model: Analytical approximation to

Okumura model.

Empirical path loss model

Path loss(L)= L1 + 20log r + nf af + nw aw

af = attenuation factor per floor. aw = attenuation factor per wall. L1 = reference path loss at r =1 m

Empirical path loss model

Models have poor accuracy (15-20 dB STD error).

Not easy to analyze.

Widely used to study cellular and WiFi performance via simulation.

Empirical path loss model

I. Multi-floor model.

II. Partition attenuation model.

Empirical models

Multi-floor model

Multi-floor model

Partition attenuation model

Partition attenuation model

The ITU indoor propagation model, is a radio propagation model that estimates the path loss inside a room or a closed area inside a building delimited by walls of any form.

Suitable for appliances designed for indoor use, this model approximates the total path loss an indoor link may experience.

ITU Model for Indoor Attenuation

This model is applicable to only the indoor environments.

Typically, such appliances use the lower microwave bands around 2.4 GHz.

However, the model applies to a much wider range.

Frequency: 900 MHz to 5.2 GHz

ITU Model for Indoor Attenuation

It is used to model the LOS path loss incurred in the channel.

It is based on the inverse square law of distance.

FRIIS MODEL

Friis Transmission Equation says that the path loss is higher for higher frequencies.

It predicts that the RSS decreases logarithmically with distance.

Log distance path loss model is a generic model and an extension to  Friis Free space model.

It is used to predict the propagation loss for a wide range of environments.

whereas, the Friis Free space model is restricted to

unobstructed clear path between the transmitter & the receiver.

Log-Distance Path Loss Model

Log-Distance Path Loss Model

Log-Distance Path Loss Model

Thank You