PCS Extension to Hata Model, Walfisch Bertoni Model, Indoor Propagation and Partition Losses...
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Transcript of PCS Extension to Hata Model, Walfisch Bertoni Model, Indoor Propagation and Partition Losses...
PCS Extension to Hata Model, Walfisch Bertoni Model, Indoor Propagation and Partition Losses
Instructor: Dr. Mustafa Shakir
PCS Extension to Hata Model PCS Extension to Hata Model Euorpean
Cooperative for Scientific and Technical Research (EURO-COST)
Walfisch and Bertoni Model Walfisch and Bertoni considers the impact of rooftops
and building height by using diffraction to predict average signal strength at street level
P0 represents the free space loss
P1 is based upon diffraction and determines the signal loss from the rooftop to the street
Q2 gives the reduction in the rooftop signal due to the row of the buildings which immediately shadow thereceiver at street level
The pathloss S as product of three fators
Indoor PropagationIndoor channels are different from traditional mobile radio
channels in two different ways: The distances covered are much smaller The variablity of the environment is much greater for a
much smaller range of T-R separation distances. The propagation inside a building is influenced by: Layout of the building Construction materials Building type: sports arena, residential home,
factory,...
Microcells Models Smaller cells for increased capacity
Base station height is typically about that as lamp posts in a street(3-6 m above ground level)
Coverage is typically few hundred meters and is determined mostly by specific locations and electrical characteristics of surrounding buildings
Dominant propagation mechanisms are: Free space propagation + multiple reflection+ scattering+ diffraction
around vertical edges of buildings and rooftops
Indoor Propagation Indoor propagation is domited by the same
mechanisms as outdoor: reflection, scattering, diffraction.
--However, conditions are much more variable Doors/windows open or not
The mounting place of antenna: desk, ceiling, etc. The level of floors Indoor channels are classified as Line-of-sight (LOS) Obstructed (OBS) with varying degrees of clutter.
Indoor Propagation Buiding types Residential homes in suburban areas Residential homes in urban areas Traditional office buildings with fixed walls (hard partitions) Open plan buildings with movable wall panels (soft
partitions) Factory buildings Grocery stores Retail stores Sport arenas
Indoor propagation events and parameters
Temporal fading for fixed and moving terminals Motion of people inside building causes Ricean Fading for the stationary
receivers Portable receivers experience in general:
Rayleigh fading for OBS propagation paths Ricean fading for LOS paths.
Multipath Delay Spread Buildings with fewer metals and hard-partitions typically have small rms
delay spreads: 30-60ns.
---Can support data rates excess of several Mbps without equalization Larger buildings with great amount of metal and open aisles may have rms
delay spreads as large as 300ns.
---Can not support data rates more than a few hundred Kbps without equalization.
Path Loss The following formula that we have seen earlier also describes the indoor path
loss:
-- PL(d)[dBm] = PL(d0) + 10nlog(d/d0) + Xs
>>n and s depend on the type of the building
>>Smaller value for s indicates the accuracy of the path loss model.
Partition Losses In building path loss:Partition losses (same
floor) Partition losses between floors Signal Penetration into Buildings
There are two kind of partition at the same floor:
Hard partions: the walls of the rooms Soft partitions: moveable partitions that does
not span to the ceiling The path loss depends on the type of the partitions
Partitions vary widely in physical and electrical characteristics making it difficult to apply general models to indoor installations specifically.
Introduction-Fading
One of the most interesting applications of radio communications, that is communication between mobile people, has many impairments.
Due to multiple users, mobility and environment dynamics, the mobile radio channel is impaired by noise, interference as well as time-varying fluctuations
System design requires statistical characterization of both disturbances and random channel space/time variations
Envelope variations are due to phenomena on different spatial/temporal
Wireless Propagation Environment
Multipath Effects Rapid changes in signal strength over a small travel distance or time
interval
Random frequency/phase modulation due to Doppler shifts on different multipath signals
Time dispersion caused by multipath propagation delays
Impulse Response Model of a Multipath Channel
A mobile radio channel may be modeled as a linear filter with a time varying impulse response, where the time variation is due to receiver motion in space.
The filtering nature of the channel is caused by the summation of amplitudes and delays of the multiple arriving waves at any instant of time.
Channel Impulse Response
Due to the different multipath waves which have propagation delays which vary over different spatial locations of the receiver, the impulse response of the linear time invariant channel should be a function of the position of the receiver.
Multipath Radio Channel