Radio propagationPath loss

ShadowingMultipath fading, ISI

Telecommunication

Dr. Dóra Maros

GSM

Cells

Earth Cell(satelite)

MacrocellSize: 350m-20 kmOutdoor, rural, roads

MicrocellSize: 50m-300 mOutdoor, city

PicocellSize: some 10 mIndoor

GSM

Radio Propagation in Mobile Networks

GSM

GSM 900, 1800, 1900 bands (2G)

GSM

Duplexing Uplink Downlink Bandwidth

UMTS-FDD 1920 - 1980 MHz 2110 - 2170 MHz 60 + 60 MHz

UMTS-TDD 1900 - 1920 MHz UL/DL2010 - 2025 MHz

UL/DL20 + 15 MHz

Satelite 1980 - 2010 MHz 2170 - 2200 MHz 30 + 30 MHz

in 2000, new frequency bands 806 - 960 MHz, 1710 - 1885 MHz (GSM

bands!) 2500 - 2690 MHz

DEC

TGSM1800

1800 1900 2000 2100 2200 2500 2600 2700

UMTSFDD

Műhold

UM

TS

TD

D

UM

TS

TD

D

UMTSFDD

Műhold

UMTS

[MHz]

Paired fr. bands

Unpaired fr. bands

Channel bandwidth: 5,10, or 20 MHz

UMTS Frequency Bands

GSM

30 bands:21 FDD9 TDD

LTE Bands

GSM

GSM antennas

Adjustable antennas

Directional Antennas

GSM

Omni antenna mounted on mobile tower

„Handy” omni antenna

Omni antennas

GSM

Micro antennas: connections towards the core network (some ten GHz)

Microwave Antennas

GSM

MIMO antennas (LTE)

Multiple sector

antennas in the same cell

3G/4G Antennas

GSM

Indoor Antennas (examples)

GSM

The wavelength is inversly proportional to the frequency of elektromagnetic wave :

λ = c/f, where

λ - wavelength (m)c - velocity of electromagnetic wave (in vacuum and in the air about 3*108 m/s, accurate value: 299792458 m/s)f - frequency (Hz)

Example: 1. f=900 MHz (9*108 Hz) λ =? 3*108 / 9*108 = 3/9 [m] ~ 0,33 [m] 2. f=2,6 GHz (2,6*109)

3*108 / 2,6*109 = 1,154 * 10-1 ~ 0,1154 [m]

Radio propagation I. Frequency and wavelength

GSM

RSL Received

Signal Level (dB)

d (distance from antenna)

Free space attenuation:

a0 = 20 log (4Πd/λ)

a0 = 20 log (df) + 28,14

Radio propagation II. Path loss

GSM

Makrocell propagation models:Relative small traffic (rural, road), high speed of movement (>100 km/h)

Hata, COST231

Mikrocell propagation models:High traffic (urban, suburban), smaller speed of movement (30-80 km/h)Walfish-Ikegami modell, COST 231

Indoor propagation models:Mootley-Keenan (félempirikus)Ray-tracing

Radio Propagation III. Propagation Models

GSM

RSL (dB)

Mean value

Slow fading caused by shadowing

Radio Propagation IV. Shadowing

d (distance from antenna)

Base Station

Mobile Equipment

GSM

Fast fading caused by reflections

Radio Propagation V. Multipath Fading

Base Station Mobile Equipment