1. infokom. 3. ea. 2012. szept. 23.1 Infocommunication systems Infokommunikációs rendszerek Lecture 3. előadás Radio transmission Rádiós átvitel Takács György

2. infokom. 3. ea. 2012. szept. 23.2 Radio transmission media Frequency bands and wave propagation modes Terrestrial radio connection Satellite communication In door radio connection

3. infokom. 3. ea. 2012. szept. 23.3 Media characteristics Transmission parameters (path loss, delay, fading, radio interferences) Reliability and availability - equipment and propagation parameters (lightning, snow, rain, fog, smoke) Openness – interferences - privacy

4. infokom. 3. ea. 2012. szept. 23.4 Is radio communication a technical issue (1)? Radio communications use open and common media. Using a radio frequency means consuming. So management of radio frequency is inevitable. Using a radio frequency means a kind of environment pollution! Frequency police? Radio frequencies are limited resources. The „good” frequencies are already consumed. Frequency fees! NMHH. Propagation of radio waves do not consider political borders! Frequency management is a typical international process. (CCIR, ITU-R)

5. infokom. 3. ea. 2012. szept. 23.5 Is radio communication a technical issue (2)? Radio frequencies have considerable physiological effect! Antennas are considered as special constructions. Local municipalities regulate construction rules and issue building licences. Satellite positions are limited resources too. The „good” positions are consumed. Differential equations of electromagnetic wave propagation are quite simple – in the case of plane wave and free space. Solutions in real geographic situations (among hills, valleys, buildings or especially inside buildings) are extremely difficult.

6. infokom. 3. ea. 2012. szept. 23.6 Frequency bands and wave propagation modes LF (30-300kHz) MF (300-3000kHz) HF (3-30 MHz) VHF (30-300 MHz) UHF (300-3000MHz) SHF (centimetric waves, 3-30GHz) EHF (millimetric waves, 30-300GHz)

7. infokom. 3. ea. 2012. szept. 23.7 Propagation modes and antennas LF MF

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9. 9 Propagation modes and antennas HF

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11. infokom. 3. ea. 2012. szept. 23.11 Propagation modes and antennas UHF VHF SHF EHF

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16. infokom. 3. ea. 2012. szept. 23.16 in free space (ε 0,µ 0 ): plane-wave solution 1. electric and magnetic field vectors are perpendicular 2. ratio of their amplitudes is a constant and called as free-space wave impedance

17. infokom. 3. ea. 2012. szept. 23.17 Reflection coefficient characteristic impedance

18. infokom. 3. ea. 2012. szept. 23.18 Free space radio link (LOS) P T transmitted power A e effective area of antenna G gain of antenna λ wavelength d distance

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20. infokom. 3. ea. 2012. szept. 23.20 Example by GSM mobile system Base station d=30m P=50W d=3cm P=5W P r =kP T /d 2 P r =k×0,0555 P r =k×5555 100000×

21. infokom. 3. ea. 2012. szept. 23.21 Property of a radiated electromagnetic wave describing the time varying direction and relative magnitude of the electric-field vector In general the field is elliptically polarized Linear and circular polarizations are special cases Polarization:

22. infokom. 3. ea. 2012. szept. 23.22 Reflection The amplitude, phase and polarization of the reflected wave is determined by the material parameters of the medias and the surface irregularity.

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26. infokom. 3. ea. 2012. szept. 23.26 Propagation with direct and reflected waves and reflected only waves

27. infokom. 3. ea. 2012. szept. 23.27 RECEIVER SENDER Without FADING RADIO FOR MOBILES

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38. infokom. 3. ea. 2012. szept. 23.38 „Good” frequencies? Bandwidth issues? Low attenuation (loss) High bandwidth Beaming – circular characteristic Cheap or free No interference Exclusive usage „Good” frequencies are not existing -- Only compromise of limitations

39. infokom. 3. ea. 2012. szept. 23.39 Radio link types Point-point connections Point multipoint connections Cellular systems

40. infokom. 3. ea. 2012. szept. 23.40 Optically visibleloop The surface of the earth 30-50 km because the spherical earth Terrestrial microwave connections

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43. infokom. 3. ea. 2012. szept. 23.43 Geostationary satellite characteristics Gravitation force Centrifugal force Mass of the satellite, kg Mass of the earth Gravitational constant Speed of the satellite, m/s

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61. infokom. 3. ea. 2012. szept. 23.61 Cellular systems in a cluster each cell has a separate frequency a is the area of one cell A is the cluster area R is the cell diameter D is the distance between clusters (the distance between cells with identical frequencies) K is the number of the cluster cells

62. infokom. 3. ea. 2012. szept. 23.62 Examples for generating clusters

63. infokom. 3. ea. 2012. szept. 23.63 Frequency reuse pattern for K=4

64. infokom. 3. ea. 2012. szept. 23.64 Frequency reuse pattern for K=7

65. infokom. 3. ea. 2012. szept. 23.65 Frequency reuse pattern for K=19

66. infokom. 3. ea. 2012. szept. 23.66 K=?

67. infokom. 3. ea. 2012. szept. 23.67 Increasing capacity in cellular systems Adding new channels Frequency borrowing Cell splitting Cell sectoring Microcells

68. infokom. 3. ea. 2012. szept. 23.68 Sectoring

69. infokom. 3. ea. 2012. szept. 23.69 In-door wireless connections

70. infokom. 3. ea. 2012. szept. 23.70 A vezetéknélküli adathálózat bázisállomásainak helye elő van készítve minden folyosón

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73. infokom. 3. ea. 2012. szept. 23.73 Interferences