C02-Wireless_Transmission

C02-Wireless_Transmission - Mobile Communications Chapter...

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2.1 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Mobile Communications Chapter 2: Wireless Transmission Frequencies Signals, antennas, signal propagation Multiplexing Spread spectrum, modulation Cellular systems
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2.2 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Frequencies for communication VLF = Very Low Frequency UHF = Ultra High Frequency LF = Low Frequency SHF = Super High Frequency MF = Medium Frequency EHF = Extra High Frequency HF = High Frequency UV = Ultraviolet Light VHF = Very High Frequency Frequency and wave length λ = c/f wave length λ , speed of light c 3x10 8 m/s, frequency f 1 Mm 300 Hz 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100 µ m 3 THz 1 µ m 300 THz visible light VLF LF MF HF VHF UHF SHF EHF infrared UV optical transmission coax cable twisted pair
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2.3 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Frequencies for mobile communication VHF-/UHF-ranges for mobile radio simple, small antenna for cars deterministic propagation characteristics, reliable connections SHF and higher for directed radio links, satellite communication small antenna, beam forming large bandwidth available Wireless LANs use frequencies in UHF to SHF range some systems planned up to EHF limitations due to absorption by water and oxygen molecules (resonance frequencies) weather dependent fading, signal loss caused by heavy rainfall etc.
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2.4 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Frequencies and regulations ITU-R holds auctions for new frequencies, manages frequency bands worldwide (WRC, World Radio Conferences) Examples Europe USA Japan Cellular phones GSM 880-915, 925- 960, 1710-1785, 1805-1880 UMTS 1920-1980, 2110-2170 AMPS, TDMA, CDMA, GSM 824- 849, 869-894 TDMA, CDMA, GSM, UMTS 1850-1910, 1930-1990 PDC, FOMA 810-888, 893-958 PDC 1429-1453, 1477-1501 FOMA 1920-1980, 2110-2170 Cordless phones CT1+ 885-887, 930- 932 CT2 864-868 DECT 1880-1900 PACS 1850-1910, 1930-1990 PACS-UB 1910-1930 PHS 1895-1918 JCT 245-380 Wireless LANs 802.11b/g 2412- 2472 802.11b/g 2412- 2462 802.11b 2412-2484 802.11g 2412-2472 Other RF systems 27, 128, 418, 433, 868 315, 915 426, 868
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2.5 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Signals I physical representation of data function of time and location signal parameters: parameters representing the value of data classification continuous time/discrete time continuous values/discrete values analog signal = continuous time and continuous values digital signal = discrete time and discrete values signal parameters of periodic signals: period T, frequency f=1/T, amplitude A, phase shift ϕ sine wave as special periodic signal for a carrier: s(t) = A t sin(2 π f t t + ϕ t )
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2.6 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Fourier representation of periodic signals ) 2 cos( ) 2 sin( 2 1 ) ( 1 1 nft b nft a c t g n n n n π = = + + = 1 0 1 0 t t ideal periodic signal real composition (based on harmonics)
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2.7 Prof. Dr.-Ing. Jochen H. Schiller www.jochenschiller.de MC - 2011 Signals II Different representations of signals amplitude (amplitude domain) frequency spectrum (frequency domain)
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This note was uploaded on 09/04/2011 for the course IT 100 taught by Professor Rickdas during the Spring '11 term at University of Mumbai.

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C02-Wireless_Transmission - Mobile Communications Chapter...

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