Remote Applications.


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Why Wireless?. FlexibleLow costEasy to deploySupport portability. Remote Technologies. . . . UWB. . Bluetooth. . . . WiFi . 3G. range. BW. WiMax. . RFID. Fundamentals of Wireless Communication. SignalFrequency allocationSignal propagationAntennasMultiplexing. Review of Wireless Transmissions. . bitstream.
Transcripts
Slide 1

Remote Applications

Slide 2

Why Wireless? Adaptable Low cost Easy to convey Support versatility

Slide 3

Wireless Technologies BW UWB WiMax WiFi 3G Bluetooth RFID range

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Basics of Wireless Communication Signal Frequency assignment Signal spread Antennas Multiplexing

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source deciphering channel coding channel disentangling source coding demodulation adjustment Overview of Wireless Transmissions sender simple sign piece stream beneficiary piece stream

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Signals I Physical representation of information Function of time and area Classification persistent time/discrete time nonstop values/discrete qualities simple sign = consistent time and constant qualities computerized signal = discrete time and discrete qualities

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Signal II Signal parameters of intermittent signs: period T, recurrence f=1/T adequacy A stage shift  sine wave as unique occasional sign for a transporter: s(t) = A t sin(2  f t +  t ) 1 0 t

Slide 8

Fourier Transform: Every Signal Can be Decomposed as a Collection of Harmonics 1 0 t perfect occasional al advanced sign deterioration The more sounds utilized, the littler the estimation mistake.

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Why Not Send Digital Signal in Wireless Communications? Computerized signals need vast frequencies for flawless transmission anyway, we have restricted frequencies in remote interchanges

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Frequencies for C ommunication wound pair persuade link optical transmission 1 Mm 300 Hz 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100 m 3 THz 1 m 300 THz obvious light VLF LF MF HF VHF UHF SHF EHF infrared UV 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 & wave length:  = c/f , wave length  , rate of light c  3x10 8 m/s, recurrence f

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Frequencies and R egulations ITU-R holds barters for new frequencies, oversees recurrence groups around the world (WRC, World Radio Conferences)

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Why Need A Wide Spectrum : Shannon Channel Capacity The most extreme number of bits that can be transmitted every second by a physical channel is: W: recurrence run that the media permits to go through S/N: signal commotion proportion

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Signal, Noise, and Interference Signal (S) Noise (N) Includes warm clamor and foundation radiation Often demonstrated as added substance white Gaussian commotion Interference (I) Signals from other transmitting sources SINR = S/(N+I) (some of the time likewise signified as SNR)

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dB and Power transformation dB Denote the contrast between two force levels (P2/P1)[dB] = 10 * log10 (P2/P1) P2/P1 = 10^(A/10) Example: P2 = 100 P1 dBm and dBW Denote the force level in respect to 1 mW or 1 W P[dBm] = 10*log10(P/1mW) P[dB] = 10*log10(P/1W) Example: P = 0.001 mW, P = 100 W

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Outline Signal Frequency designation Signal engendering Antennas Multiplexing

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Signal P ropagation R anges Transmission range correspondence conceivable low blunder rate Detection range identification of the sign conceivable no correspondence conceivable Interference range sign may not be recognized sign adds to the foundation commotion sender transmission separation recognition obstruction

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Signal P ropagation Propagation in free space constantly like light (straight line) Receiving power relative to 1/d² (d = separation amongst sender and beneficiary) Receiving power furthermore affected by blurring (recurrence subordinate) shadowing reflection everywhere impediments refraction relying upon the thickness of a medium diffusing at little snags diffraction at edges refraction shadowing reflection disseminating diffraction

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Multipath P ropagation Signal can take various ways amongst sender and collector because of reflection, dissipating, diffraction Time scattering: sign is scattered after some time  obstruction with "neighbor" images, Inter Symbol Interference (ISI) The sign achieves a recipient specifically and stage moved  twisted sign in view of the periods of various parts LOS beats multipath beats LOS: Line Of Sight sign at sender signal at recipient

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Fading Channel qualities change over the long haul & area e.g., development of recipient and/or disperses  snappy changes in the force got (short term/quick blurring) Additional adjustments in separation to sender hindrances encourage away  moderate changes in the normal force got (long haul/moderate blurring) long haul blurring power t fleeting blurring

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Received Signal Power (dB) way misfortune shadow blurring Rayleigh blurring log (separation) Typical Picture

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Real world case

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Antennas: I sotropic R adiator Isotropic radiator: a solitary point rise to radiation every which way (three dimensional) just a hypothetical reference reception apparatus Radiation design: estimation of radiation around a recieving wire z y z perfect isotropic radiator y x Question: how does influence level abatement as an element of d, the separation from the sender?

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/4 /2 Antennas: Dipole Real radio wires are not isotropic radiators but rather, e.g., dipoles with lengths /4 on auto rooftops or /2 as Hertzian dipole  state of recieving wire relative to wavelength

Slide 25

Outline Signal Frequency allotment Signal engendering Antennas Multiplexing

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Multiplexing in 4 measurements space (s i ) time (t) recurrence (f) code (c) Goal: different utilization of a common medium Important: monitor spaces required!

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Space Multiplexing stations k i Assign every locale a station Pros no dynamic coordination important works additionally for simple signs Cons Inefficient asset usage k 1 k 2 k 3 k 4 k 5 k 6 c t c s 1 t s 2 f c t s 3 f

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Frequency Multiplexing Separation of the entire range into littler recurrence groups A station gets a specific band of the range for the entire time Pros: no dynamic coordination fundamental works likewise for simple signs Cons: misuse of transfer speed if the movement is disseminated unevenly Inflexible gatekeeper spaces k 1 k 2 k 3 k 4 k 5 k 6 c f t

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Time Multiplex A station gets the entire range for a specific measure of time Pros: stand out transporter in the medium whenever throughput high notwithstanding for some clients Cons: exact synchronization vital c f t

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Time and Frequency Multiplexing Combination of both strategies A station gets a specific recurrence band for a specific measure of time (e.g., GSM) Pros: better insurance against tapping security against recurrence particular obstruction higher information rates contrasted with code multiplex Cons: exact coordination required k 1 k 2 k 3 k 4 k 5 k 6 c f t

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Code Multiplexing Each station has an extraordinary code All stations utilize the same range at the same time Pros: transfer speed proficient no coordination and synchronization vital great assurance against impedance and tapping Cons: lower client information rates more mind boggling signal recovery Implemented utilizing spread range innovation c f t

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Basics of Wireless Communication (more) Signal Frequency allotment Signal proliferation Antennas Multiplexing Modulation Spread range

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source deciphering station coding station interpreting source coding demodulation regulation Overview of Wireless Transmissions sender simple sign piece stream beneficiary piece stream

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Modulation I Digital tweak advanced information is deciphered into a simple sign (baseband) Analog balance shifts focus recurrence of baseband sign up to the radio bearer Reasons Antenna size is on the request of sign\'s wavelength More data transfer capacity accessible at higher bearer recurrence Medium attributes: way misfortune, shadowing, reflection, scrambling, diffraction rely on upon sign\'s wavelength

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simple baseband signal computerized information computerized balance simple adjustment radio transmitter 101101001 radio transporter simple baseband signal advanced information simple demodulation synchronization choice radio recipient 101101001 radio bearer Modulation and Demodulation

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Modulation Schemes Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM)

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Digital M odulation Modulation of computerized signs known as Shift Keying Amplitude Shift Keying (ASK): Pros: basic Cons: vulnerable to clamor Example: optical framework, IFR 1 0 1 t

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Digital M odulation II Frequency Shift Keying (FSK): Pros: less powerless to commotion Cons: requires bigger data transfer capacity 1 0 1 t 1 0 1

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Digital M odulation III Phase Shift Keying (PSK): Pros: Less defenseless to commotion Bandwidth effective Cons: Require synchronization in recurrence and stage  confounds beneficiaries and transmitter t

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Q I 1 0 Q 11 10 I QPSK (Quadrature Phase Shift Keying): 2 bits coded as one image needs less transmission capacity contrasted with BPSK image decides movement of sine wave Often likewise transmission of relative, not total stage shift: DQPSK - Differential QPSK 00 01 A t 01 11 10 00 Phase Shift Keying BPSK (Binary Phase Shift Keying): bit esteem 0: sine wave bit esteem 1: reversed sine wave exceptionally straightforward PSK low phantom productivity strong, utilized as a part of satellite frameworks

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Example: 16-QAM (4 bits = 1 image) Symbols 0011 and 0001 have the same stage φ , however diverse plentifulness a . 0000 and 1000 have same adequacy however distinctive stage Used in Modem Q 0010 0001 0011 0000 φ I a 1000 Quadrature Amplitude Modulation Quadrature Amplitude Modulation (QAM): consolidates abundancy and stage adjustment It is conceivable to code n bits utilizing one image 2 n discrete levels bit blunder rate increments with n

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Outline Signal Frequency assignment Signal engendering Antennas Multiplexing Spread range

Slide 43

Spread range innovation Problem of radio transmission: recurrence subordinate blurring

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