5 multiplexing dan media transmisi

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5 multiplexing dan media transmisi

  1. 1. MULTIPLEXING DAN MEDIA TRANSMISI Anhar, MT
  2. 2. OUTLINE Pengantar  FDM  TDM  WDM  Anhar : Komunikasi Data 2
  3. 3. TIU  Dpt menjelaskan proses multiplexing analog dan digital serta pengembangan teknologinya Anhar : Komunikasi Data 3
  4. 4. PENGANTAR  Mengapa multiplexing??? Keterbatasan bandwidth  Melahirkan teknik efisiensi kanal  Anhar : Komunikasi Data  Apa multiplexing 4
  5. 5. JENIS MULTIPLEXING Anhar : Komunikasi Data 5
  6. 6. FDM     Anhar : Komunikasi Data  Useful bandwidth of medium exceeds required bandwidth of channel Each signal is modulated to a different carrier frequency Carrier frequencies separated so signals do not overlap (guard bands) e.g. broadcast radio Channel allocated even if no data 6
  7. 7. DIAGRAM FDM Anhar : Komunikasi Data 7
  8. 8. FDM PROSES Anhar : Komunikasi Data 8
  9. 9. FDM OF THREE VOICE BAND SIGNALS Anhar : Komunikasi Data 9
  10. 10. CONTOH 1 Asumsikan bhw sebuah channel suara menduduki bandwidth 4 KHz. Kita perlu utk menggabungkan tiga channels suara kedlm sebuah link dng bandwidth 12 KHz, dr 20 hingga 32 KHz. Tunjukkan susunannya dng menggunakan FDM tanpa menggunakan guard bands.  Modulasikan masing2 tiga channels suara utk bandwidth yg berbeda-beda, spt pd slide berikut. Anhar : Komunikasi Data  10
  11. 11. PENYELESAIAN : Anhar : Komunikasi Data 11
  12. 12. SISTEM MULTIPLEXING ANALOG AT&T (USA)  Hierarchy of FDM schemes  Group   Supergroup Anhar : Komunikasi Data 12 voice channels (4kHz each) = 48kHz  Range 60kHz to 108kHz  60 channel  FDM of 5 group signals on carriers between 420kHz and 612 kHz   Mastergroup  10 supergroups 12
  13. 13. SISTEM MULTIPLEXING ANALOG Anhar : Komunikasi Data 13
  14. 14. SYNCRONOUS TDM Data rate of medium exceeds data rate of digital signal to be transmitted  Multiple digital signals interleaved in time  May be at bit level of blocks  Time slots preassigned to sources and fixed  Time slots allocated even if no data  Time slots do not have to be evenly distributed amongst sources  Anhar : Komunikasi Data 14
  15. 15. Anhar : Komunikasi Data 15
  16. 16. Time Slots dan Frames Anhar : Komunikasi Data Masing2 terminal/host memberikan “sebagian” dr time (time slot) Dlm TDM, sebuah frame terdiri dr satu siklus lengkap dr time slots, dimana satu slot didedikasikan ke masing2 pengirim. 16
  17. 17. SISTEM TDM Anhar : Komunikasi Data 17
  18. 18. TDM FRAMES  Pure TDM: mux-to-mux speed = penjumlahan terminal speeds  No loss of data (similar to voice call multiplexing) 28/11/2013 18
  19. 19. TDM LINK CONTROL No headers and tailers  Data link control protocols not needed  Flow control  Data rate of multiplexed line is fixed  If one channel receiver can not receive data, the others must carry on  The corresponding source must be quenched  This leaves empty slots   Error control  Errors are detected and handled by individual channel systems
  20. 20. DATA LINK CONTROL ON TDM
  21. 21. FRAMING No flag or SYNC characters bracketing TDM frames  Must provide synchronizing mechanism  Added digit framing   One control bit added to each TDM frame  Looks like another channel - “control channel” Identifiable bit pattern used on control channel  e.g. alternating 01010101…unlikely on a data channel  Can compare incoming bit patterns on each channel with sync pattern 
  22. 22. PULSE STUFFING Problem - Synchronizing data sources  Clocks in different sources drifting  Data rates from different sources not related by simple rational number  Solution - Pulse Stuffing     Outgoing data rate (excluding framing bits) higher than sum of incoming rates Stuff extra dummy bits or pulses into each incoming signal until it matches local clock Stuffed pulses inserted at fixed locations in frame and removed at demultiplexer
  23. 23. TDM OF ANALOG AND DIGITAL SOURCES
  24. 24. DIGITAL CARRIER SYSTEMS Hierarchy of TDM  USA/Canada/Japan use one system  ITU-T use a similar (but different) system  US system based on DS-1 format  Multiplexes 24 channels  Each frame has 8 bits per channel plus one framing bit  193 bits per frame 
  25. 25. DIGITAL CARRIER SYSTEMS (2)  For voice each channel contains one word of digitized data (PCM, 8000 samples per sec) Data rate 8000x193 = 1.544Mbps  Five out of six frames have 8 bit PCM samples  Sixth frame is 7 bit PCM word plus signaling bit  Signaling bits form stream for each channel containing control and routing info   Same format for digital data  23 channels of data   7 bits per frame plus indicator bit for data or systems control 24th channel is sync
  26. 26. DCS  Hirarki sinyal digital utk layanan telepon yg menggunakan multiplexing digital.. Anhar : Komunikasi Data 26
  27. 27. T LINES  DS : nama layanannya sementara T : nama saluran yg dipakai utk layanan tsb Anhar : Komunikasi Data 27
  28. 28. T-1 FRAME Anhar : Komunikasi Data 28
  29. 29. E LINES Anhar : Komunikasi Data 29
  30. 30. contoh 1 Anhar, ST, MT. Penyelesaian 28/11/2013 Empat koneksi 1-Kbps dimultiplexing bersama-sama. Satu unitnya 1 bit. Tentukan (1) durasi 1 bit sebelum dimultiplexing, (2) transmission rate dr link, (3) durasi dr time slot, and (4) durasi dr frame? Kita dpt menjawabnya : 1. durasi 1 bit adlh 1/1 Kbps, atau 0.001 s (1 ms). 2. rate link adlh 4 Kbps. 3. duratsi dr tiap time slot 1/4 ms atau 250 ms. 4. durasi dr sebuah frame 1 ms. 30
  31. 31. PENYELESAIAN SECARA RINCI : Anhar, ST, MT. 1bit 1bit  4000bps 4000bit / sec ond  0.25ms / bit  250ms / bit BitDurationlink  28/11/2013 DataRatelink  4 1kbps  4kbps  4000bps TimeSlotDurationlink  BitDuration  UnitSize  250ms / bit 1bit / TimeSlot  250ms / TimeSlot FrameDuration  TimeSlotDuration  ChannelNumber  250ms / TimeSlot * 4TimeSlot / Frame  1ms / Frame 31
  32. 32. INTERLEAVING   Multiplexer/Demultiplexer memproses terminal/host’s unit saling berkebalikan Character (byte) Interleaving   Multiplexing membentuk satu/lebih karakter(s) or byte(s) pd sebuah waktu (one byte per unit) Bit Interleaving  Multiplexing membentuk one bit pd satu waktu (one bit per unit) 28/11/2013 32
  33. 33. Contoh 2 28/11/2013 Anhar, ST, MT. Empat kanal dimultiplex menggunakan TDM. Bila masing2 kanal mengirimkan100 bytes/s dan kita memultiplex 1 byte per kanal, tunjukkan perambatan frame pd link, ukuran dr frame, durasi dr frame, kecepatan frame, dan bit rate dr link. Penyelesaian 33
  34. 34. PENYELESAIAN RINCI  4byte / frame  32bit / frame  400  bytes / sec ond  3200bps Anhar, ST, MT. DataRatelink  4 100bytes / sec ond 28/11/2013 FrameSize  ChannelNumber  UnitSize  4timeslot / frame1byte / timeslot FrameRatelink  DataRate/ FrameSize 3200bit / sec ond  100 frame / sec ond 32bit / frame 1 FrameDuration  FrameRate  10ms / frame  34
  35. 35. Contoh 3 28/11/2013 Sebuah multiplexer menggabungkan empat 100-Kbps kannels menggunakan sebuah time slot dr 2 bits. Tunjukkan output dng empat input sembarang. Berapakah frame ratenya? Berapakah durasi frame? Berapa bit rate? Berapa bit duration? Anhar, ST, MT. Solution 35
  36. 36. PENYELE RINCI  4timeslot / frame 2bit / timeslot  8bit / frame DataRatelink  4 100kbps  400kbps 1 1  sec ond / bit BitRate 400k FrameRatelink  DataRate/ FrameSize Anhar, ST, MT. BitDurationlink  28/11/2013 SAIAN FrameSize  ChannelNumber  UnitSize 400kbit / sec ond  50kframe/ sec ond 8bit / frame  50,000 frame / sec ond  FrameDuration   1 FrameRate 1  20ms / frame 50,000 frame / sec ond 36
  37. 37. SINKRONISASI   Satu /lebih Framing bit (s) ditambahkan ke masing2 frame utk singkronisasi antara multiplexer dan demultiplxer Bila framing bit per frame, framing bits berubah-ubah antara 0 dan 1 28/11/2013 37
  38. 38. Contoh 4 28/11/2013 Anhar, ST, MT. Kita memiliki 4 sumber, masing2 membangkitkan 250 karakter per second. Bila interleaved unit adlh sebuah karakter dan 1 singkronisasi bit is ditambahkan ke masing2 frame, tentukan (1) data rate dr masing2 sumber, (2) durasi dr masing2 karakter dlm masing2 sumber, (3) frame rate, (4) durasi dr masing2 frame, (5) jumlah bits pd masing2 frame, dan (6) data rate dr link. Penyelesaian Lihat slide berikutnya 38
  39. 39. Penyelesaian 28/11/2013 Kita dpt menjawab pertanyaan tsb sbb berikut : Anhar, ST, MT. 1. Data rate dr masing2 sumber adlh 2000 bps = 2 Kbps. 2. Durasi dr sebuah karakter adlh 1/250 s, or 4 ms. 3. Link diperlukan utk mengirim 250 frames per second. 4. Durasi dr masing2 frame adlh 1/250 s, or 4 ms. 5. Masing2 frame adlh 4 x 8 + 1 = 33 bits. 6. Data rate dr link adlh 250 x 33, or 8250 bps. 39
  40. 40.  4timeslot / frame1character / timeslot  1bit / frame  33bits / frame FrameRate  250 frame / sec ond Anhar, ST, MT. SAIAN FrameSize  ChannelNumber  UnitSize  Fra min gBits 28/11/2013 PENYELE DataRate  FrameRate FrameSize  250 frame / sec ond  33bits / frame  8250bit / sec ond 40
  41. 41. Contoh 5 Anhar, ST, MT. Penyelesaian 28/11/2013 Dua kannels, satu dng bit rate 100 Kbps dan yg lain dng bit rate 200 Kbps, dimultiplex. Bagaimana hal ini dpt dilakukan? Berapakah frame rate? Berapa frame duration? Berapa bit rate dr link? Kita dpt mengalokasikan satu slot utk channel pertama dan dua slot utk channel kedua. Masing2 frame membawa 3 bits. Frame ratenya adlh 100,000 frames per second krn ia membawa 1 bit dr channel pertama. Frame duration nya adlh 1/100,000 s, atau 10 us. Bit rate adlh 41 100,000 frames/s x 3 bits/frame, atau 300 Kbps.
  42. 42. PENYELESAIAN RINCI DataRatelink  100kbps  200kbps  300kbps  3bit / frame 300kbit / sec ond  100kframe/ sec ond 3bit / frame  100,000 frame / sec ond  FrameDuration   Anhar, ST, MT. FrameRatelink  DataRate / FrameSize 28/11/2013 FrameSize  UnitSize1  UnitSize2 1 FrameRate 1  10ms / frame 100,000 frame / sec ond 42
  43. 43. WDM WDM dirancang utk membawa data dng kec tinggi...  Secara prinsip sama dng FDM...  Hanya menggunakan perbedaan panjang gel..  Anhar : Komunikasi Data 43
  44. 44. STATISTICAL TDM Anhar : Komunikasi Data 44
  45. 45. MEDIA TRANSMISI - OVERVIEW Guided - wire  Unguided - wireless  Characteristics and quality determined by medium and signal  For guided, the medium is more important  For unguided, the bandwidth produced by the antenna is more important  Key concerns are data rate and distance 
  46. 46. DESIGN FACTORS  Bandwidth   Higher bandwidth gives higher data rate Transmission impairments  Attenuation Interference  Number of receivers  In guided media  More receivers (multi-point) introduce more attenuation 
  47. 47. ELECTROMAGNETIC SPECTRUM
  48. 48. GUIDED TRANSMISSION MEDIA Twisted Pair  Coaxial cable  Optical fiber 
  49. 49. TWISTED PAIR
  50. 50. TWISTED PAIR - APPLICATIONS Most common medium  Telephone network    Within buildings   Between house and local exchange (subscriber loop) To private branch exchange (PBX) For local area networks (LAN)  10Mbps or 100Mbps
  51. 51. TWISTED PAIR - PROS AND CONS Cheap  Easy to work with  Low data rate  Short range 
  52. 52. TWISTED PAIR - TRANSMISSION CHARACTERISTICS  Analog   Amplifiers every 5km to 6km Digital Use either analog or digital signals  repeater every 2km or 3km  Limited distance  Limited bandwidth (1MHz)  Limited data rate (100MHz)  Susceptible to interference and noise 
  53. 53. UNSHIELDED AND SHIELDED TP  Unshielded Twisted Pair (UTP) Ordinary telephone wire  Cheapest  Easiest to install  Suffers from external EM interference   Shielded Twisted Pair (STP) Metal braid or sheathing that reduces interference  More expensive  Harder to handle (thick, heavy) 
  54. 54. UTP CATEGORIES  Cat 3 up to 16MHz  Voice grade found in most offices  Twist length of 7.5 cm to 10 cm   Cat 4   up to 20 MHz Cat 5 up to 100MHz  Commonly pre-installed in new office buildings  Twist length 0.6 cm to 0.85 cm 
  55. 55. NEAR END CROSSTALK Coupling of signal from one pair to another  Coupling takes place when transmit signal entering the link couples back to receiving pair  i.e. near transmitted signal is picked up by near receiving pair 
  56. 56. COAXIAL CABLE
  57. 57. COAXIAL CABLE APPLICATIONS Most versatile medium  Television distribution  Ariel to TV  Cable TV   Long distance telephone transmission   Can carry 10,000 voice calls simultaneously Being replaced by fiber optic Short distance computer systems links  Local area networks 
  58. 58. COAXIAL CABLE - TRANSMISSION CHARACTERISTICS  Analog Amplifiers every few km  Closer if higher frequency  Up to 500MHz   Digital Repeater every 1km  Closer for higher data rates 
  59. 59. OPTICAL FIBER
  60. 60. OPTICAL FIBER - BENEFITS  Greater capacity  Data rates of hundreds of Gbps Smaller size & weight  Lower attenuation  Electromagnetic isolation  Greater repeater spacing   10s of km at least
  61. 61. OPTICAL FIBER - APPLICATIONS Long-haul trunks  Metropolitan trunks  Rural exchange trunks  Subscriber loops  LANs 
  62. 62. OPTICAL FIBER - TRANSMISSION CHARACTERISTICS  Act as wave guide for 1014 to 1015 Hz   Portions of infrared and visible spectrum Light Emitting Diode (LED) Cheaper  Wider operating temp range  Last longer   Injection Laser Diode (ILD) More efficient  Greater data rate   Wavelength Division Multiplexing
  63. 63. OPTICAL FIBER TRANSMISSION MODES
  64. 64. WIRELESS TRANSMISSION Unguided media  Transmission and reception via antenna  Directional  Focused beam  Careful alignment required   Omnidirectional Signal spreads in all directions  Can be received by many antennae 
  65. 65. FREQUENCIES  2GHz to 40GHz Microwave  Highly directional  Point to point  Satellite   30MHz to 1GHz Omnidirectional  Broadcast radio   3 x 1011 to 2 x 1014   Infrared Local
  66. 66. TERRESTRIAL MICROWAVE Parabolic dish  Focused beam  Line of sight  Long haul telecommunications  Higher frequencies give higher data rates 
  67. 67. SATELLITE MICROWAVE Satellite is relay station  Satellite receives on one frequency, amplifies or repeats signal and transmits on another frequency  Requires geo-stationary orbit   Height of 35,784km Television  Long distance telephone  Private business networks 
  68. 68. BROADCAST RADIO Omnidirectional  FM radio  UHF and VHF television  Line of sight  Suffers from multipath interference   Reflections
  69. 69. INFRARED Modulate noncoherent infrared light  Line of sight (or reflection)  Blocked by walls  e.g. TV remote control, IRD port 
  70. 70. REQUIRED READING Stallings Chapter 4  Komunikasi data by Dony 

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