Introduction to Digital Communications

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Introduction to Digital Communications

  1. 1. Francisco J. Escribano, 2016-17 DIGITAL COMMUNICATIONS Block 1 Introduction to Digital Communications
  2. 2. 2 Digital Communications: introduction
  3. 3. 3 Digital Communications: introduction COMMUNICATION THEORY
  4. 4. 4 Digital Communications: introduction COMMUNICATION THEORY BASIC CONCEPTS
  5. 5. 5 Digital Communications: introduction COMMUNICATION THEORY DIGITAL COMMUNICATIONS BASIC CONCEPTS
  6. 6. 6 Digital Communications: introduction COMMUNICATION THEORY DIGITAL COMMUNICATIONS BASIC CONCEPTS ADVANCED CONCEPTS
  7. 7. 7 Digital Communications: introduction COMMUNICATION THEORY DIGITAL COMMUNICATIONS BASIC CONCEPTS ADVANCED CONCEPTS
  8. 8. 8 Digital Communications: introduction COMMUNICATION THEORY DIGITAL COMMUNICATIONS COMMUNICATION SYSTEMS BASIC CONCEPTS ADVANCED CONCEPTS
  9. 9. 9 Digital Communications: introduction COMMUNICATION THEORY DIGITAL COMMUNICATIONS MOBILE COMMUNICATIONS COMMUNICATION SYSTEMS BASIC CONCEPTS ADVANCED CONCEPTS
  10. 10. 10 Digital Communications: introduction COMMUNICATION THEORY DIGITAL COMMUNICATIONS RADIATION AND RADIOCOMMUNICATION MOBILE COMMUNICATIONS COMMUNICATION SYSTEMS BASIC CONCEPTS ADVANCED CONCEPTS
  11. 11. 11 Digital Communications: introduction COMMUNICATION THEORY COMMUNICATION CIRCUITS DIGITAL COMMUNICATIONS RADIATION AND RADIOCOMMUNICATION MOBILE COMMUNICATIONS COMMUNICATION SYSTEMS BASIC CONCEPTS ADVANCED CONCEPTS
  12. 12. 12 Digital Communications: introduction ● Basic texts: – Bernard Sklar, Digital Communications, 2001, Prentice Hall (Chapter 1). – Simon Haykin, Communication Systems, 2010, Wiley (Background and preview). – John G. Proakis, Masoud Salehi, Digital Communications, 2008, McGraw-Hill (Chapter 1).
  13. 13. 13 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers
  14. 14. 14 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers
  15. 15. 15 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers
  16. 16. 16 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers Data Stream
  17. 17. 17 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers Data Stream Data Stream
  18. 18. 18 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers MEDIUM Data Stream Data Stream
  19. 19. 19 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers MEDIUM Data Stream Data Stream
  20. 20. 20 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers PHY (1) PHY (1) MEDIUM Data Stream Data Stream
  21. 21. 21 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers PHY (1) MAC (2) (<DLL) PHY (1) MAC (2) (<DLL) MEDIUM Data Stream Data Stream
  22. 22. 22 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers PHY (1) MAC (2) (<DLL) PHY (1) MAC (2) (<DLL) MEDIUM Data Stream ControlControl Data Stream
  23. 23. 23 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers PHY (1) MAC (2) (<DLL) PHY (1) MAC (2) (<DLL) MEDIUM Data Stream ControlControl Data Stream
  24. 24. 24 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers PHY (1) MAC (2) (<DLL) PHY (1) MAC (2) (<DLL) MEDIUM Digital Communications Data Stream ControlControl Data Stream
  25. 25. 25 Digital Communications: introduction ● Logical/functional organization of communications ⇒ layers PHY (1) MAC (2) (<DLL) PHY (1) MAC (2) (<DLL) MEDIUM Telematics Digital Communications Data Stream ControlControl Data Stream
  26. 26. 26 Digital Communications: introduction ● Before proceeding further... – All this is about... transferring information ● Some issues: – Can we precisely define information? – How can it and its quality be measured? – Are there any limitations to the amount of information we can transfer? ● And the answer is...
  27. 27. 27 Digital Communications: introduction ● Before proceeding further... – All this is about... transferring information ● Some issues: – Can we precisely define information? – How can it and its quality be measured? – Are there any limitations to the amount of information we can transfer? ● And the answer is... ?
  28. 28. 28 Digital Communications: introduction ● Before proceeding further... – All this is about... transferring information ● Some issues: – Can we precisely define information? – How can it and its quality be measured? – Are there any limitations to the amount of information we can transfer? ● And the answer is... INFORMATION THEORY (Block 2) Source: Wikipedia !
  29. 29. 29 Digital Communications: introduction ● What are the main functions carried out at the physical layer?
  30. 30. 30 Digital Communications: introduction ● What are the main functions carried out at the physical layer?
  31. 31. 31 Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem
  32. 32. 32 Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radio frequency -RF (analog)
  33. 33. 33 Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radio frequency -RF (analog) Upper layers (2,3...)
  34. 34. 34 Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radio frequency -RF (analog) Base- band (digital) Upper layers (2,3...)
  35. 35. 35 Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radio frequency -RF (analog) Base- band (digital) Upper layers (2,3...) ● Adaptation to the medium. ● Information protection. ● Sharing resources. ● Signal generation. ● Interface between RF and upper layers. ● Evaluation and compensation of channel distortions. ● …...........................................................
  36. 36. 36 Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radio frequency -RF (analog) Base- band (digital) Upper layers (2,3...) ● Adaptation to the medium. ● Information protection. ● Sharing resources. ● Signal generation. ● Interface between RF and upper layers. ● Evaluation and compensation of channel distortions. ● …...........................................................
  37. 37. 37 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially.
  38. 38. 38 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially.
  39. 39. 39 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially.
  40. 40. 40 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. PHY (1) TX
  41. 41. 41 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) PHY (1) TX
  42. 42. 42 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) PHY (1) TX
  43. 43. 43 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX
  44. 44. 44 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX
  45. 45. 45 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX CHANNEL1 Performance (1)
  46. 46. 46 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX CHANNEL1 Performance (1)
  47. 47. 47 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX CHANNEL1 Performance (1) CHANNEL2 Performance (2)
  48. 48. 48 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX CHANNEL1 Performance (1) CHANNEL2 Performance (2)
  49. 49. 49 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX CHANNEL1 Performance (1) CHANNEL2 Performance (2) CHANNEL3 Performance (3)
  50. 50. 50 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX CHANNEL1 Performance (1) CHANNEL2 Performance (2) CHANNEL3 Performance (3) Design & evaluation: Information Theory (Block 2)
  51. 51. 51 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially.
  52. 52. 52 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially.
  53. 53. 53 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially.
  54. 54. 54 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. PHY (1) RX
  55. 55. 55 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) PHY (1) RX
  56. 56. 56 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) PHY (1) RX
  57. 57. 57 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX
  58. 58. 58 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX
  59. 59. 59 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX CHANNEL1 Performance (1)
  60. 60. 60 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX CHANNEL1 Performance (1)
  61. 61. 61 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX CHANNEL2 Performance (2) CHANNEL1 Performance (1)
  62. 62. 62 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX CHANNEL2 Performance (2) CHANNEL1 Performance (1)
  63. 63. 63 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX CHANNEL2 Performance (2) CHANNEL1 Performance (1) CHANNEL3 Performance (3)
  64. 64. 64 Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX CHANNEL2 Performance (2) CHANNEL1 Performance (1) CHANNEL3 Performance (3) Design & evaluation: Information Theory (Block 2)
  65. 65. 65 Digital Communications: introduction ● Additional operations at the PHY. Source Destination
  66. 66. 66 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Source Destination
  67. 67. 67 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Encryption Source Destination
  68. 68. 68 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Encryption Source coding Source Destination
  69. 69. 69 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Encryption Source coding Source Destination
  70. 70. 70 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Source Destination
  71. 71. 71 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Decryption Source Destination
  72. 72. 72 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Decryption Source decoding Source Destination
  73. 73. 73 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Decryption Source decoding Source Destination
  74. 74. 74 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Decryption Source decoding Source Destination Block 2
  75. 75. 75 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Decryption Source decoding Source Destination Block 2
  76. 76. 76 Digital Communications: introduction ● Additional operations at the PHY. Medium accessMedium access (Block 4)(Block 4) ModulationModulation (CT & Block 2)(CT & Block 2) Channel codingChannel coding (Block 3)(Block 3) PHY (1) TX Distortion Noise Limitations Medium accessMedium access (Block 4)(Block 4) DemodulationDemodulation (CT & Block 2)(CT & Block 2) ChannelChannel decodingdecoding (Block 3)(Block 3) PHY (1) RX Encryption Source coding Decryption Source decoding Source Destination Block 2 Basichypothesis: equiprobablebinarysequence P(b=0)=P(b=1)=0.5
  77. 77. 77 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization.
  78. 78. 78 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude
  79. 79. 79 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude SNR, Eb/N0
  80. 80. 80 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude SNR, Eb/N0 Available power
  81. 81. 81 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude SNR, Eb/N0 Available power Transmission rate
  82. 82. 82 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude SNR, Eb/N0 Bandwidth Available power Transmission rate
  83. 83. 83 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude SNR, Eb/N0 Bandwidth Available power Transmission rate Error probability
  84. 84. 84 Digital Communications: introduction ● Design and performance criteria/parameters. – Already known for those familiar with Comunication Theory. – They are evaluated for each level/layer, point to point. – Basic issue: limitations and tradeoffs → optimization. iDude SNR, Eb/N0 Bandwidth Available power Transmission rate Error probability Distortion Interference
  85. 85. 85 Digital Communications: introduction
  86. 86. 86 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX)
  87. 87. 87 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax
  88. 88. 88 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax R1 SNR1 BW1 ...
  89. 89. 89 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax R2 SNR2 BW2 ... R1 SNR1 BW1 ...
  90. 90. 90 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax …...... R2 SNR2 BW2 ... R1 SNR1 BW1 ... Rn SNRn BWn ...
  91. 91. 91 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax …...... R2 SNR2 BW2 ... R1 SNR1 BW1 ... Rn SNRn BWn ... …...... R'2 SNR'2 BW'2 ... R'1 SNR'1 BW'1 ... R'n SNR'n BW'n ...
  92. 92. 92 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax …...... R2 SNR2 BW2 ... R1 SNR1 BW1 ... Rn SNRn BWn ... …...... R'2 SNR'2 BW'2 ... R'1 SNR'1 BW'1 ... R'n SNR'n BW'n ... SHARE AND MANAGE LIMITED RESOURCES
  93. 93. 93 MEDIUM Digital Communications: introduction Medium accessMedium access (TX)(TX) Medium accessMedium access (RX)(RX) Rmax ________ SNR ____ Allowed interference ____ Reliability ____ BWmax ____ Pmax …...... R2 SNR2 BW2 ... R1 SNR1 BW1 ... Rn SNRn BWn ... …...... R'2 SNR'2 BW'2 ... R'1 SNR'1 BW'1 ... R'n SNR'n BW'n ... SHARE AND MANAGE LIMITED RESOURCES Information Theory
  94. 94. 94 Digital Communications: introduction
  95. 95. 95 Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX)
  96. 96. 96 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX)
  97. 97. 97 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX) Rmod ____ SNR ____ Es/N0 ____ Ps (e) ____ BWmod ____ Pmod
  98. 98. 98 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX) Rmod ____ SNR ____ Es/N0 ____ Ps (e) ____ BWmod ____ Pmod
  99. 99. 99 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX) Rmod ____ SNR ____ Es/N0 ____ Ps (e) ____ BWmod ____ Pmod
  100. 100. 100 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX) Rmod ____ SNR ____ Es/N0 ____ Ps (e) ____ BWmod ____ Pmod Pb (e) _____ Eb/N0 _____ Rb
  101. 101. 101 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX) Rmod ____ SNR ____ Es/N0 ____ Ps (e) ____ BWmod ____ Pmod Pb (e) _____ Eb/N0 _____ Rb ADAPT SIGNALS TO THE CHANNEL AND IMPROVE PERFORMANCE
  102. 102. 102 CHANNEL Digital Communications: introduction ModulationModulation (TX)(TX) DemodulationDemodulation (RX)(RX) Rmod ____ SNR ____ Es/N0 ____ Ps (e) ____ BWmod ____ Pmod Pb (e) _____ Eb/N0 _____ Rb ADAPT SIGNALS TO THE CHANNEL AND IMPROVE PERFORMANCE Information Theory
  103. 103. 103 Digital Communications: introduction
  104. 104. 104 Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX)
  105. 105. 105 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX)
  106. 106. 106 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX) Pb (e) ________ Eb/N0(out) ____ Rb
  107. 107. 107 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX) Pb (e) ________ Eb/N0(out) ____ Rb
  108. 108. 108 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX) Pb (e) ________ Eb/N0(out) ____ Rb
  109. 109. 109 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX) Pb (e) ________ Eb/N0(out) ____ Rb P'b (e)<Pb (e) _____ Eb/N0(in) _____ R'b <Rb
  110. 110. 110 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX) Pb (e) ________ Eb/N0(out) ____ Rb P'b (e)<Pb (e) _____ Eb/N0(in) _____ R'b <Rb PROTECT INFORMATION INTEGRITY AT THE COST OF DATA RATE
  111. 111. 111 CHANNEL Digital Communications: introduction Channel codingChannel coding (TX)(TX) ChannelChannel decodingdecoding (RX)(RX) Pb (e) ________ Eb/N0(out) ____ Rb P'b (e)<Pb (e) _____ Eb/N0(in) _____ R'b <Rb PROTECT INFORMATION INTEGRITY AT THE COST OF DATA RATE Information Theory
  112. 112. 112 Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf )
  113. 113. 113 Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf )
  114. 114. 114 Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf )
  115. 115. 115 Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf )
  116. 116. 116 Digital Communications: introduction ● Medium access (channel identification).
  117. 117. 117 Digital Communications: introduction ● Medium access (channel identification).
  118. 118. 118 Digital Communications: introduction ● Medium access (channel identification).
  119. 119. 119 Digital Communications: introduction ● Medium access (channel identification). Signal generation
  120. 120. 120 Digital Communications: introduction ● Medium access + modulation.
  121. 121. 121 Digital Communications: introduction ● Medium access + modulation.
  122. 122. 122 Digital Communications: introduction ● Medium access + modulation.
  123. 123. 123 Digital Communications: introduction ● Medium access + modulation.
  124. 124. 124 Digital Communications: introduction ● Medium access + modulation.
  125. 125. 125 Digital Communications: introduction ● Medium access + modulation. Different modes for resource sharing
  126. 126. 126 Digital Communications: introduction ● Medium access + modulation. Different modes for resource sharing
  127. 127. 127 Digital Communications: introduction ● Modulation and channel coding.
  128. 128. 128 Digital Communications: introduction ● Modulation and channel coding.
  129. 129. 129 Digital Communications: introduction ● Modulation and channel coding.
  130. 130. 130 Digital Communications: introduction ● Modulation and channel coding. Modulator
  131. 131. 131 Digital Communications: introduction ● Modulation and channel coding. Modulator
  132. 132. 132 Digital Communications: introduction ● Modulation and channel coding. ModulatorChannel encoder
  133. 133. 133 Digital Communications: introduction ● Modulation and channel coding. ModulatorChannel encoder
  134. 134. 134 Digital Communications: introduction ● Channel encoder.
  135. 135. 135 Digital Communications: introduction ● Channel encoder.
  136. 136. 136 Digital Communications: introduction ● Channel encoder.
  137. 137. 137 Digital Communications: introduction ● Channel encoder.
  138. 138. 138 Digital Communications: introduction ● Channel encoder. Algebraic structure
  139. 139. 139 Digital Communications: introduction ● Channel encoder. Algebraic structure
  140. 140. 140 Digital Communications: introduction ● Channel encoder. Algebraic structure Implementation: finite-state machine
  141. 141. 141 Digital Communications: introduction ● It is important to discern – Abstract operations / layers (“divide and conquer”). – HW implementation. ● Recall always – Basic scheme of Digital Communications. – Design and evaluation parameters. – Concepts from Communication Theory and Signals and Systems. ● Main purpose: – Given some resources, and some target conditions and target performance, manage to evaluate and/or design the appropriate subsystems.

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