Introduction to Digital Communications

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  • 1. DIGITAL COMMUNICATIONS Block 1 Introduction to Digital Communications Francisco J. Escribano, 2013-14
  • 2. Digital Communications: introduction 2
  • 3. Digital Communications: introduction COMMUNICATION THEORY 3
  • 4. Digital Communications: introduction COMMUNICATION THEORY BASIC CONCEPTS 4
  • 5. Digital Communications: introduction COMMUNICATION THEORY BASIC CONCEPTS DIGITAL COMMUNICATIONS 5
  • 6. Digital Communications: introduction COMMUNICATION THEORY BASIC CONCEPTS DIGITAL COMMUNICATIONS ADVANCED CONCEPTS 6
  • 7. Digital Communications: introduction COMMUNICATION THEORY BASIC CONCEPTS DIGITAL COMMUNICATIONS ADVANCED CONCEPTS 7
  • 8. Digital Communications: introduction COMMUNICATION THEORY COMMUNICATION SYSTEMS BASIC CONCEPTS DIGITAL COMMUNICATIONS ADVANCED CONCEPTS 8
  • 9. Digital Communications: introduction COMMUNICATION THEORY COMMUNICATION SYSTEMS BASIC CONCEPTS DIGITAL COMMUNICATIONS MOBILE COMMUNICATIONS ADVANCED CONCEPTS 9
  • 10. Digital Communications: introduction COMMUNICATION THEORY COMMUNICATION SYSTEMS BASIC CONCEPTS DIGITAL COMMUNICATIONS MOBILE COMMUNICATIONS ADVANCED CONCEPTS RADIATION AND RADIOCOMMUNICATION 10
  • 11. Digital Communications: introduction COMMUNICATION THEORY COMMUNICATION SYSTEMS BASIC CONCEPTS DIGITAL COMMUNICATIONS MOBILE COMMUNICATIONS ADVANCED CONCEPTS COMMUNICATION CIRCUITS RADIATION AND RADIOCOMMUNICATION 11
  • 12. Digital Communications: introduction ● Basic texts: – Bernard Sklar, Digital Communications, 2001, Prentice Hall (Chapter 1). – Simon Haykin, Communication Systems, 2001, Wiley (Background and preview). – John G. Proakis, Digital McGraw-Hill (Chapter 1). Communications, 2008, 12
  • 13. Digital Communications: introduction ● Logical organization of communications ⇒ layers 13
  • 14. Digital Communications: introduction ● Logical organization of communications ⇒ layers 14
  • 15. Digital Communications: introduction ● Logical organization of communications ⇒ layers 15
  • 16. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream 16
  • 17. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream 17
  • 18. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream MEDIUM 18
  • 19. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream MEDIUM 19
  • 20. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream PHY (1) PHY (1) MEDIUM 20
  • 21. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream MAC (2) (<DLL) MAC (2) (<DLL) PHY (1) PHY (1) MEDIUM 21
  • 22. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream MAC (2) (<DLL) MAC (2) (<DLL) Control Control PHY (1) PHY (1) MEDIUM 22
  • 23. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream MAC (2) (<DLL) MAC (2) (<DLL) Control Control PHY (1) PHY (1) MEDIUM 23
  • 24. Digital Communications: introduction ● Logical organization of communications ⇒ layers Data Stream Data Stream MAC (2) (<DLL) MAC (2) (<DLL) Control PHY (1) Digital Communications Control PHY (1) MEDIUM 24
  • 25. Digital Communications: introduction ● Logical organization of communications ⇒ layers Telematics Data Stream Data Stream MAC (2) (<DLL) MAC (2) (<DLL) Control PHY (1) Digital Communications Control PHY (1) MEDIUM 25
  • 26. Digital Communications: introduction ● Before proceeding further... – ● All this is about... transferring information Some issues: – – How can it and its quality be measured? – ● Can we precisely define information? Are there any limitations to the amount of information we can transfer? And the answer is... 26
  • 27. Digital Communications: introduction ● Before proceeding further... – ● All this is about... transferring information ? Some issues: – – How can it and its quality be measured? – ● Can we precisely define information? Are there any limitations to the amount of information we can transfer? And the answer is... 27
  • 28. Digital Communications: introduction ● Before proceeding further... – ● All this is about... transferring information ! Some issues: – – How can it and its quality be measured? – ● Can we precisely define information? Are there any limitations to the amount of information we can transfer? And the answer is... Source: Wikipedia INFORMATION THEORY (Block 2) 28
  • 29. Digital Communications: introduction ● What are the main functions carried out at the physical layer? 29
  • 30. Digital Communications: introduction ● What are the main functions carried out at the physical layer? 30
  • 31. Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem 31
  • 32. Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radiofrequence (analog) 32
  • 33. Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radiofrequence (analog) Upper layers (2,3...) 33
  • 34. Digital Communications: introduction ● What are the main functions carried out at the physical layer? WIFI CARD in ADSL modem Radiofrequence (analog) Baseband (digital) Upper layers (2,3...) 34
  • 35. Digital Communications: introduction ● What are the main functions carried out at the physical layer? Adaptation to the medium. ● Information protection. ● Sharing resources. ● Signal generation. ● Interface between RF and upper layers. ● Evaluation and compensation of channel distortions. ● …........................................................... ● Radiofrequence (analog) Baseband (digital) WIFI CARD in ADSL modem Upper layers (2,3...) 35
  • 36. Digital Communications: introduction ● What are the main functions carried out at the physical layer? Adaptation to the medium. ● Information protection. ● Sharing resources. ● Signal generation. ● Interface between RF and upper layers. ● Evaluation and compensation of channel distortions. ● …........................................................... ● Radiofrequence (analog) Baseband (digital) WIFI CARD in ADSL modem Upper layers (2,3...) 36
  • 37. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. 37
  • 38. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. 38
  • 39. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. 39
  • 40. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. PHY (1) TX 40
  • 41. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium access (Block 4) PHY (1) TX 41
  • 42. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 42
  • 43. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Channel coding (Block 3) Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 43
  • 44. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Channel coding (Block 3) Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 44
  • 45. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) Channel coding (Block 3) Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 45
  • 46. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) Channel coding (Block 3) Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 46
  • 47. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL2 CHANNEL1 Performance (2) Channel coding (Block 3) Performance (1) Modulation (CT & Block 2) Medium access (Block 4) PHY (1) TX 47
  • 48. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL2 CHANNEL1 Performance (2) Channel coding (Block 3) Performance (1) Modulation (CT & Block 2) Medium access (Block 4) PHY (1) TX 48
  • 49. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL2 CHANNEL1 Performance (2) Performance (1) Modulation (CT & Block 2) Medium access (Block 4) CHANNEL3 Performance (3) Channel coding (Block 3) PHY (1) TX 49
  • 50. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL2 Performance (2) CHANNEL1 Performance (1) CHANNEL3 Performance (3) Design & evaluation: Information Theory (Block 2) Channel coding (Block 3) Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 50
  • 51. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. 51
  • 52. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. 52
  • 53. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. 53
  • 54. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. PHY (1) RX 54
  • 55. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium access (Block 4) PHY (1) RX 55
  • 56. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX 56
  • 57. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 57
  • 58. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 58
  • 59. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 59
  • 60. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 60
  • 61. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) Medium access (Block 4) CHANNEL2 Performance (2) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 61
  • 62. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) Medium access (Block 4) CHANNEL2 Performance (2) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 62
  • 63. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 Performance (1) CHANNEL2 Performance (2) CHANNEL3 Performance (3) Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 63
  • 64. Digital Communications: introduction ● NOTE: conceptually separated operations. – Implementation may be done jointly instead of sequentially. CHANNEL1 CHANNEL2 Performance (1) Performance (2) CHANNEL3 Design & evaluation: Performance (3) Information Theory (Block 2) Medium access (Block 4) Demodulation (CT & Block 2) PHY (1) RX Channel decoding (Block 3) 64
  • 65. Digital Communications: introduction ● Additional operations at the PHY. Destination Source 65
  • 66. Digital Communications: introduction ● Additional operations at the PHY. Destination Source Channel coding (Block 3) Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 66
  • 67. Digital Communications: introduction ● Additional operations at the PHY. Destination Encryption Channel coding (Block 3) Source Modulation (CT & Block 2) PHY (1) TX Medium access (Block 4) 67
  • 68. Digital Communications: introduction ● Additional operations at the PHY. Destination Encryption Channel coding (Block 3) Source coding Source Modulation (CT & Block 2) Medium access (Block 4) PHY (1) TX 68
  • 69. Digital Communications: introduction ● Additional operations at the PHY. Destination Encryption Channel coding (Block 3) Source coding Source Modulation (CT & Block 2) Distortion Noise Limitations Medium access (Block 4) PHY (1) TX 69
  • 70. Digital Communications: introduction ● Additional operations at the PHY. PHY (1) RX Channel decoding (Block 3) Demodulation (CT & Block 2) Medium access (Block 4) Destination Encryption Channel coding (Block 3) Source coding Source Modulation (CT & Block 2) Distortion Noise Limitations Medium access (Block 4) PHY (1) TX 70
  • 71. Digital Communications: introduction ● Additional operations at the PHY. PHY (1) RX Channel decoding (Block 3) Demodulation (CT & Block 2) Destination Decryption Encryption Channel coding (Block 3) Medium access (Block 4) Source coding Source Modulation (CT & Block 2) Distortion Noise Limitations Medium access (Block 4) PHY (1) TX 71
  • 72. Digital Communications: introduction ● Additional operations at the PHY. PHY (1) RX Channel decoding (Block 3) Demodulation (CT & Block 2) Medium access (Block 4) Decryption Source decoding Destination Encryption Source coding Source Modulation (CT & Block 2) Medium access (Block 4) Channel coding (Block 3) PHY (1) TX Distortion Noise Limitations 72
  • 73. Digital Communications: introduction ● Additional operations at the PHY. PHY (1) RX Channel decoding (Block 3) Demodulation (CT & Block 2) Medium access (Block 4) Decryption Source decoding Destination Encryption Source coding Source Modulation (CT & Block 2) Medium access (Block 4) Channel coding (Block 3) PHY (1) TX Distortion Noise Limitations 73
  • 74. Digital Communications: introduction ● Additional operations at the PHY. PHY (1) RX Channel decoding (Block 3) Decryption Encryption Channel coding (Block 3) Medium access (Block 4) Demodulation (CT & Block 2) Source decoding Destination Block 2 Source coding Source Modulation (CT & Block 2) Distortion Noise Limitations Medium access (Block 4) PHY (1) TX 74
  • 75. Digital Communications: introduction ● Additional operations at the PHY. PHY (1) RX Channel decoding (Block 3) Decryption Encryption Channel coding (Block 3) Medium access (Block 4) Demodulation (CT & Block 2) Source decoding Destination Block 2 Source coding Source Modulation (CT & Block 2) Distortion Noise Limitations Medium access (Block 4) PHY (1) TX 75
  • 76. Digital Communications: introduction ● Additional operations at the PHY. Basic hypothesis: equiprobable binary sequence P(b=0)=P(b=1)=0.5 PHY (1) RX Channel decoding (Block 3) Decryption Encryption Channel coding (Block 3) Medium access (Block 4) Demodulation (CT & Block 2) Source decoding Destination Block 2 Source coding Source Modulation (CT & Block 2) Distortion Noise Limitations Medium access (Block 4) PHY (1) TX 76
  • 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. 77
  • 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 78
  • 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. SNR, Eb/N0 iDude 79
  • 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. SNR, Eb/N0 iDude Available power 80
  • 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. Transmission rate SNR, Eb/N0 iDude Available power 81
  • 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. Transmission rate SNR, Eb/N0 iDude Bandwidth Available power 82
  • 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. Transmission rate SNR, Eb/N0 iDude Error probability Bandwidth Available power 83
  • 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. Distortion Interference Transmission rate SNR, Eb/N0 iDude Error probability Bandwidth Available power 84
  • 85. Digital Communications: introduction 85
  • 86. Digital Communications: introduction Medium access (RX) MEDIUM Medium access (TX) 86
  • 87. Digital Communications: introduction Rmax Medium access (RX) ________ SNR ____ Allowed interference MEDIUM ____ Reliability ____ Medium access (TX) BWmax ____ Pmax 87
  • 88. Digital Communications: introduction Rmax Medium access (RX) ________ SNR ____ Allowed interference MEDIUM ____ Reliability ____ Medium access (TX) R1 SNR1 BW1... BWmax ____ Pmax 88
  • 89. Digital Communications: introduction Rmax Medium access (RX) ________ SNR ____ Allowed interference MEDIUM ____ Reliability ____ R2 SNR2 BW2... R1 SNR1 BW1... Medium access (TX) BWmax ____ Pmax 89
  • 90. Digital Communications: introduction Rmax Medium access (RX) ________ SNR ____ Rn SNRn BWn... R2 SNR2 BW2... R1 SNR1 BW1... …...... Allowed interference MEDIUM ____ Reliability ____ Medium access (TX) BWmax ____ Pmax 90
  • 91. Digital Communications: introduction R'2 SNR'2 BW'2... R'1 SNR'1 BW'1... …...... R'n SNR'n BW'n... Rmax Medium access (RX) ________ SNR ____ Rn SNRn BWn... R2 SNR2 BW2... R1 SNR1 BW1... …...... Allowed interference MEDIUM ____ Reliability ____ Medium access (TX) BWmax ____ Pmax 91
  • 92. Digital Communications: introduction Rn SNRn BWn... R2 SNR2 BW2... R1 SNR1 BW1... Rmax Medium access (RX) SHARE AND MANAGE LIMITED RESOURCES …...... R'2 SNR'2 BW'2... R'1 SNR'1 BW'1... …...... R'n SNR'n BW'n... Medium access (TX) ________ SNR ____ Allowed interference MEDIUM ____ Reliability ____ BWmax ____ Pmax 92
  • 93. Digital Communications: introduction Rn SNRn BWn... R2 SNR2 BW2... R1 SNR1 BW1... Rmax Medium access (RX) SHARE AND MANAGE LIMITED RESOURCES …...... R'2 SNR'2 BW'2... R'1 SNR'1 BW'1... …...... R'n SNR'n BW'n... Medium access (TX) Information Theory ________ SNR ____ Allowed interference MEDIUM ____ Reliability ____ BWmax ____ Pmax 93
  • 94. Digital Communications: introduction 94
  • 95. Digital Communications: introduction Demodulation (RX) Modulation (TX) 95
  • 96. Digital Communications: introduction Demodulation (RX) CHANNEL Modulation (TX) 96
  • 97. Digital Communications: introduction Demodulation (RX) Rmod ________ CHANNEL SNR ____ Ps(e) ____ BWmod ____ Modulation (TX) Pmod 97
  • 98. Digital Communications: introduction Demodulation (RX) Rmod ________ CHANNEL SNR ____ Ps(e) ____ BWmod ____ Modulation (TX) Pmod 98
  • 99. Digital Communications: introduction Demodulation (RX) Rmod ________ CHANNEL SNR ____ Ps(e) ____ BWmod ____ Modulation (TX) Pmod 99
  • 100. Digital Communications: introduction Demodulation (RX) Rmod ________ CHANNEL Pb(e) _____ Eb/N0 _____ Rb SNR ____ Ps(e) ____ BWmod ____ Modulation (TX) Pmod 100
  • 101. Digital Communications: introduction Demodulation (RX) Eb/N0 _____ Rb ADAPT SIGNALS TO THE CHANNEL AND IMPROVE PERFORMANCE CHANNEL Pb(e) _____ Rmod Modulation (TX) ________ SNR ____ Ps(e) ____ BWmod ____ Pmod 101
  • 102. Digital Communications: introduction Demodulation (RX) Eb/N0 _____ Rb ADAPT SIGNALS TO THE CHANNEL AND IMPROVE PERFORMANCE CHANNEL Pb(e) _____ Rmod Information Modulation (TX) Theory ________ SNR ____ Ps(e) ____ BWmod ____ Pmod 102
  • 103. Digital Communications: introduction 103
  • 104. Digital Communications: introduction Channel decoding (RX) Channel coding (TX) 104
  • 105. Digital Communications: introduction Channel decoding (RX) CHANNEL Channel coding (TX) 105
  • 106. Digital Communications: introduction Channel decoding (RX) CHANNEL Pb(e) ________ Eb/N0(out) ____ Rb Channel coding (TX) 106
  • 107. Digital Communications: introduction Channel decoding (RX) CHANNEL Pb(e) ________ Eb/N0(out) ____ Rb Channel coding (TX) 107
  • 108. Digital Communications: introduction Channel decoding (RX) CHANNEL Pb(e) ________ Eb/N0(out) ____ Rb Channel coding (TX) 108
  • 109. Digital Communications: introduction Channel decoding (RX) CHANNEL P'b(e)<Pb(e) _____ Eb/N0(in) _____ R'b<Rb Pb(e) ________ Eb/N0(out) ____ Rb Channel coding (TX) 109
  • 110. Digital Communications: introduction Channel decoding (RX) Eb/N0(in) _____ R'b<Rb CHANNEL P'b(e)<Pb(e) _____ PROTECT INFORMATION INTEGRITY AT THE COST OF SPEED Pb(e) ________ Eb/N0(out) ____ Rb Channel coding (TX) 110
  • 111. Digital Communications: introduction Channel decoding (RX) Eb/N0(in) _____ R'b<Rb CHANNEL P'b(e)<Pb(e) _____ PROTECT INFORMATION INTEGRITY AT THE COST OF SPEED Pb(e) ________ Eb/N0(out) ____ Rb Information Channel coding (TX) Theory 111
  • 112. Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf ) 112
  • 113. Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf ) 113
  • 114. Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf ) 114
  • 115. Digital Communications: introduction ● Example: WiFi standard (public access: http://standards.ieee.org/getieee802/download/802.11-2007.pdf ) 115
  • 116. Digital Communications: introduction ● Medium access (channel identification). 116
  • 117. Digital Communications: introduction ● Medium access (channel identification). 117
  • 118. Digital Communications: introduction ● Medium access (channel identification). 118
  • 119. Digital Communications: introduction ● Medium access (channel identification). Signal generation 119
  • 120. Digital Communications: introduction ● Medium access + modulation. 120
  • 121. Digital Communications: introduction ● Medium access + modulation. 121
  • 122. Digital Communications: introduction ● Medium access + modulation. 122
  • 123. Digital Communications: introduction ● Medium access + modulation. 123
  • 124. Digital Communications: introduction ● Medium access + modulation. 124
  • 125. Digital Communications: introduction ● Medium access + modulation. Different modes for resource sharing 125
  • 126. Digital Communications: introduction ● Medium access + modulation. Different modes for resource sharing 126
  • 127. Digital Communications: introduction ● Modulation and channel coding. 127
  • 128. Digital Communications: introduction ● Modulation and channel coding. 128
  • 129. Digital Communications: introduction ● Modulation and channel coding. 129
  • 130. Digital Communications: introduction ● Modulation and channel coding. Modulator 130
  • 131. Digital Communications: introduction ● Modulation and channel coding. Modulator 131
  • 132. Digital Communications: introduction ● Modulation and channel coding. Channel encoder Modulator 132
  • 133. Digital Communications: introduction ● Modulation and channel coding. Channel encoder Modulator 133
  • 134. Digital Communications: introduction ● Channel encoder. 134
  • 135. Digital Communications: introduction ● Channel encoder. 135
  • 136. Digital Communications: introduction ● Channel encoder. 136
  • 137. Digital Communications: introduction ● Channel encoder. 137
  • 138. Digital Communications: introduction ● Channel encoder. Algebraic structure 138
  • 139. Digital Communications: introduction ● Channel encoder. Algebraic structure 139
  • 140. Digital Communications: introduction ● Channel encoder. Algebraic structure Implementation: finite-state machine 140
  • 141. Digital Communications: introduction ● It is important to discern – – ● Abstract operations / layers (“divide and conquer”). HW implementation. Recall always – – Design and evaluation parameters. – ● Basic scheme of Digital Communications. Concepts from Communication Theory and Signals and Systems. Main purpose: – Given some resources, and some target conditions and performance, manage to evaluate and design the appropriate subsystems. 141