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2. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels2 of 66 Arturo Rinaldi - The gr-bertool 3. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels The simulated channels were :2 of 66 Arturo Rinaldi - The gr-bertool 4. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels The simulated channels were : Wired : AWGN2 of 66 Arturo Rinaldi - The gr-bertool 5. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels The simulated channels were : Wired : AWGN Wireless : Rayleigh and Rician2 of 66 Arturo Rinaldi - The gr-bertool 6. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels The simulated channels were : Wired : AWGN Wireless : Rayleigh and Rician Verify the correspondence between the theoretical and experimentalresults of the BER (Bit Error Rate)2 of 66 Arturo Rinaldi - The gr-bertool 7. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels The simulated channels were : Wired : AWGN Wireless : Rayleigh and Rician Verify the correspondence between the theoretical and experimentalresults of the BER (Bit Error Rate) Provide complementary tools to show how audio and video les aremodied under the eect of the transmission channels2 of 66 Arturo Rinaldi - The gr-bertool 8. Goal of the thesis work The making of a learning tool for the analysis of the digital modulationsin dierent communication channels The simulated channels were : Wired : AWGN Wireless : Rayleigh and Rician Verify the correspondence between the theoretical and experimentalresults of the BER (Bit Error Rate) Provide complementary tools to show how audio and video les aremodied under the eect of the transmission channels The gr-bertool was built by using the open-source DSP platform GNURadio2 of 66 Arturo Rinaldi - The gr-bertool 9. GNU Radio GNU Radio is an open-source softwaretoolkit providing a huge library of blocks for Digital Signal Processing (DSP) written in C++ which can be combined together in order to build and develop radio applicationsGnu Radio Companion (GRC), XML Python Flow Graph (Created using the processing blocks) SWIG (Port C++ blocks to Python) GNU Radio Signal Processing Blocks (C++)USB Interface / Gigabit Ethernet Generic RF Front End ( USRP / USRP 2 )3 of 66 Arturo Rinaldi - The gr-bertool 10. GNU Radio GNU Radio is an open-source softwaretoolkit providing a huge library of blocks for Digital Signal Processing (DSP) written in C++ which can be combined together in order to build and develop radio applications It is provided with a graphical interfaceto ease its learning curve (GRC : GNU Radio Companion)Gnu Radio Companion (GRC), XML Python Flow Graph (Created using the processing blocks) SWIG (Port C++ blocks to Python) GNU Radio Signal Processing Blocks (C++)USB Interface / Gigabit Ethernet Generic RF Front End ( USRP / USRP 2 )3 of 66 Arturo Rinaldi - The gr-bertool 11. Software-Dened Radio : an introduction GNU Radio was developed to be in use of Software-Dened Radio(SDR), a new paradigm of communication systems4 of 66 Arturo Rinaldi - The gr-bertool 12. Software-Dened Radio : an introduction GNU Radio was developed to be in use of Software-Dened Radio(SDR), a new paradigm of communication systems A receiver is an SDR device if its communication functions are made asrecongurable software working on ad hoc hardware4 of 66 Arturo Rinaldi - The gr-bertool 13. Software-Dened Radio : an introduction GNU Radio was developed to be in use of Software-Dened Radio(SDR), a new paradigm of communication systems A receiver is an SDR device if its communication functions are made asrecongurable software working on ad hoc hardware So its possible to implement dierent software transmission standardsby using only one device4 of 66 Arturo Rinaldi - The gr-bertool 14. Software-Dened Radio : an introduction GNU Radio was developed to be in use of Software-Dened Radio(SDR), a new paradigm of communication systems A receiver is an SDR device if its communication functions are made asrecongurable software working on ad hoc hardware So its possible to implement dierent software transmission standardsby using only one device An SDR sytem is also able to recognize and avoid possible interferenceswith other transmission channels4 of 66 Arturo Rinaldi - The gr-bertool 15. A general overview on the main GNU Radio blocks5 of 66 Arturo Rinaldi - The gr-bertool 16. Signal Source The block generates dierent kind of waveforms to be used as the main signal to transmit or as a reference one. The block is only not able to generate Sinusoidal or Costant kind of waveforms but also Square, Triangle and Saw Tooth ones. Type : complex, oat, int, short6 of 66 Arturo Rinaldi - The gr-bertool 17. Noise Source The block is able to generate noise according to the Uniform, Gaussian, Laplacian and Impulse models. Please also note that the Amplitude parameter fed to the Gaussian kind of noise is the standard deviation of the Gaussian Noise, given by : =N0 2where N0 /2 is the power spectral density of white noise (i.e. its variance). Type : complex, oat, int, short Arturo Rinaldi - The gr-bertool7 of 66 18. OperatorsThese blocks perform the four basic arithmetical functions over the signal sources they are fed with (sum, subtraction, multiplication and division). Please also note that they perform the operation element by element (i.e. rst element of the row rst element of the column) so the rule of thumb is to feed the inputs with equal amounts of data. Type : complex, oat, int, short8 of 66 Arturo Rinaldi - The gr-bertool 19. Random Source 2 The block generates a random array of unsigned integer data with values spanning from 0 to 255 (we are working with 1-byte elements !). We use it because is a more reliable source of random data compared to the one provided with the GNU Radio platform. The only parameter fed to the block is the number of samples (i.e. the length of the generated list of elements). Type : complex, oat, byte 9 of 66 Arturo Rinaldi - The gr-bertool 20. Random Source 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24from g n u r a d i o i m p o r t g r i m p o r t random d e f OnDataSource random ( s a m p l e s ) : src1 = [ ] f o r i in range ( samples ) : d a t a = random . r a n d i n t ( 0 , 2 5 5 ) s r c 1 . append ( d a t a ) return src1 c l a s s randomsource b ( gr . h i e r b l o c k 2 ) : definit( s e l f , number samples ) : gr . h i e r b l o c k 2 . init ( s e l f , randomsource b , gr . i o s i g n a t u r e (0 , 0 , 0) , gr . i o s i g n a t u r e (1 , 1 , gr . s i z e o f c h a r ) ) d a t a s a m p l e s = OnDataSource random ( n u m b e r s a m p l e s ) s e l f . v e c t o r = g r . v e c t o r s o u r c e b ( d a t a s a m p l e s , True , 1 ) s e l f . connect ( s e l f . vector , s e l f )10 of 66 Arturo Rinaldi - The gr-bertool 21. Random Source - The easy way The block generates a random array of unsigned integer data. It is a more direct implementation compared to the one we have just seen. We feed it with the data list (of unsigned integer of course) and we also set to Yes the repeat option since we need a constant stream of data. Lets see how to build the data array this time....11 of 66 Arturo Rinaldi - The gr-bertool 22. Random Source - The easy way 1 2 3 4 5 6 7from g n u r a d i o i m p o r t g r i m p o r t numpy d a t a = map ( i n t , numpy . random . r a n d i n t ( 0 , 2 5 6 , 6 e5 ) ) v e c t o r = g r . v e c t o r s o u r c e b ( d at a , True , 1 )12 of 66 Arturo Rinaldi - The gr-bertool 23. Packed to Unpacked The block returns sequences of packed bytes according to the integer number we set to the Bits per Chunk argument. It is possible to set the Endianness of the output sequences according to Big (MSB) or Little (LSB)a . So lets assume we have this binary sequence 11100001. If we feed it to the block well get four binary sequences, specically : 00000011 00000010 00000000 00000001Type : int, short, byte a Johathan Swift, Gullivers Travels 13 of 66 Arturo Rinaldi - The gr-bertool 24. Map We usually exploit this block every time we want to perform Gray Coding on the symbols of a digital modulation. For a 2-bit symbols modulation : Binary to Gray sequence : [0,1,3,2] Gray to Binary sequence : [0,1,3,2]For a 3-bit symbols modulation : Binary to Gray sequence : [0,1,3,2,7,6,4,5] Gray to Binary sequence : [0,1,3,2,6,7,5,4]Type : byte14 of 66 Arturo Rinaldi - The gr-bertool 25. Constellation Decoder - 1 It could be seem strange feeding the same coding numeric sequence when un-gray a constellation. However, this is due to how GNU Radio works and in particular how the Constellation Decoder block operates over the signal points. So, once you have assigned the correct Symbol Value Out (i.e. for a QPSK constellation is [0,1,2,3]), you have to scramble the Symbol Position values again to perform a correct decoding. You can take care of this by using a cascading link to the Map block again and feeding it with the originary coding sequence. 15 of 66 Arturo Rinaldi - The gr-bertool 26. Constellation Decoder - 2 Please also note that all our work is based on the old version of the gr constellation decoder block. In fact, the version we have just dealt with is the one taken from the GNU Radio 3.4.2 tarball and built again as a custom block with the cmake custom wrapper you can usually nd inside a tarball1 . This however is nowadays considered an old-school method since the latest tarballs provide the Swiss-army knife tool called gr-modtool, which will generate the skeleton of your new custom package.1 This is true for tarball version ranging from 3.5.0 to 3.6.5.116 of 66 Arturo Rinaldi - The gr-bertool 27. Chunks to Symbols Once we have set the coding on our binary sequences (the ones from the Packed to Unpacked block) we can assign the points of the constellation to them. So for example, if we want to build a BPSK constellation we will assign the points [-1,1] to the Symbols Table. Otherwise if we want to build a QPSK constellation we will assign these other points : [1+1j,-1+1j,-1-1j,1-1j] Input type : int, short, byte Output type : complex, oat 17 of 66 Arturo Rinaldi - The gr-bertool 28. Throttle We usually use this block to limit the cpu load when operating with non-audio or non-usrp sources/sinks. This means that our system wont freeze or be overloaded by the GNU Radio engine. If by any chance we forget it to put it in our ow graph, we will be warned about it runtime. Type : complex, oat, int, short, byte18 of 66 Arturo Rinaldi - The gr-bertool 29. WX GUI Slider Its a simple slider making part of the GNU Radio GUIs. We can use to vary at runtime the value of certain variable we have previously set. We will mostly use this slider to set the Eb /N0 value in our simulations. We are also able to set the Default Value (it is usually a oat one), and the number of steps between the Maximum and Minimum value of the variable itself.19 of 66 Arturo Rinaldi - The gr-bertool 30. WX GUI Scope Sink The WX GUI Scope Sink is a simple graphical sink to show our generated waveforms or digital constellations as well. At runtime, you will notice that is provided with buttons to set the X and Y axis divisions and their oset as well. Be sure to set XY Mode to On when working with digital constellations or any complex stream of data to show both the orthogonal components in the correct way. Type : complex, oat 20 of 66 Arturo Rinaldi - The gr-bertool 31. Unpacked to Packed Basically, this block exactly works in the reverse way of the Packed to Unpacked block we saw a couple of slides ago. Remembering the four binary sequences, which were splitted from the original one : 00000011 00000010 00000000 00000001they will be reverted to the original transmitted binary sequence 11100001. Type : int, short, byte 21 of 66 Arturo Rinaldi - The gr-bertool 32. Import The Import block allows us to import the installed python libraries or even some custom code residing in your PYTHONPATH(s). Some common examples of imports into the block are : Import: numpy Import:scipy Import:and so on.22 of 66 Arturo Rinaldi - The gr-bertool 33. WX GUI Number Sink The WX GUI Number Sink is a simple graphical sink to display the result of a numeric calculation of a GNU Radio ow graph. We also might feed it,for example, with a constant source (depending on a variable) to have a numeric reference to compare with a real-time result. You can also set the number of the decimal digits so to get more accuracy in the displayed result. Type : complex, oat23 of 66 Arturo Rinaldi - The gr-bertool 34. BER and SER calculation These ones are the blocks for the BER and SER calculation of the digital modulation. We usually feed their inputs with the reference and the decoded stream of data. Please note that we have only to specify the number of Bits per Symbol only in the BER block. It is also recommended to set number of samples of Window Size to 600k or 1M (and of the input data streams as well) to get an accurate measure of the error rates. Input type : byte Output Type : oat 24 of 66 Arturo Rinaldi - The gr-bertool 35. Now lets build a QPSK constellation together ! ! !25 of 66 Arturo Rinaldi - The gr-bertool 36. Click on the GRC icon in your menu baror just type from your local shell :$ gnuradio-companion &26 of 66 Arturo Rinaldi - The gr-bertool 37. map(int, numpy.random.randint(0, 256, 6e5)) 1+1j, -1+1j, -1-1j, 1-1j Arturo Rinaldi - The gr-bertool27 of 66 38. The developed tool : gr-bertool28 of 66 Arturo Rinaldi - The gr-bertool 39. The developed tool : gr-bertool The tool main GUI29 of 66 Arturo Rinaldi - The gr-bertool 40. The developed tool : gr-bertool BER experimental verication30 of 66 Arturo Rinaldi - The gr-bertool 41. The developed tool : gr-bertool Real-Time BER experimental verication31 of 66 Arturo Rinaldi - The gr-bertool 42. The developed tool : gr-bertool Complementary tools32 of 66 Arturo Rinaldi - The gr-bertool 43. The BER Calculation33 of 66 Arturo Rinaldi - The gr-bertool 44. BER experimental verication The Bit Error Rate (BER) of a digital modulation, is the number of biterrors divided by the total number of transferred bits during a studied time interval34 of 66 Arturo Rinaldi - The gr-bertool 45. BER experimental verication The Bit Error Rate (BER) of a digital modulation, is the number of biterrors divided by the total number of transferred bits during a studied time interval Lets verify the BER theoretical values with the experimental ones byvarying the signal-to-noise ratio Eb /N034 of 66 Arturo Rinaldi - The gr-bertool 46. BER experimental verication The Bit Error Rate (BER) of a digital modulation, is the number of biterrors divided by the total number of transferred bits during a studied time interval Lets verify the BER theoretical values with the experimental ones byvarying the signal-to-noise ratio Eb /N0 From digital communications theory is well known that for a Q-PSKmodulation the Bit Error Rate is given by : Pb = Q2Eb N034 of 66 Arturo Rinaldi - The gr-bertool 47. BER experimental verication This set of tools calculates the BER ina range of Eb /N0 values given by min and max with the opportunity to choose the increase step size35 of 66 Arturo Rinaldi - The gr-bertool 48. BER experimental verication This set of tools calculates the BER ina range of Eb /N0 values given by min and max with the opportunity to choose the increase step size We can enable or disable the GrayCoding35 of 66 Arturo Rinaldi - The gr-bertool 49. BER experimental verication This set of tools calculates the BER ina range of Eb /N0 values given by min and max with the opportunity to choose the increase step size We can enable or disable the GrayCoding By clicking on the Plot button the BERcurves are showed in a simple BER vs Eb /N0 diagram35 of 66 Arturo Rinaldi - The gr-bertool 50. BER experimental verication We can see a perfect agreement between the theoretical results and the experimental ones :(a) BER AWGN BPSK(b) BER AWGN Q-PSK(c) BER AWGN 8-PSK36 of 66 Arturo Rinaldi - The gr-bertool 51. BER experimental vericationLets try it together ! ! !37 of 66 Arturo Rinaldi - The gr-bertool 52. The Real-Time BER Calculation38 of 66 Arturo Rinaldi - The gr-bertool 53. Real-Time BER and signal constellation evolution This tool allow us to show the real-timeBER and signal constellation evolution in the three dierent types of examinated transmission channels39 of 66 Arturo Rinaldi - The gr-bertool 54. Real-Time BER and signal constellation evolution This tool allow us to show the real-timeBER and signal constellation evolution in the three dierent types of examinated transmission channels In the following example well show theBER evolution in the Rician Channel in the range of Eb /N0 values going from 15 dB to 0 dB39 of 66 Arturo Rinaldi - The gr-bertool 55. Real-Time BER and signal constellation evolution This tool allow us to show the real-timeBER and signal constellation evolution in the three dierent types of examinated transmission channels In the following example well show theBER evolution in the Rician Channel in the range of Eb /N0 values going from 15 dB to 0 dB Once started the BER value settles tothe BER value corresponding to Eb /N0 = 0 dB about equal to 0.1139 of 66 Arturo Rinaldi - The gr-bertool 56. Real-Time BER and signal constellation evolution This tool allow us to show the real-timeBER and signal constellation evolution in the three dierent types of examinated transmission channels In the following example well show theBER evolution in the Rician Channel in the range of Eb /N0 values going from 15 dB to 0 dB Once started the BER value settles tothe BER value corresponding to Eb /N0 = 0 dB about equal to 0.11 Ch1 Experimental Value ; Ch2Theoretical Value 39 of 66 Arturo Rinaldi - The gr-bertool 57. Real-Time BER and signal constellation evolution This tool allow us to show the real-timeBER and signal constellation evolution in the three dierent types of examinated transmission channels In the following example well show theBER evolution in the Rician Channel in the range of Eb /N0 values going from 15 dB to 0 dB Once started the BER value settles tothe BER value corresponding to Eb /N0 = 0 dB about equal to 0.11 Ch1 Experimental Value ; Ch2Theoretical Value Lets see the evolution.... Arturo Rinaldi - The gr-bertool39 of 66 58. Real-Time BER evolution40 of 66 Arturo Rinaldi - The gr-bertool 59. Real-Time BER evolution41 of 66 Arturo Rinaldi - The gr-bertool 60. Real-Time BER evolution42 of 66 Arturo Rinaldi - The gr-bertool 61. Real-Time BER evolution43 of 66 Arturo Rinaldi - The gr-bertool 62. Real-Time BER evolution44 of 66 Arturo Rinaldi - The gr-bertool 63. Real-Time BER evolution45 of 66 Arturo Rinaldi - The gr-bertool 64. The signal constellation Lets consider a generic transmission scheme for a TLC system. m(t) Ss(t) Txr(t) Tx Channeld(t) RxDFigure : Generic block diagram for a TLC system46 of 66 Arturo Rinaldi - The gr-bertool 65. The signal constellation Lets consider a generic transmission scheme for a TLC system. m(t) Ss(t)r(t)Txd(t) RxTx ChannelDFigure : Generic block diagram for a TLC system In the absence fo any noise in the channel the generci transmittedsymbol si will be correctly received. The plot of the received symbols is knows as Constellation of the digital modulation. s3 (01) s0 (11) s2 (00) s1 (10) Figure : Constellation of a QPSK modulation 46 of 66 Arturo Rinaldi - The gr-bertool 66. The signal constellation The presence of noise in the channel modies phase and amplitude ofthe transmitted symbols and so the received symbol ri is not one belonging to the constellation showed before s3 (01) s0 (11) The transmitted si symbol is not correctly receivedri s2 (00) s1 (10) 47 of 66 Arturo Rinaldi - The gr-bertool 67. Evolution of the Signal Constellation48 of 66 Arturo Rinaldi - The gr-bertool 68. Evolution of the Signal Constellation49 of 66 Arturo Rinaldi - The gr-bertool 69. Evolution of the Signal Constellation50 of 66 Arturo Rinaldi - The gr-bertool 70. Evolution of the Signal Constellation51 of 66 Arturo Rinaldi - The gr-bertool 71. Evolution of the Signal Constellation52 of 66 Arturo Rinaldi - The gr-bertool 72. Real-Time BER EvolutionLets try it together ! ! !53 of 66 Arturo Rinaldi - The gr-bertool 73. Image Transmission54 of 66 Arturo Rinaldi - The gr-bertool 74. Image Transmission This tool allow us to observe how themost common image formats are aected by digital modulations55 of 66 Arturo Rinaldi - The gr-bertool 75. Image Transmission This tool allow us to observe how themost common image formats are aected by digital modulations We studied the eects over thesimulated channels (AWGN, Rayleigh e Rician) for a xed value of Eb /N0 = 0 dB and Q-PSK digital modulation for a Jpeg image55 of 66 Arturo Rinaldi - The gr-bertool 76. Image Transmission This tool allow us to observe how themost common image formats are aected by digital modulations We studied the eects over thesimulated channels (AWGN, Rayleigh e Rician) for a xed value of Eb /N0 = 0 dB and Q-PSK digital modulation for a Jpeg image Lets see the results......55 of 66 Arturo Rinaldi - The gr-bertool 77. Image Transmission : AWGN Channel(a) Original(b) AWGN 56 of 66Arturo Rinaldi - The gr-bertool 78. Image Transmission : Rician Channel(c) Original(d) Rician 57 of 66Arturo Rinaldi - The gr-bertool 79. Image Transmission : Rayleigh Channel(e) Original(f) Rayleigh 58 of 66Arturo Rinaldi - The gr-bertool 80. Image TransmissionLets try it together ! ! !59 of 66 Arturo Rinaldi - The gr-bertool 81. Audio Transmission This tool allow us to observe how themost common audio formats are aected by digital modulations60 of 66 Arturo Rinaldi - The gr-bertool 82. Audio Transmission This tool allow us to observe how themost common audio formats are aected by digital modulations We studied the eects over thesimulated channels (AWGN, Rayleigh e Rician) for a xed value of Eb /N0 = 10 dB and Q-PSK digital modulation60 of 66 Arturo Rinaldi - The gr-bertool 83. Audio Transmission This tool allow us to observe how themost common audio formats are aected by digital modulations We studied the eects over thesimulated channels (AWGN, Rayleigh e Rician) for a xed value of Eb /N0 = 10 dB and Q-PSK digital modulation We took as sample the wav leplay it sam.wav with the following specications :60 of 66 Arturo Rinaldi - The gr-bertool 84. Audio Transmission Specications of the sample le play_it_sam.wav : File Size: 1.76M Bit Rate: 1.41M Encoding: Signed PCM Channels: 2 @ 16-bit Samplerate: 44100Hz Replaygain: off Duration: 00:00:10.00 Lets see the results.... 61 of 66 Arturo Rinaldi - The gr-bertool 85. Audio Transmission(g) Original(h) AWGN Channel62 of 66 Arturo Rinaldi - The gr-bertool 86. Audio Transmission(i) Rician(j) Rayleigh63 of 66 Arturo Rinaldi - The gr-bertool 87. Conclusions64 of 66 Arturo Rinaldi - The gr-bertool 88. Conclusions Why using gr-bertool ? AdvantagesIts an helpful tool for the teacher to use in TLC courses65 of 66 Arturo Rinaldi - The gr-bertool 89. Conclusions Why using gr-bertool ? AdvantagesIts an helpful tool for the teacher to use in TLC coursesThe student can nd a quick verication with the learnt notions during classes65 of 66 Arturo Rinaldi - The gr-bertool 90. Conclusions Why using gr-bertool ? AdvantagesIts an helpful tool for the teacher to use in TLC coursesThe student can nd a quick verication with the learnt notions during classesIt has an user-friendly GUI65 of 66 Arturo Rinaldi - The gr-bertool 91. Conclusions Why using gr-bertool ? AdvantagesIts an helpful tool for the teacher to use in TLC coursesThe student can nd a quick verication with the learnt notions during classesIt has an user-friendly GUIIts open-source !65 of 66 Arturo Rinaldi - The gr-bertool 92. Contact Information Arturo Rinaldi Freelance Collaborator @ DIECII Address : Dep. of Electronics Engineering (DIECII) C.da di Dio, 98166 Messina (Italy) E-mail : [email protected] Fixed : +39-090-3977376 ; Mobile : +39-340-5795584 (Whatsapp) Skype : arty.net ; Facebook : arty.net Twitter : artynet2 ; LinkedIn : Arturo Rinaldi Prof. Giuseppe Campobello, Ph.D. Researcher in Telecommmunications Address : Dep. of Electronics Engineering (DIECII) C.da di Dio, 98166 Messina (Italy) - Room: 636 (block B, 6th oor) E-mail : [email protected] Fixed : +39-090-3977378 Prof. Salvatore Serrano, Ph.D. Researcher in Telecommmunications Address : Dep. of Electronics Engineering (DIECII) C.da di Dio, 98166 Messina (Italy) E-mail : [email protected] Fixed : +39-090-3977522 66 of 66 Arturo Rinaldi - The gr-bertool
