path: root/Wireless_Communications_and_Networking_by_V._Garg/ch4.ipynb

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  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Chapter 4: An Overview of Digital Communication and Transmission"
     ]
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 4.1, Page 93"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#Variable declaration\n",
      "Fm=20;  # in KHz\n",
      "\n",
      "#Calculations\n",
      "print \"An Engineering version of the Nyquist sampling rate : fs>=2.2*fm.\"\n",
      "print 'Therefore sampling rate of >= %d ksps should be used '%(2.2*Fm); \n",
      "print \"The sampling rate for a compact disc digital audio player = 44.1 ksps and for a studio quality audio player = 48 ksps are used.\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "An Engineering version of the Nyquist sampling rate : fs>=2.2*fm.\n",
        "Therefore sampling rate of >= 44 ksps should be used \n",
        "The sampling rate for a compact disc digital audio player = 44.1 ksps and for a studio quality audio player = 48 ksps are used.\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 4.2, Page 96"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "Rt=1; #Resistance(ohm)\n",
      "#L= Number of quantization values\n",
      "L1=32;\n",
      "L2=64;\n",
      "L3=128;\n",
      "L4=256;\n",
      "\n",
      "#Calculations\n",
      "# L=2**R i.e R=math.log2(L);\n",
      "R1=math.log(L1,2);\n",
      "R2=math.log(L2,2);\n",
      "R3=math.log(L3,2);\n",
      "R4=math.log(L4,2);\n",
      "\n",
      "#P=A**2/2; #average power of signal\n",
      "#sig**2=0.333*A**2*2**(-2*Rt); #Avg quantization noise power\n",
      "#SNR=P/sig**2;\n",
      "# SNR(dB)=1.8+ 6R;\n",
      "\n",
      "SNR1=1.8+6*R1;\n",
      "SNR2=1.8+6*R2;\n",
      "SNR3=1.8+6*R3;\n",
      "SNR4=1.8+6*R4;\n",
      "\n",
      "#Result\n",
      "print 'For L=32, SNR is %.1f dB\\n '%SNR1\n",
      "print 'For L=64, SNR is %.1f dB\\n '%SNR2\n",
      "print 'For L=128, SNR is %.1f dB\\n '%SNR3\n",
      "print 'For L=256, SNR is %.1f dB\\n '%SNR4"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "For L=32, SNR is 31.8 dB\n",
        " \n",
        "For L=64, SNR is 37.8 dB\n",
        " \n",
        "For L=128, SNR is 43.8 dB\n",
        " \n",
        "For L=256, SNR is 49.8 dB\n",
        " \n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 4.3, Page 99"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#Variable declaration\n",
      "Fs=8*10**3;  #in Hz\n",
      "Fm=3.4*10**3; # in Hz\n",
      "VCH=24; #voice channels\n",
      "SCH=1; #sunchronization channel\n",
      "PDur=1;  #extra pulse duration in microsec\n",
      "\n",
      "#Calculations&Results\n",
      "Ts=1/(Fs);\n",
      "TimeCH=Ts/(VCH+SCH)*10**6;   # in microsec\n",
      "print 'Time between the pulses is %d microsec\\n'%(TimeCH-PDur);\n",
      "#Now by using the engineering version of Nyquist rate sampling\n",
      "NyquistRate=2.2*Fm;\n",
      "Ts1_microsec=1/NyquistRate*10**6;\n",
      "Tc=round(Ts1_microsec)/(VCH+SCH);\n",
      "print \"Time between the pulses by using engineering version of Nyquist rate sampling  is %.2f microsec\\n\"%(Tc-PDur);"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Time between the pulses is -1 microsec\n",
        "\n",
        "Time between the pulses by using engineering version of Nyquist rate sampling  is 4.36 microsec\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 4.4, Page 101"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "Fm=3000; #highest modulating frequency in signal(Hz)\n",
      "M=32; # number of pulse levels \n",
      "b=5; #bits per symbol \n",
      "p=0.01; #Quantization distortion\n",
      "\n",
      "#Calculations\n",
      "#2**R = L >= 1/2P\n",
      "# where R is the number of bits required to represent quantization levels L\n",
      "R=math.log10(1./(2*p))/math.log10(2);\n",
      "Fs=2*Fm;  # Nyquist sampling criteria (samples per second)\n",
      "fs=round(R)*Fs;\n",
      "Rs=fs/b;\n",
      "\n",
      "#Result\n",
      "print 'The minimum number of bits/sample or bits/PCM word that should be used are %d'%(round(R));\n",
      "print 'The minimum sampling rate is %d samples per second\\n '%Fs;\n",
      "print 'The resulting transmission rate is %d bps\\n '%fs;\n",
      "print 'The PCM pulse or symbol transmission rate is %d symbols/sec\\n'%Rs"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "The minimum number of bits/sample or bits/PCM word that should be used are 6\n",
        "The minimum sampling rate is 6000 samples per second\n",
        " \n",
        "The resulting transmission rate is 36000 bps\n",
        " \n",
        "The PCM pulse or symbol transmission rate is 7200 symbols/sec\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 4.5, Page 110"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "S_No=53.; #dB-Hz\n",
      "R=9.6*10**3; #bps\n",
      "BW=4.8*10**3; #Khz\n",
      "Pb=10**-5; #BER<=10**-5;\n",
      "\n",
      "#Calculations\n",
      "print \"Since the required data rate of 9.6 kbps is more than the available bandwidth of 4.8 kHz, the channel is bandwidth-limited.\"\n",
      "Eb_No=S_No-10*math.log10(R); #dB\n",
      "# Try for 8-PSK modulation scheme\n",
      "M=8;\n",
      "Ps=math.log(M,2)*Pb; #Max ps\n",
      "Es_No=math.log(M,2)*10**(0.1*Eb_No);\n",
      "#Ps(8)=2*Q(math.sqrt(2*Es_No)*sin(math.pi/8));\n",
      "#2*Q(math.sqrt(2*Eb_No))=erfc(math.sqrt(Eb_No));  #Refer EQn C(7) from appendix C\n",
      "\n",
      "Ps8=math.erfc(math.sqrt(Es_No)*math.sin(math.pi/8));\n",
      "\n",
      "#Result\n",
      "print 'Symbol error rate is given as %.5f \\n '%Ps\n",
      "print 'The ratio of signal energy to noise is %.2f \\n '%Es_No;\n",
      "print 'Symbol error rate for 8-PSK  is %.5f \\n '%Ps8;\n",
      "print \"As symbol error rate for 8-PSK modulation is lower than threshold value. so, We can use 8-PSK modulation.\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Since the required data rate of 9.6 kbps is more than the available bandwidth of 4.8 kHz, the channel is bandwidth-limited.\n",
        "Symbol error rate is given as 0.00003 \n",
        " \n",
        "The ratio of signal energy to noise is 62.35 \n",
        " \n",
        "Symbol error rate for 8-PSK  is 0.00002 \n",
        " \n",
        "As symbol error rate for 8-PSK modulation is lower than threshold value. so, We can use 8-PSK modulation.\n"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 4.6, Page 111"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "SNR=48.; #dB-Hz\n",
      "BW=45.*10**3; #in Hz\n",
      "R=9.6*10**3; #bps\n",
      "Pb=10**-5; #Bit error rate\n",
      "e=2.71828; #Natural exponent e\n",
      "\n",
      "#Calculations&Results\n",
      "print \"since the available bandwidth of 45 kHz is more than adequate to support the required data rate of 9.6 kbps.\";\n",
      "print \"So, the channel is not bandwidth limited \";\n",
      "Eb_No=SNR-10*math.log10(R);\n",
      "#We try the 16-FSK modulation scheme\n",
      "M=16;\n",
      "\n",
      "Es_No=math.log(M,2)*Eb_No;\n",
      "Ps=(M-1)/2*e**(-Es_No/2);\n",
      "#For orthogonal signalling\n",
      "Ps16=(2**M-1)/(2**(M-1))*Pb;\n",
      "print \"\"\n",
      "print 'The maximum symbol error probability is %0.5f \\n '%Ps16\n",
      "print 'The symbol error probability achieved by 16-PSK is %.9f \\n '%Ps;\n",
      "print \"As achieved symbol error probability is far less than maximum tolerable value\";\n",
      "print \"So, we can meet the given speci\ufb01cations for this power-limited channel with a 16-FSK modulation scheme without any error-correction coding\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "since the available bandwidth of 45 kHz is more than adequate to support the required data rate of 9.6 kbps.\n",
        "So, the channel is not bandwidth limited \n",
        "\n",
        "The maximum symbol error probability is 0.00001 \n",
        " \n",
        "The symbol error probability achieved by 16-PSK is 0.000000553 \n",
        " \n",
        "As achieved symbol error probability is far less than maximum tolerable value\n",
        "So, we can meet the given speci\ufb01cations for this power-limited channel with a 16-FSK modulation scheme without any error-correction coding\n"
       ]
      }
     ],
     "prompt_number": 15
    }
   ],
   "metadata": {}
  }
 ]
}