path: root/Wireless_Communications_and_Networking_by_V._Garg/ch9.ipynb

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  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Chapter 9: Modulation Schemes"
     ]
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.1, Page 259"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "import scipy\n",
      "from scipy.optimize import fsolve\n",
      "\n",
      "#Variable declaration\n",
      "Pe=10**-6;#Probability of error\n",
      "e=2.71828; #Euler's Number\n",
      "\n",
      "#Calculations\n",
      "# For BPSK\n",
      "#Pe(=10**-6)=e**(-x)/(2*sqrt(%pi*x)); where x=Eb/No\n",
      "def f(x):\n",
      "    y=2.71828**(-x)/(2*math.sqrt(math.pi*x))-10**-6\n",
      "    return y\n",
      "x = fsolve(f,0.1);\n",
      "\n",
      "#Results\n",
      "print 'Eb/No For BPSK is %.2f dB'%(10*math.log10(x));\n",
      "print 'FSK requires 3 dB more in terms of Eb/N0 to give the same Pe as BPSK so it comes out to be %.2f dB'%(10*math.log10(x)+3);"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Eb/No For BPSK is 10.54 dB\n",
        "FSK requires 3 dB more in terms of Eb/N0 to give the same Pe as BPSK so it comes out to be 13.54 dB\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.2, Page 259"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "Pe=10.**-6;#Probability of error\n",
      "No=10.**-10;  # PSD in W/Hz\n",
      "R=100*10**3;  #data rate in bps\n",
      "\n",
      "#Calculations\n",
      "#From Example 9.1, Eb/N0= 10.54dB (11.32) for Pe=10**-6 \n",
      "#Therefore\n",
      "Eb_No=11.32; #From Exa. 9.1\n",
      "# Eb/No = A**2/(2*No*R);\n",
      "A=math.sqrt(2*No*(Eb_No)*R);\n",
      "\n",
      "#Result\n",
      "print 'Amplitude of a carrier signal is %.3f mV'%(A*1000);\n",
      "#Incorrect answer in textbook"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Amplitude of a carrier signal is 15.047 mV\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.3, Page 267"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#Variable declaration\n",
      "B=['00','10','01','11','01','00','11','10','10','01','01','00'];#Given Bit stream\n",
      "\n",
      "#Calculations&Results\n",
      "print \"Phase transition table for pi/4-DQPSK Modulation is given as \"\n",
      "print \" By Referring Table 9.1 on page No 266 i.e\"\n",
      "print \"Symbol    Phase transition\"\n",
      "print \"00     =>    45\u00b0\"\n",
      "print \"01     =>   135\u00b0\"\n",
      "print \"10     =>   -45\u00b0\"\n",
      "print \"11     =>  -135\u00b0\"\n",
      "print \"sym      Dell phi(k)   Phi(k)\"\n",
      "#BitStream='001001110100111010010100';\n",
      "\n",
      "phase=0; #Taking initial phase as zero\n",
      "for i in range(0,12):\n",
      "    if(B[i]=='00'):\n",
      "        phase=phase+45;  \n",
      "        print ' %s          45          %d'%(B[i],phase);\n",
      "    \n",
      "    if(B[i]=='01'):\n",
      "        phase=phase+135;\n",
      "        print ' %s         135          %d'%(B[i],phase);\n",
      "    \n",
      "    if(B[i]=='10'):\n",
      "        phase=phase-45;\n",
      "        print ' %s         -45          %d'%(B[i],phase);\n",
      "    \n",
      "    if(B[i]=='11'):\n",
      "        phase=phase-135;\n",
      "        print ' %s        -135          %d'%(B[i],phase);\n",
      "   \n",
      "\n",
      "print 'final phase for the pi/4-DQPSK modulation method for given bitstream is %d degree'%phase"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Phase transition table for pi/4-DQPSK Modulation is given as \n",
        " By Referring Table 9.1 on page No 266 i.e\n",
        "Symbol    Phase transition\n",
        "00     =>    45\u00b0\n",
        "01     =>   135\u00b0\n",
        "10     =>   -45\u00b0\n",
        "11     =>  -135\u00b0\n",
        "sym      Dell phi(k)   Phi(k)\n",
        " 00          45          45\n",
        " 10         -45          0\n",
        " 01         135          135\n",
        " 11        -135          0\n",
        " 01         135          135\n",
        " 00          45          180\n",
        " 11        -135          45\n",
        " 10         -45          0\n",
        " 10         -45          -45\n",
        " 01         135          90\n",
        " 01         135          225\n",
        " 00          45          270\n",
        "final phase for the pi/4-DQPSK modulation method for given bitstream is 270 degree\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.4, Page 270"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#Variable declaration\n",
      "CHBW=200; #Channel BW in KHz\n",
      "R=270.83; #Data rate in kbps\n",
      "Fc=900;  #carrier frequency in MHz\n",
      "\n",
      "#Calculations\n",
      "FreqShift=0.5*R;\n",
      "#Transmitted Frequencies\n",
      "Fh=Fc*1000+0.25*R;#Max\n",
      "Fl=Fc*1000-0.25*R;#Min\n",
      "BWEff=R/CHBW;\n",
      "\n",
      "#Results\n",
      "print 'The frequency shift between binary 1 and binary 0 is %.3f kHz'%FreqShift;\n",
      "print 'Maximum and Minimum value of transmitted frequencies are %.4f mHz and %.4f mHz respectively'%(Fh/1000,Fl/1000);\n",
      "print 'Bandwidth efficiency is %.2f bps/Hz'%BWEff"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "The frequency shift between binary 1 and binary 0 is 135.415 kHz\n",
        "Maximum and Minimum value of transmitted frequencies are 900.0677 mHz and 899.9323 mHz respectively\n",
        "Bandwidth efficiency is 1.35 bps/Hz\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.5, Page 271"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "R=270.; #data rate in kbps\n",
      "Eb_No=6.; # in dB\n",
      "GMSK=0.3; #Gaussian minimum shift keying\n",
      "\n",
      "#Calculations&Results\n",
      "Tb=1./R *10**3; #in microsec\n",
      "B=GMSK/Tb;\n",
      "print '3-dB BW for a gaussian low pass filter is %.f kHz'%(B*1000);\n",
      "PowerBW=1.41*R;\n",
      "DegradFac=0.89;\n",
      "Pe=math.erfc(math.sqrt(2*DegradFac*10**(0.1*Eb_No)));\n",
      "print 'Power bandwidth in the RF channel is %.1f kHz'%PowerBW\n",
      "print 'Bit error probability for GMSK is %.1e'%Pe;  #Incorrect answer in textbook"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "3-dB BW for a gaussian low pass filter is 81 kHz\n",
        "Power bandwidth in the RF channel is 380.7 kHz\n",
        "Bit error probability for GMSK is 1.7e-04\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.6, Page 273"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "\n",
      "#Variable declaration\n",
      "Rs=19200; #symbols per second\n",
      "states=64;\n",
      "\n",
      "#Calculations\n",
      "Bits_symbol=math.log(states,2);\n",
      "BitRate=Bits_symbol*Rs;\n",
      "\n",
      "#Result\n",
      "print 'Bit Rate of the modulator is %.1f kbps'%(BitRate/1000)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Bit Rate of the modulator is 115.2 kbps\n"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.7, Page 274"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "import scipy\n",
      "from scipy.optimize import fsolve\n",
      "\n",
      "#Variable declaration\n",
      "Rb=144; #data rate in kbps\n",
      "BW=36; #in MHz\n",
      "Pb=3*10**-5;#probability of bit error\n",
      "\n",
      "#Calculations\n",
      "Seff=Rb/BW;  #spectral efficiency in bps/Hz\n",
      "M=2**(Rb/BW); #since the channel is band limited\n",
      "\n",
      "#since Q[sqrt(2*Eb_No)]=(1/2)*erfc[sqrt(Eb_No)]            # refer page no 257 equ 9.35\n",
      "def f(x):\n",
      "    y=(3./8)*math.erfc(math.sqrt((2./5)*x))-Pb       #from eqn 9.66 and 9.35\n",
      "    return y\n",
      "               \n",
      "x = fsolve(f,0.1)\n",
      "\n",
      "#Result\n",
      "print 'For a rectangular constellation (refer Figure 9.12), with a Gaussian channel and matched \ufb01lter reception, the calculated Eb/No value is %.1f dB'%(10*math.log10(x));"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "For a rectangular constellation (refer Figure 9.12), with a Gaussian channel and matched \ufb01lter reception, the calculated Eb/No value is 12.9 dB\n"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.8, Page 274"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import math\n",
      "import scipy\n",
      "from scipy.optimize import fsolve\n",
      "\n",
      "#Variable declaration\n",
      "Pb=10**-8;#BER probability\n",
      "\n",
      "#Calculations&Results\n",
      "print \"For 16-PSK:\"\n",
      "# Pb=0.5*Q(0.552*sqrt(Eb_No));\n",
      "#since Q[sqrt(2*Eb_No)]=(1/2)*erfc[sqrt(Eb_No)]            # refer page no 257 equ 9.35\n",
      "def f(x):\n",
      "    y=0.25*math.erfc(math.sqrt(0.5*0.552**2*x))-Pb\n",
      "    return y\n",
      "\n",
      "x = fsolve(f,0.1)\n",
      "\n",
      "print 'Using equation 9.50 we get Eb/No as %d dB (approx)'%round(10*math.log10(x));\n",
      "\n",
      "print \"For 16-QAM\"\n",
      "#Pb=0.75*Q(sqrt(0.8*Eb_No));\n",
      "def f(x1):\n",
      "    y=(3./8)*math.erfc(math.sqrt(0.4*x1))-Pb\n",
      "    return y\n",
      "    \n",
      "x1 = fsolve(f,0.1)\n",
      "\n",
      "#since Q[sqrt(2*Eb_No)]=(1/2)*erfc[sqrt(Eb_No)] # refer page no 257 equ 9.35\n",
      "print 'Using equation 9.66 we get Eb/No as %d dB (approx)'%round(10*math.log10(x1));\n",
      "print 'Thus 16-QAM has an advantage of about %d dB compared to 16-PSK'%(10*math.log10(x)-10*math.log10(x1));"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "For 16-PSK:\n",
        "Using equation 9.50 we get Eb/No as 20 dB (approx)\n",
        "For 16-QAM\n",
        "Using equation 9.66 we get Eb/No as 16 dB (approx)\n",
        "Thus 16-QAM has an advantage of about 4 dB compared to 16-PSK\n"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Example 9.9, Page 277"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#Variable declaration\n",
      "M=8; #number of different signal elements\n",
      "Fc=250; #carrier frequency in kHz\n",
      "DelF=25; #kHz\n",
      "Pe=10**-6;#probability of error\n",
      "\n",
      "#Calculations\n",
      "TotalBW=2*M*DelF;\n",
      "nb=2*math.log(M,2)/(M+3);\n",
      "#Pe=7*Q(z) and z=approx(5.08)\n",
      "z=5.08;\n",
      "Eb_No=(z)**2/math.log(M,2);\n",
      "bits_sym=math.log(M,2);\n",
      "\n",
      "#Results\n",
      "print 'Total bandwidth required is %d kHz \\n '%TotalBW;\n",
      "print 'The bandwidth efficiency is %.4f \\n '%nb;\n",
      "print 'The required Eb/No is %.3f dB \\n '%(10*math.log10(Eb_No));\n",
      "print 'Carried bits per symbol are %d \\n '%bits_sym;"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Total bandwidth required is 400 kHz \n",
        " \n",
        "The bandwidth efficiency is 0.5455 \n",
        " \n",
        "The required Eb/No is 9.346 dB \n",
        " \n",
        "Carried bits per symbol are 3 \n",
        " \n"
       ]
      }
     ],
     "prompt_number": 10
    }
   ],
   "metadata": {}
  }
 ]
}