BPSK QPSK 16QAM 64QAM modulation python code script

This page covers BPSK, QPSK, 16QAM and 64QAM modulation python code script.

Introduction: Digital modulation techniques such as QPSK, 16QAM and 64QAM helps in achieving bandwidth efficiency by mapping multiple bits on single carrier. BPSK is the most robust modulation technique used for long distance communication and pilot subcarrier mapping.

Data mapping or modulation Python script

Following python code can be used to map digital binary data as per different modulation constellation points such as BPSK, QPSK, 16QAM and 64QAM.

# Binary data generator (1's and 0's as per user defined length)
import random
import numpy as np
import numpy
import matplotlib.pyplot as plt
# Python code to generate binary stream of data
input_data = ""
len1 = 1000 # length of input data
for i in range(len1):
  temp1 = str(random.randint(0, 1))
  input_data += temp1
print(input_data)
input_data1 = [int(i) for i in input_data] # convert string to list
print(input_data1)
# Setting up parameters such as modulation type, number of bits per carrier (nc) and norm_factor
modulation_type = int(input("Enter modulation type (0: BPSK, 1: QPSK, 2:16QAM, 3: 64QAM: "))
print(modulation_type)
norm_factor = [1.0, 0.7071, 0.3162, 0.1543]
nc = [1, 2, 4, 6]
k = norm_factor[modulation_type]
print(k)
mode = nc[modulation_type]
print(mode)
M0 = []
match mode:
case 1:
    M0 = np.array([1, -1])
    i = len(M0)
    b = np.zeros(i)
    for i in M0:
      M0 = numpy.multiply(M0, k)
    plt.plot(M0.real, M0.imag, "g*")
    plt.title("Figure-1 : BPSK constellation")
    plt.show()
case 2:
    M0 = np.array([1. + 1.j, -1. + 1.j, 1. - 1.j, -1. - 1.j])
    i = len(M0)
    b = np.zeros(i)
    for i in M0:
      N0 = numpy.multiply(M0, k)
    plt.plot(M0.real, M0.imag, "g*")
    plt.title("Figure-2 : QPSK constellation")
    plt.show()
case 4:
    M0 = np.array([1. + 1.j, 1. + 3.j, 1. - 1.j, 1. - 3.j, 3. + 1.j, 3. + 3.j,
    3. - 1.j, 3. - 3.j, -1. + 1.j, -1. + 3.j, -1. - 1.j, -1. - 3.j, -3. + 1.j,
    -3. + 3.j, -3. - 1.j, -3. - 3.j])
    i = len(M0)
    b = np.zeros(i)
    for i in M0:
      M0 = numpy.multiply(M0, k)
    plt.plot(M0.real, M0.imag, "g*")
    plt.title("Figure-3 : 16QAM constellation")
    plt.show()
case 6:
    M0 = np.array([3 + 3j, 3 + 1j, 3 + 5j, 3 + 7j, 3 - 3j, 3 - 1j, 3 - 5j,
    3 - 7j, 1 + 3j, 1 + 1j, 1 + 5j, 1 + 7j, 1 - 3j, 1 - 1j, 1 - 5j, 1 - 7j,
    5 + 3j, 5 + 1j, 5 + 5j, 5 + 7j, 5 - 3j, 5 - 1j, 5 - 5j, 5 - 7j, 7 + 3j,
    7 + 1j, 7 + 5j, 7 + 7j, 7 - 3j, 7 - 1j, 7 - 5j, 7 - 7j, -3 + 3j, 3 + 1j,
    -3 + 5j, -3 + 7j, -3 - 3j, -3 - 1j, -3 - 5j, -3 - 7j, -1 + 3j, -1 + 1j,
    -1 + 5j, -1 + 7j, -1 - 3j, -1 - 1j, -1 - 5j, -1 - 7j, -5 + 3j, -5 + 1j,
    -5 + 5j, -5 + 7j, -5 - 3j, -5 - 1j, -5 - 5j, -5 - 7j, -7 + 3j, -7 + 1j,
    -7 + 5j, -7 + 7j, -7 - 3j, -7 - 1j, -7 - 5j, -7 - 7j])
    i = len(M0)
    b = np.zeros(i)
    for i in M0:
      M0 = numpy.multiply(M0, k)
    plt.plot(M0.real, M0.imag, "g*")
    plt.title("Figure-4 : 64QAM constellation")
    plt.show()
# checking length of data to add padding zero at the end if required
remainder = len1 % mode
print(remainder)
if remainder != 0:
  remainder = mode-remainder
input_data1 = np.pad(input_data1, (0, remainder))
len1 = len(input_data1)
len2 = int(len1/mode)
input_data_r = np.reshape(input_data1, (len2, mode))
print(input_data_r)

s1 = input_data
s2 = []
chunks = [s1[i:i+mode] for i in range(0, len(s1), mode)]
for piece in chunks:
  temp = int(piece, 2)
  print(temp, piece)
  s2.append(temp)

map_out = []
for value in s2:
  map_out.append(M0[value])
  print(M0[value])