QPSK Constellation Mapping

Problem

Map a pair of bits to a Gray-coded QPSK constellation point: 00 -> [1, 1], 01 -> [-1, 1], 11 -> [-1, -1] and 10 -> [1, -1]. Return the two coordinates as a list.

Hint

Gray mapping keeps neighboring constellation points one bit apart.

Test cases

case 1

in: [[0,0]]

expected: [1,1]

case 2

in: [[0,1]]

expected: [-1,1]

case 3

in: [[1,1]]

expected: [-1,-1]

case 4

in: [[1,0]]

expected: [1,-1]

Starter codePython

def qpsk_map(bits):
    # Your code here
    pass

4 test cases · run your code against them in the editor