Repetition Code BER

Problem

Return the post-decoding bit error rate of a length-n repetition code with majority decoding over a BSC with crossover p:

P_e = sum_{i=(n+1)/2}^{n} C(n, i) * p^i * (1 - p)^(n - i)

Assume n is odd.

Hint

An error survives majority decoding only when more than half the bits flip.

case 1

in: [0.1,3]

expected: 0.028000000000000008

case 2

in: [0.5,3]

expected: 0.5

case 3

in: [0.1,5]

expected: 0.008560000000000002

case 4

in: [0.2,3]

expected: 0.10400000000000004

Starter codePython

import math
def repetition_ber(p, n):
    # Your code here
    pass

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