function x = randomPSK(n, len)
  % symbols: nth roots of unity
  % i.e. solutions to polynomial x^n - 1 = 0
  symbols = roots([1 zeros(1, n-1) -1]);

  x = zeros(1, len);
  for i = 1:len
    x(i) = randomChoice(symbols);
  end
end

function x = randomChoice(arr)
  i = randi(length(arr));
  x = arr(i);
end