Algorithm 1 Sample selector

Input: M: Modulation scale; s: Initial estimate s

Output: Candidate node: Set of each layer candidate node

1: if M = 4(QPSK) or 16(16QAM) then

2:  Base address = 0;

3:  Select all constellation points as Candidate node;

4: else

5:  Calculate Base address based on s value;

6:  Add the corresponding full constellation S table according to M;

7:  Find the candidate node value of the corresponding sequence number in the S table

and store it in candidate node;

8: end if

9: return candidate node