Soft Decode and Forward Improves Cooperative Communications

Mobile receivers can benefit from an increased spatial diversity through cooperation. Two relaying techniques are typically used: either Amplify and Forward (AF) or Decode and Forward (DF). This contribution presents a new technique which combines the main advantages of both AF and DF. This technique amounts to a DF scheme where all operations are performed in a soft-input soft-output fashion. The relay performs a soft decoding of the received signal and reencodes it softly, that is incorporates reliability information about the decoded data. Simulations show that this Soft-DF scheme outperforms both AF and DF.