The present invention relates to a method for decoding data, said method using windows (WID) of input data. The invention is characterized in that it comprises for a current window the steps of:--Performing a forward recursion, wherein said forward recursion is initialized with a forward state metric vector (a) from the upper stake (STK) of the previous window of the same step of the previous iteration, a window (WID) comprising a lower and an upper stake (STK), and--Performing a backward recursion, wherein said backward recursion is initialized with a backward state metric vector (b) from the lower stake (STK) of the next window of the same step of the previous iteration. Use: Receiver in a communication system.