SISO decoder with sub-block processing and sub-block based stopping criterion

SISO decoder for iteratively decoding a block of received information symbols (r), in particular for use in a turbo decoder, said block being divided into a number of windows of information symbols, said SISO decoder comprising:

• at least one SISO decoding unit (17, 21) for SISO decoding of the received information symbols (r) of a window,
• a window activity flag storage (23) for storing window activity flags indicating if a window is made active or inactive,
• a window activity flag setting unit (17) for setting said window activity flag active or inactive, wherein said window activity flags are initially set active and wherein a window activity flag of a window is set inactive if a certitude indication value of the information symbols in said window are above a predetermined certitude threshold,
• a window activity flag reading unit (17, 22) for reading said window activity flags from said window activity flag storage (23), and
• a control unit (27) for controlling said at least one SISO decoding unit (17) based on the read window activity flags such that the information symbols of a window for, which the corresponding window activity flag is set inactive are not SISO decoded in subsequent iterations.