**3.3. Low-complexity soft-output detection via combining multiple observations**

The blockwise processing of the receive symbol stream enables a further possibility to improve the performance without increase of the maximum delay of the ACR [17]. This method utilizes an overlapping block-structure. Since multiple blocks thus contain the same symbol, processing of each block delivers (possibly different) beliefs on the same symbol, i.e., multiple observations are available. Suitably combining the observations obtained from processing of each block, results in a (possibly more reliable) final decision. Depending on the applied blockwise decision scheme (here SO-MSDD and DF-DD are considered), there are different options how to combine multiple soft/hard observations to deliver a final hard and/or soft decision for the respective symbol [17]. The most interesting option is to combine multiple hard decisions, e.g., obtained from DF-DD, of the same symbol to form a single soft decision. This method can be implemented by using the sum of the individual hard-decisions as (quantized and scaled) "soft-output"; it preserves the low complexity of blockwise DF-DD, yet enables to exploit the additional gain of soft- vs. hard-decision channel decoding.
