Some demonstrative embodiments may include an apparatus including a Hybrid Automatic Repeat Request (HARQ) buffer configured to buffer compressed Log Likelihood Ratio (LLR) values corresponding to an unsuccessfully-decoded transmission of a data block, a bit size of the HARQ buffer is equal to or less than 2.5 times a supported HARQ receive (Rx) size, which is to be reported to a transmitter of the data block; and a decoder configured to decode a retransmission of the data block according to the HARQ scheme based on combined LLR values, which are based on the compressed LLR values and on LLR values corresponding the retransmission of the data block, wherein a HARQ gain of decoding the retransmission of the data block based on the combined LLR values is at least 2 Decibel (dB) for an Additive White Gaussian Noise (AWGN) channel.