Decoding algorithm for the HS-DPCCH HARQ message exploiting the pre-and postambles

A base station to decode a high speed dedicated physical control channel (HS-DPCCH) using a preamble and postamble of a hybrid automatic repeat request (HARQ) message while maintaining a fixed false alarm probability of interpreting a discontinuous transmission (DTX) as a HARQ acknowledgement (ACK) or HARQ negative acknowledgement (NACK), the base station comprising:

• a transceiver to receive a signal from a user equipment (UE);
• a G-RAKE demodulator coupled to the transceiver, the G-RAKE configured to despread the signal and to combine the despread signal to produce a combined symbol estimate vector x including a preamble and postamble of the HARQ message;
• and
• a decoder coupled to the G-RAKE demodulator, the decoder configured to receive the combined symbol estimate vector x from the G-RAKE demodulator, to check the combined symbol estimate vector x to determine whether the signal includes a DTX, HARQ ACK or HARQ NACK, and to output the DTX, HARQ ACK or HARQ NACK, where the decoder is further configured to determine boundaries of a DTX region, to check whether the combined symbol estimate vector x lies within the DTX region.