摘要 |
A method to construct and detect a binary transmit signal is disclosed. The method is based on the assumption that certain decision errors are less severe than other decision errors, as e.g. in transmission schemes employing ARQ. To this purpose, the important information (e.g. the acknowledgement ACK) is transmitted with high power, whereas the less important information (e.g. the non-acknowledgement NACK) is transmitted with reduced power. An asymmetric modulation scheme is obtained. The detection threshold to decide at the receiver which of the two signals was transmitted is chosen such that the reliability of a detected ACK signal is higher than that of a detected NACK signal. The scheme has the advantage that the average power consumption decreases and further that in multi-user CDMA systems the average interference is reduced. <IMAGE> |