Embodiments of the present disclosure provide methods, devices and computer program for downlink control channel transmission and detection. According to one or more embodiments, a method implemented in a network device comprises: selecting, for a terminal device, at least one set of downlink control channel candidates from two or more sets of downlink control channel candidates. Each set of the two or more sets of the downlink control channel candidates is associated with a different communication level, each communication level corresponding to one or more of a different set of aggregation levels, a different set of transmission formats, a different target block error rate (BLER), and a different target latency. The method further comprises transmitting, to the terminal device, the selected at least one set of downlink control channel candidates.