A base station transmits a control message to a wireless device to configure first radio resources of a control channel and second radio resources of a data channel. The control message indicates a starting OFDM symbol of the control channel in a subset of subframes, a frequency allocation in terms of resource blocks for the control channel, and a configuration of the subset of subframes in which the first radio resources of the control channel are configured. The second radio resources of a first data channel starts from the starting OFDM symbol in the subset of subframes.