One or more computer-readable media having instructions that, when executed, cause an eNB to: establish a primary cell, PCell, in a mobile broadband spectrum to communicate with a first relay node; transmit, via the PCell, a discovery signal message that includes configuration information of millimeter wave, mmWave, discovery signals that are to be transmitted by one or more additional relay nodes and a request for measurement information corresponding to the mmWave discovery signals; wherein the configuration information includes discovery occasions and sequence identifiers, wherein: - each of the first and the one or more additional relay nodes is configured to transmit a number of parallel mmWave discovery signals, with each mmWave discovery signal using a respective signal sequence, - the signal sequence used by each of the first and one or more additional relay nodes identifies the respective each of the first and the one or more additional relay nodes, - a discovery cluster is transmitted periodically with a discovery period and includes a number of discovery occasions, - in each discovery occasion of the discovery cluster the mmWave discovery signal is transmitted with a different beam direction, receive, via the PCell, a measurement report from the first relay node that includes measurement information that corresponds to the mmWave discovery signals, the measurement report includes; a sequence identifier that identifies which of the number of parallel mmWave discovery signals transmitted by a relay node of the one or more additional relay nodes is measured by the first relay node and a discovery occasion index that identifies the particular beam used to transmit the detected mmWave discovery signal, select a second relay node, based on the measurement report, to provide a mmWave secondary cell, SCell, for the first relay node; and transmit, to the second relay node, a radio resource control, RRC, context of the first relay node that includes the sequence identifier and the discovery occasion index. establish a primary cell, PCell, in a mobile broadband spectrum to communicate with a first relay node; transmit, via the PCell, a discovery signal message that includes configuration information of millimeter wave, mmWave, discovery signals that are to be transmitted by one or more additional relay nodes and a request for measurement information corresponding to the mmWave discovery signals; wherein the configuration information includes discovery occasions and sequence identifiers, wherein: - each of the first and the one or more additional relay nodes is configured to transmit a number of parallel mmWave discovery signals, with each mmWave discovery signal using a respective signal sequence, - the signal sequence used by each of the first and one or more additional relay nodes identifies the respective each of the first and the one or more additional relay nodes, - a discovery cluster is transmitted periodically with a discovery period and includes a number of discovery occasions, - in each discovery occasion of the discovery cluster the mmWave discovery signal is transmitted with a different beam direction, - each of the first and the one or more additional relay nodes is configured to transmit a number of parallel mmWave discovery signals, with each mmWave discovery signal using a respective signal sequence, - the signal sequence used by each of the first and one or more additional relay nodes identifies the respective each of the first and the one or more additional relay nodes, - a discovery cluster is transmitted periodically with a discovery period and includes a number of discovery occasions, - in each discovery occasion of the discovery cluster the mmWave discovery signal is transmitted with a different beam direction, receive, via the PCell, a measurement report from the first relay node that includes measurement information that corresponds to the mmWave discovery signals, the measurement report includes; a sequence identifier that identifies which of the number of parallel mmWave discovery signals transmitted by a relay node of the one or more additional relay nodes is measured by the first relay node and a discovery occasion index that identifies the particular beam used to transmit the detected mmWave discovery signal, select a second relay node, based on the measurement report, to provide a mmWave secondary cell, SCell, for the first relay node; and transmit, to the second relay node, a radio resource control, RRC, context of the first relay node that includes the sequence identifier and the discovery occasion index.