A method for communication, includes communicating over the air with a first user equipment (UE) in a frequency domain duplexing (FDD) mode, which defines a downlink channel comprising a first set of time-frequency resources in a first frequency range and an uplink channel comprising a second set of time-frequency resources in a second frequency range, which is disjoint from the first frequency range. An excess capacity is identified in the uplink channel, and at a least a portion of the excess capacity is allocated for downlink communication by assigning a subset of the time-frequency resources in the second frequency range to the downlink communication. The method includes communicating over the air with at least one second UE by transmitting downlink information using concurrently a given subset of the first set of time-frequency resources in the first frequency range and the assigned subset of the time-frequency resources in the second frequency range.