A method for transmitting over a dynamically configurable air interface, the method comprising: selecting (525, 625), by a transmitting device, an air interface from a plurality of air interface candidates in accordance with transmission requirements between the transmitting device and a receiving device; signaling, by the transmitting device, information about the selected air interface to the receiving device; and transmitting (535, 635), by the transmitting device, a packet transmission to the receiving device using the selected air interface, wherein each of the plurality of air interface candidates comprises a waveform building block, a frame structure building block, a multiple access technique building block, a transmission/re-transmission technique building block, and a coding/modulating technique building block, each building block comprising a plurality of options, wherein selecting the air interface from the plurality of air interface candidates comprises selecting an option out of the plurality of options of each building block in accordance with the transmission requirements, wherein signaling information about the selected air interface to the receiving device comprises transmitting indications of the selected options of the respective building blocks of the selected air interface to the receiving device; and wherein a transmission made for the packet transmission using the selected air interface is specified collectively by a waveform, a frame structure, a multiple access technique, a transmission/re-transmission technique and a coding/modulating technique, each being the selected option out of the plurality of options of the respective building blocks. selecting (525, 625), by a transmitting device, an air interface from a plurality of air interface candidates in accordance with transmission requirements between the transmitting device and a receiving device; signaling, by the transmitting device, information about the selected air interface to the receiving device; and transmitting (535, 635), by the transmitting device, a packet transmission to the receiving device using the selected air interface, wherein each of the plurality of air interface candidates comprises a waveform building block, a frame structure building block, a multiple access technique building block, a transmission/re-transmission technique building block, and a coding/modulating technique building block, each building block comprising a plurality of options, wherein selecting the air interface from the plurality of air interface candidates comprises selecting an option out of the plurality of options of each building block in accordance with the transmission requirements, wherein signaling information about the selected air interface to the receiving device comprises transmitting indications of the selected options of the respective building blocks of the selected air interface to the receiving device; and wherein a transmission made for the packet transmission using the selected air interface is specified collectively by a waveform, a frame structure, a multiple access technique, a transmission/re-transmission technique and a coding/modulating technique, each being the selected option out of the plurality of options of the respective building blocks.