A method for adjusting a bandwidth of a carrier signal providing access to a cellular radio network through a High Altitude Platform, HAP, the carrier signal being transmitted within a predetermined frequency spectrum channel, the HAP transmitting a first carrier signal of a first bandwidth in a first part of the predetermined frequency spectrum allocation, the method comprising: configuring transmission of a second carrier signal of a second bandwidth in a second part of the predetermined frequency spectrum allocation, the second bandwidth being different to the first bandwidth; and configuring handover of traffic from the first carrier signal to the second carrier signal.