A radio communication apparatus configured to: receive or generate a single base address seed; generate a plurality of data-channel access addresses from the single base address seed, each said data-channel access address corresponding to a respective data-channel identifier from a plurality of data-channel identifiers, wherein the generating of each access address comprises: - setting the value of a bit at a common first bit position in the respective access address to be equal to the value of a bit at a first common predetermined bit position in the base address seed or in the respective data-channel identifier; - setting the value of a bit at a common second bit position in the respective access address to be equal to the bitwise complement of the value of the bit at said first common predetermined bit position in the base address seed or in the respective data-channel identifier; and - setting values of one or more bits at one or more of the remaining bit positions in the respective access address in dependence on the values of one or more bits at one or more bit positions in the base address seed and one or more bit positions in the respective data-channel identifier that are not said first common predetermined bit position in the base address seed or in the respective data-channel identifier; and send or receive a radio data packet comprising an access address from the generated plurality of data-channel access addresses, according to a predetermined radio protocol based on Bluetooth Low Energy. receive or generate a single base address seed; generate a plurality of data-channel access addresses from the single base address seed, each said data-channel access address corresponding to a respective data-channel identifier from a plurality of data-channel identifiers, wherein the generating of each access address comprises: - setting the value of a bit at a common first bit position in the respective access address to be equal to the value of a bit at a first common predetermined bit position in the base address seed or in the respective data-channel identifier; - setting the value of a bit at a common second bit position in the respective access address to be equal to the bitwise complement of the value of the bit at said first common predetermined bit position in the base address seed or in the respective data-channel identifier; and - setting values of one or more bits at one or more of the remaining bit positions in the respective access address in dependence on the values of one or more bits at one or more bit positions in the base address seed and one or more bit positions in the respective data-channel identifier that are not said first common predetermined bit position in the base address seed or in the respective data-channel identifier; and - setting the value of a bit at a common first bit position in the respective access address to be equal to the value of a bit at a first common predetermined bit position in the base address seed or in the respective data-channel identifier; - setting the value of a bit at a common second bit position in the respective access address to be equal to the bitwise complement of the value of the bit at said first common predetermined bit position in the base address seed or in the respective data-channel identifier; and - setting values of one or more bits at one or more of the remaining bit positions in the respective access address in dependence on the values of one or more bits at one or more bit positions in the base address seed and one or more bit positions in the respective data-channel identifier that are not said first common predetermined bit position in the base address seed or in the respective data-channel identifier; and send or receive a radio data packet comprising an access address from the generated plurality of data-channel access addresses, according to a predetermined radio protocol based on Bluetooth Low Energy. <EOS>