A method comprising configuring a narrowband internet of things carrier relative to one or more physical resource blocks of a radio carrier, the one or more physical resource blocks having a bandwidth that is greater than a bandwidth of the narrowband internet of things carrier; and configuring the narrowband internet of things carrier relative to the one or more physical resource blocks such that there is a first guard band between the narrowband internet of things carrier and a first adjacent physical resource block, and a second guard band between the narrowband internet of things carrier and a second adjacent physical resource block.