The Radix token supply increases when there is unmet demand for them indicated from the integrated Radix exchange (DEX). The new supply is distributed 50% to those nodes that are supporting the Radix network in various ways via the services they run in their individual node.  The other 50% is distributed to the wallet balance holders in the form a interest payments.  By the way the wallets do not have to be online to have the interest allocated to the wallet address.  The interest just resides in the network as an unclaimed transaction until the wallet is online to receive the interest payments.