Channel-Aware Opportunistic NOMA for Random Access in IoT Networks

In the Internet-of-Things (IoT), different types of devices can co-exist within a network. For example, there can be cheap but inflexible devices as well as flexible devices in terms of radio frequency (RF) capabilities. Thus, in order to support different types of devices in different ways and improve throughput, we propose a multichannel random access scheme based on power-domain non-orthogonal multiple access (NOMA), where each flexible or dynamic device (DD) can dynamically choose one of multiple channels when it has a packet to send. Since a DD can choose either an under-utilized channel or a channel of high gain depending on channel selection criteria, we also study a selection criterion that can take into account not only the system, but also user preference indicators in order to have a balanced performance.