A system and method for providing communications between a hub (medical controller) and a node (an implant) are disclosed. The hub selects an operating channel within a channel group in accordance with applicable regulations, and transmits signals to facilitate communications with nodes. A node sequentially tunes to individual channels within the group, monitoring each channel for a hub transmission during a monitoring period. If a hub transmission is detected, the node stays on the current channel. Otherwise, the node tunes to a next channel in the channel group. The hub transmission may be directed to unconnected nodes, to a single connected node, or to a group of connected nodes. The node transmits a first frame to the hub at a designated transmission time and receives a response. The node reports an emergency by sequentially transmitting emergency frames on each of the channels until receiving an acknowledgment from the hub.