Not sure what you mean by heartbeat groups, but if I'm guessing correctly this sounds fairly similar to chaffing and winnowing https://en.wikipedia.org/wiki/Cha

Not sure what you mean by heartbeat groups, but if I'm guessing correctly this sounds fairly similar to chaffing and winnowing https://en.wikipedia.org/wiki/Chaffing_and_winnowing https://en.wikipedia.org/wiki/Chaffing_and_winnowing which lets information from multiple senders (or even bogus, non-existent senders) to be clumped together and broadcast in such a way that every destination is able to pick out only the messages intended for them and cannot distinguish messages not meant for them from uniformly random garbage.