Reduce Interference in Wireless Mesh Network
This sort of protocol can be really difficult to solve. I'll say a few words about a project I was involved with years ago. 

A "new node" didn't ping rather it listened - basically it picked-up on any nearby node that was already a member (it was listening for the node_members regular hub transmission). Doing it this way means the new_node didn't interfere with anything and, could silently choose the optimum "parent" i.e. the node_member with the most efficient transmission to the hub (master).

At regular intervals (obviously recognizable by the new_node), each node_member had a small timeslot to accept a "new node" request (should one come along). Basically this worked because there was always a "spare" receive time slot "offered" by only one node_member at a time that could be used for the new_node to make its presence known.

Once the parent (node_member) adopted the new_node, the whole network then had to accomodate space for the new guy to become a bona fide node_member and this does take some thinking about. 

It's an interesting problem and probably best solved and developed by writing a PC program that simulates a variable system with random path losses and drop-outs. That's what we started to do but, the job fell-through for commercial reasons that I don't need to go into.