Parent selection algorithms for TDMA based Wireless Sensor Networks with a tree overlay are disclosed. The WSNs are prone to faults due to the harsh environments in which they operate. When faults occur on the node, the faulty node is no longer able to transmit data. As a result, the children of the node become orphans. Existing mechanisms do not have means to assign new parents to the orphans such that either the load on the new parents is relatively balanced or the TDMA schedule change is minimal. Two algorithms are disclosed. The first one uses parent assignment algorithm such that there is minimal change in the TDMA schedule whereas the second one uses a parent selection algorithm such that the load on the new parents are relatively balanced which leads to balanced energy expenditure. FIG. 1