A battery-powered vacuum cleaner is provided with a battery pack that generates heat and is capable of efficiently cooling the battery pack. These systems provide for multiple-polarization and omnidirectional coverage using multiple radios, which may be tuned to the same frequency. For a given code rate, multiple code sizes are accommodated by allowing both the model matrix size nb and the expansion factor z to vary. The system and method further provide a repair process to reduce the latency of discovery of topology change, employ a node sequence number mechanism to differentiate between upstream nodes and downstream nodes on the multicast tree in the repair process, and provide an active joining process to reduce the latency of discovery of membership change.