The head-protection airbag device comprises an airbag stored along a roof side rail and including a gas-introducing path at its upper edge. The storage device includes a bladder that contains the hydrogen fuel source and conforms to the volume of the hydrogen fuel source. The method further includes sorting intervals between pulses into histogram bins, each bin representing a range of time intervals between two pulses, each pulse indicative of a radar frequency and limiting network traffic on a frequency based on a selected bin count. The active region includes a second conductive structure formed therein. The reinforcing rib network includes a front tubular rib element extending laterally across a front width of the seat section, and a top tubular rib element extending laterally across a top width of the back section. The locking portion having at least one locking tang attached to the coupling portion and extending to the second end of the first fitting.