New Zealand Police’s Mimomax voice backhaul network was put to the test in February 2023 when Cyclone Gabrielle struck, cutting off cellphone and fiber communications to the East Coast of New Zealand’s North Island. The Mimomax voice backhaul links situated in that area emerged unscathed from a weather event which is predicted to involve the most expensive clean-up on record from a Southern Hemisphere storm.
The situation
As the Cyclone neared New Zealand, it was clear that the impact would be felt along the eastern coast of the North Island. With at least three links operational in the region where the heaviest rains from the Cyclone made landfall, and another three links in areas of extremely high winds, the Mimomax voice backhaul network was subject to extreme weather that downed trees, created landslides and washed-out roads and bridges.
Severe flooding which pushed forestry slash down rivers, taking out bridges and roads also severed the fiber network in multiple locations. Downed trees knocked out the power which then meant that cellphone sites which typically only have battery backup to cover blackouts lasting a few hours also went down when the electrical grid was impacted. Furthermore, cellphone sites which did retain power lost communications connectivity when the fiber backhaul was severed. With roads destroyed across the region, some of NZ Police’s sites could also only be accessed by helicopter – a daunting exercise when faced with cyclone-force winds.
“These failures with phone connectivity, data circuits and the cellular networks meant that communications-wise, the Eastern Districts were entirely cut off,” says Richard Hutchinson, Infrastructure Engineer, NZ Police. “In terms of NZ Police operations, the Gisborne and Hawkes Bay areas had to fall back to regionalized dispatch.”
Results
Despite some areas receiving 600% of their average monthly rainfall totals and winds registering 145kph (90 miles per hour), the Mimomax voice backhaul network remained operational throughout the 3-day event, providing redundant communications at a time when it was most needed. “The radio standards organizations, ITU and TIA, both indicate that links below 1GHz can reasonably ignore rain events unless the links are very long or the rain is extremely heavy,” said Mr Hutchinson. “NZ Police now have some local practical experience to back those standards up.”
Read more in this article featured in Critical Comms magazine.
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