From exploding black holes to your home Wi-Fi
In the early 1990s, computers that needed to talk to each other needed cables. Radio looked like the obvious replacement, but indoors it failed badly.
Radio waves bounce off walls, ceilings and furniture. A receiver hears the same signal several times: a direct copy plus a jumble of late echoes. At useful speeds, those echoes smeared together and garbled the data. Engineers called it the multipath problem, and nobody had solved it at speed.
An answer from outer space
In the 1970s, engineer John O'Sullivan had searched for radio pulses from exploding mini black holes, as predicted by Stephen Hawking. Those pulses would arrive faint and smeared, so he built tools to clean up weak, distorted signals, including a fast Fourier transform chip.
The black holes never showed up. Back at CSIRO in Sydney, though, O'Sullivan and his team of Terry Percival, Graham Daniels, Diet Ostry and John Deane realised the same maths could fix indoor radio.
The fix
Their system split data across many slower sub-channels sent side by side. Each was slow enough that the echoes no longer overlapped. Error correction cleaned up what interference remained.
CSIRO patented the method in Australia in 1992, with the US patent following in 1996. It became part of the 802.11a, g and n Wi-Fi standards used worldwide. In 2000, the CSIRO spin-off Radiata demonstrated the first chip meeting the new standard and was soon bought by Cisco.
Getting paid
As Wi-Fi took off, most manufacturers used the CSIRO method without paying for it. From 2005, CSIRO took legal action in the United States and won settlement after settlement. By 2012 it had licence agreements with 23 companies, earning more than $430 million for Australian research.
The team won the Prime Minister's Prize for Science in 2009 and the European Inventor Award in 2012. The patents expired in 2013, by which time about five billion devices had been sold.
The handout notes one lasting regret. Australia invented the key to fast Wi-Fi but never built a Wi-Fi manufacturing industry. The chips are made overseas.
The coin
The $1 WLAN coin is part of the Royal Australian Mint's 2026 Bright Ideas collection. It is a fitting coin for anyone in science, technology or IT.