Wireless takes off

The future of hyperfast wireless broadband

DIDO promises to be a hit with users of the wireless, writes Boyd Murray

A high-speed, fixed-wireless technology recently field-tested by the CSIRO has caught the public's imagination because it has significant datarate and range advantages over competing 4G technologies preferred by NBN Co.

Distributed input, distributed output (DIDO) wireless offers 12 to 100 megabits a second to users within 60 kilometres of a tower but to understand its development and why the CSIRO's world-leading trials are so important, a brief history lesson is in order.

When Guglielmo Marconi ushered in the modern age of wireless telecommunications with his 1901 transatlantic wireless-telegraph demonstration, he achieved it using a SISO (single input, single output) system. The next advancement

was having two (or more) receiver antennas and selecting or combining the antenna outputs to improve the reception. This is now called a SIMO (single input, multiple output) system and is still widely used today.

In the 1990s and 2000s, researchers were working on MIMO (multiple input, multiple output) with transmitters and receivers on

both ends. Mathematician Claude Shannon postulated that the datarate of a single wireless link was proportional to

the amount of frequency spectrum used. But MIMO had many links between each transmitter and receiver, allowing much higher datarates in the same frequency spectrum.

But what happens when many users want to access the same wireless channel – for example, on a wi-fi network? A way is to share by using the same frequency-spectrum slot at different times – time division, multiple access (TDMA).

users) of 292 Mbps and uplink datarate of 71 Mbps. This is an average bandwidth efficiency of 9Mbps a MegaHertz (only half of even the prototype CSIRO MU- MIMO system). LTE is for mobile systems and has broad, unfocused, 120-degree sector beams to serve a five to 10 kilometre radius from the base station.

CSIRO estimated that in sparsely populated regions 20 LTE base stations would be required to service the same area served by one of its MU-MIMO base stations. All is not lost however, as it is expected that, at some time, LTE will be upgraded to include MU-MIMO.

In an August address at Macquarie University, NBN Co’s design and planning manager Peter Ferris was asked how experimental technologies such as DIDO or MU-MIMO fitted in to its thinking. Ferris said NBN Co was risk-averse (it was on a tight schedule) and would only choose standards-based technologies from recognised companies. This defines how Australia views home-grown wireless technologies.

How then can CSIRO’s wireless technologies find their way into the market without local support? Perhaps the answer comes from looking at the two most significant Australian wireless technologies success stories of the last decade – Radiata and CSIRO.

After significant research and development in the early ‘90s, CSIRO patented its OFDM WLAN technology in 1995. It was licensed by startup company Radiata, then first to develop a CMOS chipset for what was to become wi-fi. Radiata led for a time the IEEE 802.11 standard taskgroup that wrote wi-fi standards adopted by hundreds of makers worldwide. Cisco bought Radiata in 2000 for $US295 million. Two years ago, CSIRO licensed its WLAN patents to wi-fi makers for an undisclosed amount thought to be several hundred million dollars.