Optus reuses 4G 2300Mhz frequency to create dual-band 5G

Optus has successfully launched a world-first dual-band 5G network in Sydney today, by re-using existing 2300 MHz 4G spectrum alongside new 5G 3500 MHz spectrum.

Optus partnered with Samsung and Ericsson to achieve the feat, which will increase 5G coverage and capacity for customers.

The same technology will be launched in Melbourne in coming weeks, and was demonstrated today using Samsung’s new range of Galaxy S20 5G devices. The use of both frequency bands will allow Optus to provide coverage in more places, and more capacity in those places, by using two distinct frequency bands.

Kent Wu, Optus Head of Network Access Planning and Quality, said:

“As we push ahead with the roll out of our 5G network we are also continuing to test and implement new ways of enhancing our 5G network. Initial findings from our dual band testing have shown that the use of these two spectrum bands delivered increased 5G capacity and coverage which if deployed will ultimately benefit our customers.

Our 5G customers are already enjoying higher average speeds, quicker time to download content and a consistent high definition video experience. The implementation of a dual-band 5G network will enhance these elements to ensure experiences are more reliable, particularly during peak usage times.”

One of the challenges with 5G, even in the sub-6GHz range, is signal penetration.

Many of you will probably recall the earlier days of 3G – which used 2100 MHz frequency spectrum. This – and higher frequencies – led to poor indoor reception, particularly in larger, concrete and steel structures like office buildings, shopping centres, car parks and the like. Over time, the major carriers adopted lower frequency bands to increase indoor coverage and greater reach, at the expense of greater capacity. Telstra’s Next G – which ran at 850 MHz – was the most well known of the lower frequency networks.

With 5G, the frequency bands used are often higher, and even Optus is using 2300 Mhz and 3500 MHz bands which will have the same characteristics as early 3G and 4G networks. Over time, as the 3G and 4G frequencies are reused, that indoor and in-building penetration will improve, but even here, we’re only talking about the sub-6GHz frequencies.

Having equipment that can support multiple bands – which we have for 3G and 4G already – will be a huge step forward for 5G, as we approach the 3G shutdown in 4 years time. Carriers will be able to support multiple bands off single pieces of equipment, meaning less congested cell towers or – more likely – more utilisation of existing cell towers minimising the need for new ones.

mmWave networks – which will run above 30GHz – are going to have significantly worse indoor coverage, to the point they’ll likely only be really usable in outdoor areas for the foreseeable future. Today’s announcement from Optus will have no bearing on these future developments.