Will 5G 600MHz Be The New Prime Frequency Band?

Comparison of US 700MHz Digital Dividend (above) and APT 700MHz (below)

New Zealand is too small a country, with a population of 5 million, to support a full ecosystem from base stations to terminals on its own market size.

So, Professor Shafie, together with Australian operator Telstra, formally proposed APT 700MHz 5G at the 2008 APT Wireless Working Group meeting in the Asia-Pacific region.

To the surprise of both Australia and New Zealand, the band was soon adopted by South America and some countries in Northeast Asia, as it was in line with the frequency band of most countries in the ITU Region 3 (Asia Pacific). As the ecosystem grew stronger, European operators also became interested in the band.

Eventually, APT 700MHz was adopted by ITU Region 2 (Europe, Africa, Middle East), making it one of the most successful international bands for 4G LTE.

The 3GPP named APT 700MHz as Band 28, which is a frequency division duplex FDD mode with 703-748MHz uplink frequency and 758-803MHz downlink frequency, with a 10MHz protected band in the middle for uplink and downlink.

As the initiator of APT 700MHz 5G, New Zealand began deploying a 700MHz 4G network as early as 2013. In China, the 700MHz band belongs to China Radio and Television and is being used for 5G co-location sharing with mobile.

New Zealand is too small a country, with a population of only 5 million, to support a full ecosystem from base stations to terminals on its own market scale.

So, Professor Shafie joined forces with Australian operator Telstra to formally propose APT 700MHz at the 2008 APT Wireless Working Group meeting in the Asia-Pacific region.

To the surprise of both Australia and New Zealand, the band was soon adopted by South America and some countries in Northeast Asia, as it was in line with the frequency band of most countries in the ITU Region 3 (Asia Pacific). As the ecosystem grew stronger, European operators also became interested in the band.

Eventually, APT 700MHz was adopted by ITU Region 2 (Europe, Africa, Middle East), making it one of the most successful international bands for 4G LTE.

The 3GPP named APT 700MHz as Band 28. The band adopts frequency division duplex FDD mode, with 703-748MHz uplink frequency and 758-803MHz downlink frequency, and the middle 10MHz is the protection band for uplink and downlink.

As the initiator of APT 700MHz, New Zealand started to deploy a 700MHz 4G network back in 2013. In our country, as we all know, the 700MHz band belongs to China Radio and Television and is being used for 5G co-location and sharing with Mobile.

The countries and regions in blue on the map use the APT 700MHz solution

Due to the scarcity of low-frequency bands, international planning for 5G 600MHz began shortly after the dust settled on 700MHz.

In the resolution of WRC-15, the planning for mobile communications in the 470-694MHz range was put on the international agenda. And the holder of this band for the broadcast television business.

In 2017, the United States became the first country to auction the 5G 600 MHz band. The 5G 600MHz in North America is 3GPP Band 71, in FDD mode, with a downlink band of 617MHz-652MHz and an uplink of 663-698MHz.

T-Mobile became the largest holder of the 5G 600MHz spectrum, with its 600MHz 4G network starting to be deployed back in 2018, and last year T-Mobile even launched a standalone 5G network based on 600MHz.

There are two versions of the APT 600MHz plan that Professor Shafie showed us at the time, which are as the below showing.

B1, Downlink: 612-652MHz Uplink: 663-703MHz

B2, downlink: 617-657MHz uplink: 663-703MHz

The two options of APT 600MHz are perfectly interfaced with APT 700MHz, and both options have their own advantages.

B1’s upstream and downstream duplex interval is 11MHz, so the phone can meet the spurious suppression requirement with a single duplexer.

The B2 solution, however, only goes to a 617MHz downlink, which has less impact on the frequency of broadcast TV than B1. However, in B2’s scheme, the upstream and downstream duplexer interval is only 6MHz, and the protection band is very narrow, so two duplexers have to be needed in the cell phone to solve the suppression demand.

Back in the early days of APT 700MHz, the performance of duplexers was limited due to the limitations of materials and technology at that time, and the industry’s solution at that time was two duplexers switching.

Another limitation of this approach is that users can only use up to 35MHz spectrum access, while 3GPP supports a maximum of 40MHz on sub-1GHz, which is equivalent to 5MHz resources being restricted (since 3GPP has not given a specific bandwidth configuration of 600MHz for the time being, APT 700MHz is used here as a reference).

In the three AWG wireless working group meetings in 2021-2022, the program experienced heated debates due to the different interests of countries and various corporate representatives.

One of the main opposing parties was the operators who supported North American 5G 600MHz. They want to take the current North American 5G 600MHz and use it directly to advance the deployment of low-band 5G as soon as possible. If they wait for APT 600MHz, it may take a long time from the adoption of the meeting, and pre-study, to the product launch and band opening.

Another opposing party is the terminal companies. They also hope that countries in the Asia-Pacific region can use the North American 5G 600MHz band to avoid the increase in the number of cell phone RF front-end duplexers.

Finally, after many rounds of debate and strong support from India, APT’s wireless working group finally succeeded in identifying B1 as the preferred option for APT 600MHz and formally contacted 3GPP for a feasibility study.

Ericsson’s standards representative also expressed interest in APT 600MHz at the APT’s Wireless Working Group and eventually promoted it as a Study Item for 3GPP. (Note, 3GPP research usually starts with a study item first, and then the project can be formally established as a Work Item after the proposal is validated and approved by the 3GPP representative).

What 3GPP finally adopted was the B1 approach recommended by the APT Wireless Working Group, i.e. a duplexer band planning scheme, which is undoubtedly a great success for the mobile communication industry in the Asia-Pacific region.