Australia operates in the 915MHz ISM band and is somewhat unique in that both AU915 and AS923 are both allowed to operate.
With TTN about to launch the V3 server in Australian it’s an opportune time for the TTN Australian community to review how both systems can best co-exist going forward.
The launch of the V3 server is a Break-Point where we have an unique opportunity to:
- learn from history,
- review what has changed since the first introduction of LoraWan, and
- look forward at the next round of standards developments.
The later is one of the most important as we have the opportunity to ensure both AU915 and AS923 can co-exist and not restrict the deployment of the upcoming innovations.
The Australian 915MHz ISM band is divided into 64 channels. The number of channels are less than US915 where downlink channels are separate from uplink. In Australia, the gateway downlink channels overlapping the top three blocks of 8 channels (FSB6, 7 and 8). The challenge is to evaluate how AU915 and AS923 can co-exist and understand the impact of one on the other. (I’ve done this professionally looking at how cordless phone systems using different technologies can coexist, as an example, how does DECT perform when other cordless systems are in the same vicinity and then vice-versa).
In Australia we were fortunate as Meshed took a lead role and with TTN established a server in the region. They also recognised the limited supply of AU915 nodes and (at the time) the more available AS923 nodes. To provide access via AS923 Meshed installed dual head gateways, one on AU915 and the second on AS923. They are still in operation today. There are a small number of which are AS923 only.
Coming back to the points 1 and 2 above, about learning from history and the changes that have taken place since LoraWan was first rolled out in Australia. The equivalent topic would be the single channel gateway. When first released, it was one of few ways to get into LoraWan with a low cost gateway. Since there are many more gateway suppliers, there are low cost 8 channel gateway and there is significantly more open-source information to support DIY systems. As a result the single channel gateways are now actively discouraged as on-balance they do more “harm” to the network than good. So similarly, we need to understand the coexistence of AU915 and AS923 was important in the early days of LoraWan in Australia but we have the opportunity to reconsider how they can both be best used for the overall benefit of the Australian LoraWan and TTN community.
The limited supply of AU915 nodes no longer exists and the firmware is sorted. There is an installed base of AS923 nodes which need to be supported going forward. Maybe others can comment on the number or the proportion of nodes running on AS923 but there must be a reasonable number. So there is a strong case to continue supporting these existing systems.
Right now there are 1019 gateway in Australia
- 653 are on AU915
- 293 on AS_920-923
- 30 on AS_923-925
- 43 on US915 or EU868
So what is coming in the next 12+ months? (refer Semtech presentation TTN 2021 Conference)
- Frequency Hopping Spread Spectrum (as compared to the current Chirp Spread Spectrum),
- Repeater operation and
- Node to node transmissions within a LoraWan umbrella.
In my next post I will explain the Australian LoraWan channel allocation and compare the operation of AU915 and AS923.