Announcing XR Mode Version 2.0
Some stunning news to share. Earlier this year, we announced an important advance in improving the range performance of Haystack’s DASH7 technology over LoRa — DASH7 XR Mode. Using NASA-derived error correction (and deployed on the New Horizons space probe), we achieved results that were 10–20x better than a comparable LoRaWAN implementation. In addition to tripling the range of LoRa, it meant that developers could safely work with higher data rates, expect longer battery life, and expect far lower levels of packet error.
One drawback of XR Mode as we announced it in the spring, however, was its readiness for higher data rate or “LAN” applications like over-the-air firmware transfers. XR Mode also required a higher latency query regime than is possible with DASH7 LAN Mode, as well as some other limitations. So DASH7 devices in the future would potentially operate in one of two modes — XR Mode for very wide area comms and LAN Mode for local area, high bandwidth comms. Totally doable but ultimately sub-optimal: in an ideal world we would achieve XR Mode-levels of performance in all modes of DASH7-based communications.
Hacking XR Mode Further
In the course of designing XR Mode, we hypothesized that LDPC error correction would not be the end of the improvements to our DASH7 networking stack. Fast forward six months and today we have combined three encoding technologies — two of which are so bleeding-edge that mass adoption in cellular won’t happen until deep into the 5G technology roadmap — in a novel way that yields maximum gain for LPWAN-types of packets .. today. We’ve numerically analyzed trillions of parameter vectors (thanks Google Cloud) in order to get the best performing code.
The results are remarkable and you won’t find them anywhere else in the LPWAN industry today. We are observing:
- Quality of Service (QoS) that is 100x better than LoRaWAN: better real-world signal propagation over LoRaWAN by 14 dB (25x) at maximum range, and propagation at < 1% Packet Error Rate is 100x of LoRaWAN.
- Our decoder implementation is 50x faster than our LDPC decoder, so we can support data rates as high as 50 kbps. This is as fast as LoRa chips can go (SF5, 500 kHz).
- The encoding rate can be adaptively modulated the from 0.375 to 0.8, which allows the network to self-tune for low or high SNR environments.
What this All Means
This has multiple repercussions for Haystack developers and customers:
- There is no longer a distinction between DASH7 LAN mode and DASH7 XR Mode. All the builds of our software stack for Semtech’s LoRa will incorporate our latest innovations for XR Mode and … there’s no reason to continue to maintain two separate instances of DASH7 in our code. So, everyone gets XR Mode for all features and use cases — there’s no reason not to use it.
- Range is improved across all features, multi-year battery life is preserved, and implementation of features like on-demand GNSS/GPS is preserved.
- Technically speaking what we are doing is really cool considering we are doing with everyday, low power ARM-based microcontrollers what is (sometimes) done in high powered wireless comms like cellular, all while preserving multi-year battery life. Haystack’s forward error correction technology is comparable in decoding gain performance to the latest 5G codes, which are much longer (too long for practical LoRa usage), and which tend to be implemented in a hardware ASIC.
- We are achieving results that are extremely close to the Shannon limit, i.e. it is theoretically impossible to do much better with encoding technology alone. Surely, we will find areas to squeeze out an extra 0.5 dB here or there, but it won’t be though encoding directly. Now, just like the cellular industry, we have brought LPWANs into the “post-encoding” technology landscape.
Since announcing our new line of GPS asset tracking hardware, we have been delighted with the response to the availability of beta demo kits. Going forward, we will be deploying DASH7 XR Mode 2.0 on all demo kits and, of course, our commercially available hardware shipping soon. If you are interested in ordering a demo kit, our next build is underway now and supplies are limited.