I recently finished listening to the book Algorithms to Live By which takes algorithms from computer science, economics, and other fields and applies them to appropriate life circumstances. As a data scientist, this book was a great nerd out session for me filled with great insights. One of the concepts that you’ve encountered and maybe even heard of is called the information cascade. Though not always applicable, you can think of this as one way to explain the snowball effect. It is one of many ways to answer the question of why people, companies, nations, friends, and others do something that as individuals they would never do but as group end up doing, despite having different preferences.
A question I am asked often multiple times a day on sales calls is,”What about Sigfox and LoRa?” RPMA, or Random Phase Multiple Access, is often compared to, or thought to be on par with, competing unlicensed low-power, wide-area networks such as Sigfox and LoRa. I am writing today to tell you why that is far from the truth.
RPMA was created from the ground up to be the simplest, the most robust, and the most secure network for machine to machine communication. It is the only network purpose-built from the ground up to serve machines exclusively.
Let’s start with simplest. What if I told you there was a singular wireless network that could cover the earth (and no I’m not talking about Skynet Mr. Terminator)? With near infinite scalability, extremely long range, and a spectrum that is available in every country on the planet, RPMA can do just that. Device makers could create a single SKU that could operate on any part of the planet. RPMA runs on the 2.4 GHz band for the very reason of being able to cover the world with a single network. Sub-GHz competitors may point to the fact that sub-GHz frequencies can inherently penetrate further than a 2.4 GHz wave. The point, however, is moot for RPMA because with the combination of RPMA’s processing gain, receive sensitivity, and antenna diversity, it boasts the highest link budget in the wireless industry. That means RPMA broadcasts further and penetrate deeper than any sub GHz competition. Lastly, with a network built from the beginning to be able to scale to billions of endpoints, it creates a simple job for product managers. One SKU can serve any customer in the world, under any RPMA network, at any device count.
Let’s talk robustness. A single RPMA access point can demodulate and receive up to 1000 simultaneous transmissions over the network. There is virtually no such thing as a collision on an RPMA network. That fact coupled with a 100 percent message acknowledgment rate will leave even the most skeptical feeling secure and satisfied. That vastly overshadows competing unlicensed low power wide area networks that do not even have full bi-directional communication for message acknowledgment, and cannot receive two simultaneous signals without a collision and a resend.
Let’s finish with security. Imagine a small Internet of Things device, a tracker, that serves the purpose of parents being able to know the location of their children. One may reasonably suppose that the location of the child should be sent over a secure, encrypted network. The National Institute of Standards and Technology has defined a 128-bit Advanced Encryption Standard. That means that an additional 128 bits or 16 bytes must be transmitted with each message to create a secure digital signature. Sigfox provides virtually no encryption (and cannot with a fixed 12 byte message size), and LoRa provides only a 32-bit encryption. Both are well below the recommended standards. RPMA has a flexible packet size and easily supports 128 bit encryption just to name one of many security features built in.
While many may presently associate RPMA with the networks of Sigfox and LoRa, this will dramatically change as more and more familiarize themselves with the technologies behind the marketing.
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The cellular industry is built for human interface. RPMA was built from the ground up to provide connectivity exclusively for machines.
It is no secret that the Internet of Things is still very much a fragmented industry. I am constantly asked “why RPMA?” and “what about the new cellular standards for IoT?” Just to be clear, in the little over a year since Ingenu announced it would be rolling out a nationwide RPMA network in the United States, the cellular industry has discussed LTE Cat-0, LTE Cat-1, LTE Cat-M1, LTE Cat-M2, and NB-IoT each as being the answer to the IoT connectivity conundrum. Good thing machines don’t move as fast as the typical human consumer, or Mr. Machine would have already dumped his soon to be dead 2G phone for a variety of new non-working phones powered by non-existent networks. While the cellular industry does “seem” to be settling around LTE Cat-M1 and NB-IoT, we still have yet to see their networks, radio modules, devices, or applications in the real world. On the contrary, RPMA has been real world tested, and used in a variety of applications over the past eight years. It is real. It is now. It is here to stay. In stating my case for RPMA over the proposed cellular IoT networks, I will claim that RPMA is technically better, creates an easy global application, and prioritizes machines.
Let me start by admitting that cherry picking range is not directly relevant to building a commercial networks that must have deep reliable coverage. We cannot draw an 88 mile radius circle around one of our tower based Access Points and make the credible claim that by πr2,we can cover 24,000 square miles with a single tower. However, there is an indirect relevance in that the same aspect that allows RPMA to be used to build deep, reliable coverage (i.e. link budget) is the same aspect that allows for some truly amazing cherry picked results. Other technologies advertise their cherry pick, so we will play that game and show you quite an amazing cherry in the process.
T-Mobile has been refreshingly frank in its assessment of how disruptive and costly cellular technology sunsets are to end users. It doesn’t get much more direct than T-Mobile’s statement from this article:
Migrating technologies can often be expensive and include deploying skilled repair teams to swap out installed devices for LTE modules, which can cost $50 to $200 per device and up to $300 per truck roll. Those costs might not be right for every business today…
We couldn’t really have said it much better ourselves. We completely understand how important network longevity is to traditional M2M and newer IoT customers.
What we would like to explore in this post is how to efficiently send very small packets of data. For this post, we’ll concentrate on the uplink. Stay tuned for a description of the RPMA downlink in a future post.
Part Nine: Power Consumption
Low Power Wide Area (LPWA) devices are often battery powered. After all, the LP of LPWA stands for “low power”. Given that these devices are low cost, they do not warrant the cost of frequent battery replacement. Requiring labor to service these types of devices destroys the Return on Investment (ROI) the connectivity. Battery life of 10-20+ years is critical.
Thus, power consumption is extremely important to optimize for maximum battery life. Power consumption is an unknown until a finalized production system and endpoints are commercially available in the field. Cellular LPWA is designing the protocols with power consumption in mind, but they are years away from proving out the actual real-world measurements on a commercial system and have fundamental design issues regarding power consumption that will become apparent over time.
Power consumption is an unknown until a finalized production system and endpoints are commercially available in the field.
Part Eight: Robustness
Robustness (or the lack thereof) in the cellular LPWA specifications is another example of cellular folks being clever to specify requirements that are easily achievable. In this case, its simulation based on the TU-1 Hz channel model as stated in TR45.820 : Cellular system support for ultra-low complexity and low throughput Internet of Things (CIOT) lacks realistic expectations. RPMA has been in field deployed for 6 years and we have routinely seen channels in the field that are far more adversarial. We were surprised at the variability of the channel even for stationary devices.
The Typical Urban(TU) 1 Hz channel model is not a realistic model even for stationary devices, yet that is the channel model that governs all of the cellular LPWA simulations.
Part Seven: Firmware Download
Being able to download firmware updates is a critical capability in virtually all applications we have encountered. 10-20 years is a long time to commit to a factory installed firmware image. This is another example of where the cellular folks were smart enough to bias the requirements inTR45.820 : Cellular system support for ultra-low complexity and low throughput Internet of Things (CIOT). The problem is that the requirement governing code download size is far from realistic.