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The Internet of Things (IoT) is all about connectivity, so it’s not surprising that so many alternatives have arisen for getting data from “here to there”. For short range we have Wi-Fi, Bluetooth, ZigBee and Z-Wave, just to name a few. For longer range, we have had 2G / 3G and now 4G LTE, with the introduction of 5G still years from deployment. In addition, a new breed of low-power, long-range wireless networks (LPWANs) have arisen and are now being rolled out by companies such as Sigfox or Ingenu. Even some of the larger carriers have gotten into the game, such as Orange or SK Telecom, who have committed (or at least made some commitment) with a technology called LoRA. The question is, do we need these alternatives, or are they all just Band-Aids until we get to 5G?
To build connected devices you basically need three different pieces (at a minimum). You need a device that can connect, a network connection and an application. As sensor prices have decreased, we have seen projections for billions of connected devices by 2020 and beyond. So how are all these devices going to connect? To handle billions of connections, we need a wireless technology that is designed to do the job—to handle the long distances, use minimal power and lower costs associated with many IoT applications.
Many IoT connections, especially those connected at long range, are different than today’s distributed devices. The devices are in remote or hard to reach areas, so battery life is critical. We’re talking years to change batteries, not days, weeks or even months. Distances are longer (think cellular and miles / kilometers), and data rates need to handle occasional small bursts of data rather than continuous voice or video. Fundamentally, many IoT connections just don’t need what traditional 2G / 3G / 4G was designed to do.
Traditional long-range wireless connectivity is well adapted to situations where transfer rates require a reasonable amount of speed. Many connected devices (think mobile phones) have a reasonably sized battery and are easily recharged on a fairly regular basis. These networks are not designed for low data rate devices that run on either no battery or a “hearing aid” size battery. In addition, the cost models currently presented to potential IoT customers are designed more for typical cell phone data plans than the occasional transfer of data.
And so we have new options arise…LPWANs. These networks were designed to work at distances measured in kilometers and have power consumption figures that allow for years, not days or weeks. LPWANs are optimized for the IoT where data rates are not the greatest concern—range, battery life and cost are. LoRaWAN, Sigfox and Weightless, among others, were all designed from the ground up to meet the direct needs of new IoT applications.
Now don’t think that the LTE camp (3GPP) is going to sit and watch potential customers move from their networks to the new kids on the block. Driven by a large group of international vendors such as Qualcomm, Huawei, Ericsson, Mediatek, etc., they are busily at work defining solutions using the current infrastructure, which is more in line with the needs of IoT applications.
LTE-M is one option and is designed to work with existing equipment installed in LTE networks. In other words, a cellular carrier like AT&T only has to upload new baseband software onto its base stations to turn on LTE-M, and it won’t have to spend any money on new antennas. LTE-M has a little higher data rate than the other options, NarrowBand IoT (NB-IoT), but LTE-M is able to transmit fairly large chunks of data, making it applicable to more of the projected IoT applications.
NB-IoT is not based on LTE, but instead on a DSSS modulation scheme similar to those looked at by Weightless or Neul, two other LPWAN alternatives. The advantage of NB-IoT is that the reduced complexity should lead to lower cost chips. The problem with NB-IoT is that it’s not part of LTE, so it needs to operate in a sideband using different software—a costly proposition that means a different radio needs to be deployed.
There are two key issues with both these technologies. First, they weren’t designed from the ground up for IoT, so they question, “Are they really the most cost and battery efficient methods of connecting all those new devices?” hasn’t been answered. Second, what if the operator camp fractures and deploys both? Now we have an even more fractured industry than we have today.
So back to the original question, are LPWANs a Band-Aid until 5G comes out? LPWANs have their own degree of uncertainty. Are they real? Can they handle large scale deployment? Will they be able to deploy infrastructure in a timely manner to really serve IoT applications? Do they meet expectations for cost / data rate / battery life? Are they too early with not enough applications and deployment to drive the desired cost?
Finally, let’s look at the potential answer to our original question in a more subtle way. If LPWAN networks can meet the needs earlier and better than LTE-M and NB-IoT, what should the carriers do? Do they still use these options, especially LTE-M, which makes use of the current infrastructure? Or, should carriers forgo the 3GPP options and make deals to resell the LPWAN solutions—or maybe just purchase Sigfox and LoRA providers outright?