When SigFox began in 2009, it disrupted the Third Generation Partnership Project (3GPP)—the technical body that standardizes cellular communications—by saying that there was an underserved market for devices that:
- Don’t have a lot to say.
- Need to be very inexpensive.
- Require very small power budgets.
- Require very long range.
SigFox was successful on this platform for a long time—but mobile operators with multibillion-dollar businesses aren’t too keen on startups eating into the market share. In 2014, Chinese cellular technology giant Huawei acquired U.K.-based Neul, an IoT company with some interesting intellectual property around long-range radio technology. Huawei has now partnered with Ericsson to push a standard called narrowband IoT (NB-IoT), otherwise referred to as LTE-M2.
Below, we’ll provide a broad overview of both Narrowband IoT and LTE-M1—an LTE-based alternative to NB-IoT.
Definitions, Differences, & Deployability
LTE-M1 is 3GPP’s response to the growing interest in the Internet of Things and low power, wide-area networks (LPWAN). It is an attractive option for those looking to deploy on current cellular networks, but need an option that is more resource-efficient. There are two innovations that help LTE-M1 improve battery life: LTE eDRX (extended discontinuous reception) and LTE PSM (power saving mode).
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Narrowband IoT (NB-IoT, or LTE-M2) is another 3GPP proposal, but it does not operate in the LTE construct. It is based on a DSSS modulation similar to the old Neul version of Weightless-W. Many big telecommunication giants—like Huawei, Ericsson, Qualcomm, and Vodafone—have been actively involved in putting this standard together. NB-IoT is designed to exist in one of three ways:
- In unused 200-KhZ bands that have previously been used for GSM.
- On LTE base stations that can be allocate a resource block to NB-IoT operations or in their guard bands.
While these differences are quite technical, they will make a big difference in determining what cellular operators will deploy which technology.
- In the U.S., both Verizon and AT&T will likely use LTE-M1, as both companies have poured billions into their LTE network. Therefore, they will likely have very little interest in something that isn’t LTE-based.
- Areas around the world with larger GSM deployments and less LTE will likely have more reason to turn to NB-IoT. In the U.S., carriers like T-Mobile and Sprint may eventually look toward deploying NB-IoT on existing GSM spectrum.
- NB-IoT has low power consumption when it’s operating. Nearly all IoT technologies save power when they aren’t operating, as they all “sleep” about the same. But when the modem is running and having to handle all the signal processing, the technologies with simpler waveform—like NB-IoT—will consume less power. Note: Not all chipsets for LTE-M1 will have the same power efficiency. For example, the Sequans monarch chip—which is dedicated to LTE-M1 and NB-IoT—doesn’t have to run Linux or do as much signal processing, making it far more power-efficient than refarmed silicon from Altair (which supports Cat-1 today and will support LTE-M1 in the future).
- NB-IoT will have low component costs. Chips that only support NB-IoT (as opposed to those that will also support LTE-M1) will be cheaper, as they’re simpler to create. A 200 kHz NB-IoT frontend and digitizer is much simpler than a 1.4 MHz LTE resource block. Also, processing OFDM in LTE requires more power than a simpler waveform like NB-IoT. Because most chip manufacturers seem to be building silicon to support both, this may be a moot point.
- NB-IoT can handle wider deployment coverages than LTE-M1. This is because the bitrates are less, and thus the link budgets are better. We have heard rumors that process gain improvements through repetitive pages at the network level for LTE-M1 may mitigate this advantage though.
- LTE-M1 has higher data rates. This allows for LTE-M1 to have a richer solution set, as it will offer the broadest range of cellular capabilities. And while LTE-M1 allows you to go up to really high data rates, you can also benefit from new architectures like LTE eDRX and PSM, which can help you benefit from the same power budget that NB-IoT or SigFox benefit from.
- LTE-M1 has gotten rid of a lot of complexity. For example, Verizon has a single spectrum across the U.S. for LTE, which has driven a lot of complexity out of LTE-M1 solutions for them. This allows a very simple frontend and antenna configuration.
- Deployability could become problematic for NB-IoT. Since NB-IoT isn’t a part of LTE, it either needs to operate in a side band using different software—which may be costly for carriers—or it needs to be deployed in deprecated GSM spectrum. And most carriers who support LTE aren’t going to reduce the number of resource blocks allocated to LTE handsets, because they’re big moneymakers for the carriers. The issue of deployment—and the complexity that comes along with it—is big question mark for NB-IoT.
- The front-end complexity of NB-IoT could actually be greater. Often, there’s not ubiquitous or country-wide 200-KhZ spectrum from GSM available for NB-IoT to be dropped into—which means modem frontends and antennas could become more complex than intended.
- There is potential for licensing costs with NB-IoT. Companies like Ericsson and Huawei may stick their hands out for licensing—so there is the potential for some unknown IPR risk here.
- There will be legacy licensing costs involved. By using LTE, you’re likely to have to pay IP licensing to the InterDigitals and Qualcomms of the world for access to the underlying innovations like OFDM.
- The question of power efficiency is up in the air with LTE-M1. Because eDRX and PSM have never been deployed, their power efficiency is hypothetical. So while the power saving features look great, you won’t know if the networks will let them operate as designed or if carrier-specific features will eat into the power budget.
Hypothetical Deployments For NB-IoT & LTE-M1
LTE-M1 will serve applications that LTE has never been used for before—from water meters to agricultural monitors and beyond. The unique part of LTE-M1 is that it can be extremely power-efficient and move 10 bytes of data a day, but also have access to move over a megabit per second. Therefore, LTE-M1 serves a very broad set of use cases.
The major question many are asking is: Is there a use case that exists that LTE-M1 doesn’t cover but NB-IoT does? The market is primarily the same, and some are speculating that there isn’t much there that SigFox hasn’t already capitalized on.
The hype for NB-IoT is spectrum-driven. There are loads of 200-KhZ GSM spectrum that isn’t being used, and proponents want to see NB-IoT deployed on it. Politically, NB-IoT is a way for players like Huawei and Ericsson—who haven’t been as prevalent in LTE IP development—to have more skin in the low power, wide-area game than they have previously.
If you need to go to market with your solution soon, NB-IoT and LTE-M1 aren’t yet available. The chipsets are only in the prototype stage and may not be rolled out for years. Even when the technologies are available, you’ll have to pay cellular operators to use them—and it hasn’t yet been disclosed what those costs will be.
But if you are looking to deploy a low power, wide-area network in a fixed area—say, in a building, plant, ranch, or factory—take a look at Symphony Link. To find out more how a LPWAN technology like Symphony may fit your use case, download the free white paper below.