3GPP Enhancements Planned for 5G Release 17 Include RedCap, Coverage Improvements, Satellite Standards, and More

With 3GPP’s first release of the 5G NR (New Radio) standard (i.e. release 15) being commercialized, along with 3GPP’s July 2020 competition of Release 16, IoT professionals and others in the wireless industry are now looking at what updates are in the works for the next release of the 5G cellular wireless technology standard, Release 17. In particular, they are considering how Release 17’s new Reduced Capability (RedCap) device– sometimes referred to as NR Light – as well as its coverage improvements and new support for satellite communication standards might impact their long-term IoT business strategies.

Gus Vos, Chief Scientist for Technology Standards at Sierra Wireless, has been participating in 3GPP 5G standards meetings for years, working to ensure updates to the standards address the needs of IoT professionals and the IoT market. We recently talked to Gus about the 3GPP RedCap work item and other updates planned for 5G Release 17 that IoT professionals might want to keep an eye on.

Q: What are the updates in 5G Release 17 that you think will have the biggest impact on the IoT market?

A: Right now, I think the work being done on 3GPP’s newly approved RedCap work item will have the biggest impact on the IoT market over the next five years. The 3GPP standards group agreed in December 2020 to include it in 5G Release 17.

Q: What are 3GPP’s objectives with the RedCap work item?

A: The basic idea behind the RedCap work item is to define a new, less complex NR device for higher end IoT applications that offers faster data transmission speeds than Low Power Wide Area (LPWA) technologies like Narrowband IoT (NB-IoT) and LTE Machine Type Communication (LTE-M), while being much less expensive (though with slower speeds) than the multi-gigabit NR devices being deployed today.

To be very clear, a RedCap device specification is not designed to replace NB-IoT or LTE-M – 3GPP will continue to support these technology standards for IoT LPWA applications that need to be very low cost, with low power consumption, wide coverage, and high capacity (the 4Cs of LPWA).

In addition, the Redcap work item will strive to only make specification changes that will not require 5G base station (gNB) hardware changes and while providing RedCap devices with the same coverage as multi-gigabit NR devices, so no new cell sites will be required. The goal is to make Redcap devices easy to deploy, as mobile network operators (MNOs) will be able to provide connectivity to these devices via software upgrades to their existing NR network infrastructure.

Q: Why will RedCap devices cost less than other NR devices?

A: The overall idea is to design RedCap devices in a way that removes some of the bells and whistles of higher performance NR devices. By removing these bells and whistles, the RedCap study captured in 3GPP Technical Report (TR) 38.875 identified a potential cost reduction of approximately 3X (or a 65% reduction), assuming the NR devices were single band. However, since most commercial NR devices typically support more than 15 bands, we can expect the real-world cost reduction from RedCap to be larger than this.

For example, I estimate RedCap simplifications will reduce costs at a rate closer to 6X, with costs reductions even reaching 8X over the long term, when power amplifiers and flash storage start to be integrated into single chip designs. Of course, in engineering nothing comes for free, and using RedCap will result in some performance drawbacks -- especially speed. Another drawback will be higher cost per bit due a degradation in spectral efficiency since the RedCap devices will support fewer MIMO layers and fewer antennas than regular NR devices. These and other drawbacks will limit the use cases for RedCap devices. For example, it will be difficult to use RedCap devices for some new 5G enhanced Mobile Broadband (eMBB) applications that require very high data speeds and send a lot of data per month.

One of the ways in which RedCap reduces the cost of devices is that it enables companies to build devices with Half-Duplex Frequency Division Duplex (HD-FDD) communications. Unlike Full-Duplex FDD (FD-FDD) communications, where a device and cellular base station can transmit data to each other at the same time, with HD-FDD only the device or the cellular base station can transmit data at a specific time. Although HD-FDD can reduce data transmission speeds, it greatly simplifies (and thus reduces the cost) of the Radio Frequency (RF) design of multi-band RedCap devices.

3GPP has also agreed to reduce the cost of RedCap devices in others ways, including allowing them to use just one antenna for FDD bands (down from two), two antennas for most Time Division Duplex (TDD) bands (down from four) and by reducing their minimum bandwidth to 20 MHz (down from 100 MHz). The RedCap specification further reduces costs by not requiring support for multiple-input and multiple-output (MIMO), and by lowering the required downlink modulation to 64 Quadrature Amplitude Modulation (QAM) (down from 256 QAM).

All these changes will reduce the cost of RedCap devices, while also reducing their data transmission speeds and other performance capabilities. For example, for the simplest and least expensive RedCap variant, the peak speed will be around 35 Megabits per second (Mbps). Meanwhile for the most complex and expensive RedCap variant the peak speed will be around 170 Mbps. Both these speeds are much lower than the peak speeds of commercial NR devices, which today typically support peak rates of 5 gigabits per second (Gbps). However, RedCap devices’ peak data transfer speeds will be much faster than LTE-M Cat-M1 and NB-IoT Cat-NB2 devices, which in release 17 will have peak rates of 1,800 kilobits per second (kbps) and 250 kbps respectively.

Q: Will RedCap Devices be able to connect to LTE Networks?

A: A single mode RedCap device will not be able to connect to an LTE network which is why, at least initially, we will likely see RedCap devices be dual mode, supporting both LTE and NR technologies.

These dual mode devices will still be able to connect to wireless cellular networks even in areas with little to no NR coverage by using existing LTE networks for connectivity.

However, making a RedCap device dual-mode comes with a price. These devices will need to be FD-FDD since LTE is full-duplex. This, along with the need to include LTE in these devices, will make them more complex (and therefore more expensive) than NR-only RedCap devices.

Given the fact that NR coverage is likely to be extensive by 2023 in most cities and other populated areas, if you know that your device is going to be used in areas like this with strong NR coverage, you should consider using a single mode NR-only RedCap device.

Q: What other benefits do you think companies might be able to realize by using RedCap rather than LTE?

A: As mentioned above, adding a HD-FDD capability to NR is included in the RedCap work item’s objectives, and this HD-FDD capability will allow RedCap devices to be simpler, and thus less expensive to manufacture. However, this HD-FDD capability will also allow companies to build smaller devices and provide them other cost benefits as well.

For example, HD-FDD will enable RedCap devices to easily and cost effectively support lots of FDD bands, unlike LTE devices which do not support HD-FDD. This is because HD-FDD RedCap devices, unlike FD-FDD devices, will not need expensive duplexers.

Currently with LTE devices, (which are full duplex) companies that want to lower the cost and size of their devices by removing duplexers from them, can only do so by lowering the number of bands supported by these devices. This forces them to have different device types or stock-keeping units (SKU) with different band combinations for different locations, because they have to have one device SKU for a region that uses certain bands, and other devices SKUs for other regions using other bands. All these different device SKUs increase their logistical costs.

RedCap’s ability to use HD-FDD to support lots of FDD bands in a cost-effective way makes it possible for companies to have one global SKU for these devices without adding duplexers to them. This will help them simplify device procurement, manufacturing, and inventory management, as well as their customers’ worldwide IoT device deployments.

In addition, because RedCap HD-FDD devices do not need duplexers, these devices have the potential for higher silicon integration than LTE devices and high-performance NR devices. Duplexers are surface acoustic wave (SAW) filters, and are made using a piezo-electric substrate, which prevents them from being integrated into semiconductor-based chipsets. This means that HD-FDD RedCap devices are likely to have smaller form factors than current LTE and high-performance NR devices, as duplexers take up a lot of space.

Moreover, since the integration of the power amplifier and the removal of the duplexer will lower RF insertion loss, RedCap HD-FDD devices will use less power than LTE and high-performance NR devices. However, since it is unlikely large-scale silicon integration will occur in the first generation of RedCap chipsets, these power consumption and size advantages are probably more than 5 years away.

Q: What IoT use cases do you think RedCap might be particularly well-suited for?

A: RedCap is a good alternative for companies with IoT applications that might otherwise use LTE, because NB-IoT and LTE-M do not offer them the speed required for their application, while higher performance NR technologies are too expensive and provide them with more performance than they really need.

Specifically, RedCap would be good for IoT applications that use devices integrated into watches, clothes, and other wearables. It might also be a good choice for lower-cost tablets, routers, and other devices for IoT applications that need a bit more speed than LPWA technologies, but not all the performance advantages of NR.

RedCap will also benefit manufacturers, utilities, logistics firms and other companies with private NR networks who are considering the deployment of IoT applications that require higher data transmission speeds than LTE-M and NB-IoT can provide, but not the speed of high-performance NR devices. RedCap allows these organizations to lower their private network costs by using less expensive RedCap devices, rather than high-performance NR devices, for these IoT applications.

Q: Outside of RedCap, what other updates is the 3GPP 5G standards group working on for 5G Release 17 that IoT professionals should be award of?

A: 3GPP has agreed on a few updates to LTE-M and NB-IoT devices, with the main update increasing these devices’ peak data rates. Although the work is not yet finalized, LTE-M peak speeds should increase to approximately 1,200 kbps download (DL) and 1,800 kbps upload (UL), while NB-IoT peak speeds should increase to 250 kbps DL and 220 kbps UL.

3GPP is also continuing to make specification changes designed to lower power consumption for NR devices. In release 17, 3GPP is focusing on use cases in which NR devices send small amounts of data, with specifications defining new procedures for the usage of pre-configured UL resources, as well as a shortened initial access procedure.

3GPP also just agreed in Dec 2020, to make specification changes to improve coverage for NR. The 3GPP study, captured in TR 38.830, found that NR’s UL channels are bottlenecks to coverage. Therefore, 3GPP agreed to develop and specify several improvements to the UL NR data and UL NR control channels. Although this work is not yet finalized, these UL coverage improvements should add 5-6 decibels (dBs) of additional coverage to NR.

In addition, though it is still in the early stages, another exciting thing 3GPP is looking at for 5G Release 17 is a standards changes to NR, LTE-M, and NB-IoT that would make it possible for satellites to use these technologies for Non-Terrestrial Network (NTN) communications. The deployment of satellites that support NR, LTE-M, and NB-IoT would deliver huge increases in coverage, which would be useful for IoT applications that need to connect to equipment in remote areas -- in the middle of a jungle, desert, or arctic tundra -- hundreds of miles away from a cellular base station.

In addition, the recent drastic drop in the cost to launch low earth satellites, drop in the cost of these small low-earth satellites themselves, and low cost for LTE-M and NB-IoT edge devices, has made the overall cost structure for NTN services much lower than it was in the past. These lower costs, in combination with 3GPP’s new NTN standards, would make possible the deployment of new IoT applications that were previously cost-prohibitive or otherwise simply not possible before – including environmental monitoring applications that use large numbers of low cost, low power IoT devices to help track the impact of climate change.

Q: When do you currently expect all these updates to be finalized, and the 3GPP 5G standards group to freeze 5G Release 17?

A: The COVID-19 pandemic has led 3GPP to move out the schedule for 5G Release 17 nine months in total. Given this change, right now 3GPP is planning on freezing the 5G Release 17 in March of 2022.

Q: Given this timing, when can we expect to see commercial products introduced reflecting the updates in 5G Release 17?

A: I expect we'll see new products hit the market reflecting 5G Release 17’s enhancements as soon as mid-2023.

Q: What do you see as the key takeaways for IoT professionals as the work on 5G Release 17 moves forward?

A: I think the key takeaway is that 3GPP is not only trying to push cellular data transmission speeds to their limit, but is also looking at other ways it can expand the use of cellular communications for IoT applications. Whether it is the development of RedCap for mid-performance IoT applications, other performance enhancements to NB-IoT and LTE-M, or the development of NR, LTE-M, and NB-IoT standards for NTN communications, 3GPP is working to ensure that the world continues to build out the cellular connectivity technology companies need for IoT applications that transform how they do business.

Start with Sierra to learn more about how cellular technologies like NR, LTE-M, NB-IoT, and RedCap can help you unlock value in the connected economy.