DECT NR+ IoT applications FAQ

Friday 18 August 2023

We’re currently running a series of webinars on the subject of DECT NR+, an entirely new wireless technology emerging from the DECT lineage that started almost 30 years ago. The second webinar discussed applications for IoT that could use DECT NR+. The main application areas presented were smart grid and metering, building management and industrial IoT.
NR+ offers many benefits that include affordability, reliability and accessibility for smart grid operations.  Smart meters provide the electricity consumption information for smart grid management and stability purposes  The key benefits in smart buildings are multiple device types and application protocols that can operate in a common network. And for Industrial use cases the key benefit on top of those mentioned above is the support for low communication latency capability and the ability to adapt for the most suitable network topology.
DECT NR+ is based on state-of-the-art shared spectrum operation and automatic network formation which ensures minimal maintenance. The possibility of using multiple gateways to the internet enables large systems and capacity management, robust communication and high data rates. For industrial IoT applications it is important to have ultra–Reliable Operation. This is built on the NR+ Physical layer, offering high flexibility down to each leaf node and a high level of dynamic adapting and mesh networking.
The benefits and applications mentioned above were discussed in more detail in the DECT NR+ applications webinar. You can watch the recording here. During the webinar we also received a series of really interesting questions from the audience. Below you can find a recap of the questions and some key answers relating to this new standard for IoT.

What could be the maximal distance between 2 devices while maintaining a good connection between them?

The Maximum link distance is highly dependent on the environment, operating frequency and how devices are deployed, as well as the used TX power and transmission bandwidth. The factors affecting this are, for example, whether the signal can propagate in a line of sight (LOS) or non-line of sight condition (NLOS), the height of the devices from the ground and whether the signal needs to propagate through some material, e.g. a concrete wall. Typical values would be approximately the following, when using TX bandwidth of 1.728 MHz and 20 dBm Tx power: 80 meters (Indoor NLOS with concrete wall), 320 meters (NLOS, dense urban environment with devices at low level), up to 5-7 km with LOS and other devices deployed in a high level from the ground (macro cell deployment). All link distance measurements that have been done in different environments at 1,9 GHz frequency confirm the above general values and match well to known channel models.
 

Is it possible to use DECT NR+ for localization or Track & Trace ?

Yes, localization based on signal strength (RSSI) measurements is possible. Additionally, the standard does not prohibit implementing any further advanced localization methods. However, ETSI TC DECT has not yet concluded any study on those nor considered any specific signals or transmission formats to support some of the advanced localization solutions such as AoD or AoA. We believe ETSI TC DECT would welcome such work.
 

How is interference/coexistence handled between multiple collocated DECT NR+ networks (maybe from 2 users)?

Firstly, due to the defined physical layer packet structure, radio devices from one network can detect and decode radio identifiers of the other network (short Network Id and short RD Ids). This enables devices to detect interfering users as well as detecting the interference power. It can also identify the source of interference, its frequency, and the possible fixed periodicity. Based on this information it can locally decide the interference mitigation actions.
Secondly, each RD operating in FT mode, i.e. handling local radio resources, is set to determine a frequency channel that has the lowest interference (both time and received interference levels are considered) and select this frequency channel as its operating channel. So, when there is a less crowded frequency channel available, the other network will automatically move there. In case such a less crowded frequency channel is not available (both networks are already at lowest interfered frequency), the technology enables co-existence in terms of FT’s capability to detect other systems’ periodic interference and to make resource allocation decisions for both random access and scheduled access so that strong interference can be avoided.
Additionally, all random-access transmissions are using Listen Before Talk (LBT) with exponential back-off algorithm, so the device only transmits to a random access resource if the channel is free.
 

What are the bandwidths that will be possible with DECT NR+ Modules in the near future?

So far, we have seen announcements of chipsets that support bandwidths up to the width of 1.728 MHz.
 

With leaf-to-leaf communication, will it be possible for the 2 leaves to talk directly to each other?

Yes, DECT NR+ supports the so called "hop-limited flooding" for radio device to radio device communication. See more details in TS103.636-5.
 

Is it possible to have a TCP/IP connection in mesh topology?

This is not restricted by technology. However, as TCP tries to maximize possible throughput by using bandwidth delay product with slow start and congestion avoidance algorithms, and therefore it requires frequent feedbacks from the server to client - i.e. bi-directional traffic end to end - it is not the most suitable transport protocol, at least for when we are considering large scale IoT mesh networks. Therefore, the main assumption has been to use UDP with IP in mesh deployments. Further, TS103.636-5 supports end-to-end ARQ to ensure error free data delivery.
 

Will DECT NR+ software stack be provided with a license?

For DECT NR+ protocol software licensing you should contact Wirepas directly (https://www.wirepas.com/get-in-touch).
 

For an IoT application, power consumption is a key point. Roughly, what is the power consumption compared to, for example, LTE-M, NB IoT, and LoRa?

We are still early in the development process and so, for the moment at least, there are no final measurements to refer to. But for the Nordic Semiconductor implementation, the power consumption is comparable to the same solution with LTE-M.
 

Cybersecurity wise, how does DECT NR+ manage this?

DECT NR+ supports AES-128 ciphering, and CMAC (OMAC-1) integrity protection at the MAC layer which provides a link-specific security layer. Additionally, AES-128 and CMAC can be used at the CVG layer for end-to-end security, providing ciphering and integrity protection. Furthermore, the technology is open for any application layer-specific security scheme.
 

For Smart Grid, how well suited is NR+ for monitoring long linear assets like transmission lines? What kind of density of routing nodes would you recommend for reliable communication?

Regarding the expected link distances please refer to the answer above. The theoretical maximum number of hops from gateway to end device is 255. It is estimated that up to 30 to 50 hops could be expected in a very long chain type of mesh deployments which would be suitable in deployments for transmission lines and similar applications.
 

Can this technology be used for moving devices or is this mainly aimed for stationary devices?

It is designed to allow mobile devices as well as a mobile infrastructure.
 

As far as you know, is the 1.9GHz spectrum free and usable in all CE countries?

ERC Decision (94)03 and EU Council Directive 91/287/EEC designate the 1880-1900 MHz frequency band for DECT in the EU. ERC Decision (98)22 exempts DECT from individual licensing in the EU.
 
If you have more questions on how the standard can help you within the IoT, feel free to contact us.

Also check out the blog on DECT NR+ applications for audio solutions.

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