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ETSI has developed and published the first release of a new wireless communications standard that is designed for the European DECT band and equivalent bands worldwide. Additionally the standard was designed to meet a subset of the ITU IMT-2020 requirements that are applicable to IOT and Industrial internet of things. To meet the requirements of IMT-2020 DECT2020 must be teamed up with 3GPP technologies to cover all use cases but it is fully compliant with the requirements for Ultra Reliable Low Latency Communications URLLC and massive Machine Type Communication mMTC.

DECT-2020 NR has new capabilities compared to DECT and DECT Evolution
 * Better multipath operation (OFDM Cyclic Prefix)
 * Better sensitivity (OFDM and Turbocodes)
 * Better co-channel interference rejection
 * Better bandwidth usage (higher modulations specified and up to 8x8 MIMO)
 * Mesh deployment

The new standard has been designed to co-exist in the DECT band with existing DECT deployments. It uses the same Time Division slot timing and Frequency Division center frequencies and uses pre-transmit scanning to minimize co-channel interference. ETSI has developed and published the first release of a new wireless communications standard that is designed for the European DECT band and equivalent bands worldwide. Additionally the standard was designed to meet a subset of the ITU IMT-2020 requirements that are applicable to IOT and Industrial internet of things. To meet the requirements of IMT-2020 DECT2020 must be teamed up with 3GPP technologies to cover all use cases but it is fully compliant with the requirements for Ultra Reliable Low Latency Communications URLLC and massive Machine Type Communication mMTC. DECT-2020 NR has new capabilities compared to DECT and DECT Evolution The new standard has been designed to co-exist in the DECT radio band with existing DECT deployments. It uses the same Time Division slot timing and Frequency Division center frequencies and uses pre-transmit scanning to minimize co-channel interference.
 * Better multipath operation (OFDM Cyclic Prefix)
 * Better sensitivity (OFDM and Turbocodes)
 * Better co-channel interference rejection
 * Better bandwidth usage (higher modulations specified and up to 8x8 MIMO)
 * Mesh deployment

Applications
The wireless technology DECT NR+ (also called DECT-2020 NR in ETSI) was specifically developed to meet the requirements set by IMT-2020, which serves as the ITU-R framework for 5G networks. While IMT-2020 encompasses various applications, DECT NR+ primarily focuses on addressing the needs of local area deployments, whether indoor or outdoor, for two specific use cases: massive Machine Type Communication (mMTC) and Ultra-Reliable Low Latency Communication (URLLC) as defined for  5G networks application areas.

DECT NR+ offers flexibility in deployment by supporting different network topologies, namely Mesh,  Star, and Point-to-Point Link. The initial revision of the standard mainly targets several applications, including Smart Metering and Smart grid, Industrial internet of things, Building automation, and Professional audio.

For Smart Metering and Smart Grid applications, DECT NR+ provides features such as decentralized and autonomous networking capabilities, the ability to scale up to millions of devices within a single network, and compliance with the DLMS standard for electricity metering data exchange.

In Industrial IoT and Building Management, DECT NR+ caters to various use cases falling under the umbrella of Industry 4.0. These applications encompass robotics, monitoring and predictive maintenance, smart wearables (for safety), logistics, and packaging. NR+ supports these use cases through its low latency and high reliability, dedicated frequency band, and high density and scalability.

Regarding Professional Audio and PMSE applications, DECT NR+ offers the necessary features of low latency and high reliability. This makes it suitable for applications requiring real-time audio transmission and performance as required by professional audio systems.

One of the design objectives for the NR+ standard was to ensure its compatibility with various professional and consumer applications. Thus, it was designed to be agnostic and open, allowing for integration with a wide range of applications. As a result, future enhancements to the standard are anticipated to enable even more diverse applications.

Furthermore, a notable advantage of DECT NR+ is that it can operate in the dedicated DECT frequency band across Europe and many other parts of the world. This ensures that interference from other wireless systems is minimized, providing a reliable and efficient communication solution for all the aforementioned applications.

Technology
DECT NR+ technology is specified by DECT committee in the ETSI. The specifications for NR+ are called DECT-2020 in ETSI.

Topologies
NR+ supports 3 topologies :
 * 1) Mesh network
 * 2) Star network
 * 3) Point-to-Point Link

NR+ Mesh network is based on a clustered tree In all these network topologies the NR+ assumes that a device, called FT node, manages the radio resource usage in the cluster or link it controls.

The Point-to-point and star networks enable dedicated links, with reserved capacity for scheduled transmissions. A leaf node, called PT node in NR+, can ask for certain resource reservation for it when it associates to the FT node. As this reservation can be done only for the next link, Mesh networking with multiple relaying links in the path relies on random access channel usage where the devices needing to communicate compete for the access window defined by the FT node. This increases the communication delays in Mesh.

Co-Existence with Classic DECT
An important design criteria for NR+ was to co-exist with Classic DECT communications. This allows NR+ to use the DECT reserved radio bands 1, 2 and 9, in the frequency range of 1880-1930 MHz. DECT reserved radio bands are license free, but devices need to pass certification ensuring correct operation on the bands.

Mesh operation
The benefits of mesh topology and operation are robustness for changes or errors and coverage extension.

Robustness is the result of the autonomous decisions of the devices. There is no single point of failure. NR+ also supports having multiple gateway devices, called Sinks, connecting the NR+ mesh network to Internet. All the devices autonomously measure parent FT device's radio link quality, and can switch to another FT device if a better link or shorter route to sink is available. Similarly, if a parent device is not acknowledging messages, or is not sending the periodic beacon advertisement, a device will look for alternative parents. The mesh network heals itself in error situations and changes in the network.

Each device added to the network may act as a FT device, extending the network coverage. The sinks are configured first and start advertising the network in beacon messages. Devices scan radio channels, and associate to the parent they hear advertising the network and cluster. Associated devices can act as FT devices, and extend the network by selecting a channel with least traffic and start forwarding the network advertisement beacons. This extends the coverage for each FT device that joins the network.

FIXME FIGURE Mesh network -- 103 636-1 Fig 5.3.2-1

NR+ Protocol Layers
Overall description of the technology and protocol layers are provided in the DECT-2020 New Radio (NR); Part 1: Overview; Release 1 specification

FIXME Figure stacks, 103 636-1 Fig 6.1-2

Convergence Layer (CVG)
Convergence layer offers identification and multiplexing of the traffic of different applications and services using the NR+ communications. CVG operates end-to-end between the NR+ network nodes. It is analogous to ports in UDP or TCP protocol. Like UDP and TCP, CVG offers both unrealiable and reliable messaging services, datagram or flow control service and segmentation and reassembly for messages.

Convergence layer provides security with encryption and integrity protection of messages end-to-end in the NR+ network.

Data Link Control Layer (DLC)
Data link control layer is the message routing service for NR+ networks. Routing decisions are done in each device in the network, there is no central routing table. DLC routing operates in 3 modes:
 * 1) Uplink routing, to sink device: each node forwards message to parent
 * 2) Downlink routing: from sink to FT or PT device in the network. Messages are forwarded to each FT device in the network until the destination device's parent device can deliver the message to the destination device.
 * 3) Horizontal routing, between devices in the network with hop limited flooding

Unicast, multicast and broadcast routing is supported.

As the NR+ network has internal routing and addresses it can operate without Internet Protocol routing services. Internet protocols can be carried in NR+ networks.

Medium Access Control layer (MAC)
Medium access control main services are radio resource control and data transfer.

Radio resource control ensures the. To do this, FT devices periodically scan the radio channel they operate on, and map busy time slots measured to be in use assuming it is an on-going Classic DECT connection. FT devices allocate the channel access time for the child devices on free time slots, preserving error free communications on the busy slots time slots. Channel access allocations are sent in beacon messages to all devices in the cluster.

MAC layer also provides link scope encryption and integrity protection.

Physical Layer (PHY)
Physical layer uses Cyclic prefix version of OFDM as the core technology. The technologies provide well-known behaviour in challenging radio conditions.

PHY layer provides error detection to higher layers, Forward error correction and HARQ with soft combining. Received messages with errors are combined with re-transmissions, making it possible to decode correct message even if the re-transmission too contained errors.

NR+ radio can operate on frequencies below 6GHz. Standard defined speeds are up to gigabits per second. Radio implementations of course vary in the speeds achieved and frequencies supported.

Security
NR+ defines message encryption and integrity protection in both CVG and MAC layers. Encryption and integrity protection use own separate keys on the 2 layers. The encryption is security is based on AES with key length of 128 bits. Integrity protection is based on same algorithm and key length NR+ does not define the key distribution mechanism "the number of key-pairs and the key distribution is outside of the scope of the present document" although it has been studied.

Future work in ETSI
The DECT technical committee has started specification work for Release 2 of the standard in June 2023.

FIXME is there references? Do we want to say anything if no reference