DECT NR+ promises a low power, low latency and high speed mesh network operating in the DECT space of 1900MHz. It´s aimed at massive IoT and low latency use-cases. This article aims to ellaborate on the network protocol layers of DECT-NR+.

DECT-NR+ Example topology

The mesh consists of a Sink (gateway), a Router (relay), and a Leaf (node). When forwarding traffic from a leaf to the sync, the traffic is unicast until the sync. Traffic down to the leaf is flooded and relayed to any child relays. Once the traffic reaches a relay that has the leaf directly connected, the traffic is unicast. If the traffic is forwarded to relay with no further relays and the leaf is not attached, the traffic is dropped.

Network Protocol Layers

The following image is a representation of the network protocol layers. IPv6 is one choice, the application does not require to use IPv6 across the meshing network.

DECT NR+ Network Protocol Layers

Physical Layer

The physical layer utilises Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) with Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) in a Time Division Duplex (TDD) communication manner. BPSK, QPSK, and 16, 64, 256, 1024-QAM are the supported modulation schemes.

The physical layer can perform the following functions:

  • Error detection
  • FEC encoding and decoding
  • Hybrid ARQ soft-combining
  • Rate matching and mapping to physical channels
  • Modulation and de-modulation
  • Frequency and time sync
  • MIMO and TX Diversity
  • Beamforming

Medium Access Control Layer

The MAC layer supports the following functions:

  • Local Radio Control, responsible of radio resource coordination
  • Paging Transmission Control, controlling paging messages during radio resource coordination
  • Broadcast Control
  • Random Access Control
  • Beacon Scanning Control
  • Connection Configuration Control

The Data Link Control Layer

DLC Entity Set

There is an entity set for each radio link. There are 4 service types for an entity set, which are used depending on the QoS and application data format requirements.

Service TypeTransport Type
0Transparent
1Segmentation
2ARQ
3Segmentation of ARQ
Entity Set Service Types

Routing Service

The routing service supports three high level scenarios,

  1. Packet Routing from the radio device to the uplink with a special unicast address reserved for the backend.
  2. Packet Routing from the downlink to the radio device with either a unicast, multicast, or broadcast address
  3. Packet Routing between radio devices with either a unicast, multicast, or broadcast address with hop limited flooding.

The Convergence Layer

The convergence layer operates end-to-end between terminals. Intermediate nodes will not process the convergence layer payload. The convergence layer provides the following services:

  • Multiplexing services, identification and multiplexing of higher layer data.
  • Transmission services, segmentation and reassemble, retransmission, flow control and lifetime control, duplicate removal.
  • Security services, ciphering and integrity protection.

Want more information about 5G? Read more of our articles by visiting our 5G category. DECT-NR+ is an open standard managed via ETSI and supported by the DECT Forum

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