NB-IoT Network Information

This chapter provides key information for customers developing new products and services using Telekom’s NB-IoT network. It contains all relevant information needed to take full advantage of the NB-IoT specific capabilities including the Power-Saving Features.

You may also visit our IoT Creators Support Forum to get access to further extensive support material, FAQ’s, and network coverage information. You may also ask individual questions that will be answered by our Telekom experts.

NB-IoT Connectivity

Licensed bands

NB-IOT like other 3GPP™ access technologies is deployed in licensed spectrum and can be accessed using NB-IoT compliant chipsets and modules.
On our Roaming page you can see details about PLMN-IDs and bands for different countries where you can connect our SIM to NB-IoT networks.

Certified modules and chipsets

Telekom already completed first certifications of a handful of LTE-M chipsets and modules, thereby enabling faster user time-to-market and connectivity quality.

The latest information on the certified chipsets and modules can be retrieved from here or drop a question in our forum.

APN configuration

Customers can access and use all NB-IoT features and capabilities over DT’s associated public APN’s using DT’s Global SIM.

Each local operator has its own public APN’s that are specific to their local GSIM offerings. For instance:

  • Public APN from Telekom Germany: “internet.nbiot.telekom.de” or “internet.m2mportal.de” (Comfort Connect) resp. “iot.telekom.net” (Smart Connect)
  • Public APN from T-Mobile Netherlands: “m2m.public.nl” resp. “iot.t-mobile.nl” (IoT Easy Connect)
  • Public APN in Magenta Telekom: “m2m.public.at

Customers with private APNs may also access NB-IoT over their private APNs, provided of course it is provisioned for NB-IoT connectivity.

Customers with private APNs for Classic M2M connectivity may also access LTE-M over these private APNs.

NB-IoT Power-Saving Featues

Long-Periodic Tracking Area Updates (Long-Periodic TAU)

The 3GPP™ feature Long-Periodic TAU, as defined in TS24.301, is used to periodically notify the availability of the IoT device to the network. The procedure is controlled in the device’s chipset via a periodic tracking area update timer (T3412).

The benefit of the Long-Periodic TAU is that the chipset protocol stack can remain longer in deep sleep mode before it must wake up to send a TAU message. .

In DT’s NB-IoT network, customers can specify the T3412 value to be applied in the network, this value must be set between 1 hour and 310 hours.

Power-Saving Mode (PSM)

The 3GPP™ feature Power-Saving Mode (PSM) helps NB-IoT devices conserve battery power and potentially achieve longer battery lives. Although it is possible for a device’s application to shut down its radio module or chipset to conserve battery power, the device would subsequently need to reattach to the network when the radio is turned on. This reattach procedure consumes energy that can become significant over time and generates unnecessary signaling. The alternative is to use PSM to disable parts of the chipset protocol stack and drop power consumption into the micro-Ampere range while remaining attached to the network.
When a device initiates PSM with the network, it provides two preferred timers:
• PSM Activity Timer (T3324): Time during which the device remains in idle Mode, listening to paging messages.
• Long-Periodic TAU Timer (Extended T3412, see paragraph above): Time between two Tracking Area Updates.
The time during which the IoT device module or chipset is in so-called “Deep Sleep Mode” is the difference between these two timers.
For the duration of this deep-sleep mode, the network retains the state information and the IoT device remains registered with the network. If a device awakes before the expiration of the time interval to send data, a reattach procedure is not required, and energy is saved.

In DT's LTE-M network, customers can specify the T3324 value to be applied in the network, this value must be set between 0 second and 11.160 seconds (186 min).

Extended Discontinuous Reception (eDRX)

The 3GPP™ feature Extended Discontinuous Reception (eDRX) is an extension of an existing LTE feature which has been introduced to enable IoT devices to further reduce their power consumption.

This feature has been designed for downlink-centric applications (e.g. actuators) that usually receive rather than send data and is found especially useful when it is uncritical for the device to be unreachable from several seconds to a few hours.

For such applications, it is required for a device to wake up and listen to the network at regular intervals for any incoming data (so-called paging procedure).

eDRX allows the time interval during which a device is not listening to the network to be greatly extended, thus strongly reducing the power consumption of the device while remaining reachable from the network.

eDRX can be used without PSM or in conjunction with PSM to obtain additional power savings. Although it does not provide the same level of power reduction as PSM, eDRX provides a good compromise between device reachability and power consumption.

When a device initiates eDRX in the network, it can provide two preferred timer values to the network:

• Paging Transmission Window (T PTW): Time during which the device performs the DRX procedure, which can accommodate between 4 and 16 paging reception slots.

• eDRX Cycle (T eDRX): Time between the start of two consecutive PTW windows.

Between those two times, the IoT device module or chipset enters a so-called “Sleep Mode” during which the receive path of the radio chipset is deactivated.

Below you will find an illustration of the use of eDRX in combination with PSM

In DT’s NB-IoT network, customers can specify the T PTW and T eDRX values to be applied in the network.

  1. T eDRX between 20,48s and 10485,76s (~175min)
  2. T PTW between 2,56s and 40,96s

Release Assistance Indication

The 3GPP™ Release 13 Early Release Assistance Indication feature (TS24.301) helps IoT applications further reduce device power consumption. This is achieved by allowing the IoT device to prematurely tear down the Layer 3 Radio Resource Control (RRC) bearer between itself and the eNodeB on the mobile network operator's radio access network (see the “RRC_CONNECTED” state in the previous illustrations).
This is done by including a Release Assistance Indicator IE when sending data to inform the network that no subsequent uplink or downlink data transmission (e.g. an acknowledgement or response from the application server) is expected.
By activating the Early Release Indication, the IoT device is able to go straight into the Idle Mode after data transmission and/or reception, thus bypassing the RRC_CONNECTED state (which is typically 20-30 seconds long). Depending on the chipset solution being used, this means that up to 50mA of current may be saved by the IoT device.

This feature however shall only be used when no additional uplink or downlink traffic is expected in the near-term, in order to prevent unnecessary Random Access Channel transmissions and RRC bearer reestablishments.
This feature is fully supported in all DT’s NB-IoT networks, except for some regional areas within the T-Mobile Poland network.

Data Packet Buffering

The drawback of using PSM or eDRX is that the IoT device cannot be contacted by the network while its module or chipset is asleep. However, in this hibernation time, downlink data sent to the device can be buffered by the network and delivered subsequently after the device has resumed from his deep-sleep mode. This feature is called “Data Packet Buffering” or DPB.
The number and size of the data packets being buffered is specific to the visited networks which the device is attached to.
As an example, in DT’s German NB-IoT network, up to 10 packets of each 1600 Bytes can be buffered until the device gets back in connected mode.

SMS support

Unlike in LTE-M, SMS (Mobile-Terminating and Mobile-Originating) is not supported natively over the NB-IoT network.

Coverage Enhancement Level (0/1/2)

Providing "Deep Indoor" coverage is an important aspect of NB-IoT, which is essential for IoT application requiring devices to be positioned in areas not readily accessible by 2G, 3G, or LTE coverage, such as in the basements of buildings, parking garages, etc. This is achieved by repeating Layer 3 (RRC, NAS) messages a predefined number of times, thereby increasing the probability of receivers to correctly receive and demodulate the message.
The NB-IoT standard supports three so-called Coverage Enhancement (CE)-Levels.
Each CE Level determines the number of times downlink and uplink messages can be repeated to reach devices in poor coverage and the number of repetitions in each CE-Level is predefined by the network.
The CE feature essentially increases the maximum coupling loss from 144dB to up to 164dB:
• +0dB vs. GSM signal with CE Level 0 (used when coverage is good)
• up to +10dB with CE Level 1 (with moderate repetitions)
• up to +20dB with CE Level 2 (with up to 128 repetitions)
Note that a higher power density (of 23 dBm) is also used in CE-Level 1 and CE-Level 2 instead of power control
All DT’s NB-IoT networks support all three Coverage Enhancement Levels 0, 1 and 2.

Roaming

In order for customers to take full advantage of NB-IoT’s features and benefits across borders, DT is working closely with its Roaming Partners to enable NB-IoT roaming across their respective networks.
This is achieved by exchanging information on the supported NB-IoT features and performing extensive tests of those features under roaming conditions.
As a minimum, it is currently ensured that the following NB-IoT key features are available within all Roaming Partner networks:
• Power-Saving Mode (PSM)
• Long-Periodic Tracking Area Updates (Long-Periodic TAU)
The latest list of DT’s NB-IoT roaming partners can be found in the IoT Creators documentation library under Roaming Network Info.
As additional features get implemented in its network, DT will provide full transparency of the support of those features by the Roaming Partner networks.

NB-IoT Feature matrix and associated parameters

As a summary, the table below provides an overview of DT’s NB-IoT key network features and associated parameters (*). This table will be enhanced as new features are launched and operator networks deployed within Deutsche Telekom’s footprint.

(*) Note: all parameters provided above are subjected to change and are therefore only indicative and provided without guarantee. This table shall be seen as a snapshot of DT’s network configuration and values may evolve over time.


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