LTE modem

The long term evolution (LTE) modem consists of baseband processing and RF parts, which together implement a complete 3GPP LTE release 13 (Rel-13) Cat-M1 and Cat-NB1 and LTE release 14 (Rel-14) Cat-NB1 and Cat-NB2 capable product.

Note: The LTE modem hardware supports Cat-NB2, but needs modem firmware support to get enabled. For information on Cat-NB2 feature support, see the nRF9160 Modem Firmware Release Notes included in the latest nRF9160 modem firmware.

As shown in the following figure, the parts of the LTE modem are:

The modem baseband and host processor provide functions for the LTE L1, L2, and L3 (layers 1, 2, and 3 respectively) as well as IP communication layers. Modem peripherals provide hardware services for the modem operating system and the modem secure execution environment.

Figure 1. LTE modem within the nRF91
LTE modem within the nRF91

Application and modem domains interact through the interprocessor communication (IPC) mechanism. The LTE modem is accessible to users through the modem API.

The application processor is the system master and is responsible for starting and stopping the modem. The LTE modem enables the clocks and power required for its own operation. The platform handles shared resources, such as clocks, and does not need user participation. In cases where a hard fault is detected in the modem, the application domain will perform a hard reset for the modem.

Note: For details regarding the modem API, see nRF Connect SDK API documentation and nRF91 AT Commands.

The key features of the LTE modem are:

Note: nRF9160 can run different modem firmware builds that define the final modem feature set in a specific nRF9160 based application.
Note: For details on services provided by the modem AT command interface, see nRF Connect SDK AT interface and nRF91 AT Commands.