INT-RNTI (interruption RNTI)

Last updated on Apr 20, 2023

INT-RNTI (Interruption Radio Network Temporary Identifier) is a Radio Network Temporary Identifier (RNTI) that is used in LTE (Long Term Evolution) networks to support the interruption of ongoing uplink transmissions by higher priority downlink transmissions. This is a critical mechanism for ensuring the timely delivery of important downlink messages, such as call setup and emergency messages, in a timely and efficient manner.

In this article, we will discuss what an RNTI is, how INT-RNTI works, and the importance of using INT-RNTI in LTE networks.

Radio Network Temporary Identifier (RNTI)

In LTE, a Radio Network Temporary Identifier (RNTI) is a unique identifier that is assigned to a User Equipment (UE) by the network during the initial connection setup process. The RNTI is used to identify the UE on the radio interface, and it is used for various purposes, such as paging, scheduling, and handover.

There are several types of RNTI used in LTE networks, including:

Cell Radio Network Temporary Identifier (C-RNTI): This RNTI is used to identify the UE within a cell.
Paging Indicator (P-RNTI): This RNTI is used to indicate that a paging message is addressed to the UE.
Random Access Radio Network Temporary Identifier (RA-RNTI): This RNTI is used to identify the UE during the random access procedure.
Temporary C-RNTI (TC-RNTI): This RNTI is used to identify the UE during a handover.

INT-RNTI

INT-RNTI is a special type of RNTI that is used to support the interruption of ongoing uplink transmissions by higher priority downlink transmissions. This is necessary because the radio interface in LTE is a shared medium, which means that multiple UEs may be transmitting at the same time.

In LTE, the network scheduler assigns radio resources to UEs for uplink and downlink transmissions based on their priority and quality of service requirements. However, there may be situations where a higher priority downlink transmission needs to interrupt an ongoing uplink transmission in order to ensure timely delivery of important messages.

For example, suppose a UE is transmitting a large file over the uplink, and during the transmission, an emergency call arrives with a higher priority. In this case, the network needs to interrupt the ongoing uplink transmission and allocate radio resources to the emergency call in order to ensure timely delivery of the call setup message.

To support this functionality, the network assigns an INT-RNTI to the UE during the initial connection setup process. When the network needs to interrupt an ongoing uplink transmission, it sends a downlink message to the UE with the INT-RNTI, which instructs the UE to stop the ongoing transmission and allocate radio resources to the downlink transmission.

How INT-RNTI works

The use of INT-RNTI in LTE networks is governed by the 3GPP (3rd Generation Partnership Project) specifications. According to the specifications, the INT-RNTI is assigned to the UE during the initial connection setup process, and it is used to support the interruption of uplink transmissions by higher priority downlink transmissions.

When a UE is transmitting data on the uplink, it continuously monitors the downlink control channel for incoming messages. If the network needs to interrupt the ongoing uplink transmission, it sends a downlink message with the INT-RNTI to the UE. Upon receiving the message, the UE checks the INT-RNTI and stops the ongoing uplink transmission. The UE then allocates radio resources to the downlink transmission and sends an acknowledgement message back to the network.

Once the downlink transmission is complete, the UE resumes the interrupted uplink transmission. This process is known as interruption and resumption, and it ensures that higher priority downlink transmissions are delivered in a timely manner without interrupting the ongoing uplink transmissions for longer than necessary.

It is important to note that the interruption of uplink transmissions using INT-RNTI is a controlled mechanism that is initiated by the network. This means that the network has complete control over which UEs are interrupted and for what purpose. Moreover, the network can prioritize the interruption of ongoing uplink transmissions based on the priority of the incoming downlink message.

In addition to the interruption and resumption of uplink transmissions, INT-RNTI is also used for various other purposes, such as:

Paging: The network uses INT-RNTI to page the UE when there is an incoming call or message.
Handover: INT-RNTI is used during handover procedures to identify the UE and allocate radio resources.
Group Call: INT-RNTI is used for group call services, which allow multiple UEs to participate in a call at the same time.

Importance of INT-RNTI in LTE Networks

The use of INT-RNTI in LTE networks is essential for ensuring the efficient and timely delivery of important downlink messages. Without INT-RNTI, there would be no mechanism for the network to interrupt ongoing uplink transmissions in order to allocate radio resources to higher priority downlink transmissions. This would result in delays and missed messages, which could be critical in emergency situations.

In addition to its importance in supporting interruption and resumption of uplink transmissions, INT-RNTI also enables various other features and services in LTE networks. For example, it is used for paging, handover, and group call services, which are essential for providing a seamless user experience and efficient use of radio resources.

In conclusion, INT-RNTI is a critical mechanism in LTE networks that enables the interruption and resumption of ongoing uplink transmissions by higher priority downlink transmissions. Its importance lies in its ability to ensure the timely delivery of important downlink messages, such as call setup and emergency messages, while minimizing the impact on ongoing uplink transmissions. Furthermore, INT-RNTI enables various other features and services in LTE networks, making it an essential component of the LTE radio interface.