What is LTE attach call flow?

What is LTE attach call flow?

Here’s the LTE Attach Procedure Call Flow, broken down into steps, derived by 3GPP. Step 1. The UE initiates the attach procedure by transmitting an attach request to the eNodeB. Step 2. The eNodeB derives the MME from the RRC parameters carrying the old GUMMEI and the indicated Selected Network.

What is attach type in LTE?

There are three different types of attach as listed below. EPS attach : indicate the attach for EPS services only) Combined EPS/IMSI attach : indicate the attach for both EPS and non-EPS services. EPS emergency attach : indicate the attach for emergency bearer services.

What is Guti attach?

When a UE initially attaches to an LTE network (e.g. turning on the UE), it sends its IMSI to the network for authentication to have itself identified. That is, the GUTI, the temporary ID that identifies the UE, can be changed into a new value even while the UE stays attached to the network.

What happens when a LTE UE is powered on?

When you power on the mobile device, in most case the device is under a circumstance where it sees many base station (eNode B) around it. In some cases UE would be surrounded not by the multiple basestation from one system operator but by the multiple basestation from multiple system operators.

What is an attach APN?

LTE Attach APN Configuration for MBIM Modems To establish a default EPS bearer with the network the device must request a PDP context activation during the LTE attach procedure, which requires Access Point Name (APN) specification. The device specifies a specific LTE attach APN.

What is EPS only attach?

The result “EPS only” indicates that the attach request for EPS services (only) has been successful but attach for non-EPS services or “SMS only” (if requested by the UE in the ATTACH REQUEST) has failed.

How UE is connected to eNodeB?

UE establishes the RRC Connection with the eNodeB. 2. The UE sends the ATTACH REQUEST message together with a PDN CONNECTIVITY REQUEST for the PDN (IP) connectivity on the established RRC Connection. As part of this, the eNodeB establishes the S1 logical connection with the MME for this UE.

Why Guti is used in LTE?

In LTE, the GUTI is the Globally Unique Temporary ID, and identifies the mobile device to the LTE network. By allocating a temporary ID to the device, the MME maintains the security of the IMSI (International Mobile Subscriber Identification) when transmitting over radio interface.

What is NAS message in LTE?

Non-access stratum (NAS) is a functional layer in the UMTS and LTE wireless telecom protocol stacks between the core network and user equipment. Examples of NAS messages include Update or Attach messages, Authentication Messages, Service Requests and so forth.

How cell selection happens in LTE?

Initial Cell Selection At each carrier frequency, UE searches for the strongest cell only. If the UE finds a Suitable Cell, it selects that cell to camp on. If the UE fails to find a Suitable Cell, it selects an Acceptable Cell to camp on.

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