Table of Contents
2.1 Unknown UE
2.2 Known UE
This document discusses initial attach, as defined as EMM Case 1 in our previous document, “Eleven EMM Cases in an EMM Scenario” . During this phase, a user turns on his device (UE) for the first time after subscribing to an LTE network/service, and attempts to attach to the network, sending an IMSI to the network (The initial procedure will be the same if the user is using an IMSI as his UE ID, even when he has previously attached to the network).
The initial attach procedure may vary depending on circumstances. It can be as in EMM Case 1, to be explained below, or as in EMM Case 11 (initial attach in another city), to be covered in the subsequent document later. Or it can be other types depending on whether or not a user (UE) kept the information used for his last attach to the network (hereinafter referred to as the “Last Attach Information1, or whether the network (MME) has information about the user, including UE ID, (hereinafter referred to as the “Last UE Context”2). So, this document (Part 1 of Initial Attach) will describe different initial attach types, and find out their characteristics and differences from one another. The subsequent document (Part 2) will focus on EMM Case 1, providing the related procedures in details.
This document is organized as follows:
Chapter 2 identifies different initial attach cases, and
Chapter 3 briefly discusses different initial attach procedures of each case, by listing the functions to be performed by MME.
This is what I need to understand call flows. Finally I am in right place.
Thanks for these excellent explanations. Recently I cleared an interview in which your tutorials played a major role. :)
Keep goind and enlighten the world with technology knowledge
Could you please provide your tutorials on LTE RACH & HARQ procedures ?
I think, the scene ii) the MME doesn’t have the valid Last UE Context of the UE can cover the scene iv) the UE was detached from other MME last time.
Thanks for this material.
Very helpful and easy to understand. Hope that you will upload some material about AS side.
Nice and simple..Please share more documents on LTE..
Your material is great! A good introdution before one dive into 3gpp spec
Do you maybe have call flow for the following case:
1.Subscriber is attached to 2-3G network.
2.Subscriber is not provisioned on HSS
3.Subscriber is using LTE capable phone.
Subscriber has active 2-3G PDP session. What is the scenario when UE attempts to handover to 4G in this case? Can Modify Bearer request from MME to SGW happen before successfull ULR/ULA (that obviously can not be successfull, as subscriber is not provisioned in HSS)?
Very good documentation. Easy to understand and to the point.
Had a question- Figure 2 Attache case 3. If the NAS security setup is already done with OLD MME, when the UE attaches to the new MME, How can the new MME process these messages and contact the old MME ? Wont the integrity check fail as the integrity setup of the UE was with old MME and not the new MME ?
Very useful and easy to understand the flow end to end...Kudos to the team.