ProDeveloperTutorial.com

Tutorials and Programming Solutions
Menu
  • Shell Scripting
  • System Design
  • Linux System Programming
  • 4g LTE
  • Coding questions
  • C
  • C++
  • DSA
  • GIT
  • 450 DSA Cracker
  • 5G NR
  • O-RAN

LTE Detach Procedure

prodevelopertutorial May 31, 2020

Detach Request can be initiated from UE or by the Network.

We shall learn both types of detach request in this chapter.

Below are the messages that are exchanged between UE and Network during detach procedure:

DETACH REQUEST
DETACH ACCEPT

UE initiated Detach Procedure:

Detach Procedure

Detach Procedure

UE will initiate detach procedure on following scenarios:

1. UE switched off
2. USIM is removed.
3. Detach for EPS service only

Steps involved in UE initiated detach procedure:

1. UE will send detach procedure by sending DETACH REQUEST message.

2. The Detach type IE included in the message indicates whether detach is due to a “switch off” or not.

3. The Detach type IE also indicates whether the detach is for EPS services only, for non-EPS services only, or for both.

4. If the UE has a valid GUTI, the UE shall populate the EPS mobile identity IE with the valid GUTI. If the UE does not have a valid GUTI, the UE shall populate the EPS mobile identity IE with its IMSI.

5. If the detach is not due to switch off and the UE is in the state EMM-REGISTERED or EMM-REGISTERED- INITIATED, timer T3421 shall be started in the UE after the DETACH REQUEST message has been sent.

6. Network will send DETACH ACCEPT message to UE and store the current EPS security context, if the Detach type IE is not “switch off”.

7. If it is “switch off”, then MME shall delete the current EPS security context.

8. The UE, when receiving the DETACH ACCEPT message, shall stop timer T3421.

9. On the first four expiries of the timer, the UE shall retransmit the DETACH REQUEST message and shall reset and restart timer T3421. On the fifth expiry of timer T3421, the detach procedure shall be aborted.

10. Network will not send DETACH ACCEPT if the Detach Type is “switch off”.

Network initiated Detach Procedure:

Detach Procedure

Network will initiate detach procedure for the following scenarios:

1. Detach the UE for EPS services or non-EPS services or both

2. Network will initiate detach procedure by sending DETACH REQUEST. It may include EMM Cause IE to specify the reason for detach request.

3. If the detach type IE indicates “re-attach required” or “re-attach not required”, the network shall deactivate the EPS bearer context(s) for the UE locally and enter state EMM-DEREGISTERED-INITIATED.

4. If the DETACH REQUEST message and the detach type indicates “re-attach required”, the UE shall deactivate the EPS bearer context(s). The UE shall then send a DETACH ACCEPT message to the network and enter state EMM-DEREGISTERED.

Detach Accept:

DETACH ACCEPT can be sent by Network or by UE.

* In case of UE initiated DETACH REQUEST, if the “Detach Type” IE is set to “Switch Off”, the network will not send “DETACH ACCEPT” to UE.

* If the network receives a DETACH REQUEST, with “Detach Type” IE is set to “normal detach”, the network will send “DETACH ACCEPT” to UE.

* If network initiated DETACH REQUEST, the UE shall send DETACH ACCEPT message, to indicate the successful completion of the detach procedure.

Reference: 3GPP TS 24.301

 

List Of Tutorials available in this website:

C Programming 20+ ChaptersC++ Programming 80+ Chapters
100+ Solved Coding QuestionsData Structures and Algorithms 85+ Chapters
System design 20+ ChaptersShell Scripting 12 Chapters
4g LTE 60+ ChaptersMost Frequently asked Coding questions
5G NR 50+ ChaptersLinux System Programming 20+ chapters
Share
Email
Tweet
Linkedin
Reddit
Stumble
Pinterest
Prev Article
Next Article

About The Author

prodevelopertutorial

Follow this blog to learn more about C, C++, Linux, Competitive Programming concepts, Data Structures.

Leave a Reply Cancel Reply

You must be logged in to post a comment.

ProDeveloperTutorial.com

Tutorials and Programming Solutions
Copyright © 2023 ProDeveloperTutorial.com
We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept”, you consent to the use of ALL the cookies.
Do not sell my personal information.
Cookie SettingsAccept
Manage consent

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.
CookieDurationDescription
cookielawinfo-checkbox-analytics11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional11 monthsThe cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance11 monthsThis cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy11 monthsThe cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.
Functional
Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features.
Performance
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
Analytics
Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.
Advertisement
Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.
Others
Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet.
SAVE & ACCEPT