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Table of Contents 1. Introduction |
1. Introduction
This document describes the service request procedure defined as EMM Case 4 in our technical document, “Eleven EMM Cases in an EMM Scenario” [1]. This procedure is performed when an inactive UE in Idle state wishes to get activated to handle traffic when there is new traffic. New user traffic can be uplink traffic from UE or downlink traffic from the network to UE. The UE’s E-UTRAN resources (allocated by eNB) have been released, and the UE has been in ECM/RRC-Idle state. Thus, in order for the UE to receive or send user traffic, DL or UL, it needs to transmit to ECM/RRC-Connected state through the service request procedure so that E-UTRAN resources can be allocated again.
This document explains the service request procedure in an LTE network.
Chapter 2 categorizes different cases of service request depending on where new traffic is generated.
Chapter 3 and 4 describe distinct procedures required in each service request case. Finally,
Chapter 5 summarizes how information elements in EPS entities are different before and after the procedure.
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I know, in the step "15) EPS Session Modification (optional)" in Figure 3, when P-GW forwards a CCR message to PCRF, IMSI and UE’s IP address are sent as well to inform whose session is sent. How does the P-GW know to which user the session belongs to when no user ID is included in the Modify Bearer Request message that S-GW is sending to the P-GW?
In control plane, there is a GTP-C tunnel (per user) established between S-GW and P-GW. This tunnel (or user of this tunnel) is identified by a TEID. The TEID value is carried in the GTP tunnel header while control message is carried in the GTP tunnel payload field.
In the Step 15), when S-GW sends a Modify Bearer Request message to P-GW through this GTP-C Tunnel, the P-GW checks the TEID in the tunnel header and learns whose session it is.
Please explain me a scenario where UE is establishing a second dedicated bearer(ofcourse network initiated).
“At this time, the eNB allocates eNB UE S1AP ID, and includes it in the Initial UE Message sent to the MME. ”
eNB UE S1AP ID --》 eNB S1AP UE ID. Right?
Is there Any Timer defined for Inital Context Setup Request/ Response?
"SGW finds out at which MME the UE is registered" how?
Dear Netmanias team,
Thanks for your explanation, can you please explain what happens when the Service Request procedure is rejected. If possible please explain the behavior for different cause codes.
This site is the best
I have a question , After establishing the internet connection Ue is sending SR for three times since Network is ignoring the Service request . But according to spec it should send for five times .
What could be the reason here ?
Great Explanation with a diagram
HI,
Could you please explain when this scenario happens: After the S1 Setup Procdure between eNB and MME UE is sending Service Request(RRC Connection Request cause Mo-Data) and being rejected by MME since UE didn't do an Attach Request. UE never attached before.
How S-GW knows that the incoming data is for which MME/UE, means how S-GW decides the MME to send the DL data Notification. Please expaln thanks in advance
What kind of information related to UE subscription is kept in SPR ? Why PCRF does not use HSS for the same purpose ?
Excellent writeup. Thank you. One correction, Service request message is n ot sent encrypted; it is sent integrity protected, but NOT encrypted. See Clause 4.4.5 of 24.301, where the bullet says: unciphered, if it is any other initial NAS message (other than CP Service request which is sent partially ciphered). Ciphering is turned on when the service request procedure is successful, which imu, is SMC mode command (step 7) if authentication occurs, or after DRBs are setup (step 10).
hi Netmanias, one small question , what is difference bwteen seesion ID and tunnel ID and is session ID stored any where .. this queary is with respect to diagram 7 above...