S1 based inter eNB handover

S1 based inter eNB handover

In the previous chapter we saw X2 based inter eNB HO. In this chapter we shall learn S1 based HO. Scenarios where we need S1 HO. 1. If X2 interface is busy to perform HO. 2. If X2 interface is not present in between 2 eNB. …
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X2 based Handover

X2 based Handover

As we discussed in previous chapter, handover is based on 3 steps as below: 1. HO Preparation 2. HO Execution 3. HO Completion 1. HO preparation Consider the image below We have 2 eNB, source eNB and Target eNB. We have MME and SGW. SGW is …
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LTE Handover Events, Measurement Reports

LTE Handover Events, Measurement Reports

In this chapter we shall learn about 1. RSRP and RSRQ 2. Handover events 3. Introduction to handover. RSRP: Reference Signal Receive Power. It is the average power of Resource Element that carry cell specific Reference Signal.   RSRQ: Reference Signal Received Quality Both of the …
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SIP Request and Response Headers

SIP Request and Response Headers

Types of SIP Request INVITE : We will send INVITE request to invite a user to a call. ACK : Acknowledgment (ACK) message is sent in response to INVITE request. BYE : It is used to terminate a SIP session. CANCEL : Terminates an INVITE request. …
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SIP Registration and Invite Call flow

SIP Registration and Invite Call flow

In this chapter we shall see SIP Registration and SIP Invite call flow.   SIP REGISTRATION Call flow: User1 SIP Server | | | REGISTER M1 | |------------------------------>| | 401 Unauthorized M2 | |<------------------------------| | REGISTER M3 | |------------------------------>| | 200 OK M4 | |<------------------------------| | …
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VoLTE IMS KPI

VoLTE KPI Index

KPI stands for Key Performance Indicators. Based on KPI values we can access the performance of a network. KPI’s are based on mathematical calculations and hence it is an important aspect for checking the quality of VoLTE service.   1. TAS KPI’s This KPI will give …
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VoLTE INVITE Call flow

VoLTE INVITE Call flow

In this chapter we shall look at VoLTE IMS Invite Call Flow. Below image shows in brief of INVITE request if both UE are in same IMS Network Below image shows in brief of INVITE request if both UE are in same IMS Network Before UE …
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VoLTE IMS registration call flow

VoLTE IMS registration call flow

Basic Registration call flow is as shown in image below: Below image shows the sequence of steps followed for Registration process: First step involves in UE attaching to LTE Network. Once UE is attached to LTE network, UE needs to register with SIP server to make …
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IMS Architecture

IMS Architecture

In the previous chapter we had an introduction to VoLTE architecture. In this chapter we shall see in detail about IMS Core Architecture. A typical call will start from UE to eNB. From eNB it will go too SGW to PGW to Internet. Internet is where …
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