Aug 01, 2015 lte x2 handover successful handover lte mobile enodeb network core network ue target enodeb source enodeb mme sgw pgw eventstudio system designer 6 20apr 22. Lte sim is presented to provide a complete performance verification of lte. The volte call flow procedure covers messages exchanged between ue or lte mobile, lte epc entities and ims entities. The ues also obtain uplink timing information from the initial handshake.
The x2 interface is used to perform a handover between enodeb. This procedure may relocate the mme andor the serving gw. A few excerpts from the presentation as shown below. Lte1060 tdd fdd handover duplex telecommunications. Qfi is nothing but, qos flow identifier which is used to idendify a flow. Start reading radio protocols for lte and lte advanced on the free kindle. Automatic, actual size, full width, 50 %, 75%, 100%, 125%, 150%, 200%. Considerations for inter rat mobility lte, lteadvanced and. Lte x2 handover messaging eventhelix com may 10th, 2018 eventhelix com design with sequence diagrams telecom. After the handover preparation in a handover over the s1 or x2 interface is complete, if the source enodeb does not receive any messages from the target and does not cancel the handover, the l. A tutorial on lte eutran and lte self organizing networks. The system with which lte compliant ue connects initially on the network is known as enb.
Dec 04, 20 in case of intra lte handover using x2 interface the ue is source enodeb and is in connected stated and the goal is to move the ue to target enodeb. The standards lte and lte advanced provided detailed descriptions for interrat mobility, both to and from other 3gpp and non3gpp technologies respectively, geranutran and cdma2000hrpd. In case of intra lte handover using x2 interface the ue is source enodeb and is in connected stated and the goal is to move the ue to target enodeb. A brief overview of cell reselection and handover procedures for 3gpp is provided below. The messaging in x2 handover is detailed in lte x2 handover presentation. Handover preparation the x2 handover procedure is performed without evolved packet core epc involvement, i. Source enodeb hands over ue data flow to the target enodeb over the x2 interface. S1ap handover request acknowledge eps bearer setup list, eps bearers failed to setup list, transparent container handover command the target enodeb responds back to the mme with a handover request acknowledge message. As the name suggests, s1 handovers take place over the s1interface. S1ap initial ue message attach request dcnr pdn connectivity request the nas messages from the ue are signaled to the core network via the initial ue message. In lte there are three different types of handover can be possible. View notes lte attachmessaging from informatic 6281 at university of utah. Dec 20, 2016 therefore soft handover can be dropped from the lte system.
When the ue has successfully accessed the target cell, the ue sends the rrc connection reconfiguration complete message crnti to confirm the handover, along with an uplink buffer status report to the target enb to indicate that the handover procedure is completed for the ue. Long term evolution signaling flows and tutorials for lte protocol layers. The mme and the sgw are involved during the handover procedure. This registration is known as the network attachment. Automatic, actual size, full width, 50%, 75%, 100%, 125%, 150%, 200%. Lte s1ap view of an intermme s1 handover examine the s1ap messages involved in an s1 handover at full message level detail. To address the issue of packet loss, an enhancement is introduced, in release 21. It brings in promising technologies such as semipersistent scheduling, transmission time interval tti bundling, and high. Ims is the 3gpp voice over ip solution which is being deployed in the lte networks as the voice solution. Target enodeb interfaces successful handover lte mobile.
Lte x2 handover messaging free download as pdf file. The x2 handover procedure is performed without evolved packet core epc involvement, i. Gsm call flow gsm originating call cell mobile station user mobile mobile network base stations nss bss msc vlr fixed. Intra lte handover via s1, if s1 handover is to be used lte53. This step is required so that transmissions from the mobile reach the base station at the precise time and with the correct frequency.
Lte attach procedure call flow the lte attach procedure call flow is a subject that may seem hard to understand. The call initiated by ue is known as mobile originated call or mobile originating call. The messages show a high level structure of the complex messages involved in the interaction. The frequency corrections correct for the doppler shift caused by the mobiles motion. Apply the time and frequency corrections adjust the frequency and timing based on the advice from the bss. This message carries the handover command message rrc connection reconfiguration request in a transparent container. How to do a handover in an office 12 steps with pictures. The first document is an overview of lte handover, providing basic information about the procedure. Aug 01, 2015 lte s1 handover s1 handover lte mobile enodeb network core network ue target enodeb source enodeb mme sgw pgw eventstudio system designer 6 17feb14 21. Lte x2 handover sequence diagrams x2 interface connects enodebs in lte. The simplest multi cell cases would be between two lte cells. Jul 02, 2016 here we look at the s1 handover that involves an mme change. The lte enb plays a key role in the endc session setup.
This sequence diagram describes the tale of three ues uea, ueb and uec that are powered on at the same time ues synchronize with the downlink channel by decoding the pss and sss signal. Every day, eventhelix and thousands of other voices read, write, and share important stories on medium. This sequence diagram describes the tale of three ues uea, ueb and uec that are powered on at the same time. Volte originating call volte call flow procedure volte mo. Target enodeb interfaces s1 handover lte mobile enodeb.
Sep 16, 2018 5ggnb role in nonstandalone access lte enb role. Find eventhelix software downloads at cnet, the most comprehensive source for safe, trusted, and spywarefree downloads on the web. Though lte does not have soft or softer handover it still maintains seamless mobility using hard handover. The user uses mobile phone or ue or mobile subscriber. We call this kind case as intrarat multi cell scenario.
A tutorial on lte eutran and lte self organizing networks son. A new s102 reference point or interface is defined between the lte mme node and the 3gpp 1xcs iws node. If two enodebs are served by the same mme, handover from the source to the target. Downlink nas transport authentication request mme initiates the authentication procedure. Considerations for inter rat mobility lte, lteadvanced. The lte son concept aims at minimizing the human involvement in network maintenance and operation. You are find about lte ebooks by tag lte at an introduction to lte. Request letter for school teacher handover my son result.
S1 interface based handover lte and beyond techblog. Information about active erabs, security keys is included in the message. Create default bearer request imsi, msisdn, apn, serving gw address serving gateway sends create default bearer request message to the pdn gw. In this scenario, the source and target enodebs are served by different mmes. Download as ppt, pdf, txt or read online from scribd. Lte x2 handover messaging identifier telecommunication. Target enodeb interfaces s1 handover lte mobile enodeb network core network ue target enodeb mme sgw eventstudio system designer 6 17feb14 17. X2ap handover request ecgi of the target cell of target enb, ueambr, ue security capability, kenb, erab to be setup erab id, qci, arp, s1 sgw teid the source enodeb initiates the handover with the handover request message. Radio protocols for lte and lte advanced pdf download.
S1 handover is used when the direct x2 interface is not available. Well first, the ue needs to register with the network to receive services that require registration. Noreply counter is incremented by 1 each time the source enodeb does not receive a handover request. Volte originating call volte call flow procedure volte. Some ue historical information uecell rrm related information, list of visited cells is passed in handover request message. In any cellular network whether it is gsm, cdma or lte there are two main parts viz. Lte sim encompasses several aspects of lte networks, including both eutran and eps. An interesting part of lte s1 handovers is the indirect tunnel that is established to carry the downlink data during the handover.
This article provides an overview of the lte radio interface, together with a more indepth description of its features such as spectrum flexibility, multiantenna transmission, and intercell interference control. Intra lte handover via x2, if x2 handover is to be used lte1170. The source enodeb initiates a handover by sending handover required message over the s1mme reference point. Then we focus on the self organizing networks son concept being implemented in lte and handover optimization techniques. Jul 10, 2015 an s1 handover is a fallback for scenarios where x2 interface is not available. When a ue is camped on the lte network, it would need to fallback to the legacy 2g3g networks when coverage or capacity dictates. Mar 15, 2015 x2 handover the source enodeb initiates the handover with the handover request message, including information about active erabs. Handover request letter sample universitas semarang. Radio protocols for lte and lte advanced pdf download download it once and read it on your kindle device, pc, phones or tablets. An s1 handover is a fallback for scenarios where x2 interface is not available. Interfrequency load balancing, if load balancing is to be used the ue must signal its support using feature group indicators fgi, 14, 25 and 30 see. S1ap messages involved in s1 handover are shown just before the message.
Lte s1 handover sequence diagrams s1 interface connects enodebs to the mme. Handover procedure an overview sciencedirect topics. The handover without tau procedure is described through three companion documents. It supports single and heterogeneous multicell environments, qos management, multiuser environments, user mobility, handover procedures, and frequency reuse techniques. In this case source and target cells are part of the same lte network. Ue, enodeb and mme interactions in an x2 interface. S1 interface based handover lte and beyond techblog on.
Mar 24, 2012 the s1based handover procedure is used when the x2based handover cannot be used. Lte random access procedure is used by the ues to initiate a data transfer. The x2 handover flow is shown in the following sequence diagram. Uea ueb uec enodeb lte random access procedure lte random access procedure is used by the ues to initiate a data transfer. More complicated probably the most complicated cases are the multi cell scenario among different technologies different rats. The second and third documents explain the procedures for x2 handover and s1 handover in an intra lte environment, respectively.
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