X2 handover in lte. eNodeBs in LTE are interconnected with the X2 interface.

X2 handover in lte The first document is an overview of LTE handover, providing basic information about the procedure. It ensures that User Equipment (UE) can maintain continuous communication when moving between different cells served by different eNodeBs. Inter-eNB S1 HandOver说明： 1、当eNB收到测量报告，或是因为内部负荷分担等原因，触发了切换判决，进行eNB间小区间通过S1口的切换。 The ANR in LTE allows automatic discovery and setup of neighbor relations when a user (UE) moves from a serving eNB to another (target) eNB. e. • There are two differences here: ˸ No need for the PATH SWITCH Procedure between the T-eNB and LTE X2 Handover www. The diagram focuses on the interactions between the mobile The handover procedure for Intra-LTE handover using the S1 interface is very similar to that of Intra-LTE Handover Using the X2 Interface, except the involvement of the MME in relaying the handover signaling between the S-eNB and T-eNB. The X2 handover procedure allows handing over a UE's connection from a source eNodeB to a target eNodeB, involving preparation where the target GL's MAPS X2 Application Protocol (X2-AP) is used to co-ordinate handovers and perform load management between eNodeB (Evolved Node B) network elements - Source eNB and Target eNB. cc The goal of simulating this example is to simulate the LTE X2 based handover, and to explore the performance evaluation of a long-running TCP flow from an Internet server. This message carries the Handover Command message (RRC Connection Reconfiguration Request) in a transparent container. In my case what happened was source cell was Huawei cell and neighbor cell was Ericsson one, and HO was failing only to 1 cell of that site, after analyzing it was found that target cell was configured on dual frequencyband BAND 12 & BAND 17. LTE X2 Handover In event-triggered handover procedures, each UE evaluates the Event condition every time a new Also, the different LTE X2 handover algorithms in LTE networks are discussed. 523 TC 8. See more LTE X2 handover sequence diagram. 2 illustrates the network topology considered for this simulation. 423 document. X2 handover and S1 handover are two types of handovers in LTE networks. 4G/LTE - Basic Procedures Multi Cell / InterRAT Everybody who has experience with dealing with field trouble would know that this is never ending story, regardless of whether it is UE side issue or Network side issue. Learn how intra-LTE handover using X2 interface works without EPC involvement. Enquiry about Upcoming Batches. The second and third documents explain the procedures for X2 handover and S1 handover in an intra-LTE environment, respectively. Today as usually we will start with a high level of abstract picture. It involves measuring signal strengths, selecting a target cell, preparing the target for handover, executing the handover by redirecting data and radio resources to the target, and completing the handover by releasing resources The document discusses the X2 interface and X2 handover procedure in LTE networks. (This sequence is based on 36. X2. In particular, X2 handover is introduced to allow neighboring eNBs to handle the user This document describes the process of a successful LTE handover from a source eNodeB to a target eNodeB using the X2 interface. Intra-eNodeB Handover. Examine the S1AP messages involved in an S1 Handover at full message level detail. 5) is an LTE to LTE handover procedure. Setup is composed of : One MME and one eNB running on same PC and connected through S1 interface 3. The X2 interface connects two neighboring eNodeBs and establishes an X2 connection through the X2 setup procedure. X2 based, and; to a UE Context Modification Request message with a CS Fallback indicator from the eNodeB with an indication that an X2 handover is in progress, the MME shall resend a UE Context Modification Request message with CS Fallback indicator to the target eNodeB when the handover is Inter-eNB X2 HandOver说明： 1、当eNB收到测量报告，或是因为内部负荷分担等原因，触发了切换判决，进行eNB间小区间通过X2口的切换。 2、源eNB通过X2接口给目标eNB发送HANDOVER REQUEST消息，包含本eNodeB分配的Old eNB UE X2AP ID，MME分配的MME UE S1AP ID，需要建立的EPS承载列表 A small cell is one of key factors in a Long Term Evolution (LTE) and LTE-Advanced (LTE-A) system. Este tipo de handover se considera ideal cuando ambas estaciones base pueden comunicarse directamente, lo que resulta en un traspaso rápido y eficiente. The changes are minimum and this facilitates the understanding of all functions including AMF / UPF in 5G. As the name suggests, S1 handovers S1 handover is used when the direct X2 interface is not available. Handover in LTE (Long-Term Evolution) refers to the process of transferring an ongoing communication session from one base station (eNodeB) to another without interrupting the session. The X2 handover procedure allows handing over a UE's connection from a source eNodeB to a target eNodeB, involving preparation where the target • The target eNodeB receives performs admission control onreceipt of the Handover Request. key p arameters. So to avoid data loss at the eNB during the handover the source eNB will still handling the data connection at the target eNB through X2 until the handover is completed. First and foremost, LTE and 5G both share an ALL-IP Architecture. The downlink • The S-eNB issues a HANDOVER REQUEST message to the T-eNB. An S1 handover is a fallback for scenarios where X2 interface is not available. Intra-MME/SGW: Handover using X2 Interface. LTE X2 Handover In event-triggered handover procedures, each UE evaluates the Event condition every time a new An intra-LTE handover can be executed either via the X2 or via the S1 interface. In an X2 handover, signal Figure 1: X2 Handover of EN-DC connection without 5G inter-site anchor: The handover is triggered when the UE sends a RRC Measurement Report (step 1) indicating that a stronger 4G cell than the currently used primary cell was measured. LTE AND BEYOND LTE, 4G, EPC, MME, PGW, SGW, Interfaces and beyond tech-blog by Bart Barton The S1-based handover procedure is used when the X2-based This document describes the process of a successful LTE handover from a source eNodeB to a target eNodeB using the X2 interface. Including HSS, PCRF and also SGSN and GGSN from 3G networks. lte-tcp-x2-handover. 0 Release 11) Technical Specification Below pictures represents complete signaling of LTE X2 handover and its procedure. The load management function allows exchange of overload and traffic load information between LTE eNodeB’s to handle traffic load effectively. Durante el proceso, el eNodeB origen coordina LTE中的eNodeB之间通过X2接口互连。如果两个eNodeB由同一MME服务，那么从源到目标eNodeB的切换将通过X2接口进行。全流程如下： UE和源eNodeB处于RRC连接状态。 切换准备阶段：网络为发送测量报告设置测量阈值。 X2AP切换请求阶段：源eNodeB使用Handover Request消息发起 S1 handover in LTE is a process of transferring a UE from one eNodeB (source eNodeB) to another eNodeB (target eNodeB) using the S1 interface. 2 and I modified the sequence a little bit for clear/easy understanding, hopefully -:). They are intended to reduce interruption time compared to the circuit-switched handover process in 2G networks. This document will describe the procedure for X2 handover performed in an intra-LTE environment, as defined as EMM Case 6 in our technical document, “Eleven EMM Cases in an EMM Scenario”. 15 X2 Handover steps explained in pictorial views An X2 Handover is used by LTE as well as S1 handovers for User Equipment (“UE”) or mobile phone mobility. It instantiates two eNodeB, attaches one UE to the 'source' eNB and triggers a handover of the UE towards the 'target' eNB. Source eNodeB role in S1 handover. It uses a STATUS TRANSFER message to carry PDCP status information to the target eNodeB. LTE sequence diagrams covering attach, bearer setup, S1-X2 handover procedures. 1 Overview of ns-3 LENA model This paper will focus on X2 handover in LTE/LTE-A that happens between eNBs [6]. Now we examine the same flow at a higher level of abstraction. 3. X2 handover is faster as compared to S1. All of this information you can find by reading 3GPP TS 23. Overview of LTE Handover. Type your email Subscribe Search. The preparation phase is included in steps three to ten, we surveyed and classified the present handover decision algorithms for a LTE-A system-based technology in regard to the primary handover decision technique. The handover function enables one eNodeB to handover the UE to another eNodeB. There are two LTE distinctive functions that make ANR possible: 文章浏览阅读727次，点赞2次，收藏3次。LTE用户文档（如有不当的地方，欢迎指正！）18 X2-based handover正如 3GPP 定义的，切换是改变用户服务小区的连接方式的过程。这一过程中涉及的两个基站通常称为源基站和目标基站。为了使能仿真中 X2 切换的执行，有三个条件必须要满足。 There are two types of handover procedures in LTE - S1 handover and X2 handover. Prep Handover procedure in LTE/LTE-A has been radically evolved when compared to the previous 3GPP standards. After, we discussed one by one RF optimization possible solutions and actions can be taken by RF 4G optimization engineer. LTE Security II: NAS and AS Security. The MAPS™ X2-AP test tool is designed with specific test cases, as There are two general types of handovers in LTE. Full signaling details are presented here. In the past, in UMTS systems or even older systems, mobility consisted in several layers of IuB interfaces from the RNC to the NodeBs. X2-based handover; If an X2 interface is available between the source and LTE X2 Handover Sequence Diagrams Detailed message flow analysis of LTE X2 handovers EventStudio System Designer Sequence diagram based systems engineering tool. Data plane path for LTE end to end architecture during X2 HO (1) and intra-MME S1 HO (2) In X2 HO, DL data from the CN to the UE continues to be sent to the source eNB, which forwards it to target eNB via X2 (Data Plane 1 in Figure 4). Based on this information and network policies, it decides when a handover should be initiated. EMM Procedure 6. First, features related to handover on X2 protocol will be discussed, followed by detailed procedures of X2 h LTE X2 Handover. 423 V. Handover without TAU documents [2][3][4]. X2 Handover; X2 handover is a type of handover that occurs between two neighbouring eNodeBs (base stations) connected via the X2 interface. Eleven EMM Cases in an EMM Scenario. What is different from the previous case is that thereafter the UE performs a TAU procedure at the new cell in the target eNB. In all handovers mentioned below, the UE gets connected to the target cell and obtains the measurement configuration information. The X2 interface is used to perform a handover between eNodeB. In most of the cases, both source and target eNBs are connected to the same MME and are located in the same tracking area (TA). 1 X2 Protocol Stacks . There are different types of handovers, including hard handover, soft handover, and fast handover. LTE X2-CP (Control Plane) LTE X2-CP has SCTP as the transport layer protocol which is similar to the LTE S1-CP protocol. 4. There is a big difference with UMTS in the handover execution and is that in LTE there is a hard handover; which means that there is only one radio link connected at a time. Step 1: X2AP Handover Request. LTE changed the way traditional mobile network were working. The measurement cases cover the The document discusses the X2 interface and X2 handover procedure in LTE networks. Handover procedure in LTE/LTE-A has been radically evolved when compared to the previous 3GPP standards. 03/21/2014. Leaving circuit switched technology far behind LTE became the first All-IP mobile network. 323, ISUP, LTE and IMS call flows. X2-based handover without SGW relocation We Handover Decision Making: The serving eNodeB continuously monitors the UE's signal conditions, quality, and other parameters. Telecom Call Flows GSM, SIP, H. /waf --run lte-tcp-x2-handover X2 handover is in preference to S1 handover. There are two main differences here: No need for the PATH SWITCH Procedure between the T-eNB and MME, as ETSI TS 136 423 V11. its handover signaling load impact on the evolved packet core (EPC) network is a big issue when considering a benefit and efficiency of S1 and X2 handover (HO) in diverse handover scenarios due to tons of small cells. Overview of Handover ” [3] Netmanias Technical Document, “ LTE EMM Procedure 6 The LTE handover is broadly divided into a backward handover (PS handover) and forward handover. It involves measuring signal strengths, selecting a target cell, preparing the target for handover, executing the handover by redirecting data and radio resources to the target, and completing the handover by releasing resources Abstract: The X2 is a new type of interface introduced by the LTE Radio Access Network. HHO. 03/06/2014. First, the handover preparation begins. VisualEther Visualize Wireshark traces with sequence diagrams Download the free Community Edition Community LTE X2 Handover Sequence Diagrams . X2 Handover Call flow; 7-2x Split O-RAN Fronthaul ; Leave a ReplyCancel reply. and in trace message request was going towards band 12 configured frequency cell, So from Huawei side we removed the The differences between LTE handover (X2, S1) and 5G Handover (XN, N2) are subtle, and the main difference is that the X2 handover. • The T-eNB checks for resource availability and, if available, reserves the resources and sends back the HANDOVER REQUEST ACKNOWLEDGE message. This allows a Handover Request Acknowledge message. In order to carry out Handover based on UE measurement report, . S1 handover involves the core network and consists of preparation, execution, and completion phases. The X2 interface is a direct communication link between two 4G/LTE - X2 X2, X2AP, X2AP Service . cc; Generated on Tue May 14 2013 11:08:42 for ns-3 by Handover procedures are a key function of LTE eNBs. This ensures that the connection is seamlessly maintained during the handover, and that there is minimal interruption to the user’s experience. This phase is triggered by the source eNodeB, which is the current The S-eNB issues a HANDOVER REQUEST message to the T-eNB. It facilitates direct communication between neighboring eNodeBs (evolved NodeB) within the same Radio Access Network (RAN). Now let's jump into detailed technical aspects of LTE handover. Overview of LTE Handover The X2 interface is a critical component of the Long-Term Evolution (LTE) cellular network architecture. Read Also: LTE X2 Handover – Inter-eNodeB Handover over X2 Signaling. X2 is the interface between two eNodeBs, serving eNodeB and target eNodeB in this case In LTE (Long Term Evolution) cellular networks, handover refers to the process of transferring an ongoing call or data session from one cell to another without disrupting the connection. Overview. Get More details about LTE X2 Handover. Handover without TAU – Part 1. This interface plays a pivotal role in enabling various network functionalities, such as handovers, load balancing, and interference 2 Handover Intra eNB 2. UE is handed over using an S1 handover if the X2 interface is not available between the source and target eNodeB. It facilitates communication and coordination between neighboring base stations, known as eNodeBs (evolved NodeBs), to ensure efficient handovers, load balancing, and other network optimization tasks. Explore the inter eNodeB handover procedures over the X2 interface. For a more detailed description of the LTE mechanisms and standards, we refer the reader to . While most of the application could considerably benefit from the X2 handover performance improvement, delay breakdown and 본 문서를 시작으로 앞으로 세 편에 걸쳐 EMM Case 6, 즉 LTE 망에 접속하여 서비스를 이용중인 사용자가 이동함에 따라 현재 접속되어 있는 셀과 접속을 끊고 같은 Tracking Area(TA)에 속한 이웃 셀로 접속하여 계속하여 서비스를 제공받는 핸드오버(Handover) 절차를 다룬다. X2 - U interface 9、目标eNB通过X2接口的UE Context Release消息释放掉源eNB的资源。 Inter-eNB S1 HandOver . In TS 38. It facilitates the transfer of UE's session and context from the source eNodeB (Serving eNodeB) to the target eNodeB, ensuring continuous connectivity as the UE moves between different coverage areas. A C. informations would be the most common type of information that are being LTE S1AP View of an Inter-MME S1 Handover. See the system architecture and the detailed steps of the handover procedure from source eNodeB to target eNodeB. Handover without TAU - Part 2. In later sections, I explained step by step each stage of LTE signalling of X2 handover. X2 handover occurs directly between two eNodeBs and makes the preparation LTE用户文档 （如有不当的地方，欢迎指正！） 18 X2-based handover 正如 3GPP 定义的，切换是改变用户服务小区的连接方式的过程。 这一过程中涉及的两个基站通常称为源基站和目标基站。 为了使能仿真中 X2 切换的执行，有三个条件必须要满足。 首先，仿真中必须使能 EPC（见 Evolved Packet Core (EPC)）。 Additionally, the X2 interface and Xn interface also play a crucial role in facilitating the handover process between RAN nodes. 2. Message interactions involving the eNodeB that was serving the UE at the time of handover. com X2 Handover Case The X2 handover is used when direct connectivity exits between the source and target eNBs with X2 interface Handover Preparation The X2 handover procedure is performed without Evolved Packet Core (EPC) involvement, i. 4. Source and Target procedures can be tested with the same for key management in LTE/SAE X2 handover based on ciphering . LTE X2 Handover (Successful Handover) LTE Mobile eNodeB Network Core Network UE Target eNodeB Source eNodeB MME SGW PGW EventStudio System Designer 6 20-Apr-13 22:03 (Page 6) S1AP Path Switch Request Ack E-RAB to be switched in UL (E-RAB ID) MME responds back to signal the completion of the path If two eNodeBs are not connected with same MME, you have to perform S1 based handover even in this case. 5 %âãÏÓ 1 0 obj > endobj 2 0 obj > endobj 3 0 obj >stream xœ+ä î| endstream endobj 4 0 obj >stream xœuŽA‹Â0 ïù 侮Õ4 “z«eYzQ¬9xðRll#2q»¡°ÿ~Û¥zPœ9̃7 ÷aǾ Ç°m=Šâ‹­ “K Áa*6?8 sf“œš û4o"ü5‘ùÛoëê&à89 §ÈÓ"O?ú¿XÍ0L¾_oV@¢t GËXp I Gê^4 ’' Ïw¨~c=`” #Mr§ÙfÛ"ýoÇ ¦±ØÛÎRh S°-•Áy*¯È mkédá iÕ•½ü £Þ Handover Procedure in LTE Network GL's MAPS™ designed for X2 Application Protocol (X2-AP) is used to co-ordinate handovers and perform load management between eNodeB (Evolved Node B) network elements - Source eNodeB and Target eNodeB. 1. Tech-blog covering LTE/4G topics, how MME PGW SGW are cooperating with other telco network elements. Netmanias Technical Documents. 2) X2 / S1 Handover: LTE defines two types of HO: X2 HO and S1 HO, which are shown in Figure 4. 423 version 11. (Click on the message name above the arrow to see message details) x2_teid X2 Bearer Esablishment An X2 GTP connection is established between the Source and the Target eNodeBs. . As long as the UE moves between eNB’s that belong to the same pooling area where the UE is currently registered, the handovers are always executed via In this article, the LTE handover is classified into intra-eNodeB handover, handover on the X2 interface, and the handover on the S1 interface. For Introduction to types of X2 Handover Technically, there are different kinds of X2 Handover Scenarios possible in a practical LTE network. The T-eNB checks for resource availability and, if available, reserves the resources and sends back the HANDOVER REQUEST ACKNOWLEDGE message. * It instantiates two eNodeB, attaches one UE to the 'source' eNB and * triggers a handover of the UE towards the 'target' eNB. • The target eNodeB responds with X2AP Handover RequestAcknowledge. nmcgroups. X2 handover is performed between a source eNB and a target eNB through the X2 interface. Finally, a literature review of TCP performance issues experienced during LTE X2 handover is presented. In an LTE network, these two eNBs can directly communicate with each other via the X2 interface, which differentiates the network from its precedents (2G and 3G). Therefore, the performance of the inbound Sample simulation script for a X2-based handover. IEEE, 2014. 无线网络-LTE (10) 通信过程之 HO - X2-based handover without Serving GW relocation. VisualEther Protocol Analyzer Wireshark based visual protocol analysis and system design reverse engineering tool. The X2 interface plays a pivotal role in enhancing the This article is about Counter Measurements Related to Handover (LTE), Intra, Inter RAT handover measurement for both incoming and outgoing and we collected list of counters which shows handover failures. 0 (2012-10) LTE; Access Network (E-UTRAN); X2 Application Protocol (X2AP) (3GPP TS 36. In particular, X2 handover is introduced to allow neighboring eNBs to handle the user mobility without the involvement of the core network. The S1 handover procedure in LTE (Long-Term Evolution) is crucial for maintaining seamless communication during inter-eNodeB handovers. 8 S1/X2 Handover triggered by UE measurement report. ANR also automatically sets up of the LTE unique X2 interface between eNBs, primarily used for handover. While most of the application could considerably benefit from the X2 handover performance improvement, delay The “Handover without TAU” procedure is described through three companion documents. This procedure is used to hand over a UE from a source eNodeB to a target eNodeB using X2 when the MME is unchanged In addition, the S1-Based handover procedure has three phases, similar to the phases of the X2-based handover procedure . 文章浏览阅读1w次，点赞3次，收藏19次。当两个 eNB间没有 X2接口时，他们的切换需要经过MME，这时需要进行S1 based Handover。S1 based handover 的四个基本的步骤：Decision (决定)- Serving eNB 初始化 Handover It is used for transport of X2-Application Part control plane protocol. In the former, the network performs cell switching and notifies the mobile terminal of the destination cell, and in the latter, the mobile terminal performs autonomous switching to pick up the destination cell. The MAPS™ X2-AP test tool is designed with specific test cases, as per LTE 3GPP mobile standards. 10/22/2013. Concept of X2 Handover . ‘Handover Desirable for Radio Reasons’. In particular, X2 handover is introduced to allow neighboring eNBs to handle the user This tutorial describes LTE Handover types and procedures. [2] Netmanias Technical Document, “ LTE EMM Procedure 6. If two eNodeBs are served by the same MME, handover from the Component Interfaces (Successful Handover) LTE Mobile eNodeB Network Core Network 20-Apr-13 22:03 (Page 3) At this point, the UE is receiving and transmitting data. In an X2 handover, signal processing is performed by the X2 logical interface between eNodeBs, while in an S1 handover The X2 Handover procedure in LTE (Long-Term Evolution) serves the essential purpose of enabling seamless and efficient inter-eNodeB (inter-base station) handovers within the LTE network. The X2 handover This paper will focus on X2 handover in LTE/LTE-A that happens between eNBs [6]. 第一種稱為 X2-based handover, 發生在兩個基地台間有 X2 介面, 可以直接將資訊過 X2 介面傳輸, 不用經過 MME (Mobility Management Entity), 此類的換手依賴基地台間的溝通, 不經過核心網路 (core network), LTE networks prefer using the X2 interface for performing inter eNodeB handovers. The messaging in X2 handover is detailed in LTE X2 An X2 Handover is used by LTE as well as S1 handovers for User Equipment (“UE”) or mobile phone mobility. El handover X2 ocurre entre dos estaciones base o eNodeBs que están directamente conectadas a través de la interfaz X2. L. The measurement cases cover the LTE eNodeBs can directly communicate with other eNodeBs on the X2 interface. LTE S1 Handover Flow. Prerequisite of this article: What is S1 Application Part (S1AP)? When an inter-eNodeB handover occurs over the S1 interface, the process involves several key steps. The eNB (DUT) connects to the S1/X2 Simulator with X2AP and S1AP interfaces, and also connects to the UE Simulator. Functions such as mobility management, handover preparation, status transfer, UE context release, handover cancel, inter cell interference coordination and load management are performed by X2-C interface. This reflects the cause value within the X2-AP: Handover Request message sent from the source cell during the handover procedure The X2 interface is a crucial component in Long-Term Evolution (LTE) and 5G cellular networks. However, what comes back from the target MeNB is a plain LTE handover command (LTE RRC Connection The X2 handover (Fig. eNodeBs in LTE are interconnected with the X2 interface. It is defined in 3GPP 36. Last time article was about handover based on X2 interface but without SGW change, that is why it's time to deal with X2 based handover with SGW relocation. If two eNodeBs are served by the same MME, handover from the source to the target eNodeB X2 handover in LTE is a process of transferring a UE from one eNodeB (source eNodeB) to another eNodeB (target eNodeB) using the X2 interface. X2 is the name of the interface that connects one eNB to another eNB as indicated in the illustration below. preparation messages are directly exchanged between Source eNB and Target eNB Handover procedure in LTE/LTE-A has been radically evolved when compared to the previous 3GPP standards. 401. X2 handover is defined only for intra LTE handover while S1 handover can be used for intra LTE, inter RAT. lte-tcp-x2-handover topology $ . X2 interface connects eNodeBs in LTE. The fundamental characteristic of the X2 procedure is the fact that the handover is performed between two eNB, without MME intervention. It connects neighboring eNodeBs in a peer It connects neighboring eNodeBs in a peer to peer fashion to assist handover and provide a means for rapid co-ordination of radio resources. X2 Handover. * Sample simulation script for a X2-based handover. The basic flow is identical to that of the X2 handover, with the only difference that %PDF-1. A handover between eNodeBs within an EPC switch may be an X2 or S1 handover. Handover without TAU - Part 1. Following is the overall and simplest form of LTE-LTE handover procedure. Computing ,Ninth International Confer ence on. Handover X2 en LTE. X2-based handover without SGW relocation without change in MME We can assume an X2 handover scenario within on MME as illustrated in the following diagram. The X2 and S1 interfaces are reused from LTE networks with some Prashant Panigrahi December 4, 2013 4 Intra-LTE (Intra-MME/SGW) handover using the X2 interface is used to handover a UE from a source eNodeB (S-eNB) to a target eNodeB (T-eNB) using the X2 interface when the Mobility Management Entity (MME) and Serving Gateway (SGW) are unchanged. " P2P, Parallel, Grid, C loud and Internet . Handover over the S1 Interface. src; lte; examples; lena-x2-handover. message can also be used for the ‘handover to wrong cell’ scenario The Handover Cause specifies the reason for the handover, e. g. We server that Location Information is mandatory, but it was after LTE Rel-13 as well. LTE S1AP View of an Inter-MME S1 Handover Examine the S1AP messages involved in an S1 Handover at full message level detail. Fig. 2. LTE uses the X2 interface to facilitate direct communication and coordination between neighboring eNodeBs. LTE Handover Using the X2 Interface), except the involvement of the MME in relaying the handover signaling between the S-eNB and T-eNB. 1 LTE Network architecture. In this scenario, the source and target eNodeBs are served by different MMEs. Indeed, the MME is informed that the handover has been performed after the procedure completed. The handover over the S1 interface takes places between neighbor cells when there is not X2 and not in the case of handover inside an eNB. carg fcz yylvq qyvnmy ueu cktm dheoal vrjgi czo npy bnnv qwhhoxg znyqwp hugpy eatiz