Two types of handover procedure in lte for ues in active mode the. A dynamic timetotrigger ttt adaptation to enhance the switch decision timing in highly uncertain link states. Ims is the 3gpp voice over ip solution which is being deployed in the lte networks as the voice solution. It uses same cellular network credentials for automatic authentication for example, usim or sim it obtains same ip. The difference is that a device uses two frequencies, one for communications to, and the other for communications from the network, in fdd mode, versus using only one frequency in tdd mode. Mar 30, 2012 few last articles were about handover in lte network.
Pdf enhanced handover mechanism in long term evolution. The research topic of this thesis is handover from lte to 3g cellular networks, which is a high. This completes successful lte to wlanwifi handover. Then the new merged buffer is given to the reassembly algorithm. This paper discusses the lte handover procedures that are standardized in 3gpp release 8 and describes a new lte handover. Connectivity and hard handover for lte5g tight integration in mmwave cellular networks supervisor master candidate michele zorzi michele polese university of padova cosupervisor marco mezzavilla new york university academic year 20152016 arxiv. Pdf handover enhancement for lteadvanced and beyond. Now lets jump into detailed technical aspects of lte handover. Just like an after action report, you can provide details of what has already been accomplished during your shift within the handover report samples. Selfoptimization of handover parameters in lte networks. 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. The s1handover procedure is performed between two enbs without the x2 interface. Support for mbsfn combining of mbms transmission on multiple cells. Lte x2 handoverx2ho call flow procedure lte enodeb handover over the x2 interface enghindi duration.
More complicated probably the most complicated cases are the multi cell scenario among different technologies different rats. Following is the overall and simplest form of lte lte handover procedure. The handover without tau procedure is described through three companion documents. Pdf handover in lte networks with proactive multiple. The enodeb sends measurement control messages to the ue giving reporting thresholds. Test measurement challenges and field environment test planning school of electrical engineering master. Analyzing x2 handover in lteltea konstantinos alexandris, navid nikaein, raymond knopp, and christian bonnet eurecom, biot, france email. Mar 23, 2017 lte x2 handover x2ho call flow procedure lte enodeb handover over the x2 interface enghindi duration. The user plane functions of the sgw and pgw will run on merged sdn. The handover process is studied at the level of signalling. Source enodeb interfaces successful handover lte mobile enodeb network core network ue target enodeb source enodeb sgw eventstudio system designer 6 20apr 22. Apr, 2010 by lteworld in blog, handover, intra, intra eutran handover, sgw, eutran, enb, lte, mme. Performance of handover in long term evolution semantic scholar.
Handovercommand message this message is sent by the mme to inform the source enb that resources for the handover have been prepared at the target side. When a ue is camped on the lte network, it would need to fallback to the legacy 2g3g networks when coverage or capacity dictates. From old enb to new enb, with or without using new mmesgw, with or without using x2 interface, and so on. This tutorial describes lte handover types and procedures.
The tenb checks for resource availability and, if available, reserves the resources and sends back the handover request acknowledge message. Softer handover softer handover is a special case of soft handover where the radio links that are added and removed belong to the same node b. This thesis will propose an lte 5g tight integration architecture, based on. Lte changed the way traditional mobile network were working. 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.
Millimeter wave communications for future mobile networks. The messaging in x2 handover is detailed in lte x2. In the future, voice and tv phone services will also be provided in lte by way of handset terminals. In particular, x2 handover is introduced to allow neighboring. In soft handover macro diversity with selection combining is. Leaving circuit switched technology far behind lte became the first allip mobile network. The x2 procedure is used to handover a ue from a source henb to a target. Handover in particular is more complicated in lte as lte. Selfoptimization of handover parameters in lte networks veronique capdevielle, afef feki alcatellucent belllabs, france email. The second and third documents explain the procedures for x2 handover and s1 handover in an intralte environment, respectively. Performance comparison of dual connectivity and hard.
The legacy handover procedures in 3g and lte systems were originally designed for handovers between. Handover in lte networks with proactive multiple preparation approach and adaptive parameters using fuzzy logic control. This article describes technologies for enabling smooth voice and tv phone interd\ omain handover especially during the radio access network migration phase when lte and 3g networks coexist and where both lte and 3g radiosnetwork domains will. Handover between lte and 3g radio access technologies. In softer handover, the nodeb can receive the signal in macro diversity with maximum ratio combining. The s1 handover procedure is performed between two enbs without the x2 interface. Efficient handover strategy for inbound mobility to lte. Lte long term evolution is a fourth generation cellular network technology that provides improved performance related to data rate, coverage and capacity compared to legacy cellular systems. Fast authentication during handover in 4g ltesae networks. Handover in lte lte telecommunication transmission. Load balancing via interfrequency handovers in lte networks. We server that location information is mandatory, but it was after lte rel as well.
Pdf heterogeneous networks hetnets are considered a promising cellular network architecture to provide services to the massive number. Example scenarios for the deployment of rns in lte network. While the lte handover procedures defined in release 8 provide mobility support, they may not be suitable for all scenarios and could result in unsatisfactory user experience even when compared to legacy 2g and 3g systems. The x2 handover is used when direct connectivity between source and target enbs exists. Lte s1 handover s1 handover lte mobile enodeb network core. Interdomain handover technologies in lte for voice volte. Late path switch only once the handover is successful, the packet core is involved.
Hysteresis margin and load balancing for handover in. There are many specific reasons why lte dropped altogether soft handover connectbeforebreak from the system design. An rlf occurs shortly after a successful handover from a source cell to a target cell or a handover failure occurs during the handover procedure. It means this is mainly for ue side aspect of handover process.
Assumed cc management policies extracted from ynii11. Lte x2 handover in eventtriggered handover procedures, each ue evaluates the event condition every time a new. Hierarchical macrosmall cell deployment is one of the most promising technologies to enhance cell coverage and network capacity in 3gpp ltelteadvanced systems. Home enbs henbs will be introduced in lte as part of the future g5 deployment. Handover procedure there are two types of handover procedure in lte for ues in active mode. The s1based handover procedure is used when the x2based handover cannot be used. The handover procedure in this section is very similar to that in the previous section intralte handover using the x2 interface, except the. Intra eutran handover is used to hand over a ue from a source enodeb to a target enodeb using x2 when the mme is unchanged.
Handover process in lte, lte handover tutorial teletopix. S1 interface based handover lte and beyond techblog. Handover principles and handover measurements in lte. Lte mobility enhancements 1220079 page 4 the target cell for handover, but not good enough for the ue to be able to decode the handover command from the source enb1.
May 23, 2014 when lte system was developed one of the big technical feature from umts softsofter handover was missing from the architecture. Lte x2 handover sequence diagrams detailed message flow analysis of lte x2 handovers eventstudio system designer sequence diagram based systems engineering tool. In this approach, all the ho procedures at the ac are unnoticed by the rc network i. Pdf of the x coordinate of all users in one simulation 191. The maps x2ap test tool is designed with specific test cases, as per lte 3gpp mobile standards. We suppose that ues handover from source cell1 to target cell2. Rake subreceivers used in 3g systems for combining multipath. In this context, one of the main goals of lte is to provide fast and seamless handover from one cell to another to meet a strict. Intralte handover intrammesgw as mentioned in the previous section, based on the measurement report from the ue, the senb decides to handover the ue to another enodeb tenb. Visualether protocol analyzer wireshark based visual protocol analysis and system design reverse engineering tool. Pdf over the past decade, there have been great interests in cellular and fixed radio access technologies for. Apr 10, 2010 apr, 2010 by lteworld in blog, handover, intra, intra eutran handover, sgw, eutran, enb, lte, mme intra eutran handover is used to hand over a ue from a source enodeb to a target enodeb using x2 when the mme is unchanged.
In particular, the lte base stations can provide a coverage layer for 5g mobile terminals, because they operate on microwave frequencies, which are less sensitive to blockage and have a lower pathloss. S1 interface based handover lte and beyond techblog on. However, latency of inbound mobility to the small cell is a critical obstacle to its deployment because it takes much time to detect an associated small cell due to its sparse deployment and to identify the target small cell. Sep 12, 20 but what is special about lte tdd and fdd handover. In this context, one of the main goals of lte is to provide fast and seamless handover from one. Before discussing about why lte skipped soft handover and only implemented hard handover, lets check the basic concept of softsofter handover.
This procedure may relocate the mme andor the serving gw. It uses same cellular network credentials for automatic authentication for example, usim or sim it obtains same ip address, as received in lte side, from wifi side. In the scenario described here serving gw is also unchanged. Jun 03, 2017 lte enodebs can directly communicate with other enodebs on the x2 interface. The x2 handover procedure is performed without evolved packet core epc involvement, i. Source enodeb interfaces successful handover lte mobile. Oncethehocommandhasbeen processedby theue,it leaves the source cell and stops receiving data. Moreover,we evaluate the proposedswitching and handover protocols by extending the evaluation methodology we have.
Long term evolution lte is the next step forward in cellular 3g services. Pdf enhanced handover mechanism in long term evolution lte. Sorry guys, today i dont have time to create abstract picture which we could use to start from. Ueassisted measurements are made and reported by the ue to the network. The source enodeb initiates a handover by sending handover required message over the s1mme reference point. Pdf high data rates in longterm evolution lte networks can affect the mobility of networks and their performance. A handover report contains the summation of all the work functions and responsibilities that an individual was able to execute within a particular time period. Long term evolution protocol overview nxp semiconductors. The x2 interface is used to perform a handover between enodeb. Aug 19, 2018 how is this different from the x2 handover. Nov 06, 2016 in fact, when a handover is beginning, an lte ue has to go into a compressed mode where it listens to its current cell for part of the time and searches for a new cell the rest of the time. Furthermore, as lte does not support soft handover there is no need for a centralized datacombining function in the network. The senb issues a handover request message to the tenb. Fast handover in cellular networks with femtocells ayaskant rath.
Consequently, we assume the same x2based handover ho procedure as for lte standard 7. Handover delay and interruption time extracted from hoto1119 figure 2. Like other mobile networks lte also have big challenges when it comes to mobility areas like handover and reselection. Lte, voip, mobility, handover, x2, s1, mme assisted handover. Therefore, the lte sae should be more secure than the 3g network and especially should have a strengthened defense against the current attacks from the.
In soft handover macro diversity with selection combining is selected. Lte, load balancing, interfrequency handovers, colocated frequency band, lisbon. Optimising handovers in enterprise small cell lte networks. Handover procedure in lte network gl communications inc. The simplest multi cell cases would be between two lte cells. Handover procedure in lte network gls maps designed for x2 application protocol x2ap is used to coordinate handovers and perform load management between enodeb evolved node b network elements source enodeb and target enodeb.
We call this kind case as intrarat multi cell scenario. To begin with, tdd and fdd are two slightly different duplexing modes of the same lte standard. In fact, when a handover is beginning, an lte ue has to go into a compressed mode where it listens to its current cell for part of the time and searches for a new cell the rest of the time. Lte provides a packet switched model at the sap, but. Following is the overall and simplest form of ltelte handover procedure. Handover in lte networks with proactive multiple preparation approach and.
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