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. Handover principles and handover measurements in lte. From old enb to new enb, with or without using new mmesgw, with or without using x2 interface, and so on. Following is the overall and simplest form of lte lte handover procedure. Handover in lte networks with proactive multiple preparation approach and. Handover in lte networks with proactive multiple preparation approach and adaptive parameters using fuzzy logic control.
The x2 handover procedure is performed without evolved packet core epc involvement, i. In the scenario described here serving gw is also unchanged. In the future, voice and tv phone services will also be provided in lte by way of handset terminals. The messaging in x2 handover is detailed in lte x2. Pdf high data rates in longterm evolution lte networks can affect the mobility of networks and their performance. When a ue is camped on the lte network, it would need to fallback to the legacy 2g3g networks when coverage or capacity dictates.
Handover procedure there are two types of handover procedure in lte for ues in active mode. 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. The handover without tau procedure is described through three companion documents. Selfoptimization of handover parameters in lte networks. Source enodeb interfaces successful handover lte mobile. 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. Home enbs henbs will be introduced in lte as part of the future g5 deployment. 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. S1 interface based handover lte and beyond techblog on. Oncethehocommandhasbeen processedby theue,it leaves the source cell and stops receiving data. 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. The legacy handover procedures in 3g and lte systems were originally designed for handovers between.
The maps x2ap test tool is designed with specific test cases, as per lte 3gpp mobile standards. Lte, voip, mobility, handover, x2, s1, mme assisted handover. 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 in lte lte telecommunication transmission. Before discussing about why lte skipped soft handover and only implemented hard handover, lets check the basic concept of softsofter handover. A dynamic timetotrigger ttt adaptation to enhance the switch decision timing in highly uncertain link states. 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. The tenb checks for resource availability and, if available, reserves the resources and sends back the handover request acknowledge message. We server that location information is mandatory, but it was after lte rel as well.
Load balancing via interfrequency handovers in lte networks. This tutorial describes lte handover types and procedures. 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. Visualether protocol analyzer wireshark based visual protocol analysis and system design reverse engineering tool. We suppose that ues handover from source cell1 to target cell2. The handover process is studied at the level of signalling. Pdf of the x coordinate of all users in one simulation 191. Performance of handover in long term evolution semantic scholar. Lte x2 handover sequence diagrams detailed message flow analysis of lte x2 handovers eventstudio system designer sequence diagram based systems engineering tool. Rake subreceivers used in 3g systems for combining multipath. Long term evolution lte is the next step forward in cellular 3g services. Hysteresis margin and load balancing for handover in. Handover procedure in lte network gl communications inc. May 23, 2014 when lte system was developed one of the big technical feature from umts softsofter handover was missing from the architecture.
Lte s1 handover s1 handover lte mobile enodeb network core. Pdf handover in lte networks with proactive multiple. This thesis will propose an lte 5g tight integration architecture, based on. 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. Interdomain handover technologies in lte for voice volte. The research topic of this thesis is handover from lte to 3g cellular networks, which is a high. Sep 12, 20 but what is special about lte tdd and fdd handover. More complicated probably the most complicated cases are the multi cell scenario among different technologies different rats. Aug 19, 2018 how is this different from the x2 handover.
Lte x2 handoverx2ho call flow procedure lte enodeb handover over the x2 interface enghindi duration. It uses same cellular network credentials for automatic authentication for example, usim or sim it obtains same ip. Hierarchical macrosmall cell deployment is one of the most promising technologies to enhance cell coverage and network capacity in 3gpp ltelteadvanced systems. Lte, load balancing, interfrequency handovers, colocated frequency band, lisbon. 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. S1 interface based handover lte and beyond techblog. Ueassisted measurements are made and reported by the ue to the network.
In softer handover, the nodeb can receive the signal in macro diversity with maximum ratio combining. Then the new merged buffer is given to the reassembly algorithm. In this approach, all the ho procedures at the ac are unnoticed by the rc network i. Long term evolution protocol overview nxp semiconductors. 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. Following is the overall and simplest form of ltelte handover procedure. Lte provides a packet switched model at the sap, but. Support for mbsfn combining of mbms transmission on multiple cells. The s1handover procedure is performed between two enbs without the x2 interface. When the ue detects radio link problems, it starts the rlf timer, a. The x2 interface is used to perform a handover between enodeb. Pdf heterogeneous networks hetnets are considered a promising cellular network architecture to provide services to the massive number.
In soft handover macro diversity with selection combining is. Handover between lte and 3g radio access technologies. Ims is the 3gpp voice over ip solution which is being deployed in the lte networks as the voice solution. 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. Leaving circuit switched technology far behind lte became the first allip mobile network. Pdf enhanced handover mechanism in long term evolution lte. Handover implementation in a 5g sdnbased mobile network. Pdf enhanced handover mechanism in long term evolution.
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. Lte changed the way traditional mobile network were working. 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. Now lets jump into detailed technical aspects of lte handover. The simplest multi cell cases would be between two lte cells. Handover in particular is more complicated in lte as lte.
Handover delay and interruption time extracted from hoto1119 figure 2. In particular, x2 handover is introduced to allow neighboring. This completes successful lte to wlanwifi handover. 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. The source enodeb initiates a handover by sending handover required message over the s1mme reference point. Mar 23, 2017 lte x2 handover x2ho call flow procedure lte enodeb handover over the x2 interface enghindi duration. 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. Two types of handover procedure in lte for ues in active mode the. There are many specific reasons why lte dropped altogether soft handover connectbeforebreak from the system design. In lte system, handover can be triggered when a ue detects that a neighboring cell offer better received signal strength from the serving cell. Selfoptimization of handover parameters in lte networks veronique capdevielle, afef feki alcatellucent belllabs, france email. Handover process in lte, lte handover tutorial teletopix.
Source enodeb interfaces successful handover lte mobile enodeb network core network ue target enodeb source enodeb sgw eventstudio system designer 6 20apr 22. The x2 handover is used when direct connectivity between source and target enbs exists. Sorry guys, today i dont have time to create abstract picture which we could use to start from. Moreover,we evaluate the proposedswitching and handover protocols by extending the evaluation methodology we have. In this context, one of the main goals of lte is to provide fast and seamless handover from one. 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 handover in cellular networks with femtocells ayaskant rath. Assumed cc management policies extracted from ynii11. Example scenarios for the deployment of rns in lte network.
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. It means this is mainly for ue side aspect of handover process. Like other mobile networks lte also have big challenges when it comes to mobility areas like handover and reselection. The handover procedure in this section is very similar to that in the previous section intralte handover using the x2 interface, except the. Pdf over the past decade, there have been great interests in cellular and fixed radio access technologies for. Handover mechanisms in 3gpp long term evolution lte.
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. Jun 03, 2017 lte enodebs can directly communicate with other enodebs on the x2 interface. 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. Analyzing x2 handover in lteltea konstantinos alexandris, navid nikaein, raymond knopp, and christian bonnet eurecom, biot, france email. Furthermore, as lte does not support soft handover there is no need for a centralized datacombining function in the network. The x2 procedure is used to handover a ue from a source henb to a target. The s1based handover procedure is used when the x2based handover cannot be used. Fast authentication during handover in 4g ltesae networks. To begin with, tdd and fdd are two slightly different duplexing modes of the same lte standard. The senb issues a handover request message to the tenb. We call this kind case as intrarat multi cell scenario.
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. Combining sgw and pdngw is also a valid implementation design. Optimising handovers in enterprise small cell lte networks. Efficient handover strategy for inbound mobility to lte. Performance comparison of dual connectivity and hard. Pdf handover enhancement for lteadvanced and beyond.
Lte x2 handover in eventtriggered handover procedures, each ue evaluates the event condition every time a new. Performance comparison of dual connectivity and hard handover. The differences between lte handover x2, s1 and 5g handover xn, n2 are subtle, and the main difference is that the x2 handover. In this case source and target cells are part of the same lte network. The enodeb sends measurement control messages to the ue giving reporting thresholds.
The second and third documents explain the procedures for x2 handover and s1 handover in an intralte environment, respectively. The s1 handover procedure is performed between two enbs without the x2 interface. Today we will be talking about handovers from eutran to utran, from 4g to 3g. Consequently, we assume the same x2based handover ho procedure as for lte standard 7. Apr, 2010 by lteworld in blog, handover, intra, intra eutran handover, sgw, eutran, enb, lte, mme. In soft handover macro diversity with selection combining is selected. Mar 30, 2012 few last articles were about handover in lte network. Just like an after action report, you can provide details of what has already been accomplished during your shift within the handover report samples. 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. Millimeter wave communications for future mobile networks. The user plane functions of the sgw and pgw will run on merged sdn.
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