Patent Publication Number: US-2022240129-A1

Title: Preemptive Handover Preparation and Tracking/Paging Area Handling and Intelligent Route Selection in a Cellular Network

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of copending U.S. patent application Ser. No. 16/431,647 filed Jun. 4, 2019, which is a continuation of International Application No. PCT/EP2018/000109, filed Mar. 22, 2018, which is incorporated herein by reference in its entirety, and additionally claims priority from European Application No. 17162641.9, filed Mar. 23, 2017, which is also incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present application is concerned with a concept for handovers in cellular networks, a concept for improved handling of tracking/paging/RAN notification areas for, for instance, user entities in inactive modes and a concept for enabling intelligent route selection in cellular networks. 
     Handovers of connections such as an ongoing call or a data session, or a user entity from one cell to another is an oft-occurring process and the control signaling used to establish such handovers consumes a considerable amount of the available radio and network resources and currently has an undesirable high latency for high reliability communications. Any reduction in the control signaling overhead and/or latency would be desirable. 
     Handovers take place in an activated mode of a user entity. Most of the time, however, user entities are not in an active mode or, differently speaking, most of the time there is no need for a continuous data communication for a user entity, but rather, discontinuously or intermittently, packets of a certain data session, are to be transmitted to/from the user entity. In such a case, continuously performing handovers might be unnecessary as long as a user entity is within a certain tracking/paging area. Merely when leaving the tracking/paging area, the user entity informs the cellular network on its new location or position. This entails, however, power consumption by the user entity and accordingly, it would be desirable to have a concept at hand which allows for reduction in this power consumption. 
     SUMMARY 
     An embodiment may have a cellular network supporting a preemptive preparation of a handover for a user entity. 
     Another embodiment may have a cellular network apparatus, configured to analyze a predetermined set of cells around a position of user entity with respect to a set of possible routes leading away from the user entity&#39;s position to determine a favorite route among the set of possible routes in terms of connectivity of the user entity; and provide for the user entity information about the favorite route. 
     Another embodiment may have a user entity for communication over a cellular network, wherein the user entity is configured to gain information on a predicted future route of the user entity and inform the cellular network on the predicted future route. 
     Another embodiment may have a user entity for communication over a cellular network, wherein the user entity is configured to manage a set of one or more preemptively prepared handovers. 
     Another embodiment may have a base station of a cellular network configured to determine a preliminary set of one or more target base stations of the cellular network based on a predicted future route of a user entity currently connected to the cellular network via the base station or triggered by the user entity entering a predetermined area, query each of the preliminary set of one or more target base stations regarding an accessibility of the cellular network via the respective target base station, receive, from each of the preliminary set of one or more base stations, an answer to the query, sending to the user entity a schedule indicating, for each of a set of one or more base stations within the preliminary set, a temporal access interval and one or more access parameters indicating that the user entity may access the cellular network via the respective base station during the temporal access interval using the one or more access parameters, cutting, upon receipt of an access confirmation from any of the set of one or more base stations, a connection to the user entity. 
     Another embodiment may have a cellular network configured to establish for a predetermined user entity a schedule of a time-varying tracking/paging area spanned by a time-varying set of one or more base stations, or to establish the time-varying tracking/paging area and provide the user entity with updates on changes of the time-varying tracking/paging area. 
     Another embodiment may have a cellular network configured to determine for a predetermined user entity a tracking/paging area depending on a predicted future route of a user entity. 
     Still another embodiment may have a user entity for communicating over a cellular network, wherein the user entity is configured to continuously check a schedule of a time-varying tracking/paging area whether the user entity leaves the time-varying tracking area and send a tracking/paging area update message to the cellular network in case of the user entity leaving the time-varying tracking/paging area. 
     Another embodiment may have a method for operating a cellular network having preemptively preparing a handover for a user entity. 
     According to another embodiment, a method for operating a cellular network may have the steps of: analyzing a predetermined set of cells around a position of user entity with respect to a set of possible routes leading away from the user entity&#39;s position to determine a favorite route among the set of possible routes in terms of connectivity of the user entity; and providing information about the favorite route for the user entity. 
     According to another embodiment, a method for communication over a cellular network may have the steps of: gaining information on a predicted future route of the user entity and informing the cellular network on the predicted future route. 
     Another embodiment may have a method for communication over a cellular network, having managing a set of one or more preemptively prepared handovers. 
     According to still another embodiment, a method of operating a base station of a cellular network may have the steps of: determining a preliminary set of one or more target base stations of the cellular network based on a predicted future route of a user entity currently connected to the cellular network via the base station or triggered by the user entity entering a predetermined area, querying each of the preliminary set of one or more target base stations regarding an accessibility of the cellular network via the respective target base station, receiving, from each of the preliminary set of one or more base stations, an answer to the query, sending to the user entity a schedule indicating, for each of a set of one or more base stations within the preliminary set, a temporal access interval and one or more access parameters indicating that the user entity may access the cellular network via the respective base station during the temporal access interval using the one or more access parameters, and cutting, upon receipt of an access confirmation from any of the set of one or more base stations, a connection to the user entity. 
     According to another embodiment, a method for operating a cellular network may have the step of: establishing for a predetermined user entity a schedule of a time-varying tracking/paging area spanned by a time-varying set of one or more base stations, or establishing the time-varying tracking/paging area and providing the user entity with updates on changes of the time-varying tracking/paging area. 
     According to another embodiment, a method for operating a cellular network may have the step of determining for a predetermined user entity a tracking/paging area depending on a predicted future route of a user entity. 
     According to another embodiment, a method for communicating over a cellular network may have the steps of: continuously check a schedule of a time-varying tracking/paging area whether the user entity leaves the time-varying tracking area and send a tracking/paging area update message to the cellular network in case of the user entity leaving the time-varying tracking/paging area. 
     Another embodiment may have a non-transitory digital storage medium having stored thereon a computer program for performing a method for operating a cellular network having preemptively preparing a handover for a user entity, when said computer program is run by a computer. 
     The present application provides, in accordance with a first aspect of the present application, a concept for improved handovers in a cellular network. This object is achieved by the subject matter of the independent claims of the present application in accordance with the first aspect of the present application. 
     In accordance with a second aspect of the present application, the present application provides a concept for an improved handling of user entities which are not in an active state. 
     One idea underlying some of the embodiments of the present application in accordance with the first and second aspects aims at achieving the above-identified improvements, by using a prediction of a future route of a user entity to improve the handover handling and/or the handling of non-active user entities, respectively. In particular, being able to exploit a predictive future route of the user entity allows for preemptive preparation of one or more handovers on the side of the cellular network. This, in turn, alleviates the control data overhead and/or reduces latency incurred by handovers. Such predictive future routes may also be advantageously used, for instance, in setting-up a time-varying tracking/paging area within which the user entity is allowed to stay without any need for keeping the cellular network updated on the exact cell within the tracking/paging area within which the user entity currently resides. This, in turn, may reduce the power consumption occurring in the user entity for indicating to the cellular network any departure from the tracking/paging area as the tracking/paging area may be adapted better to the route actually taken by the user entity. 
     A further idea which underlies some of the embodiments of the present application in accordance with the first aspect is the fact that a preemptive preparation of a handover enables the reduction in the amount of control signaling for handovers wherein, depending on these situations where such preemptive preparation of handovers is performed, the possible wastage of network resources which might be incurred by the preemptive preparation of the handovers in order to, for example, meet a certain promise that the user entity may access the cellular network at a predetermined temporal access interval using one or more access parameters at a certain base station of the cellular network, may be kept comparatively low. In particular, a preemptive preparation of handovers avoids, for a short-term or mid-term future, control signaling for handovers which will very likely occur with respect to a certain user entity. This, in turn, reduces control signaling at base stations for which the preemptive preparation of the handover has been performed, and reduces or avoids otherwise possibly occurring latency due to, for instance, the performance of handover related protocol signaling which then has to take place anytime just before the user entity seeks to move to the next cell. Naturally, this idea may be combined with the first idea so as to improve the selection of the set of base stations with respect to which the preemptive preparation of handovers is performed. Additionally or alternatively, the fact that the user entity enters a predetermined area may be identified as a circumstance where a preemptive preparation of a handover is favorably performed. For instance, such a predetermined area may be associated with a very high likelihood that the user entity will, in a near future, enter the cell of a predetermined other, i.e. target, base station and accordingly, performing a preemptive preparation of a handover towards this base station, may favorably reduce otherwise-occurring handover latency and/or control signaling associated with the handover. 
     Even additionally or alternatively, a further idea underlying some embodiments of the present application in accordance with the first and second aspects is the fact that some sort of scheduling of a tracking/paging area and/or handovers with respect to time, may alleviate the control signaling otherwise occurring if the scheduling would be replaced by a passive triggering of otherwise used tracking/paging area updates and handovers, namely, merely when needed. This idea may, obviously also be combined with the idea of exploiting a prediction of a future route of the user entity. 
     In accordance with a further aspect of the present application, the present application provides an improved concept for serving a user entity via a cellular network; namely, in a manner increasing the connectivity of the user entity. This object is achieved by the subject matter of the independent claim of the third aspect. 
     In particular, an idea on which embodiments of the third aspects are based, is that an analysis of a predetermined set of cells around a position of a user entity with respect to a set of possible routes leading away from the user entity&#39;s position to determine a—in terms of some predetermined criterion or criteria—favorite route among the set of possible routes in terms of connectivity of the user entity and providing for the user entity information about the favorite route, may be used to provide users of such a user entity with the opportunity to take this favorite route into account in planning their further journey; namely, in a manner taking into account the connectivity of the user entity and the time to come. The thus selected route could, for instance, be called a best connected/served route. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present application are described below with respect to the Figures, in which: 
         FIG. 1  shows a schematic block diagram illustrating a cellular network and a UE within the cellular network in order to illustrate a handover (HO); 
         FIG. 2  shows a temporal order of steps performed in a handover process; namely, an X2-based HO procedure according to [1] [6] wherein the diagram of  FIG. 3  distinguishes, by arranging the different entities participating in the HO procedure, side by side between the side or entity at which a certain step is performed or from whom to whom a certain signal is sent at a certain step, with a number of steps illustrated in  FIG. 2  being 12; 
         FIG. 3  shows a temporal order of steps in a manner similar to  FIG. 2  but here an S1 based HO procedure according to [1]; 
         FIG. 4  shows a schematic block diagram illustrating a cellular network and a UE communicating with the same, wherein  FIG. 4  also shows the UE as being currently connected to the cellular network via a source base station and as moving to other base stations of the cellular network which, thus, form target base stations with respect to which an handover is to be performed, wherein the cellular network, the UE and the base stations shown in  FIG. 4  may be embodied according to the present application; 
         FIG. 5  shows a schematic diagram illustrating the preemptive preparation of handovers realized by the entities presented in  FIG. 4  in accordance with an embodiment; 
         FIG. 6  shows a schematic block diagram illustrating a cellular network, a UE and signaling used in order to realize a preemptive handover preparation in an LTE framework; 
         FIG. 7  shows a table illustrating a possible signaling of preemptively prepared handovers in accordance with an embodiment; 
         FIG. 8  shows a sequence of steps involved in a preemptively prepared handover in a manner similar to the illustration used in  FIGS. 2 and 3 , in accordance with an embodiment of the present application; 
         FIG. 9  shows a schematic block diagram of a predictive handover (P-HO) architecture and message flow overview in accordance with an embodiment; 
         FIG. 10  shows a schematic block diagram illustrating an example for an out-of-coverage HO process; 
         FIG. 11  shows a schematic diagram illustrating the state machine of connection modes discussed in RAN2 for reduced signaling traffic wherein reference is made to R2-168345 [3]; 
         FIG. 12  shows a schematic diagram illustrating clusters of base station cells to tracking areas separated by tracking/paging area borders known from, for instance, [11]; in other words, non-access stratum (NAS) as depicted in  FIG. 12 ; 
         FIG. 13  shows a block diagram of a RN architecture according to [7]; 
         FIG. 14  shows a block diagram of a V2X broadcast architecture according to [8] as an example where embodiments of the present application might advantageously be used; 
         FIG. 15  shows a block diagram of a V2X eNB type roadside unit developed at the edge as an example of how a prediction of an HO process may be made faster; 
         FIG. 16  shows a schematic diagram illustrating a data split at the bearer level according to [11]; 
         FIG. 17  shows a schematic diagram illustrating a data split at the packet level according to [11]; 
         FIG. 18 a - b    shows a sequence of steps involved in a DC sequence chart according to [12], the sequence of steps being illustrated in a manner similar to the manner the sequence of step is illustrated in  FIGS. 2 and 3 ; 
         FIG. 19  shows a schematic block diagram of a cellular network, a UE and the involved base stations in accordance with embodiments of the present application where non-active UEs are efficiently handled using intelligent definition of the tracking/paging area; 
         FIG. 20  shows a schematic diagram illustrating the mode of operation of the entities involved in the scenery of  FIG. 19  in accordance with an embodiment where a time-varying tracking/paging area is used; and 
         FIG. 21  shows a schematic diagram illustrating the mode of operation of the entities involved in the scenery shown in  FIG. 19  in accordance with an embodiment where the tracking/paging area is defined depending on a predicted future route of the UE. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following, various embodiments of the present application are described. These embodiments relate to different aspects of the present application, namely the aspect of efficiently handling handovers, the concept of efficiently controlling tracking/paging areas within which user entities may efficiently reside in a non-active mode, and the concept of providing users of user entities with the opportunity to take the aim of a good connectivity into account in selecting the route to be taken in the time to come. 
     The description of these embodiments starts with an introduction and a technical overview with respect to the first concept relating to handovers. In general, a base station can be referred to as eNB (naming in the LTE context) or gNB (naming in the NR/5G context). In the following, it is not distinguished between these three terms. A user terminal/mobile user can be referred to as user equipment or user entity (UE). 
     There can be loss of connectivity during handovers in New Radio (NR) for 5G, especially for cases involving vehicular traffic, e.g. cars, busses, trucks, autonomous driving, drones and unmanned aerial vehicles (UAVs), planes, etc. The problem is threefold:
         1. The number of vehicles is increasing, causing increased signaling demand for handover processes (HOs),   2. The new mobility services, e.g. assisted driving etc., introduce new service requirements in terms of traffic models, e.g. reliability constraints like packet error rates (PER), throughput demands and packet sizes (e.g. high numbers of small control packets) as well as more stringent latency constraints,   3. State-of-the-Art handover (HO) is not optimized fully, since information wrt. localization (indoor and outdoor) as well as of traffic routes has vastly improved over the past years and enables track prediction of UEs connected to the cellular infrastructure. This is more the case for autonomous UEs with cloud connectivity, which have a tight communication link via wireless.
 
Significant HO overheads are caused when vehicles are rapidly moving across different cells during a given period. It would be favorable to improve the mobility services for vehicular/airborne UEs, which are in connected/active or lightly connected/inactive mode, especially in scenarios with vehicle-to-infrastructure (V2X), vehicle-to-vehicle (V2V) and Unmanned Aerial Vehicle (UAV) scenarios.
       

     These services shall be enhanced in order to improve performance and enhance reliability of the handover (HO) procedure through signaling procedures that specifically introduce prediction and improve the reliability of UE context transfer to the target eNBs during the predictive HO procedure. 
     The current HO procedures in LTE are designed to cater for scenarios where a UE transitions from a source eNB  12  to the target eNB  14  as indicated in  FIG. 1  or from a cell  16  of eNB  12  to a cell  18  of eNB  14 . The focus of this invention is on Intra-RAT HO procedures while Inter-RAT mobility is not precluded. 
     There are two types of HO procedure in LTE for UEs in active mode:
         1. the X2-handover procedure,   2. the S1-handover procedure.
 
1. X2-based HO: The X2-handover procedure is illustrated in  FIG. 2  and is normally used for the intra-eNB handover. The handover is directly performed between two eNBs via an X2 interface  20  connecting both eNBs  12  and  14 , which makes the preparation phase quick. The MME as part of a core network  24  of the cellular network  24  which also comprises the eNB  12  and  14  is only informed at the end of the HO procedure  26 , once the HO is successful in order to trigger the path switch. Release of resources at the source side is directly triggered from the target eNB. The X2-handover procedure  26  consists of 3 basic phases:
   1) Preparation phase  26   a  (steps  4 - 6 ),   2) Execution phase  26   b  (steps  7 - 9 ),   3) Completion phase  26   c  (after step  9 ).
 
An overview of X2-based handover procedures based on  FIG. 2  [ 6 ] is outlined below:
       1. The Source eNB  12  contains the UE context which consists of information related to area roaming and access restrictions and was initially provided during the connection establishment or Tracking Area (TA) update.   2. The UE measurement procedures can be configured via the SeNB and assist with the UE&#39;s connection mobility.   3. The Source eNB receives a measurement report from the UE as well as Radio Resource Management (RRM) Information to enable whether a HO decision is performed.   4. The source eNB issues a HO REQUEST message to the target eNB passing information entailed to prepare the HO at the target side. This information may include UE X2 signaling context reference at source eNB, UE S1 EPC (Evolved Packet Core) signaling context reference, target cell ID, K eNB* , RRC (Radio Resource Control) context including the C-RNTI (Cell-Radio Network Temporary Identifier) of the UE in the source eNB, AS (Access Stratum)-configuration, E-RAB (E-UTRAN Radio Access Bearer) context and physical layer ID of the source cell+short MAC-I (Message Authentication Code) for possible RLF (Radio Link Failure) recovery. UE X2/UE s1 signaling references enable the target eNB to address the source eNB and the EPC. The E-RAB context includes RNL (Radio Network Layer) and TNL (Transport Network Layer) addressing information, and QoS (Quality of Service) profiles of the E-RABs.   5. Resource setup primarily configures resources to query if the resources can be granted by the target eNB and also performs admission control on the received E-RAB QoS information to increase likelihood of a successful HO. “The target eNB configures the used resources according to the received E-RAB QoS information and reserves a C-RNTI and optionally a RACH preamble. The AS-configuration to be used in the target cell can either be specified independently (i.e. an “establishment”) or as a delta compared to the AS-configuration used in the source cell (i.e. a “reconfiguration”)”.   6. “The target eNB prepares HO with L1/L2 and sends the HANDOVER REQUEST ACKNOWLEDGE to the source eNB. The HANDOVER REQUEST ACKNOWLEDGE message includes a transparent container to be sent to the UE as an RRC message to perform the handover. The container includes a new C-RNTI, target eNB security algorithm identifiers for the selected security algorithms, may include a dedicated RACH preamble, and possibly some other parameters i.e. access parameters, SIBs, etc. The HANDOVER REQUEST ACKNOWLEDGE message may also include RNL/TNL information for the forwarding tunnels, if applicable. NOTE: As soon as the source eNB receives the HANDOVER REQUEST ACKNOWLEDGE, or as soon as the transmission of the handover command is initiated in the downlink, data forwarding may be initiated.”   7. “The target eNB generates the RRC message to perform the handover, i.e. RRCConnectionReconfiguration message including the mobilityControlInformation, to be sent by the source eNB towards the UE. The source eNB performs the integrity protection and ciphering of the message. The UE receives the RRCConnectionReconfiguration message with parameters used (i.e. new C-RNTI, target eNB security algorithm identifiers, and optionally dedicated RACH preamble, target eNB SIBs, etc.) and is commanded by the source eNB to perform the HO. The UE does not need to delay the handover execution for delivering the HARQ/ARQ responses to source eNB.”   8. “The source eNB sends the SN (Sequence Number) STATUS TRANSFER message to the target eNB to convey the uplink PDCP (Packet Data Convergence Protocol) SN receiver status and the downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies (i.e. for RLC AM (Acknowledge Mode)). The uplink PDCP SN receiver status includes at least the PDCP SN of the first missing UL SDU and may include a bit map of the receive status of the out of sequence UL SDUs that the UE needs to retransmit in the target cell, if there are any such SDUs. The downlink PDCP SN transmitter status indicates the next PDCP SN that the target eNB shall assign to new SDUs, not having a PDCP SN yet. The source eNB may omit sending this message if none of the E-RABs of the UE shall be treated with PDCP status preservation.”   9. When the UE has successfully accessed the target cell, the UE sends the RRCConnectionReconfigurationComplete message (C-RNTI) to confirm the handover, along with an uplink Buffer Status Report, whenever possible, to the target eNB to indicate that the handover procedure is completed for the UE. The target eNB verifies the C-RNTI sent in the RRCConnectionReconfigurationComplete message. The target eNB can now begin sending data to the UE.   10. “The target eNB sends a PATH SWITCH REQUEST message to MME to inform that the UE has changed cell.”   11. “The MME confirms the PATH SWITCH REQUEST message with the PATH SWITCH REQUEST ACKNOWLEDGE message.”   12. “By sending the UE CONTEXT RELEASE message, the target eNB informs success of HO to source eNB and triggers the release of resources by the source eNB. The target eNB sends this message after the PATH SWITCH REQUEST ACKNOWLEDGE message is received from the MME.”
 
However, when there is no X2 interface  20  between the eNBs (e.g. legacy eNBs  12  and  14  based on UTRAN architecture), or if the eNB  12  has been configured to initiate the handover towards a particular target eNB via the S1 interface  28  which connects the eNBs with the core network  22 , then the S1 handover procedure illustrated in  FIG. 3  will be triggered. The S1-handover procedure consists of 3 basic phases:
   

     1) Preparation phase  30   a  involving the core network, e.g. EPC, where the resources are first prepared at the target side (steps  2 - 8 ), 
     2) Execution phase  30   b  (steps  8 - 12 ), 
     3) Completion phase  30   c  (after step  13 ). 
     As an overview of S1-based HO Handover Procedures reference is made to [ 6 ]. For a detailed description also refer to the steps of the previous X2-based HO procedure. 
     As to Steps  13 - 15 , it is noted that some are special to the S1-based HO  30 , and comprise of acknowledgement and update information to the target MME. 
     Next, UE context transfer in 4G/5G is referred to. 
     The radio resource control (RRC) context transfer is an important procedure of the HO process. The MME  32  as a part of the core network  22  creates a UE context when a UE  12  is switched on and subsequently attempts to connect to the network  24 . A unique short temporary identity is assigned, also known as the SAE Temporary Mobile Subscriber Identity (S-TMSI), to the UE  12  that identifies the UE context in the MME  32 . This UE context contains user subscription data originally obtained from a Home Subscriber Server  34  (HSS) also being part of the core network  22 . The local storage of subscription data in the MME  32  enables faster execution of procedures such as bearer establishment since it removes the need to consult the HSS every time. In addition, the UE context also holds dynamic information such as the list of bearers that are established and the terminal capabilities [ 2 ]. During the P-HO process, the eNB  12  would be used to forward the UE&#39;s radio resource control (RRC) context to subsequent target eNBs such as eNB  14 . 
     After having described, rather generally, the task of handovers in cellular networks and how these handovers were treated so far in LTE, in the following, the description of the present application provides a presentation of embodiments relating to this task which achieve an improvement over these handover mechanisms used in LTE so far in terms of control signaling overhead on the one hand and/or handover-related latency on the other hand. 
     Later on, the description proceeds with a description as to how some of the embodiments might be embedded into, or implemented to address various specifics associated with, nowadays mobile networks. 
       FIG. 4  shows in a manner reusing the reference numbers of  FIG. 1  for entities fulfilling the same task in the overall system shown in  FIG. 4 , a cellular network  24  comprising a plurality of base stations  11  spatially spread so that their cells  15 , within which each base station  11  serves user entities residing in the respective cell  15  so as to connect them to the cellular network  24  by wireless communication, cover a certain region or area such as a geographical region  40  in a manner so that cells  15  abut or overlap each other. The cells  15  are quasi-defined by the respective wireless communication reach of each base station  11 . The cellular network of  FIG. 4  also comprises a core network via which, and to which, each base station  11  is connected via a respective interface  28  such as some cable based network such as electrical or optical cables. As already described with respect to  FIG. 1 , the base stations  11  might be connected to each other directly, too, such as via interface  20  shown in  FIG. 1  which might be cable-based or wireless such as an optical connection. 
       FIG. 4  also shows a user entity or user equipment  10 . It is currently served by base station  12 . That is, base station  12  is a special base station  11  with respect to UE  10 , namely the source base station  12 . That is, UE  10  is located within cell  15  of base station  12  and base station  12  communicates with the UE  10  via radio resources it assigns to UE  10 . The share of radio resources assigned to UE  10  depends on many factors such as subscriber data of UE  10 , number of further UEs currently served by base station  10  and so forth. It is assumed that UE  10  is currently in a connected or active mode. That is, UE  10  has, for instance, one or more current communication sessions running such as a call and/or data session. That is, the UE  10  which might be a mobile phone, a laptop or some other mobile or non-mobile device, may have one or more applications such as computer programs or the like, running thereon which communicate via base station  12  over network  34  with some third party which might be an entity within the cellular network  24 , but may alternatively be a third party device being external to the cellular network  24  and connected to core network  34  via the Internet or some other external network  42 . The core network  34  or some entity within core network  34  such as MME  32  contains or manages a context for each UE  10  currently served within region  40 . For instance, such context or context data could indicate which sessions are currently active with respect to each UE, at which base station  11  the respective UE is served, i.e., via which base station  11  the respective UE is connected to the cellular network  24 , and/or further information such as subscriber data or the like. In order to associate such contexts with the associated UEs, core network  34  assigns identifiers to the UEs. The currently serving base station  12  also knows about, or stores, the context of UE  10  and knows about the ID used within core network  34  with respect to UE  10 . Based on the context data, core network  34  is able to forward packets of any communication session associated with UE  10  towards base station  12 , which, in turn, forwards the same wirelessly to UE  10 . 
     The cellular network  24  of  FIG. 4  is configured to support a preemptive preparation of a handover for user entity  10 . This means the following. It might be, that cellular network  24 , optionally, has the afore-mentioned functionality of initiating a handover of UE  10  to another, i.e., a target base station; namely, one of the neighboring base stations neighboring base station  12 , on the basis of an evaluation of measurements made by the UE  10  which measure the connection quality between UE  10  and base station  12  as well as between UE  10  and any of the neighboring base stations  11 , provided the UE  10  is within the reach of the respective neighboring base station  11 . Such passive activation would mean that the cellular network  24  comes to the conclusion that a handover to such a neighboring target base station would be advantageous according to some criteria such as connection quality and/or other criteria. The cellular network  24  of  FIG. 4 , however, supports a speculative or preemptive preparation of a handover for a user entity such as user entity  10 . When preemptively preparing a handover for user entity  10 , the cellular network  24  establishes, for each of a set of one or more target base stations  14   a  and  14   b  of the cellular network  24 , a temporal access interval and one or more access parameters so that the user entity  10  may access the cellular network  24  via the respective base station  14   a ,  14   b  during the temporal access interval using the one or more access parameters established for the respective base station. This means, that for such a set of base stations  14   a ,  14   b , the handover is, as far as the cellular network&#39;s side is concerned, already done. It is merely up to the UE  10  or up to other circumstances discussed further below, whether the access opportunity provided within the temporal access intervals using the one or more access parameters for base stations  14   a ,  14   b  is actually used by UE  10 . The target base stations  14   a ,  14   b  to which a handover has been preemptively prepared, reserve a certain access channel or radio access channel using the one or more access parameters established for the respective base station during the temporal access interval. 
     To have a better understanding of this, reference is made to  FIG. 5 .  FIG. 5  shows the process of preemptive preparation of the handover by way of establishing respective temporal access interval and one or more access parameters for one or more target base stations by illustrating the temporal sequence of steps performed along a temporal access t. As shown in  FIG. 5 , the preemptive preparation of a handover is triggered at a time instant t 0 . In other words, at this time instant t 0 , the cellular network determines a preliminary set  50  of one or more base stations of the cellular network with respect to which a preemptive preparation of a handover might be performed. This preliminary set  50  of base stations is determined by the cellular networks so that their cells  15  cover an area where the UE  10  will probably move in the next future upon leaving the cell of current source base station  12 . As described later on, for instance, cellular network  24  may determine the preliminary set  50  depending on information on a predicted future route of the user entity. In  FIG. 4  such a predicted future route is illustrated using a dashed line  52 . The same crosses the cells of base station  14   a  and  14   b .  FIG. 5  illustrates the preliminary set  50  to be composed of, generally, base stations  14   1  . . .  14   M  with M≥N. The temporal length of the predicted future route  52  may cover a certain temporal interval  54  starting from time instant t 0  and lasting, for instance, for more than 10 seconds, 1 minute or even 5 minutes. The temporal length  54  might be determined variably as well and might be adapted, for instance, to the prediction accuracy of the predicted future route  52 . The cellular network might receive the information on the predicted future route  52  of the user entity  10  from the user entity  10  itself such as, for instance, from an application running on the user entity or a certain component thereof being able to determine the position of the user entity  10  such as a navigation system or the like, or from some other module of the UE. The information transmission may take place during RRC Connection establishment, for instance. Alternatively, information on the predicted future route  52  of the user entity  10  might come from a device other than the cellular network  24  and the user entity  10 . Such other device could be, for instance, a system which tracks the user entity  10 , but resides external to cellular network  24 . The information could be provided, for instance, by an external entity such as a V2V/V2X server, or from an over-the-top (OTT) entity such as Google 6. It might even be that the other device is responsible for granting allowance for the future route  2  such as a traffic management system which could be, for instance, responsible, for flight routes of drones as examples for UEs or the like. Additionally or alternatively, the cellular network  24  may determine the predicted future route  52  of the user entity itself such as by triangulation applied onto signals sent by the UE  10  and received by several of the base stations  11  or the like, or by extrapolating path  52  from a past travel path of UE  10  defined by updates on the UE&#39;s current position which the network  24  receives from the UE  10 . The derivation of the predicted future route  52  may involve, in any case, irrespective of the entity performing the derivation, a type of extrapolation or prediction on the basis of additional information in addition to a current position of the user entity  10  such as a route taken by the UE  10  immediately up to time instant t 0 , map data indicating a map of region  40  such as a street map or the like, and/or user preference data associated with the UE  10  having been gathered based on an evaluation of routes taken by the UE  10  in the past. Preliminary set  50  would then be determined so that the base station&#39;s cells within the set  50  would be crossed by route  52 . The UE  10  is, thus, likely to need a handover at at least a subset of base stations of set  50 . It should be noted, however, that set  50  may, alternatively, be determined by the cellular network  24  by means other than based on an evaluation of predicted future route  52 . The predicted route  52  could, for instance, be determined by a V2X broadcast server, or using information from other mobile users, e.g. by sensor fusion of a set of predicted routes from multiple UEs. Further, base station  12  could be configured to request the route vector  52  as a kind of measurement report, including route updates and top-m routes e.g. route  1 , route  2 , route  3 , . . . . 
     The use of route  52  for determining set  50  is not necessary. For instance, the mere fact or circumstance that UE  10  enters a certain predetermined area  56  may be an indicator that there is a high probability that the user entity  10  will be, during a certain time interval  54  following time instant t 0  at which the UE  10  entered area  56 , in a certain area, or will travel along a certain path or route so that set  50  could be automatically determined albeit fixedly associated with, the event of UE  10  entering area  56  at time instant t 0 . For instance, the area  56  could be one end of a street without any crossing until reaching, via a certain path  52 , namely the street, a first crossing and accordingly, as soon as the UE  10  enters the street at this point, it is very likely that the UE  10  will follow this route/street  52 . Similarly, imagine a UE  10  enters a tunnel at a first end and the tunnel being long so as to lead to another cell. While it might be unknown which street the UE takes after the tunnel, it is very likely that the UE will continue its journey after the tunnel and accordingly, set  50  could be determined so as to cover base stations surrounding that side of the tunnel. 
     Even alternatively, the prediction that there is a high probability that the user entity  10  will be, during some time interval  54  following a time instant t 0 , in a certain area, or will travel along a certain path or route, could be triggered on the basis of an evaluation of a history of a route of the CE in the past such as a time interval preceding, or even immediately preceding, time instant t 0 . In addition to the user entity  10  entering area  56 , for instance, a current heading direction of UE  10  could be taken into account so as to trigger a preemptive HO preparation merely in case of the heading direction pointing into a certain direction or field of directions in addition to UE entering  56 . For instance, preemptive preparation of HO could be triggered by the user entity coming from predetermined area  56 . Generally speaking, a history of UE positions could be evaluated in order to see whether this history meets some criteria and if so, preemptive HO could be initiated. The history of positions may be logged in any granularity or accuracy. For instance, a previous set of serving base stations or a list of previous base stations along the route of the user entity, i.e. some mobility history, could be used to this end. Irrespective of area driven or history-of-positions driven, the triggering could be done based on matching current UE&#39;s position, current UE&#39;s heading direction and/or most recent history of UE positions against one or more predetermined criteria which are independent from the most recent connection quality measured by the UE with respect to its communication connection to the source base station  12  and/or any surrounding base station  11 . 
     That is, along with determining the preliminary set  50  of base stations, cellular network  24  determines for each base station within set  50  an expected time t 1  . . . t M  at which the user entity enters the respective base station&#39;s cell  15 , i.e., is within its reach. Accordingly, base station  12 , i.e., the source eNB, queries each of the preliminary set  50  of target base stations regarding an accessibility of the cellular network  24  via the respective target base station at the respective expected time t i . As an outcome of this query, base station  12  of cellular network  24  receives from each of the preliminary set  50  of base stations, an answer to the query. While there may be none, one, or more than one base station within preliminary set  50  which denies the accessibility, there may be a set of base stations, let&#39;s say N base stations with N≥1 and N≤M which answer the query by way of indicating a temporal access interval  60  at which the respective base station is accessible by user entity  10  provided that user entity  10  uses the one or more access parameters indicated by the respective base station in the answer to the query. For instance,  FIG. 5  illustrates that a certain access interval  60  overlaps a first expected time t 1 . A base station of set  50  within the cell of which the user entity  10  is expected to be as time instant t 1 , thus, allows user entity  10  to access the cellular network  24  using one or more access parameters via correspondingly reserving respective access radio resources during time interval  60 . The same might apply for the other expected times when the associated target base stations may all be different for the expected times, but this is not necessarily the case. After the query and the answers thereto, base station  12  is, thus, able to send to the user entity  10  a schedule  62  which indicates, for each of the set  64  of one or more base stations for which a temporal access interval  60  and one or more access parameters  66  have been determined, the temporal access temporal interval  60  as well as the one or more access parameters. This schedule  62  indicates to the user entity  10  that the same may access the cellular network  24  via the respective base station  14   x  during the temporal access interval indicated, for instance, by its beginning or start at t x   start  using the associated one or more access parameters p x   access  with x being element of {a, b . . . }, i.e. being an index into set  64 . In other words, schedule  62  could be submitted as an ordered list of elements, the elements having a temporal dependency, or the schedule  62  could be submitted as a set of elements. An even alternatively, schedule  62  could be submitted as a list of lists or sets which may be ranked, e.g. top-m. Each such element would then be associated with a certain target base station, define its access interval  60  and the one or more access parameters  66 . Thereinafter, i.e. of submission of schedule  62  to UE  10 , the preemptive preparation or one or more handovers is finished and the user entity has been notified thereabout and it is, from the sending of the schedule  62  to the user entity onwards, up to the user entity  10 , whether or not the user entity uses the access opportunities during intervals  60  to handover itself from one base station to the next, or, from a different perspective, it is up to the user entity to exploit these opportunities provided that other external circumstances did not prevent user entity  10  from exploiting these opportunities because, for instance, the prediction of route  52  of the forecast on the basis of the event of UE  10  entering area  56 , turned out not to be correct. 
     For the sake of completeness only, it should be noted that the time consumed by querying the base stations of set  50  and obtaining the answers up to sending schedule  62  may be negligible compared to the temporal length  54  within which the one or more expected times t i  are distributed. The schedule  62  may define a certain temporal access  60  by indicating, for instance, its start time t x   start  wherein an end of the temporal access interval  60  could implicitly be defined by a maximum length of each interval  60 . In other words, the respective base station  14   x  could close the access opportunity after a certain time after t x   start . The temporal end of interval  60  could be indicated, too, however in the schedule  62 . 
     As described later on, the query sent from base station  12  to the target base stations of set  50  may possibly contain one or more current identifiers using which the user entity  10  is identified in the cellular network such as, for instance, an identifier via which the user entity  10  is identified in the core network  34  such as in the MME  32 . In particular, the query could additionally or alternatively inform the base stations of set  50  about the context data of user entity  10 . On the other hand, performing the preemptive preparation of the handover as just described could also additionally involve sending a schedule  66  such as a copy of schedule  62  from base station  12  to core network  34  such as MME  32  within core network  34  so as to schedule a redirection of packets of one or more communication paths for communication sessions of the user entity  10  over the cellular network  24  and the user entity  10  so that the packets are distributed to each base station of set  64  depending on the respective temporal access interval  60  of the respective base station in set  64 . In other words, MME  32  or the core network  34  would be able to plan, at an early stage; namely, at the time of receiving schedule  66 , a distribution of inbound packets arriving, for instance, from the external network, to base stations among set  64  other than the base station via which the user entity  10  is currently connected to cellular network  24 . Packets, for instance, which are likely to be buffered too long at a certain base station of set  64  and cannot be transmitted from that base station to the user entity  10  before the expected handover from that base station to the next base station of set  64 , may be forwarded by core network  34  or MME  32 , respectively, to the next base station of set  64  according to the sequence of expected times covered by the respective temporal access intervals  60 . The cellular network  34  would, first, not have to wait for such redirection until the handover actually takes place on behalf of UE  10  actually using the one or more access parameters it has been provided with by way of schedule  62 . 
     It should be noted that the cardinality of the set  50  and the cardinality of set  64  or the cardinality of either of these sets might be greater than 1. Generally, however, both may be 1, 2. As to the future start time  70  indicated in schedule  62  to indicate the start of the respective temporal access interval  60 , it is noted that the same may be indicated by quantization indices or in seconds or the like. 
     It should have become clear from the above, that, if the prediction that formed the reason for the preemptive preparation of a handover is good, the UE  10  is likely to handover from base station  12  to the target base station for which the temporally-nearest temporal access interval  60  is indicated in schedule  62 . That is, UE  10  will use the one or more access parameter  66  for this target base station which would, in the example illustrated in  FIG. 4 , for instance, be the base station  14   a , during temporal access interval  60  and thus, would perform or activate the handover preemptively prepared as described so far. This base station  14   a  would then inform base station  12  about the user entity having accessed the cellular network  24  via the base station  14   a  and triggered by this information, base station  12  would cut its connection to UE  10 , while core network  34  would be informed by base station  14   a  with, triggered thereby, redirecting a cellular network internal sub-path of each of a set of one or more communication paths of one or more communication sessions running via the cellular network  24  and the user entity  10 , from base station  12  to base station  14   a . Further, resources of the base station  11  via which the user entity  10  is currently or, better, has been so far, connected to the cellular network, here base station  12 , could be released such as one or more buffers thereof managed by the base station for the one or more currently active communication sessions of UE  10 . Base station  12  could cut its connection to UE  10  and/or release its resources alternatively in response to a signal sent from the core network indicating that the path redirection has been performed responsive, in turn, to the note sent from target base station  14   a , which then assumes the now role as source base station. In the same manner, the next handover between this target base station, which is now the source base station, to the next target base station of set  64  takes place. 
     Thus, with respect to  FIG. 4 , a cellular network  24  has been described which supports a preemptive preparation of a handover for user entity  10 . Concurrently, however, the above description revealed a user entity  10  for communication over a cellular network  24 , wherein the user entity  10  is configured to gain information on a predicted future route  52  of the user entity and inform the cellular network on the predicted future route  52 . The UE could transmit a list or vector of coordinates, e.g. WGS84 coordinates, to the cellular infrastructure  24 . UE  10  could do this upon request from the base station  12 , from a V2X server or in regular time intervals. It should be noted, however, as described above, the origin of the information on the predicted future route  52  may stem from an entity other than the user entity  10 . The information on the predicted future route  52  may be sent to cellular network  24 , for instance, as a set of pairs of time and coordinates of locations at which the user entity  10  is on the predicted future route  52 , or a sequence of coordinates of location sequentially traversed by the user entity along the predicted future route  52  such as locations which the user entity traverses along the predicted future route  52  at a certain temporal pitch of a constant pitch interval. 
     Further, however, the above description revealed the description of a user entity for communication over a cellular network  24 , wherein the user entity  10  is configured to manage a set of one or more preemptively prepared handovers. In this way, the user entity  10  not necessarily informs the cellular network on the predicted future route  52 . In general, the user entity  10  could handover to more than one carrier. The user entity could, thus, perform the handover within the frame work of dual connectivity, e.g. LTE+NR/5G, multi-RAT e.g. separate networks LTE, CDMA/UMTS, NR or carrier aggregation, e.g. handover to a carrier with lower frequency=better coverage or higher frequency=potential higher capacity or lower latency. Details and background in this respect are outlined below. In any case, the user entity  10  may be able to manage a set of one or more preemptively prepared handovers; namely, those indicated in schedule  62  which user entity  10  receives from the cellular network  24  and the source base station  12 , respectively. From the reception onwards, i.e., substantially over the whole time interval  54 , the user entity  10  continuously checks whether the schedule  62  becomes inadequate. For instance, the user entity recognizes that the user entity gets farther away from the predicted future route  52  because, for instance, the user of the user entity  10  decided to take another way than rule  52 . In that case, user entity could inform the cellular network  24  on the inadequateness so that, for instance, cellular network  24  could inform the target base stations of set  64  thereabout so that the latter could render the reserved radio access resources associated with the one or more access parameters available for other user entities. As described above, the user entity could derive from the schedule  62  the temporal access interval  60  plus associated one or more access parameter  66  per target base station within set  64  and then, from the reception of schedule  62  onwards, continuously decide on accessing the cellular network  24  via any of this set  64  of target base stations; namely, any base station of the set  64  within a reach of which the user entity  10  currently is. Obviously, this decision is merely available during the temporal access interval  60  associated with a respective target base station, annually using the one or more access parameters specified in the schedule. The user entity  10  is able to perform a handover or access of the cellular network using schedule  62 , or perform the just described continuous decision thereabout, without obtaining current permissions from the cellular network  24  on a case by case basis, i.e., without obtaining current permission during time interval  54 . Schedule  52 , instead, serves as a license for user entity to perform each handover during the respective time interval  60 . 
     As described later on in more detail, user entity  10  may be configured to perform the management of the set of one or more preemptively prepared handovers as outlined in schedule  62  with respect to one or more wireless connections to the cellular network  24  of a set of current wireless connections to the cellular network  24 . For instance, user entity  10  could use aggregated carriers and perform the exploitation of preemptively prepared handovers with respect to one or more than one component carrier of such aggregated carriers. 
     As should have become clear from the above, the user entity may be able to resume connectivity to the cellular network after loss of the connectivity using any of the set of one or more preemptively prepared handovers despite a temporary loss of connection. For example, in a scenario where the UE lost connection due to a tunnel, UE  10  and the next base station involved in the preemptive preparation of HOs may simply resume the connection between using the preemptively prepared HO. 
     Although not described above so far, it should be noted that in addition to the description brought forward above with respect to  FIG. 4 , or alternatively thereto, a cellular network could be configured to follow a third aspect of the present application. In particular, the cellular network could analyze a predetermined set of cells  15  of base stations around the position of the user entity with respect to a set of possible routes leading away from the user entity&#39;s position to determine a favorite route among the set of possible routes in terms of connectivity to the user entity. For instance, a cellular network could query the set  50  of target base stations with the set  50 , however, covering more than one route, i.e., a set of possible routes leading away from the current user entity&#39;s position. The target base stations of set  50  would, thus, be determined to cover all routes in the set of possible routes. The target base stations of set  50  would answer the query and based on these answers, cellular network  24  could determine a favorite route out of all routes in the set of possible routes in terms of connectivity; namely, the route alongside of which, for instance, all nearest base stations indicated a possible access time interval  60  plus associated one or more access parameters  66 . For example, the favorite route could be the Best Connected Route from point-of-view of the user terminal UE, such as the route providing highest QoS. The favorite route could be the Best Connected Route from base station point-of-view such as the route with the least traffic or highest capacity/coverage/lowest delay/best user experience/low overload likelihood. The cellular network  24  could inform the user entity  10  about the favorite route actively or upon request or polling by the UE  10 . For instance, currently serving base station  12  could provide a download link, so that the UE  10  or its user can decide itself to update its route. In other words, base station  12  or cellular network  24  could push this information to the UE. Alternatively, the UE  10  could download or pull this information on the favorite route from the cellular network  24 . Applications running on the user entity, for instance, could use this information. By this measure, the user of a user entity, for instance, could be provided with this information such as, for instance, via a display or a similar output device of the UE  10 , and the user could decide, as the bearer of the user entity  10 , to take the favorite route in order to, for instance, enjoy a currently downloaded video without any stall event. The “user” should be, however, not be restricted to a human user. Imagine the UE to form an interface of a robot or other autonomous driving device where an interruption of the data connection could have tremendously negative and dangerous impacts. Likewise, the recipient of a path recommendation could be another device such as device responsible for, or cooperating in, determining the future route which the UE takes such as a traffic management unit. The information about the possible routes could be provided by the cellular network from outside. However, the cellular network could determine the set of possible routes by itself or could receive this information on the set of possible routes from the user entity. That is, the cellular infrastructure  24  could recommend certain routes based on the coverage, e.g. by indicating to the user, which route index provides the best coverage, e.g. top-m routes from the network point-of-view. Analysis and information provision could be performed within the source base station  12 . That is, any base station  11  could have this functionality. The functionality could, however, by realized in other device of the cellular network  24 . 
     The above embodiments could be used to achieve lower handover latency and/or lower control signal overhead associated with handovers. 
     Current LTE Handover (HO) procedures have not been designed to accommodate Ultra Reliable Low Latency Communications (URLLC) where the existing average minimum HO is approximately between 40-50 ms [1]. As a result, there is room to improve the efficiency of the overall HO process for 5G use cases, including low latency communications. This may be done by using the embodiments described so far. 
     An efficient and rapid mechanism for performing handovers through predictive route information of the UE with varying mobility speeds may be achieved using above embodiments. The advantage of the latter enables reduced signaling overhead and latency when connecting to the subsequent target eNB(s)/gNB(s) for LTE and New Radio (NR) network architectures. This may be performed by UE signaling the pre-allocated target cell parameters  66  used to connect to the target eNB/gNB before the actual HO process.  FIG. 6  provides an overview of a Predictive-HO (P-HO) scheme in the LTE framework. 
     A preemptive decision will have to be triggered before the actual HO occurs in order for the Source/Anchor eNB/gNB  12  to signal the UE  10  with the target eNB/gNB parameters  66  (e.g. RRCConnectionReconfiguration including the mobilityControllnfo message), examples of which are outlined in the table shown in  FIG. 7 . 
     In even other words, the embodiments described so far enable an efficient mechanism for predictive handovers in a NR network with N predicted target gNBs. 
     The following aspects may be supported (cp.  FIG. 4  and  FIG. 6 ):
         1) Initiate a HO preparation to N-target eNBs  64  along a predicted path  52  and UE pre-allocated signaling using triggers initiated by the:
           a. the source gNB or anchor gNB  12  (Network Controlled),   b. UE  10  triggered,   c. a novel centralized entity  80  in the radio access network  24 , e.g. central baseband unit (CBBU) with a central Radio Resource Management (RRM) (Network Controlled).   
           2) Efficient N-hop predictive context forwarding using network signaling sent from
           a. a source or anchor-gNB  12  to N target-gNBs  64 ,   b. an anchor gNB  12  within a RAN paging/tracking/notification area such as 40 to N new or potentially new anchor eNB within a new RAN paging/tracking/notification area,   c. a central baseband unit  80  and/or to N new or potentially new central baseband units,   d. a source gNB  12  or CBBU  80  to the UE  10  in preparation of a HO process.   
               

     In particular, the NW or UE  10  can trigger the initiation of a N-hop Predictive Handover (P-HO), according to the RRC State. The P-HO procedure is a set of configuration parameters  64  of a set  64  of target cells along a predicted route  59  that are signaled to a UE  10 , before a HO actually takes place. The UE  10  can, with the aid of certain available side information (CAM Messages containing time, 2D and 3D location reporting, location vectors, location coordinate intervals, journey route, flight plan etc.) trigger the source/anchor eNB  12  to perform a P-HO. Two options are considered for driving the P-HO:
         1. In RRC Connected (LTE)/Active (NR) Mode: The source/anchor eNB  12  or the CBBU  80  in case of CU/DU (central unit/distributed unit) split) initiates and performs the P-HO.   2. In Lightly Connected (LTE)/Inactive (NR) Mode: The UE  10  autonomously initiates the request for the relevant P-HO configuration parameters including the predictive context forwarding to all relevant target eNBs/gNBs.       

     Therefore, the source eNB or centralized entities (e.g., CRRM, CBBU, MME) can initiate the multiple predictive HO preparation for N≥1 target eNBs  64  along the predicted UE trajectory  52 . This scheme avoids the need to re-initiate the HO preparation phase once the UE passes through each of the expected target cells since all the used resources have been pre-allocated. The resulting P-HO scheme aims to reduce signaling overhead and latency, once information about the predicted route  52  has been established. The N expected target eNBs  64  will expect the UE  10  to reach its cell within a pre-defined interval  60  (valid time interval) based on the initial setup time t 0  of the N-hop predictive HO procedure and a UE mobility type (e.g. high or low speed). If the UE  10  abruptly changes trajectory or remains stationary at a particular target cell, then all target eNBs/gNBs  64  identified during the P-HO procedure can release the pre-allocated resources via a timeout. 
     An example sequence diagram for a NW or UE driven P-HO is shown in the sequence chart in  FIG. 8 . The embraced portion  90  indicates the signaling scheme specific for the P-HO scenario. The P-HO procedure is triggered by the centralized entities such as 80 or source eNB/gNB  12  when the UE  10  is either in the proposed active (NR) and normal RRC connected states (LTE) as shown in the state diagram ( FIG. 3 ) [3]. When the UE  10  is in the lightly connected mode, prediction information based on the P-HO can enable the UE to autonomously transition between eNB/gNBs cells belonging to different paging areas as described farther below. In order to perform the used RRC Reconfiguration between each cell, the UE can transition from a normally connected state to a lightly connected state. As a result, the UE can be in a low power lightly connected state and still perform the P-HO. 
     Messaging Step Overview of  FIG. 8 
     Message 2: This trigger can be initiated in the source eNB (or centralized unit) when the UE is in RRC connected/Active mode (in which there is no additional message. Alternatively, the P-HO can be triggered by the UE autonomously in lightly connected/inactive mode as part of the measurement report.   Message 3: This is a distributed message by the source eNB/gNB requesting the availability of resources from each target eNB/gNB (multiple HO preparation) together with the UE context to be transferred.   Message 4: Container with ACKs from respective target eNBs/gNBs with available resources.   Message 5: UE message with the used signaling parameters for the target eNBs/gNBs.   

       FIG. 9  is a further illustration of the aforementioned messages using a Centralized Unit/Distributed NR Architecture. The signaling flows of the messages correspond to the proposed messages in  FIG. 8 . 
     Key Procedures of the P-HO: 
     A more detailed exemplary message description is presented below:
     Message 2: The Source eNB/centralized unit or UE can trigger the P-HO process. From the source eNB/centralized unit perspective the trigger can occur by monitoring the UE when in connected mode and then executing a P-HO. In relation to the UE, information about the predicted route can be directed by the UE itself, enabling it to autonomously move between paging areas in lightly connected mode using the onboard prediction data. The UE can signal the following messages to the source eNB within the measurement report:
       CAM messages,   Speed, acceleration, velocity, 2D and 3D location reporting, etc.   Route information, GPS information, flight plan   Traffic information, etc.   
       

     Example Syntax: UE-aided-P-HO-IE 
       
     
       
         
           
               
               
             
               
                   
               
               
                 IE/Group Name 
                 Description 
               
               
                   
               
             
            
               
                 Message Type [4] 
                 “Identifies the message being 
               
               
                   
                 transmitted, e.g. Handover Resource 
               
               
                   
                 Allocation, Path Switch Request” [12] 
               
               
                 CAM-Aided-Route-Prediction 
                 The list of data elements in [14] Annex 
               
               
                   
                 A, e.g. Acceleration Control, 
               
               
                   
                 CourseofJourney, Reference Position 
               
               
                 Path-target-eNB-ID-List 
                 If available the positions or ID of 
               
               
                   
                 target eNBs along the predicted route 
               
               
                 RRC-Connect-Time 
                 RRC connect period of current cell 
               
               
                 RouteInfo/FlightPlanInfo 
                 2D and 3D location vector of UE, UE 
               
               
                   
                 Direction, course location points along 
               
               
                   
                 a UE route 
               
               
                   
               
            
           
         
       
         
         Message 3: The P-HO request message via S1/X2 requests resource availability from potential target eNB/gNBs about a predicted handover from a specific UE. It can contain information about the user such as expected arrival time, unique IDs, context and security information and expected level of service requirements. 
       
    
     Additionally, the context of the UE can be pushed to all target eNBs. An example of this setup S1 message could include: P-HO-REQUEST-IE (Direction: source eNBs→Target eNBs) 
     
       
         
           
               
               
             
               
                   
               
               
                 IE/Group Name 
                 Description 
               
               
                   
               
             
            
               
                 Message Type [4] 
                 Identifies the message being 
               
               
                   
                 transmitted, e.g. Handover Resource 
               
               
                   
                 Allocation, Path Switch Request 
               
               
                 Handover Type[4] 
                 Indicates the type of Handover at the 
               
               
                   
                 source eNB, e.g. IntraLTE, 
               
               
                   
                 LTEtoUTRAN 
               
               
                 eNB List to be setup 
                 Identifies a list of target eNBs 
               
               
                 MME-UE-S1-AP-ID[4] 
                 “Uniquely identifies the UE 
               
               
                   
                 association over the S1 interface 
               
               
                   
                 within the MME.” [12] 
               
               
                 eNB UE S1AP ID [4] 
                 “Uniquely identifies the UE 
               
               
                   
                 association over the S1 interface 
               
               
                   
                 within the eNB.” [12] 
               
               
                 Predicted UE Behavior 
                 Defines the future behavior of the UE 
               
               
                   
                 with predictable activity with predicted 
               
               
                   
                 info, to assist future eNBs in 
               
               
                   
                 determining the optimum RRC 
               
               
                   
                 connection time. 
               
               
                 UE Context Transfer 
                 The UE context is pushed to all Target 
               
               
                   
                 nodes based on the prediction. 
               
               
                 UE Mobility Type 
                 Low, Medium, High speed 
               
               
                   
               
            
           
         
       
         
         Message 4: The response from the target eNB can acknowledge or deny the request via S1/X2 to the requesting source eNB/centralized unit using a ACK/NACK message. The decision is based on the outcome of the admission control and availability of resources. Once the target eNB acknowledges the request it has prepared resources for the potential new UE, has stored the new context and configured the lower layer protocols. An example of such a message from each target eNB is given as:
       P-HO-REQUEST-ACK-IE (Direction: Target eNBs→source eNB/Centralized Unit)   
     
       
    
     
       
         
           
               
               
             
               
                   
               
               
                 IE/Group Name 
                 Description 
               
               
                   
               
             
            
               
                 Message Type [4] 
                 “Identifies the message being transmitted, e.g. 
               
               
                   
                 Handover Resource Allocation, Path Switch 
               
               
                   
                 Request” [12] 
               
               
                 eRABs-Admitted-List [4] 
                 “HO Request ACK message is sent by the 
               
               
                   
                 Target eNB to inform the MME about the 
               
               
                   
                 prepared resources of the Target such as E- 
               
               
                   
                 RABs Admitted List. Hence the E-RABs those 
               
               
                   
                 could be admitted in the target are refered as 
               
               
                   
                 E-RABs Admitted List.” [12]. 
               
               
                 MME-UE-S1-AP-ID [4] 
                 “Uniquely identifies the UE association over 
               
               
                   
                 the S1 interface within the MME.” [12] 
               
               
                 eNB UE S1AP ID [4] 
                 “Uniquely identifies the UE association over 
               
               
                   
                 the S1 interface within the eNB.”[12] 
               
               
                   
               
            
           
         
       
         
         Message 5: The table shown in  FIG. 7  is a summary of the used UE signaling parameters that would be sent over the air to the UE originating from the eNB/gNB. The security keys of the target cells would use an additional layer of encryption, if they are to be pre-allocated. The RNTI and RACH Preambles can be pre-allocated according to the mobility type, thus eliminating the need for the UE to acquire these parameters each time when transitioning between the target cells. The UE could keep its identity across several cells, depending on whether the UE is in high mobility. One approach could be that the UE has a single ID within the RAN paging/notification area (e.g. selected by the anchor eNB where the UE entered the RAN paging/notification area or selected by a central node e.g. CRRM, CBBU, MME) denoted by the Unique-UE-ID element.
       The RAN (source eNB/centralized unit) may differentiate between three mobility types (e.g. low, medium and high mobility). Low and medium mobility types would get a cell specific C-RNTI, while the high mobility types of UEs can keep their identities. The target eNB would then know which UE ID to lookup, from the UE context already received in message 3. The SL configuration can also be pre-allocated to enable V2V communications. If the request is granted and the handover is prepared this message includes parameters used for the UE connect to Target eNBs.   The timeout indicator would be set at the source eNB depending on whether the P-HO was NW or UE triggered, and shared with the multiple target eNBs. The UE can notify the target eNBs via uplink signaling and if the UE does not enter the cells of the target eNBs within the time used, the pre-allocated resources are released and the fallback would be the traditional HO procedure.   A common RACH preamble management and/or common RACH resource management within the RAN paging/notification area would be envisioned. A high mobility UE would transition rapidly from one eNB to another and therefore may use the same preamble, across multiple target eNBs. It would then entail the notion of a common RACH resource pools across eNBs in order for the same RACH signal to be sent to multiple target eNBs along the route. Multiple target eNBs might then be able to decode the signal, which entails the formation of a common RACH resource pool. This highly depends on the RACH load and the RACH resource reuse. Since multiple cells share resources it might need to be operated at lower load decreasing efficiencies due to lower resource reuse.   
     
       
    
     P-HO User Data Forwarding, in case of out-of-coverage scenario may be done as follows: In the event that the UE loses coverage and has a Radio Link Failure (RLF) during the P-HO process with source eNB-1, we have the out-of-coverage scenario shown in  FIG. 10 . The UE attempts an RRC connection re-establishment to the target eNB given that it has already acquired the signaling parameters to connect with the target eNB. Redundant data forwarding could be applied to a centralized unit architecture. 
     Step/Description 1: RRC connection re-establishment: Enabling synchronization and timing advance using the prediction information already at the UE. This procedure can be initiated with the prepared RACH preambles and C-RNTI. 
     Step/Description 2.1: Prior to timeout with the source eNB, the core network has already forwarded redundant data via the centralized unit to the next target eNB based on information from the predictive HO procedure. This redundant data is forwarded to the target eNB, subject to the initiation of the P-HO process. 
     
       
         
           
               
               
             
               
                   
               
               
                 IE/Group Name 
                 Description 
               
               
                   
               
             
            
               
                 Message Type [4] 
                 “Identifies the message being transmitted, 
               
               
                   
                 e.g. Handover Resource Allocation, Path 
               
               
                   
                 Switch Request” [12] 
               
               
                 X2 TNL Configuration 
                 Contains the P-HO related information. 
               
               
                 Info [4] 
               
               
                 Core Data Forwarding 
                 Forwards the redundant data as initially 
               
               
                   
                 transmitted to the source eNB. 
               
               
                 MME-UE-S1-AP-ID-SeNB 
                 “Uniquely identifies the UE association over 
               
               
                   
                 the S1 interface within the MME.” [12] 
               
               
                   
               
            
           
         
       
     
     Step/Description 2.2: The UE can transmit a last packet ACK sequence number to the target eNB, to resume data forwarding from the last known timeout of the RRC connection with the SeNB. 
     
       
         
           
               
               
             
               
                   
               
               
                 IE/Group Name 
                 Description 
               
               
                   
               
             
            
               
                 Message Type [4] 
                 “Identifies the message being transmitted, 
               
               
                   
                 e.g. Handover Resource Allocation, Path 
               
               
                   
                 Switch Request” [12] 
               
               
                 X2 TNL Configuration 
                 Contains the P-HO related information. 
               
               
                 Info [4] 
               
               
                 UE Data Forwarding 
                 Sends ACK and forwards the SN number. 
               
               
                   
               
            
           
         
       
     
     In Dual-connectivity mode UE P-HO could be used as well. 
     Dual-connected (DC) P-HOs enable URLLC services of mobile UEs and therefore can fulfill the high reliability requirement. Predicted UE route information can also aid in seamless handover of UEs, which are in dual-connectivity mode, i.e. simultaneously connected to two eNBs, the master eNB and secondary eNB. This is particularly applicable to scenarios where a mobile UE travels across a number of small cells within a macro cell environment, e.g. dense urban scenario. A group of such small cells belong to a secondary cell group (SCG). DC enabled HOs can result in zero interruption due to the availability of at least one connected link at all times. The novel claim consists of the way Dual-connectivity can be initially leveraged to enable the master eNB to perform the P-HO for multiple small cells (secondary eNBs) allowing the UE to move across the small cells in a seamless fashion reducing overhead in standard HO signaling as described in E1. The procedure is as follows:
         1. The master eNB initiates the P-HO process (according to the source driven P-HO procedure) by receiving the SCG information which includes the parameters in Table 1 for each small cell.   2. The master eNB then provides this information to the UE (via a RRC Reconfiguration message) with all the used P-HO information for each small cell along the predicted route (See Table 1).   3. The master eNB can then terminate dual-connectivity, allowing the UE to have a single Uu connection with each small along the predicted route with the advantage that the HO has already been prepared, allowing a RRC Reconfiguration with each small cell in a seamless fashion.       

     The following description now attends to a description of the second aspect of the present application which pertains to the handling of user entities in a non-active mode in an efficient manner by the usage of a so-called “tracking/paging area”. Again, the description of this aspect and embodiments thereof starts with a type of presentation or overview so that the underlying problem with non-active UEs is clear and the advantages resulting from the embodiments described later on. The following overview is, however, partially also an extension of the introductory portion with respect to the description and presentation of the embodiments concerning the first and third aspects of the present application described above. 
     Mobility enhancements in lightly connected or inactive mode were recently developed. The state machine in current control plane protocols in cellular wireless mainly support two modes: the idle mode and the connected mode. In the idle mode, the UE monitors the control channel (PCH) according to a discontinuous reception (DRX) cycle. While in the idle state, the MME is responsible for the monitoring the UE. In the connected mode, the UE is connected to a known cell and can perform data transfer to and from the device. While in the connected mode/active state, the corresponding eNB is responsible for monitoring the UE. 
     HOs are performed when the UE is in the RRC connected mode. Currently in discussion is the introduction of a new mode, which is referred to as lightly connected (in LTE) or as inactive state (in 5G new radio (NR)), which should increase signaling efficiency, also for new services. In this state, the UE is responsible for transferring into idle or connected states. The lightly connected UEs enter into legacy behavior in RRC connected via RRC procedure including three messages (i.e. request, response and complete). In the lightly connected state, the S1 connection for this UE is kept and active, and a new signaling scheme from the UE could be introduced, in order to optimize handovers and improve network performance though movement predictions.  FIG. 11  is an example of the lightly connected state mode of operation as proposed in [ 3 ]. 
     RAN Paging/Notification Area and Tracking Area is used to track non-active UEs. Paging is used for network-initiated connection setup when the UE is in the idle state (RRC IDLE), see [5]. This shall indicate to the UE to start a service request. Since the location of the device is typically not known on a cell level, the paging message is typically transmitted across multiple cells in the so-called tracking area. These tracking areas are controlled by the MME. The UE informs the network via tracking area updates (TAU) of its location with the network. To reduce signaling traffic, a UE does not need to initiates a TAU if it enters a tracking area which is included in its tracking area list (TAL). See  FIG. 2 . 
     As to NR Architecture, two proposed architecture types for NR are proposed, viz. Centralized Unit (CU) Architecture or Distributed Unit (DU) Architecture as shown in  FIG. 13 . 
     Regarding V2X System Architecture, one of the main modes of operation in V2X consists of the broadcast architecture and serves as example application of the proposed P-HO scheme. 
     As to Broadcast V2X Architecture, the high-level V2X broadcast architecture is shown in  FIG. 14  with a new additional entity known as the V2X application server [8]. 
     The core functionality V2X Application Server is out of scope of 3GPP [8], and an overview of the role of the Application server has been defined by the ITS. According to the definition in [8], the Application server aggregates inputs from several sources including the vehicles on the road, road side units as well as external information from various other network entities. The Application Server then correlates this information based on time, location and incident to develop a better idea regarding the state of traffic. Once the information has been consolidated and processed it then has to decide in which information it has to disseminate to other vehicles in a geographic area [9]. Currently the V2X application server has the following specifications according to 3GPP, which fall in line with ETSI&#39;s proposal [8]:
         Ability to receive uplink data from the UE over unicast.   Delivering data to the UE(s) in a target area using Unicast Delivery and/or MBMS       

     Delivery.
         Mapping from geographic location information to appropriate target MBMS Service       

     Area ID (SAI(s)) for the broadcast.
         Mapping from geographic location information to appropriate target 3GPP E-UTRAN       

     Cell Global Identifier (ECGI(s)) for the broadcast.
         Pre-configured with Local MBMS (L.MBMS) information (e.g. IP multicast address, multicast source (SSM), C-TEID).   Pre-configured with L.MBMS&#39;s IP address and port number for the user-plane.       

     In order to minimize delays between RAN and V2X infrastructure, the V2X entities can be grouped into a eNB type Road Side Unit (RSU). This RSU can be deployed directly at a eNB, similar to edge-cloud computing, e.g. via local IP breakout interface (LIPA). This enables faster prediction of the HO process. See  FIG. 15 . 
     Dual-connectivity (DC) was included as part of small cell enhancements in LTE and offers several advantages which include [ 10 ]:
         Increased UE throughput at the cell edge,   Increase in robustness for UE mobility,   Reduction in signaling overhead toward the core due to frequent HO.       

     A UE can be connected to a Master eNB and Secondary eNB but can have only one RRC connection with the Master eNB. In a V2X scenario, DC can enhance seamless or zero interruption HO between various eNBs along a predicted route, by ensuring guaranteeing one active/inactive. The data split in the User-plane can take place at the bearer or packet level as shown in  FIGS. 16 and 17  [10] 
     “To initiate the HO, the source eNB sends a HO Request on X2. The HO Request needs to be modified to indicate that this is a dual connectivity HO as opposed to a traditional HO. The goal of the HO is to hand over a subset of the DRBs to the target eNB. Thus, we will need to augment the HO request message to specify which bearers are to be handed over. Currently, the UE context includes information on the bearers that are assigned to the source eNB. For dual connectivity, the UE context will need to specify which of its bearers are mapped to the target eNB. 
     The target eNB will indicate which bearers it is willing to accept in the HO Request ACK. As in the current HO procedure, bearers that are not accepted will be dropped. The target eNB sends the DL allocation and RRCConn Reconf with mobilityControlInformation to the source who sends it to the UE. SN status transfer and data forwarding will proceed for the bearers that are to be transferred. The UE will start RACH on one of its radios while maintaining regular communication of all bearers that remain on the source eNB. 
     If the handover is successful, the UE sends RRC Conn Reconf Complete as usual. Upon HOF, a new RRC message is sent to the source eNB on its associated UE radio to indicate the failure. The source eNB can assist the UE by either accepting a connection from radio #2 or by preparing another eNB to do so. 
     If the HO was successful, the target eNB will send a path switch Request to the MME on S1 requesting its assigned bearers. The MME will send Modify Bearer request to the Gateway. Finally, the target eNB updates its UE Context and sends a UE Context Update to the source eNB over X2. The source eNB updates its UE Context and releases resources associated with the HO.” [12] 
     It should have become clear from the brief introduction put forward above, the concept of managing a tracking/paging area for some user entity reduces the burden on the side of the cellular network to continuously reserve radio resources for user entities for which one or more communication sessions are active, but for which the one or more communication session does not involve a continuous transmission of packets. Thus, it is sufficient if the cellular network keeps track of where the UE is at least approximately; namely, within some tracking/paging area, so that packets addressed to the UE may be forwarded to the one or more base stations within this tracking/paging area, and if the base stations within the tracking/paging area know the context data of the UE. The concept exploited in some of the embodiment described with respect to active UEs and the preemptive preparation of handovers as used in some of the embodiments described above, is now reused in order to more efficiently deal with non-active UEs; namely, in that a schedule of a time-varying tracking/paging area is introduced and/or a tracking/paging area is determined depending on a predicted future route of the user entity. 
     In order to explain embodiments of the present application with respect to this aspect, reference is made to  FIG. 19  which reuses some of the reference signs already used previously; namely, with respect to entities that assume the same or a similar task within the overall communication network. 
     In particular,  FIG. 19  shows a cellular network  24  which is, as discussed with respect to  FIG. 4 , composed of a plurality of base stations  11  spread so as to cover with their associated cells  15  a certain region or geographical area, wherein the base stations  11  serve UEs within their cells in that the same perform the wireless communication with the UEs within their cells. The base stations  11  are connected via some interface  28  with the core network  34  of cellular network  24 . This core network  34  in turn, may have an interface towards an external network  42 . With respect to activated UEs, i.e., UEs which are currently connect to the cellular network  24  via a current source base station, the behavior of cellular network  24  and the UEs communicating via cellular network  24  of  FIG. 19  may be as described with respect to  FIG. 4  or, optionally, in accordance with the current solutions discussed above with respect to  FIGS. 1 to 3 . The cellular network  24  of  FIG. 19 , however, is configured to establish for a predetermined user entity  10  a schedule of a time-varying tracking/paging area spanned or defined by a time-varying set of one or more base stations or made-up by the cell(s) of the set of one or more base stations. In order to explain this in more detail, reference is made to  FIG. 20 .  FIGS. 19 and 20  assume that the base stations  11  are spatially pre-clustered into so-called “paging areas”  90 . Four such clusters or spatially-neighboring base stations  11  are exemplarily shown in  FIG. 19 . It should be noted, however, that this clustering is not mandatory for the present embodiment. As shown in  FIG. 20 , the cellular network  24  determines, at some time instant t 0 , for a UE  10 , a time-varying tracking/paging area. The time instant t 0  might, for instance, be initiated by UE  10  which decides to switch from an active mode to an intermediate mode of low activity, the details of which are described and exemplified in more detail below. The tracking/paging area is, at each time instant, an area served or spanned by a set of one or more base stations, but this set varies in time. Its determination occurs at time instant t 0  based on some sort of prediction similar to thoughts which led to set  50  in  FIG. 5 . For instance, the tracking/paging area may be defined to follow a predicted future route  52  of UE  10 , i.e., to follow the position the UE  10  has predicted to assume in route  52 . The outcome of such determination is shown in  FIG. 20  as a schedule  100 . In particular, schedule  100  defines, for each time instant within some time interval  102  which follows time instant t 0 , the set of one or more base stations  11  which form the tracking/paging area, i.e., set  104 . In  FIG. 20  it is exemplified that schedule  100  indicates the set  104  in units of clusters  92 , but this might be solved differently. In particular, schedule  100  indicates this set for consecutive partial intervals  106 , into which the time interval  102  is sub-divided. That is, for each such partial interval  106 , schedule  100  indicates the set  104  of base stations  11  which make up the tracking/paging area. Alternatively, the UE  10  is intermittently informed on the time-varying tracking/paging area by way of messages intermittently updating the set of base station cells defining the area  104 . 
     The cellular network  24  then sends the schedule  100  or messages intermittently updating area  104  to the user entity  10  which, thus, is able to continuously check whether the UE  10  leaves this time-varying tracking/paging area defined by the time-varying set of one or more base stations  104  or not. As long as the UE does not leave the time-varying tracking/paging area, the UE is within an area within which the cellular network  24  expects the UE  10  to be. As long as the UE  10  does not wish to initiate an uplink communication and to switch to active mode, the UE  10  needs to do nothing. The cellular network  24 , in turn, takes the appropriate measures to fulfill tasks which seek to reflect the fact that the tracking/paging area is changing over time as scheduled in schedule  100 . In particular, the cellular network  24  provides each base station of set  104 , i.e., each base station currently within the set  104  of base stations which define the tracking/paging area, with context data of UE  10  so that these base stations are aware, for instance, of the UE&#39;s  10  subscriber data currently active one or more communication sessions, one or more IDs used by the cellular network  24  to identify UE  10  and distinguish UE  10  from other UEs and/or other UE specific data. Further, cellular network  24 , itself, uses schedule  100  so as to search for UE  10  whenever an inbound or downlink packet of one of one of more active communications sessions arrives at the core network  34  addressed to UE  10 . In particular, the cellular network  24  then looks up in schedule  100  which set  104  of base stations currently makes up or defines the tracking/paging area and informs via these one or more base stations that the UE  10  should connect to the cellular network  24  so as to be able to receive this packet. The control signaling overhead is kept low as the UE is within the time-varying tracking/paging area and the base station within the cell  15  of which the UE  10  currently is, belongs to the set  104  defining this tracking/paging area and this base station already has at hand the context data of UE  10 . 
     It should be noted that, according to an alternative embodiment, the cellular network of  FIG. 19  does not form a schedule  100  of a time-varying tracking/paging area. Rather, as depicted in  FIG. 21 , according to this alternative, the cellular network  24  uses the gained knowledge about the predicted future route  52  so as to appropriately select the set  104  of one or more base stations which define the tracking/paging area. As long as the UE is within this area  104  which has precisely been predicted using predicted future route  52 , control signaling overhead on the side of the UE which could negatively impact the power consumption of UE  10 , may be avoided. In the example of  FIG. 21 , cellular network  24  sends to the UE  10  the set  104 . In both alternatives discussed above with respect to  FIGS. 20 and 21 , the user entity  10  is a user entity for communication over cellular network  24  and the user entity  10  is configured to continuously check whether it is still in the tracking/paging area defined by the set  100  of one or more base stations or whether the user entity has left the same. In case of leaving, the user entity  10  sends a tracking/paging area update message to the cellular network  24  which, in turn, then re-initiates the determination of the tracking/paging area according to  FIG. 20  or  FIG. 21 , respectively. In case of receiving schedule  100 , user entity  10  is able to check this schedule  100 . 
     Thus, the above examples of  FIGS. 19 to 21  reveal that it is possible to realize and autonomous UE handover decision in RRC inactive state for NR (in LTE called lightly connected) assuming the new context already exists in the new node (already received in the new node because of the predictive context forwarding). In other words, these embodiments enable a lightly connected mode of the UE with efficient paging using prediction information. 
     Efficient Paging using prediction information in Lightly Connected Mode as shown in  FIG. 19  entails the update of the centralized unit information and the Tracking Area Identifier (TAI) List of the various RAN paging/notification areas using the predicted route information of the UE when in RRC lightly connected mode (RRC Idle mode not precluded). The UE traditionally receives a TAI list when initially attaching to a source eNB in the LTE network. When the UE travels in a Tracking Area not contained in the TAI list, the UE sends a Tracking Area Update (TAU) informing the MME (core network) about its position. In order to enable to efficient paging using predicted route information, another solution is proposed whereby the UE does not require the transmission of updates to the anchor eNB or centralized unit when the UE changes RAN paging/notification areas: 
     1. The source/anchor eNB or centralized unit provides a near complete predicted RAN paging/notification area list (pPAI) list to the UE upon connection establishment, corresponding with the predicted route of the UE, avoiding the need to page multiple cells of the same paging area (See  FIG. 19 ) to locate the UE, thus reducing paging overhead. According to  FIG. 19 , the UE would receive a pPAI={PA1, PA2, PA3} corresponding to the predicted route. 2. To further increase paging efficiency in terms of finer granularity, another list containing the Target eNB IDs could also be provided. For example the target eNB list could contain, TeNBI={eNB-1, eNB-3, eNB-4, eNB-5, eNB-7} as seen in  FIG. 19 . When a DL message is waiting to be received in lightly connected mode, the anchor eNB or centralized unit need not page the PAs but rather the individual eNBs in the TeNBI list. 
     3. In the event, that the UE route abruptly changes the route and moves to a PA not on the pPAI, e.g. PA4 in  FIG. 19 , the UE notifies the anchor eNB or centralized unit using a paging area/RAN notification area update (PAU/RNAU). An example of additional predicted paging message parameters is shown in Table 1: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Example messages for predictive paging 
               
            
           
           
               
               
            
               
                 IE/Group Name 
                 Description 
               
               
                   
               
               
                 UE-Paging-Area-ID 
                 “This IE represents the Identity with which the 
               
               
                   
                 UE is paged.” [12] 
               
               
                 pPAI-List 
                 TA list corresponding to predicted route 
               
               
                 TeNBI-List-ID 
                 Identifiers of Target eNBs along predicted 
               
               
                   
                 route 
               
               
                   
               
            
           
         
       
     
     Thus, the above-described embodiment, inter alias, enabled a preemptive UE signaling based on predictive UE route information to perform a faster HO. Again, it is noted that this might be used also in UEs which are in a dual-connectivity mode. High reliability HO by using RRC diversity using route prediction and dual-connectivity mode is feasible. All the above embodiments can be applied to wireless communication systems, e.g., cellular, wireless or meshed wireless networks as well as wireless ad-hoc networks. 
     Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be executed by (or using) a hardware apparatus, like for example, a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important method steps may be executed by such an apparatus. 
     Depending on certain implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be performed using a digital storage medium, for example a floppy disk, a DVD, a Blu-Ray, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, having electronically readable control signals stored thereon, which cooperate (or are capable of cooperating) with a programmable computer system such that the respective method is performed. Therefore, the digital storage medium may be computer readable. 
     Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed. 
     Generally, embodiments of the present invention can be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer. The program code may for example be stored on a machine readable carrier. 
     Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier. 
     In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer. 
     A further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein. The data carrier, the digital storage medium or the recorded medium are typically tangible and/or non-transitionary. 
     A further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or the sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet. 
     A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein. 
     A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein. 
     A further embodiment according to the invention comprises an apparatus or a system configured to transfer (for example, electronically or optically) a computer program for performing one of the methods described herein to a receiver. The receiver may, for example, be a computer, a mobile device, a memory device or the like. The apparatus or system may, for example, comprise a file server for transferring the computer program to the receiver. 
     In some embodiments, a programmable logic device (for example a field programmable gate array) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor in order to perform one of the methods described herein. Generally, the methods may be performed by any hardware apparatus. 
     The apparatus described herein may be implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer. 
     The apparatus described herein, or any components of the apparatus described herein, may be implemented at least partially in hardware and/or in software. 
     The methods described herein may be performed using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer. 
     The methods described herein, or any components of the apparatus described herein, may be performed at least partially by hardware and/or by software. 
     While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which will be apparent to others skilled in the art and which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention. 
     LIST OF ACRONYMS AND SYMBOLS 
     In addition, reference is made to 3GPP TR 21.905: “Vocabulary for 3GPP Specifications”.
     eNB Evolved Node B (3G or 4G base station)   gNB NR node=next Generation NB (5G base station)   LTE Long-Term Evolution   NR New Radio   UE User Equipment (User Terminal)   HO Handover   P-HO Predicted Handover   RRC Radio Resource Control   MME Mobile Management Entity   V2V Vehicle-to-Vehicle   V2X Vehicle-to-infrastructure   SeNB Secondary eNB   MeNB Master eNB   

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