Patent Description:
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 requires, 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.

In <CIT>, systems and methods for adaptive access and handover configuration based on historical data are described. An operating environment predicts the need for a future handover based on a predicted travel path for a user device over a specified time period. The predicted travel path may be estimated using historical travel patterns for a user device.

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.

By way of informative examples, a concept for an improved handling of user entities which are not in an active state is also presented herein.

A prediction of a future route of a user entity may be used 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 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, 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 necessary 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 comparison example, an improved concept for serving a user entity via a cellular network is provided; namely, in a manner increasing the connectivity of the user entity.

Advantageous implementations of embodiments of the present application are the subject of the dependent claims. Preferred embodiments of the present application are described below with respect to the figures among which.

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/<NUM> 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 <NUM>, 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:.

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 <NUM> to the target eNB <NUM> as indicated in <FIG> or from a cell <NUM> of eNB <NUM> to a cell <NUM> of eNB <NUM>. 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:.

An overview of X2-based handover procedures based on <FIG> [<NUM>] is outlined below:.

However, when there is no X2 interface <NUM> between the eNBs (e.g. legacy eNBs <NUM> and <NUM> based on UTRAN architecture), or if the eNB <NUM> has been configured to initiate the handover towards a particular target eNB via the S1 interface <NUM> which connects the eNBs with the core network <NUM>, then the S1 handover procedure illustrated in <FIG> will be triggered. The S1-handover procedure consists of <NUM> basic phases:.

As an overview of S1-based HO Handover Procedures reference is made to [<NUM>]. For a detailed description also refer to the steps of the previous X2-based HO procedure.

As to Steps <NUM>-<NUM>, it is noted that some are special to the S1-based HO <NUM>, and comprise of acknowledgement and update information to the target MME.

Next, UE context transfer in <NUM> / <NUM> is referred to.

The radio resource control (RRC) context transfer is an important procedure of the HO process. The MME <NUM> as a part of the core network <NUM> creates a UE context when a UE <NUM> is switched on and subsequently attempts to connect to the network <NUM>. A unique short temporary identity is assigned, also known as the SAE Temporary Mobile Subscriber Identity (S-TMSI), to the UE <NUM> that identifies the UE context in the MME <NUM>. This UE context contains user subscription data originally obtained from a Home Subscriber Server <NUM> (HSS) also being part of the core network <NUM>. The local storage of subscription data in the MME <NUM> 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 [<NUM>]. During the P-HO process, the eNB <NUM> would be required to forward the UE's radio resource control (RRC) context to subsequent target eNBs such as eNB <NUM>.

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 necessary 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> shows in a manner reusing the reference numbers of <FIG> for entities fulfilling the same task in the overall system shown in <FIG>, a cellular network <NUM> comprising a plurality of base stations <NUM> spatially spread so that their cells <NUM>, within which each base station <NUM> serves user entities residing in the respective cell <NUM> so as to connect them to the cellular network <NUM> by wireless communication, cover a certain region or area such as a geographical region <NUM> in a manner so that cells <NUM> abut or overlap each other. The cells <NUM> are quasi-defined by the respective wireless communication reach of each base station <NUM>. The cellular network of <FIG> also comprises a core network via which, and to which, each base station <NUM> is connected via a respective interface <NUM> such as some cable based network such as electrical or optical cables. As already described with respect to <FIG>, the base stations <NUM> might be connected to each other directly, too, such as via interface <NUM> shown in <FIG> which might be cable-based or wireless such as an optical connection.

<FIG> also shows a user entity or user equipment <NUM>. It is currently served by base station <NUM>. That is, base station <NUM> is a special base station <NUM> with respect to UE <NUM>, namely the source base station <NUM>. That is, UE <NUM> is located within cell <NUM> of base station <NUM> and base station <NUM> communicates with the UE <NUM> via radio resources it assigns to UE <NUM>. The share of radio resources assigned to UE <NUM> depends on many factors such as subscriber data of UE <NUM>, number of further UEs currently served by base station <NUM> and so forth. It is assumed that UE <NUM> is currently in a connected or active mode. That is, UE <NUM> has, for instance, one or more current communication sessions running such as a call and/or data session. That is, the UE <NUM> 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 <NUM> over network <NUM> with some third party which might be an entity within the cellular network <NUM>, but may alternatively be a third party device being external to the cellular network <NUM> and connected to core network <NUM> via the Internet or some other external network <NUM>. The core network <NUM> or some entity within core network <NUM> such as MME <NUM> contains or manages a context for each UE <NUM> currently served within region <NUM>. For instance, such context or context data could indicate which sessions are currently active with respect to each UE, at which base station <NUM> the respective UE is served, i.e., via which base station <NUM> the respective UE is connected to the cellular network <NUM>, and/or further information such as subscriber data or the like. In order to associate such contexts with the associated UEs, core network <NUM> assigns identifiers to the UEs. The currently serving base station <NUM> also knows about, or stores, the context of UE <NUM> and knows about the ID used within core network <NUM> with respect to UE <NUM>. Based on the context data, core network <NUM> is able to forward packets of any communication session associated with UE <NUM> towards base station <NUM>, which, in turn, forwards the same wirelessly to UE <NUM>.

The cellular network <NUM> of <FIG> is configured to support a preemptive preparation of a handover for user entity <NUM>. This means the following. It might be, that cellular network <NUM>, optionally, has the afore-mentioned functionality of initiating a handover of UE <NUM> to another, i.e., a target base station; namely, one of the neighboring base stations neighboring base station <NUM>, on the basis of an evaluation of measurements made by the UE <NUM> which measure the connection quality between UE <NUM> and base station <NUM> as well as between UE <NUM> and any of the neighboring base stations <NUM>, provided the UE <NUM> is within the reach of the respective neighboring base station <NUM>. Such passive activation would mean that the cellular network <NUM> 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 <NUM> of <FIG>, however, supports a speculative or preemptive preparation of a handover for a user entity such as user entity <NUM>. When preemptively preparing a handover for user entity <NUM>, the cellular network <NUM> establishes, for each of a set of one or more target base stations 14a and 14b of the cellular network <NUM>, a temporal access interval and one or more access parameters so that the user entity <NUM> may access the cellular network <NUM> via the respective base station 14a, 14b 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 14a, 14b, the handover is, as far as the cellular network's side is concerned, already done. It is merely up to the UE <NUM> 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 14a, 14b is actually used by UE <NUM>. The target base stations 14a, 14b 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> 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>, the preemptive preparation of a handover is triggered at a time instant t<NUM>. In other words, at this time instant t<NUM>, the cellular network determines a preliminary set <NUM> 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 <NUM> of base stations is determined by the cellular networks so that their cells <NUM> cover an area where the UE <NUM> will probably move in the next future upon leaving the cell of current source base station <NUM>. As described later on, for instance, cellular network <NUM> may determine the preliminary set <NUM> depending on information on a predicted future route of the user entity. In <FIG> such a predicted future route is illustrated using a dashed line <NUM>. The same crosses the cells of base station <NUM>a and <NUM>b. <FIG> illustrates the preliminary set <NUM> to be composed of, generally, base stations <NUM><NUM>. <NUM>M with M≥N. The temporal length of the predicted future route <NUM> may cover a certain temporal interval <NUM> starting from time instant t<NUM> and lasting, for instance, for more than <NUM> seconds, <NUM> minute or even <NUM> minutes. The temporal length <NUM> might be determined variably as well and might be adapted, for instance, to the prediction accuracy of the predicted future route <NUM>. The cellular network might receive the information on the predicted future route <NUM> of the user entity <NUM> from the user entity <NUM> 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 <NUM> 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 <NUM> of the user entity <NUM> might come from a device other than the cellular network <NUM> and the user entity <NUM>. Such other device could be, for instance, a system which tracks the user entity <NUM>, but resides external to cellular network <NUM>. 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 ®. It might even be that the other device is responsible for granting allowance for the future route <NUM> 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 <NUM> may determine the predicted future route <NUM> of the user entity itself such as by triangulation applied onto signals sent by the UE <NUM> and received by several of the base stations <NUM> or the like, or by extrapolating path <NUM> from a past travel path of UE <NUM> defined by updates on the UE's current position which the network <NUM> receives from the UE <NUM>. The derivation of the predicted future route <NUM> 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 <NUM> such as a route taken by the UE <NUM> immediately up to time instant t<NUM>, map data indicating a map of region <NUM> such as a street map or the like, and/or user preference data associated with the UE <NUM> having been gathered based on an evaluation of routes taken by the UE <NUM> in the past. Preliminary set <NUM> would then be determined so that the base station's cells within the set <NUM> would be crossed by route <NUM>. The UE <NUM> is, thus, likely to need a handover at at least a subset of base stations of set <NUM>. It should be noted, however, that set <NUM> may, alternatively, be determined by the cellular network <NUM> by means other than based on an evaluation of predicted future route <NUM>. The predicted route <NUM> 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 <NUM> could be configured to request the route vector <NUM> as a kind of measurement report, including route updates and top-m routes e.g. route <NUM>, route <NUM>, route <NUM>,.

The use of route <NUM> for determining set <NUM> is not necessary. For instance, the mere fact or circumstance that UE <NUM> enters a certain predetermined area <NUM> may be an indicator that there is a high probability that the user entity <NUM> will be, during a certain time interval <NUM> following time instant t<NUM> at which the UE <NUM> entered area <NUM>, in a certain area, or will travel along a certain path or route so that set <NUM> could be automatically determined albeit fixedly associated with, the event of UE <NUM> entering area <NUM> at time instant t<NUM>. For instance, the area <NUM> could be one end of a street without any crossing until reaching, via a certain path <NUM>, namely the street, a first crossing and accordingly, as soon as the UE <NUM> enters the street at this point, it is very likely that the UE <NUM> will follow this route/street <NUM>. Similarly, imagine a UE <NUM> 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 <NUM> 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 <NUM> will be, during some time interval <NUM> following a time instant t<NUM>, 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<NUM>. In addition to the user entity <NUM> entering area <NUM>, for instance, a current heading direction of UE <NUM> 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 <NUM>. For instance, preemptive preparation of HO could be triggered by the user entity coming from predetermined area <NUM>. 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's position, current UE'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 <NUM> and/or any surrounding base station <NUM>.

That is, along with determining the preliminary set <NUM> of base stations, cellular network <NUM> determines for each base station within set <NUM> an expected time t<NUM>. tM at which the user entity enters the respective base station's cell <NUM>, i.e., is within its reach. Accordingly, base station <NUM>, i.e., the source eNB, queries each of the preliminary set <NUM> of target base stations regarding an accessibility of the cellular network <NUM> via the respective target base station at the respective expected time tI. As an outcome of this query, base station <NUM> of cellular network <NUM> receives from each of the preliminary set <NUM> of base stations, an answer to the query. While there may be none, one, or more than one base station within preliminary set <NUM> which denies the accessibility, there may be a set of base stations, let's say N base stations with N ≥ <NUM> and N ≤ M which answer the query by way of indicating a temporal access interval <NUM> at which the respective base station is accessible by user entity <NUM> provided that user entity <NUM> uses the one or more access parameters indicated by the respective base station in the answer to the query. For instance, <FIG> illustrates that a certain access interval <NUM> overlaps a first expected time t<NUM>. A base station of set <NUM> within the cell of which the user entity <NUM> is expected to be as time instant t<NUM>, thus, allows user entity <NUM> to access the cellular network <NUM> using one or more access parameters via correspondingly reserving respective access radio resources during time interval <NUM>. 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 <NUM> is, thus, able to send to the user entity <NUM> a schedule <NUM> which indicates, for each of the set <NUM> of one or more base stations for which a temporal access interval <NUM> and one or more access parameters <NUM> have been determined, the temporal access temporal interval <NUM> as well as the one or more access parameters. This schedule <NUM> indicates to the user entity <NUM> that the same may access the cellular network <NUM> via the respective base station <NUM>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 <NUM>. In other words, schedule <NUM> could be submitted as an ordered list of elements, the elements having a temporal dependency, or the schedule <NUM> could be submitted as a set of elements. An even alternatively, schedule <NUM> 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 <NUM> and the one or more access parameters <NUM>. Thereinafter, i.e. of submission of schedule <NUM> to UE <NUM>, 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 <NUM> to the user entity onwards, up to the user entity <NUM>, whether or not the user entity uses the access opportunities during intervals <NUM> 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 <NUM> from exploiting these opportunities because, for instance, the prediction of route <NUM> of the forecast on the basis of the event of UE <NUM> entering area <NUM>, 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 <NUM> and obtaining the answers up to sending schedule <NUM> may be negligible compared to the temporal length <NUM> within which the one or more expected times tI are distributed. The schedule <NUM> may define a certain temporal access <NUM> by indicating, for instance, its start time tx start wherein an end of the temporal access interval <NUM> could implicitly be defined by a maximum length of each interval <NUM>. In other words, the respective base station <NUM>x could close the access opportunity after a certain time after t x start. The temporal end of interval <NUM> could be indicated, too, however in the schedule <NUM>.

As described later on, the query sent from base station <NUM> to the target base stations of set <NUM> may possibly contain one or more current identifiers using which the user entity <NUM> is identified in the cellular network such as, for instance, an identifier via which the user entity <NUM> is identified in the core network <NUM> such as in the MME <NUM>. In particular, the query could additionally or alternatively inform the base stations of set <NUM> about the context data of user entity <NUM>. On the other hand, performing the preemptive preparation of the handover as just described could also additionally involve sending a schedule <NUM> such as a copy of schedule <NUM> from base station <NUM> to core network <NUM> such as MME <NUM> within core network <NUM> so as to schedule a redirection of packets of one or more communication paths for communication sessions of the user entity <NUM> over the cellular network <NUM> and the user entity <NUM> so that the packets are distributed to each base station of set <NUM> depending on the respective temporal access interval <NUM> of the respective base station in set <NUM>. In other words, MME <NUM> or the core network <NUM> would be able to plan, at an early stage; namely, at the time of receiving schedule <NUM>, a distribution of inbound packets arriving, for instance, from the external network, to base stations among set <NUM> other than the base station via which the user entity <NUM> is currently connected to cellular network <NUM>. Packets, for instance, which are likely to be buffered too long at a certain base station of set <NUM> and cannot be transmitted from that base station to the user entity <NUM> before the expected handover from that base station to the next base station of set <NUM>, may be forwarded by core network <NUM> or MME <NUM>, respectively, to the next base station of set <NUM> according to the sequence of expected times covered by the respective temporal access intervals <NUM>. The cellular network <NUM> would, first, not have to wait for such redirection until the handover actually takes place on behalf of UE <NUM> actually using the one or more access parameters it has been provided with by way of schedule <NUM>.

It should be noted that the cardinality of the set <NUM> and the cardinality of set <NUM> or the cardinality of either of these sets might be greater than <NUM>. Generally, however, both may be <NUM>, <NUM>. As to the future start time <NUM> indicated in schedule <NUM> to indicate the start of the respective temporal access interval <NUM>, 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 <NUM> is likely to handover from base station <NUM> to the target base station for which the temporally-nearest temporal access interval <NUM> is indicated in schedule <NUM>. That is, UE <NUM> will use the one or more access parameter <NUM> for this target base station which would, in the example illustrated in <FIG>, for instance, be the base station <NUM>a, during temporal access interval <NUM> and thus, would perform or activate the handover preemptively prepared as described so far. This base station <NUM>a would then inform base station <NUM> about the user entity having accessed the cellular network <NUM> via the base station <NUM>a and triggered by this information, base station <NUM> would cut its connection to UE <NUM>, while core network <NUM> would be informed by base station <NUM>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 <NUM> and the user entity <NUM>, from base station <NUM> to base station <NUM>a. Further, resources of the base station <NUM> via which the user entity <NUM> is currently or, better, has been so far, connected to the cellular network, here base station <NUM>, 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 <NUM>. Base station <NUM> could cut its connection to UE <NUM> 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 <NUM>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 <NUM> takes place.

Thus, with respect to <FIG>, a cellular network <NUM> has been described which supports a preemptive preparation of a handover for user entity <NUM>. Concurrently, however, the above description revealed a user entity <NUM> for communication over a cellular network <NUM>, wherein the user entity <NUM> is configured to gain information on a predicted future route <NUM> of the user entity and inform the cellular network on the predicted future route <NUM>. The UE could transmit a list or vector of coordinates, e.g. WGS84 coordinates, to the cellular infrastructure <NUM>. UE <NUM> could do this upon request from the base station <NUM>, 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 <NUM> may stem from an entity other than the user entity <NUM>. The information on the predicted future route <NUM> may be sent to cellular network <NUM>, for instance, as a set of pairs of time and coordinates of locations at which the user entity <NUM> is on the predicted future route <NUM>, or a sequence of coordinates of location sequentially traversed by the user entity along the predicted future route <NUM> such as locations which the user entity traverses along the predicted future route <NUM> 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 <NUM>, wherein the user entity <NUM> is configured to manage a set of one or more preemptively prepared handovers. In this way, the user entity <NUM> not necessarily informs the cellular network on the predicted future route <NUM>. In general, the user entity <NUM> 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/<NUM>, 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 <NUM> may be able to manage a set of one or more preemptively prepared handovers; namely, those indicated in schedule <NUM> which user entity <NUM> receives from the cellular network <NUM> and the source base station <NUM>, respectively. From the reception onwards, i.e., substantially over the whole time interval <NUM>, the user entity <NUM> continuously checks whether the schedule <NUM> becomes inadequate. For instance, the user entity recognizes that the user entity gets farther away from the predicted future route <NUM> because, for instance, the user of the user entity <NUM> decided to take another way than rule <NUM>. In that case, user entity could inform the cellular network <NUM> on the inadequateness so that, for instance, cellular network <NUM> could inform the target base stations of set <NUM> 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 <NUM> the temporal access interval <NUM> plus associated one or more access parameter <NUM> per target base station within set <NUM> and then, from the reception of schedule <NUM> onwards, continuously decide on accessing the cellular network <NUM> via any of this set <NUM> of target base stations; namely, any base station of the set <NUM> within a reach of which the user entity <NUM> currently is. Obviously, this decision is merely available during the temporal access interval <NUM> associated with a respective target base station, annually using the one or more access parameters specified in the schedule. The user entity <NUM> is able to perform a handover or access of the cellular network using schedule <NUM>, or perform the just described continuous decision thereabout, without obtaining current permissions from the cellular network <NUM> on a case by case basis, i.e., without obtaining current permission during time interval <NUM>. Schedule <NUM>, instead, serves as a license for user entity to perform each handover during the respective time interval <NUM>.

As described later on in more detail, user entity <NUM> may be configured to perform the management of the set of one or more preemptively prepared handovers as outlined in schedule <NUM> with respect to one or more wireless connections to the cellular network <NUM> of a set of current wireless connections to the cellular network <NUM>. For instance, user entity <NUM> 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 <NUM> 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>, 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 <NUM> of base stations around the position of the user entity with respect to a set of possible routes leading away from the user entity'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 <NUM> of target base stations with the set <NUM>, however, covering more than one route, i.e., a set of possible routes leading away from the current user entity's position. The target base stations of set <NUM> would, thus, be determined to cover all routes in the set of possible routes. The target base stations of set <NUM> would answer the query and based on these answers, cellular network <NUM> 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 <NUM> plus associated one or more access parameters <NUM>. 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 <NUM> could inform the user entity <NUM> about the favorite route actively or upon request or polling by the UE <NUM>. For instance, currently serving base station <NUM> could provide a download link, so that the UE <NUM> or its user can decide itself to update its route. In other words, base station <NUM> or cellular network <NUM> could push this information to the UE. Alternatively, the UE <NUM> could download or pull this information on the favorite route from the cellular network <NUM>. 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 <NUM>, and the user could decide, as the bearer of the user entity <NUM>, 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 <NUM> 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 <NUM>. That is, any base station <NUM> could have this functionality. The functionality could, however, by realized in other device of the cellular network <NUM>.

The above techniques may 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 <NUM>-<NUM> [<NUM>]. As a result, there is room to improve the efficiency of the overall HO process for <NUM> use cases, including low latency communications. This may be done as 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 concepts. 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 <NUM> necessary to connect to the target eNB/gNB before the actual HO process. <FIG> 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 <NUM> to signal the UE <NUM> with the target eNB/gNB parameters <NUM> (e.g. RRCConnectionReconfiguration including the mobilityControllnfo message), examples of which are outlined in the table shown in <FIG>.

In even other words, the concepts 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> and <FIG>):.

In particular, the NW or UE <NUM> 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 <NUM> of a set <NUM> of target cells along a predicted route <NUM> that are signaled to a UE <NUM>, before a HO actually takes place. The UE <NUM> 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 <NUM> to perform a P-HO. Two options are considered for driving the P-HO:.

Therefore, the source eNB or centralized entities (e.g., CRRM, CBBU, MME) can initiate the multiple predictive HO preparation for N≥<NUM> target eNBs <NUM> along the predicted UE trajectory <NUM>. 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 required resources have been pre-allocated. The resulting P-HO scheme aims to reduce signaling overhead and latency, once information about the predicted route <NUM> has been established. The N expected target eNBs <NUM> will expect the UE <NUM> to reach its cell within a pre-defined interval <NUM> (valid time interval) based on the initial setup time t<NUM> of the N-hop predictive HO procedure and a UE mobility type (e.g. high or low speed). If the UE <NUM> abruptly changes trajectory or remains stationary at a particular target cell, then all target eNBs/gNBs <NUM> 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>. The embraced portion <NUM> indicates the signaling scheme specific for the P-HO scenario. The P-HO procedure is triggered by the centralized entities such as <NUM> or source eNB/gNB <NUM> when the UE <NUM> is either in the proposed active (NR) and normal RRC connected states (LTE) as shown in the state diagram (<FIG>) [<NUM>]. When the UE <NUM> 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 required 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.

<FIG> 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>.

A more detailed exemplary message description is presented below:
Message <NUM>: 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:.

Message <NUM>: 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).

Message <NUM>: The response from the target eNB can acknowledge or deny the request via S1/X2 to the requesting 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 → centralized Unit).

Message <NUM>: The table shown in <FIG> is a summary of the required 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 require 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.

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-<NUM>, we have the out-of-coverage scenario shown in <FIG>. 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 <NUM>: 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 <NUM>: 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.

Step/Description <NUM>: 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.

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:.

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.

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 <NUM> 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> is an example of the lightly connected state mode of operation as proposed in [<NUM>].

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 [<NUM>]. 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).

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>.

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> with a new additional entity known as the V2X application server [<NUM>].

The core functionality V2X Application Server is out of scope of 3GPP [<NUM>], and an overview of the role of the Application server has been defined by the ITS. According to the definition in [<NUM>], 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 [<NUM>]. Currently the V2X application server has the following specifications according to 3GPP, which fall in line with ETSI's proposal [<NUM>]:.

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.

Dual-connectivity (DC) was included as part of small cell enhancements in LTE and offers several advantages which include [<NUM>]:.

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 always one active/inactive. The data split in the User-plane can take place at the bearer or packet level as shown in <FIG> and <FIG> [<NUM>].

"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 mobilityControllnformation 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 #<NUM> 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.

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 comparison examples with respect to this aspect, reference is made to <FIG> 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> shows a cellular network <NUM> which is, as discussed with respect to <FIG>, composed of a plurality of base stations <NUM> spread so as to cover with their associated cells <NUM> a certain region or geographical area, wherein the base stations <NUM> serve UEs within their cells in that the same perform the wireless communication with the UEs within their cells. The base stations <NUM> are connected via some interface <NUM> with the core network <NUM> of cellular network <NUM>. This core network <NUM> in turn, may have an interface towards an external network <NUM>. With respect to activated UEs, i.e., UEs which are currently connect to the cellular network <NUM> via a current source base station, the behavior of cellular network <NUM> and the UEs communicating via cellular network <NUM> of <FIG> may be as described with respect to <FIG> or, optionally, in accordance with the current solutions discussed above with respect to <FIG>. The cellular network <NUM> of <FIG>, however, is configured to establish for a predetermined user entity <NUM> 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>. <FIG> and <FIG> assume that the base stations <NUM> are spatially pre-clustered into so-called "paging areas" <NUM>. Four such clusters or spatially-neighboring base stations <NUM> are exemplarily shown in <FIG>. It should be noted, however, that this clustering is not mandatory. As shown in <FIG>, the cellular network <NUM> determines, at some time instant t<NUM>, for a UE <NUM>, a time-varying tracking/paging area. The time instant t<NUM> might, for instance, be initiated by UE <NUM> 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<NUM> based on some sort of prediction similar to thoughts which led to set <NUM> in <FIG>. For instance, the tracking/paging area may be defined to follow a predicted future route <NUM> of UE <NUM>, i.e., to follow the position the UE <NUM> has predicted to assume in route <NUM>. The outcome of such determination is shown in <FIG> as a schedule <NUM>. In particular, schedule <NUM> defines, for each time instant within some time interval <NUM> which follows time instant t<NUM>, the set of one or more base stations <NUM> which form the tracking/paging area, i.e., set <NUM>. In <FIG> it is exemplified that schedule <NUM> indicates the set <NUM> in units of clusters <NUM>, but this might be solved differently. In particular, schedule <NUM> indicates this set for consecutive partial intervals <NUM>, into which the time interval <NUM> is sub-divided. That is, for each such partial interval <NUM>, schedule <NUM> indicates the set <NUM> of base stations <NUM> which make up the tracking/paging area. Alternatively, the UE <NUM> 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 <NUM>.

The cellular network <NUM> then sends the schedule <NUM> or messages intermittently updating area <NUM> to the user entity <NUM> which, thus, is able to continuously check whether the UE <NUM> leaves this time-varying tracking/paging area defined by the time-varying set of one or more base stations <NUM> 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 <NUM> expects the UE <NUM> to be. As long as the UE <NUM> does not wish to initiate an uplink communication and to switch to active mode, the UE <NUM> needs to do nothing. The cellular network <NUM>, 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 <NUM>. In particular, the cellular network <NUM> provides each base station of set <NUM>, i.e., each base station currently within the set <NUM> of base stations which define the tracking/paging area, with context data of UE <NUM> so that these base stations are aware, for instance, of the UE's <NUM> subscriber data currently active one or more communication sessions, one or more IDs used by the cellular network <NUM> to identify UE <NUM> and distinguish UE <NUM> from other UEs and/or other UE specific data. Further, cellular network <NUM>, itself, uses schedule <NUM> so as to search for UE <NUM> whenever an inbound or downlink packet of one of one of more active communications sessions arrives at the core network <NUM> addressed to UE <NUM>. In particular, the cellular network <NUM> then looks up in schedule <NUM> which set <NUM> of base stations currently makes up or defines the tracking/paging area and informs via these one or more base stations that the UE10 should connect to the cellular network <NUM> 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 <NUM> of which the UE <NUM> currently is, belongs to the set <NUM> defining this tracking/paging area and this base station already has at hand the context data of UE <NUM>.

It should be noted that, according to an alternative, the cellular network of <FIG> does not form a schedule <NUM> of a time-varying tracking/paging area. Rather, as depicted in <FIG>, according to this alternative, the cellular network <NUM> uses the gained knowledge about the predicted future route <NUM> so as to appropriately select the set <NUM> of one or more base stations which define the tracking/paging area. As long as the UE is within this area <NUM> which has precisely been predicted using predicted future route <NUM>, control signaling overhead on the side of the UE which could negatively impact the power consumption of UE <NUM>, may be avoided. In the example of <FIG>, cellular network <NUM> sends to the UE <NUM> the set <NUM>. In both alternatives discussed above with respect to <FIG>, the user entity <NUM> is a user entity for communication over cellular network <NUM> and the user entity <NUM> is configured to continuously check whether it is still in the tracking/paging area defined by the set <NUM> of one or more base stations or whether the user entity has left the same. In case of leaving, the user entity <NUM> sends a tracking/paging area update message to the cellular network <NUM> which, in turn, then re-initiates the determination of the tracking/paging area according to <FIG>, respectively. In case of receiving schedule <NUM>, user entity <NUM> is able to check this schedule <NUM>.

Thus, the above examples of <FIG> 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 comparison examples 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> 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:.

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>) to locate the UE, thus reducing paging overhead. According to <FIG>, the UE would receive a pPAI={PA1,PA2,PA3} corresponding to the predicted route. 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, TeNBl={eNB-<NUM>,eNB-<NUM>, eNB-<NUM>, eNB-<NUM>, eNB-<NUM>} as seen in <FIG>. 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. 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>, 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 <NUM>:.

Thus, the above description, 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.

The above described embodiments are merely illustrative for the principles of the present invention. It is understood that modifications and variations of the arrangements and the details described herein will be apparent to others skilled in the art. It is the intent, therefore, to be limited only by the scope of the impending patent claims and not by the specific details presented by way of description and explanation of the embodiments herein.

Claim 1:
Cellular network supporting a preemptive preparation of a handover for a user entity, wherein the cellular network is configured for determining a preliminary set (<NUM>) of more than one base station of the cellular network;
sending a query from a centralized unit of the cellular network to each of the preliminary set of more than one base station of the cellular network regarding an accessibility of the cellular network via the respective base station at an expected time at which the user entity enters a cell of the respective base station;
sending an answer from the respective base station to the centralized unit;
performing the preemptive preparation of the handover by establishing, for each of the set of more than one base station of the cellular network,
a temporal access interval (<NUM>) and
one or more access parameters (<NUM>) and
performing or activating the preemptively prepared handover and accessing, by the user entity, the cellular network via the respective base station during the temporal access interval using the one or more access parameters.