RU2781810C2 - Proactive preparation for handover and processing of tracking/search call area and smart route selection in cellular network - Google Patents

Abstract

FIELD: wireless communication.

SUBSTANCE: cellular network supports proactive preparation of handover for a user communication node.

EFFECT: reduction in service load of control signaling, when performing handovers in cellular networks.

22 cl, 21 dwg, 6 tbl

Description

The present invention relates to a principle for handovers in cellular networks, a principle for advanced processing of RAN tracking/paging/notification areas, for example, for user nodes in idle modes, and a principle for providing intelligent route selection in cellular networks.

Handovers of connections, such as an ongoing call or data session, or a user node from cell to cell, are a frequently occurring process, and the control signaling used to establish such handovers consumes a significant amount of available radio and network resources and currently has an undesirably high latency. for high reliability transmissions. Any reduction in control signaling overhead and/or latency would be desirable.

Handovers occur in the activated mode of the user node. However, most of the time, the user nodes are not in the active mode, or in other words, most of the time, the user node does not need to continuously transmit data, but on the contrary, intermittently or from time to time, packets of a data session are to be transmitted to/from the user node. . In such a case, continuous handover may not be required as long as the user node is in a certain tracking/paging area. Only by leaving the tracking/paging area does the user node inform the cellular network of its new location or position. However, for this, the user node requires energy and, accordingly, it would be desirable to have a principle at its disposal to reduce its energy consumption.

The present invention provides, in accordance with the first aspect of the present invention, a principle for advanced handovers in a cellular network. This problem is solved 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 the second aspect of the present invention, the present invention provides a principle for improved handling of user nodes that are not in an active state.

One idea behind some of the embodiments of the present invention in accordance with the first and second aspects aims to achieve the above improvements, using user node future route prediction to improve handover handling and/or idle user node handling, respectively. In particular, the ability to use the predictive future route of the user node allows proactive preparation of one or more handovers on the cellular network side. This in turn reduces the control data overhead and/or reduces latency due to handovers. Such predictive future routes can also be used to advantage, for example, by establishing a time-varying tracking/paging area in which the user node is allowed to remain without the need to constantly update the cellular network in a particular cell in the tracking/paging area where it is currently the user node is located. This, in turn, can reduce the power consumption that occurs at the user node to indicate to the cellular network any exit from the tracking/paging area, since the tracking/paging area can better adapt to the actual route of the user node.

An additional idea underlying some of the embodiments of the present invention in accordance with the first aspect is that pre-emptive handover provisioning can reduce the amount of control signaling for handovers, and depending on these situations where such pre-proactive handover preparation is performed, it is possible the waste of network resources, which may be due to proactive preparation of handovers, to, for example, fulfill some promise that the user node will be able to access the cellular network in a predetermined access time interval using one or more access parameters at some base station of the cellular network, may remain relatively low. In particular, the proactive preparation of handovers makes it possible, in the short to medium term, to get rid of control signaling for handovers that are very likely to occur against some user node. This, in turn, reduces control signaling at base stations that have been proactively prepared for handover and reduces or eliminates latency that might otherwise occur due to, for example, handover-related protocol signaling that must then occur. at any time just before the user node attempts to move to the next cell. Naturally, this idea can be combined with the first idea to improve the selection of the set of base stations for which pre-handover preparation is performed. Additionally or alternatively, the fact that the user node enters the predetermined zone can be identified as the case where the proactive handover preparation is successful. For example, such a predetermined area may be associated with a very high probability that a user node, in the near future, will enter a cell of a predetermined other, i.e. target base station, and accordingly performing proactive handover preparation to that base station, can advantageously reduce otherwise occurring handover latency and/or control signaling associated with handover.

Also additionally or alternatively, a further idea underlying some embodiments of the present invention in accordance with the first and second aspects is that some form of scheduling the tracking/paging area and/or handovers with respect to time makes it possible to reduce the control signaling that had would be the case if scheduling were replaced by passively triggering otherwise necessary updates and handovers of the tracking/paging area, namely only when necessary. This idea can obviously also be combined with the idea of using a user node's future route prediction.

In accordance with a further aspect of the present invention, the present invention provides an improved concept for serving a user node over a cellular network; namely, by increasing the communication capability of the user node. This problem is solved by the subject matter of the independent claim of the third aspect.

In particular, the idea on which the embodiments of the third aspect are based is that the analysis of a predetermined set of cells around the position of the user node in relation to the set of possible routes leading from the position of the user node to determine - in relation to some predetermined criterion or criteria - the most preferred route from the set of possible routes in terms of the user node's ability to communicate and provide the user node with the most preferred route information can be used to enable users of such user node to consider this most preferred route when planning their next move; namely, taking into account the possibility of communication of the user node and the margin of time. The route thus selected may, for example, be referred to as the best route built/maintained.

Advantageous implementations of the embodiments of the present invention are the subject of the dependent claims. Preferred embodiments of the present invention are described below with reference to the drawings, in which

fig. 1 is a block diagram showing a cellular network and a UE in a cellular network to illustrate handover (HO)

fig. 2 - the time order of the steps carried out in the process of handover; namely, the HO procedure based on X2 according to [1] [6], in which the circuit in FIG. 3 differs by placing the different nodes participating in the HO procedure side by side between the party or node on which a certain step is performed or from where a certain signal is sent at a certain step, while the number of stages presented in FIG. 2 is equal to 12;

fig. 3 is a temporal order of steps similar to FIG. 2, but here the HO procedure based on S1 according to [1];

fig. 4 is a block diagram showing a cellular network and a UE communicating with it, wherein FIG. 4 also shows that the UE is currently connected to the cellular network via the source base station and is moving to other base stations of the cellular network, which thus form the target base stations to be handed over, the cellular network, the UE and the base stations stations shown in Fig. 4 can be implemented according to the present invention;

fig. 5 is a diagram showing proactive handovers implemented by the nodes shown in FIG. 4 according to the embodiment;

fig. 6 is a block diagram showing a cellular network, UEs, and signaling used to implement proactive handover preparation in the LTE framework;

fig. 7 is a table showing possible signaling of pre-arranged handovers according to an embodiment;

fig. 8 is a sequence of steps for performing a pre-arranged handover similar to the illustration used in FIG. 2 and 3, in accordance with an embodiment of the present invention.

Fig. 9 is a block diagram of a predictive handover (P-HO) architecture and an overview of the message flow in accordance with an embodiment;

fig. 10 is a flow chart showing an example of an out-of-coverage HO process;

fig. 11 is a diagram showing the state machine connection modes discussed in RAN2 for reduced signaling traffic, where reference is made to R2-168345 [3];

fig. 12 is a diagram showing the clustering of cells of base stations into tracking areas separated by tracking/paging area boundaries known, for example, from [11]; in other words, the Non-Access Layer (NAS) as indicated in FIG. 12;

fig. 13 is a block diagram of the RN architecture according to [7];

fig. 14 is a block diagram of a V2X broadcast architecture according to [8] as an example where embodiments of the present invention can be advantageously used;

fig. 15 is a block diagram of an eNB V2X type roadside unit developed at the edge as an example of how to accelerate the prediction of the HO process;

fig. 16 is a diagram showing data separation at the bearer level according to [11];

fig. 17 is a diagram showing data separation at the packet level according to [11];

fig. 18 is a sequence of steps carried out in the DC sequence diagram according to [12], the sequence of steps being illustrated similarly to the sequence of steps in FIG. 2 and 3;

fig. 19 is a block diagram of a cellular network, UEs, and participating base stations in accordance with embodiments of the present invention, where idle UEs are efficiently handled using intelligent tracking/paging;

fig. 20 is a diagram showing the mode of operation of the nodes involved in the decoration of FIG. 19 according to an embodiment where a time-varying tracking/paging area is used; and

fig. 21 is a diagram showing the operation mode of the nodes involved in the decoration shown in FIG. 19 according to an embodiment where the tracking/paging area is determined depending on the predicted future route of the UE.

The following describes various embodiments of the present invention. These embodiments relate to different aspects of the present invention, namely, the aspect of efficiently handling handovers, the principle of efficiently managing tracking/paging areas in which user nodes can be efficiently located in idle mode, and the principle of enabling users of user nodes to consider the goal of good communication capability. when choosing a route in the future.

The description of these embodiments begins with an introduction and technical overview regarding the first principle relating to handovers. In general, a base station may be referred to as an eNB (in the context of LTE) or gNB (in the context of NR/5G). In the following, no distinction is made between these three terms. The user terminal/mobile user may be referred to as user equipment or user node (UE).

Loss of communication capability may occur during 5G New Radio (NR) handovers, especially in traffic cases such as cars, buses, trucks, autonomous driving, drones and unmanned aerial vehicles (UAVs), airplanes, etc. d. The problem is threefold:

1. The number of vehicles is increasing, resulting in an increase in the need for signaling for handover (HO) processes,

2. New mobility services, such as driving assistance, etc., have new service requirements for traffic patterns, such as reliability constraints, including burst error rates (PER), bandwidth requirements, and packet sizes (for example, a large number of small control packages) as well as more stringent latency restrictions,

3. Conventional handover (HO) is not fully optimized because location information (indoor and outdoor) as well as traffic routes have increased significantly in recent years and can predict the routes of UEs connected to the cellular infrastructure. This is more applicable to stand-alone cloud-capable UEs that have tight wireless communications.

Significant HO overhead occurs when vehicles move rapidly between different cells during a given period. It would be useful to improve mobility services for automotive/aeronautical UEs that are in connected/active or loosely connected/idle mode, especially in vehicle-to-infrastructure (V2X), vehicle-to-vehicle (V2V) and unmanned aerial vehicles (UAVs).

These services need to be enhanced to improve the performance and reliability of the handover (HO) procedure through signaling procedures that, in particular, introduce prediction and improve the reliability of the UE context transfer to target eNBs during the predictive HO procedure.

Current HO procedures in LTE are designed to support scenarios where the UE transitions from source eNB 12 to destination eNB 14 as indicated in FIG. 1 or from cell 16 of eNB 12 to cell 18 of eNB 14. This invention focuses mainly on intra-RAT HO procedures while inter-RAT mobility is not eliminated.

There are two types of HO procedure in LTE for a UE in active mode:

1. X2 handover procedure,

2. S1 handover procedure.

1. HO based on X2: The X2 handover procedure is shown in FIG. 2 and is normally used for intra-eNB handover. The handover is performed directly between the two eNBs via the X2 interface 20 connecting both eNBs 12 and 14, which speeds up the preparation phase. The MME as part of the core network 24 of the cellular network 24, which also contains the eNBs 12 and 14, is only informed at the end of the HO procedure 26, after the successful completion of the HO to start the path switching. The release of resources on the source side is triggered directly from the target eNB. The X2 handover procedure 26 consists of 3 main phases:

1) preparation phases 26a (steps 4-6),

2) execution phases 26b (steps 7-9),

3) completion phase 26c (after step 9).

The following is an overview of X2 based handover procedures based on FIG. 2 [6]:

1. Source eNB 12 contains a UE context that consists of information related to inter-area roaming and access restrictions and was originally provided during connection setup or tracking area (TA) update.

2. The UE measurement procedures can be configured via the SeNB and implemented using the UE's connection mobility.

3. The source eNB receives the measurement report from the UE as well as radio resource scheduling (RRM) information to perform decision making at the HO.

4. The source eNB issues an HO request message to the target eNB containing the necessary information to prepare the HO on the target side. This information may include a reference to the X2 signaling context of the UE at the source eNB, a reference to the signaling context of the EPC (Evolved Packet Network Core) S1 UE, a target cell ID, K _eNB* , an RRC (Radio Resource Control) context including C- RNTI (Cell Radio Network Temporary Identifier) of the UE at the source eNB, AS (Access Layer) configuration, E-RAB (E-UTRAN Radio Access Bearer) Context and Source Cell Physical Layer ID+Short MAC-I (Message Authentication Code) to recover after a possible RLF (radio link failure). UE X2/UE S1 signaling links allow the target eNB to access the source eNB and the EPC. The E-RAB context includes the necessary RNL (Radio Network Layer) and TNL (Transport Network Layer) addressing information and E-RAB QoS (Quality of Service) profiles.

5. Resource establishment basically configures resources to query whether the target eNB can provide resources, and also performs admission control on the received E-RAB QoS information to increase the probability of successful HO. ʺThe target eNB configures the necessary resources according to the received E-RAB QoS information and reserves the C-RNTI and optionally the RACH preamble. The AS configuration to be used in the target cell may be set either independently (ie, "setup") or as a delta compared to the AS configuration used in the source cell (ie, "reconfigure")'.

6. The target eNB prepares the HO with L1/L2 and sends a handover request acknowledgment to the source eNB. The handover request acknowledgment message includes a transparent container to send to the UE as an RRC message for handover. The container includes the new C-RNTI, the target eNB's security algorithm identifiers for the selected security algorithms, may include a specific RACH preamble, and possibly some other parameters ie. access parameters, SIB, etc. The handover request acknowledgment message may also include RNL/TNL information for relay tunnels, if necessary. Note: As soon as the source eNB receives the handover request acknowledgment, or as soon as the transmission of the handover command is initiated on the downlink, data relay may be initiated.ʺ

7. 'The target eNB generates an RRC message for handover, ie. an RRC connection reconfiguration message including mobility control information to be sent by the source eNB to the UE. The source eNB provides the necessary integrity protection and message encryption. The UE receives the RRC Connection Reconfigure message with the necessary parameters (i.e., new C-RNTI, target eNB Security Algorithm Identifiers and optionally specific RACH preamble, target eNB SIB, etc.) and receives the command from the source eNB exercise HO. The UE does not have to delay handover to deliver HARQ/ARQ responses to the source eNB.

8. ʺThe source eNB sends an SN (Sequence Number) Status Transfer message to the target eNB to transfer the uplink PDCP (Packet Data Convergence Protocol) SN sink status and E-RAB downlink PDCP SN transmitter status, for which PDCP status retention applies (i.e. for AM (handshake mode) RLC). The PDCP status of the uplink SN receiver includes at least the PDCP SN of the first missed UL SDU, and may include a receive status bitmap from a sequence of UL SDUs that the UE needs to retransmit in the target cell, if any such SDUs are present. The downlink PDCP SN transmitter status indicates the next PDCP SN that the target eNB should assign to new SDUs not yet having a PDCP SN. The source eNB may skip sending this message if none of the E-RAB UEs should be processed while maintaining PDCP status.ʺ

9. When the UE successfully accesses the target cell, the UE sends an RRC Connection Reconfiguration Completion (C-RNTI) message to confirm handover, together with an uplink buffer status report, if possible, to the target eNB to indicate that the handover procedure for UE is completed. The target eNB checks the C-RNTI sent in the RRC Connection Reconfiguration Completion message. The target eNB can now start sending data to the UE.

10. ʺThe target eNB sends a path switch request message to the MME to inform that the UE has changed cell.ʺ

11. The ʺMME acknowledges the Path Switch Request message with a Path Switch Request Acknowledge message.ʺ

12. By sending a context release message to the UE, the target eNB informs the source eNB of the success of the HO and triggers resource release on the source eNB. The target eNB sends this message after receiving a path switch request acknowledgment message from the MME.

However, in the absence of an X2 interface 20 between the eNBs (eg, legacy eNBs 12 and 14 based on the UTRAN architecture), or if the eNB 12 is configured to initiate handover to a particular target eNB via the S1 interface 28 that connects the eNB to the core network 22, then the handover procedure S1 shown in FIG. 3. The S1 handover procedure consists of 3 main phases:

1) provisioning phases 30a involving the core network, such as EPC, where resources are first provisioned on the target side (steps 2-8),

2) execution phases 30b (steps 8-12),

3) completion phase 30c (after step 13).

For an overview of S1-based HO handover procedures, reference should be made to [6]. For a detailed description, one should also refer to the steps of the previous HO procedure based on X2.

With respect to steps 13-15, note that some are specific to HO 30 based on S1, and contain acknowledgment and updating information to the target MME.

Next, consider UE context transfer in 4G/5G.

Radio Resource Control (RRC) context transfer is an important procedure of the HO process. The MME 32, as part of the core network 22, creates a UE context when the UE 12 turns on and then attempts to join the network 24. A unique short temporary identifier, also known as an SAE temporary mobile subscriber identity (S-TMSI), is assigned to the UE 12, which identifies the context. UE in the MME 32. This UE context contains the user's subscription data originally received from the home subscriber server (HSS) 34, also part of the core network 22. Local storage of the subscription data in the MME 32 allows faster procedures such as bearer setup, since this eliminates the need to refer to the HSS each time. In addition, the UE context also contains dynamic information, such as a list of installed bearers, and terminal capabilities [2]. During the P-HO process, eNB 12 will need to relay the UE's Radio Resource Control (RRC) context to subsequent target eNBs, such as eNB 14.

Having described, quite generally, the task of handovers in cellular networks and how these handovers were handled previously in LTE, in the following, the description of the present invention provides a presentation of embodiments related to this task, which achieve an improvement in these handover mechanisms previously used in LTE in relation to the necessary overhead control signaling loads on one side and/or handover latency on the other side.

We now turn to a description of how some of the embodiments may be implemented in, or implemented to address, various features currently associated with mobile networks.

In FIG. 4 using the reference numerals of FIG. 1 for nodes performing the same task in the overall system shown in FIG. 4, a cellular network 24 is shown comprising a plurality of base stations 11 spatially distributed such that their cells are 15, in which each base station 11 serves the user nodes present in the corresponding cell 15 to connect them to the cellular network 24 via wireless communication, coverage some area or zone, such as geographic area 40 such that cells 15 are adjacent or overlapped with each other. Cells 15 are quasi-defined by the respective wireless range of each base station 11. The cellular network in FIG. 4 also contains a core network through which, and with which, each base station 11 is connected via a respective interface 28, such as some cable network, such as electrical or optical cables. As already described with reference to FIG. 1, the base stations 11 can also be directly connected to each other, for example via the interface 20 shown in FIG. 1, which may be wired or wireless, such as an optical connection.

In FIG. 4 also shows/o the user node or user equipment 10. It is currently served by the base station 12. Thus, the base station 12 is a special base station 11 in relation to the UE 10, namely the source base station 12. That is, the UE 10 resides in cell 15 of base station 12, and base station 12 communicates with UE 10 via the radio resources it assigns to UE 10. The sharing of the radio resources assigned to UE 10 depends on many factors, such as UE 10 subscriber data, number of additional UEs, currently served by base station 10, and so on. It is assumed that UE 10 is currently in connected or active mode. Thus, UE 10 is running, for example, one or more ongoing communication sessions, such as a call and/or data session. Thus, UE 10, which may be a mobile phone, laptop computer, or some other mobile or stationary device, may be running one or more applications, such as computer programs, etc., that communicate through base station 12 over a network. 34 with some third party, which may be a node in the cellular network 24, but alternatively may be a third party device external to the cellular network 24 and connected to the core network 34 via the Internet or some other external network 42. Core network 34 or some node in core network 34, such as MME 32, maintains or administers a context for each UE 10 currently served in area 40. For example, such context or context data may indicate which sessions are currently active with respect to each UE, on which base station 11 is served by the corresponding UE, i. e. through which base station 11 the respective UE is connected to the cellular network 24, and/or additional information such as subscriber data and the like. To associate such contexts with respective UEs, core network 34 assigns identifiers to the UEs. The currently serving base station 12 also knows or stores the context of the UE 10 and knows the ID used in the core network 34 in relation to the UE 10. Based on the context data, the core network 34 is able to relay the packets of any session associated with the UE 10 to the core station 12, which in turn relays them wirelessly to UE 10.

Cellular network 24 in FIG. 4 is capable of supporting proactive handover preparation for the user node 10. This means the following. It is possible that the cellular network 24 optionally has the aforementioned functionality of initiating a handover of a UE 10 to another, i.e. target base station; namely, one of the neighboring base stations adjacent to the base station 12, based on the evaluation of the measurements performed by the UE 10, which measure the quality of the connection between the UE 10 and the base station 12, and between the UE 10 and any of the neighboring base stations 11, when provided that the UE 10 is within range of the corresponding neighbor base station 11. Such passive activation means that the cellular network 24 concludes that a handover to such a neighboring target base station will take precedence according to some criteria, such as connection quality and/or or other criteria. However, the cellular network 24 shown in FIG. 4 supports hypothetical or proactive handover preparation for a user node, such as user node 10. When preparing a proactive handover for user node 10, cellular network 24 sets, for each of the set of one or more target base stations 14a and 14b of cellular network 24 , an access timeslot, and one or more access parameters, which allows the user node 10 to access the cellular network 24 through the respective base station 14a, 14b during the access timeslot using one or more access parameters set for the respective base station. This means that for such a set of base stations 14a, 14b, handover, from the point of view of the cellular network, has already been performed. It is up to UE 10, or other circumstances further discussed below, to determine whether UE 10 actually uses the access opportunity provided during access timeslots using one or more access parameters for base stations 14a, 14b. The pre-handovered target base stations 14a, 14b reserve some access channel or radio access channel using one or more access parameters set for the corresponding base station during the access time interval.

To better understand this, let us turn to FIG. 5. In FIG. 5 shows a process for preemptively preparing a handover by establishing an appropriate access time slot and one or more access parameters for one or more target base stations by showing a time sequence of steps performed during an access time slot t. As shown in FIG. 5, preemptive handover preparation starts at time t ₀ . In other words, at this time t ₀ , the cellular network determines a pre-set 50 of one or more base stations of the cellular network that can be proactively prepared for handover. This base station pre-set 50 is determined by the cellular networks such that their cells 15 cover the area where the UE 10 is likely to move in the future when leaving the cell of the current source base station 12. As described below, for example, the cellular network 24 may determine the pre-set 50 depending on information about the predicted future route of the user node. In FIG. 4, such a predicted future route is illustrated using dashed line 52. It intersects base station cells 14a and 14b. In FIG. 5 shows that pre-set 50 generally consists of base stations 14 ₁ ... 14 _M , where M≥N. The time span of the predicted future route 52 may cover a time interval 54 starting at time t ₀ and lasting more than 10 seconds, 1 minute, or even 5 minutes, for example. The time span 54 may also be variably determined and may adapt, for example, to the prediction accuracy of the predicted future route 52. The cellular network may receive information about the predicted future route 52 of the user node 10, for example, from the user node 10 itself, a user node or some component thereof capable of determining the position of the user node 10, such as a navigation system or the like, or from some other UE. The transmission of information may occur, for example, during the establishment of an RRC connection. Alternatively, information about the predicted future route 52 of the user node 10 may come from a device other than the cellular network 24 and the user node 10. Such other device may be, for example, a system that tracks the user node 10 but is located outside the cellular network 24. Information may be provided, for example, by an external host, such as a V2V/V2X server, or from an over-the-top (OTT) host, such as Google®. It is even possible that another device is responsible for granting permission to the future route 2, such as a traffic dispatch system, which may be responsible for, for example, drone flight paths as examples of UEs and the like. Additionally or alternatively, the cellular network 24 may itself determine the user node's predicted future route 52, for example by triangulating signals sent by UE 10 and received by multiple base stations 11, etc., or by extrapolating path 52 from the path traveled by UE 10, given by updates to the current position of the UE that the network 24 receives from the UE 10. The derivation of the predicted future route 52 may provide, in any case, regardless of the inferring node, the type of extrapolation or prediction based on additional information other than the current position of the user node 10, for example, the route traveled by the UE 10 just prior to time t ₀ , map data indicating a map of the area 40 such as a city plan or the like, and/or user preference data associated with the UE 10 collected based on the estimation of the routes traveled by the UE 10 in the past. Preset 50 will then be determined such that route 52 traverses base station cells in set 50. Thus, UE 10 would likely need to handover at least a subset of base stations from set 50. However, it should be noted that set 50 may , alternatively, be determined by the cellular network 24 not based on an estimate of the predicted future route 52. The predicted route 52 may, for example, be determined by a V2X broadcast server or using information from other mobile users, such as a sensor combination of a set of predicted routes from multiple UEs. Additionally, base station 12 may be configured to request route vector 52 as a kind of measurement report including route updates and m higher routes, e.g., route 1, route 2, route 3, ...

The use of route 52 to define set 50 is not required. For example, the mere fact or occurrence that UE 10 enters some predetermined zone 56 may indicate that there is a high probability that user node 10 will, for some time interval 54 after time t ₀ of entry UE 10 into zone 56, in some zone, or will move along some path or route, whereby set 50 can be automatically determined by the event of UE 10 entering zone 56 at time t ₀ , even if there is a close connection. For example, zone 56 may be one end of a street without any intersection until it reaches, along some path 52, street, the first intersection and, accordingly, once UE 10 is on the street at that point, it is very likely that UE 10 will follow this route/street 52. Similarly, imagine that UE 10 enters the tunnel at the first end and the tunnel is long enough to reach another cell. Although it may not be known which street the UE will move down after the tunnel, it is highly likely that the UE will continue to move after the tunnel and accordingly set 50 can be defined to cover the base stations surrounding that side of the tunnel.

In addition, alternatively, the prediction that there is a high probability that the user node 10 will, for some time interval 54 after time t ₀ , be in a certain area, or will move along a certain path or route, can be triggered based on the estimate history of the CE route in the past, for example, the time interval preceding, or even immediately preceding, the time t ₀ . In addition to the user node 10 entering the area 56, for example, the current direction of movement of the UE 10 can be taken into account to start preparation of proactive HO only in the case of a direction of movement pointing in some direction or direction field in addition to the direction of entry of UE 56. For example, proactive preparation of HO can be started by a user node coming from a predetermined zone 56. Generally speaking, the position history of the UE may be evaluated to see if that history meets certain criteria, and if so, a proactive HO may be initiated. Position history can be recorded with any granularity or precision. For example, a previous set of serving base stations, or a list of previous base stations along a user node's route, i.e. some mobility history can be used for this. Regardless of the triggered area or triggered position history, triggering may be based on matching the UE's current position, the UE's current moving direction, and/or the UE's latest position history with one or more predetermined criteria that are independent of the most recent connection quality measured by the UE in in relation to its communication connection with the original base station 12 and/or any surrounding base station 11.

Thus, in conjunction with determining the pre-set 50 base stations, cellular network 24 determines for each base station in set 50 an expected time t_one … t_Mwhen the user node enters the cell 15 of the corresponding base station, i.e. is within its range. Accordingly, the base station 12, i. e. source eNB, queries each of the pre-set 50 target base stations for the availability of the cellular network 24 through the respective target base station at the respective expected time t_i. As a result of this request, the base station 12 of the cellular network 24 receives from each of the pre-set 50 base stations, a response for the request. While none may exist in preset 50, there may be one or more base stations that are denying access, there may be a set of base stations, e.g., N base stations, where N ≥ 1 and N ≤ M, that respond to the request. , indicating the access time interval 60 during which the corresponding base station is available to the user node 10, provided that the user node 10 uses one or more access parameters indicated by the corresponding base station in the response for the request. For example, FIG. 5 shows that some access interval 60 overlaps with the first expected time t_one. Base station from set 50 in the cell where user node 10 is expected to appear at time t_onethus allows the user node 10 to access the cellular network 24 using one or more access parameters by respectively reserving the respective access radio resources during the time interval 60 . The same may apply for other expected times, where the associated target base stations may be different for the expected times, but this is not necessarily the case. After the request and responses to it, the base station 12 is thus able to send to the user node 10 a schedule 62 that indicates, for each of the set 64 of one or more base stations for which the access timeslot 60 is defined and one or more parameters 66 access, access timeslot 60, and one or more access parameters. This schedule 62 indicates to the user node 10 that it can access the cellular network 24 through the corresponding base station 14_x during the access time interval specified, for example, by its start or the start time t^x _startusing one or more access parameters associated with it p^x _access, where x is an element of the set {a, b…}, i.e. is the index of set 64. In other words, schedule 62 may be provided as an ordered list of items, items having a time dependency, or schedule 62 may be provided as a set of items. Also, alternatively, schedule 62 may be provided as a list of lists or sets that may be ranked, eg, the highest m. Then each such element will be associated with some target base station, set its interval 60 access and one or more parameters 66 access. Then, i.e. after the schedule 62 is transmitted to the UE 10, the proactive preparation of one or more handovers ends and the user node is informed of this, and this is done, from sending the schedule 62 to the user node ahead, insofar as the user node 10, whether or not using the user node access capabilities during intervals 60 to perform its handover from one base station to the next, or, in another view, insofar as the user node uses these opportunities, provided that other external circumstances do not prevent the user node 10 from using these opportunities, since, for example, prediction of the prediction route 52 based on the event of UE 10 entering zone 56 is incorrect.

Solely for completeness, it should be noted that the time spent requesting base stations from the set 50 and receiving responses before sending the schedule 62 may be negligible compared to the time span 54 in which one or more expected times t are distributed._i. Schedule 62 may define some access timeslot 60 by specifying, for example, its start time t^x _start, wherein the end of an access slot 60 may be implicitly defined by the maximum length of each slot 60. In other words, the corresponding base station 14_x may close access some time after t^x _start. However, the end time of interval 60 may also be specified in schedule 62.

As described below, the request sent from the base station 12 to the target base stations of the set 50 may contain one or more current identifiers by which the user node 10 is identified in the cellular network, for example, an identifier by which the user node 10 is identified by the core network 34 , for example, in MME 32. In particular, the request may additionally or alternatively inform base stations in set 50 about user node 10 context data. from base station 12 to core network 34, such as MME 32 in core network 34 to schedule packet forwarding of one or more communication paths for user node 10's communication sessions over cellular network 24 and user node 10, whereby the packets are distributed to each base station from set 64 depending and from the corresponding access time slot 60 of the corresponding base station in set 64. In other words, the MME 32 or the core network 34 gets the opportunity to schedule, at an early stage; namely, at the time of receiving the schedule 66, the distribution of incoming packets coming, for example, from an external network, to base stations from the set 64, other than the base station through which the user node 10 is currently connected to the cellular network 24. The packets that , for example, are probably too long buffered at some base station in set 64 and cannot be transmitted from this base station to user node 10 before the expected handover from this base station to the next base station in set 64, may be relayed by core network 34 or MME 32 , respectively, to the next base station from the set 64 according to the sequence of expected times covered by the respective access slots 60 . The cellular network 34 would not need to wait for such a redirect until a handover actually occurs from the UE 10 actually using one or more of the access parameters it is provided with through the schedule 62.

It should be noted that the number of elements of the set 50 and the number of elements of the set 64 or the number of elements of any of these sets can be greater than 1. However, in general, both can be equal to 1, 2. As for the future start time 70 specified in the schedule 62 to indicate the start of the corresponding access time slot 60, note that it may be indicated by quantization indices or in seconds, and the like.

It follows from the above that if the prediction that caused the preemptive handover preparation is good, UE 10 is likely to handover from base station 12 to the target base station for which the nearest access slot 60 is specified in schedule 62. Thus, UE 10 will use one or more access parameters 66 for that target base station, which, in the example shown in FIG. 4, for example, will be the base station 14 _a during the access time slot 60 and thus perform or activate the pre-arranged handover as previously described. This base station 14 _a will then inform the base station 12 of the user node accessing the cellular network 24 through the base station 14 _a , and based on this information, the base station 12 will terminate its connection with the UE 10, which the core network 34 will be informed by base station 14 _a , and based on this, redirect the internal cellular network subpath of each of the set of one or more communication paths of one or more communication sessions passing through cellular network 24 and user node 10 from base station 12 to base station 14 _a . Additionally, the resources of the base station 11 through which the user node 10 is currently or, better, previously connected to the cellular network, here the base station 12, can be freed, for example, one or more of their buffers scheduled by the base station for one or more active at the moment of UE 10 communication sessions. Base station 12 may terminate its connection with UE 10 and/or release its resources alternatively in response to a signal sent from the core network indicating that a path redirect has taken place, in response, in turn, to a notification sent from the target base station 14 _a , which now assumes the role of the source base station. In the same way, the next handover occurs between this target base station, which is now the source base station, and the next target base station in set 64.

Thus, with reference to FIG. 4, a cellular network 24 is described that supports proactive handover preparation for a user node 10. However, in the above description, a user node 10 is disclosed for communicating over a cellular network 24, wherein the user node 10 is configured to obtain predicted future route information 52 user node and informing the cellular network of the predicted future route 52. The UE may transmit a list or vector of coordinates, such as WGS84 coordinates, to the cellular infrastructure 24. UE 10 may do so upon request from base station 12, from a V2X server, or at regular time intervals. It should be noted, however, as described above, the predicted future route information 52 may originate from a node other than the user node 10. The predicted future route information 52 may be sent to the cellular network 24, for example, as a set of time and location coordinate pairs, in which the user node 10 is on the predicted future route 52, or the sequence of coordinates of places traversed by the user node sequentially along the predicted future route 52, for example, the places that the user node traverses along the predicted future route 52 with some constant step interval time step.

Additionally, in the above description, a description has been given of a user node for communicating over the cellular network 24, wherein the user node 10 is configured to manage a set of one or more pre-arranged handovers. Thus, user node 10 is not required to inform the cellular network of the predicted future route 52. In general, user node 10 may handover to more than one carrier. Thus, the user node can handover in a dual capability infrastructure, e.g., LTE+NR/5G, multi-RAT, e.g. separate LTE, CDMA/UMTS, NR networks, or carrier aggregation, e.g., handover to a lower frequency carrier. = better coverage or higher frequency = potentially higher throughput or lower latency. The details and background in this regard are set out below. In any case, the user node 10 has the ability to manage a set of one or more pre-arranged handovers; namely, those specified in the schedule 62 that the user node 10 receives from the cellular network 24 and from the source base station 12, respectively. From reception forward, i.e. as such, throughout the entire time interval 54, the user node 10 continuously checks to see if the schedule 62 is becoming inadequate. For example, the user node recognizes that the user node deviates from the predicted future route 52 because, for example, the user of the user node 10 decided to take a different path than rule 52 dictates. In this case, the user node can inform the cellular network 24 of the inadequacy, whereby, for example, cellular network 24 may inform target base stations in set 64 to allow the latter to provide reserved radio access resources associated with one or more access parameters to other user nodes. As described above, the user node may derive from the schedule 62 the access time slot 60 plus the associated one or more access parameters 66 for each target base station in the set 64 and then, from receiving the schedule 62 forward, continuously decide to access the cellular network 24 through any of the target base stations of this set 64; namely, any base station from the set 64 within the range of which the user node 10 is currently located. Obviously, this solution is only possible during the access time interval 60 associated with the corresponding target base station annually using one or more access parameters specified in the schedule. The user node 10 is able to handover or access the cellular network using the schedule 62, or perform the continuous decision about it described above, without obtaining current permissions from the cellular network 24 on a case-by-case basis, i.e. without obtaining a current permit within a time interval 54 . The schedule 52 instead serves as a license for the user node to perform each handover during the corresponding time interval 60 .

As described in more detail below, user node 10 may be configured to schedule a set of one or more proactively scheduled handovers 62 for one or more wireless connections to cellular network 24 from a set of current wireless connections to cellular network 24. For example, user node 10 may use aggregated carriers and perform proactively prepared handovers with respect to one or more than one component carrier of such aggregated carriers.

As follows from the above, the user node has the ability to resume the ability to communicate with the cellular network after losing the ability to communicate using any of the set of one or more proactively prepared handovers, despite the temporary loss of connection. For example, in a scenario where a UE loses connection due to a tunnel, the UE 10 and the next base station participating in the forward HO may simply reconnect between themselves using the forward prepared HO.

Although not previously described, it should be noted that in addition to the description given above with reference to FIG. 4, or alternatively, the cellular network may be implemented in accordance with the third aspect of the present invention. In particular, the cellular network may analyze a predetermined set of cell 15 base stations around the user node's position with respect to the set of candidate routes leading from the user node's position to determine the most preferred route from the set of possible routes with respect to the possibility of communicating with the user node. For example, a cellular network may request a set of 50 target base stations, but set 50 spans more than one route, i. a set of possible routes leading from the user node's current position. Thus, target base stations from set 50 will be determined to cover all routes in the set of possible routes. The target base stations of the set 50 will respond to the request and based on these responses, the cellular network 24 will be able to determine the most preferred route out of all the routes in the set of possible routes in terms of communication capability; namely, a route along which, for example, all nearby base stations have indicated a possible access time interval 60 plus associated one or more access parameters 66 . For example, the most preferred route may be the best connected route from the UE's point of view, eg, the route that provides the highest QoS. The most preferred route may be the best connected route from the point of view of the base station, eg, the route with the least traffic or the highest capacity/coverage/lowest delay/best user experience/lowest congestion probability. Cellular network 24 may inform user node 10 of the most preferred route actively or upon request or poll by UE 10. route. In other words, base station 12 or cellular network 24 can force this information to be sent to the UE. Alternatively, UE 10 may download or retrieve this most preferred route information from cellular network 24. This information may, for example, be used by applications running on the user node. This measure allows the user of the user node, for example, to receive this information, for example, through the display or similar output device of the UE 10, and the user can decide, as the carrier of the user node 10, to move in the most preferred route, for example, to watch the video being downloaded at a given time. without any parrer event. However, the "user" is not limited to a human user. Consider a UE to form the interface of a robot or other autonomous driving device, where interruption of the data connection can have very negative and dangerous consequences. Likewise, the recipient of the path advice may be another device, eg, a device responsible for, or participating in, determining(s) the future route the UE is taking, eg, a traffic scheduling unit. Information about possible routes may be provided by the cellular network from outside. However, the cellular network may itself determine the set of possible routes, or may receive this information about the set of possible routes from the user node. Thus, the cellular infrastructure 24 may recommend some routes based on coverage, such as indicating to the user which route index provides the best coverage, such as the top m routes from a network point of view. The analysis and provision of information may be performed at the source base station 12. Thus, any base station 11 may have this functionality. However, the functionality may be implemented in another cellular network device 24.

The above described embodiments can be used to achieve lower handover latency and/or lower control signal overhead associated with handovers.

Current LTE handover (HO) procedures do not allow high reliability low latency communications (URLLC) where the existing average minimum HO is approximately 40-50 ms [1]. As a result, there is room for improvement in the overall HO process for 5G use cases, including low latency communications. This can be done using the embodiments described previously.

An efficient and fast mechanism for performing handovers via route prediction information of UEs with varying mobility rates can be provided using the above-described embodiments. The latter has the advantage of reducing signaling overhead and latency when connected to subsequent target(s) eNB/gNB for LTE and new radio (NR) network architectures. This can be done by the UE signaling the pre-allocated target cell parameters 66 needed to connect to the target eNB/gNB prior to the actual HO process. Fig. 6 provides an overview of the predictive HO (P-HO) scheme in the LTE framework.

The proactive decision should be triggered before the actual HO for the source/anchor eNB/gNB 12 occurs, for signaling the UE 10 the parameters 66 of the target eNB/gNB (e.g., RRC connection reconfiguration including reporting mobility control information), examples of which are given in the table shown in Fig. 7.

In other words, the previously described embodiments provide an efficient mechanism for predictive handovers in an NR network with N predicted target gNBs.

The following aspects may be supported (cf. FIG. 4 and FIG. 6):

1) initiate HO preparation to N target eNBs 64 via predicted path 52 and pre-allocated UE signaling using triggers initiated by:

a. source gNB or anchor gNB 12 (network control),

b. running UE 10,

c. a new centralized node 80 in the radio access network 24, such as a base band central unit (CBBU) with a central radio resource management (RRM) (network management).

2) Efficient N-hop predictive context relay using network signaling sent from

a. source or anchor gNB 12 to N target gNB 64,

b. anchor gNB 12 in RAN paging/monitoring/notification area, e.g. 40 to N new or potential new anchor eNBs in new RAN paging/tracking/notification area,

c. baseband center block 80 and/or to N new or potential new baseband center blocks,

d. source gNB 12 or CBBU 80 to UE 10 in preparation for the HO process.

In particular, the NW or UE 10 may trigger predictive handover (P-HO) initiation with N hops according to the state of the RRC. The P-HO procedure is a set of target cell set 64 configuration parameters 64 along the predicted route 59 that are signaled to the UE 10 prior to the actual implementation of the HO. The UE 10 may, with some available assistance information (CAM messages containing time, 2D and 3D position reporting, position vectors, position coordinate intervals, route, flight plan, etc.), launch the home/anchor eNB 12 for implementation of P-HO. Consider two options for P-HO excitation:

1. In RRC-Connected (LTE)/Active (NR) mode: Source/anchor eNB 12 or CBBU 80 in case of CU/DU split initiates and performs P-HO.

2. In the loosely connected (LTE)/dormant (NR) mode: UE 10 independently initiates a request for appropriate P-HO configuration parameters, including predictive context relay to all relevant target eNBs/gNBs.

Thus, the source eNB or centralized nodes (eg, CRRM, CBBU, MME) can initiate multiple predictive prepared HOs for N≥1 target eNBs 64 along the predicted UE path 52 . This scheme avoids the need to restart the HO preparation phase when the UE passes through each of the expected target cells, since all the necessary resources are pre-allocated. As a result, the P-HO scheme can reduce signaling overhead and latency once predicted route information 52 is established. the set start time t ₀ of the predictive procedure HO with N hops; and the mobility type of the UE (eg, high or low speed). If UE 10 abruptly changes trajectory or remains stationary in a particular target cell, then all target eNBs/gNBs 64 identified during the P-HO procedure may release previously allocated resources upon expiration of a timeout.

An exemplary flowchart for a P-HO driven by an NW or a UE is shown in the flowchart of FIG. 8. Covered area 90 indicates a signaling scheme specific to the P-HO scenario. The P-HO procedure is triggered by centralized nodes, for example 80, or source eNB/gNB 12, when UE 10 is either in proposed active (NR) or normal RRC connected (LTE) state as shown in the state diagram (FIG. 3) [3]. When the UE 10 is in the loosely connected mode, the P-HO based prediction information allows the UE to independently move between eNB/gNB cells belonging to different paging zones, as described below. To perform the necessary RRC reconfiguration between different cells, the UE may transition from a normally connected state to a loosely connected state. As a result, the UE may be in a low power loosely connected state and still perform P-HO.

An overview of the messaging step in FIG. eight

Message 2: This trigger may be initiated on the source eNB (or centralized unit) when the UE is in RRC-connected/active mode (in which no additional messages exist. Alternatively, the UE may independently trigger P-HO in loosely connected/idle mode as part of the measurement report.

Message 3: This is a distributed message from the source eNB/gNB requesting the availability of resources from each target eNB/gNB (preparing multiple HOs) together with the UE context to be transferred.

Message 4: Container with ACK from corresponding target eNB/gNB with available resources.

Message 5: UE message with required signaling parameters for target eNBs/gNBs.

In FIG. 9 further illustrates the above messages using a centralized unit/distributed NR architecture. The signaling flows from the messages correspond to the proposed messages in FIG. eight.

Key P-HO procedures:

Below is a more detailed description of the illustrative messages:

Message 2: Source eNB/Centralized Unit or UE may start the P-HO process. From the perspective of the source eNB/centralized unit, the trigger may occur by monitoring the UE when it is in connected mode and then performing a P-HO. With respect to the UE, the predicted route information may be sent by the UE itself, which will allow it to independently move between paging areas in a loosely coupled mode using onboard prediction data. The UE may signal the following messages to the source eNB in the measurement report:

- CAM messages,

- providing a report on speed, acceleration, speed, 2D and 3D location, etc.

- route information, GPS information, flight plan

- traffic information, etc.

Illustrative syntax: UE-aided-P-HO-IE

IE/ group name Description Message type [4] ʺIdentifies the message being sent, e.g. handover resource allocation, path switching requestʺ [12] CAM-Aided-Route-Prediction List of data items in [14] Appendix A, e.g. acceleration control, driving route, reference position Path-target-eNB-ID-List If present, position or ID of target eNBs along the predicted route RRC-Connect-Time RRC connection period of the current cell RouteInfo/FlightPlanInfo 2D and 3D UE location vector, UE direction, waypoints along UE route

Message 3: The P-HO request message via S1/X2 requests the availability of resources from potential target eNBs/gNBs in relation to a specific UE's predicted handover. It may contain information about the user, such as expected time of arrival, unique IDs, context and security information, and expected level of service requirements. Additionally, the UE context can be forced to be sent to all target eNBs. An example of this S1 establishment message may include: P-HO-REQUEST-IE (direction: source eNBs → target eNBs)

IE/ group name Description Message type [4] Identifies the message being sent, e.g. handover resource allocation, path switching request Handover type [4] Indicates the type of handover on the source eNB, e.g. intra-LTE, from LTE to UTRAN List of eNBs to be established Identifies the list of target eNBs MME-UE-S1-AP-ID[4] ʺUniquely identifies the UE binding on the S1 interface in the MME.ʺ [12] eNB UE S1AP ID [4] ʺUniquely identifies the UE binding on the S1 interface in the eNB.ʺ [12] Predicted UE Behavior Specifies the future behavior of the UE with predictable activity using predicted information to help future eNBs determine the optimal RRC connection time. UE context transfer The UE context is forced to all target nodes based on the prediction. UE mobility type Low, medium, high speed

Message 4: The response from the target eNB may acknowledge or reject the request via S1/X2 to the requesting source eNB/centralized unit using an ACK/NACK message. The decision is based on the result of admission control and resource availability. When the target eNB acknowledges the request, it prepares resources for the potential new UE, saves the new context, and configures 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] ʺIdentifies the message being sent, e.g. handover resource allocation, path switching requestʺ [12] eRABs-Admitted-List [4] ʺA HO request ACK message is sent by the target eNB to inform the MME of the target's provisioned resources, such as the list of admitted E-RABs. Therefore, the E-RABs that can be admitted to the target are referred to as the list of admitted E-RABs.ʺ [12]. MME-UE-S1-AP-ID [4] ʺUniquely identifies the UE binding on the S1 interface in the MME.ʺ [12] eNB UE S1AP ID [4] ʺUniquely identifies the UE binding on the S1 interface in the eNB.ʺ[12]

Message 5: In the table shown in FIG. 7, the required UE signaling parameters to be sent wirelessly to the UE originating from the eNB/gNB are summarized. Target cell security keys will require an additional layer of encryption if they are to be preallocated. The RNTI and RACH preambles can be preallocated according to the mobility type, which saves the UE from having to obtain these parameters each time it moves between target cells. The UE may keep its identity between several cells, depending on whether the UE has high mobility. According to one approach, the UE may have a single ID in the RAN paging/notification zone (eg, selected by the anchor eNB when the UE enters the RAN paging/notification zone, or selected by the central node, eg, CRRM, CBBU, MME), denoted as " unique UE ID".

The RAN (originating eNB/centralized unit) can distinguish between three types of mobility (eg, low, medium, and high mobility). The low and medium mobility types will receive a cell-specific C-RNTI, while the high mobility type UEs may retain their identities. The target eNB will then know which UE ID to look for from the UE context already received in message 3. The SL configuration can also be preallocated to enable V2V communication. In the case of granting a request and preparing a handover, this message includes the parameters needed by the UE to connect to the target eNBs.

The timeout indicator will be set on the source eNB depending on whether the P-HO NW or UE is running and shared with multiple target eNBs. The UE may notify the target eNBs through uplink signaling, and if the UE does not enter the cells of the target eNBs at the required time, the previously allocated resources are released and the return will be a conventional HO procedure.

RACH common preamble scheduling and/or RACH common resource scheduling in the RAN paging/notification zone is assumed. A highly mobile UE will quickly move from one eNB to another and thus may use the same preamble for multiple target eNBs. Therefore, shared RACH resource pools between eNBs are required to send the same RACH signal to multiple target eNBs along a route. This allows multiple target eNBs to decode the signal, which requires the formation of a common pool of RACH resources. This is highly dependent on RACH load and RACH resource reuse. Because multiple cells share resources, they may be required to operate at a lower load, which reduces efficiency due to lower resource reuse.

Retransmission of P-HO user data, in the case of an out-of-coverage scenario, can be carried out as follows:

in the case where the UE loses coverage and experiences a radio link failure (RLF) during the P-HO process with the source eNB-1, the out-of-coverage scenario is shown in FIG. 10. The UE attempts to re-establish an RRC connection with the target eNB, provided that it has already received signaling parameters for connection with the target eNB. Retransmission of redundant data may be applied to the architecture of the centralized unit.

Step/Description 1: RRC connection re-establishment: resolving synchronization and timing advance using prediction information already at the UE. This procedure may be initiated with RACH and C-RNTI preambles prepared.

Step/Description 2.1: Before the timeout with the source eNB, the core network has already relayed redundant data through the centralized unit to the next target eNB based on the information from the HO prediction procedure. This redundant data is relayed to the target eNB if the P-HO process is initiated.

IE/ group name Description Message type [4] ʺIdentifies the message being sent, e.g. handover resource allocation, path switching requestʺ [12] TNL X2 Configuration Information [4] Contains information related to P-HO. Basic Data Relay Relays the redundant data as originally sent to the source eNB. MME-UE-S1-AP-ID-SeNB ʺUniquely identifies the UE binding on the S1 interface in the MME.ʺ [12]

Step/Description 2.2: The UE may send the ACK sequence number of the last packet to the target eNB to resume data relay from the last known RRC connection timeout to the SeNB.

IE/ group name Description Message type [4] ʺIdentifies the message being sent, e.g. handover resource allocation, path switching requestʺ [12] TNL X2 Configuration Information [4] Contains information related to P-HO. UE Data Relay Sends ACK and relays SN number.

In UE dual connectivity mode, P-HO can also be used.

Dual Connectivity (DC) P-HOs allow URLLC services of mobile UEs and thus can meet the requirement of high reliability. The UE's predicted route information may also assist UEs that are in dual connectivity mode, ie. connected to two eNBs, the master eNB and the slave eNB at the same time, to perform seamless handover. This is particularly applicable to scenarios where the mobile UE moves between multiple small cells in a macro cell environment, such as in a dense urban scenario. A group of such small cells belongs to a subsidiary cell group (SCG). HOs with DC capability can result in zero interruption due to the constant presence of at least one connected link. The new requirement is that dual connectivity can be initially enhanced so that the master eNB can perform P-HO for multiple small cells (auxiliary eNBs), allowing the UE to move between small cells without service interruption, which reduces the overhead in standard HO signaling. , as described in E1. The procedure is carried out as follows:

1. The master eNB initiates the P-HO process (according to the initial initiated P-HO procedure) by receiving the SCG information, which includes the parameters in Table 1 for each small cell.

2. The master eNB then sends this information to the UE (via an RRC reconfigure message) with all the necessary P-HO information for each small cell along the predicted route (see Table 1).

3. The master eNB can then cancel the dual connection capability, allowing the UE to have a single Uu connection with each small cell along the predicted route, with the advantage that the HO is already prepared, allowing RRC to be reconfigured with each small cell without service interruption.

The following description is devoted to the second aspect of the present invention, which relates to the efficient processing of user nodes in idle mode using the so-called "tracking/paging area". Again, the description of this aspect and its embodiments starts with the type of presentation or overview, which allows to solve the problem with inactive UEs and obtain the benefits due to the embodiments described below. However, the following overview is partly also a continuation of the introductory part with respect to the description and presentation of embodiments relating to the first and third aspects of the present invention described above.

Mobility improvements in loosely coupled or idle mode have recently been proposed. The state machine in current control plane protocols in cellular wireless communication mainly supports two modes: idle mode and connected mode. In the sleep mode, the UE monitors a control channel (PCH) according to a discontinuous reception (DRX) cycle. At the same time, in the idle state, the MME is responsible for monitoring the UE. In connected mode, the UE is connected to a known cell and can carry out data transfer to and from the device. Meanwhile, in the connected mode/active state, the corresponding eNB is responsible for tracking the UE.

HOs are performed when the UE is in RRC connected mode. The implementation of a new mode, referred to as loosely connected (in LTE) or idle state (in 5G "new radio" (NR)), is currently under consideration to improve signaling efficiency, also for new services. In this state, the UE is responsible for transitioning to the idle or connected state. Loosely connected UEs enter traditional RRC connection behavior through an RRC procedure including three messages (ie, request, response, and done). In the loosely connected state, the S1 connection for that UE remains active, and a new signaling scheme from the UE may be introduced to optimize handovers and improve network performance through motion predictions. In FIG. 11 shows an example of the loosely coupled mode of operation proposed in [3].

The RAN paging area/notifications and tracking area is used to keep track of idle UEs. Paging is used for network initiated connection establishment when the UE is in the idle state (RRC_IDLE), see [5]. It is intended to instruct the UE to start a service request. Because the location of a device is generally unknown at the cell level, the paging message is typically transmitted across multiple cells in a so-called tracking zone. These watch zones are managed by the MME. The UE informs the network via tracking area updates (TAUs) of its location in the network. To reduce signaling traffic, the UE does not need to initiate a TAU if it is in a tracking area that is included in its tracking area list (TAL). See fig. 2.

With regard to the NR architecture, two types of architecture for NR are proposed, namely, a centralized unit (CU) architecture and a distributed unit (DU) architecture, as shown in FIG. 13.

With respect to the architecture of the V2X system, one of the main modes of operation in V2X consists of the broadcast architecture and exemplifies the application of the proposed P-HO scheme.

As for the V2X broadcast architecture, the high-level V2X broadcast architecture is shown in FIG. 14 with a new additional node known as the V2X application server [8].

The basic functionality of the V2X Application Server is outside the scope of 3GPP [8], and the role of the Application Server is outlined in the ITS. As defined in [8], an application server aggregates inputs from multiple sources, including vehicles on the road, roadside blocks, and external information from various other network nodes. The application server then correlates this information based on time, location, and event to develop a better idea regarding the motion state. After collecting and processing the information, he decides what information needs to be distributed to other vehicles in the geographical area [9]. Currently, the V2X Application Server has the following specifications according to 3GPP, which is in line with the ETSI proposal [8]:

- the ability to receive uplink data from the UE in unicast mode.

- delivery of data to the UE in the target area using unicast delivery and/or MBMS delivery.

- mapping of geographic location information to the proper target MBMS service area ID (SAI) for broadcast.

- Mapping of geographic location information to the appropriate target 3GPP E-UTRAN Global Cell Identifier (ECGI) for broadcast.

- pre-configuring local MBMS (L.MBMS) information (eg, multicast IP address, multicast source (SSM), C-TEID).

- pre-configured with IP address and L.MBMS port number for the user plane.

To minimize delays between the RAN and the V2X infrastructure, V2X nodes can be grouped into an eNB roadside unit (RSU). This RSU can be installed directly on the eNB, similar to edge-to-cloud computing, for example, through the Local Breakthrough IP (LIPA) interface. This allows faster prediction of the HO process. See fig. fifteen.

Dual Connectivity (DC) capability has been included as part of the small cell improvements in LTE and provides a number of benefits that include [10]:

- increasing the throughput of the UE at the cell edge,

- increased stability for UE mobility,

- reduced signaling overhead to the core due to frequent HO.

The UE may connect to the master eNB and the subsidiary eNB, but may only have one RRC connection to the master eNB. In the V2X scenario, the DC can improve non-discontinuous or zero-interruption HO between different eNBs along the predicted path, ensuring that there is always one active/inactive. User plane data separation may occur at the bearer or packet level, as shown in FIG. 16 and 17 [10]

ʺTo initiate a HO, the source eNB sends a HO request on X2. The HO request needs to be modified to indicate that it is a dual-capability HO as opposed to a traditional HO. The purpose of the HO is to transfer the DRB subset to the target eNB. Thus, it is necessary to refine the HO request message to indicate which bearers are to be transmitted. At this point, the UE context includes information about the bearers assigned to the source eNB. For dual connectivity, the UE context will be required to indicate which of its bearers are mapped to the target eNB.

The target eNB will indicate which bearers it wants to receive in the ACK of the HO request. As with the modern HO procedure, bearers that are not received will be discarded. The target eNB sends the DL allocation and RRC connection reconfiguration with the mobility control information to the source, which sends it to the UE. SN status transfer and data relay will continue for bearers to be transferred. The UE will initiate RACH on one of its radio bearers while maintaining regular communication on all bearers that remain on the source eNB.

In case of successful handover, the UE sends "RRC connection reconfiguration done" as usual. After the HOF, a new RRC message is sent to the source eNB on its associated UE radio bearer to indicate the failure. The source eNB may assist the UE by either accepting a connection from radio bearer #2 or by preparing the other eNB to do so.

In the case of a successful HO, the target eNB will send a Path Switch Request to the MME on S1 requesting its assigned bearers. The MME will send a bearer modification request to the gateway. Finally, the target eNB updates its UE context and sends the UE context update to the source eNB over X2. The source eNB updates its UE context and releases the resources associated with the HO.ʺ [12]

It follows from the above brief introduction that the principle of scheduling a tracking/paging area for some user node reduces the load on the cellular network side in order to continuously reserve radio resources for user nodes with one or more active sessions, but for which one or more sessions are not provided continuous packet transmission. Thus, it is sufficient for the cellular network to at least approximately track the location of the UE; namely, in a certain tracking/paging area, whereby packets addressed to the UE can be relayed to one or more base stations in that tracking/paging area, and if the base stations in the tracking/paging area know the UE context data. The principle applied in some of the embodiments described in relation to active UEs and the proactive handover preparation used in some of the above embodiments is now being reused to work more efficiently with inactive UEs; namely, that a time-varying tracking/paging area schedule is introduced and/or a tracking/paging area is determined depending on the user node's predicted future route.

For an explanation of embodiments of the present invention with respect to this aspect, reference should be made to FIGS. 19, which reuses some of the reference numerals previously used; namely, with respect to nodes performing the same or a similar task in a common communication network.

In particular, in FIG. 19 shows a cellular network 24 which, as discussed with reference to FIG. 4 is comprised of a plurality of base stations 11 distributed such that their associated cells 15 cover an area or geographic area in which base stations 11 serve UEs in their cells for wireless communication with UEs in their cells. The base stations 11 are connected via some interface 28 to the core network 34 of the cellular network 24. This core network 34, in turn, may have an interface to the external network 42. With respect to activated UEs, i.e. UEs that are currently connected to cellular network 24 via the current source base station, cellular network 24, and UEs communicating via cellular network 24 in FIG. 19 may behave as described with reference to FIG. 4 or, optionally, in accordance with the state of the art discussed above with reference to FIG. 1-3. However, the cellular network 24 shown in FIG. 19 is configured to schedule a predetermined user node 10 with a time-varying tracking/paging zone covered or defined by a time-varying set of one or more base stations or formed by cell(s) from a set of one or more base stations. For a more detailed explanation of this, refer to FIG. 20. In FIG. 19 and 20, it is assumed that the base stations 11 are previously spatially clustered into so-called "paging zones" 90. Four such clusters or spatially adjacent base stations 11 are shown by way of example in FIG. 19. However, it should be noted that this clustering is not mandatory for the present embodiment. As shown in FIG. 20, cellular network 24 determines, at some point in time t ₀ , for UE 10, a time-varying tracking/paging area. Time t ₀ may, for example, be initiated by UE 10 which decides to transition from an active mode to an intermediate low activity mode, the details of which are described in more detail and presented below. A tracking/paging area, at any point in time, is an area served or covered by a set of one or more base stations, but this set changes over time. Its determination occurs at time t ₀ based on some kind of prediction, similar to the principles for obtaining set 50 in FIG. 5. For example, the tracking/paging area may be set in accordance with the predicted future route 52 of UE 10, ie. according to the predicted position of UE 10 on route 52. The result of this determination is shown in FIG. 20 as schedule 100. In particular, schedule 100 defines, for each time point during some time interval 102 that follows time t ₀ , a set of one or more base stations 11 that form a tracking/paging area, i.e. e. set 104. In FIG. 20 shows that schedule 100 indicates set 104 in units of clusters 92, but another solution is possible. In particular, the schedule 100 specifies this set for the successive partial slots 106 into which the time slot 102 is divided. Thus, for each such sub-slot 106, schedule 100 specifies a set 104 of base stations 11 that form a tracking/paging area. Alternatively, the UE 10 is occasionally informed of the time-varying tracking/paging area by messages periodically updating the cell set of the base stations defining the area 104.

The cellular network 24 then sends the schedule 100 or messages updating the area 104 from time to time to the user node 10 to continuously check whether the UE 10 is leaving this time-varying tracking/paging zone defined by a time-varying set of one or more base stations 104. Assuming the UE does not leave the time-varying tracking/paging area, the UE is in the area where the cellular network 24 expects the UE 10 to be. Assuming the UE 10 does not wish to initiate uplink communications connection and wake up, UE 10 does not need to do anything. Cellular network 24, in turn, takes appropriate steps to perform tasks that are designed to reflect the fact that the tracking/paging area changes over time, as scheduled in schedule 100. In particular, cellular network 24 supplies each base station from a set of 104, i.e. each base station currently in the base station set 104 that define the tracking/paging area, UE 10 context data, whereby these base stations know, for example, UE 10 subscriber data, one or more currently active sessions communication, one or more IDs used by cellular network 24 to identify UE 10 and distinguish UE 10 from other UEs, and/or other UE-specific data. Additionally, cellular network 24 itself uses a schedule 100 to search for UE 10 whenever an incoming or downlink packet of one of one or more active transmissions arrives at core network 34 destined for UE 10. In particular, cellular network 24 searches for in the schedule 100 which set 104 of base stations is currently forming or defining a tracking/paging area and informing through these one or more base stations that the UE 10 must connect to the cellular network 24 in order to be able to receive this packet. The control signaling overhead remains low because the UE is in a time-varying tracking/paging area, and the base station in whose cell 15 the UE 10 is currently located belongs to the set 104 defining this tracking/paging area, and this base station the station already has UE 10 context data at its disposal.

It should be noted that, according to an alternative embodiment, the cellular network in FIG. 19 does not form a time-varying tracking/paging zone schedule 100 . On the contrary, as shown in FIG. 21, according to this alternative, the cellular network 24 uses the received predicted future route information 52 to appropriately select a set 104 of one or more base stations that define a tracking/paging area. Provided that the UE is in this area 104, which was accurately predicted using the predicted future route 52, the control signaling overhead on the UE side can be avoided, which can adversely affect the power consumption of the UE 10. In the example shown in FIG. 21, cellular network 24 sends set 104 to UE 10. In both alternatives discussed above with reference to FIG. 20 and 21, the user node 10 is a user node for communicating over the cellular network 24, and the user node 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 the user node has left it. In the event of leaving, the user node 10 sends a tracking/paging area update message to the cellular network 24, which in turn then re-initiates the tracking/paging area determination of FIG. 20 or FIG. 21, respectively. In case of receiving schedule 100, user node 10 is able to check this schedule 100.

Thus, the above examples in Figs. 19-21 demonstrate the possibility of implementing and autonomously deciding to handover a UE in the RRC dormant state for NR (referred to as loosely connected in LTE), assuming a new context already exists at the new node (already received at the new node due to predictive context relay). In other words, these embodiments allow for a loosely connected UE mode with efficient paging using prediction information.

Efficient paging using prediction information in loosely coupled mode as shown in FIG. 19 allows updating the centralized unit information and the list of tracking area identifiers (TAIs) of various RAN paging/notification areas using the predicted route information of the UE in loosely connected RRC mode (RRC sleep mode is not excluded). The UE conventionally receives a TAI list when initially joining a source eNB in an LTE network. When the UE moves in a tracking area not included in the TAI list, the UE sends a tracking area update (TAU) informing the MME (core network) of its position. In order to be able to efficiently paging using the predicted route information, another solution is proposed whereby the UE does not require updates to be sent to the anchor eNB or centralized unit when the UE changes RAN paging areas/notifications:

1. The source/anchor eNB or centralized unit transmits to the UE a list of almost fully predicted RAN paging/advertisement (pPAI) areas after connection establishment corresponding to the UE's predicted route, avoiding the need for multiple cells of the same paging area to be paged (see Fig. 19) to determine the location of the UE, thus reducing the paging overhead. According to FIG. 19, the UE will receive pPAI={PA1,PA2,PA3} corresponding to the predicted route.

2. To further improve paging performance with respect to finer granularity, another list containing the target eNB IDs may also be provided. For example, the eNB target list may contain, TeNBI={eNB-1,eNB-3, eNB-4, eNB-5, eNB-7} as shown in FIG. 19. In the case of waiting to receive a DL message in a loosely connected mode, the anchor eNB or centralized unit does not need to paging the PA, but rather the individual eNBs in the TeNBI list.

3. In the case where the UE's route abruptly changes route and transitions to a non-pPAI PA, such as PA4 in FIG. 19, the UE notifies the anchor eNB or the central unit of the paging area/RAN notification area (PAU/RNAU) update. An example of additional predicted parameters of the paging message is shown in Table 1:

Table 1: Exemplary Messages for Predictive Paging

IE/group name Description UE-Paging-Area-ID ʺThis IE represents the UE's paging identifier.ʺ [12] pPAI-List List of TAs corresponding to the predicted route TeNBI-List-ID Target eNB IDs along the predicted route

Thus, the above-described embodiment, among other things, provides proactive signaling to the UE based on the UE's route prediction information to implement accelerated HO. Again, note that this can also be used in UEs in dual connectivity mode. High reliability HO using RRC diversity can be performed using route prediction and dual connectivity mode. All of the above embodiments can be applied to wireless communication systems, such as cellular, wireless or mesh wireless networks, as well as wireless ad hoc networks.

Although some aspects have been described in the context of equipment, it is obvious that these aspects also represent a description of the corresponding method, where the block or device corresponds to a method step or a feature of a method step. Likewise, aspects described in the context of a method step also provide a description of the associated block or element or feature of the associated equipment. Some or all of the steps of the method may be performed by (or with) hardware, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important steps of the method may be performed by such equipment.

Depending on some implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation can be carried out using a digital storage medium, such as a floppy disk, DVD, Blu-ray, CD, ROM, PROM, EPROM, EEPROM or flash memory, where electronically readable control signals are stored that cooperate (or are capable of cooperating) with programmable computer system to implement the respective method. Thus, the digital storage medium may be computer-readable.

Some embodiments according to the invention comprise a storage medium having electronically readable control signals that are capable of cooperating with a programmable computer system to implement one of the methods described herein.

In general, embodiments of the present invention may be implemented as a computer program product with program code, wherein the program code is for performing one of the methods when the computer program product is executed on the computer. The program code may, for example, be stored on a computer-readable medium.

Other embodiments comprise a computer program for carrying out one of the methods described herein, stored on a computer-readable medium.

In other words, an embodiment of the method of the invention provides for a computer program having program code for performing one of the methods described herein when the computer program is executed on a computer.

An additional embodiment of the methods of the invention provides for a storage medium (either a digital storage medium or a computer-readable medium) on which a computer program for carrying out one of the methods described herein is recorded. The storage medium, digital storage medium, or recorded medium is typically tangible and/or non-transient.

Thus, a further embodiment of the method of the invention provides for a data stream or sequence of signals representing a computer program for carrying out one of the methods described herein. The data stream or signal sequence may, for example, be carried over a data-capable connection, such as over the Internet.

An additional embodiment comprises processing means, such as a computer or programmable logic device, capable of or adapted to perform one of the methods described herein.

An additional embodiment includes a computer on which a computer program is installed to implement one of the methods described here.

An additional embodiment according to the invention comprises equipment or a system capable of transferring (eg, electronic or optical) a computer program for performing one of the methods described herein to a recipient. The recipient may be, for example, a computer, mobile device, storage device, or the like. The equipment or system may, for example, include a file server for transferring a computer program to a recipient.

In some embodiments, a programmable logic device (eg, a user programmable gate array) may be used to implement some or all of the functionality of the methods described herein. In some embodiments, a user-programmable gate array may cooperate with a microprocessor to implement one of the methods described herein. In general, the methods are preferably implemented in any hardware.

The equipment described herein may be implemented using hardware, or using a computer, or using a combination of hardware and a computer.

The hardware described herein, or any components of the hardware described herein, may be implemented at least in part in hardware and/or software.

The methods described herein may be carried out using hardware, or using a computer, or using a combination of hardware and a computer.

The methods described herein, or any components of the equipment described herein, may be implemented at least in part in hardware and/or software.

The above embodiments are merely illustrative of the principles of the present invention. It should be understood that modifications and variations of the arrangements and details described herein may be suggested by those skilled in the art. Thus, the invention is only to be limited by the scope of the following claims, and not by the specific details provided herein in the description and explanation of the embodiments.

List of abbreviations and symbols

In addition, reference should be made to 3GPP TR 21.905: "3GPP specification dictionary".

eNB Evolved Node B (3G or 4G Base Station) gNB New Generation NR=NB Node (5G Base Station) LTE Long Term Development Project

NR new radio

UE user equipment (user terminal)

HO handover

P-HO predicted handover

RRC radio resource control

MME mobile dispatch node

V2V car to car

V2X from vehicle to infrastructure

SeNB auxiliary eNB

MeNB main eNB

Links

[one] S. Sesia, I. Toufik, and M. Baker, LTE The UMTS Long Term Evolution: From Theory to Practice, 2nd ed. Wiley, 2011 [2] Alcatel Lucent, The LTE Network Architecture: A comprehensive Tutorial, White Paper, pp. 1-26, 2009 [3] Qualcomm, Design details for light connection model A, TDoc R2-168345 [four] LTE; Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP), TS 136 413 V12.3.0 (2014-09), pp. 114 [5] E. Dahlman, S. Parkvall, J. Sköld, ʺ4G, LTE-Advanced Pro and The Road to ^5Gʺ , Elsevier, 3rd Edition, 2016 [6] LTE; Evolved Universal Terrestrial Radio Access Network (E-UTRAN);Overall Description, Stage 2, Release 14, TS 36 300 V14.1.0 (2016-12), pp. 96 [7] 3GPP, ʺStudy on New Radio Access Technology; Radio Access Architecture and Interfaces (Release 14)ʺ, Tech. Rep, TR 36.801 v1.0.0, Dec. 2016. [eight] Technical Specification Group Services and System Aspects; Architecture enhancements for V2X services (Release 14), TS 23.285, V14.1.0, (2016-12) [9] Intelligent Transport Systems (ITS); Framework for Public Mobile Networks in Cooperative ITS (C-ITS); ETSI TR 102 962 V1.1.1 (2012-02), pp. 37 [ten] Zhang et al., LTE Small Cell Enhancement by Dual Connectivity, Wireless World Research Forum, White Paper, Nov. 2014. [eleven] Broadcom Corporation, ʺMobility for dual connectivityʺ, T-DOC, R2-130990, 2013. [12] Frédéric Firmin, NAS, 3GPP, http://www.3gpp.org/technologies/keywords-acronyms/96-nas, Last Accessed 27 January 2017. [13] Developing Solutions, About the S1 Dictionary, http://www.developingsolutions.com/S1Dict/Topics/About.htm, Last Accessed 27January 2017. [fourteen] Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of Applications; Part 2: Specification of Cooperative Awareness Basic Service, ETSI TS 102 637-2 V1.2.1, Mar. 2011. [fifteen] Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set of Applications; Part 3: Specifications of Decentralized Environmental Notification Basic Service, Final draft ETSI EN 302 637-3 V1.2.1, Sep. 2014.

Claims (78)

1. Cellular network supporting proactive handover preparation for the user node, the cellular network is designed to: determining a preliminary set of base stations of the cellular network, wherein the number of elements of the preliminary set of base stations is greater than one; and sending a request from the centralized unit of the cellular network to each of the preliminary set of base stations of the cellular network about the availability of the cellular network through the corresponding base station at the expected time when the user node enters the cell of the corresponding base station, and sending a response from the corresponding base station to the centralized unit. 2. The cellular network as claimed in claim 1, wherein the cellular network is configured to initiate proactive handover preparation depending on the predicted future route information (52) of the user node. 3. Cellular network according to claim 2, wherein the cellular network is configured to: receive information about the predicted future route (52) of the user node (10) from custom node or a device other than the cellular network and other than the user site, or determine the predicted future route (52) of the user node. 4. Cellular network according to claim 1, wherein the cellular network is configured to initiate proactive preparation of a handover initiated by a user node entering a predetermined zone (56), and/or initiate proactive preparation of a handover triggered by the position history of the user node meeting a predetermined criterion. 5. The cellular network according to claim 1, wherein the cellular network is configured to perform proactive handover preparation by establishing, for each of a set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters. 6. The cellular network according to claim 1, wherein the cellular network is configured to perform proactive handover preparation by establishing, for each base station x from a set of one or more base stations of the cellular network, an access time interval (60) starting at the initial time t ^x _start , and one or more access parameters (66), so that allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters, and sending to the user node a schedule indicating the start time t ^x _start and one or more access parameters (66) for each base station x from the set of one or more base stations. 7. Cellular network according to claim. 1, and the cellular network is configured to perform proactive handover preparation by establishing, for each base station x from a set of one or more base stations of the cellular network, an access time slot (60) starting at the start time t ^x _start and ending at the end time, and one or more access parameters (66), so that allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters, and sending to the user node a schedule indicating the start time t ^x _start , one or more access parameters (66) and when the access time interval ends for each base station x from the set of one or more base stations. 8. Cellular network according to claim 5, wherein the cellular network is configured to determine a set of one or more base stations of the cellular network based on the predicted future route (52), whereby the set (64) of one or more base stations is located along the predicted future route (52). 9. Cellular network according to claim. 1, in which the request includes information about one or more current identifiers by which the user node (10) is identified in the cellular network. 10. Cellular network according to claim 5, wherein the cellular network is configured in such a way that each of the set (64) of one or more base stations reserves radio access resources specified by one or more access parameters (66) for the corresponding base station during the time interval access for the corresponding base station. 11. A cellular network supporting proactive handover preparation for a user node, the cellular network comprising a network node configured to perform proactive handover preparation by establishing, for each of the set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters; and perform proactive handover preparation by further scheduling, for each of the set (64) of one or more base stations of the cellular network, redirecting packets of one or more transmissions passing through the cellular network and the user node, whereby the packets are distributed to each of the set of one or more more base stations of the cellular network, depending on the access time interval for the corresponding base station. 12. The cellular network of claim. 5, in which the number of elements of the set of one or more base stations is greater than one. 13. A cellular network supporting proactive handover preparation for a user node, the cellular network comprising a network node configured to perform proactive handover preparation by establishing, for each of the set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters; and setting, for at least one of the set of one or more base stations, an access time slot such that the time access is indicated by a start time of the access time slot. 14. The cellular network according to claim 5, wherein the cellular network is configured to provide the user node with a schedule indicating, at least for each of the subsets of the set of one or more base stations, access timeslot and one or more access parameters. 15. A cellular network supporting proactive handover preparation for a user node, the cellular network comprising a network node configured to perform proactive handover preparation by establishing, for each of the set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters; and in the case of access to the cellular network by the user node through one of the set (64) of one or more base stations, redirect the internal subpath of the cellular network of each of the set of current communication paths passing through the cellular network and the user node (10), from the base station, through which the user node is currently connected to the cellular network, to one of the set of base stations. 16. The cellular network according to claim 5, wherein the cellular network is configured to, in the event that the user node accesses the cellular network through one of the set (64) of one or more base stations, to further release resources at the base station through which the user node (10) previously connected to a cellular network. 17. The cellular network of claim 1, wherein the cellular network is configured to resume communication with the user node after losing communication with the user node via a pre-arranged handover. 18. A method for operating a cellular network, comprising preparing a preemptive handover for a user node, the method comprising: determining a preliminary set of base stations of the cellular network, wherein the number of elements of the preliminary set of base stations is greater than one; and sending a request from the centralized unit of the cellular network to each of the preliminary set of base stations of the cellular network about the availability of the cellular network through the corresponding base station at the expected time when the user node enters the cell of the corresponding base station, and sending a response from the corresponding base station to the centralized unit. 19. A method for operating a cellular network, comprising preparing a preemptive handover for a user node, performed by a network node, the method comprising: performing proactive handover preparation by establishing, for each of the set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters; and performing proactive handover preparation by additional scheduling, for each of the set (64) of one or more base stations of the cellular network, redirecting packets of one or more transmissions passing through the cellular network and the user node, whereby the packets are distributed to each of the set of one or more more base stations of the cellular network, depending on the access time interval for the corresponding base station. 20. A method for operating a cellular network, comprising preparing a preemptive handover for a user node, performed by a network node, the method comprising: performing proactive handover preparation by establishing, for each of the set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters; and setting, for at least one of the set of one or more base stations, an access slot such that the access slot is a future start slot. 21. A method for operating a cellular network, comprising preparing a preemptive handover for a user node, performed by a network node, the method comprising: performing proactive handover preparation by establishing, for each of the set of one or more base stations of the cellular network, time slot (60) access and one or more access parameters (66), so that it allows the user node (10) to access the cellular network through the corresponding base station during the access time interval using one or more access parameters; and in the case of access to the cellular network by the user node through one of the set (64) of one or more base stations, redirect the internal subpath of the cellular network of each of the set of current communication paths passing through the cellular network and the user node (10), from the base station, through which the user node is currently connected to the cellular network, to one of the set of base stations. 22. A computer-readable medium containing a computer program executable by a computer and instructing him to perform the method according to one of paragraphs. 18-21.

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