WO2015052208A1

WO2015052208A1 - A method and apparatus for mobility management

Info

Publication number: WO2015052208A1
Application number: PCT/EP2014/071486
Authority: WO
Inventors: Per Henrik Michaelsen; Lars Dalsgaard
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2013-10-09
Filing date: 2014-10-08
Publication date: 2015-04-16

Abstract

A method and apparatus can be configured to receive an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by the user equipment. The method can also include reporting at least one cell that fulfills the first condition or a second condition as a reported cell. The method can also include selecting a cell as a selected cell. The method can also include determining whether the selected cell corresponds to at least one reported cell. The method can also include performing either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

Description

DESCRIPTION TITLE

A METHOD AND APPARATUS FOR MOBILITY MANAGEMENT

BACKGROUND: Field:

[0001] Embodiments of the invention relate to a method and an apparatus for mobility management.

Description of the Related Art:

[0002] Long-term Evolution (LTE) is a standard for wireless communication that seeks to provide improved speed and capacity for wireless communications by using new modulation/signal processing techniques. The standard was proposed by the 3^rd Generation Partnership Project (3GPP), and is based upon previous network technologies. Since its inception, LTE has seen extensive deployment in a wide variety of contexts involving the communication of data.

SUMMARY:

[0003] According to a first embodiment, a method may include receiving, by a user equipment, an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by the user equipment. The method may also include reporting at least one cell that fulfills the first condition or a second condition as a reported cell. The method may also include selecting a cell as a selected cell. The method may also include determining whether the selected cell corresponds to at least one reported cell. The method may also include performing either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

[0004] In the method of the first embodiment, the first condition corresponds to an entering condition. [0005] In the method of the first embodiment, the second condition corresponds to a leaving condition.

[0006] In the method of the first embodiment, the prepared cells correspond to cells with user-equipment context or supporting context fetch.

[0007] In the method of the first embodiment, the selecting, the determining, and the performing are performed after at least one of an occurrence of a radio-link failure and a sending of a measurement report.

[0008] In the method of the first embodiment, the receiving comprises receiving an indication that the network will consider cells reported to the network, upon occurrence of an event, e.g., an event, as prepared cells.

[0009] In the method of the first embodiment, the determining comprises determining whether a cell corresponds to at least one reported cell. For example, the method may determine whether a physical-cell identification of a selected cell corresponds to a physical- cell identification of at least one reported cell.

[0010] According to a second embodiment, an apparatus may include at least one processor. The apparatus may also include at least one memory including computer program code. The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus at least to receive an indication that cells reported as fulfilling a first condition can be considered to be prepared cells, wherein the cells reported as fulfilling the first condition are reported to a network by the user equipment. The apparatus may also be caused to report at least one cell that fulfills the first condition or a second condition as a reported cell. The apparatus may also be caused to select a cell as a selected cell. The apparatus may also be caused to determine whether the selected cell corresponds to at least one reported cell. The apparatus may also be caused to perform either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

[0011] In the apparatus of the second embodiment, the first condition corresponds to an entering condition.

[0012] In the apparatus of the second embodiment, the second condition corresponds to a leaving condition.

[0013] In the apparatus of the second embodiment, the prepared cells correspond to cells with user-equipment context or supporting context fetch. [0014] In the apparatus of the second embodiment, the selecting, the determining, and the performing are performed after at least one of an occurrence of a radio-link failure and a sending of a measurement report.

[0015] In the apparatus of the second embodiment, the receiving comprises receiving an indication that the network will consider cells reported to the network, upon occurrence of an event, e.g., an event A4, as prepared cells.

[0016] In the apparatus of the second embodiment, the determining comprises determining whether a selected cell corresponds to at least one reported cell. For example, the apparatus may determine whether a physical-cell identification of a selected cell corresponds to a physical-cell identification of at least one reported cell.

[0017] According to a third embodiment, a computer program product may be embodied on a non-transitory computer readable medium. The computer program product may be configured to control a processor to perform a process including receiving, by a user equipment, an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by the user equipment. The process may also include reporting at least one cell that fulfills the first condition or a second condition as a reported cell. The process may also include selecting a cell as a selected cell. The process may also include determining whether the selected cell corresponds to at least one reported cell. The process may also include performing either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition. Call establishment may also be performed if the selected cell does not correspond to a reported cell.

[0018] According to a fourth embodiment, a method may include transmitting, by a network node, an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells. For example, the network may prepare the reported cells. The cells reported as fulfilling the first condition are reported to the network by a user equipment. The method may also include receiving a reporting of at least one reported cell that fulfills the first condition or a second condition.

[0019] In the method of the fourth embodiment, the transmitting and the receiving are performed before a radio-link failure occurs. [0020] In the method of the fourth embodiment, the transmitting may include transmitting an indication that the network will consider cells reported to the network, upon occurrence of an event, e.g., an event, as being prepared cells.

[0021] According to a fifth embodiment, an apparatus may include at least one processor. The apparatus may also include at least one memory including computer program code. The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus at least to transmit an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells. The cells reported as fulfilling the first condition are reported to the network by a user equipment. The apparatus may also be caused to receive a reporting of at least one reported cell that fulfills the first condition or a second condition.

[0022] In the apparatus of the fifth embodiment, the transmitting and the receiving are performed before a radio-link failure occurs.

[0023] In the apparatus of the fifth embodiment, the transmitting includes transmitting an indication that the network will consider cells reported to the network, upon occurrence of an event, e.g., an event A4, as being prepared cells.

[0024] According to a sixth embodiment, a computer program product may be embodied on a non-transitory computer readable medium. The computer program product may be configured to control a processor to perform a process including transmitting, by a network node, an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells. The cells reported as fulfilling the first condition are reported to the network by a user equipment. The process may include receiving a reporting of at least one reported cell that fulfills the first condition or a second condition.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0025] For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:

[0026] Fig. 1 illustrates a flowchart of a method in accordance with embodiments of the invention.

[0027] Fig. 2 illustrates a flowchart of a method in accordance with embodiments of the invention. [0028] Fig. 3 illustrates an apparatus in accordance with embodiments of the invention.

[0029] Fig. 4 illustrates an apparatus in accordance with embodiments of the invention.

[0030] Fig. 5 illustrates an apparatus in accordance with embodiments of the invention.

[0031] Fig. 6 illustrates an apparatus in accordance with embodiments of the invention.

[0032] Fig. 7 illustrates an apparatus in accordance with embodiments of the invention.

[0033] Fig. 8 illustrates a system in accordance with embodiments of the invention.

DETAILED DESCRIPTION: [0034] Embodiments of the present invention are related to user-equipment-controlled (UE- controlled) mobility management.

[0035] A UE can experience radio-link problems that culminate in Radio Link Failure (RLF) between the UE and a corresponding serving cell. As a result of the RLF, the UE can execute a call re-establishment procedure to try to re-establish the radio link between the UE and the corresponding serving cell. The corresponding serving cell may be a former serving cell or a newly selected cell. In the event that the serving cell is not prepared for re-establishing the radio link to the UE, the connection between the UE and the network will be dropped. The cell may not be prepared for re-establishment because the cell may not have the required UE context.

[0036] Embodiments of the present invention can be directed to providing mobility management without having knowledge of velocities of the UE and without having UE Mobility State Estimation (MSE) information.

[0037] As described above, embodiments of the present invention address the problem where a UE experiences radio link problems that culminate in radio-link failure (RLF), which is then followed by a call re-establishment attempt with a selected cell. In the event that the selected cell is not prepared (e.g., if the cell does not have the UE context, for example), then re-establishment will not be successful and the connection between the UE and the network will be dropped.

[0038] One previous approach for performing re-establishment of a connection between a UE and a corresponding serving cell is to have the network send a list of prepared cells to the UE. For example, the list of prepared cells can be transmitted by a base station to the UE. The list of prepared cells can correspond to a listing of the cells that the UE can successfully connect to. The list of prepared cells can then be used by the UE during the re- establishment procedure for selecting an appropriate cell to connect with.

[0039] However, a shortcoming of this previous approach is that this approach relies on transmitting the list of prepared cells (with the list of prepared cells likely based on a UE measurement report) via network signaling to the UE. This list of prepared cells may need to be updated frequently. The need to frequently transmit the list of prepared cells, as required by the previous approaches, can be burdensome.

[0040] According to the previous approaches, with the current 3GPP specification, the UE is relied upon to perform the function of call re-establishment. If the corresponding serving cell is not prepared for re-establishing the call/connection with the UE, the re-establishment attempt will be rejected by the network, resulting in the failure of the re-establishment attempt. Once the re-establishment attempt fails, the UE can enter into an "idle" state. Once the "idle" state is reached, a call can then be established as opposed to being re-established. A normal call establishment procedure can occur from the "idle" state.

[0041] Embodiments of the present invention are directed to a method of improving a call re-establishment procedure between a UE and a corresponding serving cell without needing to pre-configure the UE with a list of prepared cells. Embodiments of the present invention can be directed to a procedure to be performed by the UE. Embodiments of the present invention can use a network indication to indicate, to the UE, that the UE should follow the procedure.

[0042] The network indicates, to the UE, that the UE should consider certain cells that the UE has reported to the network as being prepared cells (i.e., the network indicates to the UE that these cells will have the appropriate UE context). For example, the reporting can be based on event A4 and/or can be based on using "Entering" and "Leaving" conditions. Event

A4 can generally correspond to the circumstance when a signal strength of a neighbor cell becomes better than a certain threshold.

[0043] If RLF occurs, and if the UE begins cell selection, the UE can use the cells that the UE reported to the network. The UE reporting can be based on network configuration. For example, the network can configure the UE with a carrier and an event (such as an event A4) including entering and leaving conditions and a suitable threshold (and other settings according to 3GPP TS 36.331 ). The UE performs cell detection and measurements on the given carrier. When the measurements, for example, from a cell are better than the indicated threshold, the UE can send a measurement report that indicates an entering condition to the network. For example, the UE can report the cells to a base station, or to some other network node. The UE can perform cell selection (potentially on the carrier on which the reported cells are deployed, for example, by using an existing stored-list-cell-selection procedure), and the UE can camp on a suitable cell. The UE can then compare the identity of a selected cell, e.g., the cell's physical cell ID (PCI), with identities of earlier reported cells (e.g., the PCIs of earlier/most-recently reported cells).

[0044] If the identity of the selected cell (for example, the PCI of the selected cell) matches a PCI that has been earlier reported by the UE to the network, the UE may perform call re- establishment with the selected cell. On the other hand, if the PCI of the selected cell does not match the PCI of an earlier-reported cell, the UE may either choose another cell or directly perform call establishment. The comparing can, for example, be restricted to a given Carrier (MeasObject), a specific Measld (object and event), and/or a specific Event. Methods of embodiments of the present invention can be applied in different ways, such as, (1 ) on a carrier level - the network indicates that the methods are applied for any cell reported from a given carrier, (2) the methods are only applied to cells reported for a given carrier, and/or (3) the methods are only applied to a specific event, for example.

[0045] Although the embodiments of the present invention have been described above in connection with radio-link monitoring (RLM), radio-link-failure (RLF), and the performing of re- establishment procedures, embodiments of the present invention are not limited to be used in conjunction with RLM, and/or RLF, nor limited to providing re-establishment procedures. Embodiments of the present invention can be applied in a general manner, for example, in connection with UE-autonomous mobility management (i.e., UE-controlled mobility management as compared to network-controlled mobility management). For example, the UE can perform call re-establishment after a cell change if the new cell has been earlier reported to the network by the UE. Otherwise, as described above, if the new cell was not earlier reported to the network by the UE, the UE can perform call establishment, as opposed to call re-establishment.

[0046] Additionally, embodiments of the present invention can generally be used in conjunction with any measurement report and with any cell that has been reported by a UE. The method of determining the performing of call re-establishment/establishment, based on whether the UE has earlier reported a cell or not, can be applied to any reported cell by the

UE. The UE can report on cells on multiple carriers and Radio Access Technologies (RATs).

[0047] Radio Link Monitoring requirements for the UE are, for example, described in 3GPP 36.133 (section 7.6). UE re-establishment delay requirements are also described in 3GPP 36.133 (section 6.1.2.1 ). The UE procedure of determining to either perform call re- establishment or to perform call establishment can be used in connection with, for example, reception of thresholds Qin and Qout, timers T310 and T31 1 , and the actions related to detection of RLF.

[0048] In one example of performing a method in accordance with embodiments of the present invention, first, an evolved Node B (eNB) can configure a UE with a measurement configuration. Measurement configurations can be prepared, for example, in accordance with the current procedures as defined in 3GPP TS 36.331 . For example, a network can configure the UE to measure a given carrier (Object) and send a measurement report if a neighbor cell on that carrier is better than a set threshold for a given time. For example, an Event A4 (inter-frequency) can be used for reporting when a neighbor cell becomes better than a certain threshold (or some other event that the network sees as most beneficial for this purpose), triggering an "entering" condition. A "Leaving" condition can also be used as a reporting trigger that would ensure that the network has received updated information related to the cell or cells which are within a given range of, for example, a Reference-Signal- Received- Power (RSRP) or a Reference-Signal-Received-Quality (RSRQ). The UE can then measure and evaluate information relating to the cells. The UE can then update/report the information to the network when triggered to do so. The network will receive the results of the report and decide whether and/or when to prepare neighbor cells. The network can then configure the UE such that the UE is aware that when the UE sends, for example, the A4 report (maybe for a given carrier), the UE should use the reported cells according to a new behavior. The UE can assume that the cells which are reported as fulfilling the "entering" condition have UE context, and the UE should perform call re-establishment on such cells. Cells that are reported as fulfilling the "leaving" condition are no longer regarded as prepared cells. One method of the present invention also helps the network in preparing the correct cells (cells which fulfill the "entering" condition) and keeps an updated set of prepared cells by removing, from the set of prepared cells, the cells which are reported as fulfilling the "leaving" condition.

[0049] Second, the UE can continue to perform measurements in conjunction with the performing of RLM functionality.

[0050] Third, upon occurrence of a number of "out-of-sync" indications, a timer can start. For example, upon the occurrence of N310 consecutive "out-of-sync" indications, a timer

T310 can start. Timer T310 can be a timer used to determine whether a radio link failure has occurred.

[0051] Fourth, a RLF can be detected. Upon expiry of the timer T310, a radio link failure can be considered to be detected. A connection re-establishment procedure can then be initiated. [0052] Fifth, embodiments of the present invention can attempt to re-establish a connection between a UE and a cell. The UE can perform cell selection in accordance with the cell selection process as specified in Technical Specification 36.304. The cell selection can be performed by using, for example, the existing cell selections with a stored-list-cell-selection procedure. The cell selection can also be performed by using any optimized UE procedure, for example, based on reported cells.

[0053] Sixth, after performing successful cell selection (a suitable cell has been detected according to existing UE implementation, for example), a selected cell can be compared with cells reported to the network (for example, the PCIs can be compared). If the selected cell has been earlier reported to the network by the UE as meeting a condition (such as the "entering" condition, for example), the UE can perform call re-establishment. Otherwise, if the selected cell has not been earlier reported to the network as meeting the conditions for re-establishment, the UE can instead perform call establishment.

[0054] Embodiments of the present invention can configure a UE in various ways. In one configuration, the network can indicate to the UE to apply the method for a given specific carrier and for cells reported on that carrier. This indication could be given together with the measurement configuration (when configuring the UE to perform measurements on that carrier), for example. Whenever the UE reports cells on that carrier, the UE stores reported cells. In one embodiment, the UE can store the latest cells. In one embodiment, the UE can store the PCIs of the cells. The network can use this information to prepare the reported cells. In case RLF occurs, the UE can compare the identity (e.g., the PCI of the new source cell) with the set of reported cells. If there is a cell identity/PCI match between a new source cell and a cell that has been reported as meeting the necessary condition, the UE can apply call re-establishment, otherwise the UE can perform normal call establishment.

[0055] In embodiments of the present invention, one option for simplifying the usage would be to combine the above-described methods with a network that is able to indicate to the UE if the above-described methods should be applied to a certain carrier or a set of carriers. For example, the network can indicate that the reported cells for which these methods are to be applied should be on a given carrier(s).

[0056] In view of the above, in embodiments of the present invention, there may be no need for signaling. However, other embodiments may use some signaling support. There may be no need for the UE and the network to keep and update a list of prepared cells. Embodiments of the present invention can reduce signaling (for example, there may be no additional signaling exchange between the UE and the network compared to what is needed by the previous approaches). The methods of the present invention can be generally applied. Embodiments of the present invention can reduce call establishment times.

[0057] Fig. 1 illustrates a flowchart of a method in accordance with embodiments of the invention. The method illustrated in Fig. 1 includes, at 100, receiving an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by the user equipment. The method can also include, at 101 , reporting at least one cell that fulfills the first condition or a second condition as a reported cell. The method can also include, at 102, selecting a cell as a selected cell. The method can also include, at 103, determining whether the selected cell corresponds to at least one reported cell. The method can also include, at 104, performing either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition. Call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

[0058] Fig. 2 illustrates a flowchart of a method in accordance with embodiments of the invention. The method illustrated in Fig. 2 includes, at 200, transmitting an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells. The cells reported as fulfilling the first condition are reported to the network by a user equipment. The method can also include, at 201 , receiving a reporting of at least one reported cell that fulfills the first condition or a second condition.

[0059] Fig. 3 illustrates an apparatus in accordance with embodiments of the invention. In one embodiment, the apparatus can be a user device. In another embodiment, the apparatus can be a network node (such as a base station and/or an eNB, for example). Apparatus 10 can include a processor 22 for processing information and executing instructions or operations. Processor 22 can be any type of general or specific purpose processor. While a single processor 22 is shown in Fig. 3, multiple processors can be utilized according to other embodiments. Processor 22 can also include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, as examples.

[0060] Apparatus 10 can further include a memory 14, coupled to processor 22, for storing information and instructions that can be executed by processor 22. Memory 14 can be one or more memories and of any type suitable to the local application environment, and can be implemented using any suitable volatile or nonvolatile data storage technology such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and removable memory. For example, memory 14 include any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, or any other type of non-transitory machine or computer readable media. The instructions stored in memory 14 can include program instructions or computer program code that, when executed by processor 22, enable the apparatus 10 to perform tasks as described herein.

[0061] Apparatus 10 can also include one or more antennas (not shown) for transmitting and receiving signals and/or data to and from apparatus 10. Apparatus 10 can further include a transceiver 28 that modulates information on to a carrier waveform for transmission by the antenna(s) and demodulates information received via the antenna(s) for further processing by other elements of apparatus 10. In other embodiments, transceiver 28 can be capable of transmitting and receiving signals or data directly.

[0062] Processor 22 can perform functions associated with the operation of apparatus 10 including, without limitation, precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatus 10, including processes related to management of communication resources.

[0063] In an embodiment, memory 14 can store software modules that provide functionality when executed by processor 22. The modules can include an operating system 15 that provides operating system functionality for apparatus 10. The memory can also store one or more functional modules 18, such as an application or program, to provide additional functionality for apparatus 10. The components of apparatus 10 can be implemented in hardware, or as any suitable combination of hardware and software.

[0064] Fig. 4 illustrates an apparatus in accordance with embodiments of the invention. Apparatus 400 can be a user equipment, for example. Apparatus 400 can include a receiving unit 401 that receives an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by the user equipment. Apparatus 400 can also include a reporting unit 402 that reports at least one cell that fulfills the first condition or a second condition as a reported cell. Apparatus 400 can also include a selecting unit 403 that selects a cell as a selected cell. Apparatus 400 can also include a determining unit 404 that determines whether the selected cell corresponds to at least one reported cell. Apparatus 400 can also include a performing unit 405 that performs either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

[0065] Fig. 5 illustrates an apparatus in accordance with embodiments of the invention. Apparatus 500 can be a network node, for example. For example, apparatus 500 can be a base station and/or an evolved Node B. Apparatus 500 can include a transmitting unit 501 that transmits, by a network node, an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells. The cells reported as fulfilling the first condition are reported to the network by a user equipment. Apparatus 500 can also include a receiving unit 502 that receives a reporting of at least one reported cell that fulfills the first condition or a second condition.

[0066] Fig. 6 illustrates an apparatus in accordance with embodiments of the invention. Apparatus 600 can be a user equipment, for example. Apparatus 600 can include a receiving means 601 that receives an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by apparatus 600. Apparatus 600 can also include a reporting means 602 that reports at least one cell that fulfills the first condition or a second condition as a reported cell. Apparatus 600 can also include a selecting means 603 that selects a cell as a selected cell. Apparatus 600 can also include a determining means 604 that determines whether the selected cell corresponds to at least one reported cell. Apparatus 600 can also include a performing means 605 that performs either call re-establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

[0067] Fig. 7 illustrates an apparatus in accordance with embodiments of the invention. Apparatus 700 can be a network node, for example. For example, apparatus 700 can be a base station and/or an evolved Node B. Apparatus 700 can include a transmitting means 701 that transmits an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells. The cells reported as fulfilling the first condition are reported to the network by a user equipment. Apparatus 700 can also include a receiving means 702 that receives a reporting of at least one reported cell that fulfills the first condition or a second condition.

[0068] Fig. 8 illustrates a system 850 in accordance with embodiments of the invention. System 850 includes a first apparatus 800. First apparatus 800 may include a first receiving means 801 that receives an indication that cells reported as fulfilling a first condition can be considered to be prepared cells. The cells reported as fulfilling the first condition are reported to a network by the first apparatus 800. First apparatus 800 can also include a reporting means 802 that reports at least one cell that fulfills the first condition or a second condition as a reported cell. First apparatus 800 can also include a selecting means 803 that selects a cell as a selected cell. First apparatus 800 can also include a determining means 804 that determines whether the selected cell corresponds to at least one reported cell. First apparatus 800 can also include a performing means 805 that performs either call re- establishment or call establishment. Call re-establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition. System 850 may also include a second apparatus 810. Second apparatus 810 may include a transmitting means 81 1 that transmits the indication that the network can consider cells reported as fulfilling the first condition as being the prepared cells. The cells reported as fulfilling the first condition are reported to the network by the first apparatus 800. Second apparatus 810 can also include a second receiving means 812 that receives the reporting of at least one reported cell that fulfills the first condition or the second condition.

[0069] The described features, advantages, and characteristics of the invention can be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages can be recognized in certain embodiments that may not be present in all embodiments of the invention. One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.

Claims

WE CLAIM:

1 . A method, comprising: receiving, by a user equipment, an indication that cells reported as fulfilling a first condition can be considered to be prepared cells, wherein the cells reported as fulfilling the first condition are reported to a network by the user equipment; reporting at least one cell that fulfills the first condition or a second condition as a reported cell; selecting a cell as a selected cell; determining whether the selected cell corresponds to at least one reported cell; and performing either call re-establishment or call establishment, wherein call re- establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

2. The method according to claim 1 , wherein the first condition corresponds to an entering condition.

3. The method according to claim 1 or 2, wherein the second condition corresponds to a leaving condition.

4. The method according to any of claims 1 -3, wherein the prepared cells correspond to cells with user-equipment context or supporting context fetch.

5. The method according to any of claims 1 -4, wherein the selecting, the determining, and the performing are performed after at least one of an occurrence of a radio- link failure and a sending of a measurement report.

6. The method according to any of claims 1 -5, wherein the receiving comprises receiving an indication that the network will consider cells reported to the network, upon occurrence of an event, as prepared cells.

7. The method according to any of claims 1 -6, wherein the determining comprises determining whether a physical-cell identification of the selected cell corresponds to a physical-cell identification of at least one reported cell.

8. An apparatus, comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus at least to receive an indication that cells reported as fulfilling a first condition can be considered to be prepared cells, wherein the cells reported as fulfilling the first condition are reported to a network by the user equipment; report at least one cell that fulfills the first condition or a second condition as a reported cell; select a cell as a selected cell; determine whether the selected cell corresponds to at least one reported cell; and perform either call re-establishment or call establishment, wherein call re- establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

9. The apparatus according to claim 8, wherein the first condition corresponds to an entering condition.

10. The apparatus according to claim 8 or 9, wherein the second condition corresponds to a leaving condition.

1 1 . The apparatus according to any of claims 8-10, wherein the prepared cells correspond to cells with user-equipment context or supporting context fetch.

12. The apparatus according to any of claims 8-1 1 , wherein the selecting, the determining, and the performing are performed after at least one of an occurrence of a radio- link failure and a sending of a measurement report.

13. The apparatus according to any of claims 8-12, wherein the receiving comprises receiving an indication that the network will consider cells reported to the network, upon occurrence of an event, as prepared cells.

14. The apparatus according to any of claims 8-13, wherein the determining comprises determining whether a physical-cell identification of the selected cell corresponds to a physical-cell identification of at least one reported cell.

15. A computer program product, embodied on a non-transitory computer readable medium, the computer program product configured to control a processor to perform a process, comprising: receiving, by a user equipment, an indication that cells reported as fulfilling a first condition can be considered to be prepared cells, wherein the cells reported as fulfilling the first condition are reported to a network by the user equipment; reporting at least one cell that fulfills the first condition or a second condition as a reported cell; selecting a cell as a selected cell; determining whether the selected cell corresponds to at least one reported cell; and performing either call re-establishment or call establishment, wherein call re- establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the first condition, and call establishment is performed if the selected cell corresponds to at least one reported cell and fulfills the second condition.

16. A method, comprising: transmitting, by a network node, an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells, wherein the cells reported as fulfilling the first condition are reported to the network by a user equipment; and receiving a reporting of at least one reported cell that fulfills the first condition or a second condition.

17. The method according to claim 16, wherein the transmitting and the receiving are performed before a radio-link failure occurs.

18. The method according to claim 16 or 17, wherein the transmitting comprises transmitting an indication that the network will consider cells reported to the network, upon occurrence of an event, as being prepared cells.

19. An apparatus, comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus at least to transmit an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells, wherein the cells reported as fulfilling the first condition are reported to the network by a user equipment; and receive a reporting of at least one reported cell that fulfills the first condition or a second condition.

20. The apparatus according to claim 19, wherein the transmitting and the receiving performed before a radio-link failure occurs.

21 . The apparatus according to claim 19 or 20, wherein the transmitting comprises transmitting an indication that the network will consider cells reported to the network, upon occurrence of an event, as being prepared cells.

22. A computer program product, embodied on a non-transitory computer readable medium, the computer program product configured to control a processor to perform a process, comprising: transmitting, by a network node, an indication that a network can consider cells reported as fulfilling a first condition as being prepared cells, wherein the cells reported as fulfilling the first condition are reported to the network by a user equipment; and receiving a reporting of at least one reported cell that fulfills the first condition or a second condition.