Method of managing handover between cells in cellular telecommunication network

Abstract

A method of managing handover between cells in a cellular telecommunications network, comprising: communicating power mode data of a source cell to one or more active user equipments (UEs) served by the source cell; determining conditional handover configuration data for each of the one or more potential target cells, wherein the conditional handover configuration data includes one or more handover execution conditions; based on the power mode data, one or more switching execution conditions are modified.

Description

Technical Field

[0001] The present invention relates to managing handovers in a cellular network. In particular, the present invention provides a method for managing handovers of active UEs connected to the network via a serving cell scheduled to enter a power saving mode. Background Art

[0002] Energy consumption in mobile telecommunications networks is a significant component (typically between 20% and 90%) of network operating expenditure (OPEX). In particular, much of the power consumption may be attributed to base stations in the radio access network (with data centers also consuming significant power).

[0003] In a 5G network, the energy consumption of a 5G site depends on the active devices rather than the data load on the devices. Compared to previous network technologies, the total energy consumption of a 5G site increases because more antennas, more frequency bands, and a denser network of small cells are required instead of relatively fewer large cells. In one example, a typical 5G site may require about 11.5Kw of power, which is about 70% more than a 2G / 3G / 4G base station that provides similar coverage levels.

[0004] Within a base station, radio frequency (RF) equipment (power amplifiers, transceivers, cables, etc.) is the largest component of energy consumption. Typically, RF equipment uses about 65% of the total energy consumed by a base station. For comparison, cooling consumes about 17.5%, digital signal processing / baseband consumes about 10%, and AC / DC converters consume about 7.5%.

[0005] Improving energy efficiency in mobile networks can be achieved through a variety of solutions, including smart buildings, virtualized core, and improving RAN efficiency through modernization of legacy equipment and implementation of low power solutions to optimize power consumption and efficiency on both the UE and network side. The object of the present invention is to provide a new method for improving power efficiency in telecommunication networks. Summary of the invention

[0006] The present invention provides a method for managing handover between cells in a cellular telecommunication network, the method comprising:

[0007] delivering power mode data of the source cell to one or more user equipments UE (preferably active UEs) served by the source cell;

[0008] determining, for each of the one or more potential target cells, conditional handover configuration data and one or more associated handover execution conditions; and

[0009] One or more switching execution conditions are modified based on the power mode data.

[0010] As used in this application, the step of "delivering" may include sending and / or receiving. Therefore, delivering an indication to a UE may be interpreted as sending an indication to the UE or receiving an indication by the UE. In the same manner, delivering an indication from a base station may be interpreted as sending an indication by the base station or receiving an indication from the base station.

[0011] There may be one or more base stations associated with each source cell.The power mode data of the source cell may include power mode data of one or more base stations associated with the source cell.

[0012] The method may also include identifying one or more potential target cells.

[0013] One or more handover execution conditions may be modified based on determining that the source cell is scheduled to enter a power save mode.

[0014] Preferably, the power mode data includes one or more of the following:

[0015] an indication (e.g., actual time or countdown) that the source cell is scheduled to enter power saving mode;

[0016] The time when the source cell is scheduled to enter the power saving mode;

[0017] The remaining time until the source cell is scheduled to enter power saving mode;

[0018] one or more threshold modification instructions based on a remaining time until the source cell is scheduled to enter a power save mode; and

[0019] One or more offset modification instructions based on a remaining time until the source cell is scheduled to enter a power save mode.

[0020] Preferably, the one or more switching execution conditions include:

[0021] Determine that the signal measurement value of the corresponding potential target cell is greater than the signal measurement value of the source cell by at least one offset,

[0022] Wherein modifying the one or more handover execution conditions comprises modifying an offset based on a remaining time until the source cell is scheduled to enter a power saving mode.

[0023] As used in this application, a signal measurement that is "larger" than another signal measurement may be interpreted as providing a better signal. Where signal measurements are provided in decibels (dB) or decibel meters (dBm), these values ​​may typically be negative. For example, in this case, a value of -80 dBm is interpreted as a value greater than -100 dBm. Where the signal measurement relates to a characteristic that is better when the value is lower (such as latency), the skilled person will appreciate that a handover should be triggered when it is determined that the signal measurement of the corresponding potential target cell is at least one offset lower (or below a threshold) than the signal measurement of the source cell.

[0024] Preferably, the one or more switching execution conditions include:

[0025] Determine that the signal measurement value of the corresponding potential target cell is greater than a threshold level,

[0026] Wherein modifying one or more handover execution conditions includes modifying a threshold level based on the remaining time until the source cell is scheduled to enter a power saving mode. (When there is not much time left, the signal measurement value of the serving cell is not considered, and only the signal measurement value of the potential target cell is considered)

[0027] Preferably, each of the one or more switching execution conditions includes an activation flag, wherein the one or more switching execution conditions include:

[0028] Determine that the signal measurement value of the corresponding potential target cell is greater than a threshold level,

[0029] Wherein modifying the one or more switching execution conditions comprises setting the activation flag from an inactive state to an active state in response to:

[0030] An indication that the source cell is scheduled to enter a power saving mode;

[0031] An instruction to modify an activation flag passed from the source cell to the UE; or

[0032] A determination is made that the remaining time until the source cell is scheduled to enter the power saving mode is less than a threshold time.

[0033] Preferably, the one or more switching execution conditions include:

[0034] It is determined that the signal measurement value of the corresponding potential target cell is greater than the signal measurement values ​​of other potential target cells.

[0035] Preferably, each of the one or more switching execution conditions includes an activation flag, wherein the one or more switching execution conditions include:

[0036] Under the first handover execution condition, determining that a signal measurement value of a corresponding potential target cell is greater than a signal measurement value of a source cell by at least one offset;

[0037] Under the second handover execution condition, determining that the signal measurement value of the corresponding potential target cell is greater than a threshold level; and

[0038] Under the third handover execution condition, it is determined that the signal measurement value of the corresponding potential target cell is greater than the signal measurement values ​​of other potential target cells,

[0039] Modifying one or more switching execution conditions includes:

[0040] In response to determining that the remaining time until the source cell is scheduled to enter the power saving mode is less than a first threshold, setting an activation flag of the first handover execution condition from an inactive state to an active state;

[0041] In response to determining that the remaining time until the source cell is scheduled to enter the power saving mode is less than a second threshold, setting an activation flag of the second handover execution condition from an inactive state to an active state;

[0042] In response to determining that the remaining time until the source cell is scheduled to enter the power saving mode is less than a third threshold, an activation flag of the third handover execution condition is set from an inactive state to an active state.

[0043] Modifying one or more handover execution conditions may additionally include modifying an offset and / or a threshold based on a remaining time until the source cell is scheduled to enter the power saving mode.

[0044] Preferably, the signal measurements include one or more of the following:

[0045] signal strength indicator; and

[0046] Signal quality indicator.

[0047] Signal measurements may additionally or alternatively include other measurements including, but not limited to, timing data, signal latency, channel noise, error rates, and the like.

[0048] In one example, the power mode data may be broadcast to one or more active UEs simultaneously.

[0049] In another example, the power mode data may be sent to a group including one or more active UEs.

[0050] In another example, the power mode data may be communicated to each of the one or more UEs via a corresponding dedicated message.

[0051] The method by which the power mode data is communicated may depend on the number of active UEs. For example, if there are many active UEs connected, a broadcast message may be an efficient way to communicate the power mode data to each of these active UEs. Conversely, if there are relatively few active UEs (e.g., 5 or less), it may be more efficient to send a group message or a separate dedicated message to each of these UEs.

[0052] The method may further include delivering the conditional handover configuration data and / or the handover execution condition to each of the one or more active UEs.

[0053] The conditional handover configuration data and / or handover execution conditions may be delivered from a base station associated with a source cell to each of the one or more active UEs. There may be multiple base stations associated with each source cell, in which case each active UE may receive the conditional handover configuration data and / or handover execution conditions from the corresponding base station.

[0054] The handover execution condition may be modified by a base station associated with the serving cell and sent from the base station to the UE.

[0055] In one example, the conditional handover configuration data may be based on current cell configuration data of the source cell.

[0056] Alternatively, the conditional switching configuration data may be based on reference configuration data.

[0057] The conditional handover configuration data may be received from one or more potential target cells.

[0058] The method may also include receiving conditional handover configuration data from each of the one or more potential target cells.

[0059] The UE may receive conditional handover configuration data from each of the one or more potential target cells via a base station associated with the source cell.

[0060] In some examples, the potential target cell may receive power mode data from the source cell and modify the conditional handover configuration data based on the power mode data.

[0061] The method may further include:

[0062] passing power mode data from a source cell to a potential target cell;

[0063] modifying conditional switching configuration data based on the power mode data; and

[0064] The modified conditional handover configuration data is transferred from the potential target cell to the source cell.

[0065] The method may further comprise communicating the modified conditional handover configuration data from the source cell to the UE (optionally together with one or more associated handover execution conditions).

[0066] In case a potential target cell provides modified and unmodified conditional handover configuration data, there may be different handover execution conditions associated with each conditional handover configuration data.

[0067] Preferably, each of the one or more active UEs is configured to initiate a handover to a potential target cell based on the conditional handover configuration data if one of the corresponding handover execution conditions is met.

[0068] In other words, for each potential target cell, the UE determines the conditional handover configuration data associated with the potential target cell and one or more handover execution conditions associated with the conditional handover configuration data. The handover execution condition defines whether and when the UE should initiate a handover to the potential target cell. The conditional handover configuration data defines how the UE should initiate a handover to the potential target cell.

[0069] Preferably, the method further comprises:

[0070] Based on the conditional handover configuration data, it is determined that a handover execution condition is satisfied, and a handover is initiated to a corresponding target cell of the one or more potential target cells.

[0071] In another example, a method of managing handover between cells in a cellular telecommunications network includes:

[0072] delivering power mode data of the source cell to one or more user equipments UE served by the source cell;

[0073] determining one or more handover execution conditions for each of the one or more potential target cells; and

[0074] Based on the power mode data, one or more switching execution conditions are modified.

[0075] The method may also include determining conditional handover configuration data associated with one or more handover execution conditions (and associated with the corresponding potential target cell) for each of the one or more potential target cells. If one of the handover execution conditions is met, the UE may use the conditional handover configuration data to initiate a handover to the corresponding potential target cell.

[0076] In another example, a method of managing handover between cells in a cellular telecommunications network includes:

[0077] delivering power mode data of a source cell serving one or more user equipments UE to one or more potential target cells;

[0078] determining, for each of the one or more potential target cells, conditional handover configuration data and / or one or more associated handover execution conditions; and

[0079] Based on the power mode data, the conditional handover configuration data and / or one or more associated handover execution conditions are modified.

[0080] The present invention also provides a base station configured to perform one or more of the methods described above.

[0081] The present invention also provides a user equipment UE, which is configured to execute one or more of the methods described above.

[0082] The present invention also provides computer software comprising instructions which, when executed by a processor of a computing device, cause the computing device to carry out one or more of the methods described above.

[0083] Once the source cell enters power saving mode, the source cell may no longer serve one or more active UEs. Therefore, handover may be necessary for the source cell to enter power saving mode. The corresponding (one or more) base stations may still serve one or more active UEs via another cell or RAT. However, the existing cell will be powered off.

[0084] The serving cell may be provided by an evolved Node B (eNB), a next generation Node B (gNB), or a next generation evolved Node B (ng-eNB). In other words, the radio access technology may preferably be 4G or 5G (although these methods are suitable for any radio access technology). BRIEF DESCRIPTION OF THE DRAWINGS

[0085] The invention is described with reference to the following specific non-limiting examples.

[0086] Figure 1A A schematic coverage diagram of a standard cellular network is illustrated.

[0087] Figure 1B Pictured Figure 1A A schematic coverage diagram of FIG. 1 shows an example of an extended coverage area of ​​a cell.

[0088] Figure 2A An example cellular network is illustrated in which each cell is associated with a corresponding base station located at the midpoint of the cell.

[0089] Figure 2B An example cellular network is illustrated in which each cell is associated with three corresponding base stations, each of which is located at a cell boundary.

[0090] Figure 3AThe communication between the UE, the serving cell and the potential target cells is schematically illustrated.

[0091] Figure 3B A flow chart illustrating an example method is illustrated.

[0092] Figure 4A A graph of signal measurements versus time is illustrated to illustrate a simplified version of a first example switching execution condition.

[0093] Figure 4B A graph of signal measurement values ​​versus time is illustrated to explain a first example switching execution condition in another scenario.

[0094] Figure 4C A graph of signal measurements versus time is illustrated to explain how a first example switching execution condition may be modified according to a specific example.

[0095] Figure 4D A graph of signal measurements versus time is illustrated to explain another way in which the first example switch execution condition may be modified according to a specific example.

[0096] Figure 5A A graph of signal measurements versus time is illustrated to illustrate a simplified version of a second example switching execution condition.

[0097] Figure 5B A graph of signal measurement values ​​versus time is illustrated to explain a second example switching execution condition in another scenario.

[0098] Figure 5C A graph of signal measurements versus time is illustrated to explain how the second example switching execution condition may be modified according to a specific example.

[0099] Figure 5D A graph of signal measurements versus time is illustrated to explain another way in which the second example switch execution condition may be modified according to a specific example.

[0100] Figure 6 A graph of signal measurements versus time for three potential target cells is illustrated to illustrate a third example handover execution condition.

[0101] Figure 7 A timeline of three example switch execution conditions being configured and subsequently activated is illustrated.

[0102] Figure 8 A flow chart illustrating an example method is illustrated.

[0103] Fig. 9A An example user device is illustrated.

[0104] Fig. 9B An example user equipment base station is illustrated. DETAILED DESCRIPTION

[0105] The present application describes different power modes of a cell, including a full power mode (such as a "connected mode") and a power saving mode (such as a "network power saving mode"). The present application also describes a handover process that can be implemented before a cell is placed in a power saving mode in order to maintain connections (such as voice and data connections) via a telecommunications network for active UEs.

[0106] The power mode of a cell may change in response to changes in demand placed on the network. For example, during the night when network load is typically low, some cells may be placed in a power saving mode. In some cases, changes to the power mode may be pre-scheduled so that the cell is switched to a power saving mode at the same time each night for the same period of time.

[0107] In full power mode, such as "connected mode", a cell may operate normally. An active UE served by that cell may initiate a handover to another cell based on signal measurements in the normal manner. In full power mode, the handover conditions are generally not based on the power mode of the cell.

[0108] In low power mode, the cell operates with significantly reduced power consumption. The power consumption attributed to the cell may not be zero, because there may be some elements that are driven in low power mode (for example, because they are slow to power on and off, or are essential even when the cell is inactive). In low power modes such as NES (network energy saving) mode, the cell may not be able to establish a new connection with the UE or maintain an existing connection. Therefore, when the cell enters low power mode, active UEs connected via the serving cell may lose their connection. This will cause call drops and data session terminations.

[0109] Therefore, when a cell is scheduled to transition from full power mode to power saving mode, it is important to switch active UEs connected to the cell to the best possible alternative cell before the serving cell enters power saving mode. UEs in idle / inactive mode also need to be transferred to alternative cells. However, once the cell enters power saving mode, users of such UEs will not immediately observe service interruption, while users of active UEs will observe such service interruption.

[0110] If many active UEs experience service interruption in the same time period, this may cause an overload situation on other cells, as these UEs will try to access other cells at the same time (e.g., by sending RRC re-establishments due to coverage loss of the serving cell). Such situations can be avoided by ensuring proper handover of active UEs before the serving cell enters power saving mode.

[0111] Therefore, the present application provides an enhanced switching method, which facilitates the UE to switch out of a serving cell that is scheduled to enter a power saving mode.

[0112] Figure 1A Figure 2 shows a schematic coverage diagram of a standard cellular network. Figure 1A As can be seen in FIG, serving cell 10 is surrounded by neighboring cells 21 to 26. A UE connected via serving cell 10 monitors the signal provided by serving cell 10 and also monitors signals received from one or more of neighboring cells 21 to 26. If the signal from a neighboring cell (such as cell 22) becomes better than the signal from serving cell 10 (e.g., because the UE moves between coverage areas), the UE may initiate a handover to neighboring cell 22.

[0113] Although Figure 1A The coverage area of ​​each cell is illustrated as being shaped as a tessellated hexagon, but this is merely a simple illustration, often used to explain how multiple cells (each providing coverage over a small area) are combined to provide coverage over a larger area. In reality, the cell coverage areas are not hexagonal, but overlap each other. Therefore, cell signals are detectable outside the illustrated hexagonal coverage areas. Figure 1B An example of extended coverage areas of cells 22, 24 and 26 is illustrated, shown in this simplified example as circles 32, 34 and 36, respectively.

[0114] As from Figure 1B As can be seen, the entire coverage area of ​​serving cell 10 is covered by extended coverage circles 32, 34 and 36 from neighboring cells 22, 24 and 26. Thus, during times of low demand, serving cell 10 may be switched to a power saving mode and coverage may be provided by neighboring cells 22, 24 and 26 to the geographic area.

[0115] In addition, telecommunication networks may include cells of varying sizes (e.g., macro, micro, and femto cells). Some cells may be used to increase network capacity in high demand areas, rather than being essential to providing geographic coverage. At times of lower demand, such cells may be switched to a power saving mode without compromising overall coverage.

[0116] In view of the above, and considering that most of the power consumption of a telecommunications network may be attributed to base stations, placing a subset of cells in power saving mode during times of lower demand will result in improvements in power efficiency in the telecommunications network. In some cases, this can be achieved without compromising network coverage. In other cases, coverage may be slightly impaired, but this can be explained by the reduction in power consumption.

[0117] In order for a cell to enter power saving mode, it is preferred that no active UEs are connected via the cell for the reasons discussed above. Figure 1B , which is currently served by the serving cell 10. If the serving cell 10 were to enter power saving mode while the active UE is still connected, the active session (e.g., voice and / or data session) at the UE 90 would terminate. Therefore, before the serving cell 10 enters power saving mode, the UE 90 should switch to an alternative cell. In addition to the signal of the serving cell itself, the neighboring cell 22 may have the best signal (considering the extended coverage area 32 of the neighboring cell 22). However, as long as the serving cell 10 is still in connected mode, the signal of the serving cell may be better than the signal of the neighboring cell. Therefore, under normal circumstances, the UE will not initiate a handover to the neighboring cell 22. Therefore, when the serving cell 10 enters power saving mode, the UE will experience a drop in service. At this time, the UE will need to reconnect and may reestablish the connection via the neighboring cell 22. However, this drop in connection is undesirable.

[0118] In view of this, the present application proposes a method for guiding a UE served by a serving cell to switch to a neighboring cell even if the signal of the serving cell is better.

[0119] Figure 2A A simple example is illustrated, where each cell is associated with one corresponding base station located at the midpoint of the cell. The serving cell 10 is associated with the base station 40, and the neighboring cells 21 to 26 are associated with the base stations 41 to 46, respectively. When the serving cell 10 is placed in power saving mode, the base station 40 can be placed completely in power saving mode. Similarly, if the neighboring cells 21, 23 and 25 are placed in power saving mode, the base stations 41, 43 and 45 can be placed completely in power saving mode.

[0120] Figure 2B An alternative example is illustrated in which a base station is located at the corner of its associated cell. Each cell is associated with three base stations and cell coverage is provided by a combination of the three associated base stations. Figure 2B In the example illustrated in , serving cell 10 is associated with base stations 51, 52, and 53. Neighboring cell 21 is associated with base stations 51, 54, and 55; neighboring cell 22 is associated with base stations 51, 56, and 57; neighboring cell 23 is associated with base stations 52, 57, and 58; neighboring cell 24 is associated with base stations 52, 59, and 60; neighboring cell 25 is associated with base stations 53, 60, and 61; and neighboring cell 26 is associated with base stations 53, 54, and 62.

[0121] When the serving cell 10 is placed in power saving mode, it may not be feasible to completely place each of the associated base stations 51, 52 and 53 in power saving mode because these base stations are also associated with other cells that may not be placed in power saving mode. For example, if neighboring cells 22, 24 and 26 are to remain in full power mode, and the serving cell 10 and neighboring cells 21, 23 and 25 are to be placed in low power mode, the base station 51 can be partially placed in low power mode. The components of the base station 51 associated with the serving cell 10 (and the neighboring cell 21) can be placed in low power mode, while the components of the base station 51 associated with the neighboring cell 22 can remain in full power mode. Similarly, the components of the base stations 52 and 53 associated with the serving cell 10 (and the neighboring cells 23 and 25) can be placed in power saving mode, while the components associated with the neighboring cells 24 and 26 can remain in full power mode.

[0122] Figure 3A The communication between the UE 40, the serving cell 10 and the potential target cells 22, 24 and 26 is schematically illustrated. Figure 3B A flowchart illustrating an example method is illustrated in FIG.

[0123] At step 301, conditional handover configuration data is sent from potential target cells: cell 22, cell 24 and cell 26 to serving cell 10. These potential target cells may be cells that are geographically close to the serving cell (ie, they may be neighboring cells).

[0124] UE 40 is currently served by serving cell 10. At step 302, serving cell 10 provides conditional handover configuration data to UE 40 so that if certain conditions are met (e.g., the signal of the potential target cell becomes better than the signal of the serving cell), the UE can initiate a handover to the potential target cell. Serving cell 10 can also provide handover execution conditions to UE 40, which define the conditions under which a handover should be initiated. These conditions can include thresholds and offsets that define the conditions.

[0125] At step 303, a determination is made that the cell 10 is scheduled to enter a power saving mode within X minutes (or at time Y).

[0126] At step 304, serving cell 10 provides power mode data to UE 40 (e.g., via a broadcast message, a group message, or a dedicated message). The power mode data may include an indication that serving cell 10 will enter a power saving mode within X minutes (or at time Y). In some examples, the power mode data may include:

[0127] A flag (e.g., a bit of data) indicating that the serving cell (or an associated base station) is scheduled to enter a power saving mode;

[0128] The time (e.g. 19:00) at which the serving cell (or associated base station) is scheduled to enter power saving mode; and / or

[0129] A countdown (eg, 10 minutes) after which the serving cell (or associated base station) is scheduled to enter a power saving mode.

[0130] At step 305 (which may be performed simultaneously with step 304 ), the cell 10 may also send updated conditional handover configuration data of the cells 22 , 24 , and 26 to the UE 40 .

[0131] The skilled person is familiar with the conditional handover mechanism. Conditional handover is based on the premise that each of the potential target cells prepares resources for the UE that may be handed over to the cell and provides a conditional handover command to the UE 40. The handover command will only be executed if one or more of the handover execution conditions are met. The handover execution conditions are provided from the serving cell (specifically, from a base station associated with the serving cell, such as the source gNB). These conditions are related to handover events and their parameters.

[0132] At step 306 (which may be performed simultaneously with steps 304 and 305), the serving cell 10 provides the modified handover execution conditions to the UE 40. The modified handover execution conditions include adaptation thresholds and offsets for conditional handover to the potential target cells 22, 24, and 26. Due to the modified handover execution conditions, the UE is more likely to initiate a handover to the potential target cell before the serving cell enters the power saving mode.

[0133] The handover execution condition is based on the handover event and may be related to the reference signal received power / quality (RSRP / RSRQ) value difference between the serving cell 10 and the corresponding potential target cell 22, 24 or 26. The handover execution condition may take into account a threshold or an offset according to the configured handover event.

[0134] As an alternative to step 306, UE 40 may modify the handover execution condition in response to the power mode data received from the serving cell in step 304. UE 40 may modify the handover execution condition according to instructions stored on UE 40 or instructions received from serving cell 10.

[0135] At step 307, additional modified handover execution conditions may be determined. If a time until the cell 10 enters the power saving mode is provided in step 304, an additional handover execution condition taking this time into account may be defined as:

[0136] Triggering a handover when the potential target cell signal measurement is better than the serving cell measurement by an offset, where the offset decreases as the power saving mode time approaches; and / or

[0137] · Trigger handover when the potential target cell signal measurement value is greater than a threshold, where the threshold decreases as the power saving mode time approaches.

[0138] refer to FIG. 4A to FIG. 4D as well as FIG. 5A to FIG. 5C Specific examples illustrated in FIG. 2 explain some switching execution conditions in more detail.

[0139] At step 308, once the time X is about to expire, if there are still connected mode UEs, these UEs should initiate handover to the best available cell among the potential target cells.

[0140] The handover execution conditions (also referred to as "handover events") can be configured at the UE using a conditional handover (CHO) command. These events can be used to trigger a handover to a corresponding potential target cell. These events can also be configured at the UE (using a "measurement configuration" command).

[0141] In some examples, the potential target cell may receive power mode data from the source cell and modify the conditional handover configuration data based on the power mode data. The potential target cell may modify the conditional handover configuration data by providing reduced functionality to the UE based on the power mode data. Given that the source cell is scheduled to enter power saving mode, the handover execution conditions are more likely to be met. Therefore, the UE is more likely to accept the reduced functionality in order to obtain an effective handover (and avoid dropped calls and data sessions) before the source cell enters power saving mode.

[0142] The potential target cell may not be able to provide a handover to the UE using the unmodified conditional handover configuration data (e.g., because the load on the potential target cell is already high). However, based on the power mode data (i.e., an indication that the source cell will enter a power saving mode), the potential target cell may be able to provide a handover to the UE using modified conditional handover configuration data (which may provide reduced functionality, reduced bandwidth, or other modified characteristics).

[0143] This may be particularly useful if there are fewer available potential target cells, if the available potential target cells have poor signal measurements. By providing modified conditional handover configuration data from potential target cells, more handover options are provided to the UE. Therefore, it is more likely that the UE will successfully handover before the source cell enters power saving mode.

[0144] Figure 4A A graph of a signal measurement value (such as RSRP or RSRQ) versus time is illustrated to illustrate a simplified version of a first example handover execution condition, referred to in the art as an A3 handover event.

[0145] like Figure 4AAs can be seen in , the handover condition is met when the signal measurement value of the potential target cell is better than the signal measurement value of the serving cell by at least one offset.

[0146] The relevant equation for this event is:

[0147] Mn+Ofn+Ocn–Hys>Mp+Ofp+Ocp+Off

[0148] in:

[0149] Mn is the signal measurement value of the potential target cell;

[0150] Ofn is a specific offset relative to the frequency of the potential target cell;

[0151] Ocn is the specific offset associated with the potential target cell;

[0152] Mp is the signal measurement value of the primary channel of the serving cell;

[0153] Hys is the hysteresis parameter associated with the event;

[0154] Ofp is the specific offset of the frequency linked to the serving cell;

[0155] Ocp is a specific offset linked to the serving cell; and

[0156] Off is the specific offset associated with this event.

[0157] For simplicity, Figure 4A The example illustrated in combines different offset and hysteresis parameters (because only the trigger condition is considered, and the cancellation condition is not considered). Therefore, the equation becomes:

[0158] Potential target cell signal measurement value > serving cell signal measurement value + offset

[0159] As from Figure 4A As can be seen in , when the signal measurement value of the potential target cell improves relative to the signal measurement value of the serving cell and becomes better than the offset, the handover condition is met. For example, this may occur if the UE moves away from the serving cell and moves towards the potential target cell.

[0160] like Figure 4B As illustrated in , if the signal measurement value of the potential target cell does not become better than the signal measurement value of the serving cell by the offset, the handover condition will not be met and the handover will not be initiated. In the case where the serving cell is scheduled to enter power saving mode, it is preferred to encourage handover away from the serving cell. Therefore, the offset can be reduced. Figure 4C As illustrated in , reducing the offset may cause the switching condition to be more easily satisfied.

[0161] Advantageously, reducing the offset before entering the scheduled power saving mode may reduce the barrier to handover and thus result in more UEs handing over to the alternative cell.

[0162] In another example, as the time when the serving cell is scheduled to enter the power saving mode approaches, the offset may be gradually reduced over time. For example, for each time interval before the time when the serving cell enters the power saving mode, the offset may be reduced by 1 unit (such as 1 dB or 1 dBm). Figure 4D This example is shown in the figure.

[0163] Figure 5A A graph of a signal measurement value (such as RSRP or RSRQ) versus time is illustrated to illustrate a simplified version of a second example handover execution condition, referred to in the art as an A4 handover event.

[0164] The handover execution condition does not consider the signal measurement value of the serving cell, but only considers the signal measurement value of the potential target cell.

[0165] like Figure 5A As can be seen in , when the signal measurement value of the potential target cell is higher than (or better than) the threshold, the switching condition is met.

[0166] The relevant equation for this event is:

[0167] Mn+Ofn+Ocn-Hys>Thresh

[0168] in:

[0169] Mn is the signal measurement value of the potential target cell;

[0170] Ofn is a specific offset relative to the frequency of the potential target cell;

[0171] Ocn is the specific offset associated with the potential target cell;

[0172] Hys is the hysteresis parameter associated with the event; and

[0173] Thresh is the threshold value associated with the event.

[0174] For simplicity, Figure 5A The example illustrated in combines the offset and hysteresis parameters (because only the trigger condition is considered, and the cancellation condition is not considered). Therefore, the equation becomes:

[0175] Potential target cell signal measurement value > threshold

[0176] like Figure 5AAs can be seen, when the signal measurement value of the potential target cell improves, the handover condition is satisfied. This may occur, for example, if the UE moves towards the potential target cell.

[0177] As Figure 5B As illustrated, if the signal measurement value of the potential target cell does not become better than the threshold, the handover condition will not be satisfied and the handover will not be initiated. In the case where the serving cell is scheduled to enter the power saving mode, it is preferably encouraged to hand over from the serving cell. Therefore, the threshold may be reduced. As Figure 5C As illustrated, reducing the threshold can cause the handover condition to be more easily satisfied. Advantageously, reducing the threshold before entering the predetermined power saving mode can reduce the barrier to handover and thus cause more UEs to hand over to the alternative cell.

[0178] In another example, as the time when the serving cell is scheduled to enter the power saving mode approaches, the threshold can be gradually reduced over time. For example, for each time interval before the time when the serving cell enters the power saving mode, the threshold can be reduced by 1 dBm. Figure 5D This example is illustrated.

[0179] Advantageously, compared with the conditions illustrated in Figure 4A-4D even if the signal measurement value of the serving cell is very good, Figure 5A-5D the conditions illustrated in

[0180] In the case of the present invention, in both of the example handover execution conditions illustrated in Figure 4A-4D and Figure 5A-5D parameters (threshold / offset) within the existing handover event are modified based on power mode data (e.g., the time until the serving cell is scheduled to enter a power saving mode such as the NES mode). Since after entering the power saving mode, the serving cell will not provide normal services, the modified handover execution conditions make handover more likely compared to the unmodified handover execution conditions.

[0181] Other example handover execution conditions are also possible. For example, the B2 handover event in the prior art can be modified based on power mode data. The B2 event occurs when the signal measurement value of the serving cell is below the first threshold and the inter-RAT measurement value becomes greater than the second threshold.

[0182] MP + Hys < Thresh; and

[0183] Mn + Ofn + Ocn - Hys > Thresh2.

[0184] The threshold may be adjusted based on the power mode data. In one case, in response to an indication that the cell is scheduled to enter a power saving mode, the threshold may be adjusted to make a handover more likely. In another case, as the time when the serving cell is scheduled to enter a power saving mode approaches, the threshold may be gradually adjusted so that a handover becomes more likely over time.

[0185] In some cases, the base station may provide coverage via different radio access technologies and / or frequencies. It may be that only a subset of RATs and / or frequencies are scheduled to be placed in power saving mode. Therefore, UEs connected via these RATs and / or frequencies should switch before power saving mode. Since other RATs and / or frequencies can remain in full power mode, the UE can switch to these RATs and / or frequencies and remain connected via the same base station as before the switch, but via different RATs / frequencies.

[0186] Once the time X is about to expire (i.e., the serving cell is about to enter power saving mode urgently), a new handover execution condition needs to be defined to trigger the execution of the preconfigured handover command to one of the potential target cells. The potential target cell can be selected simply based on the best signal measurement value among the preconfigured potential target cells. This is Figure 6 It is shown in Figure 6 The figure shows a graph of signal measurements (such as RSRP or RSRQ) of each of the potential target cells versus time. At a certain point, if the UE is still connected to the serving cell and the power saving mode is urgently scheduled, a handover to the potential target cell with the best signal measurement is initiated.

[0187] In the present invention, the handover execution conditions are modified based on the power mode data. For example, the threshold, offset, etc. of a specific handover event can be modified according to the remaining time until the serving cell enters the power saving mode.

[0188] The serving cell may provide the UE with a value (eg, in dBm) to be added / subtracted from the threshold / offset. Alternatively, as the time for the serving cell to enter power saving mode approaches, the serving cell may provide the UE with instructions to adjust the threshold / offset.

[0189] As described above, the handover execution conditions may be configured immediately at the UE (e.g., using a "measurement configuration" command). Alternatively, handover events may be configured in advance but not immediately implemented (e.g., using a CHO command with a "deactivate" flag). These events may then be activated at an appropriate time (e.g., using a separate message) based on the remaining time until the serving cell is scheduled to enter power saving mode.

[0190] like Figure 7As illustrated in FIG, three switching execution conditions 701, 702, and 703 are configured at time A, but are configured with an activation flag that is initially set (e.g., set to false) so that the switching execution conditions are deactivated. In view of the power mode data, the switching execution conditions 701, 702, and 703 can be modified by setting the activation flag from an inactive state to an active state. As the time when the power saving mode is scheduled approaches, the active switching conditions may change. At time B, switching condition 701 is activated. At time C, switching condition 702 is activated. At time D, switching condition 703 is activated.

[0191] The activation flag may be changed in response to an indication that the source cell is scheduled to enter the power saving mode. The UE may modify the activation flag in response to determining that a remaining time until the source cell is scheduled to enter the power saving mode is less than a threshold time.

[0192] The activation flag may be changed in response to an instruction to modify the activation flag communicated from the source cell to the UE. The instruction to modify the activation flag may be signaled explicitly or implicitly (eg, based on a cell switch-off indication).

[0193] For example, switching execution condition 701 can be an A3 event (determining that the signal measurement value of the corresponding potential target cell is greater than the signal measurement value of the source cell by at least one offset), switching execution condition 702 can be an A4 event (determining that the signal measurement value of the corresponding potential target cell is greater than a threshold level), and switching execution condition 703 can be triggered by determining that the signal measurement value of the corresponding potential target cell is greater than the signal measurement values ​​of other potential target cells.

[0194] Conditions 701, 702 and 703 may relate to potential target cell 22. Similar conditions may be provided for other potential target cells 24 and 26.

[0195] Figure 8 A method of managing handover between cells in a cellular telecommunication network according to a specific example is illustrated. The method comprises the following steps:

[0196] 801: Deliver power mode data of a source cell to one or more active user equipments UE served by the source cell;

[0197] 802: Determine conditional handover configuration data and one or more associated handover execution conditions for each of one or more potential target cells;

[0198] 803: Modify one or more switching execution conditions based on the power mode data.

[0199] Fig. 9AA schematic diagram of a UE 900 according to a specific example is illustrated. The UE includes a processor 910 and a transceiver 920, the transceiver 920 being configured to receive power mode data, conditional handover configuration data, and one or more associated handover execution conditions. The UE is configured to modify one or more handover execution conditions based on the power mode data.

[0200] Fig. 9B A schematic diagram of a base station 950 according to a specific example is illustrated. The base station includes a processor 960 and a transceiver 970, and the transceiver 970 is configured to send power mode data, conditional handover configuration data, and one or more associated handover execution conditions (to one or more UEs). The base station is configured to modify one or more handover execution conditions based on the power mode data.

[0201] Although the base station is described as a single base station, the functionality of the base station may be distributed across a number of different physical base station sites.

[0202] As used herein (including in the claims), unless the context indicates otherwise, the singular form of the terms herein should be interpreted as including the plural form, and vice versa. For example, unless the context indicates otherwise, a singular reference herein (including in the claims), such as "a" or "an" (such as an analog-to-digital converter) means "one or more" (e.g., one or more analog-to-digital converters). Throughout the description and claims of the present disclosure, the words "include", "comprising", "having" and "containing" and variations of these words, such as "including" and "comprising" or similar words, mean "including but not limited to", and are not intended to exclude (and do not exclude) other components.

[0203] Although embodiments according to the present disclosure have been described with reference to specific types of devices and applications (particularly base stations and UEs), and the embodiments have particular advantages in this context, as discussed herein, methods according to the present disclosure may be applied to other types of networks. The specific structural details of the platforms and servers, while potentially advantageous (particularly in view of known 3GPP constraints and capabilities), may vary significantly to achieve devices and methods with similar or identical operations. Unless otherwise stated, each feature disclosed in this specification may be replaced by an alternative feature for the same, equivalent or similar purpose. Therefore, unless otherwise stated, each feature disclosed is merely an example of a general series of equivalent or similar features.

[0204] Unless otherwise claimed, the use of any and all examples or exemplary language ("such as", "such as", "for example" and similar language) provided herein is intended only to better illustrate the present invention and does not indicate a limitation on the scope of the present invention. No language in the specification should be construed as indicating any non-claimed element is essential to the practice of the present invention.

[0205] Unless otherwise specified or the context requires otherwise, any steps described in this specification may be performed in any order or simultaneously.

[0206] All aspects and / or features disclosed in this specification may be combined in any combination, except at least some mutually exclusive combinations of such features and / or steps. As described herein, there may be a specific combination of further useful aspects, such as determining a set of compensation parameters and applying the set of compensation parameters to the aspects of measurement. In particular, preferred features of the present invention are applicable to all aspects of the present invention and may be used in any combination. Equally, the features described in the non-essential combination may be used alone (not combined for use).

Claims

1. A method of managing handover between cells in a cellular telecommunication network, the method comprising: delivering power mode data of the source cell to one or more active user equipments UE served by the source cell; determining, for each of the one or more potential target cells, conditional handover configuration data and one or more associated handover execution conditions; Based on the power mode data, one or more switching execution conditions are modified.

2. The method of claim 1 , wherein the power mode data comprises one or more of the following: An indication that the source cell is scheduled to enter a power saving mode; The time at which the source cell is scheduled to enter the power saving mode; The remaining time until the source cell is scheduled to enter the power saving mode; one or more threshold modification instructions based on a remaining time until the source cell is scheduled to enter a power saving mode; as well as One or more offset modification instructions based on a remaining time until the source cell is scheduled to enter a power save mode.

3. The method according to claim 1 or claim 2, wherein the one or more switching execution conditions include: determining that a signal measurement value of a corresponding potential target cell is greater than a signal measurement value of the source cell by at least one offset, Wherein modifying the one or more handover execution conditions comprises modifying the offset based on a remaining time until the source cell is scheduled to enter a power saving mode.

4. The method according to any preceding claim, wherein the one or more switching execution conditions include: determining that the signal measurement value of the corresponding potential target cell is greater than a threshold level, Wherein modifying the one or more handover execution conditions comprises modifying the threshold level based on a remaining time until the source cell is scheduled to enter a power saving mode.

5. The method according to claim 1 or claim 2, wherein each of the one or more handover execution conditions comprises an activation flag, wherein the one or more handover execution conditions comprise: determining that the signal measurement value of the corresponding potential target cell is greater than a threshold level, Wherein modifying the one or more switching execution conditions comprises setting the activation flag from an inactive state to an active state in response to: An indication that the source cell is scheduled to enter a power saving mode; an instruction to modify the activation flag delivered from the source cell to the UE; or A determination is made that the remaining time until the source cell is scheduled to enter the power saving mode is less than a threshold time.

6. The method according to any preceding claim, wherein the one or more handover execution conditions comprise: It is determined that the signal measurement value of the corresponding potential target cell is greater than the signal measurement values ​​of other potential target cells.

7. The method according to any one of claims 3 to 6, wherein the signal measurements include one or more of the following: signal strength indicator; and Signal quality indicator.

8. A method according to any preceding claim, wherein: The power mode data is broadcast simultaneously to one or more active UEs; sending the power mode data to a group including the one or more active UEs; or The power mode data is communicated to each of the one or more UEs via a corresponding dedicated message.

9. A method according to any preceding claim, wherein the conditional switching configuration data is: Based on current cell configuration data of the source cell; or Based on reference configuration data; 10. A method according to any preceding claim, wherein the conditional handover configuration data is received from the one or more potential target cells.

11. The method of claim 9 or claim 10, wherein each of the one or more active UEs is configured to initiate a handover to a potential target cell based on the conditional handover configuration data if one of the corresponding handover execution conditions is met.

12. The method according to any one of claims 9 to 11, further comprising: Based on the conditional handover configuration data, it is determined that a handover execution condition is satisfied, and a handover is initiated to a corresponding target cell among the one or more potential target cells.

13. A base station, configured to perform the method according to any one of claims 1 to 11.

14. A user equipment UE, configured to execute the method according to any one of claims 1 to 12.

15. Computer software comprising instructions which, when executed by a processor of a computing device, cause the computing device to carry out the method of any one of claims 1 to 12.

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