Energy saving method and related device

Abstract

This application discloses an energy-saving method and related apparatus applicable to an energy-saving scenario of a base station. The method includes a step in which a network device determines a target symbol within a multimedia broadcast multicast service single frequency network (MBSFN) subframe of a first cell. The target symbol is a cell-specific reference signal (CRS) symbol, a demodulation reference signal (DMRS) symbol, a physical downlink control channel (PDCCH) symbol dedicated to a user equipment (UE), and a physical downlink shared channel (PDSCH) symbol dedicated to the UE. When the load of the first cell is lower than a preset threshold, the network device reduces the transmission power of the target symbol. When the load of the first cell is higher than the preset threshold, the network device increases the transmission power of the target symbol. In this application, the overall transmission power of the cell is adjusted by simultaneously adjusting the transmission powers of the four types of symbols, and the UE does not need to be notified via an air interface message. Therefore, the overall transmission power of the cell can be adjusted quickly, and the service stability of the base station can be guaranteed while realizing energy saving.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 202210912704.0, titled "Energy Saving Method and Related Device", filed with the China National Intellectual Property Administration on July 30, 2022, the entire content of which is incorporated herein by reference.

[0002] This application relates to the field of communications, and particularly to an energy saving method and related device.

Background Art

[0003] With the development of communication technologies, Long Term Evolution (LTE) has become the mainstream wireless communication standard, carrying a large amount of data and a large amount of voice services. The evolved NodeB (eNB) occupies a large proportion of the base stations of all operators and is an important revenue source for operators. However, the large-scale energy consumption of eNBs also accounts for a high proportion of the energy consumption of operators. Therefore, operators are eager to further reduce the energy consumption of eNBs.

[0004] A method for reducing the energy consumption of an eNB is to reduce the transmission power of the cell when the cell of the eNB has a low load, thereby reducing the energy consumption of the eNB. In the case of an eNB cell, the Cell-specific Reference Signal (CRS) occupies a large amount of air interface resources, and during the low load period, the CRS consumes a large amount of energy. Therefore, in order to reduce the transmission power of the cell, the transmission power of the CRS needs to be reduced first.

[0005] Currently, a common method for reducing CRS transmit power is to permanently reduce the CRS power configuration of the cell. However, reducing the transmit power of the CRS symbol changes the power bias difference, which does not match the power bias difference previously notified to the UE. The UE is unable to cope with this situation. Therefore, terminal devices need to be notified in advance of changes in the power bias difference via air interface messages. However, the response time of air interface messages is usually long, at the level of hundreds of milliseconds or even several seconds. As a result, the CRS transmit power cannot be adjusted quickly. If the cell load increases rapidly, the CRS transmit power cannot be restored in a timely manner. In other words, the response time cannot adapt to rapid traffic changes. [Overview of the project] [Means for solving the problem]

[0006] This application provides an energy-saving method and related apparatus for rapidly adjusting the transmission power of a cell.

[0007] The network device determines the target symbols within the Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN) subframe of the first cell. The target symbols are the cell-specific reference signal CRS symbol, the demodulation and modulation reference signal DMRS symbol, the physical downlink control channel PDCCH symbol dedicated to the terminal device UE, and the physical downlink shared channel PDSCH symbol dedicated to the UE. If the load of the first cell is below a preset threshold, the network device reduces the transmit power of the target symbols. If the load of the first cell is above the preset threshold, the network device increases the transmit power of the target symbols.

[0008] The energy saving method provided in the first embodiment is applicable to frequency division duplex (FDD) mode and time division duplex (TDD) mode. In FDD mode, subframes 0, 4, 5, and 9 are always non-MBSFN subframes. In other words, MBSFN subframes may be subframes 1, 2, 3, 6, 7, and 8. In TDD mode, if the uplink-downlink subframe configuration is 1, MBSFN subframes may occupy subframes 4 and 9. If the uplink-downlink subframe configuration is 2, MBSFN subframes may occupy subframes 3, 4, 8, and 9. If the uplink-downlink subframe configuration is 5, MBSFN subframes may occupy subframes 3, 4, 7, 8, and 9. In addition, subframes 2 and 7 may be uplink subframes. Therefore, since subframes 0, 1, 5, and 6 are always normal subframes, MBSFN subframes can be downlink subframes within subframes 3, 4, 7, 8, and 9.

[0009] The network device can monitor the instantaneous load status of the first cell in real time (e.g., at the millisecond level), and the status includes, but is not limited to, uplink service load, downlink service load, data buffer size, and number of users. When the load of the first cell is below a preset threshold, it indicates that the first cell is in a low-traffic state. In this case, the first cell does not normally require transmit power, and the network device reduces the transmit power of the first cell by reducing the transmit power of the target symbol. If the network device detects, by monitoring, that the load of the first cell is above a preset threshold, this indicates that the service requirements of the first cell have increased, and the network device increases the transmit power of the target symbol, restoring the transmit power of the target symbol to its state before the power reduction. Naturally, the network device may alternatively further increase the transmit power of the target symbol based on the actual load status of the first cell. For example, if the load on the first cell is much higher than a preset threshold, the network device may increase the power of the target symbol instead of simply restoring the target symbol's transmit power to the level before the power reduction.

[0010] Specifically, the method for adjusting (including reducing and increasing) the transmit power of target symbols by a network device involves simultaneously adjusting the transmit power of four types of symbols: cell-specific reference signal CRS symbols, demodulation modulation reference signal (DMRS) symbols, physical downlink control channel (PDCCH) symbols dedicated to user equipment (UE), and physical downlink shared channel (PDSCH) symbols dedicated to UE.

[0011] In a first aspect of this application, the network device adjusts the cell's transmit power by simultaneously adjusting the transmit power of four types of symbols: CRS symbols, DMRS symbols, UE-specific PDCCH symbols, and UE-specific PDSCH symbols. When the power of these symbols is adjusted together, the UE can understand the power adjustment as usual and process the service as usual. Thus, the overall transmit power of the cell can be adjusted quickly, provided that the MBSFN subframe does not need to be specially configured in the first cell and the UE does not need to be notified that the transmit power of the first cell has been reduced via air interface messages (e.g., system messages or Radio Resource Control (RRC) signaling). Thus, according to the energy saving method provided in a first aspect of this application, changes in cell service fluctuations can be quickly tracked, and a stable user experience can be ensured while achieving energy savings.

[0012] In a possible implementation of the first embodiment, the MBSFN subframe does not carry System Information Block (SIB) messages, paging messages, message 2 (MSG2), or message 4 (MSG4) of the first cell. In this possible implementation, it is limited that the MBSFN subframe in which the target symbol is located does not carry cell common messages. When the MBSFN subframe is used to carry cell common messages, the transmit power of all symbols within the subframe is not reduced; that is, none of the symbols are target symbols. Therefore, the normal implementation of basic functions such as receiving paging messages and initiating access requests by the UE remains unaffected.

[0013] In a possible implementation of the first embodiment, the target symbols do not include symbols in the Physical Control Format Indicator Channel (PCFICH) and the Physical Hybrid ARQ Indicator Channel (PHICH), or the cell's common PDCCH symbols and Channel State Information Reference Signal (CSIRS) symbols. In this possible implementation, the specific content of the target symbols is limited, and as a result, the implementation of the cell's basic functionality may not be affected.

[0014] In a possible implementation of the first embodiment, the PDSCH symbol does not include the Voice over Long-Term Evolution (VoLTE) symbol, the Signal Radio Bear 1 (SRB1) symbol, or the Signal Radio Bear 2 (SRB2) symbol. In this possible implementation, the specific content of the target symbol is limited, and as a result, the implementation of the cell's basic functionality may not be affected.

[0015] In a possible implementation of the first embodiment, the CRS symbol is located outside the position of symbol 0 in the MBSFN subframe.

[0016] In some cases, a UE in a neighboring cell of the first cell may use a CRS symbol located at the position of symbol 0 in the MBSFN subframe to measure the coverage strength of the first cell, for example, to measure the Reference signal received power (RSRP) or Reference signal received quality (RSRQ). In this possible implementation, the CRS symbol included in the target symbol is limited to being located outside the position of symbol 0 in the MBSFN subframe. Therefore, reducing the transmit power of the target symbol does not affect the result of the coverage measurement of the first cell by the UE in the neighboring cell, nor does it affect mobility functions such as reselection of the UE in the neighboring cell and handover to the current cell.

[0017] In a possible implementation of the first aspect, the method further includes the step of a network device sending a target message to a second cell. The target message indicates that an evolutionary multimedia broadcast multicast service (eMBMS) cell resides in a neighboring cell with which the second cell has a handover relationship, and that, for the second cell, its neighboring cells also include the first cell.

[0018] The network device notifies the neighboring cell (i.e., the second cell) of the first cell via a pseudo-message (i.e., a target message) that an Evolved Multimedia Broadcast Multicast Service (eMBMS) neighboring cell is present in the vicinity. After the second cell learns of the presence of the eMBMS neighboring cell, the second cell notifies the UE within the second cell via a system message, so that when measuring the neighboring cell's signal, the UE in the second cell measures only the CRS symbols within the neighboring cell's non-MBSFN subframes. The network device does not reduce the transmit power of symbols within the non-MBSFN subframes of the first cell. Therefore, the signal intensity of the first cell, as obtained through measurements by the UE in the second cell, does not change before and after the network device adjusts the transmit power of the first cell, thereby ensuring that mobility functions such as re-selection and handover of the UE in the second cell to the first cell can remain normal.

[0019] In a possible implementation of the first embodiment, prior to the step of the network device reducing the transmit power of the target symbol, the method further includes the step of the network device determining that the intensity of the signal received by the UE in the first cell is higher than the target threshold of the first cell. The target threshold is higher than the minimum access level threshold of the first cell.

[0020] When a network device reduces the transmit power of a target symbol, it can cause a decrease in the coverage signal strength of the first cell, potentially triggering a pre-emptive inter-frequency / inter-system cell handover to UEs originally located near the edge area of ​​the first cell, which can lead to KPI risks such as traffic loss or call drops. To avoid this as much as possible, the network device sets a target threshold. The target threshold is higher than the minimum access level threshold of the first cell. The network device reduces the transmit power of the target symbol only if the signal strength of all UEs connected to the first cell is higher than the target threshold. If the signal strength of the UEs is lower than the target threshold, the network device stops reducing the transmit power of the target symbol, and as a result, the coverage signal strength of the first cell is no longer reduced. If the signal strength of the UEs is again higher than the target threshold, the network device continues to reduce the transmit power to ensure that the decrease in coverage signal strength does not cause the UEs to pre-emptively trigger an inter-frequency or inter-system handover, thereby avoiding KPI risks such as traffic loss or call drops.

[0021] In a possible implementation of the first embodiment, after the step of the network device reducing the transmit power of the target symbol, the method further includes the step of the network device calculating a compensation amount for the reference signal received power RSRP or a compensation amount for the reference signal received quality RSRQ of the first cell. Based on the compensation amount for RSRP or RSRQ, the network device compensates the RSRP or RSRQ reported by the UE in the first cell.

[0022] When a network device reduces the transmit power of a target symbol, it causes a decrease in the coverage signal strength of the first cell, prompting the UE to pre-emptively trigger an in-frequency cell handover. To avoid as much as possible KPI risks such as traffic loss or call drops resulting from the UE being pre-emptively handed over to another in-frequency cell, the network device calculates the amount of RSRP compensation or RSRQ compensation for the first cell based on the reduced transmit power and performs compensatory remediation against the RSRP or RSRQ value reported by the UE based on the compensation amount. The RSRP or RSRQ value is carried in the in-frequency handover request event. If the signal strength of the UE in the first cell after compensatory remediation does not actually meet the in-frequency handover threshold requirements, the network device will not perform the UE handover. The network device will only actually perform the UE handover if the signal strength of the UE in the first cell after compensatory remediation is indeed low enough to meet the in-frequency handover threshold requirements. In this possible implementation, the network device can perform compensatory remediation on the signal strength of the first cell to avoid, as much as possible, situations where UEs within the first cell are pre-handed over to another cell within a different frequency, thereby avoiding KPI risks such as traffic loss or call drops.

[0023] In a possible implementation of the first embodiment, the network device reduces the minimum access level threshold of the first cell based on the RSRP compensation amount or the RSRQ compensation amount.

[0024] In a possible implementation of the first embodiment, the method further includes the step of a network device reducing the minimum access level threshold of a first cell based on an RSRP compensation amount or an RSRQ compensation amount.

[0025] A minimum access level threshold is set for each cell. If the RSRP or RSRQ of the first cell, which is obtained by an idle UE through measurement, is less than the access level threshold, the idle UE cannot measure the network signal. Considering this, the network device obtains a compensation amount for the RSRP or RSRQ of the first cell, and reduces the minimum access level threshold of the first cell based on the compensation amount for the RSRP or RSRQ, so as to ensure that the idle UE is not disconnected from the network when the transmission power of the first cell is reduced. Thereby, traffic and user losses are prevented.

[0026] The second aspect of this application provides a communication device including a determination module, a reduction module, and an increase module. The determination module is configured to determine a target symbol within a multimedia broadcast multicast service single frequency network (MBSFN) subframe of the first cell. The target symbols are cell-specific reference signal (CRS) symbols, demodulation reference signal (DMRS) symbols, physical downlink control channel (PDCCH) symbols dedicated to the user equipment (UE), and physical downlink shared channel (PDSCH) symbols dedicated to the UE. The reduction module is configured to reduce the transmission power of the target symbol when the load of the first cell is lower than a preset threshold. The increase module is configured to increase the transmission power of the target symbol when the load of the first cell is higher than a preset threshold.

[0027] In a possible implementation form of the second aspect, the MBSFN subframe does not carry the system information block (SIB) message, paging message, message 2 (MSG2), or message 4 (MSG4) of the first cell.

[0028] In a possible implementation of the second aspect, the target symbol does not include symbols in the physical control format indicator channel PCFICH and the physical hybrid automatic repeat indicator channel PHICH, or the common PDCCH symbols and the channel state reference signal CSIRS symbols of the first cell.

[0029] In a possible implementation of the second aspect, the PDSCH symbol does not include a voice over long term evolution VoLTE symbol, a signaling radio bearer 1 SRB1 symbol, or a signaling radio bearer 2 SRB2 symbol.

[0030] In a possible implementation of the second aspect, the CRS symbol is located outside the position of symbol 0 in the MBSFN subframe.

[0031] In a possible implementation of the second aspect, the communication device further includes a transmission module configured to transmit a target message to the second cell. The target message indicates that an evolved multimedia broadcast multicast service eMBMS cell exists in a neighboring cell having a handover relationship with the second cell, and that the neighboring cell includes the first cell.

[0032] In a possible implementation of the second aspect, the determination module is further configured to determine that the intensity of the signal received by the UE in the first cell is higher than the target threshold of the first cell. The target threshold is higher than the minimum access level threshold of the first cell.

[0033] In a possible implementation of the second aspect, the communication device is configured to calculate a compensation amount for the reference signal received power RSRP or the reference signal received quality RSRQ of the first cell, and to compensate the RSRP or RSRQ reported by the UE in the first cell based on the compensation amount for the RSRP or the compensation amount for the RSRQ, and further includes a calculation module.

[0034] In a possible implementation of the second embodiment, the reduction module is further configured to reduce the minimum access level threshold of the first cell based on the RSRP compensation amount or the RSRQ compensation amount.

[0035] A communication device provided in a second aspect of this application is configured to perform a method by means of either the first aspect or a possible implementation of either the first aspect.

[0036] A third aspect of this application further provides a communication device including a processor and memory. The memory is configured to store instructions. The processor is configured to retrieve instructions stored in the memory and to execute a method according to the first aspect or by a possible implementation of either aspect.

[0037] A fourth aspect of this application provides a computer-readable storage medium. The computer-readable storage medium includes instructions. When the instructions are invoked by a computer, the computer executes a method according to the first aspect, or a method according to a possible implementation of either aspect.

[0038] A fifth aspect of this application provides a computer program product including instructions. When the computer program product is started on a computer, the computer is made capable of executing the first aspect, or a method according to a possible implementation of either the first aspect.

[0039] A sixth aspect of this application provides a chip system, the chip system comprising at least one processor and a communication interface, the communication interface and the at least one processor interconnected via a line, the at least one processor configured to invoke a computer program or instructions to execute a communication method in the manner of the first aspect or by a possible implementation of either aspect. [Brief explanation of the drawing]

[0040] [Figure 1]This is a diagram showing the architecture of a communication system to which one embodiment of this application is applied. [Figure 2] This is a diagram illustrating one embodiment of an energy saving method according to one embodiment of this application. [Figure 3] This figure shows another embodiment of the energy saving method according to one embodiment of this application. [Figure 4] This is a diagram showing the structure of a communication device according to one embodiment of this application. [Figure 5] This is a diagram showing another structure of a communication device according to an embodiment of this application. [Figure 6] This is a diagram showing another structure of a communication device according to an embodiment of this application. [Modes for carrying out the invention]

[0041] Embodiments of this application provide an energy-saving method and related apparatus for rapidly adjusting the transmission power of a cell. Embodiments of this application further provide a corresponding computer-readable storage medium, a computer program product, and the like. A detailed description is provided below.

[0042] The embodiments of this application will be described below with reference to the attached drawings. Clearly, the embodiments described are only a selection of the embodiments of this application, and not all of them. Those skilled in the art will see that, with advances in the technology and the development of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to solving similar technical problems.

[0043] In the specification, claims, and accompanying drawings of this application, terms such as “first” and “second” are intended to distinguish similar subjects but do not necessarily indicate a particular order or sequence. Data referred to in this way are interchangeable in appropriate circumstances, and it should be understood that the embodiments described herein may be implemented in any order other than that illustrated or described herein. In addition, the terms “includes,” “has,” and any other variations thereof are intended to include non-exclusive inclusions. For example, a process, method, system, product, or device including an enumeration of steps or units is not necessarily limited to such explicitly enumerated steps or units, and may include other steps or units that are not explicitly enumerated or specific to such process, method, product, or device.

[0044] Figure 1 is a diagram of the architecture of a communication system according to one embodiment of this application.

[0045] The communication system includes a network device 101 and terminal devices 102, 103, and 104. Network device 101 may manage one or more cells, such as cells 105 and 106 shown in Figure 1. Different cells have different coverage signal strength and frequency domain resources. Network device 101 communicates with terminal devices 102 and 103 via the radio transmission resources of cell 105 and with terminal device 104 via the radio transmission resources of cell 106. When a handover is triggered, terminal device 102 may be handed over to cell 106 for connection, and terminal device 104 may be substituted for cell 105 for connection. It should be understood that Figure 1 is merely an example. In actual applications, the number of network devices and terminal devices are not limited thereto. Network device 101 may substituted for more cells, or it may manage only a single cell. This is not specifically limited herein.

[0046] Terminal devices 102, 103, and 104 may be devices having wireless transmission and reception capabilities, or they may be chips that can be placed in any device. Terminal devices may be deployed on land, including indoor devices, outdoor devices, handheld devices, and / or in-vehicle devices, on water (e.g., on a ship), or in the air (e.g., on an airplane, balloon, or satellite). Terminal devices may also be called user equipment (UE) and may include handheld devices, in-vehicle devices, wearable devices, or computing devices having wireless communication capabilities. For example, terminal devices may be mobile phones, tablet computers (Pads), or computers with wireless transceiver capabilities, or virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, wireless terminals for industrial control, wireless terminals for autonomous driving, wireless terminals for telemedicine, wireless terminals for smart grids, wireless terminals for smart cities, wireless terminals for smart homes, and / or others.

[0047] The network device 101 may be a device deployed in a radio access network that can conduct wireless communication with terminal devices, for example, an advanced base station eNB of an LTE system, a next-generation base station (next-generation nodeB, gNB) of a new radio (NR) system, or a base transceiver station (BTS) of a global system for mobile communication (GSM) system or a code division multiple access (CDMA) system.

[0048] Currently, the energy consumption caused by network device 101 accounts for a large proportion of the overall communication system. To reduce energy consumption, the transmit power of network device 101 needs to be reduced. Specifically, the transmit power of cell 105 or cell 106 may be reduced. However, currently, when reducing the transmit power of a cell, the response time is long and it is not possible to adapt to rapid changes in communication services (generally at the level of 10 milliseconds). In consideration of this, one embodiment of the present application provides an energy-saving method for rapidly adjusting the transmit power of a cell.

[0049] It should be noted that the energy saving methods provided in the embodiments of this application are applicable to a variety of communication systems, such as long-term evolution (LTE) systems, LTE frequency division duplex systems, LTE time division duplex systems, new radio (NR) systems, future communication systems (e.g., 6th generation (6G) communication systems), or systems integrating multiple communication systems. For the sake of clarity, LTE FDD systems and LTE TDD systems are used as illustrative examples in the embodiments of this application, but are not specifically limited herein.

[0050] Figure 2 is a diagram of one embodiment of an energy saving method according to one embodiment of the present application. As shown in Figure 2, the energy saving method of this embodiment includes steps 201 to 203.

[0051] 201: The network device determines the target symbol within the MBSFN subframe of the first cell.

[0052] The network device first determines the target symbol. The target symbol is located within the MBSFN subframe and includes the CRS symbol, DMRS symbol, UE-specific PDCCH symbol, and UE-specific PDSCH symbol.

[0053] The energy saving method provided in this embodiment is applicable to LTE FDD mode and LTE TDD mode. In FDD mode, subframes 0, 4, 5, and 9 are always non-MBSFN subframes, so MBSFN subframes can be subframes 1, 2, 3, 6, 7, and 8. In TDD mode, if the uplink-downlink subframe configuration is 1, MBSFN subframes may occupy subframes 4 and 9. If the uplink-downlink subframe configuration is 2, MBSFN subframes may occupy subframes 3, 4, 8, and 9. If the uplink-downlink subframe configuration is 5, MBSFN subframes may occupy subframes 3, 4, 7, 8, and 9. In addition, subframes 2 and 7 can be uplink subframes. Therefore, since subframes 0, 1, 5, and 6 are always normal subframes, MBSFN subframes can be downlink subframes within subframes 3, 4, 7, 8, and 9.

[0054] Optionally, to prevent the normal operation of the cell's basic functions from being affected during a reduction in the transmit power of the target symbol, the MBSFN subframe in which the target symbol is located cannot carry SIB messages or paging messages. In addition, the MBSFN subframe cannot carry message 2 (MSG2) or message 4 (MSG4) used for UE access. If the MBSFN subframe is used to carry the cell's common messages, the transmit power of all symbols within the subframe is not reduced; that is, none of the symbols are target symbols.

[0055] The PDSCH symbol selected as the target symbol at will not include the VoLTE symbol, SRB1 symbol, or SRB2 symbol.

[0056] In some possible solutions, the CRS symbol at position 0 within the MBSFN subframe is used by the UE in a neighboring cell to measure the coverage signal strength of the first cell, for example, to measure the RSRP or RSRQ of the first cell. Therefore, the target symbol may alternatively be a CRS symbol within the MBSFN subframe other than the symbol at position 0, rather than all CRS symbols within the MBSFN subframe.

[0057] Optionally, the target symbol does not contain symbols within PCFICH or PHICH. In addition, the target symbol does not contain the cell's common PDCCH or CSIRS symbols.

[0058] It should be noted that the energy saving method provided in this embodiment is applicable to the processing of CRS symbols for all ports (Ports) within the first cell.

[0059] 202: If the load on the first cell is below a preset threshold, the network device reduces the transmit power of the target symbol.

[0060] Network devices can monitor the instantaneous load status of the first cell in real time, which includes, but is not limited to, uplink service load, downlink service load, data buffer size, and the number of users. When the load of the first cell is lower than a preset threshold, it indicates that the first cell is in a low-traffic state. In this case, the first cell is in a normal service state and does not require transmit power, and the network device reduces the transmit power of the first cell by reducing the transmit power of the target symbol.

[0061] Specifically, the method for adjusting (including reducing and increasing) the transmit power of target symbols by a network device involves simultaneously adjusting the transmit power of four types of symbols: CRS symbols, DMRS symbols, UE-specific PDCCH symbols, and UE-specific PDSCH symbols.

[0062] In this embodiment, it should be noted that the network device adjusts the cell's transmit power by simultaneously adjusting the transmit power of four types of symbols: CRS symbols, DMRS symbols, UE-specific PDCCH symbols, and UE-specific PDSCH symbols. When the power of these symbols is adjusted together, the UE can understand the power adjustment as usual, and the UE can process services as usual. Therefore, MBSFN subframes do not need to be specially configured in the first cell, and the UE does not need to be notified via air interface messages that the transmit power of the first cell has been reduced. Thus, in this embodiment, when the network device monitors the instantaneous load status of the first cell, the status determination period can be several milliseconds to tens of milliseconds. Power reduction methods currently in common use require modification of the cell's parameter configuration, resulting in long response times (at the level of seconds (s) or more), and the damage to coverage and user experience is far more severe compared to that of this embodiment.

[0063] 203: If the load on the first cell exceeds a preset threshold, the network device increases the transmit power of the target symbol.

[0064] If the network device detects, through monitoring, that the load on the first cell is higher than a preset threshold, this indicates that the service requirements of the first cell have returned to normal, and the network device increases the transmit power of the target symbol, restoring the transmit power of the target symbol to its pre-power reduction state. Naturally, the network device may alternatively adjust the transmit power of the target symbol based on the actual load conditions of the first cell. For example, if the load on the first cell is much higher than the preset threshold, the network device may increase the power of the target symbol rather than simply restoring the transmit power of the target symbol to its pre-power reduction level.

[0065] In this embodiment, the network device adjusts the cell's transmit power by simultaneously adjusting the transmit power of four types of symbols: CRS symbols, DMRS symbols, UE-specific PDCCH symbols, and UE-specific PDSCH symbols. When the power of these symbols is adjusted together, the UE can understand the power adjustment as usual and process services as usual. Therefore, the overall transmit power of the cell can be adjusted quickly, provided that the MBSFN subframe does not need to be specially configured in the first cell and the UE does not need to be notified that the transmit power of the first cell has been reduced via air interface messages (e.g., system messages or Radio Resource Control (RRC) signaling). Thus, according to the energy saving method provided in the first aspect of this application, changes in cell service fluctuations can be quickly tracked, and a stable user experience can be ensured while achieving energy savings. In addition, in this embodiment, because the specific content of the target symbols is limited, the normal implementation of basic functions such as receiving paging messages and initiating access requests by the UE is not affected.

[0066] Figure 3 shows another embodiment of the energy saving method according to one embodiment of the present application. In this embodiment, if the transmit power of the first cell is reduced, it can be further ensured to the extent possible that the first cell does not suffer traffic and user losses caused by the power reduction. The following provides a detailed description with reference to Figure 3. As shown in Figure 3, the energy saving method of this embodiment includes steps 301 to 308.

[0067] 301: The network device determines the target symbol within the MBSFN subframe of the first cell.

[0068] Step 301 in this embodiment is the same as step 201 in the previously described embodiment shown in Figure 2. Details will not be explained again here.

[0069] 302: The network device sends the target message to the second cell.

[0070] As defined in protocol 3GPP® TS 36331, if an Evolved Multimedia Broadcast Multicast Service (eMBMS) cell exists in a neighboring cell, the cell notifies its UEs (User Entities) of the presence of the eMBMS neighboring cell via a system message. Therefore, when measuring the coverage signal strength of a neighboring cell, the UEs in the cell measure only CRS symbols within the neighboring cell's non-MBSNF subframes.

[0071] Based on this, the network device may send a target message via the X2 interface to a neighboring cell (i.e., a second cell) that has a handover relationship with the first cell. The target message is used to inform the second cell that the eMBMS cell is located in the second cell's neighboring cell. When the second cell measures the coverage signal strength of the first cell after receiving the target message, the UE in the second cell measures only CRS symbols in the non-MBSNF subframes of the neighboring cell. The network device does not adjust the transmit power of the symbols. Therefore, the coverage signal strength of the first cell, as measured by the UE in the second cell, does not change before and after the network device adjusts the transmit power of the first cell, and the reselection of the UE in the second cell and the handover to the first cell are unaffected.

[0072] After receiving the target message, the second cell broadcasts the target message to the UE connected to the second cell via a system message. Specifically, the UE of the second cell may be notified by broadcast via the neighCellConfig field in the second cell's SIB3 and SIB5 messages. The field definition is as follows:

[0073] 00: Not all neighbor cells have the same MBSFN subframe allocation as the serving cell on this frequency, if configured, and as the PCell otherwise.

[0074] 10: The MBSFN subframe allocations of all neighbor cells are identical to or subsets of that in the serving cell on this frequency, if configured, and of that in the primary cell otherwise.

[0075] 01: No MBSFN subframes are present in all neighbor cells.

[0076] 11: Different UL / DL allocation in neighboring cells for TDD compared to the serving cell on this frequency, if configured, and compared to the primary cell otherwise.

[0077] From the field definition, it can be seen that a UE connected to a second cell may be notified of the existence of an eMBMS neighboring cell by configuring the field as 00.

[0078] In some possible solutions, it should be noted that when measuring the coverage signal strength of an eMBMS neighboring cell, in addition to measuring the CRS symbol in a non-MBSFN subframe, the UE further measures the CRS symbol at the position of symbol 0 in the MBSFN subframe. In this case, in step 301, it must be limited that the target symbol does not contain the CRS symbol at the position of symbol 0 in the MBSFN subframe. If the network device reduces the transmit power of the target symbol, the result of the UE's measurement of the coverage signal strength of the first cell in the second cell will be reduced, which will affect the handover of the UE in the second cell to the first cell for connection.

[0079] It can be understood that step 302 may be performed before or after step 303, in which the transmission power of the target symbol is reduced. The time order of step 302 is not limited herein.

[0080] 303: If the load on the first cell is lower than a preset threshold, the network device reduces the transmit power of the target symbol.

[0081] Step 303 in this embodiment is the same as step 202 in the previously described embodiment shown in Figure 2. Details will not be explained again here.

[0082] 304: The network device reduces the minimum access level threshold for the first cell.

[0083] Reducing the transmit power of the target symbol (CRS symbol) of the first cell will result in a decrease in the coverage signal strength of the first cell, as measured by the UE within the first cell. The coverage signal strength is primarily the RSRP or RSRQ value. However, an idle UE does not continuously measure the CRS symbol; an idle UE remains asleep for a certain period and then wakes up periodically to measure the cell's signal. The wake-up time window does not have a fixed length but includes a certain number of normal subframes (i.e., non-MBSFN subframes). This is because normal subframes contain information such as the Master Information Block (MIB), Primary Synchronization Signal (PSS), and Paging, and the UE needs this information to perform basic functions such as reading synchronization and paging messages. Therefore, reducing the transmit power of the target symbol will not cause an idle UE to fail to detect the signal of the first cell.

[0084] However, in actual use, a minimum access level threshold is typically set for a cell, and a decrease in coverage signal strength can cause the RSRP or RSRQ value obtained by an idle UE through measurement to fall below the minimum access level threshold, potentially causing the idle UE to be disconnected from the network. Taking this into consideration, after reducing the transmit power of the target symbol, the network device obtains the RSRP compensation amount or the RSRQ compensation amount for the first cell, reduces the minimum access level threshold for the first cell based on the RSRP compensation amount or RSRQ compensation amount, and notifies the UE via a system message, thereby ensuring that the RSRP or RSRQ value actually obtained by the UE through measurement is higher than the reduced minimum access level threshold, and that the idle UE is not disconnected from the network. Step 306 describes a method for the network device to obtain the RSRP compensation amount or the RSRQ compensation amount for the first cell.

[0085] 305: The network device determines that the UE connected to the first cell is within the target threshold.

[0086] For UEs in a connected state, a decrease in cell coverage signal strength can pre-trigger inter-frequency or inter-system handovers to UEs in edge areas, impacting cell traffic and key performance indicators (KPIs), such as call interruptions. Therefore, UEs should be prevented from being pre-handovered to inter-frequency or inter-system cells whenever possible.

[0087] With this in mind, the network device may set a target threshold. The target threshold is higher than the minimum access level threshold for the first cell. Indeed, in addition to the minimum access level threshold, another threshold that can indicate cell edge characteristics may be used as an alternative, and this is not particularly limited herein. The network device reduces the transmit power of the target symbol only if the strength of all signals from the UE connected to the first cell is higher than the target threshold. If the signal strength of the UE is lower than the target threshold, the network device stops reducing the transmit power of the target symbol, and as a result, the coverage signal strength of the first cell is no longer reduced. If the signal strength reported by the UE is again higher than the target threshold, the network device continues to reduce the transmit power to ensure that the UE does not pre-trigger an inter-frequency or inter-system handover due to a decrease in coverage signal strength, thereby avoiding KPI risks such as traffic loss or call drops.

[0088] 306: The network device calculates the compensation amount for the first cell and, based on the compensation amount, compensates for the RSRP or RSRQ reported by the UE in the first cell.

[0089] Compared to inter-frequency or inter-system cell handovers, intra-frequency cell handovers have less impact on service, and there are more UEs that can trigger intra-frequency cell handovers. Therefore, unlike inter-frequency or inter-system cell handovers, it is not possible to immediately stop reducing the transmit power of a target symbol when a UE is outside the target threshold.

[0090] In the case of in-frequency cell handover, the network device calculates the ratio of the decrement (in the time dimension) of CRS symbols at Port0 and Port1 and the ratio of the periodic reduction amplitude, and obtains a compensation amount using a linear calculation method. The compensation amount includes RSRP compensation values ​​or RSRQ compensation values ​​and is converted to values ​​in the dB domain (δ). The following uses FDD mode as an example for explanation.

[0091] Network devices obtain compensation based on the TTI amount (CRS Down TTI), the number of CRS symbols (CRS Down TTI, which is a decrement of 3 or 4), and the linear power reduction ratio (CRS Down Power Ratio) to implement power reduction in historical statistical periodicity. The calculation formula is as follows: The RSRP / RSRQ compensation amount δ(dB) = 10 × (-log(((CRS Down TTI × 3) × (CRS Down Power Ratio) + CRS Down TTI × 1 + (Total DL Tti - CRS Down TTI) × 3) / (Total DL TTI × 3))) The compensation value is obtained by calculation and is equal to -1.1 dB.

[0092] After obtaining the compensation amount for the first cell through calculation, the network device compensates for the RSRP or RSRQ reported by the UE in the first cell based on the compensation amount. The RSRP or RSRQ is carried in the handover request event.

[0093] 307: The network device determines whether the UE needs to be handed over to a neighboring cell within the frequency range.

[0094] When triggering an in-frequency cell handover, the UE in the first cell sends a handover request to the network device. The handover request carries the signal strength of the first cell (RSRP or RSRQ) and the signal strength of the in-frequency neighboring cell, as measured by the UE. After performing compensatory remediation for the RSRP or RSRQ of the first cell, as measured and reported by the UE, the network device determines whether the UE needs to be handed over to an in-frequency neighboring cell. Specifically, if the signal strength of the UE in the first cell after the compensation check does not actually meet the in-frequency handover threshold requirement, the network device will not perform the UE handover. The network device will only actually perform the UE handover if the signal strength of the UE in the first cell after the compensation check is indeed low enough to meet the in-frequency handover threshold requirement. For example, the in-frequency handover threshold is 3dB, and the RSRP value of the first cell, obtained by the UE through measurement, is -95dBm, and the RSRP value of the in-frequency neighboring cell to be handed over is -91dBm, and the difference between the two values ​​is greater than 3dB. However, in this case, the coverage compensation amount is 2dB, so the RSRP value of the first cell, obtained by the UE through measurement, is restored to -93dBm after compensation, and the difference between the RSRP value of the first cell and the RSRP value of the in-frequency neighboring cell is less than 3dB. The handover threshold is not actually met, and the network device does not need to perform a handover by the UE.

[0095] 308: If the load on the first cell exceeds a preset threshold, the network device increases the transmit power of the target symbol.

[0096] Step 308 in this embodiment is the same as step 203 in the previously described embodiment shown in Figure 2. Details will not be described again here.

[0097] In this embodiment, in addition to rapidly adjusting the cell's transmit power, the network device can further maintain the measurement of cell signal invariance by UEs in neighboring cells without affecting mobility functions such as UE reselection and handover to cells in neighboring cells. In addition, the network device can prevent UEs in a cell from being handed over to another cell as much as possible. This prevents traffic and user loss and ensures stable basic KPIs such as call drops and handovers. Furthermore, the network device can automatically adjust the cell's transmit power based on a pre-configured cell load threshold, and can further automatically stop reducing the cell's transmit power or continue reducing the cell's transmit power based on the status of UEs in the cell, without complex manual intervention and processing, thereby reducing application difficulty.

[0098] The above describes the energy saving method in the embodiments of this application. The following describes the communication device in the embodiments of this application. Please refer to Figure 4. One embodiment of the communication device in the embodiments of this application is: A determination module 401 configured to determine a target symbol within a subframe of a first cell's multimedia broadcast multicast service single-frequency network MBSFN, wherein the target symbol is a cell-specific reference signal CRS symbol, a demodulated modulation reference signal DMRS symbol, a physical downlink control channel PDCCH symbol dedicated to terminal devices UE, and a physical downlink shared channel PDSCH symbol dedicated to UE. A reduction module 402 configured to reduce the transmit power of a target symbol when the load of the first cell is lower than a preset threshold, An increase module 403 is configured to increase the transmit power of the target symbol when the load of the first cell is higher than a preset threshold. Includes.

[0099] The following describes in detail the communication device according to the embodiments of this application. Please refer to Figure 5. Another embodiment of the communication device according to the embodiments of this application is: A determination module 501 configured to determine a target symbol within a subframe of a first cell's multimedia broadcast multicast service single-frequency network MBSFN, wherein the target symbol is a cell-specific reference signal CRS symbol, a demodulated modulation reference signal DMRS symbol, a physical downlink control channel PDCCH symbol dedicated to terminal devices UE, and a physical downlink shared channel PDSCH symbol dedicated to UE. A reduction module 502 configured to reduce the transmit power of a target symbol when the load of the first cell is lower than a preset threshold, An increase module 503 is configured to increase the transmit power of the target symbol when the load of the first cell is higher than a preset threshold. Includes.

[0100] Optionally, the MBSFN subframe does not carry the System Information Block (SIB) message, Paging message, Message 2 (MSG2), or Message 4 (MSG4) of the first cell.

[0101] Optionally, the target symbols do not include symbols in the physical control format indicator channel PCFICH and the physical hybrid auto-resend indicator channel PHICH, or the common PDCCH symbol and channel state reference signal CSIRS symbol of the first cell.

[0102] Optionally, the PDSCH symbol may not include the Voice over Long Term Evolution (VoLTE) symbol, the Signaling Radio Bearer 1 (SRB1) symbol, or the Signaling Radio Bearer 2 (SRB2) symbol.

[0103] Optionally, the CRS symbol is located outside the position of symbol 0 in the MBSFN subframe.

[0104] Optionally, the communication device further includes a transmit module 504 configured to transmit a target message to a second cell. The target message indicates that an Evolutionary Multimedia Broadcast Multicast Service (eMBMS) cell resides in a neighboring cell with which it has a handover relationship with the second cell, and that the neighboring cell includes the first cell.

[0105] Optionally, the decision module 501 is further configured to determine that the intensity of the signal received by the UE in the first cell is higher than the target threshold of the first cell. The target threshold is higher than the minimum access level threshold of the first cell.

[0106] Optionally, the communication device further includes a calculation module 505 configured to calculate a compensation amount for the reference signal received power RSRP or the reference signal received quality RSRQ of a first cell, and to compensate for the RSRP or RSRQ reported by the UE in the first cell based on the RSRP or RSRQ compensation amount.

[0107] Optionally, the reduction module 502 is further configured to reduce the minimum access level threshold of the first cell based on the RSRP compensation amount or the RSRQ compensation amount.

[0108] In this embodiment, the units within the communication device perform the operations of the communication device in the embodiments shown in Figures 2 and 3. Further details will not be described here.

[0109] Figure 6 is a possible diagram of the structure of a communication device according to one embodiment of the present application. The communication device includes a processor 601, a communication interface 602, a memory 603, and a bus 604. The processor 601, the communication interface 602, and the memory 603 are interconnected via the bus 604. In the embodiment of the present application, the processor 601 is configured to control and manage the operation of the communication device. For example, the processor 601 is configured to perform the steps in the embodiment of the method shown in Figures 2 and 3. The communication interface 602 is configured to support communication of the communication device. The memory 603 is configured to store program code and data of the communication device.

[0110] The processor 601 may be a central processing unit, a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or another programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The processor may implement or run various exemplary logic blocks, modules, and circuits described with reference to what is disclosed in this application. Alternatively, the processor may be a combination of processors that perform arithmetic functions, for example, a combination of one or more microprocessors, or a combination of a digital signal processor and a microprocessor. The bus 604 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus. The bus may include an address bus, a data bus, a control bus, etc. For ease of representation, the bus is shown as a single thick line in Figure 6. However, this does not mean that there is only one bus or only one type of bus.

[0111] One embodiment of this application further provides a computer-readable storage medium. The computer-readable storage medium includes instructions. When the instructions are invoked in a computer, the computer is enabled to perform the method according to the embodiment shown in Figures 2 and 3.

[0112] One embodiment of this application further provides a computer program product including instructions. When the computer program product is started on a computer, the computer is made able to perform the methods of the embodiments shown in Figures 2 and 3.

[0113] One embodiment of this application further provides a chip system. The chip system includes at least one processor and a communication interface. The communication interface and the at least one processor are interconnected via a line. The at least one processor is configured to invoke a computer program or instruction to execute the method in the embodiment shown in Figures 2 and 3.

[0114] For the sake of a simple and concise explanation, the detailed operating processes of the aforementioned systems, apparatus, and units should be referred to the corresponding processes in the embodiments of the methods described above, and it will be readily apparent to those skilled in the art that further details are not described herein.

[0115] In some embodiments provided in this application, it should be understood that the disclosed systems, apparatus, and methods may be implemented in other ways. For example, the embodiments of the apparatus described above are merely illustrative. For example, the unit division is merely a logical functional division, and other divisions may be used in actual implementations. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the mutual coupling, direct coupling, or communication connection shown or discussed may be implemented through some interfaces. Indirect coupling or communication connection between apparatus or units may be implemented in an electrical, mechanical, or other form.

[0116] Units described as separate parts may or may not be physically separate, and parts shown as units may or may not be physical units, may be located in one place, or may be distributed across multiple network units. Some or all of the units may be selected based on the actual requirements in order to achieve the objectives of the solutions of the embodiments.

[0117] In addition, the functional units in the embodiments of this application may be integrated into a single processing unit, or each unit may exist physically independently, or two or more units may be integrated into a single unit. The integrated unit may be implemented in hardware form or in the form of a software functional unit.

[0118] If the integrated unit is implemented in the form of a software function unit and sold or used as an independent product, the integrated unit may be stored on a computer-readable storage medium. Based on such understanding, the technical solution of this application, or a portion that contributes to the prior art, or all or part of the technical solution, may be implemented in the form of a software product. A computer software product includes several instructions that are stored on a storage medium and instruct a computer device (which may be a personal computer, server, network device, etc.) to perform all or part of the steps of the method described in the embodiments of this application. The aforementioned storage medium includes any medium capable of storing program code, such as a USB flash drive, removable hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk. [Explanation of symbols]

[0119] 101 Network Devices 102 Terminal devices 103 Terminal devices 104 Terminal Devices 105 cells 106 cells 401 Decision Module 402 Reduction Module 403 Expansion Module 501 Decision Module 502 Reduction Module 503 Expansion Modules 504 Transmitter Module 505 Computing Module 601 Processor 602 Communication Interface 603 memory 604 Bus

Claims

1. It is an energy saving method, A step of determining, by a network device, a target symbol within a multimedia broadcast multicast service single-frequency network subframe of a first cell, wherein the target symbol is one of four types of target symbols: a cell-specific reference signal symbol, a demodulation modulation reference signal symbol, a physical downlink control channel symbol dedicated to a terminal device, and a physical downlink shared channel symbol dedicated to the terminal device. If the load of the first cell is lower than a preset threshold, the network device simultaneously reduces the transmission power of the four types of target symbols. If the load of the first cell is higher than the preset threshold, the network device simultaneously increases the transmit power of the four types of target symbols. Methods that include...

2. The method according to claim 1, wherein the multimedia broadcast multicast service single-frequency network subframe does not carry the system information block message, paging message, message 2, or message 4 of the first cell.

3. The method according to claim 1 or 2, wherein the target symbol does not include symbols in the physical control format indicator channel and the physical hybrid auto-resend indicator channel, or the common physical downlink control channel symbol and channel state reference signal symbol of the first cell.

4. The method according to claim 1 or 2, wherein the physical downlink shared channel symbol does not include a voice-over-long-term evolution symbol, a signaling radio bearer 1 symbol, or a signaling radio bearer 2 symbol.

5. The method according to claim 1 or 2, wherein the cell-specific reference signal symbol is located outside the position of symbol 0 of the multimedia broadcast multicast service single-frequency network subframe.

6. The method described above is The method according to claim 1 or 2, further comprising the step of sending a target message to a second cell by the network device, wherein the target message indicates that an evolutionary multimedia broadcast multicast service cell is located in a neighboring cell having a handover relationship with the second cell, and the neighboring cell includes the first cell.

7. Before the step of simultaneously reducing the transmission power of the four types of target symbols by the network device, the method The method according to claim 1 or 2, further comprising the step of the network device determining that the intensity of a signal received by a terminal device in the first cell is higher than a target threshold for the first cell, wherein the target threshold is higher than a minimum access level threshold for the first cell.

8. After the step of simultaneously reducing the transmission power of the four types of target symbols by the network device, the method The steps include: calculating the amount of compensation for the reference signal received power or the reference signal received quality of the first cell using the network device; The steps include: compensating the reference signal received power or the reference signal received quality reported by the terminal device in the first cell with the network device based on the compensation amount for the reference signal received power or the compensation amount for the reference signal received quality; The method according to claim 1 or 2, further comprising:

9. The method described above is The method according to claim 8, further comprising the step of reducing the minimum access level threshold of the first cell by the network device based on the compensation amount for the reference signal received power or the compensation amount for the reference signal received quality.

10. A communication device, A determination module configured to determine a target symbol within a single-frequency network subframe of a first cell's multimedia broadcast multicast service, wherein the target symbol is one of four types of target symbols: a cell-specific reference signal symbol, a demodulated modulation reference signal symbol, a physical downlink control channel symbol dedicated to a terminal device, and a physical downlink shared channel symbol dedicated to the terminal device. A reduction module configured to simultaneously reduce the transmit power of the four types of target symbols when the load of the first cell is lower than a preset threshold, An increase module configured to simultaneously increase the transmit power of the four types of target symbols when the load of the first cell is higher than the preset threshold, and A device equipped with the following features.

11. The apparatus according to claim 10, wherein the multimedia broadcast multicast service single-frequency network subframe does not carry the system information block message, paging message, message 2, or message 4 of the first cell.

12. The apparatus according to claim 10 or 11, wherein the target symbol does not include symbols in the physical control format indicator channel and the physical hybrid auto retransmission indicator channel, or the common physical downlink control channel symbol and channel state reference signal symbol of the first cell.

13. The apparatus according to claim 10 or 11, wherein the physical downlink shared channel symbol does not include a voice-over-long-term evolution symbol, a signaling radio bearer 1 symbol, or a signaling radio bearer 2 symbol.

14. The apparatus according to claim 10 or 11, wherein the cell-specific reference signal symbol is located outside the position of symbol 0 of the multimedia broadcast multicast service single-frequency network subframe.

15. The apparatus according to claim 10 or 11, further comprising a transmission module configured to transmit a target message to a second cell, wherein the target message indicates that an evolved multimedia broadcast multicast service cell is located in a neighboring cell having a handover relationship with the second cell, and the neighboring cell includes the first cell.

16. The apparatus according to claim 10 or 11, wherein the determination module is further configured to determine that the intensity of a signal received by a terminal device in the first cell is higher than a target threshold of the first cell, and the target threshold is higher than a minimum access level threshold of the first cell.

17. The apparatus according to claim 10 or 11, further comprising a calculation module configured to calculate a compensation amount for the reference signal received power or the reference signal received quality of the first cell, and to compensate the reference signal received power or the reference signal received quality reported by the terminal device in the first cell based on the compensation amount for the reference signal received power or the compensation amount for the reference signal received quality.

18. The apparatus according to claim 17, wherein the reduction module is further configured to reduce the minimum access level threshold of the first cell based on the compensation amount for the reference signal received power or the compensation amount for the reference signal received quality.

19. A communication device, It comprises at least one processor and interface circuitry, The interface circuit is configured to provide programs or instructions to the at least one processor, A communication device in which the at least one processor is configured to execute the program or the instructions, enabling the communication device to perform the method according to claim 1 or 2.

20. A computer-readable medium wherein the computer-readable medium stores instructions, and when an instruction is executed by a computer, the method according to claim 1 or 2 is performed.

21. A computer program including instructions, wherein when the instructions are executed in a computer, the computer is enabled to perform the method according to claim 1 or 2.

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