Method, apparatus and computer program product for wireless communication

Abstract

The present disclosure generally relates to a method, an apparatus, and a computer program product for wireless communication. The method is performed by a first network element (NE) in a wireless network, the method comprising: transmitting a first handover request message to a second NE, the first handover request message requesting a handover of a user equipment (UE) from a source cell in the first NE to a first cell in the second NE, the first handover request message comprises at least one of the following: an identifier of the first cell; a switching reason; load information of one or more source cells managed by the first NE; or a power saving mode associated with power saving in the first NE.

Description

[0001] This application is a divisional application of Chinese patent application No. 202280094873.6, filed on April 22, 2022, entitled “Method, apparatus and system for resource management in wireless networks”. Technical Field

[0002] This disclosure is generally directed to wireless communications, and more particularly to methods, apparatus and systems for resource management and power saving in wireless networks. Background Technology

[0003] Energy efficiency is a key performance indicator in wireless communication networks. Controlling power consumption and reducing energy costs are crucial for the development and deployment of wireless communication networks. Energy-saving technologies play a vital role in achieving this goal. From the user equipment (UE) perspective, UE battery life has a significant impact on user experience. From the network perspective, energy consumption is a key consideration for operators to improve investment efficiency. The ability to dynamically control the power consumption of various network elements and / or network resources while still meeting performance requirements is beneficial. Summary of the Invention

[0004] This disclosure relates to a method, apparatus, and system for resource management and power saving in wireless networks.

[0005] In some embodiments, a method performed by a device in a wireless network is disclosed. The method may include: receiving a first message from a network element in the wireless network, the first message including validity information for downlink transmission resources associated with downlink transmission; and skipping monitoring of downlink transmission resources in response to the validity information indicating that the downlink transmission resources are invalid.

[0006] In some embodiments, a method performed by a first network element (NE) in a wireless network is disclosed. The method may include: transmitting a first handover request message to a second NE, the first handover request message requesting a user equipment (UE) to be handed over from the first NE to a first cell in the second NE, the first handover request message including at least one of the following: an identifier of the first cell; a handover reason; load information of the first cell; or a power-saving mode associated with power saving in the first NE.

[0007] In some embodiments, there is a network element or UE that includes a processor and a memory, wherein the processor is configured to read code from the memory and implement any of the methods described in any embodiment.

[0008] In some embodiments, a computer program product includes computer-readable program medium code stored thereon, which, when executed by a processor, causes the processor to perform any of the methods described in any embodiment.

[0009] Other aspects and alternatives to the above embodiments and their implementation are described in more detail in the following drawings, description and claims. Attached Figure Description

[0010] Figure 1 An example wireless communication network is shown.

[0011] Figure 2 An example wireless network node is shown.

[0012] Figure 3 An example user device is shown.

[0013] Figure 4 An exemplary downlink (DL) slot closure scheme is illustrated.

[0014] Figure 5 An exemplary message stream is shown for notifying slot / symbol closing information.

[0015] Figure 6 An exemplary bitmap showing coverage slots under various subcarrier spacings is shown.

[0016] Figure 7 An exemplary DL symbol closure scheme is shown.

[0017] Figures 8-10 An exemplary switching scenario is shown. Detailed Implementation

[0018] Wireless communication network

[0019] Figure 1 An exemplary wireless communication network 100 is shown, including a core network 110 and a radio access network (RAN) 120. The core network 110 also includes at least one mobility management entity (MME) 112 and / or at least one access and mobility management function (AMF). Other functions that may be included in the core network 110 are not shown in the diagram. Figure 1As shown in the diagram. RAN 120 also includes multiple base stations (e.g., base stations 122 and 124). Base stations may include at least one evolved NodeB (eNB) for 4G LTE, an enhanced LTE eNB (ng-eNB), or a next-generation NodeB (gNB) for 5G New Radio (NR), or any other type of signal transmission / reception equipment such as a UMTS NodeB. eNB 122 communicates with MME 112 via the S1 interface. Both eNB 122 and gNB 124 can be connected to AMF 114 via the Ng interface. Each base station manages and supports at least one cell. For example, base station gNB 124 can be configured to manage and support cells 1, 2, and 3.

[0020] The gNB 124 may include a centralized unit (CU) and at least one distributed unit (DU). The CU and DU may be located in the same location, or they may be separated into different locations. The CU and DU may be connected via an F1 interface. Alternatively, for an eNB capable of connecting to a 5G network, it may similarly be divided into a CU and at least one DU (referred to as ng-eNB-CU and ng-eNB-DU, respectively). The ng-eNB-CU and ng-eNB-DU may be connected via a W1 interface.

[0021] The wireless communication network 100 may include one or more tracking areas. The tracking area may include a set of cells managed by at least one base station. For example, tracking area 1, labeled 140, includes cells 1, 2, and 3, and may also include cells that can be managed by other base stations and are not yet in use. Figure 1 More cells are shown in the diagram. The wireless communication network 100 may also include at least one UE 160. The UE can select a cell from a plurality of cells supported by the base station to communicate with the base station via an over-the-air (OTA) radio communication interface and resources, and can reselect the cell for communication as the UE 160 travels within the wireless communication network 100. For example, the UE 160 may initially select cell 1 to communicate with the base station 124, and then it may reselect cell 2 at a later time. The cell selection or reselection of the UE 160 may be based on the radio signal strength / quality in each cell and other factors.

[0022] The wireless communication network 100 can be implemented as, for example, a 2G, 3G, 4G / LTE, or 5G cellular communication network. Correspondingly, base stations 122 and 124 can be implemented as 2G base stations, 3G NodeBs, LTE eNBs, or 5G NR gNBs. The UE 160 can be implemented as a mobile or fixed communication device capable of accessing the wireless communication network 100. The UE 160 can include, but is not limited to, mobile phones, laptops, tablets, personal digital assistants, wearable devices, Internet of Things (IoT) devices, MTC / eMTC devices, distributed remote sensing devices, roadside assistance devices, XR devices, and desktop computers. The UE 160 may also be commonly referred to as a wireless communication device or a wireless terminal. The UE 160 can support sidelink communication to another UE via a PC5 interface.

[0023] Although the following description focuses on, for example Figure 1 The cellular wireless communication system shown is based on the same principles, but the same principles apply to other types of wireless communication systems used for paging wireless devices. These other wireless systems may include, but are not limited to, Wi-Fi, Bluetooth, ZigBee, and WiMax networks.

[0024] Figure 2 An example of an electronic device 200 for implementing a network base station (e.g., a radio access network node), core network (CN), and / or operation and maintenance (OAM) is shown. Optionally, in one embodiment, the example electronic device 200 may include radio transmit / receive (Tx / Rx) circuitry 208 for transmitting / receiving communications with a UE and / or other base stations. Optionally, in one embodiment, the electronic device 200 may also include network interface circuitry 209 for communicating the base station with other base stations and / or the core network, for example, optical or wired interconnects, Ethernet, and / or other data transmission media / protocols. The electronic device 200 may optionally include an input / output (I / O) interface 206 for communicating with operators, etc.

[0025] Electronic device 200 may also include system circuitry 204. System circuitry 204 may include one or more processors 221 and / or memory 222. Memory 222 may include operating system 224, instructions 226, and parameters 228. Instructions 226 may be configured for one or more processors 221 to perform the functions of a network node. Parameters 228 may include parameters for supporting the execution of instructions 226. For example, parameters may include network protocol settings, bandwidth parameters, radio frequency mapping allocation, and / or other parameters.

[0026] Figure 3An example of an electronic device for implementing terminal device 300 (e.g., user equipment (UE)) is shown. UE 300 may be a mobile device, such as a smartphone or a mobile communication module installed in a vehicle. UE 300 may include some or all of the following: communication interface 302, system circuitry 304, input / output interface (I / O) 306, display circuitry 308, and storage device 309. The display circuitry may include a user interface 310. System circuitry 304 may include any combination of hardware, software, firmware, or other logic / circuit. System circuitry 304 may be implemented using, for example, one or more system-on-chip (SoC), application-specific integrated circuit (ASIC), discrete analog and digital circuitry, and other circuitry. System circuitry 304 may be part of an implementation of any desired functionality in UE 300. In this regard, system circuitry 304 may include, for example, logic that facilitates decoding and playing music and video (e.g., MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback); running applications; accepting user input; saving and retrieving application data; establishing, maintaining, and terminating cellular phone calls or data connections (e.g., internet connections); establishing, maintaining, and terminating wireless network connections, Bluetooth connections, or other connections; and displaying relevant information on user interface 310. User interface 310 and input / output (I / O) interface 306 may include a graphical user interface, a touch-sensitive display, haptic feedback or other haptic outputs, voice or facial recognition inputs, buttons, switches, speakers, and other user interface elements. Additional examples of I / O interface 306 may include microphones, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headset and microphone input / output jacks, universal serial bus (USB) connectors, memory card slots, radiation sensors (e.g., IR sensors), and other types of inputs.

[0027] Reference Figure 3The communication interface 302 may include radio frequency (RF) transmission (Tx) and reception (Rx) circuitry 316, which processes the transmission and reception of signals via one or more antennas 314. The communication interface 302 may include one or more transceivers. The transceiver may be a wireless transceiver, including modulation / demodulation circuitry, a digital-to-analog converter (DAC), a shaping table, an analog-to-digital converter (ADC), filters, waveform shapers, filters, preamplifiers, power amplifiers, and / or other logic for transmission and reception via one or more antennas or (for some devices) via a physical (e.g., wired) medium. The transmitted and received signals may follow any of a variety of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), frequency channels, bit rates, and encodings. As a specific example, the communication interface 302 may include a transceiver supporting transmission and reception under 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High-Speed ​​Packet Access (HSPA)+, 4G / LTE, and 5G standards. However, the techniques described below are applicable to other wireless communication technologies, whether they originate from the 3rd Generation Partnership Project (3GPP), the GSM Association, 3GPP2, IEEE, or other partners or standards bodies.

[0028] Reference Figure 3 System circuitry 304 may include one or more processors 321 and memory 322. Memory 322 stores, for example, an operating system 324, instructions 326, and parameters 328. Processor 321 is configured to execute instructions 326 to achieve the desired functionality of UE 300. Parameters 328 can provide and specify configuration and operational options for instructions 326. Memory 322 may also store any BT, WiFi, 3G, 4G, 5G, or other data that UE 300 will send or has received via communication interface 302. In various embodiments, the system power of UE 300 may be provided by power storage devices such as batteries or transformers.

[0029] Power saving in wireless networks

[0030] Energy consumption has become a critical component of operators' operating expenses (OPEX). In wireless networks, significant energy consumption comes from the radio access network, particularly from hardware circuitry such as active antenna units (AAU), radio units (RU), remote radio units (RRU), and power amplifiers (PA).

[0031] In wireless networks, various network operation modes can be implemented to accommodate different service requirements and trade-offs. One mechanism for saving network power consumption is flexible downlink transmission management, utilizing fast-response hardware that can be activated and deactivated on timescales ranging from hundreds of microseconds to hundreds of milliseconds. For example, downlink transmission can be performed at the slot level and the symbol level. Based on certain load and service management policies, the base station can determine to shut down certain slots and / or symbols. When a slot or symbol is shut down, it is considered invalid or reserved, and the UE will not monitor the shut-down resource. Through this shutdown mechanism, related hardware such as radio frequency (RF) circuits, transmit (TX) / receive (RX) antennas, etc., can be deactivated to save power.

[0032] Furthermore, in a wireless network, multiple RAN nodes (e.g., gNB, eNB, or ng-eNB, or combinations thereof) can interact with each other to exchange power-saving information about various resources and states. Resources may include: cells, carriers, beams, network slices, bandwidth portions (BWP), bandwidth represented by frequency ranges, time slots, or symbols. States may include power-saving modes / states. Power-saving information may also include load information. By utilizing power-saving information from other network elements, such as RAN nodes, network elements can make more informed choices when attempting to shut down specific resources such as time slots or symbols. In some implementations, artificial intelligence (AI) models can be developed and deployed, using power-saving information as input, to determine patterns for shutting down resources such as time slots and symbols.

[0033] From the perspective of time slot / symbol shutdown, the timing of the RAN node notifying the UE to skip and resume signal monitoring is important.

[0034] This disclosure presents various embodiments for implementing base station and UE coordination when downlink slots / symbols are off.

[0035] Example 1: Downlink slot closure

[0036] Figure 4 An example DL slot closure scheme is illustrated. Line 410 above shows the UE monitoring behavior when no DL slot is closed, and line 450 below shows the UE monitoring behavior when DL slot 1 is closed. In this disclosure, when a DL slot is closed, that DL slot is invalid for, for example, signal / data transmission. The closed slot may also be referred to as a reserved slot, which is not intended for UE monitoring.

[0037] DL transmission may include Physical Downlink Control Channel (PDCCH) transmission and Physical Downlink Shared Channel (PDSCH) transmission. Using PDSCH as an example, in an exemplary implementation, when the duration of PDSCH transmission conflicts with an invalid (closed) time slot, it can be postponed to the next valid time slot. (See also...) Figure 4 The PDSCH transmission duration 412 lasts for 10 symbols (i.e., in line 410 above, from symbol 10 in slot 0 to symbol 5 in slot 1). During the PDSCH transmission session, the base station (e.g., gNB, eNB, or ng-eNB) can decide to close slot 1. Line 450 below shows slot 1 (shaded) being closed and therefore invalid. The PDSCH transmission is deferred from slot 1 to slot 2 and ends in symbol 5 of slot 2. Figure 4 As shown, when time slot 1 is closed, symbols 0 to 5 initially assigned in time slot 1 are shifted to the next time slot, i.e., time slot 2. In this case, the UE will skip monitoring time slot 1 and continue monitoring symbols 0-5 in time slot 2, which are mapped to symbols 0-5 initially assigned in time slot 1. The new PDSCH duration when time slot 1 is closed is shown as 452 in line 450 below.

[0038] In one implementation, when a time slot is closed for DL ​​transmission, the DL transmission can be postponed to the next nth time slot (where n is a positive integer) and can be predetermined or signaled to the UE. Figure 4 In the example shown, n=1.

[0039] Reference Figure 5 The DL slot closure information can be signaled to the UE by the base station via at least one of the following: Radio Resource Control (RRC) messages, Medium Access Control (MAC) CE messages, Downlink Control Information (DCI) messages, or System Information messages (e.g., using System Information Blocks (SIBs)). The RRC, SIB, MAC CE, or DCI messages can carry a bitmap indicating which slot(s) will be closed (e.g., invalidSlotBitmap or reservedSlotBitmap). For example, each bit in the bitmap can correspond to a slot. When the bit is set to "1", the corresponding slot is invalid (closed or reserved) and will not be used or monitored by the UE.

[0040] In wireless networks, different subcarrier spacings (SCS) can exist. The SCS can affect the number of slots in each frame. Table 1 below shows exemplary SCS and the corresponding number of slots in each frame for a normal cyclic prefix.

[0041] Table 1: Number of OFDM symbols per slot, number of slots per frame, and number of slots per subframe for a normal cyclic prefix.

[0042]

[0043] Table 2 below shows the exemplary SCS and the corresponding number of slots in each frame for the extended cyclic prefix.

[0044] Table 2: Number of OFDM symbols per slot, number of slots per frame, and number of slots per subframe for the extended cyclic prefix.

[0045]

[0046] As can be seen, each frame can have a different number of time slots under different SCSs. For example, for a 15 kHz SCS, each frame has 10 time slots; for a 240 kHz SCS, each frame has 160 time slots. Several options for indicating invalid time slots are described below in this disclosure.

[0047] Option 1

[0048] In this option, select a fixed-length 160-bit bitmap to indicate invalid time slot information. For example:

[0049] invalidSlotBitmap (or reservedSlotBitmap) BIT STRING (SIZE (160))

[0050] Since 160 is the maximum number of time slots a frame can have under the maximum SCS configuration, depending on the SCS, 160 bits in the bitmap can cover the time slots of multiple extended frames, such as... Figure 6 As shown:

[0051] • For SCS 240kHz, in the time domain, each bit in the bitmap corresponds to (one-to-one mapping) each time slot of a radio frame.

[0052] • For SCS 120kHz, in the time domain, each bit in the bitmap corresponds to (one-to-one mapping) each time slot of two radio frames.

[0053] • For SCS 60kHz, in the time domain, each bit in the bitmap corresponds to (one-to-one mapping) each time slot of the four radio frames.

[0054] • For SCS 30kHz, in the time domain, each bit in the bitmap corresponds to (one-to-one mapping) each time slot of the eight radio frames.

[0055] • For SCS 15kHz, in the time domain, each bit in the bitmap corresponds to (one-to-one mapping) each time slot of the sixteen radio frames.

[0056] Option 2

[0057] Depending on the SCS, use a variable-length bitmap. For example:

[0058]

[0059] In this option, each bit in the bitmap is mapped one-to-one to a time slot in a radio frame. For example, when the SCS is 15 kHz, the bitmap only requires 10 bits to map to each of the 10 time slots in a frame under that SCS setting. As another example, when the SCS is 120 kHz, the bitmap requires 80 bits because there are 80 time slots per frame under that SCS setting.

[0060] Option 3

[0061] Unlike the first two options that use only one bitmap, this option applies a bitmap to up to two time slots, with each bit corresponding to one symbol in those two time slots. For example, when the bit is set to 1, the corresponding symbol in those two time slots will be turned off (invalidated). This option also provides periodicity, so the symbol-off pattern specified in the bitmap follows this periodic repetition.

[0062] Below are sample information elements for this option:

[0063] InvalidSymbolPattern ::= SEQUENCE {

[0064] symbols CHOICE {

[0065] oneSlot BIT STRING (SIZE (14)),

[0066] twoSlots BIT STRING (SIZE (28))

[0067] },

[0068] periodicityAndPattern CHOICE {

[0069] n2 BIT STRING (SIZE (2)),

[0070] n4 BIT STRING (SIZE (4)),

[0071] n5 BIT STRING (SIZE (5)),

[0072] n8 BIT STRING (SIZE (8)),

[0073] n10 BIT STRING (SIZE (10)),

[0074] n20 BIT STRING (SIZE (20)),

[0075] n40 BIT STRING (SIZE (40))

[0076] } OPTIONAL, --Need M ...

[0078] }

[0079] In the definition above:

[0080] • Symbol: A symbol-level bitmap in the time domain for one or two time slots, where each bit in the bitmap corresponds to a symbol.

[0081] •periodicityAndPattern: A time-domain repeating pattern under which the pattern is repeated. This time-slot pattern itself repeats continuously.

[0082] Example 2: Downlink Symbol Closure

[0083] In this disclosure, transmission resources can be disabled not only at the time slot level, as described in Example 1, but also at the symbol level.

[0084] Figure 7 An example DL symbol shutdown scheme is illustrated. Line 710 above shows the UE monitoring behavior when no DL symbol is shut down, and line 750 below shows the UE monitoring behavior when DL symbols 4 and 5 in slot 1 are shut down. In this disclosure, when a DL symbol is shut down, that DL symbol is invalid for, for example, signal / data transmission. A shut-down symbol may also be referred to as a reserved symbol, which is not intended for UE monitoring.

[0085] DL transmissions may include PDCCH transmissions and PDSCH transmissions. Using PDSCH as an example, in an exemplary implementation, when the duration of a PDSCH transmission conflicts with an invalid (closed) symbol, it can be deferred to the next valid symbol. See also... Figure 7The PDSCH transmission duration 712 lasts for 9 symbols (i.e., in line 710 above, starting from symbols 2-10 in time slot 1). During this PDSCH transmission session, the base station (e.g., gNB, eNB, or ng-eNB) can decide to shut down symbols 4-5 in time slot 1. Line 750 below shows symbols 4-5 in time slot 1 (shaded) being shut down and therefore invalid. The PDSCH transmission is deferred to the next valid symbol (i.e., symbol 6 in time slot 1). Figure 7 As shown in line 750 below, the DL transmission ends at symbol 12 in time slot 1. Because two symbols are turned off for the DL transmission, the entire DL transmission is shifted by 2 symbols and has a new PDSCH duration of 752.

[0086] DL symbol shutdown information can be sent by the base station via at least one of RRC messages, MAC CE, SIB, or DCI messages, in conjunction with... Figure 5 The UE is notified in a similar manner as shown. RRC, MAC CE, SIB, or DCI messages may carry a bitmap (e.g., invalidSymbolBitmap or reservedSymbolBitmap) indicating which symbol(s) will be turned off. For example, each bit in the bitmap may correspond to a symbol. When the bit is set to "1", the corresponding symbol is invalid (turned off or reserved) and will not be used or monitored by the UE.

[0087] In this disclosure, several options for indicating invalid symbols are described below.

[0088] Option 1

[0089] Considering that each slot has the same number of symbols (under normal cyclic prefix) for different SCS configurations, as mentioned above, invalidSlotBitmap or reservedSlotBitmap can be defined as a fixed-length bitmap:

[0090] invalidSymbolBitmap (or reservedSymbolBitmap) BIT STRING (SIZE (14))

[0091] Each bit of the bitmap corresponds to one symbol in one time slot. For SCS60kHz with an extended cyclic prefix, two bits are reserved (e.g., the last two bits).

[0092] Option 2:

[0093] In this option, a bitmap is applied to up to two time slots, with each bit corresponding to one symbol in those two time slots. For example, when the bit is set to 1, the corresponding symbol in those two time slots will be turned off (invalidated). This option also provides periodicity, so the symbol-off pattern specified in the bitmap repeats according to this periodicity.

[0094] Below are sample information elements for this option:

[0095] InvalidSymbolPattern ::= SEQUENCE {

[0096] symbols CHOICE {

[0097] oneSlot BIT STRING (SIZE (14)),

[0098] twoSlots BIT STRING (SIZE (28))

[0099] },

[0100] periodicityAndPattern CHOICE {

[0101] n2 BIT STRING (SIZE (2)),

[0102] n4 BIT STRING (SIZE (4)),

[0103] n5 BIT STRING (SIZE (5)),

[0104] n8 BIT STRING (SIZE (8)),

[0105] n10 BIT STRING (SIZE (10)),

[0106] n20 BIT STRING (SIZE (20)),

[0107] n40 BIT STRING (SIZE (40))

[0108] } OPTIONAL, --Need M ...

[0110] }

[0111] In the definition above:

[0112] • A symbol-level bitmap in the time domain for one or two time slots, where each bit in the bitmap corresponds to a symbol.

[0113] •periodicityAndPattern: A time-domain repeating pattern under which the pattern is repeated. This time-slot pattern itself repeats continuously.

[0114] Reference Figure 7 For an example regarding periodicity, in line 750 below, symbols 4-5 in slot 1 are turned off, which can be represented by two bits in `InvalidSymbolPattern:symbol`. The turning off of these two symbols can be periodic; that is, for example, the two identical symbols (i.e., symbols with the same number of symbols) can be turned off once every 1 frame, every 2 frames, every 4 frames, etc. Periodicity is defined by `InvalidSymbolPattern:periodicityAndPattern`.

[0115] Example 3:

[0116] The power-saving schemes described in Examples 1 and 2 may have an impact on UE handover (HO) scenarios. Specifically, when a base station decides to shut down some time slots and / or symbols or other resources, it may need to transfer (aggregate) some UE services / loads to another base station by performing UE handover.

[0117] In this embodiment, a base station initiates a handover request, requesting that the UE be handed over to a target cell in a second base station. The second base station, based on its policy and referring to load information, can accept the handover request, but will use a different cell to host the UE. See below for further details. Figure 8 To describe the details.

[0118] Step 1

[0119] Base station 1 sends a handover request message to base station 2. The handover request message may include at least one of the following: the target cell in base station 2, the reason for handover, the load information of one or more source cells managed by base station 1, or the power saving mode associated with base station 1.

[0120] The reason for switching can include at least one of the following:

[0121] • Load aggregation from base station 1 to base station 2;

[0122] • Load transfer from base station 1 to base station 2;

[0123] • Load balancing between base station 1 and base station 2;

[0124] • Overload conditions in base station 1;

[0125] • The network in base station 1 is power-saving; or

[0126] • The cell in base station 1 is closed.

[0127] Load information may include at least one of the following:

[0128] • Used by physical resource blocks (PRBs) in one or more source cells managed by base station 1;

[0129] • PRB usage for each beam in one or more source cells managed by base station 1;

[0130] • Used by the control channel element (CCE) in one or more source cells managed by base station 1;

[0131] • CCE usage for each beam in one or more source cells managed by base station 1;

[0132] • The number of active UEs in one or more source cells managed by base station 1; or

[0133] • The number of active UEs in each beam of one or more source cells managed by base station 1.

[0134] Power saving modes may include at least one of the following:

[0135] • A cell shutdown mode in which at least one cell is shut down;

[0136] • A carrier shutdown mode in which at least one carrier is turned off;

[0137] • Beam shut-off mode in which at least one beam is turned off;

[0138] • A slot closure mode in which at least one time slot is closed;

[0139] • A symbol-off mode in which at least one symbol is turned off;

[0140] • Deep sleep mode;

[0141] • Light sleep mode; or

[0142] • Normal mode.

[0143] When the base station (or other network element, UE, etc.) is in deep sleep mode, at least one of the radio circuits, radio resources, or network components is turned off.

[0144] When the base station (or other network elements, UE, etc.) is in a light sleep mode, the base station transmits or receives radio signals after a longer discontinuous reception (DRX) period or time interval than in normal mode. For example, multiple DRX periods can be configured, and one of the DRX periods can be used in normal mode. In light sleep mode, a longer DRX period can be selected from the configured DRX periods.

[0145] Step 2

[0146] Base station 2 may decide not to authorize access to the UE in the target cell specified in the handover request. However, if a new target cell exists in base station 2 that provides the same coverage as the target cell, or if the new target cell meets the UE's Quality of Service (QoS) requirements, base station 2 may decide to accept the UE in the new target cell. Base station 2 may send a handover request confirmation message to base station 1. The handover request confirmation message may include information that helps redirect the UE to the new target cell. This information may include at least one of the following:

[0147] •reason;

[0148] • Load information of the target cell and / or new target cells (the target cell and new target cells can be identified by cell identifiers, such as the Cell Global Identifier (CGI)).

[0149] • Redirection information associated with the new target cell; or

[0150] • RRC reconfiguration information associated with the new target cell.

[0151] The reasons may include at least one of the following: redirection triggered by load balancing, redirection triggered by overload, redirection triggered by network power saving, or redirection triggered by cell shutdown. For example, the target cell initially selected by the base station may be shut down or about to be shut down. The reason for "redirection triggered by overload" may indicate that the initially selected target cell is overloaded. The reason for "redirection triggered by network power saving" may indicate that the redirection is for power saving purposes.

[0152] The load information for the target cell and / or the new target cell includes at least one of the following:

[0153] • PRB usage in the target cell and / or new target cells;

[0154] • PRB usage for each beam in the target cell and / or new target cells;

[0155] • CCE usage in the target cell and / or new target cells;

[0156] • CCE usage for each beam in the target cell and / or new target cells;

[0157] • The number of active UEs in the target cell and / or new target cells; or

[0158] • The number of active UEs in each beam of the target cell and / or the new target cell.

[0159] Example 4:

[0160] In this embodiment, a base station initiates a handover request to hand over the UE to a target cell in a second base station. Based on its policy and referring to load information, the second base station may refuse the handover request, but can identify a new target cell in a third base station that might be suitable for handover. The following refers to... Figure 9 To describe the details.

[0161] Step 1

[0162] Base station 1 sends a handover request message to base station 2. This step is the same as step 1 in embodiment 3, and will not be described in detail here.

[0163] Step 2

[0164] Base station 2 may decide not to authorize access to the UE in the target cell specified in the handover request. However, if a new target cell exists in base station 3 that provides the same coverage as the target cell, or if the new target cell can meet the UE's Quality of Service (QoS) requirements, base station 2 may send a handover preparation failure message to base station 1. This handover preparation failure message may include information that helps redirect the UE to the new target cell in base station 3. This information may include at least one of the following:

[0165] •reason;

[0166] • Target cell load information (the target cell can be identified by its cell identifier, such as CGI); or

[0167] • Redirection information associated with the new target cell (e.g., the cell identifier of the new target cell).

[0168] The cause may include at least one of the following: load balancing, overload, network power saving, or cell shutdown.

[0169] The load information of the target cell includes at least one of the following:

[0170] • PRB usage in the target cell;

[0171] • PRB usage for each beam in the target cell;

[0172] • CCE usage in the target cell;

[0173] • CCE usage for each beam in the target cell;

[0174] • The number of active UEs in the target cell; or

[0175] • The number of active UEs for each beam in the target cell.

[0176] Step 3

[0177] After receiving a handover preparation failure message from base station 2, base station 1 can send a new handover request message to base station 3. This message may include the identifier of the new target cell in base station 3 to request that the UE be handed over to the new target cell in base station 3.

[0178] Example 5:

[0179] In this embodiment, a base station initiates a handover request to hand over the UE to a target cell in a second base station. Based on its policy and referring to load information, the second base station may refuse the handover request and may not be able to determine a new target cell for handover, but it can identify the target carrier for handover. The following refers to... Figure 10 To describe the details.

[0180] Step 1

[0181] Base station 1 sends a handover request message to base station 2. This step is the same as step 1 in embodiment 3, and will not be described in detail here.

[0182] Step 2

[0183] Base station 2 may decide not to authorize access to the UE in the target cell specified in the handover request. However, base station 2 can identify the carriers (or a list of carriers) used for handover. In this case, base station 2 may send a handover preparation failure message to base station 1. This handover preparation failure message may include information that helps the UE perform measurements on the identified carriers used for handover. This information may include at least one of the following:

[0184] •reason;

[0185] • Load information of one or more target cells managed by base station 2; or

[0186] • Redirection information associated with the target carrier;

[0187] The cause may include at least one of the following: redirection triggered by load balancing, redirection triggered by overload, redirection triggered by network power saving, or redirection triggered by cell shutdown.

[0188] The target carrier's payload information may include at least one of the following:

[0189] • Used by PRB in one or more target cells managed by base station 2;

[0190] • PRB usage for each beam in one or more target cells managed by base station 2;

[0191] • Used by CCE in one or more target cells managed by base station 2;

[0192] • CCE usage for each beam in one or more target cells managed by base station 2;

[0193] • The number of active UEs in one or more target cells managed by base station 2; or

[0194] • The number of active UEs in each beam of one or more target cells managed by base station 2.

[0195] The load information may also include load information for the cell used by base station 2.

[0196] Step 3

[0197] After receiving a handover preparation failure message from base station 2, base station 1 can send an RRC reconfiguration message to the UE to trigger the UE to perform direct measurements. The RRC reconfiguration request can include a measurement configuration (measConfig) carrying target carrier information. The target carrier information can include measurement object information. The UE can then perform direct measurements based on the measurement configuration.

[0198] In Examples 3-5, during the handover process, base station 1 and base station 2 exchange handover-related messages on the Xn interface using the Xn Application Protocol (XnAP). The same underscore principle can be used for handover based on the NG Application Protocol (NGAP) on the NGAP interface.

[0199] For example, Figure 8-10 The HANDOVER REQUEST message can be applied to both HANDOVERREQUIRED and HANDOVER REQUEST messages on the NGAP interface. Specifically, as described in Example 3, both the HANDOVERREQUIRED and HANDOVER REQUEST messages on the NGAP interface can include... Figure 8 Similar information may be included in the handover request. This information may include at least one of the following: the identifier of the target cell identified by the source base station, the handover reason, the load information of one or more source cells managed by the source base station, or the power saving mode associated with the source base station.

[0200] For another example, the HANDOVER REQUEST ACKNOWLEDGE message (such as...) Figure 8 (As shown) can be applied to the HANDOVER REQUEST ACKNOWLEDGE and HANDOVER COMMAND messages on the NGAP interface. Specifically, the HANDOVER REQUEST ACKNOWLEDGE and HANDOVER COMMAND messages on the NGAP interface can include, for example: Figure 8 Similar information contained in the switch request confirmation message shown. This information may include at least one of the following:

[0201] •reason;

[0202] • Load information of the target cell and / or new target cells (the target cell and new target cells can be identified by cell identifiers, such as CGI);

[0203] • Redirection information associated with the new target cell; or

[0204] • RRC reconfiguration information associated with the new target cell.

[0205] For another example, Figure 9-10 The HANDOVER PREPARATION FAILURE message can be applied to both HANDOVER FAILURE and HANDOVER PREPARATION FAILURE messages on the NGAP interface. Specifically, both HANDOVER FAILURE and HANDOVER PREPARATION FAILURE messages on the NGAP interface can include... Figure 9 or Figure 10 The message contains the same content as the handover preparation failure message shown. This message may include at least one of the following: redirection information with a new target cell ID or a new carrier, a reason, or load information.

[0206] The above description and accompanying drawings provide specific example embodiments and implementations. However, the described subject matter can be embodied in a variety of different forms, and therefore, the covered or claimed subject matter is intended to be construed as not being limited to any of the example embodiments set forth herein. A reasonably broad scope is intended for use with respect to the claimed or covered subject matter. Among other things, the subject matter can be embodied as a method, apparatus, component, system, or non-transitory computer-readable medium for storing computer code. Therefore, embodiments can take the form, for example, hardware, software, firmware, storage media, or any combination thereof. For example, the method embodiments described above can be implemented by components, apparatus, or systems including memory and processor by executing computer code stored in memory.

[0207] Throughout this specification and claims, terms may have subtle meanings implied or suggested in the context, rather than just explicitly stated meanings. Similarly, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to different embodiments. For example, the subject matter intended for the claims may include combinations of all or some of the exemplary embodiments.

[0208] Generally, terms can be understood, at least in part, from their usage in the context. For example, terms such as “and,” “or,” or “and / or,” as used herein, may include a variety of meanings that can depend, at least in part, on the context in which such terms are used. Typically, if “or” is used with an associative list such as A, B, or C, it is intended to mean A, B, and C, used here in an inclusive sense, and A, B, or C, used here in an exclusive sense. Furthermore, the term “one or more,” as used herein, depends at least in part on the context and can be used to describe any feature, structure, or characteristic in a singular sense, or can be used to describe a combination of features, structures, or characteristics in a plural sense. Similarly, terms such as “a,” “an,” or “the” can be understood to express either a singular or plural usage, at least in part on the context. Moreover, the term “based on” can be understood not necessarily to express a set of exclusive factors, but again can, at least in part on the context, allow for additional factors that are not necessarily explicitly described.

[0209] References to features, advantages, or similar language throughout this specification do not imply that all features and advantages achievable using this solution should be or are included in any single implementation thereof. Rather, language relating to features and advantages is to be understood as meaning that a specific feature, advantage, or characteristic described in conjunction with an embodiment is included in at least one embodiment of this solution. Therefore, throughout this specification, discussions of features and advantages and similar language may, but are not necessarily, refer to the same embodiments.

[0210] Furthermore, the features, advantages, and characteristics described in this solution can be combined in any suitable manner in one or more embodiments. Those skilled in the art will recognize that, in light of the description herein, this solution can be practiced without one or more specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of this solution.

Claims

1. A method for wireless communication, the method being performed by a first network element NE in a wireless network, the method comprising: A first handover request message is transmitted to the second NE, the first handover request message requesting that the user equipment UE be handed over from the source cell in the first NE to the first cell in the second NE, the first handover request message including at least one of the following: The identifier of the first cell; Reason for switching; Load information of one or more source cells managed by the first NE; or Power saving mode associated with power saving in the first NE.

2. The method according to claim 1, wherein, Each of the first NE and the second NE includes at least one of gNB, eNB, or ng-eNB.

3. The method according to claim 1, wherein, The switching reason includes at least one of the following: Load aggregation from the first NE to the second NE; Load balancing between the first NE and the second NE; Overload conditions in the first NE; The first NE's network is power-efficient; or The cell in the first NE is shut down.

4. The method according to claim 1, wherein, The load information of one or more source cells managed by the first NE includes at least one of the following: Physical resource blocks (PRBs) of one or more source cells managed by the first NE are used; Used by the control channel element (CCE) of one or more source cells managed by the first NE; or The number of active UEs in one or more source cells managed by the first NE.

5. The method according to claim 1, wherein, The power-saving mode includes at least one of the following: A cell shutdown mode in which at least one cell is closed; Carrier shutdown mode in which at least one carrier is turned off; Beam shut-off mode in which at least one beam is turned off; A slot-off mode in which at least one time slot is closed; Symbol-off mode in which at least one symbol is turned off; Deep sleep mode; Light sleep mode; or Normal mode.

6. The method according to any one of claims 1-5, further comprising: The acknowledgment of the first handover request message is received, the acknowledgment including redirection information indicating that the UE is to be redirected to a second cell in the second NE, and the acknowledgment further including at least one of the following: reason; Load information of the first cell; Load information of the second cell; or RRC reconfiguration information associated with the second cell.

7. The method according to claim 6, wherein, The reasons include at least one of the following: Load balancing between cells or carriers; Overload; Network power saving; or The residential area is closed.

8. The method according to claim 6, wherein, The load information of the second cell includes at least one of the following: PRB usage in the second cell; PRB usage for each beam in the second cell; CCE is used in the second cell; CCE usage for each beam in the second cell; The number of active UEs in the second cell; or The number of active UEs for each beam in the second cell.

9. The method according to any one of claims 1-5, further comprising: The system receives a response to the first handover request message, the response including redirection information indicating that the UE should be redirected to a third cell in the third NE, and the response further including at least one of the following: reason; Load information of the second cell; or The identifier of the third cell.

10. The method according to claim 9, wherein, The third NE includes at least one of gNodeB (gNB), eNodeB (eNB), or ng-eNB.

11. The method according to claim 9, wherein, The reasons include at least one of the following: Load balancing between cells or carriers; Overload; Network power saving; or The residential area is closed.

12. The method according to claim 9, wherein, The load information of the second cell includes at least one of the following: PRB usage in the second cell; PRB usage for each beam in the second cell; CCE is used in the second cell; CCE usage for each beam in the second cell; The number of active UEs in the second cell; or The number of active UEs for each beam in the second cell.

13. The method of claim 9, further comprising: A second handover request message is transmitted to the third NE, the second handover request message requesting that the UE be handed over to the third cell in the third NE.

14. The method according to any one of claims 1-5, further comprising: Receive a response to the first handover request message, the response indicating that the handover of the UE to the first cell failed and redirection to the target carrier, and the response further includes: Target carrier information for the target carrier selected by the UE for performing the handover; reason; Load information of the second cell; or Load information of the cell managed by the second NE.

15. The method according to claim 14, wherein, The reasons include at least one of the following: Redirection; Load balancing; Overload; Network power saving; or The residential area is closed.

16. The method of claim 14, wherein, The load information of the second cell includes at least one of the following: PRB usage in the second cell; PRB usage in the second cell; PRB usage for each beam in the second cell; CCE is used in the second cell; CCE usage for each beam in the second cell; The number of active UEs in the second cell; or The number of active UEs for each beam in the second cell.

17. The method of claim 14, further comprising: An RRC reconfiguration request, including measurement configuration information associated with the target carrier, is transmitted to the UE, and the RRC reconfiguration request triggers the UE to perform measurements based on the measurement configuration information.

18. A device for wireless communication, the device comprising a memory for storing computer instructions and a processor communicating with the memory, wherein, When the processor executes the computer instructions, the processor is configured to implement the method according to any one of claims 1-17.

19. A computer program product comprising a non-transient computer-readable program medium having computer code stored thereon, the computer code, when executed by one or more processors, causing the one or more processors to perform the method according to any one of claims 1-17.

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