BR112017024778B1 - PAGING METHOD, CENTRAL NETWORK DEVICE, BASE STATION AND USER EQUIPMENT - Google Patents

Abstract

PAGING METHOD, CENTRAL NETWORK DEVICE, BASE STATION AND USER EQUIPMENT. The present invention relates to a paging method, central network apparatus, base station and user equipment (UE). The method comprises: when a central network apparatus determines that the time for synchronization is approaching, determining, by the central network apparatus, reference frame information, wherein the reference frame information comprises a radio frame number, sending, by the central network apparatus, reference frame information to a base station in a paging area so that the base station synchronizes, according to the reference frame information, a radio frame at the base station. Embodiments of the present invention can reduce the possibilities in which a UE is unable to monitor paging messages.

Description

FIELD OF TECHNIQUE

[001] The present invention relates to the field of communication technologies and, in particular, to a paging method, user equipment, a base station and a central network device.

BACKGROUND

[002] Machine-to-Machine (M2M) is short for information and data exchange between machines in a wireless network, and is an important direction for the development of the next stage of mobile communications. M2M is widely applied to many fields that include intelligent transportation, a building control system, a smart home control system, a video surveillance system, industrial monitoring and the like.

[003] In an M2M system, when downlink data on a core network needs to be sent to user equipment (UE), a core network device starts a paging timer and sends, to each base station in a paging area, a paging message carrying a UE identifier (ID). When receiving the paging message, the base station in the paging area calculates, according to the UE identifier carried in the paging message, a closest paging occasion (OP) on an interface. , of the UE corresponding to the UE identifier and sends, when the OP arrives, the paging message to the UE corresponding to the UE identifier. The UE corresponding to the UE identifier initiates a random access process upon receipt of the paging message, to establish a connection with the base station and the core network. Downlink data is sent to the UE in the core network after the UE accesses the network. A paging moment depends on the paging superstructure (PSF) and the OP.

[004] To save UE power in an idle state, an extended discontinuous reception (eDRX) mechanism is introduced into the M2M system. The UE in the idle state listens to a paging channel in an eDRX manner. That is, the UE listens to the paging channel only when a paging moment of each eDRX active period arrives. If no paging message is obtained by listening, the UE enters a sleep state and wakes up when a next paging time arrives to listen to the paging channel. In this way, UE power consumption is reduced. Specifically, the UE maintains a UE-specific eDRX cycle and the UE reports the eDRX cycle to the core network device using a NAS message or in another manner. When transmitting a paging message, the core network device adds information such as the eDRX cycle and UE identifier to the paging message and transmits the paging message to a base station. The base station calculates a paging super frame (PSF) and a PO of the UE according to the information and sends the paging message at a paging time that is indicated by the PSF and the PO. The UE calculates the PSF and the PO according to information such as the UE's eDRX cycle and the UE identifier and receives the paging message at the paging time that is indicated by the PSF and the PO. The PSF and PO that are calculated by the UE must be the same as the PSF and PO that are calculated by each base station. The PSF is a superstructure that has a PO and the PO is a structure that is in the paging superstructure and has a paging message.

[005] It was found that the existing paging method has the following problems: in consideration of UE mobility, if the UE in the idle state moves between different cells, the UE may perform cell reselection before a paging time. of a current cell arrives, the UE may perform cell reselection before a paging time of a current cell arrives, a new cell is reselected, and a paging time of the new cell has passed when reselection is completed. In this way, the UE loses the paging time of the current cell, and also loses the paging time of the new cell. After cell reselection, the UE can receive the paging message only when the paging time of a next eDRX cycle arrives. In the M2M system, the eDRX cycle is long and can be up to one or more hours. After the new cell is reselected, the UE may need to wait almost one eDRX cycle before the next paging moment arrives. Due to the relatively long time waiting, the UE is very likely to perform cell reselection again in this period of time, and also misses an imminent paging moment of the current cell. After a new cell is reselected, the UE may also miss a paging moment of the new cell and so on. If the UE keeps moving, cell reselection may occur continuously during the hold. Consequently, the UE repeatedly fails to obtain a paging moment and cannot receive the paging message.

SUMMARY

[006] Embodiments of the present invention provide a paging method, UE, a base station and a central network device, so as to reduce problems that the UE cannot hear a paging message.

[007] To solve the above technical problem, embodiments of the present invention reveal the following technical solutions.

[008] According to a first aspect, an embodiment of the present invention provides a paging method, including: determining, by a central network device, reference frame information when the central network device determines that a synchronization occasion arrives , where the reference frame information includes a radio frame number; and sending, by the central network device, the reference frame information to a base station in a paging area, such that the base station synchronizes a radio frame at the base station in accordance with the reference frame information.

[009] With reference to the first aspect, in a first possible implementation of the first aspect, which the central network device determines that a synchronization occasion arrives includes: determining, by the central network device, that a new base station in the paging area connects the core network device; or determining, by the central network device, that a base station in the paging area restarts and then reconnects to the central network device; or determining, by the central network device, that a synchronization moment of each synchronization cycle arrives; or receiving, by the central network device, a synchronization request message sent by at least one base station in the paging area.

[0010] With reference to the first aspect and/or the first possible implementation of the first aspect, in a second possible implementation of the first aspect, the determination, by a central network device, of reference frame information includes: pre-storing, by the core network device, an initial radio frame number; calculating, by the central network device, an absolute time deviation between a current time and an initial moment, where the initial moment is an initial moment of a radio frame indicated by the radio frame number; and determining, by the central network device, the absolute time offset and the initial radio frame number as the reference frame information.

[0011] With reference to the first aspect and/or the first possible implementation of the first aspect, in a third possible implementation of the first aspect, the determination, by a central network device, of the reference frame information includes: pre-storing, by the core network device, an initial radio frame number; continuously updating, by the central network device, the stored radio frame number to a frame number of a current radio frame of the central network device according to a duration time of a radio frame; and reading, by the central network device, the radio frame number stored in the central network device.

[0012] With reference to the first aspect and/or the first possible implementation of the first aspect, in a fourth possible implementation of the first aspect, the reference frame information further includes a subframe number; and determining, by a central network device, a reference frame information includes: pre-storing, by the central network device, a radio frame number and starting subframe number; continuously update, by the central network device, the stored radio frame number to a frame number of a current radio frame and update the stored subframe number to a subframe number of a current subframe in the current radio frame accordingly with the time durations of a system paging frame and subframe; and reading, by the central network device, the radio frame number and the subframe number that are stored in the central network device.

[0013] With reference to the first aspect and/or the first possible implementation of the first aspect, in a fifth possible implementation of the first aspect, the determination, by a central network device, of a reference frame information includes: receiving, by central network device, frame information of a first base station that is sent by the first base station and determining the frame information of the first base station as the reference frame information, wherein the frame information includes: a reference frame number radio of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[0014] With reference to the first aspect and/or the first possible implementation of the first aspect, in a sixth possible implementation of the first aspect, the determination, by the central network device, of reference frame information includes: receiving, by the core network, frame information of a first base station that is sent by the first base station and determining the frame information of the first base station as the reference frame information, wherein the frame information includes: a frame number and a number of radio subframe of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[0015] With reference to the fifth possible implementation of the first aspect and/or the sixth possible implementation of the first aspect, in a seventh possible implementation of the first aspect, the determination, by a central network device, of the reference frame information includes: sending , by the central network device, a request for frame information to the first base station prior to receiving the frame information from the first base station.

[0016] With reference to the first aspect and/or the first possible implementation of the first aspect and/or the second possible implementation of the first aspect and/or the third possible implementation of the first aspect and/or the fourth possible implementation of the first aspect and/ or to the fifth possible implementation of the first aspect and/or to the sixth possible implementation of the first aspect and/or to the seventh possible implementation of the first aspect, in an eighth possible implementation of the first aspect, after sending, by the central network device, the information of frame to the base station, the method further includes: receiving, by the central network device, an acknowledgment message that is sent by the base station after the base station receives the frame information.

[0017] With reference to the first aspect and/or the first possible implementation of the first aspect and/or the second possible implementation of the first aspect and/or the third possible implementation of the first aspect and/or the fourth possible implementation of the first aspect and/ or to the fifth possible implementation of the first aspect and/or to the sixth possible implementation of the first aspect and/or to the seventh possible implementation of the first aspect and/or to the eighth possible implementation of the first aspect, in a ninth possible implementation of the first aspect, the method further includes: receiving, by the core network device, a UE eDRX cycle that is sent by the UE in a connected state and calculating a PF and a PO of the UE in accordance with the eDRX cycle; and when downlink data for the UE arrives and the UE is in an idle state, send, by the core network device, a paging message to the base station before a paging time that is indicated by the PF and the PO, of way that the base station sends the paging message to the UE.

[0018] With reference to the ninth possible implementation of the first aspect, in a tenth possible implementation of the first aspect, a time at which the core network device sends the paging message to the base station is closest to the paging time between a time in which PF and PO are calculated and the paging time.

[0019] With reference to the first aspect and/or the first possible implementation of the first aspect and/or the second possible implementation of the first aspect and/or the third possible implementation of the first aspect and/or the fourth possible implementation of the first aspect and/ or to the fifth possible implementation of the first aspect and/or to the sixth possible implementation of the first aspect and/or to the seventh possible implementation of the first aspect and/or to the eighth possible implementation of the first aspect, in an eleventh possible implementation of the first aspect, the The method further includes: receiving, by the central network device, a UE eDRX cycle that is sent by the UE in a connected state; when downlink data for the UE arrives and the UE is in an idle state, sending, by the core network device, a paging message to the base station, wherein the paging message includes the eDRX cycle of the UE; receiving, by the core network device, a first time slot sent by the base station, wherein the first time slot is sent by the base station when the base station calculates a PF and a PO of the UE according to the eDRX cycle and determines that a time interval between a current time and a paging time that is indicated by the EU PF and PO is greater than a preset time limit; and the first time interval is less than or equal to the time interval between the UE paging time and the current time; and sending, by the central network device, a paging message to the base station according to the first received time slot.

[0020] With reference to the eleventh possible implementation of the first aspect, in a twelfth possible implementation of the first aspect, sending, by the central network device, a paging message to the base station according to the first time slot received includes: for each base station, sending, by the central network device according to a first time slot sent by the base station, a paging message to the base station after the first time slot of the base station; or selecting, by the central network device, a first minimum time slot from the first time slots sent by the base stations, and sending a paging message to the base stations after the first minimum time slot.

[0021] With reference to the eleventh possible implementation of the first aspect, in a thirteenth possible implementation of the first aspect, sending, by the central network device, a paging message to the base station includes: immediately sending, by the base station device, core network, the paging message to the base station when determining that no paging message to the UE has been sent after the UE changes from the connected state to the idle state; or when determining that a paging message for the UE has been sent after the UE changes from the connected state to the idle state, determining, by the central network device according to a time at which the last paging message for the UE is sent and the eDRX cycle of the UE, a time to send a current paging message and send the paging message to the base station when the time to send the current paging message arrives.

[0022] With reference to the eleventh possible implementation of the first aspect, in a fourteenth possible implementation of the first aspect, sending, by the central network device, a paging message to the base station includes: immediately sending, by the base station device, core network, the paging message to the base station when determining that no paging message to the UE has been sent after the UE changes from the connected state to the idle state; or when determining that a paging message for the UE has been sent after the UE changes from the connected state to the idle state, determine, by the core network device in accordance with a pre-stored reference sending time and reference time interval and the eDRX cycle of the UE, a time to send a current paging message, and sending, by the core network device, the paging message to the base station when the time to send the current paging message arrives.

[0023] With reference to the fourteenth possible implementation of the first aspect, in a fifteenth possible implementation of the first aspect, the method further includes: each time the core network device sends the paging message, if the first time interval sent by the base station is received, update, by the central network device, the reference sending time using a time at which the paging message is sent, and update the reference time interval using the first received time interval.

[0024] With reference to the first aspect and/or the first possible implementation of the first aspect and/or the second possible implementation of the first aspect and/or the third possible implementation of the third aspect and/or the fourth possible implementation of the first aspect and/ or the fifth possible implementation of the first aspect and/or the sixth possible implementation of the first aspect and/or the seventh possible implementation of the first aspect and/or the eighth possible implementation of the first aspect, in a sixteenth possible implementation of the first aspect, the The method further includes: receiving, by the central network device, a UE eDRX cycle that is sent by the UE in a connected state; and immediately send, by the core network device, the paging message to the base station when downlink data for the UE arrives and the UE is in an idle state, and when the core network device determines that no paging message for the UE was sent after the UE changed from the connected state to the idle state; or when downlink data for the UE arrives and the UE is in an idle state, and when the core network device determines that the paging message for the UE was sent after the UE changed from the connected state to the idle state, determine, by the core network device according to a time at which the last paging message for the UE is sent, the eDRX cycle of the UE, and second time intervals corresponding to the last paging message sent to the UE, a time to send a current paging message, and send the paging message to the base station when the time to send the current paging message arrives, where the second time slots corresponding to the last paging message sent to the UE are: second time slots carried in paging response messages that are correspondingly sent back by the base stations when the central network device sends the last paging message to the UE; and the second time slots are used to indicate, to the core network device, UE paging times that are calculated by the base stations.

[0025] With reference to the sixteenth possible implementation of the first aspect, in a seventeenth possible implementation of the first aspect, the determination, by the core network device according to a time at which a last paging message to the UE is sent, of the UE's eDRX cycle, and the second time slots corresponding to the last paging message sent to the UE, a time to send a current paging message includes: selecting, by the core network device, a second time slot that has a minimum value of second time slots; and determine, by the central network device according to the following formula, the time to send the current paging message: Time to send the current paging message = Time at which the last paging message to the UE is sent + cycle M*eDRX + Second time interval that has the minimum value, where M is a natural number

[0026] According to a second aspect, an embodiment of the present invention provides a paging method, including: receiving, by a base station, reference frame information sent by a central network device, where the reference frame information includes a radio frame number; and synchronizing, by the base station, a radio frame at the base station in accordance with the reference frame information.

[0027] With reference to the second aspect, in a first possible implementation of the second aspect, the synchronization, by the base station, of a radio frame at the base station in accordance with the frame information includes: calculating, by the base station in accordance with an absolute time offset and a duration of a radio frame, a quantity of radio frames included in the absolute time offset and a remaining time offset; calculating, by the base station according to the remaining time offset and a duration of a subframe, a number of subframes included in the remaining time offset; and adding by the base station, a starting radio frame number and the quantity of radio frames to obtain a frame number of a current radio frame, and determining a subframe number of a current subframe in the current radio frame accordingly with the number of subframes.

[0028] With reference to the second aspect, in a second possible implementation of the second aspect, the synchronization, by the base station, of a radio frame at the base station in accordance with the frame information includes: updating, by the base station, a number of a current radio frame at the base station to the radio frame number loaded in the reference frame information.

[0029] With reference to the second aspect, in a third possible implementation of the second aspect, the frame information further includes a subframe number; and the synchronization, by the base station, of a radio frame at the base station in accordance with the frame information includes: updating, by the base station, a frame number of a current radio frame at the base station to the frame number of radio loaded in the reference frame information, and updating a subframe number of the current radio frame at the base station to the subframe number loaded in the reference frame information.

[0030] With reference to the second aspect and/or the first possible implementation of the second aspect and/or the second possible implementation of the second aspect and/or the third possible implementation of the second aspect, in a fourth possible implementation of the second aspect, the method further includes: sending, by the base station, an acknowledgment message for the reference frame information to the central network device.

[0031] With reference to the second aspect and/or the first possible implementation of the second aspect and/or the second possible implementation of the second aspect and/or the third possible implementation of the second aspect, in a fifth possible implementation of the second aspect, the method further includes: receiving, by the base station, a paging message sent by the central network device; calculating, by the base station, a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; and sending, by the base station, the paging message to the UE at a paging time that is indicated by the PF and the PO of the UE.

[0032] With reference to the second aspect and/or the first possible implementation of the second aspect and/or the second possible implementation of the second aspect and/or the third possible implementation of the second aspect, in a sixth possible implementation of the second aspect, the method further includes: receiving, by the base station, a paging message sent by the central network device; calculating, by the base station, a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; determining, by the base station, a first time interval when determining that a time interval between a current time and a paging time that is indicated by the PF and the PO is greater than a preset time threshold, and sending the first time interval determined for the core network device, where the first time interval is less than or equal to the time interval between the paging time and the current time; and receiving, by the base station, a paging message for the UE that is sent by the core network device according to the first time slot.

[0033] With reference to the sixth possible implementation of the second aspect, in a seventh possible implementation of the second aspect, prior to sending the first determined time slot to the central network device, the method further includes: obtaining, by the base station, a recommended cell list in the received paging message, and determining that the base station is a base station serving a cell listed in the recommended cell list; or obtain, by the base station, a recommended base station list in the received paging message, and determine that the base station is a base station listed in the recommended cell list.

[0034] With reference to the second aspect and/or the first possible implementation of the second aspect and/or the second possible implementation of the second aspect and/or the third possible implementation of the second aspect, in an eighth possible implementation of the second aspect, the method further includes: receiving, by the base station, a paging message sent by the central network device; calculating, by the base station, a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; and determining, by the base station, a second time interval according to a time interval between a current time and a paging time that is indicated by the PF and the PO, adding the second time interval to a paging response message , and send the paging response message to the central network device, where the second time slot is used to indicate, to the central network device, the paging time that is indicated by the PF and the PO.

[0035] With reference to the second aspect and/or the first possible implementation of the second aspect and/or the second possible implementation of the second aspect and/or the third possible implementation of the second aspect and/or the fourth possible implementation of the second aspect and/ or to the fifth possible implementation of the second aspect and/or to the sixth possible implementation of the second aspect and/or to the seventh possible implementation of the second aspect and/or to the eighth possible implementation of the second aspect, in a ninth possible implementation of the second aspect, before the receiving, by a base station, frame information sent by a central network device, the method further includes: sending, by the base station, a synchronization request message to the central network device when determining that a time between a moment current and a time at which last reference frame information is received exceeds a preset cycle value, where the synchronization request message is used to request the central network device to send current frame information.

[0036] According to a third aspect, a paging method is provided, including: calculating, by the user equipment, a PF and a PO of the user equipment when entering an inactive state; hibernate, by the user equipment, at a first moment before a paging moment that is indicated by the PF and the PO, and determine whether the user equipment performs cell reselection, where a time interval between the first moment and the paging time is greater than or equal to a time that is used by the user equipment to complete a cell reselection; and if cell reselection is to be performed, listening to a paging message on a paging channel of a reselected cell after cell reselection is completed; or if cell reselection is not performed, listen for a paging message on a current cell's paging channel, or enter a sleep state and wake up at paging time to listen for a paging message on a current cell channel. pagination of a current cell.

[0037] With reference to the third aspect, in a first possible implementation of the third aspect, the time interval between the first moment and the paging moment is greater than or equal to the sum of a time duration of a radio frame and the time that is used by the user equipment to complete cell reselection.

[0038] According to a fourth aspect, an embodiment of the present invention provides a central network device, including: a processor, configured to determine, by the central network device, reference frame information when determining that a synchronization occasion arrives , where the reference frame information includes a radio frame number; and a transmitter configured to send the reference frame information determined by the processor to a base station in a paging area, such that the base station synchronizes a radio frame at the base station in accordance with the reference frame information.

[0039] With reference to the fourth aspect, in a first possible implementation of the fourth aspect, the processor is specifically configured to: determine that a new base station in the paging area connects to the central network device; or determining that a base station in the paging area restarts and then reconnects to the central network device; or determine that a synchronization moment of each synchronization cycle arrives; or receiving a synchronization request message sent by at least one base station in the paging area.

[0040] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect, in a second possible implementation of the fourth aspect, the processor is specifically configured to: pre-store an initial radio frame number; calculating an absolute time deviation between a current time and an initial moment, where the initial moment is a starting moment of a radio frame indicated by the radio frame number; and determining the absolute time offset and the initial radio frame number as the reference frame information.

[0041] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect, in a third possible implementation of the fourth aspect, the processor is specifically configured to: pre-store an initial radio frame number; continuously updating stored radio frame number to a frame number of a current radio frame of the central network device according to a time duration of a radio frame; and read the radio frame number stored in the central network device.

[0042] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect, in a fourth possible implementation of the fourth aspect, the frame information further includes a subframe number; and the processor is specifically configured to: pre-store the radio frame number and initial subframe number; continually update the stored radio frame number to a frame number of a current radio frame and update the stored subframe number to a subframe number of a current subframe in the current radio frame according to the time durations of a paging frame and a system sub-frame; and read the radio frame number and radio subframe number that are stored in the core network device.

[0043] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect, in a fifth possible implementation of the fourth aspect, the core network device further includes: a receiver, configured to receive frame information from a first base station which is sent by the first base station, wherein the frame information includes: a radio frame number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area, where the processor is further configured to determine the frame information of the first base station as the reference frame information.

[0044] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect, in a sixth possible implementation of the fourth aspect, the core network device further includes: a receiver, configured to receive frame information from a first base station which is sent by the first base station, wherein the frame information includes: a frame number and a radio subframe number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area, where the processor is further configured to determine the frame information of the first base station as the reference frame information.

[0045] With reference to the fifth possible implementation of the fourth aspect and/or the sixth possible implementation of the fourth aspect, in a seventh possible implementation of the fourth aspect, the transmitter is further configured to send a frame information request to the first base station before the receiver receives the frame information from the first base station.

[0046] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect and/or the second possible implementation of the fourth aspect and/or the third possible implementation of the fourth aspect and/or the fourth possible implementation of the fourth aspect and/ or to the fifth possible implementation of the fourth aspect and/or to the sixth possible implementation of the fourth aspect and/or to the seventh possible implementation of the fourth aspect, in an eighth possible implementation of the fourth aspect, the core network device further includes: the receiver is configured to receive an acknowledgment message that is sent by the base station after the base station receives the frame information.

[0047] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect and/or the second possible implementation of the fourth aspect and/or the third possible implementation of the fourth aspect and/or the fourth possible implementation of the fourth aspect and/ or to the fifth possible implementation of the fourth aspect and/or to the sixth possible implementation of the fourth aspect and/or to the seventh possible implementation of the fourth aspect, and to the eighth possible implementation of the fourth aspect, in a ninth possible implementation of the fourth aspect, the device of core network further includes: the receiver is configured to receive a UE eDRX cycle that is sent by the UE in a connected state; the processor is further configured to calculate a PF and a PO of the UE according to the eDRX cycle; and the transmitter is further configured to: when downlink data for the UE arrives and the UE is in an idle state, send a paging message to the base station prior to a paging time that is indicated by the PF and the PO, of way that base station sends the paging message to the UE.

[0048] With reference to the ninth possible implementation of the fourth aspect, in a tenth possible implementation of the fourth aspect, a time at which the core network device sends the paging message to the base station is closest to the paging time between a time in which PF and PO are calculated and the paging time.

[0049] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect and/or the second possible implementation of the fourth aspect and/or the third possible implementation of the fourth aspect and/or the fourth possible implementation of the fourth aspect and/ or to the fifth possible implementation of the fourth aspect and/or to the sixth possible implementation of the fourth aspect and/or to the seventh possible implementation of the fourth aspect and/or to the eighth possible implementation of the fourth aspect, in an eleventh possible implementation of the fourth aspect, the core network device further includes: the receiver is configured to receive a UE eDRX cycle that is sent by the UE in a connected state; the transmitter is configured to: when downlink data for the UE arrives and the UE is in an idle state, send a paging message to the base station, where the paging message includes the eDRX cycle of the UE; the receiver is further configured to receive a first time slot sent by the base station, where the first time slot is sent by the base station when the base station calculates a PF and a PO of the UE according to the eDRX cycle and determines that a time interval between a current time and a paging time that is indicated by the PF and the PO of the UE is greater than a preset time limit; and the first time interval is less than or equal to the time interval between the UE's paging time and the current time; and the transmitter is further configured to send a paging message to the base station according to the first received time slot.

[0050] With reference to the eleventh possible implementation of the fourth aspect, in a twelfth possible implementation of the fourth aspect, the transmitter is specifically configured to: for each base station, send, in accordance with a first time slot sent by the base station , from a paging message to the base station after the first base station timeslot; or select a first minimum time slot from the first time slots sent by the base stations, and send a paging message to the base station after the first minimum time slot.

[0051] With reference to the eleventh possible implementation of the fourth aspect, in a thirteenth possible implementation of the fourth aspect, the transmitter is specifically configured to: immediately send the paging message to the base station when it is determined that no paging message for the UE was sent after the UE changed from the connected state to the idle state; or when it is determined that a paging message for the UE was sent after the UE changed from a connected state to the idle state, determine, according to a time at which the last paging message for the UE is sent and the cycle of eDRX of the UE, a time to send a current paging message, and send the paging message to the base station when the time to send the current paging message arrives.

[0052] With reference to the eleventh possible implementation of the fourth aspect, in a fourteenth possible implementation of the fourth aspect, the transmitter is specifically configured to: immediately send the paging message to the base station when it is determined that no paging message for the UE was sent after the UE switched from the connected state to the idle state; or when it is determined that a paging message for the UE was sent after the UE changed from the connected state to the idle state, determine, according to pre-stored reference sending time and reference time interval and the eDRX cycle of the UE, a time to send a current paging message, and send, by the core network device, the paging message to the base station when the time to send the current paging message arrives.

[0053] With reference to the fourteenth possible implementation of the fourth aspect, in a fifteenth possible implementation of the fourth aspect, the processor is further configured to: each time the paging message is sent, if the first time slot sent by the station base is received, update the reference sending time using a time at which the paging message is sent, and update the reference time interval using the first received time interval.

[0054] With reference to the fourth aspect and/or the first possible implementation of the fourth aspect and/or the second possible implementation of the fourth aspect and/or the third possible implementation of the fourth aspect and/or the fourth possible implementation of the fourth aspect and/ or to the fifth possible implementation of the fourth aspect and/or to the sixth possible implementation of the fourth aspect and/or to the seventh possible implementation of the fourth aspect and/or to the eighth possible implementation of the fourth aspect, in a sixteenth possible implementation of the fourth aspect , the core network device further includes: the receiver is configured to receive a UE eDRX cycle that is sent by the UE in a connected state; the processor is further configured to: when downlink data for the UE arrives and the UE is in an idle state, and when it is determined that a paging message for the UE has been sent after the UE changes from the connected state to the idle state, determine, according to a time at which the last paging message for the UE is sent, the eDRX cycle of the UE, and second time intervals corresponding to the last paging message sent to the UE, a time for sending a message current paging number; and the transmitter is further configured to: immediately send the paging message to the base station when downlink data for the UE arrives and the UE is in the idle state, and when it is determined that no paging message for the UE has been sent after the UE changes from the connected state to the inactive state; or when downlink data for the UE arrives and the UE is in the idle state; and how much it is determined that the paging message to the UE was sent after the UE changed from the connected state to the idle state; send the paging message to the base station when the time for sending the current paging message arrives, where the second time slots corresponding to the last paging message sent to the UE are: second time slots carried in paging response messages which are correspondingly sent back by the base stations when the central network device sends the last paging message to the UE; and the second time slots are used to indicate, to the core network device, UE paging times that are calculated by the base stations.

[0055] With reference to the sixteenth possible implementation of the fourth aspect, in a seventeenth possible implementation of the fourth aspect, the processor is specifically configured to select a second time slot that has a minimum value of the second time slots; and determine, according to the following formula, the time to send the current paging message: Time to send the current paging message = Time at which the last paging message to the UE is sent + M*eDRX cycle + Second time interval that has the minimum value, where M is a natural number

[0056] According to a fifth aspect, an embodiment of the present invention provides a base station, including: a receiver, configured to receive reference frame information sent by a central network device, wherein the reference frame information includes a radio frame number; and a processor configured to synchronize a radio frame at the base station in accordance with reference frame information received by the receiver.

[0057] With reference to the fifth aspect, in a first implementation of the fifth aspect, the processor is specifically configured to: calculate, according to an absolute time offset and a duration of a radio frame, a quantity of radio frames included in the absolute time deviation and a remaining time deviation; calculating, according to the remaining time offset and a duration of a subframe, a number of subframes included in the remaining time offset; and adding an initial radio frame number and the quantity of radio frames to obtain a frame number of a current radio frame, and determining a subframe number of a current subframe in the current radio frame according to the quantity of subframes.

[0058] With reference to the fifth aspect, in a second possible implementation of the fifth aspect, the processor is specifically configured to: update a frame number of a current radio frame at the base station to the radio frame number loaded in the radio frame information reference frame.

[0059] With reference to the fifth aspect, in a third possible implementation of the fifth aspect, the frame information further includes a subframe number; and the processor is specifically configured to: update a quarter number of a current radio frame at the base station to the radio frame number loaded in the reference frame information and update a subframe number of the current radio frame at the base station for the subframe number loaded in the reference frame information.

[0060] With reference to the fifth aspect and/or the first possible implementation of the fifth aspect and/or the second possible implementation of the fifth aspect and/or the third possible implementation of the fifth aspect, in a fourth possible implementation of the fifth aspect, the station base further includes: a transmitter, configured to send an acknowledgment message for the reference frame information to the central network device.

[0061] With reference to the fifth aspect and/or the first possible implementation of the fifth aspect and/or the second possible implementation of the fifth aspect and/or the third possible implementation of the fifth aspect, in a fifth possible implementation of the fifth aspect, the station base further includes: the receiver is further configured to receive a paging message sent by the central network device; the processor is further configured to calculate a PF and a UE PO in accordance with an eDRX cycle and a UE identifier that are carried in the paging message; and the transmitter is further configured to send the paging message to the UE at a paging time that is indicated by the PF and the PO of the UE.

[0062] With reference to the fifth aspect and/or the first possible implementation of the fifth aspect and/or the second possible implementation of the fifth aspect and/or the third possible implementation of the fifth aspect, in a sixth possible implementation of the fifth aspect, the station base further includes: the receiver is further configured to receive a paging message sent by the central network device; the processor is further configured to: calculate a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; and determining a first time interval when determining that a time interval between a current time and a paging time that is indicated by the PF and the PO is greater than a preset time limit; the transmitter is further configured to send the first determined time interval to the central network device, where the first time interval is less than or equal to the time interval between the paging moment and the current time; and the receiver is further configured to receive a paging message for the UE that is sent by the core network device according to the first time slot.

[0063] With reference to the sixth possible implementation of the fifth aspect, in a seventh possible implementation of the fifth aspect, the processor is further configured to: obtain a recommended cell list in the paging message received by the receiver, and determine that the base station is a base station serving a cell listed in the recommended cell list; or obtain a recommended base station list in the paging message received by the receiver, and determine that the base station is a base station listed in the recommended cell list.

[0064] With reference to the fifth aspect and/or the first possible implementation of the fifth aspect and/or the second possible implementation of the fifth aspect and/or the third possible implementation of the fifth aspect, in an eighth possible implementation of the fifth aspect, the station base further includes: the receiver is further configured to receive a paging message sent by the central network device; the processor is further configured to: calculate a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; and determining a second time interval according to a time interval between a current time and a paging time that is indicated by the PF and the PO; and the base station further includes: a transmitter, configured to add the second time slot to a paging response message, and send the paging response message to the central network device, where the second time slot is used to indicate, to the central network device, the paging time indicated by the PF and the PO.

[0065] With reference to the fifth aspect and/or the first possible implementation of the fifth aspect and/or the second possible implementation of the fifth aspect and/or the third possible implementation of the fifth aspect and/or the fourth possible implementation of the fifth aspect and/ or to the fifth possible implementation of the fifth aspect and/or to the sixth possible implementation of the fifth aspect and/or to the seventh possible implementation of the fifth aspect and/or to the eighth possible implementation of the fifth aspect, in a ninth possible implementation of the fifth aspect, the transmitter is further configured to send a synchronization request message to the central network device when the processor determines that a time between a current time and a time at which the last reference frame information is received exceeds a preset cycle value, where the synchronization request message is used to request the central network device to send current structure information.

[0066] According to a sixth aspect, an embodiment of the present invention provides user equipment, including: a processor, configured to calculate a PF and a PO of the user equipment when the user equipment enters an inactive state; and waking up the user equipment at a first moment before a paging moment that is indicated by the PF and the PO, and determining whether the user equipment performs cell reselection, where a time interval between the first moment and the paging time is greater than or equal to a time that is used by the user equipment to complete a cell reselection; and if cell reselection must be performed, complete the cell reselection; and a receiver, configured to: when the processor determines that cell reselection should be performed, listen for a paging message on a paging channel of a reselected cell; or when the processor determines that cell reselection should not be performed, listen for a paging message on a paging channel of a current cell, or enter a sleep state and wake up at paging time to listen for a paging message on a paging channel of a current cell.

[0067] With reference to the sixth aspect, in a first possible implementation of the sixth aspect, the time interval between the first moment and the paging moment is greater than or equal to a sum of the time duration of a radio frame and the time that is used by the user equipment to complete a cell reselection.

[0068] In embodiments of the present invention, the central network device determines the reference frame information when the central network device determines that the synchronization occasion arrives. The reference frame information includes the radio frame number. The central network device sends the reference frame information to the base station in the paging area, so that the base station synchronizes the radio frame at the base station according to the reference frame information. In this way, at least radio frame numbers are synchronous between the central network device and the base station, and a difference in time between the central network device and the base station is limited to the time duration of one radio frame, thereby reducing timing error between cells of different base stations as much as possible, and reducing, to a certain extent, problems that the UE still misses a paging moment of a new cell even if cell reselection is completed before a moment of pagination of a current cell.

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] To describe the technical solutions in the embodiments of the present invention more clearly, the following briefly describes the accompanying drawings required to describe the embodiments. Apparently, one of ordinary skill in the art can still derive other designs from these accompanying designs without creative efforts.

[0070] FIG. 1 shows an example of an application scenario according to an embodiment of the present invention.

[0071] FIG. 2 is a schematic flowchart of a paging method in accordance with an embodiment of the present invention;

[0072] FIG. 3 is another schematic flowchart of a paging method in accordance with an embodiment of the present invention;

[0073] FIG. 4 is another schematic flowchart of a paging method in accordance with an embodiment of the present invention;

[0074] FIG. 5 is another schematic flowchart of a paging method in accordance with an embodiment of the present invention;

[0075] FIG. 6 is another schematic flowchart of a paging method in accordance with an embodiment of the present invention.

[0076] FIG. 7 is another schematic flowchart of a paging method in accordance with an embodiment of the present invention;

[0077] FIG. 8 is a schematic structural diagram of a core network device in accordance with an embodiment of the present invention;

[0078] FIG. 9 is a schematic structural diagram of a base station in accordance with an embodiment of the present invention; It is

[0079] FIG. 10 is a schematic structural diagram of user equipment in accordance with an embodiment of the present invention.

DESCRIPTION OF MODALITIES

[0080] The inventors find that the reason why UE misses cell paging moments before and after reselection when cell reselection happens is that the base stations are out of synchronization in time. Although different base stations obtain the same PSF and PO from the same UE through calculation, due to the fact that the base stations are out of synchronization in time, a paging moment indicated by the same PSF and PO may correspond to different absolute time at different base stations . For example, it is assumed that a PSF1 and a PO 1 of UE 1 have indicated a paging time 1, the UE 1 is currently located in a cell of a base station A, and reselects a cell b of a base station B, the time paging time 1 of the UE arrives at an absolute time t1 in base station cell A, and paging time 1 of the UE arrives at an absolute time t2 in the cell of base station B. If t2<t1, even if the UE starts to perform cell reselection and reselect cell b before paging time 1 of cell to arrive, and a time at which the UE completes reselection is before t1, the UE loses paging time 1 of cell b as long as the time is after t2. Consequently, UE 1 needs to wait for a paging time from cell b in a next eDRX cycle. Furthermore, if UE 1 moves frequently and the above case repeats, UE 1 cannot obtain a paging message for a long time by listening, and cannot receive data that a core network intends to transmit.

[0081] In this way, embodiments of the present invention provide a paging method, in order to reduce problems that the UE cannot obtain a paging message by listening to the previous case.

[0082] To make one skilled in the art understand the technical solutions in the embodiments of the present invention better and to make the objectives, features and advantages of the embodiments of the present invention clearer, the following further describes the theoretical solutions in the embodiments of the present invention in detail with reference to the accompanying drawings.

[0083] The paging method in embodiments of the present invention can be applied to a paging scenario that is M2M, LTE and other communication systems and that satisfies the following conditions: an eDRX way is used and UE is mobile to a certain extent point. For example, FIG. 1 shows an example of a network structure to which a paging method according to an embodiment of the present invention is applied. The network structure includes: a core network device 110, base stations 120, cells 130 of base stations 120, and UE 140. The UE 140 is in one of the cells 130. The UE 140 is mobile to some extent and can move to another cell.

[0084] When this embodiment of the present invention is applied to M2M, in this embodiment of the present invention, the radio frame is a superframe in M2M, the subframe is a frame in the superframe, a core network device may be a GPRS support node ) (SGSN, Serving GPRS Support Node). When this embodiment of the present invention is applied to LTE, in this embodiment of the present invention, the radio frame is an LTE frame, the subframe is an LTE subframe, and a core network device may be a mobility management entity ( MME, Mobility Management Entity). An M2M super paging frame, an LTE paging frame, and another radio frame that has a PO are referred to as a paging frame (PF) in this embodiment of the present invention. The PF is a radio frame that has a PO, the PO is a subframe that is in the radio frame and that has a paging message, and a PF can include one or more POs.

[0085] With reference to FIG. 2, FIG. 2 is a schematic flowchart of a paging method in accordance with an embodiment of the present invention. The method includes the following steps.

[0086] Step 201: A central network device determines reference frame information when the central network device determines that a synchronization occasion arrives, where the reference frame information includes a radio frame number.

[0087] That the central network device determines that a synchronization occasion arrives may include: determining, by the central network device, that a new base station in a paging area connects to the central network device; or determining, by the central network device, that a base station in a paging area restarts and then reconnects to the central network device; or determining, by the central network device, that a synchronization moment of each synchronization cycle arrives; or receiving, by the central network device, a synchronization request message sent by at least one base station in a paging area.

[0088] A specific cycle length of the synchronization cycle is not limited in this embodiment of the present invention and the timing of synchronization in each synchronization cycle is not limited in this embodiment of the present invention, as long as the central network device sends the synchronization information reference frame.

[0089] In this step, the determination, by a central network device, of reference frame information may include: pre-storing, by the central network device, an initial radio frame number; calculating, by the central network device, an absolute time deviation between a current time and an initial moment, where the initial moment is an initial moment of a radio frame indicated by the radio frame number; and determining, by the central network device, the absolute time offset and the initial radio frame number as the reference frame information.

[0090] In this step, the determination, by the central network device, of reference frame information may include: pre-storing, by the central network device, an initial frame number; continuously updating, by the central network device, the stored radio frame number to a frame number of a current radio frame of the central network device according to a time duration of a radio frame; and reading, by the central network device, the radio frame number stored in the central network device.

[0091] For example, the initial radio frame number pre-stored in the core network device is assumed to be 0, the initial moment is 0, and the time duration of a radio frame is T. At a time T, the frame number of the current radio frame is 1, and the frame number 1 is used to update the stored radio frame number 0. In a 2T time, the frame number of the current radio frame is 2, and the frame number 2 is used to update the stored radio frame number 1, and so on. In this way, the stored radio frame number is updated in real time, and it is ensured that the stored radio frame number is always the frame number of the current radio frame.

[0092] The reference frame information may further include a subframe number. In this case, the determination, by a central network device, of reference frame information may include: pre-storing, by the central network device, a radio frame number and starting subframe number; continuously updating, by the central network device, the stored radio frame number to a frame number of a current radio frame and updating the stored subframe number to a subframe number of a current subframe in the current radio frame accordingly with the time durations of a system paging frame and subframe; and reading, by the central network device, the radio frame number and radio subframe number that are stored in the central network device.

[0093] For example, the initial radio frame number pre-stored in the core network device is assumed to be 0, the subframe number pre-stored in the core network device is 0, the initial moment is 0, the duration of time of a radio frame is T and each radio frame has 64 subframes. In a T/64 time, the frame number of the current radio frame is 0, the subframe number is 1, and the frame number 0 and subframe number is 1 are used to update the stored radio frame number 0 and the subframe number 0. In T/32 time, the frame number of the current radio frame is 0, the subframe number is 2, and the frame number 0 and subframe number 2 are used to update the number radio frame number 0 and subframe number 1, and so on. In this way, the stored radio frame number and radio subframe number are updated in real time, and it is ensured that the radio frame number and radio subframe number are always the frame number of the current radio frame number and subframe number. of the current subframe in the current radio frame.

[0094] In the above description, the central network device maintains current frame information of the central network device, and uses the maintained frame information as the reference frame information. Alternatively, the central network device may not maintain current frame information, but obtain, from a base station in the paging area, base station current frame information and use the base station's current frame information as the base station information. of reference frame.

[0095] For example, the determination, by a central network device, of reference frame information may include: receiving, by the central network device, frame information from a first base station that is sent by the first base station, and determining the frame information of the first base station as the reference frame information, wherein the frame information includes: a radio frame number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[0096] Alternatively, determination, by a central network device, of reference frame information may include: receiving, by the central network device, frame information from a first base station that is sent by the first base station, and determining of the frame information of the first base station as the frame information, wherein the frame information includes: a frame number and a radio subframe number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area. In the above two examples, the first base station may actively send frame information from the first base station to the central network device. During actual application, the first base station may alternatively send the frame information of the first base station to the central network device when the central network device sends a request. In this case, determination by a central network device of reference frame information may include: sending, by the central network device, a request for frame information to the first base station; and receiving, by the central network device, frame information from the first base station that is sent by the first base station, and determining the frame information from the first base station as the reference frame information, wherein the frame information includes: a radio frame number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[0097] Alternatively, determination, by a central network device, of reference frame information may include: sending, by the central network device, a request for frame information to the first base station/ and receiving, by the central network device, a request for frame information core network, frame information of the first base station that is sent by the first station, and determining the frame information of the first base station as the reference frame information, where the frame information includes: a frame number and a number of radio subframe of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[0098] Step 202: The central network device sends the reference frame information to a base station in a paging area, so that the base station synchronizes a radio frame at the base station according to the reference information. reference frame.

[0099] In this step, the central network device may send the reference frame information to all base stations in the paging area or may send the reference frame information to one or more base stations in the paging area. Specifically, this can be independently adjusted during actual application, and is not limited here. For example, when the synchronization occasion of the central network device is that a new base section connects to the central network device, the central network device may send the reference frame information only to the new base station or may send the reference frame information for all base stations in the paging area. Alternatively, when the synchronization occasion of the central network device is that a synchronization request message from a base station is received, at this stage, the central network device may send the reference frame information only to the sending base station. the synchronization request message or can send the reference frame information to all base stations in the paging area.

[00100] In this embodiment, the central network device sends current reference frame information from the central network device to the base station, so that the base station updates the radio frame at the base station according to the reference frame information. reference. The reference frame information includes the radio frame number. In this way, at least the radio frame numbers are synchronous between the central network device and the base station, and a time difference between the central network device and the base station is limited to the time duration of one radio frame. , thus decreasing a timing error between cells of different base stations as much as possible and reducing, to a certain extent, problems that the UE still misses a paging moment of a new cell even though cell reselection is completed before a paging time of a current cell.

[00101] With reference to FIG. 3, FIG. 3 is another schematic flowchart of a paging method in accordance with an embodiment of the present invention. The method includes the following steps.

[00102] Step 301: A base station receives reference frame information sent by a central network device, where the frame information includes a radio frame number.

[00103] Step 302: The base station synchronizes a radio frame at the base station according to the reference frame information.

[00104] Synchronization, by the base station, of a radio frame at the base station in accordance with reference frame information may include: updating, by the base station, a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information.

[00105] The frame information may further include a subframe number. Correspondingly, synchronization by the base station of a radio frame at the base station in accordance with reference frame information may include: updating, by the base station, a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information, and updating a subframe number of the current radio frame at the base station to the subframe number loaded in the reference frame information.

[00106] The frame information may further include an absolute time deviation between a current time and an initial time. Correspondingly, synchronization by the base station of a radio frame at the base station in accordance with reference frame information may include: determination by the base station of a frame number of a current radio frame and a subframe number of a current subframe in the current radio frame according to the absolute time offset and a starting radio frame number.

[00107] Specifically, the base station can calculate, according to the absolute time offset and a duration of a radio frame, a quantity of radio frames included in the absolute time offset and a remaining time offset, and calculate, according to the remaining time offset and a duration of a subframe, a number of subframes included in the remaining time offset; and adding the initial radio frame number and the number of radio frames to obtain the frame number of the current radio frame; and determining the subframe number of the current subframe in the current radio frame according to the number of subframes.

[00108] For example, the initial radio frame number is 1, Absolute time duration/Duration of a radio frame = 5, a remainder is x and x/Duration of a subframe = 3. The frame number of the radio frame current is 1+5=6 and if a subframe number of a subframe starts from 0, the subframe number of the current subframe is 2. If x cannot be divided exactly by the duration of a subframe, an obtained amount of subframes can be rounded up, rounded down, or rounded to get the number of subframes. For example, x/Duration of a subframe = 3.4, the subframe number can be rounded up to 4 or rounded down to 3 or rounded up to 3.

[00109] Alternatively, the base station may divide the absolute time deviation by the duration of a radio frame and round up a quotient to obtain the number of radio frames, and add the initial radio frame number and the amount of radio frames to obtain the frame number of the current radio frame; and determining that the subframe number of the current subframe in the current radio frame is 0.

[00110] For example, Absolute time duration/Duration of a radio frame = 5.x, and 5.x is rounded up to obtain that the number of radio frames is 6. Assuming that the number of radio frames initial is 0, the frame number of the current radio frame is 6, and the subframe number is 0.

[00111] In this embodiment, the base station receives the reference frame information sent by the central network device. The reference frame information includes the radio frame number. The base station synchronizes the radio frame at the base station according to the reference frame information. In this way, at least radio frame numbers are synchronous between the central network device and the base station, and a time difference between the central network device and the base station is limited to the time duration of one radio frame, thereby reducing a timing error between the cells of different base stations as much as possible, and reducing, to a certain extent, problems that the UE still misses a paging moment of a new cell even though cell reselection is completed before a paging moment. pagination of a current cell.

[00112] FIG. 4 is another schematic flow chart of a paging method in accordance with an embodiment of the present invention. The method includes the following steps.

[00113] Step 401: UE calculates a paging frame (PF) and a UE PO when entering an idle state.

[00114] Step 402: the UE wakes up at a first time before a paging time that is indicated by the PF and the PO and determines whether the UE performs cell reselection, where a time interval between the first time and the time of paging is greater than or equal to a time that is used by the UE to complete a cell reselection.

[00115] The time for cell reselection generally depends on a time for measuring a neighboring cell in a cell reselection process.

[00116] Step 403: If cell reselection is to be performed, listening for a paging message on a paging channel of a reselected cell after cell reselection is completed.

[00117] Step 404: If cell reselection is not to be performed, listen to a paging message on a paging channel of a current cell or enter a sleep state and wake up at the time of paging to listen to a paging channel on a paging channel of a current cell.

[00118] In this mode, the UE calculates the PF and the PO when entering the idle state, wakes up at the first moment before the paging memento that is indicated by the PF and the PO and determines whether the UE performs cell reselection. The time interval between the first time and the paging time is greater than or equal to the time that is used by the UE to complete a cell reselection. If cell reselection has to be performed, the UE listens to the paging message on the paging channel of the reselected cell after the cell reselection is completed.

[00119] If cell reselection is not to be performed, the UE listens to the paging message on the paging channel of the current cell or enters the sleep state and wakes up at the time of paging to listen to the paging channel on the paging channel of the current cell. In this way, it is ensured as much as possible that the UE completes cell reselection before the current cell paging time, in combination with the above synchronization of at least radio frame number between the core network device and the base station, thereby reducing, to some extent, problems that the UE still misses a paging time of a new cell even though cell reselection is completed before the paging time of the current cell.

[00120] FIG. 5 is a schematic flowchart of a paging method in accordance with an embodiment of the present invention. The method includes the following steps.

[00121] Step 501: a central network device determines reference frame information when each synchronization occasion arrives, where the reference frame information includes: a frame number and a radio subframe number; and sends the reference frame information to a base station.

[00122] The synchronization occasion may include as follows: a new base station in the paging area connects to the central network device; or a base station in the paging area reboots and then reconnects to the central network device; or a synchronization moment of each synchronization cycle arrives; or the central network device receives a synchronization request message sent by at least one base station in the paging area.

[00123] The central network device may determine, by setting a synchronization timer, that the synchronization time of the synchronization cycle arrives. Specifically, a synchronization timer time duration is equal to a synchronization cycle time duration. A specific time duration of the synchronization cycle is not limited in this embodiment of the present invention. When the synchronization timer expires, the synchronization moment arrives, and step 501 is triggered. The central network device resets the synchronization timer after sending the reference frame information.

[00124] The central network device may send the reference frame information using a newly defined S1 interface message or may add the reference frame information to a newly added IE in an existing message. If IE is added to the existing message, the message can be a signaling message or a data message sent by the core network device to the base station. This is not limited to this embodiment of the present invention. Furthermore, a bit may be reserved in the existing message to indicate whether the message carries frame information. If the message carries frame information, the IE is added to a part of the message.

[00125] Furthermore, the message carrying the reference frame information may further indicate whether the base station needs to feed back an acknowledgment message to an SGSN.

[00126] In this case, the synchronization occasion may further include that, in step 501, the central network device does not receive, within a preset time, any acknowledgment message sent by one or more base stations.

[00127] The synchronization request message may be a synchronization request message that is sent by the base station to the central network device when the base station determines that a time between a current time and a time at which the last information of frame is received exceeds a preset cycle value. The synchronization request message is used to request the central network device to send the reference frame information. The current moment here is a moment at which the base station performs the determination step. The base station may start a synchronization timer each time frame information is received. A time duration of the synchronization timer is the preset cycle value. When the synchronization timer expires and no frame information is received, the base station determines that the time between the current time and the time at which the last frame information is received exceeds the preset cycle value.

[00128] As for a method for determining frame of reference information by the central network device, refer to a detailed description in step 210. Details are not described here again.

[00129] Step 502: The base station receives the reference frame information, updates a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information, and updates a number of subframe of the current radio frame at the base station to the subframe number loaded in the reference frame information.

[00130] Step 503: the base station sends an acknowledgment message for the reference frame information to the central network device and the central network device receives, within a preset time, acknowledgment messages sent by the base stations.

[00131] The acknowledgment message may be a newly defined S1 interface message, or an IE carrying the acknowledgment message may be added to an existing control message or data message sent by the base station to the device core network.

[00132] That the base station sends the acknowledgment message may be negotiated and adjusted in advance between the base station and the central network device or may be indicated by the central network device to the base station using the message it carries. the frame information.

[00133] It can be arranged that if the central network device does not receive, within the preset time, any acknowledgment messages sent by one or more base stations, step 501 is triggered again until a preset maximum amount of delay times has elapsed. is reached or the acknowledgment message sent by the base station is received.

[00134] This step is an optional step.

[00135] Step 504: UE sends an eDRX cycle from the UE to the core network device in a connected state.

[00136] Step 505: The core network device calculates a PF and a PO of the UE according to the eDRX cycle.

[00137] The core network device can calculate the PF and PO of the UE according to the eDRX cycle and a UE identifier.

[00138] In step 504, if the eDRX cycle is sent by the UE to the base station and then carried forward by the base station to the central network device, the UE identifier may be added when the base station carries forward the eDRX cycle. eDRX.

[00139] In step 504, if the eDRX cycle is sent by the UE and transparently transmitted by the base station to the central network device, the UE identifier may be added when the UE sends the eDRX cycle.

[00140] Step 506: When downlink data for the UE arrives and the UE is in an idle state, the core network device sends a paging message to the base station prior to a paging time that is indicated by the PF and the PO, where the paging message includes the UE's eDRX cycle and a UE identifier.

[00141] A time at which the core network device sends the paging message to the base station is preferably closer to the paging time between the time at which the PF and PO are calculated and the paging time.

[00142] In step 504 to step 506, the core network device calculates the PF and PO of the UE, stores the paging message, and sends the paging message before the paging time that is indicated by the PF and PO. During actual application, a core network may not calculate the PF and PO of the UE. In this case, step 504 through step 506 may be replaced with the following steps.

[00143] Step A: The core network device receives a UE eDRX cycle which is sent by the UE in a connected state.

[00144] The central network device may store the eDRX cycle of the UE in the central network device.

[00145] Step B: When downlink data for the UE arrives and the UE is in an idle state, the core network device sends a paging message to the base station, where the paging message includes the UE's eDRX cycle .

[00146] Sending, by the core network device, a paging message to the base station may include: determining by the core network device whether a paging message to the UE has been sent after the UE changes from the connected state to the inactive state; and directly sending, by the central network device, the paging message to the base station if the central network device has not sent any paging message to the UE after the UE changes from the connected state to the idle state; or if the central network device has sent a paging message to the UE after the UE changes from the connected state to the idle state, determine, by the central network device according to a time at which a last paging message is sent and the UE eDRX cycle, a time for sending a current paging message and sending the paging message to the base station when the time for sending the current paging message arrives.

[00147] For example, the core network device sent a paging message 1 to the UE to the base stations after the UE changes from the connected state to the idle state, and a current to-be-sent paging message is a message paging message 2. Paging message 1 and paging message 2 are different paging messages rather than copies of the same paging message.

[00148] In this step, the core network device determines that the paging message 1 for the UE was sent after the UE changed from the connected state to the idle state, and the core network device calculates, according to a time at which a last paging message 1 is sent and the UE eDRX cycle and according to a formula: Time at which the last paging message 1 is sent + UE n*eDRX cycle, a time closest to a current time for send the paging message 2.

[00149] For example, the core network device has not sent any paging message to the UE for the base stations after the UE changes from the connected state to the idle state, and a to-be-sent paging message is the first message of paging sent to the base stations for the UE after the UE changes from the connected state to the idle state. In this step, the core network device determines that no paging message for the UE has been sent after the UE changes from the connected state to the idle state, and the core network device calculates a further time for sending the paging message, but directly sends the paging message to the base stations.

[00150] Alternatively, sending, by the core network device, a paging message to the base station may include: determining, by the core network device, whether a paging message to the UE has been sent after the UE changes state connected to idle state; and directly sending, by the core network device, the paging message to the base station if the core network device has not sent any paging message to the UE after the UE changes from the connected state to the idle state; or if the central network device has sent a paging message to the UE after it has sent a paging message to the UE after the UE changes from the connected state to the idle state, determine, by the central network device according to a pre-stored reference sending and reference time interval and the eDRX cycle of the UE, a time to send a current paging message, and send, by the central network device, the paging message to the base station when the time to send the current paging message to arrive. A specific calculation formula can be: Time to send the current paging message = Reference sending time + Reference time interval + m*eDRX, where m is a natural number and m preferably has such a value that the calculated time to send the current paging message exceeds the current time and is close to the current time.

[00151] The reference sending time and reference time interval that are stored in the central network device are updated continuously, and an update rule and method may include: each time the central network device sends the message paging, if a first time slot sent by the base station when the base station performed step c is received, update, by the central network device, the reference sending time using a time at which the paging message is sent, and updating the reference time interval using the first received interval.

[00152] Further, if the reference time slot is shared by all base stations, if the central network device receives first time slots sent by multiple base stations, the central network device may select a first time slot that has a minimum value to update the reference time range. If each base station corresponds to a reference time slot, the core network device may use a first time slot sent by a corresponding base station to update a reference time slot corresponding to the base station.

[00153] Step c: the base station receives the paging message, calculates a PF and a PO of the UE according to the eDRX cycle, and sends a first time slot to the core network device when determining that a time slot is time between a current time and a paging moment that is indicated by the PF and the PO of the UE is greater than a preset time limit, where the first time interval is less than or equal to the time interval between the paging moment UE paging and current time; and step d must be performed.

[00154] If the base station determines that the time interval between the paging time and the current time is less than the preset time limit, step 508 must be performed.

[00155] Not all base stations receiving the paging message need to send a first time slot to the central network device, and instead some base stations send a first time slot. Specifically, if a base station sends a first time slot can be independently adjusted during actual application, as long as at least one base station sends a first time slot when the time slot between the current time and the paging time is indicated by the PF and the PO of the UE is greater than the preset time limit.

[00156] In one possible implementation, the paging message may include a recommended cell list or a recommended base station list. If the paging message includes the recommended cell list, a base station serving a cell listed in the recommended cell list may send a first time slot to the central network device. If the paging message includes the recommended base station list, a base station listed in the recommended base station list may send a first time slot to the central network device.

[00157] Step d: the central network device receives the first time slot sent by the base station.

[00158] Step e: The core network device sends a paging message to the base station according to the first time slot received.

[00159] Sending, by the central network device, a paging message to the base station in accordance with the first received time slot may include: for each base station, sending, by the central network device in accordance with a first time slot sent by the base station, a paging message to the base station after the first base station time slot; or selecting, by the central network device, a first minimum time slot from the first time slots sent by base stations, and sending a paging message to the base stations after the first minimum time slot.

[00160] That is, if only one base station sends a first time slot, the core network device may send the paging message to the base station in the paging area after the base station's first time slot.

[00161] If at least two base stations send a first time slot, the core network device may select a minimum first time slot, and send the paging message to the base station in the paging area after the first time slot Minimum. Alternatively, the core network device may send the paging message to each base station according to the first time slot of each base station.

[00162] Optionally, after the core network device sends the paging message to the base station according to the first received time slot, the method includes: for a subsequent paging message to be sent to the terminal, calculating, by core network, a subsequent paging frame location of the terminal based on the first time slot sent by the base station, and the terminal paging eDRX cycle.

[00163] That is, before the base station reports the time interval, the core network stores the paging message for the terminal. For the subsequent paging message to be sent to the terminal, the core network may calculate the location of the terminal's subsequent paging frame based on the time interval that is sent back by the base station and the paging eDRX cycle of the terminal. A specific calculation formula can be: Location of the time slot paging frame that is sent back by the base station + eDRX cycle N*Paging.

[00164] When the core network device and the base station perform step a through step e, if at least two base stations send a first time slot in step e, the core network device selects a first minimum time slot, and sends the paging message to the base station in the paging area after the first minimum time interval. Because the core network device selects the first minimum time interval, for a specific base station, a time interval between the paging time that is indicated by the PF and the PO of the UE and a time at which the base station receives the paging message resent by the core network device may be even longer than the preset time limit. In this case, the base station may resend a first time slot to the central network device, until the time interval between the paging time and the time in which the base station receives the paging message sent by the paging device is reached. core network is less than the preset time limit, or a number of times that the base station continuously sends a first time slot to the core network device reaches a preset limit for the number of times. Then the base station performs step 507. The core network device may indicate, for each base station using a paging message, a limit for a number of times to the base station; or a limit to the number of times a base station can be preset at the base station.

[00165] Step 507: The base station receives the paging message and calculates the PF and PO of the UE according to the eDRX cycle and UR identifier that are carried in the paging message.

[00166] Step 508: the UE calculates, when entering the idle state, the PF and PO of the UE according to the eDRX cycle and the UE identifier, wakes up at a first moment before the paging moment that is indicated by PF and PO, determine whether the UE performs cell reselection and if cell reselection has to be performed, listen to a paging message on a paging channel of a reselected cell after cell reselection is finished; or if cell reselection is not to be performed, listen for a paging message on a paging channel of a current cell or enter a sleep state and wake up at the time of paging to listen for a paging channel on a paging channel of a current cell.

[00167] A time interval between the first time and the paging time is greater than or equal to a time that is used by the UE to finish a cell reselection.

[00168] If the frame information in step 501 includes only the radio frame number, the time interval between the first moment and the paging moment is preferably greater than or equal to a sum of a time duration of one radio frame and the time that is used by the UE to complete a cell reselection.

[00169] Step 507 and step 508 are not necessarily performed in a particular order, as long as the two steps are both performed before step 509.

[00170] Step 509: At the paging time that is indicated by the PF and the PO of the UE, a base station to which a cell in which the UE is located sends the paging message to the UE and the UE receives the paging message .

[00171] When the UE receives the paging message, the UE starts a random access process to establish a connection with the base station and the core network device, and the core network device sends the downlink data to the UE after the UE accesses a network. Details of this processing process are not described here.

[00172] In this embodiment, the core network device maintains a synchronous state of radio frames and subframes of base stations in the same paging area, so that paging moments of the UE in different paging cells are basically synchronous. Due to the fact that a paging time of a cell before reselection and a paging time of a cell after reselection are equal in time in the same paging area, in an eDRX mechanism, even if the UE performs cell reselection, the UE does not miss a paging time of a new cell, as long as cell reselection is completed before the paging time arrives.

[00173] The central network device stores the message and transmits the paging message to the base station before the paging time, in order to reduce the storage time of the paging message by the base station.

[00174] The UE wakes up at the first moment before the paging moment arrives to check whether it performs cell reselection, thus ensuring that the paging moment does not appear in a cell reselection process and preventing the UE from missing the paging moment .

[00175] FIG. 6 is a schematic flowchart of a paging method in accordance with an embodiment of the present invention. The method includes the following steps.

[00176] Step 601: a central network device determines reference frame information when each synchronization occasion arrives, where the reference frame information includes: a frame number and a radio subframe number; and sends the reference frame information to a base station.

[00177] To implement this step, refer to step 501. Details are not described here again.

[00178] Step 602: The base station receives the reference frame information, updates a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information, and updates a number of subframe of the current radio frame at the base station to the subframe number loaded in the reference frame information.

[00179] Step 603: the base station sends an acknowledgment message for the reference frame information to the central network device and the central network device receives, within a preset time, acknowledgment messages sent by the base stations.

[00180] The acknowledgment message may be a newly defined S1 interface message, or an IE carrying the acknowledgment message may be added to an existing control message or data message sent by the base station to the receiving device. core network.

[00181] That the base station sends the acknowledgment message may be negotiated and adjusted in advance between the base station and the central network device or may be indicated by the central network device to the base station using the message carrying the information of frame.

[00182] It can be arranged that if the core network device does not receive, within the preset time, any acknowledgment messages sent by one or more base stations, step 601 is triggered again until a preset maximum amount of times has elapsed. is reached or the acknowledgment message sent by the base station is received.

[00183] This step is an optional step.

[00184] Step 604: The core network device receives a UE eDRX cycle which is sent by the UE in a connected state.

[00185] The central network device may store the eDRX cycle of the UE in the central network device.

[00186] Step 605: When downlink data for the UE arrives and the UE is in an idle state, the core network device determines whether a paging message for the UE has been sent after the UE changes from the connected state to the idle state , and if no paging message for the UE has been sent, the core network device directly sends a paging message to the base station; or if a paging message for the UE has been sent, the core network device determines, according to a time at which a last paging message for the UE is sent and the eDRX cycle of the UE, a time to send a current paging message, and the core network device sends the paging message to the base station when the time to send the current paging message arrives.

[00187] The paging message includes a UE identifier.

[00188] For example, the core network device sent a paging message 1 to the UE to the base stations after the UE changes from the connected state to the idle state, and a current to-be-sent paging message is a message pagination 2.

[00189] In this step, the core network device determines that the paging message 1 for the UE was sent after the UE changed from the connected state to the idle state, and the core network device calculates, according to a time at which a last paging message 1 is sent and the UE eDRX cycle and according to the formula: Time at which the last paging message 1 is sent + UE n*eDRX cycle, a time closest to a current time for send the paging message 2.

[00190] For example, the core network device has not sent any paging message to the UE for the base stations after the UE changes from the connected state to the idle state, and a current to-be-sent paging message is the first paging message sent by the core network device to the base stations to the UE after the UE changes from the connected state to the idle state. In this step, the core network device determines that no paging message for the UE has been sent after the UE changes from the connected state to the idle state, and the core network device no longer calculates a time to send the paging message, and may immediately send the paging message to the base stations.

[00191] Step 606: The base station receives the paging message and calculates a PF and a PO of the UE according to the eDRX cycle, and the base station determines whether a time interval between a real time and a paging time which is indicated by the PF and PO of the UE is greater than a preset time limit; and if the time interval is greater than the preset time limit, send a first time interval to the central network device, where the first time interval is less than or equal to the time interval between the paging moment of the UE and the current time, and step 607 must be performed; or if the time interval is not greater than the preset time limit, step 609 must be performed.

[00192] In one possible implementation, the first time slot may be used to indicate, to the core network device, the paging moment of the UE that is calculated by the base station sending the first time slot. Specifically, when an information transmission latency and processing latency between the base station and the core network device are not considered, the first time interval may be equal to the time interval between the UE paging time and the current time , and the core network device can add the current time and the first time slot to obtain the paging time of the UE. If an information transmission latency and processing latency between the base station and the core network device are considered, the first time interval needs to be less than the time interval between the UE paging moment and the current time and can be specifically: Time interval between the UE paging time and the current time - Transmission latency - Processing latency, and the central network device can further add the current time and the first time interval to obtain the paging time UE paging.

[00193] A limit for the number of times to continuously send a first time slot to the central network device for the same paging message can be set for each base station. The limit for the number of times may be indicated by the central network device for each base station. For example, the limit for the number of times may be added to the paging message sent to the base station or may be preset at the base station. When the limit for the number of times is set for the base station, if the base station determines that the time interval between the current time and the paging time that is indicated by the PF and the PO of the UE is greater than the limit of preset time, for this paging message received by the base station, the base station further needs to determine whether a number of times that the base station continuously sends a first time slot to the central network device reaches the limit for number of times. If the limit for the number of times is reached, step 609 must be performed. If the limit for the number of times is not reached, step 607 must be performed.

[00194] Not all base stations receiving the paging message need to send a first time slot to the central network device, and otherwise some base stations send a first time slot. Specifically, whether a base station sends a first time slot can be independently adjusted during actual application, as long as at least one base station sends a first time slot when the time slot between the current time and the paging time that is indicated by the PF and the PO of the UE is greater than the preset time limit.

[00195] In one possible implementation, the paging message may include a recommended cell list or a recommended base station list. If the paging message includes the recommended cell list, a base station serving a cell listed in the recommended cell list may send a first time slot to the central network device. If the paging message includes the recommended base station list, a base station listed in the recommended base station may send a first time slot to the central network device.

[00196] For a base station that does not send a first time slot to the core network device, when the core network device sends the paging message in step 605, or when the core network device resends the paging message in step 608, the base station receives the paging message, and calculates the PF and PO of the UE according to the eDRX cycle. Then steps 609 and 610 must be performed.

[00197] Step 607: The core network device receives the first time slot sent by the base station.

[00198] Step 608: the core network device sends a paging message to the base station according to the first received time slot; and step 606 must be performed.

[00199] Sending, by the central network device, a paging message to the base station in accordance with the first received time slot may include: for each base station, sending, by the central network device in accordance with a first time slot sent by the base station, a paging message to the base station after the first base station time slot; or selecting, by the central network device, a first minimum time slot from the first time slots sent by base stations and sending a paging message to the base stations after the first minimum time slot.

[00200] That is, if only one base station sends a first time slot, the core network device sends the paging message to a base station in a paging area after the base station's first time slot; or if at least two base stations send a first time slot, the core network device may select a first minimum time slot and send the paging message to a base station in a paging area after the first minimum time slot; or the core network device may send the paging message to each base station according to the first time slot of each base station.

[00201] Optionally, after the core network device sends the paging message to the base station according to the first received time slot, the method includes: for a subsequent paging message sent to UE, calculating, by the network device central, a subsequent paging frame location of the UE based on the first time slot sent by the base station, and the eDRX cycle of the UE.

[00202] That is, before the base station reports the time slot, the core network stores the paging message for the UE. For the subsequent paging message sent to the UE, the core network may calculate the subsequent paging frame location of the UE based on the first time slot that is sent back by the base station and the eDRX cycle of the UE. A specific calculation formula can be: Paging frame location of the first time slot that is sent back by the base station + eDRX cycle N*Paging, where N is a natural number.

[00203] Step 609: the UE calculates, when entering the idle state, the PF and PO of the UE according to the eDRX cycle and the UE identifier, wakes up at a first moment before the paging moment that is indicated by PF and the PO and determine whether the UE performs cell reselection, and if cell reselection is to be performed, listens for a paging message on a paging channel of a reselected cell after cell reselection is completed; or if cell reselection is not to be performed, listen for a paging message on a paging channel of a current cell, or enter a sleep state and wake up at the time of paging to listen for a paging channel on a current cell channel. pagination of a current cell.

[00204] A time interval between the first time and the paging time is greater than or equal to a time that is used by the UE to complete cell reselection.

[00205] If the frame information in step 601 includes only the radio frame number, the time interval between the first moment and the paging moment is preferably greater than or equal to a sum of a time duration of one radio frame and the time that is used by the UE to complete a cell reselection.

[00206] Step 610: At the paging time that is indicated by the PF and the PO of the UE, a base station to which a cell where the UE is located sends the paging message to the UE and the UE receives the paging message.

[00207] When the UE receives the paging message, the UE starts a random access process to establish a connection with the base station and the core network device, and the core network device sends the downlink data to the UE after the UE accesses a network. Details of this processing process are not described here.

[00208] In this embodiment, the core network device maintains a synchronous state of radio frames and subframes of base stations in the same paging area, so that paging moments of the UE in different paging cells are basically synchronous. Because a paging time of a cell before reselection and a paging time of a cell after reselection are equal in time in the same paging area, in an eDRX mechanism, even if the UE performs cell reselection, the UE does not miss a paging time of a new cell, as long as cell reselection is completed before the paging time arrives.

[00209] The central network device stores the paging message and transmits the paging message to the base station before the paging time, so as to reduce the storage time of the paging message by the base station.

[00210] The UE wakes up at the first moment before the paging moment arrives to check whether to perform cell reselection, thus ensuring that the paging moment does not appear in a cell reselection process and preventing the UE from missing the paging moment .

[00211] With reference to FIG. 7, FIG. 7 is a schematic flowchart of a paging method in accordance with an embodiment of the present invention. The method includes the following steps.

[00212] Step 701: a central network device determines reference frame information when each synchronization occasion arrives, where the reference frame information includes: a frame number and a radio subframe number; and sends the reference frame information to a base station.

[00213] To implement this step, refer to step 501. Details are not described here again.

[00214] Step 702: The base station receives the reference frame information, updates a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information, and updates a number of subframe of the current radio frame at the base station to the subframe number loaded in the reference frame information.

[00215] Step 703: the base station sends an acknowledgment message for the reference frame information to the central network device and the central network device receives, within a preset time, acknowledgment messages sent by the base stations.

[00216] The acknowledgment message may be a newly defined S1 interface message, or an IE carrying the acknowledgment message may be added to an existing control message or data message sent by the base station to the receiving device. core network.

[00217] For the base station to send the acknowledgment message may be negotiated and adjusted in advance between the base station and the central network device or may be indicated by the central network device to the base station using the message carrying the frame information.

[00218] It can be arranged that if the central network device does not receive, within the preset time, any acknowledgment messages sent by one or more base stations, step 701 is triggered again until a preset maximum amount sending times is reached or the acknowledgment message sent by the base station is received.

[00219] This step is an optional step.

[00220] Step 704: The core network device receives a UE eDRX cycle that is sent by the UE in a connected state.

[00221] The central network device may store the eDRX cycle of the UE in the central network device.

[00222] Step 705: When downlink data for the UE arrives and the UE is in an idle state, the core network device determines whether a paging message for the UE has been sent after the UE changes from the connected state to the idle state , and if no paging message for the UE has been sent, the core network device directly sends a paging message to the base station and step 707 must be performed; or if a paging message for the UE was sent, step 706 must be performed.

[00223] Step 706: The core network device determines, according to a time at which the last paging message to the UE is sent, the eDRX cycle, and second time intervals corresponding to the last paging message sent to the UE, a time for sending a current paging message, and the core network device sends the paging message to the base station when the time for sending the current paging message arrives, and step 707 is to be performed.

[00224] The second time slots corresponding to the last paging message sent to the UE are: second time slots carried in paging response messages that are correspondingly sent back to the base stations when the central network device sends the last paging message to the UE.

[00225] The determination, by the core network device according to a time at which a last paging message to the UE is sent, the eDRX cycle, and the second time intervals corresponding to the last paging message sent to the UE , a time to send a current paging message may include: selecting, by the core network device, a second time slot that has a minimum value of the second time slots; and determine, by the central network device according to the following formula, the time for sending the current paging message: Time for sending the current paging message = Time at which the last paging message to the UE is sent + cycle of M*eDRX + Second time interval that has the minimum value, where M is a natural number and m preferably has such a value that the calculated time for sending the current paging message exceeds a current time and is closest to the current time.

[00226] If a transmission latency and a processing latency between the base station and a central network device are not considered for the second time slot that is fed back from the base station, the time that is calculated in the above formula for Sending the current paging message can be modified by subtracting the transmission latency and processing latency. If a transmission latency and a processing latency between the base station and the core network device are considered for the second time slot that is fed back from the base station, the time that is calculated in the above formula for sending the Current paging message does not need to be modified.

[00227] Step 707: The base station receives the paging message, calculates the PF and PO of the UE according to the eDRX cycle, and sends a paging response message to the core network device, where the message paging response time includes a second time slot and the second time slot is used to indicate, to the core network device, a paging time that is indicated by the PF and the PO of the UE.

[00228] If the transmission latency and processing latency between the base station and the core network device are not considered, the second time interval may be equal to the time interval between the current time and the paging time which is indicated by the PF and the PO of the UE. If the transmission latency and processing latency between the base station and the core network device were considered, the second time interval may be less than the time interval between the current time and the paging time that is indicated by the PF and the PO of the UE, and can be specifically: Time interval between the current time and the paging moment that is indicated by the PF and the PO of the UE - Transmission latency - Processing latency.

[00229] Step 708: the UE calculates, when entering the idle state, the PF and PO of the UE according to the eDRX cycle and a UE identifier, wakes up at a first moment before the paging moment that is indicated by PF and the PO and determine whether the UE performs cell reselection and whether cell reselection should be performed, listens for a paging message on a paging channel of a reselected cell after cell reselection is completed; or if cell reselection is not to be performed, listen for a paging message on a paging channel of a current cell, or enter a sleep state and wake up at the time of paging to listen for a paging channel on a paging channel of a current cell.

[00230] A time interval between the first time and the paging time is greater than or equal to a time that is used by the UE to complete a cell reselection.

[00231] If the frame information in step 701 includes only the radio frame number, the time interval between the first moment and the paging moment is preferably greater than or equal to a sum of a time duration of one radio frame and the time that is used by the UE to complete a cell reselection.

[00232] Step 709: At the paging time that is indicated by the PF and the PO of the UE, a base station to which a cell in which the UE is located sends the paging message to the UE and the UE receives the paging message .

[00233] When the UE receives the paging message, the UE starts a random access process to establish a connection with the base station and the core network device, and the core network device sends the downlink data to the UE after the UE accesses a network. Details of this processing process are not described here.

[00234] In this embodiment, the core network device maintains a synchronous state of radio frames and subframes of base stations in the same paging area, so that paging moments of the UE in different paging cells are basically synchronous. Due to the fact that a paging time of a cell before reselection and a paging time of a cell after reselection are equal in time in the same paging area, in an eDRX mechanism, even if the UE performs cell reselection, the UE does not miss a paging time of a new cell, as long as cell reselection is completed before the paging time arrives.

[00235] The central network device stores the message and transmits the paging message to the base station before the paging time, in order to reduce the storage time of the paging message by the base station.

[00236] The UE wakes up at the first moment before the paging moment arrives to check whether it performs cell reselection, thus ensuring that the paging moment does not appear in a cell reselection process and preventing the UE from missing the paging moment .

[00237] Corresponding to the above method, an embodiment of the present invention provides a central network device. With reference to FIG. 8, a central network device 800 includes: a processor 810, configured to determine, by the central network device, reference frame information when determining that a synchronization occasion arrives, wherein the reference frame information includes a frame number radio; and a transmitter 820, configured to send the reference frame information determined by the processor to the base station in a paging area, such that the base station synchronizes the radio frame at the base station in accordance with the reference frame information .

[00238] Optionally, the processor is configured to: determine that a new base station in the paging area connects to the central network device; or determining that a base station in the paging area restarts and then reconnects to the central network device; or determine that a synchronization moment of each synchronization cycle arrives; or receiving a synchronization request message sent by at least one base station in the paging area.

[00239] Optionally, the processor is specifically configured to: pre-store an initial radio frame number; calculate an absolute time deviation between a current time and an initial moment, where the initial moment is an initial moment of a radio frame indicated by the radio frame number; and determining the absolute time offset and the initial radio frame number as the reference frame information.

[00240] Optionally, the processor is specifically configured to: pre-store an initial radio frame number; continuously updating the stored radio frame number to a frame number of a current radio frame of the core network device according to a time duration of a radio frame; and reading the radio frame number stored in the central network device.

[00241] Optionally, the frame information further includes a subframe number; and the processor is specifically configured to: pre-store an initial radio frame number and subframe number; continually update the stored radio frame number to a frame number of a current radio frame and update the stored subframe number to a subframe number of a current subframe in the current radio frame according to the time durations of a system paging frame and subframe; and read the radio frame number and subframe number that are stored in the core network device.

[00242] Optionally, the core network device further includes: a receiver, configured to receive frame information from a first base station that is sent by the first base station, wherein the frame information includes: a radio frame number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[00243] The processor is further configured to determine the frame information of the first base station as the reference frame information.

[00244] Optionally, the core network device further includes: a receiver, configured to receive frame information from a first base station that is sent by the first base station, wherein the frame information includes: a frame number and a number of radio subframe of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area.

[00245] The processor is further configured to determine the frame information of the first base station as the reference frame information.

[00246] Optionally, the transmitter is further configured to send a request for frame information to the first base station before the receiver receives the frame information from the first base station.

[00247] Optionally, the core network device further includes: the receiver is configured to receive an acknowledgment message that is sent by the base station after the base station receives the frame information.

[00248] Optionally, the core network device further includes: the receiver is configured to receive a UE eDRX cycle that is sent by the UE in a connected state.

[00249] The processor is further configured to calculate a PF and a PO of the UE according to the eDRX cycle.

[00250] The transmitter is further configured to: when downlink data for the UE arrives and the UE is in an idle state, send a paging message to the base station prior to a paging time that is indicated by the PF and the PO , so that the base station sends the paging message to the UE.

[00251] Optionally, a time at which the core network device sends the paging message to the base station is closest to the paging time between a time at which the PF and PO are calculated and the paging time.

[00252] Optionally, the core network device further includes: the receiver is configured to receive a UE eDRX cycle that is sent by the UE in a connected state.

[00253] The transmitter is configured to: when downlink data for the UE arrives and the UE is in an idle state, send a paging message to the base station. The paging message includes the UE's eDRX cycle.

[00254] The receiver is further configured to receive a first time slot sent by the base station. The first time slot is sent by the base station when the base station calculates a PF and a PO of the UE according to the eDRX cycle and determines that a time slot between a real time and a paging time that is indicated by the PF and the PO of the UE is greater than a preset time limit. The first time interval is less than or equal to the time interval between the UE's paging time and the current time.

[00255] The transmitter is further configured to send a paging message to the base station according to the first received time slot.

[00256] Optionally, the transmitter is specifically configured to: for each base station, send, in accordance with a first time slot sent by the base station, a paging message to the base station after the first base station time slot; or select a first minimum time slot from the first time slots sent by the base stations, and send a paging message to the base stations after the first minimum time slot.

[00257] Optionally, the transmitter is specifically configured to: immediately send the paging message to the base station when it is determined that no paging message for the UE has been sent after the UE changes from the connected state to the idle state; or when it is determined that a paging message for the UE was sent after the UE changed from the connected state to the idle state, determine, according to a time at which the last paging message for the UE is sent and the eDRX cycle of the UE, a time to send a current paging message, and send the paging message to the base station when the time to send the current paging message arrives.

[00258] Optionally, the transmitter is specifically configured to: immediately send the paging message to the base station when it is determined that no paging message for the UE has been sent after the UE changes from the connected state to the idle state; or when it is determined that a paging message for the UE was sent after the UE changed from the connected state to the idle state, determine, in accordance with a pre-stored reference sending time and reference time interval and the cycle of eDRX of the UE, a time to send a current paging message and send, by the core network device, the paging message to the base station when the time to send the current paging message arrives.

[00259] Optionally, the processor is further configured to: each time the paging message is sent, if the first time slot sent by the base station is received, update the reference sending time using a time at which the paging message is sent. paging is sent, and update the reference time interval using the first received time interval.

[00260] Optionally, the core network device further includes: the receiver is configured to receive a UE eDRX cycle that is sent by the UE in a connected state.

[00261] The processor is further configured to: when downlink data for the UE arrives and the UE is in an idle state, and when it is determined that a paging message for the UE has been sent after the UE changes from the connected state to the idle state, determine, according to a time at which a last paging message for the UE is sent, the eDRX cycle of the UE, and second time intervals corresponding to the last paging message for the UE, a time to send a current paging message.

[00262] The transmitter is further configured to: immediately send the paging message to the base station when downlink data for the UE arrives and the UE is in the idle state, and when it is determined that no paging message for the UE has been sent after the UE changes from the connected state to the idle state; or when the downlink data for the UE arrives and the UE is in the idle state, and when it is determined that the paging message for the UE was sent after the UE changed from the connected state to the idle state, send the paging message to the base station when the time to send the current paging message arrives.

[00263] The second time slots corresponding to the last paging message sent to the UE are: second time slots carried in paging response messages that are correspondingly sent back by the base stations when the core network device sends the last message paging code for the UE.

[00264] The second time slots are used to indicate, to the central network device, UE paging times that are calculated by the base stations.

[00265] Optionally, the processor is specifically configured to select a second time slot that has a minimum value of the second time slots; and determine, according to the following formula, the time to send the current paging message: Time to send the current paging message = Time at which the last paging message to the UE is sent + M*eDRX cycle + Second time interval that has the minimum value, where M is a natural number.

[00266] In this embodiment, the central network device sends current reference frame information from the central network device to the base station, so that the base station updates the radio frame at the base station according to the reference frame information. reference. The reference frame information includes the radio frame number. In this way, at least the radio frame numbers are synchronous between the central network device and the base station, and a time difference between the central network device and the base station is limited to the time duration of one radio frame. , thereby reducing timing error between cells of different base stations as much as possible, and reducing, to a certain extent, problems that the UE still misses a paging moment of a new cell even though cell reselection is completed before a moment page number of a current cell.

[00267] An embodiment of the present invention further provides a base station. With reference to FIG. 9, base station 900 includes: a receiver 910, configured to receive reference frame information sent by a central network device, wherein the reference frame information includes a radio frame number; and a processor 920 configured to synchronize a radio frame at the base station in accordance with reference frame information received by the receiver.

[00268] Optionally, the processor is specifically configured to: calculate, according to an absolute time offset and a duration of a radio frame, a quantity of radio frames included in the absolute time offset and a remaining time offset; calculating, according to the remaining time offset and a duration of a subframe, a number of subframes included in the remaining time offset; and adding an initial radio frame number and the quantity of radio frames to obtain a frame number of a current radio frame, and determining a subframe number of a current subframe in the current radio frame according to the quantity of subframes.

[00269] Optionally, the processor is specifically configured to: update a frame number from a current radio frame at the base station to the radio frame number loaded in the reference frame information.

[00270] Optionally, the frame information further includes a subframe number; and the processor is specifically configured to: update a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information, and update a subframe number of the current radio frame at the base station to the subframe number loaded in the reference frame information.

[00271] Optionally, the base station further includes: a transmitter, configured to send an acknowledgment message for reference frame information to the central network device.

[00272] Optionally, the base station further includes: the receiver is further configured to receive a paging message sent by the central network device.

[00273] The processor is further configured to calculate a PF and a PO of the UE according to an eDRX cycle and a UE identifier that are carried in the paging message.

[00274] The transmitter is further configured to send the paging message to the UE at a paging time that is indicated by the PF and the PO of the UE.

[00275] Optionally, the base station further includes: the receiver is further configured to receive a paging message sent by the central network device.

[00276] The processor is further configured to: calculate a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; and determining a first time interval when determining that a time interval between a current time and a paging time that is indicated by the PF and PO is greater than a preset time limit.

[00277] The transmitter is further configured to send the first determined time slot to the central network device. The first time interval is less than or equal to the time interval between the paging time and the current time.

[00278] The receiver is further configured to receive a paging message for the UE that is sent by the central network device according to the first interval.

[00279] Optionally, the processor is further configured to: obtain a recommended cell list in the paging message received by the receiver and determine that the base station is a base station serving a cell listed in the recommended cell list; or obtain a recommended base station list in the paging message received by the receiver, and determine that the base station is a base station listed in the recommended cell list.

[00280] Optionally, the base station further includes: the receiver is further configured to receive a paging message sent by the central network device.

[00281] The processor is further configured to: calculate a PF and a UE PO according to an eDRX cycle and a UE identifier that are carried in the paging message; and determining a second time interval according to a time interval between a current time and a paging time that is indicated by the PF and the PO.

[00282] The base station further includes: a transmitter, configured to add the second time slot to a paging response message and send the paging response message to the central network device. The second time slot is used to indicate, to the central network device, the paging time that is indicated by the PF and the PO.

[00283] Optionally, the transmitter is further configured to send a synchronization request message to the central network device when the processor determines that a time between a current time and a time at which the last reference frame information is received exceeds a preset cycle value. The synchronization request message is used to request the central network device to send current frame information.

[00284] In this embodiment, the base station receives the reference frame information sent by the central network device. The reference frame information includes the radio frame number. The base station synchronizes the radio frame at the base station according to the reference frame information. In this way, at least radio frame numbers are synchronous between the central network device and the base station and a time difference between the central network device and the base station is limited to the duration of time in the radio frame, in this way decreasing the timing error between cells of different base stations as much as possible, and reducing, to a certain extent, problems that the UE still misses a paging moment of a new cell even though cell reselection is completed before a paging moment of a current cell.

[00285] An embodiment of the present invention further provides user equipment. As shown in FIG. 10, user equipment 1000 includes: a processor 1010, configured to calculate a PF and a PO of the user equipment when the user equipment enters an inactive state; and wakes up the user equipment at a first moment before a paging moment that is indicated by the PF and the PO and determines whether the user equipment performs cell reselection, where a time interval between the first moment and the paging moment is greater than or equal to a time that is used by the user equipment to complete a cell reselection; and if cell reselection must be performed, complete cell reselection; and a receiver 1020, configured to: when the processor determines that cell reselection should be performed, listen for a paging message on a paging channel of a reselected cell; or when the processor determines that cell reselection should not be performed, listens for a paging message on a paging channel of a current cell, or enters a sleep state and wakes up at paging time to listen for a paging message on a paging channel of a current cell.

[00286] Optionally, the time interval between the first moment and the paging moment is greater than or equal to a sum of a time duration of a radio frame and the time that is used by the user equipment to complement a cell reselection.

[00287] In this embodiment, the UE calculates the PF and the PO when entering the idle state, wakes up at the first moment before the paging moment that is indicated by the PF and the PO and determines whether the UE performs cell reselection. The time interval between the first time and the paging time is greater than or equal to the time that is used by the UE to complete a cell reselection. If cell reselection has to be performed, the UE listens to the paging message on the paging channel of the reselected cell after cell reselection is completed.

[00288] If cell reselection is not to be performed, the UE listens to the paging message on the paging channel of the current cell or enters the sleep state and wakes up at the time of paging to listen to the paging channel on the paging channel of the current cell. current cell. In this way, it is ensured as much as possible that the UE completes cell reselection before the current cell paging time, in combination with the above synchronization of at least radio frame numbers between the central network device and the base station, thereby way reducing, to some extent, problems that the UE still misses a paging time of a new cycle even though cell reselection is completed before the paging time of the current cell.

[00289] One skilled in the art can clearly understand that technologies in embodiments of the present invention can be implemented by software in addition to a necessary general hardware platform. Based on such an understanding, technical solutions in embodiments of the present invention essentially or in part contributing to the prior art can be implemented in a form of a software product. The software product is stored on a storage medium such as a ROM/RAM, a magnetic disk, or an optical disk and includes various instructions for instructing a computer device (which may be a personal computer, a server, a network or similar) to carry out the methods described in the embodiments or some parts of the embodiments of the present invention.

[00290] The embodiments in the present application are all described in a progressive manner, for the same or similar parts in the embodiments, references may be made to these embodiments, and each embodiment focuses on a difference from the other embodiments. Especially, a system embodiment is basically similar to a method embodiment, and in this way is described briefly. For related parts, refer to partial descriptions in the method modality.

[00291] The above descriptions are implementations of the present invention, but are not intended to limit the scope of protection of the present invention. Any modification, equivalent substitution and improvement made without departing from the principle of the present invention must fall within the scope of protection of the present invention.

Claims (21)

1. Paging method, characterized by the fact that it comprises: determining (201), by a central network device, reference frame information when the central network device determines that a synchronization occasion arrives, where the reference frame information reference comprises a radio frame number; and sending (202), by the central network device, reference frame information to a base station in a paging area, such that the base station synchronizes a radio frame at the base station in accordance with the reference frame information ; the method further comprising: receiving, by the core network device, an extended discontinuous reception cycle (eDRX) from user equipment (UE) that is sent by the UE in a connected state, and calculating a paging frame (PF) and an occasion paging (PO) of the UE according to the eDRX cycle; and when downlink data for the UE arrives and the UE is in an idle state, send, by the core network device, a paging message to the base station prior to a paging time that is indicated by the PF and the PO, so that the base station sends the paging message to the UE. 2. The method of claim 1, wherein the core network device determining that a synchronization occasion arrives comprises: determining, by the core network device, that a new base station in the paging area connects the core network; or determining, by the central network device, that a base station in the paging area restarts and then reconnects to the central network device; or determining, by the central network device, that a synchronization moment of each synchronization cycle arrives; or receiving, by the central network device, a synchronization request message sent by at least one base station in the paging area. 3. Method according to claim 1 or 2, characterized by the fact that determining, by a central network device, the reference frame information comprises: pre-storing, by the central network device, a reference frame number home radio; calculating, by the central network device, an absolute time deviation between a current time and an initial moment, where the initial moment is an initial moment of a radio frame indicated by the radio frame number; and determining, by the central network device, the absolute time deviation and initial radio frame number as the reference frame information. 4. Method according to claim 1 or 2, characterized by the fact that determining, by a central network device, reference frame information comprises: pre-storing, by the central network device, a frame number initial radio; continuously updating, by the central network device, the stored radio frame number to a frame number of a current radio frame of the central network device according to a time length of a radio frame; and reading, by the main network device, the radio frame number stored in the main network device. 5. Method according to claim 1 or 2, characterized in that the reference frame information further comprises an auxiliary frame number; and determining, by a central network device, the reference frame information comprises: pre-storing, by the central network device, an initial radio frame number and subframe number; continuously update, by the central network device, the stored radio frame number to a frame number of a current radio frame and update the stored subframe number to a current subframe number in the current radio frame according to lengths of time of a paging system frame and an auxiliary frame; and reading, by the main network device, the radio frame number and the subframe number that are stored in the main network device. 6. Method according to claim 1 or 2, characterized by the fact that determining, by a central network device, reference frame information comprises: receiving, by the central network device, frame information from a first base station that is sent by the first base station and determining the frame information of the first base station as the reference frame information, wherein the frame information comprises: a radio frame number of the first base station when the first base station sends frame information; and the first base station is a base station in the paging area. 7. Method according to claim 1 or 2, characterized by the fact that determining, by a central network device, reference frame information comprises: receiving, by the central network device, frame information from a first base station that is sent by the first base station and determining the frame information of the first base station as the reference frame information, wherein the frame information comprises: a radio frame number and a subframe number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area. 8. Method according to claim 6 or 7, characterized by the fact that determining, by a central network device, the reference frame information further comprises: sending, by the central network device, a request for frame information to the first base station before receiving the frame information from the first base station. 9. Method according to any one of claims 1 to 8, characterized by the fact that after sending, by the main network device, the frame information to a base station, the method further comprises: receiving, by the network device central, a reception confirmation message that is sent by the base station after the base station receives the frame information. 10. Central network device, characterized by the fact that it comprises: a processor (810), configured to determine, by the central network device, reference frame information when determining that a synchronization occasion arrives, where the reference frame information reference includes a radio frame number; and a transmitter (820) configured to send the reference frame information determined by the processor (810) to a base station in a paging area, such that the base station synchronizes a radio frame at the base station in accordance with the frame of reference information; and a receiver, configured to receive an extended discontinuous receive cycle (eDRX) from user equipment (UE) that is sent by the UE in a connected state; the processor (810) is further configured to calculate a paging frame (PF) and a paging occasion (PO) of the UE in accordance with the eDRX cycle; and the transmitter (820) is further configured to: when downlink data for the UE arrives and the UE is in an idle state, send a paging message to the base station prior to a paging time that is indicated by the PF and the PO, so that the base station sends the paging message to the UE. 11. The core network device of claim 10, wherein the processor (810) is specifically configured to: determine that a new base station in the paging area connects to the core network device; or determining that a base station in the paging area restarts and then reconnects to the central network device; or determine that a synchronization moment of each synchronization cycle arrives; or receiving a synchronization request message sent by at least one base station in the paging area. 12. The core network device of claim 10, wherein the processor (810) is specifically configured to: pre-store an initial radio frame number; calculating an absolute time deviation between a current time and an initial moment, where the initial moment is a starting moment of a radio frame indicated by the radio frame number; and determining the absolute time offset and the initial radio frame number as the reference frame information. 13. The core network device of claim 10 or 11, wherein the processor (810) is specifically configured to: pre-store an initial radio frame number; continuously updating the stored radio frame number to a frame number of a current radio frame of the core network device according to a time duration of a radio frame; and read the radio frame number stored in the central network device. 14. The core network device of claim 10 or 11, wherein the frame information further comprises a subframe number; and the processor (810) is specifically configured to: pre-store the radio frame number and initial subframe number; continually update the stored radio frame number to a frame number of a current radio frame and update the stored subframe number to a subframe number of a current subframe in the current radio frame according to the time durations of a paging frame and a system subframe; and read the radio frame number and radio subframe number that are stored in the core network device. 15. The core network device of claim 10 or 11, further comprising: the receiver is further configured to receive frame information from a first base station that is sent by the first base station, wherein the frame information frame includes: a radio frame number of the first base station when the first base station sends the frame information; and the first base station is a base station in the paging area, where the processor (810) is further configured to determine the frame information of the first base station as the reference frame information. 16. Base station, characterized by the fact that it comprises: a receiver (910), configured to receive reference frame information sent by a central network device, wherein the reference frame information comprises a radio frame number; and a processor (920) configured to synchronize a radio frame at the base station in accordance with reference frame information received by the receiver (910); the receiver (910) is further configured to receive a paging message sent by the central network device; the processor (920) is further configured to calculate a paging frame (PF) and a user equipment (UE) paging occasion (PO) in accordance with an extended discontinuous receive cycle (eDRX) and a UE identifier that are carried in the paging message; and a transmitter, configured to send the paging message to the UE at a paging time that is indicated by the PF and the PO of the UE. 17. Base station according to claim 16, characterized by the fact that the processor (920) is specifically configured to: calculate, according to an absolute time offset and a duration of a radio frame, a number of radio frames radio comprised in the absolute time deviation and a remaining time deviation; calculating, according to the remaining time offset and a duration of a subframe, a number of subframes included in the remaining time offset; and adding an initial radio frame number and the quantity of radio frames to obtain a frame number of a current radio frame, and determining a subframe number of a current subframe in the current radio frame according to the quantity of subframes. 18. The base station of claim 16 or 17, wherein the processor (920) is specifically configured to: update a frame number of a radio frame current at the base station to the loaded radio frame number in the frame of reference information. 19. Base station according to claim 16 or 17, characterized by the fact that the frame information further comprises a subframe member; and the processor (920) is specifically configured to: update a frame number of a current radio frame at the base station to the radio frame number loaded in the reference frame information and update a subframe number of the current radio frame at the base station to the subframe number loaded in the reference frame information. 20. The base station of any one of claims 16 to 17, further comprising: the transmitter is further configured to send an acknowledgment message for reference frame information to the central network device. 21. Computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the method as defined in claim 1.