WO2017177402A1

WO2017177402A1 - Communication handover methods, user equipment and base stations

Info

Publication number: WO2017177402A1
Application number: PCT/CN2016/079185
Authority: WO
Inventors: Yun HOU; Eddy Chiu
Original assignee: Huizhou Tcl Mobile Communication Co.,Ltd
Priority date: 2016-04-13
Filing date: 2016-04-13
Publication date: 2017-10-19
Also published as: CN109479218B; CN109479218A

Abstract

A communication handover method is disclosed. The method includes measuring, by a piece of user equipment (UE), candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results, wherein each VC includes multiple TPs that share a common physical cell identifier (PCI); selecting, by the UE, a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results; and accessing, by the UE, to the target VC and target TP. A piece of UE and a base station are further disclosed. Thus, both the physical layer and the virtual layer can be transferred when the UE is transferred to the VC.

Description

COMMUNICATION HANDOVER METHODS, USER EQUIPMENT AND BASE STATIONS

FIELD OF THE DISCLOSURE

The present disclosure relates to communication technologies, and more particularly, to communication handover methods, user equipment, and base stations.

BACKGROUND OF THE DISCLOURE

The ultra-dense network (UDN) has been considered as a promising candidate for future 5G networks to meet the explosive data demand and mobile services. The UDN can effectively improve the network throughput and resource efficiency. Small cells may be densely deployed in a UDN, though this may be conducive to enhance the network capacity, it could cause excessive handovers of user equipment (UE) when the UE moves across different small cells, which may thus increase the consumption of the UE's battery energy and the network resources.

Cell virtualization is thus introduced to address the above issue. Cell virtualization includes two layers of networks, the virtual layer network and the physical layer network. A virtual cell (VC) may include multiple transmission points (TPs) that share a common physical cell identifier (PCI) . The VC corresponds to the virtual layer network and is responsible for the control plane to provide a wide coverage, while the TPs correspond to the physical layer network and are responsible for the user plane to transmit user data to the UE. Handover is not required when the UE moves around within a same VC, and the UE may typically connect to the nearest TP so a high data throughput is expected.

When the UE moves across different VCs, handover is required, in which case the UE needs to not only access to another VC on the virtual layer, but connect to a new TP on the physical layer. However, the handover in the prior art occurs only on a single layer.

SUMMARY OF THE DISCLOSURE

A principal technical problem to be addressed by the disclosure is to provide communication handover methods, user equipment, and base stations to solve the issue in the prior art that the handover only occurs on a single layer.

One technical solution adopted by the disclosure is to provide a communication handover method. The method includes: measuring, by a piece of user equipment (UE) , candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results, wherein each VC includes multiple TPs that share a common physical cell identifier (PCI) ； selecting, by the UE, a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and accessing, by the UE, to the target VC and target TP.

The block of the UE measuring the candidate VCs and candidate TPs and accordingly selecting the target VC and target TP may include: measuring, by the UE, the candidate VCs to obtain VC measurement results； selecting, by the UE, the target VC from the candidate VCs according to the VC measurement results； measuring, by the UE, the candidate TPs in the target VC to obtain TP measurement results； and selecting, by the UE, the target TP from the candidate TPs in the target VC according to the TP measurement results.

The block of the UE measuring the candidate VCs may include: measuring the candidate VCs when the UE is connected to an edge TP of a source VC (currently attached VC) .

The block of the UE measuring the candidate VCs may include: measuring the neighboring VCs of the edge TP when the UE is connected to this edge TP.

The method may further include, between the block of the UE selecting the target VC from the candidate VCs and the block of measuring the candidate TPs within the target VC: transmitting, by the UE, the target VC information to a base station of the source VC； and receiving, by the UE, measurement configuration information of the candidate TPs in the target VC, which is sent from the base station of the source VC based on the target VC information.

The candidate TPs measurement configuration information of the target VC may include a set of edge TPs within the target VC, and the UE may measure the edge TPs according the edge TPs set. The edge TPs set may be sent from a base station of the target VC to the base station of the source VC.

The edge TPs set may include at least one OFF TP, and the candidate TPs measurement configuration information of the target VC may further include discovery reference signal (DRS) timing information, which indicates the time the OFF TP sends the DRS.

The block of the UE measuring the candidate VCs may include: receiving, by the UE, cell reference signals (CRSs) from the candidate VCs； and detecting the signal strength and/or signal quality of the CRSs from the candidate VCs, wherein the CRS of a candidate VC is acquired by aggregation of reference signals transmitted by all ON TPs within this candidate VC.

Another technical solution adopted by the disclosure is to provide a communication handover method. The method includes: transmitting, by a base station, candidate virtual cells (VCs) measurement configuration information and candidate transmission points (TPs) measurement configuration information to a piece of user equipment (UE) , which thus measures the candidate VCs and the candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC may include multiple TPs that share a common physical cell identifier (PCI) ； and enabling, by the base station, the UE to access to the target VC and target TP.

The block of the base station transmitting the candidate VCs measurement configuration information and candidate TPs measurement configuration information to the UE, which thus measures the candidate VCs and candidate TPs and further selects the target VC and target TP may include: transmitting, by the base station, the candidate VCs measurement configuration information to the UE, which thus may measure the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and may further select the target VC from the candidate VCs according to the VC measurement results； receiving, by the base station, the target VC information from the UE； transmitting, by the base station, the candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE may measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and may further select the target TP from the candidate TPs within the target VC according to the TP measurement results； and receiving, by the base station, the target TP information from the UE.

The block of the base station transmitting the candidate VCs measurement configuration information to the UE may include: transmitting, by the base station, the candidate VCs measurement configuration information, to the UE when the UE is connected to an edge TP of a corresponding VC (source VC) of the base station.

The candidate VCs measurement configuration information may include the neighboring VCs of this edge TP connected to the UE.

The candidate TPs measurement configuration information of the target VC may include a set of the edge TPs within the target VC, wherein the edge TPs set is received by the base station from a base station of the target VC.

The edge TPs set may include at least one OFF TP, and the candidate TPs measurement configuration information of the target VC may further include discovery reference signal (DRS) timing information, where the DRS is a reference signal transmitted by an OFF TP, and the DRS timing information indicates the time the OFF TP sends the DRS.

The block of the base station enabling the UE to access to the target VC and target TP may include: initiating, by the base station, a handover request to the base station of the target VC, and sending the target TP information to the base station of the target VC.

Yet another technical solution adopted by the disclosure is to provide a piece of user equipment (UE) . The UE includes: a measurement module configured to measure candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results, wherein each VC includes multiple TPs that share a common physical cell identifier (PCI) ； a selection module configured to select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and an access module configured to access to the target VC and the target TP.

The measurement module may include a VCs measurement unit configured to measure the candidate VCs to obtain VC measurement results； a TPs measurement unit configured to measure the candidate TPs in the target VC to obtain TP measurement results. The selection module may include a VC selection unit configured to select the target VC from the candidate VCs according to the VC measurement results； and a TP selection unit configured to select the target TP from the candidate TPs according to the TP measurement results.

The VCs measurement unit may be configured to measure the neighboring VCs of an edge TP when the UE is connected to the edge TP of a source VC (currently attached VC) .

The UE may further include a transmission module configured to transmit the target VC information to a base station of the source VC； and a reception module configured to receive the candidate TPs measurement configuration information of the target VC, which is sent from the base station of the source VC based on the target VC information.

Still another technical solution adopted by the disclosure is to provide a base station. The base station includes: a configuration module configured to transmit candidate virtual cells (VCs) measurement configuration information and candidate transmission points (TPs) measurement configuration information to a piece of user equipment (UE) , which thus measures the candidate VCs and the candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC may include multiple TPs that share a common physical cell identifier (PCI) ； and a handover module configured to enable the UE to access to the target VC and target TP.

The configuration module may include a first transmission unit configured to transmit candidate VCs measurement configuration information to the UE, which thus measures the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and further selects the target VC from the candidate VCs according to the VC measurement results； a first reception unit configured to receive the target VC information from the UE； a second transmission unit configured to transmit the candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE may measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and may further select the target TP from the candidate TPs in the target VC according to the TP measurement results； and a second reception unit configured to receive the target TP information from the UE.

The first transmission unit may be configured to transmit the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of a corresponding VC (source VC) of the base station.

The handover module may be configured to initiate a handover request to a base station of the target VC, and send the target TP information to the base station of the target VC.

Still another technical solution adopted by the disclosure is to provide a piece of user equipment (UE) . The UE includes a processor and a communication circuit connected to the processor. The processor is configured to: measure, through the communication circuit, candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results, wherein each VC includes multiple TPs that share a common physical cell identifier (PCI) ； select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and access to the target VC and target TP.

The processor may: measure through the communication circuit the candidate VCs to obtain VC measurement results； select the target VC from the candidate VCs according to the VC measurement results； transmit through the communication circuit the target VC information to a base station of a source VC (currently attached VC) ； receive through the communication circuit the candidate TPs measurement configuration information of the target VC, which is sent from the base station of the source VC based on the target VC information, and measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results； and select the target TP from the candidate TPs in the target VC according to the TP measurement results.

The processor may measure through the communication circuit the candidate VCs when the UE is connected to an edge TP of the source VC.

The processor may measure through the communication circuit the neighboring candidate VCs of the edge TP when the UE is connected to this edge TP.

The processor may: receive through the communication circuit the cell reference signals (CRSs) from the candidate VCs； and detect signal strength and/or signal quality of the CRSs from the candidate VCs, wherein the CRS of a candidate VC is acquired by aggregation of reference signals transmitted by all ON TPs in this candidate VC.

Still another technical solution adopted by the disclosure is to provide a base station. The base station includes a processor and a transceiver connected to the processor. The processor is configured to: transmit, through the transceiver, candidate VCs measurement configuration information and candidate TPs measurement configuration information to a UE, which thus measures the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC may include multiple TPs that share a common physical cell identifier (PCI) ； and enable the UE to access to the target VC and target TP.

The processor may: transmit through the transceiver the candidate VCs measurement configuration information to the UE, which thus measures the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and further selects the target VC from the candidate VCs according to the VC measurement results； receive through the transceiver the target VC information from the UE； transmit, through the transceiver, the candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE may measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and may further select the target TP from the candidate TPs in the target VC according to the TP measurement results； and receive through the transceiver the target TP information from the UE.

The processor may transmit through the transceiver the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of a corresponding VC (source VC) of the base station.

The candidate VCs measurement configuration information may include neighboring candidate VCs of the edge TP connected to the UE.

The processor may further receive through the transceiver a set of edge TPs within the target VC from a base station of the target VC, and generate the candidate TPs measurement configuration information of the target VC according to the edge TPs set.

The processor may further initiate through the transceiver a handover request to the base station of the target VC, and send the target TP information to the base station of the target VC.

Advantages of the disclosure may follow: the UE can measure both the candidate VCs and candidate TPs, select a target VC and a target TP from the candidate VCs and candidate TPs accordingly, and can thus access to the target VC and target TP, where the target VC corresponds to the virtual layer, and the target TP corresponds to the physical layer, thus both the physical layer and the virtual layer can be transferred when a handover of the UE occurs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow chart illustrating a first embodiment of a communication handover method according to the disclosure.

FIG. 2 shows a schematic diagram of virtual cells (VCs) .

FIG. 3 shows a flow chart illustrating a second embodiment of the communication handover method according to the disclosure.

FIG. 4 shows a schematic diagram illustrating handovers between VCs in a communication handover method according to the disclosure.

FIG. 5 shows a flow chart illustrating a third embodiment of the communication handover method according to the disclosure.

FIG. 6 shows a flow chart illustrating a fourth embodiment of the communication handover method according to the disclosure.

FIG. 7 shows a flow chart illustrating a fifth embodiment of the communication handover method according to the disclosure.

FIG. 8 shows a block diagram of a first embodiment of a piece of user equipment (UE) according to the disclosure.

FIG. 9 shows a block diagram of a second embodiment of the UE according to the disclosure.

FIG. 10 shows a block diagram of a third embodiment of the UE according to the disclosure.

FIG. 11 shows a block diagram of a fourth embodiment of the UE according to the disclosure.

FIG. 12 shows a block diagram of a first embodiment of a base station according to the disclosure.

FIG. 13 shows a block diagram of a second embodiment of the base station according to the disclosure.

FIG. 14 shows a block diagram of a third embodiment of the base station according to the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to FIG. 1, there is shown a flow chart illustrating a first embodiment of a communication handover method, which includes the following steps.

In a first step S11, the user equipment (UE) measures candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results.

Referring also to FIG. 2, each VC may include multiple TPs that share a common physical cell identifier (PCI) and a central controller used to control the TPs, for example, a dedicated building baseband unit (BBU) , a centralized BBU, or a virtual base station based on cloud architecture baseband pooling. The TPs are connected to the central controller through low latency transmission network to achieve ideal backhaul. All the TPs within a same VC may transmit the common control channels, e.g., primary synchronization signal (PSS) , secondary synchronization signal (SSS) , broadcast channel (BCH) , and cell reference signal (CRS) .

To reduce energy consumption as well as to minimize interference, the TPs can be turned ON or OFF according to UE attachment and traffic tidal effects. An OFF TP cannot be connected to the UE to transmit the user data, but it may periodically transmit discovery reference signal (DRS) to provide measurement. The transmission period of the DRS is longer than that of the reference signal emitted by an ON TP.

The UE can receive measurement configuration information from the base station of the source cell to obtain information of the candidate VCs and candidate TPs, or it can acquire the information of the candidate VCs and candidate TPs by blind detection. The source cell, which the UE is currently attached to, can be a conventional cell, and can also be a virtual cell. When the source cell is a virtual cell, the base station of the source cell can be the central controller of the source cell, and/or the base station of the TP which the UE is currently attached to. Typically, the candidate VCs are neighboring cells of the source VC.

The UE may measure CRSs from the candidate VCs and the TP-level reference signals from the candidate TPs. For example, the UE may measure the reference signal received power (RSRP) , reference signal received quality (RSRQ) , etc. of the reference signals from the candidate VCs and candidate TPs, so as to obtain the measurement results. The step may proceed to step S12.

In the following step S12, the UE may select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results.

The UE may first measure the candidate VCs and select the target VC, and then measure the candidate TPs and choose the target TP, in which case the candidate TPs are all within the target VC. The UE can also measure the candidate VCs and candidate TPs simultaneously, to obtain the measurement results, and respectively select the target VC and target TP according to the measurement results, ensuring that the target TP belongs to the target VC. The step may then proceed to step S13.

In the following step S13, the UE may access to the target VC and the target TP.

Typically, the UE may transmit the information of the target VC and target TP to the base station of the source cell, which may initiate a handover request to a base station of the target VC and further send the information of the target TP to the base station of the target VC, which may respond to the handover request, thus the UE can be connected to the target VC on the virtual layer, and to the target TP on the physical layer. The UE can certainly autonomously initiate the handover request to the base station of the target VC.

Therefore, the UE can measure both the candidate VCs and the candidate TPs, select a target VC and a target TP, and thus access to the target VC and target TP, where the target VC corresponds to the virtual layer, and the target TP corresponds to the physical layer. Thus, when the UE is transferred to the target VC, both the physical layer and the virtual layer can be transferred.

Referring now to FIG. 3, there is shown a flow chart of second embodiment of the communication handover method, which is based on the first embodiment communication handover method and further defines the above steps S11 and S12.

In a first sub-step S111, the UE measures the candidate VCs to obtain VC measurement results.

The UE may receive the CRSs from the candidate VCs and detect the signal strength and/or signal quality of the CRSs. The signal strength may be represented as RSRP, and the signal quality as RSRQ.

According to an embodiment, the CRS of a candidate VC may be acquired by aggregation of the references signals transmitted from all the ON TPs within this candidate VC.

In a following sub-step S112, the UE selects a target VC from the candidate VCs according to the VC measurement results.

The UE may autonomously select the target VC according to the VC measurement results, or may report the VC measurement results to the base station of the source VC, which makes the selection.

Typically, the UE may select the target VC from the candidate VCs according to the measured RSRP and/or RSRQ of the various VCs.

For example, suppose the UE is currently connected to a VC A, and it may measure candidate VCs B and C. If the UE detects that the RSRP of the VC B is greater than that of the source VC A (currently attached cell) , and the difference between the RSRP of the two cells are larger than a predetermined threshold value, the handover conditions would be satisfied； while the RSRP of the VC C doesn’t meet the handover conditions, then the UE will select the VC B as the target VC. If the RSRP of the VCs B and C both meets the handover conditions, then the UE may compare the RSRP of the VCs B and C, and select one with a higher RSRP as the target VC. The UE can also compare the RSRQ of the VCs B and C, and select one with a higher RSRQ as the target VC. The UE can also report the PCIs of the VCs B and C and their corresponding RSRP to the base station of the source cell A, which decides to select which VC based on the load information of the VCs B and C, which is acquired from the base stations of the VCs B and C through X2 background process, and to send the selection results to the UE.

The RSRP is primarily based to make the selection in the above example, and the RSRQ serves as a potential assistance. Alternatively, the selection can be made chiefly based on the RSRQ or on a combination of the RSRP and RSRQ.

In the following sub-step S113, the UE measures the candidate TPs in the target VC to obtain TP measurement results.

The UE may receive TP-level reference signals from the candidate TPs of the target VC, and detect the signal strength and/or signal quality of the TP-level reference signals. The signal strength may be represented as RSRP, while the signal quality as RSRQ.

The candidate TPs of the target VC may refer to all the TPs within the target VC, or the edge TPs in the target VC that are neighboring the source VC.

In a following sub-step S114, the UE selects a target TP from the candidate TPs within the target VC.

The UE may autonomously select the target TP according to the TP measurement results, or may report the TP measurement results to the base station of the source VC, which thus makes the selection.

Since TPs are used to transmit user data, the signal strength and/or signal quality is the principal criterion in selection of target TP. The candidate TP with the maximum signal strength and/or signal quality will be selected as the target TP, in which case the load conditions of the candidate TPs will not be considered.

Therefore, the candidate VCs may first be measured to select the target VC, and the candidate TPs within the target VC will then be measured to select the target TP, which thus, compared with directly measuring the TPs within all the VCs, can effectively reduce the TP measurements of the UE, and can save the energy consumption of the UE, particularly when the TP deployment density in the candidate VCs is large.

According to an embodiment, when the UE is currently connected to a VC, it may measure the candidate VCs when it is connected to an edge TP of the source VC (currently attached VC) .

Since the UE may typically connect to the nearest TP, the position of the UE can be roughly quickly estimated via the TP connected to the UE. When the UE is connected to an edge TP of the source VC, and it is determined that the UE is close to the edge of the source VC and it may move beyond the source VC, then the candidate VCs will be measured. If the UE switches from an edge TP to a non edge TP, the measurement will be canceled.

An edge TP can be one whose physical position or coverage area locates at the edge of a VC, or may also be a TP defined by the base station to which the UE may be switched to. For example, when edge TPs of the VC have malfunctioned, the base station can designate some TPs, which are not located at the edge of the VC but are relatively close to the malfunctioning TPs, as edge TPs.

Typically, in the prior art the measurement is triggered when the signal power of the source cell is lower than a threshold value. However, in a VC, when the UE moves to the edge of the VC and connects to an edge TP, the signal power may not experience a significant decline, thus the conventional measurement triggering mechanism cannot accurately determine when the measurement is required. If continuously carrying out the measurement, the UE may in effect perform an overload of unnecessary measurements and the energy consumption will be increased. According to the above embodiment though, the measurement is only conducted when the UE is connected to an edge TP, which can thus save the energy consumption and can enable a comparatively accurate measurement triggering mechanism.

When the UE is connected to an edge TP of the source VC, it will measure the neighboring VCs of this edge TP. Typically, the UE may connect to the nearest TP, thus the neighboring VCs of this edge TP may be the nearest VCs to the UE, and the nearest VCs are most likely to be selected as the target VC. Therefore, the UE may only measure the neighboring VCs of this edge TP, which can reduce the VC measurements and thus can save the energy consumption of the UE. Each VC may include multiple edge TPs, and different edge TPs may correspond to a same or different neighboring VCs.

Referring now to FIG. 4, the UE is currently connected to TP 1 in VC 1, where measurement of the candidate VCs is triggered. The candidate VCs include the neighboring VCs 2 and 3 of the TP 1, but not the VCs 4, 5, 6, and 7, which neighbor the VC 1 but don’t neighbor the TP 1.

Referring now to FIG. 5, there is shown a flow chart illustrating a third embodiment of a communication handover method, which is further extended on the basis of the second embodiment communication handover method, thus the common steps as the second embodiment will not be described in detail. The third embodiment communication handover method may include the following steps.

In a first step S121, the UE measures the candidate VCs to obtain VC measurement results. The method may proceed to step S122.

In the following step S122, the UE selects a target VC from the candidate VCs according to the VC measurement results. The method may proceed to step S123.

In the following step S123, the UE sends the target VC information to a base station of a source VC (currently attached VC) .

The UE may send the PCI of the target VC to the base station of the source VC.

If the selection of the target VC is to be carried out by the base station of the source VC, the UE needs to send the PCIs of the candidate VCs and the corresponding measurement results, e.g., the RSRP and/or RSRQ, to the base station. The method may further continue to step S124.

In the following step S124, the UE receives measurement configuration information for the candidate TPs in the target VC, which is sent from a base station of the source VC based on the target VC information.

The base station of the source VC may send the candidate TPs measurement configuration information of the target VC to the UE via RRC connection reconfiguration. The RRC connection reconfiguration information may include a tpsToAddModList information element (IE) and a tpsToRemoveList IE, which represent the candidate TPs set. The candidate TPs set may be transmitted from the base station of the target VC to the base station of the source VC through X2 process.

According to one embodiment, the candidate TPs set consists of edge TPs within the target VC. This set of edge TPs can include all the edge TPs within the target VC, or may include only the edge TPs neighboring the source VC.

Referring also to FIG. 4, the target VC is VC 2, and the candidate TPs set can include all the edge TPs 2, 3, 4, 5, 6 and 7 within the VC 2, or may include only the edge TPs 2 and 3 neighboring the VC 1.

Thus, the TP measurements of the UE can be significantly reduced, so is the energy consumption.

Since the edge TPs in the target VC that neighbor the source VC are nearest to the UE, their signal strength and quality are typically better, and they are more likely to be selected as the target TP. When the candidate TPs set includes only edge TPs neighboring the source VC, the number of the TPs to be measured by the UE can be further reduced without causing a big impact on the selection results.

According to an embodiment, the candidate TPs set may include at least one OFF TP, in which case the candidate TPs measurement configuration information of the target VC may further include discovery reference signal (DRS) timing information, for example, discovery signals measurement timing configuration (DMTC) sub-frame offset. The DRS is transmitted by an OFF TP. The DRS timing information may include the transmission period and offset of the DRS emitted by an OFF TP, depending on which the time of each transmission of DRS from an OFF TP can be calculated. The UE can measure an OFF TP relying on the DRS timing information.

Thus, the OFF TPs can be measured, which expands the range of candidate TPs and further optimizes the selection of the target TP. The method may further proceed to step S125.

In the step S125, the UE measures the candidate TPs in the target VC to obtain TP measurement results.

The UE may measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information of the target VC. The method may then continue to step S126.

In the following step S126, the UE selects a target TP from the candidate TPs within the target VC according to the TP measurement results.

In this embodiment, the UE may first receive the candidate VCs measurement configuration information from the base station of the source VC, and then measure the candidate VCs and select a target VC before reporting the target VC information to the base station of the source VC, and receive the candidate TPs measurement configuration information. Alternatively, the UE may simultaneously obtain the candidate VCs information and information of the TPs in the candidate VCs. After it selects the target VC, the UE may select, from the TPs contained in the acquired TPs information, the TPs belonging to the target VC as the candidate TPs. Thus, the number of the candidate TPs to be measured can be reduced.

Referring now to FIG. 6, there is shown a flow chart illustrating a fourth embodiment of a communication handover method. The method includes the following steps.

In a first step S21, a base station transmits candidate VCs measurement configuration information and candidate TPs measurement configuration information to a piece of user equipment (UE) .

Each VC may include multiple TPs that share a common physical cell identifier (PCI) and a central controller used to control the TPs, for example, a dedicated building baseband unit (BBU) , a centralized BBU, or a virtual base station based on cloud architecture baseband pooling. The TPs may be connected to the base station through low latency transmission network to achieve ideal backhaul. The base station can be the central controller of the source cell, and/or the base station of the TP which the UE is currently attached to.

Typically, the base station may send the candidate VCs measurement configuration information and candidate TPs measurement configuration information through RRC connection reconfiguration. The base station may simultaneously or separately send the candidate VCs measurement configuration information and the candidate TPs measurement configuration information to the UE.

The UE may then measure the candidate VCs and candidate TPs according to the received candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further select a target VC and a target TP from the candidate VCs and candidate TPs. The step may then proceed to step S22.

In the following step S22, the base station may enable the UE to access to the target VC and the target TP.

The base station may receive the target VC and target TP information from the UE, send a handover request to a base station of the target VC, and further send the target TP information to the base station of the target VC, for example, it may add in the handover request an information element (IE) indicating the target TP. The base station of the target VC may respond to the handover request and prepare the target TP accordingly. For example, when the target TP is an OFF TP, the base station of the target VC may turn it on, after which the UE can be connected to the target VC and this target TP. The base station can disconnect its connection with the UE before or after the UE connects to the target VC and the target TP.

Therefore, the UE can measure both the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information received from the base station, select a target VC and a target TP from the candidate VCs and candidate TPs, thus the base station can enable the UE to access to the target VC and the target TP, where the target VC corresponds to the virtual layer, and the target TP corresponds to the physical layer. Thus, when the UE is transferred to the target VC, both the physical layer and the virtual layer can be transferred.

Referring now to FIGS. 7, there is shown a flow chart of a fifth embodiment of a communication method, which is based on the fourth embodiment communication method and further defines the above step S21, which includes the following sub-steps.

In a first sub-step S211, the base station sends candidate VCs measurement configuration information to the UE.

The base station may send the candidate VCs measurement configuration information to the UE through RRC connection reconfiguration, in which a CellstoAddModList information element (IE) may include PCIs of the candidate VCs. The UE may measure the candidate VCs according to the candidate VCs measurement configuration information to obtain the VC measurement results, and further select a target VC from the candidate VCs according to the VC measurement results. The UE as shown in FIGS. 7 may autonomously select the target VC. In other embodiments, the UE may report the VC measurement results to the base station, which carries out the selection.

According to an embodiment, the base station may send the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of the source VC, such that the UE can measure the candidate VCs according to the candidate VCs measurement configuration information.

Since the UE may typically connect to the nearest TP, the position of the UE can be roughly quickly estimated via the TP connected to the UE. When the UE is connected to an edge TP of the source VC, and it is determined that the UE is close to the edge of the source VC and it may move beyond the source VC, the candidate VCs measurement will be triggered.

An edge TP can be a TP whose physical position or coverage area locates at the edge of a VC, or one defined by the base station to which the UE may be switched to. For example, when edge TPs of the VC have malfunctioned, the base station can designate some TPs, which are not located at the edge of the VC but are relatively close to the malfunctioning TPs, as edge TPs.

Typically in the prior art the measurement is triggered when signal power of the source cell is lower than a certain threshold value. However, in a VC, when the UE moves to the edge of the VC and connects to an edge TP, the signal power may not experience a significant decline, thus the conventional measurement triggering mechanism cannot accurately determine when the measurement is required. If continuously carrying out the measurement, the UE may in effect perform an overload of unnecessary measurements and the energy consumption will be increased. According to the above embodiment though, the measurement is only conducted when the UE is connected to the edge TP, which can thus save the energy consumption and can enable a comparatively accurate measurement triggering mechanism. In addition, it can avoid blindly sending the candidate VCs measurement configuration information to the UE when the UE is connected to a non-edge TP, which thus can reduce the transmitted information.

The candidate VCs contained in the candidate VCs measurement configuration information may include neighboring VCs of the edge TP connected to the UE.

Typically, the UE may connect to the nearest TP, and the neighboring VCs of the currently connected edge TP may be the nearest VCs to the UE, and the nearest VCs are most likely to be selected as the target VC. The base station may only send the neighboring VCs to the UE for measurement, thus the VC measurements can be significantly reduced and so is the energy consumption. Each VC may include multiple edge TPs, and different edge TPs may correspond to a same or different neighboring VCs.

If the candidate VCs are changed, for example, if an original candidate VC has malfunctioned and needs to be removed from the candidates, or if the UE switches between different edge TPs causing the corresponding neighboring VCs, which are selected as the candidate VCs, to change, then the base station may need to re-initiate the RRC connection reconfiguration to send updated candidate VCs measurement configuration information to the UE. If the UE switches from an edge TP to a non edge TP, the base station may need to re-initiate the RRC connection reconfiguration to cancel the measurement.

In a following sub-step S212, the base station receives the target VC information from the UE.

The base station may receive the PCI of the target VC from the UE.

In the following sub-step S213, the base station sends the candidate TPs measurement configuration information of the target VC to the UE according to the target VC information.

The base station of the source VC may send the candidate TPs measurement configuration information of the target VC to the UE via RRC connection reconfiguration. The RRC connection reconfiguration information may include a tpsToAddModList IE and a tpsToRemoveList IE specifying the candidate TPs set.

The candidate TPs set is transmitted from the base station of the target VC to the base station of the source VC through X2 process. The X2 process may be executed after the step S212 and before the step S213. The actual X2 process can be background periodical process and take place at any moment before the step S213. In servedCell-Information transmitted during the X2 process, a TpId IE is added to indicate the candidate TPs set.

The UE may measure the candidate TPs within the target VC according to the candidate TPs measurement configuration information to obtain the TP measurement results, and select a target TP from the candidate TPs according to the TP measurement results. The UE may autonomously select the target TP, as shown in the figure, or may report the TP measurement results to the base station, which makes the selection of the target TP.

According to one embodiment, the candidate TPs set consists of edge TPs within the target VC. This set of edge TPs can include all the edge TPs within the target VC, or only the edge TPs neighboring the source VC.

Thus, the TP measurements to be conducted by the UE can be significantly reduced, so is the energy consumption.

According to an embodiment, the candidate TPs set may include at least one OFF TP, in which case the candidate TPs measurement configuration information of the target VC may further include discovery reference signal (DRS) timing information, for example, DMTC sub-frame offset. The DRS is transmitted by an OFF TP. The DRS timing information may include the transmission period and offset of the DRS emitted by an OFF TP, depending on which the time of each transmission of DRS from an OFF TP can be calculated. The UE can thus measure the OFF TP relying on the DRS timing information.

Thus, the OFF TPs can be measured, which further expands the range of candidate TPs and optimizes the selection of the target TP. The method may then proceed to step S124.

In the following sub-step S214, the base station receives the target TP information from the UE.

The base station may receive the target TP identifier (ID) from the UE.

Thus, the base station may first send the candidate VCs measurement configuration information to the UE, receive the target VC information generated through the measurement and selection of the UE, and further send the candidate TPs measurement configuration information of the target VC to the UE. Compared to sending the information of TPs of all the candidate VCs to the UE, the current embodiment can significantly reduce the number of TPs to be transmitted.

Referring now to FIG. 8, there is shown a block diagram illustrating a first embodiment of a piece of user equipment (UE) . The UE includes a measurement module 11, a selection module 12, and an access module 13.

The measurement module 11 is configured to measure candidate VCs and candidate TPs to obtain measurement results. Each VC may include multiple TPs that share a common physical cell identifier (PCI) .

The selection module 12 is configured to select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results.

The access module 13 is configured to access to the target VC and the target TP.

The various modules of the current embodiment UE may be configured to execute the corresponding steps of the first embodiment communication handover method, as shown in FIG. 1. See FIG. 1 and the relevant description for details.

Therefore, in the current embodiment the UE measures both the candidate VCs and candidate TPs, selects a target VC and a target TP from the candidate VCs and candidate TPs, and thus accesses to the target VC and target TP, where the target VC corresponds to the virtual layer, and the target TP corresponds to the physical layer. Thus, when the UE is transferred to the target VC, both the physical layer and the virtual layer can be transferred.

Referring now to FIG. 9, there is shown a second embodiment of the UE according to the disclosure, which is based on the first embodiment UE, where the above measurement module 11 further includes the following units.

A VC measurement unit 111 configured to measure the candidate VCs to obtain VC measurement results.

According to an embodiment, the VC measurement unit 111 may measure the neighboring VCs of an edge TP when the UE is connected to the edge TP of the source VC (currently attached VC) .

Since the UE may typically connect to the nearest TP, the position of the UE can be roughly quickly estimated via the TP connected to the UE. When the UE is connected to an edge TP of the source VC, and it is determined that the UE is close to the edge of the source VC and it may move beyond the source VC, then the candidate VCs measurement will be triggered.

Typically, in the prior art the measurement is triggered when signal power of the source cell is lower than a certain threshold value. However, in a VC, when the UE moves to the edge of the VC and connects to an edge TP, the signal power may not experience a significant decline, thus the conventional measurement triggering mechanism cannot accurately determine when the measurement is required. If continuously carrying out the measurement, the UE may in effect perform an overload of unnecessary measurements and the energy consumption will be increased. According to the above embodiment though, the measurement is only conducted when the UE is connected to the edge TP, which can thus save the energy consumption and can enable a comparatively accurate measurement triggering mechanism.

A TP measurement unit 112 configured to measure the candidate TPs within the target VC to obtain TP measurement results.

The selection module 12 may include the following units.

A VC selection unit 121 configured to select a target VC from the candidate VCs according to the VC measurement results.

A TP selection unit 122 configured to select a target TP from the TPs within the target VC according to the TP measurement results.

The various modules of the current embodiment UE may be configured to execute the corresponding steps of the second embodiment communication handover method, as shown in FIG. 3. See FIG. 3 and the relevant description for details.

Therefore, the candidate VCs may first be measured to select the target VC, and the candidate TPs in the target VC will then be measured to select the target TP, which thus, compared with directly measuring the TPs within all the VCs, can effectively reduce the TP measurements of the UE, and can save the energy consumption of the UE, particularly when TP deployment density in the candidate VCs is large.

Referring now to FIG. 10, there is shown a third embodiment of the UE according to the disclosure, which is based on the second embodiment UE, and further includes the following modules.

A transmission module 14 configured to transmit the target VC information to the base station of the source VC.

A reception module 15 configured to receive the measurement configuration information of the candidate TPs within the target VC, which is transmitted from the base station of the source VC based on the target VC information.

The various modules of the current embodiment UE may be configured to execute the corresponding steps of the third embodiment communication handover method, as shown in FIG. 5. See FIG. 5 and the relevant description for details.

Therefore, the UE may first receive the candidate VCs measurement configuration information from the base station of the source VC, and then measure the candidate VCs and select a target VC, before reporting the target VC information to the base station of the source VC, and again receive the candidate TPs measurement configuration information. Alternatively, the UE may simultaneously obtain the candidate VCs information and information of the TPs in the candidate VCs. After it selects the target VC, the UE may select, from the TPs in the acquired TPs information, the TPs belonging to the target VC as the candidate TPs. Thus, the number of the candidate TPs to be measured can be reduced.

Referring now to FIG. 11, there is shown a block diagram of a fourth embodiment of the UE according to the disclosure. The UE includes a processor 110 and a communication circuit 120 connected to the processor 110 via a bus.

The communication circuit 120 is configured to transmit and receive data. It is an interface through which the UE communicates with other communication equipment.

The processor 110 controls the operations of the UE, and can also be referred to as a central processing unit (CPU) . The processor 110 can be an integrated circuit chip with signal processing capabilities. The processor 110 may also be a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , or other programmable logic devices, discrete gates, transistor logic devices, or discrete hardware components. The general purpose processor can be a microprocessor or any conventional processor.

The UE may further include a memory storage (not shown) used to store the commands and data necessary for operations of the processor 110. The memory storage can also store the data received by the communication circuit 120.

The processor 110 may: measure, via the communication circuit 120, candidate VCs and candidate TPs to obtain measurement results, where each VC may include multiple TPs that share a common physical cell identifier (PCI) ； select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and access to the target VC and the target TP.

Specifically, the processor 110 may: measure the candidate VCs to obtain VC measurement results； select the target VC from the candidate VCs according to the VC measurement results； transmit through the communication circuit 120 the target VC information to a base station of the source VC； receive through the communication circuit 120 the candidate TPs measurement configuration information of the target VC, which is sent from the base station of the source VC based on the target VC information, and measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results； and select the target TP from the candidate TPs in the target VC according to the TP measurement results.

The processor 110 may measure through the communication circuit 120 the candidate VCs when the UE is connected to an edge TP of the source VC.

Specifically, the processor 110 may measure through the communication circuit 120 the neighboring VCs of the edge TP when the UE is connected to this edge TP.

Furthermore, the processor 110 may: receive, via the communication circuit 120, cell reference signals (CRSs) from the candidate VCs； and detect signal strength and/or signal quality of the CRSs from the candidate VCs, wherein the CRS of a candidate VC is acquired by aggregation of reference signals transmitted by all the ON TPs within this candidate VC.

Referring now to FIG. 12, there is shown a first embodiment of a base station according to the disclosure. The base station includes a configuration module 21 and a handover module 22.

The configuration module 21 is configured to transmit candidate VCs measurement configuration information and candidate TPs measurement configuration information to a UE, which thus measures the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and the candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC may include multiple TPs that share a common physical cell identifier (PCI) .

The handover module 22 is configured to enable the UE to access to the target TP of the target VC.

According to an embodiment, the handover module 22 may initiate a handover request to the base station of the target VC, and send the target TP information to the base station of the target VC.

The various modules of the current embodiment base station may be configured to execute the corresponding steps of the fourth embodiment communication handover method, as shown in FIG. 6. See FIG. 6 and the relevant description for details.

Therefore, the UE can measure both the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information transmitted from the base station, select a target VC and a target TP from the candidate VCs and candidate TPs, thus the base station can enable the UE to access to the target VC and the target TP, wherein the target VC corresponds to the virtual layer, and the target TP corresponds to the physical layer. Thus, both the physical layer and the virtual layer can be transferred to the target VC when a handover of the UE is required.

Referring now to FIG. 13, there is shown a second embodiment of the base station according to the disclosure, which is based on the first embodiment base station, in which the configuration module 21 further includes the following units.

A first transmission unit 211 configured to transmit the candidate VCs measurement configuration information to the UE, which may thus measure the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and may further select a target VC from the candidate VCs according to the VC measurement results.

According to an embodiment, the first transmission unit 211 may transmit the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of a corresponding VC of the base station.

A first reception unit 212 configured to receive the target VC information from the UE.

A second transmission unit 213 configured to send the candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE may measure the candidate TPs within the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and select a target TP from the candidate TPs within the target VC according to the TP measurement results.

A second reception unit 214 configured to receive the target TP information from the UE.

The various modules of the current embodiment base station may be configured to execute the corresponding steps of the fifth embodiment communication handover method, as shown in FIG. 7. See FIG. 7 and the relevant description for details.

Therefore, the base station may first send the candidate VCs measurement configuration information to the UE, receive the target VC information generated through the measurement and selection of the UE, and further send the candidate TPs measurement configuration information within the target VC to the UE. Compared to sending information of TPs of all the candidate VCs to the equipment, the current embodiment can significantly reduce the number of candidate TPs to be transmitted.

Referring now to FIG. 14, there is shown a block diagram of a third embodiment of the base station according to the disclosure. The base station includes a processor 210 and a transceiver 220 connected to the processor 210 via a bus.

The transceiver 220 is configured to transmit and receive data. It is an interface through which the base station communicates with other communication equipment.

The processor 210 controls operations of the base station, and can also be referred to as a central processing unit (CPU) . The processor 210 can be an integrated circuit chip with signal processing capabilities. The processor 210 may also be a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , or other programmable logic devices, discrete gates, transistor logic devices, or discrete hardware components. The general purpose processor can be a microprocessor or any conventional processor.

The base station may further include a memory storage (not shown) used to store the commands and data necessary for operations of the processor 210. The memory storage can also store the data received through the transceiver 220.

The processor 210 may: transmit, through the transceiver 220, candidate VCs measurement configuration information and candidate TPs measurement configuration information to a UE, which may thus measure the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and the candidate TPs measurement configuration information, and may further select a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC may include multiple TPs that share a common physical cell identifier (PCI) ； and enable the UE to access to the target VC and the target TP.

Specifically, the processor 210 may: transmit through the transceiver 220 the candidate VCs measurement configuration information to the UE, which may thus measure the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and may further select the target VC from the candidate VCs according to the VC measurement results； receive through the transceiver 220 the target VC information from the UE； transmit through the transceiver 220 the candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE may measure the candidate TPs in the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and may select the target TP from the candidate TPs in the target VC according to the TP measurement results； and receive through the transceiver 220 the target TP information from the UE.

The processor 210 may: transmit through the transceiver 220 the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of a corresponding VC of the base station. The candidate VCs measurement configuration information may include information of the neighboring candidate VCs of this edge TP connected to the UE.

The processor 210 may receive through the transceiver 220 a set of edge TPs in the target VC from the base station of the target VC, and generate the candidate TPs measurement configuration information of the target VC according to the edge TPs set.

The processor 210 may further initiate through the transceiver 220 a handover request to the base station of the target VC, and send the target TP information to the base station of the target VC.

It should be noted that, in the embodiments disclosed herein, the disclosed UEs, base stations and methods can also be implemented by other ways. Rather, the UE embodiments and base station embodiments described are merely illustrative, for example, the division of modules or units is only a division based on logic functions, thus in actual implementations there may be other division manners, for example, multiple units or components may be combined or integrated onto another system, or some features may be ignored or not executed. In addition, the displayed or discussed mutual couplings, direct couplings or communication connections may be achieved through some interfaces, devices or units, and may be achieved electrically, mechanically or in other forms.

The separated units as described may or may not be physically separated. Components displayed as units may or may not be physical units, and may reside at one location or may be distributed to multiple networked units. Part or all of the units may be selected, according to actual requirements, to achieve the objectives of the solutions of the embodiments.

In addition, various functional units in embodiments of the disclosure may be integrated into one processing unit, and may be present as various physically separated units, and two or more units may be integrated into one unit. The integrated units may be implemented by hardware, and may also be implemented as software functional units.

If the integrated units are implemented as software functional units and sold or used as standalone products, they can be stored in a computer readable storage medium. On the basis of such an understanding, the substantial technical solution, or the part which contributes to the prior art, or all or part of the technical solution, of the disclosure, may be embodied as software products. The computer software products can be stored in a storage medium and can include multiple instructions enabling a computing device (for example, a personal computer, a server, a network device, etc. ) or a processor to execute all or part of the steps of the methods as described in various embodiments of the disclosure. The storage medium may include all kinds of medium that can store program codes such as, for example, a USB flash disk, a mobile hard drive, a read-only memory (ROM) , a random access memory (RAM) , a magnetic disk or an optical disk.

The above description is merely embodiments of the disclosure, but is not limiting the scope of the disclosure. Any equivalent structures or flow transformations made to the disclosure, or any direct or indirect applications of the disclosure on other related fields, shall all be covered within the protection of the disclosure.

Claims

A communication handover method, comprising:

measuring, by a piece of user equipment (UE) , candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results, wherein each VC comprises a plurality of TPs that share a common physical cell identifier (PCI) ；

selecting, by the UE, a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and

accessing, by the UE, to the target VC and the target TP.
The method according to claim 1, wherein the block of the UE measuring the candidate VCs and candidate TPs and further selecting the target VC and the target TP comprises:

measuring, by the UE, the candidate VCs to obtain VC measurement results, and selecting, by the UE, the target VC from the candidate VCs according to the VC measurement results；

measuring, by the UE, the candidate TPs to obtain TP measurement results； and

selecting, by the UE, the target TP from the candidate TPs within the target VC according to the TP measurement results.
The method according to claim 2, wherein the block of the UE measuring the candidate VCs comprises:

measuring, by the UE, the candidate VCs when the UE is connected to an edge TP of a source VC.
The method according to claim 3, wherein the block of the UE measuring the candidate VCs comprises:

measuring neighboring candidate VCs of the edge TP when the UE is connected to this edge TP of the source VC.
The method according to claim 2, further comprising, after the block of selecting the target VC and before the block of measuring the candidate TPs within the target VC:

transmitting, by the UE, the target VC information to a base station of a source VC； and

receiving, by the UE, measurement configuration information of the candidate TPs within the target VC, which is transmitted from the base station of the source VC based on the target VC information.
The method according to claim 5, wherein the candidate TPs measurement configuration information of the target VC comprises a set of edge TPs within the target VC, and the UE measures the edge TPs according to the edge TPs set, wherein the edge TPs set is transmitted from a base station of the target VC to the base station of the source VC.
The method according to claim 6, wherein the edge TPs set comprises at least one OFF TP, and the candidate TPs measurement configuration information of the target VC further comprises discovery reference signal (DRS) timing information, which indicates the time the OFF TP emits the DRS.
The method according to of claim 1, wherein the block of the UE measuring the candidate VCs comprises:

measuring, by the UE, cell reference signals (CRSs) from the candidate VCs, detecting at least one of signal strength and signal quality of the CRSs, wherein the CRS of each candidate VC is acquired by aggregation of reference signals transmitted by all ON TPs within this candidate VC.
A communication handover method, comprising:

transmitting, by a base station, candidate virtual cells (VCs) measurement configuration information and candidate transmission points (TPs) measurement configuration information to a piece of user equipment (UE) , which measures the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC comprises a plurality of TPs that share a common physical cell identifier (PCI) ； and

enabling, by the base station, the UE to access to the target VC and the target TP.
The method according to claim 9, wherein the block of the base station transmitting the candidate VCs measurement configuration information and candidate TPs measurement configuration information to the UE, which measures the candidate VCs and candidate TPs and further selects the target VC and target TP comprises:

transmitting, by the base station, the candidate VCs measurement configuration information to the UE, which thus measures the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and further selects the target VC from the candidate VCs according to the candidate VCs measurement configuration information；

receiving, by the base station, the target VC information from the UE；

transmitting, by the base station, candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE measures the candidate TPs within the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and further selects the target TP according to the TP measurement results； and

receiving, by the base station, the target TP information from the UE.
The method according to claim 10, wherein the block of the base station transmitting the candidate VCs measurement configuration information to the UE comprises:

transmitting, by the base station, the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP within a corresponding VC of the base station.
The method according to claim 11, wherein the candidate VCs measurement configuration information comprises information of neighboring candidate VCs of this edge TP connected to the UE.
The method according to claim 10, wherein the candidate TPs measurement configuration information of the target VC comprises a set of the edge TPs within the target VC, and the edge TPs set is received by the base station from a base station of the target VC.
The method according to claim 13, wherein the edge TPs set comprises at least one OFF TP, and the candidate TPs measurement configuration information of the target VC further comprises discovery reference signal (DRS) timing information, wherein the DRS is a reference signal transmitted by the OFF TP, and the DRS timing information indicates the time the OFF TP emits the DRS.
The method according to claim 9, wherein the block of the base station enabling the UE to access to the target VC and the target TP comprises:

initiating, by the base station, a handover request to a base station of the target VC, and transmitting the target TP information to the base station of the target VC.
A piece of user equipment (UE) , comprising:

a measurement module configured to measure candidate virtual cells (VCs) and candidate transmission points (TPs) to obtain measurement results, wherein each VC comprises a plurality of TPs that share a common physical cell identifier (PCI) ；

a selection module configured to select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and

an access module configured to access to the target VC and the target TP.
The UE according to claim 16, wherein the measurement module comprises:

a VC measurement unit configured to measure the candidate VCs to obtain VC measurement results；

a TP measurement unit configured to measure the candidate TPs within the target VC to obtain TP measurement results； and

the selection module comprises:

a VC selection unit configured to select the target VC from the candidate VCs according to the VC measurement results； and

a TP selection unit configured to select the target TP from the candidate TPs within the target VC according to the TP measurement results.
The UE according to claim 17, wherein the VC measurement unit is configured to measure, when the UE is connected to an edge TP of a source VC, neighboring candidate VCs of this edge TP connected to the UE.
The UE according to claim 17, further comprising:

a transmission module configured to transmit the target VC information to a base station of a source VC； and

a reception module configured to receive the candidate TPs measurement configuration information of the target VC, which is transmitted from the base station of the source VC based on the target VC information.
A base station, comprising:

a configuration module configured to transmit candidate virtual cells (VCs) measurement configuration information and candidate transmission points (TPs) measurement configuration information to a piece of user equipment (UE) , which thus measures the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC comprises a plurality of TPs that share a common physical cell identifier (PCI) ； and

a handover module configured to enable the UE to access to the target VC and the target TP.
The base station according to claim 20, wherein the configuration module comprises:

a first transmission unit configured to transmit the candidate VCs measurement configuration information to the UE, which thus measures candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and further selects a target VC from the candidate VCs according to the VC measurement results；

a first reception unit configured to receive the target VC information from the UE；

a second transmission unit configured to transmit the candidate TPs measurement configuration information of the target VC to the UE based on the target VC information, such that the UE measures the candidate TPs within the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and further selects the target TP from the candidate TPs according to the candidate TPs measurement configuration information； and

a second reception unit configured to receive the target TP information from the UE.
The base station according to claim 21, wherein the first transmission unit is configured to transmit the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of a corresponding VC of the base station.
The base station according to claim 20, wherein the handover module is configured to initiate a handover request to a base station of the target VC, and send the target TP information to the base station of the target VC.
A piece of user equipment (UE) , comprising: a processor and a communication circuit connected to the processor； wherein

the processor is configured to: measure candidate virtual cells (VCs) and candidate transmission points (TPs) via the communication circuit to obtain measurement results, wherein each VC comprises a plurality of TPs that share a common physical cell identifier (PCI) ； select a target VC and a target TP from the candidate VCs and candidate TPs according to the measurement results； and access to the target VC and the target TP.
The UE according to claim 24, wherein the processor is configured to measure via the communication circuit the candidate VCs to obtain VC measurement results； select the target VC from the candidate VCs according to the VC measurement results； transmit through the communication circuit the target VC information to a base station of a source VC； receive via the communication circuit the candidate TPs measurement configuration information of the target VC, which is transmitted from the base station of the source VC based on the target VC information, and measure the candidate TPs within the target VC according to the candidate TPs measurement configuration information of the target VC to obtain TP measurement results； and select the target TP from the candidate TPs within the target VC according to the TP measurement results.
The UE according to claim 25, wherein the processor is configured to measure via the communication circuit the candidate VCs when the UE is connected to an edge TP of the source VC.
The UE according to claim 26, wherein the processor is configured to measure neighboring candidate VCs of the edge TP via the communication circuit when the UE is connected to this edge TP.
The UE according to claim 24, wherein the processor is configured to receive, via the communication circuit, cell reference signals (CRSs) from the candidate VCs, and detect at least one of signal strength and signal quality of the CRSs, wherein the CRS of a candidate VC is acquired by aggregation reference signals transmitted by all ON TPs within this candidate VC.
A base station, comprising: a processor and a transceiver connected to the processor； wherein

the processor is configured to: transmit candidate virtual cells (VCs) measurement configuration information and candidate transmission points (TPs) measurement configuration information to a piece of user equipment (UE) via the transceiver, such that the UE measures the candidate VCs and candidate TPs according to the candidate VCs measurement configuration information and candidate TPs measurement configuration information, and further selects a target VC and a target TP from the candidate VCs and candidate TPs, wherein each VC comprises a plurality of TPs that share a common physical cell identifier (PCI) ； and enable the UE to access to the target VC and the target TP.
The base station according to claim 29, wherein the processor is configured to: transmit the candidate VCs measurement configuration information to the UE via the transceiver, such that the UE measures the candidate VCs according to the candidate VCs measurement configuration information to obtain VC measurement results, and further selects the target VC from the candidate VCs according to the candidate VCs measurement configuration information； receive via the transceiver the target VC information from the UE； transmit the candidate TPs measurement configuration information of the target VC to the UE via the transceiver based on the target VC information, such that the UE measures the candidate TPs within the target VC according to the candidate TPs measurement configuration information to obtain TP measurement results, and further selects the target TP from the candidate TPs within the target VC according to the TP measurement results； and receive via the transceiver the target TP information from the UE.
The base station according to claim 30, wherein the processor is configured to transmit the candidate VCs measurement configuration information to the UE when the UE is connected to an edge TP of a corresponding VC of the base station.
The base station according to claim 31, wherein the candidate VCs measurement configuration information comprises information of neighboring candidate VCs of this edge TP connected to the UE.
The base station according to 30, wherein the processor is further configured to receive via the transceiver a set of edge TPs within the target VC from a base station of the target VC, and generate the candidate TPs measurement configuration information of the target VC according to the edge TPs set.
The base station according to claim 29, wherein the processor is further configured to initiate a handover request to a base station of the target VC through the transceiver, and transmit the target TP information to the base station of the target VC.