CN104349402A

CN104349402A - Terminal switching method supporting D2D technology, communication node, terminal and system

Info

Publication number: CN104349402A
Application number: CN201310313988.2A
Authority: CN
Inventors: 马书宇; 陈琳; 罗宇民; 谢峰; 鲁照华
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2013-07-24
Filing date: 2013-07-24
Publication date: 2015-02-11
Also published as: WO2015010511A1

Abstract

The invention discloses a terminal switching method supporting device to device (D2D) technology. The method includes the step that a source communication node controls a first D2D terminal to be switched to a target communication node according to measurement results reported by the first D2D terminal and/or the information of a second D2D terminal. The invention also discloses a communication node, a terminal and a system. With the terminal switching method supporting the D2D technology, the communication node, the terminal and the system of the invention adopted, the problem of conflict of resources used by D2D communication and resources of a cell after D2D user equipment is switched can be solved.

Description

Terminal switching method, communication node, terminal and system supporting D2D technology

Technical Field

The present invention relates to the field of mobile communication technologies, and in particular, to a terminal switching method, a communication node, a D2D terminal, and a system supporting Device-to-Device (D2D) technologies.

Background

Currently, with the development of wireless multimedia services, the demand for high data rate and user experience is increasing, and thus higher requirements are put on the system capacity and coverage of the conventional cellular network. On the other hand, the popularity of applications such as social networking, near-distance data sharing, local advertising, etc. has led to an increasing need for people to know and communicate with people or things of interest nearby, namely: there is an increasing demand for proximity services (proximitiservics). Given the significant limitations of conventional base station centric cellular networks in terms of high data rates and support for proximity services, the D2D technology representing a new direction for future communication technology development has emerged. The application of the D2D technology can reduce the burden of the cellular network, reduce the battery power consumption of the user equipment, increase the data rate, and improve the robustness of the network infrastructure, and well meet the requirements of the high data rate service and the proximity service.

The D2D technology can operate in licensed or unlicensed bands, allowing multiple D2D capable User equipments, i.e., D2D User equipments (D2D User Equipment, D2D UE) to perform direct discovery/direct communication with or without network infrastructure. There are three main application scenarios of D2D:

1) the UE1 and the UE2 perform data interaction under the coverage of a cellular network, and user plane data does not pass through a network infrastructure, as shown in pattern 1 in fig. 1;

2) UE relay transmission in weak/no coverage areas, as shown in pattern 2 in fig. 1, allowing a UE4 with poor signal quality to communicate with the network through a UE3 with nearby network coverage can help operators to extend coverage and increase capacity;

3) in the event of an earthquake or an emergency, and the cellular network cannot work normally, direct communication among the devices is allowed, as shown in mode 3 in fig. 1, and the control plane and the user plane among the UE5, the UE6 and the UE7 do not go through the network infrastructure and perform one-hop or multi-hop data communication.

D2D technology generally includes D2D discovery technology and D2D communication technology; the D2D discovery technology is a technology for determining/confirming that two or more D2D ues are in proximity to each other, for example, within a range where D2D can be directly communicated, or for determining/confirming that a first ue is in proximity to a second ue. Generally, the D2D ues can discover each other by sending or receiving discovery signals/information, and under the coverage of cellular network, the network can assist the D2D ues in D2D discovery; the D2D communication technology refers to a technology in which some or all of the data communicated between the D2D user equipments can be directly communicated without passing through a network infrastructure.

Handover refers to the access of a wireless terminal from one cell or base station to another cell or base station, and communication can continue, and the main functions of the handover technology are to keep the service of the terminal during the moving process, not drop the call, and not reduce the quality of service (QoS).

The D2D communication technology can be divided into two technologies, network assisted D2D communication and non-network assisted D2D communication. In network assisted D2D communication technologies, there is also a need to ensure that D2D user equipment can correctly switch between cells.

The existing handover technology of Long Term Evolution (LTE) supports common wireless user equipment, namely: handover of wireless user equipment of cellular technology, but does not take into account the scenario in which D2D communication is ongoing at the time of user equipment handover. If the existing LTE technology is used to perform handover of the D2D ue, after the handover, if the D2D terminal still uses the previously allocated resources for communication, it is likely to collide with the radio resources of the cell where the terminal is located after the handover, which may cause that the service of the D2D ue cannot be performed normally.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a terminal handover method, a communication node and a system supporting D2D technology, which can solve the problem of resource conflict between the resource used for D2D communication and the resource of the cell after handover caused by handover of the existing D2D user equipment.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the invention provides a terminal switching method for supporting a device-to-device D2D technology, which comprises the following steps:

and the source communication node controls the first D2D terminal to be switched to the target communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal.

Wherein the first D2D terminal is a D2D enabled user equipment served by the source communication node and in D2D communication with a second D2D terminal.

The source communication node and the target communication node are base stations or cells.

Preferably, the method further comprises:

and if the source communication node simultaneously receives the measurement results reported by the first D2D terminal and the second D2D terminal, and if the first D2D terminal is the main device, the switching decision operation of the first D2D terminal is preferentially carried out.

Wherein the master device refers to a D2D device with high priority in the D2D communication nodes or a D2D device with resource management capability.

Wherein, the controlling, by the source communication node, the first D2D terminal to switch to the target communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal includes:

the source communication node judges whether the first D2D terminal is switched and a target communication node for switching according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal;

if the first D2D terminal satisfies a handover condition and there is a suitable target communication node, the source communication node handing over the first D2D terminal to the target communication node.

Preferably, the source communication node determines whether the first D2D terminal is handed over and before the target communication node of the handover, the method further includes:

if the source communication node monitors that a serving communication node of the second D2D terminal in D2D communication with the first D2D terminal is different from the source communication node, the source communication node increases a cell offset corresponding to the serving communication node of the second D2D terminal when performing measurement configuration for the first D2D terminal;

and the source communication node sends the adjusted measurement configuration to the first D2D terminal, and the first D2D terminal measures according to the received measurement configuration and reports the measurement result to the source communication node.

Wherein the measurement result comprises a reference signal received power, RSRP, and/or a reference signal received quality, RSRQ.

Preferably, the source communication node monitors that a serving communication node of the second D2D terminal in D2D communication with the first D2D terminal is different from the source communication node, the method further comprising:

the source communication node acquiring the second D2D terminal information and serving communication node information of a second D2D terminal when the D2D communication of the first D2D terminal is established;

when the second D2D terminal is handed over, the source communication node acquires the service communication node information after the handover of the second D2D terminal is performed and updated from the service communication node of the second D2D terminal.

Preferably, the acquiring, by the source communication node, the service communication node information of the second D2D terminal and the second D2D terminal when the D2D communication of the first D2D terminal is established includes:

when the first D2D terminal establishes a communication connection, the first D2D terminal sends a message to its serving communication node, including D2D communication connection information, and serving communication node information of a second D2D terminal; or,

and the service communication nodes of the first D2D terminal and the second D2D terminal negotiate to control the establishment of D2D communication connection, and in the negotiation process, the first D2D terminal/the second D2D terminal store the information of the second D2D terminal/the first D2D terminal and the corresponding service base station information.

Preferably, the determining, by the source communication node, whether the first D2D terminal is handed over and a target communication node of the handover according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal includes:

the source communication node acquires information whether the neighboring communication node supports the D2D function, and if the neighboring communication node does not support the D2D function, the source communication node cannot serve as a target communication node of the first D2D terminal;

the source communication node judges whether the second D2D terminal is performing handover, and if so, performs handover decision of the first D2D terminal after the handover of the second D2D terminal is completed;

the source communication node judges whether switching is needed according to the measurement result reported by the first D2D terminal, and if switching is needed, the source communication node finds out a candidate target communication node of the first D2D terminal according to the measurement result;

if the source communication node finds candidate target communication nodes of a plurality of first D2D terminals, the source communication node preferentially takes the service communication node of a second D2D terminal as the target communication node of the first D2D terminal according to the acquired service communication node information of the second D2D terminal.

Wherein the source communication node acquires information whether the adjacent communication node supports the D2D function, including:

the source communication node exchanges information with the adjacent communication node through an X2 port message to acquire information whether the adjacent communication node supports the D2D communication function; or,

the source communication node acquires information whether the adjacent communication node supports the D2D function or not through an S1 port and a network manager; or,

and the source communication node acquires information whether the adjacent communication node supports the D2D function or not through the information reported by the self-service terminal.

Preferably, the method further comprises:

if only the D2D communication mode traffic and no cellular communication mode traffic exists between the first D2D terminal and the second D2D terminal, the source communication node reduces its corresponding cell offset when performing measurement configuration for the first D2D terminal.

Preferably, the source communication node handing over the first D2D terminal to the target communication node if the first D2D terminal satisfies a handover condition and there is a suitable target communication node, including:

the source communication node sends a switching request message to a target communication node, wherein the message carries information related to a first D2D terminal and a second D2D terminal;

after receiving the handover request message, the target communication node sends a handover request response message to the source communication node, where the message carries information related to D2D, where the information includes: D2D radio resource allocation information;

after receiving the switching request response message, the source communication node sends a switching command to the first D2D terminal, wherein the switching command carries D2D wireless resource allocation information;

and the first D2D terminal receives the switching command and accesses to a target communication node according to the switching command.

Wherein, after the first D2D terminal is handed over to the target communication node, the method further comprises:

and the first D2D terminal updates the D2D communication resources according to the D2D wireless resource allocation information and performs D2D communication with the second D2D terminal by using the updated resources.

Wherein the target communication node sending D2D radio resource allocation information to the source communication node in a handover request response message, comprising:

if the serving communication node of the second D2D terminal is the same as the target communication node, the target communication node allocating the first D2D terminal with radio resources corresponding to the same target communication node as the second D2D terminal;

if the serving and target communication nodes of the second D2D terminal are not the same, the target communication node allocates the same radio resources between the serving and target communication nodes of the second D2D terminal to the first D2D terminal.

Wherein the first D2D terminal performing D2D communication resource update according to the D2D wireless resource allocation information, and performing D2D communication with the second D2D terminal by using the updated resource, comprising:

if the first D2D terminal is the master device, the first D2D terminal initiates D2D communication resource update, and uses the updated resource to perform D2D communication with the second D2D terminal;

if the first D2D terminal is not the master device and the second D2D terminal is the master device, after the handover of the first D2D terminal is finished, the serving communication node of the second D2D terminal notifies the second D2D terminal that the first D2D terminal is finished, and notifies the first D2D terminal of the radio resource allocation information of the switched D2D;

the second D2D terminal initiates a D2D communication resource update and uses the updated resource for D2D communication with the first D2D terminal.

Preferably, the method further comprises:

if the first D2D terminal is at a different communication node from the second D2D terminal after the handover, the serving communication node of the second D2D terminal obtains the resource configuration of the first D2D terminal after the handover in a handover preparation phase; or,

after the handover, the serving communication node handed over by the first D2D terminal notifies the serving communication node of the second D2D terminal.

Preferably, the method further comprises:

the source communication node informs the first D2D terminal and the second D2D terminal to switch back from the D2D communication mode to the cellular communication mode.

Preferably, the method further comprises: and the source communication node sends a switching request message to the target communication node to carry out the inter-cell switching of the first D2D terminal and the second D2D terminal or the first D2D terminal.

The invention also provides a communication node, which comprises a control module, and is used for controlling the first D2D terminal to switch to an opposite communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal.

Wherein the first D2D terminal is a D2D enabled user equipment served by the source communication node and in D2D communication with a second D2D terminal; the communication node is a base station or a cell.

Preferably, the control module is further configured to receive measurement results reported by the first D2D terminal and the second D2D terminal at the same time, and preferentially perform a handover decision operation of the first D2D terminal when the first D2D terminal is a master device.

Preferably, the control module is configured to determine whether the first D2D terminal is switched and an opposite-end communication node for switching according to a measurement result reported by the first D2D terminal and/or information of the second D2D terminal; when it is determined that the first D2D terminal satisfies a handover condition and there is a suitable correspondent communication node, then the first D2D terminal is handed over to the correspondent communication node.

Preferably, whether the first D2D terminal is switched and before the opposite communication node of the switching is judged,

the control module is further configured to, when monitoring that a serving communication node of the second D2D terminal that performs D2D communication with the first D2D terminal is different from a communication node to which the serving communication node belongs, perform measurement configuration for the first D2D terminal, increase a cell offset corresponding to the serving communication node of the second D2D terminal;

and is further configured to send the adjusted measurement configuration to the first D2D terminal, and receive a measurement result reported by the first D2D terminal.

Preferably, the serving communication node of the second D2D terminal monitoring D2D communication with the first D2D terminal is different from the communication node to which it belongs,

the control module is further configured to acquire the second D2D terminal information and service communication node information of a second D2D terminal when D2D communication of the first D2D terminal is established;

and is further configured to acquire, from the serving correspondent node of the second D2D terminal, the serving correspondent node information of the second D2D terminal after performing handover and updating when the handover occurs to the second D2D terminal.

Preferably, the control module is further configured to, when only the D2D communication mode service and no cellular communication mode service exists between the first D2D terminal and the second D2D terminal, adjust down a cell offset corresponding to the corresponding communication node when performing measurement configuration for the first D2D terminal.

Preferably, the control module is further configured to notify the first D2D terminal and the second D2D terminal to switch from the D2D communication mode back to the cellular communication mode.

Preferably, the control module is further configured to send a handover request message to the peer communication node, and perform inter-cell handover between the first D2D terminal and the second D2D terminal, or the first D2D terminal.

The invention also provides a D2D terminal, wherein the D2D terminal comprises a switching module, configured to switch to a second communication node under the control of the first communication node according to the measurement result reported by the D2D terminal and/or the information of another D2D terminal.

Wherein the D2D terminal is a D2D enabled user equipment served by the first communication node and in D2D communication with the other D2D terminal.

Preferably, the handover module is further configured to report the measurement result to the first communication node simultaneously with another D2D terminal, and accept a handover decision operation performed by the first communication node when the D2D terminal to which the handover module belongs is a master device.

Preferably, the handover module is further configured to report the measurement result and/or the information of the another D2D terminal to the first communication node, and handover to a second communication node under the control of the first communication node when it is determined that the D2D terminal that the handover module belongs to meets the handover condition and a suitable peer communication node exists.

Preferably, the D2D terminal is different from the serving communication node of the other D2D terminal,

the switching module is further configured to receive the measurement configuration sent by the first communication node, and report a measurement result to the first communication node.

Preferably, after the D2D terminal is handed over to the second communication node,

the switching module is further configured to update the D2D communication resources according to the D2D radio resource allocation information, and perform D2D communication with the another D2D terminal using the updated resources.

Preferably, the switching module is further configured to switch from the D2D communication mode back to the cellular communication mode after receiving the notification of the first communication node.

The invention also provides a terminal switching system supporting the D2D technology, which comprises the communication node and the D2D terminal.

According to the terminal switching method, the communication node and the system supporting the D2D technology, the source communication node controls the first D2D terminal to be switched to the target communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal. Wherein the first D2D terminal is a D2D enabled user equipment served by the source communication node and in D2D communication with a second D2D terminal. The invention solves the problem that the resource used by D2D communication may conflict with the resource of the cell after the D2D user equipment is switched in the prior LTE technology, ensures that the cell can be efficiently selected when the D2D user equipment is switched, can correctly perform resource negotiation in the switching process of the D2D user equipment, and can ensure the service continuity of the D2D user equipment switching and the smoothness of communication service.

Drawings

Fig. 1 is a diagram illustrating different modes of communication between conventional D2D ue devices;

FIG. 2 is a schematic diagram of a D2D handover scenario according to an embodiment of the present invention;

fig. 3 is a switching flowchart corresponding to a first switching scenario in an embodiment of the present invention, where a switching UE is a master UE;

fig. 4 is a switching flowchart corresponding to a first switching scenario in an embodiment of the present invention, where a UE is switched to a slave UE;

fig. 5 is a switching flowchart corresponding to a first switching scenario in an embodiment of the present invention, where a UE is switched without a master-slave mode;

fig. 6 is a switching flowchart corresponding to a second switching scenario in the embodiment of the present invention, where a switching UE is a master UE or a slave UE;

fig. 7 is a switching flowchart corresponding to a second switching scenario in the embodiment of the present invention, where the switching UE does not have to be divided into a master and a slave;

fig. 8 is a switching flowchart corresponding to a third switching scenario in the embodiment of the present invention, where a switching UE is a master UE;

fig. 9 is a switching flowchart corresponding to a third switching scenario in the embodiment of the present invention, where a UE is switched to a slave UE;

fig. 10 is a switching flowchart corresponding to a third switching scenario in the embodiment of the present invention, where a UE is switched without master-slave;

fig. 11 is a switching flow chart of the UE switching back to the cellular communication mode and then switching according to embodiment D2D of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

Preferably, the second D2D terminal is a user equipment in D2D communication with the first D2D terminal.

Preferably, the source communication node and the target communication node are base stations or cells.

Preferably, the method further comprises:

Preferably, the master device refers to a D2D device with a high priority in the D2D communication nodes, or a D2D device with resource management capability.

Preferably, the controlling, by the source communication node, the first D2D terminal to switch to the target communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal includes:

Preferably, the obtaining, by the source communication node, information whether the neighboring communication node supports the D2D function includes:

Preferably, the method further comprises:

Preferably, after the first D2D terminal is handed over to the target communication node, the method further includes:

Preferably, the target communication node sends D2D radio resource allocation information to the source communication node in a handover request response message, including:

Preferably, the updating of the D2D communication resources by the first D2D terminal according to the D2D radio resource allocation information, and the D2D communication with the second D2D terminal using the updated resources, includes:

Preferably, the method further comprises:

Preferably, the first D2D terminal is a D2D enabled user equipment served by the source communication node and in D2D communication with a second D2D terminal; the communication node is a base station or a cell.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The scenes switched by D2D can be classified into the following 3 categories.

The first scenario is shown in fig. 2 (a), before handover, both UE1 and UE2 are under the coverage of eNB1, their serving enbs are both eNB1, UE1 and UE2 are performing D2D communication, and UE1 or UE2 is handed over from eNB1 to eNB 2. This scenario can be summarized as: two UEs are under one eNB before handover, and two UEs are under different enbs after handover.

The second category of scenarios is shown in fig. 2 (b), where the UE1 is under the coverage of eNB1, and its serving eNB is eNB 1; under the coverage of eNB2, the UE2 serving eNB is eNB2, UE1 and UE2 are performing D2D communication, UE1 is handed over from eNB1 to eNB2 or UE2 is handed over from eNB2 to eNB1, and this scenario can be summarized as: the two UEs before the handover are under different eNBs, and the two UEs after the handover are under the same eNB.

A third category of scenarios is shown in fig. 2 (c), where the UE1 is under the coverage of eNB1, and its serving eNB is eNB 1; under the coverage of eNB2, the UE2 serving eNB is eNB2, UE1 and UE2 are performing D2D communication, UE1 is handed over from eNB1 to eNB3 or UE2 is handed over from eNB2 to eNB3, and this scenario can be summarized as: the two UEs are under different enbs before handover, and the two UEs are under the same eNB after handover.

Example one

In this embodiment, in a first type of scenario, that is, two UEs before handover are under one eNB, and two UEs after handover are under different enbs, an embodiment of D2D terminal handover is provided. The embodiment shows the flow of D2D UE handover in the first type of scenario.

Example 1, the UE to be switched is the main UE, FIG. 3 is a schematic diagram of the switching process

D2D switching is divided into four parts of measuring object parameter adjustment, switching judgment, switching preparation and switching execution. The measurement object parameter adjustment is an optional procedure, but the step of acquiring the UE location in the measurement object parameter adjustment procedure is a necessary operation.

The measurement object parameter adjustment is a procedure unique to D2D handover, and includes the steps of acquiring the location of the UE and adjusting the measurement object parameter. The handover decision is a procedure in which the eNB receives a measurement report to decide that the UE can perform handover. The handover preparation is a process between sending a handover request message to the original eNB and receiving a handover request response message to the target eNB. And the switching execution is a process of sending a switching command to the UE to access the target eNB for the source eNB.

The measurement object parameter adjustment is a procedure unique to D2D handover, and before handover, an eNB is to acquire which eNB serves two UEs performing D2D communication, respectively. In this embodiment, eNB1 knows that UE1 is served by eNB1, and that UE2 is also served by eNB 1. This embodiment corresponds to the scenario corresponding to fig. 2 (a), in which both UE1 and UE2 are under eNB1, and therefore no adjustment of the measurement target parameters is required.

When the information about the radio signal of the eNB2 monitored by the UE1 reaches the triggering condition for message reporting, the UE1 sends a message to report the measurement result. For example: when the UE1 monitors that the Reference Signal Received Power (RSRP) or the Reference Signal Received Quality (RSRQ) of the eNB2 meets the measurement reporting standard, it triggers measurement reporting.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 3. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, a network node (MME), and the like, and may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcasted by the neighboring eNB contains information on whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the neighboring eNB supports the D2D function, the terminal sends a message to the eNB1 and reports the message to the eNB 1; the eNB1 may also know whether the neighboring eNB supports the D2D function through a message between enbs, i.e., an X2 message, or a message between upper network entities such as eNB and MME, i.e., an S1 message, when deciding on handover. For example: the eNB1 messages information from the MME to know whether the neighboring enbs support D2D functionality.

After knowing which neighboring enbs support the D2D function, the eNB1 will determine which enbs meet the handover condition according to the information. Only enbs supporting the D2D function are eligible to be the target of handover.

When two D2D UEs are handed over simultaneously, there may be a case where resources between enbs cannot be coordinated, and therefore, the eNB needs to know the status of another D2D terminal performing D2D communication, i.e. whether another D2D terminal is in a handover state or a non-handover state. The handover state is a state from when the eNB sends a handover request message requesting handover to when the eNB receives a UE context release (UE context release) message indicating that the handover of the UE is completed. In this embodiment, since both UEs are under eNB1, eNB1 may obtain whether UE2 is in a handover state and a non-handover state. Therefore, no message interaction with other eNBs is needed.

The eNB1 determines whether to handover and which eNB to handover according to the measurement result reported by the UE1 and the conditions such as whether the eNB supports D2D communication and the state of the UE, and if a plurality of enbs satisfy the handover conditions, the eNB1 preferentially selects the serving eNB of the UE2 as the target eNB for handover of the UE 1. In this embodiment, eNB1 eventually selects eNB2 as the target eNB for handover of UE 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB2, the message carrying information related to the UE1 and the D2D of the UE2, such as: whether the UE to be handed over is a master UE. Information of a D2D Data Radio Bearer (DRB) to handover the UE. Resource information used by the D2D UE for D2D communications, and information of which eNB the UE2 is under.

After receiving the handover request message, the eNB2 first determines the location of the UE2 and which of the UE2 and the UE1 is the master UE, and thus can determine which type of handover the current D2D handover corresponds to.

For different situations, different resource allocation methods are adopted, and in this embodiment, the two UEs are served by the same eNB, and after the handover, the two UEs are served by different enbs.

The eNB2 finds the same resource subset to be allocated to the UE1 and the UE2 for D2D communication according to the radio resource situation of D2D communication allocated between the eNB1 and the eNB2, and after the eNB2 allocates the radio resource range, transmits the allocated radio resource to the eNB1 when the eNB1 returns a handover response message. If no cross-eNB D2D communication is possible between eNB2 and eNB1, eNB2 indicates a handover failure in the handover acknowledgement message.

In addition, the handover response message returned by the eNB2 to the eNB1 may also carry some other information related to D2D, for example: D2D DRB related information allowed to use and not allowed to use, which can make the UE know which DRBs can be used continuously after handover and which can not. Another example is: eNB2 communication, discovery, and measurement related information configured for UE 2; this information will be used in D2D operations related to discovery, measurement, etc. within the coverage of eNB2 after handover of the UE 1.

After receiving the handover response message, the eNB1 sends a handover command to the UE1, and after receiving the handover command message, the UE1 indicates access to the target eNB, that is, the eNB2, according to the handover command.

In this example, the UE1 is the master UE, and after accessing the eNB2, the UE1 updates the D2D communication resources according to the radio resource information allocated for D2D communication in the handover process, and the master UE, that is, the UE1, allocates the radio resources used for D2D communication to the UE1 and the UE2 within the range of the newly allocated radio resources. The UE1 and UE2 use the resource for D2D communication.

After that, the UE1 sends a radio resource control connection reconfiguration complete (rrcconnectionreconfiguration complete) message to the eNB2 indicating that the handover of the D2D UE has been completed. The eNB2 then sends a UE context release command to the eNB1 to notify the eNB1 that the handover of the D2D of the UE1 has been successfully completed, so that the eNB1 releases the context resource of the UE 1. This completes the handover procedure of the D2D UE.

Example 2, the UE to be switched is the slave UE, FIG. 4 is a schematic diagram of the switching process

D2D switching is divided into four parts of measuring object parameter adjustment, switching judgment, switching preparation and switching execution. The measurement object parameters are adjusted to be optional procedures, but obtaining the UE position is a necessary operation.

The measurement object parameter adjustment is a procedure unique to D2D handover, and includes the steps of acquiring the location of the UE and adjusting the measurement object parameter. The switching judgment is that the eNB receives the measurement report and judges the flow between the UE and the switching. The handover preparation is a process between sending a handover request message to the original eNB and receiving a handover request response message to the target eNB. And the switching execution is a process of sending a switching command to the UE to access the target eNB for the source eNB.

When the information about the radio signal of the eNB2 monitored by the UE1 reaches the triggering condition for message reporting, the UE1 sends a message to report the measurement result. For example: when the UE1 monitors that the RSRP or RSRQ of the eNB2 meets the measurement reporting standard, it triggers measurement reporting.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 4. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcasted by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the neighboring eNB supports the D2D function, the terminal sends a message to the eNB1 and reports the message to the eNB 1; the eNB1 may also know whether the neighboring eNB supports the D2D function through a message between enbs, i.e., an X2 message, or a message between upper network entities such as eNB and MME, i.e., an S1 message, when deciding on handover. E.g., eNB1, knows from the MME whether the neighboring eNB supports D2D functionality.

When two D2D UEs are handed over simultaneously, there may be a case where resources between enbs cannot be coordinated, and therefore, the eNB needs to know the status of another D2D terminal performing D2D communication, i.e. whether another D2D terminal is in a handover state or a non-handover state. The handover state is a period of state from when the eNB sends a handover request message requesting handover to when the eNB receives a UE context release message indicating that handover of the UE is completed. In this embodiment, since both UEs are under eNB1, eNB1 may obtain whether UE2 is in a handover state and a non-handover state. Therefore, no message interaction with other eNBs is needed.

The eNB1 determines whether to handover and which eNB to handover according to the measurement result reported by the UE1 and the conditions such as whether the eNB supports D2D communication and the state of the UE, and if a plurality of enbs satisfy the handover conditions, the eNB1 preferentially selects the serving eNB of the UE2 as the target eNB for handover of the UE 1.

In this embodiment, eNB1 eventually selects eNB2 as the target eNB for handover of UE 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB2, the message carrying information related to the UE1 and the D2D of the UE2, such as: whether the UE to be handed over is a master UE. Information of a D2D data radio bearer (D2D DRB) to handover the UE. Resource information used by the D2D UE for D2D communications. And which eNB the UE2 is under, etc.

In addition, the handover response message replied by the eNB2 to the eNB1 may also carry some other information related to D2D, such as information related to D2D DRBs that are allowed to be used and those that are not allowed to be used, where the message may enable the UE to know which DRBs may be continuously used after handover and which are not. Another example is: eNB2 communication, discovery, and measurement related information configured for UE 2; this information will be used in D2D operations related to discovery, measurement, etc. within the coverage of eNB2 after handover of the UE 1.

In this example, if the UE1 is a slave UE, after the UE1 accesses the eNB2, the eNB2 sends a message to the eNB1 to notify the eNB1 that the UE1 accesses the eNB 2; the eNB1 then sends a message to the UE2 informing the UE2 that communication resource updates are available, the message carrying radio resources that need to be updated. The UE2 performs D2D communication resource update according to the message, and the master UE, i.e., UE2, allocates radio resources used for D2D communication to UE1 and UE2 within the newly allocated radio resources. The UE1 and UE2 use the resource for D2D communication.

After that the UE1 sends an rrcconnectionreconfiguration complete message to the eNB2 indicating that the handover of the D2D UE has been completed. The eNB2 then sends a UE context release command to the eNB1 to notify the eNB1 that the D2D handover of the UE1 has been successfully completed, and let the eNB1 release the context resource of the UE 1. This completes the handover procedure of the D2D UE.

Example 3, the UE to be switched does not have to be the master UE or the slave UE, and fig. 5 is a schematic diagram of the switching process

The measurement object parameter adjustment is a procedure unique to D2D handover, and includes steps of acquiring the location of the UE, and adjusting the measurement object parameter. And switching judgment, namely the eNB receives the measurement report and judges the flow between the UE and the switching. Handover preparation, which is a process between sending a handover request message to an original eNB and receiving a handover request response message to a target eNB. And performing handover, namely sending a handover command to the UE for the source eNB to access to the flow between the target eNB.

The measurement object parameter adjustment is a unique procedure for D2D handover, and before handover, the eNB is to acquire which eNB serves two UEs performing D2D communication, respectively, in this embodiment, the eNB1 knows that the UE1 is served by the eNB1, and the UE2 is also served by the eNB 1. This embodiment corresponds to the scenario corresponding to fig. 2 (a), in which both UE1 and UE2 are under eNB1, and therefore no adjustment of the measurement target parameters is required.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 5. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example, the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the neighboring eNB supports the D2D function, the terminal sends a message to the eNB1 and reports the information to the eNB 1; the eNB1 may also know whether the neighboring eNB supports the D2D function through a message between enbs, i.e., an X2 message, or a message between upper network entities such as eNB and MME, i.e., an S1 message, when deciding the handover. For example: the eNB1 messages information from the MME to know whether the neighboring enbs support D2D functionality.

In this embodiment. The eNB1 eventually selects eNB2 as the target eNB for handover of UE 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB2, which carries information about the UE1 and the D2D of the UE2, e.g., whether the UE to be handed over is the master UE. Information of a D2DDRB to switch the UE. Resource information used by the D2D UE for D2D communications. And which eNB the UE2 is under, etc.

After receiving the handover request message, the eNB2 first determines the location of the UE2 and who the UE2 and the UE1 are master UEs, and thus can determine which type of handover the current D2D handover corresponds to.

For different situations, different resource allocation methods are adopted, and in the case of this embodiment, two UEs are served by the same eNB, and after the handover, the two UEs are served by different enbs.

In this embodiment, the eNB does not allocate radio resources to the UE1 and the UE2, but only notifies the D2D of the radio resource range used by the D2D communication, after the UE1 accesses the eNB2, the eNB2 sends a message to the eNB1 to notify the eNB1, and the UE1 accesses the eNB2, then the eNB2 sends a message to the UE1, and the eNB1 sends a message to the UE2 to notify the radio resource range used by the UE for the D2D communication, so that the two UEs can randomly select resources within the range to communicate.

After that the UE1 sends an rrcconnectionreconfiguration complete message to the eNB2 indicating that the handover of the D2D UE has been completed. The eNB2 then sends a UE context release command to the eNB1 to notify the eNB1 that the handover of the D2D of the UE1 has been successfully completed, so that the eNB1 releases the context resource of the UE 1. This completes the handover procedure of the D2D UE.

Example two

In this embodiment, in the second type of scenario, that is, two UEs before handover are under two enbs, and two UEs after handover are under the same eNB, the D2D terminal is handed over. In this embodiment, the procedure of switching between D2D UEs in the second type of scenario is described, and in this embodiment, the switching procedures of the master UE and the slave UE are the same.

Example 1, the UE to be switched is a master/slave UE, and FIG. 6 is a schematic diagram of the switching process

The measurement object parameter adjustment is a unique procedure for D2D handover, and before handover, the eNB will acquire which eNB serves two UEs performing D2D communication, respectively, in this embodiment, the eNB1 knows that the UE1 is served by the eNB1, and the UE2 is served by the eNB 2.

This embodiment corresponds to the scenario corresponding to fig. 2 (b), in which the UE1 is handed over from eNB1 to eNB 2. The eNB1 will adjust the parameters of the measurement objects of the UE1 according to the positions of the UE1 and the UE2 and transmit the parameters of the measurement objects to the UE1 through a message, i.e., transmit the cell offset (celllnividualoffset) parameters to the UE1 through a measurement object (MeasObjectEUTRA) message. In this embodiment, the eNB1 knows that the UE2 is in the eNB2, and the eNB1 increases the parameter value of the cellIndividualOffset parameter corresponding to the UE2 in the measObjectEUTRA message, where the value means: the cell where the UE2 is located is shifted, and the UE increases the value of Ocn corresponding to the eNB2 according to the parameter, so that the triggering condition Mn + Ofn + Ocn-Hys > Mp + Ofp + Ocp + Off entering the eNB2 in the event of A3 is more easily satisfied, and the UE1 is more easily handed over to the cell where the UE2 is located.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 6. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. For example: the eNB1 knows information from the MME whether the neighboring enbs support the D2D functionality, which is a message added newly according to this functionality. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the D2D function is supported by the neighboring eNB, the terminal sends a message to the eNB1 and reports the information to the eNB 1.

After knowing which neighboring enbs support the D2D function, the eNB1 may determine, based on the information, which enbs are eligible for handover. Only enbs supporting the D2D function are eligible to be the target of handover.

When two D2D UEs are handed over simultaneously, there may be a case where resources between enbs cannot be coordinated, so to ensure that two D2D UEs cannot be handed over simultaneously, the eNB needs to know the status of another D2D terminal performing D2D communication, i.e. whether the terminal is in a handover state or a non-handover state. The handover state is a period of state from when the eNB sends a handover request message requesting handover to when the eNB receives a UE context release message indicating that handover of the UE is completed. In the present embodiment, the eNB2 and the eNB1 may notify the counterpart UE1 and UE2 whether or not in a handover state through an X2 message. When the eNB1 finds that the UE2 is in the handover state, no handover decision will be made, and the eNB1 will make a handover decision for the UE1 only after the UE2 completes handover.

In this embodiment, the UE2 is at eNB2, and eNB1 eventually selects eNB2 as the target eNB for handover of the UE 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB2, the message carrying information related to the UE1 and the D2D of the UE2, such as: information on whether the UE to be handed over is a master UE, information on the D2D drbs to which the UE is to be handed over, resource information used by the D2D UE for D2D communication, information on which eNB the UE2 is under, and the like.

After receiving the handover request message, the eNB2 first determines the location of the UE2 and who the UE2 and the UE1 are master UEs, and accordingly can determine which type of D2D the current D2D handover belongs to, and for different situations, different resource allocation methods are adopted.

eNB2 will allocate a portion of the radio resources for eNB1 to use for D2D communications between UE1 and UE 2. After the eNB2 has allocated the radio resource range, it sends a handover response message back to the eNB1, and then transmits the allocated radio resource to the eNB 1. If no cross-eNB D2D communication is possible between eNB2 and eNB1, eNB2 indicates a handover failure in the handover acknowledgement message.

In addition, the handover response message returned by the eNB2 to the eNB1 may also carry some other information related to D2D, for example: D2D DRB related information allowed to be used and not allowed to be used, which can make the UE know which DRBs can be used continuously after handover and which are not. Another example is: eNB2 communication, discovery, and measurement related information configured for UE 2; this information will be used in D2D operations related to discovery, measurement, etc. within the coverage of eNB2 after handover of the UE 1.

After the UE1 accesses the eNB2, the eNB2 sends a message to the master UE between the UE1 and the UE2, and sends the radio resource configuration information of the D2D communication between the UE1 and the UE2, which is allocated before, to the master UE. After receiving the message, the master UE updates the D2D communication resources according to the allocated radio resource information for performing D2D communication, and the master UE, that is, UE2, allocates the radio resources used for performing D2D communication to UE1 and UE2 within the newly allocated radio resource range. The UE1 and UE2 use the resource for D2D communication.

After that, the UE1 sends an rrcconnectionreconfiguration complete message to the eNB2 indicating that the handover of the D2D UE has been completed. The eNB2 then sends a UE context release command to the eNB1 to notify the eNB1 that the handover of the D2D of the UE1 has been successfully completed, so that the eNB1 releases the context resource of the UE 1. This completes the handover procedure of the D2D UE.

Example 2, the UE to be switched is not divided into master and slave UEs, and FIG. 7 is a schematic diagram of the switching process

This embodiment corresponds to the scenario corresponding to fig. 2 (b), in which the UE1 is handed over from eNB1 to eNB 2. The eNB1 will adjust the parameters of the measurement objects of UE1 according to the location of UE1 and UE 2. And transmits the parameters of the measurement object to the UE1 through a message, i.e., transmits cellIndividualOffset parameters to the UE1 through a measObjectEUTRA message. In this embodiment, the eNB1 knows that the UE2 is in the eNB2, and the eNB1 increases the parameter value of the cellIndividualOffset parameter corresponding to the UE2 in the measObjectEUTRA message, where the value means: the cell where the UE2 is located is shifted, and the UE increases the value of Ocn corresponding to the eNB2 according to the parameter, so that the triggering condition Mn + Ofn + Ocn-Hys > Mp + Ofp + Ocp + Off entering the eNB2 in the event of A3 is more easily satisfied, and the UE1 is more easily handed over to the cell where the UE2 is located.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 7. For example, the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or the like, and may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. For example: the eNB1 knows information from the MME whether the neighboring enbs support the D2D functionality, which is a message added newly according to this functionality. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the D2D function is supported by the neighboring eNB, the terminal sends a message to the eNB1 and reports the information to the eNB 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB2, where the message carries information about the UEs 1 and D2D of the UE2, such as information about whether the UE to be handed over is the master UE, the D2DDRB of the UE to be handed over, resource information used by the D2D UE for D2D communication, and information about which eNB the UE2 is under.

In this embodiment, the eNB does not allocate radio resources to the UE1 and the UE2, but only notifies the UE1 and the UE2 of the radio resource range used by D2D communication, and after the UE1 accesses the eNB2, the eNB2 sends a message to the UE1 and the UE2 to notify the radio resource range used by the UE1 and the UE2 of the D2D communication, and the two UEs can randomly select resources within the range to communicate.

EXAMPLE III

In this embodiment, in a third type of scenario, that is, two UEs are under two enbs before handover, and two UEs are under two enbs after handover, the D2D terminal is handed over. In the third scenario, the present embodiment shows the procedure of D2D UE handover,

example 1, the UE to be switched is the main UE, FIG. 8 is a schematic diagram of the switching process

This embodiment corresponds to the scenario corresponding to fig. 2 (c), in which the UE1 is handed over from eNB1 to eNB 2. The eNB1 will adjust the parameters of the measurement objects of the UE1 according to the positions of the UE1 and the UE2, and transmit the parameters of the measurement objects to the UE1 through a message, i.e., transmit cellIndividualOffset parameters to the UE1 through a measObjectEUTRA message. In this embodiment, the eNB1 knows that the UE2 is in the eNB2, and the eNB1 increases the parameter value of the cellIndividualOffset parameter corresponding to the UE2 in the measObjectEUTRA message, where the value means: the cell where the UE2 is located is shifted, and the UE increases the value of Ocn corresponding to the eNB2 according to the parameter, so that the triggering condition Mn + Ofn + Ocn-Hys > Mp + Ofp + Ocp + Off entering the eNB2 in the event of A3 is more easily satisfied, and the UE1 is more easily handed over to the cell where the UE2 is located.

When the information about the radio signal of the eNB2 monitored by the UE1 reaches the triggering condition for message reporting, the UE1 sends a message to report the measurement result. For example, when the UE1 detects that the RSRP or RSRQ of the eNB2 meets the criterion of measurement reporting, it triggers measurement reporting.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 8. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. For example, the eNB1 may send a message to the MME to know whether the neighboring eNB supports the D2D function, which is a message added according to this function. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the D2D function is supported by the neighboring eNB, the terminal sends a message to the eNB1 and reports the information to the eNB 1.

In this embodiment, while the UE2 is in eNB2, eNB2 does not satisfy the handover condition, while eNB3 satisfies the handover condition. The eNB1 eventually selects eNB3 as the target eNB for handover of UE 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB3, the message carrying information about the UE1 and the D2D of the UE2, such as: information on whether the UE to be handed over is a master UE, information on D2D DRB of the UE to be handed over, resource information used by the D2D UE for D2D communication, and information on which eNB the UE2 is under.

After receiving the handover request message, the eNB3 first determines the location of the UE2 and who the UE2 and the UE1 are master UEs, and accordingly can determine which type of D2D the current D2D handover belongs to, and for different situations, different resource allocation methods are adopted.

In this embodiment, the eNB3 will know that the UE2 is served by the eNB2 through the handover request message, and the eNB3 will send a resource negotiation request message to the eNB2 through the X2 port for D2D communication resource negotiation. The message will carry radio resources allocated by eNB3 for use by D2D communications between UE1 and UE 2. The eNB2 replies to the resource negotiation failure in the resource negotiation response message if the resource is deemed to be unavailable; if the eNB2 considers the resource available, it replies in a resource negotiation response message that the resource negotiation was successful.

After receiving the resource negotiation response of the eNB2, the eNB3 returns a handover request response message to the eNB1, where the handover request response message carries the radio resource allocated by the eNB 3. In addition, the handover response message returned by the eNB2 to the eNB1 may also carry some other information related to D2D, for example: D2D DRB related information allowed to use and not allowed to use, which can make the UE know which DRBs can be used continuously after handover and which can not. Another example is: eNB3 communication, discovery, and measurement related information configured for UE 2; this information will be used in D2D operations related to discovery, measurement, etc. within the coverage of eNB3 after handover of the UE 1.

After receiving the handover response message, the eNB1 sends a handover command to the UE1, and after receiving the handover command message, the UE1 indicates access to the target eNB, that is, the eNB3, according to the handover command.

In this embodiment, the UE1 is the master UE, and after the UE1 accesses the eNB3, the eNB3 knows that the serving eNB of the UE2 is the eNB2 according to the previous information. When the eNB3 knows that the UE1 has accessed the eNB3, the eNB3 sends a message to the eNB2 to inform the eNB2 that the UE1 has accessed the eNB3, and the eNB2 sends a message to the UE2 to send the radio resource configuration information, which is negotiated and allocated before, for D2D communication between the UE1 and the UE2 to the UE 2. After receiving the message, the UE2 updates the D2D communication resources according to the allocated radio resource information for D2D communication, and the master UE, i.e., UE2, allocates the radio resources used for D2D communication to UE1 and UE2 within the newly allocated radio resource range. The UE1 and UE2 use the resource for D2D communication.

In this embodiment, the UE1 is a master UE, and after accessing the eNB3, the UE1 updates the D2D communication resources according to the radio resource information for D2D communication allocated in the handover process, and the master UE, that is, the UE1, allocates the radio resources used for D2D communication to the UE1 and the UE2 within the range of the newly allocated radio resources. The UE1 and UE2 use the resource for D2D communication.

After that the UE1 sends an rrcconnectionreconfiguration complete message to the eNB3 indicating that the handover of the D2D UE has been completed. The eNB3 then sends a UE context release command to the eNB1 to notify the eNB1 that the handover of the D2D of the UE1 has been successfully completed, so that the eNB1 releases the context resource of the UE 1. This completes the handover procedure of the D2D UE.

Example 2, the UE to be switched is the slave UE, FIG. 9 is a schematic diagram of the switching process

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 9. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. For example, the eNB1 may send a message to the MME to know whether the neighboring eNB supports the D2D function, which is a message added according to this function. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the D2D function is supported by the neighboring eNB, the terminal sends a message to the eNB1 and reports the information to the eNB 1.

After completing the handover decision, the eNB1 sends a handover request message to the eNB3, the message carrying information related to the UE1 and the D2D of the UE2, such as: information on whether the UE to be handed over is a master UE, information on the D2D drbs to which the UE is to be handed over, resource information used by the D2D UE for D2D communication, and information on which eNB the UE2 is under.

After receiving the resource negotiation response of the eNB2, the eNB3 returns a handover request response message to the eNB1, where the handover response message carries the radio resource allocated by the eNB 3. In addition, the handover response message returned by the eNB2 to the eNB1 may also carry some other information related to D2D, for example: D2D DRB related information allowed to use and not allowed to use, which can make the UE know which DRBs can be used continuously after handover and which can not. Another example is: eNB3 communication, discovery, and measurement related information configured for UE 2; this information will be used in D2D operations related to discovery, measurement, etc. within the coverage of eNB3 after handover of the UE 1.

In this embodiment, the UE1 is a slave UE, the UE2 is a master UE, and after the UE1 accesses the eNB3, the eNB3 knows that the serving eNB of the UE2 is the eNB2 according to the previous information. When the eNB3 knows that the UE1 has accessed the eNB3, the eNB3 sends a message to the eNB2 to inform the eNB2 that the UE1 has accessed the eNB3, and the eNB2 sends a message to the UE2 to send the radio resource configuration information, which is negotiated and allocated before, for D2D communication between the UE1 and the UE2 to the UE 2. After receiving the message, the UE2 updates the D2D communication resources according to the allocated radio resource information for D2D communication, and the master UE, i.e., UE2, allocates the radio resources used for D2D communication to UE1 and UE2 within the newly allocated radio resource range. The UE1 and UE2 use the resource for D2D communication.

After that the UE1 sends an rrcconnectionreconfiguration complete message to the eNB3 indicating that the handover of the D2D UE has been completed. The eNB3 then sends a UE context release command to the eNB1 to notify the eNB1 that the D2D handover of the UE1 has been successfully completed, and let the eNB1 release the context resource of the UE 1. This completes the handover procedure of the D2D UE.

Example 3, the UE to be switched is not divided into master and slave UEs, and FIG. 10 is a schematic diagram of the switching process

This embodiment corresponds to the scenario corresponding to fig. 2 (c), in which the UE1 is handed over from eNB1 to eNB 2. The eNB1 will adjust the parameters of the measurement objects of the UE1 according to the positions of the UE1 and the UE2, and transmit the parameters of the measurement objects to the UE1 through a message, i.e., transmit cellIndividualOffset parameters to the UE1 through a measObjectEUTRA message. In this embodiment, the eNB1 learns that the UE2 is in the eNB2, the eNB1 increases a parameter value of a cellIndividualOffset parameter corresponding to the UE2 in the measObjectEUTRA message, where the value is a cell offset corresponding to a cell in which the UE2 is located, and the UE increases a value of an Ocn corresponding to the eNB2 according to the parameter, so that in an event of the A3, a triggering condition Mn + Ofn + Ocn-Hys > Mp + Ofp + Ocp + Off entering the eNB2 is more easily satisfied, and the UE1 is more easily switched to the cell in which the UE2 is located.

The eNB1 obtains information about whether the neighboring eNB supports D2D functionality, which may be obtained before the handover decision, as shown in fig. 10. For example, the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager, an MME, or the like, and may also know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. For example, the eNB1 may send a message to the MME to know whether the neighboring eNB supports the D2D function, which is a message added according to this function. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the D2D function is supported by the neighboring eNB, the terminal sends a message to the eNB1 and reports the information to the eNB 1.

After receiving the handover request message, the eNB3 first determines the location of the UE2 and who the UE2 and the UE1 are master UEs, and accordingly can determine which type of D2D the current D2D handover belongs to. For different situations, different resource allocation methods are adopted.

After receiving the resource negotiation response of the eNB2, the eNB3 returns a handover request response message to the eNB1, where the handover request response message carries the radio resources allocated by the eNB 3. In addition, the handover response message replied by the eNB2 to the eNB1 may also carry some other information related to D2D, such as information related to D2D DRBs that are allowed to be used and those that are not allowed to be used, where the message may enable the UE to know which DRBs may be continuously used after handover and which are not. Also for example, eNB3 may be configured to communicate, discover, and measure related information for UE 2; this information will be used in D2D operations related to discovery, measurement, etc. within the coverage of eNB3 after handover of the UE 1.

In this embodiment, the eNB does not allocate radio resources to the UE1 and the UE2, but only notifies the UE1 and the UE2 of the radio resource range used by the D2D communication, and after the UE1 accesses the eNB3, the eNB3 knows that the serving eNB of the UE2 is the eNB2 according to the previous information. When the eNB3 knows that the UE1 has accessed the eNB3, the eNB3 sends a message to the eNB2 to inform the eNB2 that the UE1 has accessed the eNB3, the eNB2 sends a message to the UE2, the eNB3 sends a message to the UE1 to inform the wireless resource range used by the UE for D2D communication, and the two UEs can randomly select resources to communicate in the range.

Example four

This embodiment provides another solution for D2D handover, i.e. during the handover, the D2D user switches back to the cellular mode first and then performs the handover. In this embodiment, it is not necessary to distinguish between master and slave UEs, in this embodiment, taking the handover of the second type D2D as an example, the UE1 and the UE2 are respectively subordinate to the eNB1 and the eNB2, and the UE1 is handed over from the eNB1 to the eNB2, which is a schematic diagram of a handover flow in fig. 11.

The method comprises four parts of measurement object parameter adjustment, switching judgment, switching preparation and switching execution. Wherein, the parameters of the measuring object are adjusted to be selectable processes.

The measurement object parameter adjustment is a unique process for D2D switching, and comprises the steps of obtaining and judging whether only D2D business is stored, and adjusting the measurement object parameter. The switching judgment is that the eNB receives the measurement report and judges the flow between the UE and the switching. The handover preparation is a process between sending a handover request message to the original eNB and receiving a handover request response message to the target eNB. And the switching execution is a process of sending a switching command to the UE to access the target eNB for the source eNB.

Measurement object parameter adjustment is a procedure unique to D2D handover, before handover, eNB will acquire whether only D2D communication is stored, in this embodiment, through message query between enbs, if only D2D communication is stored, adjust the parameter of the measurement object of UE1, and transmit the parameter of the measurement object to UE1 through message, that is, transmit cellIndividualOffset parameter to UE1 through measObjectEUTRA message. The eNB1 reduces a parameter value of cellIndividualOffset parameter corresponding to the UE1 in the measObjectEUTRA message, where the value means a cell offset corresponding to the cell where the UE1 is located, and the UE increases the value of Ocp corresponding to the eNB1 according to the parameter, so that the triggering condition Mn + Ofn + Ocn-Hys > Mp + Ofp + Ocp + Off entering the eNB2 is less likely to be satisfied in an A3 event, thereby delaying the handover of the UE 1.

The eNB1 may obtain information whether the neighboring eNB supports D2D functionality, which may be obtained before a handover decision, as shown in fig. 11. Such as: the eNB1 may know whether the neighboring eNB supports the D2D function through configuration of an upper network entity such as a network manager and an MME, or may know whether the neighboring eNB supports the D2D message through a message of an X2 port or an S1 port. For example: the eNB1 knows information from the MME whether the neighboring enbs support the D2D functionality, which is a message added newly according to this functionality. The eNB1 may also obtain information whether the neighboring eNB supports the D2D function according to the terminal report. For example: the SIB message broadcast by the neighboring eNB includes information about whether the D2D function is supported, and after the terminal served by the eNB1 knows whether the D2D function is supported by the neighboring eNB, the terminal sends a message to the eNB1 and reports the information to the eNB 1.

The eNB1 will determine whether to handover or not and which eNB to handover according to the measurement result reported by the UE1, and if there are multiple enbs that satisfy the handover condition, the eNB1 may preferentially select the UE supporting D2D communication for handover. The present embodiment selects eNB2 as the target UE.

Before handover, the eNB will acquire which eNB the two UEs performing D2D communication are respectively served by. Upon completion of the handover decision, eNB1 sends a message to eNB2 informing it to switch UE2 back to cellular communication mode; eNB1 messages UE1, eNB2 messages UE2 to inform the UEs to switch back to cellular communication mode, and UE1 and UE2 switch back to cellular communication mode. When the UE2 switches back to cellular mode, eNB2 sends a message to eNB1 informing it that UE2 has switched back to cellular mode.

The eNB1 starts to perform normal cellular handover procedures, including handover preparation procedures and handover execution procedures, after confirming that both UE1 and UE2 have switched back to cellular mode.

After the UE1 switches to the eNB2, the UE1 may check whether D2D communication conditions are met between the UE1 and the UE2, and if the UE1 and the UE2 are met with D2D communication conditions, the UE1 and the UE2 may switch back to the D2D communication mode.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A method for terminal handover to support device-to-device D2D technology, the method comprising:

2. The method of claim 1, wherein the first D2D terminal is a D2D enabled user equipment served by the source communication node and is in D2D communication with a second D2D terminal.

3. The method according to claim 1 or 2, wherein the source communication node and the target communication node are base stations or cells.

4. The method of claim 1, further comprising:

5. The method of claim 4, wherein the master device refers to a D2D device with a higher priority among D2D communication nodes or a D2D device with resource management capability.

6. The method according to claim 4 or 5, wherein the source communication node controlling the first D2D terminal to switch to the target communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal, comprises:

7. The method according to claim 6, wherein the source communication node determines whether the first D2D terminal is handed over and before a target communication node of the handover, the method further comprising:

8. The method according to claim 7, wherein the measurement results comprise reference signal received power, RSRP, and/or reference signal received quality, RSRQ.

9. The method of claim 7, wherein the source communication node monitors that a serving communication node of the second D2D terminal in D2D communication with the first D2D terminal is different from the source communication node, the method further comprising:

10. The method of claim 9, wherein the source communication node obtaining serving communication node information for the second D2D terminal and a second D2D terminal when the D2D communication of the first D2D terminal is established, comprises:

11. The method according to claim 6, wherein the determining, by the source communication node, whether the first D2D terminal is handed over and a target communication node for the handover according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal comprises:

12. The method of claim 11, wherein the source communication node obtaining information whether the neighboring communication node supports the D2D function comprises:

13. The method of claim 6, further comprising:

14. The method of claim 6, wherein the source communication node handing over the first D2D terminal to the target communication node if the first D2D terminal satisfies a handoff condition and there is a suitable target communication node, comprising:

15. The method of claim 14, wherein after the handover of the first D2D terminal to the target communication node, the method further comprises:

16. The method of claim 14, wherein the target communications node sending D2D radio resource allocation information to the source communications node in a handover request response message, comprising:

17. The method of claim 15, wherein the first D2D terminal performs D2D communication resource update according to the D2D radio resource allocation information, and performs D2D communication with the second D2D terminal using the updated resources, comprising:

18. The method of claim 17, further comprising:

19. The method of claim 13, further comprising:

20. The method of claim 19, further comprising: and the source communication node sends a switching request message to the target communication node to carry out the inter-cell switching of the first D2D terminal and the second D2D terminal or the first D2D terminal.

21. A communication node is characterized in that the communication node comprises a control module, which is used for controlling the first D2D terminal to switch to an opposite communication node according to the measurement result reported by the first D2D terminal and/or the information of the second D2D terminal.

22. The communications node of claim 21, wherein said first D2D terminal is a D2D enabled user equipment served by said source communications node and is in D2D communication with a second D2D terminal; the communication node is a base station or a cell.

23. The communication node according to claim 21 or 22,

the control module is further configured to receive measurement results reported by the first D2D terminal and the second D2D terminal at the same time, and preferentially perform a handover decision operation of the first D2D terminal when the first D2D terminal is a master device.

24. The communication node according to claim 21 or 22,

the control module is configured to determine whether the first D2D terminal is switched and an opposite-end communication node of the switching according to a measurement result reported by the first D2D terminal and/or information of the second D2D terminal; when it is determined that the first D2D terminal satisfies a handover condition and there is a suitable correspondent communication node, then the first D2D terminal is handed over to the correspondent communication node.

25. The communications node of claim 24, wherein determining whether the first D2D terminal is handed off and before a correspondent node for the handover,

26. The communications node of claim 25, wherein said serving communications node monitoring said second D2D terminal in D2D communication with said first D2D terminal is different from its own communications node,

27. The communications node of claim 24, wherein the control module is further configured to reduce a cell offset corresponding to the communications node to which the first D2D terminal is subject when performing measurement configuration for the first D2D terminal when only D2D communication mode traffic and no cellular communication mode traffic is available between the first D2D terminal and the second D2D terminal.

28. The communication node of claim 27,

the control module to further notify the first D2D terminal and the second D2D terminal to switch from the D2D communication mode back to the cellular communication mode.

29. The communication node of claim 28,

the control module is further configured to send a handover request message to the peer communication node, and perform inter-cell handover between the first D2D terminal and the second D2D terminal, or the first D2D terminal.

30. A D2D terminal, wherein the D2D terminal includes a handover module, configured to handover to a second communication node under the control of a first communication node according to the measurement result reported by the D2D terminal and/or the information of another D2D terminal.

31. The D2D terminal of claim 30, wherein the D2D terminal is a D2D enabled user equipment served by the first communication node and in D2D communication with the other D2D terminal.

32. The D2D terminal of claim 30 or 31,

the handover module is further configured to report a measurement result to the first communication node simultaneously with another D2D terminal, and accept a handover decision operation performed by the first communication node when the D2D terminal to which the handover module belongs is a master device.

33. The D2D terminal of claim 32,

the switching module is further configured to report the measurement result and/or the information of the another D2D terminal to the first communication node, and switch to the second communication node under the control of the first communication node when it is determined that the D2D terminal of the switching module itself meets the switching condition and a suitable peer communication node exists.

34. The D2D terminal of claim 33, wherein the D2D terminal is not the same as a serving communication node of the other D2D terminal,

35. The D2D terminal of claim 33, wherein after the D2D terminal switches to the second communication node,

36. The D2D terminal of claim 35,

the switching module is further configured to switch from the D2D communication mode back to the cellular communication mode after receiving the notification from the first communication node.

37. A terminal switching system supporting D2D technology, characterized in that the system comprises a communication node according to any of claims 21-29 and a D2D terminal according to any of claims 30-36.