CN108632878B - Base station switching method for terminal - Google Patents
Base station switching method for terminal Download PDFInfo
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- CN108632878B CN108632878B CN201710186482.8A CN201710186482A CN108632878B CN 108632878 B CN108632878 B CN 108632878B CN 201710186482 A CN201710186482 A CN 201710186482A CN 108632878 B CN108632878 B CN 108632878B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/08—Reselecting an access point
Abstract
The invention provides a base station switching method for a terminal, which comprises the following steps: the terminal receives a switching command from a source base station; the terminal and the target base station interact an uplink/downlink data PDCP status report; and after the interaction of the uplink/downlink data PDCP status reports is finished, the terminal and the target base station transmit the uplink/downlink data. The invention can realize the information interaction of the PDCP status report of the uplink/downlink data in the process of establishing the uplink synchronization between the terminal and the target base station, and immediately transmit the uplink/downlink data, thereby achieving the technical effects of quickly interacting with the target base station and reducing the time delay of the switching interruption.
Description
Technical Field
The present invention relates to the field of communications and information technologies, and in particular, to a base station handover method for a terminal.
Background
With the continuous development of wireless communication technology, users have made more urgent demands for ultra-high traffic density, ultra-high connection density, and ultra-high mobility. For this reason, following the third generation mobile communication Technology and the fourth generation mobile communication Technology, the third generation partnership project (3GPP) will introduce a fifth generation mobile communication (5G) Technology, i.e., a New Radio Access Technology in 3GPP (NR) Technology having a larger data capacity and a faster data processing speed, to cope with the demand for a larger data amount and the demand for a smaller transmission delay. In the fifth generation mobile communication technology, due to the diversification of services, a higher demand is placed on the interruption delay of the handover process.
At present, in the conventional handover process, data interaction is usually performed after a terminal establishes connection with a target base station, and if data interaction is performed while maintaining connection with a source serving cell all the time and the signal quality of the source serving cell is continuously deteriorated, the source serving cell can gradually fail to serve the terminal, so that service interruption is caused, a long interruption time delay is caused, and the requirement of a user on data access continuity cannot be met.
Therefore, in order to meet the requirement of the user for reducing the interruption delay in the handover process, a base station handover method needs to be designed, so that the terminal can quickly perform data interaction with the target base station after receiving the handover command, and the interruption delay in handover is reduced.
Disclosure of Invention
The base station switching method for the terminal provided by the invention can be used for aiming at the defects of the prior art, so that the terminal can quickly establish uplink synchronization and perform data interaction with a target base station after receiving a switching command, and the switching interruption time delay close to 0ms is realized.
The invention provides a base station switching method for a terminal, which comprises the following steps:
the method comprises the following steps: the terminal receives a switching command from a source base station;
step two: the terminal and a target base station interact an uplink/downlink data PDCP status report;
step three: and after the uplink/downlink data PDCP status report interaction is finished, the terminal and the target base station transmit uplink/downlink data.
Optionally, the foregoing step includes the terminal sending a preamble and a downlink PDCP status report to the target base station.
Optionally, the above step two includes that the target base station sends a random access response and an uplink PDCP status report to the terminal.
Optionally, the third step includes that the target base station sends downlink data to the terminal after the target base station receives the downlink PDCP status report sent by the terminal.
Optionally, the downlink data is forwarded downlink data received by the target base station from the source base station.
Optionally, the third step includes that the terminal sends uplink data to the target base station after receiving the uplink PDCP status report sent by the target base station.
Optionally, the source base station or the target base station triggers the forwarding of the downlink data.
Optionally, after the first step is completed, the source base station instructs the target base station to start data forwarding.
Optionally, in the second step, after receiving the random access message sent by the terminal, the target base station sends a data forwarding request to the source base station, and after receiving the data forwarding request, the source base station feeds back a data forwarding response to the target base station and starts to forward data to the target base station.
Optionally, the data forwarding includes that the source base station feeds back the receiving state of the uplink data and the sequence number information of the downlink data to the target base station, and forwards the corresponding downlink data to the target base station.
The base station switching method for the terminal provided by the embodiment of the invention can realize the information interaction of the PDCP status report of the uplink/downlink data in the process of establishing uplink synchronization between the terminal and the target base station, and immediately transmits the uplink/downlink data after the terminal and the target base station receive the PDCP status report, thereby achieving the technical effect of reducing the switching interruption time delay.
Drawings
FIG. 1 is a flow diagram of a handover execution phase in the 5G NR technique;
FIG. 2 is a flow chart of a handover execution phase according to an embodiment of the present invention;
FIG. 3 is a simplified downlink data PDCP status report according to an embodiment of the present invention;
fig. 4 is a simplified uplink data PDCP status report according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the LTE handover process, the uplink/downlink data interaction process can be performed only after the terminal and the target cell complete the uplink synchronization process. The switching interruption time delay is long, and the requirement of 0ms interruption time delay of 5G NR switching cannot be met. The fifth generation communication technology proposes conditional Handover (Condition Handover). Specifically, the threshold for measurement reporting of the terminal may be relaxed, and the source serving cell may be notified in advance to trigger the handover preparation process of the target cell. The target cell may instruct the terminal to perform a handover condition, and when the instructed condition is satisfied, the terminal starts a handover procedure to the target cell.
Fig. 1 shows a flow diagram of a handover execution phase in the 5G NR technique discussed at the present stage. Firstly, a source base station distributes downlink resources to UE, sends a switching command with mobile control information to the UE, and informs the UE to execute a switching process, and at the moment, the UE can continuously maintain link connection and uplink and downlink data interaction with a source service cell. Step S11 is then executed, and the UE establishes synchronization with the target base station. At S12, the target base station sends the allocated uplink grant to the UE, while indicating the UE uplink Timing Advance (TA). At S13, the UE returns a handover complete message to the target base station. And then the UE and the target base station start to carry out uplink/downlink data interaction. At step S14, the target cell sends a handover complete indication to the source serving cell, requesting the source serving cell to perform data forwarding. The source serving cell sends an SN Status Transfer signaling (SN Status Transfer) to the target cell at S15, and notifies the target cell to start data forwarding, and the source cell forwards the data packet to the target cell. Specifically, the SN status transition signaling includes, but is not limited to, transferring PDCP sequence numbers, thereby enabling the target base station to obtain the data transfer situation of the source base station. The target cell receives the data forwarding response message and obtains the data packet forwarded by the source serving cell, and in step S16, notifies the terminal to interrupt the connection with the source serving cell. And then, the uplink and downlink data transmission process between the terminal and the target cell is carried out.
In the base station switching mode of the 5G NR technology, when the UE establishes uplink synchronization with the target cell, if the link connection with the source serving cell is maintained and data interaction is performed, the UE switches to perform data interaction with the target cell after successful handover to the target cell. In the process of performing handover by the UE, as the quality of the signal of the UE in the source serving cell continuously deteriorates, the source serving cell may not serve the terminal, thereby causing service interruption. In order to meet the requirement of 0ms switching interruption time delay of the 5G NR technology, the invention provides a base station switching method.
Fig. 2 shows a flow chart of the handover execution phase of the present invention. Optionally, in step S21, the source base station sends an SN status transition signaling to the target base station, and notifies the target base station to start data forwarding. Specifically, the SN status transition signaling includes, but is not limited to, transferring PDCP sequence numbers, thereby enabling the target base station to obtain the data transfer situation of the source base station. In step S22, the UE sends a Preamble, a Packet Data Convergence Protocol (PDCP) status report, and optionally Data to the target base station, specifically, the UE sends a downlink PDCP status report while sending the Preamble specified by the target cell to the target cell, and indicates a receiving status of the downlink Data to the target cell. Typically, the downlink data receiving status indicated by the UE to the target cell includes, but is not limited to, a PDCP status report assembled by the UE into downlink data according to the receiving condition of the downlink data sent by the source serving cell, and sent to the target cell while sending the preamble; further, after the UE transmits the preamble, the UE may monitor a Physical Downlink Control Channel (PDCCH) to receive Downlink data transmitted by the target cell. Optionally, at step S23, the target base station makes a data forwarding request to the source base station, and after receiving the request, the source base station responds to the target base station at step S24, typically, the source base station may implement a response by sending an SN status migration signaling. At step S25, the target base station sends a random access response to the UE, including allocating an uplink grant, indicating a timing advance TA, and sending an uplink PDCP status report to indicate a reception status of uplink data to the UE.
Specifically, after receiving the Preamble sent by the UE in step S22 and receiving the downlink PDCP status report sent by the UE, the target cell starts sending downlink data to the terminal from the first unreceived data packet of the UE according to the indication information of the PDCP status report. Specifically, the target cell assembles an uplink data PDCP status report according to the reception status of the uplink data indicated by the source serving cell at step S24, and transmits the random access response to the UE at the same time as transmitting the random access response at step S25. Specifically, the UE sends, according to the received first unreceived uplink data packet information indicated by the PDCP status report sent by the target base station, the first unreceived uplink data packet to the target cell in the uplink grant carried in the random access response message sent by the target cell.
Further, the sending process of the downlink data PDCP status report at step S22 according to an embodiment of the present invention includes: firstly, UE receives a switching command sent by a source service cell, and acquires access information of a target cell, wherein the access information includes but is not limited to resources such as a special Preamble (Preamble), a radio network temporary identifier (C-RNTI), data forwarding and the like which are pre-designated by a target base station; secondly, the UE starts to execute switching, assembles a PDCP status report according to the receiving condition of downlink data sent by the source service cell, then sends a Preamble code on a corresponding PRACH to carry out an uplink synchronization process with a target cell, and simultaneously sends the assembled PDCP status report at a pre-designated resource position.
The simplified downlink data PDCP status report is shown in fig. 3, where the FMS is used to indicate the sequence number of the first incorrectly received downlink data packet, and the PDU type is a protocol data unit type.
Specifically, the pre-specified resource location may be, but is not limited to, a resource associated with a Preamble or PRACH resource, and corresponding data can be received on the associated resource by receiving the Preamble. Typically, the association relationship between the UE and the target base station may be agreed, and may be completed without indication or configuration. In particular, to avoid wasting the pre-specified resources, the pre-specified resources should be within a suitable size level. Thus, the UE may choose to report the simplified PDCP status report, e.g., only indicate the sequence number of the first incorrectly received PDCP data packet. After receiving the PDCP status report sent by the UE, the target cell may send downlink data to the UE according to the first unsuccessfully received packet sequence number indicated by the information of the PDCP status report if it has received data forwarded by the source serving cell.
Further, in an embodiment of the present invention, in the step S25, the process of sending the uplink data PDCP status report is specifically that, in step S25, after receiving the Preamble and the downlink PDCP status report sent by the UE, the target cell assembles an uplink data PDCP status report according to the receiving status of the uplink data indicated by the source serving cell, and sends the uplink data PDCP status report to the UE while sending the random access response. And after receiving the random access response message, the UE can send uplink data according to the uplink authorization indicated by the random access response message.
Fig. 4 shows an uplink data PDCP status report, where the FMS is used to indicate a sequence number of a first incorrectly received uplink data packet, the Bitmap is used to indicate a reception condition of a data packet after the first incorrectly received uplink data packet, and the PDU is a protocol data unit.
Typically, the target cell may obtain the receiving state of the uplink data indicated by the source serving cell by the following method: in step S21, after sending the handover command to the UE, the source serving cell sends a data forwarding indication to the target cell, and notifies the target cell of the receiving condition of the uplink data of the terminal from the source serving cell, and the target cell assembles a downlink data PDCP status report according to the information indicated by the source serving cell.
Optionally, in steps S23 and S24, in order to reduce the amount of data that the target cell buffers the data forwarded by the source serving cell, after the target cell receives the Preamble sent in step S22, the target cell sends a data forwarding request message to the source serving cell in step S23, and after the source serving cell receives the data forwarding request message, the source serving cell sends a response message to the target cell in step S24 according to the receiving condition of the uplink data of the UE. The target cell assembles an uplink data PDCP status report at step S25 according to the information indicated by the source serving cell. The steps S23 to S24 may reduce the amount of unnecessary buffered data, but there is a certain delay due to the need of information interaction between the source serving cell and the target cell, and if the random access response window length configuration is not appropriate, the sending of the uplink data PDCP status report may be affected.
Specifically, the source serving cell feeds back the receiving state of the uplink data and the sequence number information of the downlink data to the target cell, and forwards the corresponding downlink data to the target cell.
The base station switching method for the terminal can realize the information interaction of the PDCP status report of the uplink/downlink data in the process of establishing uplink synchronization between the terminal and the target base station, and immediately transmits the uplink/downlink data after the terminal and the target base station receive the PDCP status report, thereby reducing the switching interruption time delay, improving the efficiency of information communication and improving the experience of users.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (8)
1. A base station switching method for a terminal, comprising:
the method comprises the following steps: a source base station sends SN state migration signaling to a target base station;
step two: the terminal receives a switching command from the source base station, acquires access information of the target base station, and sends a lead code and a downlink PDCP status report to the target base station;
step three: the target base station sends a data forwarding request to the source base station;
step four: the source base station sends an SN state migration signaling to the target base station to realize response;
step five: the target base station distributes uplink authorization and indication TA to the terminal and sends an uplink PDCP status report;
step six: the terminal feeds back a switching completion message to the target base station;
step seven: and the terminal and the target base station transmit uplink/downlink data.
2. The base station switching method of claim 1, wherein the seventh step comprises the target base station sending downlink data to the terminal after the target base station receives a downlink PDCP status report sent by the terminal.
3. The base station switching method according to claim 2, wherein the downlink data is forwarded downlink data received by the target base station from the source base station.
4. The base station switching method of claim 1, wherein the seventh step comprises the terminal sending uplink data to the target base station after the terminal receives the uplink PDCP status report sent by the target base station.
5. The base station switching method according to claim 3, wherein the source base station or the target base station triggers the forwarding of the downlink data.
6. The base station switching method according to claim 5, wherein after the step two is completed, the source base station instructs the target base station to start data forwarding.
7. The base station switching method according to claim 5, wherein in said step two, after receiving the random access message sent by the terminal, the target base station sends a data forwarding request to the source base station, and after receiving the data forwarding request, the source base station feeds back a data forwarding response to the target base station and starts to forward data to the target base station.
8. The base station switching method according to claim 6 or 7, wherein the data forwarding comprises the source base station feeding back the receiving status of the uplink data and the sequence number information of the downlink data to the target base station, and forwarding the corresponding downlink data to the target base station.
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| CN101048001A (en) * | 2006-06-22 | 2007-10-03 | 华为技术有限公司 | Switchover control method |
| CN101415219A (en) * | 2007-10-19 | 2009-04-22 | 华为技术有限公司 | Method, system and apparatus for processing data |
| CN101668320A (en) * | 2008-09-01 | 2010-03-10 | 普天信息技术研究院有限公司 | Method for reducing handover delay in long term evolution systems |
| CN105578548A (en) * | 2007-09-29 | 2016-05-11 | 华为技术有限公司 | Downlink and uplink data packet forwarding method based on S1 handover and evolution base station |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101048001A (en) * | 2006-06-22 | 2007-10-03 | 华为技术有限公司 | Switchover control method |
| CN105578548A (en) * | 2007-09-29 | 2016-05-11 | 华为技术有限公司 | Downlink and uplink data packet forwarding method based on S1 handover and evolution base station |
| CN101415219A (en) * | 2007-10-19 | 2009-04-22 | 华为技术有限公司 | Method, system and apparatus for processing data |
| CN101668320A (en) * | 2008-09-01 | 2010-03-10 | 普天信息技术研究院有限公司 | Method for reducing handover delay in long term evolution systems |
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