CN101198155A - Handover data transmission method, system, target evolved base station and user equipment - Google Patents

Abstract

The embodiment of the present invention discloses a data transmission method during handover, including: the target eNB sends a timing advance to the user equipment UE, and sends user data to the UE before receiving the user data transmitted by the MME/UPE; the UE acquires The timing of sending by the target eNB is advanced, and the user data sent by the target eNB is received. The embodiment of the present invention also discloses a handover data transmission system, a target evolved base station and user equipment. The target eNB is used to send a timing advance to the UE, and before receiving user data transmitted by the MME/UPE, to the UE Sending user data; the UE is used to receive the user data sent by the target eNB after acquiring the timing advance sent by the target eNB. Utilizing the method, system, target evolved base station and user equipment provided by the embodiments of the present invention can reduce the interruption time of user data transmission and the transmission delay in the handover process.

Description

Handover data transmission method, system, target evolved base station and user equipment

technical field

The present invention relates to wireless communication technology, in particular to a data transmission method, system, target evolved base station (eNB) and user equipment in handover.

Background technique

The goals and requirements of the Long Term Evolution (LTE, Long Term Evolution) of the Universal Terrestrial Radio Access Network mainly include requirements in terms of performance, deployment, evolution, radio resource management, and complexity. An important requirement in terms of performance is to reduce latency. At present, the transmission delay in the wireless network of the 3GPP system is very large, which cannot meet the requirements of delay-sensitive services. In order to solve this problem, the Enhanced Universal Terrestrial Radio Access Network (UTRAN), referred to as E-UTRAN, proposes the following standards: the delay of the user plane is less than 5 milliseconds, and the transition time of the control plane from the sleep state to the active state is less than 50 milliseconds. The transition time from the resident state to the active state should be less than 100 milliseconds.

Handover is the most important part of the entire radio resource management, and handover delay is an important indicator of system mobility management performance. The handover performance of the LTE system directly affects the performance of the entire network.

Fig. 1 is the flow chart of the first kind of wireless network switching method in the prior art, in the figure, the solid line with the arrow represents the signaling transmission, and the dotted line with the arrow represents the data transmission, and this process includes the following steps:

In step 101, a user equipment (UE) sends a measurement report to a source evolved base station (eNB) according to certain rules, such as system information.

Step 102, the source eNB determines the target eNB to be handed over and the target cell according to the received measurement report and radio resource management (RRM) information, and sends handover request information carrying UE context information to the determined target eNB.

Step 103, the target eNB prepares for handover, and sends new handover related parameters to the source eNB, including C_RNTI, access parameters, system information blocks (SIBs, System Information Blocks), etc. After the source eNB receives the new handover related parameters, Start transmitting user data to the target eNB.

Step 104, the source eNB sends a handover command to the UE carrying necessary handover parameters, the handover necessary parameters include: new C_RNTI, possible start time, and SIBs of the target eNB. The UE receives the handover command, and after the handover start time provided by the handover command arrives, separates from the source eNB and the source cell, and performs step 105 .

When the UE receives the handover command carrying the necessary handover parameters sent by the source eNB, it may further confirm the reception of the handover command through a radio link control (RLC) confirmation process.

Step 105, the UE performs synchronization with the target eNB, and starts to request uplink (UL) timing advance from the target eNB.

Step 106, the target eNB sends the UL configuration and timing advance to the UE.

In step 107, the UE receives the UL configuration and timing advance sent by the target eNB, and sends a handover confirmation command to the target eNB. For the UE, the handover process is completed.

The target eNB may further confirm the receipt of the handover confirmation command through the RLC confirmation procedure.

Step 108: After the target eNB completes the handover, it notifies the source eNB that the handover is successful, and notifies the mobility management entity/user plane entity (MME/UPE) to update the positioning information of the UE, where MME/UPE is a network device composed of a combination of MME and UPE .

At this time, the source eNB can clear the previously successfully transmitted data in its own buffer. If there is still untransmitted data in the buffer of the source eNB, or the MME/UPE is still transmitting data to the source eNB, the source eNB can still continue to transmit user data to the target eNB.

After the target eNB notifies the MME/UPE to update the positioning information of the UE, the MME/UPE can directly transmit data to the target eNB.

In step 109, the MME/UPE transmits data to the target eNB, and the UE starts to receive user data from the target eNB.

In the handover method shown in FIG. 1 , only after the MME/UPE starts to directly transmit data to the target eNB, the UE starts to receive user data from the target eNB, thus resulting in a longer interruption time of user data. At the same time, before the MME/UPE directly transmits user data to the target eNB, all the data is buffered in the target eNB, so the buffering capability of the target eNB is very high, especially when multiple users switch at the same time, it is likely to be due to Buffering problems lead to congestion, and once congestion occurs, it will inevitably lead to further increase in delay. And because the amount of data buffered in the target eNB is large, it will also cause the target eNB to spend more time performing reordering, thereby causing an increase in delay.

In addition, after the UE handover described in step 107 is completed, there may still be data received by the source eNB, and then the source eNB transmits the data to the target eNB, which will not only lead to waste of resources, but also increase out-of-sequence data. Thereby causing a certain impact on the delay.

FIG. 2 is a flow chart of the second wireless network switching method in the prior art. In the figure, a solid line with arrows represents signaling transmission, and a dotted line with arrows represents data transmission. The process includes:

Step 201, the UE sends a measurement report to the source eNB according to certain rules, such as system information, etc.;

Step 202, the source eNB determines the target eNB and the target cell to be handed over according to the measurement report and the RRM information, and transmits handover request information carrying UE context information to the target eNB.

In step 203, after the target eNB receives the handover request information sent by the source eNB, the UE or the target eNB estimates that the timing advances and prepares for handover. At the same time, the target eNB sends new handover related parameters and timing advance to the source eNB, wherein the handover related parameters include: C_RNTI and some other parameters, such as access parameters, SIBs, etc. After receiving the handover related parameters, the source eNB starts to transmit user data to the target eNB.

Step 204, the source eNB sends a handover command to the UE carrying necessary handover parameters, the handover necessary parameters include: timing advance, new C_RNTI, possible start time, and SIBs of the target eNB. The UE receives the handover command, and after the handover start time provided by the handover command arrives, separates from the source eNB and the source cell, and performs step 205 .

In step 205, the UE starts to receive user data from the target eNB, and feeds back the receiving situation of the user data to the target eNB.

In step 206, the target eNB notifies the source eNB that the handover is successful.

In this way, the source eNB can clear previously successfully transmitted data from its own buffer. If the source eNB still has some user data in the buffer, or the MME/UPE is still transmitting user data to the source eNB, the source eNB can continue to transmit user data to the target eNB.

In step 207, the target eNB instructs the MME/UPE to update the location information of the UE, so that the MME/UPE can directly transmit user data to the target eNB.

As mentioned above, the handover method shown in Figure 2 achieves the purpose of reducing the user data interruption time by using the target eNB to estimate the timing ahead in advance, or the UE to automatically estimate the timing ahead, but the target eNB estimates the timing ahead or the UE automatically estimates the timing to advance All must be realized under the condition of a synchronous network, so the application of the handover method shown in Figure 2 has relatively large limitations.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a data transmission method during handover, which reduces the interruption time of user data transmission and the transmission delay in the handover process.

Another main purpose of the present invention is to provide a data transmission system during switching, which can reduce the interruption time of user data transmission and the transmission delay during the switching process.

The third main purpose of the present invention is to provide a target evolved base station, which can reduce the interruption time of user data transmission and the transmission delay in the handover process.

The fourth main object of the present invention is to provide a user equipment capable of reducing the interruption time of user data transmission and the transmission delay during handover.

In order to achieve the first aspect of the above object, the present invention provides a data transmission method during handover, the method comprising:

A. The target evolved base station eNB sends a timing advance to the user equipment UE, and sends user data to the UE before receiving the user data transmitted by the mobility management entity/user plane entity MME/UPE;

B. The UE obtains the timing advance sent by the target eNB, and receives the user data sent by the target eNB.

In order to achieve the second aspect of the above object, the present invention provides a handover data transmission system, the system includes: UE, target eNB,

The target eNB is used to send a timing advance to the UE, and send user data to the UE before receiving the user data transmitted by the MME/UPE;

The UE is configured to receive the user data sent by the target eNB after acquiring the timing advance sent by the target eNB.

In order to achieve the third aspect of the above object, the present invention provides a target evolved base station, the target evolved base station at least includes: a timing advance sending module, a user data sending module,

The timing advance sending module is configured to send timing advance to UE, and notify the user data sending module after sending;

The user data sending module is configured to start sending user data to the UE after receiving the notification sent by the timing advance sending module and before receiving the user data sent by the MME/UPE.

In order to achieve the fourth aspect of the above object, the present invention provides a user equipment, the user equipment at least includes a timing advance acquisition module, a user data receiving module,

The timing advance acquisition module is configured to acquire the timing advance sent by the target eNB, and notify the user data receiving module;

The user data receiving module is configured to receive the user data from the target eNB after receiving the notification sent by the timing advance obtaining module.

The method, system, target evolved base station, and user equipment provided by the embodiments of the present invention for reducing transmission delay during handover start to send the eNB to the UE before receiving the user data sent by the MME/UPE after advancing the timing of the transmission to the UE. The UE sends the user data, which realizes the purpose of reducing the interruption time of user data transmission and the transmission delay in the handover process.

Description of drawings

FIG. 1 is a flowchart of a first wireless network switching method in the prior art;

FIG. 2 is a flowchart of a second wireless network switching method in the prior art;

FIG. 3 is a flowchart of a data transmission method in handover according to an embodiment of the present invention;

FIG. 4 is a structural diagram of a data transmission system in handover according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings.

In the handover data transmission method and system provided by the embodiments of the present invention, the target eNB starts to send user data to the UE before receiving the user data sent by the MME/UPE after the timing of sending the target eNB to the UE is advanced, thereby realizing the reduction of user data The purpose of the transmission interruption time and the transmission delay in the handover process, and reduce the user data buffered in the target eNB.

The data transmission method in handover provided by the embodiment of the present invention includes the following steps:

A. The target eNB sends a timing advance to the user equipment UE, and sends user data to the UE before receiving the user data transmitted by the mobility management entity/user plane entity MME/UPE;

B. The UE obtains the timing advance sent by the target eNB, and receives the user data sent by the target eNB.

In order to further effectively reduce the buffered data in the target eNB, after receiving the user data sent by the target eNB in step B of the embodiment of the present invention, the UE may further include:

The UE sends a notification that the user data has been correctly received to the target eNB;

After receiving the notification sent by the UE that the user data has been correctly received, the target eNB clears the user data in its own buffer that the UE has correctly received.

In order to reduce the amount of user data transferred from the source eNB and effectively improve the utilization rate of resources, after the UE in step B of the embodiment of the present invention obtains the advance timing of the target eNB transmission, it may also include: the UE notifies the target eNB that the handover is completed;

After the target eNB confirms that the handover of the UE is completed, before notifying the source eNB that the handover is successful, the target eNB notifies the MME/UPE to update the positioning information of the UE, and the MME/UPE stops transmitting user data to the source eNB , start transmitting user data to the target eNB.

Fig. 3 is a flow chart of the data transmission method in handover according to the embodiment of the present invention. This embodiment describes the best implementation of the data transmission method in handover in the present invention, that is, after the target eNB sends the timing advance to the UE, it starts immediately Send user data to the UE, and after the UE receives the timing advance sent by the target eNB, it will immediately start receiving the user data sent by the target eNB, so the interruption time of user data transmission can be minimized.

In Fig. 3, a solid line with an arrow represents signaling transmission, and a dotted line with an arrow represents data transmission, and the flow includes the following steps:

In step 301, the UE sends a measurement report to the source eNB according to certain rules, such as system information.

Step 302, the source eNB determines the target eNB to be handed over according to the received measurement report and RRM information, and sends handover request information carrying UE context information to the determined target eNB.

Step 303, the target eNB prepares for handover, and sends new handover related parameters to the source eNB, including C_RNTI, access parameters, SIBs, etc. After receiving the new handover related parameters, the source eNB starts to transmit user data to the target eNB.

In step 304, the source eNB sends a handover command carrying necessary handover parameters to the UE. The handover necessary parameters include: new C_RNTI, possible start time, and SIBs of the target eNB. The UE receives the handover command, and after the handover start time provided by the handover command arrives, separates from the source eNB and the source cell, and performs step 305 .

When the UE receives the handover command carrying the necessary handover parameters sent by the source eNB, it may further confirm the reception of the handover command through a radio link control (RLC) confirmation procedure.

Step 305, the UE performs synchronization with the target eNB, and starts to request the uplink (UL) timing advance to the target eNB, the target eNB receives the request sent by the UE, sends the UL configuration and timing advance to the UE, and immediately starts to send the UL configuration and timing advance to the UE. data.

In step 306, the UE acquires the UL configuration and timing advance sent by the target eNB, and starts to receive user data sent by the target eNB.

After the UE correctly receives the user data transmitted by the target eNB, the UE can send a notification that the user data has been correctly received to the target eNB; after receiving the notification that the user data has been correctly received sent by the UE, the target eNB can clear its own buffer User data that has been correctly received by the UE.

Step 307, after the UE obtains the UL configuration and timing advance sent by the target eNB, the UE sends a handover confirmation command to the target eNB, and for the UE, the handover process is completed.

The target eNB may further confirm the receipt of the handover confirmation command through the RLC confirmation procedure.

Step 308, after the target eNB receives the handover confirmation command sent by the UE, it notifies the MME/UPE to update the location information of the UE. After receiving the notification, the MME/UPE stops sending user data to the source eNB after updating the location information of the UE, and starts sending user data to the source eNB. The target eNB sends user data.

After the target eNB receives the handover confirmation command sent by the UE, it notifies the MME/UPE to update the positioning information of the UE, so that the MME/UPE can stop sending data to the source eNB as soon as possible, and the MME/UPE can directly send user data to the target eNB the goal of.

Step 309, after the target eNB completes the handover, it notifies the source eNB that the handover is successful.

The source eNB may clear previously successfully transmitted data in its own buffer. If there is still untransmitted data in the buffer of the source eNB, the source eNB can still continue to transmit this part of untransmitted user data to the target eNB.

Step 310, the MME/UPE transmits data to the target eNB.

It can be seen from the process shown in Figure 3 that the UE and the target eNB are synchronized, and start receiving user data buffered in the target eNB from the target eNB immediately after obtaining the timing advance, which not only reduces the interruption time of user data transmission, but also reduces the buffer load. In this embodiment, after the UE has correctly received the user data transmitted by the target eNB, the data buffered in the target eNB that the UE has correctly received is cleared, thereby further effectively reducing the buffer load of the target eNB. Congestion occurs when handovers are performed at the same time. Since the amount of data in the buffer of the target eNB is greatly reduced, the out-of-order data generated when the MME/UPE starts to transmit data directly to the target eNB will also be greatly reduced, thereby effectively reducing the workload of the eNB to perform reordering and reducing the sorting time. Thereby reducing the delay of user data transmission.

At the same time, when the target eNB receives the handover confirmation command sent by the UE, it notifies the MME/UPE to update the positioning information of the UE, so that the MME/UPE stops sending data to the source eNB as soon as possible, thereby reducing the data transferred from the source eNB It can effectively improve the utilization rate of resources.

In addition, compared with the handover method in the prior art shown in Figure 2, the method for reducing the transmission delay provided by the embodiment of the present invention does not require network synchronization, that is, it does not require the target eNB to estimate the timing advance in advance, or the UE to automatically estimate The timing is advanced, so it has a wider range of use.

The present invention also provides a wireless network switching system. As shown in FIG. 4 , the system includes: UE, source eNB, target eNB and MME/UPE.

Wherein, the target eNB is used to send the timing advance to the UE, and send the user data to the UE before receiving the user data transmitted by the MME/UPE;

The UE is configured to start receiving the user data sent by the target eNB after acquiring the timing advance sent by the target eNB.

The UE is further configured to send a notification that the user data has been correctly received to the target eNB; the target eNB is further configured to receive the notification that the user data has been correctly received sent by the UE, and clear the user data that the UE has correctly received in its own buffer.

The UE is also used to notify the target eNB of the completion of the handover; the target eNB is also used to notify the MME/UPE to update the positioning information of the UE after confirming the completion of the UE handover and before notifying the source eNB of the successful handover; the MME/UPE is used to update the positioning information of the UE, Stop transmitting user data to the source eNB, and start transmitting user data to the target eNB.

The target evolved base station of the wireless network system at least includes: a timing advance sending module and a user data sending module; the user equipment at least includes: a timing advance acquiring module, and a user data receiving module.

The timing advance sending module is used to send timing advance to the timing advance acquisition module, and notify the user data sending module;

After receiving the notification sent by the timing advance sending module, the user data sending module starts sending user data to the user data receiving module before receiving the user data sent by the MME/UPE.

The target evolved base station may further include: a buffer clearing module, configured to receive the data receiving confirmation information sent by the data receiving confirming module, and clear the user data in the buffer that has been correctly received by the user data receiving module.

The target eNB may also include an information update notification module, which is used to receive the handover completion confirmation information sent by the handover completion notification module, and notify the MME/UPE to update the UE's positioning information before notifying the source eNB of the successful handover.

The timing advance acquisition module is used to obtain the timing advance sent by the timing advance sending module, and notify the user data receiving module;

The user data receiving module is configured to receive the user data from the user data sending module after receiving the notification sent by the timing advance obtaining module.

The user equipment may further include: a data receiving confirmation module, the user data receiving module is a first user data receiving module, and the first user data receiving module is configured to notify Data reception confirmation module;

The data receiving confirmation module is connected to the first user data receiving module, and is used to send data receiving confirmation information to the buffer clearing module when the user data receiving module successfully receives the user data sent by the user data sending module.

The user equipment may further include: a switching completion notification module,

The timing advance acquisition module is a first timing advance acquisition module, and the first timing advance acquisition module is used to obtain the timing advance sent by the timing advance sending module, and notify the user data receiving module and the switching completion notification module;

The handover completion notification module is configured to receive the notification sent by the first timing advance acquisition module, and send handover completion confirmation information to the information update notification module.

In a word, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (14)

1. A data transmission method in handover, characterized in that the method comprises: A. The target eNB sends a timing advance to the user equipment UE, and sends user data to the UE before receiving the user data transmitted by the mobility management entity MME/user plane entity UPE; B. The UE obtains the timing advance sent by the target eNB, and receives the user data sent by the target eNB. 2. The method according to claim 1, wherein the sending of user data by the target eNB to the UE in step A is: the target eNB starts sending user data to the UE after the timing of sending to the UE is advanced. 3. The method according to claim 1, wherein, after the UE in step B receives the user data sent by the target eNB, further comprising: The UE sends a notification that the user data has been correctly received to the target eNB; After receiving the notification sent by the UE that the user data has been correctly received, the target eNB clears the user data in its own buffer that the UE has correctly received. 4. The method according to any one of claims 1 to 3, wherein after the UE in step B obtains the timing advance sent by the target eNB, it further includes: the UE notifies the target eNB that the handover is completed; After the target eNB confirms that the handover of the UE is completed, before notifying the source eNB that the handover is successful, the target eNB notifies the MME/UPE to update the positioning information of the UE, the MME/UPE stops transmitting user data to the source eNB, and starts transmitting user data to the target eNB. 5. The method according to any one of claims 1 to 3, wherein, before the target eNB in step A sends a timing advance to the UE, the method further comprises the following steps: The source eNB determines the target eNB to be handed over according to the measurement report sent by the UE, and sends handover request information carrying UE context information to the determined target eNB; After the source eNB receives the new handover-related parameters sent by the target eNB, it starts to transmit user data to the target eNB; The UE receives the handover command carrying the necessary handover parameters sent by the source eNB, and after the handover start time provided by the handover command arrives, separates from the source eNB, performs synchronization with the target eNB, and reports to the The target eNB requests timing advance. 6. A data transmission system in handover, the system comprising: UE, target eNB, characterized in that, The target eNB is used to send a timing advance to the UE, and send user data to the UE before receiving the user data transmitted by the MME/UPE; The UE is configured to receive the user data sent by the target eNB after acquiring the timing advance sent by the target eNB. 7. The system of claim 6, wherein: The UE is further configured to send a notification that the user data has been correctly received to the target eNB; The target eNB is further configured to receive a notification sent by the UE that the user data has been correctly received, and clear the user data that the UE has correctly received in its own buffer. 8. The system according to claim 6 or 7, further comprising: a source eNB and an MME/UPE, The UE is further configured to notify the target eNB that the handover is completed; The target eNB is further configured to notify the MME/UPE to update the positioning information of the UE before notifying the source eNB that the handover is successful after confirming that the handover of the UE is completed; The MME/UPE is configured to update the positioning information of the UE, and start transmitting user data to the target eNB. 9. A target evolved base station, characterized in that the target evolved base station includes: a timing advance sending module, a user data sending module, The timing advance sending module is configured to send timing advance to UE, and notify the user data sending module after sending; The user data sending module is configured to start sending user data to the UE after receiving the notification sent by the timing advance sending module and before receiving the user data sent by the MME/UPE. 10. The target evolved base station according to claim 9, wherein the target evolved base station further comprises: a buffer clearing module, The buffer clearing module is configured to confirm that the UE has correctly received the user data sent by the user data sending module, and clear the user data in the buffer that has been correctly received by the UE. 11. The target eNB according to claim 10, further comprising: an information update notification module, which is configured to notify the source eNB of the handover after confirming that the handover of the UE is completed Before success, notify the MME/UPE to update the location information of the UE and notify the MME/UPE to update the location information of the UE. 12. A user equipment, characterized in that the user equipment includes a timing advance acquisition module and a user data receiving module, The timing advance acquisition module is configured to acquire the timing advance sent by the target eNB, and notify the user data receiving module; The user data receiving module is configured to receive the user data from the target eNB after receiving the notification sent by the timing advance obtaining module. 13. The user equipment according to claim 12, characterized in that, the user equipment further comprises: a data reception confirmation module, The user data receiving module is a first user data receiving module, and the first user data receiving module is configured to receive user data from the target eNB after receiving the notification sent by the timing advance acquisition module, and receive After receiving the user data sent by the target eNB, notify the data reception confirmation module; The data receiving confirmation module is configured to receive the notification sent by the first user data receiving module, and notify the target eNB. 14. The user equipment according to claim 12, characterized in that, the user equipment further comprises: a handover completion notification module, The timing advance acquisition module is a first timing advance acquisition module, and the first timing advance acquisition module is used to acquire the timing advance sent by the target eNB, and notify the user data receiving module and the handover completion notification module; The handover completion notification module is configured to receive the notification sent by the first timing advance acquisition module, and notify the target eNB user equipment of the handover completion.

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