CN107872856B

CN107872856B - Method and device for reducing switching time delay

Info

Publication number: CN107872856B
Application number: CN201610862958.0A
Authority: CN
Inventors: 李娜; 丁飞; 胡南; 陈卓
Original assignee: China Mobile Communications Group Co Ltd; China Mobile Communications Ltd Research Institute
Current assignee: China Mobile Communications Group Co Ltd; China Mobile Communications Ltd Research Institute
Priority date: 2016-09-28
Filing date: 2016-09-28
Publication date: 2020-10-02
Anticipated expiration: 2036-09-28
Also published as: CN107872856A

Abstract

The invention relates to the field of wireless communication, in particular to a method and a device for reducing switching time delay, wherein the method comprises the steps that a source eNB receives UE capacity information reported by UE; the source eNB determines a switching scheme according to the received UE capability information, and sends a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme; and the source eNB receives a switching request response message returned by the target eNB based on the switching request, and if the switching request response message is determined to carry the confirmation information of the target eNB on the switching scheme, the UE is instructed to adopt the switching scheme to complete the switching, so that the source eNB and the target eNB negotiate to determine the switching scheme according to different application scenes, and the appropriate switching scheme with low time delay and low service interruption time is flexibly determined for the UE.

Description

Method and device for reducing switching time delay

Technical Field

The present invention relates to the field of wireless communications, and in particular, to a method and an apparatus for reducing a handover delay.

Background

In the switching process of a terminal (User Equipment, UE), the switching delay has a great influence on both the service quality and the system network performance, and reducing the service interruption time in the switching process has become a hot topic of reducing the switching delay, and is receiving more and more attention.

In the prior art, there are several schemes for reducing service interruption time in the handover process:

the first scheme is as follows: a Random Access Channel-less (RACH-less) handover scheme.

In practice, a typical handover delay is 40-50ms, where the RACH occupies about 10-12 ms. Therefore, the elimination of RACH time delay in the switching process will significantly reduce service interruption time and improve user experience.

The existing RACH less handover schemes have the following two types:

1) RACH less handover scheme 1: the uplink signal sent by the UE is measured by a target evolved Node B (eNB).

The basic principle is as follows: the source eNB tells the UE to send an uplink Signal at a predetermined time, for example, a Sounding Reference Signal (SRS), and tells the target eNB to measure the uplink Signal sent by the UE at the time. Based on the uplink signal, the target eNB calculates a Time Advance (TA) value and sends the TA value to the source eNB, and then the source eNB issues the TA value to the UE through a Handover Command (HO Command).

2) RACH-less handover scheme 2: and measuring the downlink signal of the target eNB through the UE.

The basic principle is as follows: referring to fig. 1, the UE first obtains a downlink propagation time difference between the source cell and the target cell (i.e., T1-T2), and then obtains a TA value of the target cell based on the TA value of the source cell (assuming that the UL propagation delay and the DL propagation delay are the same), specifically:

TA_target＝TA_source-2(T1-T2) (synchronous network)

TA_target＝TA_source-2(T1-T2) + Δ T (non-synchronized network)

Where Δ T (which may be positive or negative) represents a subframe boundary offset value between the source eNB and the target eNB.

The RACH less switching scheme is simple and easy to realize, has no extra capability requirement on UE, but the uplink synchronization precision is greatly influenced by a wireless environment. When the UL propagation delay and the DL propagation delay are different, certain interference may be caused to the uplink transmission system, and in severe cases, reliable reception of service data may not be ensured. In addition, since there is no RACH procedure, an additional mechanism is needed to control the power of the first uplink transmission, power boosting, and an additional mechanism is needed to provide uplink resources for the UE to send Msg 3.

The second scheme is as follows: seamless (Seamless) handover schemes.

Specifically, referring to fig. 2, the UE maintains connection with the source eNB during the uplink and downlink synchronization with the target eNB. Thus, no service data interruption in the switching process can be realized.

The Seamless handover scheme can achieve the same uplink synchronization precision performance as the existing mechanism and achieve zero service interruption, but needs the UE to have dual transceiving capability, and compared with the RACH less handover scheme, the Seamless handover scheme has the advantages of large complexity and long overall handover delay.

Therefore, in the prior art, the method for reducing the handover delay cannot comprehensively consider the UE capability and the network environment, and flexibly determine different handover schemes, and there is no scheme for determining the specific execution flow of the RACH less.

Disclosure of Invention

Embodiments of the present invention provide a method and an apparatus for reducing a handover delay, so as to solve the problem that a handover scheme in the prior art is relatively single and a suitable handover scheme cannot be flexibly determined according to different application scenarios.

The embodiment of the invention provides the following specific technical scheme:

a method of reducing handover latency, comprising:

a source eNB receives UE capacity information reported by UE;

the source eNB determines a switching scheme according to the received UE capability information, and sends a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme;

and the source eNB receives a switching request response message returned by the target eNB based on the switching request, and if the switching request response message is determined to carry the confirmation information of the target eNB on the switching scheme, the source eNB instructs the UE to adopt the switching scheme to complete the switching.

Preferably, the receiving, by the source eNB, the UE capability information reported by the UE specifically includes:

the source eNB receives UE capacity information reported by UE through a response message returned based on a UE capacity inquiry request sent by the source eNB; or the like, or, alternatively,

and the source eNB receives the UE capability information reported by the UE through the RRC connection establishment message.

Preferably, the determining, by the source eNB, the handover scheme according to the received UE capability information specifically includes:

if the UE is determined to have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: an RACH less switching scheme 1, an RACH less switching scheme 2 and a Seamless switching scheme; or the like, or, alternatively,

if the UE is determined not to have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: RACH less handover scheme 1, RACH less handover scheme 2.

Preferably, the confirmation information of the target eNB to the handover scheme is determined by the target eNB according to the current network environment.

Preferably, further comprising:

if the determined handover scheme is an RACH less handover scheme 1, the handover request at least carries time for sending an uplink signal by the UE, and the handover request response message at least carries a first TA value of the target eNB, wherein the first TA value of the target eNB is calculated by the target eNB according to a preset algorithm based on the received time for sending the uplink signal by the UE; or the like, or, alternatively,

if the determined handover scheme is RACH less handover scheme 2, when the source eNB and the target eNB are unsynchronized, the handover request response message at least carries a subframe boundary deviation value of the source eNB and the target eNB; or the like, or, alternatively,

if the determined handover scheme is an RACH less handover scheme 1+ Seamless handover scheme, the handover request at least carries time for the UE to send an uplink signal, and the handover request response message at least carries a first TA value of the target eNB; or the like, or, alternatively,

if the determined handover scheme is a RACH less handover scheme 2+ Seamless handover scheme, the handover request response message carries a subframe boundary offset value of the source eNB and the target eNB at least when the source eNB and the target eNB are not synchronized.

Preferably, the instructing the UE to use the handover scheme to complete the handover includes:

if the determined switching scheme is RACH (random access channel) less switching scheme 1, indicating the UE to adopt the RACH less switching scheme 1 for switching, sending a first TA (timing advance) value of the target eNB to the UE, and enabling the UE to send an uplink signal on uplink resources allocated to the UE by the target eNB based on the first TA value of the target eNB; or the like, or, alternatively,

if the determined switching scheme is RACH (random access channel) less switching scheme 2, indicating the UE to adopt the RACH less switching scheme 2 for switching, and when the UE determines that the source eNB and the target eNB meet the uplink synchronization requirement, enabling the UE to send an uplink signal on uplink resources allocated to the UE by the target eNB based on a second TA (timing advance) value of the target eNB; the second TA value of the target eNB is calculated by the UE according to the measured downlink signals of the source eNB and the target eNB; or the like, or, alternatively,

if the determined switching scheme is a Seamless switching scheme, indicating the UE to adopt the Seamless switching scheme for switching, and enabling the UE to initiate an RACH flow to a target eNB; or the like, or, alternatively,

if the determined switching scheme is an RACH (random access channel) less switching scheme 1+ Seamless switching scheme, indicating the UE to adopt the RACH less switching scheme 1+ Seamless switching scheme for switching, sending a first TA (timing advance) value of the target eNB to the UE, and enabling the UE to send an uplink signal on uplink resources allocated to the UE by the target eNB based on the first TA value of the target eNB; or the like, or, alternatively,

if the determined switching scheme is an RACH (random access channel) less switching scheme 2+ Seamless switching scheme, indicating the UE to adopt the RACH less switching scheme 2+ Seamless switching scheme for switching, sending a subframe boundary deviation value of a source eNB and a target eNB to the UE when the source eNB and the target eNB are asynchronous, and enabling the UE to send an uplink signal on an uplink resource distributed to the UE by the target eNB based on a second TA (timing advance) value of the target eNB when the UE determines that the source eNB and the target eNB meet an uplink synchronization requirement; or the like, or, alternatively,

and if the determined switching scheme is the RACH less switching scheme 2+ Seamless switching scheme, indicating the UE to adopt the RACH less switching scheme 2+ Seamless switching scheme for switching, sending a subframe boundary deviation value of the source eNB and the target eNB to the UE when the source eNB and the target eNB are asynchronous, and enabling the UE to initiate an RACH flow to the target eNB when the UE determines that the source eNB and the target eNB do not meet the uplink synchronization requirement.

Preferably, the uplink resource allocated to the UE by the target eNB is sent to the UE by the target eNB through the source eNB; or the like, or, alternatively,

the uplink resource allocated to the UE by the target eNB is sent to the UE by the target eNB in a preset pre-scheduling mode; or the like, or, alternatively,

and the uplink resource allocated to the UE by the target eNB is sent to the UE by the target eNB in a dynamic scheduling mode.

An apparatus for reducing handoff latency, comprising:

a receiving unit, configured to receive UE capability information reported by a UE;

the processing unit is used for determining a switching scheme according to the received UE capability information and sending a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme;

and the indicating unit is used for receiving a switching request response message returned by the target eNB based on the switching request, and indicating the UE to adopt the switching scheme to complete the switching if the switching request response message is determined to carry the confirmation information of the target eNB on the switching scheme.

Preferably, when receiving the UE capability information reported by the UE, the receiving unit is specifically configured to:

receiving UE capacity information reported by UE through a response message returned based on a UE capacity inquiry request sent by a source eNB; or the like, or, alternatively,

and receiving UE capability information reported by the UE through a Radio Resource Control (RRC) connection establishment message.

Preferably, when determining the handover scheme according to the received UE capability information, the processing unit is specifically configured to:

Preferably, further comprising:

Preferably, the UE is instructed to adopt the handover scheme, and when the handover is completed, the instructing unit is specifically configured to:

The invention has the following beneficial effects:

a source eNB receives UE capacity information reported by UE; the source eNB determines a switching scheme according to the received UE capability information, and sends a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme; and the source eNB receives a switching request response message returned by the target eNB based on the switching request, and if the switching request response message is determined to carry confirmation information of the target eNB on the switching scheme, the UE is instructed to adopt the switching scheme to complete switching.

And for different switching schemes, a specific execution method is provided, so that the purpose of reducing service interruption time in switching time delay under different switching schemes is achieved.

Drawings

FIG. 1 is a diagram illustrating a UE handover in the prior art;

FIG. 2 is a flow chart of a Seamless handover scheme in the prior art;

FIG. 3 is a flowchart illustrating an overview of a method for reducing handoff delay in an embodiment of the present invention;

fig. 4 is a detailed flowchart of a method for reducing handover delay in an application scenario according to an embodiment of the present invention;

fig. 5 is a detailed flowchart of a method for reducing handover delay in application scenario two in the embodiment of the present invention;

fig. 6 is a detailed flowchart of a method for applying a scenario three-down handover delay in an embodiment of the present invention;

fig. 7 is a detailed flowchart of a method for reducing handover delay in an application scenario four in an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a device for reducing a switching delay in an embodiment of the present invention.

Detailed Description

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 order to solve the problem that the switching scheme in the prior art is single and different application scenarios cannot be comprehensively considered to flexibly determine a proper switching scheme, in the embodiment of the invention, a source eNB determines the switching scheme according to UE capacity information and the current network environment, indicates the switching scheme to a target eNB, and adopts the switching scheme to realize the switching of the UE after the target eNB confirms.

The present invention will be described in detail with reference to specific examples, but it is to be understood that the present invention is not limited to the examples.

Referring to fig. 3, in the embodiment of the present invention, a specific process of the method for reducing the handover delay includes:

step 100: and the source eNB receives the UE capability information reported by the UE.

In practice, when the UE performs handover, there are three handover schemes for reducing service interruption time in the handover process: RACH less handover scheme 1, RACH less handover scheme 2 and Seamless handover scheme. The basic principle of the RACH less switching scheme 1 is that a TA value of a target eNB is calculated by measuring an uplink signal sent by UE through the target eNB, so that switching is realized; the basic principle of the RACH less switching scheme 2 is that the TA value of the target eNB is calculated by measuring the downlink signal of the target eNB through the UE, so that the switching is realized; the basic principle of the Seamless handover scheme is that the UE maintains connection with the source eNB during the uplink and downlink synchronization with the target eNB.

It should be noted that the common idea of both the RACH less handover scheme 1 and the RACH less handover scheme 2 is to eliminate the RACH delay in the handover process, and the distinction between 1 and 2 is only for convenience of the following description, and has no other meaning.

In the embodiment of the invention, based on the three switching schemes, different switching schemes can be flexibly configured according to different conditions, and specific implementation processes of different switching schemes are provided.

The UE capability information indicates whether the UE has dual transceiving capability.

When step 100 is executed, the following two cases can be distinguished:

in the first case: and the source eNB receives the UE capability information reported by the UE through a response message returned based on the UE capability inquiry request sent by the source eNB.

That is, in the handover preparation phase, the source eNB may send a UE capability query request to the UE, and the UE may report the UE capability information to the source eNB after receiving the UE capability query request.

In the second case: the source eNB receives UE capability information reported by the UE through a Radio Resource Control (RRC) connection setup message.

That is, the UE capability information may be reported to the source eNB through an RRC connection setup message in the process of establishing an RRC connection between the UE and the source eNB.

Step 110: and the source eNB determines a switching scheme according to the received UE capability information and sends a switching request to the target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme.

In step 110, when the source eNB determines the handover scheme according to the received UE capability information, there may be the following two cases:

in the first case: if the UE is determined to have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: RACH less handover scheme 1, RACH less handover scheme 2 and Seamless handover scheme.

In the second case: if the UE is determined not to have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: RACH less handover scheme 1, RACH less handover scheme 2.

In this way, the source eNB may configure different handover schemes according to the UE capability information, and how a specific source eNB determines a current handover scheme from a plurality of alternative handover schemes.

In step 110, after the source eNB determines the handover scheme, and when the source eNB sends the handover request to the target eNB based on the handover scheme, the following specific cases may be correspondingly implemented:

in the first case: and if the determined switching scheme is the RACH less switching scheme 1, the source eNB sends a switching request to the target eNB based on the RACH less switching scheme 1. Wherein, the switching request at least carries the RACH less switching scheme 1 and the time of UE sending uplink signals.

In the second case: and if the determined switching scheme is the RACH less switching scheme 2, the source eNB sends a switching request to the target eNB based on the RACH less switching scheme 2. Wherein, the switching request at least carries the RACH less switching scheme 2.

Further, the handover request may also carry radius information of the source cell corresponding to the source eNB. In this way, the target eNB can determine whether the RACH less handover scheme 2 is applicable based on the radius information of the source cell and the radius of the target cell corresponding to the target eNB.

In the third case: and if the determined handover scheme is a Seamless handover scheme, the source eNB sends a handover request to the target eNB based on the Seamless handover scheme. Wherein, the switching request at least carries a Seamless switching scheme.

In a fourth case: and if the determined switching scheme is the RACH less switching scheme 1+ Seamless switching scheme, the source eNB sends a switching request to the target eNB based on the RACH less switching scheme 1+ Seamless switching scheme. Wherein, the switching request at least carries the RACH less switching scheme 1+ the Seamless switching scheme and the time for the UE to send the uplink signal.

In the fifth case: and if the determined switching scheme is the RACH less switching scheme 2+ Seamless switching scheme, the source eNB sends a switching request to the target eNB based on the RACH less switching scheme 2+ Seamless switching scheme. Wherein, the switching request at least carries the RACH less switching scheme 2+ the Seamless switching scheme.

Further, the handover request may carry radius information of a source cell corresponding to the source eNB.

Thus, based on the above five situations, after determining the handover scheme, the source eNB may indicate to the target eNB the handover scheme that the target eNB desires to adopt, and simultaneously transmit information required when adopting the handover scheme, so that the target eNB may determine whether the handover scheme can be adopted based on the information, and if the target eNB agrees to adopt the handover scheme, may directly perform subsequent operations according to the information.

Step 120: and the source eNB receives a switching request response message returned by the target eNB based on the switching request, and if the switching request response message is determined to carry the confirmation information of the target eNB on the switching scheme, the source eNB instructs the UE to adopt the switching scheme to complete the switching.

The confirmation information of the handover scheme by the target eNB is determined by the target eNB according to the current network environment, and is specifically described in detail in the following cases.

Based on the five cases in step 110, when step 120 is executed, the following cases may be also classified:

1) in the first case: and if the determined switching scheme is the RACH less switching scheme 1.

Firstly, if the target eNB agrees to adopt the RACH less handover scheme 1, the target eNB returns a handover request response message carrying confirmation information of the RACH less handover scheme 1 to the source eNB.

The target eNB determines whether to agree to adopt the RACH less handover scheme 1, specifically: and the target eNB judges whether the time is idle or not based on the received time of the UE for transmitting the uplink signal, namely whether the target eNB can measure the uplink signal transmitted by the UE at the time, and if so, the target eNB determines to approve adopting the RACH less switching scheme 1.

Further, the handover request response message carries a first TA value of the target eNB, where the first TA value of the target eNB is calculated by the target eNB according to a preset algorithm based on the received time for the UE to transmit the uplink signal, and specifically is: the target eNB measures an uplink signal transmitted by the UE at the time, and calculates a first TA value of the target eNB based on the measured uplink signal transmitted by the UE.

Further, the handover request response message may also carry uplink resources allocated to the UE by the target eNB, that is, uplink resources used for sending the Msg 3.

It should be noted that, if the handover request response message does not carry the uplink resource allocated to the UE by the target eNB, the target eNB needs to send the uplink resource to the UE in a pre-scheduling or dynamic scheduling manner.

Then, after receiving the handover request response message, the source eNB sends a handover command to the UE, instructs the UE to complete handover by using the RACHless handover scheme 1, and sends the first TA value of the target eNB to the UE.

Further, if the handover request response message carries the uplink resource sent to the UE by the target eNB, the source eNB sends the uplink resource allocated to the UE by the target eNB to the UE.

Finally, the UE transmits an uplink signal on the uplink resource allocated by the target eNB based on the first TA value of the target eNB, that is, the handover is completed.

2) In the second case: and if the determined switching scheme is the RACH less switching scheme 2.

First, if the target eNB agrees to adopt the RACH less handover scheme 2, the target eNB returns a handover request response message carrying confirmation information of the RACH less handover scheme 2 to the source eNB.

The target eNB determines whether to agree to adopt the RACH less handover scheme 2, specifically: and the target eNB calculates the difference value between the radius of the target cell corresponding to the target eNB and the radius of the source cell based on the received radius information of the source cell, judges whether the difference value is larger than a preset threshold value, if so, the target eNB determines that the RACH (random access channel) less switching scheme 2 is not adopted, and otherwise, the target eNB agrees to adopt the RACH less switching scheme 2.

Further, when the source eNB and the target eNB are unsynchronized, the handover request response message needs to carry a subframe boundary offset value between the source eNB and the target eNB.

Further, the handover request response message may also carry uplink resources allocated to the UE by the target eNB.

Similarly, if the handover request response message does not carry the uplink resource allocated to the UE by the target eNB, the target eNB needs to send the uplink resource to the UE in a pre-scheduling or dynamic scheduling manner.

Then, after receiving the handover request response message, the source eNB sends a handover command to the UE to instruct the UE to complete handover by using the RACHless handover scheme 2.

Then, the UE calculates a second TA value of the target eNB, and determines whether the source eNB and the target eNB meet the uplink synchronization requirement, and when it is determined that the uplink synchronization requirement is met, it is determined that the RACH less handover scheme 2 may be adopted.

The second TA value of the target eNB is calculated by the UE according to the measured downlink signals of the source eNB and the target eNB, and specific calculation methods and determination methods are described in detail in the following application scenarios, and are not described in detail here.

Finally, the UE transmits an uplink signal on the uplink resource allocated by the target eNB based on the second TA value of the target eNB, that is, the handover is completed.

3) In the third case: and if the determined switching scheme is a Seamless switching scheme.

First, if the target eNB agrees to adopt the Seamless handover scheme, the target eNB returns a handover request response message carrying confirmation information of the Seamless handover scheme to the source eNB.

Further, the handover request response message may carry Physical Random Access Channel (PRACH) information, such as a preamble code, allocated to the UE by the target eNB.

Then, after receiving the handover request response message, the source eNB sends a handover command to the UE to instruct the UE to complete handover by using the Seamless handover scheme.

Finally, the UE initiates a RACH procedure to the target eNB.

It is worth to be noted that, if the handover request response message carries PRACH information allocated to the UE by the target eNB, the source eNB sends the PRACH information to the UE, and the UE may initiate an RACH procedure to the target eNB based on the PRACH information allocated by the target eNB; if the handover request response message does not carry the PRACH information allocated to the UE by the target eNB, the UE may actively initiate an RACH procedure to the target eNB by using other resources when performing handover using the Seamless handover scheme.

The RACH procedure may be executed by using a method for executing the RACH procedure in the prior art, which is not described in the embodiment of the present invention.

4) In a fourth case: and if the determined switching scheme is the RACH less switching scheme 1+ Seamless switching scheme.

First, if the target eNB agrees to adopt the RACH less handover scheme 1+ Seamless handover scheme, the target eNB returns a handover request response message carrying confirmation information of the RACH less handover scheme 1+ Seamless handover scheme to the source eNB.

Further, the handover request response message carries the first TA value of the target eNB calculated by the target eNB, and may also carry uplink resources allocated to the UE by the target eNB, that is, uplink resources used for sending the Msg 3.

Then, the source eNB sends a handover command to the UE after receiving the handover request response message.

For example, the source eNB may select one of them to instruct the UE to perform handover using one of the handover schemes, e.g., RACH less handover scheme 1.

And finally, the UE adopts the switching scheme indicated by the source eNB to complete the switching. For example, the UE transmits an uplink signal on the uplink resource allocated to the UE by the target eNB based on the first TA value of the target eNB.

Further, if the target eNB replies the confirmation information to only one of the handover schemes, the target eNB only performs subsequent operations based on the handover scheme confirmed by the target eNB, and specifically, further introduces the subsequent operations in subsequent application scenarios.

5) In the fifth case: and if the determined switching scheme is the RACH less switching scheme 2+ Seamless switching scheme.

First, if the target eNB agrees to adopt the RACH less handover scheme 2+ Seamless handover scheme, the target eNB returns a handover request response message carrying acknowledgement information for the RACH less handover scheme 2+ Seamless handover scheme to the source eNB.

Further, the handover request response message may carry PRACH information (e.g. preamble code) allocated by the target eNB to the UE, uplink resources allocated by the target eNB to the UE, that is, uplink resources for sending Msg3, and a subframe boundary offset value between the active eNB and the target eNB when the source eNB and the target eNB are asynchronous.

For example, the source eNB may select one of them to instruct the UE to perform handover using one of the handover schemes, e.g., RACH less handover scheme 2.

Then, if the result is RACH less switching scheme 2, the UE calculates a second TA value of the target eNB, and determines whether the source eNB and the target eNB meet the uplink synchronization requirement, and when it is determined that the uplink synchronization requirement is met, it is determined that the RACH less switching scheme 2 may be adopted, otherwise, the UE may adopt a Seamless switching scheme according to the instruction of the source eNB.

And finally, the UE completes the switching based on the determined switching scheme.

That is to say, in the embodiment of the present invention, according to the UE capability information and the current network environment (for example, the radius of the cell corresponding to the source eNB and the target eNB, etc.), the source eNB and the target eNB may negotiate to determine which handover scheme to use, where the negotiation process is initiated by the source eNB through a handover request and is confirmed by the target eNB through a handover request response message, so as to determine a suitable handover scheme with low handover delay and low service interruption time for the terminal.

It should be noted that the first TA value of the target eNB and the second TA value of the target eNB are calculated differently in different situations, and have no other meaning.

The above embodiments are described in further detail below using several specific application scenarios.

Application scenario one: referring to fig. 4, specifically, the method for reducing handover delay in the embodiment of the present invention is implemented as follows:

step 200: the source eNB sends a UE capability query request to the UE.

Step 201: and the UE reports the UE capability information to the source eNB.

Wherein, in the UE capability information, the UE is indicated not to have dual transceiving capability.

Step 202: the source eNB sends a handover request to the target eNB.

Wherein, in the switching request, the indication hopes to adopt the RACH less switching scheme 1 and carries the time of UE sending uplink signals.

Step 203: the target eNB measures the uplink signal transmitted by the UE at this time, and calculates the TA value of the target eNB based on the uplink signal transmitted by the UE.

In the embodiment of the present invention, the method for calculating the TA value of the target eNB is not limited, and the target eNB may calculate the TA value by using an existing method.

Step 204: the target eNB returns a handover request response message to the source eNB.

The handover request response message carries the confirmation information of the target eNB to the RACH less handover scheme 1 and the TA value of the target eNB, and further may carry uplink resources allocated to the UE, that is, uplink resources used by the UE to send Msg 3.

If the handover request response message does not carry the uplink resource allocated to the UE, the target eNB may also send the uplink resource to the UE in a pre-scheduling or dynamic scheduling manner.

Step 205: and the source eNB sends a switching command to the UE, instructs the UE to adopt the RACH less switching scheme 1 and carries the TA value of the target eNB, and further carries the uplink resource distributed to the UE by the target eNB if the switching request response message carries the uplink resource distributed to the UE.

Step 206: and the UE transmits an uplink signal to the target eNB on the uplink resource allocated by the target eNB based on the TA value of the target eNB, and completes the switching.

(II) application scenario II: specifically referring to fig. 5, the method for reducing handover delay in the embodiment of the present invention specifically includes the following steps:

step 300: the source eNB sends a UE capability query request to the UE.

Step 301: and the UE reports the UE capability information to the source eNB.

Step 302: the source eNB sends a handover request to the target eNB.

Wherein, in the handover request, it is indicated that the RACH less handover scheme 2 is expected to be adopted, and possibly, the source cell radius information corresponding to the source eNB is carried.

Step 303: and if the target eNB receives the source cell radius information, determining whether the RACH less scheme 2 can be used or not based on the comparison result of the source cell radius and the target cell radius.

The method specifically comprises the following steps: and calculating the difference value between the radius of the target cell corresponding to the target eNB and the radius of the source cell, and judging whether the difference value is larger than a preset threshold value, if so, determining that the RACH (random access channel) less switching scheme 2 is not adopted by the target eNB, namely, the confirmation information of the RACH less switching scheme 2 is not returned to the source eNB, otherwise, determining that the RACH less switching scheme 2 is adopted by the target eNB.

It should be noted that step 303 is an optional step, and is not necessarily performed, and determines whether to adopt the RACHless handover scheme 2, or the source eNB may perform the determination, and when it is determined that the rach less handover scheme 2 can be adopted, the source eNB indicates to the target eNB, and at this time, the source eNB does not need to send the radius information of the source cell to the target eNB.

Step 304: the target eNB returns a handover request response message to the source eNB.

The handover request response message carries the confirmation information of the target eNB to the RACH less handover scheme 2, and further may carry uplink resources allocated to the UE, and when the source eNB and the target eNB are asynchronous, carries a subframe boundary offset value between the source eNB and the target eNB.

Further, if the target eNB does not agree to adopt the RACH less handover scheme 2, that is, does not send acknowledgement information to the source eNB, the source eNB may adopt another handover scheme to reinitiate the handover request.

Step 305: and the source eNB sends a switching command to the UE to instruct the UE to adopt an RACH (random access channel) less switching scheme 2, and further, if the switching request response message carries the uplink resource and the subframe boundary deviation value distributed to the UE, the switching request response message simultaneously carries the uplink resource distributed to the UE by the target eNB and the subframe boundary deviation between the source eNB and the target eNB.

Step 306: the terminal calculates the TA value of the target eNB.

For example, specifically: first, the UE obtains a downlink propagation time difference between the source cell and the target cell, e.g., T1-T2.

Then, based on the TA value of the source eNB, the TA value of the target eNB is calculated (assuming that the Uplink (UL) propagation delay and the Downlink (DL) propagation delay are the same):

1) TA when Source eNB and target eNB are synchronized_target＝TA_source-2(T1-T2)

Wherein, TA_targetRepresenting the TA value, TA, of the target eNB_sourceRepresenting the TA value of the source eNB.

2) TA when Source eNB and target eNB are not synchronized_target＝TA_source-2(T1-T2)+ΔT

Where Δ T represents a subframe boundary offset value between the source eNB and the target eNB.

Step 307: the terminal judges whether the uplink synchronization requirement is met, if so, step 308 is executed, otherwise, step 309 is executed.

For example, specifically: and judging (T1-T2) whether the threshold value is larger than a preset threshold value, such as TH, if so, determining that the uplink synchronization requirement is not met, otherwise, determining that the uplink synchronization requirement is met.

The preset threshold value TH may be configured to the UE through RRC signaling or agreed in a protocol.

Of course, how to judge whether the uplink synchronization requirement is satisfied may also adopt other methods, and the embodiment of the present invention is not limited.

Step 308: and the UE transmits an uplink signal to the target eNB on the uplink resource allocated by the target eNB based on the TA value of the target eNB, and completes the switching.

Step 309: and the UE initiates an RACH flow to complete the switching.

That is, at this time, the RACH less handover scheme 2 is unavailable, and the UE cannot complete handover based on the RACH less handover scheme 2, and the UE needs to adopt other conventional handover schemes, for example, perform RACH procedure to complete handover.

(III) application scenario III: the UE has dual transceiving capabilities and the handover scheme is RACH less handover scheme 1+ Seamless handover scheme, and the target eNB confirms that both the RACH less handover scheme 1+ Seamless handover scheme are applicable (taking RACH less handover scheme 1 as an example), specifically referring to fig. 6, in the embodiment of the present invention, the implementation process of the method for reducing the handover delay is specifically as follows:

step 400: the source eNB sends a UE capability query request to the UE.

Step 401: and the UE reports the UE capability information to the source eNB.

And the UE capability information indicates that the UE has dual transceiving capability.

Step 402: the source eNB sends a handover request to the target eNB.

Wherein, in the switching request, the indication hopes to adopt the RACH less switching scheme 1+ the Seamless switching scheme and carries the time of the UE for sending the uplink signal.

Step 403: the target eNB measures the uplink signal transmitted by the UE at this time, and calculates the TA value of the target eNB based on the uplink signal transmitted by the UE.

Step 404: the target eNB returns a handover request response message to the source eNB.

The handover request response message carries acknowledgement information and TA value of the target eNB for the RACH less handover scheme 1+ Seamless handover scheme, and further may carry uplink resources allocated to the UE.

Step 405: and the source eNB sends a switching command to the UE, instructs the UE to adopt an RACH (random access channel) less switching scheme 1+ Seamless switching scheme and carries a TA (timing advance) value, and further carries the uplink resource distributed to the UE by the target eNB if the switching request response message carries the uplink resource distributed to the UE.

Step 406: and the UE transmits an uplink signal to the target eNB on the uplink resource allocated by the target eNB based on the TA value to complete the switching.

(IV) application scenario IV: the UE has dual transceiving capabilities and the handover scheme is RACH less handover scheme 2+ Seamless handover scheme, and the target eNB confirms that the RACH less handover scheme 2 is not applicable, and the Seamless handover scheme is applicable, as shown in fig. 7 specifically, in the embodiment of the present invention, the execution process of the method for reducing the handover delay specifically includes:

step 500: the source eNB sends a UE capability query request to the UE.

Step 501: and the UE reports the UE capability information to the source eNB.

Step 502: the source eNB sends a handover request to the target eNB.

Wherein, in the handover request, it is indicated that the RACH less handover scheme 2+ Seamless handover scheme is desirably adopted, and possibly, the source cell radius information corresponding to the source eNB is carried.

Step 503: if the target eNB receives the source cell radius information, the target eNB determines whether the RACH less scheme 2 can be used or not based on the comparison result of the source cell radius and the target cell radius, for example, determines that the RACH less scheme 2 is not applicable.

Wherein, the step 503 is the same as the step 303.

Step 504: the target eNB returns a handover request response message to the source eNB.

The handover request response message carries the acknowledgement information of the target eNB to the Seamless handover scheme and the rejection information of the RACH less handover scheme 2, and may carry PRACH information allocated to the UE by the target eNB.

Step 505: and the source eNB sends a switching command to the UE to indicate the UE to adopt a Seamless switching scheme and possibly carry PRACH information distributed to the UE by the target eNB.

Step 506: the UE initiates a RACH procedure to the target eNB.

(V) application scenario V: in the first application scenario, the UE does not have dual transceiving capabilities and the handover scheme is the RACH less handover scheme 1, and the target eNB determines that the RACH less handover scheme 1 is unavailable, the source eNB may use the RACH less handover scheme 2 to re-send the handover request to the target eNB, and the subsequent execution process and the application scenario are the same, which is not described herein again.

Or, the source eNB directly instructs the UE to perform handover by using other conventional handover schemes in the prior art, where the execution process of the conventional handover scheme may use the existing method, and is not described herein again. The conventional handover scheme herein refers to other handover schemes besides the RACH less handover scheme 1, the RACH less handover scheme 2 and the Seamless handover scheme mentioned in the embodiments of the present invention.

(VI) application scenario six: in the second scenario, the UE does not have dual transceiving capabilities and the handover scheme is RACH less handover scheme 2, and the target eNB determines that the RACH less handover scheme 2 is unavailable, the source eNB may re-send the handover request to the target eNB by using the RACH less handover scheme 1, and the subsequent execution process is the same as the application scenario, which is not described herein again.

Alternatively, the source eNB may directly instruct the UE to perform handover using other conventional handover schemes in the prior art.

(VII) application scenario seven: in contrast to the application scenario three, the UE has dual transceiving capabilities and the handover scheme is the RACH less handover scheme 1+ Seamless handover scheme, and the target eNB confirms that both the RACH less handover scheme 1+ Seamless handover scheme are applicable (taking the Seamless handover scheme as an example), or confirms that the RACH less handover scheme 1 is not applicable and the Seamless handover scheme is applicable, at this time, the Seamless handover scheme is adopted for handover, and the specific execution process and the application scenario are similar, except that the handover scheme information carried in the handover request response message and the handover command are different.

(eight) application scenarios eight: in a fourth scenario, the UE has dual transceiving capabilities and the handover scheme is RACH less handover scheme 2+ Seamless handover scheme, and the target eNB confirms that both the RACH less handover scheme 2+ Seamless handover scheme are applicable.

The execution process is similar to the application scenario two, except that the acknowledgement information and the PRACH resource for the Seamless handover scheme are added to both the handover request response message returned by the target eNB and the handover command sent to the UE by the source eNB.

And, the process corresponding to step 309 is different, instead: and the UE adopts a Seamless switching scheme to complete the switching. That is, when the target eNB determines that both the RACH less handover scheme 2+ the Seamless handover scheme are applicable at the same time, and when the UE determines that the RACH less handover scheme 2 is not applicable, the UE may directly perform handover using the Seamless handover scheme again.

(nine) application scenarios nine: the UE has dual transceiving capability and the handover scheme is a Seamless handover scheme, and the target eNB confirms that the Seamless handover scheme is applicable. The execution process and the application scenario are similar, except that there is no judgment on the RACH less handover scheme 2 (i.e., step 503 is not included), and the handover request response message do not need to carry the radius information of the source cell corresponding to the RACH less handover scheme 2 and the source eNB.

It should be noted that, when the UE has dual transceiving capabilities, the handover scheme determined by the source eNB may also be only one of the RACHless handover scheme 1 and the RACH less handover scheme 2, and the execution process is the same as the application scenario one and the application scenario two.

Other possible application scenarios, which are not listed in the embodiments of the present invention, can be easily inferred by those skilled in the art based on the above application scenarios, and are also within the scope of the present invention.

Based on the foregoing embodiments, referring to fig. 8, in an embodiment of the present invention, an apparatus for reducing a handover delay includes:

a receiving unit 60, configured to receive UE capability information reported by the UE;

a processing unit 61, configured to determine a handover scheme according to the received UE capability information, and send a handover request to a target eNB based on the handover scheme, where the handover request at least carries the handover scheme;

an indicating unit 62, configured to receive a handover request response message returned by the target eNB based on the handover request, and if it is determined that the handover request response message carries confirmation information of the handover scheme by the target eNB, indicate the UE to adopt the handover scheme to complete handover.

Preferably, when receiving the UE capability information reported by the UE, the receiving unit 60 is specifically configured to:

and receiving the UE capability information reported by the UE through the RRC connection establishment message.

Preferably, when determining the handover scheme according to the received UE capability information, the processing unit 61 is specifically configured to:

Preferably, further comprising:

Preferably, the indicating unit 62 is configured to, when the UE is instructed to adopt the handover scheme and handover is completed:

if the determined switching scheme is an RACH (random access channel) less switching scheme 1+ Seamless switching scheme, indicating the UE to adopt the RACH less switching scheme 1+ Seamless switching scheme for switching, and enabling the UE to send an uplink signal on uplink resources allocated to the UE by the target eNB based on the first TA value of the target eNB by using the first TA value of the target eNB; or the like, or, alternatively,

In summary, in the embodiments of the present invention, the source eNB receives UE capability information reported by the UE; the source eNB determines a switching scheme according to the received UE capability information, and sends a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme; and the source eNB receives a switching request response message returned by the target eNB based on the switching request, and if the switching request response message is determined to carry confirmation information of the target eNB on the switching scheme, the UE is instructed to adopt the switching scheme to complete switching, so that the source eNB and the target eNB negotiate to determine the switching scheme according to the UE capacity information and the current network environment, namely different application scenes, and the appropriate switching scheme with low time delay and low service interruption time is flexibly determined for the UE.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the present invention without departing from the spirit or scope of the embodiments of the invention. Thus, if such modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to encompass such modifications and variations.

Claims

1. A method for reducing handoff delay, comprising:

a source evolution type base station eNB receives UE capacity information reported by a terminal UE;

the source eNB determines a switching scheme according to the received UE capability information, and sends a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme; the source eNB determines a handover scheme according to the received UE capability information, which specifically includes: if the UE is determined to have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: the method comprises the following steps of (1) a random access procedure-free RACH (random access channel) less switching scheme 1, an RACH less switching scheme 2 and a Seamless Seamless switching scheme; or, if it is determined that the UE does not have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: the method comprises the following steps of 1, 2, wherein the RACH less switching scheme 1 is used for calculating a TA (timing advance) value of a target eNB by measuring an uplink signal sent by UE (user equipment) through the target eNB to realize switching, 2, the RACH less switching scheme is used for calculating the TA value of the target eNB by measuring a downlink signal of the target eNB through the UE to realize switching, and the Seamless switching scheme is used for keeping connection with a source eNB to realize switching in the process that the UE and the target eNB finish uplink and downlink synchronization;

2. The method of claim 1, wherein the receiving, by the source eNB, the UE capability information reported by the UE specifically includes:

and the source eNB receives the UE capability information reported by the UE through the radio resource control RRC connection establishment message.

3. The method of claim 1 or 2, wherein the acknowledgement information of the handover scheme by the target eNB is determined by the target eNB based on the current network environment.

4. The method of claim 3, further comprising:

if the determined handover scheme is an RACH less handover scheme 1, the handover request at least carries time for sending an uplink signal by the UE, and the handover request response message at least carries a first Time Advance (TA) value of the target eNB, wherein the first TA value of the target eNB is calculated by the target eNB according to a preset algorithm based on the received time for sending the uplink signal by the UE; or the like, or, alternatively,

if the determined handover scheme is RACHless handover scheme 2+ Seamless handover scheme, the handover request response message carries the subframe boundary offset value of the source eNB and the target eNB at least when the source eNB and the target eNB are not synchronous.

5. The method of claim 4, wherein the instructing the UE to complete the handover by using the handover scheme comprises:

if the determined switching scheme is RACH less switching scheme 1+ Seamless switching scheme, indicating the UE to adopt RACHless switching scheme 1+ Seamless switching scheme for switching, and sending the first TA value of the target eNB to the UE, and enabling the UE to send an uplink signal on the uplink resource allocated to the UE by the target eNB based on the first TA value of the target eNB; or the like, or, alternatively,

if the determined switching scheme is RACH less switching scheme 2+ Seamless switching scheme, indicating the UE to adopt RACHless switching scheme 2+ Seamless switching scheme for switching, sending a subframe boundary deviation value of a source eNB and a target eNB to the UE when the source eNB and the target eNB are asynchronous, and enabling the UE to send an uplink signal on an uplink resource distributed to the UE by the target eNB based on a second TA value of the target eNB when the UE determines that the source eNB and the target eNB meet an uplink synchronization requirement; or the like, or, alternatively,

and if the determined switching scheme is an RACH less switching scheme 2+ Seamless switching scheme, indicating the UE to adopt the RACHless switching scheme 2+ Seamless switching scheme for switching, sending the subframe boundary deviation value of the source eNB and the target eNB to the UE when the source eNB and the target eNB are asynchronous, and enabling the UE to initiate an RACH flow to the target eNB when the UE determines that the source eNB and the target eNB do not meet the uplink synchronization requirement.

6. The method of claim 5, wherein the uplink resources allocated to the UE by the target eNB are transmitted by the target eNB to the UE via the source eNB; or the like, or, alternatively,

7. An apparatus for reducing handoff latency, comprising:

a receiving unit, configured to receive UE capability information reported by a terminal UE;

the processing unit is used for determining a switching scheme according to the received UE capability information and sending a switching request to a target eNB based on the switching scheme, wherein the switching request at least carries the switching scheme; when determining the handover scheme according to the received UE capability information, the processing unit is specifically configured to: if the UE is determined to have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: the method comprises the following steps of (1) a random access procedure-free RACH less switching scheme 1, an RACHless switching scheme 2 and a Seamless Seamless switching scheme; or, if it is determined that the UE does not have dual transceiving capability according to the UE capability information, the handover scheme determined by the source eNB is one or any combination of the following: RACH less switching scheme 1 and RACHless switching scheme 2, wherein the RACHless switching scheme 1 is to calculate the TA value of a target eNB by measuring an uplink signal sent by UE through the target eNB to realize switching, the RACH less switching scheme 2 is to calculate the TA value of the target eNB by measuring a downlink signal of the target eNB through the UE to realize switching, and the Seamless switching scheme is to keep connection with a source eNB to realize switching in the process that the UE and the target eNB finish uplink and downlink synchronization;

8. The apparatus of claim 7, wherein when receiving the UE capability information reported by the UE, the receiving unit is specifically configured to:

9. The apparatus of claim 7 or 8, wherein the acknowledgement information of the handover scheme by the target eNB is determined by the target eNB based on a current network environment.

10. The apparatus of claim 9, further comprising:

11. The apparatus of claim 10, wherein the UE is instructed to use the handover scheme, and when the handover is completed, the instructing unit is specifically configured to:

12. The apparatus of claim 11, wherein the uplink resources allocated to the UE by the target eNB are transmitted by the target eNB to the UE via the source eNB; or the like, or, alternatively,