WO2018126890A1

WO2018126890A1 - Method for maintaining uplink synchronization, base station, and user equipment

Info

Publication number: WO2018126890A1
Application number: PCT/CN2017/117482
Authority: WO
Inventors: 张莹; 赵娟娟
Original assignee: 中兴通讯股份有限公司
Priority date: 2017-01-05
Filing date: 2017-12-20
Publication date: 2018-07-12
Also published as: CN108282858A

Abstract

A method for maintaining uplink synchronization comprising: when detecting that TAT remaining time of a user equipment reaches a preset time threshold, a base station transmits a physical downlink control channel order to the user equipment engaged in a service; the base station receives a preamble sequence returned by the user equipment on the basis of the physical downlink control channel order; and the base station estimates a TA on the basis of the preamble sequence and transmits the TA to the user equipment, thus allowing the user equipment to maintain uplink synchronization on the basis of the TA.

Description

Maintain uplink synchronization method, base station and user equipment

Technical field

The present disclosure relates to, but is not limited to, the field of communications, and more particularly to a method, base station and user equipment for maintaining uplink synchronization.

Background technique

In order for the base station to correctly solve the data sent by the terminal, the terminal and the base station need to maintain uplink synchronization, so that the signal of the terminal can accurately fall into the receiving time window of the base station, that is, within the cyclic prefix range. Because the terminal and the base station have a certain air interface delay, the time synchronization point of the terminal is inconsistent with the time synchronization point of the base station. To eliminate the time synchronization deviation between the terminal and the base station, the UE (User Equipment) needs to transmit the signal. Time adjustment is performed and transmitted according to the time synchronization point of the base station. This adjustment time is called TA (Time Advance). The base station can control the time when the uplink signal from different UEs arrives at the base station by appropriately controlling the TA value of each UE. For a UE farther from the base station, because the transmission delay is larger, it is required to be sent earlier than the UE close to the base station. For the uplink data, the TA value is also relatively large.

In order to ensure the uplink synchronization between the UE and the base station, the base station needs to measure the TA value of the UE, and then obtain a final TA by a series of calculations such as smoothing, and form the TA value into a TAC (Time Advance Command), and then pass the RAR ( The Random Access Response (Random Access Response) brings the TAC to the UE, so that the UE knows how long to send data in advance to ensure that its data just falls within the cyclic prefix range of the base station.

Common TA estimation methods may include frequency domain estimation and time domain estimation. The frequency domain estimation method may include a frequency domain phase difference estimation method, and commonly used time domain estimation methods may include a sinc function interpolation method, a DFT (Discrete Fourier Transform) interpolation method, a center of gravity method, a DFT interpolation + a center of gravity method. Wait.

Summary of the invention

The following is an overview of the topics detailed in this document. This summary is not intended to limit the scope of the claims.

The TA estimation methods known in the art are only applicable to the case of a large number of resources such as a multi-subcarrier case. For the case of a single subcarrier, since the effective resources are small, the TA estimation is greatly difficult, and the estimated TA is Inaccurate, so it is impossible to maintain uplink synchronization.

Therefore, in the process of single subcarrier service, if the TA is not estimated or the TA estimation is inaccurate, it will lead to uplink out of synchronization.

The present disclosure provides a method, a base station, and a user equipment for maintaining uplink synchronization, which can avoid the uplink out-of-synchronization caused by the TA not being estimated or the TA estimation is inaccurate in the process of performing single subcarrier service.

The present disclosure provides a method for maintaining uplink synchronization, including: when the base station detects that the remaining time of the TAT (Time Alignment Timer) of the user equipment reaches a preset time threshold, the base station sends a PDCCH Order to the user equipment. a downlink control channel command, the base station receives a preamble sequence returned by the user equipment according to the PDCCH Order; the base station estimates a TA according to the preamble sequence, and sends the TA to the User equipment to enable the user equipment to maintain uplink synchronization according to the TA.

In an exemplary embodiment, sending the PDCCH Order to the user equipment includes: determining whether the uplink BSR (Buffer Status Report) is not empty or whether the downlink has data to be sent; the uplink BSR is not The eNB sends a PDCCH Order to the user equipment outside the inactive period of the user equipment DRX (Discontinuous Reception).

In an exemplary embodiment, the preset time threshold = TAT total duration - (the scheduling duration of the PDCCH Order + the scheduling duration of the TA + the transmission duration of the preamble sequence).

In an exemplary embodiment, the method further includes: the base station resetting a TAT corresponding to the user equipment if receiving the service data from the user equipment.

In another aspect, the present disclosure further provides a method for maintaining an uplink synchronization, including: receiving, by a user equipment, a PDCCH Order from a base station, where the PDCCH Order is that the base station detects that a TAT remaining time of the user equipment reaches a preset time threshold. The user equipment sends a preamble sequence to the base station according to the PDCCH Order; the user equipment receives the TA returned by the base station according to the preamble sequence, and resets the TAT corresponding to the user equipment; the user The device transmits data to the base station according to the TA.

In another aspect, the present disclosure further provides a base station, including: a first sending module, configured to: when detecting that a remaining time of a TAT of the user equipment reaches a preset time threshold, send a PDCCH Order to the user equipment; The method is configured to: receive a preamble sequence that is returned by the user equipment according to the PDCCH order; and an estimation module, configured to: estimate a TA according to the preamble sequence; and the second sending module is configured to: send the TA to the user equipment So that the user equipment maintains uplink synchronization according to the TA.

In an exemplary embodiment, the first sending module includes: a determining unit, configured to: determine whether the uplink BSR is not empty or whether the downlink has data to be sent; and the sending unit is configured to: the uplink BSR is not empty. Or if the downlink has data to be sent, the base station sends a PDCCH Order to the user equipment outside the inactivity period of the user equipment DRX.

In an exemplary embodiment, the preset time threshold of the determining unit is determined according to the following manner: the preset time threshold=the total length of the TAT-(the scheduling duration of the PDCCH Order+the scheduling of the TA) Duration + transmission duration of the preamble sequence).

In an exemplary embodiment, the method further includes: a first reset module, configured to: reset the TAT corresponding to the user equipment if the service data from the user equipment is received.

In another aspect, the present disclosure further provides a user equipment, including: a second receiving module, configured to: receive a PDCCH Order from a base station, where the PDCCH Order is that the base station detects that a TAT remaining time of the user equipment is reached. The third sending module is configured to send a preamble sequence to the base station according to the PDCCH order, and the second reset module is configured to: receive the TA returned by the base station according to the preamble sequence, and And resetting the TAT corresponding to the user equipment to update the time to the total duration of the TAT; and the fourth sending module is configured to: send data to the base station according to the TA.

Embodiments of the present disclosure also provide a computer readable storage medium storing computer executable instructions that, when executed, implement the method of maintaining uplink synchronization as described above.

When detecting that the remaining time of the TAT of the user equipment reaches a preset time threshold, the disclosure sends a PDCCH Order to the user equipment, so that the preamble sequence returned by the user can be received, and the TA is estimated according to the preamble sequence, and then the user can be allowed to The device uses the TA to implement uplink synchronization. In this process, whether or not it is a single subcarrier, the TA can be easily estimated by using the foregoing method, thereby completing the uplink synchronization, and avoiding the TA not estimating or during the process of performing the single subcarrier service. TA estimates the insufficiency caused by inaccurate conditions.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

1 is a flow chart of a method of maintaining uplink synchronization in a first embodiment of the present disclosure;

2 is a flow chart of a method of maintaining uplink synchronization in a second embodiment of the present disclosure;

3 is a schematic structural diagram of a base station in a third embodiment of the present disclosure;

4 is a schematic diagram showing an optional structure of a base station in a third embodiment of the present disclosure;

5 is a schematic structural diagram of a user equipment in a fourth embodiment of the present disclosure;

6 is a flowchart of an uplink synchronization method in a fifth embodiment of the present disclosure;

Fig. 7 is a conceptual diagram of a TAT fast timeout time in the fifth embodiment of the present disclosure.

Preferred embodiment of the present disclosure

Embodiments of the present disclosure will be described below with reference to the accompanying drawings.

The present disclosure provides a method, a base station, and a user equipment for maintaining uplink synchronization, which can avoid uplink synchronization failure caused by the TA not being estimated or the TA estimation is inaccurate in the process of performing single subcarrier service.

The first embodiment of the present disclosure provides a method for maintaining uplink synchronization. The flow of the method is as shown in FIG. 1, and may include steps S102 to S106:

S102: The base station sends a PDCCH Order to the user equipment when detecting that the remaining time of the TAT of the user equipment reaches a preset time threshold. The PDCCH Order in this process is equivalent to one form of MSG0 specified in the 3GPP (3rd Generation Partnership Project) standard.

S104. The base station receives a preamble sequence returned by the user equipment according to the PDCCH Order. The leader sequence in this process is equivalent to one form of MSG1 as specified in the standard.

S106. The base station estimates the TA according to the preamble sequence, and sends the TA to the user equipment, so that the user equipment maintains uplink synchronization according to the TA. In the implementation process, the base station may estimate the TA according to the preamble sequence, and send the TA to the TAC field and send the data to the user equipment through the RAR. The RAR carrying the TA in this process is equivalent to one form of MSG2 specified in the standard.

When detecting that the remaining time of the TAT of the user equipment reaches the preset time threshold, the PDCCH Order is sent to the user equipment, so that the preamble sequence returned by the user can be received, and the TA is estimated according to the preamble sequence, and then, Let the user equipment use the TA to implement uplink synchronization. In the process, whether the service is transmitted on a single subcarrier, the TA can be easily estimated by using the foregoing method, thereby completing uplink synchronization, and avoiding the process of performing single subcarrier service. TA does not estimate the upstream out-of-synchronization caused by the inaccurate TA estimation.

When the PDCCH order is sent to the user equipment, it can be determined whether the uplink BSR is not empty or whether there is data to be sent in the downlink; if the uplink BSR is not empty or the downlink has data to be sent, it can be stated that the service is still continuing, and the base station can The PDCCH Order is sent to the user equipment outside of the inactive period of the user equipment DRX.

The embodiment of the present disclosure uses TAT, which is already present in the 3GPP protocol. The protocol specifies that the behavior of the UE is: during the TAT operation, the UE considers itself to be synchronized, otherwise, the UE considers that it is out of synchronization. In the case of out-of-synchronization, if the UE wants to resend data, it can initiate a contention random access, and the UE can start or restart the timer when receiving the TAC. Therefore, the foregoing process is actually a method in which the TA can be determined by using random access, so that the user equipment in the service is randomly accessed again, thereby determining the TA, and avoiding the inability to implement the service caused by the user equipment entering the out-of-synchronization state when the TAT times out. .

Optionally, the preset time threshold=the total length of the TAT-(the scheduling duration of the PDCCH Order+the scheduling duration of the TA+the transmission duration of the preamble sequence).

When the base station can receive the service data from the user equipment, the base station can save the TAT corresponding to each user equipment. Therefore, when the service data is received, it can be proved that the use of the TA to complete the uplink synchronization succeeds. The TAT corresponding to the user equipment in the base station is reset to update the time to the total length of the TAT, and the process restarts the timer.

The second embodiment of the present disclosure provides a method for maintaining an uplink synchronization. The process of the method is as shown in FIG. 2, and may include steps S202 to S208:

S202, the user equipment receives the PDCCH Order from the base station, where the PDCCH Order is sent by the base station when detecting that the remaining time of the TAT of the user equipment reaches a preset time threshold;

S204. The user equipment sends a preamble sequence to the base station according to the PDCCH Order.

S206. The user equipment receives the TA returned by the base station according to the preamble sequence, and resets the TAT corresponding to the user equipment, to update the time to the total duration of the TAT.

S208. The user equipment sends data to the base station according to the TA.

In this embodiment, when the base station of the peer end detects that the remaining time of the TAT of the user equipment reaches the preset time threshold, it can determine whether the uplink BSR is not empty or whether the downlink has data to be sent; if the uplink BSR is not empty or has a downlink If the data is to be sent, the service of the user equipment can be continued. Therefore, the base station can send the PDCCH Order to the user equipment outside the inactivity period of the user equipment DRX, and the user equipment can send the preamble sequence to the base station according to the PDCCH order, so that The base station may estimate the TA according to the preamble sequence; after receiving the TA returned by the base station, reset the TAT of the user equipment side, and then the user equipment may use the TA to send the service data to the base station.

The third embodiment of the present disclosure provides a base station, which is shown in FIG. 3 and may include:

The first sending module 10 is configured to: when detecting that the remaining time of the TAT of the user equipment reaches the preset time threshold, send the PDCCH Order to the user equipment; the first receiving module 11 is configured to: coupled with the first sending module 10, and receive The preamble sequence returned by the user equipment according to the PDCCH order; the estimating module 12 is configured to: coupled with the first receiving module 11 to estimate the TA according to the preamble sequence; the second sending module 13 is configured to: coupled with the estimating module 12, send the TA to The user equipment is such that the user equipment maintains uplink synchronization according to the TA.

The first sending module 10 may include: a determining unit, configured to: determine whether the uplink BSR is not empty or whether the downlink has data to be sent; and the sending unit is configured to: when the uplink BSR is not empty or the downlink has data to be sent. Next, the base station sends a PDCCH Order to the user equipment outside the inactivity period of the user equipment DRX. The preset time threshold of the determining unit may be determined as follows: the preset time threshold=the total length of the TAT-(the scheduling duration of the PDCCH Order+the scheduling duration of the TA+the sending duration of the preamble sequence).

FIG. 4 is also a schematic diagram showing an optional structure of the foregoing base station. The base station may further include: a first reset module 14 configured to be coupled to the second sending module 13 and receiving service data from the user equipment. , reset the TAT corresponding to the user equipment to update the time to the total duration of the TAT.

The fourth embodiment of the present disclosure provides a user equipment, which is shown in FIG. 5, and may include: a second receiving module 20 configured to: receive a PDCCH Order from a base station, where the PDCCH Order is detected by the base station When the TAT remaining time of the user equipment reaches the preset time threshold, the third sending module 21 is configured to: coupled with the second receiving module 20, send a preamble sequence to the base station according to the PDCCH Order; and the second reset module 22 is set to And being coupled to the third sending module 21, receiving the TA returned by the base station according to the preamble sequence, and resetting the TAT corresponding to the user equipment to update the time to the total duration of the TAT; and the fourth sending module 23 is configured to: and the second reset Module 22 is coupled to transmit traffic data to the base station based on the TA.

The user equipment in this embodiment can interact with the base station in the foregoing third embodiment. In this process, whether the service is transmitted on a single subcarrier, the TA can be easily estimated by using the foregoing method, so that the user equipment completes uplink synchronization.

In the fifth embodiment of the present disclosure, in the service maintenance process, if it is found that the situation is a single carrier or the TA cannot be estimated, the base station may send a PDCCH Order to the UE at the time of the TAT fast timeout, forcing the UE to initiate random access, and randomly connecting The incoming TA ensures uplink synchronization and avoids uplink out-of-synchronization. The uplink synchronization method in this embodiment is as shown in FIG. 6. The system function and the interaction process in the actual application scenario are described in conjunction with FIG. 6 . The uplink synchronization method may include:

Step 1: The UE starts the TAT timer after receiving the TAC or MSG4 message from the base station. After the random access is completed, the base station side starts the TAT timer. The MSG4 message is an RRC (Radio Resource Control) connection setup message.

Step 2: During the service, when the TAT timer (TAT_eNB timer) of the base station enters the fast timeout period, and the uplink BSR of the base station is not empty or the data of the downlink is to be sent, the UE can maintain the synchronization state for performing. For data transmission, the base station initiates a PDCCH Order (ie, MSG0), forcing the UE to initiate a random access.

The concept of the TAT fast timeout moment is shown in Figure 7. The TAT fast timeout period = TAT-(MSG0 scheduling duration + MSG2 scheduling duration + MSG1 transmission duration), and the PDCCH Order needs to avoid the DRX inactivity period. The formula principle is : DRX repeats its On Duration and Inactive time periodically. The UE only needs to listen to the dedicated PDCCH channel for the duration. During the non-active period, the UE remains silent to save power.

The UE may not monitor the PDCCH channel during the Inactive period. The TAT fast timeout period of the following PDCCH order may consider the DRX Inactive period, avoiding the DRX inactive period, and issuing the PDCCH Order, and ensuring that the UE is out of synchronization before the UE is out of synchronization. To the TAC, the scheduling time of the MSG0, the duration of the MSG1, and the scheduling duration of the MSG2 can also be considered.

Step 3: The UE blindly detects the PDCCH Order in its USS (UE-specific Search Space) space, and sends a preamble sequence (MSG1) to the base station.

Step 4: The base station estimates the TA according to the preamble sequence, and sends the calculated TA component TAC field to the RAR (Random Access Response) MAC PDU (Media Access Control Protocol Data Unit). UE (RAR MAC PDU is MSG2).

Step 5: The UE receives the RAR sent by the base station in the RAR time window of the CSS (Common Search Space) space, solves the TAC field and obtains the TA value, and restarts the TAT timer on the UE side, and sends the TAT timer. When the RRC Connection Request message is MSG3, the TA time is sent in advance.

Step 6: The base station receives the MSG3 sent by the UE, and resets the TAT timer on the base station side after the CRC (Cyclic Redundancy Check) check is passed.

The UE may start a TAT timer when receiving the TAC or MSG4 message of the base station; the base station may also start the TAT timer after the random access is completed. When the TAT timer of the UE is timed out, the UE may consider that the uplink is out of synchronization. Otherwise, the UE may consider that the uplink is synchronized. When the TAT timer of the base station expires, the base station may consider that the UE is currently out of synchronization, when the base station During the operation of the Timer, the base station can consider that the UE is currently synchronized.

When a UE enters the TAT fast timeout period, and the uplink BSR of the UE is not empty or the data is to be sent in the downlink, the base station may send a PDCCH Order to the UE to force the UE to re-initiate a random access. The TA in the random access is used to maintain the uplink synchronization of the UE.

When the UE receives the TAC of the base station, the UE may restart the TAT timer; the base station may reset the TAT timer in two places, one is when the TAC ACK (Acknowledgement) of the UE is received, and the second is the MSG3 CRC check. when.

The TAT fast timeout period can comprehensively consider the scheduling time of the MSG0, the scheduling time of the MSG2, and the duration of the MSG1, and avoid sending the PDCCH Order in the DRX inactivity period, so that the UE receives the TAC before the out-of-synchronization, and prevents the UE from losing the uplink.

The method proposed in the present disclosure is used to prevent the base station from influencing the data transmission and the user experience by increasing the uplink out-of-synchronization due to the estimation of the TA in the case of the single-subcarrier in the service maintenance process.

Those of ordinary skill in the art will appreciate that all or some of the steps, systems, and functional blocks/units of the methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be composed of several physical The components work together. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer readable medium, which may include computer storage media (or non-transitory media) and communication media (or transitory media). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and nonvolatile, implemented in any method or technology for storing information, such as computer readable instructions, data structures, program modules or other data. Sex, removable and non-removable media. Computer storage media include, but are not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), and Electrically Erasable Programmable Read-only Memory (EEPROM). Flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical disc storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device, or Any other medium used to store the desired information and that can be accessed by the computer. Moreover, it is well known to those skilled in the art that communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and can include any information delivery media. .

A person skilled in the art can understand that the technical solutions of the present disclosure may be modified or equivalent, without departing from the spirit and scope of the present disclosure, and should be included in the scope of the claims of the present disclosure.

Industrial applicability

Claims

A method of maintaining uplink synchronization, including:

The base station sends a physical downlink control channel command PDCCH Order to the user equipment when detecting that the remaining time of the timing assignment timer TAT of the user equipment reaches a preset time threshold;

Receiving, by the base station, a preamble sequence returned by the user equipment according to the PDCCH Order;

The base station estimates a timing advance TA according to the preamble sequence, and sends the TA to the user equipment, so that the user equipment maintains uplink synchronization according to the TA.
The method of claim 1, wherein the transmitting the PDCCH Order to the user equipment comprises:

Determine whether the BSR of the uplink buffer status is not empty or whether there is data to be sent in the downlink;

In a case that the uplink BSR is not empty or there is data to be transmitted in the downlink, the base station sends the PDCCH Order to the user equipment outside the inactivity period in which the user equipment discontinuously receives the DRX.
The method of claim 2, wherein

The preset time threshold=the total length of the TAT-(the scheduling duration of the PDCCH Order+the scheduling duration of the TA+the transmission duration of the preamble sequence).
The method of any of claims 1 to 3, the method further comprising:

The base station resets the TAT corresponding to the user equipment when receiving the service data from the user equipment.
A method of maintaining uplink synchronization, including:

The user equipment receives the physical downlink control channel command PDCCH Order from the base station, where the PDCCH Order is sent by the base station when the time delay of the timer assignment TAT of the user equipment is detected to reach a preset time threshold;

The user equipment sends a preamble sequence to the base station according to the PDCCH Order;

Receiving, by the user equipment, a time advancement amount TA returned by the base station according to the preamble sequence, and resetting a TAT corresponding to the user equipment;

The user equipment sends data to the base station according to the TA.
A base station comprising:

The first sending module is configured to: when detecting that the remaining time of the timing assignment timer TAT of the user equipment reaches a preset time threshold, send a physical downlink control channel command PDCCH Order to the user equipment;

a first receiving module, configured to: receive a preamble sequence returned by the user equipment according to the PDCCH Order;

An estimation module, configured to: estimate a timing advance TA according to the preamble sequence;

The second sending module is configured to: send the TA to the user equipment, so that the user equipment maintains uplink synchronization according to the TA.
The base station of claim 6, wherein the first sending module comprises:

The determining unit is configured to: determine whether the uplink buffer status report BSR is not empty or whether the downlink has data to be sent;

The sending unit is configured to: when the uplink BSR is not empty or the downlink has data to be sent, the base station sends a PDCCH Order to the user equipment outside the inactive period in which the user equipment discontinuously receives the DRX.
The base station according to claim 7, wherein the preset time threshold of the determining unit is determined as follows:

The preset time threshold=the total length of the TAT-(the scheduling duration of the PDCCH Order+the scheduling duration of the TA+the transmission duration of the preamble sequence).
The base station according to any one of claims 6 to 8, further comprising:

The first reset module is configured to: when the service data from the user equipment is received, reset the TAT corresponding to the user equipment.
A user equipment comprising:

The second receiving module is configured to: receive a physical downlink control channel command PDCCH Order from the base station, where the PDCCH order is sent by the base station when the time delay of the timer of the user equipment is detected to reach a preset time threshold of;

The third sending module is configured to: send a preamble sequence to the base station according to the PDCCH Order;

The second reset module is configured to: receive a timing advance TA returned by the base station according to the preamble sequence, and reset a TAT corresponding to the user equipment, to update the time to a total TAT duration;

The fourth sending module is configured to: send data to the base station according to the TA.
A computer readable storage medium storing computer executable instructions that, when executed, implement a method of maintaining uplink synchronization as claimed in any one of claims 1 to 5.