WO2008025288A1

WO2008025288A1 - A method and terminal for controlling connection reconstructing in lte system

Info

Publication number: WO2008025288A1
Application number: PCT/CN2007/070526
Authority: WO
Inventors: Hao Wu; Liyan Yin
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-08-24
Filing date: 2007-08-21
Publication date: 2008-03-06
Also published as: CN101132611A; CN101132611B

Abstract

A method for controlling connection reconstructing in LTE system is disclosed. In the said method, after detecting wireless link break, the terminal starts the process of initial accessing on initial accessing channel in the period of reconstructing delay. A relative terminal is also disclosed. The said terminal includes: a time setting unit to set the time of reconstructing delay according to the type of object cell to be searched; a detecting unit, which is connected with the time setting unit, to detect whether the time to reconstruct connection is exceed the time of reconstructing delay. In the solution above, the breaking connection canbe reconstructed successfully, and long time resources occupying is avoided.

Description

Method and terminal for controlling connection reconstruction in a long term evolution system This application claims to be Chinese patent filed on August 24, 2006, with the application number of 200610111381.6, and the invention titled "Method and Terminal for Control Connection Reconstruction in Long Term Evolution System" Priority of the application, the entire contents of which are incorporated herein by reference.

Technical field

The present invention relates to the field of communications technologies, and in particular, to a method and a terminal for controlling connection reestablishment in a long term evolution system.

Background technique

In order to make the 3GPP (The 3rd Generation Partnership Project) wireless access technology in a favorable position in the future of mobile communication technology, it is necessary to consider the long-term evolution of 3GPP wireless access technology. (LTE, Long Term Evolution). The goal of long-term evolution is to develop a framework for wireless access technologies with features such as high data rates, low response times, and optimal packet access. Therefore, important parts of LTE include reduced response times, higher user data rates, increased system capacity and coverage, and reduced operator cost.

Due to the inevitable obstacles and shields in the real network, these effects can cause the terminal to have poor signal quality at a certain time at a certain time, which may result in the loss of the wireless connection due to the failure of the wireless link. After the wireless connection is lost, the network does not immediately release the resources allocated to the terminal, but reserves these resources to wait for the terminal to perform the initial access process. Therefore, after the wireless connection is lost, the terminal should be able to perform cell search in a short time, for example, searching for a cell in the neighbor list, and after searching for a suitable cell, performing an initial access operation, for example, Establish an RRC (Radio Resource Control) connection or perform cell handover.

For example, in a WCDMA (Wideband Code Division Multiple Access) system, when the terminal wireless connection is lost, measurement of the physical channel is started, after 160 ms, based on the measured channel quality and a threshold. The values are compared, and if the channel quality is always less than the threshold within this 160 milliseconds, then the wireless link is considered to have failed. Then, the terminal searches for a cell, and after searching for the cell, the UE (customer equipment, user equipment) upper layer requests to initiate an RRC connection re-establishment process or a handover process. The UE's upper layer sends an RRC connection reestablishment through the common control channel. begging. The establishment process of the RRC connection includes an optional cell reselection, access control, and establishment of an L2 signaling connection.

If the initial access operation cannot be effectively controlled by the terminal as soon as possible, the network may retain resources for a long time, which may result in serious resource waste, which may reduce the cell throughput and affect system performance, especially for requirements. LTE systems with features such as high data rate, low response time, and optimal packet access.

Summary of the invention

The embodiments of the present invention provide a method for controlling connection reestablishment in a long term evolution system to effectively control reestablishment of a terminal RRC connection in an LTE system, thereby saving network resources.

Another aspect of the embodiments of the present invention provides a terminal to reduce the time for the RRC connection reestablishment of the terminal, and avoid long-term occupation of network resources.

To this end, the embodiments of the present invention provide the following technical solutions:

A method for controlling connection reestablishment in a long term evolution system, the method comprising:

The terminal detects that the wireless link fails.

The terminal begins performing an initial access operation on the initial access channel during the connection reestablishment delay time. A terminal, comprising: a transceiver unit,

a connection reconstruction delay time setting unit, configured to determine a delay time according to a type of the target cell that the terminal needs to search;

The detecting unit is connected to the connection re-establishment delay time setting unit, and is configured to detect whether the time of the terminal connection re-establishment execution exceeds the determined delay time.

It can be seen from the technical solutions provided by the foregoing embodiments of the present invention that, in the connection re-establishment process of the LTE system, determining a reasonable delay time according to the type of the target cell that the terminal needs to search, and controlling the terminal within the determined delay time. The connection re-establishment process is completed, so that the connection reconstruction is successful, and the network is prevented from retaining resources for a long time, thereby reducing the waste of network resources, ensuring the cell throughput, and reducing the impact of the reserved resources on the system performance.

DRAWINGS

1 is a flowchart of an implementation of a first embodiment of a method according to the present invention;

2 is a flowchart of an implementation of a second embodiment of a method according to the present invention;

3 is a schematic block diagram of one embodiment of a terminal of the present invention. detailed description

The embodiments of the present invention are directed to the LTE system requirements for reduced response time, higher user data rate, and system capacity. In the connection reestablishment process after the wireless connection is lost, a reasonable connection is determined according to the type of the target cell that the terminal needs to search. The reconstruction delay time is completed, and the control terminal completes the connection reconstruction process within a determined delay time.

The connection reestablishment delay time is determined by some or all of the time required to search for the cell, the time required to search for the sector, the time required to obtain the system information, and the delay generated by the initial access operation. Specifically, if the target cell to be searched, for example, the cell in the neighbor cell list maintained by the terminal, is located at the same frequency layer, the connection reconstruction delay time is required by the time required to search for the cell, the time required to read the system information, and the initial connection. The delay time caused by the incoming process is determined; if the target cell being searched is located at a different frequency layer, the connection reconstruction delay time is the product of the time required to search for the cell and the number of search cells, the time required to read the system information, and the initial connection The delay time caused by the incoming process is determined; in the case where the target cell has multiple sectors, the time required to search for the sector is also considered. The delay caused by the initial access procedure described above may be after the cell search and system information acquisition. For the case of transmitting the preamble, the access slot waiting for the transmission may be required to arrive. This waiting time is caused by the initial access procedure. Delay, in addition, in the case of transmitting a connection reestablishment request, the delay of the initial access includes the time to transmit the preamble and the correct response of the waiting network, in addition to waiting for the arrival of the access slot.

In order to enable the terminal to complete the connection re-establishment process in a reasonable time, the present invention needs to determine a reasonable connection re-establishment delay time according to factors required to perform the connection re-establishment process, and control the terminal to start the initial execution within the determined connection re-establishment delay time. Access operation. If the terminal fails to perform the initial access operation on the initial access channel within the determined connection re-establishment delay time, the connection failure processing is performed, or the connection re-establishment attempt is re-established, to avoid the network side retaining resources for a long time and affecting the cell throughput. .

After confirming the failure of the radio link, the terminal needs to perform cell search. After finding a suitable campable cell, it starts to receive relevant system information on the cell, and finds an appropriate RACH according to the information provided in the system information block (Randic Access Channel, random access channel), the initial access process. To this end, the present invention determines a reasonable connection reconstruction delay time based on the different conditions of the cell to be searched during the connection reconstruction process. The connection re-establishment process will be separately described below for the different operations that the terminal needs to perform during the connection re-establishment process.

(1) After the terminal detects the loss of the wireless connection, perform cell search, wherein the searched cells are all the same carrier frequency (this is determined by network planning, usually in order to increase the capacity, the operator will use the second, or third Frequency)) After searching for a cell whose signal strength meets the requirements, the relevant system information is received from the common channel of the cell, and then the initial access operation is performed. For example, a random access process or a handover process. If the service currently performed by the terminal requires data lossless quality of service, the terminal may send a forward handover request in the initial access procedure of the connection reestablishment, so that the network needs to perform data forwarding operation after the connection reestablishment is completed, and the terminal loses the link. The data on the former serving cell is forwarded to the target cell, and then sent by the target cell to the terminal to ensure data loss. For some services, such as voice services, a certain number of data packets are allowed to be lost, but the delay requirements are strict. After the connection is established, new data is directly sent and received, and there is no need to forward the data packets lost due to the loss of the wireless connection. In this case, an RRC connection re-establishment process is required.

(2) After the terminal detects that the wireless connection is lost, performing cell search, where the searched cell includes: a cell with the same carrier frequency and a cell with different carrier frequencies, and the terminal needs to adjust the frequency in addition to the cell of the same frequency. To search for cells of other frequencies, after searching for a cell whose signal strength meets the requirements, the relevant system information is received from the common channel of the cell, and then the initial access operation is performed.

(3) In the existing GSM (Global System for Mobile Communications) system, in order to expand the system capacity, when the traffic of a cell is too large, the cell will be divided into multiple sectors, and the corresponding antenna will be added. . Also, in the LTE system, one cell can be divided into a plurality of sectors during network planning. 4 Let one cell be divided into three sectors, then in this cell, the same common channel, such as a synchronization channel and a broadcast channel, may be used. However, the LTE system is a multi-carrier system based on OFDM (Orthogonal Frequency Division Multiplexing), which can allocate different frequency bands to different sectors, and different frequency bands may be configured with different pilot channels. Therefore, the pilots for each cell are different.

In this case, for the terminal, the cell search process can only detect the signal strength and channel quality of the cell common channel, and the terminal needs to select the cell to be camped according to the signal strength, and then the terminal needs to continue searching and detecting. The pilot channel of the sector is determined by comparing the channel quality Which sector of the cell is camped on. That is to say, when several sectors in a cell use the same common channel and different pilot channels, the terminal not only needs to search for the cell, but also searches for sectors in the cell. Then, in the above two processes, it is also necessary to increase the process of sector search, that is, after searching for the sector with the best signal quality, the initial access process is performed.

Therefore, the delay time determined by the present invention may specifically be the following:

(1) If the target cells to be searched are all of the same frequency layer, that is, the carrier frequency of the target cell is the same, then the connection reestablishment delay time TRRC_RE-ESTABLISH is:

TRRC— RE-ESTABLISH = Tsearch + TSI+ TRA

(2) If the target cell to be searched is at a different frequency layer, that is, the carrier frequency of the target cell is not the same, then the connection reestablishment delay time TRRC_RE-ESTABLISH is:

TRRC— RE-ESTABLISH = Nfrequency*Tsearch + TSI+ TRA

The meanings of the parameters in the above formulas are as follows:

Tsearch is the time required to search for a cell;

The TSI is the time required to read system information, including receiving relevant system information and high-level processing delay time of the system information block;

TRA is the delay time caused by the initial access procedure;

Nfrequency is the number of frequencies of the cell being searched.

(3) If the sector within the cell is also to be searched, the connection reestablishment delay time TRRC_RE-ESTABLISH is:

TRRC— RE-ESTABLISH = Tsearch + TSI+ TRA + Tsector ; or

TRRC—RE-ESTABLISH = Nfrequency*Tsearch + TSI+ TRA+ Tsector where Tsector is the time required to search for a sector.

In order to provide a person skilled in the art with a better understanding of the present invention, the method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

Referring to Figure 1, there is shown an implementation flow of a first embodiment of the method of the present invention. In this embodiment, the terminal needs to initiate an RRC Connection Reestablishment Request or a Transmit Preamble on the initial access channel within the determined connection reestablishment delay time.

Includes the following steps:

Step 101: Determine the delay time required for the connection re-establishment process. The determination of the delay time required for the connection reconstruction process has been described in detail above and will not be described herein.

Step 102: Set the timing value of the timer to the determined delay time value.

Step 103: After confirming that the radio link fails, the terminal starts a timer and performs an RRC connection reestablishment attempt.

The terminal can determine whether the wireless link fails by detecting the channel quality, and report the radio link failure to the lower layer of the terminal, for example, the physical layer, so that the physical layer performs cell search, system information reception, initial access, and the like. operating.

During this attempt, the terminal needs to do the following:

First, the terminal performs a cell search to determine a campable cell or sector; then, starts receiving system information on the determined cell or sector, and determines a random access channel according to the received system information; after the random access channel is determined, The terminal needs to start performing an access operation on the determined random access channel.

Step 104: Determine whether the timer time has arrived. If yes, go to step 105; otherwise, return to step 104 and wait for the timer time to arrive.

Step 105: Determine whether the terminal has started to send an RRC connection reestablishment request or preamble on the initial access channel. If it has already started, it proceeds to step 106; otherwise, it proceeds to step 107.

Step 106: Perform the normal processing flow.

Step 107: Perform connection failure processing, or re-initiate an RRC connection re-establishment attempt by the terminal. Referring to Figure 2, there is shown an implementation flow of a second embodiment of the method of the present invention. In this embodiment, the terminal needs to initiate a handover request on the initial access channel within the determined connection reestablishment delay time. The process includes the following steps:

Step 201: Determine the delay time required for the connection reconstruction process.

The determination of the delay time required for the connection reconstruction process has been described in detail above and will not be described herein.

Step 202: Set a timing value of the timer to a determined delay time value.

Step 203: After confirming that the radio link fails, the terminal starts a timer and performs a cell handover attempt.

The terminal can determine whether the wireless link fails by detecting the channel quality, and report the radio link failure to the lower layer of the terminal, for example, the physical layer, so that the physical layer performs cell search and system information again. Information reception and initial access operations.

During this attempt, the terminal needs to do the following:

First, the terminal performs a cell search, such as searching for a cell in the neighbor list maintained by the terminal, determining a campable cell or sector; and then starting to receive system information on the determined cell or sector, and according to the received system The information determines a random access channel; after the random access channel is determined, the terminal needs to start performing an access operation on the determined random access channel.

Step 204: Determine whether the timer time has arrived. If yes, go to step 205; otherwise, return to step 204 and wait for the timer time to arrive.

Step 205: Determine whether the terminal has started to send a handover request message on the initial access channel. If it has already started, it proceeds to step 206; otherwise, it proceeds to step 207.

Step 206: Perform a normal processing flow.

Step 207: Perform connection failure processing.

As can be seen from the above embodiment, the present invention determines the connection reestablishment delay time according to the type of the target cell that the terminal needs to search by analyzing the operation required for the connection re-establishment process, and the control terminal completes the connection re-establishment process within the delay time. With the invention, under the premise that the connection reconstruction is successfully executed, the occupation time of the system resources can be reduced, and the system capacity and throughput can be improved.

Referring to FIG. 3, FIG. 3 is a schematic block diagram of an embodiment of a terminal according to the present invention:

The terminal includes: a connection reestablishment delay time setting unit S11, a detecting unit S12, and a transceiving unit S13. The connection reestablishment delay time setting unit S11 is configured to determine the delay time according to the type of the target cell that the terminal needs to search; the detecting unit S12 is configured to detect whether the time for the terminal connection reestablishment execution exceeds the determined delay time, and if so, notify the terminal Performing a connection failure process, or re-initiating a connection re-establishment attempt by the terminal; the transceiver unit S13 is configured to receive or transmit a wireless signal.

Before the connection reconstruction, the connection reconstruction delay time setting unit S11 calculates the total delay time according to whether the target cell that the terminal needs to search for is in the same frequency layer, and whether each cell contains multiple sectors and the like, and sends the total delay time to the detection. Unit S12. The connection reconstruction delay time setting unit S11 can refer to the foregoing description of the method of the present invention for the determination of the connection reconstruction delay time, and details are not described herein again.

After the terminal confirms that the radio link has failed, the detecting unit S12 counts the delay time. If the actual connection reestablishment time is less than the delay time, that is, the connection reestablishment process is completed within the delay time, the connection reestablishment is considered to be successfully completed; otherwise, if the connection reestablishment request or the preamble is not sent after the delay time is exceeded, Then, the connection reestablishment fails, the terminal is notified to perform the connection failure processing, or the connection re-initiation is initiated by the terminal.

In a specific implementation, the transceiver unit S13 may send a notification message to the detecting unit S12 after transmitting an RRC connection reestablishment request, or a preamble, or a handover request to the network side. The detecting unit S12 internally sets a timer to time the delay time, and when the timer time arrives, sends an interrupt message to the detecting unit. In this way, the detecting unit S12 can judge whether the time for the terminal connection re-establishment execution exceeds the determined delay time according to the notification message sent by the transceiver unit S13 and the interrupt message of the internal timer. If the notification message is received before the interruption message is received, it indicates that the connection re-establishment is successfully completed. At this time, the timer can be reset, and the timer is restarted after the next time the terminal confirms that the radio link has failed. If the interrupt message is received before the notification message is received, it indicates that the terminal does not complete the sending operation on the initial access channel within the set connection reestablishment delay time. At this time, the connection reestablishment failure is considered, and the terminal is notified. The connection failure processing is performed, or the connection re-initiation attempt is re-initiated by the terminal.

It can be seen that, by using the terminal of the present invention, it is possible to effectively prevent the network side from retaining resources for a long time and waste the network resources, thereby ensuring the performance of the LTE system.

While the invention has been described by the embodiments of the present invention, it will be understood that

Claims

Rights request

The terminal detects that the wireless link fails.

The terminal starts performing the initial access operation on the initial access channel during the connection reestablishment delay time.

2. The method according to claim 1, wherein the connection reestablishment delay time is determined by part or all of the following: time required to search for a cell, time required to search for a sector, and required to acquire system information Time and delay caused by initial access operations.

3. The method of claim 2, wherein

When a cell of a different frequency needs to be searched, the time required to search for the cell is determined by the number of different frequencies of the search cell.

The method of claim 1, wherein the process of starting the initial access operation on the initial access channel by the terminal during the connection reestablishment delay time comprises:

The terminal performs a cell search to determine a campable cell or sector;

Receiving system information on the determined cell or sector, and determining an initial access channel according to the received system information;

The terminal begins performing an initial access operation on the determined initial access channel during the reestablishment delay time.

The method according to any one of claims 1 to 4, wherein the initial access operation is specifically: the terminal sends a radio resource control connection reestablishment request message on the initial access channel.

The method according to any one of claims 1 to 4, wherein the initial access operation is specifically: the terminal sends a preamble on the initial access channel.

The method according to any one of claims 1 to 4, wherein the initial access operation is specifically: the terminal sends a handover request message on the initial access channel.

8. The method of claim 1, wherein the method further comprises:

If the terminal fails to start the initial access operation within the connection re-establishment delay time, the connection failure process is performed, or the connection re-attempt attempt is re-initiated by the terminal.

A terminal, comprising: a transceiver unit, further comprising:

a connection reconstruction delay time setting unit, configured to determine according to the type of the target cell that the terminal needs to search Delay time

The terminal according to claim 9, wherein the detecting unit counts the connection reconstruction execution time by a timer provided therein, and performs a delay time set by the connection reconstruction delay time setting unit. In comparison, if the connection re-establishment execution time exceeds the delay time, the terminal is triggered to perform a connection failure process or re-initiate a connection re-establishment attempt.