KR101757295B1 - Method of reliable handover signaling procedure in a Broadband Wireless Access System - Google Patents

Abstract

The present invention relates to a broadband wireless access system, and more particularly, to a method for confirming whether a mobile station exists in a coverage of a serving base station during a handover process and a device for performing the same in order to perform a more reliable handover will be.
According to another aspect of the present invention, there is provided a method for performing an existence check procedure in a handover of a broadband wireless access system, the method including receiving a first signal for requesting presence from a serving base station, step; And transmitting a second signal for the presence acknowledgment to the serving base station. Here, the first signal may be received after a first time point, which represents a time limit at which the MS performs network re-entry to the target BS, has elapsed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a reliable handover signaling procedure in a broadband wireless access system,

The present invention relates to a broadband wireless access system, and more particularly, to a method for confirming whether a mobile station exists in a coverage of a serving base station during a handover process and a device for performing the same in order to perform a more reliable handover will be.

Handover (HO) refers to the movement of a mobile station from a radio interface of one base station to a radio interface of another base station. Hereinafter, a handover procedure in a general IEEE 802.16e system will be described.

In the IEEE 802.16 network, a Serving Base Station (SBS) transmits neighbor base station information to a mobile station (MS) (MOB_NBR) in order to inform basic network configuration information (topology) -ADV) message. ≪ / RTI >

The MOB_NBR-ADV message includes system information about a serving BS and neighbor BSs, for example, a preamble index, a frequency, a degree of HO optimization and a DCD (Downlink Channel Descriptor) / UCD (Uplink Channel Descriptor) information.

The DCD / UCD information includes information that the UE needs to know in order to perform information communication through the downlink and the uplink in the UE. For example, there are information such as HO trigger information, MAC version (Medium Access Control version) of the base station, and Media Independent Handover Capability (MIH) capability.

In a general MOB_NBR-ADV message, only information on neighboring BSs of the IEEE 802.16e type is included. Accordingly, neighboring base station information having a type other than IEEE 802.16e can be broadcasted to terminals through a Service Identity Information ADVertisement (SII-ADV) message. Accordingly, the UE can acquire information on the heterogeneous network base station by requesting the serving base station to transmit the SII-ADV message.

A procedure in which a terminal that has acquired information of a neighboring base station through the above-described method performs a handover in an IEEE 802.16e network will be described in detail with reference to FIG.

1 shows an example of a handover procedure that can be performed in an IEEE 802.16e system.

Referring to FIG. 1, a mobile station (MS) is connected to a serving base station (SBS) to perform data exchange (S101).

The serving base station periodically broadcasts information on a neighboring base station located in the serving base station to the terminal through the MOB_NBR-ADV message (S102).

The MS may start scanning for candidate HO BSs using a handover trigger condition during communication with the serving BS. If the MS exceeds a handover condition, for example, a predetermined hysteresis margin value, the MS may send a handover request message (MOB_MSHO-REQ) to the serving BS to request handover procedure (S103).

The serving BS can inform the candidate BSs included in the MOB_MSHO-REQ message of the handover request of the MS through the HO-REQ message (S104).

The candidate base stations (Candidate HO BSs) may perform a preliminary action for the UE requesting the handover and may forward information related to the handover to the serving BS through the HO-RSP message (S105).

The serving BS can transmit information related to the handover obtained through the HO-RSP message from the candidate BSs to the MS through a handover response (MOB_BSHO-RSP) message. Herein, the MOB_BSHO-RSP message includes information for performing handover such as an operation time for handover, a handover identifier (HO-ID), and a dedicated handover CDMA ranging code (S106).

The UE can determine one target base station among the candidate base stations based on the information included in the MOB_BSHO-RSP message received from the serving base station. Accordingly, the MS may attempt ranging by transmitting a CDMA code to the determined target BS (S107).

Upon receiving the CDMA code, the target BS can transmit the ranging success and physical correction values to the MS through a ranging response (RNG-RSP) message (S108).

Next, the mobile station can transmit a ranging request (RNG-REQ) message for authentication to the target base station (S109).

The target BS receiving the ranging request message of the MS can provide the MS with system information and the like that can be used by the corresponding BS, such as a CID (Connection IDentifier), through a ranging response message (S110).

If the target BS has successfully completed the authentication of the MS and has sent all of the update information, the target BS can inform the serving BS of the MS of the success of the handover through the HO-CMPT (S111).

After that, the MS may exchange information with the target BS that performed the handover (S112).

The handover procedure that can be performed in the IEEE 802.16m system is similar to the handover procedure of the IEEE 802.16e system described above. However, the names of the following messages may be different.

MOB_NBR-ADV -> AAI_NBR-ADV: The message includes system information transmitted in the form of S-SFH instead of DCD / UCD.

MSHO-REQ -> AAI_HO-REQ

BSHO-RSP -> AAI_HO-CMD

RNG-REQ (CDMA code) -> Ranging preamble code

RNG-RSP (ranging status) - > AAI_RNG-ACK (ranging status)

RNG-REQ (MAC message) -> AAI_RNG-REQ

RNG-RSP -> AAI_RNG-RSP: The message contains the station identifier TSTID or STID instead of the CID.

During the handover procedure, when the UE or the serving BS discards a Medium Access Control (MAC) management message (e.g., an AAI_HO-CMD message) related to a handover during a handover attempt due to channel condition deterioration or the like Can occur. In this case, the UE can not receive the scheduling from the serving BS after a predetermined time even though the UE can not attempt the handover to the target BS.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a more efficient handover method and an apparatus therefor.

It is another object of the present invention to provide a method for efficiently performing a procedure for checking existence of a UE during a handover that can minimize a downtime even if a MAC message related to a handover is lost between a serving BS and a terminal during handover, And to provide an apparatus for the same.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to another aspect of the present invention, there is provided a method for performing an existence check procedure in a handover of a broadband wireless access system, the method including receiving a first signal for requesting presence from a serving base station, step; And transmitting a second signal for the presence acknowledgment to the serving base station. Here, the first signal may be received after a first time point, which represents a time limit at which the MS performs network re-entry to the target BS, has elapsed.

At this time, the serving BS transmits the first signal to the MS if the target BS does not notify the serving BS of the completion of the handover until the first time has elapsed.

The first signal is an UL grant signal including uplink allocation information and the second signal is a padding protocol data unit padding transmitted through an uplink resource indicated by the uplink grant signal. PDU) or a medium access control protocol data unit (MPDU).

Also, the first signal is an unsolicited AAI_RNG-RSP message in which a bit for requesting ranging is set to the UE, and the second signal is a periodic ranging code Do.

Receiving a ranging acknowledgment (AAI_RNG-ACK) message indicating a ranging success state from the serving base station; And transmitting a ranging acknowledgment (AAI_RNG-CFM) message including an identifier of the UE to the serving base station.

In addition, it is preferable that the first time point is a ranging starting limit line (Ranging_Initiation_Deadline).

According to another aspect of the present invention, there is provided a method for performing a procedure for checking whether a serving BS exists in a handover of a broadband wireless access system, Transmitting; And receiving a second signal for presence confirmation from the terminal. Here, the first signal may be transmitted to the mobile station after a time limit at which the mobile station performs network re-entry to the target base station has elapsed.

In this case, the step of transmitting the first signal may be performed when the end notification of the handover is not received from the target BS until the threshold time elapses.

In addition, the first signal is an UL grant signal including uplink allocation information and the second signal is a padding PDU or a medium access control protocol data unit (MPDU) .

Also, the first signal is an unsolicited AAI_RNG-RSP message in which a bit for requesting ranging is set to the UE, and the second signal is a periodic ranging code Do.

Transmitting a ranging acknowledgment (AAI_RNG-ACK) message indicating a ranging success state to the MS if the code is successfully received; And receiving a ranging acknowledgment (AAI_RNG-CFM) message including the identifier of the terminal from the terminal.

Also, the threshold time point is preferably a ranging starting limit line (Ranging_Initiation_Deadline).

According to another aspect of the present invention, there is provided a mobile terminal operating in a broadband wireless access system, the mobile terminal including: a processor; And a wireless communication (RF) module for transmitting / receiving a wireless signal to / from the outside under the control of the processor. Here, the processor controls the second base station to transmit a second signal for confirming existence to the serving base station when a first signal for requesting presence confirmation is received from the serving base station, It is preferable that a first time point indicating a threshold time point at which network re-entry is performed to the target base station has elapsed and is received.

In this case, the serving BS transmits the first signal to the MS if the target BS does not notify the serving BS of the end of the handover until the first time has elapsed.

The first signal is an UL grant signal including uplink allocation information and the second signal is a padding protocol data unit padding transmitted through an uplink resource indicated by the uplink grant signal. PDU) or a medium access control protocol data unit (MPDU).

Preferably, the first signal is an unsolicited AAI_RNG-RSP message in which a bit for requesting ranging is set, and the second signal is a periodic ranging code.

The AAA_RNG-ACK message includes a ranging acknowledgment (AAI_RNG-CFM) including an identifier of the mobile station to the serving BS when the ranging acknowledgment (AAI_RNG-ACK) message indicating the ranging success state is received from the serving BS, The message can be controlled to be transmitted.

In addition, it is preferable that the first time point is a ranging starting limit line (Ranging_Initiation_Deadline).

According to the embodiments of the present invention, the following effects are obtained.

First, since the interruption time is minimized, a more reliable handover can be performed.

Second, even if the MAC message is lost between the serving BS and the MS during the handover, the serving BS can confirm the existence of the MS, so that more reliable handover can be performed.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

1 shows an example of a handover procedure that can be performed in an IEEE 802.16e system.
2 shows an example of a handover procedure in a general IEEE 802.16m system.
FIG. 3 shows an example of an existence check procedure according to an embodiment of the present invention.
FIG. 4 shows an example of a procedure for confirming existence of a response message to a handover indication message according to an embodiment of the present invention.
FIG. 5 shows another example of the existence check procedure when a response message to a handover indication message according to an embodiment of the present invention is requested.
FIG. 6 shows another example of the existence check procedure when a response message to a handover indication message according to an embodiment of the present invention is requested.
FIG. 7 illustrates an example of an existence checking procedure in an EBB handover according to an embodiment of the present invention.
8 is a block diagram showing an example of a structure of a transmitting end and a receiving end according to another embodiment of the present invention.

In order to solve the above-described problems, the present invention discloses a more efficient handover procedure and an apparatus for performing the same.

The following embodiments are a combination of elements and features of the present invention in a predetermined form. Each component or characteristic may be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some of the elements and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

Herein, the embodiments of the present invention have been described with reference to the data transmission / reception relationship between the base station and the terminal. Here, the BS has a meaning as a terminal node of a network that directly communicates with the MS. The specific operation described herein as performed by the base station may be performed by an upper node of the base station, as the case may be.

That is, it is apparent that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. The term 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point (AP) The term 'terminal' may be replaced with terms such as a UE (User Equipment), an MS (Mobile Station), an MSS (Mobile Subscriber Station), an AMS (Advanced MS), or an SS (Subscriber Station).

Embodiments of the present invention may be implemented by various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For a hardware implementation, the method according to embodiments of the present invention may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) , Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to embodiments of the present invention may be implemented in the form of a module, a procedure or a function for performing the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the IEEE 802 systems, 3GPP systems, 3GPP LTE systems and 3GPP2 systems, which are wireless access systems. That is, the steps or portions of the embodiments of the present invention that are not described in order to clearly illustrate the technical idea of the present invention can be supported by the documents. In addition, all terms disclosed in this document may be described by the standard document. In particular, embodiments of the present invention may be supported by one or more of the standard documents P802.16-2004, P802.16e-2005, P802.16Rev2, and IEEE P802.16m documents of the IEEE 802.16 system.

The specific terminology used in the following description is provided to aid understanding of the present invention, and the use of such specific terminology may be changed into other forms without departing from the technical idea of the present invention.

Hereinafter, a handover procedure in the IEEE 802.16m system will be described.

Currently, in IEEE 802.16m, HO is divided into three procedures: HO decision and Initiation, HO preparation and HO Execution. Before performing these three procedures, the terminal needs a procedure of collecting information on neighboring base stations. This scanning process is similar to the scanning process in a general IEEE 802.16e network. However, when there is an interval in which the terminal does not communicate with the S-ABS, it can scan peripheral base stations using the interval.

In the HO decision and initiation procedure, a terminal or a base station can initiate a handover procedure. When the UE starts the handover, the UE transmits a handover request (AAI_HO-REQ) message to the serving BS. At this time, the UE determines whether to perform the EBB handover according to the determination of the BS.

In the HO preparation procedure, terminal information is exchanged between the serving base station (S-ABS) and the target base station (T-ABS), and the conditions for the HO execution procedure and the resources (dedicated code, STID, security parameters, do. Depending on the situation, the S-ABS may give the terminal a plurality of T-ABSs. When the UE initiates the HO, it requests the HO through the AAI-HO-REQ message and receives the above-mentioned information from the base station through the handover command (AAI_HO-CMD). In this case, the AAI_HO-CMD message includes an action time and a disconnect time. The action time is a time for the UE to perform a network re-entry. It means the time to stop allocation of uplink / downlink (DL / UL) resources.

In HO execution procedure, it is time to perform network reentry procedure with T-ABS according to action time. At this time, network re-entry is possible through the CDMA ranging or immediate ranging request (AAI_RNG-REQ) message. When the terminal performs an EBB (Entry Before Brake), it continuously communicates information to the S-ABS in a predetermined available interval (AI), and performs a network reentry procedure to the T-ABS in an unavailable interval (UAI) . When a terminal performs a BBE (Break Before Entry) handover, an AI or UAI is not determined, and the procedure is the same as that of a hard handover of a general IEEE 802.16e network.

The above-described handover procedure will be described in more detail with reference to FIG.

2 shows an example of a handover procedure in a general IEEE 802.16m system.

Referring to FIG. 2, the serving BS may start the handover procedure (S201a) or may start the terminal (S201b). When the UE starts a handover, there is a procedure of transmitting a handover request (AAI_HO-REQ) message to the serving BS to request a handover. However, the serving BS may perform a handover procedure without receiving a corresponding message from the UE .

Upon receiving the handover command (AAI_HO-CMD) message from the serving base station, the terminal may selectively transmit a handover indication (AAI_HO-IND) message to the serving base station (S202). The conditions for transmitting a handover indication message to a serving base station are as follows.

1) When you want to cancel HO based on the conditions set by S-ABS

2) When a plurality of candidate target base stations included in the AAI_HO-CMD message are selected and one of them is selected

3) All candidate target base stations included in the AAI_HO-CMD message can not be accessed

4) If the connection with the serving base station can not be maintained before the disconnect time expires

Thereafter, the terminal performs network re-entry to the target base station (S203).

If there is scheduling of the serving base station before performing the EBB handover or before the disconnect time expires, the terminal may exchange data with the serving base station during the network re-entry procedure (S204).

When the network re-entry is completed, the target BS informs the serving BS of the end of the handover (S205), and the MS can normally exchange data with the target BS (S206).

In the handover procedure, the UE transmits a handover request (AAI_HO-REQ) message to the serving BS to initiate a handover procedure. The serving BS transmits a handover command (AAI_HO-CMD) Over. At this time, if the UE or the BS fails to successfully transmit or receive the handover-related MAC management message, there may be a problem in the handover procedure.

For example, when the UE initiates the handover, the handover is initiated through the AAI_HO-REQ message transmission. When the UE receives the AAI_HO-CMD message from the S-ABS, the handover is performed in earnest. In this case, if the AAI_HO-CMD message is lost and the UE can not receive the AAI_HO-CMD message, the base station retransmits the AAI_HO-CMD or retransmits the AAI_HO-REQ message to guarantee the stability of the handover procedure .

However, if the BS instructs the handover (BS initiated HO), if the UE does not normally receive the AAI_HO-CMD message, a serious problem may occur in the handover. As described above, the AAI_HO-CMD message includes 'disconnect time' information indicating a time point at which the serving BS ends the scheduling for the UE during handover. If the UE fails to receive the AAI_HO-CMD message including the ACI_HO-CMD message, the UE does not receive the scheduling (resource allocation) after the disconnect time. However, the UE does not know whether this situation is caused by the handover procedure. Therefore, in such a case, the operation of the terminal needs to be defined.

In addition, when the MS performs the network re-entry to the target BS and the handover procedure is completed, the target BS informs the serving BS of the end of the handover through the backhaul, and the backbone network message has a relatively large delay. Therefore, in order to prevent waste of resources allocated to the mobile station by the serving base station even before the disconnect time, a method for the serving base station to quickly determine that the mobile station no longer exists in the coverage of the serving base station is required.

In addition, when the MS initiates a handover, if a handover request message transmitted from the MS to the serving BS is lost and the BS can not normally receive the handover request message, additional operations of the MS need to be defined.

Confirm existence of terminal

According to an embodiment of the present invention, a method of checking the existence of a terminal (AMS presence check) in case the handover command (AAI_HO-CMD) message is lost is proposed.

That is, regardless of whether the AAI_HO-CMD message is successfully received, the serving base station will terminate the communication with the terminal according to the Disconnect Time. Accordingly, the UE does not receive the scheduling from the serving BS after the Disconnect Time, but the UE does not know the cause of the situation and thus a problem occurs.

Accordingly, in the present embodiment, in order to avoid such an ambiguous situation, the S-ABS base station provides a method of confirming whether the terminal has received the AAI_HO-CMD or whether there is a terminal in its coverage. Hereinafter, the procedure for confirming the reception of the AAI_HO-CMD message of the terminal or the presence of the terminal is referred to as a "presence check" procedure.

1) How to identify existence

A specific method of performing the existence checking procedure according to the present exemplary embodiment may be performed through a procedure of requesting the serving base station to confirm presence in the terminal and a procedure of receiving a response to the request from the terminal.

In order to request the presence confirmation, the serving BS may transmit a MAC message to the UE or allocate an UL grant to the UE.

When an uplink grant is used, the UE transmits a padding protocol data unit (hereinafter referred to as "PDU") or an MPDU (MAC PDU) as an uplink resource indicated by the uplink grant in response to the allocated uplink grant To the serving base station through the base station.

As another example of a fixed-amount link grant, the serving BS can assign UL grant (BR grant) for bandwidth request to the MS. The MS can perform the existence verification procedure by transmitting a bandwidth request code (BR code) to the serving BS in response to the request.

When a MAC message is used, an unsolicited AAI_RNG-RSP (Unsolicited AAI_RNG-RSP) message is generated in which a ranging request bit is set (for example, set to '1' ) Message may be used. If an unsolicited ranging response message is received from the serving base station, the terminal may perform ranging to respond to it. In this case, the ranging performed by the UE is preferably periodic ranging, and the UE may transmit a periodic ranging code to the serving BS to perform periodic ranging. When the periodic ranging code is received from the UE, the serving BS can additionally transmit a ranging acknowledgment (AAI_RNG-ACK) message to the UE. At this time, the ranging acknowledgment message may include information indicating a ranging success state and a periodic ranging code transmitted from the terminal. When the ranging acknowledgment message is received from the serving base station, the UE requests uplink resource allocation and transmits a ranging acknowledgment (AAI_RNG-CFM) message in response thereto. At this time, the ranging acknowledgment message may include the station's station identifier (STID). If the ranging acknowledgment message includes a MAC control extended header (MCEH) with a polling bit set to 1, the serving BS can further transmit a message acknowledgment (AAI_MSG-ACK) message to the MS.

As another example where a MAC message is used, a newly defined message (e.g., AAI_PCHECK-REQ / RSP) may be used for presence verification.

The existence checking procedures described above may be used independently or together. For example, the serving BS may allocate the uplink grant to perform the existence check procedure, and if there is no response from the MS after the predetermined number of times, the serving BS may perform the presence check procedure using the MAC message. Also, some messages may be omitted in the existence confirmation procedure using the MAC message.

2) When to perform the existence check procedure

Since the problem caused by the suspension of the scheduling for the UE occurs after the Disconnect Time, the serving BS preferably confirms whether the AAI_HO-CMD message has been successfully received after the Disconnect Time, but may be performed before that.

Alternatively, a ranging starting limit line (Ranging_Initiation_Deadline) indicating a threshold time for expecting reception of a ranging request message for network re-entry from a terminal performing a handover in the target base station is set during handover. Since the ranging threshold is also known, the serving BS can initiate the existence check procedure if there is no HO completion notification from the target BS through the backbone network after the ranging start threshold .

When the UE receives the handover command message at the start time of another existence confirmation procedure, it proposes to transmit a response message for the handover command message, for example, an AAI_HO-IND message, to the serving base station within a predetermined time . Accordingly, if a handover indication message is not received from the UE within a predetermined time after transmitting the handover command message, the serving BS can start the existence checking procedure. A more detailed procedure using the response message for the handover command message will be described later.

On the other hand, even when a hybrid automatic repeat request (HARQ) response to the MPDU including the MAC message (i.e., AAI_HO-CMD) is not received or a NACK is received even though retransmission is performed for the maximum number of retransmissions, have.

It is preferable that the above existence checking procedure is performed when the S-ABS instructs handover (BS initiated HO) in the handover process. This is because the UE expects to receive the AAI_HO-CMD message in the case of the handover initiated by the UE.

However, the present invention does not exclude performing the existence check procedure even in the case of the handover initiated by the terminal.

3) Specific Embodiment

Hereinafter, the existence checking procedure according to an embodiment of the present invention will be described in more detail with reference to FIG. 3 to FIG.

FIG. 3 shows an example of an existence check procedure according to an embodiment of the present invention.

Referring to FIG. 3, the serving BS can determine a handover of the MS according to a predetermined condition, and can exchange a handover request / response message with the target BS in step S301 and S302.

The serving base station transmits a handover command (AAI_HO-CMD) message to the mobile station in order to instruct the mobile station to perform handover, but the mobile station does not successfully receive the handover command (S303).

Accordingly, the UE can receive the normal scheduling from the serving BS until the Disconnect Time (S304), but after that, the UE experiences an interruption time (S305) in which it can not receive the scheduling from the serving BS without knowing the reason.

On the other hand, the terminal does not know the handover procedure initiated by the base station and will not transmit the ranging request message to the target base station even if the ranging starting limit line (Ranging_Initiation_Deadline) expires. Accordingly, the target BS can notify the serving BS through the backbone network that the handover procedure is not normally performed (handover failure).

When the serving base station notifies the handover failure of the target base station, the serving base station performs the existence check procedure to request the terminal to confirm presence (S307). When the terminal performs the response (S308), the serving base station resumes the scheduling for the terminal (S309).

At this time, the method for the existence confirmation procedure is as described above, so the overlapping description will be omitted.

Thereafter, the serving base station exchanges a handover request / response message with the target base station in order to instruct handover to the mobile station (S310, S311), and transmits a handover command (AAI_HO-CMD) message to the mobile station based on the handover request / response message. At this time, since the handover procedure is newly started, it is preferable that the Disconnect time and Ranging Initiation Line (Ranging_Initiation_Deadline) are renewed to a new value.

If there is no response from the UE to the existence confirmation request (S307), the serving BS starts the resource retention timer and releases the connection context of the corresponding terminal when the resource retention timer expires . The resource retention timer may be released when the UE enters the serving BS again or if there is a handover completion notification from another BS.

Hereinafter, a case where a mobile station transmits a response message to a handover command message with reference to FIG. 4 to FIG. 6, and a case where a serving base station performs an existence check procedure when a response message is not received will be described.

First, the case in which the existence checking procedure is performed before the ranging starting limit line (Ranging_Initiation_Deadline) will be described with reference to FIG.

FIG. 4 shows an example of a procedure for confirming existence of a response message to a handover indication message according to an embodiment of the present invention.

Referring to FIG. 4, the serving BS can determine handover of the MS according to a predetermined condition, and can exchange a handover request / response message with the target BS in step S401 and S402.

The serving base station transmits a handover command (AAI_HO-CMD) message to the mobile station in order to instruct the mobile station to perform handover, but the mobile station does not successfully receive the handover command (S403). In this case, if the MS always transmits a specific MAC message, for example, a handover indication (AAI_HO-IND) to the serving BS in response to the handover command message, or if a bit indicating a response to the handover command message is set, The BS expects the MAC message from the MS.

However, since the UE has not received the handover command message, the UE does not transmit a response message to the serving base station in step S404.

The serving base station can perform the presence confirmation procedure (S405, S406) if there is no response to the handover indication message from the terminal until a certain point in time (e.g., Disconnect time).

If the existence confirmation procedure is successfully completed, the serving base station can start the handover procedure again. That is, after the serving base station completes the information exchange related to the handover with the target base station (S407, S408), the serving base station retransmits the handover command message to the terminal (S409), and the terminal successfully receives the handover command message (I.e., a handover indication message) to the serving base station (S410).

Thereafter, the MS may perform a network re-entry procedure to the target BS (S411).

On the other hand, the existence checking procedure may be performed after the ranging starting limit line (Ranging_Initiation_Deadline). This will be described with reference to FIG.

FIG. 5 shows another example of the existence check procedure when a response message to a handover indication message according to an embodiment of the present invention is requested.

In FIG. 5, steps S501 to S504 are similar to steps S401 to S404 of FIG. 4, so duplicate descriptions will be omitted for simplicity of description.

Since the UE has not received the handover command message, the UE does not attempt ranging to the target BS until the ranging starting limit line (Ranging_Initiation_Deadline) has passed. The target base station can notify the serving base station of the handover failure through the backbone network as the ranging starting limit line (Ranging_Initiation_Deadline) is exceeded (S505).

If the target base station reports a handover failure or there is no handover completion notification even after the ranging start limit has been reached from the target base station, the serving base station can perform the existence checking procedure (S506, S507).

The procedures (S508 to S512) after the existence confirmation procedure has been successfully completed are similar to the steps S407 to S411 of FIG. 4, and thus duplicate descriptions will be omitted.

On the other hand, if there is no response from the UE to the handover indication message, the serving BS can repeatedly retransmit the handover indication message a predetermined number of times. This will be described with reference to FIG.

FIG. 6 shows another example of the existence check procedure when a response message to a handover indication message according to an embodiment of the present invention is requested.

Referring to FIG. 6, the serving BS can determine a handover of the MS according to a predetermined condition, and can exchange a handover request / response message with the target BS in step S601 and S602.

The serving base station transmits a handover command (AAI_HO-CMD) message to the mobile station in order to instruct handover to the mobile station, but the mobile station does not successfully receive the handover command (S603) It is not transmitted to the base station (S604).

The serving base station updates the Disconnect Time when a response message is not received from the UE until a predetermined time, and retransmits the handover indication message to the UE by a preset number of times until a response to the response is received (S605). If the target base station notifies the handover failure through the backbone network in step S607, the target base station does not receive a response message from the terminal despite the retransmission of the handover command message a predetermined number of times (S606) , The serving base station can perform the existence checking procedure (S608, S609).

The procedures (S610 to S616) after the existence confirmation procedure is successfully completed are similar to the S407 to S411 procedures of FIG. 4, and therefore duplicate explanations are omitted.

According to another aspect of the present embodiment, the existence checking procedure can be applied to an EBB (hand-over) type handover. This will be described with reference to FIG.

FIG. 7 illustrates an example of an existence checking procedure in an EBB handover according to an embodiment of the present invention.

Referring to FIG. 7, in step S701, the UE determines handover start according to a predetermined condition and transmits a handover request (AAI_HO-REQ) message to the serving base station (S702) ).

Accordingly, the serving BS can exchange the handover information with the target BS through the handover request / response message (S703, S704).

The serving base station transmits a handover command message to the mobile station (S705). The serving base station may include EBB handover coordination information and action time information indicating a time point at which the target base station performs network re-entry.

The EBB handover adjustment information may include information on a period in which the serving base station does not communicate with the serving base station, that is, a handover re-entry interleaving interval (HO_Reentry_Interleaving_Interval, or an unavailable interval) according to the scheduling of the serving base station.

In step 706, the target BS transmits a ranging acknowledgment (AAI_RNG-ACK) including the ranging success and the physical correction value to the target BS in step S706. Message to the terminal (S707).

The serving BS schedules the UE to the next incapable period. At this time, the serving BS does not know whether the UE exists in its own coverage, A confirmation procedure can be performed (S708, S709).

In this case, the UE may perform the CQICH report by requesting the CQICH through a dedicated channel quality information indication channel (CQICH) (S710).

If the existence check procedure is successfully performed, the serving BS can allocate resources to the MS and perform data exchange (S711).

If the next incapable interval comes, the terminal can perform the remaining handover procedure with the target base station (S712 to S714). The remaining handover procedure is similar to the general handover procedure, so redundant description is omitted.

Terminal and base station structure

Hereinafter, a terminal and a base station (FBS, MBS) in which the embodiments of the present invention can be performed will be described as another embodiment of the present invention.

The terminal may operate as a transmitter in an uplink and as a receiver in a downlink. In addition, the base station can operate as a receiver in an uplink and operate as a transmitter in a downlink. That is, the terminal and the base station may include a transmitter and a receiver for transmission of information or data.

The transmitter and receiver may comprise a processor, module, part and / or means, etc., for performing embodiments of the present invention. In particular, the transmitter and receiver may include a module (means) for encrypting the message, a module for interpreting the encrypted message, an antenna for transmitting and receiving the message, and the like. An example of such a transmitting end and a receiving end will be described with reference to Fig.

8 is a block diagram showing an example of a structure of a transmitting end and a receiving end according to another embodiment of the present invention.

Referring to FIG. 8, the left side shows the structure of the transmitting end, and the right side shows the structure of the receiving end. Each of the transmitting end and the receiving end includes antennas 5 and 10, processors 20 and 30, transmission modules (Tx modules 40 and 50), reception modules (Rx modules 60 and 70), and memories 80 and 90 . Each component can perform a function corresponding to each other. Each component will be described in more detail below.

The antennas 5 and 10 transmit the signals generated by the transmission modules 40 and 50 to the outside or receive radio signals from the outside and transmit the signals to the reception modules 60 and 70. If a multi-antenna (MIMO) function is supported, more than two may be provided.

The antenna, the transmitting module and the receiving module can together form a wireless communication (RF) module.

The processors 20 and 30 typically control the overall operation of the mobile terminal as a whole. For example, a controller function, a service characteristic, and a MAC (Medium Access Control) frame variable control function, a handover function, an authentication and encryption function, and the like for performing the above- . More specifically, the processors 20 and 30 can perform overall control for performing the handover procedure shown in FIGS.

In particular, when there is a presence confirmation request from the serving base station in the handover process, the processor of the mobile terminal can perform a presence verification procedure by transmitting a response corresponding to the type of presence confirmation request to the serving base station.

In addition, if a bit indicating that a response message is to be transmitted is set in the handover command message, or if it is predetermined to always transmit a response message to the handover command message, the corresponding message can be transmitted to the serving base station.

In addition, the processor of the terminal may perform an overall control operation of the operation procedure described in the above embodiments.

The transmission modules 40 and 50 may perform predetermined coding and modulation on the data to be transmitted to the outside and transmit the data to the antenna 10 after being scheduled from the processors 20 and 30.

The receiving modules 60 and 70 decode and demodulate the radio signals received from the outside through the antennas 5 and 10 to restore them in the form of original data and transmit them to the processors 20 and 30 .

The memories 80 and 90 may store programs for processing and controlling the processors 20 and 30, and may perform functions for temporary storage of input / output data. The memories 80 and 90 may be a flash memory type, a hard disk type, a multimedia card micro type, a card type memory (for example, SD or XD memory A static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM) Magnetic disk, magnetic disk, magnetic disk, or optical disk.

The base station includes a controller function for performing the above-described embodiments of the present invention, orthogonal frequency division multiple access (OFDMA) packet scheduling, time division duplex (TDD) packet scheduling and channel multiplexing , MAC frame variable control function according to service characteristics and propagation environment, high speed traffic real time control function, handover function, authentication and encryption function, packet modulation / demodulation function for data transmission, high speed packet channel coding function and real time modem control function Etc. may be performed through at least one of the modules described above, or may include additional means, modules, or portions for performing such functions.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention. In addition, claims that do not have an explicit citation in the claims may be combined to form an embodiment or be included in a new claim by amendment after the filing.

Claims (18)

[Claim 1 has been abandoned due to the registration fee.] A method for performing an existence check procedure of a terminal during a handover of a broadband wireless access system,
Receiving a first signal for a presence confirmation request from a serving base station; And
And transmitting a second signal for an existence acknowledgment to the serving base station,
Wherein the first signal is received after a disconnect time for instructing an interruption of resource allocation for uplink / downlink communication with the serving base station of the serving base station,
The first signal
An unsolicited AAI_RNG-RSP message in which a bit for requesting ranging is set to the UE,
Wherein the second signal is a periodic ranging code. [Claim 2 is abandoned upon payment of the registration fee.] The method according to claim 1,
The serving base station,
And transmits the first signal to the MS if the target BS does not notify the serving BS of the end of the handover until the connection release time elapses. delete delete [Claim 5 is abandoned upon payment of registration fee.] The method according to claim 1,
Receiving a ranging acknowledgment (AAI_RNG-ACK) message indicating a ranging success state from the serving base station; And
And transmitting a ranging acknowledgment (AAI_RNG-CFM) message including an identifier of the mobile station to the serving base station. delete [7] has been abandoned due to the registration fee. A method for performing a presence verification procedure of a terminal during a handover of a broadband wireless access system,
Transmitting a first signal for requesting existence confirmation to the terminal; And
Receiving a second signal for an existence confirmation response from the terminal,
The first signal is transmitted to the MS after a disconnect time for instructing a termination of resource allocation for uplink / downlink communication with the serving base station of the serving base station has elapsed ,
The first signal
An unsolicited AAI_RNG-RSP message in which a bit for requesting ranging is set to the UE,
Wherein the second signal is a periodic ranging code. [8] has been abandoned due to the registration fee. 8. The method of claim 7,
Wherein the transmitting the first signal comprises:
And when the handover completion notification is not received from the target base station until the connection release time elapses. delete delete [Claim 11 is abandoned upon payment of the registration fee.] 8. The method of claim 7,
If the code is successfully received,
Transmitting a ranging acknowledgment (AAI_RNG-ACK) message indicating a ranging success state to the UE; And
Further comprising the step of receiving a ranging acknowledgment (AAI_RNG-CFM) message including the identifier of the terminal from the terminal. delete A mobile terminal operating in a broadband wireless access system,
A processor; And
And a wireless communication (RF) module for transmitting and receiving a wireless signal to and from the outside under the control of the processor,
The processor comprising:
When a first signal for requesting the presence confirmation is received from the serving base station, controls to transmit a second signal for an existence confirmation response to the serving base station,
Wherein the first signal is received after a disconnect time for instructing an interruption of resource allocation for uplink / downlink communication with the serving base station of the serving base station,
The first signal
An unsolicited AAI_RNG-RSP message in which a bit for requesting ranging is set to the UE,
And the second signal is a periodic ranging code. 14. The method of claim 13,
The serving base station,
And transmits the first signal to the mobile terminal when the target base station does not notify the serving base station of the end of the handover until the connection release time elapses. delete delete 14. The method of claim 13,
The processor comprising:
(AAI_RNG-ACK) message indicating a ranging success state is received from the serving base station, a ranging acknowledgment (AAI_RNG-CFM) message including an identifier of the mobile terminal is transmitted to the serving base station Lt; / RTI > delete

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