KR20110093675A - Apparatus and method for updating a control information of a target base station during handover operation in a broadband wireless communication system - Google Patents

Abstract

PURPOSE: A method and apparatus for updating control information of a target base station in handover are provided to efficiently obtain system information of a target base station without system information of the target base station. CONSTITUTION: A control unit(812) controls a wireless communication unit in order to transmit a handover request message to a serving base station. The control unit controls a handover command message including delta control information from the serving base station. The control unit updates control information of the garget base station.

Description

A method and apparatus for updating control information of a target base station during a handover in a broadband wireless communication system.

The present invention relates to a broadband wireless access system, and more particularly, to a method for efficiently obtaining system information (or control information) of a target base station during handover and an apparatus for performing the same.

Handover (HO) refers to a terminal moving 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 an IEEE 802.16e network, a serving base station (SBS) transmits neighboring base station information to a neighbor advertisement (information topology) to inform a mobile station (MS) of the basic network configuration information (topology). It can be broadcasted through a MOB_NBR-ADV) message.

The MOB_NBR-ADV message includes system information about the serving base station and neighboring base stations, for example, preamble index, frequency, HO optimization possibility, and downlink channel descriptor (DCD). Channel Descriptor / Uplink Channel Descriptor (UCD) information.

The DCD / UCD information includes information that the terminal needs to know in order to perform information communication through downlink and uplink in the terminal. For example, there is information such as handover trigger (HO trigger) information, a medium access control version (MAC) of the base station, and media independent handover capability (MIH).

In more detail, the DCD includes downlink burst profiles DL_Burst_Profiles, which are information for the UE to decode a message transmitted by the base station. Since the messages broadcast by the base station can be received by all terminals within the coverage of the base station, since the most robust RS_Burst_Profile configuration value is applied, the configuration value is rarely changed. However, since a message transmitted in unicast to each terminal is sent with an appropriate setting value according to the channel state of the terminal, the DL_Burst_Profile setting value may be different for each terminal during unicast. The UCD contains UL_Burst_Profiles, which are information for the UE to send messages to the base station, and may be configured differently according to the channel environment state.

As described above, system information in a general IEEE 802.16e system is transmitted through the uplink UCD and the downlink DCD, and may have a transmission period of up to 10 seconds. In this case, when the system information is updated, the base station schedules such that all the terminals recognize at least once about the updated system information so that there is no mismatch in the system information of the corresponding base station held by the terminal. To this end, in the case of UCD, a period of a UCD transition interval start and a UCD transition interval expired is defined, and the base station transmits a new UCD in the period.

A method of performing handover in an IEEE 802.16e network by a terminal acquiring system information of a neighbor base station through the above-described method will be described in more detail.

The handover procedure in the general IEEE 802.16e network is roughly three procedures, and may be composed of handover initialization and preparation (HO initiation & preparation), handover execution (HO execution) and handover completion (HO completion).

An example of a basic handover procedure that can be configured as described above will be described with reference to FIG. 1.

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

Referring to FIG. 1, firstly, a terminal MS may be connected to a serving base station SBS to perform data exchange (S101).

The serving base station may periodically broadcast information about neighboring base stations located therein to the terminal through a MOB_NBR-ADV message (S102).

The UE may start scanning for candidate HO BSs using a handover trigger condition while communicating with the serving base station. When the terminal has exceeded a handover condition, for example, a predetermined hysteresis margin value, the terminal may request a serving base station to perform a handover procedure by transmitting a handover request (MOB_MSHO-REQ) message (S103).

The serving base station may inform the candidate base station (candidate HO BS) included in the MOB_MSHO-REQ message through the HO-REQ message of the handover request of the terminal (S104).

Candidate base stations BS may take preliminary measures for the UE requesting the handover and transmit information related to the handover to the serving base station through the HO-RSP message (S105).

The serving base station may transmit information related to handover obtained from candidate base stations through a HO-RSP message to the terminal through a handover response (MOB_BSHO-RSP) message. The MOB_BSHO-RSP message includes information for performing handover such as an action time for handover, a handover identifier (HO-ID), and a dedicated handover CDMA ranging code. It may be included (S106).

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

Upon receiving the CDMA code, the target base station may transmit success of ranging and physical correction values through a ranging response (RNG-RSP) message to the terminal (S108).

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

The target base station receiving the ranging request message of the terminal may provide the terminal with system 2 information that can be used in the corresponding base station such as a connection identifier (CID) through the ranging response message (S110).

When the target base station successfully completes authentication of the terminal and sends all the updated information, the target base station may inform the serving base station of the terminal whether the handover is successful through the handover completion message (HO-CMPT) (S111).

Thereafter, the terminal may perform information exchange with the target base station which performed the handover (S112).

In the IEEE 802.16m system, there is a change in the name and / or function of each MAC management message in the above handover procedure.

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, there is a change in the name and / or the function of each MAC management message as described below.

MOB_NBR-ADV-> AAI_NBR-ADV: This message includes system information delivered in S-SFH format, not DCD / UCD format.

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- [0031] REQ

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

In addition, in the IEEE 802.16m system, the system information of the base station is transmitted through the superframe header.

Hereinafter, a frame structure and a superframe header of the IEEE 802.16m system will be described.

2 illustrates an example of a physical frame structure used in a wireless wide area network (Wireless MAN) mobile communication system based on the IEEE 802.16 system.

Referring to FIG. 2, a superframe has a length of 20 ms and consists of four frames.

One frame is composed of eight subframes again, and the eight subframes include a downlink subframe region and an uplink subframe including a predetermined number of subframes according to the downlink and uplink ratio (DL / UL ratio). It can be divided into areas. When the uplink / downlink (UL / DL) ratio is 5: 3 as shown in FIG. 2, five of eight subframes are allocated to downlink subframes SF0 to SF4, and the remaining three are uplink subframes ( SF5 through SF7).

An idle time, that is, a TTG (Transmit / Receive Transition Gap), exists between a downlink subframe region and an uplink subframe, in which a data symbol (that is, a valid symbol) including data is not allocated. In addition, an idle time, that is, a RTG (Receive / transmit Transition Gap) may exist after the downlink subframe region. In addition, one subframe consists of six OFDM symbols.

By using the above-described frame structure, the base station and the terminal may perform data exchange. For example, the terminal may receive data from the base station through a downlink subframe and transmit data to the base station through an uplink subframe. In addition, the base station may transmit data to the terminal through the downlink subframe, and may receive data from the terminal through the uplink subframe.

Meanwhile, in the above-described frame structure, the superframe header may be transmitted to the terminal through the first subframe of the superframe. The superframe header may include resource allocation information or system information in units of frames or subframes included in the superframe header.

In more detail, in the IEEE 802.16m system, the superframe header (hereinafter referred to as "SFH") may include essential system parameters and system configuration information.

Superframe headers are referred to as Primary Superframe Headers (P-SFH) and Secondary Superframe Headers (S-SFH). ) Can be separated. The P-SFH transmitted in every superframe includes the lowest 4 bits (4bit-LSB) information of the superframe number and the information related to the S-SFH transmitted in the corresponding superframe. S-SFH delivers actual system information. System information is divided into subpackets according to its characteristics, and each of them is referred to as S-SFH SPn (n = 1, 2, 3). Each S-SFH SP IE is transmitted in a different transmission period (TSP1 <TSP2 <TSP3). Here, the system information is setting values according to a communication environment, such as ranging and power control, required by the terminal for downlink / uplink (DL / UL) transmission.

Information related to the S-SFH included in the P-SFH includes an S-SFH change count indicating the S-SFH version currently transmitted, and an S-SFH indicating whether the S-SFH is transmitted in the corresponding superframe. S-SFH Scheduling information bit-map, S-SFH size indicating the number of logical resource units (LRUs) allocated for S-SFH transmission, S-SFH repetition indicating the transmission format of S-SFH S-SFH number of repetitions, S-SFH subpacket change bitmap indicating which S-SFH SP has been changed, and the like. At this time, the size of the S-SFH Scheduling information bit-map and the S-SFH SP change bitmap field is equal to the total number of SPs of the SSFH included in the corresponding superframe.

When the terminal intends to perform a handover to a specific target base station, a difference may occur in the handover delay time depending on whether the superframe header (SFH) information of the target base station held by the terminal is up to date. If the handover is performed in a state in which the SFH of the target base station is received through the neighbor advertisement (AAI_NBR-ADV) message, the target base station may immediately perform network re-entry to complete the handover.

However, the terminal may not receive a neighbor advertisement (AAI_NBR-ADV) message including the SFH of the target base station, or may receive an AAI_NBR-ADV message in which the SFH change of the target base station is not yet reflected. In this state, the terminal performing the handover performs network reentry after receiving all SFHs from the target base station. That is, the handover delay time is increased by the time that the terminal receives all of the S-SFH SP1 / 2/3, and additionally ranging or seamless handover using a dedicated ranging code. It is not possible to perform a handover optimization (HO optimized) procedure.

In other words, when the terminal does not receive even a part of the target base station SFH or directly receives the SFH from the target base station while performing the handover in a state that is not up-to-date information, the handover delay time can be greatly increased, and thus the standardization standard The minimum handover delay time specified may not be satisfied.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the general technology, and an object of the present invention is to provide an efficient method for performing handover and an apparatus for performing the same.

Another object of the present invention is to provide a method and an apparatus for the terminal which does not have the latest system information of the target base station to efficiently obtain the system information of the target base station during the handover process.

Another object of the present invention is to provide a method and apparatus for a time point when the latest system information received by the terminal is applied when the latest system information of the target base station is received.

Technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

The present invention provides a method of operating a terminal for updating control information (SFH) of a target base station in a handover process, the base station serving a neighbor advertisement message including the control information of at least one neighboring base station including the target base station; Receiving from; Transmitting a handover request message including first change count information indicating a change count of the received neighbor advertisement message to the serving base station; Receiving a handover command message from the serving base station, the handover command message including delta control information different from the control information included in the neighbor advertisement message; And updating the control information of the target base station by using the received difference control information.

The handover command message may further include second change count information indicating a neighbor advertisement message version held by the serving base station, and the difference control information includes the first change count information and the second change count information. Is different from the handover command message.

The handover command message may further include indication of application of the difference control information.

The indication of application of the difference control information is information indicating whether to apply the difference control information received from the serving base station to the target base station when performing a network reentry process.

The handover command message may further include information on when to apply the difference control information.

The difference control information application timing information indicates a time offset from a frame number in which the handover command message is transmitted when the difference control information is applied when the terminal performs a network reentry process to the target base station. It is done.

In addition, the control information is characterized in that the superframe header (superframe header).

In addition, the present invention comprises the steps of transmitting a ranging request message to the target base station using the updated control information; And receiving a ranging response message from the target base station.

The present invention also provides a handover command message including first change count information indicating a version of a neighbor advertisement message in a method of operating a terminal for updating control information (SFH) of a target base station during a handover process. Receiving from the serving base station; Confirming whether previously received first change count information and second change count information held by the terminal match; And transmitting a handover indication message including an event code indicating the cancellation of the handover command requested by the serving base station to the serving base station if there is a mismatch.

The method may further include receiving a first message from the serving base station, the first message including the latest version control information of the target base station; And updating the control information currently held by the terminal with the latest version control information.

The handover indication message may further include a control information mismatch indicator indicating that the control information included in the handover command message is not the latest control information for the target base station.

In addition, the first message may be a neighbor advertisement message (NBR-ADV message).

The present invention also provides a terminal for updating the control information (SFH) of the target base station in the handover process, the memory; A wireless communication unit for transmitting and receiving wireless signals with the outside; And controlling the wireless communication unit to receive a neighbor advertisement message including control information of at least one neighbor base station including the target base station from a serving base station, the first change count information indicating a neighbor advertisement message version. And control the wireless communication unit to transmit an over request message to the serving base station, and to receive a handover command message from the serving base station, the handover command message including delta control information different from the control information included in the neighbor advertisement message. And a control unit controlling a communication unit and controlling to update the control information of the target base station using the received difference control information.

The handover command message may further include second change count information indicating a version of a neighbor advertisement message held by the serving base station, and the controller may further include the first change count information and the second change count information. In a different case, the handover command message is controlled to include the difference control information.

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

First, the terminal may perform handover more efficiently.

Second, the terminal that does not have the latest system information of the target base station through the embodiments of the present invention can efficiently receive the latest system information during the handover, the handover delay time can be reduced.

Third, when the latest system information of the target base station is received through the embodiments of the present invention, it is possible to know when to apply the latest system information received by the terminal to perform a network re-entry process without delay to the target base station. Can be done.

1 shows an example of a handover procedure that may be performed in an IEEE 802.16e system.
2 illustrates an example of a physical frame structure used in a wireless wide area network (Wireless MAN) mobile communication system based on the IEEE 802.16 system.
3 illustrates an example of a procedure for updating system information of a target base station in a handover process according to an embodiment of the present invention.
4 illustrates an example of a system information update procedure of a target base station through EBB handover according to an embodiment of the present invention.
5 illustrates an example of a procedure of updating system information of a target base station through a neighbor advertisement message in a handover process according to an embodiment of the present invention.
6 illustrates an example of a procedure for updating system information of a target base station in a handover process according to another embodiment of the present invention.
7 illustrates another example of a procedure of updating system information of a target base station in a handover process according to another embodiment of the present invention.
8 is a block diagram illustrating an example of a terminal and a base station as another embodiment of the present invention.

In order to solve the above technical problem, the present invention discloses a method for more efficiently receiving system information of a target base station in a 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 feature may be considered to be optional unless otherwise 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 components 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.

In the present specification, embodiments of the present invention have been described based on data transmission / reception relations between a base station and a terminal. Here, the base station has a meaning as a terminal node of the network that directly communicates with the terminal. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, it is obvious that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. A 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point (AP), and the like. In addition, the term 'terminal' may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), or a subscriber station (SS).

Embodiments of the invention may be implemented through 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 the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802 system, 3GPP system, 3GPP LTE system and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

As described above, the terminal needs to acquire system information of the target base station in performing the handover. Examples of system information of the target base station include uplink / downlink resource configuration, uplink frequency reuse rate, power control, ranging channel information, advanced map (A-MAP) information, feedback (HARQ) information, and backoff. Information and the like.

The above system information may be obtained to the terminal through a superframe header (SFH) of the target base station or a neighbor advertisement (AAI_NBRADV) message broadcasted by the serving base station.

However, there may occur a case in which the terminal owns information of an older version of SFH than the current SFH of the neighbor base stations. This is a problem that may occur because the transmission period of the neighbor advertisement message is relatively longer than the transmission period of the superframe header. This state may be referred to as a situation in which a specific base station and a superframe header mismatch (SFH mismatch).

The situation where the SFH mismatch may occur may include 1) the terminal not receiving the latest neighbor advertisement (AAI_NBR-ADV) message reflecting the SFH update, or 2) the terminal before the AAI_NBR-ADV message reflecting the SFH update is broadcasted. The case where handover is performed to this target base station is mentioned.

When such an SFH mismatch occurs, the target base station SFH information update method of the terminal proposed by the present invention can be considered into two cases.

The first case is the case where the terminal initiates a handover, and the second case is the case where the base station initiates the handover.

First, the case where the terminal initiates the handover (MS initiated HO) will be described.

According to an embodiment of the present invention, there is provided a method in which a terminal in an SFH mismatch state can efficiently receive the latest system information of a target base station in a handover procedure initiated by the terminal.

When the terminal initiates the handover, the method for updating the SFH inconsistent with the target base station according to an embodiment of the present invention can be classified into three types as follows.

1. A method of transmitting inconsistent SFH delta information to a UE through a handover command (AAI_HO-CMD) message in a handover procedure

2. A method of coordinating an serving before break (EBB) handover procedure for the SFB to directly update the target base station during the handover procedure by the serving ABS (S-ABS).

3. The serving base station (S-ABS) rejects the handover procedure initiated by the terminal.

First Embodiment

1. First, explain the first method.

In one aspect of the present embodiment, when the UE initiates handover by sending a handover request (AAI_HO-REQ) message, the current neighbor announcement change count (AAI_NBR-) owned by the terminal in the corresponding message (AAI_HO-REQ). It is suggested to include ADV change count information.

Here, the AAI_NBR-ADV change count means a version of a neighbor advertisement (AAI_NBR-ADV) message of the current serving base station (S-ABS). That is, an increase of one change count means that information included in the AAI_NBR-ADV message of the S-ABS has been updated.

In this case, it is preferable to add a field shown in Table 1 below to the AAI_HO-REQ message.

Table 1 shows an example of a field type added to a handover request (AAI_HO-REQ) message according to an embodiment of the present invention.

Name Value Usage Change count AAI _ NBR - ADV Change Count last received from  the serving ABS

A handover procedure in the case where the above-described change count information is applied will be described with reference to FIG. 3.

3 illustrates an example of a procedure for updating system information in a handover process according to an embodiment of the present invention.

Referring to FIG. 3, the terminal may normally exchange data with a serving base station and receive a neighbor advertisement (AAI_NBR-ADV) message including system information of neighboring base stations from the serving base station (S301).

Here, it is assumed that the change count value of the neighbor advertisement message is 2. The serving base station then updates the system information so that the change count value of the neighbor advertisement message is changed to three.

When the predetermined handover condition is satisfied, the terminal transmits a handover request (AAI_HO-REQ) message to the serving base station by setting the neighbor advertisement change count information to 2 to start the handover (S302).

Upon receiving the handover request message of the terminal, the base station may recognize that a mismatch (SFH mismatch) occurs in the neighbor advertisement message information held by the terminal, and accordingly, the change count value is 3 in the handover command (AAI_HO-CMD) message. In addition, the neighbor advertisement message includes the SFH difference (SFH delta) according to the version change and transmits it to the terminal (S303).

Accordingly, the terminal may transmit the ranging request (AAI_RNG-REQ) message to the target base station after obtaining the latest system information of the target base station using the SFH difference value included in the handover command message (S304).

The target base station may transmit a ranging response (AAI_RNG-RSP) message in response to the ranging request message transmitted by the terminal (S305).

Thereafter, the terminal and the target base station successfully complete the handover procedure and may normally perform data exchange (S306).

Second Embodiment

2. Next, explain the second method.

In another aspect of the present embodiment, the terminal includes the neighbor advertisement change count information in the handover request message so that the serving base station determines the SFH mismatch state of the terminal. However, it is proposed to allow the UE to receive mismatched SFH information directly from the target base station through an EBB (Entry Before Break) handover rather than a handover command message.

Here, EBB handover refers to the handover reentry mode 1 (HO_Reentry_Mode 1), which is a method of performing data exchange by maintaining a connection with a serving base station until the terminal enters the target base station during the handover process. time is reduced.

To this end, the serving base station (S-ABS) may adjust the EBB handover procedure (coordination) so that the terminal can directly receive 2 mismatched SFH information from the target base station. In more detail, the terminal updates the SFH in the target base station (T-ABS) in the interval (HO_Reentry_Interleaving_Interval) does not communicate with the serving base station according to the scheduling of the serving base station, and receives the service (service) from the S-ABS continuously. The serving base station transmits at least one of SP scheduling periodicity information of the SFH broadcast from the target base station and information indicating an SFH mismatch state in order to support the terminal to receive only the necessary SFH message (AAI_HO-CMD). It can be included in the transmission to the terminal. Based on the information, the UE may perform an EBB handover procedure.

In this case, it is preferable to add a field as shown in Table 2 below to the handover command (AAI_HO-CMD) message.

Table 2 shows an example of a field form included in a handover command (AAI_HO-CMD) message according to an embodiment of the present invention.

Name Value Usage Mode 0b00: HO command;
0b01: Zone switch command from MZone to LZone;
0b10: AMS HO request rejected (ABS in list unavailable). In this case, AAI_HO-CMD message shall not include any target ABS.
0 b11 : HO reject Reject Reason 0 b00 T- ABS is full
0 b01 : SFH mismatch is detected with  T- ABS In case of Mode is set to  0 b11 , this  parameter indicates the  reason of HO rejection . HO_Reentry_Mode 1: the AMS maintains communication with Serving ABS while performing network reentry with the Target ABS (Mode = 0b00); or the AMS maintains communication with MZone while performing network reentry with LZone in the same frame or on another carrier (Mode = 0b01).
0: the AMS disconnects from the Serving ABS before performing network reentry with the Target ABS (Mode = 0b00); or the AMS disconnects from the MZone before performing network reentry with the LZone (Mode = 0b01). Should be included when Mode = 0b00.
Shall be included when Mode = 0b01. HO_Reentry_Interleaving_Interval If HO Reentry Interleaving Interval> 0, the AMS performs network reentry to the target ABS within the HO Reentry Interleaving Interval and continues data transmission with the Serving ABS in the remaining time.
If HO Reentry Interleaving Interval = 0, the AMS performs multi-carrier EBB (Established Before Break) HO procedure per 16.2.8.2.9.2.2 Shall be included when HO Reentry Mode is set to 1 HO Reentry Iteration The requested number of iterating HO Reentry Intervals by an AMS. Shall be included when HO Reentry Interleaving Interval> 0 SP scheduling  periodicity information 4 bit Indicates the scheduling  periodicity of SP1 , SP2 and SP3

Referring to Table 2, in the AAI_HO-CMD message, the Mode field is set to a specific value (here, 0b11) to inform the rejection of the handover request initiated by the terminal. In this case, the reject reason indicating the rejection reason (reject reason) The field may be additionally included.

The field indicating the reason for rejection may be used to indicate the SFH mismatch state to the UE. More specifically, when the rejection reason field is set to a specific value (here, 0b01), it may indicate that the UE is in an SFH mismatch state. If the rejection reason field is set to a value different from the SFH mismatch state, it may indicate to the terminal that the target base station can no longer accommodate the terminal.

In addition, the AAI_HO-CMD message may include the SP scheduling period information to inform the UE of the transmission period for each S-SFH SP.

The above-described SFH update procedure through the EBB will be described with reference to FIG. 4.

4 illustrates an example of a system information acquisition procedure of a target base station through EBB handover according to an embodiment of the present invention.

Referring to FIG. 4, first, a UE normally performs data exchange with a serving base station and may receive a neighbor advertisement (AAI_NBR-ADV) message including system information of neighboring base stations from the serving base station (S401).

Here, it is assumed that the change count value of the neighbor advertisement message is 2. Thereafter, the serving base station updates the system information (ie, SFH) of the neighbor base station so that the change count value of the neighbor advertisement message is changed to three.

When the predetermined handover condition is satisfied, the terminal transmits a handover request (AAI_HO-REQ) message to the serving base station by setting the neighbor advertisement change count information to 2 to start the handover (S402).

The serving base station receiving the handover request message of the terminal may know that a mismatch (SFH mismatch) occurs in the neighbor advertisement message information held by the terminal, and may adjust the EBB handover to the terminal accordingly. To this end, the serving base station sends a handover command (AAI_HO-) to at least one of change count information set to 3, information indicating whether or not the SFH mismatch, and EBB handover adjustment information that informs the terminal that the serving base station will adjust the EBB handover. CMD) may be included in the message and transmitted to the terminal (S403).

The EBB handover coordination information may include information about a section that does not communicate with the serving base station according to scheduling of the serving base station, that is, information about a handover reentry interleaving interval (HO_Reentry_Interleaving_Interval). In addition, serving

The base station may further include SFH scheduling information indicating when the SFH information inconsistent with the handover command message is transmitted from the target base station.

Upon receiving the handover command message, the UE can know the SFH mismatch state and can directly receive inconsistent SFH information (SFH delta 1) from the target base station in the handover reentry interleaving period by using the information included in the handover command message. It may be (S404).

If the handover command message includes the SFH scheduling information of the target base station, the terminal may further receive the SFH by referring to this in step S404.

When the terminal is not in the handover reentry interleaving interval, the terminal may perform data exchange with the serving base station according to the scheduling of the base station (S405).

If there is mismatched SFH information even after receiving the SFH performed in step S404, the UE may additionally receive SFH (SFH delta 2) of the target base station in the next handover reentry interleaving interval, and serve according to the scheduling of the serving base station after the corresponding interval. Data exchange with the base station may be performed (S406 and S407).

Thereafter, the terminal may transmit the ranging request message to the target base station according to obtaining the latest system information of the target base station through SFH reception (S408).

The target base station transmits the ranging response message to the terminal in response to the ranging request message transmitted by the terminal (S409).

Thereafter, the terminal and the base station can successfully complete the handover procedure and perform data exchange normally (S410).

Third Embodiment

3. Next, explain the third method.

In another aspect of the present embodiment, the terminal includes neighbor advertisement change count information in the handover request message so that the serving base station determines the SFH mismatch state of the terminal. However, when the terminal is in an SFH mismatch state, the serving base station rejects the handover request of the terminal and suggests that the terminal receives the neighboring advertisement (AAI_NBR-ADV) message that is broadcasted next from the serving base station with the mismatched SFH information. do. This will be described with reference to FIG. 5.

5 illustrates an example of a procedure of updating system information of a target base station through a neighbor advertisement message in a handover process according to an embodiment of the present invention.

Referring to FIG. 5, the terminal may normally exchange data with a serving base station and receive a neighbor advertisement (AAI_NBR-ADV) message including system information of neighboring base stations from the serving base station (S501).

Here, it is assumed that the change count value of the neighbor advertisement message is 2. Thereafter, the serving base station updates the system information (ie, SFH) of the neighbor base station so that the change count value of the neighbor advertisement message is changed to three.

When the predetermined handover condition is satisfied, the terminal transmits a handover request (AAI_HO-REQ) message to the serving base station by setting the neighbor advertisement change count information to 2 to start the handover (S502).

Upon receiving the handover request message of the terminal, the serving base station may know that a mismatch (SFH mismatch) occurs in neighboring advertisement message information held by the terminal, and thus the terminal receives the AAI_NBR-ADV message transmitted next. You can reject the requested handover. To this end, the serving base station includes at least one of change count information set to 3 and mode information set to a value indicating a handover rejection (for example, 0b10) in the handover command (AAI_HO-CMD) message. It may be transmitted to the terminal (S503).

Upon receiving the handover command message from the serving base station, the UE may know that the handover initiated by the UE is rejected as an SFH mismatch state. Accordingly, the terminal may perform data exchange with the serving base station (S504).

Thereafter, the UE may receive the latest AAI_NBR-ADV message (change count value = 3) from the serving base station (S505).

Upon receiving the latest AAI_NBR-ADV message, the UE may acquire the latest SFH (ie, system information) of the target base station, and in order to request a handover again, a handover request (AAI_HO-) in which a change count value is set to 3 to the serving base station. REQ) message can be sent.

The serving base station receiving the handover request message from the terminal may know that there is no SFH mismatch in the terminal, and accordingly transmits a handover command message to the terminal (S507).

Since the following procedure is a general handover procedure, duplicate descriptions will be omitted for simplicity of the specification.

Hereinafter, another embodiment of the present invention will be described when the base station initiates handover (BS initiated HO).

According to another embodiment of the present invention, a method in which a terminal in an SFH mismatch state can efficiently receive the latest system information of a target base station in a handover procedure initiated by a serving base station.

When the serving base station initiates the handover, a method of updating the SFH that is inconsistent with the target base station according to an embodiment of the present invention may be classified into two types as follows.

1. Method for UE to perform handover after updating all SFH in serving base station

2. Method of updating and receiving the SFH directly from the target base station by requesting EBB handover after the terminal rejects the handover request of the serving base station

Fourth embodiment

1. First, explain the first method.

In one aspect of the present embodiment, when the base station transmits a handover command (AAI_HO-CMD) message to the unsolicited request to initiate the handover, if the UE recognizes the SFH mismatch, it is to reject the handover through the handover indication message. Suggest.

This will be described with reference to FIG. 6.

6 illustrates an example of a procedure for updating system information of a target base station in a handover process according to another embodiment of the present invention.

Referring to FIG. 6, the terminal may normally exchange data with a serving base station and receive a neighbor advertisement (AAI_NBR-ADV) message including system information (SFH information) of neighboring base stations from the serving base station (S601).

Here, it is assumed that the change count value of the neighbor advertisement message is 2. Thereafter, the serving base station updates the system information (ie, SFH) of the neighbor base station so that the change count value of the neighbor advertisement message is changed to three.

The serving base station transmits a handover command (AAI_HO-CMD) message to the terminal by setting the neighbor advertisement change count information to 3 to start the handover when a predetermined handover condition is satisfied (S602).

In this case, the handover command message may further include a superframe header counter of the neighbor base station.

Upon receiving the handover command message, the terminal may know that the neighbor advertisement change count of the serving base station does not match its neighbor advertisement count and thus is in an SFH mismatch state. Accordingly, the UE may transmit an event code of the handover indication (AAI_HO-IND) message to a serving base station by setting the event code to a value indicating handover cancellation or rejection (S603).

In this case, when the terminal rejects the handover, information indicating the reason for the rejection may be additionally included in the handover instruction message. An example of a handover indication (AAI_HO-IND) message type including this information will be described with reference to Table 3.

Name Value Usage HO Event Code 0b000: Target ABS selection in case of multiple candidate T-ABSs.
0b001: All target ABSs in AAI_HO-CMD are unreachable. In this case, the AMS shall include a new target ABS that was not included in AAI_HO-CMD.
0b010: AMS unable to stay connected to serving ABS until expiration of disconnect time
0b011: HO cancel.
0 b100 : HO reject This is used to distinguish AAI_HO-IND among different scenarios Reject Reason 0 b00 : SFH mismatch is detected with  T- ABS In case of HO Event Code is set to  0b100, this parameter  indicates the reason of HO rejection .

Referring to Table 3, in the event code field of the handover indication message, a value indicating HO reject (for example, 0b100) is newly established to perform the handover procedure initiated by the base station. You can refuse.

In addition, when the event code value is set to a value indicating handover rejection, the handover instruction message may further include a rejection reason field indicating a reject reason. If the rejection reason field is set to a specific value (for example, 0b00), this may indicate that the corresponding UE is in an SFH mismatch state.

Meanwhile, the change count information may be further included in the handover indication message. In this case, a problem that may occur when seamless handover is performed may be solved. That is, when seamless handover is performed, if it is determined that the terminal has old target base station system information, the serving base station cancels the unnecessary stop.

It can prevent the occurrence of time.

Referring back to FIG. 6, the terminal may receive the latest neighbor advertisement message having a change count set to 3 from the serving base station and update the SFH information of the neighbor base station.

Thereafter, if a predetermined handover condition is satisfied while performing data exchange with the serving base station, the terminal may transmit a handover request (AAI_HO-REQ) message with a change count set to 3 to the serving base station (S605 and S606).

Upon receiving the handover request message of the terminal, the base station may know that there is no SFH mismatch in the neighbor advertisement information held by the terminal, and accordingly, may transmit a handover command message to the terminal (S607).

Since the following procedure is similar to the general handover procedure, duplicate description will be omitted.

The handover indication (AAI_HO-IND) may include information indicating the mismatch when the neighbor advertisement change count value transmitted from the serving base station and the neighbor advertisement change count value held by the terminal do not match.

Table 4 below shows an embodiment of a handover indication (AAI_HO-IND) message including information indicating a neighbor advertisement change count value mismatch.

Name Value Usage HO Event Code 0b000: Target ABS selection in case of multiple candidate T-ABSs.
0b001: All target ABSs in AAI_HO-CMD are unreachable. In this case, the AMS shall include a new target ABS that was not included in AAI_HO-CMD.
0b010: AMS unable to stay connected to serving ABS until expiration of disconnect time
0b011: HO cancel.
0 b100 : AAI _ NBR - ADV change count mismatch indication . This is used to distinguish  AAI_HO-IND among different scenarios AAI _ NBR - ADV Change count AAI _ NBR - ADV change count last  received from the serving ABS This is only included when  a mismatch of SFH has occurred .

Fifth Embodiment

2. Next, the second method is described.

In another aspect of the present embodiment, if the UE recognizes the SFH mismatch when the base station transmits a handover command (AAI_HO-CMD) message to the unsolicited request, the UE rejects the handover through the handover indication message. do. However, unlike the above aspect, it is proposed that the UE does not acquire mismatched SFH information through the neighbor advertisement message of the serving base station, but requests the EBB handover procedure from the target base station.

This will be described with reference to FIG. 7.

7 illustrates another example of a procedure of updating system information of a target base station in a handover process according to another embodiment of the present invention.

Referring to FIG. 7, the terminal may normally exchange data with a serving base station and receive a neighbor advertisement (AAI_NBR-ADV) message including system information (SFH information) of neighboring base stations from the serving base station (S701).

Here, it is assumed that the change count value of the neighbor advertisement message is 2. Thereafter, the serving base station updates the system information (ie, SFH) of the neighbor base station so that the change count value of the neighbor advertisement message is changed to three.

The serving base station sets the neighbor advertisement change count information to 3 and transmits a handover command (AAI_HO-CMD) message to the terminal to start the handover when the predetermined handover condition is satisfied (S702).

In this case, the handover command message may further include a superframe header counter of the neighbor base station.

Upon receiving the handover command message, the terminal may know that the neighbor advertisement change count of the serving base station does not match its neighbor advertisement count and thus is in an SFH mismatch state. Accordingly, the UE sets the event code of the handover indication (AAI_HO-IND) message to a value for requesting EBB handover due to an SFH mismatch (for example, any one of 0b101 to 0b111) to the serving base station. It may transmit (S703).

The serving base station receiving the handover indication message of the terminal may know that a mismatch (SFH mismatch) occurs in the neighbor advertisement message information held by the terminal, and may adjust the EBB handover to the terminal accordingly. To this end, the serving base station may include the EBB handover adjustment information informing the terminal that it will coordinate the EBB handover in the handover command (AAI_HO-CMD) message and transmit the same to the terminal (S704).

The EBB handover coordination information may include information about a section that does not communicate with the serving base station according to scheduling of the serving base station, that is, information about a handover reentry interleaving interval (HO_Reentry_Interleaving_Interval). In addition, serving

The base station may further include SFH scheduling information indicating when the SFH information inconsistent with the handover command message is transmitted from the target base station.

The terminal may directly receive inconsistent SFH information (SFH delta 1) from the target base station in the handover reentry interleaving period by using the information included in the handover command message (S705).

If the handover command message includes the SFH scheduling information of the target base station, the terminal may further receive the SFH by referring to this in step S705.

When the terminal is not in the handover reentry interleaving interval, the terminal may perform data exchange with the serving base station according to the scheduling of the base station (S706).

If there is mismatched SFH information even after receiving the SFH performed in step S705, the UE may additionally receive SFH (SFH delta 2) of the target base station in the next handover reentry interleaving interval, and serve according to the scheduling of the serving base station after the corresponding interval. Data exchange with the base station may be performed (S707 and S708).

Thereafter, the terminal may transmit the ranging request message to the target base station according to obtaining latest system information of the target base station through SFH reception (S709).

The target base station transmits the ranging response message to the terminal in response to the ranging request message transmitted by the terminal (S710).

Thereafter, the terminal and the base station can successfully complete the handover procedure and perform data exchange normally (S711).

Meanwhile, in the above-described embodiments, although the UE acquires the latest information about S-SFH SP 1 and S-SFH SP 2 of the target base station during the handover process, there may be a case where SFH mismatch occurs only in S-SFH SP3. have. S-SFH SP3 is not related to the ranging procedure performed in the handover process, but includes information required in the registration procedure (AAI_REG-REQ / RSP handshake), but the latency if such information is outdated or not acquired by the terminal In terms of latency, inefficiency may occur. In this case, the UE may include information for requesting S-SFH SP3 information in the ranging request (AAI_RNG-REQ) message when transmitting the ranging request message to the target base station. Accordingly, the target base station may transmit the S-SFH-SP 3 information to the terminal through a ranging response (AAI_RNGRSP) message.

Sixth embodiment

Hereinafter, when the terminal receives the latest system information (SFH) of the target base station from the serving base station, it will be described in detail with respect to the method (when to apply) when to apply the latest system information received by the terminal. .

If the terminal does not have the latest SFH information of the target base station to be HO, serving ABS may update the SFH information held by the terminal with the delta SFH information through the AAI_HO-CMD message to the terminal.

However, since the terminal does not know when the updated SFH information is applied in the target base station, the terminal does not know which SFH information to use when network re-entry.

Here, the information on when the SFH information is applied has a variable 'SFH applying offset' in the P-SFH information, but this problem occurs because it is not included in the neighbor advertisement message (AAI_NBR-ADV) message.

Therefore, the present invention intends to provide a method for applying the latest SFH information received from the serving base station through the following method.

One. AAI _ NBR - ADV P- SFH  Include information

The serving base station includes P-SFH information in the neighbor advertisement message (AAI_NBR-ADV) and transmits it to the terminal. In this case, the terminal can basically know when the updated SFH information is applied in the target base station.

In this case, since the UE normally updates the SFH information of the target base station through the AAI_NBR-ADV message received from the serving base station, the terminal applies the updated SFH information when reentering the network.

2. SFH delta information apply indicator

The serving base station includes an indicator indicating whether to apply the updated SFH information in the AAI_HO-CMD message to the terminal, so that the terminal can know whether to apply the updated SFH information at the time of network re-entry. .

That is, the UE can know whether or not to apply the latest SFH update information transmitted in the AAI_HO-CMD message at the time of network re-entry to the target ABS through the 1-bit indicator included in the AAI_HO-CMD message.

As another method, the serving base station may transmit the updated SFH information application time information in the AAI_HO-CMD message to the terminal, so that the terminal can know the application time of the updated SFH information.

In this case, the updated SFH delta information apply time offset indicates information indicating a few frames after the time when the serving base station transmits the AAI_HO-CMD message.

That is, the serving base station may inform the terminal of the number of frames so that when the terminal applies the SFH update information, it can inform the target base station.

Table 5 below shows an embodiment of the AAI_HO-CMD message including the SFH delta information apply indicator.

M / O Attributes / Array of attributes Size (bits) Value / Note Conditions O SFH delta  information indicator One Indicates the presence of SFH  delta information
0: SFH delta information is not included
One: SFH delta information is included Shall be included when  Mode = 0 b00 O SFH delta information Variable Delta encoding with reference to the serving ABS. May be included for each target ABS when Mode = 0b00 and SFH delta information is not included in the AAI_NBR-ADV message for the target ABS O SFH delta  information apply indicator One Indicates whether to apply the  included SFH delta information  when performing network re -entry at target ABS or not .
0: AMS shall perform network  re-entry at target ABS using the  old SFH information
One: AMS shall perform network  re-entry at target ABS using  the provided SFH delta information Shall be included when  SFH delta information  indicator is set to  One

Table 6 below shows an embodiment of an AAI_HO-CMD message including SFH delta information apply time offset.

M / O Attributes / Array of attributes Size (bits) Value / Note Conditions O SFH delta  information indicator One Indicates the presence of SFH  delta information
0: SFH delta information is not included
One: SFH delta information is included Shall be included when  Mode = 0 b00 O SFH delta information Variable Delta encoding with reference to the serving ABS. May be included for each target ABS when Mode = 0b00 and SFH delta information is not included in the AAI_NBR-ADV message for the target ABS O SFH delta  information apply  time offset 8 The number of frames from the  transmission of AAI _ HO - CMD  message indicates the time  offset when the AMS shall  apply the SFH delta  information at the target ABS . May be included for each  target ABS when Mode  = 0b00 and SFH delta  information is not  included in the  AAI_NBR-ADV message for the  target ABS

Terminal and base station structure

Hereinafter, as another embodiment of the present invention, a terminal and a base station in which the above-described embodiments of the present invention can be performed will be described.

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

The transmitter and the receiver may include a controller, a module, a part and / or a means for performing the 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.

8 is a block diagram illustrating an example of a terminal 810 and a base station 820 according to another embodiment of the present invention.

Referring to FIG. 8, the left side represents the terminal 810 and the right side represents the base station 820. Each of the terminal and the base station includes an antenna, a control unit 812 and 822, a transmission module (Tx modules 811-1 and 821-1), a reception module (Rx modules 811-2 and 821-2), and a memory 813. 823). Each component may perform a function corresponding to each other. Hereinafter, each component will be described in more detail.

The antenna transmits a signal generated by the transmission module (Tx module (811-1, 821-1)) to the outside, or receives a radio signal from the outside to the receiving module (Rx module (811-2, 821-2)) Perform the function of passing. When the multiple antenna (MIMO) function is supported, two or more may be provided.

The antenna, the transmission module and the reception module may together constitute a radio communication (RF) module.

The controllers 812 and 822 typically control the overall operation of the entire mobile terminal. For example, a controller function for performing the above-described embodiments of the present invention, a medium access control (MAC) frame variable control function, a handover function, an authentication and an encryption function, etc. according to service characteristics and a propagation environment may be used. Can be performed. More specifically, the controllers 812 and 822 may perform overall control for performing the above handover procedure.

In particular, the controller of the mobile terminal may obtain change count information of the corresponding message and system information (ie, SFH information) of the neighboring base station through the neighbor advertisement (AAI_NBR-ADV) message broadcast from the serving base station.

The controller may determine whether a predetermined handover condition is satisfied, and when the corresponding condition is satisfied, the controller may control a handover request message including change count information obtained to request the handover to the serving base station to be transmitted to the serving base station. have. If the handover initiated by the base station, this procedure will not be performed.

Thereafter, the UE may determine whether the UE is in an SFH mismatch state through the change count information included in the handover command message received from the serving base station.

Accordingly, the control unit may control to receive the latest SFH directly from the target base station through the EBB handover or obtain mismatched SFH information through the handover command message. Alternatively, the controller may notify the serving base station of the handover rejection and update the system information of the target base station through the latest version of the neighbor advertisement message received next.

For a more detailed procedure of the operation of the control unit described above, the overall control operation of the operation process disclosed in the above-described embodiments with reference to FIGS. 3 to 7 may be performed.

The transmission module (Tx module 811-1, 821-1) performs a predetermined coding and modulation on data scheduled from the controllers 812 and 822 to be transmitted to the outside, and then transmits the data to the antenna. Can be.

Receiving modules (Rx modules 811-2 and 821-2) decode and demodulate radio signals received through an antenna from the outside to restore the original data to form original data. 822).

The memories 813 and 823 may store a program for processing and controlling the controllers 812 and 822, and provide a function for temporarily storing input / output data (for example, system information of the target base station). It can also be done. In addition, the memories 813 and 823 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). Etc.), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EPEROM), programmable read-only memory (PROM), At least one type of storage medium may include a magnetic memory, a magnetic disk, and an optical disk.

On the other hand, the base station is 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 function 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 and 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 above-described modules, or may further include additional means, modules or parts for performing such a function.

The invention can be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative.

The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. In addition, the claims may be incorporated into claims that do not have an explicit citation relationship in the claims, or may be incorporated into new claims by amendment after filing.

810: terminal
820: base station
811, 821: wireless communication unit
812, 822: control unit
813, 823: memory

Claims (20)

In the handover process, in the operation method of the terminal for updating the control information (SFH) of the target base station,
Receiving a neighbor advertisement message from a serving base station including control information of at least one neighbor base station including the target base station;
Transmitting a handover request message including first change count information indicating a change count of the received neighbor advertisement message to the serving base station;
Receiving a handover command message from the serving base station, the handover command message including delta control information different from the control information included in the received neighbor advertisement message; And
And updating the control information of the target base station using the received difference control information. The method of claim 1,
The handover command message further includes second change count information indicating a change count of a neighbor advertisement message held by the serving base station,
And the difference control information is included in the handover command message when the first change count information and the second change count information are different. The method of claim 1,
The handover command message may further include indication of application of the difference control information. The method of claim 3, wherein
And the indication of application of the difference control information is information indicating whether to apply the difference control information received from the serving base station to the target base station when performing a network reentry process. The method of claim 1,
The handover command message may further include information on when to apply the difference control information. 6. The method of claim 5,
The difference control information application timing information indicates a time offset from a frame number in which the handover command message is transmitted when the difference control information is applied when the terminal performs a network reentry process to the target base station. How to. The method of claim 1,
And the control information is a superframe header. The method of claim 1,
Transmitting a ranging request message to the target base station using the updated control information; And
Receiving a ranging response message from the target base station. In the handover process, in the operation method of the terminal for updating the control information (SFH) of the target base station,
Receiving a handover command message from the serving base station including first change count information indicating a change count of a neighbor advertisement message;
Checking whether the received first change count information and second change count information held by the terminal match; And
And if there is a mismatch, transmitting a handover indication message including an event code indicating the cancellation of a handover command requested by the serving base station to the serving base station. The method of claim 9,
Receiving a first message from the serving base station including the latest version control information of the target base station; And
And updating the control information currently held by the terminal with the latest version control information. The method of claim 9,
The handover indication message further comprises a control information mismatch indicator indicating that the control information included in the handover command message is not the latest control information for the target base station. The method of claim 9,
And the control information is a superframe header. The method of claim 10,
And the first message is a NBR-ADV message. In the handover process, the terminal for updating the control information (SFH) of the target base station,
Memory;
A wireless communication unit for transmitting and receiving wireless signals with the outside; And
Control the wireless communication unit to receive a neighbor advertisement message including control information of at least one neighboring base station including the target base station from a serving base station, and receive first change count information indicating a change count of the received neighbor advertisement message. Control the wireless communication unit to transmit a handover request message including the handover command message to the serving base station, and receive a handover command message including delta control information different from the control information included in the neighbor advertisement message from the serving base station; And a controller configured to control the wireless communication unit to control the wireless communication unit and to update the control information of the target base station using the received difference control information. The method of claim 14,
The handover command message further includes second change count information indicating a change count of a neighbor advertisement message held by the serving base station,
The control unit,
And the difference control information is included in the handover command message when the first change count information and the second change count information are different. The method of claim 14,
The handover command message further comprises an indication of application of the difference control information. 17. The method of claim 16,
The indication of application of the difference control information is information indicating whether to apply the difference control information received from the serving base station when performing a network re-entry process to the target base station. The method of claim 14,
The handover command message, characterized in that the terminal further comprises the information on when to apply the difference control information. 19. The method of claim 18,
The difference control information application timing information indicates a time offset from a frame number in which the handover command message is transmitted when the difference control information is applied when the terminal performs a network reentry process to the target base station. Terminal. The method of claim 14,
And the control information is a superframe header.

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