KR20090100478A - Method of performing location update in wireless communication system - Google Patents

Abstract

PURPOSE: A method for performing the location update in a wireless communication system is provided to remove the collision which may be generated by a contention-based initial ranging. CONSTITUTION: A method for performing the location update in a wireless communication system comprises the following steps of: transmitting a message for requesting to periodically transmit a paging message for instructing execution of the location update(S210); periodically receiving the paging message in an idle mode(S230,S240); and receiving a response message including the transmission period of the paging message. The request message is a DREG- REQ(Deregistration-Request) message. The paging message includes a dedicated code for the location update.

Description

How to perform location update in wireless communication system {METHOD OF PERFORMING LOCATION UPDATE IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a wireless communication system, and more particularly to a method for performing a periodic location update.

The Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard provides technologies and protocols to support broadband wireless access. Standardization has been in progress since 1999, and IEEE 802.16-2001 was approved in 2001. It is based on a single carrier physical layer called 'WirelessMAN-SC'. Later, in the IEEE 802.16a standard approved in 2003, 'WirelessMAN-OFDM' and 'WirelessMAN-OFDMA' were added to the physical layer in addition to 'WirelssMAN-SC'. After the completion of the IEEE 802.16a standard, the revised IEEE 802.16-2004 standard was approved in 2004. In order to correct bugs and errors in the IEEE 802.16-2004 standard, IEEE 802.16-2004 / Cor1 was completed in 2005 in the form of 'corrigendum'.

The communication channel between the base station and the terminal is composed of a downlink (DL, downlink) channel from the base station to the terminal and an uplink (UL, uplink) channel from the terminal to the base station.

In general, a state mode of a terminal may be divided into an active mode and an idle mode. In the active mode, the UE continuously communicates with and receives data from the BS.

The idle mode is a mechanism that can receive a downlink broadcast message periodically without registering with a specific base station, even if the terminal roams a wireless link environment having a plurality of base stations over a wide area. Idle mode stops all normal operations as well as handover (HO), and only adjusts downlink synchronization to receive paging messages, which are broadcast messages, over a period of time. It is set. The paging message is a message instructing the paging action (paging action) to the terminal. For example, paging operations include ranging, network reentry, and the like.

The terminal entering the idle mode operates in an unavailable interval or listening interval. During the unavailable period, the terminal cannot receive the downlink message. However, the terminal may power down, scan a neighbor BS, reselect a preferred base station, or perform ranging. Here, the neighbor BS refers to a base station that is not a serving base station. The terminal wakes up at a certain listening interval and receives a paging message or takes an action corresponding thereto. Idle mode is provided to save power and resources of the base station when the terminal has little communication with the base station.

The paging controller stores idle mode retain information, which is information about a terminal entering the idle mode, and controls a paging related operation for the terminal. The idle mode retention information is for quickly processing network reentry by minimizing a state trasition delay when the idle mode terminal performs network reentry. The idle mode holding information includes a terminal service (MS service), operational information of the terminal, location information of the terminal, and the like. For example, the paging controller may be included in a serving BS or may be a separate network entity. Here, the serving base station refers to a base station which the mobile station has most recently registered. The paging controller operates an idle mode system timer, which is the maximum time for storing idle mode retention information. When the idle mode system timer expires, the paging controller deletes the stored idle mode holding information and stops paging related control for the corresponding terminal. The paging controller exchanges information about the terminal with the base station through a backbone network.

The idle mode terminal may perform a location update to update its location information stored in the paging controller. When performing the position update, the idle mode system timer of the paging controller is reset. The terminal will not want the paging controller to delete the idle mode retention information of the terminal except in special circumstances. Accordingly, the terminal must update its position to initialize the idle mode system timer so that the paging controller can continue to store the idle mode retention information of the terminal. However, since the idle mode system timer expires after a predetermined time, the idle mode system timer may be continuously initialized by periodically performing the location update. That is, if the location update is performed periodically, the paging controller may continue to store the idle mode holding information of the terminal. Therefore, there is a need for a method that can efficiently perform periodic location updates.

An object of the present invention is to provide a method for efficiently performing periodic location update in a wireless communication system.

In one aspect, a method of performing a location update in a wireless communication system is provided. The method includes transmitting a request message requesting to periodically transmit a paging message instructing to perform a location update, and periodically receiving the paging message in an idle mode.

In another aspect, a method of performing a location update in a wireless communication system is provided. The method includes receiving a request message requesting to periodically transmit a paging message instructing to perform a location update and periodically transmitting the paging message.

The idle mode terminal may periodically perform a location update, such that the paging controller may continue to store the idle mode holding information of the terminal. Therefore, the network re-entry of the terminal in the future can be processed quickly. In addition, a dedicated code may be included in the paging message to perform periodic location update through dedicated ranging. In this case, collisions that may occur due to contention-based initial ranging can be eliminated, resource waste can be minimized, and location update can be performed quickly. In addition, since there is no need to retransmit the control message for ranging when a collision occurs, the performance of the entire system can be expected by reducing the number of retransmission of the control message.

The following techniques can be used in various wireless communication systems. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like. This technique can be used for downlink or uplink. In general, downlink means communication from a base station (BS) to a mobile station (MS), and uplink means communication from a terminal to a base station. A base station generally refers to a fixed station for communicating with a terminal, and may be referred to in other terms such as node-B, base transceiver system (BTS), and access point. The terminal may be fixed or mobile and may be called in other terms such as user equipment (UE), user terminal (UT), subscriber station (SS), wireless device (wireless device), and the like.

The wireless communication system may be an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) based system. OFDM uses multiple orthogonal subcarriers. OFDM uses orthogonality between inverse fast Fourier Transform (IFFT) and fast Fourier Transform (FFT). At the transmitter, data is sent by performing an IFFT. The receiver performs FFT on the received signal to recover the original data. The transmitter uses an IFFT to combine multiple subcarriers, and the receiver uses a corresponding FFT to separate multiple subcarriers.

1 is a block diagram showing elements of a terminal.

Referring to FIG. 1, the terminal 50 includes a processor 51, a memory 52, an RF unit 53, a display unit 54, and a user interface unit. , 55). The processor 51 is responsible for transmitting and receiving a physical layer or medium access control (MAC) message. The following data transmission and reception method may be implemented through the processor 51. The memory 52 is connected to the processor 51 to store a terminal driving system, an application, and a general file. The display unit 54 displays various information of the terminal, and may use well-known elements such as liquid crystal display (LCD) and organic light emitting diodes (OLED). The user interface unit 55 may be a combination of a well-known user interface such as a keypad or a touch screen. The RF unit 53 is connected to a processor and transmits and / or receives a radio signal.

2 shows an example of a frame structure. A frame is a sequence of data for a fixed time used by physical specifications. This may be referred to section 8.4.4.2 of the IEEE standard 802.16-2004 "Part 16: Air Interface for Fixed Broadband Wireless Access Systems" (hereafter reference 1).

Referring to FIG. 2, the frame includes a downlink (DL) subframe and an uplink (UL) subframe. Time division duplex (TDD) is a method in which uplink and downlink transmissions share the same frequency but occur at different times. The downlink subframe is temporally ahead of the uplink subframe. The downlink subframe starts with a preamble, a frame control header (FCH), a downlink (DL) -MAP, an uplink (MAP) -MAP, and a burst region. A guard time for distinguishing the downlink subframe and the uplink subframe is inserted in the middle part (between the downlink subframe and the uplink subframe) and the last part (after the uplink subframe) of the frame. A transmit / receive transition gap (TGT) is a gap between a downlink burst and a subsequent uplink burst. A receive / transmit transition gap (RTG) is a gap between an uplink burst and a subsequent downlink burst.

The preamble is used for initial synchronization, cell search, frequency offset, and channel estimation between the base station and the terminal. The FCH includes the length of the DL-MAP message and the coding scheme information of the DL-MAP.

DL-MAP is an area where a DL-MAP message is transmitted. The DL-MAP message defines access to the downlink channel. This means that the DL-MAP message defines the indication and / or control information for the downlink channel. The DL-MAP message includes a configuration change count of a downlink channel descriptor (DCD) and a base station identifier (ID). DCD describes a downlink burst profile applied to the current map. The downlink burst profile refers to a characteristic of a downlink physical channel, and the DCD is periodically transmitted by the base station through a DCD message.

The UL-MAP is an area in which the UL-MAP message is transmitted. The UL-MAP message defines a connection to an uplink channel. This means that the UL-MAP message defines the indication and / or control information for the uplink channel. The UL-MAP message includes a configuration change count of an uplink channel descriptor (UCD) and an allocation start time of uplink allocation defined by UL-MAP. UCD describes an uplink burst profile. The uplink burst profile refers to characteristics of an uplink physical channel, and the UCD is periodically transmitted by the base station through a UCD message.

The downlink burst is an area in which data transmitted from the base station to the terminal is transmitted, and the uplink burst is an area in which data transmitted from the base station to the terminal is transmitted.

The uplink subframe may include a ranging subchannel. The ranging subchannel is a ranging region allocated for the ranging request of the terminal. The ranging region is allocated by the UL-MAP message.

In the following, a slot is defined as the minimum possible data allocation unit, time and subchannel. The number of subchannels depends on the FFT size and the time-frequency mapping. The subchannel includes a plurality of subcarriers, and the number of subcarriers per subchannel depends on a permutation scheme. Permutation means mapping logical subchannels to physical subcarriers. The IEEE 802.16 standard uses permutations such as full usage of subchannels (FUSC), partial usage of subchannels (PUSC), optinal-FUSC (O-FUSC), optional-PUSC (O-PUSC), and adaptive modulation and coding (AMC). It starts. A set of OFDMA symbols in which the same permutation scheme is used is called a permutation zone, and one frame includes at least one permutation region. The definition of a slot depends on the permutation scheme. For example, when a PUSC permutation is used, the ranging slot, which is a slot in the ranging region, is 3 OFDMA symbols in one subchannel.

3 shows an example of a paging group.

Referring to Fig. 3, the base stations are arranged in a hexagonal grid. The plurality of base stations are divided into logical groups (logical gruop) called paging groups. One base station may belong to one or more paging groups. The purpose of the paging group is to provide a contiguous coverage region so that the terminal does not need to perform uplink transmission but can receive a paging message that is a broadcast message. The size of the paging group should be large enough so that most of the terminals remain in the same paging group for a certain time, and should be small enough that the occurrence of paging overhead is adequate. Base stations belonging to different groups may transmit paging messages at different periods. That is, the base stations belonging to the same group broadcast the same paging message to all terminals belonging to the group during the same period.

4 is a flowchart illustrating an example of an idle mode terminal operation.

Referring to FIG. 4, the terminal is deregistered from the base station and enters an idle mode (S110). The base station may be a paging controller. If the paging controller is a separate network entity, the base station exchanges information with the paging controller through the backbone network. When the idle mode is initiated, the paging controller starts an idle mode system timer. The idle mode system timer is the maximum time the paging controller can store idle mode hold information. The terminal operates an idle mode timer corresponding to the idle mode system timer.

During the listening period, the terminal receives a DL-MAP / UL-MAP message and a DCD / UCD message (S120). In order to decode the paging message, the UE decodes the DL-MAP message and the DCD message and synchronizes the downlink of the preferred base station. The DCD message includes a paging group identifier (Identifier) identifying a paging group to which the base station belongs.

During the listening interval, the terminal receives a MOB_PAG-ADV (BS broadcast paging) message, which is a paging message (S130). The MOB_PAG-ADV message indicates a paging action to be performed by the terminal.

The idle mode terminal performs location update due to various causes (S140). If the position update is successful, the idle mode timer and idle mode system timer are reset. If the idle mode system timer expires, the paging controller deletes the stored idle mode holding information and stops the paging related control for the corresponding terminal. If the idle mode timer expires, the terminal considers the paging controller to delete the idle mode holding information.

Hereinafter, each operation of the idle mode terminal and the base station will be described in detail.

Now, the idle mode entry process of the terminal will be described.

The idle mode is initiated by the terminal transmitting a DREG-REQ message to the base station or receiving a De / Reregister command (DREG-CMD) message from the base station. The DREG-REQ message is sent to inform the UE that it is deregistration from the normal operation service of the base station. The DREG-CMD message is transmitted by the base station to change the access state of the terminal. The DREG-CMD message may be sent in response to the DREG-REQ message or may be sent unsolicited.

The following table shows an example of a format of a DREG-REQ message.

Management Message Type is to identify the type of management message. If the management message type is '49', this means that it is a DREQ-REQ message. The deregistration_Request_Code is a code for identifying the type of deregistration request. If the deregistration request code is '0x00', it is a deregistration request from the base station and the network. If the deregistration request code is '0x01', it is a deregistration and idle mode start request from the serving base station. If the deregistration request code is '0x02', it is a response to deregistration initiated from the base station. If the deregistration request code is '0x03', it is a rejection of the idle mode request from the base station.

The DREG-REQ message requesting to initiate idle mode (unregistration request code = '0x01') includes an idle mode retain information parameter, a medium access control (MAC) hash skip threshold (MAC Hash Skip Threshold) parameter, and the like. It may include. The idle mode retention information parameter is idle mode retention information that the terminal requests to hold the paging controller. For example, the idle mode retention information parameter may be associated with terminal service and operation information associated with an SS basic capability-Request / Response (SBC-REQ / RSP) message, and a privacy key management-Request / Response (PKM-REQ / RSP) message. Terminal service and operation information, and terminal service and operation information associated with a Registration-Request / Response (REG-REQ / RSP) message. The MAC hash omission threshold parameter is the maximum number of times that the MOB_PAG-ADV message without the terminal MAC address hash can be continuously transmitted. The terminal MAC address hash is a hash of the terminal MAC address. Here, the terminal MAC address is a unique identifier assigned in the manufacturing step and used for identification of the terminal. For example, when the size of the terminal MAC address is 48 bits, the size of the terminal MAC address hash may be 24 bits.

The following table shows an example of a format of a DREG-CMD message.

The management message type is to identify the type of management message. If the management message type is '29', this means that it is a DREQ-CMD message. An action code indicates an operation to be performed by a terminal. The following table shows an example of the action code.

If the action code is '0x00', the terminal immediately terminates the service with the base station, and should attempt network entry to another base station. If the action code is '0x01', the terminal listens to the base station but does not transmit the uplink. If the action code is '0x02', the terminal listens to the base station, but should transmit an uplink only through a basic connection or a primary management connection. If the action code is '0x03', the terminal recovers to normal operation. If the action code is '0x04', the terminal should terminate the normal operation with the base station in response to the DREG-REQ message with the deregistration request code '0x00'. If the action code is '0x05', the terminal must immediately deregister from the base station and request to start the idle mode. When the action code is '0x06', it is a response to a DREG-REQ message (deregistration request code = '0x01') requesting to start idle mode.

The DREG-CMD message may include a request duration parameter. In this case, the terminal may retransmit the DREG-REQ message when the request period expires.

The DREG-CMD message (action code = '0x05') requesting to start the idle mode may include a paging information parameter, a paging controller ID parameter, an idle mode retention information parameter, a MAC hash skip threshold parameter, and the like. The paging information parameter includes a paging cycle, which is a transmission period of a paging message, a paging offset indicating a frame in which a paging message is transmitted in the paging cycle, a paging group ID, and the like. The paging controller ID is a paging controller identifier. The idle mode retention information parameter indicates the idle mode retention information held and managed by the paging controller.

The idle mode may be initiated by the terminal or initiated by the base station.

When initiated by the terminal, the terminal may be initiated by sending a DREG-REQ message (deregistration request code = '0x01') requesting to start idle mode, and in response to the base station transmitting a DREG-CMD message. .

Initiation by the base station is as follows. The base station transmits a DREG-CMD message (action code = '0x05') requesting to start the idle mode, and in response, the base station may start by sending a DREG-REQ message (deregistration request code = '0x02'). have. If there is uplink data pending, the terminal may transmit a DREG-REQ message (deregistration request code = '0x03') that rejects the idle mode start request of the base station. In this case, no idle mode is started.

As another method initiated by the base station, the base station may send a DREG-CMD message (action code = '0x05') requesting to start the idle mode including the request interval parameter. In this case, the terminal may start the idle mode by transmitting a DREG-REQ message (deregistration request code = '0x01') requesting the idle mode to start when the request period expires.

Now, the MOB_PAG-ADV message, which is a paging message received by the terminal during the listening period, will be described.

The following table shows an example of the MOB_PAG-ADV message format.

The MOB_PAG-ADV message includes a management message type, the number of paging group IDs (Num_Paging_Group_IDs), the paging group ID, the number of terminal MAC addresses (Num_MACs), the terminal MAC address hash, and an action code. The management message type is to identify the type of management message. If the management message type is '61', this means that the message is MOB_PAG-ADV. The number of paging group IDs and the paging group ID identify the paging group to which the base station belongs. The number of terminal MAC addresses and the terminal MAC address hash identify the terminal. The action code indicates the paging operation to be performed by the terminal.

If the action code is '0b00', no paging operation is required for the terminal. If the action code is '0b01', the terminal performs ranging for location update and informs that it has received a message. If the action code is '0b10', the terminal enters the network.

Now, the location update of the idle mode terminal is described.

The location update may be caused by the base station or by the terminal. In some cases, the base station transmits a MOB_PAG-ADV message (action code = '0b01') indicating the location update. Cases caused by the terminal may include a paging group update, a power down update, a MAC hash skip threshold update, and the like.

The paging group update is performed when the terminal reselects a base station belonging to another paging group as a preferred base station. For example, the UE reselects a second base station belonging to a second paging group as a preferred base station from a first base station belonging to a first paging group. The UE recognizes that the paging group is changed through the paging group ID included in the DCD message or the MOB_PAG-ADV message. Upon recognizing the paging group change, the terminal performs a location update to update the location information of the terminal stored in the paging controller.

The power reduction update is for the terminal to request the paging controller to delete the idle mode retention information of the terminal before power reduction. If the terminal does not perform the power reduction update, the paging controller unnecessarily stores the idle mode holding information until the idle mode system timer expires. Therefore, the terminal provides the paging controller with accurate state information of the terminal through the power reduction update, so that the paging controller can immediately delete the idle mode holding information of the terminal.

The MAC hash skip threshold update is performed when the MAC hash skip counter of the terminal exceeds the MAC hash skip threshold. After the location update, the terminal and the base station reinitialize each MAC hash omission counter. The MAC hash omission threshold may be transmitted in a DREG-REQ / CMD message or a RNG-REQ / RSP (Ranging-Request / Response) message.

In addition, the idle mode terminal may periodically perform a location update to initialize the idle mode system timer.

5 illustrates an example of a method of performing periodic location update.

Referring to FIG. 5, the terminal enters an idle mode through a DREG-REQ / CMD message. When the idle mode is started, the paging controller operates the idle mode system timer, and the terminal operates the idle mode timer. The terminal receives a MOB_PAG-ADV message, which is a paging message at a paging cycle. For example, the MOB_PAG-ADV message (action code = '0b00') is a paging message that requires no paging operation from the terminal. The UE periodically performs a location update through initial ranging d before the idle mode timer expires. If the location update is successful, the idle mode system timer of the paging controller and the idle mode timer of the terminal are initialized. Thus, the paging controller continues to store idle mode retention information. If the position update is not performed and the idle mode system timer and idle mode timer expire, the paging controller deletes the idle mode holding information.

Here, location update was performed through initial ranging. Initial ranging is performed by a terminal randomly selecting a ranging slot in a ranging region, randomly selecting a code division multiple access (CDMA) code, and transmitting the CDMA code through the ranging slot. Therefore, initial ranging is a contention-based process in which a plurality of terminals transmit the same ranging code through the same ranging slot to cause a collision. In case of a collision, the UE should attempt initial ranging by randomly selecting a ranging slot and a ranging code. In this case, a lot of time and radio resources are consumed.

However, paging group update, power reduction update, MAC hash skip threshold update, etc. are triggered by an event, but a position update for initializing an idle mode system timer is periodically triggered. In the case of the periodic location update, although the contention-based initial ranging is used even though the idle mode timer is periodically performed before the idle mode timer expires, the probability of collision occurs is inefficient. Therefore, in the case of periodic location update, there is a need for a method of location update through non-contention based dedicated ranging.

6 is a flowchart illustrating a method of performing a location update according to an embodiment of the present invention.

Referring to FIG. 6, the terminal transmits a DREG-REQ message (registration request code = '0x01') requesting to start the idle mode to the base station (S210), and the base station transmits a DREG-CMD message to the terminal (S220). ) Idle mode is started. The base station may be a paging controller. If the paging controller is a separate network entity, the base station exchanges information with the paging controller through the backbone network. When the idle mode is initiated, the terminal operates the idle mode timer and the base station operates the idle mode system timer.

The DREG-REQ message (deregistration request code = '0x01') requesting to start the idle mode may further include a Periodic Location Update Indication parameter. The periodic location update indication parameter is to request the base station to periodically transmit a paging message instructing to perform a location update. For example, when the size of the periodic location update indication parameter is 1 bit, '0' does not request the base station to periodically transmit a paging message instructing to perform the location update, and '1' performs the location update to the base station. It is a request to periodically send a paging message indicating. For example, a paging message for instructing the base station to perform location update is a MOB_PAG-ADV message (action code = '0b01').

The DREG-CMD message may include a response bit indicating an acceptance or rejection of the DREG-REQ message when the DREG-REQ message indicates a periodic location update. The DREG-CMD message may include a location update period parameter when the periodic location update indication is accepted. The location update period parameter means a period during which the base station transmits a paging message indicating the location update. The location update period is a smaller time interval than the idle mode system timer. For example, the location update period may be a transmission period of the MOB_PAG-ADV message (action code = '0b01') indicating the location update. Since the location update period parameter is a transmission period of a paging message, a paging cycle or seconds may be used as a unit.

Alternatively, the DREG-CMD message may include only the location update period parameter, not the response bit, when the DREG-REQ message indicates the periodic location update. In this case, whether to accept the periodic location update indication may be implicitly informed through the location update period parameter. For example, when the value of the position update period parameter is '0', the position update period is rejected.

The base station transmits a MOB_PAG-ADV message, which is a paging message (S230). The MOB_PAG-ADV message (action code = '0b00') is a paging message that does not request any paging operation from the terminal.

The base station periodically transmits a MOB_PAG-ADV message (action code = '0b01') indicating the location update (S240). The MOB_PAG-ADV message indicating the location update is periodically transmitted with a time interval smaller than the idle mode system timer. The MOB_PAG-ADV message indicating the location update may include a dedicated code for location update.

The terminal performs a location update (S250). In this case, the terminal may perform location update through dedicated ranging using a dedicated code received through a MOB_PAG-ADV message. A detailed process of location update through dedicated ranging will be described later.

Since the MOB_PAG-ADV message indicating the position update is transmitted at a transmission interval smaller than the idle mode system timer, and because the position update is performed, the idle mode system timer is initialized before expiration. In addition, an idle mode timer corresponding to the idle mode system timer is also initialized. Therefore, the paging controller continues to store the idle mode holding information including the updated location information of the terminal, it is possible to quickly process the network re-entry of the terminal in the future.

Until the idle mode is terminated, a MOB_PAG-ADV message (action code = '0b00') is transmitted that does not require any paging operation to the terminal of the base station (S260), and a MOB_PAG-ADV message (action indicating the location update) The process of periodically transmitting the code = '0b01' (S270), performing location update through dedicated ranging (S280), and the like is repeated.

The method of performing location update may also be applied when the idle mode is initiated by the base station. For example, the base station transmits a DREG-CMD message (action code = '0x05') requesting to start the idle mode, and the terminal transmits a DREG-REQ message (deregistration request code = '0x02') in response. It is a case where it starts by doing.

In this case, the DREG-CMD message may include a location update period parameter. The location update period parameter is a transmission period of a paging message indicating a location update. Through the location update period parameter, the base station may implicitly inform that the terminal periodically transmits a paging message indicating the location update. The UE receiving the DREG-CMD message including the location update period parameter may include the periodic location update indication parameter in the DREG-REQ message. The periodic position update indication parameter means whether to accept the periodic position update. For example, when the size of the periodic location update indication parameter is 1 bit, '0' rejects the periodic update indication of the base station, and '1' accepts the periodic update indication of the base station. When the terminal accepts the periodic update instruction of the base station, the base station periodically transmits a paging message indicating the position update according to the position update period. For example, a message indicating the location update is a MOB_PAG-ADV message (action code = '0b01').

Now, a detailed process of location update through dedicated ranging is described. In order to perform location update through dedicated ranging, the base station provides dedicated ranging information. Dedicated ranging information includes a ranging area, a dedicated code, a transmission opportunity, and the like.

7 is a flowchart illustrating a location update process through dedicated ranging.

Referring to FIG. 7, the base station transmits a UL-MAP message (S310). The base station may be a paging controller. If the paging controller is a separate network entity, the base station exchanges information with the paging controller through the backbone network.

The UL-MAP message may allocate a ranging region and further include a dedicated ranging indicator. The ranging region may be allocated with an OFDMA symbol offset, a subchannel offset, an OFDMA symbol (No. OFDMA symobs), and a subchannel number (No. subchannels). The OFDMA symbol offset is the offset of the OFDMA symbol at which the ranging region begins. The subchannel offset is the lowest index of the ranging region subchannel. The number of OFDMA symbols is the number of OFDMA symbols used in the ranging region. The number of subchannels is the number of subchannels used in the ranging region. The dedicated ranging indicator indicates whether to perform dedicated ranging. For example, when the size of the dedicated ranging indicator is 1 bit, '0' instructs the terminal to perform initial ranging rather than dedicated ranging, and '1' instructs the terminal to perform dedicated ranging. Instruct.

The base station periodically transmits a MOB_PAG-ADV message (action code = '0b01'), which is a paging message indicating a location update (S320). The MOB_PAG-ADV message indicating the location update may include a dedicated code for location update and a transmission opportunity. The dedicated code is a CDMA code which is a pseudonoise code generated by a pseudo-random binary sequence (PRBS). The transmission opportunity is an opportunity to transmit a dedicated code within the ranging region allocated by the UL-MAP message. The transmission opportunity may be expressed as an offset from the ranging region.

The terminal transmits a CDMA code which is a dedicated code to the base station (S330). The terminal performs dedicated ranging by transmitting a dedicated code at a transmission opportunity within the ranging region. The dedicated code is transmitted after binary phase shift keying (BPSK) modulation.

The base station transmits a ranging-response (RNG-RSP) message to the terminal (S340).

The following table shows an example of a format of an RNG-RSP message.

The management message type is to identify the type of management message. If the management message type is '5', this means that it is an RNG-RSP message.

In addition, the RNG-RSP message may include a ranging status parameter, a MAC hash skip threshold parameter, and the like.

The ranging state parameter is an indicator of whether the base station accepts the uplink message. If the ranging state parameter is '1 = continue', the terminal transmits the CDMA code, which is a dedicated code again. If the ranging state parameter is '2 = abort', the terminal must acquire downlink synchronization again.

If the ranging state parameter is '3 = success', the base station transmits a CDMA allocation message (S350). The CDMA assignment message allocates bandwidth to the UE and is included in the UL-MAP message and transmitted. For example, bandwidth allocation may be in units of OFDMA slots.

The terminal transmits a RNG-REQ (Ranging Request) message to the base station (S360). The RNG-REQ message sends the RNG-REQ message over the bandwidth allocated in the CDMA assignment message.

The following table shows an example of the format of the RNG-REQ message.

The management message type is to identify the type of management message. If the management message type is '4', this means that it is an RNG-REQ message. The RNG-REQ message may include a ranging purpose indication parameter, a paging controller ID parameter for identifying a paging controller, a MAC hash skip threshold parameter, and the like. In addition, the RNG-REQ message may further include a power down indicator parameter when the terminal attempts to update the location due to power reduction.

The ranging purpose indication parameter may be included when the terminal attempts network re-entry, handover (HO) or location update.

The following table shows an example of ranging purpose indication parameters.

Name Type (1 byte) Length Value (Variable-length) PHY Scope Ranging Purpose Indication 6 One Bit 0: HO indication (when this bit is set to 1 in combination with other included information elements indicates the MS is currently attempting to HO or network reentry from idle mode to the BS) Bit 1: Location update request (when this bit is set to 1, it indicates MS action of idle mode location update process) Bits 2-7: Reserved -

When 'bit 0' of the ranging purpose indication parameter is '1', it indicates that the terminal attempts to handover or reenters the network from the idle mode. When the 'bit 1' of the ranging purpose indication is '1', it indicates that the idle mode terminal attempts a location update. Since the idle mode terminal is performing the location update, 'bit 1' of the ranging purpose indication parameter of the RNG-REQ message is '1'.

The base station transmits an RNG-RSP message to the terminal (S370).

The RNG-RSP message is sent in response to the RNG-REQ message. If the response to the RNG-REQ message requesting a location update, where 'bit 1' of the ranging purpose indication parameter is '1', the RNG-RSP message may further include a Location Update Response parameter. have.

The following table shows an example of the location update response parameter.

Name Type (1 byte) Length Value (Variable-length) PHY Scope Location Update Response 6 One 0x00 = Success of Location Update 0x01 = Failure of Location Update 0x02 = Reserved 0x03 = Success of location update and DL traffic pending 0x04 ~ 0xFF: Reserved All

When the location update response is '0x00', it indicates that the location update has been successful, and when the location update response is '0x01', it indicates that the location update has failed. If the periodic location update indication is '0x03', it indicates that the location update was successful and there is downlink traffic pending.

If the position update is successful, the idle mode system timer of the paging controller is initialized. Therefore, the paging controller continues to store the idle mode holding information including the updated location information of the terminal, it is possible to quickly process the network re-entry of the terminal in the future.

As noted, in order to perform location update via dedicated ranging, a ranging area is allocated in a UL-MAP message, and a dedicated code and transmission opportunity are MOB_PAG-ADV messages (action code = '0b01') indicating the location update. ) Can be assigned. By performing periodic location update through dedicated ranging, collisions that may occur due to contention-based initial ranging may be eliminated. Therefore, it is possible to minimize the waste of resources and to perform the location update quickly. In addition, since there is no need to retransmit the control message for ranging when a collision occurs, the performance of the entire system can be expected by reducing the number of retransmission of the control message.

8 is a flowchart illustrating a method of performing a location update according to another embodiment of the present invention.

Referring to FIG. 8, the terminal transmits a DREG-REQ message (registration request code = '0x01') requesting to start the idle mode to the base station (S410), and the base station transmits a DREG-CMD message to the terminal (S420). ) Idle mode is started. The base station may be a paging controller. If the paging controller is a separate network entity, the base station exchanges information with the paging controller through the backbone network. When the idle mode is initiated, the terminal operates the idle mode timer and the base station operates the idle mode system timer.

The DREG-REQ message (deregistration request code = '0x01') requesting to start the idle mode may further include a periodic location update indication parameter. In addition, the DREG-CMD message may include a response bit informing of acceptance or rejection when the DREG-REQ message indicates a periodic location update. In addition, the DREG-CMD message may include a location update period parameter when accepting a periodic location update indication.

Alternatively, the DREG-CMD message may include only the location update period parameter, not the response bit, when the DREG-REQ message indicates the periodic location update. In this case, whether to accept the periodic position update instruction may be implicitly informed through the position update cycle parameter.

The base station transmits a MOB_PAG-ADV message, which is a paging message (S430). The MOB_PAG-ADV message (action code = '0b00') is a paging message that does not request any paging operation from the terminal.

The base station periodically transmits a MOB_PAG-ADV message (action code = '0b01') indicating the location update (S440). The MOB_PAG-ADV message indicating the location update is periodically transmitted with a time interval smaller than the idle mode system timer. The MOB_PAG-ADV message indicating the location update may include a dedicated code for location update.

The terminal performs the location update. In this case, the terminal may perform location update through dedicated ranging using a dedicated code received through a MOB_PAG-ADV message.

The terminal transmits a dedicated code. The base station transmits the RNG-RSP message in response to the dedicated code transmission, and allocates a bandwidth for the terminal to transmit the RNG-REQ message through the CDMA allocation message.

The terminal transmits an RNG-REQ message (S450). The RNG-REQ message may further include a Periodic Location Update Indication parameter. The periodic location update indication parameter is to change whether or not to periodically transmit a paging message instructing the base station to update the location.

The following table shows an example of a periodic position update indication parameter. The periodic location update indication parameter may be encoded in TLV (Type / Length / Value) format.

Name Type (1 byte) Length Value (Variable-length) PHY Scope Periodic Location Update Indication variable One This parameter indicates the availability of the periodic location update performed by the BS. 0x00: not perform the periodic location update 0x01: perform the periodic location update 0x02-0xFF: reserved OFDMA

If the periodic location update indication parameter is '0x00', it does not request the base station to periodically transmit a paging message indicating the location update, and if it is '0x01', periodically transmits a paging message indicating the location update to the base station. To ask.

That is, whether or not to periodically update the location may be maintained or changed through the periodic update indication parameter of the RNG-REQ message. When the base station performing periodic location update receives the RNG-REQ message with the location update indication parameter '0x01', maintains the periodic location update and receives the RNG-REQ message with the location update indication parameter '0x00' In this case, the base station should stop the periodic location update.

The base station transmits an RNG-RSP message (S455). The RNG-RSP message is sent in response to the RNG-REQ message. If the RNG-RSP message indicates a periodic location update, the RNG-RSP message may include a response bit indicating an acceptance or rejection thereof. In addition, the RNG-RSP message may include a location update period parameter when the periodic location update instruction is accepted.

The following table shows an example of the position update period parameters. The location update period parameter may be encoded in the TLV format.

Name Type (1 byte) Length Value (Variable-length) PHY Scope Location Update Interval variable variable This parameter indicates the time interval (explicit value: seconds or paging cycles) of the periodic location update performed by the BS. OFDMA

The location update period parameter means a period during which the base station transmits a message indicating location update. For example, the location update period may be a transmission period of the MOB_PAG-ADV message (action code = '0b01') indicating the location update. The location update period is a smaller time interval than the idle mode system timer. Since the location update period parameter is a transmission period of a paging message, a paging cycle or seconds may be used as a unit. That is, the transmission period of the paging message indicating the location update may be maintained or changed through the location update period parameter of the RNG-RSP message.

Alternatively, the RNG-RSP message may include only the location update period parameter, not the response bit, when the RNG-REQ message indicates the periodic location update. In this case, whether to accept the periodic position update instruction may be implicitly informed through the position update cycle parameter. For example, when the value of the position update period parameter is '0', it may be a rejection of the periodic position update instruction.

In the case where the periodic location update of the base station is maintained through the RNG-REQ / RSP message (S450, S455), the MOB_PAG-ADV message (action code = '0b00') not transmitted to the terminal of the base station is transmitted (S460). The periodic transmission (S470) of the MOB_PAG-ADV message (action code = '0b01') indicating the location update and the process of performing the location update through dedicated ranging are repeated. In addition, during the dedicated ranging process, it is possible to change whether to periodically update the location through the RNG-REQ / RSP message (S480, S485). If the periodic location update is stopped through the RNG-REQ / RSP message, the base station no longer periodically transmits a MOB_PAG-ADV message (action code = '0b01') indicating the location update.

The method of performing location update may also be applied when the idle mode is initiated by the base station.

As such, by including the periodic location update indication parameter in the RNG-REQ message and the location update period parameter in the RMG-RSP message, not only when the idle mode is started through the DREG-REQ / CMD message, but also the location update process It is possible to determine or change whether or not to periodically perform subsequent location updates.

9 illustrates an example of operations of an idle mode terminal and a base station.

Referring to FIG. 9, the terminal initiates an idle mode by transmitting a DREG-REQ message including a periodic update indication and receiving a DREG-CMD message. When the idle mode is initiated, the terminal operates the idle mode timer and the base station operates the idle mode system timer.

The base station transmits a MOB_PAG-ADV message having an action code of '0b00' during the paging listening section. In addition, the base station periodically transmits a MOB_PAG-ADV message (action code = '0b01') indicating the location update. At this time, the MOB_PAG-ADV message includes a dedicated code. Upon receiving the MOB_PAG-ADV message (action code = '0b01') indicating the location update, the UE performs the location update through dedicated ranging using the dedicated code. Dedicated ranging is done via RNG-REQ / RSP. The transmission period of the MOB_PAG-ADV message (action code = '0b01') indicating the location update is shorter than the expiration period of the idle mode timer and the idle mode system timer. The idle mode timer and idle mode system timer are initialized by sending a MOB_PAG-ADV message (action code = '0b01') indicating the location update. Again, a MOB_PAG-ADV message (action code = '0b01') indicating a location update is periodically transmitted, and location update is performed through dedicated ranging.

10 shows another example of an idle mode terminal operation.

Referring to FIG. 10, the terminal initiates an idle mode by transmitting a DREG-REQ message including a periodic update indication and receiving a DREG-CMD message. When the idle mode is initiated, the terminal operates the idle mode timer and the base station operates the idle mode system timer.

The base station transmits a MOB_PAG-ADV message having an action code of '0b00' during the paging listening section. In addition, the base station periodically transmits a MOB_PAG-ADV message (action code = '0b01') indicating the location update. At this time, the MOB_PAG-ADV message includes a dedicated code. Upon receiving the MOB_PAG-ADV message (action code = '0b01') indicating the location update, the UE performs the location update through dedicated ranging using the dedicated code. Dedicated ranging is done via RNG-REQ / RSP. The location update period is shorter than the expiration period of the idle mode timer and the idle mode system timer. The idle mode timer and idle mode system timer are initialized by sending a MOB_PAG-ADV message (action code = '0b01') indicating the location update. If there is a location update due to a paging group update, power reduction update, or MAC hash skip threshold update, before the MOB_PAG-ADV message (action code = '0b01') is sent in the next cycle, the Mode timer, idle mode system timer is initialized. After that, a MOB_PAG-ADV message (action code = '0b01') indicating a location update is periodically transmitted.

All of the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

1 is a block diagram showing elements of a terminal.

2 shows an example of a frame structure.

3 shows an example of a paging group.

4 is a flowchart illustrating an example of an idle mode terminal operation.

5 illustrates an example of a method of performing periodic location update.

6 is a flowchart illustrating a method of performing a location update according to an embodiment of the present invention.

7 is a flowchart illustrating a location update process through dedicated ranging.

8 is a flowchart illustrating a method of performing a location update according to another embodiment of the present invention.

9 illustrates an example of an idle mode terminal operation.

10 shows another example of an idle mode terminal operation.

Claims (9)

In the method of performing a location update in a wireless communication system, Transmitting a request message requesting to periodically transmit a paging message instructing to perform a location update; And Periodically receiving the paging message in an idle mode. 2. The method of claim 1, further comprising receiving a response message that includes a transmission period of the paging message. The method of claim 1, wherein the request message is a Deregistration-Request (DREG-REQ) message. 2. The method of claim 1, wherein the paging message includes a dedicated code for location update. 5. The method of claim 4, further comprising transmitting a location update stop message requesting to stop the periodic transmission of the paging message using the dedicated code. 6. The method of claim 5, wherein the location update stop message is a ranging-request (RNG-REQ) message. 6. The method of claim 5, further comprising receiving a location update response message including whether to accept the request to stop the location update message. In the method of performing a location update in a wireless communication system, Receiving a request message requesting to periodically transmit a paging message instructing to perform a location update; And Periodically transmitting the paging message. The method of claim 8, wherein the paging message is transmitted before the timer of the paging controller storing information of the terminal expires and the information of the terminal is deleted.

Images