KR20050089625A - Broadband wireless communication system and method for supporting idle state - Google Patents

Abstract

The present invention provides a broadband wireless communication system comprising: a plurality of base stations for broadcasting a call message to a cell which is an area managed by the mobile station; And a location information management device that manages location information of the mobile terminal and transitions to an idle state for receiving a call message.

Description

Broadband Communication System and Method for Supporting Idle State

The present invention relates to a broadband wireless access communication system and method, and more particularly, to a system and method for supporting handoff and paging of an idle mobile terminal.

The IEEE 802.16 working group, a standardization group related to broadband wireless access communication, has created 802.16, 802.16a, and 802.16b for high-speed wireless Internet services, and are currently creating 802.16d and 802.16e. The 802.16d is a standard integrating the previously prepared standards of 802.16, 802.16a, and 802.16b into one, and aims to provide wireless Internet services to fixed terminals, and 802.16e is a standard aiming to improve mobility of 802.16d. Currently, the 802.16d standard supports hard handoff at a level that supports no-medical mobility.

Then, a process of performing handoff by the terminal in the 802.16e standard will be described with reference to FIG. 1.

Referring to FIG. 1, the mobile terminal 100 leaves the area 111 managed by the first base station 101 and enters the area 112 managed by the second base station 102. The handoff message is exchanged with the 101 and the second base station 102. Then, when the terminal 100 continues to move from the area 111 managed by the first base station 101 to the area 113 managed by the third base station 103, the terminal 100 may proceed to step 121 and step 122. At least two handoffs are taken.

2 is a signal flowchart illustrating a handoff process by a request of a terminal 100 in the 802.16e standard. Here, the terminal 100 is in a state of being connected to the first base station 101.

Referring to FIG. 2, the terminal 100 examines base stations 101, 102, 103 around the terminal in step 200, and then transmits a handoff request message to the serving base station 101 that is already connected in step 205. . The serving base station 101 receiving the handoff request message transmits a handoff message to the handoff candidate base stations 102 and 103 in steps 210 and 215. Then, the base stations 102 and 103 that have received the handoff message transmit the handoff response message to the serving base station 201 in steps 220 and 225, respectively. The serving base station 101 selects the final target base station in step 230 and transmits a handoff notification confirmation message to the corresponding base station. In FIG. 2, the serving base station 101 is selected as the target base station. In addition, the serving base station 101 transmits a terminal handoff response message to the terminal 100 in step 235. In step 240, the terminal 100 receives the terminal handoff indication message to the serving base station 101. Then, the serving base station 101 releases the call with the terminal 245 in step 245. The target base station 103 transmits the fast distance measurement information element in step 250, and the terminal 100 transmits a distance measurement request message to the target base station 103 in step 255. The target base station 103 transmits the distance measurement response message to the terminal 100 in step 260 in response to the distance measurement request message, and completes the initial connection with the terminal 100 in step 265.

However, since many overhead messages are generated in the handoff process illustrated in FIG. 2, when the terminal 100 is changed from the region of the first base station 101 to the region 103 of the third base station as described above. Increasing the number of messages in In addition, since the handoff process is performed regardless of whether the terminal receives data, there are a lot of terminals connected to the network, and if a large number of terminals move, there is a problem that a large load is placed on the base station and the access network.

Accordingly, an object of the present invention for solving the above problems is to provide a handoff system and method by a mobile terminal in the idle state to reduce the load of the access network generated during handoff.

Another object of the present invention is to provide a system and method for efficiently transmitting the data packet by efficiently calling an idle terminal when there is a data packet destined for the idle terminal.

Embodiment of the present invention for achieving the above object is a method for changing from an active state to an idle state in a broadband wireless communication system, the data communication is a certain time in the active state in which a specific base station resources are allocated to the mobile terminal Or a second process of releasing a specific base station resource allocated to the mobile station and transitioning to an idle state if it is determined that data communication will not occur within a certain time later. It features.

Another embodiment of the present invention for achieving the above object is, in a broadband wireless communication system, a plurality of base stations for broadcasting a call message to a cell that is managed by the cell, and the active state or the specific base station resources are allocated And a mobile station that transitions to an idle state in which a specific base station resource is released and periodically receives the call message from the base station, and a location information management device that manages location information of the mobile station.

Another embodiment of the present invention for achieving the above object is a handoff of a mobile terminal in an idle state in a broadband wireless communication system comprising a base station supporting an idle state and a location management device for managing the location of the mobile terminal. A method comprising: a first process of determining whether a call message is received from a base station at a predetermined call cycle after transitioning to an idle state; and if the call message is not received from the base station, the neighboring base stations are examined and examined from the neighbor base stations. And a second process of receiving a call message and handing it off.

Another embodiment of the present invention for achieving the above object is to call a mobile terminal in the idle state in a broadband wireless communication system comprising a base station supporting an idle state and a location management device for managing the location of the mobile terminal; 1. A method, comprising: a first process of a location management device searching for a location of a specific mobile terminal according to a call request of a specific mobile terminal from an external source, and a call message to the specific mobile terminal through a base station located around the specific mobile terminal; And a second process of transmitting.

Hereinafter, the detailed operation and structure of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that reference numerals and like elements among the drawings are denoted by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The present invention proposes a system and method for supporting an idle state of a terminal to minimize the wireless transmission of the terminal in order to reduce the system load due to frequent handoff of the mobile terminal in the broadband wireless access network.

The present invention also proposes a handoff method of a mobile terminal in an idle state and a call method to the mobile terminal in the idle state in a broadband wireless communication system supporting the idle state of the mobile terminal.

Then, as described above, a broadband wireless communication system supporting an idle state of a mobile terminal according to an exemplary embodiment of the present invention will be described with reference to FIGS. 3A and 3B.

Referring to FIG. 3A, a plurality of base stations located in a cell managed by the cell are illustrated, and the predetermined cells are gathered to form one zone 310. The mobile terminal 300 can communicate with the base stations, and a hard handoff is performed to change the base station serving the mobile terminal as the mobile terminal moves between cells.

A location management device (SCMM) 350 communicates with each of the base stations, manages the location of the terminal by receiving a location registration message sent by the mobile terminal 100 to the base station, and transmits a packet to the mobile terminal. It informs the location of the mobile terminal when it arrives.

In addition, the base station and the mobile terminal can support the idle state, Figure 3b is a diagram illustrating a state machine to add the idle state (Idle State) proposed by the present invention to the existing 802.16e state machine.

First, referring to FIG. 3B, the operation state of the existing 802.16e is indicated by an active state 410, and the active state includes a sleep form 411 and an awakening form 412. The behavior in each sleep mode and wakefulness form follows the existing 802.16e definition. The change from active state to idle state 401 or from idle state to active state 402 consists of the occurrence of a Status Change Event.

In the active state 410, the terminal is allocated the base station resources and data communication is possible immediately, whereas the idle state 420 is a state in which the base station resources allocated to the terminal are released and do not transmit and receive data messages and wake up periodically. Receives only broadcast messages sent by the base station. The wake-up cycle is defined as a call cycle, and the call cycle is determined by the terminal and informs the base station. The terminal sends a response message to the base station when the terminal receives a call broadcast message.

The idle state has two types of cell registration type 421 and zone registration type 422 according to the location registration method of the terminal. In the case of the cell registration form 421, a registration process is performed whenever a cell to which a terminal belongs is changed, and in the case of the zone registration form 422, a registration process is performed whenever a paging zone to which a terminal belongs is changed. Perform. The UE determines the cell registration type and the zone registration type by itself and basically performs the zone registration type. If the cell registration type is selected, the call speed can be improved and the call load can be reduced. However, the registration load is increased when there is much movement.

In addition, when an active event 402 occurs in response to a call from a base station in an idle state 420, it transitions to an active state 410.

The present invention proposes three embodiments of a method of changing to an idle state, a handoff method of an idle mobile terminal, and a paging method to an idle mobile terminal in a system supporting the idle state of the mobile terminal as described above. do.

First, a method of changing to an idle state according to a preferred embodiment of the present invention will be described with reference to FIG. 4. 4 is a flowchart illustrating an operation of a mobile terminal or a base station for explaining a method of changing to an idle state in a broadband communication system.

Referring to FIG. 4, an idle event 401 illustrated in FIG. 3B occurs in an activated state in which a specific base station is allocated a resource to a mobile terminal in step 40 as follows. That is, it is expected that there will be no data communication for a long time, or the mobile terminal or the base station requests to change to the idle state at any time.

The mobile terminal transmits an idle request message to the base station in order to switch to the idle state at the request of the mobile terminal. 5 illustrates an idle request message transmitted to a base station by a mobile terminal requesting to switch to an idle state. Referring to FIG. 5, a management message type number is determined in the future, and a transaction number is sequentially assigned by the sender.

On the contrary, the base station transmits an idle request message to the base station in order to switch to the idle state at the request of the base station. 6 illustrates a message transmitted to a mobile terminal by a base station requesting to switch to an idle state. The message shown in FIG. 6 has the same function as the message shown in FIG.

Therefore, in step 41 of FIG. 4, the base station or the mobile terminal anticipates whether data communication will occur within a predetermined time or determines whether an idle state change request message has been received. As a result of the determination of step 41, when no data communication is expected for a long time or an idle state change request message is received, the mobile station and the base station switch to the idle state through the protocol in step 42.

In FIG. 4, the mobile terminal sends the registration request message of FIG. 7 to the base station one or more times before or after switching to the idle state. The period and location should be reported to the base station, and the base station should send the information to the mobility management device 350 and share it with other base stations.

Next, a second handoff method of the mobile terminal in the idle state according to the preferred embodiment of the present invention will be described with reference to FIG. In the following, it is assumed that the mobile terminal registers a location in accordance with the zone change.

Referring to FIG. 10, in operation 500, the mobile terminal transitions to an idle state, and in operation 510, an internal timer is operated to check whether a call cycle has arrived.

In the call period, the terminal transmits the distance measurement and registration request message of FIG. 7 to the base station, registers it with the mobile management apparatus, and is shared by all base stations. The call time is determined by Equation 1 below.

Call time = Hash_Function (Terminal ID) + K * Call period (K is an integer)

As a result of the check in step 510, when the call period arrives, the mobile terminal checks whether a call message is received from the base station of the cell where the mobile terminal is located before the call period expires in step 520. If the call message is not received as a result of the check in step 520, the mobile station searches for neighbor base stations and updates the list of neighbor base stations in step 530. In operation 540, the call message is received from the examined neighbor BSs.

However, when the check message is received in step 520, the mobile terminal checks whether the terminal ID is included in the call message in step 550. The call message shown in FIG. 9 includes a terminal ID.

As a result of the check in step 550, if the call message includes the ID of the mobile terminal, it is determined that there is a call request to the mobile terminal, and the mobile terminal performs the call operation in step 560. It will be described in detail in the method of invoking.

On the other hand, if the check message in step 550 does not include the ID of the mobile terminal in the call message, the mobile terminal in step 570 the call message is a call message transmitted by the base station located in the zone where the mobile terminal was previously located It will be judged. That is, it is determined whether the mobile terminal has moved by changing the zone. This is to register the location of the mobile terminal according to the zone change since the mobile terminal is in the zone registration form. If the mobile terminal is a cell registration type instead of the zone registration type, step 570 is omitted, and the mobile terminal always performs a location registration process when handing off.

As a result of the determination in step 570, if the zone is not changed, the mobile terminal returns to the idle state in step 500. However, if the zone is changed as a result of the determination in step 570, the mobile terminal transmits a location registration request message to the base station in step 580, so that the location of the mobile terminal is registered in the location management apparatus.

After transmitting the location registration request message, the mobile station determines whether a location registration response message is received from the base station in step 590. As a result of the determination in step 590, if the location registration response message is not received, the mobile terminal returns to step 580 and retransmits the location registration request message. If the distance measurement and registration response message is not received or an error occurs, the terminal repeatedly transmits the distance measurement and registration request message.

However, if the location registration response message is received as a result of the determination in step 590, the mobile terminal returns to step 500 is switched to the idle state.

Then, the handoff process as the mobile terminal moves to the area of the base station belonging to the same zone, and the handoff process as the mobile terminal leaves the zone to which the serving base station belongs as described above. An example of the process will be described.

FIG. 11 is a diagram illustrating an idle handoff process without a registration process as a mobile terminal moves to an area of base stations 311, 312, and 313 belonging to the same zone 310.

Referring to FIG. 11, when the idle state terminal 300 is in the idle state in step 600 and the preset call period arrives in step 610, the idle state terminal 300 wakes up from the idle state and receives a call message from the base station 311 in which the current mobile terminal is located. do. In this case, the received call message does not include the ID of the terminal. Thus, the mobile terminal remains idle until the next call period.

However, in step 620, the mobile terminal is out of the communication range of the base station 311. Then, the mobile terminal does not receive the call message transmitted by the base station 311 even when the mobile station wakes up in step 630. Therefore, in step 640, the mobile terminal searches for the neighbor base station and collects information on the neighbor base station. In step 650, the mobile terminal receives a call message from the examined neighbor base station 312. Since the call message is a base station located in the same zone as the previously located base station 311, the mobile terminal does not perform a location registration process and transitions to an idle state. If the mobile terminal moves to the cell of the base station 313 again in step 660, the mobile terminal receives a call message from the base station 313 in step 670 with reference to the information examined in step 640.

12 is a diagram illustrating an idle handoff process including a registration process when the mobile terminal leaves the zone 310 to which the base station 311 to which the mobile station was previously located belongs.

Referring to FIG. 12, as in FIG. 11, the mobile terminal 300, which is in an idle state at step 700, wakes up every call period and receives a call message from the base station 311 at step 710. The call message here does not include the mobile terminal ID. The mobile terminal transitions back to the idle state, and in step 720, the mobile terminal moves out of the paging zone A 310 where the base station 311 is located and moves to the paging zone 320 where the base station 321 is located. Then, even if the mobile terminal wakes up again in step 730 in the next call period, the mobile station does not receive the call message from the base station 311 until the call period expires. In step 740, the mobile station searches for the neighbor base station and updates the neighbor base station list. In operation 750, the mobile terminal receives a call message from the base station 321 included in the neighbor base station list. Since the call message is a call message transmitted from a base station located in another zone, the mobile station transmits a distance measurement and registration request message to the base station 321 in step 760, and informs the location of the mobile terminal. Registers the location of the terminal in the location management device 350 to share the location of the mobile terminal 300 with other base stations. The base station 321 transmits a distance measurement and registration response message in step 780 to inform the mobile terminal 300 that the location of the mobile terminal 300 has been registered. Then, the mobile terminal 300 returns to the idle state in step 790 after receiving the response message.

Finally, a method of calling a mobile terminal in an idle state according to an exemplary embodiment of the present invention will be described with reference to FIG. 13.

Referring to FIG. 13, since the mobile terminal 300 does not receive data in the idle state and wakes up every call cycle, and receives data, the base station should deliver a call message according to the call cycle of the terminal in order to call the mobile terminal in the idle state. do.

When the idle state terminal 300 is called, since the location of the terminal is stored in the location management apparatus 350, the terminal call request message is transmitted to the location management apparatus 350 in step 800. The location management apparatus 350 that receives the call request message determines the location of the idle state terminal 300, and thus, in step 810 and 820, the base station 311 which belongs to the call area 310 in which the terminal is expected to be located. Send a paging message to 312). The base stations 311 and 312 receiving the call message from the location management apparatus 350 wait until the mobile terminal wakes up in step 830 in consideration of the call cycle of the mobile terminal 300. When the mobile terminal wakes up, the base stations 311 and 312 call the idle terminal by broadcasting a call message. In FIG. 13, it is assumed that the idle state terminal 300 is located in the base station 2 312, and the mobile terminal does not receive the call message 608 sent from the base station 1 601 and the call message 609 sent from the base station 2 602. Will receive. The transmitted call message includes the ID of the terminal as shown in FIG. 9. The mobile terminal 300 receiving the call message transitions from the idle state to the active state, and performs an access procedure starting with transmitting the distance measurement request message with the base station 312 in step 850. The base station 2 312 confirms that the mobile terminal 100 is activated, updates the location of the terminal to the location management apparatus 860 in step 860, and informs that the called terminal 300 is activated.

As described above, the present invention has proposed a method of reducing a system load due to handoff occurring when a mobile station is added by adding an idle state in a broadband wireless access technology, and has the following effects.

First, when the idle terminal is moved, the terminal can move without sending a handoff message, thereby reducing power consumption of the terminal and reducing the load on the base station.

Secondly, the location registration process message and the distance measurement message are integrated to reduce unnecessary message use and to perform the location registration process quickly.

Third, when the terminal is in the zone registration form, it is possible to reduce the number of location registration and network load by location registration per call area. When the terminal uses the cell registration form, the coverage area is reduced from a plurality of base stations to one base station, thereby reducing the load on the network when calling an idle terminal.

Fourth, when the terminal is changed to the idle state, it is possible to release the base station resources allocated to the terminal to efficiently use the resources.

Sixth, the terminal can register the call cycle using the exponential power notation to register both a very long call cycle and a very short call cycle can register the desired call cycle according to the state of the terminal.

Seventh, by calculating the call time of the idle terminal in the manner of all the base station can calculate the call time only by the ID and the call period of the terminal, eliminating the phenomenon that the call times of a plurality of terminals are driven to one side.

1 is a view for explaining a process of the terminal performs a handoff in the 802.16e standard,

2 is a signal flow diagram illustrating a handoff process by a request of a terminal in the 802.16e standard;

3A is a diagram illustrating a system for supporting an idle state according to a preferred embodiment of the present invention;

3B is a view for explaining a state change of a system according to an embodiment of the present invention;

4 is a flowchart illustrating a method for switching from an active state to an idle state according to a preferred embodiment of the present invention;

5 is a diagram illustrating an idle request message according to a preferred embodiment of the present invention;

6 illustrates an idle response message according to an embodiment of the present invention.

7 is a diagram illustrating a distance measurement and registration request message according to an embodiment of the present invention;

8 is a diagram illustrating a distance measurement and registration response message according to an embodiment of the present invention;

9 is a view showing a call message according to an embodiment of the present invention;

10 is a signal flow diagram illustrating a handoff operation of an idle mobile terminal according to an embodiment of the present invention;

11 illustrates an idle handoff process without a registration process according to an embodiment of the present invention;

12 illustrates an idle handoff process with a registration process according to an embodiment of the present invention;

13 is a signal flow diagram illustrating a method of calling a mobile terminal in an idle state according to a preferred embodiment of the present invention.

Claims (16)

A method for changing from an active state to an idle state in a broadband wireless communication system, A first process of determining whether data communication is generated between a mobile station and a base station within a predetermined time in an active state in which a specific base station resource is allocated to the mobile station; If it is determined that data communication will not occur within a certain time later, the method comprises releasing a specific base station resource allocated to the mobile terminal and transitioning to an idle state. The method of claim 1, The mobile management device managing a location of the mobile terminal through the specific base station, a registration request message including a call period and its location information, which is a time interval in which the mobile terminal can receive a call message from the base station in an idle state. The method further comprises the step of transmitting. The method of claim 1, And transitioning to an idle state at the request of the mobile terminal or the base station. In a broadband wireless communication system, A plurality of base stations for broadcasting a call message to a cell which is an area managed by the mobile station; A mobile terminal transitioning to an idle state in which an active state allocated to a specific base station resource or a specific base station resource is released and periodically receives the call message from the base station; And a location information management device for managing location information of the mobile terminal. The method of claim 4, wherein the mobile terminal And transmitting a registration request message including a call period, which is a time interval for receiving a call message from the base station and its location information in an idle state, to the mobile management device managing the location of the mobile terminal through the specific base station. The system described above. The method of claim 4, wherein the mobile terminal And after the transition to the idle state, if no call message is received in a predetermined call period, the call message is received from a neighboring base station and handed off. The method of claim 4, wherein the mobile terminal The cell according to claim 1, wherein, as the cell in which the cell is located is changed, the cell is registered with the location management apparatus through the base station. The method of claim 4, wherein the mobile terminal Examine the incoming call message to determine whether the user has moved by changing a zone, which is a set of divided cells according to a predetermined criterion, and when the zone is changed, registers its location with the location management device through the base station. Said system, characterized in that. The apparatus of claim 4, wherein the location management device is The system of claim 1, wherein the location of the mobile terminal is tracked and the mobile terminal is called. The method of claim 4, wherein the mobile terminal If the call message includes the ID of the mobile terminal, the system characterized in that the transition to the active state. A handoff method of a mobile terminal in an idle state in a broadband wireless communication system including a base station supporting an idle state and a location management device managing a location of the mobile terminal, A first process of determining whether a call message is received from the base station at a predetermined call period after the transition to the idle state; And if the call message is not received from the base station, a second process of examining the neighbor base station and receiving a call message from the neighbor base stations and handing it off. The method of claim 11, And registering the own location with the location management device through the base station as the cell of the own location is changed. The method of claim 11, Examine the incoming call message to determine whether the user has moved by changing a zone, which is a set of divided cells according to a predetermined criterion, and when the zone is changed, registers its location with the location management device through the base station. The method further comprises a process. A method of calling an idle mobile terminal in a broadband wireless communication system including a base station supporting an idle state and a location management device managing a location of the mobile terminal, A first process of searching for a location of a specific mobile terminal by a location management apparatus according to a call request of a specific mobile terminal from the outside, And a second process of transmitting a call message to the specific mobile terminal through a base station located around the specific mobile terminal.  The method of claim 14, wherein the second process The base station receiving the call message transmits the call message in a call cycle of the specific mobile terminal. 15. The method of claim 14, wherein the call message The method of claim 1, wherein the ID of the mobile terminal is included.