KR20060016720A - Method and system for fragmenting broadcast message in broadband wireless access system - Google Patents

Abstract

The present invention provides a wireless broadband Internet service to a mobile terminal, and in the broadband wireless access system comprising a base station for transmitting the information of neighbor base stations for handoff support of the mobile terminal to the mobile terminal, A method of dividing a broadcast message including information of neighbor base stations, the method comprising: searching for information of the neighbor base stations to be transmitted to the mobile terminal, and checking whether the amount of information of the searched neighbor base stations exceeds a preset frame size; And if the amount of information of the neighbor base stations exceeds the frame size, dividing the broadcast message including the information of the neighbor base stations, and setting a field related to the information of neighbor base stations of the divided broadcast message. Preset the set broadcast message to the mobile terminal It characterized in that it comprises a process of transmitting at a predetermined cycle.

Broadband wireless access system, broadcast message partitioning, neighbor base station information, handoff, MOB_NBR_ADV.

Description

Method and system for fragmentation broadcast message in broadband wireless access system             

1 is a diagram illustrating cells configured by base stations supporting different operating modes in a typical broadband wireless access system.

2 is a diagram illustrating a set of neighbor base stations divided by a current divided message number and a total number of divided messages according to a preferred embodiment of the present invention;

3 is a diagram illustrating segmentation of a broadcast message in a broadband wireless access system according to an embodiment of the present invention;

4 is a flowchart illustrating a splitting operation of a broadcast message including neighboring base station information according to a preferred embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadband wireless access system, and more particularly, to a broadcast message segmentation method and system for informing a mobile station of neighbor base station information in a mobile broadband wireless access system.

In general, communication systems have been developed mainly for voice services, and are gradually developing as communication systems capable of not only voice but also data services and various multimedia services. However, since the voice-oriented communication system has a relatively small data transmission bandwidth and a high usage fee, the voice-oriented communication system cannot meet the rapidly increasing demand for users. In addition, due to the development of the communication industry and increasing user demand for Internet services, there is an increasing need for a communication system that can efficiently provide Internet services. As a result, broadband wireless access systems have been introduced to efficiently provide Internet services with broadband enough to meet the increasing demands of users.

The broadband wireless access system is a system for integrating and supporting not only voice but also various low speed and high speed data services and multimedia application services such as high definition video. The broadband wireless access system can access PSTN and PSDN networks, Internet networks, IMT-2000 networks, ATM networks, etc. in a mobile or fixed environment based on wireless media using broadband such as 2 GHz, 5 GHz, 26 GHz and 60 GHz. It is a wireless communication system that can support more than a channel rate. The broadband wireless access system may be classified into a broadband wireless subscriber network, a broadband mobile access network, and a high-speed wireless LAN according to the mobility (fixed or mobile) and communication environment (indoor or outdoor) of a terminal, and a channel rate.

The wireless access method of the broadband wireless access system is being standardized by the IEEE 802.16 standardization group of the Institute of Electrical and Electronics Engineers, one of the international standardization organizations, and is currently providing wireless broadband Internet service to fixed terminals. The IEEE 802.16d standard is being promoted as a standard.

The IEEE 802.16d standard has a wider bandwidth of data than a conventional radio technology for voice service, and can perform a lot of data transmission in a short time, and it is possible to efficiently use a channel by sharing all user channels. In addition, quality of service (QoS) is guaranteed so that users can receive different quality of services according to the characteristics of the service. In the IEEE 802.16d system, all users connected to a base station share a common channel, and each user uses a channel, and an interval for each user is allocated by the base station every uplink and downlink frame. Uplink and downlink access information should be informed so that it can be used separately. In the IEEE 802.16d system, channel information is divided into an uplink channel and a downlink channel, and information about each channel is defined as a TLV (Type, Length, Value) and included in a downlink channel descriptor (DCD) and an uplink channel descriptor (UCD) message. By transmitting the information to all the users to inform the terminal of the characteristic information on the channel.

In addition, the IEEE 802.16 standardization group is in the process of standardizing 802.16e, which adds mobility to IEEE 802.16d. The IEEE 802.16e standard has a wider bandwidth of data than a conventional wireless technology for voice service, and can transmit a lot of data in a short time, and it is possible for all users to share a channel and efficiently use the channel. In addition, the quality of service (QoS) is guaranteed so that the user can be provided with different quality of services according to the characteristics of the service, and the mobility of the mobile terminal is guaranteed with the support of handoff.

In the IEEE 802.16e system, in order to support handoff of a mobile terminal, the base station periodically broadcasts a mobile neighbor advertisement (MOB-NBR-ADV) message to all mobile terminals in its cell to provide status information of neighbor cells. You will be notified in advance. That is, when a mobile terminal in one cell moves to an adjacent cell, the mobile terminal can support handoff since the mobile terminal already has base station information of neighbor cells such as a network ID and channel characteristics broadcasted from the base station in advance.

However, in the IEEE 802.16e system, when the base station has a large number of neighbor cells or the capability of the neighbor cells is significantly different from a cell currently being served, the amount of neighbor base station information to be transmitted to the mobile terminal becomes very large. Therefore, since all information cannot be delivered in one frame, all neighbor base station information cannot be broadcast to the mobile terminal. In addition, the IEEE 802.16e / D4 has a problem that the MAC management message (fragmentation) can not be transmitted by fragmentation.

Accordingly, an object of the present invention is to provide a method and system for dividing a broadcast message for notifying a mobile terminal in a mobile broadband wireless access system.

Another object of the present invention is to provide a method and system for dividing a broadcast message including neighboring base station information having a large size by adding a specific value to a MOB_NBR_ADV message which is a broadcast message in a mobile broadband wireless access system.

A method for achieving the objects of the present invention is a broadband wireless network including a base station for providing a wireless broadband Internet service to a mobile terminal and transmitting information of neighbor base stations for handoff support of the mobile terminal to the mobile terminal. In the access system, the base station divides the broadcast message including the information of the neighboring base station, the process of retrieving the information of the neighboring base stations to be transmitted to the mobile terminal, and the amount of the information of the searched neighboring base stations is preset Checking whether the frame size exceeds the frame size, and when the amount of the neighbor base station information exceeds the frame size, dividing the broadcast message including the information of the neighbor base stations, Set a field related to information to transfer to the mobile terminal. It characterized by comprising the step of transmitting a predetermined broadcast message in advance set intervals.

In addition, a system for achieving the objects of the present invention, a broadband including a base station for providing a wireless broadband Internet service to a mobile terminal and transmitting information of neighbor base stations for handoff support of the mobile terminal to the mobile terminal; A system for dividing a broadcast message including information of neighboring base stations in a wireless access system, wherein if the amount of information of neighboring base stations exceeds and exceeds a preset frame size, the system includes information of the neighboring base stations; Receiving a broadcast message in a predetermined period and the base station for dividing a broadcast message, and setting a field related to the information of the neighbor base stations of the divided broadcast message in a predetermined period, and includes in the received broadcast message The adjacent base station Check the fields relating to the information it characterized in that it comprises the mobile station to determine whether or not the divided message.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying 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 to be described later is applied to the IEEE 802.16e system with added mobility, in the embodiment of the present invention to broadcast the broadcast message including the neighbor base station information having a large size to inform the mobile station of the neighbor base station information in the IEEE 802.16e A method and system for dividing and transmitting will be described. In addition, a broadcast message including neighboring base station information will be described as a mobile neighbor advertisement (hereinafter referred to as MOB-NBR-ADV) message in which the base station periodically broadcasts the mobile terminal to inform the status information of the neighboring cell. do.

1 is a diagram illustrating cells configured by base stations supporting different operating modes in a typical broadband wireless access system.

Referring to FIG. 1, a broadband wireless access system includes a mobile terminal 10 and a plurality of base stations 20a, 20b,..., 20g supporting different operating modes, and the plurality of base stations 20a, 20b, ..., 20g) each form a cell. Here, it can be seen that the mobile terminal 10 moves from the base station 20a to the base station 20b.

The mobile terminal 10 receives the MOB-NBR-ADV message to which the base station operation information of the neighbor cell broadcasted by the base station 20a currently being serviced is added. In addition, since the mobile station 10 has already received the neighboring device station information through the MOB-NBR-ADV message, if the mobile station 10 receives only the channel information of the base station 20b, the mobile terminal 10 immediately proceeds to establish a connection with the base station 20b.

In the broadband wireless access system having such a structure, the base station indicates the MOB-NBR-ADV message format for transmitting the neighbor base station information to the mobile terminal, as shown in Table 1 below.

In Table 1, the MOB-NBR-ADV message includes an 8-bit Management Message Type (49) field, an Operator ID field allocated for 24-bit operation, and an 8-bit neighbor base station. It includes the number of (hereinafter referred to as N_NEIGHBORS) field, the 21-bit 'HMAC Tuple' field, and information of all neighboring base stations together. The MOB-NBR-ADV message adds an 8-bit neighbor set field of neighbor base stations.

The Neighbor Set field of the neighbor BSs is divided into 4 bits of current fragment index information and 4 bits of Neighbor Set-Total information. This newly added information is as shown in FIG. 2.

The N_NEIGHBORS field includes a 32-bit downlink physical frequency, a configuration change count field for the 8-bit broadcast message, and a variable-bit TLV-encoded neighbor base station field (TLV Encoded Neighbor). information).

In a broadband wireless access system according to another embodiment of the present invention, the MOB-NBR-ADV message format for transmitting a base station information to a mobile station by a base station is shown in Table 2 below.                     

In Table 2, the MOB-NBR-ADV message includes an 8-bit Management Message Type (49) field, an Operator ID field allocated for 24-bit operation, and the 8-bit broadcast. Contains a Change Change Count field for the message.

The message may be divided and transmitted when the size of the message does not transmit all contents at once. The message transmitted during the split transmission of the message should indicate that the message has been split, and when the mobile terminal receives the split message, it must receive all the remaining messages to receive all neighbor base station information.

The following fields are needed to indicate that the message is to be sent partially.

In addition, the MOB-NBR-ADV message includes a 1-bit fragmentation mode field, a field indicating the total number of 7-bit neighbor base stations (TOT_N_NEIGHBORS), a 1-bit start bit field, and a 6-bit field. Contains a field indicating the number of fragmented messages remaining (Number of Remaining Fragments).

The message may indicate that the message is divided into two types. The split mode field indicates how the split of the message is indicated. The split mode field is set to '1' when the message segmentation is expressed by the total number of base stations, and is set to '0' when representing the number of fragmented message fragments.

When the split mode field is set to '1', "TOT_N_NEIGHBORS" represents the total number of neighboring base stations to which the base station intends to broadcast, and "N_Neighbors" represents the number of base station information transmitted due to the split message. If the number of information transmitted in the divided message is smaller than the total number of base stations, the mobile terminal should continue to receive the divided message to obtain the remaining base station information.

When the split mode field is set to '0', 'start bit' indicates transmission of the first split message and is set to '1' when the first split message is transmitted. It is set to '0' when transmitting the remaining split message. The "REMAINING FRAGMENTS" field indicates the number of remaining fragmented messages that the mobile terminal should receive.

In addition, the MOB-NBR-ADV message includes an N_NEIGHBORS field of 8 bits, a TLV encoded neighbor information field of variable bits, a DCD change count field for an 8-bit broadcast message, A UCD change count field for an 8-bit broadcast message, a length field indicating a length of 8 bits, a field indicating a neighbor BS-ID of 48 bits, and a preamble index field of 8 bits Include.

As described above, a method of dividing the MOB-NBR-ADV message including the neighbor base station information, that is, the broadcast message through the information of the newly defined MOB-NBR-ADV message will be described.

3 is a diagram illustrating the division of a broadcast message in a broadband wireless access system according to a preferred embodiment of the present invention.

Referring to FIG. 3, block 310 exceeds one frame of a predetermined size as the number of neighboring base stations increases. These messages are partitioned due to the difficulty in transmitting frames. That is, the block 320 is divided into a block 330.

Block 320 includes a message identification number (ID) and " Tuple " identical to the message type included in block 310, and includes a set of neighbor base stations separated by a number and a total number; It includes information 1-6 of some neighboring base stations among the information of neighboring base stations of the block 320.

 Block 330 includes a message type (type) and a message identification number and "Tuple" like the block 320, the set of neighbor base stations and the remaining neighbor base station information (17 ~ ~) divided by the number and the total number 24).

The base station includes the number of messages to be divided according to the size of the frame to be transmitted in the "Neighbor Set-Total", and includes the divided current message number in the "Neighbor Set-Index", and then divides and transmits neighboring base station information. Accordingly, the MOB_NBR-ADV message can be transmitted several times in one frame.

A splitting operation of a broadcast message including such neighbor base station information will be described with reference to the accompanying drawings.

4 is a flowchart illustrating a splitting operation of a broadcast message including neighboring base station information according to a preferred embodiment of the present invention.

Referring to FIG. 4, in step 401, the base station searches for information of neighbor base stations to be transmitted to the mobile terminal, and in step 403, the base station determines whether the amount of information of neighbor base stations that is found is greater than the size of a preset frame. In this case, when the neighboring device stations information is not larger than the frame size, the base station includes the searched neighboring base station information in the broadcast message (MOB-NBR-ADV) and transmits the information to the mobile terminal as it is. Otherwise, in step 405, the base station divides the broadcast message (MOB-NBR-ADV) including the information of the neighbor base stations into a size within a frame size.

In step 407, the base station sets the newly added neighbor base station set field to a corresponding value. That is, if a message including neighboring base station information is divided into two, for example, the total number of divided messages (Neighbor Set_Total) of two messages has a common value with a binary value of 0010, and the value of the current divided message of the first message. The number (Neighbor Set_Index) value is set to 0001, and the number (Neighbor Set_Index) value of the currently divided message of the second message is set to 0010. Then, in step 409, the base station transmits the set broadcast message (MOB-NBR-ADV) to the mobile terminal at a predetermined cycle.

The mobile terminal receiving the broadcast message (MOB-NBR-ADV) at a predetermined cycle checks a field related to neighbor base station information included in the broadcast message, that is, the total number of divided messages (Neighbor Set-Total). Check whether the return message is split. That is, if the value of the Neighbor Set-Total field is 0, it means that the message has not been split. If the value of the field is set, the total number of split messages will be received. Wait for the next split message.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention proposes a procedure of dividing a broadcast message for informing a mobile station of a large size of adjacent base station information in a wideband wireless access system. When using the method proposed by the present invention, the broadcast message (MOB-NBR-ADV), which is large in size due to a large number of neighbor base station information, may be broadcast to the mobile terminal through a message division scheme.

Claims (4)

In a broadband wireless access system including a base station for providing a wireless broadband Internet service to a mobile terminal and transmitting the information of neighbor base stations for handoff support of the mobile terminal to the mobile terminal, the base station is the information of the neighbor base stations In the method for dividing a broadcast message comprising: Searching for information of the neighbor base stations to be transmitted to the mobile terminal; Checking whether the amount of the neighboring base stations information found exceeds a preset frame size; When the amount of the neighbor base stations information exceeds the frame size, split the broadcast message including the information of the neighbor base stations, And setting a field related to information of neighboring base stations of the divided broadcast message and transmitting the set broadcast message to the mobile terminal at a predetermined period. The method of claim 1, And a field related to the information of the neighbor base stations is a neighbor base station set field, wherein the neighbor base station set field is divided into numeric information of a currently divided message and numeric information of a currently divided message. In a broadband wireless access system comprising a base station for providing a wireless broadband Internet service to a mobile terminal, and transmitting the information of neighboring base stations for handoff support of the mobile terminal to the mobile terminal, including the information of the neighbor base stations In the system for splitting a broadcast message, If the amount of information of the neighboring base stations exceeds and exceeds the preset frame size, the broadcast message including the information of the neighboring base stations is divided, and a field related to the information of neighboring base stations of the divided broadcast message is set. The base station for transmitting at a predetermined period of time; And a mobile terminal for receiving a broadcast message from the base station at a predetermined period and checking whether a message is divided by checking a field related to information of the neighbor base stations included in the received broadcast message. . The method of claim 1, And a field related to the information of the neighbor base stations is a neighbor base station set field, wherein the neighbor base station set field is divided into numeric information of a currently divided message and numeric information of a currently divided message.

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