KR100990285B1 - Target base station channel determination method using group scan - Google Patents

Abstract

A method of determining a target base station channel is disclosed. A method for determining a target base station channel using a cooperative scan with an adjacent group user, the method comprising: determining whether a terminal needs to search a channel by determining a signal strength of a first received signal from a serving base station, and a signal strength of the first received signal Determining a presence of a participation group and whether to participate in the participation group based on a signal strength of a second received signal from a neighboring group user and an advertisement message from the serving base station; Participating in the participation group to scan a target candidate channel, and if participation in the participation group is not possible, forming an independent group to scan the target candidate channel.

Group Scan, WiBro, Mobile WiMAX, Scan, Target Base Station, Dynamic Neighbor Base Station Channel

Description

Target base station channel determination method using group scan {METHOD FOR TARGET BASE STATION CHANNEL DECISION USING GROUP SCANNING}

The present invention relates to a method for determining a target base station channel using a display group scan, and more particularly, to a method for determining a target base station channel using a cooperative scan with an adjacent group user.

Portable Internet Technology IEEE 802.16e is a broadband wireless communication technology that supports high data rates based on an improved air interface, guarantees user mobility and covers a large area.

The scan procedure defined in the IEEE 802.16e standard allows the neighboring base station channels to be scanned sequentially until the user determines the target base station channel. Since the serving base station of IEEE 802.16e does not manage information about the actual location of the user, the information about neighbor base station channels provided by the serving base station is not related to the user's actual location. Therefore, each time the user attempts to scan for a neighboring base station channel that is not appropriate as a target, the user stays in the scanning process.

Therefore, there is an urgent need for a method for determining a target base station channel in a shorter time and completing a scan procedure.

The present invention provides a group scan method for forming a group among adjacent users and dividing and scanning several neighboring base station channels, thereby determining a target base station channel for discovering a target base station channel in a shorter time by sharing the scan results of each group of users. Provide a method.

The present invention provides a dynamic channel apparatus that manages scan results of all groups belonging to a serving base station for each group within the serving base station, so that all users belonging to the serving base station share the group scan results so that users can quickly reach the target base station. A method of determining a target base station channel for searching for a channel is provided.

In a method of determining a target base station channel according to an embodiment of the present invention, determining whether a channel search is required by a terminal by determining a signal strength of a first received signal from a serving base station, signal strength, and proximity of the first received signal. Determining the presence of a participation group and whether or not to participate in the participation group based on a signal strength of a second received signal from a group user and an advertisement message from the serving base station; And joining the group to scan the target candidate channel, and if it is impossible to participate in the participating group, forming an independent group to scan the target candidate channel.

According to an aspect of the present disclosure, the determining whether the participation is possible may include: when the first received signal is smaller than a preset scan preparation threshold and the second received signal is larger than a preset group participation threshold, the participation. If it is determined that the group can participate, and if the first received signal is smaller than a preset scan start threshold and the second received signal is smaller than a preset group joining threshold, it is determined that participation is impossible. Characterized in that may include.

According to one aspect of the invention, the step of scanning, if it is possible to participate in the participation group, determines whether the participation group has found a target base station channel,

When the target base station channel is found, the target candidate channel is scanned, and when the target base station channel is not found, a scan for discovering the target candidate channel is performed with the existing participants of the participating group. It may include.

In accordance with another aspect of the present invention, there is provided a method for determining a target base station channel. The method comprising: receiving a channel scan schedule request message from a terminal, determining whether the message includes a group ID, and if the message includes a group ID, The terminal may be a group scan participant performing a group scan to discover a target base station channel or a target scan participant performing a scan on a previously found target base station channel according to whether or not a target base station channel is already found in the group. And setting the group scan participant if the group ID is not included in the message.

According to an embodiment of the present invention, by providing a group scan method for forming a group among adjacent users and dividing and scanning several neighboring base station channels, a target base station channel can be created in a shorter time by sharing the scan results of each group of users. A method for determining a target base station channel to discover is provided.

According to an embodiment of the present invention, by providing a dynamic channel device for managing the scan results of all the groups belonging to the serving base station for each group in the serving base station, by sharing the group scan results to all users belonging to the serving base station A method of determining a target base station channel in which users search for a target base station channel more quickly.

Hereinafter, with reference to the contents described in the accompanying drawings will be described in detail an embodiment according to the present invention. However, the present invention is not limited to or limited by the embodiments. Like reference numerals in the drawings denote like elements.

1 is a flowchart illustrating a method of determining a target base station channel according to an embodiment of the present invention.

Referring to FIG. 1, first, in step S110, a signal strength of a first received signal from a serving base station is determined to determine whether a channel search is necessary for a terminal (user). That is, when the size of the first received signal, which is a signal received by the terminal from the serving base station, is smaller than a preset scan ready threshold, it may be determined that the terminal needs to search for another channel, which is greater than or equal to the scan ready threshold. In this case, it may be determined that there is no need for searching for another channel.

In step S120, the presence of a participation group and the participation in the participation group are determined based on the signal strength of the first received signal, the signal strength of the second received signal from the neighboring group user, and the advertisement message from the serving base station. To judge. That is, if it is determined in step S110 that there is a need for searching for another channel, the channel may be searched together with other group users for channel searching. Accordingly, the signal strength of the second received signal, which is a signal received from the user of the neighboring group, and the advertisement message provided by the serving base station are determined to determine that the second received signal can participate in the group if the second received signal is greater than or equal to a preset group participation threshold. can do.

In operation S130, when the participation group can participate, the target group is scanned by participating in the participation group. At this time, if the available group discovers the target base station channel, it participates as a target scan participant and has an opportunity to immediately scan the target base station channel, and if the group has not yet found the target base station channel, as a group scan participant A group scan may be performed to discover a target base station channel with previous group scan participants.

In step S140, if participation in the participation group is impossible, an independent group is formed to scan the target candidate channel. That is, a user who does not find a group that can participate until the received signal strength from the serving base station reaches a scan start threshold may form a new group and perform a group scan to discover a target base station channel.

2 is a diagram illustrating an area of a group based on preset threshold values of a received signal strength according to an embodiment of the present invention.

Referring to FIG. 2, the group region 209 may be determined as a threshold for three received signal strengths of the scan start threshold 206, the scan preparation threshold 207, and the group participation threshold 208. The initial participant A 202 is a user who has not found a group to which he can participate until the received signal strength from the serving base station 201 reaches the scan start threshold 206 and is the first to form a new group. Means user. The user B 203 senses the signal of the user A, which is the reference of the group currently being formed, larger than the group participation threshold 208 when the received signal strength from the serving base station is smaller than the scan ready threshold 207. As a result, the user may recognize that the user can join the group. In addition, other users, including user C, may satisfy the three threshold conditions constituting the group area by subsequent movement, and then join the group formed by the initial participants A and B.

Users who join a group after the initial formation of a group of participants have the opportunity to join the group as a target scan participant and immediately scan the target base station channel if the group discovers the target base station channel, and the group is still If the target base station channel is not found, as a group scan participant, a group scan for discovering the target base station channel may be performed together with the previous group scan participants.

FIG. 3 is a diagram for describing an uplink opportunity of each user in a frame when a serving base station broadcasts an uplink allocation map according to an embodiment of the present invention.

Referring to FIG. 3, the uplink media access method in IEEE 802.16e is based on the OFDMA scheme, and the uplink opportunities allocated to the respective users are subchannel and time (times; timeslot; OFDMA symbol). ) Can be reserved for mapping. The serving base station broadcasts an uplink allocation map to all users at the beginning of each frame period, and each user can transmit its uplink message to the serving base station for a specific period reserved for the uplink allocation map broadcast message. have.

The serving base station according to the present invention may announce a specific part of an uplink allocation map broadcast message for a specific purpose, and all other users except for a user who transmits an uplink message at a specific interval and at the same time are classified into such a notification. By sensing the specific uplink mapping interval, the signal strength of the user transmitting the uplink message during the specific interval can be observed. Therefore, with respect to the group participation threshold, if the serving base station announces the uplink interval of the initial participant, each user may compare the received signal strength with the group participation threshold by observing the signal strength of the initial participant as needed. Can be.

4 is a flowchart illustrating a group forming procedure on the user side according to an embodiment of the present invention.

Referring to FIG. 4, in step S401, it is determined whether a predetermined received signal strength threshold condition (eg, the strength of the first received signal received from the serving base station is smaller than the preset scan ready threshold value) is satisfied. Can be. In step S404, it may be determined whether there is a group that can participate in the advertisement message periodically transmitted by the serving base station. In operation S402, for a user who does not have a group to join, it may be determined whether the strength of the first received signal received from the serving base station is smaller than a preset scan start threshold. In operation S405, when the strength of the first received signal is smaller than the preset scan start threshold, the scan schedule request message in which the group ID is set to Null may be transmitted to the serving base station. In operation S406, a scan schedule response message may be received from the serving base station. In step S407, as an initial participant forming a group, periodic uplink transmission may be performed to provide an opportunity to sense itself to another user under the control of the serving base station. Thereafter, a group may be formed with neighboring users to perform a scan as a group scan participant.

In operation S403, the user who finds a group in which the user can participate may determine whether the strength of the second received signal, which is a signal received from the group scan user, is greater than a preset group participation threshold. In step S408, the user who finds a group that can join the user may transmit a scan schedule request message including the group ID to the serving base station, and in step S409, a response message thereof may be received. In step S410, it may be determined whether the corresponding group has already scanned a channel having a high target potential. If the group has already scanned a highly targeted channel, it is defined as a target scan participant, and if the group has not yet scanned a highly targeted channel, it is defined as a group scan participant. The scan can be performed with other group scan participants in the group.

5 is a flowchart illustrating a group forming procedure in terms of a serving base station according to an embodiment of the present invention.

Referring to FIG. 5, when one or more groups exist, the serving base station scans the scan schedules of the group scan participants in each group so that users outside the group may attempt to sense any group scan participants when necessary. The uplink transmission opportunity in the result report may be periodically included in the neighboring base station advertisement message (MOB_NBR-ADV) or may be periodically announced by defining a separate message.

In step S501, the serving base station may receive a scan schedule request message from the user. In step S502, it may be determined whether the group ID is included in the message. In step S504, if the group ID is not included, the user may be defined as a group scan user and a scan schedule response message may be transmitted. In step S503, the status list of the dynamic neighbor base station channel of the group corresponding to the group ID is checked, and in step S505, it is determined whether the target base station channel of the group which is performing the group scan is found or not, and thus the channel having high target potential in the group You can determine if there is. In step S506, when there is no channel with high target potential in the group, the user may be defined as a group scan participant and a scan schedule response message may be transmitted. In step S507, when there is a channel with high target potential in the group, the user May be defined as a target scan participant and may transmit a scan schedule response message.

6 is a flowchart illustrating a procedure of performing a group scan by group users according to an embodiment of the present invention.

Each user performs the group scan while alternately performing the scan interval and the interleaving interval (601).

Referring to FIG. 6, group scan operations such as serving base station 602 and three initial participants, group 1 603, group 1's later participant 604, and new initial participant group 2 605; The role of the dynamic channel apparatus 606 in the serving base station is shown.

Here, the initial participants 1, 2, and 3 of the group 1 may each be group scan participants who are allocated neighboring base station channels to be scanned from the serving base station so as not to overlap and perform a scan for them. The schedules of the scan intervals and the interleaving intervals of the initial participants may be set differently according to the requirements (data delay, data jitter, etc.) of each service currently being used. Each initial participant transmits a scan result report message for the allocated channels to the serving base station at the end of the scan interval (607), and when the appropriate channel is reported to the target, the received signal strength when scanning the corresponding channel is reported. It may be included in the message (608). The group scan participant may achieve its purpose as a target scan participant by requesting the serving base station a scan schedule message of the target base station channel after the target base station channel of the group is found (609).

In the case of a later participant who wants to perform a group scan by accessing the inside of the area of group 1, if the participating group finds the target base station channel, the channel is preferentially assigned and scanned as the target scan participant (610), and the participating group is still the target base station. If the channel is not found, as a group scan participant, the group may attempt to scan by allocating neighboring base station channels that have not been scanned together with other group scan participants in the group.

If Group 2 is formed, which is a separate new initial participating user without access inside the area of Group 1, the serving base station is operated by the dynamic channel device to operate Group 2 faster and more efficiently for Group 2 based on the scan result reports of Group 1. A channel list may be provided (611), wherein a dynamic channel device that references the dynamic neighbor channel state list of existing groups as a whole provides the neighbor base station channel list in a low-targetable order (612). can do. Here, the details of the operation of the dynamic channel apparatus will be described in detail with reference to FIG. 8 below.

FIG. 7 is a diagram for comparing and explaining a scan time required in an embodiment of the present invention.

Referring to FIG. 7, a comparison between scan times 702, 703, and 704 taken in a group scan 720 by joining a group and a scan time 701 in a single user scan 710 in the IEEE 802.16e standard is described. can do.

In this case, the scan time required to discover a target base station channel through a single user scan in IEEE 802.16e is T _MS 701. When a single user sequentially scans a neighbor base station channel, two scan intervals and After the interleaving interval, the time from the third scan interval (scan attempt for the fourth channel) to the completion of synchronization for the target base station channel. The user waits for reception of the DL-MAP and UL-MAP until T _{21 in the} neighbor base station channel which is not likely to be the target (705). The fourth neighbor base station channel successfully receiving the DL-MAP and the UL-MAP is reported as a channel that is likely to be the target base station channel (706).

The minimum scan time for discovering the target base station channel during the group scan is T _ELJ2 703, which means that Participants 1, 2, and 3 are each {first, second channel} {third, fourth channel}, When the {Fifth and Sixth Channel} has been assigned to the neighboring base station channel to be scanned, Participant 2 completes the synchronization for the assigned fourth channel and reports it as a channel 707 that is likely to be the target base station channel. It's time. Participants 1 and 3 who have not directly scanned the target base station channel are required to receive information about the target base station channel, and the target base station channel at T _ELJ1 702 and T _ELJ3 704 using the scan result report message reported by participant 2. 708 and 709 may be scanned. Therefore, the group scan time of each user in the group according to the present invention discovers the target base station channel within a shorter time than the scan time T _MS required by the conventional scan method.

Thus, as discussed above, the group scan reduces the number of neighboring base station channels that any user will scan to find the target base station channel, thereby improving the total scan time to discover the target base station channel for a shorter scan time. The effect is possible.

8 is a flowchart illustrating a dynamic neighbor base station channel state update procedure according to an embodiment of the present invention.

Referring to FIG. 8, the dynamic channel apparatus 801 may allocate the best neighbor base station channels according to the situation of all users. The dynamic channel apparatus maintains a list of identical neighboring base station channels for each group, with the initial group channel list 802 applied to the first group consisting of an initial channel list 803 that does not contain any reliability. Can be. As the group scan proceeds, the dynamic channel apparatus refers to the information of the scan result report message received by the serving base station, and gradually obtains the status information 805 and 806 for each channel, such as the group 2 channel list 804. Can be updated with Therefore, when a group scan participant belonging to Group 2 or a target scan participant urgently needs to scan a target channel, the dynamic channel apparatus may allow the serving base station to allocate the best neighboring base station channel to the corresponding user. Here, the best neighbor base station channel may mean a channel that is highly targetable in the status list 806 for each channel.

Determining that the existing groups are not within the scope of the existing groups despite the existence of the existing groups, the user group forming the new group refers to the channel state information of the existing groups as much as possible by the dynamic channel device (809), and thus has the lowest target probability. In order to scan from a neighboring base station channel, an initial channel list 808 in the form of inverting existing information 811 may be allocated. This is because a channel that is likely to be targeted to groups in an area in which it cannot participate is less likely to be targeted to itself from a positional perspective. Therefore, through the operation of the dynamic channel apparatus, the group scan method can provide the best neighbor base station channel list to users in a specific group as well as to users who are difficult to associate with any group.

In addition, any users who join the group can move at any time. Therefore, any user can leave the group area in an unpredictable form, so that a user outside the group determines that the user who left the group is still in the group area and joins the group through detection. Can happen. In the case of a user newly participating in the group in such a situation, it is not easy to apply the group scan method. Therefore, since the dynamic neighbor base station channel list as described above cannot be used permanently, the proposed invention senses a user who has left a specific group area and performs a real scan when the neighboring base station channel of the group participating as a later participant is allocated. If the result and the information in the assigned dynamic neighbor base station channel list differ, it is assumed that the group scan user sensed by him no longer has a dependency on the group area, and the user can form a new group to perform the group scan. Can be. In this situation, the serving base station excludes the wrong group scan participant from the group and adds mapping information related to the uplink transmission of the user from the periodic user group advertisement message so that sensing by other users no longer occurs. You may not disclose it anymore.

Also, when a group scan participant scans a target channel due to the necessity to scan a target channel, when the scan target is different and the scan result is different, the serving base station discards all information about the group itself. can do. This is because even users who form a group and cooperatively sense a channel consider sharing information with each other as meaningless. That is, the serving base station expands to a larger area by voluntary movement of each group scan users who initiated a group scan in a small group area, so that the group scan user itself and the user outside the group are no longer. It is not considered useful to them either.

As described above, the present invention provides a group scan method for dividing and scanning several neighboring base station channels by forming a group among adjacent users, and dynamically manages scan results of all groups belonging to the serving base station within the serving base station by group. By providing a channel device, the effect of discovering a target base station channel in a shorter time can occur.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above-described embodiments, which can be variously modified and modified by those skilled in the art to which the present invention pertains. Modifications are possible. Accordingly, the spirit of the present invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications thereof will belong to the scope of the present invention.

1 is a flowchart illustrating a method of determining a target base station channel according to an embodiment of the present invention.

2 is a diagram illustrating an area of a group based on preset threshold values of a received signal strength according to an embodiment of the present invention.

FIG. 3 is a diagram for describing an uplink opportunity of each user in a frame when a serving base station broadcasts an uplink allocation map according to an embodiment of the present invention.

4 is a flowchart illustrating a group forming procedure on the user side according to an embodiment of the present invention.

5 is a flowchart illustrating a group forming procedure in terms of a serving base station according to an embodiment of the present invention.

6 is a flowchart illustrating a procedure of performing group scans by group users according to an embodiment of the present invention.

FIG. 7 is a diagram for comparing and explaining a scan time required in an embodiment of the present invention.

8 is a flowchart illustrating a dynamic neighbor base station channel state update procedure according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

201: serving base station 205: maximum reach

206: scan start threshold 207: skin preparation threshold

208: group participation threshold 209: group area

Claims (5)

Determining whether a terminal needs to search a channel by determining a signal strength of a first received signal from a serving base station; Determining the presence of a participation group and whether to participate in the participation group based on the signal strength of the first received signal, the signal strength of the second received signal from a neighboring group user, and the advertisement message from the serving base station; And If the participation group is able to participate, joining the participation group to scan a target candidate channel, If it is impossible to participate in the participation group, forming an independent group to scan a target candidate channel Target base station channel determination method comprising a. The method of claim 1, Determining whether or not the participation, When the first received signal is smaller than the preset scan ready threshold and the second received signal is greater than the preset group joining threshold, it is determined that participation is possible in the participating group. Determining the target base station channel, if the first received signal is smaller than the preset scan start threshold, and the second received signal is smaller than the preset group participation threshold, it is determined that participation in the participation group is impossible Way. The method of claim 1, The scanning step, If participation is possible in the participation group, it is determined whether the participation group has found a target base station channel, If the target base station channel is found, the target candidate channel is scanned; And if the target base station channel is not found, performing a scan for discovering a target candidate channel with existing participants of the participating group. The method of claim 1, The signal strength of the second received signal is And detecting signal strength of a terminal transmitting an uplink message during the interval by sensing an uplink mapping interval broadcast by the serving base station. Receiving a channel scan schedule request message from a terminal; Determining whether a group ID is included in the message; And When the group ID is included in the message, a group scan participant performing a group scan to discover a target base station channel or a previously found target base station channel according to whether a target base station channel is found in the group. As a target scan participant who scans for, If the message does not include a group ID, setting the terminal as the group scan participant Target base station channel determination method comprising a.

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