KR101453165B1 - Media independent handover method and apparatus - Google Patents

Abstract

The present invention discloses a media independent handover method and apparatus. According to the present invention, there is provided a medium independent handover method of a mobile terminal, comprising the steps of: (a) performing a handover, transmitting a network before the handover (first network) Storing at least one history table including at least one history table, the pre-handover data including at least one of time, position, direction, speed and received signal strength; And (b) comparing the current data with data before handover stored in one or more history tables to determine a handover target network.

Description

[0001] MEDIA INDEPENDENT HANDOVER METHOD AND APPARATUS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for media independent handover, and more particularly, to a method and apparatus for predicting a handover target network based on a user's experience so that a fast handover can be performed.

Generally, in the case of a normal person, when a mobile device such as a smart phone or a notebook computer is used in a situation where the user is moving at a house, a public place, an office, a school, etc., handover will occur from time to time.

In the conventional standard technology and algorithms related to vertical handover, information about various networks around a user is collected and a handover network is selected and a handover is performed in consideration of the user's preference or the state of the terminal.

However, it is necessary not only to collect information from the neighboring network before each handover, but also to attempt handover to a network where there is no possibility of handover, thereby causing unnecessary handover signaling, and power consumption for receiving various network signals .

1 is a flowchart illustrating an MIH-based vertical handover signaling according to the related art.

Referring to FIG. 1, a mobile node requests information (MIH_Get_Information_Request) for media independent handover (MIH_Get_Information_Response) (step 100) to a media independent information server (MIIS) (Step 102).

The mobile node and the serving network then determine the resource availability.

More specifically, when the mobile node transmits a query request (MIH_MN_HO_Query_Candidate_request) for a candidate network adjacent to the serving network in a serving network (step 104), the serving network cooperates with the neighboring networks (CN1 to CNn) (MIH_N2N_HO_Query_Resource_request / response, step 106), and transmits a response (MIH_MN_HO_Query_Candidate_response) including neighbor candidate network information to the mobile node (step 108).

A handover network (CN1) is determined through steps 104 to.

After the handover network is determined, the mobile node and the serving network perform resource preparation for handover to the determined network.

To this end, the mobile node sends a handover commit request (MIH_MN_HO_Commit_request) to the serving network (step 110) and the serving network sends and receives the MIH_N2N_HO_Commit_request / response to the handover network (CN1) (MIH_MN_HO_Commit_response) to the handover commit request (step 116).

Thereafter, a two-layer connection configuration and an upper layer handover are performed (step 118)

As described above, conventionally, when the mobile node is handed over, the serving network must check the resource status in cooperation with a plurality of adjacent candidate networks, which is inefficient.

Disclosure of Invention Technical Goals The present invention has been made in view of the above problems and it is an object of the present invention to provide a medium independent handover method and apparatus capable of quickly performing a handover by predicting a handover target network using network information mainly used by a user I want to.

According to a preferred embodiment of the present invention, there is provided a medium independent handover method for a mobile terminal, comprising the steps of: (a) performing a handover, the network before the handover (first network) (Second network) identification information and data prior to handover, the pre-handover data including at least one of time, location, direction, speed and received signal strength; And (b) comparing the current data with data before handover stored in one or more history tables to determine a handover target network.

Wherein the step (b) includes a first network including the first network, which is the same as the current network of the at least one history table, and includes a history table including data having the same position, time, direction, To be the handover target network.

The method of claim 1, further comprising calculating a usage rate of each second network included in the at least one history table, wherein, when a plurality of handover target network candidates exist, The handover target network can be determined based on the utilization rate.

The usage rate calculation step may set the second network to a black list if the network usage rate is less than or equal to a threshold value for a predetermined period.

The step (b) includes: calculating a data matching rate for a first history table having previous data matching the current data; Calculating a probability according to a usage rate of a second network included in the first history table; And determining the second network included in the first history table as a candidate for the handover target network when the data matching rate is greater than the calculated probability.

The usage rate may be updated at a preset period of time.

The probability calculation may be performed according to the following equation.

[Mathematical Expression]

Where U is utilization rate

In the step (b), when there are a plurality of handover target network candidates, one handover target network may be determined using a neuron algorithm.

Normalizing the handover pre-handover data and the current data included in the first history table corresponding to the plurality of handover target candidates when the number of the handover target network candidates is a plurality; And calculating the Euclidean distance between the normalized data before handover and the current data, wherein the one handover target network can be determined using the calculated Euclidean distance.

It can be determined that there is a positional identity if the current position is within a predetermined range of the coverage radius of the current network centered on the previous position included in the history table.

In the step (a), when the received signal strength decreases, data before handover for a preset time can be stored.

According to another aspect of the present invention, there is provided a computer-readable recording medium on which a program for performing the above-described method is recorded.

According to another aspect of the present invention, there is provided an apparatus for performing a medium independent handover, the apparatus comprising: means for performing a handover, the network before the handover (first network) Wherein the pre-handover data includes at least one of time, location, direction, speed, and received signal strength; And a control unit for determining a handover target network by comparing current data and data before handover stored in at least one history table.

According to the present invention, since data before handover is stored in the handover and data of the current data and the data before handover are compared with each other, the handover target network is predicted in advance, so that power consumption and efficiency can be reduced at the time of handover have.

1 illustrates a flow diagram of an MIH-based vertical handover signaling according to the prior art;
2 is a diagram for explaining a state in which a media independent handover occurs during movement of a user;
3 is a diagram for explaining a process of storing a previous history when performing a handover according to an embodiment of the present invention.
4 is a diagram illustrating data stored in a history table and a stack structure of a mobile terminal according to an embodiment of the present invention.
FIG. 5 illustrates an example of a history table according to an embodiment of the present invention. FIG.
FIG. 6 is a flowchart of a handover entire process according to an embodiment of the present invention; FIG.
FIG. 7 is a flowchart of a handover target network determination process according to an exemplary embodiment of the present invention; FIG.
8 is a view for explaining a process of determining a positional consistency according to an embodiment of the present invention.
9 is a view for explaining a direction identity determination process according to an embodiment of the present invention;
10 is a diagram for explaining a neural system algorithm;
11 is a flowchart of a network module power management process according to a preferred embodiment of the present invention.
12 is a flowchart illustrating an MIH-based vertical handover signaling according to an exemplary embodiment of the present invention.
13 is a block diagram of a mobile terminal in accordance with an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate a thorough understanding of the present invention, the same reference numerals are used for the same means regardless of the number of the drawings.

2 is a diagram for explaining a state in which a media independent handover occurs during movement of a user.

As shown in FIG. 2, the moving range of a general user becomes a house where the user resides, a public place (road, stop, subway, etc.) to be moved when commuting to and from work, and a company.

The mobile range of the user includes a 3G network (or LTE network), a WAMAX network (WIBRO), and a wireless LAN network. Accordingly, the mobile terminal 200 such as a smart phone or a notebook is used And handover is occasionally generated when the mobile terminal is connected to the network.

According to a preferred embodiment of the present invention, when performing a handover as shown in FIG. 3, the mobile terminal 200 determines whether or not the network before the handover (the first network) and the network after the handover And a history table including data before handover for a predetermined time, and determines a network to be handed over by comparing current data with data before handover included in the history table.

For example, as shown in FIG. 4, the data prior to handover according to the present invention includes data up to 10 seconds before (T-10s) based on the handover time T, ) In the form of a stack.

More specifically, as shown in FIG. 5, the history table according to the present invention includes network identification information (Prev. Net) before handover, network identification information (HO Net) after handover, The received signal strength (RSSI), position, direction, and velocity information at the receiver.

Preferably, the time information may be stored on a 24-hour basis in units of seconds, the position information in units of longitude and latitude, the velocity information in units of seconds (m / 2), and the direction information in degrees.

According to a preferred embodiment of the present invention, the history table may further include information on the network usage rate (P (U)) in addition to the above information.

The present invention predicts a handover target network by comparing current data with one or more history tables based on a movement pattern of a user. When the second network after handover stored in the history table is not used for a predetermined period or more, The second network can be managed as a black list.

Here, management by black list means that even if there is a history table including previous data matching the current data, the history table is not used for handover prediction.

Preferably, the mobile terminal 200 calculates the network usage rate at a preset periodic period, and manages the second network in a black list if the network usage rate is below a threshold value during the previous period.

For example, the network utilization rate may be updated on a weekly basis. If the network utilization rate is 0 for the previous week of the second network, that is, if the second network included in the history table is never used, do.

Hereinafter, a handover target network determination process according to the present invention will be described in detail with reference to the drawings.

FIG. 6 is a flowchart of an overall handover procedure according to an embodiment of the present invention.

Referring to FIG. 6, the mobile terminal 200 determines whether the current network matches the pre-handover network (Prev. Net) included in the history table (step 600).

If there is a history table including the pre-handover network matching the current network, the mobile terminal 200 determines whether the received signal strength in the current network is a reduced state (step 602).

The mobile terminal 200 determines that the handover needs to be performed and compares the data in the current network with one or more history tables stored in advance, A prediction process is performed (step 604).

7 is a flowchart of a handover target network determination process according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the mobile terminal 200 stores data (location, time, direction, speed, and RSSI) in the current network in a predetermined time unit (for example, every second) (step 700).

At the same time as storing the current data as in step 700, it is judged whether or not it matches the data contained in the pre-stored history table (step 702).

According to the present invention, step 702 is a process for determining whether the position, time, direction, speed, and RSSI (previous data) included in the history table have the same identity within each predetermined range with each piece of information at the current time.

More specifically, in the case of positional consistency according to the present invention, the mobile terminal 200 may determine that there is a positional identity if the current position is within a predetermined radius range centered on the previous position.

As shown in FIG. 8, if there is a current position in a 10% error range (R / 10) of the radius R of the current network coverage around the previous position, the mobile terminal 200 determines that the position is identical can do.

In terms of time and direction, the mobile terminal 200 may determine that the time and direction are the same when the current time is in the previous time and the current direction is within the predetermined time range in the previous direction.

For example, if the previous time and the current time are within the 1 hour range, it can be determined that there is time coincidence.

As shown in FIG. 9, the mobile terminal 200 has a directional identity when the current direction is in the 10% error range of the previous forward direction (e.g., within the range of ± 36 degrees from the previous direction) .

Also, in terms of speed, the mobile terminal 200 may determine that there is a speed identical if the previous speed and the current speed have a difference of 10% range.

The mobile terminal 200 can determine that the received signal strength is identical to the received signal strength when the signal strength is the same or is about 10% of the dBm value.

Referring again to FIG. 7, if there is a table value having the same identity as the current data through the above process, the mobile terminal 200 transmits a handover to the network after the handover included in the history table including the identical data. 2 network) is blacklisted (704).

If there is no history table including data matching the current data in step 702, or if the network is black list after handover, the mobile terminal 200 searches for the neighboring network in the conventional manner as shown in FIG. 1, (Step 706).

If the network is not blacklisted after the handover included in the history table, the mobile terminal 200 calculates the data concordance rate (HIT rate) of the previous data and the current data included in the history table (step 708).

As shown in FIG. 5, when the current time, position, speed, direction, and received signal strength are each matched with the data included in each column of the history table, the HIT is processed as HIT, The number of which is matched.

The mobile terminal 200 calculates a probability P according to the network utilization (U (%)) for one or more history tables (step 710).

Step 710 is a process for selecting only the network as a candidate of the handover target network after the handover included in the history table in which the total HIT rate (data matching rate) exceeds a predetermined value.

According to the present invention, the probability P of each history table can be determined through the following equation.

According to the present invention, a network can be determined as a handover target network candidate after a handover included in a history table having a HIT rate exceeding a predetermined value. If the network utilization rate U is high according to Equation (1) , The probability P becomes small, and even if the total HIT rate is somewhat small, it can be selected as a candidate.

That is, even if the data matching rate is low due to a high probability of handover in a network with a high utilization rate, the possibility of being determined as a handover target network is high, and therefore, the probability is calculated using Equation (1).

After calculating the probability P, the mobile terminal 200 determines whether the number of handover target networks having the HIT rate greater than the probability P is one or more (step 712). If there is one handover target network, Management algorithm and a handover preparation algorithm by MIH (steps 714 and 716).

On the other hand, if there are a plurality of candidate network candidates for handover, the mobile terminal 200 determines a handover target network by a neuron method (step 718).

As shown in FIG. 10, a neuron model is a model of a human sensory neuron and a motor neuron. In the initial learning process, when input values (data sets) are input, it is mapped to neurons (result values) And a neuron (result value) is determined by comparing similarity (Euclidean distance) with previous input data values with respect to input values inputted afterward.

Euclidean distance calculations for each data are performed at step 718 for the neuron scheme. The Euclidean distance calculation is a process for using the neuron algorithm described below and normalizing the previous data and the current data by the following equation and obtaining the average value of the Euclidean distance (proximity) between the data .

Where x _n is current data such as current position, time, velocity, direction, received signal strength and y _n is data such as previous position, time, velocity, direction, received signal strength.

11 is a flowchart of a network module power management process according to a preferred embodiment of the present invention.

Referring to FIG. 11, after the handover target network prediction is completed (Step 1100), the mobile terminal 200 determines whether the handover target network module is ON (Step 1102).

If the handover target network module is ON, the MIH-based handover to the handover target network is performed (step 1104).

When the handover target network module is turned off, the mobile terminal 200 turns it on (step 1106) and performs an MIH-based handover.

The network module before handover excluding the currently used network module is turned off (step 1108).

According to the present invention, when the handover target network is predicted through the prediction algorithm as described above, handover can be performed without requesting and signaling the neighboring network information such as MIIS (Media Independent Information Server).

12, when the CN1 (Candidate Network1) is selected as the handover target network through the prediction of the handover target network, the resource availability check process of FIG. 1 of the serving network can be omitted, Over can be performed.

13 is a diagram illustrating a configuration of a mobile terminal according to an embodiment of the present invention.

13, the mobile terminal 200 according to the present invention may include a control unit 1300, a storage unit 1302, and network modules 1304-1 to 1304-n.

The controller 1300 stores the position, time, direction, speed, and received signal strength data of the mobile terminal 200 in the memory in a predetermined number of stacks.

If the received signal strength decreases to a predetermined strength or less, the controller 1300 stores the data as a stack. If a handover occurs, the control unit 1300 performs handover before and after handover, And controls the data in the immediately preceding preset time to be stored in the storage unit 1302 as a history table.

After storing the history table, if the network at the current time matches the pre-stored network of the history table of the stored history table and the received signal strength decreases, the controller 1300 compares the current data with one or more history tables, Over-target network is predicted.

If the handover target network is predicted, the controller 1300 manages the power of the module 1304-n corresponding to the predicted handover target network to perform the handover.

Embodiments of the present invention may be implemented in the form of program instructions that can be executed on various computer means and recorded on a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Examples of program instructions, such as magneto-optical and ROM, RAM, flash memory and the like, can be executed by a computer using an interpreter or the like, as well as machine code, Includes a high-level language code. The hardware devices described above may be configured to operate as one or more software modules to perform operations of one embodiment of the present invention, and vice versa.

It will be apparent to those skilled in the relevant art that various modifications, additions and substitutions are possible, without departing from the spirit and scope of the invention as defined by the appended claims. The appended claims are to be considered as falling within the scope of the following claims.

Claims (13)

A media independent handover method of a mobile terminal,
(a) storing at least one history table including identification information of a network before a handover (first network) and a network after a handover (second network) and data before handover at the time of performing a handover, The data comprising at least one of time, position, direction, velocity and received signal strength; And
(b) comparing the current data with data before handover stored in one or more history tables to determine a handover target network,
Further comprising calculating a usage rate of each second network included in the one or more history tables,
The step (b)
Calculating a data consistency rate for a first history table having previous data consistent with the current data;
Calculating a probability according to a usage rate of a second network included in the first history table; And
And determining a second network included in the first history table as a candidate for a handover target network when the data matching rate is greater than the calculated probability. The method according to claim 1,
The step (b)
The second network of the history table including the first network identical to the current network among the one or more history tables and including data having the same position, time, direction, speed, and signal strength as the current network, A medium independent handover method for determining over-target network. delete The method according to claim 1,
Wherein the utilization rate calculation step comprises:
And setting the second network to a black list if the network utilization rate is less than or equal to a threshold value for a predetermined period of time. delete The method according to claim 1,
Wherein the usage rate is updated at a preset period of time. The method according to claim 1,
Wherein the probability calculation is performed according to the following equation.
[Mathematical Expression]

Where U is utilization rate The method according to claim 1,
The step (b)
And determining a single handover target network using a neuron algorithm when the number of handover target candidates is plural. 9. The method of claim 8,
The step (b)
Normalizing the handover pre-handover data and the current data included in the first history table corresponding to the plurality of handover target network candidates when the number of the handover target network candidates is a plurality; And
Calculating the Euclidean distance between the normalized handover pre-handover data and the current data,
Wherein the one handover target network is determined using the calculated Euclidean distance. 3. The method of claim 2,
The step (b)
And determines that there is a positional identity if the current position is within a predetermined range of the coverage radius of the current network centered on a previous position included in the history table. The method according to claim 1,
The step (a)
And storing data before handover for a predetermined time when the received signal strength decreases. A computer-readable recording medium on which a program for performing the method according to claim 1 is recorded. 1. An apparatus for performing media independent handover,
A storage unit for storing one or more history tables including a network before the handover (first network) and a network (second network) identification information after the handover and data prior to the handover, Comprising at least one of time, position, direction, velocity and received signal strength; And
And a control unit for determining a network to be handed over by comparing current data and data before handover stored in one or more history tables,
Wherein the controller calculates a usage rate of each second network included in the at least one history table, calculates a data consistency rate for a first history table having previous data matching the current data, And determines a second network included in the first history table as a candidate for a handover target network when the data matching rate is greater than the calculated probability.

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