JP4694319B2 - Wireless communication control system and wireless communication control method - Google Patents

Description

  The present invention relates to a wireless communication control system and a wireless communication control method.

In recent years, a seamless communication technique in which a mobile terminal has a plurality of communication media and switches without interrupting communication when selecting an optimal communication medium according to a situation such as a wireless environment or a communication purpose has been studied. For example, it is possible to adaptively switch between a cellular system and a wireless local area network (LAN) system capable of high-speed wireless access. In the conventional seamless communication technique, the received power for each communication medium in the mobile terminal is measured, and the communication medium is switched according to the transmission speed or the like. For example, when a mobile terminal has a cellular system and a wireless LAN system, a wide coverage area can be used according to the cellular system, and a high throughput can be obtained according to the wireless LAN system. In order to take advantage of the characteristics of both, the wireless LAN system is used when the measured value of the received power of the wireless LAN system is sufficient, while the cellular value is measured when the measured value of the received power of the wireless LAN system is insufficient. Control to use the system.
Saito et al., “Development of software for switching between different types of wireless communication media”, 2003 UEC, B-5-289, Mar. 2003

  However, in the conventional seamless communication technique described above, there are cases where it is difficult to smoothly switch between a plurality of communication media. For example, if the received power suddenly drops while using high-speed wireless access such as a wireless LAN system, the communication media may not be switched in time, and communication quality such as communication interruption may be deteriorated. is there.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a wireless communication control system and a wireless communication control method that can contribute to smooth switching of a plurality of communication media. is there.

In order to solve the above problems, a radio communication control system according to the present invention is a radio communication control system which performs switching control of the plurality of communication media according to the radio communication, created respectively by the communication medium, each position Based on the received power characteristics representing the received power characteristics, position predicting means for predicting the position of the mobile terminal having the plurality of communication media, and the received power characteristics on the path of movement until reaching the predicted position, A switching prediction unit that predicts switching of communication media and a switching control unit that prepares switching of the communication media based on the prediction result of the switching are provided.

  In the wireless communication control system according to the present invention, the switching predicting means determines whether or not the communication medium is switched based on a limit received power at which the switching of the communication medium occurs.

  In the wireless communication control system according to the present invention, when the mobile terminal arrives at a position where it is predicted that there is a possibility of switching the communication media, the switching of the communication media is started based on the measured value of received power. It is characterized by judging.

  In the wireless communication control system according to the present invention, the switching of the communication medium is forcibly started when the mobile terminal reaches a position where the communication medium is predicted to be switched. To do.

The wireless communication control system according to the present invention is a wireless communication control system that performs switching control of a plurality of communication media related to wireless communication, a received power map representing a received power characteristic for each position for each communication medium, and the plurality of the plurality of communication media Position predicting means for predicting the position of a mobile terminal having communication media; switching predicting means for predicting switching of the communication media based on the received power characteristics in the course of movement until reaching the predicted position; Switching control means for preparing the switching of the communication media based on the prediction result of, and calculating the slope of the received power characteristic on the received power map in the course of the movement path, the slope is negative and When the absolute value exceeds a predetermined value, the communication medium is prepared for switching.

  In the radio communication control system according to the present invention, it is determined whether or not to execute control processing based on the slope of the received power characteristic, based on the received power characteristic on the received power map.

A radio communication control method according to the present invention is a radio communication control method for performing switching control of a plurality of communication media related to radio communication, the process of predicting the position of a mobile terminal having the plurality of communication media, and the communication Based on the process of obtaining the received power characteristic on the path of movement until reaching the predicted position from the received power map representing the received power characteristic for each position created for each medium, and based on the obtained received power characteristic And a step of predicting switching of the communication media and a step of preparing switching of the communication media based on the prediction result of the switching.
A radio communication control method according to the present invention is a radio communication control method for performing switching control of a plurality of communication media related to radio communication, the process of predicting the position of a mobile terminal having the plurality of communication media, and the communication A process of obtaining a received power characteristic on the movement path until reaching the predicted position from a received power characteristic representing a received power characteristic for each position for each medium, and based on the obtained received power characteristic, A step of predicting switching, and a step of preparing switching of the communication media based on the prediction result of the switching, and calculating a slope of the received power characteristic on the received power map on the moving path, When the slope is negative and the absolute value exceeds a predetermined value, switching of the communication media is prepared.
In the wireless communication control method according to the present invention, it is determined whether or not to execute a control process based on a slope of the received power characteristic based on the received power characteristic on the received power map.

  According to the present invention, since the switching of the communication medium is predicted and the switching is prepared in advance, the switching can be smoothly executed when a request for switching the communication medium actually occurs.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a wireless communication control system according to an embodiment of the present invention. In the wireless communication control system shown in FIG. 1, switching (handover) between the wireless network A_100 and the wireless network B_200 used for the communication path of the mobile terminal 30 is controlled. For example, handover of the cellular system and the wireless LAN system is controlled.

  In FIG. 1, the control device 10 is communicatively connected to both the wireless network A_100 and the wireless network B_200. Further, the control device 10 can communicate with the database 20 and read data from the database 20. The mobile terminal 30 has communication media of both the wireless network A_100 and the wireless network B_200, and can wirelessly connect to both the wireless network A_100 and the wireless network B_200.

  In the control device 10 of FIG. 1, the communication unit 11 is connected to both the wireless network A_100 and the wireless network B_200, and transmits and receives data between the wireless network A_100, the wireless network B_200, and the mobile terminal 30. Data is transmitted to and received from the mobile terminal 30 via the wireless network A_100 or the wireless network B_200.

The information acquisition unit 12 acquires various types of information from the mobile terminal 30 via the communication unit 11. The information acquired from the mobile terminal 30 includes position information indicating the position of the mobile terminal 30 and speed information indicating the moving speed and the moving direction of the mobile terminal 30.
The position prediction unit 13 predicts the position of the mobile terminal 30 after a predetermined time (T seconds) based on the position information and speed information acquired from the mobile terminal 30.
The switching predicting unit 14 causes a handover of the radio network A_100 and the radio network B_200 related to the mobile terminal 30 on the moving route from the current position to the predicted position T seconds after the current position. Predict. For this prediction, a received power map stored in the database 20 is used.
The switching control unit 15 prepares for the handover based on the prediction result of the occurrence of the handover.

In the mobile terminal 30 of FIG. 1, a wireless communication unit A_31 is a communication medium of the wireless network A_100, and communicates by wirelessly connecting to the wireless network A_100. The wireless communication unit B_32 is a communication medium of the wireless network B_200, and communicates by wirelessly connecting to the wireless network B_200.
The control unit 33 controls the wireless communication unit A_31 and the wireless communication unit B_32, and performs control processing related to the handover of the wireless network A_100 and the wireless network B_200. Further, the control unit 33 communicates with the control device 10 via the wireless communication unit A_31 or the wireless communication unit B_32, and transmits and receives data.
The measurement unit 34 performs various measurements. The measurement items include the position, moving speed, and moving direction of the mobile terminal 30. The measurement unit 34 measures the longitude, latitude, moving speed, and moving direction of the current position using, for example, GPS (Global Positioning System). The measured longitude and latitude are transmitted as position information, and the moving speed and moving direction are transmitted as speed information to the control device 10 via the control unit 33, respectively.

  FIG. 2 is a diagram illustrating a configuration example of the reception power map 21 stored in the database 20. The received power map 21 represents received power characteristics for each position from a specific wireless network. As illustrated in FIG. 2, the received power map 21 includes data of a combination of position and received power. In the example of FIG. 2, the received power map 21 is composed of data of a combination of longitude and latitude indicating position and RSSI (Received Signal Strength Indicator) indicating received power. The received power (RSSI (x, y)) at a specific position (longitude (x), latitude (y)) can be obtained from the received power map 21 in FIG. The reception power map 21 is created in advance by actual measurement. In the present embodiment, the reception power map 21 is created separately for each of the wireless network A_100 and the wireless network B_200. Note that the data of the received power map 21 illustrated in FIG. 2 is data for convenience.

  Hereinafter, characteristic wireless communication control processing of the present embodiment will be described in detail.

First, an overview of the wireless communication control process according to the present embodiment will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the wireless communication control process according to the present embodiment.
In general, within a coverage area of a radio base station of a radio network, there is a reception power characteristic depending on a location as illustrated in FIG. 3, and the frequency of occurrence of handover is also a place as the reception power characteristic changes. It is considered to change depending on Based on this knowledge, in the present embodiment, the occurrence of a handover is predicted based on the received power characteristics in the course of the movement path from the current position of the mobile terminal 30 to the predicted position T seconds later. Then, preparation for handover is performed according to the prediction result.

FIG. 4 is a flowchart showing the flow of the wireless communication control process according to the present embodiment. A specific wireless communication control process according to this embodiment will be described with reference to FIG.
4, the information acquisition unit 12 of the control device 10 acquires position information (longitude; X0, latitude; Y0) and speed information (longitude direction speed; Vx0, latitude direction speed; Vy0) from the mobile terminal 30 ( Step S1). Next, the position predicting unit 13 predicts the position (X1, Y1) after T seconds of the mobile terminal 30 from the acquired position information (X0, Y0) and speed information (Vx0, Vy0) (step S2). . In the prediction, the position (X1, Y1) is calculated using the following equation.
(X1, Y1) = (X0, Y0) + T × (Vx0, Vy0)

  Next, the switching prediction unit 14 examines the reception power characteristic on the movement route from the current position (X0, Y0) of the mobile terminal 30 to the predicted position (X1, Y1) T seconds later, and predicts the occurrence of a handover. . Specifically, for each sample position on the moving route, the reception power is acquired from the reception power map 21 in the database 20 to predict the occurrence of the handover.

First, an initial value 0 is set to the variable t (step S3). Next, a sample position (x, y) on the moving route is set (step S4). The sample position (x, y) is calculated using the following equation.
(X, y) = (X0, Y0) + T × (Vx0, Vy0) × t / a
However, a is a constant (positive integer) that determines the number of samples.

  Next, the switching prediction unit 14 acquires the received power (RSSI (x, y)) at the sample position (x, y) from the received power map 21 stored in the database 20 (step S5). Next, the acquired RSSI (x, y) is compared with a predetermined reception power TH_RSSI (step S6). The predetermined reception power TH_RSSI corresponds to the limit reception power at which handover occurs. A plurality of predetermined received power TH_RSSI may be set to an appropriate value according to each wireless network.

  When the RSSI (x, y) acquired from the received power map 21 is less than the predetermined received power TH_RSSI as a result of the comparison in step S6 (step S6 is YES), the switching predicting unit 14 may cause a handover. The switch control unit 15 is notified of the presence, and in response to this notification, the switch control unit 15 starts pre-processing related to the handover (step S7).

  On the other hand, when the RSSI (x, y) acquired from the received power map 21 satisfies the predetermined received power TH_RSSI (step S6 is NO), the switching prediction unit 14 similarly evaluates the received power for the next sample position. To determine the possibility of occurrence of handover. Specifically, 1 is added to the variable t in step S8, and the variable t is compared with the constant a in step S9. If the variable t is equal to or smaller than the constant a (NO in step S9), the process returns to step S4 to calculate the next sample position (x, y). On the other hand, if the variable t exceeds the constant a (YES in step S9), since the determination of the possibility of occurrence of handover for all the sample positions is completed, the processing is ended as it is.

  According to the above-described embodiment, a handover is predicted and a handover is prepared in advance. Therefore, a handover can be smoothly executed when a handover request is actually generated. As a result, even if the received power is suddenly reduced, handover is performed smoothly, and deterioration of communication quality such as communication interruption can be prevented.

  When the mobile terminal 30 reaches a position where it is predicted that a handover may occur, the following two methods A and B can be considered as a method of handover control.

(Method A)
Based on the measured value of received power, the start of handover is determined. For example, received power measured at the mobile terminal 30 is used. According to this method A, handover according to actual received power can be performed.
(Method B)
The handover is forcibly started when a position where it is predicted that a handover may occur is reached. According to this method B, in an area where a handover can occur, the handover can be performed with a margin when the handover is not actually required.

  Note that various modifications can be made in the wireless communication control process according to the present embodiment.

(Modification 1)
The slope of the received power characteristic on the received power map 21 is calculated along the moving path from the current position (X0, Y0) of the mobile terminal 30 to the predicted position (X1, Y1) T seconds later. When the slope is negative and the absolute value exceeds a predetermined value, preparation for handover is started. As a result, for example, it is possible to take care of a case where the received power drops suddenly due to a building or the like, and perform handover with a margin.

(Modification 2)
By determining the received power on the received power map 21 with a threshold value, it is determined whether or not to execute the process according to the first modification. For example, the limit received power at which handover occurs is set as the threshold value, and when the received power on the received power map 21 is less than the threshold value, the first modification is not adopted. Thereby, in an area where a handover may occur, the processing load can be reduced by eliminating the processing of the first modification.

In addition, the functional arrangement of the wireless communication control system according to the present embodiment can be changed as appropriate.
For example, the mobile terminal 30 includes the position prediction unit 13 and the switching prediction unit 14 illustrated in FIG. 1, and the mobile terminal 30 performs position prediction and prediction of occurrence of a handover, and transmits the result to the control device 10. May be. In this case, the received power map 21 is downloaded from the database 20 to the mobile terminal 30. Moreover, in the download, it is only necessary to acquire only necessary area data as appropriate.
In addition, the control device 10 may be included in the mobile terminal 30.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

It is a block diagram which shows the structure of the radio | wireless communication control system which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the received power map 21 which concerns on the same embodiment. It is explanatory drawing for demonstrating the radio | wireless communication control process which concerns on the same embodiment. It is a flowchart which shows the flow of the radio | wireless communication control process which concerns on the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 11 ... Communication part, 12 ... Information acquisition part, 13 ... Position prediction part, 14 ... Switching prediction part, 15 ... Switching control part, 20 ... Database, 21 ... Received power map, 30 ... Mobile terminal, 31 , 32 ... wireless communication unit, 33 ... control unit, 34 ... measurement unit, 100, 200 ... wireless network

Claims (4)

In a wireless communication control system that performs switching control of a plurality of communication media related to wireless communication,
A received power map representing received power characteristics for each position for each communication medium;
Position prediction means for predicting the position of a mobile terminal having the plurality of communication media;
A switching prediction means for predicting switching of the communication media based on the received power characteristic in the course of a movement path until reaching the predicted position;
Switching control means for preparing the switching of the communication media based on the prediction result of the switching, and
A slope of the received power characteristic on the received power map in the course of the movement path is calculated, and when the slope is negative and the absolute value exceeds a predetermined value, preparation for switching the communication media is provided. A wireless communication control system. The radio communication control system according to claim 1 , wherein it is determined whether or not to execute control processing based on a slope of the reception power characteristic based on the reception power characteristic on the reception power map. A wireless communication control method for performing switching control of a plurality of communication media related to wireless communication,
Predicting the location of a mobile terminal having the plurality of communication media;
From the received power map representing the received power characteristics for each position for each communication medium, obtaining the received power characteristics on the path of movement until reaching the predicted position;
Predicting switching of the communication media based on the acquired received power characteristics;
A step of preparing the switching of the communication medium based on the prediction result of the switching;
Including
A slope of the received power characteristic on the received power map in the course of the movement path is calculated, and when the slope is negative and the absolute value exceeds a predetermined value, preparation for switching the communication media is provided. A wireless communication control method. 4. The radio communication control method according to claim 3 , wherein it is determined whether to execute a control process based on a slope of the received power characteristic based on the received power characteristic on the received power map.

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