JP2020182121A - Communication terminal, processing method, and program - Google Patents

Abstract

To determine a modulation coding method suitable for wireless communication with a base station before roaming at the time of roaming between base stations.SOLUTION: A communication terminal S1 includes a communication IF 11 for wireless communication, and a calculation unit 12 that intercepts the radio wave of wireless communication transmitted by a base station A2 by the communication IF11, and calculates a first vector which is an error vector of a signal point included in the intercepted radio wave in a state in which the communication IF 11 establishes a communication link with a base station A1, and a determination unit 13 that determines a modulation coding method in which the first vector belongs to an allowable range of the error vector predetermined for the modulation coding method from among a plurality of modulation coding methods that can be used for wireless communication between the communication IF 11 and the base station A2 as a modulation coding method used for wireless communication between the communication IF 11 and the base station A2.SELECTED DRAWING: Figure 2

Description

The present invention relates to communication terminals, processing methods, and programs.

There is a communication system that enables wireless communication by communication terminals existing in a relatively wide area by arranging a plurality of wireless base stations (also simply referred to as base stations).

In such a communication system, the communication terminal establishes a communication link with any of a plurality of base stations. Further, when the communication terminal moves, it sequentially establishes a communication link (also referred to as roaming) with an appropriate base station while moving. When a communication terminal establishes a new communication link with a base station, the communication rate used in the communication link is determined based on the quality of wireless communication. Specifically, in order to obtain an appropriate communication rate (modulation coding method) for maintaining the quality of wireless communication, communication with a plurality of modulation coding methods is tried, and appropriate communication is performed based on the result. Wireless communication takes place using the rate.

Patent Document 1 discloses a method of measuring the quality of wireless communication, and more specifically, discloses a method of measuring EVM (Error Vector Magnitude) as the quality of wireless communication.

Japanese Unexamined Patent Publication No. 2009-21784

When roaming, the communication terminal needs to determine the modulation coding method to be used for communication on the new communication link. If the modulation coding method used for communication on a new communication link is decided after roaming, communication using an appropriate modulation coding method will not be performed until the decision, and communication quality or communication speed, etc. There is a problem that improper communication can be made.

The present invention has been made to solve the above problems, and provides a communication terminal or the like capable of determining a modulation coding method suitable for wireless communication with a base station before starting roaming when roaming between base stations. The purpose is.

In order to solve the above problems, the communication terminal according to one aspect of the present invention has a communication interface for wireless communication and a second base station in a state where the communication interface establishes a communication link with the first base station. Intercepts the radio communication radio wave transmitted by the communication interface and calculates the first vector which is the error vector of the signal point included in the intercepted radio wave, the communication interface and the second base station. Among a plurality of modulation coding methods that can be used for wireless communication with, the communication of the modulation coding method in which the first vector belongs to the allowable range of the error vector predetermined for the modulation coding method. It includes a determination unit that determines as a modulation coding method used for wireless communication between the interface and the second base station.

According to this, the communication terminal uses the error vector of the radio wave from the second base station while establishing the communication link with the first base station, and is a modulation coding method suitable for communication with the second base station. To be determined in advance. If it is determined in this way, when communicating with the second base station thereafter, communication is performed using an appropriate modulation coding method determined in advance without performing processing for determining an appropriate modulation coding method. It can be performed. In this way, when roaming between base stations, the communication terminal can determine a modulation coding method suitable for wireless communication with the base station before the start of roaming.

Further, the calculation unit repeatedly intercepts the radio wave of the wireless communication transmitted by the second base station in the state, calculates the first vector based on the intercepted radio wave each time, and determines the determination. The unit may determine the modulation coding method used for communication with the second base station each time the calculation unit calculates the first vector.

According to this, the communication terminal repeatedly determines a modulation coding method that can be appropriately used for communication with the second base station. Therefore, the communication terminal can determine a modulation coding method suitable for a relatively new environment even when the surrounding wireless environment is fluctuating. Therefore, the communication terminal can appropriately determine a modulation coding method suitable for wireless communication with the base station, which is suitable for the surrounding wireless environment.

Further, the communication terminal further (a) disconnects the communication link between the communication interface and the first base station, and (b) establishes the communication link between the communication interface and the second base station. The communication interface may be provided with a control unit that controls communication with the second base station by using the modulation coding method determined by the determination unit.

According to this, after roaming from the first base station to the second base station, the communication terminal communicates by a predetermined modulation coding method. If the modulation coding method is not determined in advance, the communication terminal has a communication quality or communication speed that is not suitable for wireless communication with the second base station until an appropriate modulation coding method is determined. It will communicate. Therefore, the communication terminal can appropriately determine a modulation coding method suitable for wireless communication with the base station, and can suppress communication in which communication quality and the like are not appropriate.

Further, the determination unit may determine the modulation coding method using the permissible range defined for each of the plurality of modulation coding methods.

According to this, the communication terminal more easily determines the modulation coding method by using the allowable range defined for the modulation coding method. When roaming between base stations, the communication terminal can more easily determine a modulation coding method suitable for wireless communication with the base station.

Further, the determination unit learns by learning (c) the correspondence between the quality of wireless communication by the communication interface at the past time point and the first vector acquired based on the radio wave intercepted at the time point. Data is created, (d) the permissible range predetermined for each of the plurality of modulation coding methods is changed based on the learning data, and (e) the modulation coding method is used using the changed permissible range. May be determined.

According to this, the communication terminal more easily determines the modulation coding method by reflecting the result of learning based on the actual communication quality in the past in the predetermined allowable range for the modulation coding method. When roaming between base stations, the communication terminal can more easily determine a modulation coding method suitable for wireless communication with the base station.

Further, the calculation unit further calculates a second vector which is an error vector of a signal point included in the radio wave received from the first base station, and the control unit further calculates the second vector and the first vector. The timing of performing the cutting according to (a) and the establishment according to (b) may be controlled based on the comparison with the vector.

According to this, the communication terminal can compare the communication quality of the communication with the base station before roaming and the communication quality with the base station after roaming, and can perform roaming at an appropriate timing. Therefore, when roaming between base stations, the communication terminal can appropriately determine a modulation coding method suitable for wireless communication with the base station and roam at an appropriate timing.

In order to solve the above problems, the processing method according to one aspect of the present invention is a processing method executed by a communication terminal provided with a communication interface for wireless communication, and the communication interface provides a communication link with a first base station. In the established state, the radio communication radio wave transmitted by the second base station is intercepted by the communication interface, and the calculation step of calculating the first vector which is the error vector of the signal point included in the intercepted radio wave. Of the plurality of modulation coding methods that can be used for wireless communication between the communication interface and the second base station, the first vector falls within the allowable range of the error vector predetermined for the modulation coding method. It includes a determination step of determining the modulation coding method to which it belongs as the modulation coding method used for wireless communication between the communication interface and the second base station.

According to this, the same effect as that of the communication terminal is obtained.

In order to solve the above problems, the program according to one aspect of the present invention is a program for causing a computer to execute the above processing method.

According to this, the same effect as that of the communication terminal is obtained.

It should be noted that the present invention can be realized not only as an apparatus, but also as a method in which the processing means constituting the apparatus is used as a step, as a program for causing a computer to execute those steps, or as a computer reading in which the program is recorded. It can be realized as a possible recording medium such as a CD-ROM, or as information, data or a signal indicating the program. Then, those programs, information, data and signals may be distributed via a communication network such as the Internet.

According to the present invention, when roaming between base stations, the communication terminal can determine a modulation coding method suitable for wireless communication with the base station before the start of roaming.

FIG. 1 is an explanatory diagram showing a configuration of a communication system according to an embodiment. FIG. 2 is an explanatory diagram showing a configuration of a communication terminal according to an embodiment. FIG. 3 is an explanatory diagram of the error vector. FIG. 4 is a first explanatory diagram of a signal point included in a radio wave intercepted by a communication IF (interface) according to an embodiment and an allowable range of an error vector. FIG. 5 is a second explanatory diagram of a signal point included in the radio wave intercepted by the communication IF according to the embodiment and an allowable range of the error vector. FIG. 6 is an explanatory diagram showing a table showing an appropriate communication rate for each base station according to the embodiment. FIG. 7 is a flow chart showing processing of the communication terminal according to the embodiment.

Hereinafter, embodiments will be specifically described with reference to the drawings.

Each of the embodiments described below shows a preferred specific example of the present invention. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present invention will be described as arbitrary components constituting the more preferable form. The same components may be designated by the same reference numerals and description thereof may be omitted.

(Embodiment)
In the present embodiment, a communication terminal or the like that appropriately determines a modulation coding method suitable for wireless communication with a base station when roaming between base stations will be described.

FIG. 1 is an explanatory diagram showing a configuration of a communication system 1 according to the present embodiment.

As shown in FIG. 1, the communication system 1 includes base stations A1 and A2 (also referred to as base station A1 and the like). The base stations A1 and A2 are communicably connected by the network N. Further, the communication terminals S1 and S2 (also referred to as communication terminals S1 and the like) are communicably connected to the base stations A1 and A2, respectively. In the communication system 1 according to the present embodiment, a case where the number of base stations A1 and the like is two will be described as an example, but the same description holds true even when there are three or more base stations. The network N and the communication terminals S1 and S2 may or may not be included in the communication system 1.

The base station A1 is a wireless communication base station (for example, an access point). The base station A1 establishes a communication link L1 for wireless communication with the communication terminal S1 and can communicate with the communication terminal S1 through the communication link L1. The wireless communication standard of the base station A1 is, for example, the IEEE802.11 series (IEEE802.11a, b, g, n, etc.). Further, the base station A1 is communicably connected to the base station A2 by the network N. In addition, another network (not shown) may be connected to the network N. In this case, the communication terminal S1 connected to the base station A1 can communicate via the base station A1 and another network. Other networks may include local area networks such as offices or factories, the Internet, and the like.

The base station A2 is a base station having the same function as the base station A1 and operates independently of the base station A1. The communicable area of the base station A2 is adjacent to the communicable area of the base station A1, and may partially overlap.

The communication terminal S1 or the like is a communication terminal that establishes a communication link with any of the base stations A1 and the like and communicates with the base station A1 and the like through the communication link. The communication standard that can be used by the communication terminal S1 is the same as the communication standard of the base station A1 and the like.

FIG. 1 shows a state in which the communication terminal S1 has established a communication link L1 with the base station A1, and the communication terminal S2 has established a communication link L2 with the base station A2. In this state, the configuration and processing of the communication terminal S1 will be described assuming that the communication terminal S1 disconnects the communication link L1 and establishes a new communication link L3 with the base station A2.

FIG. 2 is an explanatory diagram showing the configuration of the communication terminal S1 according to the present embodiment.

As shown in FIG. 2, the communication terminal S1 includes a communication IF (interface) 11, a calculation unit 12, a determination unit 13, and a control unit 14. The calculation unit 12, the determination unit 13, and the control unit 14 can be realized by the processor executing a predetermined program using the memory.

The communication IF 11 is a communication interface for wireless communication with any of the base stations A1 and the like. The communication standard of the communication IF11 is, for example, the IEEE802.11 series (IEEE802.11a, b, g, n, etc.). It is assumed that the communication IF 11 initially establishes a communication link L1 with the base station A1, then disconnects the communication link L1 and establishes a communication link L3 with the base station A2 (). See Figure 1). The base station A1 corresponds to the first base station, and the base station A2 corresponds to the second base station.

The calculation unit 12 intercepts the radio wave of the wireless communication transmitted by the base station A2 by the communication IF11 in a state where the communication IF11 establishes the communication link L1 with the base station A1, and the signal point included in the intercepted radio wave. It is a processing unit that calculates the error vector (also called the first vector) of. The radio wave of wireless communication transmitted by the base station A2 is, for example, a radio wave related to a communication frame (control frame, data frame, etc.) of wireless communication. The destination of the communication frame is, for example, the communication terminal S2, but is not limited to this. The error vector of the signal point will be described in detail later.

When the communication channel of the radio communication of the base station A1 (also simply referred to as a channel) and the channel of the base station A2 are the same, the calculation unit 12 determines when the communication IF 11 is communicating with the base station A1. By analyzing the received radio wave, the radio wave transmitted by the base station A2 can be acquired, and this process corresponds to the above interception. On the other hand, when the channel of the base station A1 and the channel of the base station A2 are different, the calculation unit 12 temporarily transfers the channel of the communication IF 11 to the channel of the base station A2 while maintaining the state in which the communication link L1 is established. It is possible to receive the radio wave transmitted by the base station A2 by setting the target. Then, by analyzing the radio wave received in this way, the radio wave transmitted by the base station A2 can be acquired, and this process corresponds to the above-mentioned interception.

The communication terminal according to the present embodiment will be described on the premise that there is only one communication IF 11, but may include two or more communication IFs. In this case, even if the channel of the base station A1 and the channel of the base station A2 are different, one communication IF maintains a state in which a communication link is established with the channel of the base station A1 while maintaining the other. The communication IF can acquire (intercept) the radio wave transmitted by the base station A2 on the channel of the base station A2. That is, the communication terminal can always receive the radio waves transmitted by the base station A2 without temporarily setting the channel of the base station A2.

In the determination unit 13, among a plurality of modulation coding methods that can be used for wireless communication between the communication IF 11 and the base station A2, the first vector belongs to the allowable range of the error vector predetermined for the modulation coding method. This is a processing unit that determines the modulation coding method used as the modulation coding method used for wireless communication between the communication IF11 and the base station A2. The modulation coding method is also generally called MCS (Modulation and Coding Scheme), and indicates a communication method defined by a combination of a modulation method, a coding rate, and the like. Modulation methods include, for example, QPSK (Quadrature Phase shift Keying), 8PSK (Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and the coding rate is, for example, 1/2, 2/3/3/3/. There are 5/6 and so on.

The control unit 14 is a processing unit that controls the establishment and disconnection of a communication link by the communication IF 11. Specifically, the control unit 14 controls to disconnect the communication link L1 between the communication IF 11 and the base station A1. Further, the control unit 14 establishes a communication link L3 between the communication IF 11 and the base station A2 after disconnecting the communication link L1, and uses the modulation coding method determined by the determination unit 13 to connect the communication IF 11 to the base station. Controls communication with A2.

Further, the control unit 14 can also control the timing of controlling the establishment and disconnection (that is, roaming) of the communication link by the communication IF 11. For example, the control unit 14 calculates the second vector, which is an error vector of the signal point included in the radio wave received from the base station A1, by the calculation unit 12, and compares the calculated second vector with the first vector. Based on the above, the timing of disconnecting the communication link L1 with the base station A1 and establishing the communication link L3 with the base station A2 is controlled. More specifically, the control unit 14 may compare the EVM of the second vector and the EVM of the first vector, and control to roam when the EVM of the first vector is smaller. Further, roaming may be controlled when the EVM of the second vector is equal to or less than a predetermined value, or roaming may be controlled when the EVM of the first vector is equal to or more than a predetermined value. You may. EVM will be described in detail in the description of FIG.

In addition, the calculation unit 12 repeatedly intercepts the radio wave of the wireless communication transmitted by the base station A2 in a state where the communication link L1 is established with the base station A1, and each time the intercepted radio wave is intercepted. The first vector may be calculated based on. In that case, the determination unit 13 determines the modulation coding method used for communication with the base station A2 each time the calculation unit 12 calculates the first vector. The interception interval is, for example, about 100 msec to several seconds, but is not limited to this.

Next, the error vector will be described with reference to FIG.

In FIG. 3, the error vector is represented on the complex plane which is the constellation space. The error vector generally means a vector in the constellation space from the signal point defined for the modulation method to the signal point related to the signal received in the actual wireless communication. Here, the signal point defined for the modulation method is an ideal signal point in the modulation method, and corresponds to the reference signal point shown in FIG. Further, the signal point related to the signal received in the actual wireless communication corresponds to the measurement signal point shown in FIG.

The magnitude of the error vector is generally called EVM and can be used as an index of the signal quality of wireless communication. EVM is an index showing the degree to which a signal or signal point received in actual wireless communication deviates from an ideal signal or signal point. The larger the error vector, the larger the deviation of the measurement signal point from the reference signal point, and conversely, the smaller the error vector, the smaller the deviation of the measurement signal point from the reference signal point. It can be said that the signal received in the actual wireless communication is deformed from the ideal signal due to noise mixing or delay, and the degree of the deformation is indicated by EVM.

The communication frame related to wireless communication is normally received if the amount of noise mixing or delay is less than a predetermined amount. At this time, the EVM of the wireless communication corresponding to the received communication frame shows how much the signal received in the actual wireless communication is deformed from the ideal signal. Therefore, even when the communication frame is normally received, the quality of the wireless communication for each communication frame can be evaluated by EVM. That is, the smaller the size of the EVM, the more it can be evaluated that the modulation method actually used in the wireless communication can perform wireless communication with a more suitable modulation method in the surrounding wireless environment.

FIG. 4 is a first explanatory diagram of a signal point included in the radio wave intercepted by the communication IF 11 according to the present embodiment and an allowable range of the error vector. Here, it is assumed that three modulation coding methods can be used for wireless communication between the communication IF 11 and the base station A2. As for the three modulation coding methods, it is assumed that the modulation method is QPSK and there are three types of coding rates.

In FIG. 4, signal points 31 and 32, an error vector 33, and allowable ranges 35, 36, and 37 for each modulation coding method are shown on the complex plane which is the constellation space.

The signal point 31 is a signal point defined for QPSK and corresponds to a reference signal point in FIG.

The signal point 32 is a signal point included in the radio wave intercepted by the communication IF 11 calculated by the calculation unit 12, and corresponds to the measurement signal point in FIG.

The error vector 33 is a vector starting from the signal point 31 and ending at the signal point 32, and corresponds to the error vector in FIG.

The tolerance ranges 35, 36, and 37 indicate the tolerances of the error vectors predetermined for the three modulation coding methods, respectively. The allowable ranges 35, 36, and 37 have larger dimensions in the constellation space as the modulation coding method has a smaller coding rate, that is, the modulation coding method having a slower communication speed. Each of the tolerances 35, 36 and 37 is generally represented as a circle in the constellation space, in which case the above dimensions can be represented by the radius of the circle indicating the tolerance. The predetermined error vector allowable range may be specifically defined by (1) a communication standard (for example, IEEE802.11a, b, g, n, etc.), or (2) a base. It may be based on the result of learning the correspondence between the quality of wireless communication performed with the station and the error vector. In the case of (1) above, the allowable range of the error vector may be set at the time of shipment from the factory or before the network administrator starts using the communication terminal, and in the case of (2) above, communication may be set. It may be determined after communication between the terminal and the base station has been performed for a certain period of time.

More specifically, the allowable range 35 is the tolerance of the error vector for the modulation coding method corresponding to the coding method having the lowest coding rate among the three modulation coding methods, that is, the slowest communication speed. The range. Here, the modulation coding method corresponding to the allowable range 35 is also referred to as, for example, MCS1. The permissible range 35 is represented by a circle centered on the signal point 31 in the constellation space, and the radius of the circle is the largest of the above three permissible ranges.

The permissible range 36 is an error vector permissible range for a modulation coding method corresponding to a coding method having a medium coding rate, that is, a medium communication speed among the three modulation coding methods. .. The modulation coding method corresponding to the allowable range 36 is also referred to as, for example, MCS2. The permissible range 36 is represented by a circle centered on the signal point 31 on the constellation space, and the radius of the circle is medium among the above three permissible ranges.

The permissible range 37 is the permissible range of the error vector for the modulation coding method corresponding to the coding method having the highest coding rate among the three modulation coding methods, that is, the fastest communication speed. The modulation coding method corresponding to the allowable range 37 is also referred to as, for example, MCS3. The permissible range 37 is represented by a circle centered on the signal point 31 in the constellation space, and the radius of the circle is the smallest of the above three permissible ranges.

The calculation unit 12 calculates the position of the signal point included in the radio wave from the base station A2 intercepted by the communication IF 11 in the constellation space, and whether or not the position belongs to the allowable ranges 35, 36, and 37. That is, it is determined whether or not it is within the allowable range area.

For example, the calculation unit 12 determines whether or not the error vector 33 belongs to the permissible range 35, 36, and 37, respectively. In the example shown in FIG. 4, the calculation unit 12 determines that the error vector 33 belongs to any of the allowable ranges 35, 36, and 37. This corresponds to the fact that communication by the modulation coding method corresponding to the allowable range 35, 36 or 37 is suitable for communication between the communication terminal S1 and the base station A2. In this case, it can be said that communication by the modulation coding method corresponding to the allowable range 37 having the highest communication speed among the allowable ranges 35, 36 and 37 is most suitable.

Further, the calculation unit 12 may determine whether or not the error vector belongs to the permissible range in order from the smallest permissible range. Specifically, the calculation unit 12 determines whether or not the error vector belongs to the smallest allowable range 37 among the allowable ranges 35, 36, and 37. As a result of the determination, the calculation unit 12 determines that the error vector belongs to the allowable range 37. This corresponds to the fact that communication by the modulation coding method corresponding to the allowable range 37 is most suitable for communication between the communication terminal S1 and the base station A2.

It should be noted that the determination unit 13 may determine the modulation coding method using the tolerance range defined for each of the plurality of modulation coding methods as the allowable range of the error vector predetermined for the modulation coding method. Good. Specifically, the allowable ranges 35, 36, and 37 may use the allowable ranges specified by the communication standard for each of the three modulation coding methods. The permissible range defined by the communication standard may be, for example, a fixed range that does not fluctuate with time. Thereby, the determination unit 13 can determine an appropriate modulation coding method by utilizing the standard allowable range defined for the modulation coding method.

Further, the determination unit 13 creates learning data by learning (a) the correspondence between the quality of wireless communication by the communication IF11 at the past time point and the first vector acquired based on the radio wave intercepted at that time point. Then, (b) the predetermined tolerance range for each of the plurality of modulation coding methods is changed based on the learning data, and (c) the modulation coding method is dynamically determined using the changed tolerance range. Good. As a result, the determination unit 13 can determine an appropriate modulation coding method by using the tolerance range that reflects the actual communication quality in the past with respect to the standard tolerance range for the modulation coding method.

FIG. 5 is a second explanatory diagram of a signal point included in the radio wave intercepted by the communication IF 11 according to the present embodiment and an allowable range of the error vector.

In FIG. 5, as compared with the case of FIG. 4, the signal point 32a in the first quadrant does not belong to the permissible range 37 and is located outside the permissible range 37. The signal point 32a belongs to the allowable ranges 35 and 36.

In this case, the calculation unit 12 determines that the error vector 33a belongs to any of the allowable ranges 35 and 36. This corresponds to the fact that communication by the modulation coding method corresponding to the allowable range 35 or 36 is suitable for communication between the communication terminal S1 and the base station A2. In this case, it can be said that communication by the modulation coding method corresponding to the allowable range 36 having the highest communication speed among the allowable ranges 35 and 36 is most suitable.

Further, when the calculation unit 12 determines whether or not the error vector belongs to the permissible range in order from the smallest permissible range, the error vector 33a does not belong to the permissible range 37, and the permissible range 36 It is determined that the error vector 33a belongs to. This corresponds to the fact that communication by the modulation coding method corresponding to the allowable range 36 is most suitable for communication between the communication terminal S1 and the base station A2.

FIG. 6 is an explanatory diagram showing a table showing an appropriate modulation coding method for each base station according to the present embodiment.

In the table shown in FIG. 6, the base station and the modulation coding method are associated with each other. The modulation coding method shown in the above table is a modulation coding method determined by the determination unit 13 to be suitable for communication between the base station and the communication IF 11. The base stations shown in the above table include a base station (for example, base station A1) to which the communication IF11 has established a communication link and a base station (for example, base station A2) for which a communication link has not been established. Is shown.

Specifically, it has been shown that it is appropriate to use MCS3 as the modulation coding method for communication with the base station A1. This can be determined by the error vector calculated from the radio wave of the wireless communication received by the communication IF 11 from the base station A1.

Further, it has been shown that it is appropriate to use MCS2 as the modulation coding method for communication with the base station A2. This can be determined by an error vector calculated from the radio wave of the wireless communication intercepted by the base station A2 while the communication IF11 maintains the communication link L1 with the base station A1.

When the control unit 14 establishes the communication link L3 with the base station A2, the control unit 14 can refer to the table shown in FIG. 6 and communicate using the MCS2 immediately after the establishment. As a result, after the communication link L3 between the communication IF11 and the base station A2 is established, communication with a plurality of modulation coding methods is tried in order to obtain an appropriate modulation coding method, and communication quality and the like are not appropriate. Can be suppressed.

FIG. 7 is a flow chart showing processing of the communication terminal S1 according to the present embodiment.

In step S101, the communication IF 11 establishes a communication link L1 with the base station A1.

In step S102, the communication IF 11 intercepts the radio wave of the wireless communication transmitted by the base station A2 in a state where the communication IF 11 establishes the communication link L1 with the base station A1.

In step S103, the calculation unit 12 calculates the first vector, which is the error vector of the signal point included in the radio wave intercepted in step S102.

In step S104, among a plurality of modulation coding methods that can be used for wireless communication between the communication IF 11 and the base station A2, the first calculation in step S103 is within the allowable range of the error vector predetermined for the modulation coding method. The modulation coding method to which one vector belongs is determined as the modulation coding method used for wireless communication between the communication IF11 and the base station A2.

In step S105, the communication IF 11 disconnects the communication link L1 with the base station A1 and establishes the communication link L3 with the base station A2 under the control of the control unit 14, and the modulation coding determined in step S104. The method is used to communicate with the base station A2. It should be noted that the execution of step S105 is not essential. This is because even if step S105 is not executed, the effect that a modulation coding method suitable for wireless communication with the base station is determined before the start of roaming is obtained.

In this way, the communication terminal S1 can appropriately determine a modulation coding method suitable for wireless communication with the base station when roaming between the base stations. In addition, wireless communication with the base station can be performed using the determined appropriate modulation coding method.

As described above, the communication terminal according to the present embodiment is suitable for communication with the second base station by using the error vector of the radio wave from the second base station while establishing the communication link with the first base station. Modulation coding method is determined in advance. If it is determined in this way, when establishing a communication link with the second base station thereafter, it is determined in advance and appropriate without performing processing such as a communication trial for determining an appropriate modulation coding method. Communication can be performed using a modulation coding method. In this way, when roaming between base stations, the communication terminal can determine a modulation coding method suitable for wireless communication with the base station before the start of roaming.

Further, the communication terminal repeatedly determines a modulation coding method that can be appropriately used for communication with the second base station. Therefore, the communication terminal can determine a modulation coding method suitable for a relatively new environment even when the surrounding wireless environment is fluctuating. Therefore, the communication terminal can appropriately determine the modulation coding method suitable for wireless communication with the base station while considering the surrounding wireless environment.

Further, the communication terminal communicates by a predetermined modulation coding method after roaming from the first base station to the second base station. If the modulation coding method is not determined in advance, the communication terminal has a communication quality or communication speed that is not suitable for wireless communication with the second base station until an appropriate modulation coding method is determined. It will communicate. Therefore, the communication terminal can appropriately determine a modulation coding method suitable for wireless communication with the base station, and can suppress communication in which communication quality and the like are not appropriate.

Further, the communication terminal more easily determines the modulation coding method by using the allowable range defined for the modulation coding method. When roaming between base stations, the communication terminal can more easily determine a modulation coding method suitable for wireless communication with the base station.

Further, the communication terminal more easily determines the modulation coding method by reflecting the result of learning based on the actual communication quality in the past in the predetermined allowable range for the modulation coding method. When roaming between base stations, the communication terminal can more easily determine a modulation coding method suitable for wireless communication with the base station.

Further, the communication terminal can compare the communication quality of the communication with the base station before roaming and the communication quality with the base station after roaming, and perform roaming at an appropriate timing. Therefore, when roaming between base stations, the communication terminal can appropriately determine a modulation coding method suitable for wireless communication with the base station and roam at an appropriate timing.

It should be noted that the present invention can be realized not only as an apparatus, but also as a method in which the processing means constituting the apparatus is used as a step, as a program for causing a computer to execute those steps, or as a computer reading in which the program is recorded. It can be realized as a possible recording medium such as a CD-ROM, or as information, data or a signal indicating the program. Then, those programs, information, data and signals may be distributed via a communication network such as the Internet.

Although the communication terminal and the like of the present invention have been described above based on the embodiment, the present invention is not limited to this embodiment. As long as the gist of the present invention is not deviated, various modifications that can be conceived by those skilled in the art are applied to the present embodiment, and a form constructed by combining components in different embodiments is also included in the scope of the present invention. ..

The present invention can be used in communication terminals such as computers, smartphones and tablets.

1 Communication system 11 Communication IF
12 Calculation unit 13 Decision unit 14 Control unit 31, 32, 32a Signal point 33, 33a Error vector 35, 36, 37 Tolerance range A1, A2 Base station L1, L2, L3 Communication link N network S1, S2 Communication terminal

Claims (8)

A communication interface for wireless communication and
In a state where the communication interface establishes a communication link with the first base station, the radio wave of wireless communication transmitted by the second base station is intercepted by the communication interface, and the signal point included in the intercepted radio wave A calculation unit that calculates the first vector, which is an error vector,
Among a plurality of modulation coding methods that can be used for wireless communication between the communication interface and the second base station, the first vector belongs to the allowable range of an error vector predetermined for the modulation coding method. A communication terminal including a determination unit that determines a modulation coding method to be used as a modulation coding method used for wireless communication between the communication interface and the second base station. The calculation unit
In the above state, the radio wave of the wireless communication transmitted by the second base station is repeatedly intercepted, and each time the radio wave is intercepted, the first vector is calculated based on the intercepted radio wave.
The decision unit
The communication terminal according to claim 1, wherein each time the calculation unit calculates the first vector, the modulation coding method used for communication with the second base station is determined. The communication terminal further
(A) The communication link between the communication interface and the first base station is disconnected.
(B) A communication link between the communication interface and the second base station is established, and the communication interface is made to communicate with the second base station by using the modulation coding method determined by the determination unit. The communication terminal according to claim 1 or 2, further comprising a control unit for controlling. The communication terminal according to any one of claims 1 to 3, wherein the determination unit determines the modulation coding method using the permissible range defined for each of the plurality of modulation coding methods. The decision unit
(C) Learning data is created by learning the correspondence between the quality of wireless communication by the communication interface at a past time point and the first vector acquired based on the radio wave intercepted at the time point.
(D) The permissible range predetermined for each of the plurality of modulation coding methods is changed based on the learning data.
(E) The communication terminal according to any one of claims 1 to 3, wherein the modulation coding method is determined by using the modified allowable range. The calculation unit further
The second vector, which is the error vector of the signal point included in the radio wave received from the first base station, is calculated.
The third aspect of claim 3, wherein the control unit controls the timing of performing the cutting according to (a) and the establishment according to (b) based on the comparison between the second vector and the first vector. Communication terminal. It is a processing method executed by a communication terminal equipped with a communication interface for wireless communication.
In a state where the communication interface establishes a communication link with the first base station, the radio wave of wireless communication transmitted by the second base station is intercepted by the communication interface, and the signal point included in the intercepted radio wave A calculation step for calculating the first vector, which is an error vector, and
Among a plurality of modulation coding methods that can be used for wireless communication between the communication interface and the second base station, the first vector belongs to the allowable range of an error vector predetermined for the modulation coding method. A processing method including a determination step of determining a modulation coding method to be used as a modulation coding method used for wireless communication between the communication interface and the second base station. A program for causing a computer to execute the processing method according to claim 7.

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