JP6841502B2 - Communication equipment, base station selection method and base station selection program - Google Patents

Description

The present invention relates to a communication device, a base station selection method and a base station selection program, and more particularly to a communication device for selecting a handover destination candidate cell while moving, a base station selection method and a base station selection program.

When the communication device moves, it is desirable that the communication device can select a cell in the moving direction (traveling direction) in preparation for future movement. For example, Patent Document 1 describes a communication system in which a plurality of communication terminal devices perform wireless communication. The communication system described in Patent Document 1 selects the cell having the best reception quality of the reference signal (the cell having the highest reception power of the reference signal) from the detected cells.

Further, it is desirable that the optimum cell radius and cell size can be selected according to the moving speed of the communication terminal. For example, Patent Document 2 describes a method of estimating the moving speed of a mobile station. By selecting such an optimal cell, disconnection during handover and frequent handover can be prevented.

International Publication No. 2015/015886 Japanese Unexamined Patent Publication No. 2016-130692

For example, a method of selecting an area from position information, traveling direction, and moving speed is generally known. However, in the standard standard (for example, 3GPP (Third Generation Partnership Project) W-CDMA (Wideband Code Division Multiple Access) / LTE (Long Term Evolution)), an interface for notifying the position information of the base station to the moving device side and There is no interface for exchanging location information between base stations.

Therefore, in order to realize the method described in the above-mentioned Patent Document 1 and the like in the current standard, a specific means for notifying each position information to the base station that determines the handover destination is required. Further, for example, when constructing a system in a multi-vendor environment, it becomes necessary to provide another server or the like via a common interface. Further, in some cases, it may be necessary for the operator to input data.

Therefore, an object of the present invention is to provide a communication device, a base station selection method, and a base station selection program that can select a handover destination candidate cell by a moving device alone.

The communication device according to the present invention is a multi-dimensional antenna that receives radio waves transmitted from a base station, and a moving self-communication device and a base station based on the difference in reception time and received power of radio waves received by the multi-dimensional antenna. A relative position calculation unit that calculates the relative position, and a speed direction calculation unit that calculates the relative movement speed and movement direction between the base station and the self-communication device from each difference of the relative positions calculated multiple times in time series. , When the moving speed exceeds a predetermined speed, the base station cell is selected from the base station selection unit that selects the base station corresponding to the cell in the moving direction as the handover destination base station, and the calculated relative position and received power. A cell radius estimation unit for estimating a radius is provided, and a base station selection unit selects a base station corresponding to a cell having an estimated cell radius of a predetermined size or more as a handover destination base station. ..

In the base station selection method according to the present invention, a radio wave transmitted from a base station is received by a multidimensional antenna, and a moving communication device and a base station are selected based on the difference in reception time and received power of the radio wave received by the multidimensional antenna. The relative position of the base station is calculated, the cell radius of the base station is estimated from the calculated relative position and the received power, and the relative position between the base station and the communication device is calculated from each difference of the relative positions calculated multiple times in time series. A base station that corresponds to a cell in the moving direction and corresponds to a cell having an estimated cell radius of a predetermined size or more when the moving speed exceeds a predetermined speed by calculating a moving speed and a moving direction. It is characterized in that it is selected as a base station as a handover destination.

The base station selection program according to the present invention allows a computer to calculate the relative position between a moving own computer and its base station from the difference in reception time and received power of radio waves from the base station received by a multidimensional antenna. position calculating process, when the respective differences of the calculated relative positions multiple times series, speed direction calculating processing for calculating the relative movement speed and movement direction of the base station and the own computer, moving speed is the predetermined speed When it exceeds, the base station selection process that selects the base station corresponding to the cell in the moving direction as the base station of the handover destination , and the cell radius estimation that estimates the cell radius of the base station from the calculated relative position and received power. It is characterized in that the process is executed and the base station corresponding to the cell whose estimated cell radius is equal to or larger than a predetermined size is selected as the handover destination base station in the base station selection process.

According to the present invention, a handover destination candidate cell can be selected by the moving device alone.

It is a block diagram which shows one Embodiment of the communication apparatus by this invention. It is explanatory drawing which shows the example of the method of calculating a relative position. It is explanatory drawing which shows the example of the method of specifying a moving direction. It is explanatory drawing which shows another example of the method of specifying a moving direction. It is explanatory drawing which shows the example of the process of selecting a cell. It is explanatory drawing which shows the operation example in which the handover is performed. It is a flowchart which shows the operation example of a communication device. It is a block diagram which shows the outline of the communication apparatus by this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a communication device according to the present invention. The communication device 100 of the present embodiment includes an antenna 11, a relative position calculation unit 12, a velocity direction calculation unit 13, a cell radius estimation unit 14, and a base station selection unit 15.

The antenna 11 is a multidimensional antenna that receives radio waves transmitted from the base station. The antenna 11 receives, for example, a radio wave such as a Reference or Synchronized Signal that is periodically transmitted from the base station. As will be described later, in order to appropriately calculate the reception direction of radio waves, the antenna 11 is realized by at least four or more receiving antennas or two or more planar array antennas. The antenna 11 is composed of a receiving antenna capable of detecting reception from all directions at 360 degrees in all directions.

The radio wave detected by the antenna 11 does not have to be a radio wave transmitted periodically. As long as the antenna 11 can receive a plurality of radio waves in time series, the transmission interval may be irregular.

The relative position calculation unit 12 calculates the relative position between the communication device 100 and the base station. Specifically, the relative position calculation unit 12 calculates the relative position between the moving communication device 100 and the base station from the difference in the reception time and the received power of the radio waves periodically received by the antenna 11.

FIG. 2 is an explanatory diagram showing an example of a method of calculating a relative position from a received radio wave. As shown in FIG. 2A, it is assumed that the two antennas 21 and the antenna 22 receive radio waves from the base station 200.

Assuming that the distance from the base station 200 to the antenna 21 is r, the distance y from the base station 200 to the antenna 22 is y = x + r. Here, x is the distance difference of the antenna 22 to the base station 200 when compared with the antenna 21.

Assuming that the time difference between the antenna 21 and the antenna 22 receiving the same signal is t and the speed of light (300,000 kilometers per second) is c ₀ , the distance difference x is calculated by _{x = t × c 0.} In recent years, ^{it is possible to measure in units of 1.0 × 10-12} picoseconds, and it is possible to measure that a radio wave (light) advances by 0.3 mm in 1 picosecond.

The straight line connecting the antenna 21 and the antenna 22 is one side, the angle with the base station 100 which is the source of radio waves is θ, and the antenna where the signal arrives first from the base station (antenna 21 in the example shown in FIG. 2). Let r be the distance to. At this time, from the relationship of FIG. 2 showing the Pythagorean theorem ^{a 2 + b 2 = c 2} (b), the relative position of the communication device 100 can be calculated by Equation 1 shown below.

Since θ and r are unknown at the time of receiving radio waves, θ and r satisfying the above equation 1 can be obtained by a three-dimensional curved surface. Further, when there are two antennas, the position of the base station cannot be uniquely obtained, but when there are three antennas, a curve showing the relationship between θ and r can be obtained from the simultaneous equations of the above equation 1. Then, when there are four antennas, θ and r can be obtained at one point from three simultaneous equations.

In FIG. 2, the above equation 1 is defined with the distance between the antenna 21 and the antenna 22 being 1. Therefore, by clarifying the positional relationship of each receiving antenna, it is possible to calculate the relative position in the same manner.

As described above, when the number of antennas is three or less, it is difficult to correctly recognize the receiving direction, although it depends on the type of antenna. Further, it is preferable that the four antennas are configured to form a triangular pyramid so that a difference is generated between the radio wave transmission source and each antenna.

The speed direction calculation unit 13 calculates the relative moving speed and moving direction between the base station and the communication device 100 from each difference of the relative positions calculated a plurality of times. If a plurality of relative positions can be obtained in a time series, it is possible to calculate the moving speed and the moving direction. The speed direction calculation unit 13 calculates the relative moving speed based on the distance calculated from the difference between the time interval at which the radio wave is detected and the relative position.

FIG. 3 is an explanatory diagram showing an example of a method of specifying a moving direction from each difference of relative positions. FIG. 3A shows a situation in which the communication device 100 moves with the positions of the two base stations 200 and 300 fixed. Further, FIG. 3B shows a situation in which the position of the communication device 100 is fixed and the two base stations 200 and 300 are assumed to move. In both cases shown in FIGS. 3 (a) and 3 (b), the direction in which the communication device is moving with respect to the base station is determined by measuring the relative position between the communication device and the base station. (Movement direction indicated by arrows A and B) can be specified.

FIG. 4 is an explanatory diagram showing another example of a method of specifying a moving direction from each difference of relative positions. FIG. 4 shows a situation in which only the orientation of the communication device is changed (rotated). Similar to the contents shown in FIG. 3, FIG. 4A shows a situation in which the communication device 100 rotates with the positions of the two base stations 200 and 300 fixed. Further, FIG. 4B shows a situation in which the position of the communication device 100 is fixed and the two base stations 200 and 300 are assumed to move in the rotational direction.

With reference to FIG. 4B, the direction of the base station has changed significantly. Here, if it is assumed that the base station 200 and the base station 300 do not move, the side consisting of the base station 200 and the base station 300 is overlapped and the difference in rotation is removed to change the position relative to the base station 100. It turns out that there is no.

That is, assuming that the base station does not move in a certain short period of time, the position relative to the base station using the period (interval) for receiving radio waves regardless of the direction and direction in which the communication device 100 advances. By finding the relationship, it is possible to find the moving speed and moving direction relative to the base station.

The cell radius estimation unit 14 estimates the cell radius of the base station from the calculated relative position and received power. The method by which the cell radius estimation unit 14 estimates the cell radius of the base station is arbitrary. The cell radius estimation unit 14 may estimate the cell radius by calculating the amount of attenuation of the received power, for example. In this embodiment, it is assumed that the cell radius does not change significantly in a certain short period of time.

When the calculated relative moving speed exceeds a predetermined speed, the base station selection unit 15 selects the base station corresponding to the cell in the moving direction as the handover destination base station. Then, the base station selection unit 15 notifies the base station side of the contents of the selected base station.

Specifically, the base station selection unit 15 measures the received power and the reception quality by a generally known method, and determines whether or not the measured values exceed a predetermined threshold value. Examples of reception quality include signal-to-interference ratio (SIR), reference signal (RSRP: Reference Signal Received Power), reference signal reception quality (RSRQ: Reference Signal Received Quality), and block error rate (BLER:). Block Error Rate) and so on.

Next, the base station selection unit 15 determines whether or not the calculated relative moving speed exceeds a predetermined speed (that is, is moving at high speed). When not moving at high speed, the base station selection unit 15 performs the handover with priority given to the strength of the received power from the base station and the reception quality described above, as in the general method. On the other hand, during high-speed movement, the base station selection unit 15 selects a base station corresponding to a cell within a predetermined angle with respect to the traveling direction of the communication device 100 as the handover destination base station. Specifically, the base station selection unit 15 selects a neighboring base station corresponding to the cell in the direction closest to the radio wave arrival direction as the handover destination base station.

FIG. 5 is an explanatory diagram showing an example of a process of selecting a cell. For example, it is assumed that the communication device 100 is present in a vehicle moving by car and is moving at high speed in the direction of the solid line. Further, it is assumed that base stations 200 to 500 exist in the vicinity of the communication device 100. In this case, the base station selection unit 15 specifies a cell of the base station 300 whose moving direction and the direction of the received radio wave fall within a certain angle as shown by the thick frame in FIG. 5 as a candidate cell for the handover destination. , Base station 300 is selected.

When the cell radius is estimated, the base station selection unit 15 selects a base station whose estimated cell radius is equal to or larger than a predetermined threshold value. By selecting such a cell, it is possible to exclude the selection of a cell having a small cell radius that causes an immediate switchover.

Further, it is preferable that the base station selection unit 15 selects a base station whose received power and reception quality satisfy predetermined criteria even during high-speed movement.

In the present embodiment, the communication device 100 notifies the base station side of the measurement result before the base station selects the handover destination. At that time, the base station selection unit 15 may notify the handover destination by excluding in advance not only the contents of the base station selected as the handover destination but also the contents of the base station that is not appropriate for the handover destination. This is because the handover process is usually performed on the base station side.

FIG. 6 is an explanatory diagram showing an operation example in which the handover is performed. Generally, for example, as shown in FIG. 6A, when the communication device notifies the base station #S of the measured value, the base station #S selects a cell based on the measured value and sends a handover request to another base. Notify station # D. On the other hand, in the present embodiment, as shown in FIG. 6B, the base station selection unit 15 selects a cell candidate and notifies the base station #S of the measured value. Therefore, the notified base station #S can notify the other base station #D of the handover request in consideration of the candidate cell.

The relative position calculation unit 12, the velocity direction calculation unit 13, the cell radius estimation unit 14, and the base station selection unit 15 are realized by a computer CPU that operates according to a program (base station selection program). For example, the program is stored in a storage unit (not shown) of the communication device 100, the CPU reads the program, and according to the program, the relative position calculation unit 12, the velocity direction calculation unit 13, the cell radius estimation unit 14, and the base. It may operate as a station selection unit 15. Further, the relative position calculation unit 12, the velocity direction calculation unit 13, the cell radius estimation unit 14, and the base station selection unit 15 may be realized by dedicated hardware, respectively.

Next, the operation of the communication device 100 of the present embodiment will be described. FIG. 7 is a flowchart showing an operation example of the communication device 100 of the present embodiment. The antenna 11 receives the radio wave transmitted from the base station (step S11). The base station selection unit 15 selects a base station corresponding to a cell whose received power and reception quality exceed the reference (step S12).

The relative position calculation unit 12 calculates the relative position between the communication device 100 and the base station from the difference between the reception time and the received power of the received radio wave (step S13). The speed direction calculation unit 13 calculates the relative moving speed between the base station and the communication device 100 from each difference in the relative positions (step S14). The base station selection unit 15 determines whether or not the moving speed exceeds a predetermined speed (that is, whether or not the vehicle is moving at high speed) (step S15). If the vehicle is not moving at high speed (No in step S15), the process ends without selecting the base station.

On the other hand, in the case of high-speed movement (Yes in step S15), the speed direction calculation unit 13 calculates the movement direction from each difference of the relative positions (step S16). Then, the base station selection unit 15 selects the base station corresponding to the cell in the moving direction as the handover destination base station (step S17). At that time, the base station selection unit 15 selects only base stations whose cell radius estimated by the cell radius estimation unit 14 is equal to or greater than a predetermined threshold value.

As described above, in the present embodiment, the antenna 11 receives the radio wave transmitted from the base station, and the relative position calculation unit 12 moves based on the difference in the reception time and the received power of the received radio wave. And the base station are calculated. Then, the speed direction calculation unit 13 calculates the relative movement speed and movement direction between the base station and the communication device 100 from each difference of the relative positions calculated a plurality of times in the time series, and the base station selection unit 15 calculates the relative movement speed and the movement direction. , When the moving speed exceeds a predetermined speed, the base station corresponding to the cell in the moving direction is selected as the handover destination base station. Therefore, the handover destination candidate cell can be selected by the moving device alone.

That is, in the present embodiment, the handover destination is selected from the relative positional relationship between the base station and the communication device. At that time, the moving direction and moving speed of the communication device 100 are measured relative to the base station by using an antenna (for example, a plurality of array antennas) on the communication device 100 side. That is, the communication device 100 of the present embodiment does not use GPS (Global Positioning System). For example, it is assumed that some users do not enable GPS from the viewpoint that they do not want to know their privacy and personal information. On the other hand, since the communication device 100 of the present embodiment does not use GPS, the base station of the handover destination can be appropriately selected without enabling GPS.

The communication device 100 of the present embodiment is realized by, for example, a mobile terminal such as a smartphone. That is, the antenna 11 of this embodiment is also mounted on a mobile terminal, for example. However, the mode of the communication device 100 is not limited to the mobile terminal. For example, the vehicle itself may be realized as the communication device 100 of the present embodiment.

Next, the outline of the present invention will be described. FIG. 8 is a block diagram showing an outline of the communication device according to the present invention. The communication device 80 according to the present invention moves due to the difference in reception time and reception power between the multidimensional antenna 81 (for example, the antenna 11) that receives the radio waves transmitted from the base station and the radio waves received by the multidimensional antenna 81. From each difference between the relative position calculation unit 82 (for example, the relative position calculation unit 12) that calculates the relative position between the self-communication device 80 and the base station and the relative position calculated a plurality of times in time series, the base station and the self Corresponds to the speed direction calculation unit 83 (for example, the speed direction calculation unit 13) that calculates the relative movement speed and the movement direction with the communication device 80, and the cell in the movement direction when the movement speed exceeds a predetermined speed. It includes a base station selection unit 84 (for example, a base station selection unit 15) that selects a base station as a handover destination base station.

With such a configuration, the handover destination candidate cell can be selected by the moving device alone.

Further, the communication device 80 may include a cell radius estimation unit (for example, a cell radius estimation unit 14) that estimates the cell radius of the base station from the calculated relative position and received power. Then, the base station selection unit 84 may select a base station corresponding to a cell having an estimated cell radius of a predetermined size or more as the handover destination base station.

Further, the base station selection unit 84 may select the base station corresponding to the cell in the direction closest to the radio wave arrival direction as the handover destination base station.

Further, the base station selection unit 84 may select a base station corresponding to a cell that fits within a certain angle.

Further, the base station selection unit 84 may select a base station corresponding to a cell in which the reception power and reception quality of radio waves exceed a predetermined threshold value.

The multidimensional antenna 81 is at least four or more receiving antennas or two or more planar array antennas.

Some or all of the above embodiments may also be described, but not limited to:

(Appendix 1) Relative between the moving self-communication device and the base station based on the difference in reception time and received power between the multidimensional antenna that receives the radio waves transmitted from the base station and the radio waves received by the multidimensional antenna. A relative position calculation unit that calculates the position, and a speed direction calculation unit that calculates the relative movement speed and movement direction between the base station and the self-communication device from each difference of the relative positions calculated multiple times in a time series. A communication device including a base station selection unit that selects a base station corresponding to a cell in the moving direction as a handover destination base station when the moving speed exceeds a predetermined speed.

(Appendix 2) A cell radius estimation unit that estimates the cell radius of the base station from the calculated relative position and received power is provided, and the base station selection unit corresponds to a cell whose estimated cell radius is larger than a predetermined size. The communication device according to Appendix 1, which selects a base station to be used as a handover destination base station.

(Appendix 3) The communication device according to Appendix 1 or Appendix 2, wherein the base station selection unit selects the base station corresponding to the cell in the direction closest to the radio wave arrival direction as the handover destination base station.

(Supplementary note 4) The communication device according to any one of Supplementary note 1 to Supplementary note 3, wherein the base station selection unit selects a base station corresponding to a cell that fits within a certain angle.

(Supplementary Note 5) The communication device according to any one of Supplementary note 1 to Supplementary note 4, wherein the base station selection unit selects a base station corresponding to a cell whose reception power and reception quality of radio waves exceed a predetermined threshold value. ..

(Supplementary note 6) The communication device according to any one of Supplementary note 1 to Supplementary note 5, wherein the multidimensional antenna is at least four or more receiving antennas or two or more planar array antennas.

(Supplementary note 7) The communication device according to any one of Supplementary note 1 to Supplementary note 6, wherein the base station selection unit preferentially selects a base station corresponding to a cell in a moving direction over reception power and reception quality.

(Appendix 8) The radio wave transmitted from the base station is received by the multidimensional antenna, and the relative position between the moving communication device and the base station is determined from the difference in the reception time and the received power of the radio wave received by the multidimensional antenna. Is calculated, and the relative moving speed and moving direction between the base station and the communication device are calculated from each difference of the relative positions calculated a plurality of times in a time series, and the moving speed exceeds a predetermined speed. In addition, a base station selection method comprising selecting a base station corresponding to a cell in the moving direction as a handover destination base station.

(Appendix 9) The cell radius of the base station is estimated from the calculated relative position and received power, and the base station corresponding to the cell whose estimated cell radius is larger than a predetermined size is selected as the handover destination base station. The base station selection method according to Appendix 8.

(Appendix 10) Relative position calculation process for calculating the relative position between the moving own computer and the base station from the difference in reception time and received power of the radio wave received by the multidimensional antenna from the base station. A speed direction calculation process for calculating the relative movement speed and movement direction between the base station and the own computer from each difference of the relative positions calculated a plurality of times in the series, and a case where the movement speed exceeds a predetermined speed. A base station selection program for executing a base station selection process for selecting a base station corresponding to a cell in the moving direction as a handover destination base station.

(Appendix 11) The computer is made to execute a cell radius estimation process for estimating the cell radius of the base station from the calculated relative position and received power, and the estimated cell radius is equal to or larger than a predetermined size in the base station selection process. 10. The base station selection program according to Appendix 10, which selects a base station corresponding to the cell of 1 as a handover destination base station.

11 Antenna 12 Relative position calculation unit 13 Velocity direction calculation unit 14 Cell radius estimation unit 100 Communication device 200 to 500 Base station

Claims (7)

A multidimensional antenna that receives radio waves transmitted from the base station,
A relative position calculation unit that calculates the relative position between the moving self-communication device and the base station from the difference in the reception time and the received power of the radio wave received by the multidimensional antenna.
A speed direction calculation unit that calculates the relative movement speed and movement direction between the base station and the self-communication device from each difference of the relative positions calculated multiple times in a time series.
A base station selection unit that selects a base station corresponding to a cell in the moving direction as a handover destination base station when the moving speed exceeds a predetermined speed .
It is equipped with a cell radius estimation unit that estimates the cell radius of the base station from the calculated relative position and received power.
The base station selection unit is a communication device characterized in that a base station corresponding to a cell having an estimated cell radius of a predetermined size or more is selected as a handover destination base station. Base station selection unit, radio wave incident direction to select a base station corresponding to the closest direction of the cell as a handover destination base station according to claim 1 Symbol placement of the communication device. The communication device according to claim 1 or 2 , wherein the base station selection unit selects a base station corresponding to a cell that fits within a certain angle. The communication device according to any one of claims 1 to 3 , wherein the base station selection unit selects a base station corresponding to a cell whose radio wave reception power and reception quality exceed a predetermined threshold value. Multidimensional antenna communication apparatus according to any one of claims 1 to 4 is at least four or more receive antennas or two or more planar array antenna. The radio waves transmitted from the base station are received by the multidimensional antenna, and
The relative position between the moving communication device and the base station is calculated from the difference in the reception time and the received power of the radio wave received by the multidimensional antenna.
Estimate the cell radius of the base station from the calculated relative position and received power,
The relative moving speed and moving direction between the base station and the communication device are calculated from each difference of the relative positions calculated a plurality of times in the time series.
When the moving speed exceeds a predetermined speed, a base station corresponding to the cell in the moving direction and having an estimated cell radius of a predetermined size or more is selected as the handover destination base station. A base station selection method characterized by the fact that. On the computer
Relative position calculation processing that calculates the relative position between the moving own computer and the base station from the difference in the reception time and received power of the radio wave from the base station received by the multidimensional antenna.
Speed direction calculation processing that calculates the relative movement speed and movement direction between the base station and the own computer from each difference of the relative positions calculated multiple times in the time series .
A base station selection process for selecting a base station corresponding to a cell in the moving direction as a handover destination base station when the moving speed exceeds a predetermined speed , and
The cell radius estimation process for estimating the cell radius of the base station is executed from the calculated relative position and received power.
A base station selection program for executing a base station selection process for selecting a base station corresponding to a cell having an estimated cell radius of a predetermined size or more as a handover destination base station.

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