JP2018164202A - Communication device, base station selection method, and base station selection program - Google Patents

Abstract

A communication apparatus capable of selecting a handover destination candidate cell by a moving apparatus alone is provided.
A multidimensional antenna 81 receives a radio wave transmitted from a base station. The relative position calculation unit 82 calculates the relative position between the mobile communication device 80 that moves and the base station from the difference between the reception time and the reception power of the radio wave received by the multidimensional antenna 81. The speed direction calculation unit 83 calculates the relative moving speed and moving direction between the base station and the communication apparatus 80 from each difference between the relative positions calculated a plurality of times in time series. The base station selection unit 84 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.
[Selection] Figure 8

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, a base station selection method, and a base station selection program that select a handover destination candidate cell during movement.

  When the communication device moves, it is desirable that the communication device can select a cell in its 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 Literature 1 selects a cell with the highest reference signal reception quality (a cell with the highest reference signal reception power) from the detected cells.

  Moreover, it is desirable that an optimal 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 for 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 JP 2016-130692 A

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

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

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

  The communication device according to the present invention is based on the difference between the multidimensional antenna that receives the radio wave transmitted from the base station, and the reception time and reception power of the radio wave received by the multidimensional antenna. A relative position calculation unit that calculates a relative position, and a speed direction calculation unit that calculates a relative movement speed and a movement direction between the base station and the communication apparatus from each difference between the relative positions calculated a plurality of times in time series, And a base station selecting section 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.

  A base station selection method according to the present invention receives a radio wave transmitted from a base station with a multidimensional antenna, and determines the difference between the reception time and the received power of the radio wave received with the multidimensional antenna. When the relative speed of the base station and the communication device are calculated from the difference between the relative positions calculated multiple times in time series, the relative movement speed and the movement direction are calculated, and the movement speed exceeds a predetermined speed. In addition, a base station corresponding to a cell in the moving direction is selected as a handover destination base station.

  The base station selection program according to the present invention allows a computer to calculate a relative position between a moving own computer and the base station based on a difference in reception time and reception power of a radio wave received from a base station received by a multidimensional antenna. Position calculation processing, speed direction calculation processing for calculating the relative moving speed and moving direction between the base station and the own computer from each difference of the relative position calculated multiple times in time series, and the moving speed is a predetermined speed The base station selection process for selecting the base station corresponding to the cell in the moving direction as the handover destination base station is executed.

  According to the present invention, a handover destination candidate cell can be selected by a 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 the other example of the method of specifying a moving direction. It is explanatory drawing which shows the example of the process which selects a cell. It is explanatory drawing which shows the operation example in which a handover is performed. It is a flowchart which shows the operation example of a communication apparatus. It is a block diagram which shows the outline | summary 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 apparatus according to the present invention. The communication apparatus 100 of this embodiment includes an antenna 11, a relative position calculation unit 12, a speed 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 a base station. The antenna 11 receives radio waves such as Reference or Synchronized Signal periodically transmitted from the base station, for example. 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 reception antennas or two or more planar array antennas. The antenna 11 is configured by a receiving antenna that can detect reception from all directions, 360 degrees in all directions.

  Note that the radio wave detected by the antenna 11 may not 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 reception time and reception power of radio waves periodically received by the antenna 11.

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

  If 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 a distance difference between the antenna 22 and the base station 200 when compared with the antenna 21.

The time difference which has received the same signal at the antenna 21 and the antenna 22 is t, when the speed of light (per second 300,000 km) and c _0, distance difference x is calculated by x = t × c _0. In recent years, measurement can be performed in units of 1.0 × 10 ⁻¹² picoseconds, and it can be measured that radio waves (light) travel 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 that is a radio wave transmission source is θ, and the antenna from which the signal arrives first (in the example shown in FIG. Let the distance to be r. At this time, the relative position of the communication device 100 can be calculated from the relationship shown in FIG. 2B indicating Pythagorean theorem a ² + b ² = c ² using Equation 1 below.

  Since θ and r are unknown at the time of radio wave reception, θ and r satisfying Equation 1 can be obtained by a three-dimensional curved surface. Further, when the number of antennas is two, the position of the base station cannot be uniquely determined. However, when the number of antennas is three, a curve indicating the relationship between θ and r can be obtained from the simultaneous equation of Equation 1 above. When there are four antennas, θ and r can be obtained at one point from three simultaneous equations.

  In FIG. 2, the above formula 1 is defined with the distance between the antenna 21 and the antenna 22 being 1. Therefore, the relative position can be calculated in the same manner by clarifying the positional relationship between the receiving antennas.

  As described above, in general, when there are three or less antennas, it is difficult to correctly recognize the reception 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 between the relative positions calculated a plurality of times. If a plurality of relative positions can be acquired in time series, the moving speed and moving direction can be calculated. The speed direction calculation unit 13 calculates a 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 illustrating an example of a method for specifying a moving direction from each difference in relative position. FIG. 3A shows a situation in which the communication apparatus 100 moves while the positions of the two base stations 200 and 300 are fixed. FIG. 3B shows a situation where the two base stations 200 and 300 are assumed to move while the position of the communication device 100 is fixed. In either case shown in FIG. 3 (a) or FIG. 3 (b), by measuring the relative position between the communication device and the base station, in which direction the communication device is moving with respect to the base station (Movement direction indicated by arrows A and B) can be specified.

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

  Referring to FIG. 4 (b), the direction of the base station has changed greatly. Here, if there is a premise that the base station 200 and the base station 300 do not move, the relative position with respect to the base station 100 is changed by removing the rotation difference by overlapping the sides of the base station 200 and the base station 300. You can see that there is no.

  That is, assuming that the base station does not move in a short period of time, the relative position with respect to the base station using the period (interval) of receiving radio waves, regardless of the direction and direction of communication device 100 By obtaining the relationship, it is possible to obtain the relative moving speed and moving direction with respect 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. For example, the cell radius estimation unit 14 may calculate the amount of attenuation of received power to estimate the cell radius. In the present embodiment, it is assumed that the cell radius does not change greatly in a short period of time.

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

  Specifically, the base station selection unit 15 measures reception power and reception quality by a generally known method, and determines whether the measured value exceeds a predetermined threshold value. Examples of the reception quality include a signal to interference ratio (SIR), a reference signal (RSRP), a reference signal received quality (RSRQ), and a block error rate (BLER). Block Error Rate).

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

  FIG. 5 is an explanatory diagram illustrating an example of processing for selecting a cell. For example, it is assumed that the communication device 100 is present in a car that is 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 around the communication device 100. In this case, the base station selection unit 15 specifies a cell of the base station 300 in which the moving direction and the direction of the received radio wave are within a certain angle as shown by a thick frame in FIG. 5 as a handover destination candidate cell. The base station 300 is selected.

  When the cell radius is estimated, the base station selection unit 15 selects a base station having the estimated cell radius equal to or greater than a predetermined threshold. By selecting such a cell, it is possible to exclude the selection of a cell having a small cell radius that causes switching immediately.

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

  In this embodiment, the base station notifies the measurement result from the communication device 100 to the base station before selecting the handover destination. At that time, the base station selection unit 15 may notify not only the content of the base station selected as the handover destination but also the content of the base station that is not appropriate for the handover destination in advance. This is because the handover process is normally performed on the base station side.

  FIG. 6 is an explanatory diagram illustrating an operation example in which handover is performed. In general, for example, as shown in FIG. 6 (a), when a communication apparatus notifies a measurement value to a base station #S, the base station #S selects a cell based on the measurement value and sends a handover request to another base station. Notify station #D. On the other hand, in the present embodiment, as illustrated in FIG. 6B, the base station selection unit 15 selects a cell candidate and notifies the measurement value to the base station #S. Therefore, the base station #S that has received the notification can notify the handover request to the other base station #D in consideration of the candidate cell.

  The relative position calculation unit 12, the speed direction calculation unit 13, the cell radius estimation unit 14, and the base station selection unit 15 are realized by a CPU of a computer 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 apparatus 100, and the CPU reads the program, and in accordance with the program, the relative position calculation unit 12, the velocity direction calculation unit 13, the cell radius estimation unit 14, and the base The station selection unit 15 may operate. Further, each of 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.

  Next, the operation of the communication apparatus 100 of this embodiment will be described. FIG. 7 is a flowchart illustrating an operation example of the communication apparatus 100 according to 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 reception 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 of the received radio wave and the received power (step S13). The speed direction calculation unit 13 calculates a relative moving speed between the base station and the communication device 100 from each difference of the relative positions (step S14). The base station selection unit 15 determines whether the moving speed exceeds a predetermined speed (that is, whether the moving speed is moving at high speed) (step S15). If it is not moving at high speed (No in step S15), the process ends without selecting a base station.

  On the other hand, when moving at high speed (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 a base station corresponding to the cell in the moving direction as a handover destination base station (step S17). At that time, the base station selection unit 15 selects only those base stations whose cell radius estimated by the cell radius estimation unit 14 is equal to or greater than a predetermined threshold.

  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 between the reception time of the received radio wave and the received power. And the relative position of the base station. Then, the speed direction calculating unit 13 calculates the relative moving speed and moving direction between the base station and the communication device 100 from each difference between the relative positions calculated multiple times in time series, and the base station selecting unit 15 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 this embodiment, the handover destination is selected from the relative positional relationship between the base station and the communication device. At this time, the moving direction and moving speed of the communication apparatus 100 are measured by using the antenna (for example, a plurality of array antennas) on the communication apparatus 100 side to measure the relative position to the base station. That is, the communication apparatus 100 according to 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 privacy or personal information. On the other hand, since the communication apparatus 100 according to the present embodiment does not use GPS, it is possible to appropriately select a handover destination base station without enabling GPS.

  The communication apparatus 100 of this embodiment is implement | achieved by portable terminals, such as a smart phone, for example. That is, the antenna 11 of the present embodiment is also mounted on, for example, a mobile terminal. However, the aspect 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 a communication apparatus according to the present invention. The communication device 80 according to the present invention moves from a multidimensional antenna 81 (for example, the antenna 11) that receives a radio wave transmitted from a base station, and a difference in reception time and reception power of the radio wave received by the multidimensional antenna 81. The relative position calculation unit 82 (for example, the relative position calculation unit 12) that calculates the relative position between the local communication device 80 and the base station, and the difference between the relative positions calculated multiple times in time series, Corresponding to a cell in the moving direction when the moving speed exceeds a predetermined speed, and a speed direction calculating unit 83 (for example, a speed direction calculating unit 13) that calculates a moving speed and a moving direction relative to the communication device 80. A base station selection unit 84 (for example, the base station selection unit 15) that selects a base station as a handover destination base station.

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

  Further, the communication device 80 may include a cell radius estimation unit (for example, the 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 a handover destination base station.

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

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

  Further, the base station selection unit 84 may select a base station corresponding to a cell whose radio wave reception power and reception quality exceed a predetermined threshold.

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

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Supplementary note 1) Relative between the base station and the multi-dimensional antenna that receives the radio wave transmitted from the base station, and the difference between the reception time and the reception power of the radio wave received by the multi-dimensional antenna A relative position calculation unit that calculates a position; and a speed direction calculation unit that calculates a relative movement speed and a movement direction between the base station and the communication apparatus based on each difference between the relative positions calculated a plurality of times in time series A communication apparatus comprising: a base station selection unit that selects a base station corresponding to the 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 supports cells whose estimated cell radius is greater than or equal to a predetermined size. The communication apparatus according to appendix 1, wherein a base station to be selected is selected as a handover destination base station.

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

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

(Supplementary note 5) The communication device according to any one of supplementary notes 1 to 4, 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. .

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

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

(Supplementary note 8) Relative position between the mobile communication device and the base station is determined by receiving a radio wave transmitted from the base station with a multidimensional antenna, and a difference in reception time and reception power of the radio wave received with the multidimensional antenna. When the relative moving speed and moving direction between the base station and the communication device are calculated from each difference of the relative position calculated multiple times in time series, and the moving speed exceeds a predetermined speed And a base station corresponding to the cell in the moving direction is selected as a handover destination base station.

(Supplementary note 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 having the estimated cell radius of a predetermined size or larger is selected as the handover destination base station. The base station selection method according to attachment 8.

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

(Additional remark 11) Let a computer perform the cell radius estimation process which estimates the cell radius of a base station from the calculated relative position and received power, and the estimated cell radius is more than predetermined magnitude | size by the base station selection process Item 11. The base station selection program according to appendix 10, which selects a base station corresponding to the cell as a handover destination base station.

DESCRIPTION OF SYMBOLS 11 Antenna 12 Relative position calculation part 13 Speed direction calculation part 14 Cell radius estimation part 100 Communication apparatus 200-500 Base station

Claims (10)

A multidimensional antenna that receives radio waves transmitted from the base station;
A relative position calculation unit that calculates a relative position between the mobile communication device and the base station, from a difference in reception time and reception power of radio waves received by the multidimensional antenna;
From each difference of the relative position calculated multiple times in time series, a speed direction calculation unit that calculates a relative movement speed and a movement direction between the base station and the communication apparatus,
A communication apparatus comprising: a base station selecting 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. A cell radius estimation unit for estimating the cell radius of the base station from the calculated relative position and received power,
The communication apparatus according to claim 1, wherein the 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. The communication apparatus according to claim 1 or 2, wherein the base station selection unit selects a base station corresponding to a cell with the closest radio wave arrival direction as a handover destination base station. The communication apparatus according to any one of claims 1 to 3, wherein the base station selection unit selects a base station corresponding to a cell that falls within a certain angle. The communication apparatus according to any one of claims 1 to 4, 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. The communication device according to any one of claims 1 to 5, wherein the multidimensional antenna is at least four or more receiving antennas or two or more planar array antennas. The radio wave transmitted from the base station is received by the multidimensional antenna,
From the difference between the reception time and the reception power of the radio wave received by the multidimensional antenna, the relative position between the moving communication device and the base station is calculated,
From each difference of the relative position calculated multiple times in time series, the relative moving speed and moving direction of the base station and the communication device are calculated,
When the moving speed exceeds a predetermined speed, a base station corresponding to the cell in the moving direction is selected as a handover destination base station. From the calculated relative position and received power, the cell radius of the base station is estimated,
The base station selection method according to claim 7, wherein a base station corresponding to a cell having an estimated cell radius equal to or larger than a predetermined size is selected as a handover destination base station. On the computer,
Relative position calculation processing for calculating the relative position between the moving own computer and the base station from the difference between the reception time and the received power of the radio wave received from the base station received by the multidimensional antenna,
From each difference of the relative position calculated multiple times in time series, a speed direction calculation process for calculating a relative moving speed and moving direction between the base station and the own computer, and
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 when the moving speed exceeds a predetermined speed. On the computer,
From the calculated relative position and received power, execute a cell radius estimation process for estimating the cell radius of the base station,
The base station selection program according to claim 9, wherein a base station corresponding to a cell having an estimated cell radius greater than or equal to a predetermined size is selected as a handover destination base station in the base station selection process.

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