JP2010216935A - Wireless communication system, wireless communication terminal, and distance calculation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system that calculates a distance between a wireless communication terminal and a first base station apparatus, provided that the wireless communication terminal can receive signals from the first base station apparatus and a second base station apparatus having a radio communicable distance shorter than the first base station apparatus, even when location information of each base station apparatus is unknown, and to provide the wireless communication terminal and a distance calculation method. <P>SOLUTION: When the wireless communication terminal 300 receives signals from the first base station apparatus 100 and the second base station apparatus 200 having a radio communicable distance shorter than the first base station apparatus 100, it is assumed that the distance between the wireless communication terminal 300 and the second base station apparatus 200 is zero to calculate the distance between the wireless communication terminal 300 and the first base station apparatus 100. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication system such as a mobile phone service, a wireless communication terminal, and a distance calculation method.

Conventionally, as a method for calculating position information of a wireless communication terminal, a position information acquisition method using a GPS (Global Positioning System) or a CDMA (Code Division Multiple Access) communication system is known (for example, Patent Document 1, Non-Patent Document 1). Patent Document 1).
In these conventional methods, signals subjected to spread spectrum transmission using different PN (Pseudo Noise) codes are transmitted from a plurality of transmitters (GPS satellites or CDMA base station devices) that are time-synchronized. Are simultaneously received by a receiver (a GPS receiver or a CDMA terminal). The receiver performs a correlation operation between the received signal and the PN code, and obtains the timing transmitted by a specific transmitter corresponding to the PN code from the timing at which the correlation value is maximized. The receiver obtains the pseudo propagation time from the transmitter to the receiver based on its own time. From this pseudo propagation time and the propagation distance of the radio wave per unit time, the pseudo distance between the receiver and the transmitter is obtained.
The pseudo distance is calculated simultaneously for a plurality of transmitters having different PN codes, and pseudo distances to the plurality of transmitters are obtained. Based on the "pseudo distance between the receiver and each transmitter" obtained here and the "position information (coordinates)" transmitted superimposed on the transmission signal from each transmitter, the position information of the receiver is calculated. It becomes possible to do.

Hereinafter, a conventional method for calculating position information will be described in more detail.
FIG. 6 is a diagram illustrating a relationship between a signal and time in a conventional position information calculation method.
In FIG. 6, T _S is a reference time at the transmitter, T _S ′ is a reference time at the receiver, and T _i ′ is a reception time at the receiver. It is assumed that the receiver time error δ is shifted with respect to the transmitter between the transmitter clock and the receiver clock.

In this case, the pseudo distance r _i can be expressed by the following equation.
r _i = ρ _i + cδ = ρ _i + s
However,
Pseudo-range r _i : distance including a distance error caused by a receiver time error with respect to transmitter i,
True distance ρ _i : true distance between transmitter i and receiver,
Distance error s: error from true distance caused by time error,
Radio wave speed c: Radio wave transmission distance per unit time.

Here, it is possible to obtain the pseudo-range r _i from the received signal.
r _i = c × (T _i ′ −T _S ′)

When the position of the receiver is (x, y, z) and the position of the transmitter i is (x _i , y _i , z _i ), the pseudorange r _i can be expressed as follows.

Here, with respect to the transmitter i = 1 to 4, the respective distances can be expressed as follows.

  Conventionally, the correct position and the correct time of the receiver have been obtained by solving the above four equations with respect to the unknowns x, y, z, and s.

JP-T-2002-507727

Takeyasu Sakai “Introduction to GPS Technology” Tokyo Denki University Press 2003

  However, in the prior art, in order to obtain the distance between a radio communication terminal (corresponding to the above-described receiver) and a base station apparatus (corresponding to the above-described transmitter), first, each of the radio communication terminal and the base station apparatus After obtaining the location information, it was necessary to obtain the distance. At this time, in order to obtain the position information of the wireless communication terminal, it is necessary to receive signals from the four base station apparatuses, and it is necessary that the position information of each base station apparatus is known. Therefore, there is a problem that the distance between the wireless communication terminal and the base station device cannot be obtained unless the radio wave condition at the position where the wireless communication terminal is placed is good.

  An object of the present invention is to provide a wireless communication terminal capable of receiving signals from a first base station apparatus and a second base station apparatus having a shorter distance for wireless communication than the first base station apparatus. Another object of the present invention is to provide a radio communication system, a radio communication terminal, and a distance calculation method capable of calculating the distance between the radio communication terminal and the first base station apparatus even if the position information of each base station apparatus is unknown.

  The present invention proposes the following matters in order to solve the above problems. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

(1) The present invention relates to a first base station device (100), a second base station device (200) having a shorter wireless communication distance than the first base station device, and the first base station. A wireless communication system comprising a station device and a wireless communication terminal (300) capable of wireless communication with the second base station device, wherein the first base station device generates a first reference signal And a first base station signal transmitter (110) for transmitting a first base station signal based on the first reference signal generated by the first reference signal generator (110). 120), and the second base station device generates a second reference signal whose time is synchronized with the first reference signal generated by the first reference signal generator A second reference signal generator (210) and a second reference signal generated by the second reference signal generator; And a second base station signal transmission unit (220) for transmitting the second base station signal based on the second base station signal, wherein the wireless communication terminal receives the first base station signal and the second base station signal. A base station signal receiving unit (310) and a base station type determining unit (320) for determining the base station type of each of the first base station signal and the second base station signal received by the base station signal receiving unit And a reception time detector (330) for detecting the time at which the base station signal receiver has received the first base station signal and the second base station signal, respectively, and the first base station apparatus And at least one of the second base station device and the wireless communication terminal is configured to receive the base station type and the reception of the first base station signal and the second base station signal determined by the base station type determination unit, respectively. The first detected by the time detector A distance calculator (130, 340) that calculates a distance between the wireless communication terminal and the first base station apparatus based on the time when the base station signal is received and the time when the second base station signal is received A wireless communication system characterized by comprising:

  According to the present invention, the first reference signal generator generates the first reference signal. The first base station signal transmission unit transmits a first base station signal based on the first reference signal generated by the first reference signal generation unit. The second reference signal generation unit generates a second reference signal whose time is synchronized with the first reference signal generated by the first reference signal generation unit. The second base station signal transmission unit transmits a second base station signal based on the second reference signal generated by the second reference signal generation unit. The base station signal receiving unit receives the first base station signal and the second base station signal. The base station type determining unit determines the base station type of each of the first base station signal and the second base station signal received by the base station signal receiving unit. The reception time detection unit detects the time at which the base station signal reception unit receives the first base station signal and the second base station signal. The distance calculation unit includes the base station type of each of the first base station signal and the second base station signal determined by the base station type determination unit, and the time when the first base station signal detected by the reception time detection unit is received and The distance between the wireless communication terminal and the first base station apparatus is calculated based on the time when the second base station signal is received. Therefore, the distance between the radio communication terminal and the first base station device can be calculated even if the position information of each base station device is unknown.

(2) In the wireless communication system according to (1), the distance calculation unit (130, 340) may be configured such that the distance between the wireless communication terminal (300) and the second base station device (200) is A wireless communication system is proposed in which the distance between the wireless communication terminal and the first base station apparatus (100) is calculated with zero as zero.

  According to this invention, the distance calculation unit calculates the distance between the radio communication terminal and the first base station apparatus with the distance between the radio communication terminal and the second base station apparatus as zero. Therefore, the distance between the wireless communication terminal and the first base station apparatus can be calculated by simple calculation.

(3) In the wireless communication system according to (1) or (2), the distance calculation unit (130, 340) uses the first base station signal detected by the reception time detection unit (330). When the reception time is T _BS ′, the reception time of the second base station signal is T _AP ′, and the radio wave speed is c, the wireless communication terminal (300) and the first base station apparatus (100 The wireless communication system is characterized in that the distance ρ _BS between the two is determined by ρ _BS = c × (T _BS ′ −T _AP ′).

According to the present invention, the distance calculating unit receives the time when the first base station signal detected by the reception time detecting unit is received as T _BS ′, the time when the second base station signal is received as T _AP ′, When the speed is c, the distance ρ _BS between the wireless communication terminal and the first base station apparatus is obtained by ρ _BS = c × (T _BS ′ −T _AP ′). Therefore, the distance between the wireless communication terminal and the first base station apparatus can be calculated by simple calculation.

(4) The present invention provides the wireless communication system according to any one of (1) to (3), between the second base station apparatus (200) and the wireless communication terminal (300). The distance at which wireless communication is possible is determined based on the time that is the minimum unit detectable by the reception time detection unit (330) from the first base station signal and the second base station signal. , 340) is shorter than the distance measurement accuracy which is the minimum unit distance that can be calculated.

  According to the present invention, the distance at which wireless communication can be performed between the second base station apparatus and the wireless communication terminal is the minimum that the reception time detector can detect from the first base station signal and the second base station signal. The distance calculation unit determined based on the unit time is shorter than the distance measurement accuracy that is the minimum unit distance that can be calculated. Therefore, it is possible to calculate the distance with high accuracy.

(5) In the wireless communication system according to any one of (1) to (4), the present invention provides the wireless communication terminal (300) calculated by the distance calculation unit (130, 340) and the first communication device. A transmission power control unit (140, 350) that controls transmission power of at least one of the wireless communication terminal and the first base station device based on a distance from one base station device (100). Has been proposed.

  According to this invention, the transmission power control unit is based on the distance between the radio communication terminal calculated by the distance calculation unit and the first base station device, and is at least one of the radio communication terminal and the first base station device. To control the transmission power. Therefore, it is possible to control the transmission power so that the power is necessary and sufficient for the distance between the wireless communication terminal and the first base station apparatus.

(6) The present invention is capable of wireless communication between the first base station device (100) and the second base station device (200) having a shorter wireless communication distance than the first base station device. A radio communication terminal (300) that receives a first base station signal transmitted from the first base station apparatus and a second base station signal transmitted from the second base station apparatus. Unit (310), a base station type determining unit (320) for determining a base station type of each of the first base station signal and the second base station signal received by the base station signal receiving unit, and the base A reception time detection unit (330) for detecting a time at which the station signal reception unit receives the first base station signal and the second base station signal, and the first determination by the base station type determination unit Base station type and base station type of each of the base station signal and the second base station signal Based on the time when the first base station signal detected by the reception time detection unit and the time when the second base station signal is received between the radio communication terminal and the first base station device A wireless communication terminal comprising a distance calculation unit (130, 340) for calculating a distance is proposed.

  According to this invention, the base station signal receiving unit receives the first base station signal transmitted from the first base station apparatus and the second base station signal transmitted from the second base station apparatus. The base station type determining unit determines the base station type of each of the first base station signal and the second base station signal received by the base station signal receiving unit. The reception time detection unit detects the time at which the base station signal reception unit receives the first base station signal and the second base station signal. The distance calculation unit includes the base station type of each of the first base station signal and the second base station signal determined by the base station type determination unit, and the time when the first base station signal detected by the reception time detection unit is received and The distance between the wireless communication terminal and the first base station apparatus is calculated based on the time when the second base station signal is received. Therefore, the distance between the radio communication terminal and the first base station device can be calculated even if the position information of each base station device is unknown.

(7) The present invention relates to the first base station device (100), the second base station device (200) having a shorter wireless communication distance than the first base station device, and the first base station. A distance between the radio communication terminal and the first base station apparatus is calculated in a radio communication system including a station apparatus and a radio communication terminal (300) capable of radio communication with the second base station apparatus A first base station signal transmitted by the first base station apparatus and a second base station signal transmitted by the second base station apparatus, and the received first base station signal. A base station signal of each of the first base station signal and the second base station signal is detected, times when the first base station signal and the second base station signal are received are detected, and the first base station signal is detected. The base station type and the second base station signal and the second base station signal respectively. Calculating a distance between the wireless communication terminal and the first base station apparatus based on a time when the base station signal is received and a time when the second base station signal is received Proposed method.

  According to the present invention, the distance calculation method for calculating the distance between the radio communication terminal and the first base station apparatus includes the first base station signal and the second base station transmitted by the first base station apparatus. The second base station signal transmitted by the apparatus is received, the base station type of each of the received first base station signal and second base station signal is determined, and the first base station signal and second base station are determined. The time at which the signals are received is detected, the base station type of each of the first base station signal and the second base station signal, the time at which the first base station signal is received, and the time at which the second base station signal is received The distance between the wireless communication terminal and the first base station device is calculated based on Therefore, the distance between the radio communication terminal and the first base station device can be calculated even if the position information of each base station device is unknown.

According to the present invention, it is possible to calculate the distance between the base station apparatus and the radio communication terminal without knowing the position information of the base station apparatus and the radio communication terminal, or without obtaining it by calculating or the like.
In addition, if the wireless communication terminal is in an area where at least one small base station signal can be received and can receive a signal from one base station apparatus that is a distance calculation target, the base station apparatus and the wireless communication terminal Can be calculated.

It is a figure which shows 1st Embodiment of the radio | wireless communications system using the distance calculation method by this invention. It is a block diagram which shows the structure of the radio | wireless communications system of 1st Embodiment. It is a figure which shows the relationship between the signal and time in 1st Embodiment. It is a block diagram which shows the structure of the radio | wireless communications system of 2nd Embodiment. It is a block diagram which shows the structure of the radio | wireless communications system of 3rd Embodiment. It is a figure which shows the relationship between the signal and time in the calculation method of the conventional position information.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

(First embodiment)
FIG. 1 is a diagram showing a first embodiment of a wireless communication system using a distance calculation method according to the present invention.
The wireless communication system according to the present embodiment is a CDMA (Code Division Multiple Access) communication system including a first base station apparatus 100, a second base station apparatus 200, and a wireless communication terminal 300, and a cellular phone service. Used for.

  The first base station apparatus 100 is a base station apparatus that performs wireless communication with a wireless communication terminal that subscribes to a mobile phone service. The first base station apparatus 100 is a large-scale base station apparatus called a so-called macro cell, in which a wireless communication distance with the wireless communication terminal 300 is several kilometers.

  The second base station apparatus 200 is the same as the first base station apparatus 100 in that the second base station apparatus 200 is a base station apparatus that performs wireless communication with a wireless communication terminal subscribed to a mobile phone service. However, the second base station apparatus 200 has a shorter wireless communication distance than the first base station apparatus 100. The second base station apparatus 200 of this embodiment is a so-called femtocell base station apparatus with a maximum distance of about 10 m that can communicate with a wireless communication terminal.

  In contrast to the conventional macro cell base station apparatus having a communication area with a radius of several hundred m to several tens of kilometers, in recent years, a micro base station apparatus called a femto cell having only a communication area with a radius of about 10 m has been developed. Yes. Conventional large-scale base station apparatuses are called macrocell base station apparatuses, whereas small base station apparatuses called nanocells and picocells are conventionally used. The femtocell is a base station apparatus suitable for use in an individual home where the communication area is narrower than those of these small base station apparatuses and radio waves from a macrocell or the like are difficult to reach.

  The wireless communication terminal 300 is a mobile phone that can wirelessly communicate with the first base station apparatus 100 and the second base station apparatus 200.

FIG. 2 is a block diagram illustrating a configuration of the wireless communication system according to the first embodiment.
The first base station apparatus 100 includes a first reference signal generation unit 110 and a first base station signal transmission unit 120.

The first reference signal generator 110 generates a first reference signal including time information and transmits the first reference signal to the first base station signal transmitter 120.
The first base station signal transmission unit 120 generates a first base station signal based on the first reference signal acquired from the first reference signal generation unit 110. Also, the first base station signal transmission unit 120 transmits the first base station signal as a signal subjected to spectrum spreading using a PN (Pseudo Noise) code having a chip rate of 1.2288 Mchip / sec.
Communication between the first base station apparatus 100 and the second base station apparatus 200 and the wireless communication terminal 300, including the first base station signal transmitted by the first base station signal transmission unit 120, This is performed by radio communication using radio waves using a known transmission / reception unit and antenna equipment (not shown).

The second base station apparatus 200 includes a second reference signal generation unit 210 and a second base station signal transmission unit 220.
Second reference signal generator 210 generates a second reference signal including time information and transmits the second reference signal to second base station signal transmitter 220. Here, the second reference signal generation unit 210 synchronizes the time with the clock unit included in the first reference signal generation unit 110 so that the second reference signal is synchronized with the first reference signal. Equipped with a watch.

  Second base station signal transmission section 220 generates a second base station signal based on the second reference signal acquired from second reference signal generation section 210. Second base station signal transmission section 220 transmits the second base station signal as a signal subjected to spectrum spreading using a PN code having a chip rate of 1.2288 Mchip / sec.

The wireless communication terminal 300 includes a base station signal reception unit 310, a base station type determination unit 320, a reception time detection unit 330, and a distance calculation unit 340.
The base station signal receiving unit 310 receives the first base station signal from the first base station apparatus 100 and the second base station signal from the second base station apparatus 200. Base station signal reception section 310 sends the received first base station signal and second base station signal to base station type determination section 320 and reception time detection section 330.

  The base station type determination unit 320 determines the base station type of each of the first base station signal and the second base station signal received by the base station signal reception unit 310. Here, the base station type is a type of base station according to the maximum distance at which the base station that transmitted the base station signal can communicate wirelessly. In this embodiment, it is classified into whether it is a macrocell base station apparatus or a femtocell base station apparatus. The first base station signal and the second base station signal include ID information for identifying the base station, and the base station type determination unit 320 uses the ID information and the base station. The base station type of each of the first base station signal and the second base station signal is determined by referring to the PN code to be performed. The base station type determination unit 320 sends the determined base station types of the first base station signal and the second base station signal to the distance calculation unit 340.

  The reception time detector 330 detects the time at which the base station signal receiver 310 receives the first base station signal and the second base station signal. The reception time detection unit 330 sends the detected reception time of the first base station signal and the reception time of the second base station signal to the distance calculation unit 340.

  The distance calculation unit 340 includes the base station type of each of the first base station signal and the second base station signal acquired from the base station type determination unit 320, and the first base station signal acquired from the reception time detection unit 330. Based on the reception time and the reception time of the second base station signal, the distance between the radio communication terminal 300 and the first base station device 100 is calculated.

Next, a distance calculation method performed by the distance calculation unit 340 will be described. In the following description, an item related to the first base station apparatus 100 is labeled “BS”, an item related to the second base station apparatus 200 is labeled “AP”, and an item related to the wireless communication terminal 300 is “AT”. A description will be given with appropriate reference numerals.
FIG. 3 is a diagram illustrating a relationship between a signal and time in the first embodiment.
Before the distance is calculated, the positions of the first base station apparatus 100 (BS), the second base station apparatus 200 (AP), and the wireless communication terminal 300 (AT) are unknown. In addition, it is known that the wireless communication terminal 300 (AT) is within a range in which a signal from the second base station apparatus 200 (AP) can be received (R _AP ≧ ρ _AP ). This is determined by the radio communication terminal 300 (AT) receiving the second base station signal from the second base station apparatus 200 (AP).

Here, variables are defined as follows.
Distance R _AP : Maximum distance at which the second base station apparatus 200 (AP) can receive a signal,
Distance R _BS : Maximum distance at which the first base station apparatus 100 (BS) can receive a signal,
Pseudo distance r _i : distance including a distance error caused by a time error of the radio communication terminal 300 (AT) with respect to the base station apparatus i,
True distance ρ _i : True distance between base station apparatus i and wireless communication terminal 300 (AT).

The radio communication terminal 300 (AT) capable of receiving the signal of the second base station apparatus 200 (AP) is the first communication from the first base station apparatus 100 (BS) and the second base station apparatus 200 (AP). The first base station signal and the second base station signal are received, and the reception time is obtained by measuring T _AP ′ and T _BS ′ (detected by the reception time detector 330). Here, the pseudo distances r _AP and r _BS from the second base station apparatus 200 (AP) and the first base station apparatus 100 (BS) to the radio communication terminal 300 (AT) AT are as follows: Can be represented.
r _AP = c × (T _AP '−T _S ')
r _BS = c × (T _BS '−T _S ')
Here, the speed c of radio waves: the transmission distance of radio waves per unit time.

Moreover, since this value includes the time error of the radio communication terminal 300 (AT), it can be expressed as follows.
r _AP = ρ _AP + cδ = ρ _AP + s
r _BS = ρ _BS + cδ = ρ _BS + s
Here, the definition of each variable is as follows.
Time error δ: Time error of radio communication terminal 300 (AT) with respect to base station apparatus i,
Distance error s: error from true distance caused by time error,
True distance ρ _i : True distance between base station apparatus i and wireless communication terminal 300 (AT).

From here, these differences can be expressed as follows.
_{r BS -r AP = (ρ BS} + s) - (ρ AP + s) = ρ BS -ρ AP
At this time, since the range in which signals can be received from the second base station apparatus 200 (AP) is limited, it can be considered that ρ _AP ≈0, and the distance calculation is performed by replacing ρ _AP = 0. Is possible. That is, the maximum communicable distance of the second base station apparatus 200 (AP) is very small compared to the communicable maximum distance of the first base station apparatus 100 (BS). ) To the second base station apparatus 200 (AP) can be assumed to be sufficiently smaller than the distance from the radio communication terminal 300 (AT) to the first base station apparatus 100 (BS).

In addition, since the distance in which the second base station apparatus 200 can perform wireless communication is shorter than the distance in which the first base station apparatus can perform wireless communication, the distance is calculated by replacing ρ _AP = 0. Whether or not ρ _AP = 0 may be replaced when the wireless communication distance is short may be appropriately selected depending on the purpose of using the calculated distance. That is, it depends on how much accuracy is required for the calculated distance.
As one guideline, the distance at which wireless communication is possible between the second base station apparatus 200 (AP) and the wireless communication terminal 300 (AT) is shorter than the distance measurement accuracy (distance granularity) of the wireless communication system. Is desirable. The distance measurement accuracy is a minimum unit distance that can be calculated by the distance calculation unit 340. The distance measurement accuracy is determined based on the time that is the minimum unit that the reception time detection unit 330 can detect from the first base station signal and the second base station signal. In the present embodiment, the first base station signal and the second base station signal are transmitted as signals subjected to spread spectrum using a PN code having a chip rate of 1.2288 Mchip / sec. The minimum time that can be detected by the reception time detection unit 330 is determined from the length. Assuming that the speed of radio waves is c = 299792458 m / sec, the distance measurement accuracy Δd of the wireless communication system of the present embodiment is as follows.
Δd = (1 / 1.2288 × 10 ⁶ ) × 299792458 m≈244 m
On the other hand, the maximum communicable distance of the second base station apparatus 200 (AP) is 10 m, which is sufficiently small.

By replacing ρ _AP = 0, the distance ρ _BS from the wireless communication terminal 300 (AT) to the first base station apparatus 100 (BS) is obtained as follows.
_{ρ BS = (r BS -r AP} ) + ρ AP ≒ r BS -r AP = c × (T BS '-T S') -c × (T AP '-T S') = c × (T BS '- _TAP ')

  That is, when the radio communication terminal 300 (AT) can receive the signal of the second base station device 200 (AP), the distance to the first base station device 100 (BS) that is the target of distance measurement is the first base station. It can be obtained only by measuring the reception time difference between signals from the station apparatus 100 (BS) and the second base station apparatus 200 (AP).

  As described above, according to the first embodiment, the wireless communication terminal 300 is the first base station device 100, and the second base station that has a shorter distance for wireless communication than the first base station device. If the signal from apparatus 200 can be received, the distance between radio communication terminal 300 and first base station apparatus 100 can be calculated even if the position information of each base station apparatus is unknown.

(Second Embodiment)
FIG. 4 is a block diagram illustrating a configuration of a wireless communication system according to the second embodiment.
The second embodiment is the same as the first embodiment except that a transmission power control unit 350 is added to the wireless communication terminal 300. Therefore, the same reference numerals are given to the portions that perform the same functions as those in the first embodiment described above, and repeated descriptions are omitted as appropriate.
In addition to the base station signal receiving unit 310, the base station type determining unit 320, the reception time detecting unit 330, and the distance calculating unit 340, the wireless communication terminal 300 of the second embodiment A transmission power control unit 350 is provided.
The transmission power control unit 350 acquires the distance between the wireless communication terminal 300 and the first base station device 100 obtained by the distance calculation unit 340, and controls the transmission power of the wireless communication terminal 300 based on this distance. Do.

  According to the second embodiment, the transmission power control unit 350 determines the transmission power of the radio communication terminal 300 based on the distance between the radio communication terminal 300 and the first base station device 100 obtained by the distance calculation unit 340. Since the control is performed, the wireless communication terminal 300 can perform transmission with necessary and sufficient transmission power.

(Third embodiment)
FIG. 5 is a block diagram illustrating a configuration of a wireless communication system according to the third embodiment.
In the third embodiment, the distance calculation unit 340 and the transmission power control unit 140 having functions corresponding to the distance calculation unit 340 and the transmission power control unit 350 provided in the wireless communication terminal 300 in the second embodiment are changed to the first embodiment. In this mode, the base station apparatus 100 is relocated. Other parts of the third embodiment are the same as those of the second embodiment. Therefore, the part which fulfill | performs the function similar to 2nd Embodiment mentioned above attaches | subjects the same code | symbol, and abbreviate | omits the overlapping description suitably.

The wireless communication terminal 300 according to the third embodiment includes a base station signal reception unit 310, a base station type determination unit 320, and a reception time detection unit 330.
The base station type determination unit 320 sends the determined base station types of the first base station signal and the second base station signal to the distance calculation unit 130.
The reception time detection unit 330 sends the detected reception time of the first base station signal and reception time of the second base station signal to the distance calculation unit 130.

  The first base station apparatus 100 in the third embodiment includes a distance calculation unit 130 in addition to the first reference signal generation unit 110 and the first base station signal transmission unit 120 similar to those in the third embodiment. The transmission power control unit 140 is provided.

  The distance calculation unit 130 includes the base station type of each of the first base station signal and the second base station signal acquired from the base station type determination unit 320, and the first base station signal acquired from the reception time detection unit 330. Based on the reception time and the reception time of the second base station signal, the distance between the radio communication terminal 300 and the first base station device 100 is calculated.

  The transmission power control unit 140 acquires the distance between the wireless communication terminal 300 and the first base station device 100 obtained by the distance calculation unit 130, and the transmission power of the first base station device 100 based on this distance. Control.

  According to the third embodiment, the transmission power control unit 140 determines the first base station apparatus 100 based on the distance between the radio communication terminal 300 and the first base station apparatus 100 obtained by the distance calculation unit 130. Since the transmission power is controlled, the first base station apparatus 100 can perform transmission with necessary and sufficient transmission power.

  Note that the processing of the wireless communication terminal 300 or the first base station apparatus 100 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the wireless communication terminal 300 or the first base station apparatus 100. By executing, the wireless communication terminal 300, the first base station apparatus 100, and the distance calculation method of the present invention can be realized. The computer system here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW (World Wide Web) system is used. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

(Deformation)
(1) In 1st Embodiment and 2nd Embodiment, the form by which the distance calculation part 340 is provided in the radio | wireless communication terminal 300 is shown, and in 3rd Embodiment, the distance calculation part 130 is 1st base station. The form provided in the apparatus 100 is shown. However, the present invention is not limited to this, and for example, a function corresponding to the distance calculation unit may be provided in both the wireless communication terminal 300 and the first base station device 100. In addition, a function corresponding to the distance calculation unit may be provided in the second base station apparatus 200, or an apparatus independent of the first base station apparatus 100, the second base station apparatus 200, and the wireless communication terminal 300. May be provided.

(2) In the second embodiment and the third embodiment, the transmission power control unit 350 or the transmission power control unit 140 uses the transmission power of the radio communication terminal 300 or the first base station apparatus 100 in which it is included, respectively. The form to control was shown. However, the present invention is not limited thereto, and for example, the transmission power control unit 350 provided in the wireless communication terminal 300 may control the transmission power of the first base station apparatus 100 in addition to the transmission power of the wireless communication terminal 300. Further, the transmission power control unit 140 provided in the first base station apparatus 100 may control the transmission power of the radio communication terminal 300 in addition to the transmission power of the first base station apparatus 100.

(3) In each embodiment, the distance calculation units 340 and 130 regard the distance between the second base station apparatus 200 and the radio communication terminal 300 as zero, and regard the first base station apparatus 100 and the radio communication terminal 300 as zero. An example of calculating the distance between the two is shown. However, the present invention is not limited to this, and for example, the distance between the second base station apparatus 200 and the wireless communication terminal 300 can be regarded as the maximum distance 10 m that allows wireless communication between them, or wireless communication is possible. It may be considered that it is 5 m which is a half of the maximum distance.
In addition, although 1st Embodiment-3rd Embodiment and modification can also be used in combination suitably, detailed description is abbreviate | omitted.

DESCRIPTION OF SYMBOLS 100 1st base station apparatus 110 1st reference signal generation part 120 1st base station signal transmission part 130,340 Distance calculation part 140,350 Transmission power control part 200 2nd base station apparatus 210 2nd reference signal Generation unit 220 Second base station signal transmission unit 300 Wireless communication terminal 310 Base station signal reception unit 320 Base station type determination unit 330 Reception time detection unit

Claims (7)

A first base station device;
A second base station apparatus that has a shorter wireless communication distance than the first base station apparatus;
A wireless communication terminal capable of wireless communication with the first base station device and the second base station device;
A wireless communication system comprising:
The first base station apparatus
A first reference signal generator for generating a first reference signal;
A first base station signal transmitter that transmits a first base station signal based on a first reference signal generated by the first reference signal generator;
The second base station apparatus is
A second reference signal generator that generates a second reference signal that is synchronized in time with the first reference signal generated by the first reference signal generator;
A second base station signal transmitter for transmitting a second base station signal based on the second reference signal generated by the second reference signal generator;
The wireless communication terminal is
A base station signal receiver for receiving the first base station signal and the second base station signal;
A base station type determining unit that determines a base station type of each of the first base station signal and the second base station signal received by the base station signal receiving unit;
A reception time detector that detects the time at which the base station signal receiver has received the first base station signal and the second base station signal,
At least one of the first base station apparatus, the second base station apparatus, and the wireless communication terminal is configured so that each of the first base station signal and the second base station signal determined by the base station type determination unit is Base station type and the time when the first base station signal detected by the reception time detector is received and the time when the second base station signal is received, and the wireless communication terminal and the first base station A distance calculation unit for calculating a distance to the device;
A wireless communication system. The wireless communication system according to claim 1, wherein
The distance calculation unit calculates a distance between the radio communication terminal and the first base station apparatus, with a distance between the radio communication terminal and the second base station apparatus as zero;
A wireless communication system. The wireless communication system according to claim 1 or 2,
The distance calculator is T _BS ′ when the first base station signal detected by the reception time detector is received, T _AP ′ is the time when the second base station signal is received, and the radio wave speed is c, the distance ρ _BS between the wireless communication terminal and the first base station apparatus is
ρ _BS = c × (T _BS '−T _AP ')
A wireless communication system characterized by: In the radio | wireless communications system of any one of Claim 1- Claim 3,
The distance at which wireless communication can be performed between the second base station apparatus and the wireless communication terminal is the minimum unit that the reception time detection unit can detect from the first base station signal and the second base station signal. Shorter than the distance measurement accuracy that is the minimum unit distance that can be calculated by the distance calculation unit determined based on the time to become,
A wireless communication system. In the radio | wireless communications system of any one of Claim 1- Claim 4,
Transmission for controlling transmission power of at least one of the radio communication terminal and the first base station apparatus based on the distance between the radio communication terminal calculated by the distance calculation unit and the first base station apparatus Providing a power control unit;
A wireless communication system. A wireless communication terminal capable of wireless communication between a first base station apparatus and a second base station apparatus having a shorter distance capable of wireless communication than the first base station apparatus,
A base station signal receiving unit that receives the first base station signal transmitted by the first base station device and the second base station signal transmitted by the second base station device;
A base station type determining unit that determines a base station type of each of the first base station signal and the second base station signal received by the base station signal receiving unit;
A reception time detection unit for detecting the time at which the base station signal reception unit receives the first base station signal and the second base station signal; and
The base station type of each of the first base station signal and the second base station signal determined by the base station type determination unit and the time when the first base station signal detected by the reception time detection unit is received and A distance calculating unit that calculates a distance between the wireless communication terminal and the first base station device based on a time at which the second base station signal is received;
A wireless communication terminal comprising: Wireless communication between the first base station apparatus, the second base station apparatus having a shorter wireless communication distance than the first base station apparatus, the first base station apparatus, and the second base station apparatus A distance calculation method for calculating a distance between the wireless communication terminal and the first base station apparatus in a wireless communication system including a wireless communication terminal capable of communication,
Receiving the first base station signal transmitted by the first base station apparatus and the second base station signal transmitted by the second base station apparatus;
Determining the base station type of each of the received first base station signal and the second base station signal;
Detecting the time at which each of the first base station signal and the second base station signal is received;
The wireless communication based on a base station type of each of the first base station signal and the second base station signal, a time when the first base station signal is received, and a time when the second base station signal is received Calculating a distance between the terminal and the first base station device;
A distance calculation method characterized by

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