JP2008300991A - Radio communication system, mobile terminal, base station, and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system capable of reducing an influence of delay due to the distance between a mobile terminal and a base station by setting transmission timing of a radio signal on the basis of position information on the mobile terminal and position information on the bases station and to provide the mobile terminal, the base station, and a radio communication method. <P>SOLUTION: The radio communication system includes a plurality of base stations 120 connected through a relay server 140, and the mobile terminal 110 communicating with the plurality of base stations 120 by radio includes a terminal position acquisition unit 220 which acquires the position information on the mobile terminal 110; a base station position acquisition unit 222 which acquires the position of a base station 120 communicating with the mobile terminal 110, and a transmission timing setting unit 224 which is provided to the mobile terminal 110 and sets transmission timing of a radio communication signal to be sent out from the mobile terminal 110 according to the position of the mobile terminal 110 and the position of the base station 120. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio communication system, a mobile terminal, a base station, and a radio communication method for performing radio communication with a base station through a time slot based on time division duplex.

  There is a TDMA-TDD system as one of the representative systems of wireless communication such as PHS (TDMA: Time Division Multiple Access: TDD: Time Division Duplex). TDD is a method of subdividing a communication path on a time axis and switching between transmission and reception in a short time. TDMA is a method in which one frequency is subdivided on a time axis and communication is performed with a plurality of opponents.

  FIG. 10 shows an example of transmission / reception of a TDMA-TDD system signal. In TDMA communication, a mobile terminal (PS: Personal Station) receives at a timing transmitted by a base station (CS: Cell Station), and conversely, a base station receives at a timing transmitted by a mobile terminal. Data is divided for each time slot, and data is transmitted and received. In time division multiplexing, a mobile terminal can communicate with a plurality of base stations using different channels, or can communicate with a plurality of channels using one base station. is there.

  For example, as shown in FIG. 10A, if a certain mobile terminal is assigned the third slot, data transmitted from the slot Tx3 of the base station is received in the slot Rx3 of the mobile terminal. Similarly, data transmitted from the slot Tx3 of the mobile terminal is received by the slot Rx3 of the base station.

  In this way, when the mobile terminal receives channel assignments from two base stations, the time slots corresponding to the channels are set at exclusive timing (time slots do not overlap). Therefore, the mobile terminal can receive frame data from the two base stations at different timings, and can perform stable wireless communication.

  In the service currently implemented, one frame is composed of 8 slots. One slot is composed of 625 [μs] and 240 bits. FIG. 10B shows the configuration of one slot, and there are a ramp bit (R) and a guard bit (G) in addition to 220 bits of the information part. There are 16 guard bits, and this guard bit can absorb the influence of delay to some extent.

Here, the longer the distance between the base station and the terminal is, the longer the radio wave propagation distance is increased, thereby causing a delay. When the distance is 100 [m], if the radio wave propagation speed is 3 × 10 ⁸ [m / s], the delay time is 0.33 [μs], and when the distance is 1,000 m, the delay time is 3.3 [m]. μs]. Since the base station and the mobile terminal are synchronized at the start of communication, the mobile terminal operates at a timing delayed by Δt corresponding to the delay time as an absolute time. Since the interval between the transmission timing and the reception timing is fixed, the signal reaching the base station from the mobile terminal has a delay of 2Δt corresponding to the distance of the round trip path.

  When the delay increases as the distance between the base station and the terminal increases as described above, the radio signal transmitted from the mobile terminal exceeds the receivable range on the base station side, and a situation in which communication is impossible occurs. In particular, serious influence is expected in orthogonal frequency division multiple access (OFDMA).

  Conventionally, Patent Document 1 (Japanese Patent Laid-Open No. 10-233727) proposes to variably control the data transmission timing in accordance with the distance between the base station and the terminal. Specifically, when the code error rate is greater than or equal to a predetermined value, if the received electric field strength is high (assuming that it is too close), the transmission timing is delayed, and if the received electric field strength is low (assuming that it is too far) By improving the transmission timing, the code error rate is improved.

Further, as disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2000-284040), it is also proposed to measure the distance between the transmission point and the reception point by predicting the radio wave propagation path using the observed delay profile. ing.
JP-A-10-233727 JP 2000-284040 A

  However, in the configuration described in Patent Document 1, the distance is estimated based on the received electric field strength. However, the received electric field strength varies depending on the types of base stations and mobile terminals, and increases and decreases depending on weather and obstacles, so there is no certainty in estimating the distance. As a result, there is no certainty in the direction of timing change (accelerated / delayed), which may make communication unstable.

  Further, in the propagation path prediction based on the delay profile described in Patent Document 2, it seems that the distance between the base station and the mobile terminal can be measured. However, an unstable environment such as many obstacles causes a delay spread by multipath ( There is a problem that a signal delay width occurs. Therefore, if the timing is changed in accordance with this, the distance may be mistaken and communication may become unstable.

  Further, when the transmission timing is changed when the error (code error rate) is high as in Patent Document 1, the transmission timing is set when the delay spread is large due to multipath, that is, when the propagation path is unstable. There is a risk of change. This synergistic effect may cause further instability of communication.

  Therefore, the present invention provides a wireless communication system capable of reducing the influence of delay due to the distance between the mobile terminal and the base station by setting the transmission timing of the radio signal based on the position information of the mobile terminal and the position information of the base station, An object of the present invention is to provide a mobile terminal, a base station, and a wireless communication method.

  In order to solve the above problems, a typical configuration of a wireless communication system according to the present invention includes a plurality of base stations connected via a relay server, and mobile terminals that perform wireless communication with the plurality of base stations. In the wireless communication system provided, a terminal location acquisition unit that acquires location information of a mobile terminal, a base station location acquisition unit that acquires a location of a base station that communicates with the mobile terminal, a location of the mobile terminal, And a transmission timing setting unit for setting a transmission timing of a radio communication signal transmitted from the mobile terminal in accordance with the position of the base station.

  According to the above configuration, by setting the transmission timing according to the position of the mobile terminal and the position of the base station, it is possible to set the transmission timing appropriately as compared with the case where the distance is estimated by the received electric field strength or the delay profile. Thus, the influence of delay can be surely reduced.

  The terminal location acquisition unit may be a GPS reception unit that is provided in the mobile terminal and receives a signal from a GPS satellite and acquires the longitude and latitude of the mobile terminal. Thereby, the position of the mobile terminal can be acquired as an absolute coordinate, and the influence of the delay can be appropriately reduced by considering it together with the position of the base station known in advance.

  The terminal position acquisition unit is provided in the mobile terminal or the relay server, collects position-dependent information for the mobile terminal from three or more base stations, and obtains three from the position-dependent information for at least three base stations and the position information of these base stations. The position of the mobile terminal may be acquired by point surveying. Here, the position-dependent information includes received field strength (RSSI), time difference of arrival (TDOA), time of arrival (TOA), and direction of arrival (AOA). Arrival) etc. can be used. Thereby, the position of the mobile terminal can be acquired with high accuracy, and the influence of the delay can be reduced appropriately.

  The transmission timing setting unit may set the transmission timing according to these distances calculated based on the position of the mobile terminal and the position of the base station. That is, the transmission timing can be set by considering the delay between the base station and the mobile terminal using the linear distance.

  Further, the relay server includes a delay information table including delay information of a radio signal corresponding to a region, and the base station or the mobile terminal includes a delay information acquisition unit that acquires delay information corresponding to the position of the mobile terminal from the delay information table, The transmission timing setting unit may set the transmission timing based on the delay information acquired by the delay information acquisition unit. For example, radio waves may be difficult to reach linearly in urban areas with many obstacles, so the transmission timing is set more appropriately by correcting the position of the acquired mobile terminal based on delay information according to the area. be able to.

  The transmission timing setting unit may set the transmission timing when the distance between the mobile terminal and the base station is equal to or greater than a predetermined distance. The transmission timing may be set (changed) at any distance between the mobile terminal and the base station, but by setting the transmission timing only when the distance is equal to or greater than the predetermined distance as described above, Processing can be reduced.

  The base station position acquisition unit may be provided in the mobile terminal, and the base station position acquisition unit may acquire the positions of a plurality of neighboring base stations. Thus, the mobile terminal can acquire the base station position if it receives only the base station ID from the base station. Therefore, data to be transmitted / received when transmission timing is set continuously can be reduced.

  Furthermore, the IDs and position information of all base stations may be stored in association with the mobile terminal. Conventionally, since the mobile terminal acquires the ID of the base station at the start of communication, according to the above configuration, the position of the base station is acquired without changing the base station, and the transmission timing is set together with the position of the own terminal. Can be set.

  A typical configuration of a mobile terminal according to the present invention is that a mobile terminal that performs radio communication with a base station includes a terminal location acquisition unit that acquires location information of the mobile terminal, and a location of the base station that communicates with the mobile terminal. A base station position acquisition unit to be acquired and a transmission timing setting unit that sets a transmission timing of a wireless communication signal according to the position of the mobile terminal and the position of the base station are provided.

  Further, the mobile terminal may be configured to search for a handover destination base station when the distance between the mobile terminal and the base station is a predetermined distance or more. Thereby, handover can be performed while the received electric field strength is sufficient, and smoother seamless handover can be realized.

  A representative configuration of a base station according to the present invention is such that, in a base station that performs radio communication with a mobile terminal, the mobile terminal that communicates with the base station includes the location information of the base station or a neighboring base station that includes the base station. And a base station position transmitter for transmitting the position information. Thereby, the mobile terminal can calculate the distance to the base station, and can be used for setting the transmission timing.

  A representative configuration of a wireless communication method according to the present invention is a wireless communication that performs wireless communication using a plurality of base stations connected via a relay server and mobile terminals that perform wireless communication with the plurality of base stations. In the method, a terminal location acquisition step of acquiring location information of the mobile terminal, a base station location acquisition step of acquiring the location of the base station communicating with the mobile terminal, and the distance from the location of the mobile terminal and the base station It includes a distance calculation step for calculating, and a transmission timing setting step for setting the transmission timing of the wireless communication signal according to the calculated distance.

  According to the above wireless communication method, by setting the transmission timing according to the distance between the mobile terminal and the base station, the transmission timing can be set appropriately, and the influence of delay can be reduced with certainty.

  According to the present invention, by setting the transmission timing according to the position of the mobile terminal and the position of the base station, the transmission timing can be set appropriately, and the influence of delay can be reliably reduced.

[First embodiment]
A first embodiment of a radio communication system, a mobile terminal, a base station, and a radio communication method according to the present invention will be described. In the present embodiment, the wireless communication system is a PHS (Personal Handy phone System) and will be described as communicating by the TDMA-TDD system.

  FIG. 1 is a block diagram showing a schematic configuration of a wireless communication system. The wireless communication system 100 includes a mobile terminal 110, a base station 120, a communication network 130 such as the Internet or a dedicated line, and a relay server 140.

  In the wireless communication system 100, when attempting to make a call to another mobile terminal using the mobile terminal 110, the user operates the mobile terminal 110 of the user to wirelessly connect with the base station 120 in the wireless communicable area. Communication is established, and voice communication is performed with the other mobile terminal 150 possessed by the communication partner via the communication network 130, the relay server 140, and the base station 120 in the wireless communication area of the other mobile terminal 150.

  At this time, the mobile terminal 110 performs radio communication based on the time division multiplexing method in parallel on two communicable base stations 120 and uses two time slots provided exclusively from each base station 120. Thus, wireless communication can be established (see FIG. 10).

  In this embodiment, a signal from the GPS satellite 500 is used. The GPS satellite 500 is used for general use and is not included in this system.

  Hereinafter, the mobile terminal 110 and the base station 120 in the radio communication system 100 will be described in detail. Thereafter, an example in which the transmission timing of the mobile terminal 110 is set with reference to the transmission / reception timing of the base station 120 will be described.

(Mobile terminal 110)
FIG. 2 is a functional block diagram illustrating schematic functions of the mobile terminal 110. The mobile terminal 110 includes a terminal-side control unit 210, a terminal-side memory 212, a display unit 214, an operation unit 216, and a wireless communication unit 218. Further, in the present embodiment, the mobile terminal 110 is provided with a terminal position acquisition unit 220 including a GPS reception unit, a base station position acquisition unit 222, and a transmission timing setting unit 224.

  The terminal-side control unit 210 manages and controls the entire mobile terminal 110 using a semiconductor integrated circuit including a central processing unit (CPU). The terminal-side control unit 210 performs a call function and a mail delivery function using the mobile terminal 110 using a program in the terminal-side memory 212.

The terminal-side memory 212 includes a ROM, RAM, E ² PROM, nonvolatile RAM, flash memory, HDD (Hard Disk Drive), and the like, and stores programs, applications, and the like processed by the terminal-side control unit 210.

  The display unit 214 is configured by a color or single color display, and is stored in the terminal-side memory 212 or provided from an application server (not shown) via a communication network. Interface) can be displayed.

  The operation unit 216 includes switches such as a keyboard, a cross key, and a joystick, and receives a user operation input.

  The terminal-side wireless communication unit 218 performs wireless communication with the base station 120 in the wireless communication system 100. As such wireless communication, for example, a TDMA-TDD system (TDMA: Time Division Multiple Access) in which a plurality of time slots obtained by time-dividing frames in the base station 120 is assigned to the channel of the mobile terminal 110 to perform communication. A system, TDD: Time Division Duplex, OFDMA system (Orthogonal Frequency Division Multiplex Access), etc. are used.

  The terminal location acquisition unit 220 is a GPS reception unit that receives a signal from the GPS satellite 500 and acquires the longitude and latitude of the mobile terminal. Although only one GPS satellite 500 is shown in FIG. 1, generally, signals from three to five GPS satellites 500 can be received and the longitude and latitude of the current position can be acquired as absolute values.

  The base station position acquisition unit 222 acquires position information of the base station from the base station 120, as will be described later. As the position information, longitude and latitude information can be used.

  The transmission timing setting unit 224 sets the transmission timing of the radio signal transmitted from the mobile terminal 110, as will be described later.

(Base station 120)
FIG. 3 is a functional block diagram showing a schematic function of the base station 120. The base station 120 includes a base station side control unit 230, a base station side memory 232, a wireless communication unit 234, a communication network connection unit 236, and a base station position transmission unit 238.

  The base station control unit 230 manages and controls the entire base station 120 using a semiconductor integrated circuit including a central processing unit. The base station side control unit 230 uses the program in the base station side memory 232 to support communication or communication between mobile terminals.

The base station side memory 232 is composed of ROM, RAM, E ² PROM, nonvolatile RAM, flash memory, HDD, etc., and programs processed by the base station side control unit 230 and data transmitted / received between mobile terminals. Remember.

  The wireless communication unit 234 performs wireless communication with the mobile terminal 110 based on a mobile phone network. For example, in the present embodiment, a time division multiplexing method is employed in which a plurality of time slots obtained by time-dividing frames in the base station 120 are assigned to channels and communication is performed.

  The communication network connection unit 236 transmits and receives communication signals to and from the relay server 140 through the communication network 130. The communication network may be an ISDN communication network or an IP communication network.

  The base station position transmission unit 238 transmits the position information of the base station 120 or the position information of neighboring base stations including the base station 120 to the mobile terminal 110. As the position information, longitude and latitude information can be used, and the longitude and latitude of each base station is determined at the time of installation, and can be stored in the base station side memory 232.

(Relay server 140)
FIG. 4 is a functional block diagram illustrating a schematic function of the relay server 140. The relay server 140 includes a server-side control unit 260, a server-side memory 262, and a communication network connection unit 264.

  The server-side control unit 260 manages and controls the entire relay server 140 using a semiconductor integrated circuit including a central processing unit. The server-side control unit 260 uses the program in the server-side memory 262 to select a base station 120 necessary for a call between mobile terminals, and provides connection support. When the communication line through the base station 120 is established, the voice call processing is entrusted to the base station, and voice signals are directly transmitted and received between the base stations 120 on the mobile terminal 110 side and the wireless terminal device 150 side. Then, the relay server 140 shifts to a standby state for assigning an appropriate base station 120 according to a change in the communication environment of each mobile terminal 110, 150.

The server-side memory 262 includes ROM, RAM, E ² PROM, non-volatile RAM, flash memory, HDD, and the like, and the program processed by the server-side control unit 260 and the base station 120 selected by the server-side control unit 260. Are stored in a table or the like associated with the mobile terminal 110.

  The communication network connection unit 264 transmits a command to that effect to the base station 120 selected as the communication path of the mobile terminal 110 through the communication network 130. Further, upon receiving a handover request from the base station 120, the server-side control unit 260 newly selects an appropriate base station 120, and notifies the base station 120 that it has become a handover destination.

(Wireless communication method)
A radio communication method by the radio communication system 100 including the mobile terminal 110, the base station 120, and the relay server 140 having the above configuration will be described.

  FIG. 5 is a flowchart showing an example of setting transmission timing during communication. When starting communication, the mobile terminal 110 searches for nearby base stations and connects to an optimal base station by the wireless communication unit 218. When communication is started (S102), the mobile terminal 110 acquires longitude and latitude information as the position information of the base station from the base station 120 by the base station position acquisition unit 222 (base station position acquisition step: S104). Next, the terminal position acquisition unit 220 is used to receive a signal from a GPS satellite and acquire longitude and latitude information of the terminal itself (terminal position acquisition step: S106).

  Next, the transmission timing setting unit 224 of the mobile terminal 110 calculates these distances from the position of the mobile terminal 110 and the position of the base station 120 (distance calculation step: S108). Furthermore, the transmission timing setting unit 224 sets the transmission timing of the wireless communication signal according to the calculated distance (transmission timing setting step: S110). Then, it is determined whether or not the communication is ended (S112). If the communication is not ended, a signal from the GPS satellite is received using the terminal position acquisition unit 220, and the current position of the terminal is updated.

  Here, the transmission timing is set according to the distance in the present embodiment. FIG. 6 is a diagram for explaining a transmission / reception state. The longer the distance between the base station 120 and the mobile terminal 110 is, the longer the radio wave propagation distance increases, causing a delay. Since the base station and the mobile terminal are synchronized at the start of communication, the mobile terminal operates at a timing delayed by Δt corresponding to the delay time as an absolute time. Depending on the distance of the round trip path, a delay of 2Δt occurs. Therefore, in the present embodiment, by setting the transmission timing to be advanced by 2Δt, the base station 120 can arrive at the correct timing.

For example, when the distance between the base station 120 and the mobile terminal 110 is 1000 [m], if the radio wave propagation speed is 3 × 10 ⁸ [m / s], the delay time Δt is 3.3 [μs]. Therefore, the transmission timing setting unit 224 of the mobile terminal 110 can set the transmission timing to be advanced by 6.6 [μs] which is 2Δt.

  Here, in the slot of 625 [μs], there are 4 ramp bits (about 10.4 [μs]) in front of the 220-bit information part, and 16 guard bits (about 41.7 [about [1.7] in the information part). μs]). If the transmission timing protrudes from the slot, it affects other slots, so it is preferable to set within the range of the ramp bit or guard bit. However, if the immediately preceding slot (Tx2 in the case of FIG. 6) is not used, the transmission timing can be set more greatly shifted.

  According to the above configuration, by setting the transmission timing according to the position of the mobile terminal 110 and the position of the base station 120, it is possible to set the transmission timing appropriately as compared with the case where the distance is estimated by the received electric field strength or the delay profile. It is possible to reduce the influence of delay.

  In particular, by receiving a signal from a GPS satellite and acquiring the longitude and latitude of the mobile terminal, the position of the mobile terminal can be acquired as absolute coordinates, and by considering it together with the position of the base station known in advance , The influence of the delay can be reduced appropriately.

  FIG. 7 is a flowchart illustrating an example of setting transmission timing before communication. Portions that are the same as those in FIG. 5 are given the same step numbers and description thereof is omitted.

  The base station 120 broadcasts its own latitude / longitude information at predetermined intervals (S202). Also, the mobile terminal 110 receives the broadcast even when not communicating, and acquires the longitude and latitude information of the base station 120 (S204). This is repeated until communication is started (S206). When trying to start communication, first, the distance between the base station 120 and the mobile terminal is calculated and the transmission timing is changed (S208). Note that step S208 is a subroutine from the acquisition of longitude and latitude information of the own terminal (S106) to the change of transmission timing (S112) shown in FIG.

  Then, after the transmission timing is set, communication is started (S102). With this configuration, stable communication can be performed from the beginning of communication. Further, during the communication, as in the case shown in FIG. 5, it is determined whether or not the communication is ended (S112). If the communication is not ended, the latitude and longitude information of the terminal is continuously acquired, and the distance is calculated and transmitted. The timing is changed (S210).

[Second Embodiment]
A second embodiment of the wireless communication system, mobile terminal, base station, and wireless communication method according to the present invention will be described. About the part which overlaps with said 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  FIG. 8 is a diagram illustrating the configuration of the wireless communication system 100 according to the present embodiment. In the present embodiment, a terminal location acquisition unit 266 is provided in the relay server 140. The relay server 140 collects position-dependent information for the mobile terminal 110 from three or more base stations, and determines the position of the mobile terminal 110 by triangulation from the position-dependent information for at least three base stations and the position information of these base stations. Can be obtained. Here, the position-dependent information includes received field strength (RSSI), time difference of arrival (TDOA), time of arrival (TOA), and direction of arrival (AOA). Arrival) etc. can be used.

  The terminal location information detected by the delay information acquisition unit 226 is transmitted to the terminal location reception unit 228 of the mobile terminal 110 via the base station 120. Then, the transmission timing setting unit 224 of the mobile terminal 110 can calculate the distance between the base station 120 and the mobile terminal 110 and set the transmission timing, as in the first embodiment. Thereby, the position of the mobile terminal 110 can be acquired with high accuracy without using a GPS satellite, and the influence of the delay can be appropriately reduced.

[Other Embodiments]
In the first embodiment, the delay time is calculated considering the distance between the base station 120 and the mobile terminal 110 as a linear distance. However, there may be a delay of more than a straight distance due to a roundabout of buildings and mountainous areas in urban areas.

  FIG. 9 shows another configuration example of the wireless communication system in which transmission timing is set using further delay information. In the wireless communication system 100 illustrated in FIG. 9, the relay server 140 includes a delay information table 268, and the mobile terminal 110 includes a delay information acquisition unit 226. The delay information table 268 stores radio signal delay information corresponding to the region.

  Here, the delay information is an index indicating how much the radio wave is delayed in the area on average. For example, in urban areas where there are many obstacles, radio waves may be difficult to reach in a straight line. Therefore, the transmission timing setting value (2Δt) described in the first embodiment is 1.2 times that in urban areas. Then, it can be set such as 1.0 times. The transmission timing can be set more appropriately by correcting the position of the mobile terminal 110 thus acquired based on the delay information corresponding to the area.

  In the first embodiment, the position information of the base station 120 has been described so as to acquire only the position of the connected base station 120. However, the positions of a plurality of neighboring base stations 120 may be acquired. Accordingly, if the mobile terminal receives only the ID from the base station 120, the base station position can be acquired. Therefore, when transmitting timing is set continuously (repeatedly), data to be transmitted / received can be reduced.

  Further, the IDs and the position information of all the base stations 120 may be stored in the terminal-side memory 212 of the mobile terminal 110 in association with each other. Conventionally, since the mobile terminal 110 has acquired the ID of the base station at the start of communication, by configuring as described above, the mobile terminal 110 acquires the position without changing the base station 120 and matches the position of the own terminal. To set the transmission timing.

  In the first embodiment, the transmission timing setting unit 224 has been described so as to continue setting the transmission timing at any distance (FIG. 5). However, the distance between the mobile terminal 110 and the base station 120 is a predetermined distance or more. Only in some cases, the transmission timing may be set. As a result, processing can be executed only when the delay is large, and the load on the mobile terminal 110 can be reduced.

  Further, the mobile terminal 110 may be configured to search for the handover destination base station 120 when the distance between the mobile terminal 110 and the base station 120 is a predetermined distance or more. Conventionally, when the received electric field strength with respect to the currently connected base station 120 is sufficient, the next handover destination is not searched. However, by using the distance between the mobile terminal 110 and the base station 120 as a trigger for performing handover, handover can be performed while the received electric field strength is sufficient, and smoother seamless handover can be realized.

  The present invention can be used as a wireless communication system, a mobile terminal, a base station, and a wireless communication method for performing wireless communication with a base station through a time slot based on time division duplex.

It is a block diagram which shows schematic structure of a radio | wireless communications system. FIG. 3 is a functional block diagram showing a schematic function of a mobile terminal 110. 3 is a functional block diagram showing a schematic function of a base station 120. FIG. FIG. 3 is a functional block diagram illustrating a schematic function of a relay server 140. It is a flowchart which shows the example which sets a transmission timing during communication. It is a figure explaining a transmission / reception state. It is a flowchart which shows the example which sets a transmission timing before communication. It is a figure explaining the structure of the radio | wireless communications system 100 concerning this embodiment. It is a figure which shows the other structural example of a radio | wireless communications system. It is a figure which shows the transmission / reception state of the signal of the conventional TDMA-TDD system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Wireless communication system, 110 ... Mobile terminal, 120 ... Base station, 130 ... Communication network, 140 ... Relay server, 150 ... Wireless terminal device, 210 ... Terminal side control part, 212 ... Terminal side memory, 214 ... Display part, 216 ... Operation unit, 218 ... Wireless communication unit, 220 ... Terminal position acquisition unit, 222 ... Base station position acquisition unit, 224 ... Transmission timing setting unit, 226 ... Delay information acquisition unit, 228 ... Terminal position reception unit, 230 ... Base Station side control unit, 232 ... base station side memory, 234 ... wireless communication unit, 236 ... communication network connection unit, 238 ... base station position transmission unit, 260 ... server side control unit, 262 ... server side memory, 264 ... communication network Connection unit, 266 ... terminal position acquisition unit, 268 ... delay information table, 500 ... GPS satellite

Claims (11)

In a wireless communication system comprising a plurality of base stations connected via a relay server, and a mobile terminal that performs wireless communication with the plurality of base stations,
A terminal location acquisition unit for acquiring location information of the mobile terminal;
A base station position acquisition unit that acquires a position of a base station that communicates with the mobile terminal;
A transmission timing setting unit provided in the mobile terminal and configured to set a transmission timing of a radio communication signal transmitted from the mobile terminal according to the position of the mobile terminal and the position of the base station. Wireless communication system.   2. The wireless communication system according to claim 1, wherein the terminal location acquisition unit is a GPS reception unit provided in the mobile terminal, which receives a signal from a GPS satellite and acquires the longitude and latitude of the mobile terminal.   The terminal position acquisition unit is provided in the mobile terminal or the relay server, collects position dependent information for the mobile terminal from three or more base stations, position dependent information for at least three base stations, and positions of these base stations The wireless communication system according to claim 1, wherein the position of the mobile terminal is acquired from the information by three-point surveying.   The radio communication system according to claim 1, wherein the transmission timing setting unit sets transmission timing according to the distance calculated based on the position of the mobile terminal and the position of the base station. Further, the relay server includes a delay information table including delay information of radio signals according to the area,
The base station or the mobile terminal includes a delay information acquisition unit that acquires delay information corresponding to the position of the mobile terminal from the delay information table,
The wireless communication system according to claim 1, wherein the transmission timing setting unit sets the transmission timing based on delay information acquired by the delay information acquisition unit.   The wireless communication system according to claim 4, wherein the transmission timing setting unit sets a transmission timing when a distance between the mobile terminal and the base station is a predetermined distance or more. The wireless communication system according to claim 1, wherein the base station position acquisition unit is provided in the mobile terminal, and the base station position acquisition unit acquires the positions of a plurality of neighboring base stations.
In a mobile terminal that performs radio communication with a base station,
A terminal location acquisition unit for acquiring location information of the mobile terminal;
A base station position acquisition unit that acquires a position of a base station that communicates with the mobile terminal;
A mobile terminal comprising: a transmission timing setting unit configured to set a transmission timing of a radio communication signal according to a position of the mobile terminal and a position of the base station. The mobile terminal according to claim 8, wherein when the distance between the mobile terminal and the base station is a predetermined distance or more, a handover destination base station is searched.
In a base station that performs radio communication with a mobile terminal,
A base station, comprising: a mobile terminal that communicates with the base station, and a base station position transmitter that transmits position information of the base station or position information of a neighboring base station including the base station.
In a wireless communication method for performing wireless communication using a plurality of base stations connected via a relay server and a mobile terminal that performs wireless communication with the plurality of base stations,
A terminal location acquisition step of acquiring location information of the mobile terminal;
A base station position acquisition step of acquiring a position of a base station communicating with the mobile terminal;
A distance calculating step of calculating these distances from the position of the mobile terminal and the position of the base station;
And a transmission timing setting step of setting a transmission timing of a radio communication signal according to the calculated distance.

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