JP5111193B2 - Wireless communication system, mobile station, base station, and wireless communication method - Google Patents

Description

  The present invention relates to a radio communication system, a mobile station, a base station, and a radio communication method capable of radio communication by TDMA.

  In recent years, mobile stations such as PHS (Personal Handy phone System) and mobile phones have become widespread, and there has been a demand for improvement in communication quality and communication rate as well as downsizing and weight reduction of mobile stations. In addition, expansion of communicable areas is still desired in rural areas and high-rise buildings, and additional base stations are being installed.

  Such a mobile station normally selects one base station as a wireless communication target, and establishes a communication connection with another mobile station through communication with the base station. Here, when the mobile station moves together with the user, it is assumed that the distance to the base station with which the user is communicating becomes large, and that communication is eventually interrupted. Therefore, a so-called handover technique for switching the base station to be communicated and continuing communication has been publicly disclosed. By using the handover technology, continuous communication is possible regardless of the distance traveled by the user. However, in order to implement handover, it is necessary to install a large number of base stations. There was no communication in the area where there was no communication.

  In addition, guard interval technology is used to avoid the adverse effects caused by propagation delay according to the distance between the mobile station and the base station, but the length of the guard interval is usually fixed and depends on the distance from the base station. However, even when there is a margin in radio capability, if the allowable distance of the guard interval is exceeded, effective frames interfere and communication becomes difficult.

  The transmission / reception timing shift due to the propagation delay can be corrected by deriving the propagation delay time based on the position information. However, in order to estimate the position information, the radio field intensity of the mobile station is set to three or more base stations. (3 point positioning method), and even outside the communicable range where the base station does not exist, it was not possible to specify the position.

In addition, it is desired to extend the use time of the mobile station along with the expansion of the communicable range. For example, in Patent Document 1, when the secondary battery, which is the power source of the mobile station, is about to discharge, A technique for reducing the number of mobile stations and extending the use time of a mobile station is known.
JP-A-8-70273

  Any of the above-described conventional techniques function effectively in the communicable range, but use beyond the predetermined range is impossible even when the line-of-sight range is wide and the radio capability is sufficient.

  Therefore, even if a user with a mobile station is in distress or kidnapping, or even if a mobile station or a car carrying the mobile station is stolen or lost, it cannot be tracked if the destination is outside the communicable range. There was a problem such as.

  In view of such a problem, the present invention can perform highly stable wireless communication even in an area where the installation density of base stations is low by extending the communicable distance while avoiding multipath interference. An object of the present invention is to provide a wireless communication system, a mobile station, a base station, and a wireless communication method.

  In order to solve the above problems, a typical configuration of the present invention is a wireless communication system including a mobile station and a base station capable of wireless communication with the mobile station by TDMA, and the mobile station transmits data. The data transmission unit, the position information deriving unit from the GPS signal, the position information deriving unit to be included in the data, and the reception timing of the transmitted data at the base station within the prescribed timing, the data transmission timing is adjusted When the timing adjustment unit and the transmission timing adjustment limit are reached, the expansion request unit for requesting expansion / contraction of the effective frame length of the data, and the effective frame length of the data transmitted by the data transmission unit in response to the permission response to the expansion request An expansion / contraction execution unit that expands / contracts according to the distance from the base station based on the position information, and the base station includes a data reception unit that receives data, and an effective frame. In response to expansion and contraction requirements, the authorization response transmitting unit that transmits a permission response if by stretching has been enabled frame length can receive the data to the mobile station, characterized in that it comprises a. Here, the position information refers to information whose position can be specified by latitude and longitude, a relative position from an arbitrary point, or the like.

  In the present invention, the transmission timing of the transmission data itself is adjusted, and after reaching the adjustment limit, the effective frame length of the transmission data is expanded or contracted to extend the communicable distance while avoiding multipath interference. With this configuration, the amount of unit data that can be transmitted is reduced as the frame length is shortened, but communication with the base station can be continued even when the mobile station exceeds the normal communicable range. In this way, a user having a mobile station can perform highly stable wireless communication without worrying about the location and installation density of base stations. Such expansion of the communicable distance or communicable range also means that radio field intensity and power consumption can be reduced under the same communicable range.

  Further, in the present invention, since the position information of the mobile station can be continuously acquired, the position of the mobile station can be continuously and reliably grasped by another electric device. Therefore, even when a user having a mobile station is in distress or kidnapping, the position can be quickly identified, and even when a mobile station or a vehicle carrying the mobile station is stolen or lost. The object can be easily found.

  The expansion / contraction execution unit may expand / contract the effective frame length while securing a storage area for position information. With this configuration, it is possible to continuously acquire at least position information from the mobile station, and it is possible to more stably execute expansion / contraction of the effective frame length and position determination of the mobile station.

  The mobile station may further include a mode transition unit that transitions to the low power consumption mode when the transmission timing adjustment limit is reached.

  With such a configuration, it is possible to reduce power consumption while securing a minimum transmission path necessary for transmission of position information, and in particular, it is possible to continuously acquire position information for a long time.

  The mobile station may further include a standby power supply that is provided separately from the main power supply of the mobile station and cannot be disconnected from the outside of the mobile station casing and can transmit at least mobile information.

  By providing a standby power supply that cannot be intentionally disconnected from the outside, the location information of the mobile station can continue to be transmitted without being noticed by a third party who has illegally acquired the mobile station. It is possible to quickly secure a mobile station and a user of the mobile station.

  Another representative configuration according to the present invention is a mobile station capable of wireless communication with a base station using TDMA, a data transmission unit that transmits data, and position information that is derived from GPS signals and included in the data A derivation unit, a timing adjustment unit that adjusts the data transmission timing in order to keep the reception timing of the transmitted data at the base station within the specified timing, and an effective frame length of the data when the transmission timing adjustment limit is reached An expansion / contraction requesting unit that performs an expansion / contraction request, and an expansion / contraction execution unit that expands / contracts the effective frame length of the data transmitted by the data transmission unit in response to the permission response to the expansion / contraction request according to the distance from the base station based on the position information It is characterized by providing.

  Another typical configuration according to the present invention is a base station capable of wireless communication with a mobile station by TDMA, receiving a data receiving unit for receiving data, and an expansion / contraction request for an effective frame length from the mobile station, A permission response transmission unit that transmits a permission response to the mobile station if data can be received with the stretched effective frame length, and the mobile station expands and contracts the effective frame length of the data to be transmitted according to the permission response. It is characterized by doing.

  Another exemplary configuration according to the present invention is a wireless communication method for performing wireless communication using a mobile station and a base station capable of wireless communication with the mobile station by TDMA, wherein the mobile station is transmitted In order to keep the reception timing of data at the base station within the specified timing, the data transmission timing is adjusted, and when the transmission timing adjustment limit is reached, the base station is requested to extend or contract the effective frame length of the data. In response to a request for expansion / contraction of the effective frame length, if it is possible to receive data with the expanded / contracted effective frame length, a permission response is transmitted to the mobile station, and the mobile station derives location information from the GPS signal and permits In response to the response, the effective frame length of the data to be transmitted is expanded or contracted according to the distance from the base station based on the position information.

  The components corresponding to the technical idea in the wireless communication system and the description thereof can be applied to the mobile station, the base station, and the wireless communication method.

  As described above, the present invention makes it possible to perform highly stable wireless communication even in an area where the installation density of base stations is low, by extending the communicable distance while avoiding multipath interference. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  A mobile station represented by a PHS terminal, a mobile phone, or the like constructs a wireless communication system that performs wireless communication with a base station that is fixedly arranged at a predetermined interval. Here, in order to facilitate understanding, the entire wireless communication system will be described, and then specific configurations of a PHS terminal as a mobile station and a base station will be described. In addition, although a PHS terminal is cited here as a mobile station, the present invention is not limited to this, but a mobile phone, a notebook personal computer, a PDA (Personal Digital Assistant), a digital camera, a music player, a car navigation system, a portable TV, a game Various electronic devices capable of wireless communication, such as devices, DVD players, and remote controllers, can also be used as mobile stations.

(First embodiment: wireless communication system 100)
FIG. 1 is an explanatory diagram showing a schematic connection relationship of the wireless communication system 100. The wireless communication system 100 includes a PHS terminal 110 (110A, 110B), a base station 120 (120A, 120B), an ISDN (Integrated Services Digital Network) line, an Internet, a dedicated line, etc. And a relay server 140.

  In the wireless communication system 100, when a user connects a communication line from his / her PHS terminal 110A to another PHS terminal 110B, the PHS terminal 110A makes a wireless connection request to the base station 120A within the communicable range. . The base station 120A that has received the wireless connection request requests the relay server 140 to establish a communication connection with the communication partner via the communication network 130. The relay server 140 refers to the location registration information of the other PHS terminal 110B, and so on. The base station 120B within the wireless communication range of the PHS terminal 110B is selected to secure a communication path between the base station 120A and the base station 120B, and communication between the PHS terminal 110A and the PHS terminal 110B is established.

  Here, when the PHS terminal 110B as the communication partner moves, the distance between the PHS terminal 110B and the base station 120B increases, and finally, wireless communication with the base station 120B becomes difficult. The PHS terminal 110B predicts that wireless communication becomes difficult due to the attenuation of the electric field strength of the signal from the base station 120B, performs carrier sense again, and performs wireless communication with the base station 120C having high electric field strength. To request. When the base station 120B notifies the relay server 140 to that effect, the relay server 140 performs a handover from the base station 120B to the base station 120C.

  Continuation of communication within the communicable range is ensured by such a handover, but once communication goes out of the communicable range, communication is interrupted. In the present embodiment, it is possible to extend the communicable distance while avoiding interference due to multipath, and to perform highly stable wireless communication even outside the communicable range. Hereinafter, the PHS terminal 110 and the base station 120 configuring the wireless communication system 100 will be described in detail.

(PHS terminal 110)
FIG. 2 is a functional block diagram showing a hardware configuration of the PHS terminal 110, and FIG. 3 is a perspective view showing an appearance of the PHS terminal 110. As shown in FIG. The PHS terminal 110 includes a terminal control unit 210, a terminal memory 212, a display unit 214, an operation unit 216, a voice input unit 218, a voice output unit 220, a terminal wireless communication unit 222, and a standby power source 224. Consists of including.

  The terminal control unit 210 manages and controls the entire PHS terminal 110 using a semiconductor integrated circuit including a central processing unit (CPU). In addition, the terminal control unit 210 performs a call function, a mail transmission / reception function, an imaging function, a music playback function, and a TV viewing function using the program in the terminal memory 212. The terminal memory 212 includes a ROM, RAM, EEPROM, nonvolatile RAM, flash memory, HDD (Hard Disk Drive), and the like, and stores programs processed by the terminal control unit 210, audio data, and the like.

  The display unit 214 includes a liquid crystal display, EL (Electro Luminescence), etc., and is stored in the terminal memory 212 or provided from an application relay server (not shown) via the communication network 130. GUI (Graphical User 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 voice input unit 218 includes voice recognition means such as a microphone, and converts a user voice input during a call into an electrical signal that can be processed in the PHS terminal 110. The voice output unit 220 includes a speaker, and converts the voice signal of the other party received by the PHS terminal 110 into voice and outputs the voice. Further, a ring tone, an operation sound of the operation unit 216, an alarm sound, etc. can be output.

  The terminal wireless communication unit 222 performs wireless communication with the base station 120 in the communication network 130. As such wireless communication, time division multiple access (TDMA) that performs communication by allocating a plurality of time slots obtained by time-dividing frames in the base station 120 to the channels of the PHS terminal 110 is adopted. Has been.

  The standby power source 224 is configured with a capacitor and a secondary battery separately from the main power source of the PHS terminal 110, and is provided so that it cannot be disconnected from the outside of the housing of the PHS terminal 110 (so that it cannot be turned off and removed). Even after the main power supply is cut off, the minimum components necessary for transmitting position information such as the terminal wireless communication unit 222 are operated. By providing the standby power source 224 that cannot be intentionally disconnected from the outside, the location information of the PHS terminal 110 can be continuously transmitted without being noticed by a third party who has illegally acquired the PHS terminal 110. It is possible to quickly secure the PHS terminal 110 and the user of the PHS terminal 110 involved in the network.

  The terminal control unit 210 also functions as a data transmission unit 250, a position information deriving unit 252, a timing adjustment unit 254, an expansion / contraction requesting unit 256, an expansion / contraction execution unit 258, and a mode transition unit 260.

  The data transmission unit 250 transmits data processed in the PHS terminal 110 to the base station 120.

  The position information deriving unit 252 derives position information based on a GPS signal emitted from a GPS (Global Positioning System) satellite 262 and includes the position information in data transmitted by the data transmitting unit 250.

  With such a configuration, it is possible to continuously acquire the position information of the PHS terminal 110, so that the position of the PHS terminal 110 can be continuously and reliably grasped by other electric devices. Therefore, even when the user having the PHS terminal 110 is in distress or kidnapping, the position can be quickly identified, and the PHS terminal 110 or the vehicle carrying the PHS terminal 110 is stolen or lost. Even in this case, it is possible to easily find the object.

  The timing adjustment unit 254 adjusts the data transmission timing according to the distance from the base station 120 in order to keep the reception timing of the data transmitted by the data transmission unit 250 at the base station 120 within a specified timing. It is also possible to form a closed loop between the base station 120 and the PHS terminal 110, and to adjust the transmission timing linearly by feeding back a shift in reception timing.

  4 is an explanatory diagram showing a change in the position of the PHS terminal 110, and FIG. 5 is a timing chart showing a change in data from the PHS terminal 110. As shown in FIG. Here, in the time slot 280 allocated to one PHS terminal 110 in TDMA, a valid frame 282 and a guard interval 284 are prepared as transmission data. The valid frame 282 further includes a header 286, a payload 288, and a footer 290. It consists of.

  Since the base station 120 performs wireless communication with a plurality of PHS terminals 110 having different distances, the prescribed communication timing of the base station 120 cannot be changed. Therefore, the delay time of the communication signal that changes according to the communication distance should be corrected in the PHS terminal 110.

  For example, when the PHS terminal 110 is located at the position (a) in FIG. 4, the data transmitted from the base station 120 to the other PHS terminals is only the propagation delay d as shown in FIG. It arrives late. Similarly, data transmitted from the PHS terminal 110 is transmitted to the base station 120 with a delay of the propagation delay d. Therefore, in order to receive the data transmitted by the PHS terminal 110 at the prescribed reception timing of the base station 120, it is necessary to advance the transmission timing of the transmission data by the propagation delay d as indicated by the white arrow in the figure.

  However, if the transmission timing of the PHS terminal 110 is simply advanced, data transmitted from the base station 120 to another PHS terminal or data transmitted from the adjacent PHS terminal 110 may cause interference due to multipath. Thus, the transmission data is provided with a guard interval 284 in addition to the effective frame 282 as described above. At the position (a) of the PHS terminal 110, there is no problem if adjacent transmission data is superimposed within the guard interval 284.

  The propagation delay d is proportional to the distance between the PHS terminal 110 and the base station 120, and increases as the distance increases. Therefore, the PHS terminal 110 keeps updating its transmission timing according to the distance from the base station 120. Here, when the PHS terminal 110 moves to the position (b) in FIG. 4 and reaches the boundary 292 of the communicable range, the data transmission timing is advanced. Finally, as shown in FIG. 5 (b), the guard interval 284 is allowed. It reaches the range and causes interference. Therefore, there is a limit (the state shown in FIG. 5B) for adjusting the transmission timing. Therefore, the value obtained by dividing the time of the guard interval 284 by the propagation speed is the limit (maximum value) of the communicable distance.

  Conventionally, when the PHS terminal 110 exceeds the boundary 292 of such a communicable range, timing interference with other signals occurs, and normal communication cannot be maintained.

  When reaching the transmission timing adjustment limit as shown in FIG. 5B, the expansion / contraction requesting unit 256 requests the base station 120 to expand / contract the effective frame length of the data. Here, the expansion / contraction requesting unit 256 may make the expansion / contraction request only after the PHS terminal 110 is located outside the communicable range for a predetermined time or more. This is because the boundary 292 of the communicable range is provided with hysteresis to prevent complicated switching between the transmission timing adjustment by the timing adjustment unit 254 and the expansion / contraction request by the expansion / contraction requesting unit 256. As the predetermined time, 0 sec or more can be set.

  The expansion / contraction requesting unit 256 may add the effective frame length after expansion / contraction to the above-described expansion / contraction request. In that case, the base station 120 can measure the next reception timing with reference to the effective frame length.

  The expansion / contraction execution unit 258 receives a permission response to the expansion / contraction request from the expansion / contraction requesting unit 256 from the base station 120, and expands / contracts the effective frame length of the data transmitted by the data transmission unit 250 according to the distance from the base station 120. For example, when the PHS terminal 110 moves to the position (c) of FIG. 4, the effective frame 282 of the transmission data from the PHS terminal 110 is shortened as shown in FIG. It can be avoided. At this time, the received data at the base station 120 is reduced to a part 294 of the time slot 280. Here, only the shortening of the effective frame 282 is mentioned, but it goes without saying that it can be expanded.

  Since the base station 120 is fixed in position, the position information of the base station 120 can be acquired in advance at the time of initial setting. The distance to the base station 120 can be obtained from the linear distance by comparing the position information acquired by the position information deriving unit 252 with the position information of the base station 120 acquired in advance.

  In the present embodiment, the timing adjustment unit 254 first adjusts the transmission timing of the transmission data itself, and after reaching the adjustment limit, the expansion / contraction execution unit 258 expands / contracts the effective frame length of the transmission data, thereby preventing interference due to multipath. While avoiding this, the communicable distance is extended. With this configuration, the amount of unit data that can be transmitted is reduced as the frame length is reduced, but communication with the base station 120 can be continued even when the PHS terminal 110 exceeds the conventional communicable range. . In this way, a user having the PHS terminal 110 can perform highly stable wireless communication without worrying about the location and installation density of the base station 120. Such expansion of the communicable distance or communicable range also means that radio field intensity and power consumption can be reduced under the same communicable range.

  The expansion / contraction execution unit 258 expands / contracts the effective frame length while securing at least the storage area for the position information derived by the position information deriving unit 252. When the PHS terminal 110 is further away from the position (c) in FIG. 4, the payload 288 in the effective frame 282 is further shortened, and finally the effective frame 282 includes only the header 286 and the footer 290 as shown in FIG. It becomes. As described above, the minimum information necessary for maintaining the communication including the position information is secured as the header 286 and the footer 290. With this configuration, it is possible to continuously acquire at least position information from the PHS terminal 110, and it is possible to more stably execute expansion / contraction of the effective frame length and position determination of the PHS terminal 110.

  The mode transition unit 260 transitions to the low power consumption mode when the transmission timing adjustment limit is reached. In the low power consumption mode, for example, the backlight of an LCD (Liquid Crystal Display) may be turned off, or transmission data from the terminal wireless communication unit 222 may be transmitted intermittently.

  With such a configuration, it is possible to reduce power consumption while securing a minimum transmission path necessary for transmission of position information, and in particular, it is possible to continuously acquire position information for a long time.

  The transmission side of the terminal wireless communication unit 222 also functions as a payload generation unit 270 and a header addition unit 272.

  The payload generation unit 270 generates the payload 288 by dividing the data to be transmitted with the frame length expanded / contracted by the expansion / contraction execution unit 258.

  The header adding unit 272 generates a valid frame 282 by adding a header 286 and a footer 290 to the payload 288 generated by the payload generating unit 270. At this time, the position information of the position information deriving unit 252 is included in the header 286 or the footer 290.

(Base station 120)
FIG. 6 is a block diagram illustrating a schematic configuration of the base station 120. The base station 120 includes a base station control unit 310, a base station memory 312, a base station wireless communication unit 314, and a base station wired communication unit 316.

  The base station control unit 310 manages and controls the entire base station 120 using a semiconductor integrated circuit including a central processing unit (CPU). Further, the base station control unit 310 controls communication connection of the PHS terminal 110 to the communication network 130 and other PHS terminals 110 using a program in the base station memory 312. The base station memory 312 includes a ROM, RAM, EEPROM, nonvolatile RAM, flash memory, HDD, and the like, and stores programs processed by the base station control unit 310, time information, and the like.

  The base station radio communication unit 314 can establish communication with the PHS terminal 110 and adaptively change the modulation scheme and codec according to the communication quality of the PHS terminal 110. The base station wired communication unit 316 can be connected to various servers including the relay server 140 via the communication network 130.

  The base station control unit 310 also functions as the data reception unit 350 and the permission response transmission unit 352.

  The data receiving unit 350 receives data via the terminal wireless communication unit 222. In response to the request for expansion / contraction of the effective frame length from the PHS terminal 110, the permission response transmission unit 352 returns a permission response to the PHS terminal 110 if it is possible to receive data with the expanded / contracted effective frame length.

  Further, the receiving side of the base station radio communication unit 314 functions as a frame position detection unit 370, a header detection unit 372, and a payload extraction unit 374.

  The frame position detection unit 370 grasps the head position of data received from the PHS terminal 110 and detects the arrangement of effective frames.

  The header detection unit 372 detects the header 286 and the footer 290 from the frame detected by the frame position detection unit 370 with reference to the frame length requested by the expansion / contraction requesting unit 256. The header detection unit 372 further extracts position information from the header 286 or the footer 290.

  The payload extracting unit 374 detects the header 286 and the footer 290 by the header detecting unit 372, extracts the remaining valid frame 282, and transmits it to the base station control unit 310 as normal data.

  Next, a radio communication method executed by the PHS terminal 110 and the base station 120 in the radio communication system 100 described above will be described.

(Wireless communication method)
FIG. 7 is a sequence diagram showing a specific processing flow of a wireless communication method using the PHS terminal 110 and the base station 120. The PHS terminal 110 establishes wireless communication with the base station 120 within the communicable range, and transmits data including position information derived from the GPS signal to the base station 120 (S400). At this time, the PHS terminal 110 adjusts the data transmission timing so that the reception timing of the transmitted data at the base station 120 falls within a specified timing (S402).

  When the transmission timing adjustment limit is reached (S404), the PHS terminal 110 requests the base station 120 to expand and contract the effective frame length of the data (S406), and the base station 120 requests the expansion and contraction of the effective frame length. In response, if it is possible to receive data with the expanded / contracted effective frame length, a permission response is returned to the PHS terminal 110 (S408).

  The PHS terminal 110 receives the permission response from the base station 120 and expands / contracts the effective frame length of the data to be transmitted according to the distance from the base station 120 based on the position information of the PHS terminal 110 (S410). Data is transmitted to the base station 120 based on the frame length (S412).

  By extending the communicable distance while avoiding multipath interference by this wireless communication method, highly stable wireless communication can be performed even in an area where the installation density of base stations is low.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, an example is shown in which the expansion and contraction of the effective frame length is started when the PHS terminal 110 deviates from the communicable range. However, the present invention is not limited to this, and communication is performed when the PHS terminal 110 is turned on. Even when it is out of the possible range, it is possible to detect the state and immediately start expansion / contraction of the effective frame length.

  Note that each step in the wireless communication method of the present specification does not necessarily have to be processed in time series in the order described as a sequence diagram, and may include processing in parallel or by a subroutine.

  The present invention can be used for a radio communication system, a mobile station, a base station, and a radio communication method capable of radio communication by TDMA.

It is explanatory drawing which showed the rough connection relation of the radio | wireless communications system. It is the functional block diagram which showed the hardware constitutions of the PHS terminal. It is the perspective view which showed the external appearance of the PHS terminal. It is explanatory drawing which showed the change of the position of a PHS terminal. It is the timing chart figure which showed the change of the data from the PHS terminal. It is the block diagram which showed the schematic structure of the base station. It is the sequence diagram which showed the flow of the specific process of the radio | wireless communication method using a PHS terminal and a base station.

Explanation of symbols

100 ... Wireless communication system 110 ... PHS terminal (mobile station)
DESCRIPTION OF SYMBOLS 120 ... Base station 224 ... Standby power supply 250 ... Data transmission part 252 ... Position information deriving part 254 ... Timing adjustment part 256 ... Expansion / contraction requesting part 258 ... Expansion / contraction execution part 260 ... Mode transition part 270 ... Payload generation part 272 ... Header addition part 282 ... Valid frame 284 ... Guard interval 286 ... Header 290 ... Footer 350 ... Data receiver 352 ... Permit response transmitter 370 ... Frame position detector 372 ... Header detector 374 ... Payload extractor

Claims (7)

A wireless communication system including a mobile station and a base station capable of wireless communication with the mobile station by TDMA,
The mobile station
A data transmission unit for transmitting data;
A position information deriving unit for deriving position information from the GPS signal and including it in the data;
A timing adjustment unit for adjusting the transmission timing of the data in order to keep the reception timing of the transmitted data at the base station within a specified timing;
When the transmission timing adjustment limit is reached, an expansion / contraction requesting unit that performs an expansion / contraction request for the effective frame length of the data;
An expansion / contraction execution unit that expands / contracts the effective frame length of the data transmitted by the data transmission unit in response to the permission response to the expansion / contraction request according to the distance from the base station based on the position information;
With
The base station
A data receiver for receiving data;
In response to the expansion / contraction request of the effective frame length, if it is possible to receive data with the expanded / contracted effective frame length, a permission response transmission unit that transmits a permission response to the mobile station;
A wireless communication system comprising:   The wireless communication system according to claim 1, wherein the expansion / contraction execution unit expands / contracts an effective frame length while securing a storage area for the position information.   The wireless communication system according to claim 1, wherein the mobile station further includes a mode transition unit that transitions to a low power consumption mode when the transmission timing adjustment limit is reached.   2. The mobile station further includes a standby power source provided separately from a main power source of the mobile station, which cannot be disconnected from outside the housing of the mobile station and can transmit at least the mobile information. 4. The wireless communication system according to any one of items 1 to 3. A mobile station capable of wireless communication with a base station by TDMA,
A data transmission unit for transmitting data;
A position information deriving unit for deriving position information from the GPS signal and including it in the data;
A timing adjustment unit for adjusting the transmission timing of the data in order to keep the reception timing of the transmitted data at the base station within a specified timing;
When the transmission timing adjustment limit is reached, an expansion / contraction requesting unit that performs an expansion / contraction request for the effective frame length of the data;
An expansion / contraction execution unit that expands / contracts the effective frame length of the data transmitted by the data transmission unit in response to the permission response to the expansion / contraction request according to the distance from the base station based on the position information;
A mobile station comprising: A base station capable of wireless communication with a mobile station by TDMA,
A data receiver for receiving data;
In response to a request for expansion / contraction of the effective frame length from the mobile station, if it is possible to receive data with the expanded / contracted effective frame length, a permission response transmission unit that transmits a permission response to the mobile station;
With
The base station characterized in that the mobile station expands and contracts an effective frame length of data to be transmitted according to the permission response. A wireless communication method for performing wireless communication using a mobile station and a base station capable of wireless communication with the mobile station by TDMA,
The mobile station
In order to keep the reception timing of the transmitted data at the base station within a specified timing, the transmission timing of the data is adjusted,
When the adjustment limit of the transmission timing is reached, a request to expand and contract the effective frame length of the data is made to the base station,
The base station
In response to the expansion / contraction request of the effective frame length, if it is possible to receive data with the expanded / contracted effective frame length, an authorization response is transmitted to the mobile station,
The mobile station
Deriving location information from GPS signals,
The wireless communication method according to claim 1, wherein the effective frame length of data to be transmitted is expanded or contracted according to the distance from the base station based on the position information in response to the permission response.

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