WO2014061361A1 - 通信方法、通信端末、基地局及び通信システム - Google Patents
通信方法、通信端末、基地局及び通信システム Download PDFInfo
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- WO2014061361A1 WO2014061361A1 PCT/JP2013/073767 JP2013073767W WO2014061361A1 WO 2014061361 A1 WO2014061361 A1 WO 2014061361A1 JP 2013073767 W JP2013073767 W JP 2013073767W WO 2014061361 A1 WO2014061361 A1 WO 2014061361A1
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- H—ELECTRICITY
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- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
- H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/02—Services making use of location information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
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- H—ELECTRICITY
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- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
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- H04B7/216—Code division or spread-spectrum multiple access [CDMA, SSMA]
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- H04W74/08—Non-scheduled access, e.g. ALOHA
- H04W74/0833—Random access procedures, e.g. with 4-step access
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- H04W84/06—Airborne or Satellite Networks
Definitions
- the present invention relates to a communication method, a communication terminal, a base station, and a communication system.
- a slotted-ALOHA method and a CDMA (Code Division Multiple Access) method A combination of these is known.
- a communication terminal on the transmission side transmits transmission data spread using a spread code assigned individually at a specific slot interval in synchronization with a slot on the time axis.
- This is a system in which a station despreads received data using the same spreading code as that on the transmitting side and extracts necessary data.
- Patent Document 1 in order to reduce the occurrence of packet collision, the base station notifies each terminal device of delay time information, and each communication terminal sets the transmission timing based on the delay time information acquired from the base station.
- the technique to adjust is disclosed.
- the present invention has been made to solve the above problems, and provides a communication method, a communication terminal, a base station, and a communication system capable of high throughput of communication between a base station and a communication terminal via a satellite
- the purpose is to do.
- Another object of the present invention is to enable a large number of victims to transmit rescue messages when a disaster occurs.
- a communication method is a communication method used for a communication terminal that transmits transmission data that is CDMA-spread to a base station via a satellite, for transmitting the transmission data by CDMA.
- a spread code channel selection step for randomly selecting a spread code channel, a time slot channel selection step for randomly selecting a time slot channel for transmitting CDMA spread transmission data, and a frequency channel for transmitting CDMA spread transmission data The frequency code selection step, the time slot channel selected in the time slot channel selection step, and the frequency corresponding to the frequency channel selected in the frequency channel selection step are selected in the spreading code channel selection step.
- C in the spread code channel Comprising a transmission step of transmitting the MA spread transmit data.
- the present invention it is possible to suppress the collision of data transmitted simultaneously by a large number of communication terminals, increase the success rate of communication, that is, increase the throughput, and prevent the communication line from falling into a congestion state.
- FIG. 1 is a schematic diagram of a communication system (communication terminal, base station, satellite) according to Embodiment 1 of the present invention. It is a functional block diagram of the communication terminal which concerns on Embodiment 1 of this invention. It is a figure which shows the combination of the access system of the communication terminal which concerns on Embodiment 1 of this invention. It is a flowchart which shows the transmission process of the communication terminal which concerns on Embodiment 1 of this invention. It is a flowchart which shows the process regarding selection of the combination of an access method among the transmission processes of the communication terminal which concerns on Embodiment 1 of this invention. It is a functional block diagram of the communication terminal which concerns on the modification of Embodiment 1 of this invention.
- the communication terminal which concerns on Embodiment 1, 2 and 5 of this invention, it is the table used normally and which is stored in the table memory
- a table for selecting a relatively slow time slot channel stored in the table storage unit that is referred to for selecting a combination of access methods It is. It is a functional block diagram of the communication terminal which concerns on Embodiment 2 of this invention.
- a plurality of predetermined areas obtained from position information according to Embodiment 3 of the present invention are shown, and the predetermined area includes another predetermined area (circular-circular) within the area It is a figure which shows an example.
- a plurality of predetermined regions obtained from position information according to the third embodiment of the present invention are shown, and the predetermined region includes another predetermined region (cloud type-rectangle) in the region. It is a figure which shows the example to do.
- a plurality of predetermined regions obtained from position information according to Embodiment 3 of the present invention are shown, and the predetermined region is another predetermined region (a plurality of circular aggregates- It is a figure which shows the example containing a circle.
- stored is referred for selection of the access system combination.
- stored is referred for selection of the access system combination.
- a communication terminal starts transmission at a specific slot interval in synchronization with a transmission timing of transmission data in a slot on a time axis. Also, it is necessary to use a synchronization signal for adjusting the transmission timing to the time slot, and this synchronization signal is transmitted from the base station to each communication terminal.
- the communication system according to the embodiment of the present invention transmits the rescue message all at once from the time when the communication terminal receives the rescue service start signal from the base station when a large-scale disaster occurs.
- the system cannot adopt the slot aloha method, which is likely to cause a transmission delay due to a collision of transmission data. Therefore, in the following embodiments, a combination of CDMA (Code Division Multiple Access) / FDMA (Frequency Division Multiple Access) / TDMA (Time Division Multiple Access) is used.
- CDMA Code Division Multiple Access
- FDMA Frequency Division Multiple Access
- TDMA Time Division Multiple Access
- Embodiment 1 FIG.
- the same reference numerals indicate the same or corresponding parts, and detailed descriptions thereof are omitted.
- a communication system in which a base station communicates with a plurality of communication terminals via a satellite, and 2) transmission data that is CDMA-spread to the base station via a satellite.
- a communication terminal for transmitting as a signal 3) a base station for communicating with a plurality of communication terminals via a satellite, and 4) a communication method used for a communication terminal for transmitting CDMA spread transmission data to the base station via a satellite about.
- a communication system 100 includes a plurality of satellites 1, a base station 2, a plurality of communication terminals 3, and a plurality of GPS (Global Positioning System) satellites 4.
- GPS Global Positioning System
- the plurality of satellites 1 are composed of satellites 1 that relay wireless communication between the base station 2 and the communication terminal 3.
- Each satellite 1 is composed of a quasi-zenith satellite and orbits a predetermined orbit. At least one satellite 1 exists above a specific area.
- the base station 2 performs wireless communication with the communication terminal 3 via the satellite 1. More specifically, the base station 2 distributes the forward link signal to the communication terminal 3 via the satellite 1 using the forward link communication line 17. In addition, a return link signal transmitted from the communication terminal 3 using the return link communication line 18 is received via the satellite 1.
- the base station 2 is connected to the satellite tracking control center 15 and the service center 16 via the ground network 14.
- the terrestrial network 14 is a communication network that performs data transmission based on a protocol such as TCP / IP (Transmission Control Protocol / Internet Protocol).
- the satellite tracking control center 15 transmits and receives satellite tracking information for tracking the orbit of the satellite 1 to and from the base station 2 via the ground network 14.
- the service center 16 acquires various data transmitted from the communication terminal 3 received by the base station 2 via the ground network 14 and transmits various data to be distributed to the communication terminal 3 to the base station 2.
- the communication terminal 3 performs wireless communication with the base station 2 via the satellite 1.
- the communication terminal 3 includes a communication terminal 3A, a communication terminal 3B, and a communication terminal 3C.
- the communication terminals 3A to 3C may be collectively referred to as the communication terminal 3, and any one of the communication terminals 3A to 3C may be referred to as the communication terminal 3.
- the number of communication terminals 3 is not limited to three.
- the communication terminal 3 transmits a return link signal to the base station 2 with the reception of the forward link signal transmitted from the base station 2 as a trigger.
- Return link signals respectively transmitted from the communication terminal 3A, the communication terminal 3B, and the communication terminal 3C are transmitted to the satellite 1 using the independent return link communication lines 18, are integrated in the satellite 1, and are transmitted to the base station 2. Is done.
- the GPS satellite 4 transmits a GPS signal 19 including position information and time information to the communication terminal 3.
- the satellite 1 may have the function of the GPS satellite 4.
- the forward link communication line 17 is a communication path through which the base station 2 transmits a forward link signal to the communication terminal 3 via the satellite 1.
- the return link communication line 18 is a communication path through which the communication terminal 3 transmits a return link signal to the base station 2 via the satellite 1.
- the GPS signal 19 is a signal including GPS information (position information and time information) transmitted from the GPS satellite 4 and received by the communication terminal 3.
- the communication terminal 3 includes a satellite communication antenna (communication terminal side satellite communication antenna) 3s, a GPS antenna 3g, a reception unit 6, a transmission unit 7, an information acquisition unit 8, and a spread code generation unit 9.
- a random selection unit 10 a duplexer 20, a data output terminal 21, a transmission data processing unit 22, a data input terminal 23, a transmission timing generation unit 32, a storage unit 96, a display unit 97, an operation unit 98, and a control unit 99. 2 illustrates the storage unit 96, the display unit 97, the operation unit 98, and the control unit 99.
- the control unit 99 may function so as to control each component, or each component may have a function of the control unit 99 as appropriate.
- the satellite communication antenna 3s receives the forward link signal transmitted from the base station 2 through the forward link communication line 17.
- the satellite communication antenna 3 s transmits a return link signal to the base station 2 through the return link communication line 18.
- the GPS antenna 3 g receives the GPS signal 19 transmitted from the GPS satellite 4 and outputs it to the information acquisition unit 8.
- the reception unit 6 includes a radio reception unit 24, a QPSK demodulation unit 25, an error correction decoding unit 26, and a TDM separation unit 27, and demodulates and outputs a forward link signal.
- the radio receiver 24 amplifies the forward link signal supplied via the satellite communication antenna 3 s and the duplexer 20 with low noise and supplies it to the QPSK demodulator 25.
- the QPSK demodulator 25 demodulates the forward link signal supplied from the radio receiver 24 into a QPSK modulated wave (baseband signal) and supplies it to the error correction decoder 26.
- the error correction decoding unit 26 performs error correction decoding using redundant bits added to the forward link signal, and acquires original information data.
- the TDM demultiplexing unit 27 demultiplexes transmission data addressed to the terminal itself or transmission data in which the control data is time-division multiplexed by TDM (Time Division Multiplex) to obtain reception data addressed to the terminal. And output to the reception data output terminal 21.
- TDM Time Division Multiplex
- the transmission unit 7 includes a CDMA spreading unit 11, a TDMA processing unit 12, a BPSK modulation unit 33, an FDMA processing unit 13, and a wireless transmission unit 34, and transmits transmission data supplied from the transmission data processing unit 22.
- the signal is modulated and transmitted from the satellite communication antenna 3 s through the duplexer 20.
- the CDMA spreading unit 11 CDMA spreads the transmission data by multiplying the transmission data received from the transmission data processing unit 22 by the spreading code (orthogonal code) generated by the spreading code generation unit 9.
- the TDMA processing unit 12 delays the transmission data CDMA spread by the CDMA spreading unit 11 according to the time slot for transmitting the transmission data.
- a BPSK (Binary Phase Shift Keying) modulation unit 33 discretely changes the phase of the carrier wave according to the transmission data output from the TDMA processing unit 12 and converts the phase into an electrical signal suitable for transmission. That is, BPSK modulation is performed on the transmission data.
- the FDMA processing unit 13 performs frequency conversion on the transmission data signal output from the BPSK modulation unit 33.
- the radio transmission unit 34 amplifies the power of the transmission data signal output from the FDMA processing unit 13 and transmits the amplified signal from the satellite communication antenna 3s via the duplexer 20.
- the information acquisition unit 8 includes a GPS reception unit 28 and a GPS signal processing unit 29, and receives the GPS signal 19 via the GPS antenna 3g.
- the GPS signal receiving unit 28 receives the GPS signal 19 from the GPS satellite 4 via the GPS antenna 3g.
- the GPS signal processing unit 29 processes the GPS signal 19, decodes the position information and the time information, and transmits the time information to the transmission timing generation unit 32.
- the spreading code generator 9 generates a spreading code in response to the chip lock spreading code start timing output from the transmission timing generator 32.
- the random selection unit 10 randomly selects a spreading code channel to be used by the spreading code generation unit 9 and notifies the spreading code generation unit 9 of it.
- the random selection unit 10 randomly selects a time slot channel that is a basis of the time for which the TDMA processing unit 12 delays transmission data, and notifies the TDMA processing unit 12 of the time slot channel.
- the random selection unit 10 randomly selects a frequency channel for frequency conversion by the FDMA processing unit 13 and notifies the FDMA processing unit 13 of the frequency channel.
- the duplexer 20 supplies the signal received from the communication satellite via the satellite communication antenna 3s to the reception unit 6, and supplies the transmission signal supplied from the transmission unit 7 to the satellite communication antenna 3s.
- the transmission data processing unit 22 includes a data generation unit 30 and an error correction encoding unit 31, generates transmission data to which an error correction code is attached, and supplies the transmission data to the CDMA spreading unit 11.
- the data generation unit 30 generates data to be transmitted (transmission data) in synchronization with the data clock signal supplied from the transmission timing generation unit 32.
- the error correction encoding unit 31 synchronizes the transmission data output from the data generation unit 30 with a synchronization bit so that communication between the plurality of communication terminals 3 is synchronized.
- a control bit or the like is added to generate transmission data in a burst format, a redundant bit is added to perform error correction coding, and output to the CDMA spreading unit 11.
- the storage unit 96 includes a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk device, and the like, and stores various data and various programs.
- ROM Read Only Memory
- RAM Random Access Memory
- the display unit 97 receives the image information supplied from the control unit 99, processes the image information, converts the image information into an image signal at a predetermined synchronization timing, and displays the image signal.
- the display unit 97 includes a liquid crystal display, an organic EL (Electro-Luminescence) display, and the like. Moreover, the apparatus with which the input function and display functions like a touch panel provided with a touch switch function were combined may be sufficient.
- the operation unit 98 accepts various operations and instructions from the user of the communication terminal 3.
- the operation unit 98 processes an input signal from the user and supplies the processed input signal to the control unit 99.
- the operation unit 98 includes, for example, an input button, a touch panel, and the like that are mounted on the communication terminal 3.
- the control unit 99 includes a CPU (Central Processing Unit) and the like, and performs signal processing and controls the operation of each unit.
- the control unit 99 generates transmission data by signal processing in response to a forward link signal output from the reception unit 6 to the data output terminal 21 and transmits the transmission data via the data input terminal 23. Transmission data is supplied to the data processing unit 22.
- the control unit 99 controls the operation timing of each unit.
- the control unit 99 is shown as an independent configuration, but the control unit 99 may have functions of other configurations.
- the control unit 99 may have the functions of the spread code generation unit 9, the random selection unit 10, the transmission data processing unit 22, and the timing generation unit 32.
- the communication terminal 3 transmits data to the base station 2 via the satellite 1
- the receiving unit 6 decodes the forward link signal and outputs the forward link signal to the data output terminal 23.
- the control unit 99 In response to receiving the forward signal, the control unit 99 generates data to be transmitted and supplies the data to the transmission data processing unit 22 via the data input terminal 23.
- the data generation unit 30 of the transmission data processing unit 22 converts the data input from the data input terminal 23 into data in a predetermined burst format by adding a synchronization bit, a control bit, etc., and sends it to the error correction encoding unit 31. Supply.
- the error correction encoding unit 31 performs error correction encoding on the transmission data acquired from the data generation unit 30.
- the transmission data generated by the transmission data processing unit 22 is supplied to the CDMA spreading unit 11 of the transmission unit 7.
- the CDMA spreading unit 11 CDMA spreads the transmission data by multiplying the transmission data by the spreading code (orthogonal code) generated by the spreading code generation unit 9.
- the TDMA processing unit 12 delays the transmission data CDMA spread by the CDMA spreading unit 11 according to the time slot for transmitting.
- the BPSK modulator 33 discretely changes the phase of the carrier wave according to the transmission data, and converts it into an electrical signal suitable for transmission.
- the FDMA processing unit 13 performs frequency conversion on the transmission data signal phase-modulated by the BPSK modulation unit 33.
- the wireless transmission unit 34 performs power amplification on the transmission data signal acquired from the FDMA processing unit 13 and transmits the transmission data signal to the base station 2 via the duplexer 20 and the satellite communication antenna 3s.
- the transmission timing generation unit 32 generates a clock signal and timing signal synchronized with the time signal acquired from the GPS signal processing unit 29 in order to synchronize the spread code start timing and the like among the plurality of communication terminals 3.
- the data generation unit 30 and the error correction encoding unit 31 respond to the data clock signal output from the transmission timing generation unit 32 and the error correction encoding clock so that communication is synchronized between the plurality of communication terminals 3.
- the transmission data is converted into data of a predetermined burst format in which synchronization bits, control bits, etc. are added, and redundant bits are added to perform error correction coding.
- the transmission timing generation unit 32 generates a transmission timing signal including a chip clock for spreading code generation, a spreading code start timing signal, and the like in order to synchronize the spreading code start timing among the plurality of communication terminals 3.
- the spread code generation unit 9 randomly selects one spread code from a plurality (L) of spread codes, and selects the spread code in response to the chip clock synchronized with the GPS time signal and the spread code start timing signal. Generate a spreading code.
- the chip clock and spreading code start timing of the spreading code of the CDMA signal transmitted from the plurality of communication terminals 3 to the satellite 1 can be synchronized between the plurality of communication terminals 3. Therefore, if the distances from the plurality of communication terminals 3 to the satellite 1 are substantially the same, the chip clock of the spreading code of the CDMA signal transmitted from each communication terminal 3 on the transponder of the satellite 1 and the spreading code start timing are synchronized.
- the communication terminal 3 includes an information acquisition unit 8 that acquires GPS information from the GPS satellite 4, and a spread code generation unit based on the spread code start timing generated from the time information included in the GPS information by the transmission timing generation unit 32. 9 generates a spreading code.
- the random selection unit 10 of the communication terminal 3 not only randomly selects and supplies the spreading code channel used by the spreading code generation unit 9, but also serves as a basis for the time for the TDMA processing unit 12 to delay the transmission data. A time slot channel is selected and supplied at random, and a frequency channel for frequency conversion by the FDMA processing unit 13 is selected and supplied at random.
- the transmission data CDMA spread by the CDMA spreading unit 11 is time-delayed by the TDMA processing unit 12 so as to be transmitted in this time slot according to the time slot channel acquired from the random selection unit 10. Thereafter, the transmission data is BPSK modulated by the BPSK modulation unit 33, frequency-converted to a frequency corresponding to the frequency channel input from the random selection unit 10 by the FDMA processing unit 13, and then power amplified by the wireless transmission unit 34. Then, it is transmitted to the satellite 1 as a transmission burst signal (return link signal) from the satellite communication antenna 3s via the duplexer 20 using the return link communication line 18.
- a transmission burst signal return link signal
- each communication terminal 3 uses a combination of a spread code channel, a time slot channel, and a frequency channel that are randomly set by the random selection unit 10 (random access by CDMA / FDMA / TDMA). "Access method combination").
- communication terminal 3A selects a combination of spreading code A, frequency CH1, and time slot 1
- communication terminal 3B selects a combination of spreading code B, frequency CH3, and time slot 2, and communication terminal 3C ,
- An example in which a combination of spreading code C, frequency CH2, and time slot 2 is selected is shown.
- the transmission timing of the time slot and the chip timing of the spreading code are synchronized with the GPS time signal.
- the communication terminals 3A to 3C since the communication terminals 3A to 3C have different access method combinations, there is no collision of transmission data on the satellite 1.
- the communication terminal 3 determines a channel for accessing the satellite 1 by a combination of access methods randomly selected by the random selection unit 10. Therefore, even if a large number of communication terminals 3 access the satellite 1 at the same time, the probability that the data transmitted by the communication terminals 3 collide is low. In addition, the probability that communication cannot be performed is low and the throughput is high. Further, there is a low possibility that the communication terminal 3 and the base station 2 cannot communicate with each other because the line is congested. The degree of this effect varies depending on the number of spreading code channels, the number of time slot channels, the number of frequency channels, and the number of communication terminals 3 that communicate simultaneously. For this reason, the numbers of spreading code channels, time slot channels, and frequency channels may be set according to the “probability that the combinations of access methods do not match”.
- the communication terminal 3 transmits a short message (short message, short message, location) such as safety information including personal identification information (ID information) and position information to each other via the satellite 1. It can also be said to be a short message (hereinafter referred to as a short message).
- a short message such as safety information including personal identification information (ID information) and position information
- ID information personal identification information
- the service center 16 may receive a rescue message including identification information and location information from a plurality of communication terminals 3 when a disaster occurs.
- the service center 16 instructs the base station 2 to transmit a forward link signal to the mobile terminal 3 of the victim.
- the base station 2 transmits a forward link signal to the victim's portable terminal 3 via the forward link communication line 17.
- the communication terminal 3 receives the forward link signal transmitted from the base station 2 through the forward link communication line 17.
- the communication terminal 3 uses the reception of the forward link signal as a trigger, and sends a return link signal (transmission signal) including its own location information, rescue message, emergency message, rescue signal, etc. via the return link communication line 18 to the base station 2.
- the base station 2 transmits the received return link signal to the service center 16 via the ground network 14.
- the service center 16 receives the return link signal. Thereby, the service center 16 can acquire the information of the victim.
- the service center 16 that has received the short message including the information on the victim can transmit a reply message including the ACK signal to the communication terminal 3 that has transmitted the short message through the forward link communication line 17.
- FIG. 4 is a flowchart of the transmission process of the communication terminal 3.
- This transmission process is a process in which the communication terminal 3 transmits transmission data subjected to CDMA spreading to the base station 2 via the satellite 1.
- control unit 99 when the communication terminal 3 is powered on, the control unit 99 starts up the information acquisition unit 8 and receives the GPS signal 19 via the GPS antenna 3g (step S101). In addition, the control unit 99 starts up the receiving unit 6 and receives the forward link signal from the base station 2 via the satellite communication antenna 3s (step S102). Usually, the communication terminal 3 is powered on. However, the power supply of the communication terminal 3 may be turned on as necessary.
- step S103 It is determined whether or not the communication terminal 3 transmits data (step S103).
- the determination of whether to transmit data is performed as follows, for example.
- the service center 16 starts the rescue message service and notifies the start of the service control data (this is referred to as a “rescue service start signal”.
- a rescue service start signal When the use is not a rescue message service. Or simply referred to as a “service start signal”) is transmitted to the base station 2 via the terrestrial network 14.
- the base station 2 transmits a rescue service start signal to all the communication terminals 3 as control data on the forward link signal.
- step S102 the control unit 99 determines whether or not a rescue message service start signal (service start signal) is included in the forward link signal from the received data acquired from the TDM separation unit 27.
- a rescue message service start signal (service start signal) is included in the forward link signal
- the rescue message transmission button may be a button displayed on a touch panel type display unit provided in the display unit 97 or a touch panel type display unit connected to the communication terminal 3 instead of a physical button.
- the voice input unit provided in the operation unit 98 or the voice input device connected to the communication terminal 3 may be instructed to transmit the voice message by voice input to the effect that the rescue message is to be transmitted. These are collectively referred to as “input means”.
- the control unit 99 determines to transmit data when the rescue message service start signal is received and it is determined that the rescue message transmission button is pressed (step S103; Yes).
- the control unit 99 generates a short message such as personal identification information (ID information) stored in the storage unit 96 and safety information including the location information acquired by the information acquisition unit 8, and the generated short message is stored as data.
- the data is supplied to the data processing unit 22 via the input terminal 23.
- the transmission data processing unit 22 attaches synchronization data or the like to the supplied short message, further attaches an error correction code, and outputs it to the transmission unit 7.
- step S103 the control unit 99 may determine to transmit data in response to receiving the rescue message service start signal without determining whether or not the rescue message button transmission button has been pressed.
- the communication terminal 3 may not be equipped with the rescue message button transmission button itself.
- the random selection unit 10 randomly selects one of the L spreading code channels (step S109). This can be said to be a spreading code channel selection step for randomly selecting a spreading code channel for CDMA spreading transmission data.
- the random selection unit 10 randomly selects one of the M time slot channels (step S110). This can be said to be a time slot channel selection step of randomly selecting a time slot channel for transmitting CDMA spread transmission data.
- the random selection unit 10 randomly selects one of the N frequency channels (step S111). This can be said to be a frequency channel selection step of randomly selecting a frequency channel for transmitting CDMA spread transmission data.
- the transmission unit 7 converts the transmission data supplied from the transmission data processing unit 22 as a CDMA / FDMA / TDMA signal through the satellite communication antenna 3s according to the combination of the access methods selected by the random selection unit 10 via the satellite 1 (Step S114).
- This is CDMA spread by the spreading code channel selected in the spreading code channel selection step at the frequency corresponding to the time slot channel selected in the time slot channel selection step and the frequency channel selected in the frequency channel selection step.
- This is a transmission step for transmitting the transmitted data.
- this transmission step is triggered by the communication terminal 3 receiving the forward link signal transmitted from the base station 2 via the satellite 1, and the transmission data as a return link signal. It can be said that it is processing to transmit to the base station 2.
- steps S109 to S111 and S114 are processes in which the random selection unit 10 and the transmission unit 7 transmit the short message processed by the transmission data processing unit 22 in cooperation with each other.
- the processing in step S114 also includes a synchronization step for transmitting the transmission data spread by CDMA by the transmission timing generation unit 32 in synchronization with the plurality of communication terminals 3.
- Step S109 is a CDMA spreading step (CDMA spreading unit 11) that CDMA spreads transmission data using the spreading code channel randomly selected in the spreading code channel selection step.
- Step S110 is a delay step (TDMA processing unit 12) that delays transmission data that is CDMA spread by the CDMA spreading step in the time slot channel randomly selected by the time slot channel selecting step.
- Step S111 is a frequency conversion step (FDMA processing unit 13) for frequency-converting the transmission data delayed in the delay step to the frequency corresponding to the frequency channel randomly selected in the frequency channel selection step.
- Step S114 is a transmission step (radio transmission unit 34) that transmits transmission data that is CDMA spread by the CDMA spreading step, delayed by the delay step, and frequency-converted by the frequency conversion step.
- FIG. 5 is a flowchart showing preprocessing of transmission processing of the communication terminal 3 according to the first embodiment.
- Step S201 corresponds to step S109 shown in FIG. 4 and is a spreading code channel selection step in which the random selection unit 10 randomly selects a spreading code channel for CDMA spreading transmission data.
- Step S202 corresponds to step S110 shown in FIG. 4, and is a time slot channel selection step in which the random selection unit 10 randomly selects a time slot channel for transmitting transmission data.
- Step S203 corresponds to step S111 shown in FIG. 4, and is a frequency channel selection step in which the random selection unit 10 randomly selects a frequency channel for transmitting transmission data.
- the order of the processing steps of the spreading code channel selection step (step S201), the time slot channel selection step (step S202), and the frequency channel selection step (step S203) is not limited.
- Step S205 is a process in which the random selection unit 10 determines a combination of access methods for one selected spread code channel, one time slot channel, and one frequency channel.
- the selected spread code channel is notified to the spread code generation unit 9
- the selected time slot channel is notified to the TDMA processing unit 12
- the selected frequency channel is notified to the FDMA processing unit 13. .
- the CDMA spreading unit 11 executes a CDMA spreading step for CDMA spreading the transmission data using the selected spreading code channel.
- the TDMA processing unit 12 executes a delay step for delaying the transmission data so that the CDMA spread transmission data is transmitted in the selected time slot channel.
- the wireless transmission unit 34 performs the delay step. A transmission step of transmitting transmission data that is delayed and frequency-converted by the frequency conversion step is executed.
- step S201 the random selection unit 10 randomly selects one of the spreading code channels. This corresponds to selecting one randomly from the L (plural) spread codes that can be generated by the spread code generation unit 9.
- the spreading code for example, an orthogonal Gold code is conceivable, and the number L of orthogonal codes that can be selected is 1024.
- the spreading code generated by the spreading code generator 9 is synchronized with the GPS time signal at the chip level, and is controlled so that the spreading codes transmitted from the respective communication terminals 3 are orthogonal to each other on the satellite transponder.
- the spreading code is not particularly limited to an orthogonal code, and may be a non-orthogonal code such as a Gold code or an M sequence.
- the orthogonal code is used, the mutual interference between the codes is almost eliminated, but when the non-orthogonal code is used, the mutual interference between the codes is increased.
- one frequency channel is selected at random from a plurality (M) of frequency channels.
- M the information transmission rate of transmission data transmitted by the communication terminal 3 using the return link communication line 18
- error correction coding with a coding rate of 1/2 is performed and spreading is performed 1024 times
- the chip rate Is 50 bps ⁇ 2 ⁇ 1024 102.4 kcps. Therefore, the required bandwidth of the BPSK modulated wave after CDMA spreading is about 200 kHz. That is, since this is the bandwidth of one frequency channel, for example, if the total frequency band that can be used is about 5 MHz, the number of frequency channels that can be selected is 25.
- the random selection unit 10 randomly selects one time slot from a plurality (N) of time slots.
- the total number of channels is L ⁇ N ⁇ M. Therefore, even if a large number of communication terminals 3 transmit transmission data (short messages) almost simultaneously, the probability of packet collision is small. Therefore, a communication system with high throughput and less retransmission processing can be obtained.
- the random selection unit 10 includes a combination selection unit 35 and a combination setting unit (table storage unit) 36.
- the random selection unit 10 individually selects a spread code channel, a time slot channel, and a frequency channel from the set ones, but in the communication terminal 3 shown in FIG. 6,
- the combination selection unit 35 randomly selects a combination of access methods.
- the combination setting unit 36 performs processing for transmitting table information (combination information) to the combination selection unit 35.
- the communication method according to Embodiment 1 has the spreading code channel selection step, the frequency channel selection step, and the time slot channel selection.
- the steps are preset and randomly selected from a table comprising combinations of spreading code channels and frequency channels and time slot channels.
- the communication terminal 3 shown in FIG. 6 needs to receive the forward link signal (rescue message service start signal), and the random selection unit 10 needs to select “spreading code channel”, “frequency channel”, and “time slot channel”.
- the combination selection unit 35 randomly selects one of the selection numbers set (stored) in the combination setting unit (table storage unit) 36, resulting in a “spread code channel”. ",” Frequency channel ", and” time slot channel "are selected at random.
- the communication terminal 3A shown in FIG. 1 selects the selection number 004
- the communication terminal 3B selects the selection number 001
- the communication terminal 3C selects the selection number 002
- the “spread code channel”, “frequency channel” ”,“ Time slot channel ” it is possible to select a combination of access methods in which all three items do not match among a plurality of communication terminals 3.
- the communication terminal 3 shown in FIG. 6 simultaneously executes the three processing steps of steps S109, S110, and S111 shown in FIG. That is, three processing steps of steps S201, S202, and S203 shown in FIG. 5 are executed simultaneously.
- the tables set (stored) in the combination setting unit (table storage unit) 36 may be held by the plurality of communication terminals 3 or may be different for each communication terminal 3.
- a table is prepared so that a time slot channel can be randomly selected from relatively early ones. Also good. This is the same even when the table is not used. That is, when the random selection unit 10 shown in FIG. 2 selects a time slot channel, it may be selected at a relatively early rate. Conversely, a table may be prepared so that the time slot channels can be randomly selected from relatively slow ones. This is the same even when the table is not used. That is, when the random selection unit 10 shown in FIG. 2 selects the time slot channel, it may be selected randomly from the relatively slow ones.
- FIGS. 7B and 7C are examples in the case where it is desired to provide a difference in communication start time for each communication terminal 3.
- the communication terminal 3 that uses this table inevitably compares. You can communicate quickly.
- the communication terminal 3 using this table inevitably In addition, communication can be performed relatively slowly.
- two time slot channels are selected. This is an example.
- random selection unit 10 sets the time slot for transmitting transmission data relatively earlier.
- the probability of selecting from the time slot channel can be increased.
- the probability that the random selection unit 10 can select a time slot for transmitting transmission data from a relatively slow time slot channel is increased as compared with the case where the communication is not performed. it can.
- the transmission unit 7 transmits data compared to the case where the random selection unit 10 does not.
- the time slot for transmitting is randomly selected from the relatively early time slot channels within the selectable range.
- the random selection unit 10 is a communication terminal 3 that wants to communicate relatively slowly, the time slot that is the basis of the time for which the transmission unit 7 delays the transmission data compared to the case where the random selection unit 10 is not, It can be said that the time slot channels within the selectable range are selected at random from the relatively slow ones.
- the combination setting unit 36 may supply information (combination information) in the table shown in FIG. 7A to the combination selection unit 35.
- the combination setting unit 36 of the communication terminal 3 supplies information (combination information) of the table shown in FIG. 7B to the combination selection unit 35. do it.
- the combination setting unit 36 of the communication terminal 3 supplies the information (combination information) of the table shown in FIG. 7C to the combination selection unit 35. do it.
- the information in the table shown in FIG. 7C is sent to the communication terminals 3 other than the communication terminal 3 (including a plurality of communication terminals 3).
- the information may be supplied to the combination selection unit 35, or information on the table shown in FIG. 7A that is normally used may be supplied to the combination selection unit 35.
- the information in the table shown in FIG. 7B is sent to the communication terminals 3 other than the communication terminal 3 (including a case where there are a plurality of communication terminals 3).
- the information may be supplied to the combination selection unit 35, or information on the table shown in FIG. 7A that is normally used may be supplied to the combination selection unit 35.
- FIG. A second embodiment of the present invention will be described with reference to FIGS.
- the second embodiment is an example of a communication system in which a difference is made in the time of communication for each communication terminal 3 actively (as a whole communication system).
- the same parts as those in the first embodiment are denoted by the same reference numerals.
- the communication terminal 3 further includes a position information acquisition unit 37 and a determination processing unit 38.
- the position information acquisition unit 37 acquires the position information of the own terminal (own terminal position data) from the information acquisition unit 8 and supplies it to the random selection unit 10.
- the position information acquisition unit 37 is connected to the information acquisition unit 8 (GPS signal processing unit 29). Specifically, the position information acquisition unit 37 acquires the GPS position information processed by the GPS signal processing unit 29.
- the determination processing unit 38 determines whether or not the position of the own terminal is within a predetermined area from the position information of the own terminal acquired by the position information acquiring unit 37, and combines the determination result with a combination setting unit (table Notification to the storage unit) 36. That is, the random selection unit 10 determines the position of the communication terminal 3 from position information acquired from the outside (position information acquired from GPS information).
- the random selection unit 10 includes a combination selection unit 35, a combination setting unit (table storage unit) 36, and a determination processing unit 38.
- the position information acquisition unit 37 may be incorporated in the random selection unit 10. Note that the position information acquisition unit 37 may acquire the position information of the terminal itself by a method other than receiving the GPS signal 19 from the GPS satellite 4. For example, position information may be acquired from an external device connected to the communication terminal 3, or position information input from the operation unit 98 of the communication terminal 3 may be acquired.
- the position information acquisition unit 37 acquires GPS position information from the GPS signal processing unit 29, analyzes the position of the own terminal, and supplies the position information of the own terminal to the determination processing unit 38. .
- the determination processing unit 38 stores area information (range information) indicating a predetermined area in the internal memory. Based on the location information of the own terminal acquired from the location information acquisition unit 37 and the stored region information, the determination processing unit 38 is within the predetermined region or outside the predetermined region. Local terminal internal / external information indicating whether or not there is generated is supplied to the combination setting unit 36.
- the combination setting unit 36 may select a relatively early transmission slot when the local area inside / outside information supplied from the determination processing unit 38 indicates that the position of the local terminal is within a predetermined area.
- Information on the available table (combination information) is transmitted to the combination selection unit 35.
- table information is, for example, the table shown in FIG. 7B.
- the combination setting unit 36 stores information on a table in which a relatively slow time slot can be selected, It transmits to the combination selection part 35.
- table information is, for example, the table shown in FIG. 7C.
- the combination setting unit 36 may transmit information of a table that is normally used to the combination selection unit 35 when the position of the terminal is outside a predetermined area.
- the table information normally used is, for example, the table shown in FIG. 7A.
- the area information indicating the predetermined area stored in advance by the determination processing unit 38 is when the communication terminal 3 exists outside the predetermined area when the communication terminal 3 exists within the predetermined area. It is information indicating an area where there is a high necessity for early communication.
- the communication terminal 3 in which the determination processing unit 38 previously holds area information indicating a predetermined area is described.
- the area information is externally transmitted. The communication terminal 3 to be acquired will be described.
- the combination setting unit 36 that has acquired the own terminal area internal / external information from the determination processing unit 38 supplies the table selection information (combination information) to the combination selection unit 35 in accordance with the internal terminal area internal / external information. .
- the combination selection unit 35 randomly selects one of the combinations of the spread code channel, the frequency channel, and the time slot channel (selection number when the table shown in FIG. 7 is used) from the acquired table information. Then, the combination selection unit 35 transmits the selected spreading code channel to the spreading code generation unit 9, transmits the selected time slot channel to the TDMA processing unit 12, and transmits the selected frequency channel to the FDMA processing unit 13.
- FIG. 9 is a flowchart showing a transmission process of the communication terminal 3 according to the second embodiment.
- This flowchart represents a communication method executed by the communication terminal 3 that transmits transmission data that has been CDMA-spread to the base station 2 via the satellite 1.
- Steps S101, S102, S103, S109 to S111, and S114 are the same as those shown in FIG.
- step S103 After the process of step S103 (when step S103 is omitted, after the process of step S102), the position information acquisition unit 37 executes a communication terminal position acquisition step of acquiring the location of the communication terminal 3. Subsequently, the determination processing unit 38 determines that the own terminal 3 is in a predetermined area based on the own terminal position information from the position information acquiring unit 37 and the area information previously held by the combination setting unit 36. It is determined whether or not it is located (step S106). When the determination processing unit 38 determines that the position of the own terminal is within a predetermined region (step S106; Yes), the combination setting unit 36 selects a relatively fast time slot channel. (Step S108A). For example, the determination processing unit 38 controls the combination setting unit 36 to supply the table illustrated in FIG.
- step S106 when it is determined that the position of the terminal is outside the predetermined region (step S106; No), the combination setting unit 36 has a probability that a relatively slow one is selected in the time slot channel selection. Is set to increase (step S108B).
- the determination processing unit 38 controls the combination setting unit 36 to supply the table shown in FIG. 7B to the combination selection unit 35 in step 108A, and the combination setting unit 36 shows the table shown in FIG. 7A or C in step 108B. Control is performed so that the table is supplied to the combination selector 35.
- the determination processing unit 38 controls the combination setting unit 36 to supply the table shown in FIG. 7A to the combination selection unit 35 in step S108A, and the combination setting unit 36 uses the table shown in FIG. 7C in step 108B. Control is performed so that the combination selection unit 35 is supplied.
- step S109 random selection of the spreading code channel is performed.
- step S110 the random selection unit 10 randomly selects one of the time slot channels.
- the time slot channel selection step in step S110 increases the probability that a relatively early time slot channel can be selected when the location of the communication terminal 3 is within a predetermined area, as compared with the case where the communication terminal 3 is not located. When the location of the terminal 3 is outside the predetermined area, it is a process for increasing the probability that a relatively slow time slot channel can be selected as compared with the case where the terminal 3 is not.
- the time slot channel selection step of step S110 is performed by comparing the time slot channel within the selectable range when the location of the communication terminal 3 is within a predetermined area, as compared with the case where the communication terminal 3 is not. If the location of the communication terminal 3 is outside the predetermined area, the time slot channel within the selectable range is relatively late compared to the case where the communication terminal 3 is outside the predetermined area. This is a process of selecting at random.
- step S111 one of the frequency channels is selected, and in step S112, the random selection unit 10 determines the selected spreading code channel, time slot channel, and frequency channel as one of the combinations of access methods.
- step S114 is performed, and the time slot channel selected in the time slot channel selection step and the frequency corresponding to the frequency channel selected in the frequency channel selection step are selected in the spreading code channel selection step. Transmit transmission data that is CDMA-spread on the spreading code channel.
- steps S109 to S111 are executed simultaneously when the combination selection unit 35 selects one combination.
- Embodiment 3 FIG. Next, Embodiment 3 of the present invention will be described with reference to FIGS.
- the determination processing unit 38 of the communication terminal 3 holds region information indicating a predetermined region in advance.
- the third embodiment a description will be given of a communication terminal 3 in which the determination processing unit 38 acquires area information from the outside, particularly, from the base station 2.
- the same reference numerals are given to the same parts as in the first and second embodiments.
- the communication terminal 3 which concerns on Embodiment 3 judges the position of an own terminal from the positional information which the random selection part 10 acquired from GPS information similarly to Embodiment 2.
- the communication terminal 3 includes an information acquisition unit 8 that acquires GPS information from the satellite 1 or the GPS satellite 4, and the information acquisition unit 8 acquires position information from the GPS information.
- the communication terminal 3 includes a receiving unit 6 that receives a forward link signal transmitted from the base station 2 and a transmitting unit 7 that transmits a return link signal.
- the communication terminal 3 further includes a broadcast information acquisition unit 39.
- the broadcast information acquisition unit 39 acquires region information indicating a predetermined region transmitted from the base station 2 separated from the reception data by the TDM separation unit 27 and supplies the region information to the determination processing unit 38.
- the area information may be referred to as “broadcast information”.
- the basic configuration of base station 2 according to Embodiment 3 is the same as base station 2 according to other embodiments.
- the base station 2 includes a base station transmission unit 2t, a base station reception unit 2r, a ground interface unit 41, a data generation unit 42, a control information transmission unit 44, a data processing unit 53, and a duplexer 48.
- the base station transmission unit 2t transmits a forward link signal to the plurality of communication terminals 3 that is a trigger for the plurality of communication terminals 3 to transmit a return link signal to the base station 2.
- the base station transmission unit 2t includes a TDM multiplexing unit 43, an error correction coding unit 45, a QPSK modulation unit 46, and a radio transmission unit (base station side transmission unit) 47.
- the TDM multiplexing unit 43 TDM multiplexes the transmission data (such as region information) acquired from the data generation unit 42 and the control data (such as satellite orbit information) acquired from the control information transmitting unit 44.
- the error correction encoding unit 45 performs error correction encoding on the transmission data TDM multiplexed by the TDM multiplexing unit 43.
- the QPSK modulation unit 46 performs QPSK modulation on the transmission data subjected to the error correction coding after the error correction coding of the transmission data by the error correction coding unit 45.
- the wireless transmission unit 47 frequency-converts the transmission data QPSK modulated by the QPSK modulation unit 46 to an RF frequency, and then amplifies the power.
- the base station receiver 2r generates a plurality of return link signals generated from time information obtained from the satellite 1 or GPS information and CDMA spread by a spread code generated at a spread code start timing synchronized between a plurality of communication terminals 3. From the communication terminal 3.
- the base station receiving unit 2r includes a radio receiving unit (base station side receiving unit) 49, a CDMA despreading unit 50, a BPSK demodulating unit 51, and an error correction decoding unit 52.
- the radio reception unit 49 amplifies without increasing the noise included in the return link signal acquired from the duplexer 48, and supplies a so-called low noise amplified signal to the CDMA despreading unit 50.
- the CDMA despreading unit 50 converts the low noise amplified received signal supplied from the wireless receiving unit 49 into an IF frequency signal, acquires a chip clock and a spreading code start timing from the received CDMA signal, Perform despreading.
- the BPSK demodulator 51 demodulates the signal despread by the CDMA despreader 51 of the base station 2.
- the error correction decoding unit 52 performs error correction decoding on the signal BPSK demodulated by the BPSK demodulation unit 51.
- the duplexer 48 electrically separates the reception path and the transmission path of the satellite communication antenna (base station side satellite communication antenna) 2s sharing the transmission of the forward link signal and the reception of the return link signal.
- the ground interface unit 41 receives data for transmission to the communication terminal 3 transmitted from the service center 16 via the ground network 14. Similarly, the ground interface unit 41 receives data (mainly satellite orbit information) transmitted from the satellite tracking control center 15 via the ground network 14.
- the data generation unit 42 receives data to be transmitted for each communication terminal 3 from the ground interface unit 41 and generates transmission data for each communication terminal 3.
- the control information transmission unit 44 transmits control data (such as satellite orbit information) to the TDM multiplexing unit 43.
- the data processing unit 53 forms data to be output to the service center 16 from the signal subjected to error correction decoding by the error correction decoding unit 52, and transmits the data to the ground interface unit 41. Data processed by the data processing unit 53 is transmitted from the ground interface unit 41 to the service center 16 via the ground network 14.
- the area information unit 40 transmits information serving as a source of area information indicating a predetermined area that the base station 2 transmits to the communication terminal 3 to the service center 16.
- the service center 16 transmits the area information acquired from the area information unit 40 to the base station 2 via the ground network 14.
- the region information generation unit (region information conversion unit) 16e included in the center 16 may convert the information acquired from the region information unit 40 into region information that can be used by the communication terminal 3, and then transmit the information to the base station 2.
- the base station 2 may include the area information generation unit 16e.
- FIGS. 12 to 15 are diagrams showing a predetermined area derived from the area information distributed from the base station 2 to the communication terminal 3 through the forward link communication line 17.
- the black dots “ ⁇ ” shown in these figures are points determined by the latitude and longitude coordinates acquired from the area information.
- a hatched area shown in the figure is a predetermined area formed from the coordinates of latitude and longitude acquired from the area information.
- FIG. 12A is a diagram illustrating a circular predetermined region E formed from the coordinates of the acquired center (center of gravity).
- FIG. 12B is a diagram illustrating a rectangular predetermined region E formed from the coordinates of the acquired center (center of gravity).
- FIG. 12C is a diagram illustrating a predetermined region E configured by a plurality of circles formed from the coordinates of a plurality of acquired centers (centers of gravity).
- FIG. 13A is a diagram showing a circular predetermined region E formed from the coordinates of the acquired vertices.
- FIG. 13B is a diagram illustrating a predetermined area E having a rectangular shape formed from the coordinates of the acquired vertexes.
- FIG. 13C is a diagram illustrating a circular predetermined region E formed from the coordinates of three acquired points on the circumference.
- FIG. 13D shows a circle formed from the coordinates of three points on the acquired circle, and a circular region included in the circle (this circular region is also formed from information on three points on the given circle. It is a figure which shows the predetermined area
- 14A and 14B are diagrams showing a predetermined area E formed from the coordinate information of a plurality of given points.
- FIG. 15A shows a circular predetermined area E1 formed from the coordinates of three points on the acquired circumference and a circle including the predetermined area E1 (this circular is also the acquired circumference). It is a figure which shows predetermined area
- FIG. 15B shows a predetermined region E2 formed from a plurality of acquired coordinates and a quadrangle included in the predetermined region E2 (this quadrangle is formed from the coordinates of acquired vertices). It is a figure which shows the predetermined area
- 15C shows a predetermined region E2 composed of a plurality of circles formed from the coordinates of the acquired plurality of centers (center of gravity), and a predetermined circle of circles formed from the coordinates of the acquired centers (center of gravity). It is a figure which shows the area
- the information supplied from the region information unit 40 is converted into transmission data including region information indicating a predetermined region based on a predetermined condition by the data generation unit 42, and the base station Signal processing is performed by the transmission unit 2t and transmitted to the communication terminal 3 as a forward link signal.
- the communication terminal 3 that has received this forward link signal acquires information on a predetermined area from the received forward link signal.
- the random selection unit 10 of the communication terminal 3 When the position of the communication terminal 3 is within a predetermined area, the random selection unit 10 of the communication terminal 3 relatively sets the time slot in which the transmission unit 7 transmits the transmission data as compared to the case where the position is not. Increase the probability of selecting from an early time slot channel. Note that when the position of the communication terminal 3 is outside the predetermined area, the random selection unit 10 of the communication terminal 3 sets the time slot in which the transmission unit 7 transmits the transmission data relative to the case where the position is not the case. Therefore, the probability of selecting from an early time slot channel may be lowered.
- a return link signal is transmitted to the base station 2 using a combination of access methods (spread code channel, time slot channel, frequency channel) selected by the random selection unit 10 of the communication terminal 3.
- the return link signal is received via the satellite communication antenna 2s of the base station 2, processed by the base station receiving unit 2r and the data processing unit 53, and sent from the ground interface unit 41 to the service center 16 via the ground network 14. Sent. Therefore, the service center 16 can acquire information from the plurality of communication terminals 3.
- the service center 16 can acquire safety information including personal identification information (ID information) and position information of the communication terminal 3 or its user.
- the area information unit 40 transmits information on the affected area to the service center 16 as area information.
- the information on the disaster area is not usable as area information indicating a predetermined area when the communication terminal 3 receives the information, for example, when the area name is simply the name of the disaster area, FIG.
- the area information generating unit (area information converting unit) 16e included in the service center 16 converts the information from the area information unit 40 and then transmits the information to the base station 2.
- the information converted by the region information generation unit (region information conversion unit) 16e is referred to as information on a predetermined region set based on a predetermined condition.
- the predetermined condition is, for example, “If the information transmitted from the area information unit 40 to the service center 16 (area information generation unit 16 e) is a place name, a government office or landmark existing in the area to which the place name belongs, etc. ”Is converted into position information for indicating one point represented by coordinates of latitude and longitude.”, “From the area information section 40 to the service center 16 (area information generation section 16e). If the information to be sent is a place name, the area containing the address of a prominent building such as a government office or landmark that exists in the area to which the place name belongs is formed with a plurality of points represented by latitude and longitude coordinates. “Convert to location information”.
- the “location information to indicate with one point” converted to the location information to indicate the address and position of a prominent building with a single point represented by the latitude and longitude coordinates is the data generation Generated by the unit 42 as transmission data including “position information for indicating by one point”.
- the transmission data generated by the data generation unit 42 is transmitted to each communication terminal 3 as a forward link signal by the base station transmission unit 2t.
- the communication terminal 3 that has received the forward link signal separates the position information by the TDM separation unit 27 and supplies the position information to the broadcast information acquisition unit 39.
- region set based on the predetermined condition from the positional information on one point is calculated.
- the communication terminal 3 determines a predetermined area E having a single point as the center of gravity (center) of a rectangle (may be a predetermined area E having one point as the center of gravity (center) of a polygon).
- the processing unit 38 or the broadcast information acquisition unit 39 calculates. Note that information on the radius of the region E and the distance or area of the diagonal line determined in advance may be determined in advance and stored in the determination processing unit 38 or the broadcast information acquisition unit 39 of the communication terminal 3.
- information on the radius or diagonal distance or area of the predetermined region E is set by the region information unit 40 or the region information generation unit (region information conversion unit) 16e, and is transmitted together with the position information by a forward link signal. Also good.
- the “location information for indicating with a plurality of points” converted to the location information for indicating the area indicated by the address of a prominent building with a plurality of points represented by coordinates by latitude and longitude is the ground interface.
- the data generation unit 42 generates the transmission data including “position information for indicating with a plurality of points” via the unit 41, and the base station transmission unit 2t forwards the position information of the plurality of points as the position information. It transmits to each communication terminal 3 as a link signal. Then, the communication terminal 3 that has received the forward link signal separates the position information by the TDM separation unit 27 and supplies it to the broadcast information acquisition unit 39. And the predetermined area
- a predetermined region set based on a predetermined condition is calculated from position information of a plurality of points, a plurality of circles having one point as the center (center of gravity) of a circle as shown in FIG.
- a predetermined area E, a plurality of points (three points) as shown in FIG. 13A are triangular vertices, and a plurality of points (four points) as shown in FIG.
- a predetermined region E (which may be a polygonal predetermined region E having a plurality of acquired points as vertices), and a plurality of points (three points) as shown in FIG.
- a predetermined region E a predetermined region E surrounded by a boundary line connecting a plurality of points as shown in FIGS. Is calculated.
- information such as the radius and area of the predetermined region E may be determined in advance and stored in the determination processing unit 38 or the broadcast information acquisition unit 39 of the communication terminal 3.
- information such as a predetermined radius or area of the region E may be set by the region information unit 40 or the region information generation unit (region information conversion unit) 16e and transmitted together with the position information by a forward link signal. .
- predetermined area E From the predetermined area determined in this way (predetermined area E), the determination processing unit 38, in the communication terminal 3 according to the third embodiment, as well as the second embodiment, Local terminal internal / external information indicating whether the position is within a predetermined region (predetermined region E) or outside the predetermined region is generated and supplied to the combination setting unit 36.
- the combination setting unit 36 when the information on the inside / outside of the own terminal area acquired from the determination processing unit 38 indicates that the position of the own terminal is within a predetermined area (predetermined area E). However, the combination setting unit 36 uses table information that increases the possibility of selecting a time slot for transmitting transmission data from a relatively earlier time slot channel than when the position of the terminal is outside the predetermined region. Is transmitted to the combination selection unit 35.
- the combination selection unit 35 is within the area where the position of the own terminal is predetermined.
- the combination setting unit 36 transmits information of a table that can select a time slot for transmitting transmission data from a relatively late time slot channel to the combination selection unit 35.
- the communication terminal 3 according to the third embodiment since the communication terminal 3 according to the third embodiment executes the above-described process, the communication terminal 3 according to the third embodiment has a region in which the position of the own terminal is predetermined (predetermined region E ) And when not, the selection range of the time slot for transmitting the return link signal can be changed among the plurality of communication terminals 3.
- the predetermined area E is “an area set based on a predetermined condition from position information transmitted by a forward link signal and indicated by one position information indicated by the position information” or “forward link”.
- the position information is transmitted by a signal, and is an area set based on a predetermined condition from two or more points of position information indicated by the position information.
- the terminal 3, the base station 2, and the communication system 100 have been described. Even if the position of the communication terminal 3 is within a predetermined area, the predetermined area E is further determined as the predetermined area E1.
- the selectable range of the time slot may be changed by dividing it into the area E2. Thereby, for example, it becomes possible to set the selection range of the time slot channel more finely according to the degree of damage in the affected area.
- the determination processing unit 38 generates own terminal area inside / outside information indicating information indicating whether the position of the own terminal is in the predetermined area E1 or the predetermined area E2, and this own terminal
- the inside / outside area information is supplied to the combination setting unit 36.
- the combination setting unit 36 when the local area inside / outside information acquired from the determination processing unit 38 indicates that the position of the local terminal is within the predetermined area E1, is greater than the case where the local terminal area is within the predetermined area E2.
- the combination setting unit 36 transmits information of a table that increases the possibility of selecting a time slot for transmitting transmission data from a relatively early time slot channel to the combination selection unit 35.
- the predetermined area E1 and the predetermined area E2 are obtained by dividing the predetermined area E, the predetermined area E1 and the predetermined area E2 are related to the random selection of the time slot channel. And the relationship other than the predetermined region E1 and the predetermined region E2 are the same as the relationship other than the predetermined region E and the predetermined region E.
- FIG. 15A shows a circular predetermined region E1 in which a plurality of points (three points) are located on the circumference, and a circular shape including this circular predetermined region 1 (this circular shape is also on the circumference). It is an example showing a predetermined region E2 excluding a predetermined region E1 from a region of a plurality of points (three points) positioned).
- FIG. 15B shows a predetermined range of a rectangle (this rectangle is also formed from vertices (four points)) included in the predetermined region from a predetermined region formed by a plurality of points. This is an example showing a predetermined area E2 excluding the area E1 and a quadrangular predetermined area E1 included in the predetermined area 2.
- FIG. 15C shows a predetermined area E1 of a plurality of predetermined circles having a single point as the center (center of gravity) of a circle, and a predetermined circle E1 with a predetermined circle E1. This is an example showing the region E2.
- Information such as the radius and area of the predetermined region E1 and the predetermined region E2 may be determined in advance and stored in the determination processing unit 38 or the broadcast information acquisition unit 39 of the communication terminal 3.
- the information such as the radius and area of the predetermined region E1 and the predetermined region E2 is set by the region information unit 40 or the region information generation unit (region information conversion unit) 16e, and the position is determined by the forward link signal. It may be transmitted together with the information.
- FIGS. 13C, 13D and 15A it has been described that if three points (coordinates based on latitude and longitude) can be acquired, a circular predetermined region can be specified. That is, three points (for example, (X1, Y1), (X2, Y2), (X3, Y3)) are respectively added to x and y in one of the equations of the circles shown in the following equations 1 and 2. This is because the coordinates (a, b) and radius r of the center of the circle can be easily obtained by solving the simultaneous equations derived by substituting each.
- the communication terminal 3 receives the forward link signal transmitted from the base station 2 according to the third embodiment, and is one point of position information indicated by the area information acquired from the forward link signal.
- the area set based on a predetermined condition from “A” is defined as “predetermined area (predetermined area E)”.
- the communication terminal 3 which concerns on Embodiment 3 receives the forward link signal transmitted from the base station 2 which concerns on Embodiment 3, and from the positional information of two or more points which the area
- the area to be designated is, for example, a position range where a disaster is actually expected or an area where there are many communication terminals 3 of users who want to send a short message due to the disaster.
- FIG. A fourth embodiment of the present invention will be described with reference to FIGS.
- the combination selection unit 35 that randomly selects a combination of access schemes has the “spread code channel”, “frequency channel”, “time slot” stored in the combination setting unit (table storage unit) 36.
- the combination setting unit table storage unit
- the time slot setting unit (second table storage unit) 54 sets (stores) a table that allows the combination selection unit 35 to randomly select “time slot channel”. Therefore, the combination setting unit (table storage unit) 36 according to the fourth embodiment sets (stores) a table that can randomly select “spread code channel” and “frequency channel”.
- the local terminal location data (local location information) supplied from the location information acquisition unit 37 is supplied to the time slot setting unit (second table storage unit) 54 of the random selection unit 10.
- the communication terminal 3 according to the fourth embodiment includes a time slot setting unit (second table storage unit) 54 in addition to the communication terminal 3 according to the second embodiment.
- the communication terminal 3 according to the fourth embodiment may be provided with a time slot setting unit (second table storage unit) 54 added to the communication terminal 3 according to the third embodiment. .
- FIGS. 18A and 19A are tables storing combinations of two channels of “spread code channel” and “frequency channel” stored in the combination setting unit (table storage unit) 36.
- the tables shown in FIGS. 18B and 19B are tables stored in the “time slot channel” stored in the time slot setting unit (second table storage unit) 54.
- FIG. 18C is a table in which only channel # 1 and channel # 2, which are relatively early time slot channels, are extracted from the “time slot channel” table shown in FIG. 18B (FIG. 19B) and stored.
- FIG. 18D is a table in which only channel # 3 and channel # 4, which are relatively slow time slot channels, are extracted from the “time slot channel” table shown in FIG. 18B (FIG. 19B) and stored.
- FIG. 18C is a table in which only channel # 1 and channel # 2, which are relatively early time slot channels, are extracted from the “time slot channel” table shown in FIG. 18B (FIG. 19B) and stored.
- FIG. 18D is a table in
- FIG. 19C is a table in which “time slot channel” numbers that can be selected from the elements of the “time slot channel” item in the table shown in FIG. 18C are extracted without duplication.
- FIG. 19D is a table in which “time slot channel” numbers that can be selected from the elements of the “time slot channel” item in the table shown in FIG. 18D are extracted without duplication.
- the number of selection numbers matches the number of time slot channels.
- the combination of the spreading code channel and the frequency channel is selected at random using the tables shown in FIGS.
- the position information acquisition unit 37 acquires GPS position information from the GPS signal processing unit 29 and outputs the position information of the terminal itself to the determination processing unit 38.
- the determination processing unit 38 generates information on the inside / outside of the own terminal area, which is information indicating whether the position of the own terminal is within a predetermined area or outside the area, and supplies the information to the time slot setting unit 54. .
- the combination selection unit 35 determines that the position of the own terminal is Table information (combination information) that increases the possibility of selecting a time slot for transmitting transmission data from a relatively earlier time slot channel than when it is outside the predetermined area is transmitted to the combination selection unit 35.
- Table information that can select a time slot from a relatively early time slot channel is, for example, the table shown in FIG. 18C.
- the time slot setting unit 54 combines the information of the normally used table when the information on the inside / outside area of the own terminal acquired from the determination processing unit 38 indicates that the position of the own terminal is outside the predetermined area. What is necessary is just to transmit to the selection part 35.
- the table information that is normally used is, for example, the table shown in FIG. 18B.
- the combination selection unit 35 is more than the case where the position of the own terminal is within the predetermined area.
- Information of a table that increases the probability of selecting a time slot for transmitting transmission data from a relatively slow time slot channel is transmitted to the combination selector 35.
- the table information for increasing the probability of selecting a time slot for transmitting communication data from a relatively slow time slot channel is, for example, the table shown in FIG. 19D.
- the combination setting unit 36 transmits information (combination information) of a table storing combinations of “spreading code channel” and “frequency channel” to the combination selection unit 35.
- the table information transmitted to the combination selection unit 35 is, for example, the table shown in FIG. 19A.
- the time slot setting unit 54 that has acquired the local area internal / external information from the determination processing unit 38 uses the table information (combination information) as described above to the combination selection unit 35 according to the local area internal / external information. Supply.
- the combination selection unit 35 randomly selects a time slot channel from the acquired table information. Then, the combination selection unit 35 transmits the selected time slot channel to the TDM processing unit 12.
- the combination selection unit 35 randomly selects a combination of the spread code channel and the frequency channel from the information in the table acquired from the combination setting unit 36 regardless of the contents of the local area internal / external information. Then, the combination selection unit 35 transmits the selected spreading code channel) to the spreading code generation unit 9, and transmits the selected frequency channel to the FDM processing unit 13.
- the area information indicating the predetermined area held in advance by the determination processing unit 38 is outside the predetermined area when the communication terminal 3 is within the predetermined area. Compared to the case, it is information indicating a region where there is a high necessity for early communication.
- the communication terminal 3 shown in FIG. 16 a case is described in which the combination setting unit 36 holds information on a predetermined area in advance. However, in the communication terminal 3 shown in FIG. The case where information is acquired from the outside is shown. Note that the cooperation of the broadcast information acquisition unit 39, the broadcast information acquisition unit 39, and the determination processing unit 38 illustrated in FIG. 17 is the same as the description in the third embodiment, and thus the description thereof is omitted.
- the table shown in FIG. 19 is a substitute for the table shown in FIG.
- the table shown in FIG. 19A held by the combination setting unit 36 is the same as FIG. 18A.
- the table shown in FIG. 19B held by the time slot setting unit 54 is the same as FIG. 18B.
- the combination selection unit 35 randomly selects from “NNN” combinations of selection numbers “001” to “NNN”.
- NNN a time slot that can be selected in order to increase the probability that a time slot can be selected from a relatively early time slot channel or a later time slot channel according to the contents of the local area internal / external information generated by the determination processing unit 38.
- the number of times there is no problem even if the limited time slots are registered in the table without duplication and the number of selection numbers is matched with the limited number of time slots.
- the tables shown in FIGS. 19C and 19D match the number of selectable time slot numbers with the number of selected numbers.
- the time slots that can be selected are “channel # 1” and “channel # 2”, the selection numbers are also “001” and “002”. However, it is not limited to this.
- a time slot setting unit (second table storage unit) is used as a configuration for changing the table to which the combination selection unit 35 selects a time slot channel according to the position of the communication terminal 3. 54 was newly provided.
- This makes it possible to set a “time slot channel” with a higher degree of freedom than creating three tables of “spreading code channel”, “frequency channel”, and “time slot channel” together in one table. .
- FIG. A fifth embodiment of the present invention will be described with reference to FIGS.
- the communication terminal 3 according to the fifth embodiment is different from the communication terminal 3 according to another embodiment in that the time slot channel is randomly selected under the control of the probability distribution characteristics. Therefore, even when the communication terminal 3 according to Embodiment 5 needs to change the time slot channel that can be selected in accordance with the position of the terminal itself, the random selection unit 10 uses, for example, a table as shown in FIG. There is no need to change the table to be held and referred to according to the position of the terminal itself.
- the selection of the spread code channel and the frequency channel the basic operation is the same between the communication terminal 3 according to the fifth embodiment and the communication terminal 3 according to the first to fourth embodiments. That is, the spread code channel and the frequency channel are randomly selected by the combination selection unit 35.
- the random selection unit 10 of the communication terminal 3 includes a combination selection unit 35, a combination setting unit (table storage unit) 36, a determination processing unit 38, a probability distribution storage unit 55, and a probability setting unit 56.
- the probability setting unit 56 transmits the probability distribution selection information to the probability distribution storage unit 55 based on the local area inside / outside information acquired from the determination processing unit 38.
- the probability distribution storage unit 55 supplies information on probability distribution characteristics as illustrated in FIG. 22 to the combination selection unit 35, for example.
- FIG. 20 corresponds to communication terminal 3 according to Embodiment 2, and only communication terminal 3 determines whether or not the position of its own terminal is within a predetermined area.
- the communication terminal 3 shown in FIG. 21 corresponds to the communication terminal 3 according to Embodiment 3, and the communication terminal 3 obtains information from the base station 2 as to whether or not the position of the own terminal is within a predetermined area.
- FIG. 22 is a characteristic diagram of the probability distribution for the time slot channel stored in the probability distribution storage unit 55.
- the characteristic of FIG. 22A is a distribution in which the probability is higher as the time slot channel is relatively faster
- the characteristic of FIG. 22B is a distribution with the same probability regardless of whether the time slot channel is late or not.
- the characteristic is a distribution in which the probability increases as the time slot channel is relatively slow.
- the slot selection method for starting transmission at a predetermined slot interval in synchronization with the transmission timing of transmission data in synchronization with the slot on the time axis as in the conventional random access method by the slot Aloha method is described in the present application. Is not applicable.
- a method of selecting different slots in a random access method based on CDMA / FDMA / TDMA that can support services in which the communication terminals 3 transmit rescue messages (short messages) all at once will be described.
- the slot for transmitting data is selected as follows.
- Each communication terminal 3 randomly selects one slot from a large number of slots from the time when the transmission request is generated until T time elapses.
- Each communication terminal 3 uses the absolute time acquired from the GPS time signal to synchronize the slot timing with the chip clock generated by the transmission timing generation unit 32 and the spread code start timing. The slots between are synchronized.
- the number of communication terminals 3 to be accessed is N, and one of the N communication terminals 3 is randomly assigned to one spreading code.
- the combination of the channel, the frequency channel, and the slot channel is selected, and the probability of successful message transmission Ps ”is obtained.
- the communication terminal 3 waits for a time considering the round-trip delay time (about 0.5 seconds) of the satellite line and the processing time of the base station 2.
- the round-trip delay time about 0.5 seconds
- the communication terminal 3 waits for a time considering the round-trip delay time (about 0.5 seconds) of the satellite line and the processing time of the base station 2.
- a short message is retransmitted in the latest slot when an ACK signal cannot be received from the base station 2 (that is, when a time-out occurs in the communication terminal 3).
- re-transmission is further considered until re-transmission.
- the probability that the message collides is expressed by the following Equation 5.
- the total number of communication terminals 3 that simultaneously access that is, the total number of traffic increases. That is, the total number of traffics is increased to N / (1-Pc) by the first collision in the transmission of the first message by the N communication terminals 3. In the case of retransmission, the total traffic number further increases to N / [(1-Pc) (1-Pc ⁇ 2)]. In the case of re-transmission, the total traffic number is considered to increase to N / [(1-Pc) (1-Pc ⁇ 2) (1-Pc ⁇ 3)]. Therefore, in the case of retransmission and re-transmission, the following equation 7 holds.
- Equation 7 the following Equation 8 is obtained.
- the random selection unit 10 of the communication terminal 3 randomly selects a combination of one spreading code channel, one frequency channel, and one time slot channel.
- a uniform random number Rnd between 0 and 1 is generated.
- Nc the total number of spreading code channels
- [Nc ⁇ Rnd + 1] is calculated, and the integer part is taken as one spreading code channel selected at random. The same applies to the frequency channel and the time slot channel.
- the probability setting unit 56 sets the relatively fast time slot channel selection probability when the position of the own terminal is within a predetermined region based on the own terminal region inside / outside information obtained from the determination processing unit 38. Probability distribution selection information indicating the probability distribution to be increased is transmitted to the combination selection unit 35 via the probability distribution storage unit 55.
- the combination selection unit 35 can use, for example, an inverse transformation method as a random number generation method for selecting a time slot channel.
- the inverse transformation method is a method for obtaining random numbers according to a desired probability distribution by further transforming the obtained random numbers (for example, the above-mentioned uniform random number Rnd) with a function, and is generally well known.
- a probability distribution when a variable whose probability of taking the value is determined by the result of the trial is a random variable, the correspondence between the random variable and the probability of taking the value is called a probability distribution.
- the probability is relatively the same in the first half slot channel and the probability in the remaining second slot channel. It may be a probability distribution that becomes zero. In such a case, the time slot channel is selected at random only from among the relatively early time slot channels in the first half.
- the table of FIG. 7A stores all combinations of access methods of spreading code channels, frequency channels, and time slot channels, and a selection number is assigned to each combination.
- the same spreading code channel and frequency channel as in FIG. 7A are stored, but only the relatively fast channel # 1 and channel # 2 are stored in the time slot channel. Slow channel # 3 and channel # 4 are not stored.
- the table of FIG. 7C stores the same spreading code channel and frequency channel as in FIG. 7A, but the time slot channel stores only the relatively slow channel # 3 and channel # 4 and the relatively fast channel. # 1 and channel # 2 are not stored in the table.
- the combination selection unit 35 refers to the table information (combination information) acquired from the table storage unit 36 and selects a selection number at random from the table information. Select a combination of methods at random. By selecting the selection number, each channel can be selected at random.
- the combination setting unit 36 uses preset table information (combination information) as shown in FIGS. 7B and 7C. To supply. That is, the random selection method of the combination of access methods using the above-described FIGS. 7B and 7C changes the information (combination information) of the table to be referenced, so that the combination selection unit 35 determines the relative speed of the time slot.
- the fifth embodiment is a setting method for increasing the selection probability of a relatively early time slot channel based on the local area internal / external information in the probability distribution storage unit 55 and the probability setting unit 56, or the probability distribution
- the difference is that it relates to a setting method for increasing the selection probability of a relatively slow time slot channel based on the information on the inside and outside of the terminal area in the storage unit 55 and the probability setting unit 56. Therefore, the time slot channel selection method is such that communication terminal 3 according to Embodiments 1 to 4 selects at random with reference to table information (combination information).
- the time slot channel selection method of the communication terminal 3 limits the range of time slots that can be selected based on the probability distribution characteristics, and selects at random within this limit range.
- the spreading code channel and frequency channel are selected at random in each of Embodiments 1 to 4 and Embodiment 5 with reference to table information (combination information).
- the table storage unit (combination setting unit) 36 uses the table information (combination information) shown in FIG. To supply. Based on the probability distribution characteristic information (shown in FIG. 22) sent from the probability distribution storage unit 55, the combination selection unit 35 randomly selects a time slot from the table information (combination information).
- the communication terminal 3 according to the fifth embodiment has the same function as the communication terminal 3 according to the first to fourth embodiments referring to the tables shown in FIGS. 7B and C when selecting the combination of access methods. Obtainable.
- communication terminal 3 according to Embodiment 5 has a higher degree of freedom in changing the range of randomly selected time slot channels than in other embodiments that change the tables of FIGS. 7A, 7B, and C. . This is because the slope of the straight line of the probability distribution shown in FIG. 22 can be easily changed by calculation. Therefore, in the fifth embodiment, unlike the combination setting unit 36 according to the first to fourth embodiments, it is not necessary to prepare a table other than the basic table, so that the memory of the communication terminal 3 can be greatly reduced. Connected. Of course, the communication terminal 3 according to the fifth embodiment can also be applied to the random selection of the time slot channel in the predetermined area E1 and the predetermined area E2 described in the third embodiment.
- the probability setting unit 56 selects a time slot from among the time slot channels within a selectable range when the own terminal is in a predetermined area.
- Probability distribution selection information for enabling random selection from relatively early ones is supplied to the probability distribution storage unit 55.
- the probability distribution storage unit 55 selects the characteristic probability distribution characteristic shown in FIG. 22A and supplies the information to the combination selection unit 35.
- probability distribution selection information for enabling the time slot to be selected at random from the relatively slow time slot channels within the selectable area Is supplied to the probability distribution storage unit 55.
- the probability distribution storage unit 55 selects the characteristic probability distribution characteristic of FIG.
- probability distribution selection information for allowing the time slot to be randomly selected from the time slot channels within the entire selectable range is stored in the probability distribution storage unit 55. You may supply. In this case, the probability distribution storage unit 55 selects the characteristic probability distribution characteristic of FIG. 22B and supplies it to the combination selection unit 35.
- the probability distribution storage unit 55 supplies probability distribution characteristic information to the combination selection unit 35 from the probability distribution selection information acquired from the probability setting unit 56. Therefore, the combination selection unit 35 can change the range for randomly selecting a channel (time slot channel) from the table shown in FIG. 7A based on the probability distribution characteristic information acquired from the probability setting unit 56.
- a channel time slot channel
- the communication terminal 3 as its own terminal exists in a predetermined area for example, in a disaster area
- a slot channel with a relatively early time slot is preferentially selected. It is apparent from the probability distribution characteristic shown in FIG. 25 that a short message can be transmitted.
- the function of the combination setting unit (table storage unit) 36 (including the function of the time slot setting unit (second table storage unit) 54) in other embodiments is the same as the probability distribution storage unit 55 in the fifth embodiment.
- the probability setting unit 56 and the combination setting unit (table storage unit) 36 (the stored table is only the one shown in FIG. 7A) can be interpreted as being highly functional.
- the communication terminal 3 includes a probability setting unit 56 and a probability distribution storage unit 55.
- the probability setting unit 56 transmits the probability distribution selection information to the probability distribution storage unit 55 based on the local area inside / outside information from the determination processing unit 38.
- the probability distribution storage unit 55 selects a probability distribution characteristic for the time slot channel and transmits the information.
- the probability setting unit 56 selects the characteristics shown in FIG. 22A when the own terminal is in a predetermined area, and cannot determine whether the own terminal is inside or outside the predetermined area. In such a case, the characteristic shown in FIG. 22B is selected. If the own terminal is not within the predetermined area, the characteristic shown in FIG. 22C is selected.
- the combination selection unit 35 selects a time slot channel based on the characteristics of the probability distribution from the probability distribution storage unit 55. Thereby, for example, when the own terminal is present in a predetermined area, it is possible to increase the selection probability of a relatively early time slot channel.
- the combination selection unit 35 selects a time slot based on the probability distribution characteristic using FIG. 7A as a basic table, the selection number assigned to each combination is selected, so that the spread code channel and the frequency channel are automatically selected. Is determined. That is, the combination selection unit 35 randomly selects one combination of the spread code channel, the frequency channel, and the time slot channel. Further, the combination selection unit 35 transmits the spreading code channel included in the selected selection number to the spreading code generation unit 9, transmits the frequency channel to the FDM processing unit 13, and transmits the time slot channel to the TDM processing unit 12. To do.
- the time slot is selected based on the probability distribution characteristics using FIG. 18B or FIG. 19B as the basic table, the spreading code channel and the frequency channel are separated from the time slot on the table. The channel and the frequency channel may be selected randomly from FIG. 18A or FIG. 19A.
- the communication terminal 3 according to Embodiment 5 also acquires information on a predetermined area from the received forward link signal, and the random selection unit 10 is predetermined by the own terminal. If it is within the specified region, the time slot for transmitting the transmission data is randomly selected from the relatively early time slots among the time slot channels within the selectable range, as compared with the case where it is not. On the other hand, the random selection unit 10 compares the time slot for transmitting the transmission data when the terminal is outside the predetermined area, among the time slot channels within the range in which the transmission data can be selected. Choose a relatively slow one.
- Embodiment 6 FIG. A sixth embodiment of the present invention will be described with reference to FIG. In Embodiments 1 to 5, it is assumed that the communication terminal 3 transmits a return link signal only once when there is no need for retransmission or re-transmission. A case will be described in which communication terminal 3 according to Embodiment 6 transmits a turn link signal a plurality of times from the beginning.
- the communication method according to the sixth embodiment will be described with reference to the flowcharts of FIGS. 23 and 24, and the description of the configuration of the communication terminal 3, the base station 2, and the communication system 100 according to the sixth embodiment will be omitted.
- the processing steps of steps S101, S102, S103, S109 to S112, and S114 in the flowcharts shown in FIGS. 4 and 9 have been described. As shown in FIG. In the communication method according to the sixth embodiment, processing steps of steps S105, S107, S108, and S113 are further added. In the flowchart shown in FIG. 23, the operation of the random selection unit 10 of the communication terminal 3 is basically the center.
- the determination processing unit 38 uses 1 as the initial value of the channel combination number value n (n is a positive integer) indicating the number of combinations of access methods of the spread code channel, time slot channel, and frequency channel. Is set (step S105). This is because the position of the terminal itself is outside the predetermined area, and the possibility of selection for successful early communication needs to be increased as compared with the case where the position of the terminal itself is within the predetermined area. Means no.
- the determination processing unit 38 uses the own terminal location information from the location information acquisition unit 37 and the information on the predetermined area that is held in advance, or the area information from the broadcast information acquisition unit 39, Is determined to be within a predetermined area (step S106).
- the number n of channel combinations is set to a value of 2 or more in order to increase the possibility of successful early communication (step S106).
- the random selection unit 10 uses the table shown in FIG. 7A, for example, if the number n of channel combinations is 10, 10 selection numbers and combinations of each channel shown in FIG. 7A are selected.
- step S108 the time slot selection is set to increase the probability of selecting from a relatively early time slot channel.
- steps S107 and S108 are skipped.
- step S113 it is determined whether or not the combination of the access methods of the spread code channel, the frequency channel, and the time slot channel has been selected for n channel combinations. If it is determined that n channel combinations are not selected, the process returns to step S112. That is, the process of step S112 is repeated n times. On the other hand, if it is determined that n channel combinations are selected, the process proceeds to step S114.
- the transmission unit 7 transmits the transmission data as a CDMA / FDMA / TDMA signal to the base station 2 via the satellite 1 by n combinations of access methods selected by the random selection unit 10 (step S114).
- the transmission unit 7 transmits the transmission data n times in combination. That is, the time slot channel selected in the time slot channel selection step and the frequency corresponding to the frequency channel selected in the frequency channel selection step are CDMA spread by the spreading code channel selected in the spreading code channel selection step.
- a transmission step for transmitting transmission data is executed n times.
- the combination setting unit 36 sets the number n of channel combinations to a value of 2 or more when the position of the own terminal is within a predetermined area based on the information on the inside / outside of the own terminal area.
- the information to be set is transmitted to the combination selection unit 35. This is to ensure that the short message can be delivered to the service center 16 by transmitting the same message a plurality of times using a combination of a plurality of channels when the terminal is present in a disaster area or the like.
- the combination selection unit 35 in the fifth embodiment, the probability setting unit 56
- Setting information for increasing the selection probability of the early time slot channel is transmitted to the combination selection unit 35. This is to increase the probability that a relatively early time slot can be selected when the terminal is present in a disaster area or the like so that the service center 16 can obtain a short message as soon as possible.
- FIG. 24 shows a method of randomly selecting one of a combination of a spread code channel, a frequency channel, and a time slot channel or the number n of channel combinations set by the combination setting unit 36 in the random selection unit 10 of the communication terminal 3.
- FIG. Steps S201, S202, and S203 are the same as those in the flowchart shown in FIG.
- step S304 shown in FIG. 24 the random selection unit 10 selects one combination of access methods of the selected spreading code channel, frequency channel, and time slot channel, and stores it in a memory (not shown).
- step S305 the random selection unit 10 repeats steps S201 to S203, S304 n times the number of channel combinations set by the combination setting unit 36.
- step S306 the random selection unit 10 notifies each unit of one or more combinations of access methods stored in the memory.
- the spread code channel is supplied to the spread code generator 9, the frequency channel is supplied to the FDM processor 13, and the time slot channel is supplied to the TDM processor 12.
- the communication terminal 3 randomly selects a combination of the spread code channel, the frequency channel, and the time slot channel, and transmits the transmission data to the base station 2 via the satellite 1 as a CDMA / FDMA / TDMA signal.
- collision of data transmitted simultaneously by a large number of communication terminals 3 can be suppressed, and the communication success probability, that is, the throughput can be increased.
- the communication method, the communication terminal 3, the base station 2, and the communication system 100 which can prevent that a communication line falls into a congestion state can be obtained.
- the selection range of the time slot channel may be limited to the channel 1 and the channel 2 and may be configured to be selected randomly.
- the selection range of the time slot channel may be limited to channel 1 and channel 2, and the selection unit 10 may select at random in step S110.
- the selection range of the time slot channel may be limited to the channel 3 and the channel 4, and the selection unit 10 may select at random in step S110.
- the present invention can be suitably employed in a wireless communication system, a communication terminal, a base station, and a communication method that perform communication between a base station and a communication terminal.
- Area information generation part (area information conversion part), 17 ... Forward link communication line, 18 ... Return link communication line, 19 ... GPS signal, 20 ... Duplexer, 21 ... Data output terminal, 22 ... Transmission data processing unit, 23 ... Data input terminal, 2 ... Wireless receiver, 25 ... QPSK demodulator, 26 ... Error correction decoder, 27 ... TDM separator, 28 ... GPS receiver, 29 ... GPS signal processor, 30 ... Data generator, 31 ... Error correction encoder 32 ... Transmission timing generation unit, 33 ... BPSK modulation unit, 34 ... Wireless transmission unit, 35 ... Combination selection unit, 36 ... Combination setting unit (table storage unit), 37 ... Position information acquisition unit, 38 ... Judgment processing unit, 39 ...
- Broadcast information acquisition unit 40 ... Area information unit, 41 ... Terrestrial interface unit, 42 ... Data generation unit, 43 ... TDM multiplexing unit, 44 ... Control information transmission unit, 45 ... Error correction coding unit, 46 ... QPSK Modulation unit, 47 ... radio transmission unit (base station side transmission unit), 48 ... duplexer, 49 ... radio reception unit (base station side reception unit), 50 ... CDMA despreading unit, 51 ... BPSK demodulation unit, 52 ... Correction decoding unit, 53 ... data processing unit, 54 ... time slot setting unit (second table storage unit), 55 ... probability distribution storage unit, 56 ... probability setting unit, 96 ... storage unit, 97 ... display unit, 98 ... Operation unit, 99 ... control unit, 100 ... communication system
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Abstract
Description
この衛星通信方式は、送信側の通信端末が、個別に割り当てられた拡散符号を用いて拡散された送信データを時間軸上のスロットに同期させて特定のスロット間隔で送信し、受信側の基地局が、受信データを送信側と同一の拡散符号を用いて逆拡散して必要なデータを抽出する方式である。
この二つのアクセス方式の組み合わせにより、複数の通信端末が同一のスロットでパケットを送信しても、拡散符号が異なっていれば、基地局は受信信号からデータを抽出できる。したがって、複数の通信端末から送信されたパケットの衝突により、基地局が受信信号からデータを抽出できないという事態が発生する確率は低減される。
また、本発明は、災害発生時に、多数の被災者が救難メッセージを送信することを可能とすることを他の目的とする。
以下、図1~7を参照しながら、本発明の実施の形態1について説明する。なお、図中、同一符号は、同一又は相当する部分を示すものとし、それらの詳細な説明は省略する。
TDMA処理部12は、CDMA拡散部11によりCDMA拡散された送信データを、その送信データを送信する時間スロットに応じて遅延させる。
BPSK(Binary Phase Shift Keying)変調部33は、TDMA処理部12から出力された送信データに応じて搬送波の位相を離散的に変化させ、伝送に適した電気信号に変換する。即ち、送信データにBPSK変調を施す。
FDMA処理部13は、BPSK変調部33から出力された送信データ信号を周波数変換する。
無線送信部34は、FDMA処理部13から出力された送信データ信号を電力増幅し、デュプレクサ20を介して、衛星通信用アンテナ3sから送信する。
GPS信号受信部28は、GPS衛星4からのGPS信号19を、GPS用アンテナ3gを介して受信する。
GPS信号処理部29は、GPS信号19を処理し、位置情報と時刻情報を復号し、送信タイミング生成部32に時刻情報を送信する。
ランダム選択部10は、拡散符号生成部9が使用する拡散符号チャネルをランダムに選択して拡散符号生成部9に通知する。また、ランダム選択部10は、TDMA処理部12が送信データを遅延させる時間の基になる時間スロットチャネルをランダムに選択してTDMA処理部12に通知する。さらに、ランダム選択部10は、FDMA処理部13が周波数変換する周波数チャネルをランダムに選択してFDMA処理部13に通知する。
デュプレクサ20は、衛星通信用アンテナ3sを介して通信衛星から受信した信号を受信部6に供給し、送信部7から供給された送信信号を衛星通信用アンテナ3sに供給する。
送信データ処理部22は、データ生成部30と誤り訂正符号化部31とを備え、誤り訂正符号が付された送信データを生成し、CDMA拡散部11に供給する。
データ生成部30は、送信タイミング生成部32から供給されるデータクロック信号に同期して、送信対象のデータ(送信データ)を生成する。
受信部6は、衛星通信用アンテナ3s、デュプレクサ20を介して、フォワードリンク信号を受信すると、これを復号し、フォワードリンク信号をデータ出力端子23に出力する。制御部99は、フォワード信号を受信したことに応答して、送信対象のデータを生成し、データ入力端子23を介して、送信データ処理部22に供給する。
データ生成部30と誤り訂正符号化部31とは、送信タイミング生成部32から出力されデータクロック信号と誤り訂正符号化クロックとに応答して、複数の通信端末3間で通信が同期するように、送信データに同期ビット、制御ビットなどが付加された予め定められたバーストフォーマットのデータに変換し、冗長ビットを付加して誤り訂正符号化を行なう。
なお、図3に示す例では、通信端末3A~3Cは、アクセス方式の組み合わせが互いに異なっているので、衛星1での送信データの衝突はない。
ショートメッセージを用いたサービスの一例として、災害発生時などにおいて、サービスセンター16が複数の通信端末3から、識別情報と位置情報等を含む救難メッセージを受信することがある。以下、このような場合を例に、各通信端末3の動作を説明する。
この場合、サービスセンター16は、基地局2に、フォワードリンク信号を被災者の携帯端末3に送信するように指示する。基地局2は、指示に応答して、フォワードリンク信号を、フォワードリンク通信回線17を介して被災者の携帯端末3に送信する。
図4に示すフローチャートの一連の処理は、この送信ステップは、衛星1を介して基地局2から送信されたフォワードリンク信号を通信端末3が受信したことをトリガとして、送信データをリターンリンク信号として基地局2に送信する処理といえる。
ステップS109は、拡散符号チャネル選択ステップによりランダムに選択された拡散符号チャネルを用いて送信データをCDMA拡散するCDMA拡散ステップ(CDMA拡散部11)である。
ステップS110は、時間スロットチャネル選択ステップによりランダムに選択された時間スロットチャネルでCDMA拡散ステップによってCDMA拡散された送信データが送信されるように遅延させる遅延ステップ(TDMA処理部12)である。
ステップS111は、周波数チャネル選択ステップによりランダムに選択された周波数チャネルに対応する周波数に遅延ステップで遅延された送信データを周波数変換する周波数変換ステップ(FDMA処理部13)である。
ステップS114は、CDMA拡散ステップによりCDMA拡散され、遅延ステップにより遅延され、周波数変換ステップにより周波数変換された送信データを送信する送信ステップ(無線送信部34)である。
次に、TDMA処理部12が、選択された時間スロットチャネルで、CDMA拡散された送信データが送信されるように、送信データを遅延させる遅延ステップを実行する。
最後に、FDMA処理部13が、選択された周波数チャネルに対応する周波数に前述の遅延ステップにより遅延された送信データを周波数変換する周波数変換ステップを実行した後、無線送信部34が、遅延ステップにより遅延され、周波数変換ステップにより周波数変換された送信データを送信する送信ステップを実行する。
ステップS203の処理において、ランダム選択部10は、複数(N個)の時間スロットの中から、ランダムに一つの時間スロットを選択する。
チャネルの総数は、L×N×M個となる。したがって、多数の通信端末3がほぼ同時に送信データ(ショートメッセージ)を送信しても、パケットが衝突する確率は小さい。したがって、スループットの高い、再送処理の少ない通信システムが得られる。
図6に示すように、変形例1のランダム選択部10は、組み合わせ選択部35と組み合わせ設定部(テーブル記憶部)36から構成される。図3に示す通信端末3では、ランダム選択部10が、設定されたものの中から、拡散符号チャネル、時間スロットチャネル、周波数チャネルを個別に選択しているが、図6に示す通信端末3では、図7Aに示す「テーブル記憶部(組み合わせ設定部)36が記憶するテーブル」に基づいて組み合わせ選択部35がランダムにアクセス方式の組み合わせを選択する。ランダム選択部10内では、組み合わせ設定部36がテーブルの情報(組み合わせ情報)を組み合わせ選択部35に送信する処理が行なわれる。
複数の通信端末3のなかで比較的早く通信させたいものがない場合、組み合わせ設定部36は、図7Aに示すテーブルの情報(組み合わせ情報)を組み合わせ選択部35に供給すればよい。また、複数の通信端末3のなかで比較的早く通信させたいものがある場合、その通信端末3の組み合わせ設定部36は、図7Bに示すテーブルの情報(組み合わせ情報)を組み合わせ選択部35に供給すればよい。また、複数の通信端末3のなかで比較的遅く通信させたいものがある場合、その通信端末3の組み合わせ設定部36は、図7Cに示すテーブルの情報(組み合わせ情報)を組み合わせ選択部35に供給すればよい。
なお、図7Bに示すテーブルの情報を組み合わせ選択部35に供給する場合、該通信端末3(通信端末3が複数の場合も含む)以外の通信端末3には、図7Cに示すテーブルの情報を組み合わせ選択部35に供給してもよいし、通常使用される図7Aに示すテーブルの情報を組み合わせ選択部35に供給してもよい。もちろん、図7Cに示すテーブルの情報を組み合わせ選択部35へ供給する場合、該通信端末3(通信端末3が複数の場合も含む)以外の通信端末3には、図7Bに示すテーブルの情報を組み合わせ選択部35に供給してもよいし、通常使用される図7Aに示すテーブルの情報を組み合わせ選択部35に供給してもよい。
本発明の実施の形態2について、図8、図9を参照しながら説明する。実施の形態2は、積極的に(通信システム全体として)通信端末3ごとに通信する時間に差異を設ける通信システムの例である。なお、実施の形態2においては、実施の形態1と同様の部分について同一符号を付す。
位置情報取得部37は、情報取得部8から自端末の位置情報(自端末位置データ)を取得し、ランダム選択部10に供給する。位置情報取得部37は、情報取得部8(GPS信号処理部29)と接続されている。具体的には、位置情報取得部37は、GPS信号処理部29が処理したGPS位置情報を取得する。
判断処理部38は、位置情報取得部37が取得した自端末の位置情報から、自端末の位置が予め定められた領域内にあるか否かを判定し、その判定結果を組み合わせ設定部(テーブル記憶部)36に通知する。
つまり、ランダム選択部10は、外部から取得した位置情報(GPS情報から取得した位置情報)から通信端末3の位置を判定する。
判断処理部38は、位置情報取得部37から取得した自端末の位置情報と記憶している領域情報に基づき、自端末が予め定められた領域内にあるか、あるいは予め定められた領域外にあるかを示す自端末領域内外情報を生成し、組み合わせ設定部36に供給する。
このフローチャートは、衛星1を経由して基地局2にCDMA拡散された送信データを送信する通信端末3が実行する通信方法を表すものである。なお、ステップS101,S102,S103,S109~S111,S114は、図5に示すものと同様である。
続いて、判断処理部38は、位置情報取得部37からの自端末位置情報と、組み合わせ設定部36が予め保有している領域情報とに基づいて、自端末3が予め定められた領域内に位置しているか否かを判別する(ステップS106)。
判断処理部38が自端末の位置が予め定められた領域内であると判別した場合(ステップS106;Yes)、組み合わせ設定部36は、時間スロットチャネルの選択において、相対的に早いものが選択される確率を高めるように設定する(ステップS108A)。
例えば、判断処理部38は、組み合わせ設定部36が図7Bに示すテーブルを組み合わせ選択部35に供給するように制御する。
一方、自端末の位置が予め定められた領域外であると判別された場合(ステップS106;No)、組み合わせ設定部36は、時間スロットチャネルの選択において、相対的に遅いものが選択される確率を高めるように設定する(ステップS108B)。例えば、判断処理部38は、ステップ108Aで、組み合わせ設定部36が図7Bに示すテーブルを組み合わせ選択部35に供給するように制御し、ステップ108Bで、組み合わせ設定部36が図7A又はCに示すテーブルを組み合わせ選択部35に供給するように制御する。或いは、判断処理部38は、ステップS108Aで、組み合わせ設定部36が図7Aに示すテーブルを組み合わせ選択部35に供給するように制御し、ステップ108Bで、組み合わせ設定部36が図7Cに示すテーブルを組み合わせ選択部35に供給するように制御する。
続いて、ステップS110において、ランダム選択部10は、時間スロットチャネルの一つをランダムに選択する。
ステップS110の時間スロットチャネル選択ステップは、通信端末3の所在地が予め定められた領域内にある場合、そうで無い場合と比較して、相対的に早い時間スロットチャネルを選択できる確率を高め、通信端末3の所在地が予め定められた領域外にある場合、そうで無い場合と比較して、相対的に遅い時間スロットチャネルを選択できる確率を高める処理である。また、ステップS110の時間スロットチャネル選択ステップは、通信端末3の所在地が予め定められた領域内にある場合、そうで無い場合と比較して、選択できる範囲内の時間スロットチャネルのうちで相対的に早いものからランダムに選択し、通信端末3の所在地が予め定められた領域外にある場合、そうで無い場合と比較して、選択できる範囲内の時間スロットチャネルのうちで相対的に遅いものからランダムに選択する処理である。
次に、本発明の実施の形態3について、図10~図15を参照しながら説明する。実施の形態2では、通信端末3の判断処理部38が予め定められた領域を示す領域情報を予め保有している場合について説明した。一方、この実施の形態3では、判断処理部38が領域情報を外部、特に、基地局2から取得する通信端末3について説明する。なお、実施の形態3においては、実施の形態1及び2と同様の部分には同一符号を付す。
通信端末3は、基地局2が送信するフォワードリンク信号を受信する受信部6と、リターンリンク信号を送信する送信部7とを備える。
図示するように、基地局2は、基地局送信部2t、基地局受信部2r、地上インターフェース部41、データ生成部42、制御情報送信部44、データ処理部53、デュプレクサ48を備える。
領域情報部40から送信された情報が、通信端末3が受信したときに、予め定められた領域を示す領域情報として利用できるものでない場合、例えば、単に、被災地の地名だけの場合は、サービスセンター16が備える領域情報生成部(領域情報変換部)16eが、領域情報部40から取得した情報を通信端末3が使用できる領域情報に変換してから、基地局2に送信すればよい。なお、基地局2が、領域情報生成部16eを備えてもよい。
図15Bは、複数の点で形成された予め定められた領域から、この予め定められた領域に包含される四角形(この四角形も、頂点(四点)から形成されたもの)の予め定められた領域E1を除く予め定められた領域E2と、この予め定められた領域2に包含される四角形の予め定められた領域E1とを示す例である。
図15Cは、一点を円の中心(重心)とした複数の円形で構成された予め定められた領域のうち、一つの円形を予め定められた領域E1とし、残りの円形で構成された予め定められた領域E2とを示す例である。
なお、予め定められた領域E1、予め定められた領域E2の半径や面積等の情報は事前に決めておき、通信端末3の判断処理部38又は放送情報取得部39が記憶させておいてもよいし、予め定められた領域E1、予め定められた領域E2の半径や面積等の情報を領域情報部40又は領域情報生成部(領域情報変換部)16eで設定して、フォワードリンク信号で位置の情報と併せて送信してもよい。
本発明の実施の形態4について、図16~図19を参照しながら説明する。実施の形態1~3では、ランダムにアクセス方式の組み合わせを選択する組み合わせ選択部35が、組み合わせ設定部(テーブル記憶部)36に記憶された「拡散符号チャネル」、「周波数チャネル」、「時間スロットチャネル」の三つのアクセス方式の組み合わせと、この組み合わせごとに付与された選択番号から構成されるテーブルから前述の選択番号を選択することにより、ランダムに「拡散符号チャネル」、「周波数チャネル」、「時間スロットチャネル」を決定していたが、実施の形態4では、「時間スロットチャネル」のみを別テーブルにしたものを説明する。なお、実施の形態4においては、実施の形態1~3と同様の部分には同一の符号を付す。
本発明の実施の形態5について、図20~図22を用いて説明する。実施の形態5に係る通信端末3は、確率分布特性に支配されてランダムに時間スロットチャネルを選択する点が、他の実施の形態に係る通信端末3と相違する。したがって、実施の形態5に係る通信端末3は、自端末の位置に応じて選択できる時間スロットチャネルを変更する必要がある場合でも、ランダム選択部10は、例えば、図7に示すようなテーブルを保持して、自端末の位置に応じて参照するテーブルを変更する必要はない。なお、拡散符号チャネル及び周波数チャネルの選択に関しては、実施の形態5に係る通信端末3と実施の形態1~4に係る通信端末3とは基本的な動作は同じである。つまり、拡散符号チャネル及び周波数チャネルは、組み合わせ選択部35によってランダムに選択される。
本発明の実施の形態6について、図24を参照しながら説明する。実施の形態1~5では、再送や再々送の必要が無い場合は、通信端末3は、一度だけリターンリンク信号を送信することを前提としたものであった。実施の形態6に係る通信端末3が、最初から複数回にわたって、ターンリンク信号を送信する場合について説明する。なお、実施の形態6に係る通信方法について、図23及び図24のフローチャートを用いて説明し、実施の形態6に係る通信端末3、基地局2及び通信システム100の構成の説明は省略する。
例えば、図7Bのテーブルを使用する代わりに、例えば、時間スロットチャネルの選択の範囲をチャネル1とチャネル2に限定して、選択部10がステップS110でランダムに選択するようにしてもよい。同様に、図7Cのテーブルを使用する代わりに、例えば、時間スロットチャネルの選択の範囲をチャネル3とチャネル4に限定して、選択部10がステップS110でランダムに選択するようにしてもよい。
Claims (25)
- 衛星を経由してCDMA拡散された送信データを送信先に送信する通信方法であって、
送信データをCDMA拡散するための拡散符号チャネルをランダムに選択する拡散符号チャネル選択ステップと、
前記CDMA拡散された送信データを送信する時間スロットチャネルをランダムに選択する時間スロットチャネル選択ステップと、
前記CDMA拡散された送信データを送信する周波数チャネルをランダムに選択する周波数チャネル選択ステップと、
前記時間スロットチャネル選択ステップで選択された時間スロットチャネル、かつ、前記周波数チャネル選択ステップで選択された周波数チャネルに対応する周波数で、前記拡散符号チャネル選択ステップで選択された拡散符号チャネルで前記CDMA拡散された送信データを送信する送信ステップと、
を備える通信方法。 - 前記拡散符号チャネル選択ステップで選択された拡散符号チャネルを用いて前記送信データをCDMA拡散するCDMA拡散ステップと、
前記時間スロットチャネル選択ステップで選択された時間スロットチャネルで前記CDMA拡散ステップによってCDMA拡散された送信データが送信されるように遅延させる遅延ステップを含み、
前記周波数チャネル選択ステップで選択された周波数チャネルに対応する周波数に前記遅延ステップで遅延された送信データを周波数変換する周波数変換ステップと、
をさらに備える請求項1に記載の通信方法。 - 前記時間スロットチャネル選択ステップは、
送信元が予め定められた領域の内にある場合、予め定められた領域の外にある場合と比較して、相対的に早い時間スロットチャネルを選択できる確率を高めるステップ、
及び/又は、
送信元が予め定められた領域の外にある場合、予め定められた領域の内にある場合と比較して、相対的に早い時間スロットチャネルを選択できる確率を下げるステップ、
から構成される請求項1又は2に記載の通信方法。 - 前記時間スロットチャネル選択ステップは、
送信元が予め定められた領域の内にある場合、予め定められた領域の外である場合と比較して、選択できる範囲内の時間スロットチャネルのうちで、相対的に早いものからランダムに選択するステップ、
及び/又は、
送信元が予め定められた領域の外にある場合、予め定められた領域の内にある場合と比較して、選択できる範囲内の時間スロットチャネルのうちで、相対的に遅いものからランダムに選択するステップ、
から構成される請求項1乃至3のいずれか一項に記載の通信方法。 - 前記送信元の所在地を取得する送信元位置取得ステップをさらに備える、請求項3又は4に記載の通信方法。
- 前記送信ステップは、前記衛星を介して前記基地局から送信されたフォワードリンク信号を受信したことをトリガとして、前記送信データをリターンリンク信号として前記基地局へ送信するステップである、請求項3乃至5のいずれか一項に記載の通信方法。
- 前記予め定められた領域は、前記フォワードリンク信号で領域の情報が送信され、この領域の情報が示す少なくとも一点の位置情報から予め定められた条件に基づいて設定された領域である、請求項6に記載の通信方法。
- 前記拡散符号チャネル選択ステップ及び前記周波数チャネル選択ステップは、予め設定され、拡散符号チャネル及び周波数チャネルの組み合わせから成るテーブルからランダムに選択するステップから構成される、請求項1乃至7のいずれか一項に記載の通信方法。
- 前記拡散符号チャネル選択ステップ及び前記周波数チャネル選択ステップ並びに前記時間スロットチャネル選択ステップは、予め設定され、拡散符号チャネル及び周波数チャネル並びに時間スロットチャネルの組み合わせから成るテーブルからランダムに選択する、請求項1乃至8のいずれか一項に記載の通信方法。
- 前記CDMA拡散された送信データの送信を、他の送信元と同期して行うための同期ステップをさらに備える、請求項1乃至9のいずれか一項に記載の通信方法。
- 前記拡散符号チャネルは、直交符号チャネルである、請求項1乃至10のいずれか一項に記載の通信方法。
- 衛星を経由してCDMA拡散された送信データを送信する通信端末であって、
送信データをCDMA拡散するCDMA拡散部と、
このCDMA拡散部がCDMA拡散するために用いる拡散符号を生成する拡散符号生成部と、
前記CDMA拡散部によってCDMA拡散された送信データを送信する時間スロットに応じて遅延させるTDMA処理部と、
このTDMA処理部によって遅延された送信データを周波数変換するFDMA処理部と、
前記拡散符号生成部が使用する拡散符号チャネルをランダムに選択して指示し、前記TDMA処理部が送信データを遅延させる時間の基になる時間スロットチャネルをランダムに選択して指示し、前記FDMA処理部が周波数変換する周波数チャネルをランダムに選択して指示するランダム選択部と、
を備える通信端末。 - 前記ランダム選択部は、拡散符号チャネルと時間スロットチャネルと周波数チャネルの組み合わせを複数格納するテーブルから、ランダムに、拡散符号チャネルと時間スロットチャネルと周波数チャネルの組み合わせを選択する、請求項12に記載の通信端末。
- 前記通信端末は、位置情報を取得する位置情報取得部をさらに備え、
前記ランダム選択部は、前記位置情報から得られた位置が予め定められた領域の内にある場合、そうで無い場合と比較して、前記TDMA処理部が送信データを遅延させる時間の基になる時間スロットを相対的に早い時間スロットチャネルから選択できる確率を高め、及び/又は、前記位置情報から得られた位置が予め定められた領域の外にある場合、そうで無い場合と比較して、前記TDMA処理部が送信データを遅延させる時間の基になる時間スロットを相対的に早い時間スロットチャネルから選択できる確率を下げる、
請求項12又は13に記載の通信端末。 - 前記通信端末は、位置情報を取得する位置情報取得部をさらに備え、
前記ランダム選択部は、前記位置情報から得られた位置が予め定められた領域の内にある場合、そうで無い場合と比較して、前記TDMA処理部が送信データを遅延させる時間の基になる時間スロットを、選択できる範囲内の時間スロットチャネルのうちで相対的に早い時間のものからランダムに選択し、及び/又は、前記位置情報から得られた位置が予め定められた領域の外にある場合、そうで無い場合と比較して、前記TDMA処理部が送信データを遅延させる時間の基になる時間スロットを、選択できる範囲内の時間スロットチャネルのうちで相対的に遅い時間のものからランダムに選択する、
請求項12又は13に記載の通信端末。 - 前記通信端末は、GPS情報を取得する情報取得部を備え、
前記拡散符号生成部は、前記情報取得部が取得した前記GPS情報から得られる時刻情報から生成された拡散符号開始タイミングで拡散符号を生成する、請求項12乃至15のいずれか一項に記載の通信端末。 - 衛星を経由して複数の通信端末と通信を行う基地局であって、
前記基地局に前記複数の通信端末がリターンリンク信号を送信するトリガとなるフォワードリンク信号に、予め定められた条件に基づいて設定された領域の情報を含めて、前記複数の通信端末に送信する基地局送信部と、
時刻情報から生成され、前記複数の通信端末間で同期した拡散符号開始タイミングにより生成された拡散符号によってCDMA拡散された前記リターンリンク信号を前記複数の通信端末から受信する基地局受信部と、
を備える基地局。 - 前記領域の情報は、この領域の情報が示す予め定められた領域の内に前記通信端末がある場合とそうで無い場合とで、前記通信端末に、前記リターンリンク信号を送信する時間スロットチャネルの選択範囲を変更させる、請求項17に記載の基地局。
- 前記基地局送信部は、前記領域の情報として少なくとも一点の位置情報を送信する、請求項18に記載の基地局。
- 前記基地局送信部は、地名情報を前記領域の情報に変換して送信する手段を含む、請求項19に記載の基地局。
- 衛星を経由して基地局と複数の通信端末とが通信を行う通信システムであって、
前記基地局は、前記複数の通信端末にフォワードリンク信号を送信し、
前記複数の通信端末は、それぞれ、
前記フォワードリンク信号を受信する受信部と、
この受信部が前記フォワードリンク信号を受信したことをトリガに、生成した送信データをCDMA拡散し、このCDMA拡散された送信データを送信する時間スロットに応じて遅延させ、この遅延された送信データを周波数変換して前記基地局へ送信する送信部と、
前記衛星又はGPS衛星から得られるGPS情報を取得する情報取得部と、
前記GPS情報から得られる時刻情報から生成され、前記複数の通信端末間で同期した拡散符号開始タイミングに応答して、前記送信部がCDMA拡散するために用いる拡散符号を生成する拡散符号生成部と、
前記拡散符号生成部が使用する拡散符号チャネルをランダムに選択して指示し、前記送信部が送信データを遅延させる時間の基になる時間スロットチャネルをランダムに選択して指示し、前記送信部が周波数変換する周波数チャネルをランダムに選択して指示するランダム選択部と、
を備える通信システム。 - 前記受信部は、受信した前記フォワードリンク信号から予め定められた領域の情報を取得し、
前記ランダム選択部は、前記予め定められた領域の内に通信端末がある場合、そうで無い場合と比較して、前記送信部が送信データを遅延させる時間の基になる時間スロットを相対的に早い時間スロットチャネルから選択できる確率を高め、及び/又は、前記予め定められた領域の外に該ランダム選択部を有する通信端末がある場合、そうで無い場合と比較して、前記送信部が送信データを遅延させる時間の基になる時間スロットを相対的に早い時間スロットチャネルから選択できる確率を下げる、
請求項21に記載の通信システム。 - 前記受信部は、受信した前記フォワードリンク信号から予め定められた領域の情報を取得し、
前記ランダム選択部は、前記予め定められた領域の内に通信端末がある場合、そうで無い場合と比較して、前記送信部が送信データを遅延させる時間の基になる時間スロットを、選択できる範囲内の時間スロットチャネルのうちで相対的に早い時間のものからランダムに選択し、及び/又は、前記予め定められた領域の外に通信端末がある場合、そうで無い場合と比較して、前記送信部が送信データを遅延させる時間の基になる時間スロットを、選択できる範囲内の時間スロットチャネルのうちで相対的に遅い時間のものからランダムに選択する、
請求項21に記載の通信システム。 - 前記ランダム選択部は、前記GPS情報から得られる位置情報から前記通信端末の位置を判断する請求項22又は23に記載の通信システム。
- 前記受信部は、前記フォワードリンク信号から得られる領域の情報が示す少なくとも一点の位置情報から予め定められた条件に基づいて設定された領域を、前記予め定められた領域とする、請求項22乃至24のいずれか一項に記載の通信システム。
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AU2013333213B2 (en) | 2016-05-26 |
EP2911306A1 (en) | 2015-08-26 |
US20150289163A1 (en) | 2015-10-08 |
JP5573917B2 (ja) | 2014-08-20 |
JP2014082720A (ja) | 2014-05-08 |
KR101649085B1 (ko) | 2016-08-17 |
KR20150058413A (ko) | 2015-05-28 |
AU2013333213A1 (en) | 2015-05-07 |
EP2911306B1 (en) | 2017-10-25 |
EP2911306A4 (en) | 2016-06-15 |
CN104756408B (zh) | 2016-11-09 |
CN104756408A (zh) | 2015-07-01 |
US9826431B2 (en) | 2017-11-21 |
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