WO2007108409A1 - 無線伝送システム及び無線伝送方法、並びにそれらに用いられる無線局及び送信局 - Google Patents
無線伝送システム及び無線伝送方法、並びにそれらに用いられる無線局及び送信局 Download PDFInfo
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- WO2007108409A1 WO2007108409A1 PCT/JP2007/055353 JP2007055353W WO2007108409A1 WO 2007108409 A1 WO2007108409 A1 WO 2007108409A1 JP 2007055353 W JP2007055353 W JP 2007055353W WO 2007108409 A1 WO2007108409 A1 WO 2007108409A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
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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
- H04B1/7097—Interference-related aspects
- H04B1/711—Interference-related aspects the interference being multi-path interference
- H04B1/7115—Constructive combining of multi-path signals, i.e. RAKE receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
- H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
- H04W56/0045—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by altering transmission time
Definitions
- the present invention relates to a wireless transmission system and a wireless transmission method in which a plurality of wireless transmission devices transmit and receive signals using a transmission method having multipath resistance, and a wireless station and a transmitting station used for them. .
- Orthogonal Frequency Division Multiplexing OFDM
- anti-multipath modulation method that provides multinos resistance by adding phase and amplitude redundancy in the transmission symbol
- PSK-VP Phase Shift Keying
- PSK with Random Amplitude Redundancy Return to Zero Phase Shift Keying
- Non-Patent Document 2 PSK with Random Amplitude Redundancy (Return to Zero Phase Shift Keying)
- the modulation method is normal, but there is a method that exhibits multipath resistance by using an equalizer on the receiving side.
- the spread spectrum method includes, for example, a direct sequence spread spectrum (DSSS) that multiplies spread signals in a wider band than the original signal, and a frequency hopping method (FHSS) that hops a frequency over a wide band.
- DSSS direct sequence spread spectrum
- FHSS frequency hopping method
- THSS Frequency hopping spread spectrum
- THSS time hopping spread spectrum
- the following conditions apply to the upper and lower limits of the arrival time difference of signals.
- the lower limit of the arrival time difference that can exhibit the effects of path diversity is the delay resolution
- the upper limit is the delay upper limit.
- the delay resolution and the upper limit of the delay may be determined from the principle of the modulation / demodulation method used, and the modulation / demodulation method meter and implementation constraints may also be determined.
- the delay resolution corresponds to one chip length of the spreading code
- the delay upper limit corresponds to less than the spreading code length. Therefore, when communicating using the DSSS method, if the arrival time difference is 1 chip or more and less than the spread code length, the reception side separates the received signal into delayed wave components and synthesizes them (RAKE reception). Diversity effect can be obtained.
- the delay upper limit corresponds to the time length of the guard interval in order to absorb the delayed wave component in the guard interval set in the signal. Intersymbol interference does not occur if the arrival time difference of the delayed wave is within the guard interval. Also, since error correction processing is usually performed across a plurality of subcarriers, information can be reproduced even if some subcarriers generate errors due to multipath distortion. On the other hand, the delay resolution is equivalent to the reciprocal of the frequency bandwidth. In this way, when using the OFDM scheme, the effect of path diversity can be obtained by the effect of the guard interval and the frequency diversity effect of collecting and collecting information over a wide frequency band.
- the delay resolution corresponds to a fraction of the symbol length, and the upper limit of the delay is one symbol length. It corresponds to less than about time.
- the delay resolution corresponds to the symbol length and the upper limit of the delay is the time length determined by the number of taps It corresponds to.
- Patent Document 1 describes a conventional wireless transmission system that performs communication using a modulation / demodulation method having multipath resistance.
- Figure 51 shows the wireless transmission system described in Patent Document 1. It is a block diagram of a stem. In FIG. 51, only the downlink system in which a signal is transmitted from the base station 310 to the mobile station 330 is shown. In FIG. 51, a base station 310 establishes a communication area (radio zone) 300 and communicates with a mobile station 330 in the area using a CDMA (Code Division Multiple Access) system.
- CDMA Code Division Multiple Access
- a signal output from radio device 311 is transmitted to relay device 320 and mobile station 330 via transmission antenna 312.
- signal S 1 received by reception antenna 322 is delayed by delay unit 324 and input to combiner 323.
- the signal S 2 received by the antenna 321 is directly input to the combiner 323.
- the combiner 323 combines the signals S1 and S2.
- the signal combined by the combiner 323 is amplified by the amplifier 325 and transmitted to the mobile station 330 via the transmission antenna 326.
- the mobile station 330 is a RAKE receiver, and receives three signals: a signal to which a relay apparatus gives a delay, a signal that has not been given, and a signal that has been transmitted by a transmitting station.
- delay unit 324 gives a delay equal to or greater than the code time (chip length) of the spread code sequence to signal S1, and therefore a delay equal to or greater than the chip length occurs between a plurality of signals.
- RAKE reception is performed to obtain a no-diversity effect and improve the transmission characteristics.
- This conventional wireless transmission system aims at improving the transmission characteristics by enhancing the effect of path diversity by artificially adding another transmission path delay wave as described above.
- the modulation method of the transmission method described in Patent Document 2 focusing on the symbol waveform (phase waveform in the symbol) is a convex phase synchronized with the symbol period T with respect to the phase of the symbol waveform.
- a method of obtaining a detection output by delay detection having a transition can avoid a situation in which the detection output is lost due to multipath, and conversely, a transmission effect can be improved by obtaining a path synthesis effect. In principle, this improvement effect is effective when the delay amount ⁇ of the delayed wave is within a predetermined range (0 to ⁇ ⁇ ).
- FIG. 52 is a schematic diagram showing the phase transition of the symbol waveform described in Patent Document 2.
- this phase transition is defined as a parabolic shape based on the function shown in the following equation (1), with the transition width at the time length (symbol length) ⁇ ⁇ ⁇ ⁇ of one symbol defined by the maximum phase transition amount ⁇ . Change the phase.
- FIG. 53 is a diagram showing a configuration of a transmission signal generation circuit 700 described in Patent Document 2.
- the transmission signal generation circuit 700 includes a differential sign circuit 701, a waveform generation circuit 702, a quadrature modulator 704, and an oscillator 703.
- the transmission signal generation circuit 700 then differentially encodes the transmission data by the differential encoding circuit 701, modulates the transmission data using the symbol waveform having convex phase redundancy by the waveform generation circuit 702, and performs orthogonal Modulator 704 converts the signal to a carrier frequency band signal.
- FIG. 54 is a schematic diagram showing the phase relationship between two incoming signals A and B when a symbol waveform having convex phase redundancy is used.
- the phase difference ⁇ is 180 °
- the phase transitions in a convex shape even when there is a delay between the incoming signals. Therefore, the phase where the received waves disappear due to cancellation within the effective interval (b in Fig. 54)
- the phase where the received waves disappear due to cancellation within the effective interval (b in Fig. 54)
- points a and c in Fig. 54 there are sections (points a and c in Fig. 54) where the received wave remains without cancellation.
- FIG. 55 is a schematic diagram showing a configuration of a conventional wireless transmission system using transmission diversity by a modulation method described in Patent Document 2.
- a delay device 901 is provided between the transmission signal generation circuit 700 and the first and second antennas 904 and 905, and a delay is provided between the signals transmitted from the first and second antennas 904 and 905. insert.
- the transmission characteristics can be improved by setting the delay amount so that the pass diversity effect is satisfactorily exhibited.
- Patent Document 1 Patent No. 2764150 Specification
- Patent Document 2 Patent No. 2506748
- Non-Patent Document 1 Etch Takai, “B'Performance'Ob'Anti-Multipath Modulation'Scheme ⁇ Pieske ⁇ —— Buipi ⁇ ⁇ and"It's Optimum 'Phase Waveform ", Eye Triple I ⁇ ⁇ ⁇ Trans buoy techno
- Non-Patent Document 2 S. Aaryavistacle, S. Yoshida, F. Ikegami, K. Tanaka, T. Takeuchi, “A 'Power Efficient' Linear 'Digital' Modulator 'and' It's Application ' ⁇ An'Anti-multipath ⁇ Modulation 'PSK RZet' Scheme ', Proceedings' Ob' I Triple I ⁇ ⁇ ⁇ Bikura ⁇ ⁇ ⁇ Technology Conference (S. Ariyavisitakul, S. Yoshida, F. Ikegami, K. Tanaka, T.
- the maximum number of effective branches (hereinafter, the maximum number of effective branches) is limited to a small number for independent branches that contribute to the path diversity effect. There is. This is because the maximum number of effective branches that contribute to the path diversity effect is less than or equal to the value obtained by dividing the upper limit of delay by the delay resolution, but this becomes very small when the upper limit of delay is close to the delay resolution.
- the upper limit of delay corresponds to less than the spreading code length, so that the spreading code length becomes shorter, and the number of maximum effective branches becomes smaller when the spreading chip length corresponding to the delay resolution is approached.
- the spreading code length is 4 chips and the spreading factor is 4 times, that is, when spreading with a spreading code of 1 symbol power chip
- the delay resolution is 1 chip length and the upper limit of delay is 3 chips length Therefore, the number of branches is about 4 at most.
- the delay resolution corresponds to the spreading bandwidth, and the upper limit of the delay is determined by the hop sequence length. Therefore, when the hop sequence length is narrow with a narrow spreading bandwidth, the maximum number of effective branches is limited to a small number.
- the delay resolution corresponds to the pulse width, and the upper limit of the delay is determined by the pulse sequence length. Therefore, if the pulse sequence length is wide and the pulse sequence length is short, the number of branches is limited to a small number.
- the delay resolution corresponds to the frequency bandwidth in which subcarriers are distributed and the upper limit of delay is determined by the guard interval length. Therefore, when the guard interval with a narrow frequency bandwidth is short, the maximum number of effective branches is limited to a small number.
- the PSK-VP method or PSK-RZ method the delay limit cannot exceed the symbol length in principle, so the delay resolution and the delay upper limit are close to each other.
- the delay resolution is determined by the symbol length, and the upper limit of the delay is determined by the tap length of the equalization filter. Therefore, when the filter tap time length is shorter than the symbol length, the same case occurs. Note that in an equalizer, the number of taps greatly affects the circuit scale, so the upper limit of delay is often limited due to circuit scale constraints.
- FIG. 56 is a schematic diagram showing a case where the phase relationship of the incoming signal is opposite in phase in the modulation scheme described in Patent Document 2. As shown in Fig. 56, even if the phase transition is convex, if there is no delay between the two incoming signals, the detection output will be lost if the phase is reversed, and the improvement effect will be lost. .
- FIG. 57 schematically shows the relationship between the bit error rate and the amount of delay of the transmission method described in Patent Document 2 in the two-wave arrival model.
- the horizontal axis represents the amount of delay between incoming signals in the two-wave arrival model
- the vertical axis represents the bit error rate.
- FIG. 58 is a diagram illustrating an actual bit error rate characteristic with respect to the arrival time difference of two waves in a four-phase PSK-VP method (hereinafter, QPSK-VP method) two-wave rice model.
- the horizontal axis shows the difference between arrival times and the symbol length T, and the vertical axis shows the bit error rate.
- Patent Document 2 describes a method of configuring transmission diversity by inserting a predetermined predetermined delay into a transmission signal (FIG. 55).
- the amount of delay inserted by the delay device 901 is assumed to be, for example, as shown in FIG. 57, assuming that the path difference in the propagation path including the feeder line and the delay dispersion in each path are added.
- Bottom of error rate characteristic curve (good error rate
- FIG. 59 shows the case where there are 2 reception waves (2 reception timings) and 3 waves (3 reception timings) in the QPSK-VP system.
- FIG. 60 shows the bit error rate characteristics
- FIG. 60 shows the time relationship between the 2 and 3 waves in FIG.
- each received wave is a rice fading wave
- the 3 wave is a transmission path model in which the 3rd wave is inserted at an intermediate time position in the case of 2 waves.
- the bit error rate is degraded when the third wave is inserted between the two waves compared to when the received wave is two waves.
- an object of the present invention is to increase the maximum number of effective branches that contribute to the effect of path diversity, and to maximize the effect of path diversity even when it is limited to a small number. It is to provide a wireless transmission system and a wireless transmission method that can be used, and a wireless station and a transmitting station used for them.
- path diversity is configured by a plurality of radio stations, a receiving station, and a multipath transmission path formed between these stations, and the plurality of radio stations transmit signals to the receiving station. It is directed to the system, radio station and transmitter station or method used in this system. And in this invention, in order to achieve the said objective, the following structure is used.
- Each of the plurality of radio stations selects a waveform selection control unit that selects one of a plurality of mutually different symbol waveform candidates, and transmits data based on the symbol waveform selected by the waveform selection control unit.
- a modulation unit that generates a transmission signal and a reference that transmits the transmission signal
- the transmission timing control unit that determines the timing at which the quasi-timing force is delayed by a predetermined delay amount as the transmission start timing for starting transmission of the transmission signal, and the transmission signal is transmitted at the transmission start timing determined by the transmission timing control unit.
- a transmitting unit The receiving station includes a receiving unit that receives a transmission signal transmitted from the transmitting unit.
- the number of reception timings at which the transmission signal is received by the receiving unit is set to a plurality of different symbol waveforms for each different symbol waveform, the difference in reception timing is equal to or greater than a predetermined delay resolution, and the maximum reception timing is obtained.
- the predetermined delay amount is set so that the difference between the value and the minimum value is less than or equal to the predetermined delay upper limit. It is desirable that the receiving station obtains a detection signal by delay detection.
- each of the predetermined delay resolution and the predetermined delay upper limit is set to a value that allows path diversity reception of a plurality of delayed waves.
- the reference timing that a plurality of radio stations have is the same predetermined timing.
- This wireless transmission system may further include a transmission station that transmits a signal to be transmitted to the receiving station to a plurality of wireless stations.
- each of the plurality of radio stations further includes a timing detection unit that receives a signal transmitted from the transmission station and detects a reception timing, and the transmission timing control unit determines the timing detected by the timing detection unit. It is determined as the reference timing, and the transmission unit may relay and transmit the received signal to the receiving station.
- the timing detection unit preferably detects a unique word included in the signal.
- the wireless transmission system further includes a transmission station that transmits a signal to be transmitted to the receiving station to the plurality of wireless stations, and the transmission station transmits a signal to the plurality of wireless stations.
- a transmission timing control unit that determines a timing at which the reference timing force is delayed by a predetermined delay amount as a retransmission start timing for transmitting a signal to the receiving station, and signals to a plurality of radio stations at the transmission start timing.
- a transmission unit that transmits and transmits a signal to the receiving station at a retransmission start timing.
- each of the plurality of radio stations further includes a timing detection unit that receives a signal transmitted from the transmission station and detects a reception timing, and the transmission timing control unit detects the timing detected by the timing detection unit. If the transmission unit relays the signal received by the timing detection unit to the receiving station, using the timing as the reference timing.
- the wireless transmission system further includes a transmitting station that transmits a signal to be transmitted to the receiving station to a plurality of wireless stations, and the transmitting station provides each of the signals transmitted by the plurality of wireless stations.
- the delay amount and symbol waveform determination unit for selecting the power delay amount and the symbol waveform used by multiple radio stations to generate the transmission signal one by one from the plurality of candidate values, and the delay amount / symbol waveform determination unit.
- the delay amount 'symbol waveform adding unit for adding the delay amount and symbol waveform information to the signal, and the signal having the delay amount and symbol waveform information added by the delay amount' symbol waveform adding unit to a plurality of wireless A transmission unit for transmitting to the station.
- each of the plurality of radio stations further receives a signal transmitted from the transmitting station, and further includes a delay amount and symbol waveform extraction unit for extracting the delay amount and symbol waveform information added to the signal.
- the transmission timing control unit determines the timing delayed by the delay amount extracted by the reference timing delay / symbol waveform extraction unit as the transmission start timing, and the modulation unit determines the delay amount 'symbol waveform extraction unit.
- a transmission signal may be generated from transmission data based on the symbol waveform information extracted in step (b).
- the plurality of radio stations are arranged such that the communication ranges of the radio stations adjacent to each other within a predetermined distance partially overlap, and the delay amount and symbol waveform determining unit are transmitted from the adjacent radio stations.
- the amount of delay is adjusted so that the received signal is received at the receiving station at different timings, and the transmitted signal is received at the receiving station at the same timing. It is preferable.
- a delay amount setting unit that selects a predetermined delay amount from a plurality of candidate values or a plurality of candidate value forces randomly selects a delay amount may be further provided.
- the waveform selection control unit may select a symbol waveform at random for a plurality of candidate powers for each of a plurality of radio stations.
- the plurality of radio stations have the same symbol waveform power of any two symbols separated by a predetermined number of symbols, regardless of transmission data, and the phase difference between the two arbitrary symbols is the same. Then, a transmission signal determined based on the transmission data is generated. Predetermined The number of symbols is 1, and one of the angles obtained by equally dividing 2 ⁇ by the power of 2 is used for the phase difference.
- the plurality of radio stations have a first symbol waveform having a phase transition in which the phase increases in the time direction in one symbol period and the second derivative of the time change of the phase is not always zero;
- the phase change in time and the second derivative of the phase change over time is not always zero, and the second symbol waveform with phase transition, or the time change of phase up to a predetermined point in one symbol period
- the time variation of the phase up to the predetermined point in one symbol period has a phase transition in which the time variation of the phase increases after the predetermined point.
- the first symbol waveform and the second symbol waveform having a phase transition in which the phase before the center point and the phase after the center point change symmetrically are used as at least a predetermined number of symbol waveform candidates. Include It is preferable.
- the present invention even when the number of branches that can obtain the effect of path diversity is limited to a small number, the combination of a plurality of transmission timings and a plurality of symbol waveforms maximizes the number of branches. It can exhibit a no-diversity effect. Therefore, the transmission characteristics of the wireless transmission system can be improved.
- FIG. 1 is a diagram showing a configuration of a wireless transmission system according to a first embodiment of the present invention.
- FIG. 2 is a block diagram showing a detailed configuration example of the radio station 11
- Fig. 3 is a block diagram showing a detailed configuration example of the modulator 21.
- FIG. 4 is a diagram showing an example of a differential code rule and a signal space diagram of the transmission system according to the first embodiment of the present invention.
- FIG. 5 is a diagram showing an example of the internal configuration of each block of the modulation unit 21
- FIG. 6 is a schematic diagram showing an example of a phase transition of a symbol waveform generated by the modulation unit 21
- FIG. 7 is a block diagram showing a detailed configuration example of the receiving station 12
- FIG. 8 is a block diagram showing a detailed configuration example of the demodulation unit 33
- Fig. 9 is a schematic diagram showing the phases of incoming signals A and B at the receiving station 12 for each symbol.
- Fig. 10 shows the phase relationship between incoming signals A and B and the inter-symbol Phase transition diagram schematically showing the phase relationship of
- Figure 11 shows the phase relationship between incoming signal A and incoming signal B as a vector
- Figure 12 shows the phase transition between incoming signal A and incoming signal B as a vector
- Fig. 13 is a schematic diagram showing the phase relationship between the incoming signals A and B received at the receiving station 12 when the delay dispersion of the propagation path can be ignored.
- FIG. 14 is a diagram showing the detection output of the incoming signals A and B shown in FIG. 13 after passing through the low-pass filters 1810 and 1811.
- Figure 15 is a conceptual diagram of a two-wave arrival model with two radio stations A and B.
- FIG. 16A is a schematic diagram showing the change in phase of the direct wave and the delayed wave of transmission signal A for each symbol.
- FIG. 16B is a schematic diagram showing the change in phase of the direct wave and the delayed wave of transmission signal B for each symbol.
- FIG. 17 is a diagram showing the phase relationship at the reception point of each carrier wave for the direct wave and delayed wave of transmission signals A and B.
- FIG. 18A is a phase transition diagram schematically showing the phase relationship between the direct wave and the delayed wave of transmission signal A and the phase relationship between symbols.
- FIG. 18B is a phase transition diagram schematically showing the phase relationship between the direct wave and the delayed wave of transmission signal B and the phase relationship between symbols.
- Fig. 19A is a schematic diagram showing the phase transition of the direct wave and delayed wave of transmission signal A as vectors.
- FIG. 19B is a schematic diagram showing the phase transition between the direct wave and the delayed wave of transmission signal B as a vector.
- FIG. 20 is a schematic diagram showing the phase transitions of all incoming waves as vectors.
- FIG. 21 is a diagram schematically showing the relationship between the bit error rate and the delay amount according to the transmission method of the present invention.
- FIG. 22 is a flowchart showing the operation of the radio station 11
- FIG. 23 is a diagram illustrating the timing at which radio stations A to D transmit signals.
- FIG. 24 is a block diagram showing the configuration of the radio station 20 when the modulation section gives a delay to the modulated baseband signal.
- FIG. 25 is a block diagram illustrating a detailed configuration example of the modulation unit 21c.
- FIG. 26 is a block diagram showing another detailed configuration example of the modulation unit 21c.
- FIG. 27 is a diagram showing a configuration of a wireless transmission system according to a second embodiment of the present invention.
- FIG. 28 is a diagram showing the structure of a frame used for signals transmitted by the transmitting station 13 and the wireless station 14.
- FIG. 29 is a block diagram illustrating a detailed configuration example of the radio station 14
- FIG. 30 is a flowchart showing the operation of the radio station 14
- FIG. 31 is a diagram illustrating timings at which the radio stations A1 to D1 transmit signals A1 to D1.
- FIG. 32 illustrates the configuration of the wireless transmission system according to the third embodiment of the present invention.
- FIG. 33 is a block diagram showing a detailed configuration example of the transmitting station 15
- FIG. 34 is a flowchart showing the operation of the transmitting station 15
- FIG. 35 is a diagram showing timings of signals transmitted by the transmitting station 15 and the wireless stations Al to D1.
- FIG. 36 is a diagram showing another configuration of the wireless transmission system according to the third embodiment of the present invention.
- FIG. 37 is a diagram showing a configuration of a wireless transmission system according to a fourth embodiment of the present invention.
- FIG. 38 is a block diagram showing a detailed configuration example of a transmitting station 16.
- FIG. 39 is a block diagram illustrating a detailed configuration example of the radio station 17
- FIG. 40 is a flowchart showing operations of the transmitting station 16 and the wireless station 17
- FIG. 41 is a diagram showing an example of signal transmission timing by the radio station 17
- FIG. 42 is a diagram showing a configuration of a wireless transmission system according to a fifth embodiment of the present invention.
- FIG. 43 is a schematic diagram showing the positional relationship between two radio stations A2 and B2 and the receiving station 12.
- FIG. 44 is a diagram showing the relationship between the path length difference ⁇ and the distance X between the receiving station 12 and the wireless station.
- FIG. 45 is a diagram showing signal timing when the receiving station 12 is located in the complex area ⁇ .
- FIG. 46 is a diagram showing a configuration of a wireless transmission system when the receiving station 12 is located in the complex area B.
- FIG. 47 is a diagram showing signal timing when the receiving station 12 is located in the composite area B.
- FIG. 48 is a diagram showing a configuration of a wireless transmission system according to a sixth embodiment of the present invention.
- FIG. 49 is a diagram showing an example of the arrangement of a composite area formed by a plurality of radio stations
- FIG. 50 is a diagram showing an example of allocation of arrival timing and symbol waveform for each radio station
- FIG. 51 is a block diagram of a conventional wireless communication system
- FIG. 52 is a schematic diagram showing phase transition of a conventional symbol waveform
- FIG. 53 is a diagram showing a configuration of a transmission signal generation circuit 700
- FIG. 54 is a schematic diagram showing the phase relationship between incoming signals A and B with a delay.
- FIG. 55 is a schematic diagram showing a configuration of a conventional wireless transmission system.
- FIG. 56 is a schematic diagram showing a case where the phase relationship of the incoming signal is opposite in the conventional modulation scheme.
- FIG. 57 is a diagram schematically showing the relationship between the bit error rate and the delay amount ⁇ by the conventional transmission method.
- FIG. 58 is a diagram showing the bit error rate characteristics with respect to the arrival time difference of two waves when using the QPSK-VP method.
- FIG. 59 is a diagram showing the bit error rate characteristics when the received waves in the QPSK-VP system are 2 and 3 waves.
- FIG. 60 is a diagram illustrating the time relationship between the two waves and the three waves in FIG. 59.
- FIG. 1 is a diagram showing a configuration of a wireless transmission system according to the first embodiment of the present invention.
- the wireless transmission system shown in FIG. 1 includes a plurality of wireless stations 11 and receiving stations 12.
- the plurality of radio stations 11 and the receiving station 12 are connected by radio.
- the number of power radio stations which shows an example of the number of radio stations 11, can be arbitrarily set.
- these four radio stations 11 will be referred to as radio stations A to D, respectively, if they need to be distinguished, and will be referred to as radio stations 11 if they need not be distinguished.
- Each radio station 11 holds transmission data for transmission to the receiving station 12 and a reference timing signal indicating a reference timing for transmitting the transmission data (hereinafter referred to as reference timing). Yes.
- the transmission data and the reference timing signal held by each radio station 11 are common to all radio stations 11.
- Radio stations A to D hold delay amounts tA to tD, respectively.
- the delay amounts tA to tD take one of delay amount candidate values (for example, T1 or T2).
- the radio stations A to D generate a transmission signal based on any one of the symbol waveform candidate waveforms (for example, W1 or W2), and give the delay amount tA to tD to the reference timing indicated by the reference timing signal.
- Send data for example, T1 or T2
- the receiving station 12 receives the four signals transmitted from the radio stations A to D.
- FIG. 2 is a block diagram showing a detailed configuration example of the radio station 11 shown in FIG.
- FIG. 3 is a block diagram showing a detailed configuration example of the modulation unit 21 shown in FIG.
- the radio station 11 includes a modulation unit 21, a data holding unit 22, a transmission timing control unit 23, an RF unit 24, an antenna 25, and a waveform selection control unit 26.
- the modulation unit 21 includes a read control unit 41, a waveform storage unit 42, and a DZA conversion unit 43.
- the RF unit 24 and the antenna 25 form a transmission unit.
- the transmission timing control unit 23 controls the transmission timing of a signal to be transmitted to the receiving station 12 based on the reference timing signal and a predetermined delay amount. Specifically, the transmission timing control unit 23 delays the reference timing force delay amount indicated by the reference timing signal. This timing is set as the transmission start timing. Then, at the transmission start timing, the transmission timing control unit 23 generates a transmission start signal for instructing the start of transmission and passes it to the modulation unit 21.
- the modulation unit 21 requests transmission data from the data holding unit 22, and performs predetermined modulation on the transmission data acquired in response to the request.
- the data holding unit 22 reads transmission data held in advance and passes it to the modulation unit 21 in response to a request from the modulation unit 21.
- the RF unit 24 converts the frequency of the signal modulated by the modulation unit 21 into an RF band signal and transmits it from the antenna 25.
- the waveform selection control unit 26 generates a waveform bank selection signal for reading out the corresponding symbol waveform from the waveform table card based on the waveform selection signal, and passes it to the modulation unit 21.
- the read control unit 41 is configured by a counter that operates with a base clock, and when receiving a transmission start signal, based on the counter value, a data read clock for reading transmission data and symbol waveform data And an address signal for reading from the waveform memory.
- the data read clock is output to the data holding unit 22, and the address signal is output to the waveform storage unit 42.
- the data holding unit 22 passes the transmission data in the differential encoding format to the read control unit 41 in synchronization with the data read clock.
- the waveform storage unit 42 reads the symbol waveform data corresponding to the transmission data from the waveform memory based on the address signal.
- the DZA conversion unit 43 converts the digital data read by the waveform storage unit 42 into an analog signal and outputs it as a modulated baseband signal.
- the timing at which the modulated baseband signal is output changes in units of base clocks according to the timing at which the transmission start signal is received.
- the base clock is often used at a frequency several times the symbol frequency (reciprocal of the symbol length), such as several times. Therefore, the timing at which the modulated baseband signal is output can be adjusted in units of a fraction of the symbol length to a tenth of the symbol length.
- FIG. 4 is a diagram illustrating an example of a differential code rule and a signal space diagram of the wireless transmission system according to the first embodiment of the present invention.
- FIG. 5 is a diagram illustrating an internal configuration example of each block of the modulation unit 21 illustrated in FIG.
- the modulation unit 21 stores a predetermined symbol waveform, and a differential code Baseband modulation signals 122 and 123 corresponding to the digitized signal 121 are output.
- the input bit sequence is converted into a symbol format by serial-parallel conversion with respect to the input transmission data, and differential encoding is performed, so that the in-phase signal I and quadrature of each symbol are converted.
- An axis signal Q (differential encoded signal 121) is obtained.
- D differential amplitude phase modulation
- APSK differential amplitude phase modulation
- the present invention will be described by taking as an example the case of performing differential encoding with four phases (asymmetrical arrangement).
- the in-phase signal I and the quadrature axis signal Q of the k-th symbol are converted to the kk symbol that is M symbols before (M is an integer of 1 or more).
- Ask. ⁇ ⁇ is the amount of phase rotation.
- phase rotation amount ⁇ ⁇ of a set of two consecutive bits (symbol format) of the transmission data (k) and X (k) is determined.
- the modulation unit 21 includes a base clock oscillator 1801, an L frequency divider 1802, an L counter 1803, an M counter 1804, a shift control unit 1805 and 1806, a read control unit 41, and a waveform storage Unit 42, DZA converters 1808 and 1809, and DZA converter 43 comprising low-pass filters 1810 and 1811.
- FIG. 6 shows various examples of the phase transition of the symbol waveform, which is the basis of the baseband modulated signals 122 and 123 generated by the modulation unit 21.
- a symbol waveform condition Is that the second derivative of the change is not always zero “0” in the symbol.
- the symbol waveform used by the modulation / demodulation unit of a different radio station has, for example, a phase transition in which the first symbol waveform is indicated by a solid line and the second symbol waveform is indicated by a dotted line in FIG. If it is a combination of different changes as in the case of having a phase transition, a unique diversity effect described later appears. Note that (a) to (e) in FIG.
- phase transitions 6 are merely examples of phase transitions, and other phase transitions may be used as long as the above conditions are satisfied. In addition, it is not always necessary that the phase transition of the first symbol waveform and the phase transition of the second symbol are symmetrical. In FIG. 6 (a) to (e), all combinations of solid lines and dotted lines, Or even a dotted line.
- the symbol waveform a maximum of M types of symbol waveforms can be periodically used for the transmission signal of one radio station.
- the symbol waveforms used for symbols corresponding to the same transmission data of different radio stations must be different from each other.
- Phase transition ⁇ A (t) of the m-th (l ⁇ m ⁇ M) symbol waveform of the baseband modulation signal generated by the modulation unit 21 of the first radio station is different from the first radio station
- the phase transition ⁇ ⁇ (t) of the mth symbol waveform of the baseband modulated signal generated by the modulation unit 21 of the second radio station is within the symbol at the symbol length T (0 ⁇ t ⁇ T).
- phase ⁇ (t) representing the transmission data through the differential encoding is expressed as follows, assuming that the phase of the signal point in FIG. 4 (b) is ⁇ for the qth symbol (q is an integer). Using function U (t)
- Phase transition [Phi (t) is defined only in the 0 ⁇ t ⁇ T, when the 0 in other intervals, the phase transition [psi Alpha omega of baseband modulation signal is represented by the following formula (6) .
- the baseband modulation signal from the phase transition [psi Alpha omega, phase modulated signal Y A (t) and straight
- the intermodulation signal Y A (t) is expressed by the following equation (7).
- a modulated signal in the RF band is obtained by orthogonally modulating a carrier wave with these signals. can get.
- the band since the signal becomes a wide band as it is, the band may be limited by a band limiting filter.
- the impulse response of the band limiting filter is h (t)
- the in-phase modulated signal Y A (t) and the quadrature modulated signal Y A (t) after band limitation are not the above formula (7) but the following formula:
- phase transition of the baseband modulated signal ⁇ B ( t) is expressed by the following formula (9).
- the in-phase modulation signal Y A (t) and the quadrature modulation signal Y A (t) are expressed by the following equation (10).
- the band limiting filter can use various characteristics (cosine roll-off, root Nyquist, Gauss, etc.) and parameters (cut-off, roll-off rate, etc.) as long as it is a low-pass filter.
- cut-off angular frequency ⁇ and the roll The impulse response h (t) of the cosine roll-off filter with the off coefficient ⁇ is shown in the following equation (11).
- the waveform storage unit 42 stores the in-phase modulation signal Y A (t) and the quadrature modulation according to the above equation (8).
- the adjustment signal Y A (t) is stored.
- the modulation unit 21 shown in FIG. 1 the modulation unit 21 shown in FIG.
- the waveform storage unit 42 stores all of the transmission data patterns for the current and previous and subsequent symbols, and stores the pieces of modulated signals.
- the input differential encoded signal 121 is delayed by the shift register 1805 or 1806, and includes the k 1st symbol and the k + 1th symbol before and after the kth symbol as a selection signal for a modulation signal element. Input to the waveform storage unit 42.
- the base clock oscillator 1801 oscillates a clock signal having a symbol frequency Fs and is input to each shift register 1805 or 1806 as an operation clock.
- the M counter 1804 operates at the symbol frequency Fs, and inputs M waveform selection signals 1823 to the waveform storage unit 42.
- the waveform storage unit 42 can select a plurality of symbol waveforms with M symbols as one period.
- the waveform storage unit 42 is a memory that stores a waveform table of modulation signal segments for each symbol. Each modulation signal segment is stored in L samples per symbol.
- the clock of frequency L'Fs output from L divider 1802 is used as a read clock, and the signal points in the symbol are sequentially read and operated using counter signal 1822 as a read address.
- the modulated signals of both axes are converted into analog values by DZA converters 1808 and 1809, respectively, the aliasing components are removed by low-pass filters 1810 and 1811, and output as baseband modulated signals 122 and 123.
- the modulator 21 of the second radio station also has the same configuration operation although the stored waveforms are different.
- the shift registers 1805 and 1806 are unnecessary, and the differentially encoded signal 121 is directly input to the waveform storage unit 42. Ru .
- FIG. 7 is a block diagram showing a detailed configuration example of the receiving station 12 shown in FIG.
- the receiving station 12 includes an antenna 31, an RF unit 32, and a demodulation unit 33.
- the RF unit 24 and the antenna 25 form a receiving unit.
- the RF unit 32 converts the received signal in the RF band received by the antenna 31 into a received baseband signal.
- the demodulator 33 demodulates the received baseband signal converted by the RF unit 32 to obtain received data.
- FIG. 8 is a block diagram showing a detailed configuration example of the demodulator 33 shown in FIG.
- the demodulating unit 33 includes an M simponole delay unit 1601, multipliers 1602 and 1603, a 45-degree shifter 1604, a + 45-degree phase shifter 1605, and low-pass filters 1606 and 1607.
- the M symbol delay unit 1601 delays the received signal by M symbol length.
- the low-pass filters 1606 and 1607 also serve to synthesize a plurality of detection outputs, which will be described later, in addition to removing frequency components twice the carrier wave generated by the multipliers 1602 and 1603.
- the demodulating unit 33 may be a unit that directly receives and processes a power RF band received signal for processing the received signal 131 converted into the baseband band by the RF unit 32 in the preceding stage.
- the two radio stations A and B shown in FIG. 1 are based on the first symbol waveform (or M-length symbol waveform sequence) W1 and the second symbol waveform (or M-length symbol waveform sequence) W2, respectively.
- An example will be described in which transmission signals are generated and transmitted, and the receiving station 12 receives these transmission signals.
- the signals transmitted from radio stations A and B each generate multi-nos (multi-path propagation) in the propagation path, but the relative delay between these multi-path waves becomes the symbol length. On the other hand, it can be ignored. This corresponds to the case where the incoming signal A from the wireless station A and the incoming signal B from the wireless station B have independent Rayleigh fluctuations, etc., and this is the case where the propagation path frequency characteristics are uniform within the transmission band. This is called flat fading.
- the phase difference a is a parameter that also depends on the distance relationship between the radio stations A and B and the receiving station 12.
- FIG. 9 is a schematic diagram showing the phases of the incoming signals A and B at the receiving station 12 for each symbol.
- FIG. 9 shows the phases of the k-M symbol, the k-M + 1 symbol, the k-th symbol, and the k + 1 symbol. Note that the phase of the signal point according to the transmission data is ⁇ and the radio station A k
- the incoming signal A is a symbol k at a constant phase ⁇ starting from the k-th symbol.
- the phase transition ⁇ ⁇ (t) of the Bol waveform is added.
- the incoming signal B has a symbol wave k starting from the composite phase of the phase ⁇ of the signal point in the kth symbol and the phase relationship a between the incoming signals.
- phase transition ⁇ ⁇ (t) of the shape is added. M to the kth M symbol before M symbols before the kth symbol
- the demodulation unit 33 performs delay detection with the k-th symbol and the k-M symbol.
- FIG. 10 is a phase transition diagram schematically showing the phase relationship between incoming signal A and incoming signal B and the phase relationship between symbols.
- the symbol waveforms of transmission signal A (arrival signal A) and transmission signal B (arrival signal B) undergo a phase transition as shown in FIG.
- the phase of the incoming signal A at the k-Mth symbol changes as the phase transition al
- the phase of the incoming signal B has a phase value shifted by the phase difference ⁇ with respect to the origin of the phase transition al. It changes like the phase transition bl at the starting point.
- the phase of the incoming signal A changes from the starting point of the phase transition al of the kth Mth symbol by the phase value ⁇ by the differential sign ⁇ as the starting point of phase transition a2.
- phase transition b 2 The phase changes as the phase transition b 2 starting from the phase value shifted by the phase difference ⁇ with respect to the starting point of the phase transition a2. Therefore, the relationship between the phase transitions al and bl of the k-M symbol and the phase transitions a2 and b2 of the k-th symbol is as follows:
- phase relationship between the incoming signal A and the incoming signal B will be described with reference to a vector diagram.
- the signal level of incoming signal A is 1, and the signal level of incoming signal B is And the phase difference between the incoming signals is ⁇ .
- the phase is different from the vector S of the incoming signal A by ⁇ .
- the incoming signal ⁇ is the vector S
- phase changes according to ⁇ ⁇ (t) with time starting from, and the vector at any time t
- the incoming signal B starts with the vector S and changes with time according to ⁇ ⁇ (t).
- the wave vector is V.
- the vector S of the incoming signal A is ⁇ 0 with respect to the vector S.
- phase difference ⁇ 0 between the detection target symbols is ⁇ k k
- the vector S of the incoming signal B has a phase that is
- phase of incoming signal A changes with time from ⁇ ⁇ (t) starting from vector S
- D (t) is expressed as in the following formula (15).
- the phase difference ⁇ ⁇ (t) ⁇ ⁇ (t) of the two symbol waveforms changes in the time interval 0 ⁇ t ⁇ T, it will never be zero for any p, a, and the incoming signal A
- the detection output combined with the incoming signal B does not completely disappear, meaning that a diversity effect can be obtained.
- the power that can provide a higher path diversity effect preferably 2 or more than A (t) ⁇ ⁇ (t) -a)
- each symbol waveform (or each of M-length symbol waveform series) stored in the modulation unit 21 of the wireless station A and the modulation unit 21 of the wireless station B is stored.
- Corresponding symbol waveforms) are, for example, phase transitions ⁇ ⁇ and ⁇ ⁇ ⁇ shown in (a) of Fig. 6 in which the direction of increase / decrease of phase transitions is different in the same time domain. As a result, a high path diversity effect can be obtained on the receiving side.
- FIG. 13 is a schematic diagram showing the phase relationship between incoming signals A and B received by the receiving station 12 when the delay dispersion of the propagation path can be ignored.
- the anti-phase point where the phase is reversed is indicated by X
- the in-phase point where the phase is in phase is indicated by ⁇ .
- a two-wave arrival model in which the arrival signals from two radio stations A and B are each two waves as shown in Fig. 15 is considered.
- FIG. 16A is a schematic diagram showing the change in phase of the direct wave and the delayed wave of transmission signal A for each symbol.
- the phase difference at the receiving point between the carrier waves of the direct wave and the delayed wave is assumed to be 13.
- the phase of the delayed wave is the signal corresponding to the transmission data in the kth symbol.
- ⁇ is applied to the direct wave by k A
- phase transition ⁇ A (t- ⁇ ) of the symbol waveform of the delayed transmission signal A is added.
- the phase of the delayed wave is the k-th symbol kM from the phase ⁇ of the signal point for the k-th symbol.
- the correct detection polarity is obtained and corrected, and the effective interval in which the demodulated data is obtained is the region (ii) or the kth symbol. This is the region GO ′ in the kth-Mth symbol.
- the regions before and after (0, GiO, (0 'and (m)') data signals with different adjacent symbols are mixed, so intersymbol interference occurs, and correct demodulated data cannot always be obtained! /, It is an area.
- FIG. 16B is a schematic diagram showing the change in phase of the direct wave and the delayed wave of transmission signal B for each symbol.
- transmission signal B in the above description, the phase difference at the receiving point of each of the direct wave and the delayed wave is expressed as follows.
- FIG. 17 is a diagram showing the phase relationship at the reception point of each carrier wave for the direct wave and the delayed wave of the transmission signals ⁇ and ⁇ .
- direct transmission signal A In addition to the above j8 and j8, direct transmission signal A
- the phase difference between the carrier waves and the direct wave of the transmission signal B is ⁇ ′.
- the amplitude of the delayed wave for each direct wave of transmitted signals ⁇ and ⁇ is ⁇ and p. Vibration between direct waves
- FIG. 18A is a phase transition diagram schematically showing the phase relationship between the direct wave and the delayed wave of transmission signal A and the positional correlation between symbols.
- ⁇ A shown in (a) of Fig. 6 is used as the symbol waveform of transmission signal A is shown.
- the phase of the direct wave in the k-M symbols changes as shown by phase transition al, and the phase of the delayed wave starts from the phase value shifted by j8 with respect to the origin of phase transition al. Transition Transition as cl.
- the phase of the direct wave is from the origin of the phase transition al of the kth M symbol. Transition from the phase value shifted by ⁇ ⁇ by differential encoding as the phase transition a2
- phase of the delayed wave starts at a phase value shifted by 13 relative to the origin of phase transition a2.
- phase transition diagram schematically showing the phase relationship between the direct wave and delayed wave of signal B and the phase relationship between symbols.
- FIG. 19A is a schematic diagram showing the phase transition of the direct wave and the delayed wave of transmission signal A as a vector.
- Fig. 19A shows transmission data, and the phase difference ⁇ between two symbols separated by M symbols to be detected is taken as an example.
- the signal point of the k-M symbol is shown as S
- the phase of the delayed wave vector S differs from that of the direct wave vector S by ⁇ .
- the direct wave has a phase that depends on ⁇ ⁇ (t) with time starting from vector S.
- m lAd is represented.
- the vector of the received wave at time t is v A.
- phase of the direct wave changes with time from ⁇ ⁇ (t) with vector S as the starting point.
- ⁇ ⁇ (t- ⁇ ) changes in phase and is represented by a vector S at a certain time t.
- the received wave vector at time t is v A.
- FIG. 19B is a schematic diagram showing the phase transition between the direct wave and the delayed wave of the transmission signal B as a vector. Again, only the valid interval GO or GO ′ in FIG. 16B is considered.
- FIG. 19B also shows transmission data, and shows an example in which the phase difference ⁇ ⁇ between symbols separated by M symbols to be detected is ⁇ .
- the phase is different by IB lBd B.
- the direct wave has a phase that depends on ⁇ ⁇ (t) with time starting from vector S.
- phase changes according to ⁇ ⁇ (t- ⁇ ) with time from the start point of lBd.
- the direct wave vector S is ⁇ 0 relative to the vector S.
- the delay wave vector S is different from the vector S by 2B IB k.
- phase of the direct wave changes with time from ⁇ ⁇ (t) with vector S as the starting point.
- the received wave vector at time t is V B.
- the delayed wave, the k-th symbol and the k-th symbol have the same phase transition within the symbol, so the phase relationship between the two received wave vectors V B and V B is also arbitrary.
- the wave output is calculated as two antennas V A and V B (or V A and V B ) cancel each other, or two antennas.
- the correct polarity output corresponding to the transmission data can always be obtained.
- Means In other words, as explained in Fig. 13 and Fig. 14, even if it may be zero for a moment, it will not become zero otherwise!
- the detection output is obtained, and further by passing through the low pass filter, Even if the part becomes zero and missing, a detection output that combines the effective outputs obtained at multiple time positions within the effective interval in the symbol is obtained, and the path diversity effect is exhibited.
- the same transmission data is differentially encoded and each has a different symbol waveform.
- the signal is modulated and transmitted, and is detected by delay detection at the receiving station 12.
- delay detection at the receiving station 12.
- the force depends on specific modulation parameters such as bandwidth limitation, etc., and the same conditions, the maximum number of valid branches can be increased as the allowable delay range increases by changing the symbol waveform. To increase.
- FIG. 21 is a diagram schematically showing the relationship between the bit error rate and the delay amount according to the transmission method of the present invention, as in FIG.
- T symbol length
- the effective interval becomes shorter and eventually disappears and the error rate deteriorates, but the error rate improves even when the amount of delay is near zero. The place is different. Therefore, in the transmission method of the present invention, as in Patent Document 1, it is not always necessary to insert an intentional predetermined delay between incoming signals. Rather, even if the arrival timing is the same, a unique diversity effect is obtained. can get
- the relationship between the timings T1 and ⁇ 2 and the allowable delay (good error rate interval) is preferably set as shown in FIG.
- Tl- ⁇ 2, 0 ( ⁇ 1-Tl or ⁇ 2- ⁇ 2) and T2-T1 are generated, but these must be within the allowable delay.
- the arrival time differences are T1-T2 and T2-T1
- the same symbol waveform produces the path diversity effect (see Fig. 57), but when the arrival time difference is 0, the signals using different symbol waveforms are used. There is a need.
- the maximum number of effective branches increased by using different symbol waveforms is four, and the combination of symbol waveform and arrival timing needs to be selected from four types: W1T1, W1T2, W2T1, and W2T2. .
- the maximum number of valid branches in this case, 4
- each radio station needs to transmit using a different set of these 4 sets. is there.
- no combination other than these four groups is created, and four of the radio stations are different from each other in the four groups. The remaining radio stations need to select one of these four sets for transmission.
- FIG. 22 is a flowchart showing the operation of the wireless station 11 in the wireless transmission system configured by making full use of the above-described unique path diversity effect.
- the data holding unit 22 stores transmission data (step S501).
- the transmission timing control unit 23 determines the timing at which the reference timing force is also delayed by a predetermined delay amount as the transmission start timing (step S502). Then, the transmission timing control unit 23 generates a transmission start signal and sends it to the modulation unit 21 when the transmission start timing comes (step S503, Yes).
- the modulation unit 21 modulates transmission data with the symbol waveform indicated by the waveform selection signal according to the transmission start signal, and outputs the modulated transmission data.
- the modulated transmission data is transmitted to the receiving station 12 via the RF unit 24 and the antenna 25 (step S504).
- FIG. 23 is a diagram illustrating timings at which the radio stations A to D transmit signals.
- the delay amounts tA to tD held by the radio stations A to D are T1 or T2.
- the four radio stations A to D are at the timing when the delay amount T1 or T2 is given to the reference timing TO, that is, at any timing of (Tl + TO) or (T2 + T0).
- wireless stations A and D transmit with symbol waveform W1, and wireless station B transmits with symbol waveform W2.
- the propagation times aA to aD between the radio stations A to D and the receiving station 12 are assumed to be negligibly small or all the same G.
- the receiving station 12 receives signals transmitted from the radio stations A to D at two timings of timing (T1 + G + TO) and timing (T2 + G + T0). These two timings have a time difference of (T2 ⁇ T1). Therefore, there is a certain time difference between the arrival of signals between radio station A and radio station D, and between radio station B and radio station C. Therefore, the effect of path diversity is demonstrated. Transmission characteristics can be improved. However, the symbol waveforms are different between the wireless station A and the wireless station C, and between the wireless station B and the wireless station D when the arrival of the signal is the same time, so that a path diversity effect can be generated. it can. In the end, the entire wireless transmission system can achieve a 4-pass diversity effect equal to the maximum number of effective branches increased by using different symbol waveforms.
- the wireless transmission system has a wireless station (for example, wireless station E) exceeding the maximum number of effective branches, the arrival timing is either (T1 + G + TO) force (T2 + G + T0).
- the wireless station E is set to transmit data (the symbol waveforms overlap, either W1 or W2 may be used), the characteristics can be maximized.
- the number of radio stations is equal to or greater than the maximum number of effective branches that can be used by the receiving station, it contributes to the effect of path diversity.
- the effect of path diversity can be maximized.
- the four radio stations A to D hold either the delay amount T1 or T2 in advance.
- each of the radio stations A to D may hold both the delay amounts T1 and T2.
- the selected delay amount may always be the same or random.
- the reference timing signal shared by each of the radio stations A to D may be a timing based on a beacon signal received by a station other than the radio station (for example, a master station or a transmitting station), or a GPS (Global Positioning System) signal time information and radio clock Even if it is time timing that power can be obtained.
- a desired delay is added to the transmission timing of each radio station by using a timing obtained by delaying the reference timing by a predetermined delay amount.
- the method of adding is not limited to this.
- a delay may be added to the modulation baseband signal output from the modulation unit.
- FIG. 24 is a block diagram showing a configuration of the radio station 20 when a delay is given to the modulation baseband signal output from the modulation unit.
- the radio station 20 has a configuration obtained by removing the transmission timing control unit 23 and the waveform selection control unit 26 from the radio station 11 shown in FIG.
- FIG. 25 is a block diagram showing a configuration of the modulation unit 21c shown in FIG. This modulation unit 21c is different from the modulation unit 21 shown in FIG. 3 in that it further includes a delay addition unit 44.
- the delay adding unit 44 includes a shift register, delays the input signal by a predetermined delay amount, and outputs the delayed input signal to the DZA conversion unit 43. As a result, the signal obtained from the waveform storage unit 42 can be delayed by a predetermined delay amount.
- the delay adding unit 44 may be provided after the DZA conversion unit 43 to perform the delay process on the analog signal.
- a delay adding unit 44 may be provided between the read control unit 41 and the waveform storage unit 42 to delay the address signal according to a predetermined delay amount (FIG. 26).
- a predetermined delay can be added to the modulated baseband signal.
- the method is not limited to the example described above as long as a plurality of radio stations transmit data with a predetermined delay amount added from the reference timing.
- FIG. 27 is a diagram showing a configuration of a wireless transmission system according to the second embodiment of the present invention.
- the wireless transmission system shown in FIG. 27 includes a transmitting station 13, a plurality of wireless stations 14, and a receiving station 12.
- the transmitting station 13 and the plurality of radio stations 14 and the plurality of radio stations 14 and the receiving station 12 are wirelessly connected.
- the wireless transmission system according to the second embodiment further includes a transmitting station 13 that transmits a signal to be transmitted to the receiving station 12 to a plurality of wireless stations 14, and the wireless transmission system according to the first embodiment. Is different. Below, focusing on this difference A second embodiment will be described.
- the configuration of the transmitting station 13 is a configuration in which the transmission timing control unit 23 and the waveform selection control unit 26 are excluded from the configuration of the wireless station 11 shown in FIG.
- the configuration of the receiving station 12 is the same as that shown in FIG. FIG. 27 shows an example in which the number of radio stations 14 is four.
- these four radio stations 14 will be referred to as radio stations A1 to D1, respectively, if they need to be distinguished, and will be referred to as radio stations 14 if they need not be distinguished.
- FIG. 28 is a diagram showing a configuration of a frame used for transmission signals of the transmission station 13 and the radio station 14.
- a frame includes a preamble (hereinafter referred to as PR), a unique mode (hereinafter referred to as UW), and information data.
- PR is used for gain control, symbol synchronization, and frequency synchronization.
- UW is used for frame synchronization when determining the frame type.
- the information data includes data to be transmitted by the transmission side.
- FIG. 29 is a block diagram showing a detailed configuration example of the radio station 14 shown in FIG. 29 further includes a demodulation unit 29, a UW detection unit 27, a delay amount setting unit 28, and a waveform setting unit 30 in the configuration of the wireless station 11 according to the first embodiment shown in FIG. It is a configuration.
- the signal transmitted from the transmitting station 13 is received by the antenna 25 of the radio station 14, frequency-converted by the RF unit 24, and then input to the demodulating unit 29.
- the demodulator 29 demodulates the input signal to obtain transmission data.
- the UW detection unit 27 When detecting the UW included in the transmission data output from the demodulation unit 29, the UW detection unit 27 generates a UW detection signal and passes it to the transmission timing control unit 23.
- the delay amount setting unit 28 selects one from a plurality of candidate delay amount values (T1 and T2 in this example) and passes the selected value to the transmission timing control unit 23. Note that the delay amount to be selected is preset for each wireless station.
- the waveform setting unit 30 selects one from a plurality of symbol waveform (or M-length symbol waveform series) candidates (in this example, W1 and W2) and passes them to the modulation unit 21.
- the symbol waveform to be selected is preset for each radio station.
- the transmission timing control unit 23 uses the timing at which the UW detection signal is received as the reference timing. Note that the reference timing may be the timing at which a predetermined time elapses after receiving the UW detection signal. Based on the reference timing and the delay amount set by the delay amount setting unit 28, the transmission timing control unit 23 determines the transmission timing of the modulated signal in the same manner as in the first embodiment.
- FIG. 30 is a flowchart showing the operation of the radio station 14 configured as described above.
- the demodulation unit 29 demodulates the signal output from the RF unit 24 and generates demodulated data.
- the data holding unit 22 stores the demodulated data as transmission data (step S602).
- the UW detection unit 27 detects UW from this demodulated data cover, generates a UW detection signal, and passes it to the transmission timing control unit 23.
- the transmission timing control unit 23 uses the timing at which the UW detection signal is received as the reference timing (step S603), and determines the transmission start timing based on the reference timing and the delay amount (step S604). Then, the transmission timing control unit 23 passes the transmission start signal to the modulation unit 21 when the transmission start timing comes (step S605, Yes).
- the modulation unit 21 modulates the transmission data with the symbol waveform indicated by the waveform bank selection signal according to the transmission start signal.
- the modulated transmission data is transmitted to the receiving station 12 via the RF unit 24 and the antenna 25 (step S606).
- FIG. 31 is a diagram illustrating timings at which the radio stations A1 to D1 transmit signals A1 to D1.
- the transmitting station 13 transmits signals to the surrounding radio stations A1 to D1 at a predetermined timing Ts.
- the timing at which the wireless stations A1 to D1 receive the signal from the transmitting station 13 is
- Radio station 8 1 Ding 5 + & 1 8
- Radio station Bl Ts + alB
- the propagation times alA to alD between the transmitting station 13 and the wireless stations A1 to D1 are so small that they can be ignored or all the same.
- the propagation time alA to alD is combined with the time until the UW detection signal is output at the radio stations A1 to D1, and is set as G1. Therefore, the timing at which the UW detection signal is generated is equal to the timing (Ts + Gl) in the radio stations A1 to D1.
- the radio stations A1 to D1 use the UW detection timing (Ts + Gl) indicated by the UW detection signal as the reference timing tO. Then, the radio stations A1 to D1 transmit a signal with delay amounts tA to tD with respect to the reference timing tO. For example, the wireless station A1 receives the reference timing tO to t Send signal after A time.
- the delay amounts tA to tD are selected from the delay amount candidate values T1 or T2 as in the first embodiment.
- Radio stations A1 to D1 transmit signals at either timing (Tl + Gl + Ts) or timing (T2 + G1 + TS).
- the radio station A1 and the radio station D1 transmit signals with the symbol waveform W1
- the radio station B1 and the radio station C1 transmit signals with the symbol waveform W2.
- the receiving station 12 receives signals A1 to D1 transmitted from the radio stations A1 to D1.
- the propagation times a2A to a2D between the radio stations A1 to D1 and the receiving station 12 are assumed to be negligibly small or all the same, and this is set as G2. Therefore, the timing at which the receiving station 12 receives the signals A1 to D1 is the timing (Tl + G2 + G1 + Ts) and the timing (T2 + G2 + G1 + Ts).
- the two timings have a time difference of (T2 ⁇ T1). Therefore, the same symbol waveform has a certain force.
- the effect of path diversity is exhibited.
- transmission characteristics can be improved.
- the symbol waveforms are different between the radio station A1 and the radio station C1 and between the radio station B1 and the radio station D1 when the signals arrive at the same time, a path diversity effect can be generated.
- the entire wireless transmission system can achieve a 4-pass diversity effect equal to the maximum number of effective branches increased by using different symbol waveforms.
- the wireless station when a signal transmitted from a transmitting station is transmitted to a receiving station via a plurality of wireless stations, the wireless station performs predetermined processing. The amount of delay is given. As a result, the number of sets of reception timing and symbol waveforms at which the receiving station receives the incoming wave can be made equal to the maximum number of effective branches increased by using different symbol waveforms.
- the radio station uses the timing when the UW is detected as a reference timing. Suppose This eliminates the need to hold the reference timing signal in advance.
- the UW detection signal is used as the reference timing signal.
- the timing signal that has completed reception of the frame is used. Etc. may be used.
- a CRC Cyclic Redundancy Check
- a determination output signal based on this code may be used. According to this, when the signal of the transmitting station power is determined to be a reception error in the radio station, it is possible to prevent the signal from being transmitted to the receiving station. Only signals can be received.
- FIG. 32 is a diagram showing a configuration of a wireless transmission system according to the third embodiment of the present invention.
- the radio transmission system according to the third embodiment includes a configuration of the radio station 14 (radio stations A1 to D1) and the reception station 12, a frame configuration of signals transmitted from the transmission station 15 and the radio station 14, and the radio station 14 and
- the operation of the receiving station 12 is the same as in the second embodiment, but differs from the second embodiment in that the transmission data held by the transmitting station 15 is transmitted twice.
- the third embodiment will be described with a focus on the different portions.
- the transmitting station 15 performs the first signal transmission toward the radio station 14 and performs the second signal transmission toward the receiving station 12.
- the transmitting station 15 has a signal so that the timing at which the second transmission signal reaches the receiving station 12 is equal to the timing at which the transmitted signal from the radio station 14 that has shifted to the receiving station 12 reaches V. Is transmitted with a predetermined delay amount.
- FIG. 33 is a block diagram showing a detailed configuration example of the transmitting station 15 shown in FIG.
- the transmission station 15 includes a transmission timing control unit 151, a modulation unit 21, an RF unit 24, an antenna 25, a delay amount setting unit 28, a data holding unit 22, and a waveform setting unit 30.
- the configuration other than the transmission timing control unit 151 is the same as the configuration shown in FIG. 24 or FIG.
- the transmission timing control unit 151 controls the timing of the second signal transmission (retransmission) after performing the first signal transmission as in the second embodiment.
- the transmission timing control unit 151 determines the retransmission start timing based on the reference timing indicated by the reference timing signal and the delay amount received from the delay amount setting unit 28. At this time, If the propagation time to / from radio station 14 is negligibly small, add only the delay amount to the reference timing, and if the propagation time is large, add the delay amount and propagation time to the reference timing.
- the retransmission start timing may be determined. Then, the transmission timing control unit 151 generates a retransmission start signal and passes it to the modulation unit 21 at the retransmission start timing.
- FIG. 34 is a flowchart showing the operation of the transmitting station 15 configured as described above.
- the transmitting station 15 modulates data and transmits it to the wireless station 14 (step S701).
- the transmission timing control unit 151 determines a retransmission start timing based on the reference timing and the delay amount (step S702).
- the transmission timing control unit 151 generates a retransmission start signal and passes it to the modulation unit 21 when the retransmission start timing comes (step S703).
- the modulation unit 21 modulates transmission data with the symbol waveform indicated by the waveform bank selection signal according to the retransmission start signal.
- the modulated transmission data is transmitted to the receiving station 12 via the RF unit 24 and the antenna 25 (step S704).
- FIG. 35 is a diagram illustrating timings at which the transmitting station 15 and the wireless stations A1 to D1 transmit signals.
- FIG. 35 shows the timing of the signal transmitted by the transmitting station 15 in addition to the timing of the modulated signal transmitted by the radio stations A1 to D1 shown in FIG.
- the timing at which the radio stations A1 to D1 receive the signal from the transmitting station 15 by the first transmission is as follows as described above.
- Radio station 8 1 Ding 5 + & 1 8
- Radio station Bl Ts + alB
- the transmitting station 15 gives the delay amount tO selected from the delay amount candidate values T1 or T2, and performs the second transmission.
- the symbol waveform used by the transmitting station 15 may be either W1 or W2. The conditions for maximizing the characteristics when there are many radio stations are as described above.
- the receiving station 12 receives signals transmitted from the radio station 14 and the transmitting station 15.
- timings at which the receiving station 12 receives these five signals There are two timings at which the receiving station 12 receives these five signals: timing (Tl + G2 + Gl + Ts) and timing (T2 + G2 + Gl + Ts). These two timings have a time difference of (T2 – T1). Therefore, there is a certain force in the same symbol waveform. There is an appropriate time difference in the arrival of signals between radio station A1 and radio station D1, and between radio station B1 and radio station C1, so the effect of path diversity is demonstrated. Transmission characteristics can be improved. However, since the symbol waveforms are different between radio station A1 and radio station C1 and between radio station B1 and radio station D1 when the arrival of the signal is the same time, a path diversity effect can be generated. Is possible. After all, the wireless transmission system as a whole can achieve a 4-path diversity effect equal to the maximum number of effective branches increased by using different symbol waveforms.
- the third embodiment of the present invention after a transmitting station transmits a signal to a radio station, the same signal is transmitted to a receiving station with a predetermined delay amount. As a result, the number of signals received by the receiving station increases, so that the signal reception level can be stabilized.
- the signal transmitted by the transmitting station for the second time is equal to one of the signals transmitted from the plurality of radio stations 14 and the timing of arrival at the receiving station 12. Therefore, the effect of path diversity can be maximized by reducing the number of combinations of reception timing and symbol waveform to the maximum number of effective branches.
- the transmitting station selects the delay amount candidate value T1 or T2, but each radio station selects it.
- the amount of delay to be determined may be determined randomly for a plurality of candidate value forces.
- the reference timing tO of each radio station is not limited to time information or GPS information that can be shared between the transmission station and each radio station. It may be time timing when radio clock power is obtained.
- FIG. 37 is a diagram showing a configuration of a wireless transmission system according to the fourth embodiment of the present invention.
- the wireless transmission system includes a transmitting station 16, a plurality of wireless stations 17, and a receiving station 12.
- the transmission station 16 and the radio station 17 are connected via a wired transmission path, and the radio station 17 and the reception station 12 are connected via radio.
- a transmitting station 16 and a plurality of wireless stations 17 are connected via a wired transmission path, and the delay amount and symbol waveform used by the plurality of wireless stations 17 are transmitted to the transmitting station. 16 is different from the second embodiment in that it is controlled. In the following, the fourth embodiment will be described focusing on this different part.
- FIG. 37 shows an example in which several radio stations 17 are provided in the radio transmission system.
- radio stations A2 to D2 the four radio stations 17 will be referred to as radio stations A2 to D2, respectively, if they need to be distinguished, and will be referred to as radio stations 17 if they need not be distinguished. Since the configuration of the receiving station 12 is the same as the configuration of the receiving station according to the first embodiment, description thereof is omitted.
- Transmitting station 16 instructs the delay amount and symbol waveform (or M-length symbol waveform series) used by radio station 17.
- FIG. 38 is a block diagram illustrating a detailed configuration example of the transmitting station 16.
- the transmission station 16 includes a delay amount / symbol waveform determining unit 161 and four delay amount 'symbol waveform adding units 162A to 162D.
- the modulation unit, the RF unit, and the antenna unit described so far are omitted.
- Symbol waveform determining section 161 determines delay amounts tA to tD and symbol waveforms instructed to radio stations A2 to D2 from a plurality of candidate values (for example, T1 or T2, W1 or W2). Select and decide. The number of candidate value pairs is equal to the maximum number of effective branches increased by using different symbol waveforms allowed by the wireless transmission system (as in the previous example, the maximum number of effective branches is described as an example). Do).
- the delay amount 'symbol waveform determining unit 161 passes the determined delay amounts tA to tD and symbol waveforms wA to wD to the delay amount / symbol waveform adding units 162A to 162D, respectively. It should be noted that the delay amount / symbol waveform determining unit 161 may select which delay amount and symbol waveform to be selected in advance or at random. It is desirable that the delay amount and symbol waveform sets assigned to each radio station be evenly distributed.
- the symbol waveform attached parts 162A to 162D have delay amount information indicating the determined delay amounts tA to tD, and the determined delay amounts tA to tD, in the rear part of the framed transmission data shown in FIG. Symbol waveform information indicating symbol waveforms wA to wD is added. As described above, the transmission station 16 adds the delay amount information and the symbol waveform information to the signal to notify the radio station 17 of the symbol waveform used for the delay amount and modulation of the transmission signal.
- FIG. 39 is a block diagram illustrating a detailed configuration example of the radio station 17.
- the radio station 17 shown in FIG. 39 differs from the radio station 14 shown in FIG. 29 only in the configuration of the delay amount / symbol waveform extraction unit 129.
- the delay amount / symbol waveform extraction unit 129 extracts the demodulated data power delay amount information and passes it to the transmission timing control unit 23, and also extracts the symbol waveform information from the demodulated data column to the modulation unit 21.
- the transmission data excluding the delay amount information and the symbol waveform information is passed to the data holding unit 22.
- the transmission timing control unit 23 determines the transmission timing by adding the delay amount to the reference timing.
- FIG. 40 is a flowchart showing operations of the transmission station 16 and the radio station 17 configured as described above.
- the delay amount 'symbol waveform determining unit 161 determines the delay amounts tA to tD and the symbol waveforms wA to wD to be instructed to the radio stations A2 to D2 from among a plurality of candidate values (steps).
- Delay amount ⁇ Symbol waveform adding sections 162A to 162D add the values representing the determined delay amounts tA to tD and symbol waveforms wA to wD to the rear part of the framed transmission data, and then add the modulation section, RF section, and antenna. (Step S802).
- the demodulation unit 29 demodulates the signal output from the RF unit 24, and generates demodulated data. Is generated.
- the delay amount / symbol waveform extraction unit 129 extracts delay amount and symbol waveform information from the demodulated data (step S804).
- the transmission timing control unit 23 determines the transmission timing by adding the delay amount to the reference timing (step S805). Then, the transmission timing control unit 23 passes the transmission start signal to the modulation unit 21 when the transmission start timing comes (step S806, Yes).
- the modulation unit 21 modulates transmission data with the symbol waveform indicated by the extracted waveform bank selection signal.
- the modulated transmission data is transmitted to the receiving station 12 via the RF unit 24 and the antenna 25 (step S807).
- the transmitting station can directly control the symbol waveform used for timing and modulation of the signal transmitted by the wireless station.
- the transmitting station may transmit a signal transmitted to each wireless station with a predetermined delay amount.
- FIG. 41 is a diagram showing the timing of the signal transmitted by the wireless station in this case.
- the delay amounts tA and tC that the transmitting station 18 gives to the transmission signals of the radio stations A2 and C2 are T1
- the delay amounts tB and tD that are given to the transmission signals of the radio stations B2 and D2 are T2.
- the transmitting station 18 transmits a signal to each wireless station by giving a delay amount T1 or T2 to a predetermined timing.
- the propagation time G1 between the transmitting station 18 and each of the wireless stations A2 to D2 is used, the timing at which the wireless stations A2 and C2 receive the signal from the transmitting station 18 is (T1 + G1).
- the timing at which the radio stations B 2 and D 2 receive the signal from the transmission station 18 is (T 2 + G 1).
- the receiving station 12 can detect the timing (T1 + G1 + G2) or the timing (T2 + G1 + G2)! Therefore, signals A2 to D2 are received. As a result, the transmission characteristics can be improved by taking advantage of the path diversity.
- the delay amount used by each radio station is determined by selecting the delay amount from the candidate values.
- the amount of delay may be determined by adjusting the length of the wired transmission line to be connected.
- the case has been described in which the distances between the plurality of radio stations and the receiving station are small enough to be ignored or are all the same.
- a case will be described where the difference in distance between a plurality of radio stations and a receiving station is so large that it cannot be ignored.
- FIG. 42 is a diagram showing a configuration of a wireless transmission system according to the fifth embodiment of the present invention.
- the configurations of the transmitting station 16, the radio station 17, and the receiving station 12 are the same as those in the fourth embodiment, and thus description thereof is omitted.
- the transmitting station 16 adds delay amounts tA to the signals A2 to D2 to be transmitted to the wireless stations A2 to D2, respectively. Send with ⁇ tD.
- tA delay amounts
- tD the propagation times alA to alD of the signals A2 to D2 from the transmitting station 16 to the wireless stations A2 to D2 are all set to the same G1.
- One radio station forms one communication area, and a plurality of radio stations A2 to D2 are arranged so that the plurality of communication areas are continuous. For example, a plurality of radio stations A2 to D2 are arranged in a straight line.
- the part where multiple communication areas overlap is called the composite area
- the part where the communication areas of radio stations A2, B2, and C2 overlap is the communication between composite area A and radio stations B2, C2, and D2.
- the area where the areas overlap is called the composite area B.
- the overlapping communication areas are not limited to three, and may be two or four or more. Further, when it is necessary to distinguish the signals transmitted by the radio stations A2 to D2, they are referred to as signals A to D, respectively.
- the receiving station 12 When the receiving station 12 is located in the composite area A, the receiving station 12 receives the signals A to C.
- the receiving station 12 when the receiving station 12 is located in the composite area B, the receiving station 12 receives the signals B to D. In this way, signals from the three radio stations 17 arrive in the composite areas A and B.
- FIG. 43 is a schematic diagram showing the positional relationship between the two radio stations A 2 and B 2 and the receiving station 12.
- the height of the antenna of the receiving station 12 is Hr
- the height of the antennas of the wireless stations A2 and B2 is H t
- the distance between the wireless station A2 and the wireless station B2 is L
- the distance between the receiving station 12 and the wireless station A2 is
- the distance between the receiving station 12 and the wireless station A2 is
- the distance is X
- the path length (propagation distance) zA between the radio station A2 and the receiving station 12 and the path length zB between the radio station B2 and the receiving station 12 are expressed by the following equations (16) and (17). expressed.
- the path length difference ⁇ which is the difference between the path length zB and the path length zA, is expressed by the following equation (18).
- FIG. 44 is a diagram showing the relationship between the path length difference ⁇ and the distance X between the receiving station 12 and the radio station.
- the vertical axis represents the path length difference ⁇
- the horizontal axis represents the distance X between the receiving station 12 and the radio station 17.
- the path length difference ⁇ can be approximated to the distance between the antennas of the wireless stations 2 and 2. Therefore, regardless of the position of the receiving station 12, the path length difference ⁇ is expressed by the following equation (19) that is substantially equal to the antenna interval L.
- Radio station 2 transmits at timing tA
- radio station B2 transmits at timing tB
- radio station C2 transmits at timing tC
- radio station D2 transmits at timing tD.
- FIG. 45 is a diagram showing signal timing when the receiving station 12 is located in the composite area A.
- the receiving station 12 always receives signals from the radio stations A2 to C2 from the front to the third station.
- the propagation times of the radio stations A2 to C2 are pAA, pBA, and pCA, respectively. From the approximation of equation (20), these can be expressed by the following equation (21) regardless of the position of the receiving station 12 in the composite area A.
- the timing at which the signal from each of the radio stations A2 to C2 is received by the receiving station 12 is as follows.
- the arrival time difference ⁇ ⁇ between signal A2 and signal B2 and the arrival time difference between signal ⁇ 2 and signal C2 are expressed by the following equations (22) and (23), respectively.
- the receiving station 12 receives the signal A2 and the signal C2 at the same timing.
- tAC negative, it means that the timing is earlier than tC direction 3 ⁇ 4A.
- the receiving station 12 receives the signal B after (tAB + P) from the reception timing of the signals A and C. In other words, the receiving station 12 receives signals transmitted with three radio station powers at two timings.
- FIG. 46 is a diagram showing the configuration of the wireless transmission system when the receiving station 12 is located in the complex area B
- FIG. 47 is the signal timing when the receiving station 12 is located in the complex area B.
- the timing at which the signal from each of the radio stations B2 to D2 is received by the receiving station 12 is as follows.
- the arrival time difference between signal B2 and signal C2 is BC
- signal B2 and signal D2 arrive BD is represented by the following equations (25) and (26), respectively.
- the receiving station 12 receives the signal B and the signal D at the same timing. Accordingly, the receiving station 12 first receives the signal C, and then receives the signal B and the signal D at the same timing after (tAB + P) has elapsed. That is, the receiving station 12 receives the signals transmitted from the three radio stations at two timings.
- signals from the three radio stations 17 are always received at two timings from the front.
- the two timings are the next adjacent radio station, in this embodiment, a set of radio stations A2 and C2, and a set of radio stations B2 and D2. In this way, even if the receiving station 12 is located in any composite area, signals transmitted from adjacent radio stations can be received at different timings.
- the signal received by the receiving station is adjusted so that the timing is the timing (two here) that contributes to the effect of path diversity.
- the symbol waveforms (or M-length symbol waveform series) of radio stations that arrive at the same timing, in this case, radio station B2 and radio station D2 are different, the path diversity effect can be achieved between these two. Can be generated.
- FIG. 47 shows an example in which the radio station D2 transmits with the symbol waveform W2, and the radio stations B2 and C2 transmit with the symbol waveform W1. As a result, it is possible to obtain the maximum effect of path diversity at the receiving station.
- Fig. 50 shows an example of the allocation of each radio station for the arrival timing (T1 and T2 in this example) and symbol waveforms (W1 and W2 in this example) in this case.
- Incoming waves from neighboring radio stations are generally lower in the level of incoming waves from distant radio stations, and the arrival waves from two neighboring radio stations have a large effect on transmission characteristics.
- Figure 50 shows typical 16 types of arrangement patterns that satisfy this condition, and describe each arrangement concept in the rightmost column! / Speak.
- the sixth embodiment forms a planar area by arranging the continuous linear continuous areas shown in the fifth embodiment in the horizontal direction, and receives signals at two timings in each composite area. It is characterized by that.
- FIG. 48 is a diagram showing a configuration of a wireless transmission system according to the sixth embodiment of the present invention.
- the configurations of the transmitting station 16, the radio station 17, and the receiving station 12 are the same as those of the fifth embodiment, and thus description thereof is omitted.
- the wireless transmission system includes eight wireless stations 17.
- a set of four radio stations 17 arranged in a row is arranged, and two sets are arranged to form a planar communication area.
- the radio stations 17 included in one set are called radio stations A2 to D2 in order, and the radio stations 17 included in the other set are wirelessly connected in order.
- the composite area formed by radio stations A2 to C2 is called composite area A1
- the composite area formed by radio stations B2 to D2 is called composite area B1
- the composite area formed by radio stations B3 to D3 is combined.
- the composite area formed by area B2 and radio stations C3 to E3 is called composite area C2.
- two types of arrangement patterns are used from the arrangement patterns shown in FIG.
- arrangement pattern 1 and arrangement pattern 2 in FIG. The same pair does not exist for any four (for example, enclosed by squares with dotted lines), and all the combinations are adjacent, so that the maximum path diversity effect can be expected.
- good transmission characteristics can be obtained by the maximum path diversity effect, including the composite areas Al, Bl, B2, C2, and the center of these four composite areas. It is done.
- a set of radio stations arranged in a line is arranged in a plane, thereby achieving the effect of path diversity and a wider communication area. Can be covered.
- a signal from a radio station far from the receiving station does not cause interference with the receiving station, and can contribute to the effect of path diversity.
- 8S described as an example of 8 wireless stations constituting 4 composite areas 1S In order to further increase the number of areas, it is also possible to increase the number of wireless stations arranged side by side continuously.
- FIG. 49 is a diagram showing an example of the arrangement of composite areas formed by a plurality of radio stations.
- the arrangement pattern 1 and the arrangement pattern 2 of FIG. 50 are repeatedly arranged side by side, so that any four adjacent radio stations (for example, within a dotted square) do not have the same set. All combinations are adjacent to each other, and the maximum path diversity effect can be expected.
- the transmitting station adjusts the transmission timing, so that the signal can be received at two timings regardless of the area in which the receiving station 12 is located.
- the receiving station receives signals of three radio stations.
- the delay amount is set so as to be aggregated at two reception timings, there is no restriction on the signal from the radio station received by the receiving station.
- adjusting the length of the wired transmission path connecting the transmitting station and each radio station gives it to the signal sent to each radio station. You can decide the amount of delay you can get.
- Each functional block included in a wireless station is typically realized as an LSI that is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.
- the radio transmission system of the present invention is a multi-station simultaneous transmission system in which radio stations transmit simultaneously during relay transmission, and in particular, the propagation distance is shortened so that a plurality of radio stations are close to each other and a path diversity effect cannot be obtained.
- DSRC narrow area communications
- Dedicated Short Range Communication System ⁇ Can be used for road-to-vehicle communication systems.
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Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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EP07738798A EP1990930A1 (en) | 2006-03-17 | 2007-03-16 | Wireless transmission system and wireless transmitting method, and wireless station and transmitting station used in the same |
US12/282,722 US8229015B2 (en) | 2006-03-17 | 2007-03-16 | Wireless transmission system, wireless transmitting method, and wireless station and transmitting station used therein |
CN2007800094740A CN101405956B (zh) | 2006-03-17 | 2007-03-16 | 无线传送系统及无线传送方法、和用在其中的无线电台及发射台 |
JP2008506276A JP5058974B2 (ja) | 2006-03-17 | 2007-03-16 | 無線伝送システム及び無線伝送方法、並びにそれらに用いられる無線局及び送信局 |
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JP2006075373 | 2006-03-17 | ||
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WO2010001937A1 (ja) * | 2008-07-04 | 2010-01-07 | 京セラ株式会社 | 無線通信システム、無線送信装置、無線受信装置および無線通信方法 |
JP2011507451A (ja) * | 2007-12-17 | 2011-03-03 | テレフオンアクチーボラゲット エル エム エリクソン(パブル) | 中継局における送信時間計算のためのシステム及び方法 |
US8391201B2 (en) | 2007-12-17 | 2013-03-05 | Telefonaktiebolaget Lm Ericsson (Publ) | System and method for transmit time computation at a relay station |
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EP1860790A1 (en) * | 2005-03-28 | 2007-11-28 | Matsushita Electric Industrial Co., Ltd. | Transmission method and transmission system |
JP5213586B2 (ja) * | 2008-08-25 | 2013-06-19 | 株式会社エヌ・ティ・ティ・ドコモ | ユーザ装置及び基地局装置並びに通信制御方法 |
CN102484628B (zh) | 2009-08-27 | 2014-11-05 | 三菱电机株式会社 | 无线通信装置、通信方法及通信系统 |
US8693526B2 (en) * | 2011-02-16 | 2014-04-08 | Chester Wildey | Unipolar spread spectrum modulation for low computation and power cost signal multiplexing with application to fNIRS measurments |
KR20120126448A (ko) * | 2011-05-11 | 2012-11-21 | 한국전자통신연구원 | 무선 네트워크 시스템에서의 동기 장치 및 방법 |
JP5928263B2 (ja) * | 2012-09-05 | 2016-06-01 | 富士通株式会社 | 基地局、無線通信システム及び無線通信方法 |
JP6255946B2 (ja) | 2013-02-21 | 2018-01-10 | ヤマハ株式会社 | 復調装置、音響伝送システム、プログラム及び復調方法 |
WO2014132469A1 (ja) * | 2013-02-27 | 2014-09-04 | 株式会社国際電気通信基礎技術研究所 | 端末装置、それと無線通信を行う無線装置およびそれらを備えた無線通信システム |
CN106911375A (zh) * | 2017-02-21 | 2017-06-30 | 电子科技大学 | 低复杂度差分检测方法 |
CN113228579B (zh) * | 2018-12-28 | 2024-04-16 | 三菱电机株式会社 | 无线发送装置、无线接收装置、远程通信监视系统、无线通信系统以及无线通信方法 |
JP7310495B2 (ja) * | 2019-09-26 | 2023-07-19 | オムロン株式会社 | 制御システム、情報処理装置およびプログラム |
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JP2011507451A (ja) * | 2007-12-17 | 2011-03-03 | テレフオンアクチーボラゲット エル エム エリクソン(パブル) | 中継局における送信時間計算のためのシステム及び方法 |
US8391201B2 (en) | 2007-12-17 | 2013-03-05 | Telefonaktiebolaget Lm Ericsson (Publ) | System and method for transmit time computation at a relay station |
KR101552744B1 (ko) * | 2007-12-17 | 2015-09-18 | 텔레폰악티에볼라겟엘엠에릭슨(펍) | 중계국에서 시간 계산을 송신하기 위한 시스템 및 방법 |
WO2010001937A1 (ja) * | 2008-07-04 | 2010-01-07 | 京セラ株式会社 | 無線通信システム、無線送信装置、無線受信装置および無線通信方法 |
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EP1990930A1 (en) | 2008-11-12 |
US20090097584A1 (en) | 2009-04-16 |
JP5058974B2 (ja) | 2012-10-24 |
CN101405956A (zh) | 2009-04-08 |
CN101405956B (zh) | 2012-09-26 |
JPWO2007108409A1 (ja) | 2009-08-06 |
KR20080106461A (ko) | 2008-12-05 |
US8229015B2 (en) | 2012-07-24 |
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