JP2013198023A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technic that can realize high-quality data transmission without being affected by transmission characteristics (phase characteristics, attenuation characteristics or the like) of a wired zone.SOLUTION: A communication system includes a first base station 121a and a second base station 121b each of which converts bit data of a signal received from a mobile station 101 into a complex symbol to perform differential space-time encoding thereby producing a first series signal and a second series signal orthogonal to each other. The first base station 121a performs quadrature modulation on only the first series signal into a transmission wave for transmitting to a wired transmission path. The second base station 121b performs quadrature modulation on only the second series signal into a transmission wave for transmitting to the wired transmission path. The communication system also includes a data collecting device 151 which synthesizes the transmission wave transmitted by each wired transmission path and performs differential space-time decoding on a signal obtained by quadrature detecting the synthesized wave thereby performing decode reflecting affect due to the transmission characteristics of each wired transmission path and converting decoded signal into the bit data.

Description

  The present invention relates to transmission in a wired section in a communication system that performs communication using wired communication, and in particular, DSTBC (Differential Space Time Block Coding), which is attracting attention as a wireless MIMO (Multi-Input Multi-Output) technology. The present invention relates to a wired transmission system that enables high-quality data communication by applying a (space encoding) system to wired low bit rate data transmission.

Conventionally, various inventions have been proposed for communication systems that perform communication using wired communication.
For example, in a communication system having a plurality of base stations that communicate wirelessly with a wireless terminal station, an optical line connected to each of the base stations, and an upper station connected to the optical line, an optical line from the upper station to each base station There has been proposed a technique for eliminating the difference in propagation delay in an optical line by making the lengths of the same length (see Patent Document 1).

JP 2010-193205 A

  FIG. 2 shows an example of a system diagram of a conventional communication system as a model to which the present invention is applied. In this communication system, character information and the like input to the mobile station 201 is transmitted wirelessly and by wire and displayed on the ground display device 261. In FIG. 2, for simplification, two base stations 221 (first base station 221a and second base station 221b) are used as receiving stations for signals wirelessly transmitted from the mobile station 201. Yes.

The operation of the communication system shown in FIG. 2 will be described.
When the mobile station 201 receives input of character information or the like (hereinafter simply referred to as “character information”) from the operator via the data input terminal 202, the mobile station 201 wirelessly transmits a signal of this character information through the mobile station radio unit 203.
More specifically, the mobile station radio section 203 performs MSK on the bit data of the character information output from the data input terminal 202 at a bit rate of, for example, 1200 bps (mark: 1200 Hz, space: 1800 Hz). (Minimum-Shift Keying) modulation, and further, the FM modulation unit 205 performs FM (Frequency Modulation) modulation on the MSK signal (deemed speech) in this audio band, and analog-modulates it to the radio frequency band, and outputs it from the antenna as radio waves To do.

The first base station 221a receives the radio wave from the mobile station 201, and when the received electric field strength is equal to or higher than a certain level, the internal squelch circuit is opened, the FM detector 222a performs FM detection, and the FM detection signal Is output.
Similarly, the second base station 221b receives radio waves from the mobile station 201, and when the received electric field strength is above a certain level, the internal squelch circuit is opened and FM detection is performed by the FM detection unit 222b. , FM detection signal is output.
Here, since mobile station radio section 203 on the transmission side regards the bit data of character information as MSK-modulated and processes it as a speech, the output of base station 221 on the reception side is an audio band MSK signal (deemed speech). Become. In the base station 221 having a low received electric field strength (less than a certain level), nothing is output because the internal squelch circuit does not operate.

The MSK signal (deemed speech) in the audio band output from the first base station 221a is transmitted to the data collection device 251 via the wired line 241a.
Also, the MSK signal (deemed voice) in the audio band output from the second base station 221b is transmitted to the data collection device 251 via the wired line 241b, the relay amplification device 242, and the wired line 241c.
As the wired lines 241a, 241b, and 241c, for example, a metallic line for analog signal transmission represented by a telephone line is used. In addition, the relay amplification device 242 includes an amplifier circuit 243 that amplifies the signal to correct the attenuation of the signal due to transmission when the wired line is long.

The data collection device 251 combines the MSK signal (deemed speech) from the first base station 221a and the MSK signal (deemed speech) from the second base station 221b side by the synthesizer 252 and MSK detection Bit data is restored by MSK detection in the unit 253 and output to the display device 261.
The display device 261 converts the bit data output from the data collection device 251 into character information and displays it on a display or the like.

Here, the following matters are assumed as preconditions.
That is, the wired transmission distance from the first base station 221a to the data collection device 251 is relatively short, and the wired transmission distance from the second base station 221b to the data collection device 251 is long. This is a case where the relay amplification device 242 is installed only between the second base station 221b and the data collection device 251 in order to correct. In addition, it is assumed that the ground wired infrastructure network is prepared in advance, and further, the specifications for the phase characteristics of the amplifier circuit 243 in the relay amplifier 242 are not clear.
In the following, a case where the amplifier circuit 243 in the relay amplifier 242 is a simple repetitive amplifier circuit and the phase of the amplified output with respect to the input is inverted by 180 ° will be described as an example.

First, in the case where the mobile station 201 distributes information in the vicinity of the first base station 221a, the character information to the data input terminal 202 of the mobile station 201 is wirelessly transmitted by the mobile station wireless unit 203 and passes through the wireless line. Then, it is received by the first base station 221a. In the first base station 221a, since the received electric field strength is sufficient, the squelch circuit is opened, and the MSK signal (deemed voice) reproduced by FM detection is output to the wired line 241a.
At this time, the radio wave from the mobile station 201 does not reach the second base station 221b, and nothing is output from the second base station 221b.
The data collection terminal 251 combines the signal from the first base station 221a input via the wired line and the signal from the second base station 221b, and performs MSK detection, but the second base station 221b. Since there is no input from the side, as a result, only the signal received by the first base station 221a is MSK detected, output as character information, and displayed on the display device 261.

  In the case where the mobile station 201 distributes information in the vicinity of the second base station 221b, the same operation as described above (however, the first base station 221a and the second base station 221b are reversed) The connection between the second base station 221 b and the data collection device 251 is established via the relay amplification device 242. Here, as described above, the phase is inverted by the relay amplifying device 242, but since there is no signal from the first base station 221a, the detection result by the MSK detection unit 253 of the data collecting device 251 Does not affect.

  Next, consider a case where the mobile station 201 delivers information at an intermediate point between the first base station 221a and the second base station 221b. In this case, the radio wave transmitted from the mobile station 201 is received by both the first base station 221a and the second base station 221b. Therefore, the squelch circuit is opened in both the first base station 221a and the second base station 221b, and MSK signals (deemed speech) subjected to FM detection are output in each.

  At this time, the output of the second base station 221b is subjected to signal amplification and phase inversion by the relay amplification device 242 based on the above preconditions. Therefore, since the data collection device 251 combines the signal from the first base station 221a and the signal obtained by inverting the phase of the signal from the second base station 221b, the output of the combiner 252 cancels out the two signals. Then, the input of the MSK detection unit 253 becomes zero. As a result, nothing is displayed on the display device 261.

FIG. 3 shows this state as a waveform.
FIG. 3A is an example of a waveform input from the first base station 221a.
FIG. 3B is an example of a waveform input from the second base station 221b.
3 (b) is inverted in phase with respect to FIG. 3 (a). This is due to the characteristics of the amplifier circuit 243 in the relay amplification device 242.
In this case, the output of the synthesizer 252 in the data collection device 251 is as shown in FIG. That is, the waveforms in FIGS. 3A and 3B cancel each other and become zero. At this time, the output of the data collection device 251 is the same as when there is no reception, and nothing is displayed on the display device 261.

  The simplest solution when the above problem occurs is to insert an inverting amplifier into one of the other wired lines, but the phase characteristics of the wired line can be measured beforehand using a measuring instrument. Therefore, it is difficult to investigate, and it takes an enormous amount of time to find out the cause.

  The present invention has been made in view of the above-described conventional circumstances, and a plurality of devices that can receive the same signal are connected to a data collection device by a wired line, and are combined and output by the data collection device. An object of the present invention is to propose a technology that makes it possible to realize high-quality data transmission regardless of transmission characteristics (phase characteristics, attenuation characteristics, etc.) in a wired section.

The present invention has the following configuration in order to solve the above-described problems.
That is, the differential space-time coding (DSTBC) method, which is attracting attention as a MIMO technology in wireless communication, is applied to data transmission in a wired section.

Specifically, the first base station and the second base station that receive signals transmitted from the terminal station by radio are connected to the first base station and the second base station through different wired transmission paths. In a communication system having a data collection device, processing is performed as follows.
That is, the first base station converts the bit data of the signal received from the terminal station into a complex symbol and performs differential space-time coding, thereby converting the first sequence signal and the second sequence signal orthogonal to each other. The first series of signals are orthogonally modulated and transmitted as a transmission wave to a wired transmission line. Further, the second base station converts the bit data of the signal received from the terminal station into a complex symbol and performs differential space-time coding, thereby converting the first sequence signal and the second sequence signal orthogonal to each other. The second series of signals are orthogonally modulated and transmitted as a transmission wave to the wired transmission line. Then, the data collection device synthesizes the transmission waves transmitted through the respective wired transmission paths, differentially space-time decodes the signals obtained by orthogonal detection of the synthesized waves, and converts the decoded signals into bit data .

  As described above, in the present invention, each base station generates two series of signals orthogonal to each other by the differential space-time coding system, and sends each series of signals to different wired transmission lines to collect data. Was transmitted to. For this reason, even if each series of signals transmitted through the respective wired transmission paths is combined by the data collection device, the signals do not interfere with each other, so that high-quality data transmission can be realized. . Furthermore, in the differential space-time coding method, the information representing the transmission characteristics of the transmission path is not included in the decoding arithmetic expression, but decoding that reflects the influence of the transmission characteristics of the transmission path can be performed. There is no need to know in advance the transmission characteristics of each wired transmission path.

  Here, the communication system according to the present invention may have a configuration in which a plurality of first base stations and second base stations are alternately provided. As a result, a wide wireless communication area can be secured by a plurality of base stations, and high-quality data transmission can be realized on the wired transmission path between each base station and the data collection device. There is no need to know the transmission characteristics of the transmission line in advance.

  Further, the present invention provides a communication including a first device and a second device that can receive the same signal, and a data collection device connected to the first device and the second device through different wired transmission paths. In the system, the first device generates a first sequence signal and a second sequence signal orthogonal to each other by converting the bit data of the received signal into a complex symbol and performing differential space-time coding, Of these signals, the first series of signals are orthogonally modulated and transmitted as a transmission wave to a wired transmission line, and the second device converts the bit data of the received signal into a complex symbol and performs differential space-time coding. Then, a first sequence signal and a second sequence signal that are orthogonal to each other are generated, and the second sequence signal is orthogonally modulated and transmitted as a transmission wave to a wired transmission line. Transmission wave transmitted by wired transmission line Combined, a signal obtained by quadrature detection synthesized wave differential space-time decoding, is characterized by converting the decoded signal into bit data.

  According to the present invention, each base station or each device generates two sequences of signals that are orthogonal to each other by the differential space-time coding method, and sends each sequence of signals to different wired transmission paths. Therefore, even if each series of signals transmitted through the respective wired transmission paths is combined by the data collection device, the signals do not interfere with each other, so that high-quality data transmission can be realized. Furthermore, in the differential space-time coding method, the information representing the transmission characteristics of the transmission path is not included in the decoding arithmetic expression, but decoding that reflects the influence of the transmission characteristics of the transmission path can be performed. There is no need to know in advance the transmission characteristics of each wired transmission path.

It is a figure which shows the example of the systematic diagram of the communication system which concerns on one Embodiment of this invention. It is a figure which shows the example of the systematic diagram of the conventional communication system. It is a figure which shows the example of the waveform in the structure of FIG.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a system diagram of a communication system according to an embodiment of the present invention.
The communication system of this example includes a mobile station 101 as a terminal station including a data input terminal 102 and a mobile station radio unit 103, a first base station 121a, a conversion device 131a attached thereto, and a second base station. 121b and a conversion device 131b attached thereto, a relay amplification device 142, a data collection device 151, and a display device 161 connected thereto.

Also, the conversion device 131a on the first base station 121a side and the data collection device 151 are connected by a wired line 141a, and the conversion device 131b on the second base station 121b side and the relay amplification device 142 are connected by a wired line 141b. The relay amplification device 142 and the data collection device 151 are connected by a wired line 141c.
That is, a transmission line connecting the conversion device 131a on the first base station 121a side and the data collection device 151 is configured by the wired line 141a, and connects the conversion device 131b on the second base station 121b side and the data collection device 151. The transmission path is constituted by a wired line 141b, a relay amplifier 142, and a wired line 141c.

  Here, as the wired lines 141a, 141b, and 141c, for example, a metallic line for analog signal transmission represented by a telephone line is used. Note that signals transmitted by these wired circuits are not MSK-modulated signals as in the conventional system, but are DSTBC-encoded audio band signals as will be described later.

When the mobile station 101 receives input of character information from the operator via the data input terminal 102, the mobile station 101 wirelessly transmits a signal of this character information via the mobile station radio unit 103.
More specifically, the mobile station radio section 103 performs MSK on bit data of character information output from the data input terminal 102 at a bit rate of, for example, 1200 bps (mark: 1200 Hz, space: 1800 Hz). Further, the MSK signal (deemed speech) in this audio band is FM-modulated by the FM modulation unit 105 and analog-modulated to a radio frequency band, and is output as a radio wave from the antenna.

The first base station 121a receives the radio wave from the mobile station 101, and when the received electric field strength is above a certain level, the internal squelch circuit is opened, FM detection is performed by the FM detection unit 122a, and FM detection is performed. The obtained MSK signal (deemed speech) is output to the converter 131a.
The conversion device 131a is installed in the immediate vicinity of the first base station 121a, receives the MSK signal output from the first base station 121a, detects the MSK signal and converts it into bit data, and an MSK detection unit 132a. The BPSK modulation unit 133a that converts the bit data output from the MSK detection unit 132a into a complex symbol (IQ signal) by performing BPSK (Binary Phase Shift Keying) modulation at the same bit rate, and the BPSK output from the BPSK modulation unit 133a A DSTBC encoder 134a that performs DSTBC encoding processing on the complex symbols is provided.
That is, the converter 131a sequentially performs MSK detection, BPSK modulation, and DSTBC encoding processing on the MSK signal from the first base station 121a, and outputs the resulting signal to the wired line 141a.

The second base station 121b receives the radio wave from the mobile station 101, and when the received electric field strength is above a certain level, the internal squelch circuit is opened, FM detection is performed by the FM detection unit 122b, and FM detection is performed. The obtained MSK signal (deemed speech) is output to the converter 131b.
The converter 131b is installed in the immediate vicinity of the second base station 121b, receives the MSK signal output from the second base station 121b, receives the MSK signal, detects the MSK signal and converts it into bit data, The BPSK modulator 133b that BPSK modulates the bit data output from the MSK detector 132b at the same bit rate to convert it into a complex symbol (IQ signal), and the DSTBC for the BPSK complex symbol output from the BPSK modulator 133b A DSTBC encoder 134b that performs encoding processing is provided.
That is, the converter 131b sequentially performs MSK detection, BPSK modulation, and DSTBC encoding processing on the MSK signal from the second base station 121b, and outputs the resultant signal to the wired line 141b.

  Here, the DSTBC scheme is a coding scheme that outputs two orthogonal sequences (hereinafter referred to as A sequence and B sequence), as will be described later. The DSTBC encoders 134a and 134b are set in advance to output only one of the A series and the B series different from each other. In this example, the DSTBC encoder 134a outputs only the A series. The DSTBC encoder 134b outputs only the B sequence.

The wired line 141 a transmits the A-sequence signal output from the conversion device 131 a on the first base station 121 a side to the data collection device 151.
The wired line 141b transmits the B-sequence signal output from the conversion device 131b on the second base station 121b side to the relay amplification device 142.
The relay amplifier 142 inverts and amplifies the B-sequence signal transmitted through the wired line 141b by the internal amplifier circuit 143, and outputs the amplified signal to the wired line 141c.
The wired line 141 c transmits the inverted B-sequence signal output from the relay amplification device 142 to the data collection device 151.

The data collection device 151 synthesizes the A-sequence signal transmitted from the first base station 121 a side and the B-sequence signal transmitted from the second base station 121 b side, and outputs from the synthesizer 152. A DSTBC decoder 153 that performs a DSTBC decoding process on the synthesized signal to restore a BPSK complex symbol, and a BPSK detector 154 that restores bit data by BPSK detection of the complex symbol output from the DSTBC decoder 153 Is provided.
That is, the data collection device 151 combines the A-sequence signal transmitted from the first base station 121a side and the B-sequence signal transmitted from the second base station 121b side, and performs DSTBC decoding processing and BPSK detection. The data is sequentially applied, and the resulting bit data is output to the display device 161.
The display device 161 converts the bit data output from the data collection device 151 into character information and displays it on a display or the like.

Next, the case that has become a problem in the conventional method will be taken up.
That is, consider a case where the mobile station 101 distributes information at an intermediate point between the first base station 121a and the second base station 121b. In this case, the radio wave transmitted from the mobile station 101 is received by both the first base station 121a and the second base station 121b. Therefore, the squelch circuit is opened in both the first base station 121a and the second base station 121b, and the FM detected MSK signal (deemed speech) is output in each. The operation so far is the same as the conventional method.

In the communication system of this example, the output of the first base station 121a is connected to the conversion device 131a, and the output of the second base station 121b is connected to the conversion device 131b.
In the converter 131a, the MSK signal (deemed speech) input from the first base station 121a is converted into bit data by the MSK detector 132a, BPSK modulated at the same bit rate by the BPSK modulator 133a, and complex. The signal is converted into a symbol (IQ signal), and the DSTBC encoder 134a performs DSTBC encoding processing to generate two orthogonal signals, and outputs only one of these signals (A sequence in this example).
Also, in the converter 131b, the MSK signal (deemed speech) input from the second base station 121b is converted into bit data by the MSK detector 132b, and BPSK modulated at the same bit rate by the BPSK modulator 133b. Are converted into complex symbols (IQ signals), DSTBC encoder 134b performs DSTBC encoding processing to generate two orthogonal signals, and only a sequence (in this example, a B sequence) different from that of conversion device 131a is generated. Output.
Here, it is assumed that the DSTBC encoders 134a and 134b each include an orthogonal modulator. For example, an audio band oscillator having an oscillation frequency of 1500 Hz is used as the quadrature modulator.

With such a configuration, the A series signal is input to the data collection device 151 from the conversion device 131a directly connected to the first base station 121a using the wired line 141a as a transmission path.
In addition, a B-series signal is input from the conversion device 131b directly connected to the second base station 121b to the data collection device 151 via the wired line 141a, the relay amplification device 142, and the wired line 141c.
At this time, the signal sequence (A sequence) output from the conversion device 131a on the first base station 121a side and the signal sequence (B sequence) output from the conversion device 131b on the second base station 121b side are the same. 2 (character information wirelessly transmitted from the mobile station 101), while having no correlation with each other and orthogonality.

The data collection device 151 combines a signal from the first base station 121a side and a signal from the second base station 121b side by a combiner 152. These signals are an A-sequence signal and a B-sequence signal in the DSTBC system, and have no correlation with each other and have orthogonality. Thus, the signals do not cancel each other and become zero.
The signal synthesized by the synthesizer 152 is converted into bit data by the DSTBC decoder 153 and the BPSK detector 154, and the original character information is displayed on the display device 161.

  As described above, when two base stations receive the same signal, one base station (in this example, the first base station 121a) is provided with the converter 131a that outputs the A sequence of the DSTBC scheme, and the other base station By providing the base station (in this example, the second base station 121b) with the conversion device 131b that outputs the B sequence of the DSTBC scheme, both signals are prevented from interfering with the combiner 152 of the data collection device 151. It is possible to take a simple configuration.

Here, the operation of the conversion device 131a and the data collection device 151 will be further described.
Note that the conversion device 131b is the same as the conversion device 131a except that the output series is different, and therefore the description of the conversion device 131b is omitted.

First, the operation of the conversion device 131a will be described.
The converter 131a performs the following processing using the MSK detector 132a, the BPSK modulator 133a, and the DSTBC encoder 134a.
The MSK detector 132a detects the MSK signal output from the first base station 121a and converts it into bit data. In this example, it is assumed that 2-bit bit data b _2m and b _{2m + 1} are output as a conversion result at time m (m is an integer of 0 or more).
The BPSK modulation unit 133a converts the first half bit b _2m of the 2-bit bit data b _2m and b _{2m + 1} input from the MSK detection unit 132a into a BPSK symbol x _2n , and the latter half 1 bit b _{2m +. 1} is converted into a BPSK symbol x _{2n + 1} . Here, n is a time series number that changes every two symbol times, and n = m. Symbols x _2n and x _{2n + 1} are complex numbers and can be expressed as IQ signals (= I + jQ (j is an imaginary unit)) using an in-phase value I (In-Phase) and a quadrature value Q (Quadrature-Phase). .

The DSTBC encoder 134a is configured using a differential encoding unit, a space-time encoding unit, and an orthogonal modulator.
The differential encoding unit outputs the BPSK complex symbols x _2n and x _{2n + 1} input from the BPSK modulation unit 133a at time n, and the output s _2n−2 from the differential encoding unit at time n−1. , S _2n-1 is used to calculate (Equation 1), and as a result, s _2n and s _{2n + 1} are output. Note that * represents a complex conjugate.

Here, the transformation matrix M _2n shown in (Equation 2) needs to be a unitary matrix. For this purpose, the initial values s ₋₂ and s ₋₁ given in (Equation 1) satisfy (Equation 3), In addition, it is necessary that the outputs x _2n and x _{2n + 1} from the BPSK modulation unit 133a satisfy (Equation 4).

The space-time coding unit performs space-time coding processing on s _2n and s _{2n + 1} input from the differential coding unit, outputs s _2n at the timing of symbol number 2n, and outputs symbol number 2n + 1. a series or outputs one of B series for outputting the s _2n ^* and outputs the s _{2n + 1} at the timing of the symbol number 2n timing of symbol number 2n + 1 outputs an -s _{2n + 1} ^* at timing To do. In this example, the A base is output on the first base station 121a side, and the B series is output on the second base station 121b side.
The quadrature modulator performs quadrature modulation on the signal sequence (A sequence or B sequence) output from the space-time encoding unit, for example, with an oscillation frequency of 1500 Hz, and outputs the signal as an audio band signal.

Next, the operation of the data collection device 151 will be described.
The data collection device 151 performs the following processing using the synthesizer 152, the DSTBC decoder 153, and the BPSK detector 154.
The combiner 152 combines and outputs the A-sequence signal transmitted from the first base station 121a side and the B-sequence signal transmitted from the second base station 121b side. Here, since the A-sequence signal and the B-sequence signal are not correlated with each other and have orthogonality, even when phase fluctuation occurs in the transmission process, the signal components do not interfere with each other by combining.

The DSTBC decoder 153 is configured using an orthogonal detector, a space-time decoding unit, and a determination unit.
The quadrature detector detects the combined signal input from the combiner 152 and outputs the result.
At time n, the space-time decoding unit outputs r _2n and r _{2n + 1} from the quadrature detector at time n, and output r _2n-2 from the quadrature detector at time n−1. Using r _2n−1 , the calculation of (Expression 5) is performed, and as a result, y _2n and y _{2n + 1} are output. Here, n is a time series number that changes every two symbol times.

Here, the expression for the decoding (Expression 5) does not include information indicating the transmission characteristics of the transmission path. This is based on the fact that it is estimated that there is little variation in transmission characteristics of the transmission line between the time n and the time n−1, and the received contents (r _2n , r _{2n +} at the time n are ₁ ) and the calculation using the received contents (r _2n-2 , r _2n-1 ) at time n−1, the transmission characteristics of each transmission path remain unknown, while the transmission characteristics of the transmission path remain unknown. The received content can be decrypted while reflecting the influence of.

The determination unit performs a hard decision or a soft decision on the outputs y _2n and y _{2n + 1} from the space-time decoding unit, and outputs the resulting BPSK complex symbol (IQ signal) to the BPSK detection unit 154. .
The BPSK detector 154 performs BPSK detection on the complex symbol output from the DSTBC decoder 153, restores the bit data representing the original input information, and outputs it.

  As described above, in this example, each of the first base station 121a and the second base station 121b converts the bit data of the signal received from the mobile station 101 into a complex symbol and performs differential space-time coding. Thus, a first sequence signal and a second sequence signal that are orthogonal to each other are generated, and the first base station 121a orthogonally modulates only the first sequence signal and transmits it as a transmission wave to the wired transmission path. The second base station 121b orthogonally modulates only the second series of signals and transmits it as a transmission wave to the wired transmission line, and the data collection device 151 synthesizes the transmission wave transmitted through each of the wired transmission lines. Then, by performing differential spatio-temporal decoding on the signal obtained by quadrature detection of the synthesized wave, decoding that reflects the effect of the transmission characteristics of each wired transmission path is performed, and the decoded signal is converted to bit data I tried to do it.

  In this way, each of the first base station 121a side and the second base station 121b side generates signals of two sequences (A sequence and B sequence) orthogonal to each other by the DSTBC method, Since the signals are sent to different wired transmission paths and transmitted to the data collection device 151, even if the data collection devices 151 combine the signals of each series transmitted through the respective wired transmission paths, Since they do not interfere with each other, high-quality data transmission can be realized. Further, in the DSTBC system, although the information indicating the transmission characteristics of the transmission path is not included in the decoding calculation formula, it is possible to perform decoding reflecting the influence of the transmission characteristics of the transmission path. Therefore, it is not necessary to know the transmission characteristics in advance.

Heretofore, a communication system in which one first base station 121a and one second base station 121b are provided has been described as an example, but a configuration in which a plurality of these base stations are provided may be employed.
For example, a plurality of first base stations 121a and second base stations 121b may be alternately provided in a straight line. As a result, as in a train radio system in which a plurality of base stations are arranged along a track, after securing a radio communication area along a predetermined track, a wired transmission path between each base station and the data collection device Can realize high-quality data transmission, and it is not necessary to know the transmission characteristics of each wired transmission line in advance.
For example, a plurality of first base stations 121a and second base stations 121b may be alternately provided in a lattice pattern. As a result, high-quality data transmission can be realized in the wired transmission path between each base station and the data collection device after securing a planar wireless communication area having a two-dimensional spread, In addition, it is not necessary to know in advance the transmission characteristics of each wired transmission path.
Moreover, in this example, although it converted into a complex symbol by the BPSK system, you may convert into a complex symbol by other modulation systems, such as QPSK (Quadrature Phase Shift Keying) system.

Here, the configuration of the system and apparatus according to the present invention is not necessarily limited to the configuration described above, and various configurations may be used.
For example, in the above-described embodiments, the communication system of the present invention has been described with an example in which the mobile station 101 is provided as a terminal station. However, in the present invention, the terminal stations that perform wireless communication with the base stations 121a and 121b are not limited to mobile stations, and include fixed stations that are fixedly installed.
Furthermore, in the embodiment described above, the communication system of the present invention takes the base stations 121a and 121b as examples of the first and second devices, and receives data from other devices (mobile station 101 in the embodiment) by radio. Explained the case. However, the present invention is not limited to this, and the first and second devices only need to be able to receive the same signal (bit data, etc.) from other devices, and are not wired but wired. Data may be received. Even in this case, the same effects as those of the above-described embodiment can be obtained.

The present invention can also be provided as, for example, a method or method for executing the processing according to the present invention, a program for realizing such a method or method, or a recording medium for recording the program. It is also possible to provide various systems and devices.
The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields.
In addition, as various processes performed in the system and apparatus according to the present invention, for example, the processor executes a control program stored in a ROM (Read Only Memory) in hardware resources including a processor and a memory. A controlled configuration may be used, and for example, each functional unit for executing the processing may be configured as an independent hardware circuit.
The present invention can also be understood as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD (Compact Disc) -ROM storing the control program, and the program (itself). The processing according to the present invention can be performed by inputting the program from the recording medium to the computer and causing the processor to execute the program.

101: Mobile station, 102: Data input terminal, 103: Mobile station radio section, 104: MSK modulation section, 105: FM modulation section, 121a, 121b: Base station, 122a, 122b: FM detection section, 131a, 131b: Conversion Device, 132a, 132b: MSK detection unit, 133a, 133b: BPSK modulation unit, 134a, 134b: DSTBC encoder, 141a, 141b, 141c: Wired line, 142: Relay amplifier, 143: Amplifier circuit, 151: Data collection Device: 152: combiner; 153: DSTBC decoder; 154: BPSK detector; 161: display device;
201: Mobile station, 202: Data input terminal, 203: Mobile station radio unit, 204: MSK modulation unit, 205: FM modulation unit, 221a, 221b: Base station, 222a, 222b: FM detection unit, 241a, 241b, 241c : Wired line, 242: Relay amplification device, 243: Amplifier circuit, 251: Data collection device, 252: Synthesizer, 253: MSK detection unit, 261: Display device

Claims (3)

A first base station and a second base station that receive signals transmitted wirelessly from a terminal station; and a data collection device connected to the first base station and the second base station via different wired transmission paths, respectively In a communication system having
The first base station generates a first sequence signal and a second sequence signal orthogonal to each other by converting the bit data of the signal received from the terminal station into a complex symbol and performing differential space-time coding. , Of which the first series of signals are orthogonally modulated and transmitted as a transmission wave to the wired transmission line,
The second base station generates a first sequence signal and a second sequence signal orthogonal to each other by converting the bit data of the signal received from the terminal station into a complex symbol and performing differential space-time coding. , Of which the second series of signals are orthogonally modulated and transmitted as a transmission wave to the wired transmission line,
The data collection device synthesizes the transmission waves transmitted by each wired transmission path, differential space-time decoding the signal obtained by orthogonal detection of the combined wave, and converts the decoded signal into bit data,
A communication system characterized by the above. The communication system according to claim 1,
A plurality of first base stations and second base stations provided alternately,
A communication system characterized by the above. In a communication system having a first device and a second device that can receive the same signal, and a data collection device connected to the first device and the second device by different wired transmission paths, respectively.
The first device generates a first sequence signal and a second sequence signal that are orthogonal to each other by converting the bit data of the received signal into a complex symbol and performing differential space-time coding. A series of signals are orthogonally modulated and transmitted as a transmission wave to a wired transmission line.
The second device generates a first sequence signal and a second sequence signal orthogonal to each other by converting the bit data of the received signal into a complex symbol and performing differential space-time coding. Two series of signals are orthogonally modulated and transmitted as a transmission wave to the wired transmission line.
The data collection device synthesizes the transmission waves transmitted through the respective wired transmission lines, performs differential space-time decoding on a signal obtained by orthogonal detection of the combined wave, and converts the decoded signal into bit data. A featured communication system.

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