JP2004129173A - Transmission device of radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a communication system that does not generate synchronizing timing error of a receiver in a case a signal from a specified antenna is not received, and can discriminate from which antenna a signal is received in case any information series is transmitted in a radio communication system in which a transmitter with a plurality of transmission antenna communicate with a receiver. <P>SOLUTION: The device comprises a coding means which inputs information series, and creates a coding series respectively corresponding to the plurality of transmission antenna, a mapping means which performs different mapping from signal point mapping performed on other series for at least a series out of coding series respectively corresponding to the plurality of antenna, and creates a mapping series respectively corresponding to the plurality of transmission antenna, and a modulation means which is installed corresponding to the plurality of antenna, and performs modulation processing for each mapping series respectively. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission device of a wireless communication system, and is applied to a wireless communication system such as a car phone.
[0002]
[Prior art]
A typical wireless communication system includes a transmitting device and a receiving device, and is required to achieve good quality regardless of the propagation environment between the transmitting device and the receiving device. A mobile phone system, which is one form of a wireless communication system, includes a base station connected to a communication network and a mobile station corresponding to a mobile phone or the like. Here, the communicable distance between the base station and the mobile station is deeply related to the transmittable power. Here, in order to cover a very wide area, a method of preparing a plurality of base stations and transmitting the same signal at the same frequency from the plurality of base stations can be considered.
[0003]
FIG. 8 is a block diagram showing a conventional communication system (for example, see Patent Document 1). In the figure, reference numeral 2 denotes a transmitter, which includes a modulator 5 and a delay unit 10. 1 is a transmission information input terminal. 6A and 6B are first and second transmitting antennas, 7 is a receiver, and 8 is a receiving antenna.
[0004]
In the transmitter in this example, an information sequence is input from the transmission information input terminal 1, the modulator 5 creates a modulation signal, and the modulation signal is transmitted from the transmission antenna 6A. The modulated signal created by modulator 5 is delayed by delay device 10 and transmitted from transmission antenna 6B.
That is, the same modulated signal is transmitted from the two transmission antennas 6A and 6B at different transmission timings. Therefore, for example, when the reception signal from the first transmission antenna 6A does not arrive, the receiver 7 has a synchronization timing error corresponding to the delay time inserted by the delay unit 10 of the transmitter 2.
Also, if the transmitted signal is, for example,
"+ 1, + 1, + 1, + 1 ..."
If the signal is the same as the above, there is a problem that the receiver 7 cannot identify whether the signal is a signal received from the first transmitting antenna 6A or a signal received from the second transmitting antenna 6B.
[0005]
[Patent Document 1]
Patent No. 2572765 (Patent gazette, page 2, right column, lines 15 to 50)
[0006]
[Problems to be solved by the invention]
Thus, when using the conventional method,
(1) When a signal from one side of the transmission antenna does not arrive, a synchronization timing error occurs in the receiver.
(2) When a specific transmission signal is transmitted, the receiver cannot identify the signal from which antenna.
There was a problem that.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. In a wireless communication system in which a transmitter having a plurality of transmitting antennas and a receiver communicate with each other, even when a signal from a specific antenna does not arrive, synchronization of the receiver is prevented. It is an object of the present invention to realize a communication system that does not generate a timing error and can identify a received signal from either antenna regardless of what kind of information sequence is transmitted.
[0008]
[Means for Solving the Problems]
A transmitting apparatus of a wireless communication system according to the present invention transmits signals from a plurality of transmitting antennas,
Coding means for inputting the information sequence and creating a coded sequence corresponding to each of the plurality of transmission antennas;
Of the encoded sequences respectively corresponding to the plurality of antennas, at least one sequence is subjected to mapping different from signal point mapping performed to another sequence, and mapping sequences corresponding to the plurality of transmission antennas are created. Mapping means;
Modulation means are provided corresponding to the plurality of antennas and perform modulation processing on each mapping sequence.
[0009]
Further, the transmission apparatus of the wireless communication system according to the present invention includes a delay unit that inserts a delay into an information sequence input into at least one of a plurality of encoded sequences created corresponding to a plurality of transmission antennas.
[0010]
Further, in the transmission apparatus of the wireless communication system according to the present invention, the encoding means is configured such that an encoded sequence created corresponding to a plurality of transmission antennas is obtained by convolutionally encoding an information sequence input. You.
[0011]
Further, in the transmission apparatus of the wireless communication system according to the present invention, the encoding unit is configured such that the encoded sequence corresponding to the plurality of transmission antennas is a sequence that is converted into parallel information by serially / parallel converting an information sequence input. You.
[0012]
Further, in the transmitting apparatus of the wireless communication system according to the present invention, the encoding unit converts the encoded sequence corresponding to the plurality of transmitting antennas into parallel information by converting an information sequence input from serial to parallel, and then performs an encoding process. It is configured to be a series that has been applied.
[0013]
Further, in the transmitting apparatus of the wireless communication system according to the present invention, the modulating means is a modulation method for performing differential coding.
[0014]
In the transmitting apparatus for a wireless communication system according to the present invention, the plurality of transmitting antennas are respectively arranged at positions corresponding to the base stations of the mobile communication system so that the transmission signal can cover a wide range.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention can be variously modified within the scope of the gist thereof, and the scope is not limited by the embodiments of the present invention described below.
[0016]
Embodiment 1
FIG. 1 shows an example of a mobile telephone system (mobile communication system) to which a transmitting apparatus of a wireless communication system according to Embodiment 1 of the present invention is applied. In the figure, reference numeral 2 denotes a transmitter, which includes an encoder 3, a mapper 4, a first modulator 5A, and a second modulator 5B. 1 is a transmission information input terminal. 6A and 6B are first and second transmitting antennas, 7 is a receiver, and 8 is a receiving antenna.
[0017]
Each function described in FIG. 1 is only a concept that plays an important role in a base station (transmitting device) such as a car telephone system (mobile communication system) to which the present invention is applied. Processing such as up-conversion for converting to a frequency includes all cases where the processing is already performed at the time of output from the modulator, and cases where the processing is performed after signal synthesis. The antenna has a function equivalent to that of a normal antenna, for example, a leaky coaxial cable.
[0018]
In the transmitting device 2, the information sequence input to the input terminal 1 is encoded by the encoder 3 into an encoded sequence corresponding to the number of transmitting antennas. In the case of this embodiment, it is encoded into two streams of two transmitting antennas 6A and 6B. The two coded sequences are subjected to different mappings by the mapper 4. For example, assuming a binary signal (0, 1), different signal points are mapped to each of the two modulators 5A and 5B as shown in FIG. Modulators 5A and 5B respectively perform modulation processing on these two mapping sequences.
[0019]
Here, the modulators 5A and 5B transmit the coded sequence on a plurality of carriers, in addition to the case where the coded sequence is modulated into a modulated signal transmitted on a single carrier (single carrier modulation process). When the modulation processing is performed on the modulated signal (multi-carrier modulation processing), or when the above-described coded sequence is multiplied by a predetermined spreading code to perform the modulation processing (code spreading modulation processing), the modulation determined by the wireless communication system is performed. The modulation process is performed according to the method.
Further, when generating the modulation signals with the modulators 5A and 5B, it is also possible to execute differential encoding modulation for giving a phase rotation for the mapping sequence.
[0020]
The modulated signals output from the modulators 5A and 5B are converted into RF frequencies by a frequency conversion processing unit (not shown in FIG. 1), and transmitted from the two transmitting antennas 6A and 6B, respectively.
The receiving device 7 receives the signals transmitted from the two transmitting antennas 6A and 6B with the receiving antenna 8, and performs a demodulation process.
[0021]
FIG. 3 shows an example of the encoder 3 according to this embodiment. In the figure, 1 is a transmission information input terminal, 9A and 9B are coded sequence output terminals corresponding to the first and second transmission antennas, respectively, and 10 is a delay unit.
[0022]
At the time of encoding, it is also possible to insert encoding (delay diversity) that gives a delay by the delay unit 10 to one side of the information sequence.
[0023]
FIG. 4 shows another example of the encoder in this embodiment. In the figure, 1 is a transmission information input terminal, 9A and 9B are coded sequence output terminals corresponding to the first and second transmission antennas 6A and 6B, respectively, and 10A, 10B and 10C are delays each constituted by, for example, a shift register. First, second and third delay units 11A and 11B having different times are first and second selective adders, respectively.
[0024]
Next, the operation of the encoder will be described with reference to FIG. The transmission information sequence is sequentially input to a shift register including first to third delay units 10A to 10C.
Arithmetic processing circuits for implementing different encoding rules are mounted on the selection addition circuits 11A and 11B. Selective addition circuits 11A and 11B input the values held in the delay units 10A to 10C, respectively, selectively perform arithmetic processing (convolutional encoding), and output encoded sequences from encoded sequence output terminals 9A and 9B. .
For example, the first selective addition circuit 11A outputs the exclusive OR of the values held by the delay units 10A and 10C to the encoded sequence output terminal 9A as a first encoded sequence. On the other hand, the second selective addition circuit 11B calculates the exclusive OR of the values held by the delay units 10A and 10B, and further calculates the exclusive OR by the calculated value and the value held by the delay unit 10C. And outputs it to the coded sequence output terminal 9B as a second coded sequence.
With such a configuration, diversity transmission in which each encoded sequence is different becomes possible, and the bit error characteristic is improved.
[0025]
In addition, at the time of encoding, it is also possible to convert an information sequence from serial to parallel and convert it into a parallel sequence, and then insert an encoding process (including the case where there is no encoding process). Also in this case, the bit error characteristics can be improved.
[0026]
Thus, in this embodiment, the signals transmitted from the two transmitting antennas 6A and 6B become different signals by setting the encoding or the mapping differently, and the signals are different on the receiving side. It is possible to identify which signal is received from which antenna, and it is possible to avoid a synchronization timing error even when delay diversity is realized as shown in FIG. 3 by this identification or when no signal is received from one antenna. it can.
[0027]
In the first embodiment, the modulation signals output from the modulators 5A and 5B are converted into RF frequencies by the frequency conversion processing unit and transmitted from the two transmission antennas 6A and 6B, respectively. The configuration is not limited to this, and a configuration may be used in which each modulated signal is combined into one baseband signal, then converted into an RF frequency by the frequency conversion processing unit, and transmitted from the transmission antenna.
[0028]
Embodiment 2
FIG. 5 shows a wireless communication system to which Embodiment 2 of the transmitting apparatus according to the present invention is applied. In the figure, 1 is a transmission information input terminal, 2 is a transmitter, 3 is an encoder, 6A and 6B are first and second transmission antennas, 7 is a receiver, 8 is a reception antenna, and 12A and 12B are An A-shift PSK modulator and a -A shift PSK modulator.
[0029]
Each function described in FIG. 5 is only a concept that plays an important role in a base station (transmitting device) such as a car telephone system (mobile communication system) to which the present invention is applied. Processing such as up-conversion for converting to a frequency includes all cases where the processing is already performed at the time of output from the modulator, and cases where the processing is performed after signal synthesis. The antenna has a function equivalent to that of a normal antenna, for example, a leaky coaxial cable.
[0030]
In the transmitting device 2, the information sequence input to the input terminal 1 is encoded by the encoder 3 into an encoded sequence corresponding to the number of transmitting antennas. In the case of this embodiment, it is encoded into two streams of two transmitting antennas 6A and 6B. These two encoded sequences are subjected to modulation processing by an A-shift PSK modulator 12A and a -A shift PSK modulator 12B. The signals modulated by the A-shift PSK modulator 12A and the -A-shift PSK modulator 12B are transmitted from the two transmission antennas 6A and 6B, respectively.
[0031]
When creating this modulated signal, it is also possible to execute differential encoding modulation. Further, these modulators can use modulation schemes such as π / 4 shift BPSK and −π / 4 shift BPSK. The receiver 7 receives the signals transmitted from the two transmitting antennas 6A and 6B with the receiving antenna 8, and performs a demodulation process. The encoding is the same as in the first embodiment.
[0032]
As described above, in the present invention, the signals transmitted from the two transmitting antennas become different signals by setting the encoding or the modulation method to be different, and the receiving side receives the signal from either antenna. It is possible to identify whether the received signal is a received signal, and it is possible to avoid a synchronization timing error regardless of whether delay diversity is realized as shown in FIG. 3 or no signal is received from one antenna.
[0033]
In the second embodiment, each coded sequence is subjected to modulation processing by the A-shift PSK modulator 12A and the −A-shift PSK modulator 12B. However, the combination of modulators is not limited to this. As long as a combination of a plurality of modulators having different modulation schemes is used, a combination of other modulators may be used.
For example, as shown in FIG. 6, a configuration including an A-shift PSK modulator 12A and a PSK modulator 12C (specifically, a combination of π / 2 shift BPSK and BPSK) may be employed. Also in this case, each coded sequence is coded by the A-shift PSK modulator 12A and the PSK modulator 12C, and the same effect as in the second embodiment can be obtained. Further, when performing the modulation process, it is also possible to execute differential coding modulation in each modulator.
[0034]
Embodiment 3
FIG. 7 shows an example in which the wireless communication system according to Embodiment 3 of the present invention is applied to a mobile telephone system (mobile communication system). In the figure, 1 is a transmission information input terminal, 13A and 13B are first and second base stations, respectively, and 14A and 14B are first and second base stations provided in first and second base stations 13A and 13B, respectively. The one-side transmission device, 15A and 15B are first and second base station antennas, 16 is a mobile station, and 17 is a mobile station antenna.
[0035]
Each function described in FIG. 7 is only a concept that plays an important role in a base station related to a mobile telephone system (mobile communication system) to which the present invention is applied. For example, an up-converter that converts a baseband signal to an RF frequency is used. It is assumed that the processing such as conversion includes all cases where the processing is already performed at the time of output from the modulator and the case where the processing is performed after signal synthesis. The antenna has a function equivalent to that of a normal antenna, for example, a leaky coaxial cable.
[0036]
The first base station 13A receives the information sequence and generates, for example, a signal corresponding to the output of the first modulator 5A of Embodiment 1 or the output of the A-shift PSK modulator 12A of Embodiment 2, The signal is transmitted from the first base station antenna 15A. Similarly, the second base station 13B receives the information sequence and receives, for example, a signal corresponding to the output of the second modulator 5B of the first embodiment or the output of the −A shift PSK modulator 12B of the second embodiment. Is generated and transmitted from the second base station antenna 15B. The mobile station 16 receives from the mobile station antenna 17 the signals transmitted by the two base station antennas 15A and 15B as in the first and second embodiments.
[0037]
Therefore, according to this embodiment, in a communication system covering a wide range, signals transmitted from two base station antennas have different encoding or modulation schemes, so that different signals are set. The signal becomes a signal, and the mobile station can identify which signal is received from which antenna. The synchronization timing can be obtained regardless of whether delay diversity is realized as shown in FIG. 3 or the signal is no longer received from one antenna. Errors can be avoided.
[0038]
【The invention's effect】
As described above, according to the present invention, signals transmitted from a plurality of transmitting antennas are different signals, and it is possible to identify a receiving signal from which antenna on the receiving side, and this identification realizes delay diversity. However, even when a signal is no longer received from one antenna, a synchronization timing error can be avoided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a wireless communication system according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an example of mapping according to the present invention.
FIG. 3 is a block diagram of a first encoder in FIG. 1;
FIG. 4 is a block diagram of a second encoder in FIG. 1;
FIG. 5 is a block diagram showing a configuration of a wireless communication system according to a second embodiment of the present invention.
FIG. 6 is a block diagram showing another configuration of the second embodiment of the wireless communication system according to the present invention.
FIG. 7 is a block diagram showing a configuration of a wireless communication system according to a third embodiment of the present invention.
FIG. 8 is a block diagram illustrating a configuration of a conventional wireless communication system.
[Explanation of symbols]
1: transmission information input terminal, 2: transmitter, 3: encoder, 4: mapper,
5A, 5B: modulator, 6A, 6B: transmitting antenna, 7: receiver 8, receiving antenna, 9A, 9B: coded sequence output terminal 10, 10A, 10B, 10C: delay unit, 11A, 11B: selective adding circuit ,
12A: A shift PSK modulator, 12B: -A shift PSK modulator,
12C: PSK modulator,
13A, 13B: base station, 14A, 14B: one-side transmitter, 15A, 15B: base station, 16: mobile station, 17: mobile station antenna.

Claims (7)

In a transmission device of a wireless communication system that transmits signals from a plurality of transmission antennas,
Coding means for inputting an information sequence and creating a coded sequence corresponding to each of a plurality of transmission antennas;
Among the encoded sequences respectively corresponding to the plurality of antennas, at least one sequence is subjected to mapping different from signal point mapping performed to another sequence, and mapping sequences corresponding to the plurality of transmission antennas are created. Mapping means;
A modulating unit that is provided corresponding to the plurality of antennas and performs a modulation process on each mapping sequence;
A transmission device for a wireless communication system, comprising: 2. The transmission according to claim 1, further comprising a delay unit that inserts a delay into an information sequence input into at least one of a plurality of encoded sequences created corresponding to the plurality of transmission antennas. apparatus. 2. The radio communication system according to claim 1, wherein the encoding unit is configured to assume that an encoded sequence created corresponding to a plurality of transmission antennas is obtained by convolutionally encoding an information sequence input. Transmission device. 2. The wireless communication system according to claim 1, wherein the coding unit is configured to form a coded sequence corresponding to the plurality of transmission antennas into a sequence obtained by converting an information sequence input from serial to parallel to form parallel information. Transmission device. The encoding unit is characterized in that the encoded sequence corresponding to the plurality of transmission antennas is configured to be a sequence subjected to an encoding process after converting an information sequence input from serial to parallel to parallel information. The transmitting device of the wireless communication system according to claim 1. The transmitting device of a wireless communication system according to any one of claims 1 to 5, wherein the modulating means is a modulation method that performs differential coding. 7. The radio communication system according to claim 1, wherein the plurality of transmission antennas are arranged at positions corresponding to base stations of the mobile communication system so that the transmission signal can cover a wide range. Transmission device.

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