JP2002026863A - Transmitter and receiver for communication adopting ofdm system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system where a mobile station can receive an OFDM signal without deteriorating its communication quality in the case that an on-road station transmits the OFDM signal to the mobile station for the purpose of communication. SOLUTION: The on-road station is installed with rightward circularly polarized wave transmission antennas TX1, TX2 and a vehicle 1 is installed with a leftward circularly polarized wave transmission antenna RX1 and a rightward circularly polarized wave reception antenna RX2. The rightward circularly polarized wave reception antenna RX2 receives direct waves W1, W3 from the rightward circularly polarized wave transmission antennas TX1, TX2 and the leftward circularly polarized wave reception antenna RX1 receives reflected waves W2, W4 that the transmitted from the rightward circularly polarized wave transmission antennas TX1, TX2 and reflected in an obstacle because the waves W2, W4 are leftward circularly polarized waves because of the reflection. Thus, even when the obstacle being other passing vehicle exists at one side or at both sides of the vehicle 1, the vehicle 1 can excellently execute the reception processing by means of the reception of the direct waves by the rightward circularly polarized wave reception antenna RX1 and/or the reception of the reflected waves by the leftward circularly polarized wave reception antenna RX2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transmitter and a receiver for performing communication using the OFDM system.

[0002]

2. Description of the Related Art Conventionally, in a mobile communication system used for a vehicle such as an automobile, a plurality of road stations are arranged at arbitrary intervals along a moving route of the vehicle, and a radio zone formed by each road station is provided. When a vehicle passes through any of the above, wireless communication is performed between a mobile station of the vehicle and a road station forming the wireless zone.

[0003] In such a mobile communication system, when a radio wave-hindered vehicle such as a large vehicle exists between the target mobile station and the antenna of the road station, the target mobile station is shaded and the road station cannot be connected. There is a problem of shadowing that the communication quality during the communication deteriorates. In addition, there is also a problem of multipath fading in which radio waves transmitted from roadside stations are reflected on walls or the like and reach the mobile station, and the received electric field is disturbed to deteriorate communication quality.

In order to solve such problems as shadowing and multipath fading, Japanese Patent Application Laid-Open No.
No. 67990 discloses that a transmitting / receiving antenna of a road station is installed at two or more intervals so as to cross a traffic lane of a vehicle, and transmission information from each transmitting / receiving antenna to a mobile station is repeatedly transmitted at different transmission timings. What is done is described.

[0005]

Problems to be Solved by the Invention
In the device described in Japanese Patent Publication No. 0, the same transmission information is transmitted from a plurality of transmission / reception antennas by time division so that the transmission signals do not overlap, so that the information amount of one transmission information must be reduced. There is a problem.

Therefore, when such mobile communication is performed, OFDM (Orthogonal Frequency Division Multipl
exing) It is conceivable to perform communication between a road station and a mobile station using a modulation scheme.

FIG. 13 shows a configuration of a mobile communication system when the OFDM system is used. TX1 and TX2 denote transmitting antennas of a road station, RX1 denotes a receiving antenna of a mobile station installed in the vehicle 1, and 2 denotes another passing vehicle (in the figure, a radio-controlled vehicle such as a large vehicle). The transmission antennas TX1 and TX2 are installed in a direction crossing the traveling lane of the vehicle. Further, the OFDM signal W1 is reflected from an obstacle such as a wall from the transmitting antenna TX1 and is reflected by the receiving antenna R1.
Reflected wave (indirect wave) incident on X1, OFDM signal W2
Is a reflected wave reflected from another transmitting vehicle 2 from the transmitting antenna TX2 and incident on the receiving antenna RX1, and the OFDM signal W
Reference numeral 3 indicates a direct wave incident from the transmitting antenna TX2 to the receiving antenna RX1. Note that the transmitting antenna TX1
Is reflected by another passing vehicle 2 and does not reach the receiving antenna RX1.

The OFDM signal is a signal in which a part of data (DATA) is added to the head of a transmission signal as a guard interval (GI). Here, when two or more same OFDM signals are transmitted and their GI periods are overlapped and received, they can be received satisfactorily, but if the GI periods do not overlap, they can be received with other DATA. Since the reception is mixed, the communication quality is degraded. In the case of FIG. 13, the GI of the received OFDM signal W3
Since the periods and the GI periods of the OFDM signals W2 and W1 are received without overlapping, there is a problem that communication quality is deteriorated.

In this case, it is conceivable to set the GI period to be long so that the GI periods of the direct wave and the reflected wave overlap, but this is not preferable because the amount of information to be transmitted is reduced.

[0010] The above-mentioned problem that occurs when two or more identical OFDM signals are transmitted is also caused by communication in an environment where shadowing and multipath fading are problematic, in addition to the case of performing mobile communication. Can occur.

The present invention has been made in view of the above problems, and has as its object to enable reception in a communication environment in which two or more OFDM signals are transmitted without deteriorating communication quality.

It is another object of the present invention to prevent the problem of shadowing and multipath fading in such communication (the problem of multipath fading in an environment where shadowing is not a problem).

[0013]

According to the first aspect of the present invention, a first receiving antenna (RX1) for receiving left-handed polarized waves and a second receiving antenna (RX1) for receiving right-handed polarized waves are provided. A transmitter for transmitting an OFDM signal to a receiver having a receiving antenna (RX2)
A first transmitting antenna (TX1) for transmitting a signal in one of right-handed polarization and left-handed polarization, and a polarization of the same one of the right-handed polarization and left-handed polarization as the first transmission antenna. OFDM with the same timing from the second transmitting antenna (TX2) for transmitting by radio waves and the first and second transmitting antennas.
The transmitter is characterized by having transmission circuits (10 to 12) for transmitting signals.

An OFDM signal transmitted from the first and second transmitting antennas of the transmitter is received by the first and second receiving antennas of the receiver at one of the receiving antennas having the same polarization as the direct wave, Since the reflected wave is received by the other receiving antenna, each receiving process can be performed without interference. Therefore, in communication in an environment where two or more OFDM signals are transmitted, reception can be performed without deteriorating communication quality.

Further, there is an obstacle between the first transmitting antenna of the transmitter and the receiver and / or between the second transmitting antenna of the transmitter and the receiver, so that the direct wave reaches one of the receiving antennas. Even if it is impossible, if there is a reflected wave, it can be received by the other receiving antenna, so that the problem of shadowing can be prevented. Further, since the direct wave is received by one receiving antenna and the reflected wave is received by the other receiving antenna, the problem of multipath fading can be prevented.

According to the first aspect of the present invention, the transmitting circuit has a distributor (12) for distributing an OFDM signal to be transmitted, as in the second aspect of the present invention. OFDM signals transmitted from the first and second transmission antennas at the same timing.

According to the third aspect of the present invention, there is provided a receiver including a first receiving antenna (RX1) for receiving left-handed polarized wave and a second receiving antenna (RX2) for receiving right-handed polarized wave. On the other hand, a transmitter for transmitting an OFDM signal,
The transmitter is characterized by including a transmission antenna (TX1) for transmitting an FDM signal in one of right-handed polarization and left-handed polarization, and a transmission circuit (10, 11) for transmitting an OFDM signal from the transmission antenna. .

If the transmitter has one transmitting antenna,
If there is an obstacle between the transmitting antenna of the transmitter and the receiver, direct waves may not reach the receiving antenna of the receiver, which may cause shadowing problems.However, communication in an environment where shadowing is not a problem Is performed, the direct wave is received by one receiving antenna of the receiver, and the reflected wave is received by the other receiving antenna, so that the problem of multipath fading can be prevented.

According to a fourth aspect of the present invention, there is provided a receiver for receiving an OFDM signal transmitted from the transmitter according to the first to third aspects, wherein the first receiving antenna (RX1) receives a left-handed polarized wave. ), A second receiving antenna (RX2) for receiving the right-handed polarized wave, and a receiving circuit (21 to 26, for performing reception processing based on signals received by the first and second receiving antennas).
27, 28, 29 to 36).

[0020] In the receiver according to the fourth aspect, the receiving circuit may be configured such that the first one of the signals received by the first and second receiving antennas is the same as the invention according to the fifth aspect. One that performs signal processing based on a signal or one of the signals as described in claim 6 so that the guard interval period overlaps with each signal received by the first and second receiving antennas. A signal that is delayed from the other signal and is processed by synthesizing the delayed one signal and the other signal, or received by the first receiving antenna as in the invention according to claim 7. It is possible to receive the signal and perform error detection on the signal, and also perform the reception processing on the signal received by the second receiving antenna to detect the error, and extract the received signal based on the result of both error detections. That.

According to an eighth aspect of the present invention, there is provided a transmitter for transmitting an OFDM signal to a receiver having a receiving antenna (RX1) for receiving at least one of right-handed polarization and left-handed polarization. A first transmitting antenna (TX1) for transmitting an OFDM signal with right-handed polarization and a second transmitting antenna (TX2) for transmitting OFDM signal with left-handed polarization
And OFDM transmitted from the first and second transmitting antennas
When a signal is received at the receiving antenna, the respective OF
So that the guard interval periods of the DM signal overlap,
OF at different timings from the first and second transmitting antennas
A transmitter including transmission circuits (10 to 13) for transmitting DMs is characterized.

As described above, even if the transmitter is provided with the transmitting antenna for transmitting the right-handed polarized wave and the transmitting antenna for transmitting the left-handed polarized wave, the OFDM received by the receiving antenna of the receiver may be provided.
If the guard interval periods of the signals overlap each other, it is possible to perform the reception process more favorably with the signal that receives the direct wave and the reflection.

In this case, as the transmission circuit, a distributor (12) for distributing an OFDM signal to be transmitted and one of the OFDM signals distributed by the distributor are used as the other. And a delay circuit (13) for further delaying.

According to a tenth aspect of the present invention, there is provided a receiver for receiving an OFDM signal transmitted from the transmitter according to the eighth or ninth aspect, wherein the receiver receives at least one of a right-handed polarized wave and a left-handed polarized wave. Receiving RX (RX1), and a receiving circuit (25,
26).

Further, in the transmitter according to the first, second, eighth and ninth aspects, the first and second transmission antennas are installed apart from each other in a direction crossing the lane in which the vehicle travels, and the receiver is installed. If the OFDM signal is transmitted to the vehicle, the communication can be performed without causing problems of shadowing and multipath fading by applying to a mobile communication system.

The symbols in parentheses of the above means are as follows:
It shows the correspondence with specific means described in the embodiment described later.

[0027]

(First Embodiment) FIG. 1 shows a configuration of a mobile communication system according to a first embodiment of the present invention. TX1 and TX2 denote transmitting antennas of road stations (fixed stations), RX1 and RX2 denote receiving antennas of mobile stations installed in the vehicle 1, and 2 and 3 denote other passing vehicles. The transmission antennas TX1 and TX2 are installed in a direction crossing the traveling lane of the vehicle.

In this embodiment, communication between a road station and a mobile station is performed using circularly polarized waves. Therefore, T
X1 and TX2 are right-handed polarized wave transmitting antennas for transmitting right-handed polarized waves, RX1 is a left-handed polarized wave receiving antenna for receiving left-handed polarized waves, and RX2 is a right-handed polarized wave receiving antenna for receiving right-handed polarized waves. Has become. The right-handed polarized wave is received only by the right-handed polarized wave receiving antenna, and the left-handed polarized wave is received only by the left-handed polarized wave receiving antenna. The right-handed polarized wave becomes a left-handed polarized wave when reflected once by an obstacle such as a wall, and the left-handed polarized wave becomes a right-handed polarized wave when reflected once by an obstacle such as a wall.

In such a configuration, when no other passing vehicles 2 and 3 are present, as shown in FIG. 2, the direct wave W1 from the right-handed polarized wave transmitting antenna TX1 and the right-handed polarized wave transmitting antenna TX2 Is received by the right-handed polarized wave receiving antenna RX2. The reflected wave W2 transmitted from the right-handed polarized wave transmitting antenna TX1 and reflected by an obstacle such as a wall and the reflected wave W4 transmitted from the right-handed polarized wave transmitting antenna TX2 and reflected by an obstacle such as a wall are reflected by the left-handed reflection. Since it is polarized, it is received by the left-handed polarized wave receiving antenna RX1.

Since the GI periods of the OFDM signals W1 and W3 received by the right-handed polarized wave receiving antenna RX2 are overlapped with each other, reception processing can be favorably performed by these signals. The OFDM signals W4 and W2 received by the left-handed polarized wave receiving antenna RX1 are also
Since the periods overlap, reception processing can be favorably performed by these signals. Signal W1, W3 and signal W
4 and W2 do not overlap with each other in the GI period, but are received by different receiving antennas, so that respective receiving processes can be performed without interference. The GI period is set such that the GI periods of the direct waves overlap and the GI periods of the reflected waves also overlap in the environment of the road-vehicle communication.

FIG. 3 shows a case where another passing vehicle 2 exists on one side of the vehicle 1. In this case, the direct wave W1 from the right-handed polarized wave transmitting antenna TX1 is reflected by the passing vehicle 2 and does not reach the right-handed polarized wave receiving antenna RX2, but the other signals W2, W3, and W4 are the same as in FIG. Received by
Receiving processing can be performed favorably by those signals.

FIG. 4 shows another passing vehicle 2 on both sides of the vehicle 1.
3 is present. In this case, since the direct wave W1 from the right-handed polarized wave transmitting antenna TX1 is reflected by the passing vehicle 2 and the direct wave W3 from the right-handed polarized wave transmitting antenna TX2 is reflected by the passing vehicle 3, the signals W1 and W3 are Although it does not reach the right-handed polarized wave receiving antenna RX2, other signals W
2, and W4 are received in the same manner as in the case of FIG. 2, and the reception processing can be favorably performed by those signals.

FIG. 5 shows the configuration of a transmitter of a road station in this embodiment. The data to be transmitted is modulated by the OFDM modulator 10 and converted to an RF signal by the IF / RF unit 11, then distributed by the distributor 12, and transmitted from the right-handed polarization transmission antennas TX1 and TX2, respectively.

FIG. 6 shows the configuration of the receiver of the mobile station in this embodiment. Right-handed polarized wave receiving antennas RX1, RX
2 are input to the power level detectors 21 and 22, and the respective power levels are detected. The first arriving wave detector 23 receives the reception antenna R based on the power level detected by the power level detectors 21 and 22.
Which of X1 and RX2 has received the incoming wave first is detected, and the switch 24 is switched and controlled so that the signal of the first incoming wave is passed. The signal passed through the switch 24 is sent to an RF / IF unit 25 for IF
The signal is converted to a signal, demodulated by the OFDM demodulator 26,
Taken out as TA. Note that the first arriving wave detector 2
3 maintains the switching control of the switch 24 at that time until the signal of the completion of reception is output after the detection of the first arriving wave.

As described above, according to this embodiment,
The roadside station transmits right-handed polarized waves at the same timing from two right-handed polarized wave transmitting antennas TX1 and TX2 arranged at a predetermined interval, and the mobile station transmits a direct wave using the right-handed polarized wave receiving antenna RX2. Detect and detect left-handed polarized reception antenna RX
1 detects the reflected wave. Therefore, as described with reference to FIG. 2 to FIG. 4, it is possible to perform good reception without the problem of shadowing and multipath fading. (Second Embodiment) The GI period of the direct waves W1, W3 and the GI period of the reflected waves W2, W4 are shifted by a predetermined time as shown in FIGS. For this reason, in the first embodiment described above, the receiver of the mobile station performs the receiving process using the signal that has received the first arriving wave.
However, the GI period of the direct waves W1 and W3 and the reflected waves W2 and W
4 is determined in advance according to the use environment of this communication system so that the GI period of 4 overlaps, and if the signals receiving the direct waves W1 and W3 are delayed by the time difference, the direct waves W1 and W3 are changed. Reception processing can be performed using the received signal and the received signals of the reflected waves W2 and W4.

Therefore, in this embodiment, the direct waves W1,
The signal that has received W3 is delayed by a predetermined time, and the delayed signal and the signals that have received the reflected waves W2 and W4 are combined and reception processing is performed. FIG. 7 shows the configuration of the receiver of the mobile station in this case. Right-handed polarized wave receiving antenna RX
2 is delayed by a predetermined time by the delay circuit 27, and the delayed signal is combined in the combiner 28 with the signal received by the left-handed polarization receiving antenna RX1. The combined signal is input to the RF / IF unit
The signal is converted to an F signal, demodulated by an OFDM demodulator 26, and
Retrieved as ATA. (Third Embodiment) In the first embodiment described above, the reception processing is performed based on the signal of the first arriving wave. However, in this embodiment, the right-handed polarized wave receiving antenna RX2
The error detection is performed on the signal obtained by performing the reception processing on the signal received at step (1) and the signal received at the left-handed polarized wave reception antenna RX1, and a more correct signal (a signal with less error) is extracted as DATA.

FIG. 8 shows the configuration of the receiver of the mobile station in this embodiment. The signal received by the left-handed polarized wave receiving antenna RX1 is converted into an IF signal by the RF / IF unit 29, and
After being demodulated by the FDM demodulator 30, error detection is performed by an error detector 31. In addition, a right-handed polarized wave receiving antenna RX2
Is received by the RF / IF unit 32, converted into an IF signal, demodulated by the OFDM demodulator 33, and then subjected to error detection by the error detector. The results detected by the two error detectors 31 and 34 are compared by a comparator 35, and the switching of the switching unit 36 is controlled so that the more correct DATA is output from the switching unit 36. (Fourth Embodiment) In the first to third embodiments described above, the right-handed polarized wave transmitting antennas TX1 and TX2 are provided on the road station, and the left-handed polarized wave receiving antenna RX1 and the right-handed polarized wave receiving antenna RX2 are provided on the mobile station. The right-handed polarized wave transmitting antenna TX1 and the left-handed polarized wave transmitting antenna TX are provided on the road station.
2 and one right-handed polarization receiving antenna RX1
Can be provided.

FIG. 9 shows the configuration of the mobile communication system according to this embodiment. The direct wave W1 from the right-handed polarized wave transmitting antenna TX1 and the reflected wave (right-handed polarized wave due to reflection) W2 reflected from an obstacle such as a wall from the left-handed polarized wave transmitting antenna TX2 receive right-handed polarized wave reception. Each is received by the antenna RX1. Note that a direct wave W3 from the left-handed polarized wave transmitting antenna TX2 and a reflected wave (reflected into a left-handed polarized wave) W4 reflected from an obstacle such as a wall from the right-handed polarized wave transmitting antenna TX1 are left-handed polarized waves. Therefore, it is not received by the right-handed polarized wave reception antenna RX1.

In this way, since the direct wave and the indirect wave can be received by the receiving antenna of the mobile station, the reception can be performed without causing the problems of shadowing and multipath fading. However, the direct wave W1 from the right-handed polarized wave transmitting antenna TX1 and the left-handed polarized wave transmitting antenna T
A reflected wave W2 reflected from an obstacle such as a wall from X2 reaches the right-handed polarized wave reception antenna RX1 of the mobile station with a time lag. Therefore, if the GI periods of both received signals do not overlap,
Good reception processing is not possible. Therefore, in this embodiment, after transmission from the left-handed polarized wave transmitting antenna TX2, a predetermined time elapses, the right-handed polarized wave transmitting antenna TX1 is transmitted.
, And the GI periods of the two signals arriving at the right-handed polarized wave receiving antenna RX1 overlap each other.

FIG. 10 shows a configuration of a transmitter of a road station in this embodiment. The data to be transmitted is modulated by the OFDM modulator 10, converted into an RF signal by the IF / RF unit 11, and then distributed by the distributor 12. One of the divided signals is transmitted as it is from the left-handed polarization transmitting antenna TX2, and the other of the divided-out signals is delayed by a delay circuit 13 for a predetermined time and then transmitted to the right-handed polarization transmitting antenna TX1.
Sent from

FIG. 11 shows a configuration of a receiver of a mobile station in this embodiment. The signal received by the right-handed polarized wave receiving antenna TR1 is converted into an IF signal by the RF / IF unit 25, demodulated by the OFDM demodulator 26, and extracted as DATA. (Other Embodiments) In the first to third embodiments, the use of a right-handed polarized wave transmitting antenna for transmitting right-handed polarized waves has been described as the transmitting antennas TX1 and TX2 of the roadside station. The present invention can be similarly implemented using a left-handed polarized wave transmitting antenna for transmission. In this case, in the second embodiment, a delay circuit 27 is provided for the signal received by the right-handed polarized wave reception antenna RX2. Further, the number of transmission antennas is not limited to two, and may be larger.

In the fourth embodiment, the receiving antenna RX1 of the mobile station uses a right-handed polarized wave receiving antenna. However, a left-handed polarized wave receiving antenna may be used. Both a receiving antenna and a left-handed polarized wave receiving antenna may be used.

In the first to fourth embodiments, communication between the transmitter at the road station and the receiver at the mobile station has been described. However, the receiver is installed at the road station, and the transmitter is installed at the mobile station. It is installed so that bidirectional communication can be performed between roadside stations and mobile stations.

The transmitting antennas TX1 and TX of the road station
2 may be installed above the lane without being on both sides of the lane as long as it is installed apart from the lane in which the vehicle travels.

Although the first to fourth embodiments have been described as applied to a mobile communication system, they can be similarly applied to a communication system in an environment where shadowing and multipath fading are problematic. it can. In this case, in an environment where shadowing is not a problem and multipath fading is a problem, as shown in FIG.
Communication may be performed using one right-handed polarized wave transmitting antenna TX1. In this case, the transmitter of the road station is as shown in FIG.
6 is configured without the distributor 12, and the receiver of the mobile station is configured in the same manner as that shown in FIGS.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a mobile communication system according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the mobile communication system shown in FIG. 1;

FIG. 3 is a diagram provided to explain an operation of the mobile communication system shown in FIG. 1;

FIG. 4 is a diagram provided for describing an operation of the mobile communication system shown in FIG. 1;

FIG. 5 is a diagram illustrating a configuration of a transmitter of a road station according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a mobile station receiver according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of a mobile station receiver according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a configuration of a mobile station receiver according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a configuration of a mobile communication system according to a fourth embodiment of the present invention.

FIG. 10 is a diagram illustrating a configuration of a transmitter of a road station according to a fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating a configuration of a receiver of a mobile station according to a fourth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a mobile communication system according to another embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of a conventional mobile communication system.

[Explanation of symbols]

TX1, TX2... Transmission antennas on the road station, RX1, RX
2 ... receiving antenna of mobile station, 10 ... OFDM modulator, 1
DESCRIPTION OF SYMBOLS 1 ... IF / RF part, 12 ... Distributor, 13 ... Delay circuit, 2
1, 22 ... power level detector, 23 ... first arrival wave detector, 24, 36 ... switch, 25, 29, 32 ... RF
/ IF section, 26, 30, 33 ... OFDM demodulator, 27 ...
Delay circuit, 28 ... synthesizer, 31, 34 ... error detector, 3
5 ... Comparator.

Claims (11)

[Claims] 1. An OFDM signal is transmitted to a receiver having a first receiving antenna (RX1) for receiving left-handed polarization and a second receiving antenna (RX2) for receiving right-handed polarization. A first transmitting antenna (TX1) for transmitting an OFDM signal in one of right-handed polarization and left-handed polarization; and a first transmission antenna (TX1) for transmitting the OFDM signal in the right-handed polarization and left-handed polarization. A second transmitting antenna (TX2) that transmits with the same polarization as the first transmitting antenna, and a transmitting circuit (10 to transmit the OFDM signal at the same timing from the first and second transmitting antennas, respectively)
12). 2. The transmitting circuit has a distributor (12) for distributing an OFDM signal to be transmitted, and transmits the OFDM signal distributed by the distributor from the first and second transmitting antennas at the same timing. 2. The method according to claim 1, wherein
Transmitter. 3. An OFDM signal is transmitted to a receiver having a first receiving antenna (RX1) for receiving left-handed polarization and a second receiving antenna (RX2) for receiving right-handed polarization. A transmitting antenna (TX1) for transmitting an OFDM signal in one of right-handed and left-handed polarized waves; and a transmitting circuit (10, 11) for transmitting the OFDM signal from the transmitting antenna. With transmitter. 4. A receiver for receiving an OFDM signal transmitted from the transmitter according to any one of claims 1 to 3, wherein the first reception antenna (RX1) receives left-handed polarization. A second receiving antenna (RX2) for receiving right-handed polarized waves; and a receiving circuit (21 to 26, 27, 28, 2) for performing reception processing based on signals received by the first and second receiving antennas.
9-36). 5. The signal processing apparatus according to claim 4, wherein the receiving circuit performs the signal processing based on a signal received first by the signals received by the first and second receiving antennas. Receiver. 6. The receiving circuit delays one signal with respect to each signal received by the first and second receiving antennas so that a guard interval period overlaps with the other signal, and delays the one signal with respect to the other signal. The receiver according to claim 4, wherein the signal processing is performed by synthesizing the other signal and the other signal. 7. The receiving circuit receives a signal received by the first receiving antenna and performs error detection on the signal, and also receives a signal received by the second receiving antenna and performs error detection on the received signal. The receiver according to claim 4, wherein the received signal is extracted based on a result of the error detection. 8. A transmitter for transmitting an OFDM signal to a receiver having a receiving antenna (RX1) for receiving at least one of a right-handed polarized wave and a left-handed polarized wave, wherein A first transmitting antenna (TX1) for transmitting with a polarization, a second transmitting antenna (TX2) for transmitting an OFDM signal with a left-handed polarization, and an OFDM transmitted from the first and second transmitting antennas.
When a signal is received by the receiving antenna, a transmitting circuit (10) that transmits the OFDM from the first and second transmitting antennas at different timings so that the guard interval periods of the respective OFDM signals overlap.
To 13). 9. The transmission circuit includes a distributor (12) for distributing an OFDM signal to be transmitted, and a delay circuit (13) for delaying one of the OFDM signals distributed by the distributor from the other. 9. The transmitter according to claim 8, wherein: 10. A receiver for receiving an OFDM signal transmitted from the transmitter according to claim 8 or 9, wherein the receiving antenna (RX1) receives at least one of right-handed polarization and left-handed polarization. And a receiving circuit (25, 26) for performing signal processing on a signal received by the receiving antenna. 11. The first and second transmitting antennas are installed apart from each other in a direction crossing a lane in which a vehicle travels, and the OFDM is installed in a vehicle in which the receiver is installed.
10. A signal is transmitted.
A transmitter according to any one of the preceding claims.