JP2000209145A - Multi-carrier signal transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-carrier signal transmitter-receiver that improves throughput without increasing the load of a terminal in the case of multiple address transmission at a high transmission rate so as to provide gain by diversity to all terminals. SOLUTION: The multi-carrier signal transmitter-receiver is provided with a subcarrier signal reception state measurement circuit 70 that measures a reception state from a received subcarrier signal for each antenna series, classifies the result for each communication unit and provides an output, a subcarrier signal detection synthesis circuit 50 that detects a received subcarrier signal as to each antenna series for each frequency and synthesizes detection results of each antenna series in the unit of frequencies, an antenna selection circuit 80 for each subcarrier frequency that selects an antenna where all reception states of a plurality of communication units being diversity control objects satisfy a prescribed condition on the basis of the reception state measurement result for each communication unit for each frequency, and a transmission code antenna series assignment circuit 100 that assigns a transmission code to a subcarrier frequency corresponding to each antenna series on the basis of the selection information of the antenna for each subcarrier frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-carrier signal transmitting / receiving apparatus for transmitting / receiving a digital radio signal using a plurality of carriers, and more particularly to a case where the same signal is simultaneously transmitted from a base station to a plurality of communication targets. The present invention relates to a multi-carrier signal transmitting / receiving apparatus that is advantageous to:

[0002]

2. Description of the Related Art In a case where a digital wireless communication apparatus having a low transmission rate is used in a multipath fading environment, a sudden drop in received power is caused by application of reception diversity and transmission diversity using a plurality of antennas. Can be suppressed. However, when the transmission speed is increased, the transmission band becomes wider than the frequency distortion due to multipath, so that the diversity effect cannot be expected in single carrier transmission using a single carrier. Therefore, band division type reception diversity has been proposed in which the band per carrier is reduced by employing multi-carrier transmission and reception diversity is performed for each band of each carrier.

[0003] However, in communication such as mobile communication that requires a reduction in the size of the terminal device and a reduction in power consumption, reception diversity in the terminal device is not preferable. That is, the number of antennas of the terminal device should not be increased.

On the other hand, a transmission diversity technique in a base station has been proposed as a technique for obtaining a diversity effect without imposing a burden on a terminal device (Reference: Hideyuki Tak).
ahashi and Masao Nakagawa, "Antenna and Multi-Carri
er Combined Diversity System, "IEICE Trans. Commun
i., Vol. E-79-B, no. 9, Sep. 1996). A conventional technique of transmission diversity in a base station will be described with reference to FIG. The multicarrier signal transmitting / receiving apparatus shown in FIG. 10 is used as a base station, and transmits / receives a radio signal to / from a plurality of terminal apparatuses (not shown).

First, the circuit on the receiving side in FIG. 10 will be described. The multicarrier signal transmitted by the terminal device is shown in FIG.
The signal is received by a plurality of independent antennas 210 and guided to a circuit on the receiving side by a demultiplexing circuit 220. That is, the received multicarrier signal is input to the low frequency conversion circuit 230 independent for each antenna sequence, and is converted into a low frequency signal suitable for signal processing. The signal converted to the low frequency is input to a subcarrier signal separation circuit 240 independent for each antenna sequence.

[0006] Each subcarrier signal separation circuit 240
Converts the frequency components of a plurality of subcarriers (subcarriers) included in an input multicarrier signal from each other and outputs the separated subcarrier signals as parallel signals. The signal output from each subcarrier signal separation circuit 240 is a subcarrier signal reception power measurement circuit 27.
0 and the subcarrier signal detection selection circuit 250 are input.

The subcarrier signal detection selection circuit 250
After detecting the input subcarrier signal for each antenna sequence, a signal having the largest signal strength among the detected signals of the plurality of detected subcarrier frequency components is selected. The signal of the selected subcarrier frequency component is decoded by the transmission bit estimation circuit 260 to determine an estimated transmission bit. On the other hand, the subcarrier signal reception power measurement circuit 270 measures the reception power of the subcarrier signal for each antenna sequence,
The measurement result is output to the antenna selection circuit 280 for each subcarrier frequency for each subcarrier frequency.

[0008] Antenna selection circuit 2 for each subcarrier frequency
80, based on the reception power measurement result of the subcarrier signal reception power measurement circuit 270, estimates the specific antenna at which the maximum reception power of each subcarrier frequency is obtained at the next base station transmission frame timing by the least square method,
Transmit code antenna sequence assignment circuit 300
To communicate. This antenna information is used at the next base station transmission frame timing.

Next, the circuit on the transmitting side will be described. The transmission bit is converted into a transmission code sequence by the transmission code forming circuit 290 and input to the transmission code antenna sequence assignment circuit 300. Transmission code antenna sequence assignment circuit 300
Based on the antenna information from the antenna selection circuit 280 for each subcarrier frequency obtained at the previous reception frame timing, the transmission code sequence is associated with the subcarrier frequency used in the multicarrier signal generation circuit 310, and Assign to antenna series.

[0010] Further, among a plurality of subcarrier frequencies included in the multicarrier signal, a signal having an amplitude of 0 is assigned to a subcarrier frequency not used for transmission. A parallel signal of a plurality of subcarrier frequencies output from the transmission code antenna sequence assignment circuit 300 is input to a multicarrier signal generation circuit 310 independent for each antenna sequence, and is converted into one multicarrier signal.

Each multi-carrier signal generation circuit 310
Outputs the multi-carrier signal to the high frequency conversion circuit 3
20 converts the signal to a predetermined transmission frequency. The multicarrier signal converted to the transmission frequency is output to an individual antenna 210 via a branching circuit 220 for each antenna sequence, and transmitted from the antenna 210 to a predetermined terminal station as a radio signal.

A multi-carrier signal transmitting / receiving apparatus shown in FIG. 10 is used for a base station, a multi-carrier signal from a terminal station is received by a plurality of antennas of the base station, and an antenna having a good reception state is selectively used for each sub-carrier frequency. Multi-carrier signal transmission diversity technology that transmits from the base station
TDMA-TDD (Time Division Multiple Access-Ti
me Division Duplex)
It is known as a technique for improving the bit error rate by reducing the load on the terminal device.

[0013]

In the above-described multi-carrier signal transmission diversity technique, attention is paid only to the reception state of a single terminal device, and the antenna having the highest reception power is selected for each subcarrier frequency. However, when the same signal is simultaneously transmitted (broadcast transmission) to a plurality of terminal devices, the antenna that can obtain the maximum reception power for each terminal device differs for each terminal device. Therefore, although the conventional technology can provide a diversity gain to some terminal devices, it is difficult to provide a diversity effect to all terminal devices.

For example, in the case of performing broadcast communication with the base station frame configuration shown in FIG. 9, since a channel is allocated to each terminal device on the uplink, it is necessary to select the best antenna for each terminal device. Is possible. However, since there is only one channel in the downlink, the best antenna must be selected only for a specific terminal device.

Particularly, when broadcasting information requiring high reliability, the communication quality must be kept uniform for all terminal devices, and an error correction technique such as retransmission control is required. . However, if there is at least one terminal device having a poor reception state, retransmission frequently occurs, so that the throughput of the entire system is greatly reduced. If a multi-carrier signal reception diversity technology is used in which a plurality of antennas are provided in the reception terminal device and reception diversity is performed for each subcarrier,
Diversity gain can be obtained in all terminal devices. However, the multi-carrier signal receiving diversity technique has a heavy burden on the terminal device, and is disadvantageous in terms of miniaturization and reduction in power consumption.

According to the present invention, even when the same information is simultaneously transmitted to a plurality of terminal devices at a high transmission rate, the throughput characteristics of the entire system can be improved without increasing the device load on the terminal side, and the specific terminal device can be improved. It is another object of the present invention to provide a multi-carrier signal transmitting / receiving apparatus capable of providing not only terminal apparatuses but also gains due to diversity.

[0017]

A multi-carrier signal transmitting / receiving apparatus for transmitting / receiving a wireless multi-carrier signal including a plurality of carrier frequency components to / from a plurality of communication apparatuses is provided. While transmitting a multi-carrier signal received by a plurality of antennas to a circuit on the receiving side, a demultiplexing circuit for transmitting a multi-carrier signal output from a circuit on the transmitting side to the plurality of antennas, A low-frequency conversion circuit that converts a multi-carrier signal received by an antenna into a low-frequency multi-carrier signal suitable for signal processing for each antenna sequence and outputs the multi-carrier signal, and for each antenna sequence, from the low-frequency conversion circuit. A subcarrier signal separation circuit that separates and outputs a plurality of subcarrier signals included in the output multicarrier signal, For each antenna sequence, a subcarrier signal reception state measurement circuit that measures the reception state of the subcarrier signal output from the subcarrier signal separation circuit, classifies the measurement result for each communication device that has transmitted the signal, and outputs the result. After detecting the subcarrier signal output from the subcarrier signal separation circuit for each antenna sequence for each subcarrier frequency, a subcarrier signal detection and synthesis circuit that synthesizes the detection result of each antenna sequence in subcarrier frequency units A transmission bit estimation circuit for estimating transmission bits transmitted by the communication device from a reception code sequence appearing at an output of the subcarrier signal detection / synthesis circuit; and a reception unit for each communication device output from the subcarrier signal reception state measurement circuit. Based on the status measurement results, a plurality of diversity control targets An antenna selection circuit for each subcarrier frequency for selecting an antenna in which all reception states of the communication device satisfy a predetermined condition, for each subcarrier frequency, and a transmission code formation circuit for forming a transmission code from transmission bits to be transmitted. A transmission code antenna sequence allocating circuit for allocating an output of the transmission code forming circuit to a subcarrier frequency corresponding to each antenna sequence based on information on an antenna for each subcarrier frequency output from the antenna selection circuit for each subcarrier frequency A multi-carrier signal generation circuit that selectively outputs only a sub-carrier frequency to which a transmission code sequence is allocated by the transmission code antenna sequence allocation circuit and outputs a multi-carrier signal corresponding to a corresponding transmission code sequence; For the antenna series, the multi-carrier signal generation circuit And a high-frequency conversion circuit for converting the output signal of the above into a high-frequency signal suitable for transmission from the antenna based on a predetermined signal.

In the present invention, the sub-carrier-frequency-based antenna selection circuit determines all of the plurality of communication apparatuses to be diversity-controlled based on the reception state measurement result of each communication apparatus output from the sub-carrier signal reception state measurement circuit. An antenna to be used for transmission is selected for each subcarrier frequency so that the reception state of the subcarrier satisfies a predetermined condition. As in the related art, when an antenna that provides the maximum reception power for a specific terminal device is selected, the reception state of another specific terminal device may be significantly deteriorated. However, even with the second antenna other than the first antenna that provides the maximum reception power for a specific terminal device, a relatively good reception state is often obtained.

According to the present invention, an antenna to be used for transmission is selected for each subcarrier frequency such that all reception states of a plurality of communication apparatuses to be controlled for diversity satisfy predetermined conditions. It is possible to avoid selecting an antenna whose reception condition is greatly deteriorated. That is, an antenna capable of obtaining relatively uniform and good reception power for all communication devices is selected for each subcarrier frequency. Therefore, deterioration due to fading can be minimized for all communication devices, and a certain diversity effect can be expected for all communication devices.

According to a second aspect of the present invention, in the multicarrier signal transmitting and receiving apparatus according to the first aspect, based on the received bit sequence output from the transmission bit estimation circuit, a bit error check within a certain section and extraction of error information at the time of transmission are performed. Further, a communication quality measurement circuit for performing communication quality measurement of each communication device is further provided, and the antenna selection circuit for each subcarrier frequency, a reception state measurement result for each communication device output from the subcarrier signal reception state measurement circuit, Based on the communication quality information of each communication device output from the communication quality measurement circuit, a plurality of communication devices to be subjected to diversity control is specified, and for the plurality of communication devices to be subjected to the diversity control, Is selected for each frequency of a subcarrier.

According to the present invention, it is possible to control the diversity gain according to the communication quality of the communication device. For example, it is also possible to select only the communication device whose communication quality has deteriorated and control the diversity gain. Also, in communication for performing retransmission control, NACK (Not Acknowledgem
ent) The antenna may be selected so as to provide diversity gain only to the communication device that has transmitted the signal.

According to a third aspect of the present invention, in the multicarrier signal transmitting and receiving apparatus according to the first aspect, a carrier frequency oscillation circuit for outputting a carrier signal is further provided, and the carrier signal output from the carrier frequency oscillation circuit is converted to all of the low frequency conversion circuits. And to all of the high frequency conversion circuits. Since a common carrier signal is input to all of the low frequency conversion circuits and all of the high frequency conversion circuits, the subcarrier signal of the reception side circuit and the subcarrier signal of the transmission side circuit are set to the same frequency. can do.

According to a fourth aspect of the present invention, in the multi-carrier signal transmitting and receiving apparatus according to the first aspect, based on the received bit sequence output from the transmission bit estimation circuit, a bit error check within a certain section and extraction of error information at the time of transmission are performed. A communication quality measurement circuit that performs communication to measure the communication quality of each communication target, and a carrier frequency oscillation circuit that supplies a common carrier signal to all the low frequency oscillation circuits and all the high frequency oscillation circuits are further provided. The antenna selection circuit for each subcarrier frequency, a reception state measurement result for each communication device output from the subcarrier signal reception state measurement circuit, and communication quality information of each communication device output from the communication quality measurement circuit A plurality of communication devices to be subjected to the diversity control are specified based on the plurality of communication devices, and a plurality of communication devices to be subjected to the diversity control are identified. Te, characterized in that all of the receiving state to select a predetermined condition is satisfied antenna for each frequency subcarrier.

According to the present invention, it is possible to reduce the influence of the frequency error of the carrier frequency. Claim 5
In the multicarrier signal transmitting / receiving apparatus according to any one of claims 1, 2, 3 and 4, the OFDM (Orthogonal Frequency Divide) is used for modulating the multicarrier signal.
ision Multiplexing).
It is characterized in that TDMA-TDD is adopted as a signal transmission method.

According to the present invention, the frequency use efficiency can be improved. Further, it becomes easy to use the reception state information at the time of transmission.

[0026]

(First Embodiment) An example of a multi-carrier signal transmitting / receiving apparatus according to the present invention will be described with reference to FIGS. This embodiment corresponds to claim 1.

FIG. 1 is a block diagram showing the configuration of the main part of the apparatus of this embodiment. FIG. 6 is a graph showing an example of the power distribution at the time of transmission by the base station according to the present invention. FIG. 7 is a graph showing an example of the power distribution at the time of transmitting a terminal station in the present invention.
In this embodiment, an antenna, a demultiplexing circuit, a low-frequency conversion circuit, a subcarrier signal separation circuit, a subcarrier signal reception state measurement circuit, a subcarrier signal detection and synthesis circuit, a transmission bit estimation circuit, and a subcarrier frequency antenna The selection circuit, the transmission code formation circuit, the transmission code antenna sequence assignment circuit, the multi-carrier signal generation circuit, and the high frequency conversion circuit are respectively composed of the antenna 10, the demultiplexing circuit 20,
Low frequency conversion circuit 30, subcarrier signal separation circuit 4
0, a subcarrier signal reception state measurement circuit 70, a subcarrier signal detection / combination circuit 50, a transmission bit estimation circuit 60,
Subcarrier frequency-based antenna selection circuit 80, transmission code formation circuit 90, transmission code antenna sequence assignment circuit 10
0, corresponding to the multicarrier signal generation circuit 110 and the high frequency conversion circuit 120.

In FIG. 1, a thin solid line represents a serial signal, and a thick solid line represents a parallel signal in which a plurality of independent signals are arranged in parallel. The multicarrier signal transmitting / receiving device illustrated in FIG. 1 transmits and receives a wireless multicarrier signal including a plurality of carrier frequency components to and from a plurality of communication devices. This multicarrier signal transmitting / receiving device is used, for example, as a wireless base station. A mobile terminal station or the like is assumed as a communication device of a communication partner.

In order to perform diversity communication, the multicarrier signal transmitting and receiving apparatus shown in FIG. 1 includes N independent antennas 10 (1) to 10 (1) to 1 used for transmission and reception.
0 (N) is provided. The demultiplexing circuit 20 includes the antenna 10
And transmits the multicarrier signal received from the circuit on the receiving side to the antenna 10. The demultiplexing circuit 20 includes the antenna 1
0 is independent of each other.

The receiving side circuit includes a low frequency conversion circuit 3
0, a subcarrier signal separation circuit 40, a subcarrier signal detection and synthesis circuit 50, and a transmission bit estimation circuit 60. The low frequency conversion circuit 30 and the subcarrier signal separation circuit 40 are independent for each series of the antenna 10. The low-frequency conversion circuit 30 converts a high-frequency multicarrier signal received by the antenna 10 into a low-frequency multicarrier signal suitable for signal processing and outputs the low-frequency multicarrier signal. The subcarrier signal separation circuit 40 is a low-frequency conversion circuit 30
A plurality of sub-carrier signals included in the multi-carrier signal output from are extracted, and the plurality of sub-carrier signals are output as parallel signals.

The subcarrier signal detection and synthesis circuit 50 detects the subcarrier signals output from the subcarrier signal separation circuits 40 (1) to 40 (N) for each sequence of the antenna 10 and for each frequency of the subcarrier. . Then, with respect to subcarrier signals having the same frequency, signals after detection obtained from a plurality of antenna sequences are combined. Therefore, the number of subcarrier signals corresponding to the number of subcarriers to be used is output from the subcarrier signal detection and synthesis circuit 50 in a parallel signal format. Transmission bit estimation circuit 6
0 estimates the transmission bit transmitted by the communication device on the transmission side from the received code sequence of the subcarrier signal appearing in the output of the subcarrier signal detection / combination circuit 50 and outputs it as a received bit sequence.

Subcarrier signal reception state measuring circuit 70
Measures the reception state of the subcarrier signal output from the subcarrier signal separation circuit 40 for each antenna 10 sequence. Then, the measurement results are classified and output for each communication device on the transmission side. Since the subcarrier signal reception state measurement circuit 70 grasps the communication device on the transmission side based on the identification code or the like included in the received signal, the output signal can be classified for each communication device on the transmission side.

Antenna selection circuit 8 for each subcarrier frequency
0 is an antenna in which all the reception states of the plurality of communication apparatuses to be diversity controlled satisfy predetermined conditions based on the reception state measurement result of each communication apparatus output from the subcarrier signal reception state measurement circuit 70. Select for each carrier frequency. The operation of the antenna selection circuit 80 for each subcarrier frequency will be described with reference to the examples shown in FIGS. 6 and 7, the horizontal axis represents frequency f, and the vertical axis represents power. In this example, two terminals TE1,
TE2 is used as a plurality of communication devices to be diversity controlled, and four subcarrier frequencies f1, f2, f3,
It is assumed that a multi-carrier signal including f4 is transmitted. The multi-carrier signal transmitting / receiving apparatus of FIG. 1 is used as a base station.

In the example of FIG. 7, when attention is paid only to the terminal TE1, both antennas A1 and A2 can obtain the maximum received power at the subcarrier frequency f2. However, focusing on the terminal TE2, the antenna A1 at the subcarrier frequency f2
Has a remarkably low received power. Therefore, if the received power for the terminal TE1 is the maximum subcarrier frequency f
When 2 is assigned to the antenna A1, the communication quality for the terminal TE2 is significantly deteriorated.

In order to prevent such remarkable deterioration in communication quality, the antenna selection circuit 80 for each subcarrier frequency is used.
Selects an antenna for which the reception state of all of the plurality of communication devices (TE1, TE2) satisfies a predetermined condition for each subcarrier frequency. In the example of FIG. 7, for the frequencies f1 and f4 of the subcarriers, the maximum received power cannot be obtained by using the antenna A1.
Sufficient received power is obtained for both E1 and TE2. In such a case, the antenna selection circuit 80 for each subcarrier frequency allocates the antenna A1 to the subcarrier frequencies f1 and f4 for transmission.

Similarly, the subcarrier frequencies f2 and f3
With respect to, the maximum received power cannot be obtained by using the antenna A2, but the two terminals TE1, TE2
In both cases, sufficient reception power can be obtained. In such a case, the antenna selection circuit 80 for each subcarrier frequency sets the antenna A2 to the frequency f2 or f3 of the subcarrier.
Is assigned for transmission.

Antenna selection circuit 8 for each subcarrier frequency
0 outputs information on the antenna selected for each subcarrier frequency. In the example of FIG. 7, the subcarrier frequency f
Antennas A, 1, f2, f3 and f4, respectively.
Information indicating 1, A2, A2 and A1 is output. Actually, the antenna selection circuit 80 for each subcarrier frequency
For each subcarrier frequency, the value of each evaluation function is examined to select an optimal antenna sequence.

As the evaluation function, for example, a result (sum) obtained by adding the result of weighting the reception power in each antenna sequence for all the communication devices to be controlled may be used. In this case, the antenna sequence having the largest value of the evaluation function may be selected as the optimal antenna sequence. Therefore, an antenna series in which the reception power of one of the communication devices is significantly reduced is not selected.

The transmission code forming circuit 90 shown in FIG. 1 forms a transmission code from a transmission bit sequence to be transmitted.
This transmission code is output as a parallel signal. The transmission code antenna sequence assignment circuit 100 assigns the transmission code output from the transmission code forming circuit 90 to each antenna sequence based on the information on the antenna for each subcarrier frequency input from the antenna selection circuit 80 for each subcarrier frequency. To the subcarrier frequency to be assigned.

For example, under the conditions shown in FIG.
1 and TE2, the transmission code to be broadcasted is allocated to the subcarrier frequencies f1 and f4, and the antenna A2 is allocated to the subcarrier frequencies f2 and f3. The subcarrier frequencies and antenna sequences are allocated as shown in FIG. 6 so that the transmission code is transmitted using the subcarrier frequencies f1 and f4 and the subcarrier frequencies f2 and f3 of the sequence of the antenna A2.

Multicarrier signal generation circuit 110 generates a multicarrier signal corresponding to the corresponding transmission code sequence by selectively using only the subcarrier frequencies to which the transmission code sequence is allocated by transmission code antenna sequence allocation circuit 100. And output. For example, under the conditions shown in FIGS. 6 and 7, the multicarrier signal generation circuit 110 for the sequence of the antenna A1 generates a multicarrier signal using only the subcarrier frequencies f1 and f4, and generates the components of the subcarrier frequencies f2 and f3. Is set to 0. In addition, a multi-carrier signal generation circuit 110 for a series of antennas A2
Generates a multicarrier signal using only the subcarrier frequencies f2 and f3,
Is set to zero.

The high frequency conversion circuit 120 is suitable for transmitting a signal output from the multicarrier signal generation circuit 110 from the antenna 10 based on a reference signal (for example, a carrier signal) output from a predetermined oscillator for each antenna series. To a high-frequency signal. Each high frequency conversion circuit 120
The high frequency signal output from the
The signals are input to the antennas 10 of the respective streams via 0, and are transmitted from each antenna 10 as wireless multicarrier signals.

(Second Embodiment) An example of the multicarrier signal transmitting / receiving apparatus of the present invention will be described with reference to FIG. This embodiment is a modification of the first embodiment and corresponds to claim 2. FIG. 2 is a block diagram showing the configuration of the main part of the apparatus according to this embodiment. In FIG. 2, elements corresponding to those in FIG. 1 are denoted by the same reference numerals.
In the following description, the description of the same parts as in the first embodiment will be omitted.

In this embodiment, the communication quality measuring circuit according to claim 2 corresponds to the communication quality measuring circuit 65. A communication quality measuring circuit 65 is added to the multi-carrier signal transmitting / receiving apparatus of FIG. The communication quality measuring circuit 65 measures the communication quality of each communication device by inspecting a bit error in a certain section and extracting error information at the time of transmission based on the received bit sequence output from the transmission bit estimation circuit 60. The result of the measurement is input to the antenna selection circuit 80 for each subcarrier frequency.

In the multi-carrier signal transmitting / receiving apparatus shown in FIG.
Based on the reception state measurement result of each communication device output from the subcarrier signal reception state measurement circuit 70 and the communication quality information of each communication device output from the communication quality measurement circuit 65, For each of the plurality of communication apparatuses, an antenna whose reception state satisfies a predetermined condition is selected for each subcarrier frequency.

Further, the antenna selection circuit 80 for each subcarrier frequency outputs the reception status measurement result for each communication device output from the subcarrier signal reception status measurement circuit 70 and the communication status of each communication device output from the communication quality measurement circuit 65. Based on the quality information, a plurality of communication devices to be subjected to the diversity control are specified. The subcarrier frequency-based antenna selection circuit 80 in FIG. 2 uses the following evaluation function values in order to select an optimal antenna sequence for each subcarrier frequency. That is, the reciprocal of the received power of each communication device in each antenna series is weighted by the communication quality information of each communication device output from the communication quality measurement circuit 65 so that the communication device having lower communication quality has a larger value. , And the result (total sum) obtained by adding the result for all communication apparatuses to be controlled is used.

In this case, the antenna sequence having the smallest evaluation function value is selected as the optimal antenna sequence. Therefore, an antenna series in which the reception power of one of the communication devices is significantly reduced is not selected. (Third Embodiment) An example of the multicarrier signal transmitting / receiving apparatus of the present invention will be described with reference to FIG. This embodiment is a modification of the first embodiment and corresponds to claim 3.

FIG. 3 is a block diagram showing the configuration of the main part of the apparatus of this embodiment. In FIG. 3, elements corresponding to those in FIG. 1 are denoted by the same reference numerals. In the following description, the description of the same parts as in the first embodiment will be omitted. In this embodiment, the carrier frequency oscillation circuit of claim 3 corresponds to the carrier frequency oscillation circuit 35.

The multi-carrier signal transmitting / receiving apparatus of FIG. 3 includes a carrier frequency oscillation circuit 35. The carrier frequency oscillating circuit 35 outputs signals of N carrier frequencies having different frequencies from each other. Signals of a plurality of carrier frequencies output from the carrier frequency oscillation circuit 35 are commonly applied to the high frequency conversion circuit 120 and the low frequency conversion circuit 30 belonging to the same antenna sequence.

(Fourth Embodiment) An example of a multicarrier signal transmitting / receiving apparatus according to the present invention will be described with reference to FIGS. This embodiment is a modification of the first embodiment, and corresponds to claims 4 and 5. FIG. 4 is a block diagram showing the configuration of the main part of the apparatus according to this embodiment. FIG.
FIG. 3 is a block diagram showing a specific configuration of a main part of the apparatus according to this embodiment. In FIG. 4, elements corresponding to those in FIG. 1 are denoted by the same reference numerals. In the following description, the description of the same parts as in the first embodiment will be omitted.

In this embodiment, the communication quality measuring circuit and the carrier frequency oscillating circuit of claim 4 correspond to the communication quality measuring circuit 65 and the carrier frequency oscillating circuit 35, respectively. In the multi-carrier signal transmitting / receiving apparatus of FIG. 4, a carrier frequency oscillation circuit 35 and a communication quality measurement circuit 65 are added. The carrier frequency oscillating circuit 35 outputs signals of N carrier frequencies having different frequencies from each other.

Each signal of a plurality of carrier frequencies output from the carrier frequency oscillation circuit 35 is commonly applied to the high frequency conversion circuit 120 and the low frequency conversion circuit 30 belonging to the same antenna sequence. The communication quality measuring circuit 65 measures the communication quality of each communication device by inspecting a bit error in a certain section and extracting error information at the time of transmission based on the received bit sequence output from the transmission bit estimation circuit 60. The result of the measurement is input to the antenna selection circuit 80 for each subcarrier frequency.

In the multi-carrier signal transmitting / receiving apparatus shown in FIG.
Based on the reception state measurement result of each communication device output from the subcarrier signal reception state measurement circuit 70 and the communication quality information of each communication device output from the communication quality measurement circuit 65, For each of the plurality of communication apparatuses, an antenna whose reception state satisfies a predetermined condition is selected for each subcarrier frequency.

The antenna selection circuit for each subcarrier frequency 80 measures the reception status of each communication device output from the subcarrier signal reception status measurement circuit 70 and the communication status of each communication device output from the communication quality measurement circuit 65. Based on the quality information, a plurality of communication devices to be subjected to the diversity control are specified. The antenna selection circuit 80 for each subcarrier frequency in FIG. 4 uses the following evaluation function values in order to select an optimal antenna sequence for each subcarrier frequency. That is, the reciprocal of the received power of each communication device in each antenna series is weighted by the communication quality information of each communication device output from the communication quality measurement circuit 65 so that the communication device having lower communication quality has a larger value. , And the result (total sum) obtained by adding the result for all communication apparatuses to be controlled is used.

In this case, the antenna sequence with the smallest evaluation function value is selected as the optimal antenna sequence. Therefore, an antenna series in which the reception power of one of the communication devices is significantly reduced is not selected. The multi-carrier signal transmitting / receiving apparatus of FIG. 4 can be configured as shown in FIG. 5 as an example. The multicarrier signal transmitting and receiving apparatus shown in FIG. 5 is configured to operate as a base station by applying orthogonal frequency division multiplexing (OFDM) as a multicarrier modulation scheme. Also,
TDM having a frame structure as shown in FIG. 9 as a transmission method
It is assumed that A-TDD is used.

In the multi-carrier signal transmitting / receiving apparatus shown in FIG. 5, each low-frequency conversion circuit 30 includes a multiplication circuit 31 and an analog-digital conversion circuit 32. Each subcarrier signal separation circuit 40 includes a serial-parallel conversion circuit 41 and an FFT (fast Fourier transform) circuit 42.

Each transmission bit estimation circuit 60 comprises a parallel-serial conversion circuit 61 and a decoding circuit 62. Each transmission code forming circuit 90 includes a serial-parallel conversion circuit 91 and an encoding circuit 92. Each multi-carrier signal generation circuit 110
It comprises an IFFT (Inverse Fast Fourier Transform) circuit 111 and a parallel-serial conversion circuit 112. Each high-frequency conversion circuit 120 includes a digital-analog conversion circuit 121 and a multiplication circuit 122.

First, the operation of the multicarrier signal transmitting / receiving apparatus (base station apparatus) shown in FIG. 5 at the base station side reception frame timing will be described. The wireless multi-carrier signal transmitted from the terminal side includes a plurality of antennas 1 independent of each other.
0, and the received multicarrier signal is transmitted to the receiving side circuit via the branching circuit 20 for each antenna sequence.

Inside the low-frequency conversion circuit 30 provided in the circuit on the receiving side, the multiplication of the common carrier frequency in the multiplying circuit 31 removes the harmonic components, thereby forming a low-frequency multicarrier signal suitable for signal processing. Is converted. The carrier frequency signal is input from the carrier frequency oscillation circuit 35. The output of the multiplying circuit 31 is converted into a digital signal by the analog-digital conversion circuit 32 for each antenna series.

The digital signal output from the analog-digital conversion circuit 32 of the low-frequency conversion circuit 30 is converted into a parallel signal by the serial-parallel conversion circuit 41 of the subcarrier signal separation circuit 40 and input to the FFT circuit 42. . FFT circuit 42 for each antenna series
Separates an input signal into signals for respective subcarriers by an FFT operation, and outputs the separated subcarrier signals as parallel signals.

The subcarrier signal detection / combination circuit 50 detects the subcarrier signal output from the subcarrier signal separation circuit 40 for each antenna sequence, and then combines the detection results in subcarrier frequency units. The combined subcarrier signal is converted into a serial signal by the parallel-serial conversion circuit 61 of the transmission bit estimation circuit 60, then decoded by the decoding circuit 62, and output as a reception bit sequence.

The communication quality measuring circuit 65 shown in FIG. 5 receives the received bit sequence decoded by the decoding circuit 62 as an input, checks a bit error in a certain section, and transmits error information at the time of transmission included in the received signal. (NACK signal etc.) is extracted, and the communication quality of each communication device (terminal) is measured. The measurement result is output from the communication quality measurement circuit 65.

The subcarrier signal reception state measuring circuit 70 in FIG. 5 measures the deterioration state of the subcarrier signal for each antenna sequence. A specific example of measuring the degradation state is:
It is as follows. (1) If the absolute value of the signal amplitude of the input subcarrier signal is below a certain threshold, the value of the power required up to the relevant value is used as the measured value.

(2) The reciprocal of the absolute value of the signal amplitude is calculated and used as a measured value. Subcarrier signal reception state measurement circuit 70
Outputs the measured values as reception state information, for each communication device. This reception state information is input to the antenna selection circuit 80 for each subcarrier frequency. 5 determines a plurality of communication apparatuses to be subjected to the diversity control based on the communication quality information input from the communication quality measurement circuit 65.

Further, the sub-carrier frequency-based antenna selection circuit 80 weights the reception status information of the sub-carrier signal for each antenna sequence input from the sub-carrier signal reception status measurement circuit 70 according to the communication quality information ( The larger the device, the lower the communication quality.) Then, the reception state information weighted for each of the diversity control target communication devices is added for all the diversity control target communication devices, and the sum thereof is obtained. The sum is used as an evaluation function, and an antenna that minimizes the evaluation function is selected for each subcarrier frequency.

Antenna selection circuit 8 for each subcarrier frequency
The value of the evaluation function used by 0 is such that a signal having a smaller amplitude
It grows under the influence. Therefore, at a certain subcarrier frequency, among the received signals from the terminals to be controlled for diversity, an antenna having at least one signal whose power is significantly reduced is excluded from the selection because the value of the evaluation function increases. The information on the antenna selected by the sub-carrier frequency-based antenna selection circuit 80 is used at the next base station transmission frame timing.

Antenna selection circuit 8 for each subcarrier frequency
0 outputs information on the selected antenna. The information of this antenna is stored in a transmission code antenna sequence assignment circuit 100.
Is input to Next, the operation of the multicarrier signal transmitting / receiving apparatus (base station apparatus) in FIG. 5 at the base station side transmission frame timing will be described.

The transmission bit sequence input for transmission is encoded in the encoding circuit 92 of the transmission code forming circuit 90 to become a transmission code sequence. This transmission code sequence is
The signal is converted into a parallel signal by a serial-parallel conversion circuit 91. Transmission code antenna sequence assignment circuit 10
0 inputs a transmission code sequence in a parallel signal format output from the serial-parallel conversion circuit 91,
The antenna selection information obtained at the previous reception frame timing is input from the antenna selection circuit 80 for each subcarrier frequency.

Then, transmission code antenna sequence assignment circuit 100 associates the input transmission code sequence with the subcarrier frequency used in IFFT circuit 111 based on antenna selection information, and assigns the transmission code sequence to each antenna sequence.
For the subcarrier frequencies that are not used for transmission among the subcarrier frequencies that can be allocated, the transmission code antenna sequence allocation circuit 100 allocates a signal having an amplitude of 0, so that the output of the corresponding subcarrier is reduced to 0 (ie, Unused).

For example, the distribution of the transmission power of antenna A1 shown in FIG.
Are the subcarrier frequencies f2 and f3 of the series of the antenna A1.
Is realized by allocating a signal having an amplitude of 0 with respect to the subcarrier frequencies f1 and f4. The signal output from the transmission code antenna sequence allocating circuit 100 is, for each antenna sequence,
Multi-carrier conversion is performed by the inverse fast Fourier transform operation of the FFT circuit 111. The multi-carrier signal is converted by the parallel-serial conversion circuit 112 into a multi-carrier signal in a parallel signal format.

In the high frequency conversion circuit 120, the multi-carrier signal output from the parallel-serial conversion circuit 112 is converted by the digital-analog conversion circuit 121 into an analog signal. This analog signal is multiplied by the common carrier frequency from the carrier frequency oscillation circuit 35 in the multiplying circuit 122 to remove harmonic components, so that the analog signal is converted into a high-frequency signal suitable for transmission from the antenna 10.

The high frequency signal output from the multiplying circuit 122 is
The signals are input to the individual antennas 10 for each antenna series via the demultiplexing circuit 20, and transmitted as radio multicarrier signals (OFDM signals in this example) from the respective antennas. In a communication terminal apparatus using the multicarrier signal transmitting / receiving apparatus of FIG. 5 as a base station, a diversity effect can be obtained using a single antenna. That is, radio waves transmitted from the plurality of antennas 10 (1) to 10 (N) in FIG. 5 are combined in space and reach a single antenna of the communication terminal device, so that transmission diversity is realized.

In this case, depending on the distance between each of the antennas 10 (1) to 10 (N) installed on the base station side, an arbitrary carrier phase different for each antenna sequence occurs. Such a carrier phase can be removed for each subcarrier frequency by using, for example, delay detection in a detection circuit in the communication terminal apparatus. As described above, the transmission diversity technology can be applied even in the case where the multi-carrier signal transmission / reception device of FIG. 5 performs broadcast transmission to a plurality of communication terminal devices.

In particular, when the sub-carrier frequency-based antenna selection circuit 80 selects an antenna for each sub-carrier frequency, it selects an antenna in which all the reception states of the plurality of communication apparatuses to be diversity controlled satisfy predetermined conditions. Thus, the effect of transmission diversity can be obtained in all communication devices. When the number of base station antennas is 2, the number of subcarriers is 4, and the number of gain control terminals is 2, for example, FIG.
The relationship between the antenna and the subcarrier frequency is selected as shown in FIG.

In the example shown in FIGS. 6 and 7, the base station selects two antennas for each subcarrier frequency so that the sum of the reception power drop widths for both terminals (TE1 and TE2) is minimized. Terminals TE1, TE2
It can be understood that the state of the received power of each subcarrier in each antenna of the above also becomes good.

[0076]

According to the multi-carrier signal transmitting / receiving apparatus of the present invention, the transmission diversity technique of installing a plurality of antennas only at the base station on the premise of TDMA-TDD transmission can be applied to the broadcast communication. The throughput characteristics of the entire system can be improved without increasing the load on the device.

A simulation was performed to show the specific effects of the present invention. The result (packet transfer failure probability) is shown in FIG. In this simulation, communication on a frequency selective fading communication channel was assumed. In addition, the following evaluation parameters were used. FIG.
In the above, the packet transfer failure probability is a probability that an error occurs in a packet in at least one terminal.

Carrier frequency: 5 [GHz] Number of base station antennas: 4 Number of subcarriers: 48 Modulation method: D8PSK Error correction coding rate: 2/3 Packet length: 72 [bytes] Number of FFT points: 64 Sampling rate: 20 [MHz] Guard interval: 800 [ns] Frame length: 1 [ms] RMS delay spread: 150 [ns] Doppler frequency: 50 [Hz] As is clear from FIG. The probability is reduced and the throughput characteristics are significantly improved. Further, according to the present invention, the number of subcarriers used in each antenna sequence on the base station side is evenly dispersed, which is effective in reducing the peak power of a multicarrier signal. That is, there is an effect that the required back-off condition required at the time of signal amplification is relaxed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of an apparatus according to a first embodiment.

FIG. 2 is a block diagram illustrating a configuration of a main part of an apparatus according to a second embodiment.

FIG. 3 is a block diagram illustrating a configuration of a main part of an apparatus according to a third embodiment.

FIG. 4 is a block diagram illustrating a configuration of a main part of an apparatus according to a fourth embodiment.

FIG. 5 is a block diagram illustrating a specific configuration of a main part of an apparatus according to a fourth embodiment.

FIG. 6 is a graph showing an example of power distribution at the time of transmission by a base station according to the present invention.

FIG. 7 is a graph showing an example of a power distribution at the time of terminal station transmission in the present invention.

FIG. 8 is a graph showing an example of a packet transfer failure probability in a frequency selective fading channel.

FIG. 9 is a schematic diagram illustrating a configuration example of a signal frame in broadcast communication using the TDMA-TDD scheme.

FIG. 10 is a block diagram showing a configuration of a conventional multicarrier signal transmitting / receiving apparatus.

[Explanation of symbols]

 Reference Signs List 10 antenna 20 demultiplexing circuit 30 low frequency conversion circuit 31 multiplication circuit 32 analog-digital conversion circuit 35 carrier frequency oscillation circuit 40 subcarrier signal separation circuit 41 serial-parallel conversion circuit 42 FFT circuit 50 subcarrier signal detection synthesis circuit 60 transmission Bit estimation circuit 61 Parallel-serial conversion circuit 62 Decoding circuit 65 Communication quality measurement circuit 70 Subcarrier signal reception state measurement circuit 80 Antenna selection circuit for each subcarrier frequency 90 Transmission code formation circuit 91 Serial-parallel conversion circuit 92 Encoding circuit 100 Transmission code antenna sequence assignment circuit 110 Multicarrier signal generation circuit 111 IFFT circuit 112 Parallel-serial conversion circuit 120 High-frequency conversion circuit 121 Digital-analog conversion circuit 122 Multiplication times Reference Signs List 210 antenna 220 demultiplexing circuit 230 low frequency conversion circuit 240 subcarrier signal separation circuit 250 subcarrier signal detection selection circuit 260 transmission bit estimation circuit 270 subcarrier signal reception power measurement circuit 280 subcarrier frequency per antenna selection circuit 290 transmission code formation circuit 300 transmission code antenna sequence assignment circuit 310 multicarrier signal generation circuit 320 high frequency conversion circuit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masahiro Umehira 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo F-term within Nippon Telegraph and Telephone Corporation (reference) 5K022 DD01 DD13 DD23 DD33 5K042 AA06 BA01 CA02 CA14 CA16 CA17 CA20 DA04 FA11 5K059 AA08 CC02 CC03 DD36 5K067 AA02 AA11 AA43 CC01 CC04 CC14 CC21 CC24 EE02 EE10 KK03

Claims (5)

[Claims] 1. A multicarrier signal transmitting and receiving apparatus for transmitting and receiving a wireless multicarrier signal including a plurality of carrier frequency components to and from a plurality of communication apparatuses, comprising: a plurality of antennas; A branching circuit that transmits a carrier signal to a circuit on the receiving side and transmits a multicarrier signal output from a circuit on the transmitting side to the plurality of antennas, and a multicarrier signal received by the plurality of antennas. A low-frequency conversion circuit that converts and outputs a low-frequency multi-carrier signal suitable for signal processing for each antenna sequence, and a multi-carrier signal output from the low-frequency conversion circuit for each antenna sequence and is included in the low-frequency conversion circuit. A subcarrier signal separation circuit that separates and outputs a plurality of subcarrier signals to be transmitted, A subcarrier signal reception state measurement circuit that measures the reception state of the subcarrier signal output from the carrier signal separation circuit, classifies the measurement result for each communication device that has transmitted the signal, and outputs the result. A subcarrier signal detection / synthesis circuit that detects a subcarrier signal output from a subcarrier signal separation circuit for each subcarrier frequency, and then synthesizes a detection result of each antenna sequence in subcarrier frequency units; A transmission bit estimation circuit for estimating transmission bits transmitted by the communication device from a reception code sequence appearing in an output of the circuit, based on a reception state measurement result for each communication device output from the subcarrier signal reception state measurement circuit, All receptions of a plurality of communication devices to be diversity controlled are determined in advance. An antenna selection circuit for each subcarrier frequency for selecting an antenna whose state satisfies a predetermined condition for each frequency of a subcarrier, a transmission code formation circuit for forming a transmission code from transmission bits to be transmitted, and the antenna for each subcarrier frequency A transmission code antenna sequence assignment circuit that assigns an output of the transmission code formation circuit to a subcarrier frequency corresponding to each antenna sequence, based on antenna information for each subcarrier frequency output from the selection circuit; A multicarrier signal generation circuit that selectively outputs only a subcarrier frequency to which a transmission code sequence is allocated by an allocation circuit and outputs a multicarrier signal corresponding to a corresponding transmission code sequence; The output signal of the signal generation circuit Multicarrier signal receiving apparatus characterized by comprising a high-frequency conversion circuit for converting the high frequency signal suitable for transmission from the antenna based on the item. 2. The multi-carrier signal transmitting and receiving apparatus according to claim 1, wherein a bit error is detected in a predetermined interval and error information at the time of transmission is extracted based on a received bit sequence output from the transmission bit estimating circuit. A communication quality measuring circuit for measuring the communication quality of the communication device, wherein the subcarrier frequency-based antenna selection circuit includes a reception state measurement result for each communication device output from the subcarrier signal reception state measurement circuit; Based on the communication quality information of each communication device output from the quality measurement circuit, to identify a plurality of communication devices to be subjected to diversity control, for a plurality of communication devices to be subjected to the diversity control,
A multicarrier signal transmission / reception device, wherein an antenna whose reception state satisfies a predetermined condition is selected for each subcarrier frequency. 3. The multi-carrier signal transmitting and receiving apparatus according to claim 1, further comprising a carrier frequency oscillation circuit for outputting a carrier signal, wherein said carrier frequency oscillation circuit outputs said carrier signal to all said low frequency conversion circuits and all said low frequency conversion circuits. A multicarrier signal transmission / reception device, which is commonly applied to the high frequency conversion circuit. 4. The multi-carrier signal transmitting and receiving apparatus according to claim 1, wherein a bit error is detected within a predetermined interval and error information at the time of transmission is extracted based on a received bit sequence output by the transmission bit estimation circuit, and each of the bits is extracted. A communication quality measurement circuit for measuring communication quality of a communication target, and a carrier frequency oscillation circuit for supplying a carrier signal common to all of the low frequency oscillation circuits and all of the high frequency oscillation circuits, further comprising: The antenna selection circuit for each frequency
Based on the reception state measurement result for each communication device output from the subcarrier signal reception state measurement circuit and the communication quality information of each communication device output from the communication quality measurement circuit, A multi-carrier signal transmitting / receiving apparatus, wherein, for a plurality of communication apparatuses to be subjected to the diversity control, an antenna in which all reception states satisfy predetermined conditions is selected for each subcarrier frequency. . 5. The multicarrier signal transmitting / receiving apparatus according to claim 1, wherein OFDM is used for modulating the multicarrier signal, and TDMA-TDD is used as a signal transmission method. A multi-carrier signal transmitting / receiving device characterized by employing: