JPH09331281A - Transmitter-receiver performing transmission diversity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter-receiver which can perform transmission diversity by removing the influence of adjacent waves, fading, etc., with a small circuit scale. SOLUTION: A transmitter-receiver is provided with a plurality of branches of antennas 1 and 2 for both transmission and reception, a base-band demodulating section 7 which demodulates the received signals of each branch, and a transmission antenna changeover section 10 which switches the antennas 1 and 2 to each other as transmission antennas based on the receiving power of the received signals of each branch. In the transmitter-receiver which is used for a TDD type radio communication system, a comparing means 8 which compares the receiving power of received signals of each branch with another by using digital data obtained during the demodulating process of the demodulating section 7 and outputs the information on the selection of transmission antennas to a transmission antenna changeover section 10 is provided. Therefore, the transmitter-receiver can perform transmission diversity in spite of its small circuit scale.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception apparatus for performing transmission diversity in TDD communication.
In particular, the transmission antenna with the best communication quality can be selected appropriately.

[0002]

2. Description of the Related Art Conventionally, in TDD communication in which transmission and reception are performed at the same frequency by time division, transmission diversity is achieved by selecting the antenna that has the highest reception power during reception from a plurality of antennas. Transceivers that perform are known.

As shown in FIG. 6, this conventional transmission / reception apparatus has a first antenna 48 for both transmission and reception, a second antenna 49 for both transmission and reception, and a transmission / reception separator 50 for the first antenna 48.
And a transmission / reception separator 51 for the second antenna and a first antenna
Receiver 52 that down-converts the received signal received by 48 to the baseband band, and receiver that downconverts the received signal received by the second antenna to the baseband band
53, a baseband demodulation unit 54 that decodes the received signal and outputs decoded data 58, an RSSI unit 55 that detects the received power by the output of the receiver 52, and an RSSI that detects the received power by the output of the receiver 53. A comparator 57 that compares the received power detected by the unit 56 and outputs antenna selection information.
A transmission antenna selector 59 that selects an antenna based on the antenna selection information, and a baseband modulator 61 that performs baseband modulation processing based on the input modulation data 62,
A transmitter 60 that up-converts the signal output from the baseband modulator 61 into a wireless signal is provided.

In this device, the first antenna 48 and the second antenna 48
The received power of the received signal received by the antenna 49 of
The comparator 57 is detected by the SI unit 55 and the RSSI unit 56.
Is output to The comparator 57 compares these reception powers, outputs antenna selection information for selecting an antenna connected to the branch with the larger reception power to the transmission antenna switching unit 59, the transmission antenna switching unit 59, The antenna 48 or the antenna 49 is selected according to the antenna selection information.

On the other hand, the baseband modulator 61 performs baseband modulation processing based on the input modulation data 62, and the transmitter 60 up-converts the modulated signal into a radio signal. The transmission signal output from the transmitter 60 is transmitted from the antenna selected by the transmission antenna selector 59.

As described above, in the transmission / reception apparatus of the TDD system, at the time of transmission, the transmission diversity is executed by selecting the antenna that has received the signal of the highest reception level at the previous reception.

[0007]

However, in a conventional transmitting / receiving apparatus for performing transmission diversity, an analog circuit (RSSI section) for detecting a reception level is specially provided, so that the circuit scale is increased. have.

Further, in this conventional apparatus, since the reception level is detected based on the output of the receiver at the preceding stage of the baseband, the reception level including the adjacent wave and the multipath is detected, and the reception of the main wave is detected. There is a problem that the level cannot be detected accurately, and therefore, it is not possible to select the transmission antenna of the branch having the best communication quality.

The present invention solves such a conventional problem, has a small circuit scale, and has an adjacent wave,
It is an object of the present invention to provide a transmission / reception apparatus that can select a transmission antenna having the best communication quality even when fading or multipath exists.

[0010]

Therefore, in the transmitting / receiving apparatus of the present invention, the reception power of the reception signal of each branch is compared by using the digital data obtained in the demodulation process of the baseband demodulation section. The comparison is performed using the output of the reception route Nyquist filter provided in the baseband demodulation unit and the tap coefficient set in the maximum ratio combining adaptive equalizer.

Therefore, the circuit scale can be small, and the reception power of each branch can be compared by eliminating the influence of adjacent waves, fading, multipath, and the like.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a transmission / reception antenna for a plurality of branches, a baseband demodulation unit for demodulating a reception signal of each branch, and a reception power of a reception signal of each branch. In a transmitting / receiving apparatus that performs transmission diversity in a TDD wireless communication system, the transmission antenna switching unit that switches the transmission antenna based on the above is used to receive each branch by using digital data obtained in the demodulation process of the baseband demodulation unit. Comparing the reception power of the signal, the transmission antenna switching unit is provided with a comparison means for outputting the selection information of the transmission antenna,
Transmit diversity can be performed with a small circuit scale.

According to a second aspect of the present invention, the comparison means determines the reception power of the reception signal by using the output of the reception route Nyquist filter for shaping the band of the reception signal of each branch provided in the baseband demodulation section. It is configured to make a comparison, and it is possible to compare the reception powers without the influence of adjacent waves.

According to a third aspect of the present invention, the comparing means compares the received powers of the received signals by using the tap coefficient set in the maximum ratio combining adaptive equalizer provided in the baseband demodulation section. It is possible to compare the reception powers without the influence of adjacent waves, fading, multipath, etc.

According to a fourth aspect of the present invention, the comparison means is configured to compare the reception power of the reception signals by using the tap coefficient initial value set in the maximum ratio combining adaptive equalizer. The transmitting antenna switching information can be determined at an early time and fed back to the transmitting antenna switching unit.

According to a fifth aspect of the present invention, the comparing means uses the updated tap coefficient of the maximum ratio combining adaptive equalizer,
It is configured to compare the reception power of the reception signal, and the reception power of each branch can be compared more accurately.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
3 to FIG. 3 will be described.

(First Embodiment) As shown in FIG. 1, the transmitting / receiving apparatus of the first embodiment has a first transmitting / receiving antenna 1, a second transmitting / receiving antenna 2, and a first antenna. 1, a transmission / reception separator 3 of the second antenna 2, a transmission / reception separator 4 of the second antenna 2, a receiver 5 for down-converting the reception signal received by the first antenna 1 to a baseband band, and a reception by the second antenna 2. A receiver 6 that down-converts the received signal into a base band, and a base band demodulator 7 that digitally processes and demodulates the outputs of the receivers 5 and 6.
And a comparator 8 built in the baseband demodulation unit 7 for comparing the received power of each branch with a digital signal, and a transmission antenna selector 10 for selecting an antenna based on the antenna selection information output from the comparator 8. And a baseband modulator 12 that performs a baseband modulation process based on the input modulation data 13, and a transmitter 11 that up-converts the signal output from the baseband modulator 12 into a radio signal.

As shown in FIG. 2, the baseband demodulation unit 7 shapes the band of the reception signal of the branch 1 by digital processing and the reception route Nyquist filter 14 that shapes the band of the reception signal of branch 2 by digital processing. Receive root Nyquist filter 15 and the maximum ratio combining adaptive equalization that equalizes the received signals band-shaped by the receiving root Nyquist filters 14 and 15 and weights the received signals of each branch in proportion to their levels Processing unit 16
A received signal identifying section 17 for identifying the output of the maximum ratio combining adaptive equalization processing section 16, a received data decoding section 18 for decoding a signal based on the identification result of the received signal identifying section 17, and each reception route Nyquist filter. It is provided with a comparator 19 which measures and compares the received power using the outputs of 14 and 15 and outputs the transmitting antenna switching information for designating the antenna with the larger received power.

Further, as shown in FIG. 3, the maximum ratio synthesis adaptive equalization processing unit 16 includes the delay line 42 of the branch 1, the complex tap coefficient 44, and the complex tap coefficient for the data sequentially delayed by the delay line 42. F composed of a product-sum calculation unit 46 for multiplying and adding 44
An F filter including an IR filter, a delay line 43 of the branch 2, a complex tap coefficient 45, and a product-sum calculation unit 47 that multiplies the data sequentially delayed by the delay line 43 by the complex tap coefficient 45 and adds them.
An IR filter and an adder for adding the outputs of the FIR filters of the branch 1 and the branch 2 are provided, and a weighted coefficient proportional to the reception level of each branch is set as a complex tap coefficient.

In this transmitting / receiving device, the signals received by the first antenna 1 and the second antenna 2 are received by the receivers 5 and 6.
Is down-converted to the base band band and input to the base band demodulation unit 7.

The received signal of the branch 1 input to the baseband demodulation unit 7 is digitally processed by the receiving root Nyquist filter 14 to shape the band, and the receiving signal of the branch 2 is banded by the receiving root Nyquist filter 15. Digital processing for shaping is performed, and each processed data is input to the maximum ratio synthesis equalizer 16 and the comparator 19, respectively.

The maximum ratio synthesis equalization unit 16 performs equalization processing on the data of the branch 1 and the data of the branch 2 by the two FIR filters corresponding to the branch 1 and the branch 2, and synthesizes and outputs the result.

This output is identified by the received signal identifying section 17, and the result decoded by the received data decoding section 18 is output as decoded data.

On the other hand, the comparator 19 measures and compares the powers of the outputs of the reception route Nyquist filters 14 and 15, and transmits the transmission antenna switching information designating the antenna of the branch having the larger power to the transmission antenna switching device 10. Output to.
The transmission antenna switching unit 10 selects an antenna according to the transmission antenna switching information, and the transmission signal modulated by the baseband modulation unit 12 is transmitted from the transmitter 11 through the selected antenna.

In this transmission / reception apparatus, since the comparator 8 compares the received power of each branch using the digitally processed signal of the baseband demodulation unit 7, a special analog circuit like the conventional apparatus is used. do not need. Therefore, transmission diversity can be performed with a small circuit scale.

Further, since the comparator 8 measures and compares the received power by using the output band-shaped by the reception route Nyquist filter of the baseband demodulation unit 7, the influence of the adjacent wave can be eliminated. Communication quality can be improved.

(Second Embodiment) The transmitting / receiving apparatus of the second embodiment has the same overall structure as that of FIG. 1, and the baseband demodulation section 7 has the structure of FIG.

The baseband demodulation section includes a reception route Nyquist filter 20 for shaping the band of the branch 1 reception signal by digital processing, a reception route Nyquist filter 21 for shaping the band of the branch 2 reception signal by digital processing, A maximum ratio combining adaptive equalization processing unit 25 composed of two FIR filters and an adder, and a received signal identifying unit for identifying the output of the maximum ratio combining adaptive equalization processing unit 25
26, a reception data decoding unit 29 that decodes a signal based on the identification result of the reception signal identification unit 26, and a correlation unit that correlates the reception data of branch 1 and the known data (unique word)
22 and a correlator 23 that correlates the received data of the branch 2 with known data, and the channel status is estimated based on the correlation power output from the correlator 22 and 23, and the initial value of the tap coefficient of the FIR filter is calculated. The line estimation unit 24 to be set, the error detection unit 27 that detects an error between the output of the maximum ratio combination adaptive equalization processing unit 25 and the known data, and the coefficient that updates the tap coefficient of the FIR filter based on the detected error. The update unit 28 and a comparator 30 that compares the tap coefficient initial values set in the FIR filters of the respective branches and outputs the transmission antenna switching information designating the transmission antenna are provided.

In this baseband demodulating section, the correlating sections 22 and 23, which previously hold the unique words included in the received frame, correlate the unique words with the received signals sequentially received by the respective branches. And outputs the correlation power to the line estimation unit 24. The maximum value of this correlation power becomes the correlation value when the unique word is received. The channel estimation unit 24 sets the correlation value that maximizes the correlation power of each branch as the initial value of the tap coefficient of each FIR filter of the maximum ratio combination equalization unit 25. Therefore, the FI of the branch where the line condition is good and the maximum correlation power is large
A large initial value of the tap coefficient will be given to the R filter.

The maximum ratio synthesis equalizer 25 performs equalization processing on the data of branch 1 and branch 2 in each FIR filter using the given tap coefficient initial value, synthesizes the results, and outputs the result. . This output is the received signal identification unit 26
Then, the result of being decoded by the received data decoding unit 29 is output as decoded data.

Further, the error detecting section 27 and the coefficient updating section 28 are
Training of the tap coefficient is performed based on the output of the maximum ratio synthesis equalization unit 25, and the tap coefficient of each FIR filter is updated.

The comparator 30 compares the tap coefficient initial values of the respective FIR filters set by the channel estimator 24 and outputs transmission antenna switching information for selecting the antenna of the branch having the larger tap coefficient initial value.

As described above, in the transmitting / receiving apparatus of the second embodiment, the branch for which the received signal having a high correlation with the unique word is obtained is selected based on the tap coefficient initial value of the FIR filter, and the antenna of the branch is selected. To execute the transmission. Here, since the correlation between the received signal and the unique word is observed, it is possible to accurately estimate the received power of the main wave even if the received signal includes adjacent waves or fading, and the communication quality The best antenna can be selected to improve the communication quality in transmission.

Further, in this apparatus, since the transmitting antenna switching information is determined by the tap coefficient initial value, this information can be fed back to the transmitting antenna switching unit at an early time.

(Third Embodiment) In the transmitting / receiving apparatus of the third embodiment, as shown in FIG. 5, the comparator 41 compares the tap coefficients updated by the coefficient updating unit 39 to transmit the data. Determine antenna switching information. Other configurations are the same as those in the second embodiment.

In this baseband demodulation section, the correlation section 33,
34 calculates the correlation power between the unique word and the received signal, and the line estimation unit 35 sets the maximum correlation value in this correlation power as the tap coefficient initial value of each FIR filter of the maximum ratio combination equalization unit 36. The maximum ratio synthesis equalization unit 36 performs equalization processing of the data of the branch 1 and the branch 2 in each FIR filter using the given tap coefficient initial value, and synthesizes and outputs the results. This output is identified by the received signal identifying section 37, and the result decoded by the received data decoding section 40 is output as decoded data.

The error detector 38 is a maximum ratio synthesis equalizer.
An error between the output of 36 and the unique word is detected, and the coefficient updating unit 39 determines each F of the maximum ratio synthesis equalization unit 36 based on this error.
Training of the tap coefficients, which updates the tap coefficients of the IR filter, is performed.

The comparator 41 compares the tap coefficients of the respective FIR filters updated by the coefficient updating section 39, and outputs the transmission antenna switching information for selecting the antenna of the branch having the larger tap coefficient.

As described above, in the transmitting / receiving apparatus of the third embodiment, the branch for which the received signal having a high correlation with the unique word is obtained is selected based on the updated tap coefficient of the FIR filter, and the branch of that branch is selected. Perform transmission using the antenna. Therefore, even if an adjacent wave or fading is included in the received signal, it is possible to accurately select the antenna of the branch having a high received power of the main wave and improve the communication quality in transmission.

Further, in this apparatus, since the transmitting antenna switching information is determined using the tap coefficient updated by further training than the initial value of the tap coefficient, the main wave is more accurate than the second embodiment. It is possible to compare the received powers of.

[0042]

As is clear from the above description, since the transmitting / receiving apparatus of the present invention selects the transmitting antenna by using the digital data processed by the baseband demodulating section, the transmitting diversity can be achieved with a small circuit scale. Can be done.

Further, in the device for selecting the transmission antenna by using the output of the reception route Nyquist filter of the baseband demodulation unit, it is possible to eliminate the influence of the adjacent wave and select the transmission antenna with high communication quality.

Further, in the apparatus for selecting the transmitting antenna by using the tap coefficient of the maximum ratio combining adaptive equalizer of the baseband demodulating section, the influence of adjacent waves, fading, multipath, etc. is eliminated, and the communication quality is high. The transmission antenna can be selected, and optimum transmission diversity can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transmission / reception device according to a first embodiment of the present invention,

FIG. 2 is a block diagram showing a configuration of a baseband demodulation unit according to the first embodiment,

FIG. 3 is a configuration diagram of a maximum ratio combining adaptive equalization unit according to the first embodiment,

FIG. 4 is a block diagram illustrating a configuration of a baseband demodulation unit of a transmission / reception device according to a second embodiment of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a baseband demodulation unit of a transmission / reception device according to a third embodiment of the present invention;

FIG. 6 is a block diagram showing a configuration of a conventional transmission / reception device.

[Explanation of symbols]

1, 2, 48, 49 Transmitter / receiver antenna 3, 4, 50, 51 Transmitter / receiver separator 5, 6, 52, 53 Receiver 7, 54 Baseband demodulator 8, 19, 30, 41, 57 Comparator 9, 58 Decoded data 10,59 Transmit antenna switching unit 11,60 Transmitter 12,61 Baseband modulator 13,62 Modulated data 14,15,20,21,31,32 Receive route Nyquist filter 16,25,36 Maximum ratio combining adaptive Equalization unit 17, 26, 37 Identification unit 18, 29, 40 Decoding unit 22, 23, 33, 34 Correlation unit 24, 35 Channel estimation unit 27, 38 Error detection unit 28, 39 Coefficient update unit 42, 43 Delay line 44 , 45 Tap coefficient 46, 47 Product-sum operation unit

Claims (5)

[Claims] 1. A transmission / reception antenna for a plurality of branches, a baseband demodulation unit for demodulating a reception signal of each branch, and a transmission antenna switching unit for switching a transmission antenna based on a reception power of a reception signal of each branch. , A transmission / reception apparatus for performing transmission diversity in a TDD wireless communication system, wherein the reception power of a reception signal of each branch is compared using digital data obtained in the demodulation process of the baseband demodulation unit, and the transmission antenna is used. A transmission / reception apparatus, comprising: a comparison unit that outputs selection information of a transmission antenna to the switching unit. 2. The comparing means compares the received powers of the received signals by using an output of a received route Nyquist filter for shaping the band of the received signals of the respective branches provided in the baseband demodulation section. The transmission / reception device according to claim 1, which is characterized in that. 3. The comparison means compares the reception powers of the reception signals using tap coefficients set in a maximum ratio combining adaptive equalizer provided in the baseband demodulation unit. The transmission / reception device according to claim 1. 4. The comparison means compares the reception powers of the reception signals by using tap coefficient initial values set in the maximum ratio combining adaptive equalizer.
The transmitting / receiving device according to claim 1. 5. The transmitter / receiver according to claim 3, wherein the comparing means compares the received powers of the received signals by using the updated tap coefficient of the maximum ratio combining adaptive equalizer. .