JP2695464B2 - Diversity receiver - Google Patents

Description

The present invention relates to a diversity receiver used in digital mobile radio communication and the like.

[Prior Art] FIG. 3 is a block diagram showing a conventional diversity receiver shown in “The Institute of Electronics and Communication Engineers, Mobile Communication and Fundamentals, Chapter 7, Diversity, p161 to p176”, and in FIG. , 1b is an antenna, 2a is a receiver including a demodulation circuit 3a connected to the antenna 1a, a reception electric field strength instruction circuit 4a, 2b is a demodulation circuit 3b connected to the antenna 1b, a reception electric field strength instruction circuit 4b 5 is a receiver including a comparator, 5 is a comparison circuit for comparing the outputs of the reception electric field intensity indicating circuits 4a, 4b, and 6 is a switching circuit for selecting either of the output signals of the receivers 2a, 2b according to the output signal of the comparison circuit 5. Reference numeral 7 is an adaptive automatic equalizer, and 8 is a baseband signal processing circuit.

 Next, the operation will be described.

The received waves received by the antennas 1a and 1b are detected by the demodulation circuits 3a and 3b, respectively, and the output signals thereof are sent to the switching circuit 6. The electric field strength of each received wave is detected by the received electric field strength instruction circuits 4a and 4b, and the detection signal is sent to the comparison circuit 5. Next, the comparison circuit 5 compares the electric field strength detection signals of the respective received waves to determine which received wave has the higher electric field strength, and sends a signal according to the result to the switching circuit 6. In the switching circuit 6, only the detection signal of the received wave having the stronger electric field strength is selected according to the output signal of the comparison circuit 5, and the signal is sent to the adaptive automatic equalizer 7. Generally, when performing pulse transmission through a distorted transmission path, an equalizer for removing intersymbol interference due to distortion of the transmission path is provided on the receiving side in order to correctly identify the pulse sequence sent out at regular intervals in the receiving device. It is necessary to insert the transversal adaptive automatic equalizer using a Kalman filter or the like as an effective equalizer when the distortion of the transmission line is unknown or when it varies with time. is there. The output signal of the adaptive automatic equalizer 7 is a baseband signal processing unit 8
Sent to

[Problems to be solved by the invention]

Since the conventional diversity receiver is configured as described above, when performing pulse transmission, regardless of the distortion of the transmission path of the reception wave, the reception wave of the stronger electric field strength is selected, and as a result, the transmission path There is also a problem in that a received wave with a large distortion and a large number of transmission pulse identification errors may be selected.

The present invention has been made in order to solve the above-mentioned problems of the conventional one, and an object thereof is to obtain a diversity receiving apparatus which can always select a reception wave with less error in identifying transmission pulses. And

[Means for solving the problem]

The diversity receiving apparatus according to the present invention adds an adaptive automatic equalizer to the output of the receiver, compares the average values of the output errors of the adaptive automatic equalizer, and compares the received wave of the method with the smallest error. Is to be selected.

[Action]

Since the diversity receiver according to the present invention compares the output error of the adaptive automatic equalizer, it is easy to equalize the distortion of the transmission path of the reception wave, and the reception signal such that the error of the transmission signal identification is minimized. Can be selected.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 9a is a receiver including a demodulation circuit 3a, 9b is a receiver including a demodulation circuit 3b, 10a is an adaptive automatic equalizer for equalizing the output signal of the receiver 9a, and 10b is a receiver 9b. An adaptive automatic equalizer that equalizes the output signal, 11 is a comparison and determination circuit that averages and compares the error signals of the adaptive automatic equalizers 10a and 10b, and 12 is an output signal of the comparison and determination circuit 11. It is a switching circuit that selects the output signal of the adaptive automatic equalizer.

 Next, the operation will be described.

The adaptive automatic equalizer 10a adjusts the coefficient according to an algorithm such as a Kalman filter during the training period of the transmission signal, that is, while the known signal is delayed. Then, the error between the known signal and the output of the adaptive automatic equalizer is minimized. Then, even while unknown data is sent after the training period, the coefficient is updated for each data according to an algorithm such as a Kalman filter. The adaptive automatic equalizer 10b operates similarly. Then, the error signal is sent to the comparison and determination circuit 11 for each data.
The comparison and determination circuit 11 stores the respective error signals, averages the last about 10 error signals for each adaptive automatic equalizer during the training period, and compares the averaged values. The better the equalization of intersymbol interference due to the distortion of the transmission line is, the smaller this average value is. The smaller this average value is,
The error rate for identifying unknown data after the training period is reduced. In the comparison / determination circuit 11, a signal for selecting the output of the adaptive automatic equalizer with the smaller average value is sent to the switching circuit 12, and in the switching circuit 12,
The output of the selected adaptive automatic equalizer is maintained in the baseband signal processing unit 8.

In the above embodiment, the adaptive automatic equalizers 10a and 10b are connected to the outputs of the demodulation circuits 3a and 3b, respectively, but the delay time may be reduced in a TDMA (time division multiple access) system or the like. When used in an acceptable system, as shown in the second embodiment of the present invention in FIG. 2, each demodulation circuit 3a, 3b
Is provided with storage circuits 13a and 13b for holding received data, and the output thereof has a switching circuit 12 and an adaptive automatic equalizer.
It may be configured to connect 10. At this time, the memory circuit 13a,
First, 13b outputs only the output signals of the demodulation circuits 3a and 3b during the training period to the adaptive automatic equalizer 10 in the order of each training burst. The adaptive automatic equalizer 10 obtains the error signal. The subsequent operation is the same as that of the above-described embodiment, the average value of the error signal during the training period is obtained by the comparison and determination circuit 11, and the switching circuit 12 is controlled by the controller 14 according to the result.
The receiver 3a with the smaller average value of the error signal
Alternatively, only the data of 3b is output from the storage circuit 13a or 13b to the adaptive automatic equalizer 10. And adaptive automatic equalizer 10
Is output to the baseband signal processing unit 8.

〔The invention's effect〕

As described above, according to the present invention, the plurality of received waves are selected by using the comparison result of the error signals of the adaptive automatic equalizer, so that the highly accurate diversity receiver can be obtained. There is.

[Brief description of the drawings]

1 is a block diagram showing a diversity receiver according to an embodiment of the present invention, FIG. 2 is a block diagram showing a diversity receiver according to another embodiment of the present invention, and FIG. 3 is a conventional diversity receiver. It is a block diagram. In the figure, 1a and 1b are antennas, 2a and 2b are receivers, and 3a and 3b
Is a demodulation circuit, 4a and 4b are reception electric field strength instruction circuits, 5 is a comparison circuit, 6 is a switching circuit, 7 is an adaptive automatic equalizer,
8 is a baseband signal processing circuit, 9a and 9b are receivers, and 10a and 1
Reference numeral 0b is an adaptive automatic equalizer, 11 is a comparison / determination circuit, 12 is a switching circuit, 13a and 13b are storage circuit control devices, and 14 is a control device. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A diversity receiver which receives two or more received waves and selects an optimum one, an adaptive automatic equalizer provided corresponding to each of the two or more received waves, and training. A comparison judgment circuit for calculating and comparing the average value of the output error of each adaptive automatic equalizer at the time of signal reception, and a switching circuit for selecting an optimum received wave according to the judgment result are characterized by Diversity receiver.