JPH07312590A - Method for selecting antenna of diversity - Google Patents

Abstract

PURPOSE:To improve the communication quality by storing the data at the reception level in time series, estimating the reception level in the next transmission slot time based on the stored data, and selecting the antenna with higher reception level at the transmission. CONSTITUTION:A CPU 8 predicts the value in the next reception slot time on the reception level of antennas 1 and 2 stored in time series in a memory 5 and on the bit error generation and predicts the antenna with the highest reception signal quality. The CPU 8 outputs a reception antenna selection signal in the switching timing of the reception slot based on the estimation result. When a reception antenna selection part 6-5 is controlled, the output of demodulation parts 6-7 and 6-6 are inputted in a decoding part 6-9. Thus, the signal from the best antenna is demodulated at the reception time. At the transmission time, encoding the voice signal is performed in an encoding part 6-8. Then it is modulated in a modulation part 6-1. The transmission is performed by the antenna 1 or antenna 2 with the highest reception level through a transmission part 6-2 and an antenna switching 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity antenna selection method in a TDD (time division) communication device.

[0002]

2. Description of the Related Art Regarding the propagation characteristics of radio waves in land mobile communications, a large number of waves having different propagation paths arrive due to reflected or scattered waves from surrounding buildings or topography, and interfere with each other to generate complex standing waves. At this time, the envelope and the phase of the received wave of the mobile station randomly fluctuate and appear as severe fading. This electrolytic intensity distribution is approximated to the Rayleigh distribution and is called Rayleigh-fading.

To reduce the influence of fading, diversity reception has been conventionally used. This is a method in which a plurality of antennas are used to receive radio waves whose fading fluctuations have little correlation with each other and select a received wave with a high reception level. Recent TDD in digital communication
In the method, transmission and reception are time-divisionally communicated in a transmission slot and a reception slot. In diversity reception in this TDD system, the antenna with the highest reception level is selected and received among a plurality of antennas received in a reception slot, and transmission is performed in the next transmission slot with that antenna.
This is because an antenna with a high reception level is less affected by fading, so that high gain can be obtained by using that antenna even during transmission.

[0004]

However, when the reception level a of the antenna 1 and the reception level b of the antenna 2 change as shown in FIG. 1, when the reception level of the antenna 1 is received at the reception slot at the reception time t ₃ . The reception level L ₁₃ is higher than the reception level L ₂₃ of the antenna 2 and the antenna 1 is selected and received, but at the transmission time t ₄ , the reception level L _{14 of the} antenna 1 is lower than the reception level L _{24 of the} antenna 2 There was a problem of transmitting with the antenna 1.

The present invention has been made in view of the above points, and in order to eliminate the above problems, the reception level of each antenna at the transmission time is predicted from the change in the reception level of each antenna, and the predicted reception level is obtained. It is an object of the present invention to provide a diversity antenna selection method for selecting and transmitting an antenna with high frequency.

[0006]

In order to solve the above-mentioned problems, the present invention provides a diversity antenna selection method in a communication device which comprises a plurality of antennas, a reception level detector and an antenna switch, and which performs transmission and reception in the TDD system. As shown in FIG. 2, the communication device is provided with a memory 5 for storing reception level data, and the reception level detector 3 detects the reception level at the reception slot time for each of the plurality of antennas. The data is accumulated in the memory 5 in time series, and the CPU 8 predicts the reception level at the next transmission slot time from the data accumulated in time series, and the predicted reception at the next transmission slot time. The feature is that the antenna with the highest level is selected and transmitted.

[0007]

In the present invention, the reception level detector 3 stores the reception level data of each antenna in the memory 5 in time series, and the antenna switching unit 4 stores the data in time series. Since the reception level at the next transmission slot time is predicted and the antenna with the highest predicted reception level is selected and transmitted at the time of transmission, it is less likely to transmit with a low level antenna at the time of transmission as in the past, and diversity gain is reduced. Can be raised.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing a configuration example of a communication device of an analog communication system adopting the diversity antenna selection method of the present invention. As shown in the figure, the analog communication type communication device adopting the diversity antenna selection method of the present invention includes an antenna 1, an antenna 2, a reception level detector 3,
The antenna switching device 4, the memory 5, the transceiver 6, the handset 7 and the CPU 8 are included.

The antenna 1 and the antenna 2 are installed at positions apart from each other with little correlation with each other, and the received signals of the respective antennas are transmitted to the receiving section 6-3 in the transmitter / receiver 6 via the antenna switching unit 4 and are transmitted to the receiving unit 6-3. The received signal is received by the receiving unit 6-4
The received signal of the antenna 2 is input to the receiver, is subjected to high frequency amplification, is input to the demodulation unit 6-6 via the receiving antenna selection unit 6-5, and is directly input to the reception level detector 3. The reception level detector 3 detects the reception level at the reception slot time of each antenna and outputs the data as CP.
Send to U8.

The CPU 8 stores the data in the memory 5, predicts the antenna with the highest reception level at the next transmission slot time from the data (details will be described later), and transmits the antenna switch 4 at the transmission slot. The antenna (1 or 2) controlled and predicted by the antenna selection signal is connected. CP
U8 sends the transmission / reception switching signal to the value of the transmission antenna selection signal to the antenna switching unit 4 at the transmission / reception slot switching timing. The antenna switch 4 which is set to the reception state by the transmission / reception switching signal connects both the antenna 1 and the antenna 2 to the transceiver 6. Further, the CPU 8 predicts the antenna (1 or 2) having the highest reception level at the next reception slot time from the data stored in the memory 5 by the same method as the above-mentioned prediction at the transmission slot time, and the reception antenna at the reception slot time. The reception antenna selection unit 6-5 in the transceiver 6 is controlled by the selection signal.

As a result, the transceiver 6 demodulates the received signal from the antenna having the highest reception level at the time of reception and outputs the voice to the handset 7. At the time of transmission, the voice signal from the handset 7 is modulated by the modulator 6-1. , The antenna having the highest reception level (1
Or send from 2).

FIG. 1 is a diagram for explaining a diversity antenna selection method according to the present invention. As shown in FIG. 1, the communicator alternately repeats communication in a time division manner with reception slots at times t ₁ , t ₃ ... And transmission slots at times t ₂ , t ₄ . The CPU 8 uses the reception level detector 3 at times t ₁ and t ₃
The reception levels L ₁₁ , L _{13 of} the antenna 1 received at.
.. and each data of the reception levels L ₂₁ , L ₂₃ ... Of the antenna 2 is stored in the memory 5.

Further, the CPU 8 predicts the reception level of the antenna 1 and the reception level of the antenna 2 at the next transmission slot time from the data stored in the memory 5. For example, time t
At the time of receiving the signal at ₃ , the antenna switching unit 4 determines from the reception levels L ₁₁ and L ₁₃ of the antenna 1 to the next transmission slot time t.
The reception level L ₂₄ at the next transmission slot time t ₄ is predicted from the reception level L _{14 at 4} and the reception levels L ₂₁ and L ₂₃ at the antenna 2, and the predicted high reception level antenna (the antenna 2 in the example of FIG. 1 is used. ) Switch the connection to and send. As an example of the predictive calculation method, the reception level L
_A first-order approximation curve or a second-order approximation curve is obtained from the data of ₁₁ , L ₁₃ ... And a reception level L ₁₄ at the transmission slot time t ₄ is obtained on the extension line thereof, and similarly, reception levels L ₂₁ , L _23.・
・ The reception level L ₂₄ is calculated from.

FIG. 3 is a diagram showing a configuration example of a digital communication type communication device adopting the diversity antenna selection method of the present invention. In this embodiment, the demodulation unit 6-6 is connected to the reception unit 6-3 of the reception signal of the antenna 1, the demodulation unit 6-7 is connected to the reception unit 6-4 of the reception signal of the antenna 2, and these demodulation units 6 and 6 are connected. The outputs from -6 and 6-7 are input to the receiving antenna selector 6-5 and the bit error rate detector 9, respectively.

The antenna selected at the transmission slot time is
Similar to the embodiment of FIG. 2, the CPU 8 detects the reception level detector 3 and predicts from the data accumulated in the memory 5 in time series to perform antenna switching control. The antennas selected at the reception slot time are the reception levels of the antennas 1 and 2 accumulated in time series in the memory 5 and the bit error occurrence rates of the reception signals of the antennas 1 and 2 output from the bit error occurrence rate detector 9. From this, the antenna with the best received signal quality is predicted. The bit error rate is determined from the check code included in the received signal.

The CPU 8 predicts the value at the next reception slot time for the reception level and the bit error occurrence rate of the antenna 1 and the antenna 2 stored in the memory 5 in time series, and predicts the predicted reception level and the bit error occurrence rate. According to the determination criteria with and as the determination factors, the antenna with the best received signal quality at the reception slot time is predicted. Based on this prediction result, the CPU 8 outputs the reception antenna selection signal at the reception slot switching timing, and the reception antenna selection unit 6-5
Control of the output of the connected demodulation unit (6-6 or 6-7) to the decoding unit 6- via the reception antenna selection unit 6-5.
9 is input.

As a result, the communication device demodulates and decodes the reception signal from the antenna having the best reception quality at the time of reception, encodes the voice signal from the handset 7 by the encoding unit 6-8, and further the modulation unit 6-. 1, and the signal is transmitted from the antenna 1 or the antenna 2 having the highest reception level through the transmitting unit 6-2 and the antenna switch 4.

As described above, the reception level at the next transmission slot time is predicted from the data accumulated in time series, and at the time of transmission, the antenna with the highest predicted reception level is selected and transmitted. It is less likely that a low level antenna will be used for transmission.

[0019]

As described above in detail, according to the present invention, the antenna selection switching means accumulates the reception level data of each antenna in time series, and the data is accumulated from the time series. The reception level at the time of the next transmission slot is predicted, and the antenna with the highest reception level is selected and transmitted at the time of transmission.Therefore, it is not necessary to transmit with the antenna with the low level at the time of transmission as in the past, and diversity gain should be increased. The excellent effect of being able to do is obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a diversity antenna selection method of the present invention.

FIG. 2 is a diagram showing a configuration example of a communication device of an analog communication system adopting the diversity antenna selection method of the present invention.

FIG. 3 is a diagram showing a configuration example of a communication device of a digital communication system adopting the diversity antenna selection method of the present invention.

[Explanation of Codes] 1 antenna 2 antenna 3 reception level detector 4 antenna switcher 5 memory 6 transceiver 7 transmitter / receiver 6-1 modulator 6-2 transmitter 6-3 receiver 6-4 receiver 6-5 reception Antenna selection unit 6-6 Demodulation unit 6-7 Demodulation unit 6-8 Encoding unit 6-9 Decoding unit 7 Handset 8 CPU 9 Bit error rate detector

Claims (1)

[Claims] 1. A diversity antenna selecting method in a communication device, comprising a plurality of antennas, a reception level detecting means, and an antenna switching means, and transmitting and receiving in a time division system, wherein data of the reception level is stored in the communication device. The receiving level detecting means detects the receiving level in the receiving slot for each of the plurality of antennas, accumulates the data in the storing means in time series, and further accumulates in the time series. Diversity characterized in that a prediction means for predicting a reception level in the next transmission slot is provided from the received data, and the antenna switching means selects and transmits the antenna having the highest predicted reception level in the transmission slot. Antenna selection method.