JPH1041924A - Antenna selection diversity reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely select a reception signal with a higher reception level at all times even when the fading speed is fast. SOLUTION: Each delay time of delay circuits 5, 6, 10 is selected so that a signal delay time Ta is equal to a signal delay time Tb, where Ta is a signal delay time after reception signals S1, S2 reach reception antennas 1, 2 till the signals are demodulated into digital information sets D11, D21 by reception sections 3, 4 and the digital information sets D11, D21 reach a selection switch 7 via delay circuits 5, 6 and Tb is a time after the reception signals S1, S2 are given to a reception level comparison section 9, in which the reception levels are detected and compared and a control signal C11 is generated till the control signal C11 activates the selection switch 7 actually via a delay circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna selection diversity reception system for reducing deterioration of information transmission quality due to fading in wireless communication.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of a configuration of a conventional antenna selection diversity receiving system. In the figure, the received signals from the receiving antennas 31 and 32 are:
The digital information is demodulated by the receiving units 33 and 34 and transmitted to the selection switch 36. The reception level comparison unit 35 detects and compares the signal levels of the reception signals from the reception antennas 31 and 32, and selects the digital information having the higher signal level.
Control. The decoding unit 37 decodes the digital information selected by the selection switch 36.

[0003]

In the above-mentioned conventional antenna selection diversity receiving system, especially when the fading speed is high, there is a delay time between the detection and comparison of the reception level and the actual switching of the reception antenna. Since the reception level may fluctuate between antennas, there is a problem that an optimum reception antenna having the highest reception level is not always selected.

An object of the present invention is to provide an antenna selection diversity receiving system capable of selecting an optimum receiving antenna with a reliable and simple circuit configuration even when a fading speed is high.

[0005]

According to the antenna selection diversity receiving method of the present invention, the time from when a received signal arrives at each of a plurality of receiving antennas to when demodulated digital information reaches each of the selection switches is obtained. A delay circuit is provided so that the time from when the reception signal arrives at the reception antenna to when the reception level is detected and compared and the selection switch is actually controlled becomes equal. Specifically, a plurality of receiving antennas, a plurality of receiving units respectively connected to the receiving antennas to demodulate a received signal into digital information, and one of the digital information output from the plurality of receiving units. A selection switch that selects according to a control signal; and a reception switch that detects and compares the signal levels of the plurality of reception signals and generates the control signal so as to select digital information of the reception signal having the maximum level, and sends the control signal to the selection switch. In an antenna selection diversity reception system having a level comparison unit, a signal delay time from the time when the received signal arrives at the receiving antenna until the digital information is demodulated into the digital information and reaches the selection switch,
A delay unit is provided to adjust a delay amount so that a switching delay time from when the reception signal is input to the reception level comparison unit to when the selection switch is controlled becomes equal.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. The receiving units 3 and 4 receive and demodulate the received signals S1 and S2 received by the receiving antennas 1 and 2, respectively.
It outputs digital information D11 and D21, respectively. The delay circuits 5 and 6 respectively apply a predetermined amount of delay to the digital information D11 and D21 to provide the digital information D12 and D2.
Output as 2. The selection switch 7 controls the control signal C12
, One of digital information D12 and D22 is selected. The decoding unit 8 decodes the digital information D3 selected by the selection switch 7.

[0008] The reception level comparison section 9 receives the reception signals S1, S
2, a control signal C1 for switching the selection switch 7 so as to detect and compare the signal levels of the received signals and to select digital information having the higher received level.
Send 1 The delay circuit 10 delays the control signal C11 by a predetermined amount and outputs it as a control signal C12.

Here, from the time when the received signals S1 and S2 arrive at the receiving antennas 1 and 2, the digital information demodulated by the receiving units 3 and 4 are respectively delayed by the delay circuits 5 and 6 and arrive at the selection switch 7. The time required to perform the operation is referred to as a signal delay time Ta. Further, from the time when the reception signals S1 and S2 arrive at the reception antennas 1 and 2, the control signal generated by the reception level comparison unit 9 is delayed by the delay circuit 10 and arrives at the selection switch 7, and the selection switch is actually activated. Assuming that the time until control is the switching delay time Tb, Ta
= Tb, the delay amount of the delay circuit is set.

Next, the operation will be described with reference to FIG.

The received signals S1 and S2 arriving at the receiving antennas 1 and 2, respectively, change their levels as shown in FIG. The digital information included in the received signal S1 is
The digital information indicated by the mark and included in the received signal S2
This is indicated by a mark. The digital information having the higher reception level is indicated by ○ and Δ, and the digital information having the lower reception level is indicated by ● and ▲. The digital information D12 and D22 arriving at the selection switch 7 are delayed by a signal delay time Ta as shown.

On the other hand, at time t1, t2, and t3 when the reception level reverses, the reception level comparison section 9 outputs the control signal C1.
1, the selection switch 7 switches the switching delay time Tb
It operates in response to the control signal C12 delayed by only a predetermined time. Here, by setting the delay time Ta = Tb, even when the fading speed is high, the selection switch 7 allows the digital information (方, Δ) of the higher reception level to be obtained.
Can always be reliably selected, so that the digital information D3 having good signal quality can be sent to the decoding unit 7.

[0013]

As described above, according to the present invention, by setting the signal delay time Ta and the switching delay time Tb to be equal, even when the fading speed is high, the reception level is always higher. And an optimal diversity effect can be obtained. Also, since only a delay circuit is provided, it can be realized with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the present invention.

FIG. 3 is a block diagram showing a conventional example.

[Explanation of symbols]

1, 2 receiving antenna 3, 4 receiving section 5, 6, 10 delay circuit 7 selection switch 9 reception level comparing section C11, C12 control signal D11, D21, D12, D22, D3 digital information S1, S2 received signal Ta signal delay time Tb switching delay time

Claims (2)

[Claims] A plurality of receiving antennas, a plurality of receiving units respectively connected to the receiving antennas for demodulating received signals into digital information, and one of the digital information output from the plurality of receiving units. A selection switch that selects according to a control signal; and a reception switch that detects and compares the signal levels of the plurality of reception signals and generates the control signal so as to select digital information of the reception signal having the maximum level, and sends the control signal to the selection switch. In the antenna selection diversity reception system having a level comparison unit, the signal delay time from the time when the received signal arrives at the receiving antenna until it is demodulated into digital information and reaches the selection switch, and the received signal is The switching delay time from when the signal is input to the reception level comparison unit until the selection switch is controlled is equal to An antenna selection diversity receiving method characterized by being set as follows. 2. The antenna selection diversity reception system according to claim 1, wherein a first delay unit is provided between the plurality of reception units and the selection switch to delay transmission of the digital information. An antenna selection diversity reception method, comprising: a second delay unit provided between a reception level comparison unit and the selection switch to delay transmission of the control signal.