JPH11122152A - Reception diversity system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the scale of a system by providing an omnidirectional antenna and a sector antenna and selecting an antenna depending on a reception level so as to increase a sector antenna tracking speed and using only two receivers independently of the sector division number. SOLUTION: The system adopts an omnidirectional antenna 2 and a sector antenna 1 and either of the antennas is selected depending on a reception level. In the case of reception, the reception level is detected by the omnidirectional antenna at a head of a burst and the sector antenna 1 stored at the same burst of a preceding frame to select a communication antenna. In the case the omnidirectional antenna 2 is selected for the communication antenna, reception level of all the sector antennas at the same burst is measured and compared in time division by one receiver and the result is stored and reflected on a succeeding frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna switching diversity system, and more particularly to an antenna switching diversity system using a non-directional antenna and a sector antenna in TDMA / TDD wireless communication.

[0002]

2. Description of the Related Art Conventionally, as a first conventional example of this kind of diversity receiving apparatus, there is a technique disclosed in Japanese Patent Application Laid-Open No. 63-63119.

In FIG. 6 showing the basic block configuration of this first conventional example, an omnidirectional antenna 2 covering 360 degrees with one antenna and a 360 degrees covering with a plurality of directional antennas. Sector antenna group 1a, 1
In the reception diversity system using b, in general, two sector antennas are selected from the group of sector antennas 1a and 1b based on the result of the first level measurement, and three antennas including the omnidirectional antenna 2 are selected. Diversity operation was started by using this.

[0004] Regarding unselected sector antennas, the reception level is measured when the reception level of the selected sector antenna has decreased for a certain period of time.

Further, a receiver is required for each sector antenna for measuring the reception level.

[0006] As a second conventional example, Japanese Patent Laid-Open No. 6-9022 is disclosed.
No. 7 discloses a technique disclosed therein.

The second prior art aims to provide a diversity receiving apparatus having good transmission quality by mutually compensating for shortcomings by efficiently combining the conventional diversity techniques. A reception level detector that detects and compares the reception levels of a plurality of receivers, a phase likelihood detector that detects and compares the phase likelihood of each of the receivers, a first switch, and a second switch. Is provided, and the phase likelihood of the output signal of the demodulator of each of the receivers is detected and compared by the phase likelihood detector, and the first switch is operated with the signal to determine the higher phase likelihood. An output signal is selected and output, and the reception level detector detects and compares the reception levels of the respective receivers, and operates the second switch with the signal to select and output the output signal having the higher reception level. , And each of the first and second switches First, and second to providing error correction code decoder, the first error rate estimator of error rate of the output of the second error correction code decoder for estimating compared to decode the force,
A third switch is provided, output signals of the first switch and the second switch are decoded by the error correction code decoder, an error rate at that time is estimated by an error rate estimator, and the estimation is performed. The output signal having the smaller error rate is selected by the third switch and output as received data.

[0008]

However, the prior art described above has the following drawbacks.

A first problem is that the tracking speed of the sector antenna is low in the case of diversity based on reception level detection.

[0010] The reason is that, in the conventional technique, it is impossible to measure the reception level by all the sector antennas in one reception burst.

The second problem is that the size of the apparatus is increased when performing diversity.

[0012] The reason is that a plurality of receivers are required to select a sector antenna.

In particular, the second conventional example requires an extremely large number of components.

In the antenna switching diversity system of a base station in TDMA / TDD wireless communication, antenna switching is performed by comparing input levels received by a plurality of antennas and selecting a larger antenna. Was. However, at the time of level measurement, since the level of the interference wave from a different direction from the terminal station is also detected, when one of the antennas is omnidirectional and the other is a directional sector switching antenna, It was difficult to perform optimum antenna switching simply by comparing the levels due to the difference in the characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made to solve the above-mentioned disadvantages inherent in the prior art. And a communication area is divided into a plurality of sections, and the same number of directional antennas as the number of divisions are arranged to provide a sector antenna that covers the communication area by 360 degrees. It is another object of the present invention to provide a novel antenna switching diversity system capable of increasing the sector antenna tracking speed and reducing the number of receivers to two, regardless of the number of sector divisions, to reduce the size of the apparatus.

[0016]

In order to achieve the above-mentioned object, a receiving diversity system according to the present invention, when an omni-directional antenna is selected as a communication antenna, requires that all sector antennas be used in a receiving burst. A means for measuring and storing the reception level by switching to division (FIG. 1), and a means for measuring and comparing the reception levels of the omnidirectional antenna and the stored sector antenna at the beginning of the reception burst and selecting a communication antenna ( 2).

The receiving diversity system according to the present invention uses an omni-directional antenna and a directional sector switching antenna. When performing antenna switching diversity, an input level from each antenna is detected, After weighting the detected value of the input level of the switching antenna and comparing it, the antenna switching control is performed so as to select the sector switching antenna even if the input from the sector switching antenna is small to some extent.

[0018]

At the head of a reception burst, the reception level is detected by the sector antenna which has selected the omnidirectional antenna and the stored sector. Only two receivers, one for the omnidirectional antenna and the other for the sector antenna, are used. The level is compared by this level detection, a communication antenna is selected, and a message is received.

When the omnidirectional antenna is selected as the communication antenna, all the sector antennas are switched to time division in the reception burst, and the reception level is measured.
The sector having the maximum reception level is stored. For this reason, when the omnidirectional antenna is selected as the communication antenna, it is possible to measure the reception levels of all the sector antennas, which can be realized with two receivers.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described in detail with reference to FIG.

FIG. 1 is a block diagram showing a first embodiment of the present invention. Here, communication between the base station and the terminal station will be described assuming that the own station is a base station.

[Explanation of Configuration] Referring to FIG. 1, a radio signal from a terminal station is received by a sector antenna 1 (1a, 1b) and an omnidirectional antenna 2. In the sector antenna group 1, only one sector antenna is selected by the sector changeover switch 17. The omnidirectional antenna 2 is connected to the transmitter 4 or the receiver 6 by the antenna changeover switch 3 or terminated. Similarly, sector switch 1
7 is connected to the transmitter 4 or the receiver 7 by the antenna changeover switch 3 or terminated.

The receiver 6 performs amplification and frequency conversion,
Connected to level detection circuit 8. Similarly, the receiver 7
Performs amplification and frequency conversion, and is connected to the level detection circuit 9. Each of the level detection circuits 8 and 9 measures the reception level, and the level detection result value is determined by the level comparison circuit
0, and the received signals are sent to the changeover switch 12, respectively.

The level comparison circuit 10 compares the respective level detection result values, and compares the result with the switching control circuit 11.
Output to The switching control circuit 11 stores the comparison result in association with the current reception burst,
Is controlled so as to select a system having a high reception level. The switching control circuit 11 includes, for example, the level comparison circuit 1
It is possible to use a general configuration including a table (memory) for storing the output of “0” corresponding to the burst at that time and a timing generation circuit for generating a timing signal for reading the information stored in the table. it can.

The received signal selected by the switch 12 is connected to the demodulator 13 and demodulated.

On the transmitting side, first, the transmission data signal is
And frequency conversion and amplification in the transmitter 4. The output of the transmitter 4 is connected to the antenna changeover switch 3 and transmitted from the sector antenna group 1 or the omnidirectional antenna 2. The antenna changeover switch 3 is controlled based on the result of comparison with the reception burst stored in the switching control circuit 11 and the relationship between the transmission burst and the reception burst allocated to the terminal station.

The control of the sector changeover switch 17 is performed by a sector changeover control circuit 16. When an omnidirectional antenna is selected as the communication antenna, the level detection circuit 9 detects the reception level of the received burst.

At this time, as shown in FIG. 2, the reception levels of all the sectors are detected in a time division manner by switching the sector changeover switch 17. The level detection values of all the sectors are compared with the reception level by the level comparison circuit 14, and the comparison result is reported to the sector storage circuit 15.

The sector storage circuit 15 stores the data corresponding to the current reception burst.

Next, an example of a frame format according to the present invention will be described with reference to FIG.

Referring to FIG. 2, the frame format of the present invention is used by allocating bursts between a base station and a plurality of terminal stations. The burst is composed of a preamble part, a unique word part, and a message part.

The predetermined range at the head of the reception burst is
The sector antenna 1 and the omnidirectional antenna 2 that have selected the stored sector each measure the reception level. According to the result, at the communication antenna switching timing,
An antenna and a receiver system for receiving are selected by the changeover switch 12.

At this time, when the omnidirectional antenna 2 is selected as the communication antenna, the reception level of the message part is measured in a time division manner in all the sectors (6 in FIG. 2) of the sector antenna 1. Here, the sector having the maximum reception level is stored in the sector storage circuit 15. Sector storage circuit 1
The sector stored in No. 5 is used as a candidate for selecting a communication antenna in the same reception burst of the next frame.

FIG. 3 is a flowchart of the first embodiment according to the present invention, showing the above operation.

Referring to FIG. 3, reception is started first,
In step S1, the sector antenna 1 stores the sector storage circuit 15
Is selected. next,
In step S2, it is determined whether the reception level of the sector antenna 1 is higher than the reception level of the omnidirectional antenna 2.

If the reception level of the sector antenna 1 is larger than the reception level of the omnidirectional antenna 2, the sector antenna is selected as the communication antenna in step S3, and the reception ends.

If no in step S2, that is, if the reception level of the omnidirectional antenna 2 is higher than the reception level of the sector antenna, the omnidirectional antenna 2 is selected as a communication antenna in step S4.

If a no determination is made in step S2, the reception level of each sector of the sector antenna 1 is detected by the level detection circuit 9 in step S5 simultaneously with the execution of step S4. And the sector having the highest reception level is stored in the sector storage circuit 15.

FIG. 4 is a timing chart showing the above operation of the first embodiment according to the present invention.

Referring to FIG. 4, when omnidirectional antenna 2 is selected, each sector of sector antenna group 1 is switched to time division in one reception burst in one frame. Each time, the level of the antenna 1 is detected and compared.

FIG. 5 is a block diagram showing a second embodiment according to the present invention. In the second embodiment, the detection level received by the sector antenna 2 is weighted by a weighting circuit 1.
8 is weighted according to the first comparison point.
Is different from the embodiment of the present invention.

Referring to FIG. 5, the number of errors in the received data is detected by the error detector 19, and the result is sent to the switching control circuit 11. When the number of errors exceeds a certain threshold, the switching control circuit 11 switches the switch based on the switching information from the level comparison circuit 10.

The method of level comparison will be described below.

The level received by the omnidirectional antenna 2 is detected by the level detection circuit 8 and input to the level comparison circuit 10. Further, the level received by the sector switching antenna 1 is detected by the level detection circuit 9, and the result obtained by weighting the result by the weighting circuit 18 is input to the level comparison circuit 10.

The level comparison circuit 10 compares the respective inputs and uses the sector switching antenna 1 having directivity.
When performing antenna switching diversity, the input level from each antenna is detected, and the detected value of the input level of sector switching antenna 1 is weighted and compared. Also, it transmits switching information to the switching control circuit 11 so as to select the sector switching antenna 1.

As described above, by weighting the sector switching antenna 1 at the time of comparing the reception levels, it is possible to make the sector switching antenna 1 less susceptible to interference waves arriving from directions different from the terminal station.

[0047]

The present invention is constructed and operates as described above. According to the present invention, the following effects can be obtained.

The first effect is that the followability of the sector antenna is good.

The reason is that when an omnidirectional antenna is selected as the communication antenna, the reception levels of all the sector antennas can be measured and the results can be reflected in the next frame.

The second effect is that the device can be downsized.

The reason is that, since the level of the sector antenna group is detected in a time division manner, it does not depend on the number of sector divisions.
Since it is configured with one receiver, the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a reception diversity system according to the present invention.

FIG. 2 is a reception level timing chart in the first embodiment of the reception diversity system of the present invention.

FIG. 3 is a diagram showing an antenna control flow in the first embodiment of the reception diversity system of the present invention.

FIG. 4 is a timing chart showing the operation of the first embodiment according to the present invention.

FIG. 5 is a block diagram showing a second embodiment according to the present invention.

FIG. 6 is a block diagram showing an example of a conventional reception diversity system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sector antenna 2 omnidirectional antenna 3 antenna switch 4 transmitter 5 encoder 6 receiver (for nondirectional antenna) 7 receiver (for sector antenna) 8 level detector circuit (none 9 ... Level detection circuit (for sector antenna) 10 ... Level comparison circuit 11 ... Switch control circuit 12 ... Changeover switch 13 ... Demodulator 14 ... Level comparison circuit 15 ... Sector storage circuit 16 ... Sector switching control circuit 17 ... Sector changeover switch 18 ... Weighting circuit 19 ... Error detector 20 ... TDD switch control circuit

Claims (9)

[Claims] An omnidirectional antenna that covers a communication area 360 degrees, and a sector antenna that covers a communication area 360 degrees by dividing the communication area into a plurality and arranging the same number of directional antennas as the number of divisions. In an antenna switching diversity system that selects an antenna according to a reception level, at the time of reception, the reception levels received by an omnidirectional antenna and a sector antenna are detected and compared at the head of a reception burst, and communication is performed based on the comparison result. If an omni-directional antenna is selected as the communication antenna and the omni-directional antenna is selected as the communication antenna, the reception levels measured by all the sector antennas having directivity in each direction in the same burst are measured. And a reception diversity method for storing the measurement results. 2. When the omnidirectional antenna is selected as the communication antenna, the reception level received by all the sector antennas having directivity in each direction in the same burst is measured in a time division manner. The reception diversity system according to claim 1, further comprising: 3. A sector for detecting a reception level received by the omni-directional antenna and the sector antenna at a head portion of a reception burst is a result of measuring a reception level by all of the stored sector antennas. The reception diversity system according to claim 1, further comprising: 4. A directional first antenna group, an omnidirectional second antenna, a first switch for switching and selecting between the first antenna group and a second antenna, and A second switch for switching and selecting one antenna group; a first receiver for amplifying and frequency-converting a received signal received by the first antenna; and detecting an output level of the first receiver First level detecting means, a second receiver for amplifying a received signal received by the second antenna and frequency converting the same, and a second level detecting means for detecting an output level of the second receiver. Means, a first level comparing means for comparing the levels detected by the first and second level detecting means, and an output signal of the first level comparing means being inputted to control the first switch. First switching control means; The first control is controlled by the switching control means.
And a third changeover switch for selectively selecting the output of the second level detection means and outputting the selected output to the demodulator. 5. When the second antenna is selected as the communication antenna, a reception level of the reception burst is detected by the first level detection means, and a second comparison is made between the detection results. Level comparison means, storage means for storing a comparison result of the second level comparison means, and second switching control means for controlling switching of the second changeover switch by an output of the storage means, The reception diversity system according to claim 4, further comprising measuring a reception level received by the first antenna group in a time-division manner. 6. The system according to claim 1, wherein said first switch control means stores a comparison result of said first level comparison means in association with a current reception burst, and sets said third changeover switch to a system having a high reception level. 5. The reception diversity system according to claim 4, further comprising controlling to select. 7. When the second antenna is selected, all of the first antennas are switched to time division in the reception burst and the reception level is measured. 6. The reception diversity system according to claim 5, further comprising storing the data in a storage unit and reflecting the storage result in a next frame. 8. A directional first antenna group, a non-directional second antenna, a first changeover switch for selecting and selecting between the first antenna group and the second antenna, and A first receiver for amplifying and frequency-converting a received signal received by one antenna, a first level detecting means for detecting an output level of the first receiver, and a signal received by the second antenna A second receiver for amplifying the received signal and converting the frequency; and a second receiver for detecting an output level of the second receiver.
Level detecting means, weighting means for weighting the detection result of the second level detecting means, level comparing means for comparing the output of the weighting means with the output of the first level detecting means, Switching control means for inputting the comparison result of the comparing means, and a second changeover switch controlled by the output of the switching control means for selectively selecting the output of the first and second level detecting means and outputting the selected output to the demodulator And a receiving diversity system. 9. An error detecting means is provided between the demodulator and the switching control means, and when an error is detected by the error detecting means, the second switching switch is switched via the switching control means. The receiving diversity system according to claim 8, further comprising controlling.