JPH10322254A - Antenna switching diversity system - Google Patents

Abstract

(57) [Problem] To provide an antenna switching diversity system capable of maintaining good communication quality by selecting and transmitting an antenna in which the reception state of a mobile station will be the best. A base station has a plurality of antennas.
11-4, receivers 13-1 to 13-4 and switch 12-
1 to 12-4, a transmitter 19 and a mobile station 30
During transmission, the antennas 11-1 to 11-4 are connected to the receivers 13-1 to 13-4, and the reception level of the reception burst received by each antenna from the output of the receiver and the error of the reception data are output. Detecting the state, from the reception level of the received burst in the past and the error state of the received data, determine which of the plurality of antennas should be used to transmit from the antenna at the transmission timing of the base station to determine the best reception state of the mobile station. A prediction circuit 16 for prediction is provided, and an antenna and a transmitter, which are predicted by the prediction circuit to have the best reception state of the mobile station at the time of transmission from the base station, are connected to a transmitter by a switch to perform transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system in which communication is performed between a base station and a plurality of mobile stations in a burst transmission / reception manner by time division. The present invention relates to an antenna switching diversity system for improving the degradation of the base station side.

[0002]

2. Description of the Related Art In mobile communication, there is a problem that the reception level is degraded due to fading caused by the movement of a mobile station and the quality of communication is degraded. A mobile station and a base station each have a mobile station, and a diversity system for selecting an output of a receiver having the highest reception level is adopted.

[0003] The diversity system has a drawback that the mobile station equipment is large and complicated and difficult to miniaturize because there are a plurality of antennas and receivers on the mobile station side. There is an antenna switching diversity system disclosed in the gazette.

[0004] The antenna switching diversity system uses two or more antennas, the same number of receivers connected to the antennas at the time of reception, one transmitter switchable to each antenna, and each reception burst for each reception burst. A storage circuit for storing the reception level of the receiver, a prediction circuit for predicting a subsequent reception level based on the stored reception level, a selection circuit for selecting a receiver output based on the predicted reception level, and a transmission based on the predicted reception level The base station has a switching means for switching between the mobile station and a desired antenna.

[0005]

However, in the above antenna switching diversity system, an antenna having good propagation conditions of a radio wave is predicted only by the reception level of each antenna in the prediction circuit. However, there is a problem that the antenna may be selected in spite of the poor propagation condition, and the communication quality may be degraded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and eliminates the above-mentioned problems. At the transmission timing of the base station, an antenna which will provide the best reception condition on the mobile station side is selected and transmitted. An object of the present invention is to provide an antenna switching diversity system capable of maintaining good communication quality by performing the method.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a mobile communication system in which communication between a base station and a plurality of mobile stations is performed in a burst-like manner by time division. An antenna, the same number of receivers, switching means, and transmitters as the antennas are provided, and while the mobile station is transmitting, each antenna and the receiver are connected by the switching means, and each antenna receives from the output of the receiver. The reception level of the reception burst and the error state of the reception data to be detected are detected, and from the reception level of the reception burst and the error state of the reception data in the past, the transmission timing of the base station includes a plurality of antennas,
Prediction means for predicting from which antenna the reception state of the mobile station will be the best when provided, and switching means for switching the antenna and the transmitter predicted by the prediction means that the reception state of the mobile station will be the best when transmitting from the base station And transmission is performed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a system configuration example of mobile communication using the antenna switching diversity system of the present invention. In the figure, 10 is a base station, 30 is a mobile station, and the base station 10 and a plurality of mobile stations 30-1, 30-
Communication is carried out between 2,.

Each of the mobile stations 30-1, 30-2,... Is a mobile station having only one antenna 31. The base station 10 has four base station antennas 11-1 to 11-4,
Four switchers 12-1 to 12-4 and four receivers 13-
1 to 13-4, four demodulators 14-1 to 14-4, a storage circuit 15, a prediction circuit 16, a synthesis circuit 17, and a selection circuit 18
And a transmitter 19.

In the mobile communication system having the above-described configuration, when the mobile station 30 transmits, the base station antenna 11-1
11-4 are connected to the receivers 13-1 to 13-4 by switches 12-1 to 12-4, respectively.
1 to 13-4, the reception level of the reception burst and the error state of the reception data demodulated by the demodulators 14-1 to 14-4 are stored in the storage circuit 15, and the demodulators 14-1 to 14-4. The output of 14-4 is output to the synthesis circuit 17.

As will be described in detail later, the prediction circuit 16 stores the past base station antennas 11-1 stored in the storage circuit 15.
Based on the reception level of the reception burst received by the base station antennas 11-1 to 11-4 and the error state of the received data, if any one of the base station antennas 11-1 to 11-4 is transmitted at the transmission timing, It is predicted whether the reception state of the station 30 is the best, and the base station antennas (11-1 to 11-) which predict that the reception state of the mobile station 30 predicted by the prediction circuit 16 at the transmission timing of the base station 10 is the best. 4) and the transmitter 19 are connected to the switchers (12-1 to 12-12).
-4), and transmit.

FIG. 2 is a diagram showing an example of the configuration of a reception / transmission burst, and FIG. 3 is a diagram showing an example of a slot configuration. A short burst is transmitted from a plurality of mobile stations 30 to the base station 10, and the base station 10 transmits a plurality of reception bursts (Rx1, Rx2,
Rx3, Rx4) appear. In the base station 10, each mobile station 3
Transmit with a short burst for 0. A plurality of transmission bursts of the base station (Tx1, Tx1,
2, Tx3, Tx4).

The mobile station 30-1 and the base station 10 correspond to the first station in FIG.
It is assumed that communication is performed in the slot. The base station 10 receives all the base station antennas 11-1 to 11-11 at the reception slot timing.
-4 via the switches 12-1 to 12-4.
1 to 13-4, and each base station antenna 11-1 to 11-1
The reception level of the reception burst is stored in the storage circuit 15 for each 1-4, and furthermore, the reception signal is demodulated by the demodulators 14-1 to 14-4 to obtain a signal having good reception quality or a signal having a high reception quality.
Are processed as reception signals.

At this time, the reception burst of the base station 10 includes:
As shown in FIG. 3, an error detection code (CRC in FIG. 3) of the received data is included, and it is determined whether or not the received data has been successfully received without error.
Each base station antenna 11-1 determines whether there is an error in the received data.
１１11-4 are stored in the storage circuit 15.

FIGS. 4A and 4B show the respective base station antennas 11-A at time A (past) and time B (current) in FIG.
It is a figure which shows the example of the reception level of 1-11-4, and the presence or absence of an error of the received data. In FIG. 4A, the reception level is estimated by predicting the reception level at the time point C based on the reception level of the reception burst at the time point A and the reception level of the reception burst at the time point B. Is estimated at the time point C on the extension line connecting. From the reception levels at the time points A and B, the reception level of the base station antenna predicted at the time point C in FIG.
1-3> Base station antenna 11-1> Base station antenna 11
-4> base station antenna 11-2.

On the other hand, in FIG.
The presence or absence of an error in the received data at the time is determined by the base station antenna 1
1-1 has an error at time A and time B, the base station antenna 11-2 has no error at time A and time B, the base station antenna 11-3 has an error at time A, no error at time B, and the base station antenna No. 11-4 shows no error at the time points A and B.

As described above, the reception level of the base station antenna predicted at the time point C in FIG. 2 is higher in the base station antennas 11-1 and 11-3 than in the base station antenna 11-4, If the received data received by -1 and 11-3 include an error, the base station antennas 11-1 and 11-3 are receiving interference from another radio or are affected by fading. Probability is high. Therefore, the selection circuit 18 selects the base station antenna 11-4 at the time point C in FIG. 2, connects the transmitter 19 to the base station antenna 11-4 via the switch 12-4, and
-1 and the base station 10 perform communication. As described above, not only the reception level but also the reception state (whether there is an error in the reception data)
By selecting a base station antenna selection factor,
It is possible to provide more stable mobile communication with good communication quality.

FIG. 5 is a flowchart showing a process of estimating a reception level of a reception burst of a base station antenna, performing an error check, and selecting a base station antenna to be transmitted. First, the prediction circuit 16 detects the current reception level LtB (time point B in FIG. 2) of each of the base station antennas 11-1 to 11-4 (step ST1). Next, each base station antenna 11-1 to 11-4
The reception levels of the base station antennas 11-1 to 11-4 at the base station transmission timing (point C in FIG. 2) are predicted from the reception level LtA of the past (point A in FIG. 2) and the current reception level LtB. (Step ST2). Subsequently, the past and present reception states (presence or absence of reception data errors) of each of the base station antennas 11-1 to 11-4 are checked (step ST3).

Next, the selection circuit 18 checks whether or not there is a base station antenna having no error in received data both in the past and the present (step ST4). If there is an error-free base station antenna, the base station antenna having the maximum predicted reception level is selected from the error-free base station antennas at the time of the base station transmission timing (point C in FIG. 2) (step ST5). . If there is no error-free base station antenna, the base station antenna with the highest predicted reception level at the base station transmission timing is selected from all the base station antennas (step ST6).

In the above embodiment, four base station antennas 11 (11-1, 11-2, 11-3, 11-
Although the case of 4) has been described as an example, it is obvious that the number of base station antennas is not limited to this.

[0021]

As described above, according to the present invention, the reception level of the reception burst received by each antenna and the error state of the reception data are detected, and the reception level of the reception burst and the error state of the reception data in the past are detected. From, from the plurality of antennas at the transmission timing of the base station, from which antenna when the best reception state of the mobile station is predicted, the antenna and the transmitter are connected, and the transmission is performed. Such excellent effects as described above can be obtained.

(1) By adding the reception level of the reception burst and the error state of the reception data to the determination factor at the time of selecting the antenna, accurate prediction can be made, and the improvement of communication quality can be expected. Simplification and miniaturization can be achieved, and cost reduction can be achieved.

(2) Since an antenna in which received data has an error is not selected at the time of transmission, adverse effects are less likely to occur even when an antenna failure or the like occurs.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a system configuration of mobile communication using an antenna switching diversity system according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of a reception and transmission burst.

FIG. 3 is a diagram showing a slot configuration example.

4 (a) and 4 (b) are diagrams showing examples of the reception level of each base station antenna and the presence / absence of an error in received data at the time points A and B in FIG.

FIG. 5 is a diagram showing a processing flow for predicting a reception level of a reception burst of a base station antenna, performing an error check, and selecting a transmission base station antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Base station 11-1-4 Base station antenna 12-1-4 Switch 13-1-4 Receiver 14-1-4 Demodulator 15 Storage circuit 16 Prediction circuit 17 Synthesis circuit 18 Selection circuit 19 Transmitter 30 Mobile station 30-1 mobile station 30-2 mobile station 31 antenna

Claims (1)

[Claims] 1. In mobile communication in which communication is performed between a base station and a plurality of mobile stations in a burst-like manner by time division, the base station includes a plurality of antennas, the same number of receivers and switching means as the antennas, A transmitter is provided, and while the mobile station is transmitting, the switching means connects each antenna to a receiver, and the reception level of the reception burst received by each antenna from the output of the receiver and the error of the reception data. A state is detected, and from the reception level of the reception burst in the past and an error state of reception data, the reception state of the mobile station becomes the best when transmitting from any of the plurality of antennas at the transmission timing of the base station. A predicting means for predicting whether or not the antenna and the transmitter, which have been predicted by the predicting means to have the best reception state of the mobile station at the time of transmission by the base station, are connected by the switching means. Antenna switching diversity scheme and performs transmission.