JP2001345746A - Radio communication method as well as base station and terminal station performing radio communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication method wherein a plurality of small terminal stations are present and a communication is realized with high reliability when the communication is simultaneously performed to the terminal stations from a base station. SOLUTION: In the communication toward the terminal stations from the base station, the base station 10 simultansouly transmits modulating signals from two antennas 11, 12 whose polarized waves are different. A first terminal station 13 receives the modulating signals by two antennas 14, 15. A second terminal station 16 receives the modulating signals by two antennas 17, 18. In the communication toward the base station from the terminal stations, the first terminal station 13 compares the reception quality of the modulating signal received by the first antenna 14 with the reception quality of the modulating signal received by the second antenna 15. When the former is higher, the modulating signal is transmitted toward the base station from the first antenna 14. When the latter is higher, the modulating signal is transmitted toward the base station from the second antenna 15. The same is applied also to the second terminal station.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication method, a base station and a terminal station for performing radio communication, and more specifically, to a radio communication method and a radio communication for alternately using the same frequency band. To a base station and a terminal station.

[0002]

2. Description of the Related Art FIG. 6 is a diagram for explaining a conventional technology, and is a conceptual diagram for explaining a radio communication method for alternately performing communication using the same frequency band as shown in Japanese Patent Publication No. Hei 7-44490. It is. In FIG. 6, a base station 60 includes two antennas 61 and 62 for diversity. The terminal station 63 has one antenna 64.

[0003] A terminal station 63 transmits a modulated signal from an antenna 64 to a base station. The base station 60 receives the signal with the two antennas 61 and 62 and determines which antenna has a higher reception level. Transmission from the base station 60 to the terminal station 63 is performed using either the antenna 61 or 62 having the higher reception level.

As described above, the base station 60 uses the antenna having the smaller propagation loss with the antenna of the terminal station 63 among the two antennas for both reception and transmission.
Therefore, not only communication from the terminal station to the base station but also communication from the base station to the terminal station can be realized with high reliability.

[0005]

However, according to the prior art as described above, if there are a plurality of terminal stations and the base station attempts to communicate with those terminal stations at the same time, all terminal stations will be In some cases, reliable communication cannot be performed. Which of the two antennas of the base station has the smaller propagation loss depends on the opposite terminal station, and an antenna giving a large propagation loss is selected depending on the terminal station.

In order to solve the above problem, it is conceivable to provide a terminal station with two antennas to perform diversity reception to improve reliability. However, a terminal station usually needs to be small, and the distance between two antennas cannot be increased. Therefore, the effect is small when the propagation loss increases due to shadowing.

[0007] Therefore, an object of the present invention is to realize highly reliable communication when there are a plurality of small terminal stations and the base station intends to simultaneously communicate with these terminal stations.

[0008]

According to a first aspect of the present invention, there is provided a radio communication method for alternately performing communication between one base station and a plurality of terminal stations using a predetermined frequency band. Transmits first modulation signals having different polarizations simultaneously from the two antennas having different polarizations to the plurality of terminal stations,
The plurality of terminal stations each receive the first modulated signal having the different polarization with two antennas having different polarizations, and the one base station is configured to receive the first modulated signal having the higher reception quality of the received first modulated signal. The second modulated signal is transmitted toward

[0009] A second invention is a base station that performs communication alternately with a plurality of terminal stations using a predetermined frequency band, and wherein the first modulation with different polarizations to the plurality of terminal stations is performed. Two antennas having different polarizations for receiving signals and receiving second modulation signals having different polarizations from the plurality of terminal stations, respectively, and simultaneously supplying a first modulation signal to the two antennas It is characterized by comprising transmitting means and receiving means for inputting the second modulated signals having different polarizations supplied by the two antennas.

A third aspect of the present invention is a terminal station for alternately communicating with a plurality of terminal stations using a predetermined frequency band, wherein the first base station has different first polarizations having different polarizations. Two antennas having different polarizations for receiving a signal and transmitting the second modulation signal having different polarizations to the one base station, respectively, and two different polarizations provided by the two antennas are different from each other. Receiving means for inputting a first modulated signal; receiving quality comparing means for comparing which one of the two first modulated signals having different polarizations has higher quality; and generating the second modulated signal. Transmitting means, and antenna selecting means for selecting an antenna to which the high-quality first modulated signal is supplied based on the output of the reception quality comparing means and supplying the second modulated signal to the antenna. It is characterized by.

[0011]

(Embodiment 1) A wireless communication method according to Embodiment 1 of the present invention will be described.

FIG. 1 is a conceptual diagram illustrating a radio communication method performed using a base station and a plurality of terminal stations. Two terminal stations are shown for simplicity, but the configuration and operation are the same for three or more terminal stations. In FIG. 1, reference numeral 10 denotes a base station including a first antenna 11 and a second antenna 12, and reference numeral 13 denotes a first station including a first antenna 14 and a second antenna 15.
Is a second terminal station provided with a first antenna 17 and a second antenna 18. In the base station and the plurality of terminal stations, the first antenna and the second antenna have different polarizations. The first antennas of the base station and the respective terminal stations have polarizations suitable for transmission and reception, and the second antennas of the base station and the respective terminal stations have polarizations suitable for transmission and reception. Shall be.
The wireless communication path connecting the antennas 11 and 14 is 1
4P, a wireless communication path connecting the antennas 12 and 15 is named 15P, a wireless communication path connecting the antennas 11 and 17 is named 17P, and a wireless communication path connecting the antennas 12 and 18 is named 18P.

First, a method of communication from a base station to a terminal station will be described. The base station 10 simultaneously transmits a first modulated signal from two antennas 11 and 12 having different polarizations. The first terminal station 13 receives this first modulated signal with two antennas 14 and 15. At this time, 14P and 15P are used as wireless communication paths.
Since the polarizations of the two wireless communication paths are different, mutual interference between the two signals is small, and a large diversity effect can be obtained. The second terminal station 16 receives the first modulated signal on two antennas 17 and 18. In this case, two wireless communication paths, 17P and 18P, are used.
Since the polarizations of the two wireless communication paths are different, mutual interference between the two signals is small, and a large diversity effect can be obtained. As described above, a large diversity effect can be obtained simultaneously in a plurality of terminal stations.

Next, a method of communication from a terminal station to a base station will be described. Regarding this communication, a plurality of terminal stations sequentially transmit the second modulated signal, but do not transmit them at the same time. First
Terminal station 13 compares the reception quality of the first modulation signal received by the first antenna 14 with the reception quality of the first modulation signal received by the second antenna 15, and if the former is higher, the first From the antenna 14, the second antenna 15 if the latter is higher
Transmits a second modulated signal to the base station. If the former is high, the radio communication path 14P that gives high reception quality
When the latter is high, the wireless communication path 15P giving high reception quality is used, so that good communication can be performed from the terminal station to the base station. Similarly, good communication can be performed with the second terminal station 16.

Hereinafter, the configurations of the base station and the terminal station shown in FIG. 1 will be described more specifically. First, a base station according to Embodiment 1 of the present invention is described. FIG. 2 is a block diagram showing a configuration of the base station according to Embodiment 1 of the present invention. In FIG. 2, 21 is a first antenna having a certain polarization, 22 is a second antenna having a polarization different from that of the first antenna, and 23 is a first transmission / reception switch connected to the first antenna , 24 are second transmission / reception switches connected to the second antenna, 25 is a transmission unit, and 26 is an output distribution unit for distributing the output of the transmission unit.
And 27 is a transmission / reception switch 2
It is a receiving section that receives signals from 3 and 24. It is preferable that the distance between the first antenna 21 and the second antenna 22 is large in view of the diversity effect. Further, as the different polarizations of the antenna, there are vertical polarization and horizontal polarization, or left circular polarization and right circular polarization.

Next, the operation of the base station will be described separately for a transmission state and a reception state. In the transmission state, the transmission section 25 generates a transmission modulation signal. The distributor 26 divides the transmission modulation signal into two and supplies it to the transmission / reception changeover switches 23 and 24. The transmission / reception switches 23 and 24 select the Tx side shown in FIG. 1 and supply the distributed transmission modulation signals to the antennas 21 and 22. The antennas 21 and 22 radiate transmission modulation signals having different polarizations to a plurality of terminal stations. Since transmission modulation signals having different polarizations are radiated simultaneously, a good transmission modulation signal can be transmitted to any terminal station.

In the receiving state, the antennas 21 and 22 receive the received modulated signals having different polarizations from the terminal stations. The transmission / reception changeover switches 23 and 24 select the Rx side shown in FIG. 1 and supply two reception modulation signals received by the antennas 21 and 22 to the reception unit 27. The receiving section 27 demodulates the information sent from the terminal station by receiving the two received modulation signals. As a method of receiving the reception modulation signal, for example, there is a diversity reception method. This diversity receiving method includes selecting or combining two received modulated signals. As a criterion for selection or combination, there is a signal level or an error rate during demodulation. Which of the reception modulation signals received by the two antennas gives higher reception quality differs depending on the terminal stations facing each other. Therefore, highly reliable communication can be performed by diversity receiving the reception modulation signals received by the two antennas.

[0018] A terminal station according to Embodiment 1 of the present invention will be described. FIG. 3 is a block diagram showing a configuration of the terminal station according to Embodiment 1 of the present invention. In FIG. 3, 31 is a first antenna having a certain polarization, 32 is a second antenna having a different polarization from the first antenna, and 33 is a first transmission / reception switch connected to the first antenna , 34 is the second
Second transmission / reception switch connected to the antenna of
5 is a receiving unit for receiving signals from the transmission / reception changeover switches 33 and 34, and 36 is a reception unit for receiving the signals from the transmission / reception changeover switches 33 and 34.
A reception quality comparison unit for receiving a signal from
An antenna selection switch 8 switches the output of the transmission unit and supplies the output to the transmission / reception changeover switch 33 or 34. It is preferable that the distance between the first antenna 31 and the second antenna 32 is small in terms of miniaturizing the terminal station.
Furthermore, when a parabolic antenna is used, it is desirable that the parabolic surfaces of the two antennas be shared. Further, as the different polarizations of the antenna, there are vertical polarization and horizontal polarization, or left circular polarization and right circular polarization.

Next, the operation of the terminal station will be described separately for a reception state and a transmission state. In the receiving state, the antenna 31
And 32 receive received modulated signals having different polarizations from the terminal station. The transmission / reception changeover switches 33 and 34 select the Rx side shown in FIG. 2 and supply two reception modulation signals received by the antennas 31 and 32 to the reception unit 35. The receiving unit 35 demodulates the information sent from the base station by receiving the two received modulated signals. As a method of receiving the reception modulation signal, for example, there is a diversity reception method. This diversity receiving method includes selecting or combining two received modulated signals. As a criterion for selection or combination, there is a signal level or an error rate during demodulation. Diversity reception of modulated signals having different polarizations provides a large diversity effect and enables highly reliable communication. The reception quality comparison unit 36 compares the quality of the two received modulation signals and outputs a selection signal, and holds the selection signal in preparation for a transmission state described below. As a criterion for selecting the quality level, a signal level level or a demodulation error rate is low.

In the transmission state, the transmission section 37 generates a transmission modulation signal. The antenna selection switch 38 supplies the transmission modulation signal to the transmission / reception switch 33 or 34 based on the selection signal output from the reception quality comparison unit 36. First
If it is determined that the reception quality of the antenna 31 is high, select the side A in FIG.
, And when it is determined that the reception quality of the second antenna 32 is high, the side B in FIG. 3 is selected and the transmission modulation signal is supplied to the second transmission / reception switch 34. The transmission / reception changeover switches 33 and 34 are connected to the T
The transmission modulation signal is supplied to the antennas 31 and 32 by selecting the x side. Either of the antennas 31 and 32 radiates the transmission modulation signal toward the base station. Since an antenna corresponding to the radio communication path giving high reception quality is selected, a good transmission modulation signal can be transmitted to the base station.

Next, a processing flow of the wireless communication method according to the first embodiment of the present invention will be described. First, a processing flow of the wireless communication method of the base station will be described. FIG.
4 is a flowchart of a radio communication method of a base station according to Embodiment 1 of the present invention.

(S400) It is determined whether the current state is the transmission state or the reception state. S4 if receiving
Go to 11.

(S401) The transmitting section 25 modulates the transmission signal to generate a modulated signal.

(S402) In the distributor 26, the modulated signal is divided into two and supplied to two antennas.

(S403) In the antennas 21 and 22, the polarizations of the two modulated signals are set to be different from each other.

(S404) The antennas 21 and 22 emit modulated signals of two different polarizations, and the process ends.

It should be noted that steps S401 to S404 do not have to be sequential processes in which the next process is executed after the previous process is completed, but are usually executed in parallel.

(S411) The modulated signal is received by the antenna 21 or 22.

(S412) The receiving section 27 demodulates the received modulated signal, and ends.

Note that S411 and S412 do not need to be sequential processes in which the next process is executed after the previous process is completed, but are usually executed in parallel.

Next, a processing flow of the wireless communication method of the terminal station will be described. FIG. 5 is a flowchart of a radio communication method for a terminal station according to Embodiment 1 of the present invention.

(S500) It is determined whether the current state is the transmission state or the reception state. If the state is the reception state, the flow proceeds to S501. S5 if sending
Go to 11.

(S501) The antennas 31 and 32 receive modulated signals of two different polarizations.

(S502) The receiving section 35 demodulates the received modulated signal.

(S503) The reception quality comparison section 36 compares the quality of the two demodulated reception signals, outputs the result of the comparison as a selection signal, and ends the processing.

Steps S501 to S503 do not have to be sequential processes in which the next process is executed after the previous process is completed, but are usually executed in parallel.

(S511) The transmitting section 37 modulates the transmission signal to generate a modulated signal.

(S512) The antenna selection unit 38 refers to the selection signal output by the reception quality comparison unit 36,
Select the antenna with the higher reception quality.

(S513) The antenna 31 or 32 emits a modulation signal from the selected antenna, and the processing ends.

It should be noted that steps S511 to S513 do not need to be sequential processing in which the next processing is executed after the previous processing is completed, but are usually executed in parallel.

[0041]

According to the first aspect of the present invention, in the communication from the base station to the terminal station, since the modulated signals are transmitted from two antennas having different polarizations, the mutual interference of the radio communication paths is small, and the large diversity effect is obtained. Is obtained. In the communication from the terminal station to the base station, good communication can be performed because a wireless communication path giving high reception quality is selected for communication.

In the second aspect, the base station simultaneously radiates transmission modulation signals having different polarizations in the transmission state, so that a good transmission modulation signal can be transmitted to any terminal station. In the reception state, highly reliable communication can be performed by receiving the reception modulation signals received by the two antennas.

In the third invention, in the reception state,
By receiving modulated signals having different polarizations, highly reliable communication can be performed. In the transmission state, an antenna corresponding to the radio communication path giving high reception quality is selected, so that a good transmission modulation signal can be transmitted to the base station.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a wireless communication method according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a base station according to Embodiment 1 of the present invention.

FIG. 3 is a block diagram showing a configuration of a terminal station according to Embodiment 1 of the present invention.

FIG. 4 is a flowchart of a radio communication method of a base station according to Embodiment 1 of the present invention.

FIG. 5 is a flowchart of a wireless communication method of a terminal station according to Embodiment 1 of the present invention.

FIG. 6 is a conceptual diagram illustrating a conventional wireless communication method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Base station 11, 14, 17, 21, 31 First antenna 12, 15, 18, 22, 32 Second antenna 13 First terminal station 16 Second terminal station 23 First transmission / reception switch 24 2 transmission / reception changeover switch 25, 37 transmission unit 26 distributor 27, 35 reception unit 33 first transmission / reception changeover switch 34 second transmission / reception changeover switch 36 reception quality comparison unit 38 antenna selection switch

Claims (3)

[Claims] 1. A wireless communication method for alternately performing communication between one base station and a plurality of terminal stations using a predetermined frequency band, wherein the base station receives signals from two antennas having different polarizations. The first modulation signals having different polarizations are simultaneously transmitted to the plurality of terminal stations, and the plurality of terminal stations respectively receive the first modulation signals having different polarizations by two antennas having different polarizations. And transmitting a second modulated signal to the one base station from an antenna having high reception quality of the received first modulated signal. 2. A base station for alternately communicating with a plurality of terminal stations using a predetermined frequency band, comprising: transmitting a first modulated signal having different polarizations to the plurality of terminal stations; Two antennas having different polarizations for respectively receiving the second modulation signals having different polarizations from the plurality of terminal stations; and transmitting means for simultaneously supplying a first modulation signal to the two antennas; Receiving means for inputting the second modulated signals having different polarizations supplied by the two antennas. 3. A terminal station that performs communication alternately with one base station using a predetermined frequency band, comprising: receiving a first modulated signal having a different polarization from the one base station; , Two antennas having different polarizations for transmitting a second modulation signal having different polarizations to the one base station, respectively, and a first modulation having two different polarizations supplied by the two antennas. Receiving means for inputting a signal; reception quality comparing means for comparing which of the two first modulated signals having different polarizations has higher quality; transmitting means for generating the second modulated signal; Antenna selecting means for selecting an antenna to which the first modulation signal having high quality is supplied based on an output of the reception quality comparing means and supplying the second modulation signal to the antenna. Terminal station.