JPH0779205A - Same frequency radio communications system - Google Patents

Abstract

PURPOSE:To provide a radio relay system not generating interference even between the relays of the same frequency. CONSTITUTION:A repeater station 30 transmits the frequencies f1 and f2 the same as reception frequencies f1 and f2. When the interference is recognized in channel quality in a reception station or the reception levels of the transmission/reception stations 10, 20 and 40 and the repeater station 30, the transmission power of the repeater station or the transmission/reception stations is controlled and the interference is reduced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to digital wireless communications. Especially in a radio relay system in which there is a relay station between the transmitting station and the receiving station, in the same frequency relay or single frequency relay that receives the signal transmitted at f hertz and transmits at f hertz, from the transmission wave at the relay station The present invention relates to transmission power control for compensating for interference due to its own signal, such as interference between transmission and reception of a reception wave of a relay station or overreach interference from a transmission signal of a transmission station to a reception signal of a reception station.

[0002]

2. Description of the Related Art In a radio relay system, in order to suppress interference between transmission and reception as much as possible, transmission is performed at a frequency different from the frequency of a received signal in a relay station. In this case, two types of frequencies called low group and high group are prepared and used alternately for each relay station. This is called a dual frequency relay system. When the transmission signal is in the low group, the reception signal at the same station is generally in the high group to effectively use the frequency. This relationship is shown in FIG. Here, a circle indicates a terminal station or a relay station.

On the other hand, in the wireless transmission line, 8PSK, 1 is used to improve the line quality or increase the transmission capacity.
Since multi-level modulation such as 6QAM is applied, the relay distance may be shortened. At this time, in order to effectively use the existing relay station equipment, a method of newly installing a relay station in a section of the existing transmission line having a large distance between relay stations is used.

However, since the transmitting station or the receiving station transmits or receives signals of a plurality of transmission lines, their signal frequencies are the same. Here, when one relay station is newly installed, the frequency of the transmitting station or the receiving station is changed, so that it has conventionally been necessary to newly install two stations. This relationship is shown in Figure 6.
Shown in.

In FIG. 6, the frequency of the existing intermediate relay station is changed. It is generally difficult to change the frequency of the wireless station corresponding to the terminal station, but not so difficult at the intermediate relay station. The reason is that (1) the terminal station generally has a large number of wireless channels because the lines are concentrated, and the flexibility of the change is low, and (2) the terminal station often branches and the flexibility of the change is low. 3) On the other hand, the intermediate relay station has less of the above problems.

[0006]

As described above, the method of newly installing a plurality of relay stations in order to shorten one relay distance is economically disadvantageous. Therefore, it is necessary to shorten the distance between relay stations in one section by newly installing one relay station without changing the radio frequency of the transmitting station or the receiving station.

In order to solve the above problems, the same frequency relay is effective. This is because the newly installed relay station does not change the frequency of the transmitting station or the receiving station by transmitting the signal received by the low group (or high group) in the low group (or high group), The transmission distance of the required section can be shortened simply by installing a new. This relationship is shown in FIG.

In this case, since the transmission frequency and the reception frequency in the intermediate station are the same, interference occurs between the transmission signal of the same signal and the reception signal in the relay station. This is called interference between transmission and reception. This relationship is shown in FIG.

Further, there is overreach interference which is interference from the transmitting station to the receiving station. Conventionally, this overreach interference occurs at the receiving station three sections ahead, as shown in FIG.
However, when the same frequency relay is applied, it occurs in two sections ahead as shown in FIG. In this case, there is a problem that the distance between the transmitting station of the interference signal and the receiving station of the interfered signal becomes short and the amount of interference becomes large.

It is an object of the present invention to provide a wireless relay system in which the problem of interference does not occur even if the same frequency relay is used.

[0011]

To achieve the above object, the features of the present invention include a transmitting station that modulates an original signal to be transmitted and transmits the transmitting signal at a radio frequency of f hertz, and the transmitting signal. At least one relay station that relays a transmission signal by receiving and relaying at a radio frequency of approximately f hertz, and a reception station that receives a signal transmitted from the relay station and demodulates it to reproduce an original signal. In the frequency radio communication system, the same frequency radio that controls the transmission level of at least one of the transmitting station and the relay station according to the information regarding the reception level of at least one of the relay station and the receiving station or the quality of the reproduced signal. There is a communication method.

Another feature of the present invention is that two transceiver stations respectively transmit and receive at the radio frequency of f1 for the uplink and at the radio frequency of f2 for the downlink, and receive and receive at the radio frequency of f1 for the uplink. In the same frequency wireless communication system having at least one relay station that transmits at a radio frequency of f1 and receives at a radio frequency of f2 for the downlink and transmits at a radio frequency of f2, at least one of the transceiver station and the relay station This is a same frequency wireless communication system that controls the transmission power of the transmitting / receiving station and the relay station based on the information about the reception level of one station or the line quality obtained after demodulation.

[0013]

Since the interference in the same frequency wireless communication system is the interference from the signal of the own route, the control signal in the own route processes the information about the received signal of each station or the quality of the received signal, and the interference is based on the result. It is effective to apply transmission power control to reduce D / U by lowering the transmission output of a transmitter that transmits a signal that becomes a wave or by increasing the transmission output of a transmitter that transmits a signal that becomes an interfered wave. .

In the first aspect of the invention, either the up line or the down line is closed to control the line. For example, if the desired signal transmitted from the relay station at the receiving station reaches the receiving station directly from the transmitting station due to some reason such as rainfall, and the channel quality deteriorates due to overreach interference, the transmitting power of the relay station is reduced. By increasing the number, the D / U can be improved. Further, when the signal transmitted by the transmitting station is received by the relay station with sufficiently high reception power, the D / U relating to overreach interference at the receiving station can be improved by lowering the transmission power of the transmitting station. it can.

The second invention is a method of controlling the transmission power by combining the reception power or the channel quality information of the uplink and the downlink. For example, an uplink signal transmitted by the first transceiver station and received by the relay station and a downlink signal transmitted by the relay station and received by the first transceiver station are propagated on the same propagation path, so that rainfall etc. Then, when the reception power of one of the above two reception signals decreases, the reception power of the other one also decreases due to the same rainfall. By utilizing this, the same effect as that of the first invention is realized by a simpler method. For example, if the reception power of the desired signal transmitted from the relay station at the receiving station decreases and the transmission station directly reaches the receiving station and the line quality deteriorates due to overreach interference, the transmission power of the relay station can be increased. Although the D / U can be improved, in order to realize this, in the first invention, a decrease in the reception power of the transmitting station is detected, and this information is transferred to the relay station by a control signal to increase the transmission level of the relay station. However, in the second invention, control can be performed in the relay station if the transmission output is increased by detecting a decrease in the received signal of the signal propagated in the same section among the signals received by the relay station. The transmission of control signals becomes unnecessary.

[0016]

1 and 2 show an embodiment of the first invention.
Reference numeral 10 is a transmitting station, 20 is a receiving station, and 30 is a relay station.

FIG. 1 shows an example of compensating for overreach interference at the receiving station 20. When the reception power of the desired signal 2 at the receiving station 20 decreases, the line is deteriorated due to overreach interference. Therefore, the receiving station 20
If the received power at the receiving station 20 is reduced, or if the received power at the receiving station 20 is reduced and the received power of the signal 1 of the relay station 30 is not reduced, the transmission output of the transmitting station 10 is reduced, or the relay station is reduced. Increase the transmit power of 30.

FIG. 2 is for compensating for transmission / reception wraparound interference at the relay station. When the reception power of the signal 1 transmitted from the transmission station in the relay station 30 is reduced, the line quality is deteriorated by the transmission / reception interference. Therefore, when the reception power of the signal 1 in the relay station 30 is reduced, or when the reception power of the relay station 30 is reduced and the reception power of the signal 2 in the reception station 20 is not reduced, the transmission of the transmission station 10 is performed. The power is increased or the transmission power of the relay station 30 is decreased.

FIGS. 3 and 4 show an embodiment of the second invention. Reference numeral 40 indicates a transceiver station.

FIG. 3 compensates for signal 12 being degraded by overreach interference. The relay station 30 increases the transmission power of the signal 12 when the reception power of the signal 22 decreases, or the first transmission / reception station 40 outputs the signal 2
The transmission power of the signal 11 is reduced when the reception power of 1 is not reduced.

FIG. 4 compensates for the deterioration of the signal 11 due to the transmission / reception interference. The transmission power of the signal 11 is increased when the reception power of the signal 21 is reduced in the first transceiver station, or the transmission power of the signal 12 is reduced when the reception power of the signal 22 is not reduced in the relay station.

It is also possible to combine these methods.

[0023]

As described above, the use of the present invention makes it possible to compensate for overreach interference or transmission / reception wraparound interference, and to realize the same frequency relay. Therefore, it is possible to realize a transmission path having a short section distance by using a small number of new relay stations in the existing transmission path. Therefore, it is possible to economically realize high quality and large capacity of the conventional transmission line.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 shows an embodiment of the present invention.

FIG. 3 illustrates another embodiment of the present invention.

FIG. 4 illustrates another embodiment of the present invention.

FIG. 5 shows a conventional configuration example.

FIG. 6 shows a conventional configuration example.

FIG. 7 shows a conventional configuration example.

FIG. 8 shows a conventional configuration example.

FIG. 9 shows a conventional configuration example.

FIG. 10 shows a conventional configuration example.

[Explanation of symbols]

 10 transmitting station 20 receiving station 30 relay station 40 transmitting / receiving station f, f1, f2 frequency signal

Claims (2)

[Claims] 1. A transmission station that modulates an original signal to be transmitted and transmits a transmission signal at a radio frequency of f hertz, and a transmission signal that receives the transmission signal and relays it at a radio frequency of approximately f hertz to relay the transmission signal. In the same frequency wireless communication system having at least one relay station that performs the above-mentioned operation and a receiving station that receives the signal transmitted from the relay station and demodulates the original signal, at least one of the relay station and the receiving station The same frequency wireless communication system characterized by controlling the transmission level of at least one of the transmitting station and the relay station according to the information on the reception level or the quality of the reproduced signal to compensate for the interference. 2. A first original signal is modulated to transmit a first transmission signal at a radio frequency of f1 hertz, and a second transmission signal transmitted from a relay station at a radio frequency of approximately f2 hertz is received and demodulated. And a first transmitting / receiving station that reproduces a second original signal, and a second transmitting signal that modulates the second original signal and transmits a second transmitting signal at a radio frequency of f2 Hertz and from a relay station at a radio frequency of approximately f1 Hertz. A second transmitting / receiving station that receives the first transmitted signal and demodulates it to reproduce the first original signal; and a radio frequency of approximately f1 hertz that receives the first transmitting signal and the second transmitting signal. And at least one relay station that relays the first transmission signal and the second transmission signal by relaying the second transmission signal at a radio frequency of approximately f2 Hertz. For same frequency wireless communication system And at least one of the first transceiver station and the second transceiver station according to the information regarding the reception level of at least one of the first transceiver station, the second transceiver station and the relay station or the quality of the reproduced signal. A same frequency wireless communication system characterized by controlling the transmission level of one station to compensate for interference.