JP2002185382A - Radio repeater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio repeater by which a radio relay operation is performed in a small dynamic range in such a way that the radio repeater does not perform a gain control operation at each terminal in a radio system in which the terminal controls transmitting power. SOLUTION: In the radio repeater in the radio system, the terminal controls the transmitting power with reference to an up line to a base station via the radio repeater from the terminal. The radio repeater is provided with a means which receives a control signal transmitted by the base station, and which obtains the maximum gain of the system from the transmitting power of the base station contained in the control signal and from the desired transmitting power of the base station; a means which receives a signal in a down line to the terminal via the radio repeater from the base station so as to be amplified to prescribed transmitting power; a means which automatically controls the gain of the means amplifying the down line according to the received power of the down line, and which uses the gain as a down-line gain; a means which receives the signal of the up line so as to be amplified up to the prescribed transmitting power; and a means which selects a smaller one from among the maximum gain and the down-line gain as the gain of the means amplifying the up line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio repeater, and more particularly to gain control of an amplifier.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the configuration of a conventional radio repeater. In this example, a wireless system that performs two-way communication on the uplink and downlink using a time division duplex (TDD) method is shown. In the downlink, the radio repeater 100 receives the signal transmitted from the base station 1 by the antenna 3 and inputs the signal to the variable gain amplifier 5 in the downlink by the switching circuit 4. After the variable gain amplifier 5 amplifies the input signal to a predetermined level, the signal is transmitted to the terminal 2 via the switching circuit 8 and the antenna 9. At this time, the received power varies depending on the distance between the base station and the repeater and is not constant. An automatic gain control circuit (AGC) 7 controls the gain of the variable gain amplifier 5 in order to amplify to a predetermined transmission power according to the received power.

Next, in the up line, the switching circuits 4 and 8 are connected to a-
Switch from b connection to ac connection. The radio repeater 100 receives the signal transmitted from the terminal 2 by the antenna 9 and inputs the signal to the variable gain amplifier 10 in the uplink by the switching circuit 8. After the variable gain amplifier 10 amplifies the input signal to a predetermined level, the signal is transmitted to the base station 1 by the antenna 3 through the switching circuit 4. At this time, the received power differs for each terminal depending on the distance between the terminal and the repeater, and the AGC 12 controls the gain of the variable gain amplifier 10 for each terminal. This circuit is disclosed in Japanese Patent Application Laid-Open No. Hei 10-22895 "Wireless Relay Amplifier".

[0004] Normally, a low-noise amplifier is connected to the receiving side and a high-output amplifier is connected to the transmitting side depending on the input and output power levels, but they are omitted in this figure. In some cases, the wireless repeater performs frequency conversion, but this is omitted in this example.

FIG. 5 shows a configuration example of transmission power control performed by a terminal. This shows an example based on the specifications of the ETSI BRAN 5 GHz band high-speed wireless access system HIPERLAN2. First, the terminal transmits a broadcast signal (BC) transmitted by the base station.
H) is received. This broadcast signal includes the transmission power of the base station (A
P_Tx_Level) and the received power of the uplink desired by the base station (A
P_Rx_UL_Level). The terminal inputs these pieces of information obtained by demodulating the broadcast signal to the transmission power control circuit 18. Next, the terminal receives the downlink received power RSS.
I is detected by the detector 19 and input to the transmission power control circuit 18. The transmission power control circuit 18 determines the transmission power P of the terminal.
t and mt are determined by the following equation (1). Pt, mt = min (AP_Tx_Level-RSSI + AP_Rx_UL_Level, AP_Tx_Level) (1) When the propagation loss between the base station and the terminal is small (RSSI> AP_Rx_
(UL_Level), the terminal suppresses the transmission power to a value equal to or less than AP_Tx_Level. At this time, the received power Pr, ap of the base station is AP_Rx_UL_
Level. When the propagation loss between the base station and the terminal is large (RSSI <AP_Rx_UL_Level), the terminal increases the transmission power to the maximum A
P_Tx_Level, but base station received power is AP_Rx_UL_Lev
no longer reach el. Thus, the terminal performs transmission power control on the uplink, so that the reception power Pr, ap of the base station is AP_
It becomes less than Rx_UL_Level.

[0006]

The above-mentioned radio repeater controls the gain of the amplifier independently for the downlink and the uplink. In the uplink, the gain is controlled for each terminal. For this reason, the dynamic range required by the wireless repeater is very large to cover the assumed perspective difference.

The present invention has been made in view of such circumstances, and in a wireless system in which a terminal performs transmission power control, a wireless repeater performs wireless relay in a small dynamic range without performing gain control for each terminal. The purpose is to:

[0008]

In order to achieve the above object, a feature of the present invention is to provide a radio system in which a terminal performs transmission power control on an uplink from a terminal to a base station via a radio repeater. Means for receiving a control signal transmitted by the base station in the wireless repeater and obtaining the maximum gain of the system from the transmission power of the base station and the desired received power of the base station included in the control signal; Means for receiving a downlink signal to a terminal through the terminal, amplifying the signal to a predetermined transmission power, and automatically controlling the gain of the means for amplifying the downlink according to the received power of the downlink, Means for the downlink gain, means for receiving the signal of the uplink, amplifying to a predetermined transmission power, and the gain of the means for amplifying the uplink, the maximum gain and the downlink gain Choose the smaller one In RF repeater and means that.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment. As shown in FIG. 1, when both of the states of the switching circuits 4 and 8 are ab connection, the line becomes a down line.
Uplink when -c connection is established. In the downlink, as in the conventional example, the radio repeater 100 receives the signal transmitted from the base station 1 by the antenna 3 and amplifies the input signal by the variable gain amplifier 5 to a predetermined level AP_Tx_Level. Send to 1 or 2. At this time, the AGC 7 controls the gain of the variable gain amplifier 5 according to the received power.

Next, the radio repeater 101 receives the broadcast signal (BCH) transmitted from the base station 1 and demodulates the AP_T obtained by demodulation.
Information on x_Level (transmission power of the base station) and AP_Rx_UL_Level (desired reception power of the base station) is input to the uplink gain control circuit 23. Further, the wireless repeater inputs the downlink gain Gd obtained by the AGC 7 to the uplink gain control circuit 23. The uplink gain control circuit 23 determines the uplink gain Gu by the following equation (2). Gu = min (Gd, AP_Tx_Level-AP_Rx_UL_Level) (2) AP_Tx_Level-AP_Rx_UL_Level is the difference between the transmission power of the base station and the desired reception power of the base station, and is the maximum gain of the line assumed by this system, that is, the propagation loss. If the propagation loss between the base station and the wireless repeater is small, Gu becomes Gd,
Conversely, if this propagation loss is large, Gu is the maximum gain AP_Tx_
Level-AP_Rx_UL_Level.

As described above, according to the present invention, the uplink gain is determined by the downlink gain and the maximum gain value of broadcast information, and control is not performed for each terminal regardless of the uplink propagation loss. It is one of the features.

On the other hand, since terminals 1 and 2 perform transmission power control based on a signal transmitted from wireless repeater 101, the received power of the wireless repeater in the uplink is less than AP_Rx_UL_Level. Therefore, the uplink transmission power of the wireless repeater is AP_Tx_Level at maximum.

Thus, the propagation loss between the uplink radio repeater and the terminal is absorbed by the transmission power control of the terminal, and the radio repeater covers only the propagation loss between the base station and the radio repeater. For this, information obtained by downlink gain control can be used.

As described above, in the wireless repeater of the first embodiment, it is not necessary to perform gain control for each terminal in the uplink. Further, since the dynamic range is small, the variable width of the variable gain amplifier 10 can be reduced.

FIG. 2 shows a second embodiment of the present invention. In the wireless repeater 102 of the second embodiment, the hold circuit 24 is connected to the output of the AGC 7 that controls the variable gain amplifier 5 in the downlink.
And holds the value of the control signal of the variable gain amplifier 5 for one frame. The hold circuit 24 uses the output of the AGC 7 one frame before as the control signal for the downlink.

FIG. 3 shows this state. In the figure, (a) is a downlink reception burst signal of a wireless repeater, and (b) is a downlink transmission burst signal when a conventional AGC is used.
(C) shows a downlink transmission burst signal in the case of the second embodiment. In the case (b), when the wireless repeater amplifies the received burst signal, an amplitude variation occurs at the head of the burst signal until the AGC determines the gain. If the wireless repeater directly transmits the signal having the amplitude variation due to the AGC, the receiver of the terminal may not receive the signal properly. However, in (c), amplification is performed using the gain one frame before, the gain during transmission is fixed, and amplitude fluctuation due to AGC does not occur in the transmission signal. The gain of the amplifier determined by the AGC during this frame is updated before the downstream relay of the next frame. As a result, the gain control of the downlink is delayed by one frame. However, since the base station and the wireless repeater do not normally operate in a fixed manner, the level does not fluctuate greatly during the frame length of a general wireless system. It is thought that there is no. Further, the gain may be determined using an average value of the levels of a plurality of past frames instead of the gain before the frame.

[0018]

According to the radio repeater of the first embodiment of the present invention, it is not necessary to perform gain control for each terminal in the uplink, and the dynamic range can be reduced. Also, during the relay, the wireless repeater of the second embodiment
It is possible to prevent the amplitude fluctuation due to C from being added.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a second embodiment of the present invention.

FIG. 3 is a time chart of the present invention.

FIG. 4 is a block diagram of a conventional wireless repeater.

FIG. 5 is a configuration example of transmission power control of a terminal.

[Explanation of symbols]

 Reference Signs List 1 base station 2 terminal 3, 9, 13 antenna 4, 8, 14 switching circuit 5, 10, variable gain amplifier 6, 11 distributor 7, 12 automatic gain amplifier (AGC) 15 amplifier 16 down converter 17 demodulator 18 transmission power control Circuit 19 Detector 20 Modulator 21 Upconverter 22 Variable gain amplifier 23 Up gain control circuit 24 Hold circuit 100, 101, 102 Wireless repeater

Claims (4)

[Claims] 1. A wireless repeater in a wireless system in which a terminal performs transmission power control on an uplink from a terminal to a base station via a wireless repeater, the control signal transmitted by the base station being received. Means for obtaining the maximum gain of the system from the transmission power of the base station and the desired reception power of the base station included in the base station; and receiving a downlink signal from the base station to the terminal via the wireless repeater to obtain a predetermined transmission power. A means for amplifying the downlink signal; a means for automatically controlling the gain of the means for amplifying the downlink signal in accordance with the received power of the downlink signal; A wireless repeater comprising: means for amplifying to a predetermined transmission power; and means for selecting the smaller of the maximum gain and the downlink gain as a gain of the means for amplifying the uplink. . 2. The apparatus according to claim 1, further comprising: means for using downlink gain determined from past frames without using received power of a relayed frame in downlink gain control. A wireless repeater as described. 3. The wireless repeater according to claim 2, wherein the downlink gain is determined from a frame immediately before the frame being relayed. 4. The wireless repeater according to claim 2, wherein the downlink gain is determined from an average value of levels of a plurality of past frames up to the frame being relayed.