WO2004021606A1

WO2004021606A1 - Repeater extension unit

Info

Publication number: WO2004021606A1
Application number: PCT/KR2003/001769
Authority: WO
Inventors: Hyung-Sup Shin; Hyung-Sik Cho; Han-Sin Cho
Original assignee: Ktfreetel Co., Ltd.
Priority date: 2002-08-30
Filing date: 2003-08-30
Publication date: 2004-03-11
Also published as: KR100495356B1; KR20040020285A; AU2003256129A1

Abstract

The present invention relates to a repeater extension unit. The repeater extension unit that is connected between BTS and repeater can provide a diversity function to both BTS and repeater. According to the preferred embodiment of the present invention, there is provided the repeater extension unit comprising the first to third DC coupling part, the first to second port, and the first to third REP coupling part.

Description

REPEATEREXTENSIONUNIT

Field of the invention

The present invention relates to a repeater extension unit of mobile communication

system. More particularly, the_. present invention relates to a repeater extension unit, which

is connected between at least one Base Transceiver Station (hereinafter referred as to

'BTS') and at least one repeater, for providing a diversity function to both BTS and

repeater.

Background of the invention

Currently, PICO BTS remote unit(PICO Base Transceiver Station remote unit,

hereinafter referred as to 'PRU'), which is cheap and compact-sized, has been widely used

for covering low capacity region where does not need the capacity of standard BTS. PRU

has a disadvantage for limited capacity while it has some advantages such as low price and

compact size. However it is possible to establish very effective cell plan if the PRUs are

arranged on proper places. 1 to 3 PRUs according to the number of Frequency

Allocation(hereinafter referred as 'FA') are installed at the same place with different

directions and PRUs provide a diversity function according to the connection between each

PRU.

Additionally, by using a repeater comprising master and slave, downward RF signal of BTS is radiated by PRU through transmission from master to slave and upward

RF signal received by PRU is sent to BTS through transmission from slave to master, so

that the call quality in shadowed area is improved. The RF signals of BTS can be extracted

by a directional coupler, which is coupled to the antenna of BTS, as well as input/output

terminals of BTS. The repeater can also provide a diversity function.

However, problems may arise with loss of the diversity function of PRU or

repeater sometimes. FIG. la and lb show the preferred connection between PRUs for

providing the diversity function when the repeater is not connected to each PRU, and FIG.

2a and 2b show the wrong connection between two PRUs that cannot provide the diversity

function.

FIG. la shows the preferred connection between two PRUs. DUP(Duplexer)

terminal of FA1 PRU is connected to DIN(Diversity) terminal of FA2 PRU, and DIN

terminal of FA1 PRU is connected to DUP terminal of FA2 PRU, respectively. Tx signal of

FA1 PRU is outputted from a duplexer 10 to an antenna, and Tx signal of FA2 PRU is

outputted from a duplexer 20 to the antenna. Input terminals of Rxl 11, 21 are not

connected and 2-contact switches 13, 23 are automatically switched by PLD. According to

the connections between terminals of each PRU, the diversity function of FA2 PRU is

provided from 2:1 divider 12 of FA2 PRU and the diversity function of FA1 PRU is

provided from 2:1 divider 22 of FA1 PRU.

FIG. lb shows the preferred connection between three PRUs. DUP terminal and DIN terminal of FAl PRU are connected to DIN terminal of FA2 PRU and DUP terminal

of FA3 PRU, respectively. DUP terminal of FA2 PRU is connected to DIN terminal of

FA3 PRU. Thus, the diversity function of FAl PRU, FA2 PRU and FA3 PRU are provided

from FA3 PRU, FAl PRU and FA2 PRU, respectively.

Referring to FIG. 2a, since Rxl terminals 11, 21 are connected to Rxl terminal of

a repeater 30, the diversity function of the repeater is lost. The repeater in FIG. 2b is a

Tx/RxO integrated type repeater. Namely, although Rxl terminals 11, 21 are connected to

Rxl terminal of the repeater 30, because two-contact switches 13, 23 are off(that is,

connected to DIN terminal) due to the connection between FAl PRU and FA2 PRU, Rxl

signal of repeater is not inputted to FAl PRU and FA2 PRU. Thus, the diversity function

of the repeater is not performed.

The opposite case that FAl PRU and FA2 PRU are not connected to each other

shown in FIG. la for the repeater to perform the diversity function is shown in FIG. 2b. In

this situation, the diversity function of FAl PRU and FA2 PRU becomes weak. Namely,

since DUP terminals that output the divided signal of 2:1 dividers 13, 23 are connected to

the isolated 2:1 dividers 34, 35, the diversity function of FAl PRU and FA2 PRU becomes

weak or lost. The connections occurring loss of the diversity function of PRU or repeater

shown in FIG. 2a and 2b also happen when the number of PRUs is three.

The aforementioned loss of diversity can be solved by the preferred connections

between equipments. But the connections for maintaining the diversity function of PRU and repeater are very complicate and there are numerous combinations of connections

according to the number of PRU and the type of repeater. Thus, it is actually impossible for

an engineer to establish several tens of connections individually suitable to each situation

and maintain the established connection.

Summery of the invention

Accordingly, to solve aforementioned problems, it is the primary object of the

present invention to provide a repeater extension unit, which is connected between PRU

and repeater, for providing a diversity function to both PRU and repeater regardless of the

number of PRU and the type of repeater.

Another object of the present invention is to provide a repeater extension unit for

connecting at least one PRU to eight repeaters regardless of the number of PRU and the

type of repeater if PRU and repeater are connected to each other according to the

predetermined simple instructions.

To achieve aforementioned objects, according to the preferred embodiment of the

present invention, there is provided a repeater extension unit, being connected between

BTS comprising at least one PRU and n repeaters, for providing the diversity function to

both BTS and repeater, comprising: a first DC coupling part for attenuating a forward

direction Tx signal inputted from a first PRU and a reverse direction Rx signal to be

applied to the first PRU; a second DC coupling part for attenuating a forward direction Tx signal inputted from a second PRU and a reverse direction Rx signal to be applied to the

second PRU; a third DC coupling part for outputting a forward direction Tx signal inputted

from a third PRU, and one of applied reverse direction Rx signals to the third PRU; a first

REP coupling part for dividing the forward direction Tx signal inputted from one of the

first DC coupling part, the second DC coupling part and the third DC coupling part, and

applying the divided Tx signals to at least one repeater; a second REP coupling part for

attenuating and dividing the reverse direction Rx signal inputted from one of n repeaters,

and applying the divided Rx signals to the second DC coupling part and the third DC

coupling part; and a third REP coupling part for attenuating and dividing the reverse

direction Rx signal inputted from one of n repeaters, and applying the divided Rx signals to

the first DC coupling part and the second DC coupling part.

According to another preferred embodiment of the present invention, there is

provided a repeater extension unit, being connected between BTS comprising m PRUs and

n repeaters, for providing diversity function to both BTS and repeater, comprising: a first

m:l divider, being coupled to m directional couplers that are mounted on each antenna of

the m PRUs, for receiving Tx signal from one of the m directional couplers; a first l:n

divider for dividing the Tx signal and applying the divided Tx signals to the n repeaters; a

second l:n divider for receiving Rx signal from one of the n repeaters; a second m:l

divider for dividing the Rx signal outputted from the second l:n divider and applying the

divided Rx signals to the m directional couplers; a third l:n divider for receiving Rx signal from one of the n repeaters; and a third m:l divider for dividing the Rx signal outputted

from the third l:n divider and applying the divided Rx signals to m directional couplers

that are mounted on each DIN terminal of the m PRUs.

Brief description of the drawings

FIG. la and lb show the preferred connection between PRUs for providing a

diversity function when the repeater is not connected to each PRU.

FIG. 2a and 2b show the wrong connection between two PRUs that cannot provide

a diversity function.

FIG. 3 is a schematic of the repeater extension unit according to the preferred

embodiment of the present invention.

FIG. 4 shows the structure of the repeater extension unit in FIG. 3.

FIG. 5 shows a schematic of the repeater extension unit according to another

preferred embodiment of the present invention and the connection to PRUs.

FIG. 6 illustrates an example of using the repeater extension unit according to the

preferred embodiment of the present invention.

Embodiment

Hereinafter, the preferred embodiment of the present invention will be described

with accompanying drawings. But, since the description with embodiment is only for helping those who skilled in the art to understand the present invention, the scope and

spirits of the present invention are not limited to the description and the drawings.

FIG. 3 is a schematic of the repeater extension unit according to the preferred

embodiment of the present invention, and FIG. 4 shows the structure of the repeater

extension unit in FIG. 3. The repeater extension unit comprises the first DC(Directional

coupler) coupling part 100, the second DC coupling part 110, the third DC coupling part

120, the first REP(repeater) coupling part 130, the second REP coupling part 140 and the

third REP coupling part 150.

The first to third DC coupling parts 100, 110, 120 receive Tx signals from

directional couplers that are mounted on an antenna of PRU or provide RxO signal/Rxl

signal(hereinafter 'Rx signal') to the directional couplers. The directional coupler that is

coupled to the nth DC coupling part will be noted as the nth directional coupler. And PRUs

must be connected to each other in the same manner of FIG. la or lb for the diversity

function. FIG. 4 shows three PRUs connected to the repeater extension unit as an example.

However, one or two PRU also can be connected to the repeater extension unit. A divider

that is shown in drawings and has n terminals on left side and m terminals on right side

will be noted as n:m divider in the present invention. Further, since n terminals of l:n

divider or n:l divider are isolated from each other, a signal inputted to one terminal of n

terminals is not outputted to other terminals in the same side.

The first DC coupling part 100 is provided with a DC terminal, a terminal for connecting the first REP coupling part and a terminal for connecting the third REP

coupling part, and through these terminals, the first DC coupling part 100 is connected to

the first directional coupler, the first REP coupling part 130 and the third REP coupling

part 150, respectively. The first DC coupling part 100 comprises an attenuator 102 and a

1:2 divider 104 that is serially connected to the attenuator 102. The attenuator 102

attenuates Tx signal inputted from the first directional coupler by 3dB and provides the

attenuated Tx signal to the 1:2 divider 104. The attenuator 102, further, attenuates Rx

signal inputted from the 1:2 divider 104 by 3dB and provides the attenuated Rx signal to

the first directional coupler.

The second DC coupling part 110 is provided with a DC terminal, a terminal for

connecting the first REP coupling part and a terminal for connecting the second REP

coupling part, and through these terminals, the second DC coupling part 110 is connected

to the second directional coupler, the first REP coupling part 130 and the second REP

coupling part 140, respectively. The second DC coupling part 110 comprises an attenuator

112 and a 1:2 divider 114 that is serially connected to the attenuator 112. The attenuator

112 attenuates Tx signal inputted from the second directional coupler by 3dB and provides

the attenuated Tx signal to the 1:2 divider 114. The attenuator 112 further attenuates Rx

signal inputted from the 1:2 divider 114 by 3dB and provides the attenuated Rx signal to

the second directional coupler.

The third DC coupling part 120, an 1:3 divider, is provided with a DC terminal, a terminal for connecting the first port, a terminal for connecting the second port and a

terminal for connecting the third REP coupling part, and through these terminals, the third

DC coupling part 120 is connected to the third directional coupler, the first port 160, the

second port 170 and the third REP coupling part 150, respectively. The third DC coupling

part 120 provides Tx signal inputted from the third directional coupler to the first port, and

the Tx signal is sent to the first REP coupling part 130 through the first port 160. And, the

third DC coupling part 120 provides Rx signals inputted from the second port 170 and the

third REP coupling part 150 to the third directional coupler.

The first port 160 is provided with a terminal for connecting the first REP coupling

part and a terminal for connecting the third DC coupling part, and is connected between the

third DC coupling part 120 and the first REP coupling part 130. Through opening or

closing two terminals of the first port 160, the third DC coupling part 120 and the first REP

coupling part 130 can be connected to or disconnected from each other.

The second port is provided with a terminal for connecting the second REP

coupling part and a terminal for connecting the third DC coupling part, and is connected

between the third DC coupling part 120 and the second REP coupling part 140. Through

opening or closing two terminals of the second port 170, the third DC coupling part 120

and the second REP coupling part 140 can be connected to or disconnected from each

other.

The first REP coupling part 130 is provided with a terminal for connecting the first DC coupling part, a terminal for connecting the second DC coupling part, a terminal for

connecting the first port and n terminals for connecting n repeaters, and through these

terminals, the first REP coupling part 130 is connected to the first DC coupling part 100,

the second DC coupling part 110, the third DC coupling part 120 and n repeaters

respectively. The first REP coupling part 130 comprises a 3:1 divider 132 for receiving Tx

signal from one of the first DC coupling part 100, the second DC coupling part 100 and the

third DC coupling part 120, and an l:n divider 134 for dividing Tx signal inputted from the

3:1 divider 132 and applying the divided Tx signals to n repeaters. If the repeaters

connected to the repeater extension unit are Tx/RxO integrated type repeater, then the l:n

divider 134 receives Rx signals from one of n repeaters, and the 3:1 divider 132 divides Rx

signals inputted from the l:n divider 134 and provides the divided Rx signals to the first

through third DC coupling part 100, 110, 120.

The second REP coupling part 140 is provided with a terminal for connecting the

second DC coupling part, a terminal for connecting the second port and n terminals for

connecting n repeaters, and through these terminals, the second REP coupling part 140 is

connected to the second DC coupling part 110, the third DC coupling part 120 and n

repeaters respectively. The second REP coupling part 140 comprises an l:n divider 146 for

receiving Rx signals from one of n repeaters, an attenuator 144 for attenuating the Rx

signal inputted from the 1:8 divider 146 by 3dB, and a 2:1 divider 142 for dividing the

attenuated Rx signal inputted from the attenuator and applying the divided Rx signals to the second DC coupling part 110 and the third DC coupling part 120.

The third REP coupling part 150 is provided with a terminal for connecting the

first DC coupling part, a terminal for connecting the third DC coupling part and n terminals

for connecting n repeaters, and through these terminals, the third REP coupling part 150 is

connected to the first DC coupling part 100, the third DC coupling part 120 and n repeaters

respectively. The third REP coupling part 150 comprises an l:n divider 156 for receiving

Rx signals from one of n repeaters, an attenuator 154 for attenuating the Rx signal inputted

from the 1:8 divider 156 by 3dB, and a 2:1 divider 152 for dividing the attenuated Rx

signal inputted from the attenuator and applying the divided Rx signals to the first DC

coupling part 100 and the third DC coupling part 120.

The operation of the repeater extension unit with three PRUs connected thereto

will be described hereinafter. For the convenience of describing the present invention, Rx

signal is distinguished as RxO signal and Rxl signal. The operation of repeater extension

unit coupled to a Tx/Rx separated type repeater will be described and the operation of

repeater extension unit coupled to a Tx/Rx integrated type repeater will be further

described.

Tx terminal, RxO terminal and Rxl terminal of the Tx/Rx separated type repeater

are electrically connected to the first, second, and third REP coupling part 130, 140, 150

respectively. Here, Maximum eight repeaters may be connected to the repeater extension

unit. Forward direction Tx signal inputted from the first to third PRU is applied to the

first REP coupling part 130 by the first to third DC coupling part 100, 110, 120. The Tx

signal is divided by the first REP coupling part 130 and the divided Tx signals are applied

to Tx terminals of the first to eighth repeater.

Reverse direction RxO and Rxl signals inputted respectively from RxO and Rxl

terminals of the first to eighth repeater are applied to the second REP coupling part 140

and the third REP coupling part 150. The second REP coupling part 140 attenuates the RxO

signal by 3dB, divides the attenuated RxO signal and provides the divided RxO signal to the

second DC coupling part 110 and the third DC coupling part 120. The third REP coupling

part 150 attenuates the Rxl signal by 3dB, divides the attenuated Rxl signal and provides

the divided Rxl signal to the first DC coupling part 100 and the third DC coupling part 120.

Thus, the first DC coupling part 100 directly outputs the reverse direction Rxl signal to the

first PRU 40, the second DC coupling part 110 directly outputs the reverse RxO signal to

the second PRU 42, and the third DC coupling part 120 directly outputs the reverse RxO

signal and Rxl signal to the third PRU 44. Also, since the first to third PRU 40, 42, 44 are

preferably connected as shown in FIG lb, each PRU can receive feedback Rx signal from

other PRUs.

Tx/RxO terminal and Rxl terminal of the Tx/RxO integrated type repeater are

electrically connected to the first REP coupling part 130 and the third REP coupling part

150 respectively. Here, Maximum eight repeaters may be connected to the repeater extension unit.

Forward direction Tx signals inputted from the first to third PRU 40, 42, 44 are

applied to the first REP coupling part 130 by the first through third DC coupling part 100,

110, 120. The applied Tx signal is divided by the first REP coupling part 130 and the

divided Rx signals are applied to Tx/RxO terminals of the first to eighth repeater.

Reverse direction RxO signal and Rxl signal outputted from the Tx/RxO terminals

of the first to eighth repeater are applied to the first REP coupling part 130 and the third

REP coupling part 150. The first REP coupling part 130 divides the RxO signal and applies

the divided RxO signals to the first to third DC coupling part 100, 110, 120. And the third

REP coupling part 150 attenuates the Rxl signal by 3dB, divides the attenuated Rxl signal

and applies the divided Rxl signals to the first DC coupling part 100 and the third DC

coupling part 120. Thus, the first DC coupling part 100 directly outputs the RxO signal and

Rxl signal to the first PRU 40, the second DC coupling part 110 directly outputs the RxO

signal to the second PRU 42 and the third DC coupling part 120 directly outputs the RxO

signal and Rxl signal to the third PRU 44. Also, since the first through third PRU 40, 42,

44 are preferably connected as shown in FIG lb, each PRU can receive feedback Rx signal

from other PRUs.

The connection method according to the number of PRU and Rx signals inputted

to each PRU according to the number of PRU and type of repeater will be described with

the following table. Table

When the number of PRU is one, the directional coupler connected between

duplexer and Tx/RxO antenna is connected to the second DC coupling part 110, and the

directional coupler connected between Rx receiver and Rx antenna is connected to the

third DC coupling part 120. And, the first port 160 and the second port 170 are opened

respectively. The direct Rx signal in the case of one PRU is outputted from the second DC

coupling part 110, and the feedback Rx signal in the case of one PRU is outputted from the

Rxl receiver.

When the number of PRU is two, the directional coupler connected between the

duplexer and Tx/RxO antenna of the first PRU is connected to the second DC coupling part

110, and the directional coupler connected between the duplexer and Tx/RxO antenna of

the second PRU is connected to the third DC coupling part 120. And the first port 160 and

the second port 170 are closed to connect the third DC coupling part to the first REP

coupling part 130 and the second REP coupling part 140. The direct Rx signal in the case of two PRUs is outputted from the second DC coupling part 110 and the third DC coupling

part 120, and the feedback Rx signal of the first PRU is the direct Rx signal of the second

PRU and the feedback Rx signal of the second PRU is the direct Rx signal of the first PRU.

When the number of PRU is three, the directional coupler connected between the

duplexer and Tx/RxO antenna of the first PRU is connected to the first DC coupling part

100, the directional coupler connected between the duplexer and Tx/RxO antenna of the

second PRU is connected to the second DC coupling part 110, and the directional coupler

connected between the duplexer and Tx/RxO antenna of the third PRU is connected to the

third DC coupling part 120. And the first port 160 and the second port 170 are closed to

connect the third DC coupling part to the first REP coupling part 130 and the second REP

coupling part 140. The direct Rx signal in the case of three PRUs is outputted from the first

through third DC coupling part 100, 110, 120, and the feedback Rx signal of the first PRU

is the direct Rx signal of the third PRU, the feedback Rx signal of the second PRU is the

direct Rx signal of the first PRU, and the feedback Rx signal of the third PRU is the direct

Rx signal of the second PRU.

FIG. 5 shows a schematic of the repeater extension unit according to another

preferred embodiment of the present invention and the connection to PRUs. For the

convenience of description, we will describe the present invention with a repeater

extension unit coupled to three PRUs and eight repeaters. Three PRUs 40, 42, 44 are connected to each other in the same manner of FIG. lb,

and comprise directional couplers 50, 52, 54, 60, 62, 64 that are coupled to Tx/RxO antenna

and DIN terminal thereof. If there are two PRUs, PRUs will be connected to each other in

the same manner of FIG. la.

The repeater extension unit according to another embodiment of the present

invention comprises a 3:1 divider 200, which is connected to the directional couplers

mounted on Tx/RxO antennas of three PRUs and receives Tx signals from at least one of

directional couplers, an 1:8 divider 210, which divides Tx signal inputted from the 3:1

divider and applies the divided signals to eight repeaters, an 1:8 divider 212 for receiving

Rx signal from one of eight repeaters, a 3:1 divider 202, which divides the Rx signal

inputted from 1:8 divider 212 and provides the divided Rx signals to the directional

couplers mounted on Tx/RxO antennas of three PRUs, an 1:8 divider 214 for receiving Rx

signal from one of eight repeaters, and a 3:1 divider 204, which divides the Rx signal

inputted from 1:8 divider 214 and provides the divided Rx signals to the directional

couplers mounted on Tx/RxO antennas of three PRUs. Hereinafter, the operation of the

above-mentioned repeater extension unit will be described.

At least one Tx signal extracted by the directional couplers 50, 52, 54 mounted on

Tx/RxO antennas of three PRU 40, 42, 44 is inputted to the 1:8 divider 210 through 3:1

divider 200, and divided into 8 forward direction Tx signals to be provided to Tx terminals

of each repeaters. Here, if the repeater is Tx/RxO integrated type, RxO signal inputted from one of eight repeaters is inputted to the 3:1 divider 200 through 1:8 divider 210, and

divided into 3 reverse direction RxO signals to be inputted to the directional couplers 50, 52,

54.

Reverse direction RxO signal and Rxl signal that are inputted to the 1:8 dividers

212, 214 are divided into three RxO signals and three Rxl signals. The divided RxO

signals are inputted to the directional couplers 50, 52, 54 and the divided Rxl signals are

inputted to the directional couplers 60, 62, 64.

preferred embodiment of the present invention.

Four terminal pairs, each one of a terminal pair is provided with the other three

terminals, are arranged at the lower part of the repeater extension unit. The leftmost

terminal pair is for connecting PRU, and maximum three PRUs can be connected to the

repeater extension unit. The rest of terminal pairs except the leftmost terminal pair are for

connecting repeaters, and one terminal pair corresponds to one repeater. Tx, RxO, Rxl

terminals are orderly arranged in the terminal pair, and all terminal pairs have same

terminal arrangement. Thus, through connecting PRUs to the leftmost terminal pair,

closing or opening the first port and the second port according to the number of PRU, and

connecting repeaters orderly to Tx, RxO, Rxl terminals of the terminal pairs, both PRU and

repeaters can provide a diversity function. Although the repeater extension unit that can provide the diversity function to both

PRU and repeaters has been described with the preferred embodiment, the spirit and the

scope of the present invention will be determined only by the following claims. Also, it

will be apparent for those skilled in the art that modifications or amendments to the

aforementioned embodiment within the spirit and the scope of the present invention are

possible without departing from the boundary of the claimed invention.

Industrial applicability

As described above, according to the present invention, the diversity function of

the PRU and repeater can be maintained regardless of the number of PRU and the type of

repeater. Accordingly, the operator can connect maximum eight repeaters to one PRU by

using the repeater extension unit easily regardless of the type of repeater.

Claims

1. A repeater extension unit, being connected between BTS comprising at least one PRU

and n repeaters, for providing the diversity function to both BTS and repeater, comprising:

a first DC coupling part for attenuating a forward direction Tx signal inputted from

a first PRU and a reverse direction Rx signal to be applied to the first PRU;

a second DC coupling part for attenuating a forward direction Tx signal inputted

from a second PRU and a reverse direction Rx signal to be applied to the second PRU;

a third DC coupling part for outputting a forward direction Tx signal inputted from

a third PRU, and one of applied reverse direction Rx signals to the third PRU;

a first REP coupling part for dividing the forward direction Tx signal inputted

from one of the first DC coupling part, the second DC coupling part and the third DC

coupling part, and applying the divided Tx signals to at least one repeater;

a second REP coupling part for attenuating and dividing the reverse direction Rx

signal inputted from one of n repeaters, and applying the divided Rx signals to the second

DC coupling part and the third DC coupling part; and

a third REP coupling part for attenuating and dividing the reverse direction Rx

signal inputted from one of n repeaters, and applying the divided Rx signals to the first DC

coupling part and the second DC coupling part.

2. The repeater extension unit as stated in claim 1, wherein said first DC coupling part comprises:

an attenuator for attenuating the forward direction Tx signal inputted from the first

PRU and the reverse direction Rx signal inputted from the third REP coupling part by 3dB;

and

an 1:2 divider for dividing the forward direction Tx signal inputted from the

attenuator and applying the divided Tx signal to the first REP coupling part, and applying

the reverse direction Rx signal inputted from one of the first REP coupling part and the

third REP coupling part to the attenuator.

3. The repeater extension unit as stated in claim 1, wherein said second DC coupling part

comprises:

an attenuator for attenuating the forward direction Tx signal inputted from the

second PRU and the reverse direction Rx signal inputted from the second REP coupling

part by 3dB; and

an 1:2 divider coupled to the attenuator for dividing the forward direction Tx

signal inputted from the attenuator and applying the divided Tx signal to the first REP

coupling part, and applying the reverse direction Rx signal inputted from one of the first

REP coupling part and the second REP coupling part to the attenuator.

4. The repeater extension unit as stated in claim 1, wherein said first REP coupling part divides the reverse direction Rx signal inputted from one of n repeaters and provides the

divided Rx signals to the first DC coupling part, the second DC coupling part and the third

DC coupling part.

5. The repeater extension unit as stated in claim 4, wherein said first REP coupling part

comprises:

a 3:1 divider for receiving the forward direction Tx signal inputted from one of

said first DC coupling part, the second DC coupling part and the third DC coupling part,

and dividing the Rx signal and applying the divided Rx signals to the first DC coupling

part, the second DC coupling part and the third DC coupling part; and

an l:n divider for dividing the forward direction Tx signal inputted from the 3:1

divider and applying the divided Tx signals to the n repeaters, and applying the reverse

direction Rx signal inputted from one of the n repeaters to the 3:1 divider.

6. The repeater extension unit as stated in claim 1, wherein said second REP coupling part

comprises:

an l:n divider for applying the reverse direction Rx signal inputted from one of the

n repeaters;

an attenuator for attenuating the reverse direction Rx signal inputted from the l:n

divider by 3dB; and a 2:1 divider for dividing the reverse direction Rx signal inputted from the

attenuator and applying the divided Rx signals to the second DC coupling part and the

third DC coupling part.

7. The repeater extension unit as stated in claim 1, wherein said third REP coupling part

comprises:

n repeaters;

divider by 3dB; and

a 2:1 divider for dividing the reverse direction Rx signal inputted from the

attenuator and applying the divided Rx signals to the first DC coupling part and the third

DC coupling part.

8. The repeater extension unit as stated in claim 1, wherein the number of said repeaters is

eight.

9. The repeater extension unit as stated in claim 1 further comprising:

a first port having two terminals for connecting the third DC coupling part and the

first REP coupling part; and a second port having two terminals for connecting the third DC coupling part and

the second REP coupling part,

wherein the third DC coupling part is disconnected from the first REP coupling

part and the second REP coupling part by opening the first port and the second port when

the number of PRU is one.

10. The repeater extension unit as stated in claim 7, wherein said third DC coupling part is

connected to the first REP coupling part and the second REP coupling part by closing said

terminals of the first port and the second port respectively when the number of PRU is

more than two.

11. A repeater extension unit, being connected between BTS comprising m PRUs and n

repeaters, for providing diversity function to both BTS and repeater, comprising:

a first m:l divider, being coupled to m directional couplers that are mounted on

each antenna of the m PRUs, for receiving Tx signal from one of said m directional

couplers;

a first l:n divider for dividing said Tx signal and applying said divided Tx signals

to the n repeaters;

a second l:n divider for receiving Rx signal from one of the n repeaters;

a second m:l divider for dividing the Rx signal outputted from the second l:n divider and applying the divided Rx signals to the m directional couplers;

a third l:n divider for receiving Rx signal from one of the n repeaters; and

a third m:l divider for dividing the Rx signal outputted from the third l:n divider

and applying the divided Rx signals to m directional couplers that are mounted on each

DIN terminal of the m PRUs.

12. The repeater extension unit as stated in claim 11, wherein said m is selected from one

through three and said n is selected from one to eight.

13. The repeater extension unit as stated in claim 11, wherein said first l:m divider

receives Rx signal from one of the n repeaters and provides the Rx signal to the first m:l

divider, wherein the first m:l divider divides said Rx signal and provides the divided Rx

signals to the m directional couplers.