WO2008117973A1 - Microwave repeater system for wireless network - Google Patents

Abstract

A microwave repeater system for a wireless network is disclosed. The microwave repeater system includes a donor system having a donor RF unit and a donor M/W unit, a remote system having a remote M/W unit and a remote RF unit, and microwave antennas to convert and restore an IF or RF signal into a microwave band frequency. The microwave repeater system includes a VSWR measuring unit provided in the donor M/W unit or the remote M/W unit and checking coupling of a microwave antenna and operation of an antenna circuit, and a current detecting unit interrupting an electric current flowing in a concentric cable connecting the donor RF unit and the donor M/W unit or the remote M/W unit and the remote RF unit.

Description

MICROWAVE REPEATER SYSTEM FOR WIRELESS NETWORK

Technical Field

The present invention relates to a microwave repeater system for a wireless network, and more particularly to a complex microwave repeater system for a wireless network that enables efficient realization of a microwave repeater system using transmission of microwaves to transmit RF signals for communication through free spaces in a wireless network related to mobile communication such as CDMA, WCDMA, a TRS, and a GSM, a digital TV, a DMB system, a wireless internet such as WiBro and WiMax, an IPTV, and a BCN, and enables effective installation of donor equipment, remote equipment, and antennas between a base station and a service area.

Background Art

Currently, CDMA signals, WCDMA signals, and WiBro signals are being widely used in everyday life. CDMA and WCDMA are signal transmission methods for 2G and 3G mobile communications respectively and WiBro signals may realize a wireless portable internet enabling use of a high speed internet service while a user is moving, so a 2.3 GHz wireless internet service enables a user to freely use the Internet even in a moving vehicle or subway train like a mobile phone.

Such a wireless communication service realizes its service through connection between a base station and a terminal using high frequencies transmitted and received therebetween and finishes the service by transmitting signals from the base station to the terminal via a repeater. Such a repeater re-amplifies and re-transmits a signal of a base station or a signal transmitted from a terminal in order to enable transmission of signals mainly in a partially shadow area or an area to which signals of a base station are not transferred, and is an inevitable equipment enabling a wireless communication service by optimally transmitting repeated signals to a base station. In particular, a microwave repeater may be installed in an area where waves of a base station are blocked by mountains or other topographical obstructions, an area where voice communication is impossible or poor, or an island area where passages for wire networks cannot be easily secured, in order to provide a wireless service of high quality. Therefore, use of microwave repeaters is being gradually expanded due to their low management costs as compared with optical communication repeaters and their avoidance of interference of space waves of RF repeaters covering a terrestrial area. Fig. 1 is a view schematically illustrating a conventional microwave repeater system.

As illustrated in FIG. 1, the microwave (M/W) repeater system includes a donor RF unit 10, a donor M/W unit 20, a remote M/W unit 30, and a remote RF unit 40. The M/W units transmit and receive waves in microwave frequency bands through antennas .

The M/W units basically convert signals currently serviced by a base station 5 into M/W link frequency bands and transmit the converted signals to the remote units, and the remote M/W unit reconverts and re-amplifies the received signals into their original frequencies, enabling expansion of service area. Then, the service area is determined according to the output of a high gain stage of the remote RF unit. Conventionally, however, studies on technologies for microwave repeater systems, such as synchronization between M/W units and RF units, efficient amplitude of outputs, and increase in transmission rates of signals, that are related to their performances have been widely performed, but studies on technologies for operating systems of microwave repeater systems, such as their efficient installation, monitoring of their installation, and supply of power to M/W units, that are related to their installation and maintenance have been relatively poor. Accordingly, there have occurred problems on inconvenient installation and maintenance of microwave relay systems and poor safety against operational power. Therefore, there exist demands on systems enabling effective installation and maintenance of donor units, remote units, and antennas.

Technical Problem

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a microwave repeater system for a wireless network that enables efficient transmission of signals, convenient installation and management of microwave antennas, security of safety for currents generated during installation and management, and easy diagnostication and maintenance.

Technical Solution

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a microwave repeater system includes a donor system having a donor RF unit and a donor M/W unit, a remote system having a remote M/W unit and a remote RF unit, and microwave antennas to convert and restore an IF or RF signal into a microwave band frequency. The microwave repeater system includes a VSWR measuring unit provided in the donor M/W unit or the remote M/W unit and checking coupling of a microwave antenna and operation of an antenna circuit, and a current detecting unit interrupting an electric current flowing in a concentric cable connecting the donor RF unit and the donor M/W unit or the remote M/W unit and the remote RF unit.

Advantageous Effects

A microwave repeater system for a wireless network according to the present invention enables expansion of service area for wireless communication through various installation methods and also enables precise adjustment of microwave antennas using LOS, and thereby easy installation and adjustment of microwave antennas, so as to maximize intensity of signals between a donor M/W unit and a remote M/W unit.

Furthermore, the microwave repeater system for a wireless network according to the present invention enables checking of coupling of M/W antennas and operation of antenna circuits, security of safety for power sources generated during installation and management, and easy diagnostication and maintenance. Description of Drawings

The above and other objects, features and other advantages of the present invention will be more clearly ^■understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a concept view illustrating a conventional microwave repeater system for a wireless network; Fig. 2 is a concept view illustrating a microwave repeater system for a wireless network according to an embodiment of the present invention;

Fig. 3 is a view illustrating a one-to-N multi- connection for the microwave repeater system for a wireless network according to the embodiment of the present invention;

Fig. 4 is a view illustrating a cascade connection for the microwave repeater system for a wireless network according to the embodiment of the present invention;

Fig. 5 is a view illustrating a signal branching unit; Fig. 6 is a block diagram illustrating a VSWR measuring unit for a microwave antenna according to the embodiment of the present invention;

Fig. 7 is a view illustrating a process of calculating an LOS according to the embodiment of the present invention; Fig. 8 is a view illustrating connection between a donor RF unit and a donor M/W unit through a concentric cable according to the embodiment of the present invention; and

Fig. 9 is a block diagram illustrating a current detecting unit provided in the donor RF unit according to the embodiment of the present invention.

Best Mode

Hereinafter, a preferred embodiment of the present invention will be described in detain with reference to the accompanying drawings .

Fig. 2 is a concept view illustrating a microwave repeater system for a wireless network according to an embodiment of the present invention.

The present invention efficiently realizes a microwave repeater system using transmission of microwaves to transmit radio frequency (RF) signals for communication through free spaces in a wireless network related to mobile communication such as code division multiple access (CDMA) , wideband code division multiple access (WCDMA) , a trunked radio system

(TRS) , and a global system for mobile communications (GSM) , a digital TV, a digital multimedia broadcasting (DMB) system, a wireless internet such as a wireless broadband internet (WiBro) and the worldwide interoperability for microwave access (WiMax) , an internet protocol TV (IPTV) , and a broadband convergence network (BCN) . The microwave repeater system according to the embodiment of the present invention includes a donor system having a donor RF unit 100 and a donor M/W unit 200 that receives a frequency signal from a base station 50 and converting the received frequency signal to a microwave signal and a remote system having a remote M/W unit 300 and a remote RF unit 400 that converts the microwave signal output from the donor system, and service antennas include base station service antennas 201 and 202 and a service antenna 301 of the microwave repeater system.

The donor RF unit 100 converts a forward service band signal that is to be transmitted or received to and from the base station 50 or wirelessly to an IF or RF signal and transmits the converted forward signal to a reception terminal of the donor M/W unit 200, and transmits a backward signal input through the donor M/W unit 200 to the base station. The donor M/W unit 200 converts and amplifies the forward signal received from the donor RF unit 100 into a microwave band frequency and transmits the converted and amplified forward signal to a remote micro-antenna through a micro-antenna, and converts the backward signal received from the remote M/W unit 300 to an IF or RF signal and transmits the converted backward signal to the donor RF unit 100.

The remote M/W unit 300 converts the microwave band forward signal transmitted form the donor M/W unit 200 to an IF or RF signal and transmits the converted forward signal to the remote RF unit 400, and the remote RF unit 400 converts and amplifies the IF or RF signal transmitted from the remote M/W unit 300 into a wireless wave frequency, provides a service to subscribers in a shadow area through a service antenna, and transmits the backward signal transmitted from a terminal to the remote M/W unit 300.

The microwave repeater system according to the embodiment of the present invention may include not only a single donor system and a single remote system, but also a combination of a plurality of donor systems and a plurality of remote systems in order to enhance repeater efficiency and transmission range for signals and satisfy various environmental factors.

Fig. 3 is a view illustrating a one-to-N multi- connection for the microwave repeater system according to the embodiment of the present invention, and Fig. 4 is a view illustrating a cascade connection for the microwave repeater system according to the embodiment of the present invention.

An entire microwave repeater communication network is operated by using a cascade connection in which a signal is branched through a branching unit 201' -1 as illustrated in Fig. 5 in the donor M/W unit and the remote M/W unit and is repeated by a repeater and a one-to-N multi-connection in which a signal is transmitted to a plurality of repeaters.

The one-to-N multi-connection includes branching input ports of donor M/W units and output ports of the donor M/W units into N to M/W antennas respectively and transmitting one branched signal to the dependent remote M/W units 303, 306, 307, 308, and 311, the branched M/W antennas 304, 305, 309, and 310, and the remote RF units 401, 402, 403, 404, and 405 through the donor M/W units 202 and 201 and the M/W antennas. As illustrated in Fig. 3, RF signals, communication control signals, and supply power sources that are branched and transmitted form the donor M/W units 202 and 201 and the remote M/W units 303, 306, 307, 308, and 311 are transmitted to and received from N multi-type dependent remote RF units 401, 402, 403, 404, and 405.

The cascade connection includes branching output ports of remote M/W units into N through the branching unit 201' -1 respectively and transmitting one branched signal to the dependent remote RF units 401 and 402 through the M/W antenna 303.

The combination of the multi-connection and the cascade connection enables simultaneous communication of signals without crosses of the signals by setting natural IDs to the units and carries out the two connections together.

Fig. 6 is a block diagram illustrating a VSWR measuring unit for a microwave antenna according to the embodiment of the present invention. The microwave repeater system according to the embodiment of the present invention may include a unit for measuring a voltage standing wave ratio (VSWR) of a microwave antenna in order to check coupling of the microwave antenna and operation of an antenna circuit. The VSWR measuring unit 111 includes a coupler 123 coupling an input current, a power amp detector 124 damping the current, a detector circuit 126 detecting the current, a voltage converting circuit 127 converting a voltage in correspondence to the current, and a VSWR measuring circuit 128 measuring a VSWR in correspondence to the voltage.

More particularly, the VSWR measuring unit 111 may be provided in a terminal amplifier of the donor or remote M/W unit and may measure obtains a voltage passing through the voltage converting circuit 1237 through the detector circuit 126 of an RF output port and measure a VSWR in the VSWR measuring circuit 128. In a normal state, the VSWR measured in the VSWR measuring circuit 128 is equal to or less than 1.5. Accordingly, when the VSWR is more than 1.5, there exist problems in coupling of an antenna and operation of an antenna circuit, in which case a user can easily monitor the state of the antenna by externally attaching a VSWR measuring/warning unit.

Fig. 7 is a view illustrating a process of calculating an LOS used to adjust a microwave antenna of the microwave repeater system for a wireless network according to the embodiment of the present invention.

When a user inputs specific values in edit box items in an LOS-related display window according to an operating program associated with a donor RF unit, the LOS-related display window shows azimuth angles of antennas, a distance between the current donor M/W unit and remote M/W unit, and a path loss therebetween.

That is, after latitudes, longitudes, and heights above the sea where the donor M/W unit and the remote M/W unit are installed, and heights of steel towers of and installation locations of the donor M/W unit and the remote M/W unit that correspond to the user input items are input, azimuth angles and heights of, a distance between, and a path loss between microwave antennas are calculated. The installation time for microwave antennas can be shortened by using data obtained through the LOS calculating process. Moreover, the current situation of antennas can be monitored by the user input items and be used as information for matching of LOSs of subsequent antennas .

As a result, a user can precisely adjust LOSs of microwave antennas to maximize intensities of signals between a donor M/W unit and a remote M/W unit with reference to the calculated LOSs .

Fig. 8 is a view illustrating connection between a donor RF unit and a donor M/W unit through a concentric cable of a microwave repeater system according to the embodiment of the present invention. In the donor system, a donor RF unit 100 and a donor M/W unit 200 are connected to an RF concentric cable 150, and in the remote system, a remote RF unit 300 and a remote M/W unit 400 are connected to an RF concentric cable 150. A DC block is installed at the front end of a connector of a port connected from a donor RF unit and a remote RF unit to M/W units so as to supply DC power, and a DC block is installed at the rear end of a connector connected from a donor M/W unit and a remote M/W unit to RF units so as to supply DC power.

Meanwhile, in order to prevent power failure and damage to units during connection or disconnection of an RF concentric cable connected to M/W units, power is automatically supplied when the RF concentric cable is connected to an input/output port by embedding a current detecting circuit in a power supply unit (PSU) that is a power source for RF units supplying DC power, and power is automatically interrupted when the RF concentric cable is not connected. Accordingly, safety of operators and protection of equipment in a donor M/W unit and a remote M/W unit can be secured when the concentric cable 150 is connected or disconnected.

Hereinafter, automatic interruption and connection of power will be described in detail.

Fig. 9 is a block diagram illustrating a current detecting unit provided in the donor RF unit of the microwave repeater system according to the embodiment of the present invention.

As illustrated in Fig. 9, the current detecting unit includes a condenser 151 receiving and storing an input current, a switch 152 switching the current, a current detecting circuit 153 detecting the current, and a main control unit (MCU) 180 controlling the switch 152 in correspondence to a detection signal of the current detecting circuit 153. In the donor RF unit, after the current detecting unit 160 detects a current of an output port of a DC power source of a DC/DC converter, when there flows no current, a transistor-transistor logic (TTL) signal of high level is applied from the current detecting circuit 153 to the MCU 180. Then, the MCU 180 is programmed to open the switch 152 when the TTL signal of high level is applied. After lapse of a period of time, the switch 152 is closed again to apply a voltage. Then, when there flows no current from the current detecting circuit 153 to the MCU 180, a signal of high level opens the switch 152, but when there flows a current, a signal of low level is maintained to connect the switch 152 and then apply a voltage. Therefore, when the concentric cable is disconnected, the MCU 180 sends a signal of high level and opens the switch 152, or when the concentric cable is connected, the MCU 180 sends a signal of low level and connects the switch 152.

As an alternative, as illustrated in Fig. 9, when the current detecting circuit 153 connected to a Bias Tee 155 that is a DC power output port detects that there flows no current, a TTL signal of high level is applied to the MCU 180. In this case, the MCU 180 also opens a signal of the switch 152. Accordingly, since the switch 152 is not connected, a PSU is not grounded, and since the concentric cable is not connected to the microwave repeater system, a resistance measured by the MCU 180 is the infinity. On the other hand, when the concentric cable is connected, a resistance measured by the MCU 180 is a minimum value and the MCU 180 connects the switch 152 to automatically apply a voltage. Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

Claim 1. A microwave repeater system comprising a donor system having a donor RF unit and a donor M/W unit, a remote system having a remote M/W unit and a remote RF unit, and microwave antennas to transmit communication signals in mobile communication, wireless Internet, and a wireless network, wherein the donor RF unit converts a received forward signal to an IF or RF signal and transmits the converted forward signal, and transmits a backward signal input through the donor M/W unit to a base station, the donor M/W unit converts and amplifies a received forward signal into a microwave band frequency and transmits the converted and amplified forward signal, and converts a backward signal received from the remote M/W unit to an IF or

RF signal and transmits the converted backward signal, the remote M/W unit converts the transmitted microwave band forward signal to an IF or RF signal and transmits the converted forward signal to the remote RF unit, and the remote RF unit converts and amplifies the transmitted IF or RF signal into a wireless wave frequency and transmits the transmitted backward signal to the remote M/W unit, the microwave repeater system comprising: a VSWR measuring unit provided in the donor M/W unit or the remote M/W unit and checking coupling of a microwave antenna and operation of an antenna circuit; and a current detecting unit interrupting an electric current flowing in a concentric cable connecting the donor RF unit and the donor M/W unit or the remote M/W unit and the remote RF unit .

Claim 2. The microwave repeater system as set forth in claim 1, wherein the microwave repeater system uses one of a multi-connection in which an input port of the donor M/W unit is branched into N and one branched signal is transmitted to the dependent remote M/W unit and remote RF unit through the donor M/W unit, a cascade connection in which an output port of the remote M/W unit is branched into N and one branched signal is transmitted to the dependent remote RF unit, and a combination of the multi-connection and the cascade connection.

Claim 3. The microwave repeater system as set forth in claim 1, wherein the microwave repeater system uses one of a multi-connection in which output ports of the donor M/W unit and the remote M/W unit are branched into N respectively and one branched signal is transmitted to the dependent remote M/W unit and remote RF unit through an M/W antenna, a cascade connection in which, an output port of the remote M/W unit is branched into N and one branched signal is transmitted to the dependent remote RF unit through an M/W antenna, and a combination of the multi-connection and the cascade connection.

Claim 4. The microwave repeater system as set forth in claim 1, wherein the VSWR measuring unit comprises: a coupler coupling an input current; a power amp detector damping the current; a detector circuit detecting the current; a voltage converting circuit converting a voltage in correspondence to the current; and a VSWR measuring circuit measuring a VSWR in correspondence to the voltage.

Claim 5. The microwave repeater system as set forth in claim 1, wherein the current detecting unit comprises: a condenser receiving and storing an input current; a switch switching the current; a current detecting circuit detecting the current; and an MCU controlling the switch in correspondence to a detection signal of the current detecting circuit.

Claim 6. The microwave repeater system as set forth in claim 4, wherein the MCU controls the switch in correspondence to a resistance of a connection terminal of a concentric cable.

Claim 7. The microwave repeater system as set forth in claim 1, wherein the microwave antenna is installed by receiving latitudes, longitudes, and heights above the sea where the donor M/W unit and the remote M/W unit are installed, and heights of steel towers of and installation locations of the donor M/W unit and the remote M/W unit, and using data obtained through an LOS calculating process of calculating azimuth angles and heights of, a distance between, and a path loss between the microwave antennas .