WO2005119935A1

WO2005119935A1 - Digital transceiver of mobile communication base station

Info

Publication number: WO2005119935A1
Application number: PCT/KR2004/002301
Authority: WO
Inventors: Don-Shin Lee; Seung-Hyeon Cha; Jong-Hwan Cha; Kwang-Sik Eom
Original assignee: High Gain Antenna Co. Ltd.
Priority date: 2004-06-01
Filing date: 2004-09-09
Publication date: 2005-12-15
Also published as: KR100705574B1; KR20050114311A

Abstract

The present invention relates to a digital transceiver of a base station for cellular system including a master device installed in an indoor part of a building and a slave device installed in an outdoor of the building to reducing power loss and installation cost. The digital transceiver of the base station for cellular system of the present invention comprises: a master device installed in a building to be connected to a telephone exchange, and communicating with a slave device by a digital method; a base station antenna installed at an outdoor part; the slave device installed in the vicinity of the base station antenna, connected to the base station antenna by a coaxial cable, and communicating with the master device by the digital method; and a UTP cable for connecting the master device with the slave device.

Description

DIGITAL TRANSCEIVER OF MOBILE COMMUNICATION BASE STATION

TECHNICAL FIELD The present invention relates to a digital transceiver of a mobile communication base station, and more particularly to a digital transceiver of a mobile communication base station including a master device installed in an indoor part of a building and a slave device installed in an outdoor of the building to reducing power loss and installation cost.

BACKGROUND ART In general, a cellular communication network is composed of a telephone exchange, a base station control system, a base station, and etc. in order to transmit forward signals received from the telephone exchange to subscribers through the base station and transfer backward signals received from the subscribers to the telephone exchange through the base station. In the cellular communication network, a conventional base station system encodes and modulates the forward signals received from the telephone exchange to convert the received forward signals to IF signals or RF signals of small outputs. An RF amplifier amplifies the low-output IF signals or the low-output RF signals. The amplified signals are transmitted to an antenna installed on a roof or on a high steel tower through a coaxial cable. A low noise amplification process for the backward signals received from the subscribers through the antenna is performed. The conventional base station system receives and demodulates the amplified backward signals to convert the backward signals to the IF signals, decodes the IF signals, and transmits the decoded signals to the telephone exchange. Accordingly, the conventional base station system has problems that transmission signals are attenuated as much as 1/10 thereof by the cable loss due to the increase of the length of the coaxial cable for connecting the antenna installed at a steel tower with the base station system installed in the building, and noise increases according to the input loss of the low noise amplifier in a receiving process. In addition, the installation cost for the base station increases proportionally to the increase of the consumption of the coaxial cable.

DISCLOSURE OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a digital transceiver of a mobile communication base station including for reducing the signal loss and the installation cost, by installing a slave device in the vicinity of the base station antenna, connecting the slave device with the base station antenna by a short coaxial cable or a direct connection method, connecting the slave device with the master device installed in the building by an inexpensive UTP cable, and transmitting signals by a digital method. In order to achieve the above object, the present invention provides a digital transceiver of a base station for cellular system, comprising: a master device installed in a building to be connected to a telephone exchange and communicating with a slave device by a digital method; a base station antenna installed in an outdoor region; a slave device installed in the vicinity of the base station antenna to be connected to the base station antenna through the coaxial cable or directly to the base station, and communicating directly with the master device by a digital communication method; and a UTP cable for connecting the master device with the slave device. Here, the master device comprises: an analog-digital converter for converting forward IF signals or RF signals to digital signals; a digital-analog converter for converting backward digital data to IF signals or RF signals; a programmable logic array for adding the digitally converted forward data streams to each other and distributing backward data streams; a master Ethernet encoder/decoder for encoding the forward outputs of the programmable logic array to transmit the encoded outputs through the UTP cable and decoding digital signals received through the UTP cable to reproduce the received digital signals; and a master controller for monitoring and controlling operations of each part. And, the slave device comprises: a slave Ethernet encoder/decoder for encoding and decoding the digital data to receive or transmit the data from or to the master device through the UTP cable; a programmable logic for distributing the forward data streams reproduced by the Ethernet encoder/decoder, adding the backward data to each other, and transferring the added data to the Ethernet encoder/decoder; a digital-analog converter for converting the distributed forward digital data to IF signals or RF signals; an up-converter for converting the forward IF signals to the RF signals; an RF high-output amplifier for amplifying the forward RF signals and outputting the amplified signals through a transmission antenna; a low-noise amplifier for amplifying the signals received through a reception antenna; a down-converter for converting the backward RF signals to the IF signals; and an analog-digital converter for converting the backward IF signals or RF signals to the digital signals and transferring the digital signals to the programmable logic array.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which: Fig. 1 is an installation concept diagram of a digital transceiver of a mobile communication base station according to the present invention; and Fig. 2 is a configuration block diagram illustrating the digital transceiver of a mobile communication base station according to the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION Reference will now be made in detail to the present invention, examples of which are illustrated in the accompanying drawings. Typically, a base station system is composed of one omni-directional antenna or 2 to N sector antennas having directivity. A preferred embodiment of the present invention will be described in detail by referring to a diversity method using three-sector antenna, each of which has two reception antennas. Fig. 1 is an installation concept diagram of a digital transceiver of a mobile communication base station according to the present invention. A base station system according to the present invention, as shown Fig.l, is installed in a building 2, and comprises: a master device 10 connected to a telephone exchange to communicate with a slave device 20 by a digital method; a plurality of base station antennas 31,, 31₂, 31₃, 32 32₂, 32₃, 32'ι, 32'₂, 32'₃ installed at an outdoor steel tower, the slave device 20 installed in the vicinity of the base station antennas to be connected to the base station antennas by short cables or directly to the base antennas and communicating with the master device 10 by the digital method; and a plurality of UTP cables 40-1-40-3 formed with inexpensive general telephone lines for connecting the master device 10 with the slave device 20. Referring to Fig. 1, the base station antennas 31_l9 31₂, 31₃, 32j, 32₂, 32₃, 32' i, 32'₂, 32'₃ are separated into 3sectors. Each of the sectors includes one transmission antenna and two reception antennas, h the preferred embodiment of the present invention, each of the sectors is identified by a subscript described in a bottom end of the reference number and a diversity antenna of the reception antennas is identified by adding " ' " to the reference number. The slave device 20 is installed in the vicinity of the base station antennas to be connected to the base station antennas by short coaxial cables. In addition, each of the sectors of the slave device is connected to each of the sectors of the master device

10 by the UTP cables 40-1-40-3 in the preferred embodiment of the present invention illustrating a three-sector antenna structure. In the present invention, since the master device 10 and the slave device 20 transmit and receive signals by the digital method, the loss of signals due to the UTP cables 40-1-40-3 is not generated therebetween. In addition, the loss of cables is not generated by connecting the slave device 20 to the antenna by a short coaxial cable, or connecting the slave device 20 directly to the antenna. Fig. 2 is a configuration block diagram illustrating the digital transceiver of a mobile communication base station according to the present invention comprising the master device 10 installed in the building and the slave device 20 installed in the vicinity of the base station antenna 30. Referring to Fig. 2, the forward data received from the telephone exchange are encoded and modulated by the RF or IF transmitters Tl~Tn of each of the sectors installed in the conventional base station and the modulated data are inputted into the master device 10. The master device 10 of the present invention, as shown in Fig. 2, is composed of N sector parts having the same structure in each of the sectors. Each of the sector parts includes a down-converter llι~ll_n for converting the forward RF signals to the IF signals; an analog-digital converter 13ι~13_n for converting the forward IF signals (or RF signals) to the digital signals; a digital-analog converter 14ι~14_n for converting the backward digital data to the IF signals (or RF signals); an up-converter 12ι~12_n for converting the backward IF signals to the RF signals and providing the RF signals to a plurality of receivers Rι~R_n for converting; a diversity digital-analog converter 13'ι~l 3'_n for converting the backward digital data to IF signals or (RF signals); a diversity up-converter 12'ι~12'_n for converting the backward IF signals to the RF signals and providing the RF signals to the plurality of receivers Rι~R_n; a programmable logic array 15 for adding the digitally converted forward data streams to each other and distributing the backward data streams received from the slave device; and a master Ethernet encoder/decoder 16ι~16_n for encoding outputs of the programmable logic array 15 to transmit the encoded outputs through the UTP cables 40ι~40_n and decoding signals received through the UTP cables 40]~40_n to reproduce the signals. Each of sector parts is controlled by a controller 17 and is used for bypassing the IF signals without using the down- converters 11₁ — ll_n or the up-converters 12i~12_n, 12'ι~12'_n when receiving the IF signals from the RF or IF transmitters Tι~T_n. Meanwhile, the slave device 20 of the present invention, as shown in Fig. 2, is composed of N sector parts having the same configuration. Each of the sector parts comprises a slave Ethernet encoder/decoder 26ι~26_n for encoding outputs of a programmable logic array 25 to transmit the encoded outputs though the UTP cables 40-l~40-n and decoding signals received through the UTP cables 40-l~40-n to reproduce the signals; the programmable logic array 25 for adding the digitally converted backward data streams to each other, transmitting the added backward data streams to the master device, and distributing the forward data streams received from the master device; a digital-analog converter 23ι~23_n for converting the forward digital data to IF signals (or RF signals); an up-converter 21₁~21_n for converting the forward IF signals to the RF signals; an RF high-output amplifier 27ι~27_n for amplifying the forward RF signals and outputting the amplified signals though a transmission antenna; a low-noise amplifier 28ι~28_n for amplifying the backward signals received through a main reception signal; a diversity low-noise amplifier 28 ' ι~28 '_n for amplifying signals received tlirough a diversity reception antenna; a down-converter 22ι~22_n for converting the backward RF signals to the IF signals; a diversity down-converter 22'ι~22'_n for converting the backward RF signals to the IF signals; an analog-digital converter 24ι~24_n for converting the backward IF signals (or RF signals) to the digital signals; and a diversity analog-digital converter 24' ι~24'_n for converting the backward IF signals (or RF signals) to the digital signals.

And, each of the sector parts is controlled by a slave controller 29 and communicates with the master controller 17 of the master device to exchange information each other and perform smoothly a maintenance process. In addition, the controllers 17,29 include monitoring units to monitor and control operating states (for examples, outputs, temperatures, power failure, circumferences, and etc.) of the master device and the slave device. In addition, the programmable logic arrays 15,25 can be omitted from the master device and the slave device of the present invention when the present invention is applied to one sector or the small number of sectors, a relay, and etc. Next, each of operations is a forward signal part and a backward signal part in accordance with the preferred embodiment of operations according to the present invention

[Transmission for forward signals] In order to provide a cellular communication service (data, voices, and images) using RF such as VHF, UHF, microwaves, and etc., the base station installed in the building encodes and modulates the forward subscriber signals received from the telephone exchange and inputs the RF signals of the small outputs into the master device of the present invention. The down converters l lι~l l_n of the master device according to the present invention convert the input signals to the IF signals when the input signals are the RF signals or bypasses the input signals when the input signals are the IF signals. The analog-digital converters 13ι~13_n convert the forward IF signals received from the down converters l lι~l l_n to the digital signals. The programmable logic array 15 processes the transmission data received from the analog-digital converters 13ι~13_n of each sector, forms forward data streams of each sector, and transmits the forward data streams to corresponding Ethernet encoder/decoders 16ι~16_n. And, each of the Ethernet encoder/decoders 16ι~16_n encodes the received forward data streams and transmits the encoded forward data streams to the slave device 20 through the UTP cables 40-1 -40-n. The slave device 20 installed in the vicinity of the antenna according to the present invention decodes the forward data received from the master device 10 through the UTP cables 40-l~40-n by using the Ethernet encoder/decoders 26ι~26_n, and transmits the decoded forward data to the programmable logic array 25. The programmable logic array 25 distributes the forward transmission data received from each of the Ethernet encoder/decoders 26ι~26_n and transmits the distributed forward transmission data to corresponding digital-analog converters 23ι~23_n of the sectors. The digital-analog converters 23ι~23_n convert the received forward digital signals to the IF signals. The up-converters 21ι~21_n convert the forward digital signals to the RF signals and transmits the RF signals to the RF high-output amplifiers 27ι~27_n. The RF high-output amplifiers 27₁~27_n amplify the forward RF signals and transmits the amplified signals to the subscribers through transmission antennas 31ι~31_n.

[Transmission for backward signals] Meanwhile, main reception antennas 32j~32_n and diversity reception antennas 32'₁~32'_n receive the backward signals transmitted from subscribers' terminals to the base station. Namely, the backward signals received through the main reception antennas 32ι~32_n are amplified by the low-noise amplifiers 28ι~28_n of the slave device and the amplified backward signals are converted to the IF signals by the down-converters 22ι~22_n. The IF signals are converted to the digital data by the analog-digital converters 24ι~24_n and the digital data are inputted into the programmable logic array 25. Meanwhile, the signals received through the diversity reception antennas 32'₁-32'_n are amplified by the corresponding low-noise amplifiers 28'ι~28'_n and the amplified signals are converted to the IF signals by the corresponding down-converters 22ι~22_n. The IF signals are converted to the digital data by the analog-digital converters 24ι~24_n and the digital data are inputted into the programmable logic array 25. In case of the backward path like the above, since the main reception signals and the diversity reception signals are operated equally, only the main reception signals will be described in detail to simplify the explanation. The programmable logic array 25 processes the backward data received from the slave device the analog-digital converters 24ι~24_n of each sector and transmits the processes backward data to the Ethernet encoder/decoders 26ι~26_n of the corresponding sectors. The Ethernet encoder/decoders 26i~26_n of the corresponding sectors encode the received backward digital data and transmit the encoded backward digital data to the Ethernet encoder/decoders 16j~16_n of the master device through the UTP cables 40-l~40-n. The Ethernet encoder/decoders 16ι~16_n of the master device installed in the building decode the backward signals received tlirough the UTP cables 40-l~40-n and transmits the decoded backward signals to the programmable logic array 15. The programmable logic array 15 distributes the received backward data streams to the digital-analog converters 14ι~14_n of each sector. The digital-analog converters 14ι~14_n converts the received digital data to the backward IF signals and transmits the backward IF signals to the up-converters 12ι~12_n. The up-converters 12ι~12_n convert the backward IF signals to the RF signals and transmit the RF signals to receivers Rι~R_n of the base station when the receivers Rι~R_n of the base station receive the RF signals, or bypass the backward IF signals received from the digital-analog converters 14ι~14_n and transmit the backward IF signals to the receivers Rι~R_n of the base station when the receivers Rι~R_n of the base station receive the IF signals. Meanwhile, the controller 17 of the master device and the controller 29 of the slave device transmit data according to predetermined protocols in order to provide the operating state information. The controller 17 of the master device provides the operating state information to the telephone exchange in order to perform easily a maintenance process.

INDUSTRIAL APPLICABILITY As described above, the master device of the present invention is located in the building and the slave device is located in the vicinity of the outdoor antenna when the base station system is installed in the building. The master device and the slave device are connected each other by the UTP cables in order to communicate with each other by the digital communication method. Accordingly, the present invention using the UTO cables provides inexpensive high-quality services by reducing the RF loss to 1/11, the RF transmission/reception noise to 1/10, the cable cost to 1/4, respectively in comparison with an existing method using coaxial cables. While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A digital transceiver of a mobile communication base station comprising: a master device installed in a building to be connected to a telephone exchange, and communicating with a slave device by a digital method; a base station antenna installed in an outdoor region; the slave device installed in the vicinity of the base station antenna to be connected to the base station antenna through the coaxial cable or directly to the base station, and communicating directly with the master device by a digital communication method; and a UTP cable for connecting the master device with the slave device.

2. The digital transceiver of a mobile communication base station of claim 1, wherein the master device comprises: an analog-digital converter for converting forward IF signals or RF signals to digital signals; a digital-analog converter for converting backward digital data to IF signals or RF signals; an Ethernet encoder/decoder for encoding the forward outputs of the digital- analog converter to transmit output the encoded outputs through the UTP cable and decoding the digital signals received through the UTP cable to reproduce the decoded signals; and a master controller for monitoring and controlling operations of each part.

3. The digital transceiver of a mobile communication base station of claim 2, wherein the master device further comprises a programmable logic array for adding the digitally converted forward data streams to each other, transmitting the added forward data streams to the Ethernet encoder/decoder, and distributing backward data streams received from the Ethernet encoder/decoder to the digital-analog converter of each of plural sectors when the programmable logic array is composed of the sectors.

4. The digital transceiver of a mobile communication base station of claim 2, wherein the master device further comprises: a down-converter for converting forward RF signals received from a telephone exchange to IF signals; and an up-converter for converting backward IF signals received from the digital-analog converter to the RF signals.

5. The digital transceiver of a mobile communication base station of claim 2, wherein each of the sectors of the master device comprises an analog-digital converter, a digital-analog converter, and an Ethernet encoder/decoder when the base station is composed of N sector method.

6. The digital transceiver of a mobile communication base station of claim 2, wherein the master device further comprises a diversity digital-analog converter and a diversity up-converter when using a reception diversity method.

7. The digital transceiver of a mobile communication base station of claim 1, wherein the slave device comprises: a slave Ethernet encoder/decoder for encoding and decoding the digital data to receive or transmit the digital data from or to the master device through the UTP cable; a digital analog converter for converting the decoded forward data to IF signals or RF signals; an up-converter for converting the forward IF signals to the RF signals; an RF high-output amplifier for amplifying the forward RF signals and outputting the amplified signals tlirough a transmission antenna; a low-noise amplifier for amplifying the signals received through a reception antenna; a down-converter for converting the backward RF signals to the IF signals; an analog-digital converter for converting the backward IF signals or RF signals to the digital signals; and a slave controller for monitoring and controlling operations of each part.

8. The digital transceiver of a mobile communication base station of claim 7, wherein the slave device further comprises a programmable logic array for distributing the forward data streams reproduced through the Ethernet encoder/decoder to the digital-analog converter of each of the sectors, adding the backward data received from the digital-analog converter of each of the sectors, and transferring the added backward data to the Ethernet encoder/decoder when the programmable logic array is composed of the sectors.

9. The digital transceiver of a mobile communication base station of claim 7, wherein each of the sectors of the slave device comprises a slave Ethernet encoder/decoder, the digital-analog converter, the up-converter, the RF high-output amplifier, the low-noise amplifier, the down-converter, and the analog-digital converter.

10. The digital transceiver of a mobile communication base station of claim

7, wherein the slave device further includes a diversity low-noise amplifier for amplifying signals received through a diversity reception antenna, a diversity down- converter, and a diversity analog-digital converter when using a reception diversity method.

11. The digital transceiver of a mobile communication base station of claim 1 has one-directional communication function using any one of a forward method and a backward method.