KR100232544B1 - Signal re broadcasting apparatus of digital lmds - Google Patents

Abstract

[Technical field to which the invention described in the claims belong]

Digital Local Multipoint Distribution System (LMDS)

[Technical Challenges to Invent]

The general LMDS is to implement a signal relay system that transmits the signal of the LMDS broadcasting station to the subscriber, and retransmits the signal of each subscriber to the LMDS broadcasting station.

[Summary of the solution of the invention]

A local source unit 10 for editing and transmitting a special program of a corresponding region located at a cell site end; A downlink transmitter / receiver 20 for rearranging and amplifying a signal transmitted from the headend, and multiplexing the signal transmitted from the local source unit 10 to transmit signals to respective subscribers located in the corresponding cell; An uplink retransmitter (30) for converting the signals transmitted from the subscribers into signals of appropriate magnitude and then relaying them back to the LMDS broadcasting station; It consists of a local control and monitor unit 40 for setting and controlling the relevant parameters, monitoring the operation state and performing overall control on the operation of the downlink transmission / reception unit 20 and the uplink retransmission unit 30 signal transmission and reception It is a feature.

[Important Uses of the Invention]

In digital LMDS, it is applied to retransmit each subscriber signal to LMDS station.

Description

Digital LMS Signal Repeater

In general, Digital LMDS (Local Multipoint Distribution System) is a system that provides multi-channel, two-way wireless digital CATV service using the frequency of 27.5-29.5GHz band.It is a telephone, VOD, Internet, satellite broadcasting as an additional service in addition to the existing CATV service. Provide interactive services such as

In order to implement the digital LMDS service of the nationwide or extensive region in the 28 GHz band, the LMDS network should be designed in each region with a frequency reach, that is, a radius of 5 km.

At this time, the LMDS broadcasting station transmits / receives a link signal and a signal relay system in each cell unit, which is a basic unit of network configuration. The signal relay system at the cell site of each region receives the signal from the LMDS broadcasting station, rearranges the signal, amplifies the signal, and transmits the signal to each subscriber located in the cell. It is responsible for converting the signals transmitted from the LMDS stations into signals of appropriate size.

However, the conventional signal re-relay system having such a function is suitable for analog CATV system, but has a disadvantage of being unsuitable for a multiple access digital CDMA system.

Accordingly, the present invention has been proposed to solve various problems of the analog signal re-relay system of the above type, and an object of the present invention is to reorder and add a signal transmitted from an LMDS broadcasting station, and then add subscribers located in the corresponding cell. The present invention provides a digital LMDS signal retransmission apparatus that transmits a signal to the LMDS broadcasting station after converting a signal transmitted from each subscriber into a signal of an appropriate size.

Technical means for achieving the object of the present invention, the local source unit for editing and transmitting a special program of the region located at the cell site end; A downlink transmitter / receiver for rearranging and amplifying the signal transmitted from the headend and then multiplexing the signal transmitted from the local source unit and transmitting the signal to each subscriber located in the corresponding cell; An uplink retransmitter which converts the signals transmitted from the subscribers into signals of appropriate size and then relays them back to the LMDS broadcasting station; It consists of a local control and monitor unit for setting and controlling the observation parameters when transmitting and receiving the signals of the downlink transmission and reception unit and the uplink retransmission unit, and performs overall control regarding the operation and monitoring.

Hereinafter, described in detail with reference to the accompanying drawings of the present invention.

1 is a block diagram of a signal relay apparatus for digital LMDS according to the present invention.

* Explanation of symbols for main parts of the drawings

10: local source unit 20: downlink transmission / reception unit

30: uplink retransmission unit 40: local control and monitor unit

1 is a block diagram of a signal repeater for digital LMDS according to the present invention.

As shown therein, a local source unit 10 for editing and transmitting a special program of the corresponding memory located at the cell site end; A downlink transmitter / receiver 20 for rearranging and amplifying a signal transmitted from the headend, and then multiplexing a signal transmitted from the local source unit 10 and transmitting a signal to each subscriber located in a corresponding cell; An uplink retransmitter (30) for converting the signals transmitted from the subscribers into signals of appropriate magnitude and then relaying them back to the LMDS broadcasting station; It consists of a local control and monitor unit 40 for setting and controlling the parameters related to the transmission and reception of the downlink transmission / reception unit 20 and the uplink retransmission unit 30, monitoring the operation state, and performing overall control on the operation. .

In the above, the downlink transmission / reception unit 20 amplifies an antenna 21 for receiving 27.5 GHz-29.5 GHz microwaves transmitted from the head-end, and a microwave received from the antenna 21 into a predetermined band, and then a predetermined band. A low noise amplifier 22 for converting to an intermediate frequency of the signal, an intermediate frequency processor 23 for processing the intermediate frequency obtained by the low noise amplifier 22, and separating the digital signal into an analog signal and outputting the intermediate signal; FM demodulation of the analog signal output from the (23) to make the original signal, the analog demodulation section 24, and the signal obtained from the analog demodulation section 24 and the signal transmitted from the live local source section 10 and An analog modulator 25 for modulating for each channel, a digital demodulator 26 for QPSK / QAM demodulation of the digital signal output from the intermediate frequency processor 23 to make an original signal; The digital demodulator 27 modulates the digital signal demodulated by the digital demodulator 26 for each channel, and multiplexes the signals obtained from the analog modulator 25 and the digital modulator 27 to the subscriber. It consists of a data transmission unit 28.

Referring to the operation of the signal relay device of the digital LMDS according to the present invention configured as described above are as follows.

First, the downlink transmitter / receiver 20 receives 27.5 GHz to 29.5 GHz microwaves transmitted from the head end to the antenna 21, and the low noise amplifier 22 receives noise from the received microwaves. After removing and amplifying to a predetermined level, it is converted to an intermediate frequency of 950-2050 MHz and transferred to the intermediate frequency processor 23 at the rear end.

Then, the intermediate frequency processor 23 processes the transmitted intermediate frequency to separate the analog signal and the digital signal, and transmits the analog received signal to the analog demodulator 24, and the digital received signal is the decoded demodulator 26. To pass on.

Accordingly, the analog demodulation unit 24 converts the received analog signal into analog FM demodulation to make the original signal, and the generated signal is transmitted to the analog modulation unit 25 and the local advertisement transmitted from the local source unit 10. The signal is multiplexed with a broadcast signal such as an analog signal and then analog-modulated for each channel and transmitted to the data transmitter 28.

Here, the local source unit 10 performs a function of editing and transmitting a special program of a corresponding region, that is, an emergency broadcast or a local commercial program, located at a cell site end.

In addition, the digital demodulator 26 demodulates the digital signal obtained by the intermediate frequency processor 23 to the original signal by demodulating Quadrature Phase Shift Keying (QPSK) / Quadrature Amplitude Modulation (QAM) to produce the original signal. The unit 27 is again digitally modulated for each channel and transmitted to the data transmitter 28.

In the above, the digital signal includes satellite broadcasting, broadcasting such as VOD (Video On Demand), communication services such as the Internet, telephone and data communication, control signals such as signaling, and the like.

Meanwhile, the data transmitter 28 multiplexes and amplifies the analog modulated signal and the digital modulated signal respectively obtained as described above, and transmits them to the subscriber station through the antenna 29 at a frequency of 27.5 GHz to 29.5 GHz.

Next, subscriber signals of 27.5 GHz-29.5 GHz transmitted from the subscriber end are received through the antenna 29 in the uplink retransmitter 30, and are converted into intermediate frequencies of 200-400 MHz in the retransmitter 31. After re-amplification, the antenna is retransmitted through the antenna 21 to the head-end terminal at a transmission frequency of 27.5 GHz to 29.5 GHz.

In the above, the downlink signal from the LMDS broadcasting station can be received through the optical cable as needed, and the link signal with the broadcasting station can be transmitted through the optical cable as necessary.

The local control and monitor unit 40 sets or controls various parameters related to the downlink transmission / reception unit 20 and the upstream retransmission unit 30 when the corresponding data is transmitted / received. The operation of the transmitter / receiver 20 and the uplink retransmitter 30 is monitored to monitor the operation state and manage the overall operation of the system, and perform the control function of the GUL method or the transmission / reception system.

As described in detail above, the present invention enables the realization of rational digital signal relaying of digital LMDS. Thus, the present invention provides a function for rearranging and amplifying a signal transmitted from an LMDS broadcasting station and transmitting the signal to each subscriber located in a corresponding cell. There is an effect that it is possible to smoothly perform the function of reverse relaying the signals transmitted from each subscriber to several LMDS stations which are converted into signals of appropriate size.

The present invention rearranges and adds a signal transmitted from an LMDS broadcasting station, transmits a signal to each subscriber located in a corresponding cell, converts the signals transmitted from each subscriber into a signal of an appropriate size, and then reverses the signal to the LMDS broadcasting station. The present invention relates to an implementation of a signal retransmission device for digital LMDS for relay.

Claims (4)

A digital LMDS comprising: a local source unit (10) for editing and transmitting a special program of a corresponding region located at a cell site end; A downlink transmitter / receiver 20 for rearranging and amplifying a signal transmitted from the headend, and multiplexing the signal transmitted from the local source unit 10 to each subscriber located in a corresponding cell; An uplink retransmitter (30) for converting the signals transmitted from the subscribers into signals of appropriate magnitude and then relaying them back to the LMDS broadcasting station; Characterized in that the local control and monitor unit 40 for setting and controlling the parameters related to the transmission and reception of the downlink transmission and reception unit 20 and the uplink retransmission unit 30, and performs overall control related to monitoring and operation Digital signal relay of LMDS (LMDS). The antenna of claim 1, wherein the downlink transmitter / receiver 20 amplifies an antenna 21 for receiving 27.5 GHz-29.5 GHz microwaves transmitted from the head end, and a microwave received from the antenna 21. A low noise amplifier 22 for converting into an intermediate frequency of a predetermined band, an intermediate frequency processor 23 for processing the intermediate frequency obtained by the low noise amplifier 22 and separating the digital signal into an analog signal and outputting the intermediate signal; An analog demodulator 24 for FM demodulating the analog signal output from the frequency processor 23 into the original signal, and multiplexes the signal obtained from the analog demodulator 24 and the signal transmitted from the local source unit 10. And a digital demodulator 26 for performing QPSK / QAM demodulation of the digital signal output from the intermediate frequency processor 23 to the original signal. A digital modulator 27 for modulating the digital signal demodulated by the grandfather 26 for each channel, and a data transmitter for multiplexing the signals obtained by the analog modulator 25 and the digital modulator 27 to the subscriber side. Digital signal relay of the LMDS, characterized in that consisting of (28). The signal repeater of claim 2, wherein the low noise amplifier 22 converts an input microwave of 27.5 GHz to 29.5 GHz into an intermediate frequency of 950 to 2050 MHz. The method according to claim 1, wherein the uplink retransmitter 30, after receiving the microwaves transmitted from each subscriber, the signal re-relay of the digital LMS (LMDS), characterized in that for processing by converting to an intermediate frequency of 200-400MHz Device.

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