KR20020027780A - Translator for minimizing BER of Ponit to Multi-Point transmission on millimeter wave - Google Patents

Abstract

PURPOSE: A translator for minimizing transmission errors in millimeter wave P-to-MP(Point to Multipoint) communication is provided to minimize signal errors in transmitting data using a modem in P-to-MP communication in a millimeter wave band of more than 20GHz. CONSTITUTION: A subscriber station translator(134) consists of a down converting part(211), an AGC(Auto Gain Control) part(212), a modem signal transmitting part(213), a pilot channel demodulation part(214), an APC(Auto Power Control) part(215), an up converting part(216), and a monitoring part(217). The down converting part(211) downconverts an RF signal, received from a base station through a radio transceiver(132), into a low frequency signal. The AGC part(212) adjusts an amplification degree according to the strength of the received signal and always maintains its output uniformly. The modem signal transmitting part(213) processes interfacing with a modem part(136). The pilot channel demodulation part(214) splits a pilot signal from a channel signal received from the base station, demodulates it, generates a clock signal synchronized with a reference clock signal transmitted from the base station, and supplies it to the radio transceiver(132). Also the pilot channel demodulation part(214) analyzes the level of the received pilot signal and provides a signal to control the AGC part(212) and the APC part(215). The APC part(215) maintains the power of a transmitting signal at a uniform level. The up converting part(216) receives a low-frequency transmitting signal from the modem signal transmitting part(213), upconverts it, and outputs a high-frequency RF signal to the APC part(215). The monitoring part(217) monitors the operations of the AGC part(212) and the APC part(215).

Description

Translator for minimizing BER of Ponit to Multi-Point transmission on millimeter wave}

The present invention relates to a transmission apparatus for minimizing signal error in data transmission using a modem in point-to-multipoint communication (P to MP) in the millimeter wave band of 20 GHz or more.

Recently, attention has been focused on the technology for using the millimeter wave band while designating the 20 GHz band for the B-WLL subscriber line frequency and the wireless CATV transmission frequency in order to construct a broadband wireless subscriber network (B-WLL). . As the frequency band for the B-WLL, the uplink frequency band was allocated 24.25GHz to 24.75GHz (500MHz), and the downlink frequency band was allocated 25.5GHz to 27.5GHz. Of the downlink frequency bands, 26.7 GHz to 27.5 GHz were allocated for wireless CATV transmission.

The transceiver for using the millimeter wave band requires an RF / IF unit and a modem unit. The modems known to date are designed to have a frequency deviation range of several tens of KHz or less due to the limitation of frequency characteristics on the wireline. Therefore, when using such a modem in the millimeter wave band of 20 GHz or more, a stable signal transmission can be achieved when the frequency deviation range is within several tens of KHz. In addition, even in the case of using a highly efficient modulation (64QAM or 256 QAM) signal, the transmission of the millimeter wave band must have a stable frequency deviation.

In addition, in order to maintain a good BER characteristic at a satisfactory C / N ratio according to the modulation method in the radio, it should have a good phase noise characteristic of less than 75dBc @ 10KHz.

When using a commercially available modem on the wire and a modem using a high-efficiency modulation method for transmitting / receiving millimeter wave bands, the base station and the subscriber station have a function of creating and restoring a pilot channel in order to minimize signal error, It is necessary to secure a frequency deviation of less than +/- 1 PPM.

It is an object of the present invention to provide a transmitter apparatus of a radio transceiver for minimizing transmission error in millimeter wave point-to-multipoint communication in order to meet the necessity.

1 is a configuration example of a broadband wireless subscriber network to which the present invention can be applied,

2 is a block diagram showing a subscriber station translator according to a first embodiment of the present invention;

3 is a block diagram showing a base station translator according to a first embodiment of the present invention;

4 is a block diagram showing a subscriber station translator according to a second embodiment of the present invention;

5 is a block diagram illustrating a base station translator according to a second embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

120: base station 130: subscriber station

124, 136: modem unit 126, 134: translator

128,132: wireless transceiver

In order to achieve the above object, the apparatus of the present invention includes a translator for up-converting the frequency of the transmission signal from the modem unit to the radio transceiver, and down-converting the frequency of the signal received from the radio transceiver. In a millimeter-band mode wirelessly between a base station apparatus and a subscriber station apparatus including a translator which upconverts the frequency of the transmission signal from the modem section to the radio transceiver, downconverts the frequency of the signal received from the wireless transceiver, and transmits it to the modem section. A wideband wireless subscriber network for communicating, the translator of the base station apparatus comprising: a downlink frequency converter for downconverting a signal received from a subscriber station to a low frequency band through a radio transceiver; A modem signal transmitter for transmitting a signal received from the downlink frequency converter to the modem and receiving a signal from the modem; A pilot channel modulator for generating a clock therein and providing the signal to the wireless transceiver and generating a modulated pilot signal synchronized with the clock and then modulating and outputting the pilot signal; An uplink frequency converter converting a signal input from the modem signal transmitter into an uplink frequency band; And a channel synthesizer for combining the output of the pilot channel modulator with the output of the uplink frequency converter and outputting the output to the radio transceiver. The translator of the subscriber station apparatus downgrades a signal received from a base station through a radio transceiver to a low frequency band. A downlink frequency converter for converting; An automatic gain control unit that maintains a constant output at all times by adjusting an amplification degree according to the strength of the received signal input from the downlink frequency converter; A modem signal transmission unit for transmitting a signal received from the automatic gain control unit to the modem unit and receiving a signal from the modem unit; After separating and demodulating the pilot signal from the channel signal received from the base station, a clock signal synchronized with the reference clock signal transmitted from the base station is generated and provided to the wireless transceiver, and the received pilot signal level is analyzed to analyze AGC and APC. A pilot channel demodulation unit providing a signal for controlling; An uplink frequency converter converting a signal input from the modem signal transmitter into an uplink frequency band; An automatic power controller which receives the output of the uplink frequency converter and maintains the power of the transmission signal at a constant level; Monitors the operation of the automatic gain control unit and the automatic power control unit, characterized in that it comprises a monitoring unit for monitoring the transmission and reception power level.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an example of a configuration of a broadband wireless subscriber network to which the present invention can be applied. As shown in FIG. 1, the wireless subscriber network (B-WLL) is connected to an ATM switch 114 to perform wireless transmission in the form of an ATM cell, and is connected to a switch 108 for MUX and IP. It may be configured as a network configuration in which wireless transmission is performed in IP or STM type packets. In general, the base station 120 is distributed in cell units, and the ATM switch 114 / MUX and IP switch 108 is located in a telephone station, and the subscriber station 130 is fixed in a building such as a home or an office. Is installed. The base station 120 includes a network interface module (NIM) 122, a modem 124, a translator 126, and a wireless transceiver 128. The subscriber station 130 also includes a wireless transceiver 132 and a translator 134. And a modem 136 and a subscriber interface unit (SIU) 138 to communicate in a millimeter wave band.

In the radio section (between the subscriber station and the base station), data is transmitted in an ATM cell or an IP packet, connected to an ATM switch 114 in the case of an ATM cell, and a switch 108 for an MUX and an IP in the case of an IP packet. Connected to and transmitted. By the NIM 122 of the base station, all received data is connected to the ATM switch 114 or the MUX and IP switch 108 depending on the type of traffic, and the data transmitted to the ATM cell is transferred by the ATM switch 114. Circuit emulation or LAN emulation may be transmitted to the existing dedicated circuit 104, PSTN network 102, the Internet network 106. The NIM 122 of the base station functions to provide various interfaces between the service network and the modem. The subscriber station 130 and the base station 120 form a communication channel using 24.25 GHz to 24.75 GHz (500 MHz) in the uplink and 25.5 GHz to 27.5 GHz in the downlink, and transmit and receive using a horn antenna with the radio transceivers 128 and 132. do.

The modems 124 and 136 of the base station and the subscriber station modulate and demodulate the data using 64 QAM or 256 QAM schemes, and the translators 126 and 134 up-convert the low frequency to the high frequency when transmitting and the high frequency when receiving. Performs frequency conversion function to down convert to low frequency. In particular, the translators 126 and 134 according to the present invention require the modems 124 and 136 to precisely synchronize the clock CLOCK between the base station 120 and the subscriber station 130 using the pilot signal in the first embodiment. In this embodiment, the reference clock stabilizer is used to reduce the clock deviation between the base station and the subscriber station to satisfy the performance required by the modems 124 and 136.

First embodiment

2 is a block diagram showing a subscriber station translator according to the first embodiment of the present invention. The subscriber station translator 134 according to the present invention includes a downlink frequency converter 211 and an automatic gain control unit (AGC) 212. And a modem signal transmitter 213, a pilot channel demodulator 214, an automatic power control unit (APC) 215, an uplink frequency converter 216, a monitor 217, and a receiver of the radio transceiver 132. The high frequency signal received from the modem is converted into a low frequency band and output to the modem 136, and the signal of the low frequency band received from the modem 136 is converted into a high frequency band and output to the transmitter of the radio transceiver 132. As described above, the translator 134 of the first embodiment converts the IF frequency of the radio transceiver 132 which performs the millimeter wave wireless communication to the up / down frequency band of a commercially available modem device while minimizing the signal error. Implemented to have a restore function. To this end, the pilot signal to be generated at the base station is transmitted to the subscriber station through FM / AM modulation, and the subscriber station recovers the signal and provides it as a reference clock signal of the subscriber station radio transceiver or as a reference level signal of the AGC / APC. . By doing so, the frequency deviation between the base station and the subscriber station can be minimized, and the clock signal of the modem included in the channel signal can be stably transmitted to the modem 136. At this time, the signal provided as a reference clock signal to the radio transceiver 132 should be limited in the number of multiplication to have a stable phase noise characteristics. Therefore, transmission and reception of a modulated signal and a modem used on a wire in a millimeter wave band of 20 GHz or more can be performed while maintaining a BER characteristic of 10E-7 or less.

In addition to these functions, the translator 134 of the first embodiment uses an internal CPU to enable the AGC / APC function, temperature monitoring function, oscillation frequency monitoring function, AGC / APC operation monitoring function, PLL data clock enable, etc. according to the external environment conversion. Has the function of.

Referring to FIG. 2, the downlink frequency converter 211 down-converts a high frequency signal received from a base station through a radio transceiver 132 to a low frequency signal band, and an automatic gain control unit (AGC) 212 is applied to the strength of the received signal. The output signal is always kept constant by adjusting the amplification degree, and the modem signal transmitter 213 processes the interface with the modem unit 136. The pilot channel demodulator 214 separates and demodulates the pilot signal from the channel signal received from the base station, generates a clock signal synchronized with the reference clock signal transmitted from the base station, and provides it to the radio transceiver 132. The received pilot signal level is analyzed to provide a signal for controlling the AGC 213 and the APC 215. The automatic output control unit (APC) 215 maintains the power of the transmission signal at a constant level, and the uplink frequency converter 216 receives the low-band transmission signal from the modem signal transmission unit 213 and converts it into an uplink frequency. The RF signal of the band is output to the automatic power control unit 215. The monitoring unit 217 monitors the operation of each unit, monitors the operation of the AGC / APC unit, and monitors the TX / RX power level.

3 is a block diagram illustrating a base station translator according to a first embodiment of the present invention, wherein the base station translator 126 includes a downlink frequency converter 311, a modem signal transmitter 312, and a pilot channel modulator 313. And an uplink frequency converter 314 and a channel synthesizer 315 to convert the high frequency received from the receiver of the radio transceiver 128 into a low frequency band and output the low frequency band to the modem unit 124, from the modem unit 124. The received low frequency band signal is converted into a high frequency band, synthesized together with a pilot signal, and output to the transmitter of the radio transceiver 128.

Referring to FIG. 3, the downlink frequency converter 311 down-converts a high frequency signal received from a subscriber station through a radio transceiver 128 to a low frequency signal band and outputs the signal to the modem signal transmitter 312 to transmit a modem signal. The unit 312 processes an interface with the modem unit 124. The pilot channel modulator 313 internally generates a clock (CLOCK), provides the signal to the wireless transceiver 128, generates a pilot signal synchronized with the clock, and modulates it to output the channel to the channel synthesizer 315. The uplink frequency converter 314 up-converts the lowband transmission signal received from the modem signal transmitter 312 into a highband RF signal and outputs the converted signal to the channel synthesizer 315. The channel synthesizer 315 combines the pilot signal with the signal input from the uplink frequency converter 314 and outputs the pilot signal to the radio transceiver 128.

Second embodiment

4 is a block diagram showing a subscriber station translator according to a second embodiment of the present invention, and FIG. 5 is a block diagram showing a base station translator according to a second embodiment of the present invention. In the second embodiment, the reference clock stabilizer is used to remove the pilot channel generation and recovery function of the first embodiment and maintain the frequency deviation at +/− 1 PPM. The reference clock stabilizers 414 and 513 may use an OCXO as a reference clock generator or use a stabilized TCXO having an AFC circuit and similar characteristics to achieve a target frequency stability.

Referring to FIG. 4, the downlink frequency converter 411 down-converts a high frequency signal received from a base station through the radio transceiver 132 to a low frequency signal band, and the automatic gain controller 412 amplifies the signal according to the strength of the received signal. By maintaining the output constant at all times, the modem signal transmission unit 413 processes the interface with the modem unit 136. The reference clock stabilization unit 414 generates a stable reference clock signal on its own and provides it to the radio transceiver 132. The automatic output control unit 416 maintains the power of the transmission signal at a constant level, and the uplink frequency converter 415 receives the low-band transmission signal from the modem signal transmission unit 413 and converts it into the uplink frequency of the high-band. Outputs an RF signal to the automatic power control unit 416. The monitoring unit 417 monitors the operation of each unit, monitors the operation of the AGC / APC unit 412/416, and monitors the TX / RX power level.

Referring to FIG. 5, the downlink frequency converter 511 down-converts a high frequency signal received from a subscriber station through a wireless transceiver 128 to a low frequency signal band and outputs the signal to the modem signal transmitter 512 to transmit a modem signal. The unit 512 processes the interface with the modem unit 124. The reference clock stabilizer 513 generates its own stable reference clock signal CLOCK and provides it to the radio transceiver 128, and the uplink frequency converter 514 of the low band received from the modem signal transmitter 512. The transmission signal is converted into a high band RF signal and output to the radio transceiver 128.

As described above, according to the present invention, when the base station apparatus modulates and transmits a pilot signal, the base station apparatus demodulates the pilot signal, generates a reference clock, and uses the subscriber station. This can meet the performance requirements of the modem. In addition, when the reference clock stabilizer is used to generate the reference clock at the base station and the subscriber station, the pilot signal does not need to be used, thereby simplifying the circuit configuration and satisfying the frequency deviation required by the modem.

Claims (2)

A base station apparatus including a translator which upconverts the frequency of a transmission signal from the modem unit to the radio transceiver, downconverts the frequency of the signal received from the radio transceiver, and transmits the signal to the modem unit; In the broadband wireless subscriber network for up-converting the frequency, down-converting the frequency of the signal received from the radio transceiver, and transmitting to the modem unit, the subscriber station apparatus including a translator in a millimeter band wirelessly. The translator of the base station apparatus A downlink frequency converter for downconverting the signal received from the subscriber station through the radio transceiver into the low frequency band; A modem signal transmitter for transmitting a signal received from the downlink frequency converter to the modem and receiving a signal from the modem; A pilot channel modulator for generating a clock therein and providing the signal to the wireless transceiver and generating a modulated pilot signal synchronized with the clock and then modulating and outputting the pilot signal; An uplink frequency converter converting a signal input from the modem signal transmitter into an uplink frequency band; A channel synthesizer for synthesizing an output of the pilot channel modulator to an output of the uplink frequency converter and outputting the output to the radio transceiver; The translator of the subscriber station apparatus, A downlink frequency converter for downconverting a signal received from a base station through a radio transceiver to a low frequency band; An automatic gain control unit for controlling the amplification degree according to the strength of the received signal inputted from the downlink frequency converter to keep the output constant at all times; A modem signal transmission unit for transmitting a signal received from the automatic gain control unit to the modem unit and receiving a signal from the modem unit; After separating and demodulating the pilot signal from the channel signal received from the base station, a clock signal synchronized with the reference clock signal transmitted from the base station is generated and provided to the wireless transceiver, and the received pilot signal level is analyzed to analyze AGC and APC. A pilot channel demodulation unit providing a signal for controlling; An uplink frequency converter converting a signal input from the modem signal transmitter into an uplink frequency band; An automatic power controller which receives the output of the uplink frequency converter and maintains the power of the transmission signal at a constant level; And a monitoring unit for monitoring the operation of the automatic gain control unit and the automatic power control unit, and monitoring a transmission / reception power level. A base station apparatus including a translator which upconverts the frequency of a transmission signal from the modem unit to the radio transceiver, downconverts the frequency of the signal received from the radio transceiver, and transmits the signal to the modem unit; In the broadband wireless subscriber network for up-converting the frequency, down-converting the frequency of the signal received from the radio transceiver, and transmitting to the modem unit, the subscriber station apparatus including a translator in a millimeter band wirelessly. The translator of the base station apparatus A downlink frequency converter for downconverting the signal received from the subscriber station through the radio transceiver into a low frequency band; A modem signal transmitter for transmitting a signal received from the downlink frequency converter to the modem and receiving a signal from the modem; A reference clock stabilization unit for generating a stable reference clock signal by itself and providing the same to the wireless transceiver; An uplink frequency converting unit converting a signal input from the modem signal transmitting unit into an uplink frequency band, The translator of the subscriber station apparatus, A downlink frequency converter for downconverting a signal received from a base station through a radio transceiver to a low frequency band; An automatic gain control unit that maintains a constant output at all times by adjusting an amplification degree according to the strength of the received signal input from the downlink frequency converter; A modem signal transmission unit for transmitting a signal received from the automatic gain control unit to the modem unit and receiving a signal from the modem unit; A reference clock stabilization unit for generating a stable reference clock signal by itself and providing the same to the wireless transceiver; An uplink frequency converter converting a signal input from the modem signal transmitter into an uplink frequency band; An automatic power controller which receives the output of the uplink frequency converter and maintains the power of the transmission signal at a constant level; And a monitoring unit for monitoring the operation of the automatic gain control unit and the automatic power control unit, and monitoring a transmission / reception power level.