KR101048960B1 - Signal Transition Delay Time Compensation Switching Timing Generation Method for Optical Repeater and Optical Repeater for Signal Delay Compensation Between Base Station and Repeater in OBD-TD WiBro System - Google Patents

Abstract

The present invention relates to an optical repeater and a signal transmission delay time compensation switching timing signal generation method of the optical repeater to compensate for the signal propagation delay time in the optical repeater in the WiBro system.

In the switching timing signal generation method of the present invention, when an RF signal is transmitted from a base station to a remote module through a main donor module of an optical repeater, a first step of extracting a portion of the RF signal to determine a frame start position of the RF signal Wow; Calculating a start point of a downlink signal and an uplink signal included in the RF signal based on the frame start position; A third step of compensating the signal propagation delay time by advancing the calculated starting point of the uplink signal by twice (2D) the signal propagation delay time (D) according to the optical cable length between the base station and the optical repeater remote module; A fourth step of generating a switching timing signal using the start point information of the downlink signal calculated in the second step and the start point information of the uplink signal compensated for the delay time in the third step and transmitting the switching timing signal to a switch of the optical repeater remote module; And a fifth step of the switch separating and transmitting a downlink signal and an uplink signal by the switching timing signal. There is a technical feature made to include.

Description

Optical Repeater for Compensating Delay Time between RAS and the Optical Repeater and Method for Compensation of Signal Transmit Delay Time between Base Station and Repeater in OBD-TD Wibro System for Generating Switching Timing Signal Compensating Delay Time between RAS and the Optical Repeater in OFDM-TDD Type Wireless Broadband System}

1 is a block diagram of a WiBro system for explaining the present invention,

2 is an internal configuration diagram of an optical repeater according to an embodiment of the present invention;

3 is an internal configuration diagram of a switching timing signal generation circuit according to an embodiment of the present invention;

4 is a conceptual diagram illustrating a signal propagation delay time compensation operation of the switching timing signal generation circuit of FIG. 3;

5 is a flowchart sequentially illustrating a process of generating a delay compensation signal timing signal according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: WiBro terminal 110: base station (RAS)

120: control station (ACR) 130: IP network                 

140: Internet 200: main donor module

205, 280: LNA 210, 285: E / O

215, 255: WDM 220, 260: O / E

225, 270: HPA 250: remote module

265: coupler 275: switch

290: switching timing signal generation circuit

300: Splitter 310: Level Detector

320: variable gain amplifier 330: log scale amplifier

340: pulse generator 350: comparator

360: reference pulse generator 370: phase tuning circuit

380: Timing Controller

The present invention relates to an optical repeater for signal delay delay compensation between a base station and a repeater in an OFDM-TDD type WiBro system, and a method for generating a signal timing delay compensation switching timing signal for an optical repeater. When calculating the switching timing of the optical repeater, the start timing of the downlink signal and the uplink signal from the RF signal received at the remote module through the main donor module of the optical repeater with the delay time according to the optical cable length between the base station and the optical repeater remote module. OFDM-TDD scheme that detects and forwards the start timing of the detected uplink signal by twice the delay time to the optical repeater remote module switch to prevent degradation of service quality or service interruption caused by signal transmission delay Base station and optical repeater in WiBro systems It relates to an optical repeater and a signal propagation delay time compensation switching timing signal generating method of the optical repeater for the signal propagation delay time compensation.

In general, a mobile communication system uses an optical repeater to solve the shading of radio waves in a radio shading area such as the basement, the inside of a building, and a tunnel, where radio waves are difficult to reach. The problem of radio wave shading is solved by transmitting to a radio wave shading area through a light transmission method using a repeater.

In particular, 2.5G (2.5G), PCS (PCS), and 3G (CG) CDMA2000 series systems, WCDMA systems, and WiBro systems use higher frequencies than 2G mobile communication systems. It is preferable to use an optical repeater because the radius of the cell is small because it is large, the diffraction effect is small, and the building transmission loss is large.

The optical repeater must be able to distinguish the downlink signal and the uplink signal in order to relay the radio signal between the base station and the terminal. When the FDD method is used in the optical repeater, the duplexer distinguishes the downlink signal and the uplink signal.

Recently, a portable Internet system (hereinafter referred to as WiBro system), which guarantees portability and mobility, and provides high-speed wireless Internet service at a low price, has emerged. Such a WiBro system is a duplex method using TDD (Time). Division Duplex (DM) scheme is used, and Orthogonal Frequency Division Multiplexing (OFDM) scheme is used as a modulation scheme.

The TDD scheme is a bidirectional transmission scheme in which uplinks and downlinks are alternately assigned in time in the same frequency band, and is more efficient than the frequency division duplex (FDD) scheme in which two different frequencies are allocated to the uplink and the downlink. This high, time slot dynamic allocation makes it an ideal choice for asymmetric or bursty application transfers.

In addition, the OFDM scheme is a digital modulation scheme for improving transmission rate per bandwidth and preventing multipath interference. Since the OFDM scheme has orthogonality between subcarriers, it has excellent characteristics in multipath fading. By adaptively adjusting the data rate for each subcarrier according to the signal-to-noise ratio, the transmission capacity can be greatly improved, and it is strong against narrowband interference.

In the OFDM-TDD type WiBro system, the same frequency is used for transmission of the downlink and uplink signals, and a time period is divided to distinguish the downlink and uplink signals, and thus a duplexer cannot be used for signal separation. . Accordingly, an optical repeater using a TDD scheme may use a switch to distinguish the downlink signal from the uplink signal and provide a path for each signal selectively. For this purpose, the starting point of the downlink signal and the starting point of the uplink signal may be precisely determined. The control signal is required to determine and adjust the movement path of the signal by adjusting the opening and closing of the switch according to each signal, and the optical repeater may receive the above-described control signal from the base station through the optical cable.

However, in general, since the manufacturers of the base station and the optical repeater are often different from each other, an additional cost is incurred because an additional modem must be installed in the optical repeater to receive the switch control signal transmitted from the base station. There is a problem that it is not easy to find the cause of the failure when a failure occurs. In addition, even when using a modem, a separate process of compensating the delay value of the optical cable to the control signal has to be performed, which incurs an additional cost.

Therefore, in order to use an optical repeater in a TDD-type mobile communication system, a switching timing signal must be generated in the optical repeater to distinguish a downlink signal from an uplink signal and to selectively provide a path for each signal.

On the other hand, until the signal from the base station reaches the remote module via the main donor module and the optical cable of the optical repeater, a signal propagation delay of up to 40 dB or more may occur depending on the length of the optical cable. If the switching timing signal is generated without the signal, the switching operation of the optical repeater may cause a problem, and thus the normal signal may not be relayed.

That is, the base station output signal is radiated from the base station in the downlink signal interval, and the terminal output signal is received by the base station in the uplink signal interval. The base station signal and the switching signal of the remote module provided by the base station are transmitted from the base station to the remote module of the optical repeater. The delay time according to the optical cable length D is transmitted to the optical repeater remote module, and the optical repeater remote module detects the start timing of the downlink signal section delayed by D.                         

In this case, the upstream output signals of all the terminals operating within one base station coverage must reach the base station receiving end at the base station uplink signal start timing regardless of the distance from the terminal to the base station in order to maintain orthogonality between signals at the base station receiving end.

However, if the delay time according to the optical cable length from the base station to the optical repeater remote module is not considered, the start timing of the repeater uplink signal section is delayed by D than the start time of the uplink signal section of the base station. The uplink signal reaches the antenna of the remote module of the repeater as fast as 2D than the start timing of the repeater uplink signal interval, and thus, the front part signal during 2D in time from the terminal does not pass through the repeater remote module. Will not be delivered.

Accordingly, the present invention is to solve the problems caused by the signal transmission delay of the optical repeater used in the OFDM-TDD type WiBro system, the signal transmission delay time according to the optical cable length between the base station and the optical repeater remote module In the OFDM-TDD type WiBro system for generating a switching timing signal by compensating the optical signal, an optical repeater and a signal transmission delay compensation signal generation method of the optical repeater for signal delay delay compensation between the base station and the repeater are provided. There is an object of the present invention.

The above object of the present invention uses a time division duplex (TDD) method and an orthogonal frequency division multiplexing (OFDM) method, and includes an optical relay for signal relay between a base station (RAS), a control station (ACR) and a base station and a WiBro terminal. A method of generating a switching timing signal for controlling a switch for signal separation in the optical repeater of the WiBro system, wherein, when an RF signal is transmitted from the base station to the optical repeater remote module, a part of the RF signal is extracted to extract the RF signal. A first step of determining a frame start position; Calculating a start point of a downlink signal and an uplink signal included in the RF signal based on the frame start position; A third step of compensating the signal propagation delay time by advancing the calculated starting point of the uplink signal by twice (2D) the signal propagation delay time (D) according to the optical cable length between the base station and the optical repeater remote module; A fourth step of generating a switching timing signal using the start point information of the downlink signal calculated in the second step and the start point information of the uplink signal compensated for delay in the third step and transmitting the switching timing signal to the switch of the optical repeater; And a fifth step of the switch separating and transmitting a downlink signal and an uplink signal by the switching timing signal. In the OFDM-TDD type WiBro system including a signal transmission delay time compensation switching timing signal generation method of the optical repeater.

In addition, the object of the present invention is to use the Time Division Duplex (TDD) method and Orthogonal Frequency Division Multiplexing (OFDM) method, and to the base station and WiBro terminal of a WiBro system including a base station (RAS) and a control station (ACR). Is an optical repeater which relays the RF signal transmitted from the base station to a downlink signal and an uplink signal, converts the RF signal received from the base station into an optical signal and transmits the optical signal to the remote module, and transmits the optical signal received from the remote module to the RF signal. A main donor module for converting the data into a base station; Is connected to the main donor module and the optical cable, converts the optical signal received from the main donor module to the RF signal to the WiBro terminal, and converts the RF signal received from the WiBro terminal to the optical signal to the main donor module A remote module for transmitting; A part of the RF signal transmitted from the main donor module to the remote module is extracted to correlate the generated reference signal with the extracted RF signal, and the result is analyzed to start the frame of the extracted RF signal. Determine a position, calculate starting points of the downlink signal and the uplink signal included in the extracted RF signal based on the frame start position, and determine the starting point of the calculated uplink signal to the optical cable length between the base station and the optical repeater remote module. Compensate for the signal propagation delay by advancing by twice (2D) the signal propagation delay time (D), thereby generating a switching timing signal using the calculated start point information of the downlink signal and the start point information of the uplink signal compensated for the signal propagation delay. Switching timing signal generating circuit for transmitting the switch to the switch of the remote module; In the OFDM-TDD type WiBro system comprising a optical repeater for signal delay delay compensation between the base station and the repeater.

Detailed description of the above object and technical configuration of the present invention and the effects thereof according to the present invention will be more clearly understood by the following detailed description based on the accompanying drawings.

First, Figure 1 is a block diagram of a WiBro system for explaining the present invention.

As shown, a wireless broadband (Wibro) system using a TDD scheme and an OFDM scheme includes a base station (Radio Access Station, RAS: 110) and an access control router (Access Control Router) for accessing the IP network 130. ACR 120).

The base station 110 is a mobile Internet wireless access function, wireless resource management and control function, mobility (handoff) support function, authentication and security function, QoS provision function, downlink multicast function, billing of the WiBro terminal 100 It also performs statistical information generation and notification functions.

In addition, the base station 11 has a low power RF / IF module and controller function, OFDMA / TDD packet scheduling and channel multiplexing function, MAC frame variable control function according to the service characteristics and propagation environment, 50 Mbps high-speed traffic real-time control function, hand Over function.

The control station 120 is connected to the IP network 130, IP routing and mobility management functions, authentication and security functions, QoS providing function, IP multicast function, charging service providing function to the charging server, control station in the base station It performs inter mobility control function, resource management and control function.

Here, the WiBro terminal 100 refers to a mobile communication terminal that uses a high-speed wireless Internet service by accessing a WiBro system, and according to a low power RF / Intermediate Frequency (IF) module and controller function, service characteristics, and a propagation environment. It has MAC (Media Access Control) frame variable control function, handover function, authentication and encryption function.

In addition, the WiBro terminal 100 and the base station 110 have a 50 Mbps packet transmission modulation and demodulation function, a high-speed packet channel coding function, a real-time modem control function for data transmission.

The IP network 130 tracks and connects positions of an external packet data service server such as the Internet 140 and a PDSN 131 relaying packet data transmission and reception between a base station and an external packet data service server such as the Internet 140. The AAA 133 performs charging for the packet data used in the WiBro terminal 100 in association with the PDGN 132 and the PDSN 131 which performs routing, and authenticates the connection from the WiBro terminal 100. ) And receive packet data from an external packet data service such as the Internet 140 and transmit the packet data to the base station 110.

Next, Figure 2 is an internal configuration of an optical repeater according to an embodiment of the present invention.

Since the optical repeater of the present invention uses the TDD scheme, time division of the same frequency is performed to divide the downlink signal and the uplink signal, thereby enabling bidirectional communication. Thus, the optical repeater uses the same frequency between the WiBro terminal 100 and the base station 110. To transmit the RF signal.                     

As shown, the optical repeater includes a main donor module 200 and a remote module 250.

The main donor module 200 is connected to the base station 110 through an RF cable, and when receiving the RF signal from the base station 110, converts the RF signal into an optical signal through an all-optical conversion and remotely via an optical communication cable. The optical signal is transmitted to the module 250, and the optical signal received from the remote module 250 is converted into an RF signal through photoelectric conversion and transmitted to the base station 110 through an RF cable.

When the optical module receives the optical signal from the main donor module 200, the remote module 250 converts the RF signal into an RF signal through photoelectric conversion and transmits the signal to the WiBro terminal 100 through an antenna, and receives the RF received from the WiBro terminal 100. The signal is converted into an optical signal through an all-optical conversion and transmitted to the main donor module 200 through an optical communication cable.

The main donor module 200 includes a low noise amplifier (LNA) 205, an all-optical conversion module (E / O) 210, a wavelength division multiplexer (WDM) 215, and a photoelectric conversion module (O / E) 220. And a high power amplifier (HPA) 225.

The remote module 250 includes a WDM 255, a photoelectric conversion module 260, a coupler 265, an HPA 270, a switch 275, an LNA 280, an all-optical conversion module 285, and the like. And a switching timing signal generation circuit 290.

Here, although not shown in a separate drawing, the main donor module 200 of the optical repeater may be connected to a plurality of remote modules 250 through an optical communication cable to extend the coverage of the optical repeater. 200 may include a signal divider (not shown) and a signal combiner (not shown) having multiple channels. Then, the RF signal received from the base station 110 is branched through a signal splitter to be delivered to the LNA 205 and the RF signal received from the HPA 225 is combined with the output of another remote module 250 through a signal combiner. The base station 110 may transmit the RF cable.

WDM (215, 255) is a device that divides an optical fiber channel into a plurality of channels according to the wavelength of light and can be used as a plurality of communication paths. When operating as a wavelength division multiplexer to transmit, and when receiving an optical signal, it can operate as a wavelength division demultiplexer for splitting the signals of several optical wavelengths carried in one optical fiber, respectively.

The all-optical conversion modules 210 and 285 may be implemented using a laser diode, and the photoelectric conversion modules 220 and 260 may be implemented using a photo diode.

When the switching timing signal generation circuit 290 extracts a part of the RF signal from the coupler 265, the switching timing signal generating circuit 290 generates a switching timing signal for controlling the switch by dividing the downlink signal and the uplink signal, and delivers the switching timing signal to the switch 275.

The transmission of signals in the forward and reverse channels using the components of the optical repeater will be described in detail below.

In the case of the forward channel, the RF signal transmitted from the base station 110 through the RF cable is transmitted to the LNA 205 of the main donor module 200, which reduces the noise component of the RF signal and amplifies the signal component. To the all-optical conversion module 210.                     

The all-optical conversion module 210 converts the received RF signal into an optical signal through all-optical conversion and transmits it to the WDM 215, and the WDM 215 transmits a plurality of optical signals received from the all-optical conversion module 210. Transmission to the remote module 250 via a communication cable.

The WDM 255 of the remote module 250 receiving the optical signal from the main donor module 200 branches the plurality of received optical signals to the photoelectric conversion module 260, and the photoelectric conversion module 260 transmits the photoelectric signal. The conversion converts the optical signal into an RF signal and delivers it to the HPA 270.

The HPA 270 amplifies the effective output for wirelessly transmitting the RF signal to the switch 275, and radiates the RF signal to the WiBro terminal 100 through the antenna.

In the reverse channel, when the RF signal is received from the WiBro terminal 100 through the antenna of the remote module 250, the LNA 280 removes the noise, amplifies the signal component, and transmits the signal to the all-optical conversion module 285. . The all-optical conversion module 285 converts the RF signal into an optical signal through the all-optical conversion and transmits it to the WDM 255. The WDM 255 transmits the optical signal received from the all-optical conversion module 285 through the optical communication cable. Transfer to the donor module 200.

The WDM 215 of the main donor module 200 receiving the optical signal from the remote module 250 branches the plurality of received optical signals to the photoelectric conversion module 220, and the photoelectric conversion module 220 transmits the photoelectric signal. The conversion converts the optical signal into an RF signal and forwards it to the HPA 225. The HPA 225 amplifies the effective output for transmitting the RF signal to the base station 110 and transmits the RF signal to the base station 110 through the RF cable.

On the other hand, the coupler 265 extracts a part of the RF signal transmitted from the photoelectric conversion module 260 to the HPA 270 and transfers it to the switching timing signal generation circuit 290, which is extracted from the switching timing signal generation circuit 290. The RF signal is analyzed to generate a switching timing signal for transmitting the RF signal, and then transmit the generated switching timing signal to the switch 275.

When the downlink signal is input to the switch 275, the switch 275 radiates to the WiBro terminal 100 through an antenna, and the uplink signal is input to the switch 275. In this case, the path is connected to the HPA 270 and the path is set up such that an uplink signal is input to the LNA 280.

In this case, the switching timing signal generation circuit 290 calculates the start point of the uplink signal section and the start point of the downlink signal section when generating the switching timing signal, and the optical cable length between the base station 110 and the optical repeater remote module 250. In order to compensate for the signal propagation delay time (D) according to the present invention, the start point of the calculated uplink signal interval is advanced by 2D and then a switching timing signal is generated using the same, which will be described in more detail with reference to FIGS. 3 and 4. do.

Next, FIG. 3 is an internal configuration diagram of a switching timing signal generation circuit according to an exemplary embodiment of the present invention, and FIG. 4 is a conceptual diagram illustrating a signal transfer delay time compensation operation of the switching timing signal generation circuit of FIG. 3.

As shown in FIG. 3, the switching timing signal generation circuit 290 includes a divider 300, a level detector 310, a variable gain amplifier 320, and a log. Log-Scale Amplifier 330, Pulse-Shape Generator 340, Comparator 350, Reference Pulse-Shape Generator 360, Phase Tuning Circuit Phase Tuning Circuit 370, Timing Controller 380, and the like.

A process of generating a switching timing signal using the above-described components of the switching timing signal generation circuit 290 will be described in detail below.

First, when a part of the RF signal is extracted from the coupler 265 and transmitted to the divider 300, the divider 300 distributes the RF signal to the level detector 310 and the variable gain amplifier 320. The level detector 310 measures the level of the signal and transmits the signal to the variable gain amplifier 320. The variable gain amplifier 320 receives the level value measured by the level detector 310 and outputs the variable gain amplifier 320. Keep the signal at a constant level at all times.

The logarithmic scale amplifier 330 converts the amount of change of the signal received from the variable gain amplifier 320 from the linear scale to the decibel (dB) scale and transfers it to the pulse generator 340, and the pulse generator 340 receives the input. A pulse waveform signal is generated using the received signal and transferred to the comparator 350.

The reference pulse generator 360 correlates the pulse waveform signal generated by the pulse generator 340 to generate a reference pulse waveform signal for determining a frame start position of the RF signal, and transmits the reference pulse waveform signal to the comparator 350. .                     

The comparator 350 compares the correlation between the pulse waveform signal transmitted from the pulse generator 340 and the reference pulse waveform signal transmitted from the reference pulse generator 360. That is, the comparator 350 correlates the two signals and transmits the result to the timing controller 380.

The timing controller 380 analyzes the received result to determine the frame start position of the signal extracted by the coupler 265, and calculates the start points of the downlink signal and the uplink signal based on the determined frame start position.

Here, the timing controller 380 has frame structure information of the RF signal. When the frame position of the RF signal is determined, the timing controller 380 calculates starting points of the downlink signal and the uplink signal included in the RF signal using the frame structure information. That is, one signal frame starts from the preamble, which is a signal used to synchronize the transmission timing by notifying when the data symbol starts, so the correlation result is maximized at the point where the preamble is located. Is the starting position of.

Therefore, since the structure of the frame including the uplink and the downlink is predefined, it is possible to calculate the starting point of the uplink and the downlink by calculating a predetermined time interval for each symbol included in the frame. . That is, since the frame starts from the downlink period, the starting position of the frame becomes the starting point of the downlink, and the position of the uplink is obtained by adding the interval (TTG) between the downlink and the uplink transmitted after the downlink time interval. It is a starting point.

In this case, as shown in Figure 4, the start point of the calculated downlink signal and the start point of the uplink signal is delayed by the delay time D according to the optical cable length between the base station 110 and the optical repeater remote module 250, the calculation If the start point of the upstream signal is used as it is, the upstream signal output from the terminal 100 reaches the remote module 250 as fast as the 2D start point of the calculated upstream signal, and the corresponding signal reached as quickly as 2D is a repeater. It may not pass through the remote module 250 and may not be delivered to the base station 110.

Accordingly, the timing controller 380 sets the starting point of the uplink signal interval to ensure that the previous signal lost in correspondence with twice the signal propagation delay time D reaches the base station 110 normally. The signal propagation delay time is compensated by moving 2D forward than the calculated uplink signal start point.

Thereafter, the timing controller 380 generates a switching timing signal for controlling the switch 275 by using the calculated starting point information of the downlink signal and the starting point information of the uplink signal that has been compensated for the signal transmission delay time by moving by 2D. To the switch 275.

The phase tuning circuit 370 receives phase information of the pulse waveform generated by the pulse generator 340 from the comparator 350 and tunes the phase of the reference pulse waveform.

When the switching timing signal generation circuit 290 generates the switching timing signal through the above-described process and transmits the switching timing signal to the switch 275, the switching timing signal divides the RF signal input to the switch 275 into a downlink signal and an uplink signal. When the down signal is input from the HPA 270 of the remote module 250, the switch 275 is controlled to radiate the down signal to the WiBro terminal 100 through the antenna, and the up signal is input through the antenna. The switch 275 is controlled to input an uplink signal to the LNA 280 of the remote module 250.

Accordingly, the switch 275 may selectively provide a path for each down or up signal by adjusting the short circuit of the switch 275 according to the switching timing signal, and the base station 110 and the optical repeater remote module 250 may be provided. It is possible to compensate the signal propagation delay time according to the optical cable length.

Meanwhile, the delay compensation operation will be described through transmission signal frames in the WiBro system using the TDD scheme and the OFDM modulation scheme illustrated in FIG. 4.

As shown, the transmission signal frame in the WiBro system includes a downlink (DL) frame, an uplink (UL) frame, a Tx / Rx transition gap (TGT), and an Rx / Tx transition gap (RTG). And the like.

Here, the downlink refers to a frame for the downlink signal transmitted from the base station 110 to the WiBro terminal 100 through the optical repeater, and the uplink is transmitted from the WiBro terminal 100 to the base station 110 through the optical repeater. Refers to the frame for the uplink signal.                     

The TTG and the RTG are guard times for distinguishing up and down transmission times, and do not transmit valid signals including data from the base station 110 and the WiBro terminal 100 during this interval.

The TTG refers to an interval between the downlink and the uplink transmitted subsequently. During this interval, the base station 110 is changed to a mode for receiving an uplink signal and the WiBro terminal 100 is changed to a mode for transmitting an uplink signal.

The RTG refers to an interval between an uplink and a downlink transmitted subsequently. During this interval, the base station 110 changes to a mode for transmitting a downlink signal and the WiBro terminal 100 changes to a mode for receiving a downlink signal.

The switching timing signal generation circuit 290 receives the signal (a) having the above-described frame structure (b) determines the positions of the start points of the downlink and the uplink, and calculates a predetermined time interval for each symbol on the basis of this. The start point of the downlink signal section and the start point of the uplink signal section are calculated (c). In this case, since the frame starts from the downlink period, the start position of the frame becomes the start point of the downlink, and the position where TTG is added to the downlink time interval becomes the start point of the uplink.

In this case, as shown in (b), the RF signal received by the optical repeater is a signal delayed by the signal transmission delay time D according to the optical cable length, and thus the switching timing signal generation circuit 290 uses the received signal. The starting point of the downlink signal section and the starting point of the uplink signal section calculated as described above are timings delayed by the signal transmission delay time D as shown in (c).                     

Therefore, since the uplink reception signal output from the terminal 100 will be received by the optical repeater remote module 245 by 2D faster than the start point of the uplink signal interval calculated in (c) as shown in (d), the switching timing signal. As shown in (e), the generation circuit 290 sets the starting point of the uplink signal duration calculated in (c) according to the optical cable length between the base station 110 and the optical repeater remote module 250 according to the optical cable length (D). After advance by two times (2D) of using this to generate a switching timing signal and to control the switch 275.

As a result, the start point of the uplink signal interval advanced by two times (2D) the signal propagation delay time D according to the optical cable length is compared with the start point of the uplink signal interval of the base station transmission frame of (a), (e) As shown in Fig. 2), D is advanced by the start point of the uplink signal interval of the base station transmission frame.

Accordingly, in the optical repeater, the downlink signal and the uplink signal can be distinguished and a transmission path for each signal can be selectively provided, and the signal relay delay can be compensated to perform a normal signal relay.

On the other hand, the difference between the TTG and the 2D advanced to compensate for the signal propagation delay time is the minimum physical delay time (STT) required for the switch 275 inside the optical repeater remote module 250 to switch from the down path to the up path. Of course, it should be (TTG-2D≥STT).

Finally, FIG. 5 is a flowchart sequentially illustrating a process of generating a delay time compensation switching timing signal according to an embodiment of the present invention.

As shown, when the base station 110 transmits an RF signal, the optical repeater receives the RF signal through the main donor module 200, converts the RF signal into an optical signal, and then transmits the RF signal to the remote module through the optical communication cable (S101). ).

The remote module 250 converts the received optical signal into an RF signal and transmits the converted optical signal to the WiBro terminal 100. The coupler 265 located between the photoelectric conversion module 260 of the remote module 250 and the HPA 270. A portion of the RF signal is extracted and transferred to the switching timing signal generation circuit 290 (S102).

The switching timing signal generation circuit 290 correlates the signal received from the coupler 265 and the reference signal generated by the reference pulse generator 360 of the switching timing signal generation circuit 290 to a maximum value in the waveform. Since the appearing position becomes the frame start position of the RF signal, the start position of the frame is determined by analyzing the correlation result waveform (S103).

Since the signal structure using the TDD scheme and the OFDM modulation scheme has a predefined frame structure, the switching timing signal generation circuit 290 calculates starting points of the downlink signal and the uplink signal included in the RF signal based on the frame start position (S104). ).

When the switching timing signal generation circuit 290 calculates the starting point of the downlink signal and the uplink signal, the signal transmission delay time D according to the optical cable length between the base station 110 and the optical repeater remote module 250 is determined. Compensating the signal propagation delay time by advancing by 2 times (2D) (S105), and switching timing for distinguishing the downlink signal from the uplink signal using the compensated uplink signal starting point information and the downlink signal starting point information calculated in step S104. The signal is generated and transmitted to the switch 275 (S106).

In this case, the time difference of 2D advanced to compensate for the TTG and the signal propagation delay time is the minimum physical delay time (STT) required for the switch 275 in the optical repeater remote module 250 to switch from the down path to the up path. Of course, it should be more than (TTG-2D≥STT).

When the switching timing signal is transmitted to the switch 275, the switch 275 distinguishes the downlink signal and the uplink signal by the switching timing signal, and selectively adjusts the short circuit of the switch to provide a path for each signal. (S107).

Accordingly, the optical repeater prevents the downlink signal and the uplink signal from interfering with the switching timing signal, and transmits the downlink signal to the WiBro terminal 100 and transmits the uplink signal to the base station 110 in the uplink signal. In the case of the signal transmission delay time according to the optical cable length between the base station 110 and the optical repeater remote module 250 to compensate for the transmission signal between the WiBro terminal 100 and the base station 110 normally without the effect of the time delay phenomenon Done.

As those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features, the embodiments described above should be understood as illustrative and not restrictive in all aspects. Should be. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Accordingly, the method and system for generating a delay time compensation switching timing signal in an optical repeater of a WiBro network using the TDD scheme and the OFDM modulation scheme of the present invention, the optical repeater distinguishes the downlink signal and the uplink signal and selects a path for each signal. By generating a switching timing signal that can be provided as a signal, by compensating the signal transmission delay time according to the optical cable length between the base station and the optical repeater remote module to generate the switching timing signal, the optical repeater in the WiBro system stable operation In addition, the service quality can be prevented from occurring due to the signal transmission delay between the base station and the optical repeater or the service interruption, thereby providing a high quality service.

Claims (21)

The optical of the WiBro system using a Time Division Duplex (TDD) method and an Orthogonal Frequency Division Multiplexing (OFDM) method, and including an optical base station (RAS), a control station (ACR), and an optical repeater for signal relay between the base station and the WiBro terminal. A method of generating a switching timing signal for controlling a switch for signal separation in a repeater, When the RF signal is received from the base station in the main donor module of the optical repeater and the RF signal is transmitted to the optical repeater remote module, the optical repeater extracts a portion of the RF signal to determine a frame start position of the RF signal. A first step; A second step of the optical repeater calculating starting points of a downlink signal and an uplink signal included in the RF signal based on the frame start position; A third step in which the optical repeater compensates the signal propagation delay time by advancing the start point of the calculated uplink signal by twice (2D) the signal propagation delay time D according to the optical cable length between the base station and the optical repeater remote module. Wow; The optical repeater generates a switching timing signal using starting point information of the downlink signal calculated in the second step and starting point information of the uplink signal compensated for the delay time in the third step, and transmits the switching timing signal to the switch of the optical repeater remote module. The fourth step; And A fifth step of the switch separating and transmitting a downlink signal and an uplink signal by the switching timing signal; The signal transmission delay time compensation switching timing signal generation method of the optical repeater in an OFDM-TDD type WiBro system comprising a. The method of claim 1, The first step is, Transmitting an RF signal transmitted from the base station to the optical repeater remote module in the main donor module of the optical repeater; Extracting a portion of the RF signal from a coupler of the remote module and transferring the portion of the RF signal to a switching timing signal generation circuit of the optical repeater remote module; Correlating, by the switching timing signal generation circuit, the RF signal extracted by the coupler and a reference signal generated by the switching timing signal generation circuit; Analyzing the correlation result in the switching timing signal generation circuit to determine a frame start position of the RF signal; The signal transmission delay time compensation switching timing signal generation method of the optical repeater in the OFDM-TDD type WiBro system, characterized in that comprises a. The method of claim 2, Determining the frame start position of the RF signal by analyzing the correlation result value, And analyzing the correlation result value in the switching timing signal generation circuit to determine a position at which the correlation result value is the maximum as a frame start position of the RF signal. Signaling delay time compensation switching timing signal generation method. The method of claim 1, In the fifth step, The switch radiates the downlink signal to the WiBro terminal when the downlink signal is input by the switching timing signal, and blocks a path connected to the high power amplifier (HPA) of the remote module when the uplink signal is input. And setting a path such that the upstream signal is input to a low noise amplifier (LNA) of a remote module. The method of claim 1, The frame of the RF signal, Signaling delay compensation switching timing of an optical repeater in an OFDM-TDD type WiBro system comprising a downlink frame, an uplink frame, a Tx / Rx transition gap, and an RTG (Rx / Tx transition gap) Signal generation method. The method of claim 5, The downlink is a frame for the downlink signal transmitted from the base station to the WiBro terminal through the optical repeater, and the uplink is a frame for the uplink signal transmitted from the WiBro terminal to the base station through the optical repeater. A signal transmission delay time compensation switching timing signal generation method of an optical repeater in an OFDM-TDD WiBro system. The method of claim 5, The TTG is a guard time for distinguishing a transmission time of the downlink and the uplink by an interval between the downlink and the uplink transmitted subsequently, and the base station receives the uplink signal during the TTG. The signal transmission delay time compensation switching timing signal generation method of the optical repeater in the OFDM-TDD type WiBro system, characterized in that is changed to, and the WiBro terminal is a mode for transmitting an uplink signal. The method of claim 5, The RTG is a guard time for distinguishing the transmission time of the uplink and the downlink at intervals between the uplink and the downlink transmitted subsequently. During the RTG, the base station transmits a downlink signal. The signal transmission delay time compensation switching timing signal generation method of the optical repeater in the OFDM-TDD type WiBro system, characterized in that the mode is changed, the WiBro terminal is changed to a mode for receiving a downlink signal. 9. The method according to claim 7 or 8, The signal transmission delay time compensation switching timing signal generation method of the optical repeater in the OFDM-TDD type WiBro system, characterized in that the base station and the WiBro terminal does not transmit a valid signal during the TTG or RTG. The method of claim 5, The second step, The start position of the frame is determined as the start point of the downlink, the position where the TTG is added to the downlink time interval is determined as the start point of the uplink, and the start point of the downlink is set as the start point of the downlink signal. And a signal transmission delay time compensation switching timing signal generation method of an optical repeater in an OFDM-TDD type WiBro system, wherein the start point of the uplink is set as a start point of the uplink signal. It uses a time division duplex (TDD) method and an orthogonal frequency division multiplexing (OFDM) method. The RF signal transmitted from the base station and the WiBro terminal of the WiBro system including a base station (RAS) and a control station (ACR) It is an optical repeater which is relayed by the uplink signal. A main donor module converting the RF signal received from the base station into an optical signal and transmitting the optical signal to the remote module, and converting the optical signal received from the remote module into an RF signal and transmitting the RF signal to the base station; Is connected to the main donor module and the optical cable, converts the optical signal received from the main donor module to the RF signal to the WiBro terminal, and converts the RF signal received from the WiBro terminal to the optical signal to the main donor module A remote module for transmitting; A part of the RF signal transmitted from the main donor module to the remote module is extracted to correlate the generated reference signal with the extracted RF signal, and the result is analyzed to start the frame of the extracted RF signal. Determine a position, calculate starting points of the downlink signal and the uplink signal included in the extracted RF signal based on the frame start position, and determine the starting point of the calculated uplink signal to the optical cable length between the base station and the optical repeater remote module. Compensate for the signal propagation delay by advancing by twice (2D) the signal propagation delay time (D), thereby generating a switching timing signal using the calculated start point information of the downlink signal and the start point information of the uplink signal compensated for the signal propagation delay. Switching timing signal generation circuit for transmitting to the switch of the remote module; Optical repeater for the signal transmission delay time compensation between the base station and the repeater in the OFDM-TDD type WiBro system comprising a. The method of claim 11, The main donor module of the optical repeater, An optical repeater for transmitting a signal transmission delay between the base station and the repeater in an OFDM-TDD type WiBro system, characterized in that the RF signal is transmitted to the base station through an RF cable, and the RF signal is received from the base station. The method of claim 11, The main donor module, Signal transmission delay between the base station and the repeater in an OFDM-TDD type WiBro system comprising a low noise amplifier (LNA), an all-optical conversion module, a wavelength division multiplexer (WDM), a photoelectric conversion module, and a high power amplifier (HPA) Optical repeater for time compensation. The method of claim 13, The main donor module, An optical repeater for compensating signal transmission delay time between a base station and a repeater in an OFDM-TDD type WiBro system, characterized in that connected to a plurality of optical repeater remote module via an optical cable. The method of claim 14, The main donor module, An optical repeater for compensating signal transmission delay time between a base station and a repeater in an OFDM-TDD type WiBro system comprising a signal splitter and a signal combiner having multiple channels. The method of claim 11, The remote module, Signal between base station and repeater in OFDM-TDD type WiBro system, comprising Wavelength Division Multiplexer (WDM), photoelectric conversion module, high power amplifier (HPA), switch, low noise amplifier (LNA) and all-optical conversion module Optical repeater for propagation delay compensation. The method of claim 16, The remote module, A coupler positioned between the photoelectric conversion module and the HPA and extracting a portion of the RF signal transmitted from the photoelectric conversion module to the HPA to the switching timing signal generation circuit; The optical repeater for the signal transmission delay time compensation between the base station and the repeater in the OFDM-TDD type WiBro system further comprising. The method of claim 17, The switching timing signal generation circuit, Compensating the signal transmission delay time between the base station and the repeater in the OFDM-TDD type WiBro system, characterized in that located in the remote module receives the RF signal extracted from the coupler to generate a switching timing signal to the switch Optical repeater. The method of claim 11, The switching timing signal generation circuit, When the coupler included in the remote module extracts a part of the RF signal transmitted from the main donor module to the remote module, the extracted RF signal is received and a level detector and a variable gain amplifier (VGA) are received. Divider for dispensing; A level detector for measuring a level of the extracted RF signal distributed from the distributor and transferring the level to the variable gain amplifier; A variable gain amplifier receiving the level value measured by the level detector and maintaining the extracted RF signal at a constant level; A log-scale amplifier for converting the amount of change of the extracted RF signal received from the variable gain amplifier from a linear scale to a decibel (dB) scale and transferring it to a pulse-shape generator; A pulse generator for generating a pulse waveform signal using the extracted RF signal received from the logarithmic scale amplifier and transferring the pulse waveform signal to a comparator; A reference pulse generator configured to correlate the pulse waveform signal generated by the pulse generator to generate a reference pulse waveform signal for determining a frame start position of the extracted RF signal and to transmit the reference pulse waveform signal to the comparator; A comparator for correlating the signals received from the pulse generator and the reference pulse generator and transferring the result values to a timing controller; The frame start position of the extracted RF signal is determined by analyzing the result value received from the comparator, and the start points of the downlink signal and the uplink signal included in the extracted RF signal are calculated based on the determined frame start position. Compensating the delay time by advancing the calculated starting point of the uplink signal by twice (2D) the signal propagation delay time D according to the optical cable length between the base station and the optical repeater remote module, and starting point of the calculated downlink signal. A timing controller configured to generate a switching timing signal using information and starting point information of the delay time-compensated uplink signal and to transmit the switching timing signal to a switch of the remote module; And A phase tuning circuit receiving phase information of the pulse waveform signal generated by the pulse generator from the comparator and tuning the phase of the reference pulse waveform signal; Optical repeater for the signal transmission delay time compensation between the base station and the repeater in the OFDM-TDD type WiBro system comprising a. The method of claim 19, The timing controller, The signal transmission delay time between the base station and the repeater in the OFDM-TDD type WiBro system, characterized in that the correlation result is determined to determine the maximum position of the correlation result as the frame start position of the extracted RF signal. Optical repeater for compensation. The method of claim 19, The switching timing signal is, The RF signal input to the switch is divided into a downlink signal and an uplink signal, and when a downlink signal is input from a high power amplifier (HPA) of the remote module, the downlink signal is radiated to the wibro terminal through an antenna. When the upstream signal is input through the antenna, the switch controls the switch so that the upstream signal is input to a low noise amplifier (LNA) of the remote module. An optical repeater for compensating signal propagation delay time between a base station and a repeater.

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