KR100347053B1 - High speed and long distance transmission apparatus for exchange system - Google Patents

Abstract

In a switching system, a high speed long distance transmission device between racks is disclosed. In the switching system according to the present invention, a high-speed long-distance transmission device between racks includes a signal compensating unit for amplifying a transmission signal to be transmitted to an opposite rack through a transmission medium, and compensating for attenuation and dispersion of the amplified transmission signal and transmitting it to the transmission medium; And a signal reproducing unit for reproducing the signal transmitted from the transmission medium unit in the form of a signal used in the communication exchange system, and attenuating the transmission signal generated in the transmission process before transmitting the transmission signal through the transmission medium; By compensating for dispersion in advance, high-speed, long distance transmission between racks is possible while using a transmission medium for transmitting electrical signals.

Description

High speed and long distance transmission apparatus for exchange system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exchange system, and more particularly, to an inter-rack high speed long distance transmission apparatus enabling high speed long distance transmission of signals transmitted between racks constituting an exchange system.

In general, a transmission technology applied to a communication system is very diverse, such as a technology applied to a printed circuit board, a technology applied to a connector, a technology applied to a rack or systems that are separated from each other.

At this time, among the technologies used between the racks or communication systems that are separated from each other there is a technology for transmitting as an electrical signal and a transmission technology using an optical cable. At this time, the transmission using the optical cable is mainly used when transmitting a distance of more than hundreds of meters to several tens of kilometers, and the electrical signal transmission is used when transmitting a distance of about several tens of meters.

Therefore, the signal transmission between the racks, which are usually located at a distance of several tens of meters, transmits an electrical signal. As such, a transmission medium called a balanced impedance cable is used to transmit electrical signals between racks, and typically, a twin-ax cable is used. In this case, the twin ax cable can transmit a differential mode signal transmitted between racks up to 15 m at a transmission speed of 250 Mbps and a bit error rate (BER) of 2 ^-10 or less. In other words, the twin-ax cables currently used for signal transmission between racks are considered the most suitable transmission medium for differential mode signal transmission of the system. However, the maximum transmission power of the twinax cable is not the limit to transmit at 250Mbps bit error rate (BER) to 2 ^to-10 15m or less.

Recently, high-speed large-capacity switching systems require signal transmission between racks of more than 30m at 250Mbps and more than 10m at 1Gbps, with bit error rates below 2 ^-12 , and these conditions are beyond the transmission capability of twin-ax cables. Therefore, at present, twin ax cables are not suitable for rack-to-rack signal transmission of ultra-high-capacity high-capacity switching system, and attempt to use optical cables capable of long-distance transmission instead of twin ax cables.

However, in order to use the optical cable, it is necessary to separately use components for optical transmission, and in this case, it is unreasonable to use the optical cable because the cost is high. In addition, consideration should be given to optical transmission from the design stage of the exchange system, and there is a problem in that the exchange system should be manufactured in a form suitable for optical transmission.

An object of the present invention is to provide a high-speed long-range device capable of high-speed long-distance transmission while still using a transmission medium for transmitting electrical signals between racks in an exchange system.

Another object of the present invention is to provide a signal compensation device for compensating for attenuation and dispersion of a transmission signal by a transmission medium for transmitting an electrical signal in an exchange system.

1 is a view showing a schematic configuration of the rear of the rack in the exchange system.

2 is a block diagram schematically illustrating a high speed long distance transmission apparatus between racks according to the present invention.

3 is a diagram illustrating a state where a high speed long distance transmission apparatus between racks illustrated in FIG. 2 is applied to an exchange system.

FIG. 4 is a circuit diagram specifically illustrating a high speed long distance transmission apparatus between racks illustrated in FIG. 2.

5A to 5E are diagrams illustrating eye patterns of signals transmitted by a twin ax cable when the high-speed long distance transmission apparatus between racks according to the present invention is applied or not.

In order to achieve the above object, the rack-to-rack long-distance transmission apparatus according to the present invention that enables high-speed long-distance transmission between the rack connected via a transmission medium for transmitting electrical signals in the exchange system is a transmission signal to be transmitted to the other rack through the transmission medium And a signal compensator for compensating attenuation and dispersion of the amplified transmission signal and transmitting the signal to the transmission medium and reproducing the signal transmitted from the transmission medium in the form of a signal used in an exchange system.

In order to achieve the above another object, the signal compensation device according to the present invention for compensating for the attenuation and dispersion of the transmission signal by the transmission medium for transmitting the electrical signal between the rack in the switching system is a transmission signal to be transmitted to the other rack through the transmission medium And a signal equalizer for compensating attenuation and dispersion due to a propagation difference and a transmission distance between the high frequency component and the low frequency component of the signal amplified by the signal amplifying unit, and transmitting the compensated signal to the transmission medium.

Hereinafter, with reference to the accompanying drawings, a high-speed rack long distance transmission apparatus according to the present invention will be described as follows.

1 shows a schematic configuration of the rear of a rack in an exchange system, with a functional board 10, a female connector 12, a backplane 16, mounted connectors 14a and 14b and one side connector of a twin ax cable. (18a, 18b) is shown, respectively.

Referring to FIG. 1, the function board 10 is shown connected to the female connector 12. Here, the function board 10 is a board for implementing various functions of the exchange system. In addition, the mounted connectors 14a and 14b are connected around the backplane 16, respectively. Then, the mounted connector 14a is connected to the female connector 12, and one side connector 18a, 18b of the twin ax cable is connected to the mounted connector 14b to configure the rear of the rack in the exchange system. In addition, although not shown, the other connector of the twin ax cable is connected to the other rack, the communication between the rack is made through the twin ax cable.

At this time, referring to FIG. 1, each of the connectors 18a and 18b of the twin ax cable is a coaxial cable 8a for transmitting data to the opposite rack and a coaxial cable for receiving data from the opposite rack. (8b) is a pair. Also, although not shown, each coaxial cable consists of two leads for transmission of a differential mode signal. Here, the differential mode signal is a general form of the signal transmitted between the racks. That is, an error may occur while a signal is transmitted through the coaxial cable, and in order to facilitate recovery of an error generated during transmission in the opposite rack, a differential mode signal in which phases are reversed from each other is used.

On the other hand, the signal transmitted through the twin ax cable (18a, 18b) in the switching system is a high frequency component and a low frequency component is present together. At this time, the larger the difference between these high frequency and low frequency components, and the longer the transmission distance, the more attenuation and dispersion occurs due to the interaction between the two components. As such, if a lot of attenuation and dispersion occurs during transmission, the eye pattern characteristic of the digital signal is deteriorated. Here, the eye pattern characteristic is a characteristic most used for digital signal transmission performance analysis. If the opening portion of the eye pattern is small, it may be determined that the transmission performance is not good.

Twin maximum transmission power of the ax cable (18a, 18b) as described above is to transmit at 250Mbps bit error rate (BER) to 2 ^to-10 15m or less. However, the ultra-high-capacity large-scale switching system requires a transmission capacity of 30m or more at 250Mbps and 10m or more at 1Gbps with a bit error rate of 2 ^-12 or less. In this case of high speed and long distance signal transmission, the attenuation and dispersion generated in the twin ax cables 18a and 18b are further increased. Therefore, it is difficult to use twin ax cables 18a and 18b in an ultra-high speed mass exchange system.

However, if the attenuation and dispersion of the transmission signal by the twin ax cables 18a and 18b are compensated in advance during the high speed long distance transmission, the high speed long distance transmission may be possible while using the twin ax cables 18a and 18b.

That is, the twin ax cable is connected between the mounted connector 14b and the twin ax cable 18a and 18b by modularizing a device capable of compensating for attenuation and dispersion of the transmission signal by the twin ax cables 18a and 18b. Attenuation and dispersion of (18a, 18b) can be compensated for. Therefore, high speed long distance transmission is possible while using twin ax cables 18a and 18b.

FIG. 2 is a block diagram schematically illustrating a high speed long distance transmission apparatus between racks according to the present invention that enables high speed long distance transmission between racks by compensating for attenuation and dispersion of a transmission signal by a twin ax cable. The high-speed, long-distance transmission apparatus between racks according to the present invention includes first and second connectors 20 and 28, a signal compensator 30, and a signal regenerator 26.

Referring to FIG. 2, the first connector 20 is connected to the mounted connector 14b shown in FIG. 1, and the second connector 28 is respectively connected to the twin ax cables 18a and 18b shown in FIG. The connectors are connected.

The signal compensator 30 amplifies a transmission signal transmitted from the Tx terminal of the first connector 20, compensates for the attenuation and dispersion of the amplified transmission signal, and is connected to the Tx terminal of the second connector 28. Transmission on the twin ax cables 18a and 18b. Here, the transmission signal is a standard emitter coupled logic (ECL) signal to be transmitted to the opposite rack via the twin ax cables 18a and 18b, and is a differential mode signal as described above. That is, the attenuation and dispersion of the transmission signal generated in the signal transmission process is compensated in advance through the signal compensation unit 30, and then transmitted to the opposite rack, thereby enabling high speed long distance transmission. Preferably, the signal compensator 30 includes a signal amplifier 22 and a signal equalizer 24.

The signal amplifier 22 voltage amplifies the transmission signal transmitted from the Tx terminal of the first connector 20. That is, since the standard ECL signal, which is a transmission signal, is a signal having a low voltage level, it is disadvantageous for long distance transmission. Therefore, the signal amplifier 22 voltage amplifies the long distance transmission of the standard ECL signal.

The signal equalizer 24 compensates for the difference between the propagation of the high frequency and low frequency components of the signal amplified by the signal amplifier 22 and the attenuation and dispersion caused by the long distance transmission. Occurs with Tx terminal. Accordingly, as the twin ax cables 18a and 18b connected to the Tx terminal of the second connector 28, the signal equalizing unit 24 compensates for the attenuation and dispersion occurring in the twin ax cables 18a and 18b. Is sent.

Subsequently, the signal reproducing section 26 reproduces the signal transmitted from the twin ax cables 18a and 18b through the Rx terminal of the second connector 28 as a standard ECL signal used in the exchange system, and the first connector ( Transmit to Rx terminal of 20). Therefore, the standard ECL signal is transmitted to the mounted connector 14b connected to the Rx terminal of the first connector 20.

That is, the twin ax cables 18a and 18b are connected by modularizing the high speed long distance transmission device between the racks shown in FIG. 2 and connecting the mounted connectors 14b and the twin ax cables 18a and 18b shown in FIG. High speed long distance transmission between racks is possible.

3 is a diagram illustrating a state where a high speed long distance transmission apparatus between racks illustrated in FIG. 2 is applied to an exchange system. As shown in Figure 3 by connecting the high-speed long-distance transmission device between the rack 46, 48 according to the present invention between the twin ax cable 40a, 40b and the racks 42, 44, respectively, high-speed long-distance transmission between the rack This becomes possible.

FIG. 4 is a circuit diagram specifically illustrating a high speed long distance transmission apparatus between racks illustrated in FIG. 2.

Referring to FIG. 4, the signal amplifier 22 may be implemented with an amplifier 100, resistors R1 to R5, and capacitors C1 and C2.

The amplifier 100 amplifies a differential mode transmission signal transmitted from the Txout + / Txout− terminals of the first connector 20. At this time, the amplifier 100 may be implemented as a coaxial cable driving element such as MC100EL89. In addition, the resistors R1 to R5 and the capacitors C1 and C2 filter out noise present in the power supply voltages V _EE1 and V _EE2 applied to drive the amplifier 100.

Subsequently, the signal equalizer 24 may be implemented by the first and second equalizers 122 and 124. Here, the first equalizer 122 may be implemented with resistors R6 and capacitors C3 and C6, and the second equalizer 124 may be implemented with resistors R7 and capacitors C4 and C5. At this time, the magnitudes of the resistors R6 and R7 and the capacitors C3 to C6 constituting the first and second equalizers 122 and 124 may include a high frequency bandwidth F _eql corresponding to a transmission distance and a transmission speed. Each may be determined according to the low frequency bandwidth F _eql . First, the size of the resistor R6 in the first equalizer 122 may be determined by Equation 1 below.

Here, F _eqh represents a high frequency bandwidth for which equalization is required, C _i represents an entire line capacitor applied to the first equalizer 122, and R _i represents an entire line resistance applied to the first equalizer 122. Represent each.

In addition, in the first equalizer 122 Therefore, when the size of the resistor R6 is determined in Equation 1, the size of the capacitor C3 may be determined by Equation 2 below.

In addition, the size of the capacitor C6, which is a decoupling capacitor, may be determined by Equation 3 below.

Here, _{Ferl (3db)} represents the 3 dB point of the low frequency bandwidth F _eql where equalization is required, and Z represents the line impedance of the twin axial cable, respectively.

Subsequently, the resistors R7, capacitors C5 and capacitors C4 of the second equalizer 124 are connected to the resistors R6, capacitor C3 and capacitor C6 of the first equalizer 122, respectively. It's back. Accordingly, the sizes of the resistors R7, the capacitors C5, and the capacitors C4 constituting the second equalizer 124 may also be obtained using the first through third equations.

For example, when the transmission rate is 250 Mbps and the transmission distance is 30 m, the high frequency bandwidth F _eqh that requires equalization is _{35 MHz} , and the low frequency bandwidth F _eql that requires equalization is 180 KHz. If the characteristic impedance of the twin ax cable is 50 Ω, R _i is about 49.426 Ω and C _i is 4.38 pF / meter when the transmission speed is 250 Mbps. In addition, if the characteristic impedance of the twin-ax cable is 50Ω, when the transmission rate is 1Gbps, R _i is about 49.254Ω, and C _i is considered to be 3.35pF / meter. Accordingly, the resistors R6 and R7 of the first and second equalizers 122 and 124 are each determined to be 71.41 Ω by Equation 1, and each of the capacitors C3 and C5 is 90.94 pF by Equation 2. The capacitors C6 and C4 are each determined to be 10.32nF by Equation 3. Since the actual circuit implementation requires the use of standard resistors and capacitors, the resistors R6 and R7 use 75Ω, the capacitors C3 and C5 use 100pF, and the capacitors C6 and C4 use 10nF. The first and second equalizers 122 and 124 may be implemented using the same.

In Table 1, the standard sizes of the resistors R6 and R7 and the capacitors C3 and C5 used in the first and second equalizers 122 and 124 for each transmission speed and transmission distance are obtained by Equations 1 and 2. Results are shown.

Transmission length (meter) Baud rate (Mbps) F _eqh (MHz) F _eql (KHz) R6, R7 (Ω) C3, C5 (pF) 30 250 35 180 75 100 30 1000 250 60 330 10 50 250 65 90 200 47 5 1000 180 220 50 22

Subsequently, the signal regeneration unit 26 may be implemented as the amplifier 140, the resistors R8 to R11, and the capacitors C7 to C11, respectively. The amplifier 140 amplifies the signal transmitted from the twin coaxial cable through the Rxin + / Rxin-terminal of the second connector 28 to reproduce the standard ECL signal used in the exchange system. At this time, the amplifier 140 may be implemented with a device such as MC100E416. In addition, the resistors R8 to R11 and the capacitors C7 to C9 filter noise present in the power supply voltages V _EE1 and V _EE2 applied to drive the amplifier 140.

As described above, the high-speed long-distance transmission apparatus between racks according to the present invention enables the high-speed long-distance transmission by the signal compensation unit 30 compensates for the attenuation and dispersion of the transmission signal by the twin ax cable.

5A to 5E are diagrams illustrating eye patterns of signals transmitted by a twin ax cable when the high-speed long distance transmission apparatus between racks according to the present invention is applied or not. FIG. 5A shows an eye pattern after transmitting a signal having a transmission rate of 250 Mbps for 5 m, and FIG. 5B shows an eye pattern after transmitting a signal having a transmission rate of 250 Mbps for 30 m. 5C shows an eye pattern after amplifying the transmission signal by the amplifier 100, and FIG. 5D shows a 30m transmission signal whose attenuation and dispersion are compensated by the amplifier 100 and the signal equalizer 24. FIG. Represents the eye pattern after transmission. 5E is a diagram showing an eye pattern after the signal shown in FIG. 5D is reproduced by the signal reproducing section 26 as a standard ECL signal.

5A and 5B, when the transmission distance is 5m, since there are many open portions of the eye pattern, the signal quality is excellent. However, when the transmission distance is 30m it can be seen that the open portion of the eye pattern is small and difficult to be recognized as a normal signal. In other words, when the attenuation and dispersion of the transmission signal are not compensated in the related art, the signal quality is excellent in the short distance transmission, but the signal quality is poor in the long distance transmission.

Referring to FIGS. 5C and 5D, if the amplification unit 100 amplifies as shown in FIG. 5C before transmitting the transmission signal, and transmits the number 30m that compensates for attenuation and dispersion through the signal equalizer 24, FIG. You can get an eye pattern like 5d. That is, it can be seen that the signal quality is excellent even when the long distance transmission of 30m.

In addition, FIG. 5E is a result of reproducing the 30m long-distance transmitted signal shown in FIG. 5D into a standard ECL signal of a differential mode used in an exchange system through the signal reproducing section 26 of the apparatus shown in FIG. It seems to play perfectly.

That is, conventionally, when a long distance transmission is performed using a twin ax cable, it becomes difficult to be recognized as a normal signal as shown in FIG. 5B. However, if the attenuation and dispersion of the transmission signal is compensated in advance as in the present invention, a signal having excellent quality can be obtained even when a long distance transmission is performed using a twin ax cable as shown in FIG. 5D. Also, as a result of reproducing the transmitted signal, the standard ECL signal of the differential mode can be perfectly reproduced as shown in FIG. 5E.

As described above, in the communication system according to the present invention, the high-speed long-distance transmission device between racks compensates for the attenuation and dispersion of the transmission signal generated in the transmission process before the transmission signal is transmitted through the twin ax cable, thereby reducing the twin access cable. High speed long distance transmission between racks is possible.

Claims (8)

A high speed long distance transmission device between racks connected through a transmission medium for transmitting electrical signals in an exchange system, A signal amplifier for amplifying a transmission signal of a differential mode to be transmitted to the opposite rack through the transmission medium into a differential signal having a predetermined size; A signal equalizer for compensating attenuation and dispersion due to propagation differences and transmission distances of the high frequency and low frequency components of the signal amplified by the signal amplifier, and transmitting the compensated signal to the transmission medium; And And a signal reproducing section for reproducing a signal transmitted from the transmission medium section in the form of a predetermined standard signal used in the switching system. The apparatus of claim 1, wherein the signal used in the switching system is a standard emitter coupled logic (ECL) signal. The apparatus of claim 1, wherein the signal compensator compensates for the attenuation and dispersion in accordance with a transmission speed and a length of the transmission medium. delete delete delete delete The signal equalizer of claim 1, wherein the signal equalizer A resistor having one side connected to the amplified transmission signal; A first capacitor connected in parallel with the resistor; And And a second capacitor having one side connected to the other side of the resistor and the other side connected to the transmission medium.