KR20000007454A - Bit error rate improving and burst synchronizing method using fec when combining asynchronous transfer mode network with satellite network - Google Patents

Abstract

PURPOSE: A burst synchronizing method is provided to improve the performance of a system demanding for a high-speed service such as a multimedia service by quickly obtaining the TDMA synchronization. CONSTITUTION: The burst synchronizing method comprises the steps of: correcting a single bit error by using HEC within the header of an ATM cell at the transmitting terminal of an ATM network (10) and detecting a multi bit error; inserting the FEC into the place where the HEC is removed; transmitting the ATM cell newly made by inserting the FEC onto a wireless transmitting route through a satellite(22); receiving the ATM cell in the receiving terminal of remote stations(23,24); performing the bit error correction and detection by using the FEC within the header of the ATM cell.

Description

Bit Error Rate Enhancement and Burst Synchronization Method Using FP in Asynchronous Transmission Mode Network and Satellite Network

The present invention provides a header error control (Header Error Control) present in the ATM cell header when combining an asynchronous transfer mode (hereinafter, referred to as 'ATM') network and a satellite network. Bit Error Rate (hereinafter referred to as BER) by inserting stronger Forward Error Correction (hereinafter referred to as 'FEC') instead of 'to correct' errors in the ATM header. And an ATM network to improve TDMA synchronization characteristics in a satellite network to which a Time Division Multiple Access (TDMA) scheme is applied using the FEC. The present invention relates to a BER enhancement and burst synchronization method using FEC when combining satellite networks.

In the case of a communication service system serving the world, such as an International Mobile Telecommunication (IMT) -2000 system based on an ATM network, a satellite network or a wireless network is used to connect the world.

That is, the ATM network proposed for various multimedia personal communication is combined with a satellite network or a wireless network to provide a high speed service such as a multimedia service.

1 is a diagram illustrating a combined state of an ATM network and a satellite network, wherein ATM cells of the ATM network 10 are connected to each remote station via a satellite 22 at a central station 21 of a satellite network through a radio frame. Send / receive to (Remote Station) (23, 24).

ATM cells in the ATM network 10 have a standardized HEC in the ITU-T or ATM Forum, which is present in the ATM cell header to correct a single bit error and Multiple Bit) error is detected to prevent incorrect function execution caused by header error.

For example, if we describe the HEC function if we have received R (x) and assume that the HEC polynomial (G) is G (x), then there is no error if R (x) G (x) = 0. R (x) G (x) = x ⁱ modG (x) (i = 0,1,2, ..., 39) indicates that there is a single bit error, and other patterns appear. Indicates that a multi-bit error has occurred.

The HEC operates in two types, a correction mode and a detection mode. In the correction mode, a correction for a single bit error is performed and a cell having a multi-bit error is ignored. Ignore it.

If R (x) G (X) is one of the 41 patterns representing no error or single bit error if it is a multi-bit error, that is, if the polynomial is calculated for multi-bit error, then no error or single bit error When the result of one of the 41 patterns is shown, error correction may be wrong.E (x) modG (x) = 0 (E (x) is an error polynomial, that is, error correction is wrong even in the case of a multi-bit error. Polynomial), it is recognized that there is no error in the ATM cell header, and a single bit in the header if E (x) modG (x) = x ⁱ modG (x) (i = 0,1,2,…, 39) It is recognized that there is an error.

HEC, an error correction method used in the ATM network, is insufficient to satisfy the BER required by the satellite network when combined with the satellite network.

In other words, when combining an ATM network, a satellite network, or a wireless network, a more powerful error correction method for improving BER is required.

On the other hand, when a satellite network combined with an ATM network uses a TDMA scheme, the TDMA system uses a unique word for burst synchronization.

That is, the TDMA frame is composed of a plurality of bursts # 1 to burst #n (1 to n), as shown in Figure 3, each TDMA burst signal is a guard time (a), preamble (Preamble) (b), a unique word (c), and data (d).

When the satellite network interworks with the ATM network, the data d is composed of an ATM cell coded.

Burst misdetection and burst false-detection in the UNI Word detection are very important because they cause data loss and destruction during one burst.

That is, burst miss detection affects acquisition time while TDMA sync is acquired, and burst false-detection causes false sync.

Therefore, a method for reducing the probability of false synchronization is to repeat burst detection over several consecutive frames, but this excessive burst detection repetition results in an increase in synchronization time.

When combining satellite network using ATM network and TDMA method as described above, TDMA synchronization acquisition time is slowed down by using only word for burst synchronization in TDMA system of satellite network, and it takes much time to synchronize ATM network and satellite network. There was a problem.

The present invention has been made to solve the above problems, the purpose of which is to combine the ATM network and satellite network, by inserting a stronger FEC instead of the HEC present in the ATM cell header to correct the error occurring in the ATM header It is to provide a method of improving BER when combining an ATM network and a satellite network that not only improves the performance of the BER but also reduces the cell loss ratio (CLR).

It is still another object of the present invention to improve TDMA synchronization characteristics by achieving fast burst synchronization in a TDMA satellite network using FEC technology.

1 is a diagram illustrating a combined state of an asynchronous transmission mode network and a satellite network;

2 is a flowchart illustrating a method for improving a bit error rate when combining an asynchronous transmission mode network and a satellite network according to the present invention;

3 is a view showing a structure of a time division multiple access frame and burst;

4 is a flowchart illustrating a burst synchronization method in a time division multiple access scheme according to the present invention;

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

10: ATM network 21: Central station

22: satellite 23, 24: remote station

In order to achieve the above object, the method of improving BER when combining an ATM network and a satellite network of the present invention comprises performing error correction and detection using an HEC in a header of an ATM cell at a transmitting end, and then removing the HEC, where the HEC is removed. Insert FEC, a more powerful error correction method, to transmit ATM cell over wireless transmission path, receive ATM cell on wireless transmission path at receiver, perform error correction and detection using FEC, and then remove FEC, It is characterized in that the original HEC cell is restored by inserting the same HEC as the HEC removed by the transmitter at the position where the FEC is removed.

Hereinafter, with reference to the accompanying drawings will be described in detail the BER improvement method when combining the ATM network and satellite network according to the present invention.

2 is an operation flowchart illustrating a BER improvement method when combining an ATM network and a satellite network according to the present invention.

First, the transmitting end of the ATM network 10 corrects a single bit error using the HEC in the header of the ATM cell, and detects a multi-bit error (S1).

Step S1 indicates bit error correction between the ATM network 10 and the satellite network.

Subsequently, after bit error correction and detection are performed in step S1, the HEC is removed (S2), and a more robust error correction method FEC is inserted into the position where the HEC is removed (S3).

Subsequently, the ATM cell newly created by the FEC insertion of step S3 is transmitted through the satellite 22 on the radio transmission path (S4).

Then, the receiving end of the remote station (23, 24) receives the corresponding ATM cell transmitted over the wireless transmission path (S5).

Subsequently, bit error correction and detection are performed using the FEC in the header of the ATM cell received in step S5 (S6).

That is, in step S6, more bits supporting stronger FEC parity checking are added to correct all errors that may occur in the wireless transmission path.

Then, after performing bit error correction and detection in step S6, the FEC is removed (S7), and the newly calculated HEC is inserted at the position where the FEC is removed (S8).

In this case, since the newly calculated HEC is the same as the algorithm for generating the HEC removed by the transmitter, the newly generated HEC and the HEC removed by the transmitter are the same.

Thereafter, as described above, the original ATM cell is restored according to the HEC insertion to perform the next process.

By using FEC instead of HEC in the ATM cell header as described above, it is possible to improve error correction and BER performance on the radio transmission path.

Next, a burst synchronization method in the TDMA method according to the present invention will be described with reference to FIG.

Open Aperture technology uses a narrow aperture technology that opens the aperture only near the Uniword detection time in order to reduce the probability of Uniword Fall-Detection, whereas the present invention applies FEC to burst synchronization. To further reduce the probability of burst false-detection.

That is, in the present invention, the burst synchronization is more stably achieved by completing all the error correction by the FEC as well as the conventional word detection.

First, as in the open aperture technique, a unique word is detected in a burst of a TDMA frame (S11).

At this time, whether the detection is good or bad or not is not a problem and whether or not the detection is a problem.

When the UNI word is detected in step S11, error detection and correction are performed using the FEC algorithm (S12).

Subsequently, as in the narrow aperture technique, a unique word is detected in the burst of the TDMA frame (S13).

In this case, too, if the detected error has an error, the error detection and correction is performed using the FEC in the next step.

When the UNI word is detected in step S13, error detection and correction are performed using the FEC algorithm (S14).

It is determined whether the synchronization is completed during the previously defined TDMA frame through the process up to now (S15), and if the synchronization is not completed, until the TDMA frame synchronization according to the burst synchronization is obtained (S16). S14) are performed again.

As described above, the synchronization method using the FEC of the present invention can achieve burst synchronization faster by reducing the number of continuous frames to perform synchronization than the conventional method of performing burst synchronization using only a unique word.

As described above, the present invention can improve the performance of the BER by adding the FEC instead of the HEC in the ATM header when combining the ATM network with the satellite network or the wireless network, thereby increasing the reliability on the radio link. There is an effect that can provide a better service.

In addition, in the case of a satellite network using the TDMA scheme, burst synchronization is performed using the FEC to increase the performance of a system requiring a high-speed service such as a multimedia service by quickly acquiring the TDMA synchronization.

Claims (2)

In the method for improving the BER on the radio transmission path when combining the ATM network 10 and the satellite network, A first step of correcting a single bit error by using the HEC in the header of the ATM cell at the transmitting end of the ATM network 10, and detecting the multi-bit error, and performing the bit error correction and detection in the first step, the HEC A second step of removing and inserting the FEC into the position where the HEC is removed, and transmitting the newly created ATM cell by the FEC insertion in the second step through the satellite 22 onto the wireless transmission path; A fourth step of receiving the ATM cell transmitted in the third step at the receiving end of the remote stations 23 and 24, and performing bit error correction and detection using the FEC in the header of the ATM cell received in the fourth step A fifth step of performing a bit error correction and detection in the fifth step, and removing the FEC and inserting the same HEC as the HEC removed by the transmitting end in the second step at the position where the FEC is removed; The original ATM cell is replaced by the HEC insertion in the sixth step. Source by way improve the bit error rate using the asynchronous transfer mode network and a satellite network upon binding of F Yi, characterized in that comprising a seventh step of performing the following processing. In the synchronization acquisition method of the TDMA frame when combining the ATM network 10 and the satellite network applying the TDMA method, A first step of detecting a unique word in a burst of a TDMA frame according to an open aperture technique, and a second step of performing error detection and correction using an FEC algorithm when the first word is detected in the first step; After performing the second step, a third step of detecting a UNIW word in a burst of a TDMA frame according to a narrow aperture technique, and an error detection and correction using an FEC algorithm when the UNIW word is detected in the third step After performing the fourth step, and after performing the fourth step, it is determined whether synchronization has been completed for a previously defined TDMA frame, and if the synchronization is not completed, the first to the second until the TDMA frame synchronization according to burst synchronization is obtained. 5. A burst synchronization method using FPC when combining an asynchronous transmission mode network and a satellite network, comprising a fifth step of performing a fourth step again.