KR20040044218A - A Two Dimensional Forward Error Correction Method And Data Communication Method Using The Method - Google Patents

Abstract

PURPOSE: A method for correcting two dimensional forward error and a method for communicating data by using the same are provided to improve the quality required for supplying a real time multimedia service by applying a two-dimensional forward error correction(FEC) technology. CONSTITUTION: A method for correcting two dimensional forward error includes the steps of: aligning the data packets to be transmitted in the unit of a predetermined two dimensional block during the transmission and creating a horizontal parity packet and a vertical parity packet for the each of the columns and rows of the aligned packet block; and recovering the lost data packet by using the horizontal direction and the vertical direction parity packets transmitted together with the data packets during the generation of the received data packet loss.

Description

Two-dimensional forward error correction method and data communication method using the method

The present invention relates to a two-dimensional forward error correction method applied to data communication, and a data communication method using the same, in particular in a multimedia service having a real-time transmission characteristics in a wireless communication network environment where many packet errors such as a wireless mobile communication system occurs As an efficient and flexible packet loss recovery scheme, the present invention relates to a method for increasing a recovery rate at a receiver for packets continuously lost on a wireless communication network.

Conventionally, Korean Patent Application No. 1999-0049160, "Lost Packet Recovery on the Internet Using Interleaving," uses a voice coding method having a high sound quality and high bit rate to recover packet loss that is continuously generated by a voice recovery method using redundant audio information. A method of recovering lost packets using redundant audio information when packet loss occurs by packetizing audio information coded at different times into one packet while simultaneously performing low coding and low bit rate speech coding has been proposed. However, this requires a process delay in the packetization process because two or more codecs must be supported for voice coding at different bit rates.

In addition, four forward error corrections (FEC 2733-An Real-time Transport Protocol (RTP) Payload Format for Generic Forward Error Correction (J. Rosenberg and H. Schulzrinne)) are proposed. Techniques are static lost packet recovery based on the Internet, a wired network. That is, it is generated as a result of performing an exclusive-OR (hereinafter abbreviated as "XOR") operation on two or more Real-time Transport Protocol (RTP) packets (hereinafter, referred to as "data packets") to be transmitted. The present invention provides a method of recovering a lost packet by using an additionally transmitted parity packet when packet loss occurs by transmitting the transmitted parity packet together with the data packet. The XOR operation lists two data packets as bit streams and then pads short packets to fit the longest packet size. A bit stream formed as a result of performing an XOR operation on bit streams having the same length constitutes one parity packet.

This method is suitable for the transmission of real-time data, such as multimedia data, because it does not require retransmission of packets. On the other hand, since the parity packet needs to be additionally transmitted in addition to the data packet required for information transmission, the bandwidth use of the network increases.

1 is a structural diagram of a parity packet generated by an XOR operation of a data packet, and FIG. 2 illustrates a structure of an FEC header among three parts constituting a parity packet.

The fields are as follows. The "SN base" field contains minimum sequence number information among data packets used to make a parity packet. Here, each data packet includes a sequence number (SN), and the sequence number having the smallest value among the sequence numbers included in the data packets used to generate the parity packet enters the "SN base" field. . The "Length recovery" field is filled with a value obtained by performing an XOR operation on the sequence number of the data packet used to make the parity packet, and the "E (Extension)" field is currently defined as '0'. In the "PT (Payload Type) recovery" field, the result of performing the XOR operation on the payload information of the data packet used to generate the parity packet, and in the "Mask" field, the data packet used to generate the parity packet. Information is filled in. Finally, the "Time Stamp (TS) recovery" field is filled with the result of performing the XOR operation on the TS of the data packet used to generate the parity packet.

In FIG. 3, the RTP header structure of the parity packet shown in FIG. 1 is illustrated. This format has the same structure as the RTP header of the original RTP packet (data packet).

Looking at each field one by one: First, the "V (Version)" field is '2' and indicates the version of the RTP. The "P (Padding)", "X (eXtension)", and "M (Marker)" fields are filled with the result of performing the XOR operation of the P, X, and M fields of the data packet used to generate the parity packet. The "PT (Payload Type)" field contains payload type information of the parity packet. In RFC 2733, the payload type of the parity packet is defined as '127'. The "SN (Sequence Number)" field is filled with the sequence number of the parity packet incremented by one, in addition to the sequence number of the data packet. The "TS (Time Stamp)" field is time information at the moment a parity packet is generated, and the "SSRC" field contains identification (ID) information of a source that generated the parity packet. That is, information such as the "SSRC" field of the data packet header is entered. Here, the contents of the "SSRC" field of the data packet generated by the same sender all have the same value.

Next, the basic FEC techniques proposed by RFC 2733 to guarantee the quality of service of real-time traffic are as follows.

FEC technique 1: P1, P2, f (P1, P2), P3, P4, f (P3, P4),...

The first FEC technique is shown in RFC 2733 as an example. After transmitting two data packets of P1 and P2, XOR operation is performed on these data packets P1 and P2 to generate one parity packet f (P1, P2). To send. FEC scheme 1 can recover lost P2 packets using P1 and f (P1, P2) received without error when P2 packets are lost. This technique basically has 50% overhead (rate of parity packets).

FEC technique 2: P1, f (P1, P2), P2, f (P2, P3), P3, f (P3, P4), P4, f (P4, P5),...

The second FEC technique is similar to the first method, and adds parity packet f (P1, P2) by performing XOR operation on these data packets P1 and P2 between two data packets P1 and P2. Has a head.

FEC technique 3: f (P1, P2), f (P1, P3), f (P1, P2, P3), f (P3, P4), f (P3, P5), f (P3, P4, P5), …

The third proposed FEC scheme is to transmit only parity packets F1, F2, F3, F4, F5, F6, ... without transmitting data packets P1, P2, P3, P4, .... Because this method only transmits parity packets, loss of these packets can result in irreparable data packets. In order to make up for this drawback, when a parity packet is created at the transmitting side, the data packet is duplicated so that a data packet that has not been recovered immediately can be recovered when a few parity packets are received. Therefore, the FEC scheme 3 can recover a single packet loss and two consecutive packet losses with less overhead than the FEC scheme 2. However, since only the parity packet is transmitted, the processing time of the transmitter and the receiver is longer than that of other FEC schemes.

FEC technique 4: P1, P2, f (P1, P2, P3), P3, f (P1, P3, P4), f (P1, P2, P4), P4,...

Finally, the proposed FEC scheme is designed to recover lost packets even when three or more consecutive packet losses occur. As shown in FIG. 4D, a parity packet for data packets is generated to generate a data packet and a data packet. It is a method of transmitting a parity packet. FEC scheme 4 shows high efficiency in recovering continuous packet loss, but has a disadvantage of 200% overhead.

As described above, the four FEC schemes proposed by the existing RFC 2733 do not consider packet loss due to burst error, which is a channel characteristic of a wireless network, and thus it is difficult to recover packets that are continuously lost. It is not suitable for wireless environments with characteristics. In addition, even if it is possible to overcome the aggregation error has a high overhead of 200%, there is a disadvantage of wasting the bandwidth of the limited network.

In order to overcome this problem, it is necessary to overcome packet loss due to aggregation error on the wireless network. Since the FEC techniques described above do not consider the characteristics of the radio channel, it is not suitable to apply to the wireless network.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and its main object is a two-dimensional forward error correction method capable of overcoming packet loss due to a continuous error occurring during data communication with little overhead. And the purpose is to provide a data communication method using the same.

In addition, another object of the present invention is to increase the transmission efficiency compared to the existing static forward error correction scheme by adaptively applying the forward error correction scheme in accordance with the change of the transmission error rate in consideration of the characteristics of the variable communication channel. It is to provide a two-dimensional forward error correction method and a data communication method using the same.

In order to achieve the above object, the two-dimensional forward error correction method according to the present invention, in transmission, arranges the data packets to be transmitted in units of predetermined two-dimensional blocks, and in the horizontal direction with respect to each row and column of the aligned packet blocks. A parity packet and a parity packet in a vertical direction are generated, and when a received data packet is lost when received, the parity packet is recovered by using horizontal and vertical parity packets transmitted together with the data packets. It is characterized by.

Further, in order to achieve the above object, the data communication method according to the present invention, in the data communication method, whether or not forward error correction processing using the packet loss rate information provided by the receiving side for the data packet transmitted from the transmitting side; Determining a first step; When the forward error correction process is determined, the data packets to be transmitted are arranged in predetermined two-dimensional blocks, and horizontal parity packets and vertical parity packets are generated and transmitted for each row and column of the aligned packet blocks. It is characterized by comprising a second step.

According to the present invention, a data packet for generating a parity packet needs to be stored in a queue at the transmitting side, and a receiving side requires a delay until receiving a parity packet necessary for recovering a lost packet. This is necessary. The delay at the transmitting side can reduce the processing delay required for parity packet generation by copying the packet at the same time as the data packet is generated and immediately transmitting the original packet and storing the copied packet in the queue. In addition, by applying a block interleaving technique (different packet transmission order) can overcome the congestion error characteristics on the radio.

In the present invention, it is necessary to apply different two-dimensional FEC techniques according to packet loss rate using RTCP (RTP Control Protocol) packets, which are feedback information of transmitted RTP packets (data packets). In the application of the FEC technique, by varying the (i, j) value of the matrix for the two-dimensional block of the data packet, the recovery rate is increased or decreased according to the overhead, and the sliding process is performed to fill the matrix to make the parity packet. By applying the window concept, there is a method of generating a parity packet for a data packet within a sliding window while moving a sliding window having a size (i, j) by one column. The process of generating the parity packet is as described above.

In addition, the RTP header of the parity packet described in FIG. 3 may be utilized to apply the adaptive two-dimensional FEC scheme according to the network situation using the received RTCP packet information. If the FEC scheme type information is applied to the PT (Payload Type) field containing the payload type information of the parity packet by defining the applicable two-dimensional FEC scheme type, the receiving side is currently applied without the need for a separate signaling or negotiation process. The type of 2D FEC technique being used can be identified.

If the SIP (Session Initiation Protocol) is used for signaling, it can contain information of the FEC scheme currently applied to the Session Description Protocol (SDP) part, which is the body part of the SIP message.

In addition, in the present invention, an additional processing delay occurs to recover a lost data packet using the received parity packet, but a method for reducing a recovery delay time at the receiving side is required. The receiving side receiving the data packet and the parity packet checks the sequence number of the received data packet to determine whether the data packet is lost or not. Instead of waiting for the packet to be received, the received parity packet and the vertical parity may be immediately restored.

1 is a structural diagram of a parity packet by general forward error correction (FEC).

2 is an FEC header structure diagram of the parity packet of FIG.

3 is a real-time transport protocol (RTP) header structure diagram of the parity packet of FIG.

4 is a conceptual diagram of an encoder implementing a two-dimensional forward error correction method according to the present invention.

5 is a conceptual diagram of a decoder implementing a two-dimensional forward error correction method according to the present invention.

6 and 7 are diagrams for explaining an embodiment of the FEC parity packet generation and packet transmission procedure in the two-dimensional forward error correction method according to the present invention.

8 is a view for explaining another embodiment of the FEC parity packet generation process in the two-dimensional forward error correction method according to the present invention.

9 is a view for explaining another embodiment of the FEC parity packet generation and packet transmission procedure in the two-dimensional forward error correction method according to the present invention.

10 is a flowchart illustrating a flow of processing a packet at a transmitting side using a two-dimensional forward error correction method according to the present invention.

11 is a flowchart illustrating a flow of receiving and processing a packet transmitted using a two-dimensional forward error correction method according to the present invention.

Hereinafter, a two-dimensional forward error correction method and a data communication method using the same according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a diagram conceptually illustrating a two-dimensional forward error correction method and a transmission data encoder of a transmitting side implementing the data communication method using the same.

In the figure, the RTP packet generation unit 12 packetizes the input data stream into RTP packets (data packets) under the control of the control unit 10. The generated data packet is copied and temporarily stored in a queue 14 to generate a parity packet by the two-dimensional forward error correction method according to the present invention. The data packet stored in the queue 14 is used by the parity packet generator 16 to generate the parity packet. Here, the control unit 10 performs the control by adjusting the error recovery rate of the receiving side by using the RTCP packet transmitted from the receiving side.

The parity packet generated by the RTP packet generation unit 12 and the parity packet generated by the parity packet generation unit 16 are sequentially arranged after the packet order arrangement 18 arranges the transmission order according to the present invention. It is transmitted via the output buffer 20.

In the method for generating a parity packet according to the present invention, first, a method of controlling a recovery rate by changing a value of (i, j) of a matrix, and a second sliding window concept in filling a matrix to make a parity packet. There is a method of generating a parity packet for a data packet within a sliding window while moving a sliding window having a size (i, j) by one column by applying.

The first method for generating the parity packet may be a parity packet generation method as illustrated in FIGS. 6 and 7. In the same figures, when the matrix (i, j) value is (3, 3), when the values of i and j are different, the packet generation order is also different.

The method shown in FIGS. 6 and 7 uses the exclusive OR (XOR) calculation method used for parity packet generation in the FEC method proposed in RFC 2733.

In order to increase the recovery rate of the lost RTP packet (data packet) at the receiving side, the transmitting side first selects an adaptive data packet matrix (i, j) according to the transmission error rate of the wireless network. Here, a method of adjusting the recovery rate of lost packets at the receiving side will be described. According to the matrix (i, j) value of the selected data packet, the number of additionally transmitted parity packets varies, and as the number of transmitted parity packets increases, the recovery rate increases. When the number of transmitted parity packets decreases, the recovery rate also decreases. You lose. If the matrix of data packets is (3,3), the overhead (rate of parity packets) is 66%; if the matrix of data packets is (2,2), the overhead is 100% (3, The recovery rate is higher than that of 3). Therefore, when the packet loss rate at the receiving side is low, the matrix of data packets is applied to (4, 4) or (3, 4). When the packet loss rate at the receiving side is high, the matrix of data packets is reduced to (3, 3) or (2, 3) or (2,2).

Secondly, if the generated RTP packet (data packet) is arranged in a two-dimensional (i, j) size matrix and the first row of the data packet is filled with j columns according to the value of (i, j), j data is filled. A packet generates one horizontal parity packet through an XOR operation. The same process is repeated to the i th row to generate i parity packets. When the i-th row of the first column is filled with i, the parity packet is generated. Thus, one vertical parity packet is generated through the XOR operation on the i data packets. The same process is repeated to the jth column to generate j parity packets. This generates i * j data packets and (i + j) parity packets. The generated data packet and the parity packet have a sequence number incremented by one and a start number is randomly selected. Third, the receiving side finds the lost data packet using the sequence number of the received data packet and then recovers the lost packet using the received data packet and the parity packet. Fourth, the received data packet and the recovered data packet are ordered based on the sequence number and then played out in playout units.

As described above, according to the present invention, a two-dimensional FEC technique (that is, generating and transmitting FEC parity packets in the horizontal and vertical directions) having different overheads may be applied.

The second parity packet generation method according to the present invention is a method for generating a parity packet by determining a sliding window size and moving the column size by one column.

8 shows another example of generating a parity packet in the 2D FEC scheme according to the present invention when the sliding window size is (2,2). If the window size is changed, the size of the matrix for generating the parity packet is also changed accordingly.

That is, the generated data packets P1, P2, ..., P20, ... are arranged as shown in Fig. 8 corresponding to the matrix (2, 2) which is the window size. First, a horizontal parity packet F1 is generated by performing an XOR operation of data packets P1 and P3 on data packets P1, P2, P3, and P4 corresponding to the matrix (2, 2), which is the window size, and then generate data packets P1 and P2. Generates a vertical parity packet (F2) through an XOR operation, and generates a horizontal parity packet (F3) through an XOR operation of data packets P2 and P4, and generates a vertical parity packet (F4) through an XOR operation of data packets P3 and P4. Create Then, horizontal parity packets and vertical parity packets are moved as described above with respect to (2,2) size data packets corresponding to the sliding windows, respectively, moving the (2,2) size window by one column. Create

In the present invention, an interleaving technique may or may not be applied in transmitting the data packet and the parity packet generated as described above. The interleaving technique may be classified into a block interleaving technique and a random interleaving technique.

When the interleaving technique is not applied, the packet is transmitted in the order in which the data packet and the parity packet are generated in the transmission of the data packet and the parity packet generated by the transmitter. That is, an example in which the interleaving technique is not applied is as shown in FIG. 7.

The parity packet generation process in the case of applying the interleaving scheme is the same as the case in which the interleaving scheme is not applied, and there is a difference in the transmission order of the generated data packet and the parity packet. That is, in the case of the block interleaving scheme, as shown in FIG. 9, for example, the two-dimensional FEC of (3, 3) is performed, and then the packets constituting the block are transmitted in the vertical order. In the case of a random interleaving scheme, packets constituting a block are randomly transmitted without a certain rule.

In the case of delay-sensitive traffic, it is important to reduce processing delays at the transmitting and receiving sides, so it is necessary to carefully select the interleaving technique.

Next, packet generation at the transmitting side will be described with reference to the flowchart of FIG. 10 and the encoder block diagram of FIG. 5.

First, when a data stream to be transmitted to the encoder on the transmitting side is input, the RTP packet generation unit 12 generates an RTP packet (data packet) (steps S1 and S3).

At this time, the encoder control unit 10 can know the quality (packet loss rate) of the packet being transmitted by receiving the RTCP packet containing the feedback information from the receiving side. That is, the receiving side feeds back the number of packets lost from the total received RTP packets (data packets), inter-packet transmission delay (ie, delay jitter) information, etc. in the RTCP packet to the transmitting side. The RTCP packet is divided into a Sender (SR) packet, a RR (Receiver Report) packet, a SDES (Source Description) packet, a BYE (Bye) packet, and an APP (Application Specific) packet. Here, the RTCP packet includes feedback information. Means RR packet.

The encoder control unit 10 determines, for example, whether or not FEC processing is performed by checking a "fraction lost" field containing packet loss ratio information in a field of the received RTCP packet (i.e., RR packet) (step S5). .

Here, if the packet loss rate is 0%, it is preferable to decide not to perform FEC processing, otherwise to determine to perform FEC processing.

If it is determined in step S5 not to perform the FEC process, the RTP packet (data packet) generated by the RTP packet generation unit 12 is controlled by the packet order arrangement unit 18 under the control of the control unit 10. Arranged as described above and transmitted through the output buffer 20 (step S7). In this case, the data packet is generated in a size of a predetermined packet size, the header and payload are filled, and then transmitted. At this time, the sender does not need to store the generated data packet in a queue.

On the other hand, if it is determined in the step S5 to perform the FEC process, the controller 10 checks the "fraction lost" field containing the packet loss rate information in the field of the received RTCP packet (ie, RR packet), and applies it. Determine the FEC type to be made (step S9). For example, if the packet loss rate is 10% or more, the FEC in the unit of FEC type 1 (2,2). If the packet loss rate is 5% to 10%, the matrix (2,3) is FEC type 2. FEC in units, matrix 3 (3,3) with FEC type 3 if packet loss rate is 3% to 5%, matrix with FEC type 4 (3,3) if packet loss rate is less than 3% 3) Determine the FEC of the unit.

Thereafter, an FEC parity packet is generated according to the FEC type determined in step S9 (step S11). That is, under the control of the controller 10, the RTP packets (data packets) generated by the RTP packet generator 12 are copied and temporarily stored in the queue 14, and the parity packet generator 16 is stored in the queue. The two-dimensional FEC parity packet is generated according to the determined FEC type with reference to the RTP packets (data packets) (step S11).

In this case, as shown in FIG. 3, when the FEC scheme type information applied to the PT (Payload Type) field containing the payload type information of the parity packet is included, the receiver is currently applied without any separate signaling or negotiation process. Identify types of two-dimensional FEC techniques.

Subsequently, the FEC parity packets generated in step S11 are aligned with the RTP packets (data packets) generated by the RTP packet generation unit 12 in the packet order alignment unit 18 in the transmission order and then output buffer ( 20) (step S13).

That is, in the case of applying the FEC, the parity packet is generated through the XOR operation of the data packet for generating the parity packet when the parity packet transmission turn is performed according to the applied two-dimensional FEC scheme. In this process, data packets needed to generate parity packets are copied before being sent and stored in a queue. The copied data packet stored in the queue to generate the parity packet in the 2D FEC block is deleted from the queue when the last parity packet is generated. Since the sequence number information of the data packets used to generate the parity packet is recorded in the mask field in the header part of the parity packet by RFC 2733, which parity packet should be used to recover the lost data packet at the receiving side. I can see.

On the other hand, when determining the presence or absence of FEC processing in step S5, since the RTCP packet is not received at the first transmission, a specific FEC type (e.g., FEC in the matrix (4,3) unit of FEC type 4) is applied. When the RTCP packet is received at the receiving end with respect to the packets transmitted by applying the FEC type, it is desirable to determine whether the FEC is processed and the FEC type according to the reception result.

Next, a packet receiving procedure at the receiving side will be described with reference to the flowchart of FIG. 12 and the decoder block diagram of FIG.

First, when the packets encoded by the encoder on the transmitting side are received by the decoder on the receiving side as described above (step S21), it is determined whether the packets received by the decoder type determining unit 30 are FEC processed packets (step S23). ). Here, it may be determined whether the packet is an RTP packet or a parity packet from information written in the "PT (Payload Type)" field in the header of the received packet.

If it is determined in step S23 that no FEC processing has been performed, the received packet is decomposed by the depacketizer 36, restored to the original data stream, and input into the playout buffer 37. At this time, the data stream bits input to the buffer 37 are to be played out in predetermined units (steps S25 to S31).

On the other hand, if it is determined in step S23 that the FEC processing has been performed, the processed FEC type is checked for the received packets (step S33). Here, if the FEC type is recorded in the PT (Payload Type) field of the parity packet in the transmitting encoder, the type discriminator 30 of the receiving decoder may refer to the PT (Payload Type) field of the parity packet to easily determine the FEC type. Able to know.

Thereafter, the received packets are separated into RTP packets (data packets) and FEC parity packets so that the RTP packets (data packets) are temporarily stored in the RTP buffer 32 and the FEC parity packets are temporarily stored in the FEC buffer 33 ( Steps S35, S37).

Subsequently, the packet loss discrimination unit 34 sequentially reads the RTP packets (data packets) stored in the RTP buffer 32 and checks the sequence numbers of the RTP packets (data packets) to determine whether the packets are lost. (Steps S39, S41).

If it is determined in step S41 that there is no packet loss, the RTP packet (data packet) read into the RTP buffer 32 is transferred to the depacketizer 36 and processed by the processes of steps S25 to S31 described above. do.

If it is determined in step S41 that there is a packet loss, the packet loss determining unit 34 determines whether the lost packet is recoverable based on the FEC type determined by the type determining unit 30 (step S43). ).

If it is determined in step S43 that the recovery is possible, the packet recovery unit 35 recovers the lost RTP packet (data packet) using the parity packets stored in the FEC buffer 33 (step S45). Here, the parity packet and the data packets necessary for the recovery are recovered by the XOR operation as in the case of generating the parity packet, and the recovered data packet is transmitted to the depacketizer 36 according to the sequence number. The process is performed by the above steps S25 to S31.

If it is determined in step S43 that it is not recoverable, the packet recovery unit 35 pads the lost data to "0" or "1" for the lost RTP packet (data packet) (step S47). The padded data packet is transferred to the depacketizer 36 and processed by the above steps S25 to S31.

In the case of the 2D FEC scheme according to the present invention, since it is possible to check whether packet recovery is possible twice for one data packet with a horizontal parity packet and a vertical parity packet, there is less overhead than the techniques proposed in the conventional RFC 2733. Recovery rate can be increased.

As described in detail above, according to the present invention, by applying a two-dimensional FEC technique for simultaneously transmitting a horizontal parity packet and a vertical parity packet when a packet loss occurs over the air, in real-time multimedia service by overcoming the aggregation error characteristics of the wireless channel The required quality can be improved.

In addition, the transmission efficiency can be increased by changing the overhead according to the packet loss rate in consideration of the variable radio channel characteristics, and the interleaving technique can be applied in various ways, so that the aggregation error can be overcome when the wireless network condition is not good.

In addition, only XOR operations are used to generate parity packets and recover lost packets, improving overall performance by reducing complexity and processing delay.

By applying the adaptive two-dimensional FEC scheme to packet loss over the air, by using the FEC technique suitable for the environment against continuous errors, it is possible to guarantee the data transmission quality over the wireless and to provide smooth high-speed multimedia service. Can be.

On the other hand, the present invention is not limited to the typical preferred embodiments described above, but can be carried out in various ways without departing from the gist of the present invention various modifications, changes, replacements or additions are common in the art Those who have knowledge will easily understand. If the implementation by such improvement, change, replacement or addition falls within the scope of the appended claims, the technical idea should also be regarded as belonging to the present invention.

Claims (10)

At the time of transmission, arrange the data packets to be transmitted in units of a predetermined two-dimensional block and generate a horizontal parity packet and a vertical parity packet for each row and column of the aligned packet block, And upon reception, when the loss of the received data packet occurs, recovering the lost data packet using horizontal and vertical parity packets transmitted with the data packets. In the data communication method, A first step of determining whether or not forward error correction processing is performed on the data packet transmitted from the transmitter using the packet loss rate information provided by the receiver; When the forward error correction process is determined, the data packets to be transmitted are arranged in predetermined two-dimensional blocks, and horizontal parity packets and vertical parity packets are generated and transmitted for each row and column of the aligned packet blocks. A data communication method comprising a second step. The method of claim 1, In the first step, the predetermined block unit is also determined, and in the second step, the data packets to be transmitted are arranged in the determined block unit. The method of claim 3, The data packet is a Real-time Transport Protocol (RTP) packet, and the packet loss rate information is included in a RTP (RTP Control Protocol) packet. The method of claim 4, wherein And the block unit information is included in a payload type field of an RTP header portion of the generated parity packet. The method of claim 3, In the first step, if the packet loss rate is low, a block unit having a large number of data packets is determined. If the packet loss rate is high, a block unit having a small number of data packets is determined. The method of claim 2, In the second step, after copying the data packet necessary to generate the horizontal and vertical parity packet, the original data packet is immediately transmitted and the copied data packet is stored in the queue. A data communication method, which is used for generation of a parity packet. The method according to any one of claims 2 to 7, The data communication method of the second step in the data packet and parity packet transmission method characterized in that to apply any one of the interleaving technique and the non-interleaving technique. The method of claim 9, The interleaving method is one of a block interleaving method and a random interleaving method. The method according to any one of claims 2 to 7, The receiving side receiving the data packet and the parity packet checks the sequence number of the received data packet to determine whether the data packet is lost. And a third step of immediately restoring the received horizontal parity packet and the vertical parity without waiting for a data packet to be received.