US20140075269A1 - Method for Optimizing the Forward Error Correction Scheme - Google Patents

Method for Optimizing the Forward Error Correction Scheme Download PDF

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US20140075269A1
US20140075269A1 US13/830,458 US201313830458A US2014075269A1 US 20140075269 A1 US20140075269 A1 US 20140075269A1 US 201313830458 A US201313830458 A US 201313830458A US 2014075269 A1 US2014075269 A1 US 2014075269A1
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packets
fec
packet
data packets
recovering
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Carmit Sahar
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Harmonic Inc
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Harmonic Inc
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    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00Error detection; Error correction; Monitoring
    • G06F11/07Responding to the occurrence of a fault, e.g. fault tolerance
    • G06F11/08Error detection or correction by redundancy in data representation, e.g. by using checking codes
    • G06F11/10Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03MCODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/29Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
    • H03M13/2906Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes using block codes
    • H03M13/2909Product codes
    • H03M13/2915Product codes with an error detection code in one dimension
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03MCODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/37Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35
    • H03M13/373Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35 with erasure correction and erasure determination, e.g. for packet loss recovery or setting of erasures for the decoding of Reed-Solomon codes
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/004Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0041Arrangements at the transmitter end
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/004Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0045Arrangements at the receiver end
    • H04L1/0047Decoding adapted to other signal detection operation
    • H04L1/005Iterative decoding, including iteration between signal detection and decoding operation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/004Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056Systems characterized by the type of code used
    • H04L1/0057Block codes
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/004Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056Systems characterized by the type of code used
    • H04L1/0064Concatenated codes
    • H04L1/0066Parallel concatenated codes
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/61Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/238Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams
    • H04N21/2383Channel coding or modulation of digital bit-stream, e.g. QPSK modulation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/238Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams
    • H04N21/2389Multiplex stream processing, e.g. multiplex stream encrypting

Definitions

  • the present invention relates to the field of data packet recovering methods. More particularly, the invention relates to a method for reorganizing and optimizing the Forward Error Correction (FEC) scheme in order to achieve a more efficient data packet recovery method while reducing the total overhead of the additional recovery packets.
  • FEC Forward Error Correction
  • the FEC scheme requires adding a fixed percentage of additional packets to a block of data packets such that the loss of one or more data packets in the block, within some predetermined bound, can be recovered by combining the FEC packets with those data packets that had been successfully received in order to reconstruct the missing data packets.
  • the FEC scheme potentially provides a low-latency method for effectively correcting and recovering lost packets especially in situations where the transmission is undirectional from one source to numerous destinations.
  • the FEC scheme is defined in Pro-MPEG Code of Practice #3 release 2 July 2004 “Transmission of Professional MPEG Transport Streams over IP Networks”.
  • the encoder i.e. transmitter
  • the decoder i.e. receiver
  • XOR is chosen as the error correcting function for FEC, which is computationally very easy to implement.
  • a XOR function is applied to a sequence of four data packets in order to yield a fifth packet “R”:
  • variable packet loss rates and variable bit rates coupled with the need to minimize latency, present an even greater challenge to the implementation of FEC schemes for protecting the data packets. Therefore, the selected FEC scheme, which augments a media stream with redundant data, should be designed to help restore stream integrity based upon anticipated levels of packet loss.
  • the FEC scheme which groups data packets into a FEC block, produces FEC packets which are said to cover the data packets in that block, since missing data packets can be restored by combining the remaining data packets and FEC packets in that block.
  • FEC coverage the number of missing data packets that the FEC scheme can recover within the same block, is limited to the number of FEC packets within that block. Therefore, a method is needed for arranging the FEC data packet blocks in order to achieve a reliable packet recovery method without burdening the system with a massive overhead.
  • the simple and na ⁇ ve method for using the FEC scheme suggests protecting every few consecutive packets with a FEC packet.
  • packet loss due to burst has a high probability of losing a number of consecutive packets, which in this case, may not be recoverable by the protecting FEC packet.
  • FIG. 1 a illustrates another prior art method for using the FEC scheme.
  • This method suggests protecting each block of packets having a constant gap between them with a FEC packet.
  • the total batch of data packets may be divided into fixed rows of predefined number, whereas the FEC packets are designed each to protect a column.
  • k Base
  • the receiver is able to recover them using the five FEC packets.
  • this method is capable of recovering only one lost packet in each column.
  • FIG. 1 b illustrates such a case where the highlighted packets are lost and there is no way of recovering them using this prior art method, as some of the columns have more than one lost packet.
  • US 2006/0029065 discloses a FEC encoding system and method optimized fur protecting real-time audio-video streams for transmission over packet-switched networks with minimal latency.
  • the disclosed system and method provide a low-latency FEC scheme for both variable and constant bit-rate MPEG-encoded audio and video streams.
  • the disclosed method sorts packets by content type and aggregates them into FEC blocks weighted by sensitivity in the recovered stream to packet loss of a particular content type.
  • the described method and system is very complicated and requires the knowledge and identification of the data packets contents.
  • the present invention relates to a method for optimizing the FEC scheme comprising the steps of: (a) receiving a batch of data packets designated for transmission; (b) choosing a number of divisors having no common denominators in accordance with the said batch of data packets; (c) organizing into blocks said batch of data packets a number of times in accordance with the number of divisors using said divisors; and (d) creating a FEC packet for each of said blocks.
  • the method further comprises the steps of: (e) transmitting the designated batch of data packets together with the created FEC packets to a receiver; and (f) recovering lost data packets of said designated batch using said created FEC packets at said receiver.
  • the divisors are 5, 7, and 9.
  • the divisors are 5, 6, and 7.
  • FIG. 1 a illustrates a prior art method for using the FEC scheme.
  • FIG. 1 b illustrates a prior art method for using the FEC scheme.
  • FIG. 2 is a table illustrating an example of 100 data packets and their corresponding FEC packets according to another method of a prior art.
  • FIG. 3 is a table illustrating an example of the same batch of 100 data packets organized in 3 various constellations, and their corresponding FEC packets according to an embodiment of the invention.
  • FIG. 4 is another table illustrating an example of 100 data packets, and their corresponding FEC packets according to the method of the prior art.
  • FIG. 5 is another table illustrating an example of 100 data packets, and their corresponding FEC packets according to an embodiment of the invention.
  • FEC Forward Error Correction
  • the term Forward Error Correction (FEC) scheme is used hereinafter to describe an error correction method for data transmission, in which the transmitter sends redundant data packets to a receiver or a number of receivers, for recovering errors in the data flow.
  • the FEC scheme may be used for finding errors in the received data packets, correcting errors in the received data packets, or for replacing lost data packets.
  • the FEC is also defined in Pro-MPEG Code of Practice #3 release 2 Jul. 2004 “Transmission of Professional MPEG-2 Transport Streams over IP Networks”.
  • the error correcting function chosen for FEC is XOR which is computationally very easy to implement.
  • the XOR function applied to a sequence of 4 data packets yields a FEC packet “R”:
  • each FEC packet since each FEC packet is able to recover only one packet in the sequence it protects, the smaller the amount of data packets in the protected sequence, the better the protection of the FEC scheme for error recovery.
  • a FEC packet may be added for each data packet.
  • the adding of FEC packets increases bandwidth overhead, which increases cost and latency.
  • FIG. 2 is a table illustrating an example of 100 data packets and their corresponding FEC packets according to the method of a prior art.
  • the 100 data packets are organized in 5 columns and 20 rows, where each row of data packets is protected by a FEC packet and each column of data packets is protected by a FEC packet, totaling 25 FEC packets.
  • the FEC packets protecting the rows are signed as FEC and numbered accordingly.
  • this method increases bandwidth overhead of 25%, it is widely used for recovering packet loss. For example, if the marked packets 42-47 are lost during the data flow, it is possible to recover these lost packets using the following steps:
  • this prior art method cannot recover a larger amount of lost consecutive packets such as 42-48. Furthermore, this prior art method cannot recover lour packets sharing the same rows and columns such as, 43, 44, 48 and 49.
  • FIG. 3 is a table illustrating an example of the same batch of 100 data packets organized in 3 various constellations, and their corresponding FEC packets according to an embodiment of the invention.
  • These 3 organized constellations are merely a visual representation of the operations made on the same batch of data packets.
  • the terms organize, organized, and organizing, are used hereinafter for visually, or conceptually, describing the operations made on a batch of data packets, although in reality no need arises for actually dividing and reorganizing the batch of data packets.
  • the same batch of packets designated for transmission is organized in columns, i.e. divided into groups of packets, for 3 times, prior to transmission.
  • the total amount of designated packets is organized in five columns, and a FEC packet is added for every column, meaning, that each column containing a sequence of 20 data packets is protected by one FEC packet.
  • the same total amount of designated packets is organized in seven columns, and again a FEC packet is added for protecting each column of packets.
  • packets 90 and 100 are not protected by a FEC as the total of 100 is not divisible by 7.
  • the last two packets may be protected by the existing FEC packets, such as protecting packet 99 by FEC 6 and protecting packet 100 by FEC 7.
  • the last two packets may be protected by the FEC packets of the next batch of packets.
  • the same total amount of designated packets is organized in nine columns, and again a FEC packet is added for protecting each column of packets (since the total of 100 is not divisible by 9, the last packet may be protected as described before in relation to the second step).
  • the total batch of data packets is divided, i.e. conceptually organized, into fixed rows of predefined number for 3 times, where the FEC packets are designed to protect a column each.
  • transmission the batch of packets is sent together with the created FEC packets.
  • the method of the invention requires only 3 iterations: firstly employing the FEC packets of the 9 ⁇ 11 arrangement, secondly employing the FEC packets of the 5 ⁇ 20 arrangement, and thirdly employing the FEC packets of the 7 ⁇ 14 arrangement.
  • FIG. 4 is another table illustrating an example of 100 data packets, the highlighted lost packets, and their corresponding FEC packets according to the method of the prior art.
  • the missing packets 31, 36, 37, 42, 43, 48, 49, 54, 55, and 60 form a stairway pattern.
  • iterations In order to recover the lost packets 5 iterations must be made:
  • FIG. 5 illustrates the method of the invention with the same lost packets and their corresponding FEC packets.
  • 3 iterations are required:
  • the order of the iterations is preset in order to minimize the number of iterations.
  • the preset order may be to use the FEC packets of 9 ⁇ 11 arrangement first, then to use the FEC packets of 7 ⁇ 14 arrangement, and lastly to use the FEC packets of 5 ⁇ 20 arrangement.
  • Other preset orders are possible as well.
  • the numbers, i.e. divisors, for organizing and dividing the group of data packets into columns are 5, 6, and 7, which have no common denominator and increase the bandwidth overhead by only 18%.
  • the invention may be carried out with different numbers. In any case, the invention is not limited in any way to a specific set of numbers.
  • the described optimization of the FEC scheme requires that the numbers used for organizing and dividing a batch of data packets into columns cannot be too large, since that adds too many FEC packets, or too small, since that requires each FEC packet to protect too many data packets, and the chosen numbers cannot have common denominators, since the packets they protect will overlap. Furthermore, many combinations of numbers may be used for organizing the group of data packets into columns. The total group of data packets may be divided more than 3 times or less than 3 times. Therefore, the combination of numbers may contain more or less than 3 numbers having no common denominators, and may vary greatly according to the needs and requirements of the transmitted data packets.

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  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
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  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Probability & Statistics with Applications (AREA)
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Abstract

The present invention relates to a method for optimizing the FEC scheme comprising the steps of: (a) receiving a batch of data packets designated for transmission; (b) choosing a number of divisors having no common denominators in accordance with the said batch of data packets; (c) organizing into blocks said batch of data packets a number of times in accordance with the number of divisors using said divisors; and (d) creating a FEC packet for each of said blocks.

Description

    FIELD OF THE INVENTION
  • The present invention relates to the field of data packet recovering methods. More particularly, the invention relates to a method for reorganizing and optimizing the Forward Error Correction (FEC) scheme in order to achieve a more efficient data packet recovery method while reducing the total overhead of the additional recovery packets.
  • BACKGROUND OF THE INVENTION
  • During streaming of video or audio data packets, random congestion may cause packet loss and jitter. Furthermore, the typical high sensitivity of video systems to variations in packet rate transmission also adds to the danger of degradation resulting from data congestion, potential overflow and the resulting packet loss. The data packets that are dropped and lost cause a gap in the video or audio streaming which is highly unacceptable and intolerable. In addition to contending with packet delivery problems, maintaining low latency is a critical constraint for video streaming.
  • One of the methods used today for packet recovery of lost data packets is the forward Error Correction (FEC) scheme. The FEC scheme requires adding a fixed percentage of additional packets to a block of data packets such that the loss of one or more data packets in the block, within some predetermined bound, can be recovered by combining the FEC packets with those data packets that had been successfully received in order to reconstruct the missing data packets. The FEC scheme potentially provides a low-latency method for effectively correcting and recovering lost packets especially in situations where the transmission is undirectional from one source to numerous destinations.
  • The FEC scheme is defined in Pro-MPEG Code of Practice #3 release 2 July 2004 “Transmission of Professional MPEG Transport Streams over IP Networks”. The encoder (i.e. transmitter) inserts FEC packets into the output stream and the decoder (i.e. receiver) uses those FEC packets to reconstruct missing packets in the data sequence it receives, where each FEC packet protecting a group of packets can help recover a single lost packet.
  • In the standard, XOR is chosen as the error correcting function for FEC, which is computationally very easy to implement. In this example, a XOR function is applied to a sequence of four data packets in order to yield a fifth packet “R”:
  • ti A
    Figure US20140075269A1-20140313-P00001
    B
    Figure US20140075269A1-20140313-P00001
    C
    Figure US20140075269A1-20140313-P00001
    D=R
  • “R” has the ability to recover any one lost packet of the initial four packets it protects, such as recovering packet “A”:

  • R
    Figure US20140075269A1-20140313-P00001
    B
    Figure US20140075269A1-20140313-P00001
    C
    Figure US20140075269A1-20140313-P00001
    D=A.
  • Nevertheless, inserting FEC packets into the stream introduces bandwidth overhead and implies latency, since the FEC can be calculated only after all the packets it protects have been produced. Therefore a very important parameter in configuring the FEC scheme is how many FEC packets are needed for protecting a selected hatch of data packets, and how to organize the protection of the FEC packets over the data packets.
  • Variable packet loss rates and variable bit rates, coupled with the need to minimize latency, present an even greater challenge to the implementation of FEC schemes for protecting the data packets. Therefore, the selected FEC scheme, which augments a media stream with redundant data, should be designed to help restore stream integrity based upon anticipated levels of packet loss. The FEC scheme, which groups data packets into a FEC block, produces FEC packets which are said to cover the data packets in that block, since missing data packets can be restored by combining the remaining data packets and FEC packets in that block. FEC coverage, the number of missing data packets that the FEC scheme can recover within the same block, is limited to the number of FEC packets within that block. Therefore, a method is needed for arranging the FEC data packet blocks in order to achieve a reliable packet recovery method without burdening the system with a massive overhead.
  • The simple and naïve method for using the FEC scheme suggests protecting every few consecutive packets with a FEC packet. However, packet loss due to burst has a high probability of losing a number of consecutive packets, which in this case, may not be recoverable by the protecting FEC packet.
  • FIG. 1 a illustrates another prior art method for using the FEC scheme. This method suggests protecting each block of packets having a constant gap between them with a FEC packet. In other words, the total batch of data packets may be divided into fixed rows of predefined number, whereas the FEC packets are designed each to protect a column. The payload of the kth FEC packet (out of the L) protects the D packets numbered k+nL (0≦n≦D−1), where the parameters k, L, D are transmitted in the header of each FEC packet (In the standard, L=Offset, D=NA, k=Base). As illustrated in FIG. 1 a an example of 100 data packets are divided into 20 rows, and 5 FEC packets are added, where each FEC packet protects 20 data packets assigned in a column (L=5, D=20). Thus, if the highlighted packets (i.e. 9, 22, 48, 75, and 91) are lost in the transmission, the receiver is able to recover them using the five FEC packets. However, this method is capable of recovering only one lost packet in each column. FIG. 1 b illustrates such a case where the highlighted packets are lost and there is no way of recovering them using this prior art method, as some of the columns have more than one lost packet.
  • US 2006/0029065 discloses a FEC encoding system and method optimized fur protecting real-time audio-video streams for transmission over packet-switched networks with minimal latency. The disclosed system and method provide a low-latency FEC scheme for both variable and constant bit-rate MPEG-encoded audio and video streams. To maximize bandwidth-efficiency and playable frame rate for recovered media streams, the disclosed method sorts packets by content type and aggregates them into FEC blocks weighted by sensitivity in the recovered stream to packet loss of a particular content type. However, the described method and system is very complicated and requires the knowledge and identification of the data packets contents.
  • It is an object of the present invention to provide a method for re-organizing and optimizing the FEC scheme.
  • It is another object of the present invention to provide a reliable packet recovery method using the FEC scheme.
  • It is still another object of the present invention to provide a method that achieves a simple and reliable packet recovery method without burdening the system with massive bandwidth overhead.
  • Other objects and advantages of the invention will become apparent as the description proceeds.
  • SUMMARY OF THE INVENTION
  • The present invention relates to a method for optimizing the FEC scheme comprising the steps of: (a) receiving a batch of data packets designated for transmission; (b) choosing a number of divisors having no common denominators in accordance with the said batch of data packets; (c) organizing into blocks said batch of data packets a number of times in accordance with the number of divisors using said divisors; and (d) creating a FEC packet for each of said blocks.
  • Preferably, the method further comprises the steps of: (e) transmitting the designated batch of data packets together with the created FEC packets to a receiver; and (f) recovering lost data packets of said designated batch using said created FEC packets at said receiver.
  • Preferably, the divisors are 5, 7, and 9.
  • In an embodiment the divisors are 5, 6, and 7.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • In the drawings:
  • FIG. 1 a illustrates a prior art method for using the FEC scheme.
  • FIG. 1 b illustrates a prior art method for using the FEC scheme.
  • FIG. 2 is a table illustrating an example of 100 data packets and their corresponding FEC packets according to another method of a prior art.
  • FIG. 3 is a table illustrating an example of the same batch of 100 data packets organized in 3 various constellations, and their corresponding FEC packets according to an embodiment of the invention.
  • FIG. 4 is another table illustrating an example of 100 data packets, and their corresponding FEC packets according to the method of the prior art.
  • FIG. 5 is another table illustrating an example of 100 data packets, and their corresponding FEC packets according to an embodiment of the invention.
  • DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
  • The term Forward Error Correction (FEC) scheme is used hereinafter to describe an error correction method for data transmission, in which the transmitter sends redundant data packets to a receiver or a number of receivers, for recovering errors in the data flow. The FEC scheme may be used for finding errors in the received data packets, correcting errors in the received data packets, or for replacing lost data packets. The FEC is also defined in Pro-MPEG Code of Practice #3 release 2 Jul. 2004 “Transmission of Professional MPEG-2 Transport Streams over IP Networks”.
  • The error correcting function chosen for FEC is XOR which is computationally very easy to implement. For example, the XOR function applied to a sequence of 4 data packets yields a FEC packet “R”:

  • A
    Figure US20140075269A1-20140313-P00001
    B
    Figure US20140075269A1-20140313-P00001
    C
    Figure US20140075269A1-20140313-P00001
    D=R
  • FEC packet R has the ability to recover any one lost packet of the sequence of 4 packets it protects, such as packet “A”: R
    Figure US20140075269A1-20140313-P00001
    B
    Figure US20140075269A1-20140313-P00001
    C
    Figure US20140075269A1-20140313-P00001
    D=A
  • Therefore, since each FEC packet is able to recover only one packet in the sequence it protects, the smaller the amount of data packets in the protected sequence, the better the protection of the FEC scheme for error recovery. In extreme cases a FEC packet may be added for each data packet. However, the adding of FEC packets increases bandwidth overhead, which increases cost and latency.
  • FIG. 2 is a table illustrating an example of 100 data packets and their corresponding FEC packets according to the method of a prior art. In this example the 100 data packets are organized in 5 columns and 20 rows, where each row of data packets is protected by a FEC packet and each column of data packets is protected by a FEC packet, totaling 25 FEC packets. For the sake of brevity, the FEC packets protecting the rows are signed as FEC and numbered accordingly. Although this method increases bandwidth overhead of 25%, it is widely used for recovering packet loss. For example, if the marked packets 42-47 are lost during the data flow, it is possible to recover these lost packets using the following steps:
      • 1. recovering packet 43 using FEC3,
      • 2. recovering packet 44 using FEC4,
      • 3. recovering packet 45 using FEC5,
      • 4. recovering packet 46 using FEC1,
      • 5. After recovering packet 46, recovering packet 47 using FEC 10,
      • 6. After recovering packets 43, 44, and 45, recovering packet 42 using FEC9.
  • However, this prior art method cannot recover a larger amount of lost consecutive packets such as 42-48. Furthermore, this prior art method cannot recover lour packets sharing the same rows and columns such as, 43, 44, 48 and 49.
  • FIG. 3 is a table illustrating an example of the same batch of 100 data packets organized in 3 various constellations, and their corresponding FEC packets according to an embodiment of the invention. These 3 organized constellations are merely a visual representation of the operations made on the same batch of data packets. For sake of brevity, the terms organize, organized, and organizing, are used hereinafter for visually, or conceptually, describing the operations made on a batch of data packets, although in reality no need arises for actually dividing and reorganizing the batch of data packets. In this embodiment the same batch of packets designated for transmission is organized in columns, i.e. divided into groups of packets, for 3 times, prior to transmission. First, the total amount of designated packets is organized in five columns, and a FEC packet is added for every column, meaning, that each column containing a sequence of 20 data packets is protected by one FEC packet. Secondly, the same total amount of designated packets is organized in seven columns, and again a FEC packet is added for protecting each column of packets. In this example constellation, packets 90 and 100 are not protected by a FEC as the total of 100 is not divisible by 7. However, in another embodiment of the invention the last two packets may be protected by the existing FEC packets, such as protecting packet 99 by FEC 6 and protecting packet 100 by FEC 7. In addition, since it is not necessary to have exactly the same 100 packets protected by exactly the same FEC packets, the last two packets may be protected by the FEC packets of the next batch of packets. Lastly, the same total amount of designated packets is organized in nine columns, and again a FEC packet is added for protecting each column of packets (since the total of 100 is not divisible by 9, the last packet may be protected as described before in relation to the second step). In summation, the total batch of data packets is divided, i.e. conceptually organized, into fixed rows of predefined number for 3 times, where the FEC packets are designed to protect a column each. During, transmission the batch of packets is sent together with the created FEC packets. In this embodiment, 21(=5+7+9) FEC packets have been added totaling only 21% of bandwidth overhead, while, in many cases, the sought protection exceeds the protection of prior art methods. For example, assuming the highlighted packets (i.e. 60, 61, 62, 67, 68, 69, 74, 75, 76, 81, 82, and 83) were lost in transmission, using the following steps all the packets can be recovered:
      • 1. recovering packet 61 using FEC19,
      • 2. recovering packet 62 using FEC20,
      • 3. recovering packet 68 using FEC17,
      • 4. recovering packet 75 using FEC15,
      • 5. recovering packet 81 using FEC21,
      • 6. recovering packet 82 using FEC13,
      • 7. recovering packet 60 using FEC5,
      • 8. recovering packet 67 using FEC2,
      • 9. recovering packet 76 using FEC1,
      • 10.recovering packet 83 using FEC3,
      • 11. recovering packet 69 using FEC11,
      • 12. recovering packet 74 using FEC9.
  • Thus the lost packets are recovered.
  • In many cases it is also significant to test how many iterations the method requires for recovering the lost packets. For example, when recovering the lost data packets highlighted in FIG. 3 the method of the invention requires only 3 iterations: firstly employing the FEC packets of the 9×11 arrangement, secondly employing the FEC packets of the 5×20 arrangement, and thirdly employing the FEC packets of the 7×14 arrangement.
  • FIG. 4 is another table illustrating an example of 100 data packets, the highlighted lost packets, and their corresponding FEC packets according to the method of the prior art. In this example the missing packets 31, 36, 37, 42, 43, 48, 49, 54, 55, and 60 form a stairway pattern. In order to recover the lost packets 5 iterations must be made:
      • 1. recovering packets 31 and 60 using the FEC′ packets (specifically: FEC′7 and FEC′12),
      • 2. recovering packets 36 and 55 using the FEC packets (specifically: FEC1 and FEC5),
      • 3. recovering packets 37 and 54 using the FEC′ packets (specifically: FEC′8 and FEC′11),
      • 4. recovering packets 42 and 49 using the FEC packets (specifically: FEC2 and FEC4),
      • 5. recovering packets 43 and 48 using the FEC′ packets (specifically: FEC′9 and FEC′10).
  • However, the same lost packets may be recovered with less iterations when applying the method of the invention, for example, FIG. 5 illustrates the method of the invention with the same lost packets and their corresponding FEC packets. In order to recover the missing packets 31, 36, 37, 42, 43, 48, 49, 54, 55, and 60 only 3 iterations are required:
      • 1. recovering packets 43 and 48 using the FEC packets of 9×11 arrangement (specifically: FEC 19 and FEC15),
      • 2. recovering packets 36, 37, 31, 54, 55, and 60 using the FEC packets of 7×14 arrangement (specifically: FEC6, FEC7, FEC8, FEC10, FEC11, and FEC9),
      • 3. recovering packets 42 and 49 using the FEC packets of 5×20 arrangement (specifically: FEC2 and FEC4).
  • In one of the embodiments, the order of the iterations is preset in order to minimize the number of iterations. For example, the preset order may be to use the FEC packets of 9×11 arrangement first, then to use the FEC packets of 7×14 arrangement, and lastly to use the FEC packets of 5×20 arrangement. Other preset orders are possible as well.
  • As understood, other numbers, i.e. divisors, may be used for organizing a batch of data packets into columns other than 5, 7, and 9 for carrying out the invention. However, the essence of the invention lies in choosing the numbers that have no common denominator, since using numbers with common denominators causes overlapping of the protected data packets. For example, if among the chosen divisors are 3 and 9, the 3 FEC packets protecting the 3 columns are totally superfluous as their data packets are already better protected by the 9 FEC packets.
  • In another embodiment of the invention the numbers, i.e. divisors, for organizing and dividing the group of data packets into columns, are 5, 6, and 7, which have no common denominator and increase the bandwidth overhead by only 18%. In other embodiments, the invention may be carried out with different numbers. In any case, the invention is not limited in any way to a specific set of numbers.
  • In conclusion, the described optimization of the FEC scheme requires that the numbers used for organizing and dividing a batch of data packets into columns cannot be too large, since that adds too many FEC packets, or too small, since that requires each FEC packet to protect too many data packets, and the chosen numbers cannot have common denominators, since the packets they protect will overlap. Furthermore, many combinations of numbers may be used for organizing the group of data packets into columns. The total group of data packets may be divided more than 3 times or less than 3 times. Therefore, the combination of numbers may contain more or less than 3 numbers having no common denominators, and may vary greatly according to the needs and requirements of the transmitted data packets.
  • While some embodiments of the invention have been described by way of illustration, it will be apparent that the invention can be carried into practice with many modifications, variations and adaptations, and with the use of numerous equivalents or alternative solutions that are within the scope of persons skilled in the art, without departing from the spirit of the invention or exceeding the scope of the claims.

Claims (4)

1. A method for optimizing the FEC scheme comprising the steps of:
a. receiving a batch of data packets designated for transmission;
b. choosing a number of divisors having no common denominators in accordance with the said batch of data packets;
c. organizing into blocks said batch of data packets a number of times in accordance with the number of divisors using said divisors; and
d. creating a FEC packet for each of said blocks.
2. A method according to claim 1 further comprising the steps of:
e. transmitting the designated batch of data packets together with the created FEC packets to a receiver; and
f. recovering lost data packets of said designated batch using said created FEC packets at said receiver.
3. A method according to claim 1, where the divisors are 5, 7, and 9.
4. A method according to claim 1, where the divisors are 5, 6, and 7.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130007552A1 (en) * 2011-06-30 2013-01-03 Brother Kogyo Kabushiki Kaisha Data processing devices, computer readable storage media, and methods

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8031701B2 (en) 2006-09-11 2011-10-04 Cisco Technology, Inc. Retransmission-based stream repair and stream join
WO2009089695A1 (en) * 2008-01-14 2009-07-23 Zte Corporation A data transmission method and equipment
CN101286819B (en) * 2008-05-07 2010-05-12 中兴通讯股份有限公司 Data receiving method and device
US9312989B2 (en) * 2008-07-07 2016-04-12 Cisco Technology, Inc. Importance-based FEC-aware error-repair scheduling
US10498359B2 (en) * 2011-07-14 2019-12-03 Microsoft Technology Licensing, Llc Correction data
IL217306A (en) * 2012-01-01 2016-05-31 Video Flow Ltd Packets recovery system and method

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5369682A (en) * 1992-08-17 1994-11-29 Glenayre Electronics, Inc. Digital simulcast transmission system
US6681362B1 (en) * 2000-03-06 2004-01-20 Sarnoff Corporation Forward error correction for video signals
US20080219151A1 (en) * 2007-03-07 2008-09-11 Nokia Corporation System and method for using a peer to peer mechanism to repair broadcast data in wireless digital broadcast networks
US20080250299A1 (en) * 2004-04-29 2008-10-09 Arnaud Maillet Method of Transmitting Digital Data Packets and Device Implementing the Method and Receiver
US7539187B2 (en) * 2004-07-07 2009-05-26 Qvidium Technologies, Inc. System and method for low-latency content-sensitive forward error correction
US7660245B1 (en) * 2004-09-16 2010-02-09 Qualcomm Incorporated FEC architecture for streaming services including symbol-based operations and packet tagging
US7738501B2 (en) * 2005-04-15 2010-06-15 Zarlink Semiconductor, Inc. Method of recovering timing over a granular packet network

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5369682A (en) * 1992-08-17 1994-11-29 Glenayre Electronics, Inc. Digital simulcast transmission system
US6681362B1 (en) * 2000-03-06 2004-01-20 Sarnoff Corporation Forward error correction for video signals
US20080250299A1 (en) * 2004-04-29 2008-10-09 Arnaud Maillet Method of Transmitting Digital Data Packets and Device Implementing the Method and Receiver
US7539187B2 (en) * 2004-07-07 2009-05-26 Qvidium Technologies, Inc. System and method for low-latency content-sensitive forward error correction
US7660245B1 (en) * 2004-09-16 2010-02-09 Qualcomm Incorporated FEC architecture for streaming services including symbol-based operations and packet tagging
US20100050057A1 (en) * 2004-09-16 2010-02-25 Qualcomm Incorporated Fec architecture for streaming services including symbol based operations and packet tagging
US7738501B2 (en) * 2005-04-15 2010-06-15 Zarlink Semiconductor, Inc. Method of recovering timing over a granular packet network
US20080219151A1 (en) * 2007-03-07 2008-09-11 Nokia Corporation System and method for using a peer to peer mechanism to repair broadcast data in wireless digital broadcast networks

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Moon et al, Bit Rearrangement for MIMO Retransmissions, 2007, IEEE, pp 3509-3513. *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130007552A1 (en) * 2011-06-30 2013-01-03 Brother Kogyo Kabushiki Kaisha Data processing devices, computer readable storage media, and methods
US8843809B2 (en) * 2011-06-30 2014-09-23 Brother Kogyo Kabushiki Kaisha Data processing devices, computer readable storage media, and methods

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