WO2000038098A1 - Historique synthetique pour une compression de donnees adaptative - Google Patents

Historique synthetique pour une compression de donnees adaptative Download PDF

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Publication number
WO2000038098A1
WO2000038098A1 PCT/US1999/029944 US9929944W WO0038098A1 WO 2000038098 A1 WO2000038098 A1 WO 2000038098A1 US 9929944 W US9929944 W US 9929944W WO 0038098 A1 WO0038098 A1 WO 0038098A1
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WIPO (PCT)
Prior art keywords
data
synthetic history
type
received
compressing
Prior art date
Application number
PCT/US1999/029944
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English (en)
Inventor
Nir Kalkstein
Talmon Marco
Original Assignee
Expand Networks Ltd.
Friedman, Mark, M.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Expand Networks Ltd., Friedman, Mark, M. filed Critical Expand Networks Ltd.
Priority to AU31238/00A priority Critical patent/AU3123800A/en
Publication of WO2000038098A1 publication Critical patent/WO2000038098A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M7/00—Conversion of a code where information is represented by a given sequence or number of digits to a code where the same, similar or subset of information is represented by a different sequence or number of digits
    • H03M7/30—Compression; Expansion; Suppression of unnecessary data, e.g. redundancy reduction

Definitions

  • the present invention relates to data compression and, more specifically, to compressing and decompressing data using pre-defined history-related information.
  • Data compression algorithms convert data defined in a given format to another format so that the resulting format contains fewer data bits (i.e., the ones and zeros that define digital data) than the original format. Hence, the data is compressed into a smaller representation. When the original data is needed, the compressed data is decompressed using an algorithm that is complementary to the compression algorithm.
  • Data compression techniques are used in a variety of data processing and data networking applications.
  • Personal computer operating systems use data compression techniques to reduce the size of data files stored in the hard disk drives of the computer. This enables the operating system to store more files on a given disk drive.
  • Data networking equipment use data compression techniques to reduce the amount of data sent over a data network. For example, when a web browser retrieves a file from a web server, the file may be sent over the Internet in a compressed format. This reduces the transmission time for sending the file and reduces the usage of the network, thereby reducing the cost of transmission.
  • a dictionary typically is derived from the data according to a selected scheme relating to various statistical information gathered therefrom, such as the frequencies of certain patterns in the data. For example, the length of the bit representation in the encoding table for each of the encoded data patterns may be selected so that it is inversely related to the frequency of occurrence of the corresponding patterns.
  • text refers to a stream of data bits which is provided as a unit to the compression algorithm and includes, but is not limited to, word data from a document, image data and other types of data.
  • the text can have features or characteristics such as internal patterns of data.
  • Static compression algorithms use static dictionaries. That is, the algorithms do not affect, update or otherwise change the dictionary for a given unit of text.
  • Dynamic compression algorithms constantly update or change the dictionary according to features or characteristics of the text based on a selected scheme.
  • semi-static compression algorithms the dictionary is occasionally updated or changed according to the text based on a selected scheme.
  • adaptive compression algorithm refers to a dynamic or semi-static algorithm in which the history is either constantly or occasionally updated or changed according to data pattern variations encountered in the text.
  • the dictionary is commonly referred to as a history.
  • the history is a representation of some or all of the data that has been processed by the compression algorithm.
  • An example using the text "when and where is to be determined” (underlining added) is illustrative.
  • the compression algorithm checks each string of data to determine whether that string already appears in the history. Thus, when the compression algorithm reaches the underlined "whe", the string "when” is already in the history. As a result, the compression algorithm can reference (and, consequently, compress) the first the letters of "where". From the above, it may be observed that the compression ratio for the text depends on the number of matches that are found in the history and on the length of the matched terms (given that a long term may be represented by a relatively short representation).
  • the data in the history may consist of ordinary text (as in the example above).
  • the history may consist of more sophisticated representations such as hash data or a linked list data.
  • Adaptive algorithms have a number of advantages. For example, these algorithms permit the history be adjusted to best reflect the data patterns in the text. Thus, adaptive algorithms have, in essence, a "learning" capability. Furthermore, the history need not necessarily be transmitted along with the encoded data, but rather can be fully rebuilt at the receiving end from the encoded data during decompression. Thus, this class of techniques is particularly well suited for data compression in a communication system. Examples of adaptive data compression techniques include the well-known Lempel-Ziv algorithms known, respectively, as LZ77 and LZ78, for constructing the encoding table (Ziv J., Lempel A.: A universal algorithm for sequential data compression, IEEE Transactions on Information Theory, Vol IT-23, (1977) pp. 337-343; Ziv J., Lempel A.: Compression of individual sequences via variable rate coding, IEEE Transactions on Information Theory, Vol IT-24, (1978) pp. 530-536).
  • the adaptive compression scheme of the present invention provides preliminary history data that is available when compression is commenced on a given text.
  • This preliminary history data is generated from pre-defined history-related information referred to herein as synthetic history data.
  • the method of the invention increases the probability that there will be an increased number of matches between the text and the history file data during the compression process. In particular, more matches may occur for the portion of the data in the text that is processed during the early stages of the compression process.
  • This advantage of the invention may be better understood by comparison with conventional adaptive compression techniques that commence compressing a given text with an empty history file.
  • conventional adaptive compression techniques that commence compressing a given text with an empty history file.
  • the data for the synthetic history files is defined based on an expected correlation between a given text to be compressed and a predefined body of text is related in some manner to the text to be compressed.
  • the synthetic history information consists of a "typical text.”
  • the compression algorithm processes the "typical text" to generate the preliminary history data.
  • a target text of a given type e.g., HTML
  • the associated, pre-defined "typical text” is compressed before compressing the target text.
  • the compressed data that results from the typical text is discarded. This eliminated the need, for example, to transmit this data to a remote equipment where the compressed target text is to be decompressed.
  • the decompression algorithm When the compressed target text is to be decompressed, the decompression algorithm performs steps complementary to those described above. Specifically, the decompression algorithm first decompresses a compressed "typical text" thereby creating a preliminary history. Next, the decompression algorithm decompresses the compressed target text using the preliminary history. The decompressed text that results from the compressed "target text” is then discarded. Thus, the decompression stage produces an accurate replica of the original target text.
  • the invention is implemented in a pair of devices installed in a data network such as the Internet.
  • the devices may be installed between a pair of routers that define an IP hop.
  • the device on the sending end of the hop intercepts each packet that the router sends over the hop and determines whether that packet contains a type of text that may be compressed using synthetic history.
  • the device on the other end of the hop also intercepts each incoming packet and determines whether that packet was compressed using synthetic history. If so, the packet is decompressed using synthetic history.
  • FIGURE 1 is a block diagram of one embodiment of a data compression and decompression system in accordance with the invention
  • FIGURE 2 is a flowchart of operations that may be performed by a compression system implemented according to the invention
  • FIGURE 3 is a flowchart of operations that may be performed by a decompression system implemented according to the invention.
  • FIGURE 4 is a block diagram of one embodiment of a computer configured to perform compression and/or decompression methods according to the invention
  • FIGURE 5 is a block diagram of one embodiment of a data network system incorporating compression and decompression in accordance with the invention
  • FIGURE 6 is a block diagram of another embodiment of a data network system incorporating compression and decompression in accordance with the invention.
  • FIGURE 1 is a block diagram of a data compression system C (top half of FIGURE 1) and a data decompression system D (bottom half of FIGURE 1) in accordance with one embodiment of the invention.
  • a first processor 20 executes a data compression program 22 that uses synthetic history to compress input data.
  • the compressed data is sent to a second processor 26.
  • the second processor 26 executes a data decompression program 28 that uses synthetic history to decompress the compressed data.
  • FIGURE 1 is a flowchart of one embodiment of operations that may be performed by the data compression stage C.
  • FIGURE 3 is a flowchart of one embodiment of operations that may be performed by the data decompression stage D.
  • the method of FIGURE 2 commences at block 100.
  • synthetic history data is created for each data type that is to be compressed using synthetic history compression (block 102).
  • the synthetic history data for the data types is stored in one or more synthetic history data files 30 in a data memory 32.
  • the data to be compressed may represent various information including, for example, conventional character text, image data, video data or audio data.
  • much of this data may be classified as a particular data type; for example, language type (French, English, etc.) or document type (electronic mail, JAVATM, HTML documents, executable code, etc.).
  • the synthetic history file 30 for a given data type contains a collection of characters and strings that are likely to appear in data of that type.
  • the synthetic history data (e.g., the "typical data") for a given data type may be chosen using statistical methods. For example, character or string probabilities for a given type may be generated by analyzing a large number of files of that type.
  • the processor 20 receives input data from an input data source 34 (block 104).
  • input data source 34 may be a conventional data memory such as a disk drive or random access memory (RAM).
  • streaming data the input data source 34 may be a data interface device that receives, for example, streaming packet data from a data network.
  • a data type identifier routine 36 analyzes either the input data or information associated with the input data to ascertain the data type of the input data. For example, in the first case the data type identifier 36 may perform a relatively fast analysis of the input data. This may involve searching for strings that commonly appear at the beginning of particular documents. For example, an e-mail file may contain headers such as "From" and "To". A MicrosoftTM WordTM document may contain a common signature such as "WordDocument". Alternatively, the identification process may involve searching for a word that is very likely to appear in one language, but not in other languages.
  • the data type identifier 36 ascertains the TCP port to which the incoming packet data is associated by analyzing the header information in the packet.
  • TCP ports are defined by the TCP/IP protocol that is used by many applications to route data over the
  • the TCP port number may be used to identify a data type when it is known that a specific type of file typically originates from a particular TCP source port.
  • the compression device may be configured to compress data originating from a particular server. That is, all traffic from the server may be routed through the compression device. In this case, it may be possible to predict the types of data that typically are sent by the server on a particular TCP port. From the above, it should be understood that many other methods of data type identification may be used in practicing the invention.
  • a data selector function 38 retrieves the associated "typical data” (i.e., the synthetic history data ) from the data memory 32 (block 108).
  • the data compressor 22 compresses the "typical data” (block 110) and discards the resulting compressed data (block 112).
  • the resulting history data (preliminary history data) is stored in a history file 40 that will be used during the compression of the input data.
  • the history file 40 has been pre-loaded with history data representative of the "typical data" for the input data type.
  • the input data may now be compressed using the preliminary history (block 1 14).
  • the data compressor 22 uses a Lempel-Ziv compression method. It should be understood, however, that other methods of data compression such as adaptive Huffman coding may be used in practicing the invention.
  • a reference is associated with the compressed data. This reference is used by the decompression stage D to determine which synthetic history to use when decompressing the compressed data.
  • the reference may identify the data type. In the Internet example discussed above, the reference may be inserted into the header of a packet within which the compressed data is transmitted.
  • the processor 20 sends the compressed data to an output data destination 42 and the process ends at block 120.
  • the destination 42 for the output data may be, for example, a date file or a data stream.
  • the output data destination 42 may comprise, for example, a data memory or a data interface device as described below in conjunction with FIGURES 4, 5 and 6.
  • the output data includes only the compressed input data and, if applicable, the reference.
  • the output data need not include the compressed "typical data” or the history data.
  • a decompression method is described beginning at block 150.
  • synthetic history data is created for each data type that is to be decompressed using a synthetic history. This step is performed in a similar manner as described above in conjunction with block 102, except that the "typical data" is pre-compressed using a compression algorithm that is compatible with the algorithm used by the data compressor 22 described above.
  • the decompressor's synthetic history data files 44 contain "typical compressed data.”
  • the processor 26 receives compressed input data from an input data source 46 (block 154).
  • an input data source 46 may comprise components similar to those discussed above.
  • a data type identifier routine 48 analyzes the compressed input data or information associated with the input data to determine the data type of the input data. For example, the data type identifier 48 may determine the data type by reading a reference that was sent with the data as discussed above in conjunction with block 116.
  • a data selector function 50 retrieves the associated "typical compressed data" (i.e., the synthetic history data) from the data memory 52 (block 158).
  • the data decompressor 28 decompresses the "typical compressed data” (block 160) and discards the resulting decompressed data (block 162).
  • the resulting history data (preliminary history data) is stored in a history file 54 that will be used during the decompression of the input data.
  • the history file 54 has been pre-loaded with history data representative of the "typical compressed data" for the input data type.
  • the data decompressor 28 uses the preliminary history to decompress the compressed input data. To this end, the data decompressor 28 uses a decompression algorithm that is complementary to the compression algorithm used by the data compressor 22.
  • the processor 26 sends the decompressed data (which is a replica of the original data) to an output data destination 56 and the process ends at block 168.
  • the destination for the output data may be, for example, a data file or a data stream.
  • the output data destination 56 may comprise components similar to those discussed above.
  • the synthetic history data used by the data compressor 22 may comprise actual history data.
  • the "typical data” is not stored in the synthetic history data file 30 as discussed above in conjunction with block 102 in FIGURE 2. Instead, the history data that would result from the compression of the "typical data” is stored in the synthetic history data file 30.
  • This history data may be generated, for example, by explicitly defining the history data or by actually compressing the "typical data". In the latter case, the history data is saved and the compressed "typical data" discarded.
  • the step of selecting the typical data may simply involve copying the history data from the synthetic history data file (e.g., file 30) to the history file that is used for compressing the input data (e.g., file 40).
  • the real-time steps of compressing the "typical data" (block 110) and discarding the compressed "typical data” (block 112) are omitted.
  • the decompression process may be modified in a similar manner.
  • the synthetic history data used by the data decompressor 28 may comprise actual history data.
  • the history data that would result from the decompression of the "typical compressed data” may be stored in the synthetic history data file 44.
  • This history data may be generated, for example, by explicitly defining the history data or by actually decompressing the "typical compressed data". In the latter case, the history data is saved and the decompressed "typical compressed data" discarded.
  • the step of selecting the typical data may simply involve copying the history data from the synthetic history file (e.g., file 44) to the history file that is used to decompress the input data (e.g., file 54).
  • the real-time steps of decompressing the "typical compressed data" (block 160) and discarding the decompressed "typical compressed data" (block 162) are omitted.
  • synthetic history data may include, for example, data that may be used to generate history data, actual history data that is the product of a compression or decompression operation, or predefined history data.
  • synthetic history data (such as the compressed "typical text") may be sent from the data compressor stage C to the data decompressor stage D.
  • the steps described in blocks 112, 1 16, 152, 156 and 158 may be omitted because the data decompressor 28 may simply use the compressed "typical text" (generated at block 110) at block 160.
  • this technique may be less efficient than the previously described techniques in many applications. Nevertheless, it should be understood from the above that many adaptations involving the use of synthetic histories are possible in practicing the invention.
  • FIGURE 4 illustrates some of the components that may be incorporated into a device 200 that performs data compression and/or data decompression in accordance with the invention.
  • a processor 202 executes program code (not shown) stored in a program memory 204 to perform, for example, the methods described herein in conjunction with FIGURES 1-3 and 5-6.
  • the program memory 204 comprises a read only memory (ROM) device or a semi-permanent data memory such as a flash memory.
  • the computer 200 also includes at least one storage memory 206 for storing dynamic data.
  • the storage memory 206 comprises a random access memory (RAM) device or a disk drive.
  • RAM random access memory
  • the program code may be pre-loaded into the program memory 204, for example, at the factory. Alternatively, in embodiments that are connected to a data network such as the Internet, the program may be downloaded from a server via the data network. In another embodiment, the program code may be stored on a removable media 208 such as a CD-ROM or a floppy disk. In this case the computer 200 would include a removable media drive 210 such as CD-ROM drive or a floppy disk drive. The program code may then be downloaded into the program memory 204 or, in some cases, accessed directly by the processor 202 from the removable media 208.
  • One or more data interfaces 212 may enable the computer 200 to send or receive data to or from external devices (not shown). This data may include the program data, the original data, the compressed data or the decompressed data. Examples of data interfaces 212 include serial or parallel ports, bus interfaces, or data network interfaces. The data network example is discussed in more detail below in conjunction with FIGURE 5 and 6.
  • the teachings of the invention may be used for file compression schemes that attempt to use disk drive space more efficiently by storing data in a compressed format on the system disk drive.
  • Such a scheme may be used, for example, by a computer operating system and implemented in the embodiment of FIGURE 4 in the following manner.
  • the computer 200 includes an operating system installed in the program memory 204 and executed by the processor 202.
  • the operating system incorporates the synthetic history compression and decompression functions as treated herein.
  • the operating system may compress files before they are saved to the system hard disk drive (e.g., storage memory 206).
  • the operating system may decompress files after they are read from the system hard disk drive.
  • FIGURE 5 illustrates one embodiment of the invention that compresses streaming data on-the-fly.
  • the invention is employed in equipment installed in a path in a data network.
  • this equipment incorporates features and functional elements similar to those of the embodiments described above to accomplish data compression and decompression using synthetic histories.
  • Packet-based data networks transfer information between computers and other equipment using a data transmission format known as packetized data.
  • the stream of data from a data source e.g., a host computer
  • the stream of data from a data source is divided into variable or fixed length "chunks" of data (i.e., packets).
  • Switches e.g., routers
  • the network route the packets from the source to the appropriate data destination.
  • the packets may be relayed through several routers before they reach their destination. Once the packets reach their destination, they are reassembled to regenerate the stream of data.
  • IP IP --Protocol
  • IP defines procedures for routing data through a network. To this end, IP specifies that the data is organized into frames each of which includes an IP header and the associated data. The routers in the network use the information in the IP header to forward the packet through the network. In the IP vernacular, each router-to-router (or switch-to-router, etc.) link is referred to as a hop.
  • a router 220 at one end of a hop in the network sends packets to another router 222 at the other end of the hop.
  • Some of the packets sent over the hop may be associated with data types that can be compressed using pre-defined synthetic histories (not shown).
  • a compressor 224 compresses the data in these packets using the synthetic histories.
  • a decompressor 226 decompresses the data in the compressed packets using pre-defined synthetic histories.
  • the link between the routers 220 and 222 may be either a permanent or temporary link. The link may be used to transfer unmodified layer 3 protocol packets.
  • Layer 3 is a network layer protocol and encompasses, for example, the Internet Protocol ("IP”) and those that conform to the OSI ("Open System Interconnection") reference model.
  • IP Internet Protocol
  • the compressor 224 processes an inbound stream of packets from the router 220.
  • One or more network interfaces 228 in the compressor terminates the packet protocols and provides the packet data to a processor 230.
  • the devices i.e., the compressor 224 and the decompressor 226) are installed between the routers 220 and 222 as illustrated in FIGURE 1
  • the network interface 228 connects to a wide area network (“WAN") as described above.
  • the compressor 224 may be installed farther up the link (i.e., before the router 220).
  • the network interface 228 may connect to a local area network (“LAN”).
  • LAN local area network
  • the network interface 228 in the latter type of system will include a LAN-type interface such as an Ethernet interface.
  • the processor 230 performs data compression and other processes such as those as described above in conjunction with FIGURES 1 , 2 and 4. To reduce the complexity of FIGURE 5, the data memories and other components associated with the processor 230 are not depicted.
  • the processor 230 After the processor 230 compresses the input data, the processor 230 sends the packets to the network interface 228.
  • the network interface 228 processes the packet data and provides the appropriate physical and data link layers to interface to the network (as represented by line 232).
  • the compressor 224 In practice, separate input and output network interface components may be used in the compressor 224.
  • the details of the operation and implementation of the network interfaces 224 as described are well known in the IP data networking art. Accordingly, these aspects of the compressor 224 will not be treated in detail here.
  • a network interface 234 terminates the physical and data link layers and provides network layer (IP) packets to a processor 236.
  • IP network layer
  • the processor 236 in the decompressor 226 performs data decompression and other processes such as those as described above in conjunction with FIGURES 1 , 3 and 4. To reduce the complexity of FIGURE 5, the data memories and other components associated with the processor 236 are not depicted.
  • the processor 236 After the processor 236 decompresses the input data, the processor 236 sends the packets to the network interface 234.
  • the network interface 234 processes the packet data and provides the appropriate physical and data link layers to interface to the network. The data is then forwarded to the router 222.
  • FIGURE 6 illustrates an embodiment in which the compression and decompression methods of the invention are integrated as software modules in devices 240 that are installed at each end of a predefined path in a network.
  • the devices 240 may be routers, bridges, switches, modems or any other device in the network that handles packet traffic.
  • the packet compression and decompression operations performed by the embodiment of FIGURE 6 are similar to those described above in conjunction with FIGURES 2-5.
  • Compression software modules 242 and decompression software modules 244 are linked to software modules 246 in the devices in a manner that enables the compression software modules 242 and the decompression software modules 244 to intercept and process packets routed through the devices 240.
  • other components in the devices 240 such as data memories and network interfaces are not depicted.
  • the compression and decompression software modules 242 and 244 may be implemented along the transmission path in a device 240 where the packets are fully visible. For example, some of the packets flowing through the network may be encrypted. Thus, the compressor and decompressor software modules 242 and 244 may be linked in to the device modules 246 so that the compression and decompression software modules 242 and 244 have access to decrypted data.
  • the compression and decompression modules 242 and 246 are installed on both sides of a duplex link. Accordingly, packet traffic traveling in either direction on the link may be compressed according to the invention.
  • FIGURE 6 also illustrates that the invention may be used on more than a single IP hop.
  • the packets are routed through a network 248 (e.g., the Internet) and, as a result, they may be routed over several hops.
  • appropriate routing provisions should be made to ensure that all compressed packets are routed to the same receive module at the other end of the path. This may include, for example, defining static routes using IP tunneling.
  • various initialization procedures may be performed. For example, all history files may be erased and various compression parameters may be exchanged between a paired compressor and decompressor. In the data networking embodiments, these initialization procedures may be accomplished using a relatively simple three- way handshake such as the one used in TCP. From the above, it may be seen that the invention provides an improved method of compressing data and increasing data throughput in a network. In many applications, a system or method constructed or implemented according to the invention will find history data that matches the data being compressed earlier in the compression process than conventional compression methods. As a result, data can be compressed more quickly and to a higher degree of compression.
  • a system or method constructed or implemented according to the invention may provide significantly higher compression ratios for relatively small data files (e.g., files smaller that ten kilobytes). While certain specific embodiments of the invention are disclosed as typical, the invention is not limited to these particular forms, but rather is applicable broadly to all such variations as fall within the scope of the appended claims. To those skilled in the art to which the invention pertains many modifications and adaptations will occur.
  • the devices may be installed at various locations within the network.
  • the invention may be implemented using a variety of hardware and software architectures.
  • the teachings of the invention are applicable to numerous compression algorithms and compression history techniques in addition to those described above.
  • the system and methods of the invention may be used to compress and decompress various types of data. Also, many techniques for identifying data types may be used.
  • the specific structures and methods discussed in detail above are merely illustrative of a few specific embodiments of the invention.

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Abstract

Selon l'invention, des données sont comprimées (20) et décomprimées (28) au moyen de données historiques synthétiques (30). Ces données historiques synthétiques sont utilisées pour fournir des données historiques préliminaires à un compresseur de données et un décompresseur de données, au début des opérations de compression et de décompression des données, respectivement. Plusieurs historiques synthétiques peuvent être définis et associés individuellement à un type de données prédéterminé. Les type des données à comprimer peut être établi avec précision afin de déterminer quel historique synthétique doit être utilisé pour ces données. Les données historiques synthétiques peuvent être constituées de 'texte typique' contenant des chaînes de caractères susceptibles d'apparaître dans un document d'un certain type. Ce 'texte typique' est comprimé pour fournir les données historiques préliminaires.
PCT/US1999/029944 1998-12-22 1999-12-16 Historique synthetique pour une compression de donnees adaptative WO2000038098A1 (fr)

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Cited By (2)

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WO2002041098A2 (fr) * 2000-11-16 2002-05-23 Telefonaktiebolaget Lm Ericsson (Publ) Systeme et procede de communication pour une compression de contexte partage
CN102314697A (zh) * 2011-07-20 2012-01-11 张行清 基于数据类型的数值型数据压缩及解压缩方法

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US5293379A (en) * 1991-04-22 1994-03-08 Gandalf Technologies, Inc. Packet-based data compression method
US5896403A (en) * 1992-09-28 1999-04-20 Olympus Optical Co., Ltd. Dot code and information recording/reproducing system for recording/reproducing the same

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
US5293379A (en) * 1991-04-22 1994-03-08 Gandalf Technologies, Inc. Packet-based data compression method
US5896403A (en) * 1992-09-28 1999-04-20 Olympus Optical Co., Ltd. Dot code and information recording/reproducing system for recording/reproducing the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002041098A2 (fr) * 2000-11-16 2002-05-23 Telefonaktiebolaget Lm Ericsson (Publ) Systeme et procede de communication pour une compression de contexte partage
WO2002041098A3 (fr) * 2000-11-16 2002-11-14 Ericsson Telefon Ab L M Systeme et procede de communication pour une compression de contexte partage
US6950445B2 (en) 2000-11-16 2005-09-27 Telefonaktiebolaget Lm Ericsson (Publ) Communication system and method for shared context compression
CN102314697A (zh) * 2011-07-20 2012-01-11 张行清 基于数据类型的数值型数据压缩及解压缩方法
CN102314697B (zh) * 2011-07-20 2013-04-10 张行清 基于数据类型的数值型数据压缩及解压缩方法

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