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`(12) United States Patent
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`US 6,920,150 B1
`(10) Patent N0.:
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`Pauls et al.
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`(45) Date of Patent: Jul. 19, 2005
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`USOO6920150B1
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`(54) ADAPTIVE COMMUNICATIONS
`TRANSCODING AND ERROR CONTROL
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`(75)
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`Inventors: Richard Joseph Pauls, Newton, NJ
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`(US); Michael Charles Recchione,
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`Nutley, NJ (US)
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`(73) Assignee: Lucent Technologies Inc., Murray Hill,
`NJ (US)
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`( * ) Notice:
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`Subject to any disclaimer, the term of this
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`patent is extended or adjusted under 35
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`U.S.C. 154(b) by 823 days.
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`(22)
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`(21) Appl. No.: 08/940,760
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`Filed:
`Sep. 30, 1997
`(51)
`Int. Cl.7 ................................................... H04J 3/16
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`(52) US. Cl.
`........................................ 370/465; 714/752
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`(58) Field of Search ................................. 370/465, 466,
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`370/467; 714/746, 752, 758, 759, 761,
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`762
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`(56)
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`JP
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`JP
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`JP
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`JP
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`WO
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`References Cited
`U.S. PATENT DOCUMENTS
`
`
`
`2/1996 Phillips et 211.
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`OTHER PUBLICATIONS
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`............ 370/465
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`............ H04N/7/16
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`puting Machinery.
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`Point—To Multipoint Communications.” Aug. 1, 1994; vol.
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`E77B ; p. 1013—1022; IEICE Transactions On Communi-
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`cations.
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`Han R. et a1.: “Dynamic Adaptation In An Image Transcod-
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`ing Proxy For Mobile Web Browsing.” Dec.1, 1998; vol. 5
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`p. 8—17; IEEE Personal Communications.
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`Kentarou Fukuda et a1., “The relationship bdetween QoS
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`parameters and requierd bandwidth in MPEG—2 video”,
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`1997, Department of Informatics and Matematical Science.
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`Hui Zhao, Toru Sato, and Iwane Kimura, “New Go—Back—N
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`ARQ Protocols for Point—to—Multipoint Communications,”
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`IEICE Transactions on Communications, vol. E77—B, No. 8,
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`Tokyo, JP, Aug. 1994, pp. 1013—1022.
`
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`
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`Richard Han, Pravin Bhagwat, Richard LaMaire, Todd
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`Mumert, Veronique Perret, and Jim Rubas, IBM T. J. Watson
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`Research Center, “Dynamic Adaptation in an Image
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`Transcoding Proxy for Mobile Web Browsing,” IEEE Per-
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`
`
`sonal Communications, Dec. 1998, pp. 8—17.
`
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`* cited by examiner
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`Primary Examiner—Bob Phunkulh
`
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`(74) Attorney, Agent, or Firm—Jimmy G00
`
`
`ABSTRACT
`
`
`
`(57)
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`invention is a method for improving data
`The present
`
`
`
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`
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`transfer performance over communications networks con-
`
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`
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`necting data networks and users using adaptive communi-
`
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`
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`
`
`
`
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`cations formatting. Adaptive communications formatting
`
`
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`
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`includes encoding (or compressing) the data and applying
`error control schemes to reduce the amount of data being
`
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`transmitted and to correct and/or conceal errors occurring
`
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`
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`during data transmission. In one embodiment, the present
`
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`
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`
`
`invention uses a set of transcoding techniques to encode (or
`
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`
`
`
`
`compress) the data and a set of error control schemes to
`
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`
`
`
`
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`correct and/or conceal errors occurring during data trans-
`
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`mission. The particular sets of transcoding techniques and
`
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`
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`error control schemes selected to format the data are adap-
`
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`tive to factors, such as the nature of the communications
`
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`network connecting a user to an access server on the data
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`network, the preferences of the user, and the data type of the
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`data being transmitted to the user (or the access server).
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`35 Claims, 4 Drawing Sheets
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`34%
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`J
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`EHRDR WWI.
`van/ImE 1
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`VIED/IMABE 1
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`\ VIDEO/IMAGE 2
`THANSCODER
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`Page 1 of 10
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`GOOGLE EXHIBIT 1005
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`GOOGLE EXHIBIT 1005
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`Page 1 of 10
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`US. Patent
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`Jul. 19, 2005
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`Sheet 1 0f 4
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`US 6,920,150 B1
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`35 \
`FIG.
`1
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`COMMUNICATIONS
`
`NETWORK
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`NIREO/NIHELESS
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`COMMUNICATION
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`SYSTEM
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`HIRED/WIRELESS
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`COHHUNICATION
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`SYSTEM
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`COMMUNICATION
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`DEVICE
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`COMPUTER
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`FIG. 2
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`USER ID
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`comm INFO
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`ERROR
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`0m TYPE
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`ENgAOTDAEB
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`Page 2 of 10
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`US. Patent
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`Jul. 19, 2005
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`Sheetz 0f4
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`US 6,920,150 B1
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`US 6,920,150 B1
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`1
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`ADAPTIVE COMMUNICATIONS
`
`
`TRANSCODING AND ERROR CONTROL
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`
`BACKGROUND OF THE INVENTION
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`Subscribers of wireless communications systems are
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`increasing to phenomenal numbers with more than forty-five
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`million subscribers in the United States and one-hundred
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`and twenty million subscribers worldwide. As new service
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`providers enter the wireless communication market,
`the
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`level of competition for old service providers increases to
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`retain existing customer base while attracting new subscrib-
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`ers. To maintain continued growth of subscriber numbers
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`and revenue levels, service providers are offering value-
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`added services to their subscribers.
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`The Internet explosion has provided service providers of
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`wired and wireless communications systems with a direction
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`for developing value-added services. Currently, there are
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`more than fifty million users of the Internet. Access to the
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`Internet is typically via a wired communication network.
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`However, wired Internet access requires some type of physi-
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`cal connection between the users and the wired communi-
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`cations network. Thus, the mobility of users accessing the
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`Internet via a wired connection is severely limited. By
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`contrast, access to the Internet via a wireless communica-
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`tions system offers a great deal of mobility to users/
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`subscribers. However, wireless Internet access can be pro-
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`hibitively expensive to most users/subscribers. Specifically,
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`wireless communications systems, such as those based on
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`the GSM and IS-95 CDMA standards, are limited in air
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`interface access speeds (i.e., narrow bandwidth) and are
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`subjected to an error prone transmission environment. For
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`example, data transmitted over an IS-95 CDMA based
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`wireless communication systems may be subject to a 3% or
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`more bit error rate. Such limitations increase the amount of
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`time required for successful data transfers between the
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`Internet and the user/subscriber which, in turn, increases the
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`cost of a wireless telephone call
`to the user/subscriber.
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`Accordingly, there exists a need to improve data transfer
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`performance (i.e., reduce transmission time) over commu-
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`nication networks connecting the Internet or other data
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`networks to the user/subscriber.
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`SUMMARY OF THE INVENTION
`
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`The present invention is a method for improving data
`
`
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`
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`transfer performance over communications networks con-
`
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`necting data networks and users using adaptive communi-
`
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`cations formatting. Adaptive communications formatting
`
`
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`
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`includes encoding (or compressing) the data and applying
`error control schemes to reduce the amount of data being
`
`
`
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`transmitted and to correct and/or conceal errors occurring
`
`
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`during data transmission. In one embodiment, the present
`
`
`
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`
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`
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`invention uses a set of transcoding techniques to encode (or
`
`
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`compress) the data and a set of error control schemes to
`
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`correct and/or conceal errors occurring during data trans-
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`mission. The particular sets of transcoding techniques and
`
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`error control schemes selected to format the data are adap-
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`tive to factors, such as the nature of the communications
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`network connecting a user to an access server on the data
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`network, the preferences of the user, and the data type of the
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`data being transmitted to the user (or the access server).
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`The features, aspects, and advantages of the present
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`invention will become better understood with regard to the
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`following description, appended claims, and accompanying
`drawings where:
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`FIG. 1 depicts an architecture for a system for accessing
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`a data network in accordance with the present invention;
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`FIG. 2 depicts a bitstream entering and exiting the access
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`server;
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`FIG. 3 depicts a functional block diagram of the access
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`server in accordance with one embodiment of the present
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`invention;
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`FIG. 4 depicts a table for selecting transcoding techniques
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`and error control schemes to use to format data; and
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`FIG. 5 depicts a chart illustrating examples transcoding
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`techniques and error control schemes which might be used
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`for transmission of particular data types over wireless con-
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`nections.
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`DETAILED DESCRIPTION
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`FIG. 1 illustrates an architecture for a system 10 for
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`accessing a data network in accordance with the present
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`invention. The system 10 comprises a data network 12 (e.g.,
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`the Internet), a user 14, and a communications network 16.
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`The communications network 16 comprises a plurality of
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`wired and/or wireless communications systems for provid-
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`ing a wired and/or wireless connection between the data
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`network 12 and the user 14. Wired communications systems
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`include Public Switching Telephone Networks (PSTN), and
`networks based on Integrated Services Digital Network
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`(ISDN), T1 lines and E1 lines. Wireless communications
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`systems include those based on Frequency Division Mul-
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`tiple Access (FDMA), Time Division Multiple Access
`(TDMA) and Code Division Multiple Access (CDMA). The
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`data network 12 comprises a plurality of interconnected
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`computers including at least one access server 20 and at least
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`one host 22. The access server 20 is a computer associated
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`with a service provider to which the user 14 subscribes for
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`accessing the data network 12. The host 22 is a computer
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`having data sought by the user 14. The access server 20 and
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`the host 22 may also be the same computer.
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`The user 14 comprises a communication device 24 (e.g.,
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`telephone, mobile-telephone and/or modem) for receiving
`and transmitting data from and to the access server 20 via the
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`communications network 16, and a remote computer 26
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`having software for processing data for transmission to the
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`access server 20 or for display on an output device associ-
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`ated with the remote computer 26, such as a video display,
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`an audio display, a printer, memory, etc. The user 14 gains
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`access to the data network 12 through the access server 20.
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`Specifically, the user 14 dials a number associated with the
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`access server 20. The communication network 16 connects
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`the user 14 to the access server 20 using the dialed number.
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`Upon connecting to the access server 20, the user 14 can
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`retrieve data from the host 22.
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`In general, data (being retrieved by the user) may be in the
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`form of a file or an output of a real time recording device,
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`such as a video camera, microphone, scanner, fax, transduc-
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`ers or measuring devices. In all cases, the data will have
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`associated information indicating a data type for the data.
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`For purposes of discussion, the present invention will be
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`described herein as retrieving data in the form of a file from
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`the host 22. It should not be construed, however, to limit the
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`present invention to retrieving data in the form of a file.
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`The data (or file) is retrieved via a bitstream from the host
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`22 to the access server 20 to the user 14. The bitstream
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`includes the data and control information. The data has
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`associated a filename with a file extension indicative of a
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`data type (and/or sub-type). The control
`information
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`includes a user indicator for identifying the user to whom the
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`data is intended, error control information for correcting
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`and/or concealing errors occurring during data transmission,
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`and/or a data type indicator to identify the data type of the
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`Page 6 of 10
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`US 6,920,150 B1
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`3
`associated data. Data types include, but are not limited to,
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`speech/voice, video/image and text. Each data type has one
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`or more sub-types. Examples of speech/voice sub-types (and
`file extensions) include audio (.au), wave (.wav) and speech
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`(.sp). Examples of video/image sub-types include tagged
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`image format files (.tif), graphic image format files (.gif),
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`Moving Picture Experts Group files (.mpg and .mp2).
`Examples of text sub-types include MS Word (.doc) and
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`ASCII (.txt).
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`Adaptive Communications Formatting
`At the access server 20, the data is formatted using a
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`mixture of transcoding techniques and error control schemes
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`to facilitate data transmission within acceptable quality
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`levels, as will be described herein. FIG. 2 illustrates a
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`bitstream 23 entering and a bitstream 25 exiting the access
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`server 20. When the bitstream 23 arrives at the access server,
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`the bitstream 23 includes the data and user indicator-control
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`information for identifying the user to whom the data is
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`intended. The data is formatted by the access server 20 and
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`transmitted to the user 14 via the bitstream 25, which
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`includes encoded data, error control information for con-
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`trolling and/or concealing errors resulting from data
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`transmission, and data type indicator-control information for
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`identifying the data type of the associated (encoded) data, as
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`will be described herein.
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`Transcoding techniques include encoding algorithms for
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`encoding (or compressing)
`the data. Encoding (or
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`compressing) the data facilitates data transmission by reduc-
`ing the amount of data to be transmitted which, in turn,
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`decreases the time required to transmit the data (i.e., trans-
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`mission time) from the access server to the user over a
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`transmission channel of limited bandwidth (i.e., slower
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`access speeds). Some encoding algorithms, however, have
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`associated loss that may adversely affect data quality. Alge-
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`braic Code Excited Linear Prediction (ACELP), Vector Sum
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`Excited Linear Prediction (VSELP), Enhanced Variable
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`Rate Coder (EVRC), h.263 (which is a set of guidelines
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`being considered by the International Telecommunications
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`Union for
`implementation into standards), pkzip (by
`PKWare,
`Inc.), MPEG and MPEG2 (Moving Pictures
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`Experts Group), and JPEG (Joint Pictures Experts Group)
`are some examples of encoding algorithms which are well-
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`known in the art. Each of the aforementioned encoding
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`algorithms have associated different levels or percentages of
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`compression.
`Error control schemes include techniques for correcting
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`and/or concealing errors occurring during the transmission
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`of data from the access server 20 to the user 14. Error control
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`schemes provide means for assuring data integrity has not be
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`compromised beyond acceptable levels. Some error control
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`schemes, however, increase data transmission time by add-
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`ing control information to the data and/or requiring retrans-
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`missions of the data when data error is detected. Forward
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`Error Correction (FEC), Cyclical Redundancy Check
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`(CRC), Automatic Retransmission Query (ARQ), hybrid
`ARQ (i.e., combination of ARQ and FEC) and error con-
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`cealment (e.g., muting, extrapolation from previous good
`frames, and interpolation from previous and succeeding
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`good frames) are some examples of error control schemes
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`which are well-known in the art. Each of the aforementioned
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`error control schemes have associated different levels of
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`error correction and/or concealment.
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`The particular transcoding techniques and error control
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`schemes used to format
`the data should be adaptive to
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`factors such as the nature of the communications network 16
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`connecting the user 14 to the access server 20, the prefer-
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`4
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`ences of the user 14, and the data type of the data, as will be
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`discuss herein. Note that the present invention should not be
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`limited to being adaptive to only the aforementioned factors.
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`Other factors, such as interactivity, bit rate and transmission
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`delay, may also be applicable.
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`First Factor
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`The first factor involves the nature of the communications
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`network 16 connecting the user 14 to the access server 20.
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`The nature of communications systems,
`in general
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`(regardless of whether the communication system is wired
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`or wireless), varies from one to another. The nature of
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`communications system depends on sub-factors such as
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`whether the communications system is wired or wireless,
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`whether the communications system is analog or digital, the
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`available bandwidth, the bit rate, the signal-to-noise ratio,
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`the bit error rate and the transmission delay, as will be
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`described herein.
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`the communications network 16
`As mentioned earlier,
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`comprises a plurality of wired and/or wireless communica-
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`tion systems for providing the user 14 with either a wired or
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`a wireless connection to the access server 20. For purposes
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`of discussion, a wireless connection involves using at least
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`one wireless communication system to connect the user 14
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`to the access server 20. By contrast, a wired connection
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`involves using no wireless communication system to con-
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`nect the user 14 to the access server 20. Wireless connec-
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`tions have several distinct disadvantages over wired con-
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`nections. First, the transmission times for data over wireless
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`connections are typically greater than the transmission times
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`for the same data over wired connections. The reasons for
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`this are because wireless connections generally have less
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`available bandwidth, lower bit rates and longer transmission
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`delays than wired connections. Therefore, it may be desir-
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`able to use a transcoding technique that will encode (or
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`compress) the data as much as possible to reduce the
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`transmission time over wireless connections (and perhaps
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`some wired connections). The benefits realized in facilitat-
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`ing data transmission should, however, be balanced against
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`losses associated with compression (or encoding).
`Second, data transmitted over a wireless connection is
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`more susceptible to data error than data transmitted over a
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`wired connections. The reasons for this are because wireless
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`connections generally have lower signal-to-noise ratios and
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`higher bit error rates than wired connections. Therefore, it
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`may be desirable to increase the amount of error control
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`being applied to data transmissions over wireless connec-
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`tions. The benefits of increased error control (i.e., increased
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`quality) should, however, be balanced against increased data
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`transmission time.
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`Second Factor
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`The second factor involves the preferences of the user 14.
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`The preferences of the user 14 should reflect the hardware
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`and software capabilities of the user 14 and the access server
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`20, and a balancing between facilitating data transfer and
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`acceptable data quality. The service provider and the sub-
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`scribers should agree on the manner in which the data is to
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`be formatted, i.e., agree on which transcoding techniques
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`and error control schemes to use. Whatever manner is used
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`by the access server 20 to format the data, the user 14 should
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`be able to un-format the formatted data. In other words, the
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`access server 20 should agree to use transcoding techniques
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`and error control schemes compatible with transcoding
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`techniques and error control schemes available at the user
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`14. Failure to use compatible transcoding techniques and
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`error control schemes will result in the user 14 receiving a
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`bitstream that it can not un-format. This agreement may be
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`Page 7 of 10
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`Page 7 of 10
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`US 6,920,150 B1
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`5
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`negotiated between the service provider and subscriber
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`before or at the time the user connects to the access server
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`20. Preferences of the user 14 should also reflect a balancing
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`by the user between facilitating data transfer and acceptable
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`data quality. For example, if the user 14 requires high quality
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`data, the user 14 might have to trade-off facilitating data
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`transfer for increased data quality. Thus, the user 14 might
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`select a transcoding technique with less compression and
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`minimal loss (e.g., pkzip) and an error control scheme with
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`greater error correction (e.g., ARQ) for formatting the data
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`at the access server.
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`Third Factor
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`The third factor is the data type of the data. Certain
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`transcoding techniques and error control schemes are more
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`effective when used to format particular data types. Thus, the
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`transcoding techniques and error control schemes selected to
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`format the data should be adaptive to the data type, as will
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`be described herein. Transcoding techniques include encod-
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`ing algorithms for encoding or compressing particular data
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`types: gzip and pkzip for text data; VCELP, ASELP and
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`EVRC for speech/voice data; and h.263 for video/image
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`data. Using a text transcoding technique (e.g., a transcoding
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`technique with gzip) to compress speech/voice data may not
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`be as effective as using a speech transcoding technique (e.g.,
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`a transcoding technique with VCELP) to compress the same
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`data—that is, the amount of data compression may not be
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`the same.
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`Error control schemes include techniques for different
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`levels of error correction and/or concealment. The level or
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`error correction and/or concealment applied to data should
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`depend on the amount of error tolerable by the user which,
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`in turn, depends on the data type. For example, errors in
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`audio/speech and video/image data types may be tolerable to
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`some extent. In such cases, errors in audio/speech data types
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`may best be concealed by muting, and errors in video/image
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`data types may best be concealed by interpolating from
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`previous good frames. By contrast, errors in text data types
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`may be intolerable. In this case, errors are corrected (not
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`concealed) by requesting retransmissions of the data, i.e.,
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`ARQ.
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`FIG. 3 is a functional block diagram of the access server
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`20 in accordance with one embodiment of the present
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`invention. The access server 20 comprises a data selector 30,
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`a plurality of text, speech/voice and video/image transcod-
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`ing techniques 32-11 (i.e., transcoding techniques for text,
`speech/voice and video/image data types), a plurality of text,
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`speech/voice and video/image error control schemes 34-n
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`(i.e., error control schemes for text, speech/voice and video/
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`image data types) and a combiner 38 for multiplexing
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`formatted data. The data selector 30 is a device, such as a
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`microprocessor with software, for selecting a transcoding
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`technique 32-11 and an error control scheme 34-11 for for-
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`matting the data. The transcoding technique 32-11 and error
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`control scheme 34-11 is selected using the data type,
`the
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`identity of the user, and/or a user table 40 specifying user
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`preferences (i.e., transcoding techniques and error control
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`schemes preferred by each user for each data type and/or
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`sub-type). The data selector 30 can determine the data type
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`using the file extension, other information contained within
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`the bitstream, default data types and/or a combination of the
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`aforementioned. For example,
`the data selector 30 may
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`determine data with .wav file extensions are speech/voice
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`data types. The data selector 30 can determine the identity of
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`the user using the user indicator-control information (in the
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`bitstream). Note that FIG. 3 shows an one-on-one correla-
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`tion between the transcoding techniques and error control
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`schemes. This should not, however, be construed to limit the
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`65
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`6
`present invention to embodiments with such a correlation.
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`One-to-many correlation between transcoding techniques
`and error control schemes, or vice-versa, are also possible.
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`FIG. 4 illustrates an example of a user table 40. The
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`transcoding techniques and error control schemes in the
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`table 40 specified for each user and data type (and/or
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`sub-type) should reflect the aforementioned factors, i.e., the
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`nature of the communications network connecting the user
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`to the access server, the equipment and software capabilities
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`and/or preferences of the user and the access server, and the
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`data type of the data. For example, suppose user number
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`000001 connects to the access server using a wireless
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`connection. The table 40 specifies for user number 000001
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`a set of transcoding techniques and error control schemes for
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`each data type (and/or sub-type) that are available to both
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`user number 000001 and the access server and will facilitate
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`data transmission within acceptable quality levels over a
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`wireless connection. By contrast, user number 000222 is
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`connected to the access server 20 via a wired connection.
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`For users connected via a wired connection (e.g., user
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`number 000222), the table 40 specifies no formatting (i.e.,
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`no transcoding techniques or error control schemes) because
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`wired connections (with broader bandwidths) are less prone
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`to error than narrower bandwidth wireless connections.
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`Note that the present invention should not be limited to
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`using the table 40 depicted in FIG. 4. Other types of tables
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`or collections of information, such as databases, may also be
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`used to specify transcoding techniques and error control
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`schemes for formatting data intended for particular users.
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`Other information may also be stored in the table, such as an
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`indication whether the user is connected via a wired or
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`wireless connection, or separate sets of transcoding tech-
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`niques and error control schemes for wired and wireless
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`connection