Digital subscriber line technology facilitates a graceful transition from copper to fiber

Waring, D.L.; Lechleider, J.W.; Hsing, T.R.

doi:10.1109/35.75533

Cited by 34 publications

(11 citation statements)

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“…At the same time, the communications industry should be encouraged to investigate and deploy technologies that could, in relatively short order, extend greater communications bandwidth to the home (Shumate & Snelling, 1991;Waring, Lechleider, & Hsing, 1991), so that parents and neighborhoods can join educational communities of practice.…”

Section: Discussionmentioning

confidence: 99%

Distributed Multimedia Learning Environments: Why and How?

Pea¹,

Gomez

1992

Interactive Learning Environments

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We outline the societal prospects and business opportunities for much more extensive use of interactive multimedia technologies (IMT) connected through telecommunications to create distributed multimedia learning environments (DMLE). A theoretical framework is provided with a distinctive communications perspective on learning emerging from research in the cognitive and social sciences. A major consequence of this communication emphasis is the special need for rich communication technologies to support highly interactive teaching and learning activities, especially those at a distance but even within a classroom or school. Examples of existing projects using IMT for remote learning communications are among the most dramatic examples of these new possibilities. Based on these foundations, we first depict a vision of IMT for schools that establishes the kinds of DMLE designs that appear from research to offer promising improvements. We then characterize how current educational spending trends and educational technology research and development attitudes could be transformed so that such distributed multimedia learning environments could become a reality more rapidly. Short-term progress in closing the gap from current practices to this vision is possible in specific IMT application areas described. The first author gratefully acknowledges the support of National Science Foundation Grant MDR88-55582 in work related to this report. Aspects of the framework for describing the contributions of learning research were first developed in Pea and Soloway (1987). Correspondence and requests for reprints should be sent to Roy D. Pea, Northwestern University, Institute for the Learning Sciences, 1890 Maple Avenue, Evanston, IL 60201 (pea@~ils.nwu.edu). 'Nicholas Negroponte of MIT's Media Lab depicted these trends two decades ago, and Stewart Brand (1988) has traced the history of these developments in his book on the Media Lab.

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Section: Discussionmentioning

confidence: 99%

Distributed Multimedia Learning Environments: Why and How?

Pea¹,

Gomez

1992

Interactive Learning Environments

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“…The maximum theoretical capacity of such a pair is then about 40 kb/s. Several factors limit the achievable data rates over twisted pairs in the local loop [9], [14]. A majority of these limiting factors have been widely investigated in the past: thermal noise, impedance impairments, cross talk, attenuation, and propagation speed distortion.…”

Section: Introductionmentioning

confidence: 99%

An overview of broad-band access technologies

Gagnaire¹

1997

Proc. IEEE

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The provision of broad-band services based on either the Internet or the asynchronous transfer mode (ATM) technique requires a new generation of access networks. In the short term, solutions such as x-digital subscriber line (DSL) and hybrid fiber coaxial (HFC), allowing the reuse of existing infrastructures, look very promising. For the longer term, new infrastructures based either on radio or on optical access links seem preferable. Three x-DSL techniques aiming at high-bit-rate transmission over twisted pairs are presented: high-bit-rate DSL, asymmetrical DSL, and very-high-bit-rate DSL. An extension of existing cable television networks known as HFC is also described. Two other prospective approaches, wireless in the loop (WITL) and fiber in the loop (FITL), are then presented. Several techniques are considered for WITL: digital enhanced cordless telecommunication, local multipoint distribution service, wireless ATM, and low earth orbit satellite constellations. The various architectural alternatives for the FITL approach are discussed, a special interest being dedicated to the synchronous digital hierarchy self-healing loop and the ATM over passive optical network. In our presentation, we mention the main experiments and the standardization activities inherent to the domain.

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“…OFDM has been successfully applied to a wide variety of digital communication applications over the past several years including digital video broadcasting [1], digital audio broadcasting [2], IEEE 802.16 standard [3], Asynchronous Digital Subscriber Line (ADSL) [4], [5] modems and wireless networking worldwide.…”

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confidence: 99%

A Low-Complexity Frequency Offset Correction Scheme for Synchronization in OFDM Systems

Zhao

et al. 2008

2008 4th International Conference on Wireless Communications, Networking and Mobile Computing

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A new carrier frequency offset estimation scheme in the orthogonal frequency division multiplexing (OFDM) system is proposed. In non-data-aided synchronization systems, maximum likelihood estimation (MLE) is often used for carrier frequency offset acquisition but it could not correct the accumulated residue frequency offset caused by sampling clock offset and other factors. After simple comparisons at frequency domain, the proposed scheme takes correction to OFDM symbols and makes compensation for MLE algorithm. By sharing the same phase calculation block with the acquisition step, it keeps very low computational cost and reduces the implementation complexity. The system performance was investigated in additive white Gaussian noise channel.

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Digital subscriber line technology facilitates a graceful transition from copper to fiber

Cited by 34 publications

References 11 publications

Distributed Multimedia Learning Environments: Why and How?

Distributed Multimedia Learning Environments: Why and How?

An overview of broad-band access technologies

A Low-Complexity Frequency Offset Correction Scheme for Synchronization in OFDM Systems

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