scispace - formally typeset
Search or ask a question
Topic

Communication channel

About: Communication channel is a research topic. Over the lifetime, 137411 publications have been published within this topic receiving 1715077 citations. The topic is also known as: communication channel & communications channel.


Papers
More filters
Journal ArticleDOI
TL;DR: It is concluded that the channel-optimized vector quantizer design algorithm, if used carefully, can result in a fairly robust system with no additional delay.
Abstract: Several issues related to vector quantization for noisy channels are discussed. An algorithm based on simulated annealing is developed for assigning binary codewords to the vector quantizer code-vectors. It is shown that this algorithm could result in dramatic performance improvements as compared to randomly selected codewords. A modification of the simulated annealing algorithm for binary codeword assignment is developed for the case where the bits in the codeword are subjected to unequal error probabilities (resulting from unequal levels of error protection). An algorithm for the design of an optimal vector quantizer for a noisy channel is briefly discussed, and its robustness under channel mismatch conditions is studied. Numerical results for a stationary first-order Gauss-Markov source and a binary symmetric channel are provided. It is concluded that the channel-optimized vector quantizer design algorithm, if used carefully, can result in a fairly robust system with no additional delay. The case in which the communication channel is nonstationary (as in mobile radio channels) is studied, and some preliminary ideas for quantizer design are presented. >

509 citations

Journal ArticleDOI
TL;DR: In this article, the influence of channel structures and channel coordination on the supplier, the retailer, and the entire supply chain in the context of two single-channel and two dual-channel supply chains was investigated.

509 citations

Journal ArticleDOI
TL;DR: A model is presented for the time- and frequency-selective outdoor mobile radio channel based on the physical process of wave propagation in a statistical fluctuating medium and the reduction of this complex scattering problem to a set of relations containing the pertinent statistics for conducting communications system analysis is developed.
Abstract: A model is presented for the time- and frequency-selective outdoor mobile radio channel. which is based on the physical process of wave propagation in a statistical fluctuating medium. The reduction of this complex scattering problem to a set of relations containing the pertinent statistics for conducting communications system analysis is developed. Characteristics of the propagation process, e.g., delay power spectra, amplitude distribution (Nakagami-m-distribution), and correlation functions, are derived in parameterized form from physical considerations. The method allows a classification of real configurations (environments) into several classes and the extraction of the relevant parameters in direct comparison with measured data. The method is applied to typical channel situations in Switzerland. The mathematical modeling of the classes is demonstrated. >

507 citations

Journal ArticleDOI
TL;DR: The optimal trade-offs among the parameters K, N, and μ and the intruder's uncertainty H (H is the "conditional entropy" of the data given the μ intercepted channel bits) were found and a system exists with H ≈ K − l.
Abstract: Consider the following situation. K data bits are to be encoded into N> K bits and transmitted over a noiseless channel. An intruder can observe a subset of his choice of size μ < N. The encoder is to be designed to maximize the intruder's uncertainty about the data given his μ intercepted channel bits, subject to the condition that the intended receiver can recover the K data bits perfectly from the N channel bits. The optimal trade-offs among the parameters K, N, and μ and the intruder's uncertainty H (H is the "conditional entropy" of the data given the μ intercepted channel bits) were found. In particular, it was shown that for μ = N − K, a system exists with H ≈ K − l. Thus, for example, when N = 2K and μ = K, it is possible to encode the K data bits into 2K channel bits, so that by looking at any K channel bits, the intruder obtains no more than one bit of the data.

507 citations

Patent
17 May 1996
TL;DR: In this article, an interactive cable television system is described, which utilizes a standard cable television distribution network for simultaneously providing a plurality of viewers with an interactive television program comprising a multiplicity of signals related in time and content.
Abstract: An interactive cable television system is disclosed which utilizes a standard cable television distribution network for simultaneously providing a plurality of viewers with an interactive television program comprising a plurality of signals related in time and content. Video signals are transmitted in a digital format, more than one signal being multiplexed onto a data stream on a single channel. The video signals may be compressed for efficiency. A receiver, in conjunction with a signal selector, selects a particular NTSC channel for playback, then selects a particular video signal from the data stream, and decompresses the video signal for playback. Seamless switching between video signals on different channels is provided. An alternative embodiment is disclosed wherein the various signals which comprise the interactive program are switched at the head end rather than at the receiver. The multiple choice control unit selects a desired signal by relaying the multiple choice selections of the user through a relay box back to a remotely located switching station. The switching station routes the correct video signal down the appropriate cable channel for the particular user.

506 citations


Network Information
Related Topics (5)
Wireless
133.4K papers, 1.9M citations
88% related
Network packet
159.7K papers, 2.2M citations
86% related
Wireless network
122.5K papers, 2.1M citations
84% related
Node (networking)
158.3K papers, 1.7M citations
83% related
Wireless sensor network
142K papers, 2.4M citations
83% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202270
20214,425
20206,535
20197,160
20187,052
20176,315