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Topic: Channel capacity


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  Channel capacity - Wikipedia, the free encyclopedia
By the noisy-channel coding theorem, the channel capacity of a given channel is the limiting information transport rate (in units of information per unit time) that can be achieved with vanishingly small error probability.
The key result states that the capacity of the channel, as defined above, is given by the maximum of the mutual information between the input and output of the channel, where the maximization is with respect to the input distribution.
The channel coding theorem states that for any ε > 0 and for any rate less than the channel capacity, there is an encoding and decoding scheme that can be used to ensure that the probability of block error is less than ε > 0 for sufficiently long message block M.
en.wikipedia.org /wiki/Channel_capacity   (387 words)

  
 Capacity - Wikipedia, the free encyclopedia
Cranial capacity is a measure of the volume of the interior of the skull
Seating capacity refers to the number of people who can be seated in a venue, either in terms of the space available, or in terms of limitations set by law.
Capacity utilization is a term in economics referring to the relationship of actual to potential output of industries.
en.wikipedia.org /wiki/Capacity   (278 words)

  
 The adaptive classical capacity of a quantum channel, or Information capacities of three symmetric pure states in three ...
A quantum channel of the type that Holevo [8] classifies as c-q (classical-quantum) can be constructed from these states by allowing the sender to choose one of these three pure states, which is then conveyed to the receiver.
channel capacity (or the one-shot capacity), which is the maximum of the accessible information over all probability distributions on the trine states.
Shannon's formula for the capacity of a classical channel is the entropy of the average output less the average entropy of the output.
www.research.ibm.com /journal/rd/481/shor.html   (10132 words)

  
 Citations: A general formula for channel capacity - Verdu, Han (ResearchIndex)   (Site not responding. Last check: 2007-10-21)
When codes with stochastic encoders are allowed, analogous notions of capacity (or) and capacity (or)of a channel are defined by modifying the previous definitions of these terms in an obvious way.
Recently, we proposed a stronger sense of reliable transmission and its induced notion of capacity for a channel: 9] De nition 2.2 The....
On the Information-Theoretic Capacity of Discrete-Time Queues - Bedekar, Azizoglu (1998)
citeseer.ist.psu.edu /context/471592/0   (2258 words)

  
 Predicting radio channel capacity
The mathematics for calculating the throughput capacity of a data channel can be scaled with these analogous channel parameters to calculate the expected throughput capacity of voice messages in the conventional channel.
When the channel is idle, the user may (a) transmit immediately, (b) wait a random time before transmitting or (c) choose not to transmit at all and try later.
The channel not only suffers from a rise in users trying to get "on the air," but the channel's capacity to handle this increasing load is reduced by the many users who forget their etiquette out of frustration.
mrtmag.com /mag/radio_predicting_radio_channel   (2062 words)

  
 Channel capacity   (Site not responding. Last check: 2007-10-21)
Channel Island fox (Channel Island foxes) scientific name: Urocyon littoralis An endangered species of fox native to the Channel Islands off the coast of California.
The Islands are located in the Bay of St. Malo, an area known for dramatic tidal currents (spring tide ranges exceed 30 vertical feet), often impenetrable Channel fogs, and winter weather patterns arriving from the open Atlantic, with large swells and hurricane-force winds.
Abandoned without contest by the UK Government to the advancing German forces as they swept unopposed through France, those Channel Islanders who were not evacuated to the UK mainland endured the longest enemy occupation by the Nazis, and lived under the highest ratio of enemy troops to civilians in any occupied country in Western Europe.
www.serebella.com /encyclopedia/article-Channel_capacity.html   (730 words)

  
 Channel Capacity   (Site not responding. Last check: 2007-10-21)
Exact expressions relating the input and output of the system are sufficiently complex to have hindered a determination of the channel capacity, particularly when one considers multichannel systems consisting of multiple fiber links and arbitrary input bit sequences.
While the channel capacity is determined by the conditional Probability Distribution Function (PDF) relating input to output, progress can be made even without complete knowledge of this PDF.
Starting with a physical model of the information channel, statistical properties of the input-output relation can be obtained, which are used in the determination of the capacity of a WDM system.
www.stanford.edu /~hossein/ee359/node4.html   (477 words)

  
 US CODE: Title 47,532. Cable channels for commercial use
(6) Any channel capacity which has been designated for public, educational, or governmental use may not be considered as designated under this section for commercial use for purpose of this section.
Any person aggrieved by the failure or refusal of a cable operator to make channel capacity available for use pursuant to this section may bring an action in the district court of the United States for the judicial district in which the cable system is located to compel that such capacity be made available.
The channel capacity used to provide programming from a qualified minority programming source or from any qualified educational programming source pursuant to this subsection may not exceed 33 percent of the channel capacity designated pursuant to this section.
www4.law.cornell.edu /uscode/47/532.html   (1179 words)

  
 CDSLab - Channel Capacity Analysis   (Site not responding. Last check: 2007-10-21)
In magnetic recording systems it is important to compare proposed coding and detection strategies against optimal coding and detection methods in order to gauge their effectiveness.
The motivation for this project is to investigate the effect signal dependent transition noise has on channel capacity.
Oenning and J. Moon, "The Effect of Jitter Noise on Binary Input Intersymbol Interference Channel Capacity," ICC 2001 vol.
www-cdslab.ece.umn.edu /research/capacity.html   (127 words)

  
 Extra Problems for Chapter 8
Show that the capacity of a pair of transmissions on this channel is 2 bits.
As argued in class, the input distribution that achieves capacity is the uniform distribution.
Prove a general result that for any channel, considering the encoder, channel and decoder together as a new channel from messages to estimated messages will not increase the capacity in bits per transmission of the original channel.
www-isl.stanford.edu /~jat/eit2/webbook/exch8/exch8.html   (1969 words)

  
 Citations: Sensitivity of channel capacity - Pinsker, Prelov, Verd (ResearchIndex)
In this situation, the capacity of a DSL link is the capacity of a channel subject to Gaussian noise plus a contaminating non Gaussian noise, and in this case the sensitivity of the channel capacity depends on the contaminating process distribution only through its autocorrelation function
The autocorrelation of the crosstalk can be derived from estimates of the crosstalk sources and couplings, which then allows a precise evaluation of the impact of that particular crosstalk on the channel capacity.
The second term on the right hand side of (84) is equal to (85) 86) where (85) follows from the fact that for any nonnegative matrix (87) The necessity of (81) is clear from the fact that since the mutual information is invariant to the mean of the input we can only hope to....
citeseer.ist.psu.edu /context/1244245/0   (943 words)

  
 Channel capacity   (Site not responding. Last check: 2007-10-21)
Channel capacity, shown often as "C" in communication formulas, is the amount of discrete information bitsthat a defined area or segment in a communications medium can hold.
Information Theory, developed by Claude E. Shannon in 1948, providesa mathematical model by which one can compute the maximal amount of information that can be carried by a channel.
Two additional considerations: The channel can be light beams, radio waves, a specified bandwidth, a book, or even elementaryparticles from whose state information may be gleaned.
www.therfcc.org /channel-capacity-2003.html   (226 words)

  
 1   (Site not responding. Last check: 2007-10-21)
A study of the capacity of multiple element antenna systems is interested with the emphasis on the mutual coupling effects between the antenna elements.
Since the channel capacity relates the channel impulse response matrix which is a matrix with entries as random variables, it is necessary to study how the radio channel changes with the different antenna separation, mutual coupling effects, and other fading correlation.
It is necessary to put them together into the channel impulse responses so as to obtain the total channel impulse response and more accurate channel capacity evaluation.
www.ece.utexas.edu /~yqyang/wireless_proposal.html   (847 words)

  
 Channel Capacity and Co-channel Interference
Lee [1] derived an estimate of the channel capacity in Rayleigh fading environments and showed that when using diversity in a Rayleigh fading environment, the average channel capacity can approach that for a Gaussian channel.
The normalised channel capacity for a typical hexagonal cell in a simulated system, with Rayleigh fast- and log-normal shadow fading having a standard deviation of 6 dB and a frequency of 1 Hz is shown in Figure 1.
The average SINR profile of the previously used hexagonal cell characterised previously in Figure 1 in terms of normalised channel capacity is shown in Figure 2.
www-mobile.ecs.soton.ac.uk /peter/publications/loughborough96/node1.html   (552 words)

  
 SurfWax: News, Reviews and Articles On Channel Capacity
Because advanced cable systems now have greater channel capacity than satellite, many cable companies have been able to offer subscribers not just high-definition versions of pay and basic cable services such as HBO, Discovery, and ESPN, but also the HD feeds of their local broadcast channels as well.
In a recent study by Brian Banister, one of Zeidler's graduate student researchers, a ten-fold boost in channel capacity was achieved using an eight-fold asymmetric MIMO channel compared to a one-way channel, given the same signal-to-noise ratios on each channel.
The universal access of households to the vast channel capacity of cable and satellite or digital broadcast satellite (DBS) services has eroded the notion that "television" is synonymous with the technology of "broadcasting." (The growth of cable and, later, DBS only became possible after deregulatory moves of the late...
news.surfwax.com /telecom/files/Channel_Capacity.html   (2826 words)

  
 Channel Capacity Definition   (Site not responding. Last check: 2007-10-21)
On the Capacity of Vector Gaussian Interference Channels...
GeorgaTech-2003 Oct. 7, 2003 1 Channel Capacity, Entropy and Front-ends...
Data Hiding Capacity in the Presence of an Imperfectly Known...
www.scienceoxygen.com /electrical/405.html   (290 words)

  
 US CODE: Title 47,531. Cable channels for public, educational, or governmental use
A franchising authority may establish requirements in a franchise with respect to the designation or use of channel capacity for public, educational, or governmental use only to the extent provided in this section.
Such enforcement authority includes the authority to enforce any provisions of the franchise for services, facilities, or equipment proposed by the cable operator which relate to public, educational, or governmental use of channel capacity, whether or not required by the franchising authority pursuant to subsection (b) of this section.
In the case of any franchise under which channel capacity is designated under subsection (b) of this section, the franchising authority shall prescribe—
www.law.cornell.edu /uscode/47/531.shtml   (278 words)

  
 Channel capacity: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-10-21)
The "channel capacity" of human perception and short-term memory short-term memory quick summary:
Short-term memory, sometimes referred to as "primary" or "active" memory, is that part of memory which stores a limited amount of information for a limited amount...
In information theory, the shannon-hartley theorem states the maximum amount of error-free digital data (that is, information) that can be transmitted over...
www.absoluteastronomy.com /encyclopedia/c/ch/channel_capacity.htm   (357 words)

  
 Clear Channel Capacity
This number is derived when you multiply the 24 channels by the 8 bits contained in each.
This means that the clear channel aggregate data rate is only 1.344 Mbps, which is derived when you multiply the 24 DS-0 channels by 56 kbps each.
So, clear channel capacity explains why digital services only offer data rates in multiples of 56 kbps, since the other 8 kbps is lost to signaling.
www.comtest.com /tutorials/t1.html   (645 words)

  
 Nature highlights > Radio communications: Tripling channel capacity   (Site not responding. Last check: 2007-10-21)
One of the most promising areas of progress in the theory of wireless communications is the use of multiple and 'smart' antennas to increase the channel capacity for radio links; this can involve the use of various polarizations in the transmitted signals.
This method has now been extended by the use of magnetic as well as electric field components, giving the potential to increase channel capacity by a factor of three compared with conventional dual-polarized radio signals.
The data capacity of cellphone networks can be expanded by harnessing bouncing signals.
www.nature.com /nature/links/010118/010118-2.html   (158 words)

  
 Extra Problems for Chapter 10
Consider a Gaussian noise channel of power contraint P, where the signal takes two different paths and the received noisy signals are added together at the antenna.
Using Fano's inequality, show that the capacity C is equal to zero for this channel.
Consider the channel Y=X+Z, where X is the transmitted signal with power constraint P, Z is independent additive noise, and Y is the received signal.
www-isl.stanford.edu /~jat/eit2/webbook/exch10/exch10.html   (772 words)

  
 Channel capacity   (Site not responding. Last check: 2007-10-21)
As we have already noted, the astonishing part of this theory is the existence of a channel capacity.
The binary channel (BC) is a channel with a binary input and output.
For the binary channel the maximum bit rate W is 2B.
www.cs.ucl.ac.uk /staff/S.Bhatti/D51-notes/node31.html   (504 words)

  
 Channel Capacity   (Site not responding. Last check: 2007-10-21)
In this section, we consider channels and will find out how much information can be sent through the channel reliably.
We will first consider simple channels where the input is a discrete random variable and the output is also a discrete random variable.
A binary symmetric channel (BSC) is a discrete memoryless channel with binary input and binary output and p
cnx.org /content/m10173/latest   (324 words)

  
 [No title]   (Site not responding. Last check: 2007-10-21)
However, in both slotted and unslotted versions of the ALOHA scheme, the channel capacity is reduced when message switching is used instead of packet switching.
Hence, the performance under message switching may be superior to or inferior to that under packet switching depending upon the random access scheme being used and the distribution of message length (usually a large coefficient of variation of message length implies a large degradation of channel capacity in this case) for certain random access schemes.
Nevertheless, for radio channels, message switching can achieve larger channel capacity if appropriate CSMA schemes are used.
www-db.stanford.edu /TR/CSL-TR-77-137.html   (312 words)

  
 Geometric Programming Duals of Channel Capacity and Rate Distortion   (Site not responding. Last check: 2007-10-21)
Upper bounds on channel capacity and lower bounds on rate distortion can be efficiently generated from their duals.
For channel capacity, the geometric programming characterization is shown to be equivalent to the minmaxKL characterization.
A 'duality by mapping' is then given between the Lagrange dual problems of channel capacity with input cost and rate distortion, which resolves several apparent asymmetries between their primal problems in the familiar form of mutual information optimization problems.
www.stanford.edu /~boyd/gp_chan_cap.html   (188 words)

  
 DVSI Channel Capacity
With its unique patent pending design, the MultiMux™ Vocoder Board provides 16 independent channels of compressed speech which makes it ideal for base station or gateway applications where many simultaneous users must be served in an efficient manner.
Each board compresses sixteen 64 kbps PCM voice channels from a standard T1/E1 interface into a single 64 kbps multiplexed bit stream, however several MultiMux™ boards may be used together to increase call capacity for a larger gateway.
In the application being shown the compressed bit stream is sent to a VSAT satellite terminal which serves as an inter-gateway link allowing transmission of the compressed voice bits between virtually any points on the globe.
www.dvsinc.com /papers/max%20chan%20cap.htm   (2023 words)

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