Second-order statistics of logarithmic quantization noise in QAM data communication

Saltzberg, B.R.; Wang, J.-D.

doi:10.1109/26.103041

Cited by 10 publications

(4 citation statements)

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“…The effect of this noise is such that the outermost points in a simple rectangular constellation suffer more performance degradation than the smaller internal signals. Saltzberg and Wang in [4] made the observation that not only is the noise around each point dependent on its amplitude, but that this noise is elliptical and not circular, Le., the noise components in the two dimensional QAM space are not equal. In [4], it was also shown that the two dimensional noise components are not only unequal, but also correlated for most choices of vector bases.…”

Section: Introductionmentioning

confidence: 99%

“…Saltzberg and Wang in [4] made the observation that not only is the noise around each point dependent on its amplitude, but that this noise is elliptical and not circular, Le., the noise components in the two dimensional QAM space are not equal. In [4], it was also shown that the two dimensional noise components are not only unequal, but also correlated for most choices of vector bases. These properties make the detection problem and the signal constellation design problem very interesting, and represent a new challenge in signal design.…”

Section: Introductionmentioning

confidence: 99%

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Digital companding scheme using A I based custom constellation mapping and selection

Sastry

Babu

2010

2010 IEEE International Conference on Software Engineering and Service Sciences

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The data rate is important in telecommunication because it is directly proportional to the cost of transmitting the signal. Saving bits is the same as saving money. In this paper we propose new digital companding scheme based on using different constellation orderings (QAM modulator) , depending on the data to be transmitted . The proposed scheme was simulated in Matlab7.4 and it was shown that the proposed companding scheme effective with low compression error.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Digital companding scheme using A I based custom constellation mapping and selection

Sastry

Babu

2010

2010 IEEE International Conference on Software Engineering and Service Sciences

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“…On PCM telephone channels the SNR is typically 38 dB or higher [7], with the dominant impairment being quantization noise due to companding. This SNR is high enough to support quadrature amplitude modulation (QAM) transmission with many bits per QAM symbol (per Hz).…”

Section: Introductionmentioning

confidence: 99%

“…When these noise samples are filtered, a noise process which has an additive and a multiplicative component results [7]. Furthermore the radial component is substantially larger than it's tangential component [7].…”

Section: Introductionmentioning

confidence: 99%

Cutoff rate and constellation design for the companding channel

Davidson¹,

Kalet²

Proceedings of 19th Convention of Electrical and Electronics Engineers in Israel

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In modern voiceband data communication the received signal is subject t o nonlinear quantization noise due t o companding. Under certain conditions this quantization noise m a y become dominant and cause serious degradation in performance. In this work w e first calculate the c u t 0 8 rate and t h e n use these results t o design n e w "optimal" signal constellations f o r the companding channel. These n e w constellations are computed assuming a signal dependent non-circular Gaussian channel transition density.

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Physical Media and Channels

Lee

Messerschmitt

1997

Digital Communication

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Ultimately the design of a digital communication system depends on the properties of the channel. The channel is typically a part of the digital communication system that we cannot change. Some channels are simply a physical medium, such as a wire pair or optical fiber. On the other hand, the radio channel is part of the electromagnetic spectrum, which is divided by government regulatory bodies into bandlimited radio channels that occupy disjoint frequency bands. In this book we do not consider the design of the transducers, such as antennas, lasers, and photodetectors, and hence we consider them part of the channel. Some channels, notably the telephone channel, are actually composites of multiple transmission subsystems. Such composite channels derive their characteristics from the properties of the underlying subsystems.Section 18.1 discusses composite channels. Sections 18.2 through 18.4 review the characteristics of the most common channels used for digital communication, including the transmission line (wire pair or coaxial cable), optical fiber, and microwave radio (satellite, point-to-point and mobile terrestrial radio). Section 18.5 discusses the composite voiceband telephone channel, which is often used for voiceband data transmission. Finally, Section 18.6discusses magnetic recording of digital data, as used in tape and disk drives, which has characteristics similar in many ways to the other channels discussed.The most prevalent media for new installations in the future will be optical fiber and microwave radio, and possibly lossless transmission lines based on superconducting materials. However, there is a continuing strong interest in lossy transmission lines and voiceband channels because of their prevalence in existing installations. Thus all the media discussed in this chapter are important in new applications of digital communication. COMPOSITE CHANNELSIt is common for many users to share a common communication medium, for example by time-division and frequency-division multiplexing (Chapter 16).Example 18-1. Voice signals are roughly bandlimited to frequencies lower than 4 kHz. A suitable baseband channel therefore needs to pass only frequencies up to 4 kHz. Such a channel is often derived from a much higher bandwidth physical medium that is shared with other users. A voice frequency (VF) channel derived from a coaxial cable (Section 18.2) using single-sideband modulation is shown in Fig. 18-1. The SSB modulator translates the VF channel to the neighborhood of a frequency ω c for transmission on the coaxial cable. A VF channel can be used for digital communication, as long as the modulation technique conforms to the limitations of the channel.The channel in Fig. 18-1 is an example of a composite channel, because it consists of multiple subsystems. If the VF channel was designed for voice transmission, it has certain characteristics which are beyond the control of the designer of the digital communication system. The VF channel characteristics in this case depend not only on the properties of th...

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Second-order statistics of logarithmic quantization noise in QAM data communication

Cited by 10 publications

References 1 publication

Digital companding scheme using A I based custom constellation mapping and selection

Digital companding scheme using A I based custom constellation mapping and selection

Cutoff rate and constellation design for the companding channel

Physical Media and Channels

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