An overview of wireless communications

Abrishamkar, F.; Biglieri, E.

doi:10.1109/milcom.1994.473984

“…The discretetime channel, with standing for the discrete-time index, is described by (3.3.9) where the complex transmitted sequence is a proper discretetime process [171] satisfying the average-power constraint 2 Here decomposability means that the channel is described by the one-step transition probability function p (s n+1 ; y n js n ; x n ), satisfying: a) s n+1 ; yn are independent of all past states and inputs given sn and x n : We will introduce further assumptions on the process for special cases to be detailed which fall, considering the above mentioned reservations, within the framework of the general results on finite-state channels presented in this subsection.…”

Section: ) General Finite-state Channelmentioning

confidence: 99%

“…With this in mind, we have constructed a rather extensive additional reference list, focusing on information-theoretic approaches to time-varying channels. Some additional relevant references not cited in the text are [55], [2], [9], [3], [5], [105], [302], [336], [169], [184], [189], [120], [276], [271], [212], [244], [138], [20], [246], [30], [86], [121], [339], [269], [66], [46], [233], [275], [245], [264], [18], [213], [224], [3], [7], [8], [102], [272], [1]. By no means is this list complete or even close to complete: hundreds of directly relevant references were not included, but rather appear in the reference lists of the papers cited here.…”

Section: E Concluding Remarksmentioning

confidence: 99%

“…T HE theory for Gaussian dispersive channels, whether time-invariant or variant, has been well established for decades with new touches motivated by practical technological achievements, reported systematically over the years (see [2], [62], [64], [94], [114], [122], [223], [225], [267] for some recent developments). Neither the treatment of statistical time-varying channels is new in information theory, and in fact by now this topic is considered as classic [64], with Shannon himself contributing to some of its aspects [261] (see [164] for a recent tutorial exposition, and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Fading channels: information-theoretic and communications aspects

Biglieri

¹

,

Proakis

²

,

Shamai³

1998

IEEE Trans. Inform. Theory

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Abstract-In this paper we review the most peculiar and interesting information-theoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information theory of fading channels, by emphasizing capacity as the most important performance measure. Both single-user and multiuser transmission are examined. Further, we describe how the structure of fading channels impacts code design, and finally overview equalization of fading multipath channels.

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“…Communication channels exist between transmitters and receivers. In wired communication, these channels are illustrated by twisted pairs, cables, wave guides, optical fiber and pointto-point microwave radio channels [46]. Regardless of the channel type used, the received signal differs from the input signal; here the differences are due to the channel impairments, which are known as dispersion, nonlinear distortions, delay and random noise.…”

Section: Transmission Channelmentioning

confidence: 99%

Enhancement of Wyner-Ziv video coding for wireless channels

Thambu¹

2021

Preprint

0

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Wyner-Ziv video coding (WZVC) is a fast emerging video coding technique for wireless video sensor networks. WZVC moves the complexity from the encoder (sensor) to the decoder (receiver). This thesis proposes few enhancements to solve challenging problems in WZVC, namely 1) handling impairments of a fading wireless channel in WZVC environment, 2) investigating rate penalty of WZVC in wireless fading channels, 3) adaptive encoder rate control using inter-frame cross-correlation properties, and 4) better side information estimation with a bit-based noise variance computation technique. In case (1), the decoder metric values in WZVC are calculated with respect to the correlation noise, channel noise, and fading. Multiple input multiple output (MIMO) diversity scheme is studied with WZVC for improving the reconstructed video output. Simulation results show that the average peak signal to noise ratio (PSNR) of Foreman video is improved by ≈ 3 dB with the configuration of 2I4O compared to single input single output (SISO) channel at SNR = 2 dB. In case (2), expressions for the rate penalty are analytically derived under different wireless channel conditions. WZVC scheme with receiver diversity (WZVC-RD) is proposed and also demonstrated that it alleviates the channel-induced rate penalty. Simulation results show that with adequate diversity, the channel induced rate penalty can be almost completely eliminated, i.e., the average rate penalty is reduced to be less than 20 Kbps in WZVC-RD for Foreman video at SNR = 2 dB. In case (3), theoretical rate-distortion behavior of conditional decoding is compared with that of the practical WZVC. An encoder rate control algorithm is proposed with respect to the cross-correlation threshold (CCTH) at the decoder, where the definition of the threshold is derived based on cross-correlation statistics of the key frames. Additionally, an adaptive threshold algorithm (ATHA) is proposed to improve the PSNR versus rate relationship. In case (4), correlation noise variance estimation is proposed with respect to the bit pattern of each pixel; it is named as “bit-based noise variance”. PSNR improvement of ≈ 4 dB is observed for the Foreman video frames with higher correlation noise.

show abstract

“…Communication channels exist between transmitters and receivers. In wired communication, these channels are illustrated by twisted pairs, cables, wave guides, optical fiber and pointto-point microwave radio channels [46]. Regardless of the channel type used, the received signal differs from the input signal; here the differences are due to the channel impairments, which are known as dispersion, nonlinear distortions, delay and random noise.…”

Section: Transmission Channelmentioning

confidence: 99%

Enhancement of Wyner-Ziv video coding for wireless channels

Thambu¹

2021

Preprint

0

View full text Add to dashboard Cite

Wyner-Ziv video coding (WZVC) is a fast emerging video coding technique for wireless video sensor networks. WZVC moves the complexity from the encoder (sensor) to the decoder (receiver). This thesis proposes few enhancements to solve challenging problems in WZVC, namely 1) handling impairments of a fading wireless channel in WZVC environment, 2) investigating rate penalty of WZVC in wireless fading channels, 3) adaptive encoder rate control using inter-frame cross-correlation properties, and 4) better side information estimation with a bit-based noise variance computation technique. In case (1), the decoder metric values in WZVC are calculated with respect to the correlation noise, channel noise, and fading. Multiple input multiple output (MIMO) diversity scheme is studied with WZVC for improving the reconstructed video output. Simulation results show that the average peak signal to noise ratio (PSNR) of Foreman video is improved by ≈ 3 dB with the configuration of 2I4O compared to single input single output (SISO) channel at SNR = 2 dB. In case (2), expressions for the rate penalty are analytically derived under different wireless channel conditions. WZVC scheme with receiver diversity (WZVC-RD) is proposed and also demonstrated that it alleviates the channel-induced rate penalty. Simulation results show that with adequate diversity, the channel induced rate penalty can be almost completely eliminated, i.e., the average rate penalty is reduced to be less than 20 Kbps in WZVC-RD for Foreman video at SNR = 2 dB. In case (3), theoretical rate-distortion behavior of conditional decoding is compared with that of the practical WZVC. An encoder rate control algorithm is proposed with respect to the cross-correlation threshold (CCTH) at the decoder, where the definition of the threshold is derived based on cross-correlation statistics of the key frames. Additionally, an adaptive threshold algorithm (ATHA) is proposed to improve the PSNR versus rate relationship. In case (4), correlation noise variance estimation is proposed with respect to the bit pattern of each pixel; it is named as “bit-based noise variance”. PSNR improvement of ≈ 4 dB is observed for the Foreman video frames with higher correlation noise.

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An overview of wireless communications

Cited by 7 publications

References 5 publications

Fading channels: information-theoretic and communications aspects

Fading channels: information-theoretic and communications aspects

Enhancement of Wyner-Ziv video coding for wireless channels

Enhancement of Wyner-Ziv video coding for wireless channels

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