Minimum energy required to achieve a distortion-noise profile, i.e., a function indicating the maximum allowed distortion value for each channel noise level, is studied for transmission of Gaussian sources over Gaussian channels. A general coding scheme is proposed to upper bound the minimum energy needed for any distortion-noise profile. Conversely, utilizing a family of lower bounds originally derived for broadcast channels with power constraints, the minimum required energy is lower bounded for any profile. As examples, linear, exponential, square-law, and staircase profiles are studied. It is shown that for the linear profile, as well as for any concave profile, uncoded transmission is optimal. As a negative result, it is shown that exponential profiles are not achievable with finite energy. For square-law and staircase profiles, upper bounds and lower bounds are derived and the gaps between them are studied.

Minimum energy required to achieve a distortion-noise profile, i.e., a function indicating the maximum allowed distortion value for each noise level, is studied for robust transmission of Gaussian sources over Gaussian channels. It is shown that for the inversely linear profile, uncoded transmission is optimal. On the other hand, it turns out that exponential profiles are not achievable with finite energy. Finally, using a family of lower bounds and a proposed coding scheme, the minimum energy behavior for the square-law profile is understood up to a multiplicative constant.

This paper studies lossy transmission of a memoryless bivariate Gaussian source over a bandwidth-mismatched memoryless Gaussian broadcast channel with two receivers, where each receiver is interested in reconstructing only one source component. For both bandwidth expansion and compression regimes, novel hybrid digital/analog (HDA) coding schemes are proposed. With appropriate choice of parameters, our schemes are shown to specialize to separate source-channel coding studied by Gao and Tuncel, and is, therefore, superior to it in both bandwidth regimes. Our scheme for bandwidth expansion also outperforms the HDA coding scheme of Behroozi et al. On the other hand, if a proposed conjecture (supported by numerical observations) is indeed true, the same superiority follows for the bandwidth compression regime as well. Finally, when the bandwidth expansion/compression ratio approaches 1, both of our schemes become optimal as their performance approaches that of the bandwidth-matched scheme of Tian et al.

Lossy transmission of Gaussian sources over energy-limited Gaussian point-to-point and broadcast channels is studied under the infinite bandwidth regime, i.e., when the number of channel uses is unlimited. Using previously known asymptotic achievability and converse results, the energy-distortion exponent, defined as the rate of decay of the square-error distortion as the available energy-to-noise ratio increases without bound, is completely characterized for both the point-to-point and broadcast channel cases. Turning then to the scenario of zero-delay transmission, where outage events with arbitrarily small probability are allowed, it is shown that the same energy-distortion exponent as in the infinite-delay case can be achieved in all the studied scenarios.

The energy-distortion tradeoff for the transmission of a white Gaussian source over the additive white Gaussian broadcast channel is investigated by translating the known upper and lower bounds into the infinite bandwidth regime. While a gap continues to exist between the bounds in this regime, it is shown that in a certain region on the distortion plane, the energy difference between the best known upper and lower bounds is quantifiably small.

We consider the lossy transmission of a memoryless bivariate Gaussian source over an average-power-constrained bandwidth-mismatched Gaussian broadcast channel with two receivers where each receiver is interested in only one component. We propose new hybrid digital/analog coding schemes which are demonstrated to outperform the previously known schemes.

An achievable scheme for zero-delay transmission of an i.i.d. Gaussian source over an additive white Gaussian noise channel with no bandwidth limitation is introduced, and its energy-distortion performance is analyzed. By the nature of the problem, one must transmit each source sample separately but can use the channel infinitely many times. The proposed scheme builds on separation of source and channel coding, whereby the source is quantized into “equiprobable” cells so that the output can be seen as a message suitable for channel coding. Moreover, as the number of quantization cells go to infinity, the channel capacity can be approached with arbitrarily small error. In the high energy-to-noise ratio regime, the minimum energy required to obtain a given distortion level in the proposed scheme can come as close as 3dB to the Shannon bound, which can only be achieved using infinite delay.

An achievable scheme for zero-delay transmission of an i.i.d. Gaussian source over an additive white Gaussian channel with no bandwidth limitation is introduced, and its energy-distortion performance is analyzed. By the nature of the problem, one must transmit each source sample separately but can use the channel infinitely many times. We introduce an outage concept, and analyze the expected distortion conditioned on no outage. We show that the proposed scheme can approach to the asymptotical decay for large enough energy for arbitrary outage probability. The proposed scheme builds on separation of source and channel coding, whereby the source is quantized with a high-resolution optimal quantizer. In the high energy-to-noise ratio (ENR) regime, the minimum energy required to obtain a given distortion level in the proposed scheme can approach arbitrarily close the Shannon bound, which can only be achieved using infinite delay.

For transmission of memoryless Gaussian sources over channels with additive white Gaussian noise, the tradeoff between the distortion when the channel quality is good versus bad is investigated under the constraint that the distortion is optimal when the channel has the targeted median quality. The problem was proposed by Tian and Shamai, who subsequently proved remarkable achievability results for bandwidth expansion ratios k, which are integers or unit fractions, i.e., k = 2,3,4, ... or k =1/2,1/3,1/4,... Their result is extended here to all k≥2 and k≤1/2 by generalizing the hybrid digital/analog (HDA) scheme of Wilson et al. to the case of bandwidth mismatch. Finally, novel schemes are proposed for 1/2≤k<;1and 1<;k≤ 2 achieving nontrivial tradeoffs outperforming all known schemes. These latter schemes rely on another extension of the HDA scheme by Wilson et al., namely, the relaxation of the independence of source and channel input sequences.

The problem of lossy transmission of a Gaussian source over an AWGN bandwidth-mismatched broadcast channel with three receivers is addressed. The tradeoff between the distortion levels at the good and the bad receivers is tackled when the distortion at the median receiver is required to be optimal. The problem was proposed by Tian and Shamai (2008), who subsequently found in the work of Tian and Shamai (2011) remarkable achievability results for bandwidth expansion ratios κ which are integers or unit fractions, i.e., κ = 2, 1/3, 1/5, etc. Their result is extended here to all κ ≥ 2 and κ ≤ 1/2 by generalizing the hybrid digital/analog (HDA) scheme in the work of Wilson et al. (2010) to the case of bandwidth mismatch. Finally, novel schemes are proposed for 1/2 = κ ≤ 1 and 1 <; κ ≤ 2 achieving nontrivial tradeoffs.

Lossy transmission of a Gaussian source over an additive white Gaussian (AWGN) channel with side information at the decoder is tackled under the regime of bandwidth expansion. A previously known scheme, hybrid digital/analog Wyner-Ziv (HDA-WZ) coding is shown to remain optimal when extended from the bandwidth matched case to the bandwidth expansion case. The extended scheme also exhibits similar robustness properties under mismatched side information and/or channel quality. Finally, under the criterion of min-max distortion loss, the extended HDA-WZ scheme is shown to outperform a purely-digital scheme known as the common description scheme (CDS).

This paper presents a comparison between two transmit diversity schemes, namely space-time coding and time-switched transmit diversity (TSTD) over block-fading and time-varying multi-input single-output (MISO) channels with various channel parameters. The schemes are concatenated with outer channel codes in order to achieve spatio-temporal diversity. The analytical results are derived for the error performances of the systems and simulation results as well as outage probabilities are provided. It is demonstrated using the analytical and simulation results that TSTD may have a comparable error performance with the space-time coding techniques and it even outperforms the space-time codes in some scenarios. Our results indicate that TSTD can be suggested as an alternative to space-time codes in some time-varying channels especially due to its implementation simplicity.