Reliable transmission of two correlated sources over an asymmetric multiple-access channel (Corresp.)

Abstract-It has been recently shown by Lapidoth and Steinberg that strictly causal state information can be beneficial in multiple access channels (MACs). Specifically, it was proved that the capacity region of a two-user MAC with independent states, each known strictly causally to one encoder, can be enlarged by letting the encoders send compressed past state information to the decoder. In this work, a generalization of the said strategy is proposed whereby the encoders compress also the past transmitted codewords along with the past state sequences. The proposed scheme uses a combination of long-message encoding, compression of the past state sequences and codewords without binning, and joint decoding over all transmission blocks. The proposed strategy has been recently shown by Lapidoth and Steinberg to strictly improve upon the original one. Capacity results are then derived for a class of channels that include two-user modulo-additive state-dependent MACs. Moreover, the proposed scheme is extended to state-dependent MACs with an arbitrary number of users. Finally, output feedback is introduced and an example is provided to illustrate the interplay between feedback and availability of strictly causal state information in enlarging the capacity region.Index Terms-Multiple access channels, state-dependent channels, strictly causal state information, long-message encoding, quantize-forward, output feedback.

Section: Conversementioning

confidence: 99%

Multiple Access Channels With States Causally Known at Transmitters

Simeone

Yener

2013

“…Optimality of separation in this classical sense is proved for a network of independent, non-interfering channels in [7]. A special class of the MAC, called the asymmetric MAC, in which one of the sources is available at both encoders, is considered in [8] and the classical source-channel separation optimality is shown to hold with or without causal perfect feedback at either or both of the transmitters. In [9], it is shown that for the class of MACs for which the capacity region cannot be enlarged by considering correlated channel inputs, classical separation is optimal.…”

Section: Prior Workmentioning

confidence: 99%

Source and Channel Coding for Correlated Sources Over Multiuser Channels

Gündüz

Erkip

Goldsmith

et al. 2009

Source and channel coding over multiuser channels in which receivers have access to correlated source side information is considered. For several multiuser channel models necessary and sufficient conditions for optimal separation of the source and channel codes are obtained. In particular, the multiple access channel, the compound multiple access channel, the interference channel and the two-way channel with correlated sources and correlated receiver side information are considered, and the optimality of separation is shown to hold for certain source and side information structures. Interestingly, the optimal separate source and channel codes identified for these models are not necessarily the optimal codes for the underlying source coding or the channel coding problems. In other words, while separation of the source and channel codes is optimal, the nature of these optimal codes is impacted by the joint design criterion.

“…For the regular MAC, the separation approach is known to be optimal when the channel is lossless (Slepian-Wolf source coding theorem [4]), or when the sources are independent. In the special case of transmitting correlated sources losslessly over an asymmetric MAC it is shown in [5] that necessary and sufficient conditions for reliable transmission do exist and, moreover, these conditions can be established by applying the separation approach. In [6] the authors consider the model [5] with a single distortion constraint namely, when D 1 = 0 (i.e.…”

Section: Introduction and Problem Statementmentioning

confidence: 99%

“…In the special case of transmitting correlated sources losslessly over an asymmetric MAC it is shown in [5] that necessary and sufficient conditions for reliable transmission do exist and, moreover, these conditions can be established by applying the separation approach. In [6] the authors consider the model [5] with a single distortion constraint namely, when D 1 = 0 (i.e. S 1 is recovered losslessly at the receiver), and show that source-channel separation is optimal.…”

Section: Introduction and Problem Statementmentioning

confidence: 99%

Sending a Bivariate Gaussian Source Over a Gaussian MAC With Unidirectional Conferencing Encoders

Bross

Laufer

2016

We consider the transmission of a memoryless bivariate Gaussian source over a two-user additive Gaussian multiple-access channel with unidirectional conferencing encoders. Here, prior to each transmission block, Encoder 1, which observes the first source component, is allowed to communicate with Encoder 2, which observes the second source component, via a unidirectional noise-free bit-pipe of given capacity. The main results of this work are sufficient conditions and a necessary condition for the achievability of a distortion pair expressed as a function of the channel SNR and of the source correlation. The main sufficient condition is obtained by an extension of the vector-quantizer scheme suggested by Lapidoth-Tinguely, for the case without conferencing, to the case with unidirectional conference. In the high-SNR regime, and when the capacity of the conference channel is unlimited, these necessary and sufficient conditions are shown to agree. We evaluate the precise high-SNR asymptotics for a subset of distortion pairs when the capacity of the conference channel is unlimited in which case we show that a separation based scheme attains these optimal distortion pairs. However, with symmetric average-power constraints and fixed conferencing capacity, at high-SNR the latter separation based scheme is shown to be suboptimal.