Information embedding (IE) is the transmission of information within a host signal subject to a distortion constraint. There are two types of embedding methods, namely irreversible IE and reversible IE, depending upon whether or not the host, as well as the message, is recovered at the decoder. In irreversible IE, only the embedded message is recovered at the decoder, and in reversible IE, both the message and the host are recovered at the decoder. In this paper, combinations of irreversible and reversible IE in multiple access channels (MAC) and physically degraded broadcast channels (BC) are considered. In this paper, MAC IE in which separate encoders embed their messages into their host signals subject to distortion constraints is considered. The embedded signals from the two encoders are transmitted to a single decoder across a MAC. For the MAC IE model, the following three cases are considered: A) no host recovery at the decoder, B) lossless recovery of one host at the decoder, and C) lossless recovery of both hosts at the decoder. For the cases A and B, inner bounds on the respective capacity regions are developed. For the case C, inner and outer bounds on the capacity region are developed, and the capacity region is obtained if the hosts are independent. In this paper, BC IE in which two messages intended for separate decoders are embedded into a given host sequence by a single encoder subject to a distortion constraint is also considered. For the BC IE model, the following four cases are considered: A') lossless recovery of the host sequence at neither of the decoders, B') lossless recovery of the host sequence at only the better decoder, C') lossless recovery of the host sequence at both decoders, and D') lossless recovery of the host sequence at only the worse decoder. For cases A' and B', inner and outer bounds on the respective capacity regions are developed. For cases C' and D', the identical capacity regions are obtained.

In this paper, we consider a three-terminal state-dependent relay channel (RC) with the channel state noncausally available at only the relay. Such a model may be useful for designing cooperative wireless networks with some terminals equipped with cognition capabilities, i.e., the relay in our setup. In the discrete memoryless (DM) case, we establish lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme at the relay that uses a combination of codeword splitting, Gel'fand-Pinsker binning, and decode-and-forward (DF) relaying. The upper bound improves upon that obtained by assuming that the channel state is available at the source, the relay, and the destination. For the Gaussian case, we also derive lower and upper bounds on the capacity. The lower bound is obtained by a coding scheme at the relay that uses a combination of codeword splitting, generalized dirty paper coding (DPC), and DF relaying; the upper bound is also better than that obtained by assuming that the channel state is available at the source, the relay, and the destination. In the case of degraded Gaussian channels, the lower bound meets with the upper bound for some special cases, and, so, the capacity is obtained for these cases. Furthermore, in the Gaussian case, we also extend the results to the case in which the relay operates in a half-duplex mode.

We consider a two-user state-dependent multiaccess channel in which only one of the encoders is informed, non-causally, of the channel states. Two independent messages are transmitted: a common message transmitted by both the informed and uninformed encoders, and an individual message transmitted by only the uninformed encoder. We derive inner and outer bounds on the capacity region of this model in the discrete memoryless case as well as the Gaussian case. Further, we show that the bounds for the Gaussian case are tight in some special cases.

This paper investigates downlink transmission over a quasi-static fading Gaussian broadcast channel (BC), to model delay-sensitive applications over slowly time-varying fading channels. System performance is characterized by the outage capacity region. In contrast to most previous work, here the problem is studied under the key assumption that the transmitter knows only the probability distributions of the fading coefficients, not their realizations. For scalar-input channels, two coding schemes are studied. The first scheme is called blind dirty paper coding (B-DPC), which utilizes a robustness property of dirty paper coding to perform precoding at the transmitter. The second scheme is called statistical superposition coding (S-SC), in which each receiver adaptively performs successive decoding with the process statistically governed by the realized fading. Both B-DPC and S-SC schemes achieve the outage capacity region, which dominates the outage rate region of time-sharing, irrespective of the particular fading distributions. The S-SC scheme can be extended to BCs with multiple transmit antennas.

We consider a state-dependent full-duplex relay channel with the state of the channel non-causally available at only the relay. In the framework of cooperative wireless networks, some specific terminals can be equipped with cognition capabilities, i.e, the relay in our model. In the discrete memoryless (DM) case, we derive lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme at the relay that consists in a combination of codeword splitting, Gelpsilafand-Pinsker binning, and a decode-and-forward scheme. The upper bound is better than that obtained by assuming the availability of state at the source, the relay, and the destination. For the Gaussian case, we also derive lower and upper bounds on channel capacity. The lower bound, obtained by a coding scheme based on combination of codeword splitting and generalized dirty paper coding, is tight in some cases if the channel is physically degraded. The upper bound is also better than that obtained by assuming that the channel state is available at the source, the relay, and the destination.

We consider a state-dependent multiple access channel p(y|x1, x2, s) whose output Y is controlled by the channel inputs x1and x2from two encoders and the channel state S. It is assumed that the channel state is known non-causally at one encoder, called the informed encoder. We derive the capacity region for the case of degraded messages in which the informed encoder knows the message of the uninformed encoder.

This paper studies a variant of the classical problem of "writing on dirty paper" in which the sum of the input and the interference, or dirt, is multiplied by a random variable that models resizing, known to the decoder but not to the encoder. The achievable rate of Costa's dirty paper coding (DPC) scheme is calculated and compared to the case of the decoder's also knowing the dirt. In the ergodic case, the corresponding rate loss vanishes asymptotically in the limits of both high and low signal-to-noise ratio (SNR), and is small at all finite SNR for typical distributions like Rayleigh, Rician, and Nakagami. In the quasi-static case, the DPC scheme is lossless at all SNR in terms of outage probability. Quasi-static fading broadcast channels (BC) without transmit channel state information (CSI) are investigated as an application of the robustness properties. It is shown that the DPC scheme leads to an outage achievable rate region that strictly dominates that of time division.

We consider information embedding (IE) in a degraded broadcast scenario in which two independent messages (w1, w2) are embedded into a given host sequence snunder the condition that the distortion between the embedded sequence xnand the host sequence satisfies a distortion constraint Delta. We consider four cases: A) lossless recovery of the host sequence at neither of the decoders, B) lossless recovery of the host sequence at the better decoder only, C) lossless recovery of the host sequence at both decoders, and D) lossless recovery of the host sequence at the worse decoder only. In all of the above cases, we consider decoding of the messages (w1, w2) at the better decoder and decoding of the message w2at the worse decoder. We develop inner and outer bounds for the broadcast IE capacity regions in cases A and B, and determine the broadcast IE capacity regions in cases C and D

The postal channel models a postal system in which letters, each consisting of a number of characters, are sometimes lost. We study the postal channel with variable-length letters and variable-length coding over letters, both with and without letter-by-letter feedback. Without allowing letter lengths to encode information, we examine one feedback strategy consisting of automatic repeat-request (ARQ) with exponentially increasing letter lengths. For this strategy we investigate an alternative notion of information rate per character, based upon the total, random number of characters required to convey the messages instead of its expectation. This information rate exhibits a phase transition in its convergence as the number of messages becomes large: if the letter lengths increase by a factor less than the inverse of the probability that a letter is lost, it converges to the channel capacity; otherwise, it converges to a number strictly larger than channel capacity. More generally, when we allow both the characters and the length of a letter to convey information, we compute the corresponding channel capacity with and without feedback, and find that it is twice the channel capacity of the original postal channel without allowing letter lengths to encode information