Browsing by Author "Devroye, Natasha"

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Achievable error exponents for the two-way parallel DMC
(Institute of Electrical and Electronics Engineers, 2021) Devroye, Natasha ; Palacio Baus, Kenneth Samuel
We investigate error exponent regions for the parallel two-way DMC in which each terminal sends its own message and provides feedback to the other terminal. Various error exponents are presented in different rate-region regimes based on the relative rates and zero-error capacities of both directions. The schemes employed are extensions of error exponents for one-way DMCs with noiseless, rate-limited and noisy feedback
Achievable error exponents of one-way and two-way AWGN channels
(2019) Palacio Baus, Kenneth Samuel; Devroye, Natasha
Achievable error exponents for the one-way with noisy feedback and two-way AWGN channels are derived for the transmission of a finite number of messages using fixed block length , under the almost sure (AS) and the expected block (EXP) power constraints. In the one-way setting under noisy AWGN feedback, it is shown that under the AS constraint and when the feedback link is much stronger than the direct link, active feedback leads to a larger gain over the non-feedback error exponent than passive feedback. Under the EXP constraint, a previously known error exponent for the transmission of two messages is generalized to any arbitrary but finite number of messages . In the two-way setting, where each user has its own message to send in addition to (possibly) aiding in the transmission of feedback for the opposite direction, error exponent regions are defined and derived for the first time for the AWGN two-way channel under both AS and EXP power constraints. It is shown that feedback or interaction may lead to error exponent gains in one direction, possibly at the expense of a decrease in the error exponents attained in the other direction. The relationship between and supported by our achievability strategies is explored.
An error exponent for the AWGN channel with decision feedback and lattice coding
(Institute of Electrical and Electronics Engineers, 2022) Palacio Baus, Kenneth Samuel; Devroye, Natasha
Error exponents of parallel two-way discrete memoryless channels using variable length coding
(Institute of Electrical and Electronics Engineers Inc., 2019) Palacio Baus, Kenneth Samuel; Asadi, Meysam; Devroye, Natasha
Achievable error exponents for two-way parallel discrete memoryless channels (DMC) using variable block length coding (VLC) are presented. First, Forney's erasure decoding error exponent is shown to be achievable for both directions simultaneously. Next, for some rate-pairs, it is shown that the error exponent of the direction with a smaller capacity may be further increased by allocating feedback resources to it in the other direction, at the price of a decreased error exponent for the other terminal. The presented two-way communication scheme builds upon Draper-Sahai's one-way DMC achievability scheme with noisy feedback under VLC. Both achievable error exponent regions demonstrate that the use of VLC and interaction between the terminals may benefit both directions' error exponents over fixed block length and feedback free transmission.1.
Two-way AWGN channel error exponents at zero rate
(Institute of Electrical and Electronics Engineers Inc, 2018) Palacio Baus, Kenneth Samuel; Devroye, Natasha
Achievable error exponent regions of a two-way additive white Gaussian noise (AWGN) channel, where two terminals exchange a fixed number of messages M, are derived. In particular, error exponent regions for = 2 messages under expected power and = 3 messages under almost sure power constraints are considered. For = 2 messages the use of active feedback is shown to lead to an error exponent gain over that when feedback / interaction is ignored. For = 3 messages and asymmetric channels, it is shown that the error exponent of the weaker channel may be improved through active feedback, at the expense of a decreased error exponent of the stronger direction. This may, for sufficiently asymmetric channel gains, outperform the error exponent region achieved by having both terminals operate independently of one another (ignoring the possibility of sending feedback for the other).
Variable-length coding error exponents for the AWGN channel with noisy feedback at zero-rate
(Institute of Electrical and Electronics Engineers Inc., 2019) Devroye, Natasha; Palacio Baus, Kenneth Samuel
A one-way additive white Gaussian noise (AWGN) channel with active feedback sent over another AWGN feedback channel is considered. Achievable error exponents are presented in the finite message / zero-rate regime for a variable length coding (VLC) scheme. This coding scheme uses a form of round-robin scheduling of messages, and a simplex-based feedback code to obtain reliable feedback and remain synchronized, despite the noise in the feedback link. Our results show that this new VLC scheme under an almost-sure power constraint achieves an error exponent similar to an achievable exponent attained using a fixed block length scheme under a much more relaxed expected block power constraint, and is larger than that achieved by schemes without feedback.1