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arXiv · 1504.05940

Broadcasting a Common Message with Variable-Length Stop-Feedback Codes

Kasper Fløe Trillingsgaard·Wei Yang·Giuseppe Durisi·Petar Popovski
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Abstract

We investigate the maximum coding rate achievable over a two-user broadcast channel for the scenario where a common message is transmitted using variable-length stop-feedback codes. Specifically, upon decoding the common message, each decoder sends a stop signal to the encoder, which transmits continuously until it receives both stop signals. For the point-to-point case, Polyanskiy, Poor, and Verd\'u (2011) recently demonstrated that variable-length coding combined with stop feedback significantly increases the speed at which the maximum coding rate converges to capacity. This speed-up manifests itself in the absence of a square-root penalty in the asymptotic expansion of the maximum coding rate for large blocklengths, a result a.k.a. zero dispersion. In this paper, we show that this speed-up does not necessarily occur for the broadcast channel with common message. Specifically, there exist scenarios for which variable-length stop-feedback codes yield a positive dispersion.

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Kasper Fløe Trillingsgaard, Wei Yang, Giuseppe Durisi, Petar Popovski. 2015-04-22. Broadcasting a Common Message with Variable-Length Stop-Feedback Codes. https://arxiv.org/abs/1504.05940

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