How much coordination is needed for robust broadcasting over arbitrarily varying bidirectional broadcast channels

Abstract

The paradigm shift from an exclusive to a shared use of frequencies comes along with the necessity of new concepts since interference will be ubiquitous. Resulting channels may vary in an arbitrary and unknown manner from channel use to channel use. This is the arbitrarily varying channel (AVC).Here, coordination resources such as common randomness or correlated sources have been shown to be important for reliable communication; especially for symmetrizable AVCs where deterministic approaches with pre-specified encoder and decoder fail. Here, we study the arbitrarily varying bidirectional broadcast channel (AVBBC), which is motivated by the broadcast phase of bidirectional relaying. Here, a relay establishes a bidirectional communication between two nodes while sharing resources with other coexisting networks. The question is asked how much coordination is needed for reliable communication. The capacity region of the AVBBC is established and it is shown that for a transmission of block length n no more than O(log n) outputs of the correlated source suffices to achieve the same as with the much stronger resource of common randomness. Such weak coordination resources of correlated sources can easily be realized by broadcasting a signal (e.g. via satellite) observed by all users only as correlated versions.

Reliable Communication under the Influence of a State-Constrained Jammer: An Information-Theoretic Perspective on Receive Diversity

“…In the previously mentioned contribution, an example of a symmetrizable point-to-point channel that has zero capacity for deterministic codes, but which has strictly positive capacity for CR-assisted codes, is given. Transferring the concept of CR-assisted coding to a practical application, the source of common randomness is replaced by the concept of correlated sources.This technique is intensively investigated in [13], [14] and [15]. In [14], the authors show that for an arbitrarily varying broadcast channel no more than O(log n) outputs of correlated sources at block length n are sufficient to achieve the same capacity as by using coordination established by common randomness.…”

“…Transferring the concept of CR-assisted coding to a practical application, the source of common randomness is replaced by the concept of correlated sources.This technique is intensively investigated in [13], [14] and [15]. In [14], the authors show that for an arbitrarily varying broadcast channel no more than O(log n) outputs of correlated sources at block length n are sufficient to achieve the same capacity as by using coordination established by common randomness. Nevertheless, in order to guarantee reliable message transmission under the influence of a jammer when the channel is symmetrizable, all previous work assumes an external assistance mechanism that cannot be accessed by the jammer-be it a side channel or…”

“…This technique is intensively investigated in [13], [14] and [15]. In [14], the authors show that for an arbitrarily varying broadcast channel no more than O(log n) outputs of correlated sources at block length n are sufficient to achieve the same capacity as by using coordination established by common randomness.…”