New outer bounds for the interference channel with unilateral source cooperation

Abstract

Abstract-This paper studies the two-user interference channel with unilateral source cooperation, which consists of two sourcedestination pairs that share the same channel and where one fullduplex source can overhear the other source through a noisy inband link. Novel outer bounds of the type 2R1 +R2/R1 +2R2 are developed for the class of injective semi-deterministic channels with independent noises at the different source-destination pairs. The bounds are then specialized to the Gaussian noise case. Interesting insights are provided about when these types of bounds are active, or in other words, when unilateral cooperation is too weak and leaves "holes" in the system resources.

The symmetric sum-capacity of the Gaussian half-duplex causal cognitive interference channel to within a constant gap

“…This implies that, in these regimes, the same gap results found for the FD case in [15] hold in the case of unilateral HD cooperation. In these regimes there is no penalty in HD cooperation.…”

“…• In regions 1, 4, 5 and 6 the gDoF is equal to the one with unilateral FD cooperation [15]. This implies that, in these regimes, the same gap results found for the FD case in [15] hold in the case of unilateral HD cooperation.…”

“…• The gap computed in this work is around 3 bits bigger than the one computed in the FD case [15]. Possible ways to reduce this gap may be: (i) apply joint decoding at the receivers, (ii) develop block Markov schemes instead of taking inspiration by the linear deterministic approximation channel of the Gaussian noise channel at high SNR, (iii) develop achievable schemes that exploit the randomness in the switch to convey further useful information, (iv) develop tighter upper bounds than those used in this work, especially in weak interference where the gap is quite large.…”

Approximate sum-capacity of full- and half-duplex asymmetric interference channels with unilateral source cooperation

“…However, bounds valid for a general memoryless IC with bilateral FD source cooperation can be straightforwardly adapted to the case of unilateral FD cooperation. We followed this approach in [6] and characterized the sum-capacity to within 7.3 bits for the interference-symmetric case (model depicted on the left in Fig. 1).…”

“…The interference-symmetric IC with source cooperation, wherein both destinations experience interference, has been widely studied in the literature [2], [3], [4], [5], [6]. In this work we study the interference-asymmetric IC, where either the link from source 1 to destination 2 is nonexistent (Zchannel) or the link from source 2 to destination 1 is nonexistent (S-channel).…”