A new sum-rate outer bound for Gaussian Interference Channels with Generalized Feedback

Abstract

Interference Channels (IFC) with Generalized Feedback (GF) model wireless channels where every node overhears the transmission of other nodes and uses it to engage in cooperative communication strategies. The overheard signals, instead of being treated as interference, furnish the basis for cooperation among otherwise uncoordinated users. Although cooperative communications is not equivalent to virtual Multi-Input-MultiOutput (MIMO) communications, it has been shown to benefit the rate performance of all the involved source-destination pairs without increasing neither their transmit powers nor the channel bandwidth. This paper develops a new sum-rate outer bound for Gaussian IFC-GFs based on the idea of giving the receivers the least informative GF signal as side information. We compare our new outer bound with bounds available in the literature and numerically show for which network parameters our bound strictly improves on existing ones.

Capacity theorems for the fading interference channel with a relay and feedback links

“…For the situation in which both transmitters observe noisy feedback from both receivers, it was shown that feedback looses its value when the noise in the feedback signal is of the same variance as the noise in the direct link. Finally, note that generalized feedback (or, equivalently source cooperation), studied in [27], [56], and [57] can also be considered rate-limited feedback when the SNR is finite. In [56] and [57], outer bounds were derived for ICs with generalized feedback.…”

An outer bound region for Interference Channels with Generalized Feedback

“…Our derivation here shows they hold for any IFC-GF. 4) Another generalization of [15,Th.1] for Gaussian channels in strong interference can be found in [17], where we showed that the capacity region of a Gaussian IFC-GF cannot depend on the channel coefficients h 11 and h 22 . For the Gaussian case with strong interference, we gave a receiver the GF signal of its transmitter as side information so that both messages could be decoded.…”

Capacity of All Nine Models of Channel Output Feedback for the Two-User Interference Channel

“…We would also like to remark that the work on generalized feedback in [14][15][16][17], as well as the work on source cooperation by two sources overhearing each other's messages over a noisy channel in [24] are closely related to our work. The outer and inner bounds derived in [14,16] and [24], concurrent to our work in [1,2], can be particularized to obtain the sum-capacity result shown in Lemma 4.4.…”

“…Next, we present an outer-bound on the sum-capacity of the feedback model (1111) we derived in [1]. Concurrent to [1], the authors in [15] derive an outer-bound for the generalized feedback model. The authors in [24] also derive outer bounds for interference channels with source cooperation, which can be particularized for the linear symmetric deterministic interference channel to obtain the same result.…”

“…A large body of work on interference channels [10][11][12][13] explores feedback strategies, where each receiver sends channel output feedback to its own transmitter. More generalized form of feedback in a two-user interference channel is considered in [14][15][16][17]. Recent work in [18,19] particularly analyzes the capacity region of two-user deterministic and Gaussian interference channels, where each of the receivers send channel output feedback to its own transmitter.…”