Feedback Capacity of the Gaussian Interference Channel to Within 2 Bits

• Published in: IEEE transactions on information theory Vol. 57; no. 5; pp. 2667 - 2685
• Main Authors: Changho Suh, Tse, D N C
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2011; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Channels; Communication channels; Data transmission; Deterministic model; Electric noise; Feedback; feedback capacity; Gain; Gaussian; Gaussian interference channel; Information theory; Integrated circuit modeling; Integrated circuits; Interference; Interference channels; Mathematical models; Receivers; side information; Signal to noise ratio; Transmitters
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2011.2119990

We characterize the capacity region to within 2 bits/s/Hz and the symmetric capacity to within 1 bit/s/Hz for the two-user Gaussian interference channel (IC) with feedback. We develop achievable schemes and derive a new outer bound to arrive at this conclusion. One consequence of the result is that feedback provides multiplicative gain at high signal-to-noise ratio: the gain becomes arbitrarily large for certain channel parameters. This finding is in contrast to point-to-point and multiple-access channels where feedback provides no gain and only bounded additive gain respectively. The result makes use of a linear deterministic model to provide insights into the Gaussian channel. This deterministic model is a special case of the El Gamal-Costa deterministic model and as a side-generalization, we establish the exact feedback capacity region of this general class of deterministic ICs.