On the Symmetric Feedback Capacity of the K-User Cyclic Z-Interference Channel

• Published in: IEEE transactions on information theory Vol. 59; no. 5; pp. 2713 - 2734
• Main Authors: Tandon, R., Mohajer, S., Poor, H. V.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2013; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Channel models; Communication channels; Detection, estimation, filtering, equalization, prediction; Electric noise; Encoding; Exact sciences and technology; Feedback capacity; Feedback control systems; Information theory; Information, signal and communications theory; interference channel; Interference channels; Normal distribution; Radiocommunications; Receivers; Signal and communications theory; Signal to noise ratio; Signal, noise; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Transmitters; Transmitters. Receivers; Wyner model; Wyner model; Parameter estimation; Feedback capacity; Gaussian channel; interference channel; Transmitter; Feedback regulation; Linear channel; Linear model; Gaussian process; Channel estimation; Deterministic model; Deterministic approach
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2012.2235904

The K -user cyclic Z-interference channel models a situation in which the k th transmitter causes interference only to the ( k -1)th receiver in a cyclic manner, e.g., the first transmitter causes interference only to the K th receiver. The impact of noiseless feedback on the capacity of this channel is studied by focusing on the Gaussian cyclic Z-interference channel. To this end, the symmetric feedback capacity of the linear shift deterministic cyclic Z-interference channel is completely characterized for all interference regimes. Using insights from the linear deterministic channel model, the symmetric feedback capacity of the Gaussian cyclic Z-interference channel is characterized up to within a constant number of bits. As a byproduct of the constant gap result, the symmetric generalized degrees of freedom with feedback for the Gaussian cyclic Z-interference channel are also characterized. These results highlight that the symmetric feedback capacities for both linear and Gaussian channel models are in general functions of K , the number of users. Furthermore, the capacity gain obtained due to feedback decreases as K increases.