TY - JOUR
T1 - Parallel Gaussian interference channels are not always separable
AU - Cadambe, Viveck R.
AU - Jafar, Syed A.
N1 - Funding Information:
Manuscript received February 15, 2008; revised March 17, 2009. Current version published August 19, 2009. This work was supported by DARPA IT-MANET under Grant UTA06-793. The material in this paper was presented in part at the IEEE GLOBECOM 2008, New Orleans, LA, December 2008 The authors are with the Center for Pervasive Communications and Computing, Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697 USA (e-mail: [email protected]; syed@uci. edu). Communicated by G. Kramer, Associate Editor for Shannon Theory. Color version of Figure 2 in this paper is available online at http://ieeexplore. ieee.org. Digital Object Identifier 10.1109/TIT.2009.2025530
PY - 2009
Y1 - 2009
N2 - It is known that the capacity of parallel (multicarrier) Gaussian point-to-point, multiple access and broadcast channels can be achieved by separate encoding for each subchannel (carrier) subject to a power allocation across carriers. In this paper we show that such a separation does not apply to parallel Gaussian interference channels in general. A counterexample is provided in the form of a 3 user interference channel where separate encoding can only achieve a sum capacity of 2 log(1 + 3 SNR) while the actual capacity, achieved only by joint encoding across carriers, is 3 log(1 + 2 SNR). As a byproduct of our analysis, we propose a class of multiple-access-outer bounds on the capacity of the 3 user interference channel.
AB - It is known that the capacity of parallel (multicarrier) Gaussian point-to-point, multiple access and broadcast channels can be achieved by separate encoding for each subchannel (carrier) subject to a power allocation across carriers. In this paper we show that such a separation does not apply to parallel Gaussian interference channels in general. A counterexample is provided in the form of a 3 user interference channel where separate encoding can only achieve a sum capacity of 2 log(1 + 3 SNR) while the actual capacity, achieved only by joint encoding across carriers, is 3 log(1 + 2 SNR). As a byproduct of our analysis, we propose a class of multiple-access-outer bounds on the capacity of the 3 user interference channel.
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U2 - 10.1109/TIT.2009.2025530
DO - 10.1109/TIT.2009.2025530
M3 - Article
AN - SCOPUS:69449085086
SN - 0018-9448
VL - 55
SP - 3983
EP - 3990
JO - IEEE Transactions on Information Theory
JF - IEEE Transactions on Information Theory
IS - 9
ER -