Multiple Access Outerbounds and the Inseparability of Parallel Interference Channels

Abstract

It is known that the capacity of parallel (multi-carrier) 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 counter-example is provided in the form of a 3 user interference channel where separate encoding can only achieve a sum capacity of $\log (SNR)+o(\log (SNR))$ per carrier while the actual capacity, achieved only by joint-encoding across carriers, is $3/2\log (SNR))+o(\log (SNR))$ per carrier. As a byproduct of our analysis, we propose a class of multiple-access-outerbounds on the capacity of the 3 user interference channel.

References in corpus (2)

• Degrees of Freedom Region for the MIMO X Channel
• Interference Alignment on the Deterministic Channel and Application to Fully Connected AWGN Interference Networks

Cited by in corpus (5)

• Ergodic Fading Interference Channels: Sum-Capacity and Separability
• Ergodic Interference Alignment
• Delay-rate tradeoff for ergodic interference alignment in the Gaussian case
• Capacity of a Class of Linear Binary Field Multi-source Relay Networks
• Outage analysis of Block-Fading Gaussian Interference Channels