Ergodic Interference Alignment

Abstract

This paper develops a new communication strategy, ergodic interference alignment, for the K-user interference channel with time-varying fading. At any particular time, each receiver will see a superposition of the transmitted signals plus noise. The standard approach to such a scenario results in each transmitter-receiver pair achieving a rate proportional to 1/K its interference-free ergodic capacity. However, given two well-chosen time indices, the channel coefficients from interfering users can be made to exactly cancel. By adding up these two observations, each receiver can obtain its desired signal without any interference. If the channel gains have independent, uniform phases, this technique allows each user to achieve at least 1/2 its interference-free ergodic capacity at any signal-to-noise ratio. Prior interference alignment techniques were only able to attain this performance as the signal-to-noise ratio tended to infinity. Extensions are given for the case where each receiver wants a message from more than one transmitter as well as the "X channel" case (with two receivers) where each transmitter has an independent message for each receiver. Finally, it is shown how to generalize this strategy beyond Gaussian channel models. For a class of finite field interference channels, this approach yields the ergodic capacity region.

16 pages, 6 figure, To appear in IEEE Transactions on Information Theory

References in corpus (7)

• The Approximate Capacity of the Many-to-One and One-to-Many Gaussian Interference Channels
• Interference Alignment and the Degrees of Freedom for the K User Interference Channel
• Ergodic Fading Interference Channels: Sum-Capacity and Separability
• Retrospective Interference Alignment
• Delay-rate tradeoff for ergodic interference alignment in the Gaussian case
• Interference Alignment for Line-of-Sight Channels
• On the Secrecy Rate of Interference Networks using structured codes

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• Ergodic Fading Interference Channels: Sum-Capacity and Separability
• Optimal Repair of MDS Codes in Distributed Storage via Subspace Interference Alignment
• Aiming Perfectly in the Dark - Blind Interference Alignment through Staggered Antenna Switching
• Compute-and-Forward: Harnessing Interference through Structured Codes
• On Secrecy Capacity Scaling in Wireless Networks
• Real Interference Alignment
• Scalable Capacity Bounding Models for Wireless Networks
• Capacity of a Class of Linear Binary Field Multi-source Relay Networks
• Degrees of Freedom of Multi-Source Relay Networks
• Sum-Capacity and the Unique Separability of the Parallel Gaussian MAC-Z-BC Network
• Interference Alignment at Finite SNR for Time-Invariant Channels
• Degrees of Freedom Region of a Class of Multi-source Gaussian Relay Networks
• K-User Fading Interference Channels: The Ergodic Very Strong Case
• Ergodic Secret Alignment
• Ergodic Layered Erasure One-Sided Interference Channels
• Sum capacity of multi-source linear finite-field relay networks with fading