[Paper Review] Interference Channel with State Information

Lili Zhang, Jiang, Jinhua+1 more|arXiv (Cornell University)|Apr 19, 2011

Wireless Communication Security Techniques15 references5 citations

TL;DR

This paper proposes two novel coding schemes—simultaneous and superposition encoding—combined with rate splitting and Gel'fand-Pinsker coding for the two-user interference channel with non-causally known state information at transmitters. For the Gaussian case, it introduces active interference cancellation via generalized dirty-paper coding, significantly enlarging the achievable rate region, especially in strong and mixed interference regimes.

ABSTRACT

In this paper, we study the state-dependent two-user interference channel, where the state information is non-causally known at both transmitters but unknown to either of the receivers. We first propose two coding schemes for the discrete memoryless case: simultaneous encoding for the sub-messages in the first one and superposition encoding in the second one, both with rate splitting and Gel'fand-Pinsker coding. The corresponding achievable rate regions are established. Moreover, for the Gaussian case, we focus on the simultaneous encoding scheme and propose an \emph{active interference cancellation} mechanism, which is a generalized dirty-paper coding technique, to partially eliminate the state effect at the receivers. The corresponding achievable rate region is then derived. We also propose several heuristic schemes for some special cases: the strong interference case, the mixed interference case, and the weak interference case. For the strong and mixed interference case, numerical results are provided to show that active interference cancellation significantly enlarges the achievable rate region. For the weak interference case, flexible power splitting instead of active interference cancellation improves the performance significantly.

Motivation & Objective

• To address the capacity gap in the two-user interference channel under state-dependent interference where state information is non-causally available at transmitters but not at receivers.
• To extend existing point-to-point state-dependent channel techniques—like Gel'fand-Pinsker and dirty-paper coding—to the multi-user interference channel setting.
• To develop practical coding strategies that exploit state knowledge at transmitters to mitigate interference and improve spectral efficiency.
• To characterize achievable rate regions for both discrete memoryless and Gaussian interference channels with state, including special-case heuristics for strong, mixed, and weak interference regimes.

Proposed method

• Proposes two coding schemes: one using simultaneous encoding of sub-messages and another using superposition encoding, both integrated with rate splitting and Gel'fand-Pinsker coding.
• Derives achievable rate regions for the discrete memoryless interference channel with state by characterizing mutual information constraints involving auxiliary random variables (U, V, Q) and the state S.
• Introduces active interference cancellation in the Gaussian case as a generalization of dirty-paper coding, using power allocation to partially cancel the common additive Gaussian state at receivers.
• Applies time-sharing across transmission strategies to enlarge the achievable rate region in strong, mixed, and weak interference cases.
• Optimizes dirty-paper coding parameters for one or both multiple access channels (MACs) formed by common and private messages to maximize sum rate.
• Employs sequential decoding and power splitting in the weak interference case to improve performance, replacing active cancellation.

Experimental results

Research questions

• RQ1 How can state information non-causally known at transmitters be exploited to improve spectral efficiency in a two-user interference channel?
• RQ2 What are the achievable rate regions for the discrete memoryless and Gaussian interference channels with state, when both transmitters know the state in advance?
• RQ3 In what scenarios does active interference cancellation via generalized dirty-paper coding outperform conventional schemes?
• RQ4 How do heuristic strategies based on rate splitting and power allocation improve performance in weak, strong, and mixed interference regimes?
• RQ5 What is the impact of optimizing dirty-paper coding parameters and time-sharing on the achievable rate region in state-dependent interference channels?

Key findings

• The proposed simultaneous encoding scheme with rate splitting and Gel'fand-Pinsker coding achieves a larger achievable rate region than conventional schemes in the discrete memoryless case.
• For the Gaussian case, active interference cancellation via generalized dirty-paper coding significantly enlarges the achievable rate region, particularly in strong and mixed interference regimes.
• Numerical results show that active interference cancellation provides substantial rate gains in strong and mixed interference cases, with performance improvements quantified relative to baseline schemes.
• In the weak interference regime, flexible power splitting outperforms active interference cancellation, achieving better spectral efficiency by balancing interference and signal power.
• Time-sharing across optimized transmission strategies further expands the achievable rate region, especially in strong and mixed interference scenarios.
• The derived rate constraints are shown to be non-negative under proper choice of probability distributions, ensuring vanishing error probability as blocklength increases.