Is MAC Joint Decoding Optimal for Interference Channels?

Harsh interference is a major obstacle to achieve high capacity, especially when the state-of-the-art wireless networks intend to reuse the same resource. Information theoretic study shows that joint decoding with interference can achieve the sum capacity of a strong interference channel. However, the optimal joint decoding technique is too complex for practical applications, because it requires detecting and decoding all messages simultaneously. A two-user strong interference channel can be formed by two two- user multiple access channels (MACs), so a natural question arises as whether the decoding schemes optimal for the MAC remains optimal when applied to the interference channel. This paper investigates the relevant decoding techniques, namely the MAC rate splitting (RS) and iterative detection-decoding. Although these techniques have been shown to be optimal for MACs, we show that they cannot achieve the optimal performance anymore under interference channels.