Iterative spectrum shaping with opportunistic multiuser detection

This paper studies a new decentralized resource allocation strategy, named iterative spectrum shaping (ISS), for a multi-carrier-based spectrum sharing system, where two co-existing users independently and sequentially update transmit power allocation over parallel subcarriers to maximize their individual transmit rates. Unlike the conventional iterative water-filling (IWF) algorithm that applies the single-user detection (SD) at each user receiver by treating the interference from the other user as additional noise, the proposed ISS algorithm opportunistically applies multiuser detection techniques to decode both the desired user and interference user messages, thus termed as opportunistic multiuser detection (OMD). For OMD, this paper derives the optimal user power and rate allocation strategy at each iteration of transmit adaptation. Numerical examples show that the proposed ISS deploying OMD is able to achieve substantial throughput gains over the conventional IWF deploying SD in decentralized spectrum sharing systems.