A Deterministic Initialization for Optimizing Carrier-Cooperative Transmit Strategies

Even though capacity can be achieved in parallel multiple-input multiple-output (MIMO) broadcast channels by coding separately on each carrier, joint coding across carriers (socalled carrier-cooperative transmission) can lead to performance gains in MIMO broadcast channels with a restriction to linear transceivers. In principle, carrier-cooperative transmission can be optimized in an equivalent single-carrier MIMO system, but it has been shown that most existing optimization algorithms lead to solutions that are equivalent to carrier-noncooperative transmission. The only exception discussed in the literature is the application of iterative algorithms with a random initialization. In this paper, we show that randomness is not a requirement to obtain good carrier-cooperative solutions. We do so by proposing a deterministic carrier-cooperative initialization that has good performance in numerical simulations as well as interesting interpretations: it can be interpreted in the context of equal gain transmission and based on the notion of mutual incoherence.