Protecting Legacy Wireless Systems Against Interference Using Massive MIMO

The growing demand for high-speed wireless communication has generated considerable interest in using frequency bands adjacent to those occupied by legacy wireless systems. Since legacy wireless systems were designed for past spectral usage, when bands were sparsely used, utilizing these new bands will lead to interference with the legacy users. Therefore, it is essential to develop signaling schemes that can protect legacy users from such interference. For many applications, legacy users are located within a geographically constrained region. In this paper, we use the knowledge of this region to limit the interference at legacy users. We achieve this by incorporating received power constraints termed as region constraints, in the massive multiple-input multiple-output (MIMO) system design. We perform a sum-rate analysis of the multi-user massive MIMO system with transmit power and region constraints.