Interference management and antenna downtilt in multi-antenna CoMP systems

Long Term Evolution (LTE)-Advanced has regarded both Coordinated Multi-Point (CoMP) and Multiple Input Multiple Output (MIMO) technologies as an efficient means of meeting the International Mobile Telecommunications (IMT)-Advanced requirements. In this context, efficient Radio Resource Allocation (RRA) strategies are required to exploit the available spatial degrees of freedom, coordinate the resources usage and manage the interference in order to obtain performance gains. This paper provides system-level analyses in a downlink multi-antenna CoMP system for the performance gains achieved with the inter-cell interference management through antenna downtilt and the use of interference estimates in RRA strategies such as spatial precoding and power allocation. For both spatial diversity and multiplexing schemes, the results showed that quite high performance gains in terms of system spectral efficiency are achieved through antenna downtilt and that RRA strategies always benefit from estimates of the inter-cell interference.