Joint interference mitigation approach using space-time pilot design in large-scale antenna systems

This study addresses the problem of interference mitigation in multi-cell time division duplex cellular networks with large-scale antennas. Network performance in such systems is hampered by pilot contamination effect, which results in the inter-cell interference. To mitigate the interference, the authors propose a space-time pilot design-based approach to jointly eliminate interference from both time domain and space domain. The authors’ space-time pilot design divides a cellular network into different groups which proceed channel estimation alternately in time. Moreover, a low-rate coordination assisted pilot assignment scheme is added into each cell group during its pilot phase. This pilot assignment scheme relies on the minimum mean square of the updated Bayesian channel estimation. It can make use of the second-order statistical information about the users' channel vectors within the same group to assign an identical pilot sequence to users that tend to interfere with each other at a lower level. On the basis of space-time pilot design, the base station can proceed the maximal ratio transmitting and maximal ratio combining. With rigorous theoretic proof, their joint approach is able to significantly decrease interference. Simulations verified its excellent performance promotion.