This paper considers the problem of interference mitigation in
  multi-cell multi-antenna time division duplex (TDD) wireless systems
  for downlink transmission. An efficient way to obtain channel state
  information (CSI) at the base station is by using uplink pilots and
  reciprocity of the downlink channel. At the same time, it has been
  shown that pilots from different cells contaminate each other,
  resulting in corruption of precoding matrices used by base stations,
  and high inter-cell interference. This paper studies the effects of
  shifting the location of pilots in time frames used in neighboring
  cells, and its effectiveness in obtaining better channel estimates,
  and, thereby, inter-cell interference reduction.