The position of the RSs in a frequency domain is related to the PCI of the cell. By separating the RS position of a local cell from that of its neighboring cells, the interference between RSs is reduced, which improves overall network performance (tests have indicated that a 3 dB increase in SINR can be gained in a cell with 50% load).
The RS position varies for PCI MOD3 (2/4 antenna) and PCI MOD 6 (single antenna). The following table lists a PCI plan, in which PCI MOD 3 determines the pilot position. The following figure shows the RS position distribution. Different colors indicate the positions of different RSs. Because the plan uses 2-path antennas, the pilot position takes three values.
Planning example:
