A method performed by a management node configured as a network node for automatic physical cell ID, PCI, allocation to a plurality of cell sites in a radio access network, RAN, (101, 1202), the method comprising: identifying a cell site of the plurality of cell sites, the cell site to be allocated a PCI group, wherein the cell site is the location of a base station, and wherein the PCI group is based on available count of PCIs and the number of carriers per sector of cell site; from a group of cell sites in the RAN that have already been assigned a plurality of PCI groups, respectively, for each PCI group: identifying, a closest neighbor cell site assigned to the PCI group, and providing, for the closest neighbor cell site a distance from the cell site, a tier relationship to the cell site, and relative bearings between the cell site and the closest neighbor cell site; determining whether a first one or more closest neighbor cell sites of a plurality of the identified closest neighbor cell sites meet a first criterion of having a distance greater than a cluster distance, wherein the cluster distance is a distance beyond which radio interference between any two sectors of any two cell sites, respectively, having same PCI disappears; allocating the PCI group of a first closest neighbor cell site of the first one or more closest neighbor sites to the cell site, wherein the first closest neighbor cell site has the maximum distance from the cell site, among the first one or more closest neighbor sites; and if none of the plurality of the identified closest neighbor cell sites meet the first criterion, determining a second one or more closest neighbor cell sites of the plurality of the identified closest neighbor cell sites that meet a second criterion of a lack of coverage overlap between any sector of the cell site and any sector of any of the second one or more of the closest neighbor cell site; and if the second criterion is met, allocating the PCI group of a second closest neighbor cell site of the second one or more closest neighbor sites to the cell site, wherein the second closest neighbor cell site has the maximum distance from the cell site, among the second one or more closest neighbor sites. identifying a cell site of the plurality of cell sites, the cell site to be allocated a PCI group, wherein the cell site is the location of a base station, and wherein the PCI group is based on available count of PCIs and the number of carriers per sector of cell site; from a group of cell sites in the RAN that have already been assigned a plurality of PCI groups, respectively, for each PCI group: identifying, a closest neighbor cell site assigned to the PCI group, and providing, for the closest neighbor cell site a distance from the cell site, a tier relationship to the cell site, and relative bearings between the cell site and the closest neighbor cell site; determining whether a first one or more closest neighbor cell sites of a plurality of the identified closest neighbor cell sites meet a first criterion of having a distance greater than a cluster distance, wherein the cluster distance is a distance beyond which radio interference between any two sectors of any two cell sites, respectively, having same PCI disappears; allocating the PCI group of a first closest neighbor cell site of the first one or more closest neighbor sites to the cell site, wherein the first closest neighbor cell site has the maximum distance from the cell site, among the first one or more closest neighbor sites; and if none of the plurality of the identified closest neighbor cell sites meet the first criterion, determining a second one or more closest neighbor cell sites of the plurality of the identified closest neighbor cell sites that meet a second criterion of a lack of coverage overlap between any sector of the cell site and any sector of any of the second one or more of the closest neighbor cell site; and if the second criterion is met, allocating the PCI group of a second closest neighbor cell site of the second one or more closest neighbor sites to the cell site, wherein the second closest neighbor cell site has the maximum distance from the cell site, among the second one or more closest neighbor sites.