An activity in radio network planning that is all too often left till last, is that of assessing the radiated contribution spilling over international borders to see if the level exceeds the threshold requiring formal coordination. This can be a problem if not tackled up front, because coordination activities can be lengthy.

Within CEPT this situation is anticipated, and there are various criteria agreed to allow radiation either side of a border without extraordinary activity. Typically these agreements permit an administration to implement a station that radiates towards a border, as long as the field strength incident at and beyond the border do not exceed defined limits for not more than 10% of the time. The criteria include common methods for predicting propagation which include long term statistics to satisfy the time criterion.

To expedite network roll-out, it is often interesting to engineer the network design to meet the limits. This can be done by limiting sites close to the border, omitting sectors pointing towards the border, using terrain to screen radiation towards the border, or optimisation of power delivered to the antenna and sector pointing. Often these measures need to be used in combination. For example, a site on a hill close to a border will probably require more than antenna down-tilting to be satisfactory. Of course if a configuration causing these limits to be exceeded is essential, classic coordination activities are still possible, but plenty of time must be allowed, hence it is best to identify sites requiring coordination early on in network planning.

In respect of LTE, there are several recommendations for the various harmonised bands in CEPT including the ECC recommendations (08)02 for 900/1800 MHz, (11)04 for 800 MHz, (11)05 for 2600 MHz and (14)04 for 2300 MHz. The attached CEPT LTE cross border coordination spreadsheet gives an example of how to assess if a site requires coordination for the 800/900/1800 MHz bands, but could be easily extended to cover others.