A cell of a wireless radio communication network is divided in N substantially
identical sectors S1, S2, . . . , SN looking out from a base station.
Sector Si is contiguous to sectors Si-1 and Si+1 for 2iN-1. N frequencies
f1f2 . . . fN are available for transmitting signal
from the base station to radio terminals located in the cell. At a predefined time
slot, the frequency used in the sectors S1, . . . , SN respectively is the
following: f1; f3; f5; . . . ;f2n-1; f2; f4;
f6 . . . ; f2n; if N=2n, or f1; f3; f5; . . . ; f2n-1;
f2n+1; f2; f4; f6 . . . ; f2n; if N=2n+1. The frequency used
in the sectors at any subsequent time slot is a cyclic permutation of the previous sequence.