The frequency assignment problem (FAP) asks for assigning frequencies (channels) in a wireless network from the available radio spectrum to the transceivers of the network. One of the graph theoretical models of FAP is the L(3, 2, 1)‐labeling of a graph, which is an abstraction of assigning integer frequencies to radio transceivers such that (i) transceivers that are one unit of distance apart receive frequencies that differ by at least three, (ii) transceivers that are two units of distance apart receive frequencies that differ by at least two, and (iii) transceivers that are three units of distance apart receive frequencies that differ by at least one. The relaxation of the L(3, 2, 1)‐labeling called the (s, t, r)‐relaxed k‐L(3, 2, 1)‐labeling is proposed in this paper. This concept is a generalization of the (s, t)‐relaxed k‐L(2, 1)‐labeling (Lin in J Comb Optim 2016, doi: 10.1007/s10878-014-9746-9). Basic properties of (s, t, r)‐relaxed k‐L(3, 2, 1)‐labeling are discussed and optimal (s, t, r)‐relaxed k‐L(3, 2, 1)‐labelings for paths and some cycles as well as for the hexagonal lattice and the square lattice are determined.
