Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:A discussion of particular channel estimation techniques is beyond the scope of this paper, therefore without loss of generality, we use the least-square (LS) channel estimator [14] in Sections IV and V due its widespread adoption in OFDM systems and low computational complexity.
Category: