An improved heuristic algorithm for over-the-cell channel routing

At any iterative step, a net interval is chosen for over-the-cell routing such that: (i) it dilutes the portion of the channel having the maximum congestion and span, and (ii) it subsequently forces the smallest set of other nets to be routed inside the channel. Furthermore, selection of over-the-cell candidates on the top and bottom sides of the channel is carried out simultaneously, rather than the by usual practice of treating them in isolation. A heuristic cost function befitting the authors needs is introduced for guiding the search. Experiments on standard benchmarks establish the superiority of the proposed method over other techniques