Comparison of Heuristic and Optimal Subcarrier Assignment Algorithms

Wireless multi carrier approaches can support the simultaneous transmissions to several wireless termi- nals, each one getting only some of the available sub- carriers. Judiciously assigning subcarriers to terminals can be used to, e.g., increase the capacity of a wireless cell; however, the resulting assignment problem is diffi- cult. The first subproblem is to decide the number of car- riers assigned to each terminal. Then, carriers have to be assigned to individual terminals. For this assignment problem, we present in this paper an optimal but imprac- tical algorithm as well as two new heuristic ones, which have a considerably lower complexity and can be used in real systems. We show that the performance of even the simple heuristic algorithm is comparable with that of the optimal algorithm. The advanced heuristic increases the performance further, at a modest increase in complexity. Both heuristics are at most 5% off from the optimal algo- rithm's performance 1 .

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