The present invention relates to a method, apparatus and computer program product for allocating resource units to a plurality of users in a multiplex transmission system. A transmission quality of available resource units to be allocated is determined for each user, and the resource unit with the highest transmission quality is allocated to the respective strongest user for which the highest transmission quality has been determined. An allocation range of the strongest user is expanded by allocating adjacent resource units to the strongest user as long as the determined transmission quality of the adjacent resource units is still the highest. Resource units with highest transmission quality among the remaining resource units are allocated to the respective remaining users and their allocation ranges are expanded as long as transmission quality of the adjacent resource units is still the highest among the remaining resource units.