SUBCARRIER AND BIT ALLOCATION SCHEME FOR THE MA PROBLEM BASED ON THE ANT COLONY OPTIMIZATION TO MINIMIZE POWER CONSUMPTION IN OFDMA SYSTEMS

Subcarrier and bit allocation for margin adaptive (MA) problem with goal of minimizing the transmit power consumption under a given requirement has become an important issue for providing efficient power saving design in downlink orthogonal frequency division multiplexing access (OFDMA) systems. However, the problem becomes NP-hard because it requires a great complex searching facility to find a bit and subcarrier combination which performs the best. To find the best combination without a full search, we propose an efficient subcarrier and bit allocation scheme for the MA problem based on the ant colony optimization (ACO) algorithm minimizing transmit power consumption with satisfaction of required bits. Simulation results show the proposed ACO based scheme provides better performance in terms of less transmit power consumption and faster convergence.