Opportunistic Beamforming in OFDMA Systems

The opportunistic beamforming (OB) technique in multicellular OFDMA networks is investigated in this paper. For this reason, three cross-layer radio resource management (RRM) algorithms for OFDMA operational scenarios that are based on typical resource allocation targets such as minimization of transmit power, maximization of throughput and interference averaging are considered. The OB concept is combined with the considered RRM algorithms and a comparative performance analysis between the two types of resulted networks (omni and OB) is performed in terms of throughput, blocking probability and fairness. The simulation results suggest that OB is preferred for OFDMA systems with opportunistic rate adaptation rather than power controlled systems which offer QoS provision. According to the presented results, OB provides to OFDMA systems with opportunistic rate adaptation a ~13% throughput gain and ~75% gain in terms of blocking probability. In addition, it is shown that the combination of OB with interference averaging RRM algorithms has a minor beneficial impact only on the system fairness.