Performance of OFDMA Multicell Systems with Opportunistic Beamforming

The opportunistic beamforming (OB) technique in multicellular OFDMA networks is investigated in this paper. Three cross-layer radio resource management (RRM) algorithms for OFDMA operational scenarios are considered. These algorithms build upon typical network planning practices for OFDMA systems. The first two implement an OFDMA network with opportunistic rate adaptation while the third one aims at a network which guarantees QoS provision through power control on carrier basis. The RRM algorithms are based on typical OFDMA resource allocation targets such as minimization of transmit power, maximization of throughput and interference averaging. Then, the OB concept is combined with the considered RRM algorithms and a comparative performance analysis between the two types of resulted networks (omni and opportunistic beamforming) 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.