Providing quality of service in adaptive resource allocation for OFDMA systems

We consider the quality of service (QoS) provision in the adaptive resource allocation of the orthogonal frequency division multiplexing (OFDM) multiple access (OFDMA) systems. We propose a two-step approach for a multiple QoS support, which can maximize the total data rate of each OFDMA symbol transmission while satisfying different QoS requirements of both delay-sensitive and data rate-sensitive traffic in OFDMA systems. The proposed algorithm determines the subchannel, bit and power allocation by decoupling an NP-hard combinatorial problem into two steps: (1) subchannel assignment based on users´ QoS cost function (a function of QoS constraints such as maximum allowable delay or average data rate requirement) and channel profile on each subchannel; (2) bit and power allocation to maximize the total data rate of the OFDM transmission symbol. The simulation shows that the proposed two-step approach provides well controlled QoS provisions while maintaining the flexibility of the multiple QoS support.