Spectrum sharing optimization model for OFDMA systems under joint time and frequency constraints

In this paper, we present a study on the spectrum sharing matter in orthogonal frequency division multiple access (OFDMA) systems under heterogeneous constraints leading to a joint time-frequency resource allocation model. To take advantage of the flexibility of the OFDMA-based resource allocation scheme, we analytically study the spectrum sharing matter by deriving an optimization problem that takes into account the heterogeneous time and frequency constraints. The solution of the formulated problem presents an optimal time-frequency allocation scheme based on optimal derivation of a frequency allocation function as well as a time sharing function. This solution can be seen as a cross-layer PHY-MAC solution as it combines frequency aspects (PHY level) that deal with the channel quality, and time aspects (MAC level) that ensure the quality of service (QoS) support. Simulation results demonstrate the efficiency of the proposed scheme in terms of QoS support and channel use optimization.