A framework for integrated discrete-rate and power adaptation and user selection in heterogeneous wireless networks

This paper presents novel joint link adaptation and user selection (JLAUS) schemes to maximize a weighted sum of the average rates of wireless links sharing a spectrum, while their possibly different minimum required average rates and quality of service constraints are provisioned. The schemes take into account the instantaneous SNR of all links and select a link for transmission and set its rate and power in a jointly optimized manner. The links operate based on adaptive modulation and coding and power control over heterogeneous wireless fading channels. Two JLAUS schemes are presented. The first scheme provides a framework for integrated analysis and design of link adaptation and user selection and relies on a partitioning of the space of link SNRs into regions. In this setting, the second scheme offers a particular JLAUS design, which enjoys a polynomial design complexity. The design is performed before the transmission starts, based on closed form solutions. The proposed schemes can be easily applied to a multiple access or a broadcast network. Numerical results demonstrate how the proposed JLAUS schemes outperform the benchmark schemes, or effectively meet various user requirements.