Integrated scheduling and link adaptation for heterogeneous networks: design and performance analysis

Abstract

ABSTRACT This paper presents novel integrated scheduling and link adaptation (ISLA) schemes for links which have a common spectrum and possibly different rates and reliability constraints. We consider the problem of weighted sum average rate maximisation of wireless links. In an orthogonal transmission system, a link is selected using instantaneous signal-to-noise (SNR) of all the links, and its rate and power are set in a jointly optimised manner. To demonstrate the effectiveness of the proposed approach, we analyse ISLA schemes with continuous rate adaptation using constant or adaptive transmission powers. ISLA schemes are designed in similar settings for practical discrete rate-adaptive systems using adaptive modulation and coding. To this end, a design framework is presented, which relies on a partitioning of space of links’ SNRs into regions, similar to structured vector quantisation. Within this framework, a particular ISLA design with high performance and polynomial complexity is suggested. The proposed schemes are designed before the start of the transmission, based on closed-form solutions, and can easily be applied to multiple access or broadcast networks. We also analyse several schemes for comparison, which employ modified Round-Robin, opportunistic scheduling or online generalised scheduling. Numerical results demonstrate how the proposed ISLA schemes outperform the benchmark schemes and effectively meet various user requirements.1