Adaptive link adaptation

Link adaptation (LA) can significantly increase the spectral efficiency and render various levels of services, both of which are highly desirable for today´s high-speed communication systems. Although optimality can be ensured through careful designing for a fixed link configuration, due to changes of available power, data rate, and especially channel statistics, it is better to adapt the adaptation scheme per se in real time. We term this technique adaptive link adaptation (ALA). Based on our previous work on a general optimal link adaptation scheme for a certain configuration, we continue to investigate the problem of adapting the adaptation scheme online. This paper first recapitulates that general optimal link adaptation scheme, then gives the theoretic basis of ALA, and finally presents a simple yet working implementation of the update algorithm for ALA. Both theoretical and simulation results indicate the viability of ALA and an 18 dB gain can be achieved for the investigated simple scenario. With low complexity, optimality, and generality, the proposed ALA provides a promising technique to substantially increase the spectral efficiency of practical communication systems