3 research outputs found
Does fast adaptive modulation always outperform slow adaptive modulation?
Link adaptation techniques are important modern
and future wireless communication systems to cope with quality
of service fluctuations in fading channels. These techniques
require the knowledge of the channel state obtained with a
portion of resources devoted to channel estimation instead of data
and updated every coherence time of the process to be tracked. In
this paper, we analyze fast and slow adaptive modulation systems
with diversity and non-ideal channel estimation under energy
constraints. The framework enables to address the following
questions: (i) What is the impact of non-ideal channel estimation
on fast and slow adaptive modulation systems? (ii) How to
define a proper figure of merit which considers both resources
dedicated to data and those to channel estimation? (iii) Does
fast adaptive always outperform slow adaptive techniques? Our
analysis shows that, despite the lower complexity and feedback
rate, slow adaptive modulation (SAM) can achieve higher spectral
efficiency than fast adaptive modulation (FAM) in the presence
of energy constraint, diversity, and non-ideal channel estimation.
In addition, SAM satisfies bit error outage requirements also in
FAM-denied region