A new frequency-domain link adaptation scheme for broadband OFDM systems

Abstract

This paper proposes an OFDM-oriented link adaptation scheme with new frequency-domain-based link quality estimation functions. System throughput of an OFDM system can be enhanced by using link adaptation; the best set of modulation scheme and FEC coding rate is dynamically selected to achieve the target packet error rate (PER) before ARQ. An important practical issue in applying link adaptation is how to estimate the link quality precisely. Link quality is well assessed by carrier/noise ratio (CNR) and the delay spread. Two link quality estimation functions are introduced; one examines the correlation between subcarriers while the another considers CNR. Both are simple to implement in combination with the frequency-domain initial equalizer. Simulation results verify that the proposed link adaptation scheme is effective in improving system throughput in a practical manner.