Investigation of frequency-domain link adaptation for a 5-MHz OFDMA/HSDPA system

In this paper, we investigate frequency domain link adaptation (FDLA), e.g. utilizing the frequency selectivity of the channel in an OFDMA system. To make the study specific and based on realistic parameters, we re-use the specifications from a recent 3GPP 5-MHz OFDMA study item. The link adaptation and the frequency domain link adaptation are developed in a way compliant with the basic HSDPA specifications. With FDLA we show up to 75% cell throughput gain over the OFDMA reference system at the cost of increased uplink channel quality signaling overhead for frequency selective channels. We find that optimum waterfilling power distribution only provides a marginal gain over a simpler on/off equal power distribution algorithm per sub-carrier pool when signaling imperfections are taken into account.