In order to achieve broadband communication between a fixed access point and mobile user terminals in an indoor nondirected LOS infrared wireless system, we consider the concept of rate-adaptive transmission, based on DMT modulation of multiple orthogonal subcarriers. The previously conducted capacity analysis showed great potentials compared to statically operating links, with up to 400 Mb/s conceivable under good channel conditions. In this paper we focus on the throughput maximization in practical modulation-adaptive IR systems. We evaluate the applicability and performance of two bit-loading algorithms developed originally for DSL transmission, with the aim to determine the recommendable loading technique for the specific conditions of optical wireless channel.