Link Adaptation Performance Evaluation for a MIMO-OFDM Physical Layer in a Realistic Outdoor Environment

Abstract

This paper presents a downlink performance analysis of a link adaptation (LA) algorithm applied to a MIMO-OFDM physical layer (PHY) which is a popular candidate for future generation cellular communication systems. The new LA algorithm attempts to maximize throughput and adaptation between various modulation and coding schemes in combination with both space-time block codes (STBC) and spatial multiplexing (SM) is based on knowledge of SNR and H matrix determinant; the parameters which are found to have the most significant influences on the system throughput. By means of ray-tracing software, a detailed example coherent time-variant channel trace is generated. Subsequent application of physical layer simulation software to this channel trace yields throughput results for adaptive MIMO-OFDM for the cases of the proposed LA algorithm, an algorithm based on SNR only, an algorithm based on SNR and H matrix determinant with fixed threshold levels for different SM modes and the optimal case.