Statistical Characteristics of MIMO-OFDM Transmission Systems in a Multipath Environment Where the Delay Spreading Exceeds the Guard Interval

摘要

Orthogonal frequency division multiplex (OFDM) modulation systems can completely prevent intersymbol interference due to multipath propagation by providing a guard interval which is longer than the maximum delay hereafter we call "delay spreading." In an environment in which the delay spreading exceeds the guard interval, on the other hand, intersymbol interference occurs. This study considers a MIMO-OFDM system in which a MIMO configuration with high diversity gain is introduced into the OFDM modulation scheme, and discusses the transmission characteristics of maximal ratio combining transmission (single-stream transmission). It is shown that the MIMO-OFDM system is less affected by intersymbol interference due to the delay, even if the delay spread exceeds the guard interval, and that good performance is achieved. It is also shown that the channel response which is required in realtime control can be estimated with sufficient accuracy.