An effect of arrival time differences in space-time coded communication systems

One of main goals in developing next generation wireless communication systems is increasing the data rates and high reliability. A promising way to achieve this is combination of multiple-input and multiple-output signal processing with space-time coding scheme. Naguib et al. (1988), Tarokh et al. (1998), and Hammons et al. (2000) proposed several space-time code schemes, which offer higher coding and diversity gains and are suitable for broadband applications to improve the spectrum efficiency and/or reliability of wireless applications such as in-home delivery of HDTV signals for entertainment, or high-speed computer networks based on IEEE 802.11b. In their studies, it is assumed that the multiple transmitter and receiver chains are perfect and that there is no delay or phase error among channels. This assumption, however, is difficult to warrant in practice. The time difference between transmitter and propagation paths from each transmit antenna give rise to arrival time differences in each path, which increase symbol interference and degrade the performance at the mobile receiver units. Therefore, we focus our efforts on the arrival time differences and their effects on a commercially available MIMO systems. Furthermore, we propose a compensation algorithm for a Rayleigh fading model to minimize the effects of arrival time differences.