De-Hyping Transmit Diversity in Modern MIMO Cellular Systems

Abstract

Abstract-A contemporary perspective on the tradeoff between transmit antenna diversity and spatial multiplexing is provided. It is argued that, in the context of modern cellular systems and for the operating points of interest, transmission techniques that utilize all available spatial degrees of freedom for multiplexing outperform techniques that explicitly sacrifice spatial multiplexing for diversity. Reaching this conclusion, however, requires that the channel and some key system features be adequately modeled; failure to do so may bring about starkly different conclusions. As a specific example, this contrast is illustrated using the 3GPP Long-Term Evolution system design.

Analytical approach of an FSO Link with alamouti- type STBC considering weak atmospheric turbulence

“…Free space optical (FSO) communication is a very promising and cost effecting technology for the future optical communication networks (Andrews et al, 2001;Arnon, 2003;Vincent, 2006). A major impairment in FSO links is the atmospheric turbulence-induced fading which causes fluctuations in both the intensity and phase of the received light signal which results in impairments of the link performance (Antonio, 2007;Jindal and Lozano, 2010;Bhuiyan et al, 2010;Tarokh et al, 1999;Huang et al, 1993;Zhu and Kahn, 2002). For free space optical transmission systems, most frequently used system is Intensity Modulated Direct Detection (IM/DD) system.…”