Performance Analysis of Space Time Coding on Mimo and Cooperative Diversity System
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Date
2011-07
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Addis Ababa University
Abstract
In a wireless network, users can relay information to exploit cooperative diversity, thereby
increasing reliability. The uses of multiple transmit and receive antennas (MIMO) can help
to exploit transmit and receive diversity respectively. This thesis discusses the application
of a technique called space time block coding (STBC) on a system based on the joint use
of cooperative diversity and MIMO schemes, which we hope intuitively that the system
performance can be increased further. A source node, equipped with two transmits
antennas, first encodes incoming data using STBC and then broadcasts the resulting code
to relay and destination nodes. Then, the two relay nodes, each equipped with single
antenna, either amplify-and-forward (AF) or decode-and-forward (DF) the received codes
to the destination. The destination node combines (e.g., using maximum ratio combining
(MRC)) signals received from the source’s and relay’s antennas and decodes the combined
signal in order to recover the original data. As the signals from the source and relay are
received through different paths, which are assumed to be spatially independent, spatial
diversity can be exploited. Compared with point-to-point transmission system and simple
Alamouti STBC system with no relays, AF based STBC system obtains one additional
benefit, achieving spatial diversity offered by the relays. Moreover, the STBC-based DF
cooperative system has two additional benefits. First, it achieves the spatial diversity
offered by the relay channel and secondly, it has the ability to introduce the characteristics
of STBC into the relay system. In addition, the system model and performance evaluation
of these systems in various channel conditions and modulations (using simulation) will be
addressed.
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Keywords
Diversity System