Differential Coding for MIMO and Cooperative Communications
نویسنده
چکیده
Multiple-input multiple-output (MIMO) wireless communication systems have been studied a lot in the last ten years. They have many promising features like array gain, diversity gain, spatial multiplexing gain, interference reduction, and improved capacity as compared to a single-input single-output (SISO) systems. However, the increasing demand of high data-rate in current wireless communications systems motivated us to investigate new rate-efficient channel coding techniques. In this dissertation, we study differential modulation for MIMO systems. Differential modulation is useful since it avoids the need of channel estimation by the receiver and saves valuable bandwidth with a slight symbol error-rate (SER) performance loss. The effect of channel correlation over differential MIMO system has not been studied in detail so far. It has been shown in the literature that a linear memoryless precoder can be used to improve the performance of coherent MIMO system over correlated channels. In this work, we implement precoded differential modulation for non-orthogonal and orthogonal space-time blocks codes (STBCs) over arbitrarily correlated channels. We design precoders based on pair-wise error probability (PEP) and approximate SER for differential MIMO system. The carrier offsets, which result because of the movement of the receiver or transmitter and/or scatterers, and mismatch between the transmit and receive oscillators, are a big challenge for the differential MIMO system. The carrier offsets make the flat fading channel behave as a timevarying channel. Hence, the channel does not remain constant over two consecutive STBC block transmission time-intervals, which is a basic assumption for differential systems and the differential systems break down. Double-differential coding is a key technique which could be used to avoid the need of both carrier offset and channel estimation. In this work, we propose a double-differential coding for full-rank and square orthogonal space-time block codes (OSTBC) with M-PSK constellation. A suboptimal
منابع مشابه
Differential Modulation for Broadband
Title of Dissertation: DIFFERENTIAL MODULATION FOR BROADBAND SPACE-TIME/COOPERATIVE WIRELESS COMMUNICATIONS Thanongsak Himsoon, Doctor of Philosophy, 2006 Dissertation directed by: Professor K. J. Ray Liu Department of Electrical and Computer Engineering Among various diversity techniques to combat fading in wireless channels, spatial diversity through MIMO coding scheme is an effective way to ...
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