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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design of concurrent cooperative transmission systems on software-defined radios

Chang, Yong Jun 13 January 2014 (has links)
Concurrent cooperative transmission (CCT) occurs when a collection of power-constrained single-antenna radios transmit simultaneously to form a distributed multi-input and multi-output (DMIMO) link. DMIMO can be a means for highly reliable and low-latency cooperative routing, when the MIMO channel is exploited for transmit and receive diversity; in this context, the range extension benefit is emphasized. Alternatively, DMIMO can be a means for high-throughput ad hoc networking, when the MIMO channel is used with spatial multiplexing. In both cases, concatenated DMIMO links are treated. The key contribution of this dissertation is a method of pre-synchronization of distributed single-antenna transmitters to form a virtual antenna array, in the absence of a global clock, such as a global positioning system (GPS) receiver or a network time protocol (NTP) to provide reference signals for the synchronization. Instead, the reference for synchronization comes from a packet, transmitted by the previous virtual array and simultaneously received by all the cooperative transmitters for the next hop. The method is realized for two types of modulation: narrowband non-coherent binary frequency-shift keying (NCBFSK) and wideband orthogonal frequency division multiplexing (OFDM). The pre-synchronization algorithms for transmission are designed to minimize the root-mean-square (RMS) transmit time, sampling and carrier frequency error between cooperative transmitters, with low implementation complexity. Since CCT is not supported by any existing standard or off-the-shelf radios, CT must be demonstrated by using software-defined radios (SDRs). Therefore, another contribution is a fully self-contained and real-time SDR testbed for CCT-based networking. The NCBFSK and OFDM systems have been designed and implemented in C++ and Python programming languages in the SDR testbed, providing practical performance of the CCT-based systems.

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