The emerging ultrawideband (UWB) system offers a great potential for the design of high speed short-range wireless communications. In order to satisfy the growing demand for higher data rates, one possible solution is...
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The emerging ultrawideband (UWB) system offers a great potential for the design of high speed short-range wireless communications. In order to satisfy the growing demand for higher data rates, one possible solution is to exploit both spatial and multipath diversities via the use of multiple-input multiple-output (MIMO) and proper coding techniques. In this paper, we propose a general framework to analyze the performance of multiband UWB-MIMO systems regardless of specific coding schemes. A combination of space-time-frequency (STF) coding and hopping multiband OFDM modulation is also proposed to fully exploit all of the available spatial and frequency diversities, richly inherent in UWB environments. We quantify the performance merits of the proposed scheme in case of Nakagami-m frequency-selective fading channels. Different from the conventional STF coded MIMO-OFDM system, the performance of the STF coded hopping multiband UWB does not depend on the temporal correlation of the propagation channel. We show that the maximum achievable diversity of multiband UWB-MIMO system is the product of the number of transmit and receive antennas, the number of multipath components, and the number of jointly encoded OFDM symbols. Interestingly, the diversity gain does not severely depend on the fading parameter m, and the diversity advantage obtained under Nakagami fading with arbitrary m parameter is almost the same as that obtained in Rayleigh fading channels. Finally, simulation results are presented to support the theoretical analysis.
A new multi-antenna coding framework is proposed for space-time-frequency (STF) transmissions over broadband Multiple Input Multiple Output (MIMO) systems based on Orthogonal frequency Division Multiplexing (OFDM). A ...
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ISBN:
(纸本)9781424436446
A new multi-antenna coding framework is proposed for space-time-frequency (STF) transmissions over broadband Multiple Input Multiple Output (MIMO) systems based on Orthogonal frequency Division Multiplexing (OFDM). A tensor decomposition known as PARAFAC is used as the core of a multi-stream space-time-frequency coder that jointly multiplex and spreads several input streams over space (transmit antennas), time (symbol periods) and frequency (subcarriers). We coin the term trilinear STF codes since each input symbol is coded over a space-time-frequency grid by a triple product code: each trilinearly coded symbol is interpreted as an element of a third-order tensor, which can be decomposed using PAFAFAC analysis. Trilinear STF codes are designed for an arbitrary number of transmit and receive antennas. They afford a variable degree of multiplexing-spreading over each one of the three signal dimensions while providing full diversity gain for each multiplexed stream. At the receiver, a direct blind decoding based on a relatively simple linear processing is made possible thanks to the PARAFAC modeling of the received signal. Computer simulation results are provided for performance assessment of the proposed codes in a variety of configurations.
Multiple input multiple output (MIMO) communication systems with orthogonal frequency division multiplexing (OFDM) modulation have a great potential to play an important role in the design of the next-generation broad...
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Multiple input multiple output (MIMO) communication systems with orthogonal frequency division multiplexing (OFDM) modulation have a great potential to play an important role in the design of the next-generation broadband wireless communication systems. In this paper, we address the problem of performance analysis and code design for MIMO-OFDM systems when coding is applied over both spatial, temporal, and frequency domains. First, we provide an analytical framework for the performance analysis of MIMO-OFDM systems assuming arbitrary power delay profiles. Our general framework incorporates the space-time and space-frequency (SF) coding approaches as special cases. We also determine the maximum achievable diversity order, which is found to be the product of the number of transmit and receive antennas, the number of,delay paths,. and the rank of the temporal correlation matrix. Then, we propose two code design methods that are guaranteed to achieve the maximum diversity order. The first method is a repetition coding approach using full-diversity SF codes, and the second method is a block coding approach that can guarantee both full symbol rate and full diversity. Simulation results are also presented to support the theoretical analysis.
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