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This work addresses code division multiple access (CDMA) implementation of automotive multiple-input multiple-output (MIMO) radars. The tansec frequency modulation (TSFM) is proposed as a single intracoding scheme for CDMA-MIMO radars. The properties of the TSFM coding family are analyzed and two novel codeword selection algorithms are proposed. The TSFM is compared to a variety of coding families by evaluating their autocorrelation and cross-correlation properties. The considered coding families are based on phase coding: Hadamard, Gold, optimal peak to sidelobe; and frequency coding: piecewise linear frequency modulated. Properties of the coding families are analyzed with a variety of novel criteria, which are especially useful for CDMA-MIMO radars. The performance of the CDMA-MIMO radar with different coding families is evaluated via simulations of practical multitarget automotive scenarios. It is shown that the frequency-based TSFM coding family outperforms the other considered coding families in terms of their cross-correlation properties. [ABSTRACT FROM AUTHOR]

This paper employs a special property of the Hadamard matrix to develop a novel compressive sensing (CS) based framework that eliminates the complex reconstruction step required by standard CS methods. In particular, time-difference-of-arrivals (TDOAs) of a signal at different receivers involved in positioning of unknown sources are directly estimated from CS measurements, without any attempt to reconstruct the full signals. Although this approach is designed for TDOA estimation, it is also capable of accommodating other CS applications. [ABSTRACT FROM AUTHOR]

A set of unimodular code vectors is complementary if the sum, over all code vectors, of the aperiodic autocorrelation sidelobes is zero. Complementary code sets are constructed using a matrix formulation in which code vectors form the columns of a matrix, called a complementary code matrix (CCM). Known construction methods for Hadamard matrices are examined and found to apply to the larger class of CCMs, in some cases with the addition or strengthening of conditions. These constructions include the Sylvester, Williamson, and Kronecker product constructions. Additional approaches for creating new CCMs from available CCMs are introduced and discussed. A future paper will focus on existence results for binary CCMs and on parametric families of unimodular CCMs. Special cases of CCMs are binary CCMs and Hadamard matrices. [ABSTRACT FROM AUTHOR]