| In recent years, there has been renewed interest in optimized signature waveform code sets for the growing number of code-division multiplexing applications such as plain or multiple-input
multiple-output (MIMO) code-division multiple-access (CDMA), multiuser orthogonal-frequency-division-multiplexing (OFDM),
multiuser ultra-wideband (UWB) systems, etc. When data symbols modulate a signature waveform/pattern to move across a channel in the presence of disturbance, the signature/spreading-code that
maximizes the signal-to-interference-plus-noise ratio (SINR) at the output of the maximum-SINR filter is the smallest-eigenvalue eigenvector of the disturbance autocovariance matrix. In digital
communication systems, however, the signature alphabet is finite and digital signature optimization is NP-hard. In this paper, we will
present a formal search procedure of cost linear in the signature code length that returns the maximum-SINR binary signature near lines of least SINR decrease in the Euclidean vector space. The
quality of the proposed adaptive binary design will be compared against the theoretical upper bound of the complex/real eigenvector maximizer and other known static and adaptive binary signature designs. |