Yoshihiro Tanada

On perfect arrays

In this paper construction of perfect arrays is investigated by using the Fourier transform, in order to discuss generally. Furthermore a new orthogonal transform using a perfect array is discussed, which will be applied to some applications, such as communications and signal processing.

Construction of complementary arrays

This paper discusses complementary arrays, which are multi-dimensional complementary sequences, and make clear these construction. Furtheremore generating functions for complementary arrays, whose length is a power of two, are formulated. These can be expressed by logic functions, and can show that there exist a huge number of complementary arrays.

Improved Two-Valued and Three-Valued Integrand Codes for Real-Valued Self-Orthogonal Finite-Length Sequence

A real-valued self-orthogonal finite-length sequence has a zero-sidelobe autocorrelation function except at both shift ends. Two-valued and three-valued integrand codes for the sequence are effective for a practical application. This paper presents the improved two-valued and three-valued integrand codes. The allocation of code values in every time chip is optimized so that the Fourier spectrum of the equivalent multivalued pulse-width-modulation (PWM) code waveform at every chip may resemble each other. The codes are smoothed through Gaussian low pass filter. The sidelobes of the autocorrelation outputs are improved to be about 10-dB lower than those for the not-optimized codes.

Digital matched filter of reduced operation elements for M-ary/DS-SS system using real-valued shift-orthogonal finite-length sequences

A real-valued shift-orthogonal finite-length sequence has a sharp autocorrelation function with zero sidelobes except at shift ends, and can be synthesized by element sequences. We propose the structure of a digital matched filter for M-ary direct sequence spread spectrum (M-ary/DS-SS) system using the sequences and the reduction of operation elements of the digital matched filter. It is shown that this digital matched filter for M-ary/DS-SS systems can be constructed by multipliers and adders proportional to sequence length.

Finite-Length Sequence Pairs With Impulsive Convolution and Their Application to Asymmetric-Key Spread Spectrum Communication System

In an ad-hoc communication system, the information security between a sender and a receiver must be assured strictly. In this paper, finite-length sequence pairs are introduced for the application to an asymmetric-key spread spectrum communication system. The convolution of the sequence pair gives an impulse except the small values at the first and last ends. The real-valued sequence pairs of length M have the family number of about 2M/radic2piM and are applied to a signature spread spectrum communication system.