Optimal Unimodular Sequences Design Method for Active Sensing Systems

Abstract

In active sensing systems, unimodular sequences with low autocorrelation sidelobes are widely adopted as modulation sequences to improve the distance resolution and antijamming performance. In this paper, in order to meet the requirements of specific practical engineering applications such as suppressing certain correlation coefficients and finite phase, we propose a new algorithm to design both continuous phase and finite phase unimodular sequences with a low periodic weighted integrated sidelobe level (WISL). With the help of the transformation matrix, such an algorithm decomposes the N-dimensional optimization problem into N one-dimensional optimization problems and then uses the iterative method to search the optimal solutions of the N one-dimensional optimization problems directly. Numerical experiments demonstrate the effectiveness and the convergence property of the proposed algorithm.

Single Carrier-Frequency Division Multiple Access Radar: Waveform Design and Analysis

“…In Fig. 7, the autocorrelation properties of 100-element long waveform, PWCIA (Periodic Correlation Weighted Cyclic Iteration Algorithm) generated by a sequence of 8 phases proposed by Li et al in [27] are compared with our proposed 128-element long, 8-phase SC-FDMA waveform initiated by 64-element Frank code; each with a chipwidth of 1µs. The plots show that the autocorrelation of our waveform is better than that of the PWCIA waveform except at the recurring grating lobe points.…”

“…Autocorrelation of PWCIA waveform with 8-phases and 100 subsequences [27] verses the proposed 8-phase SC-FDMA waveform (initiated with 8-phase Frank code) when grating lobes are resolved. Fig.…”

“…The results given in Table 1 show that each of the proposed SC-FDMA signals, generated by using different initial sequences, offers better PAPR values as compared to their respective OFDM signals. Table. 2 presents the values of PAPR of the proposed SC-FDMA waveforms and their comparison with unimodular sequences proposed in [25] and [27], and with nonlinear piecewise frequency modulated signals proposed in [28]. Although the autocorrelation properties of the waveform in [28] are good, however, its PAPR is much higher than the proposed waveform.…”

“…These sequences have unit PAPR ratio as well as low auto-correlation sidelobes. In their work in [27], Ze Li et al proposed Periodic correlation Weighted Cyclic Iteration Algorithm (PWCIA) for finite phase unimodular sequences to achieve lower integrated sidelobe levels as compared to [25] and [26]. These sequences also possess unit PAPR ratio because of their unimodular structure.…”

“…• The performance of the proposed radar waveform is compared with those of the notable existing multicarrier radar waveforms [25], [27], [32] and [28].…”