Performance comparison and improvement in adaptive arrays based on time‐ and frequency‐domain signal processing

Abstract

SUMMARYIt has been known that an adaptive array antenna is effective for reducing frequency-depending selective fading, which is a problem in wide-band land-mobile communication systems. In an environment in which many delayed signals arrive, it is desirable to improve their SN ratio by using co-phase synthesis. There have been two types of adaptive array antenna for this purpose: an antenna based on time-domain signal processing using a TDL (tapped delay line), and an antenna based on frequency-domain signal processing using a fully reconfigurable filter. The latter has variations in its configuration, and is useful for making practical apparatus. However, its convergence process and behavior in a fading environment have not been clearly understood. In this paper, the performance and the advantages and disadvantages of adaptive array antennas based on various configurations with time-and frequencydomain signal processing are compared. It is found that combinations of some configurations improve their performance. The improvement in performance is also described.

Subband signal processing adaptive array with a data transmission scheme inserting a cyclic prefix

“…1 in terms of the increase in the amount of signal processing [6]. Configuration (ii) has identical performance to TDLAA even for the convergence time [3,6] and does not exhibit the advantages of SBAA in particular. For these reasons, we will examine the configuration in Fig.…”

“…(2) SBAA operates in each subband, can be implemented as parallel processing, and substantially reduces the overall processing load. In other words, SBAA is extremely superior from the perspective of the computational load [6,7].…”

“…If the number of taps is the same, the TDLAA has superior performance. (However, the degree of degradation depends on each assumed case [6].) (2) SBAA operates in each subband, can be implemented as parallel processing, and substantially reduces the overall processing load.…”

“…The advantages of the SBAA are its ability to perform parallel signal processing in each divided subband and the substantial reduction in the overall computational load. However, the price is not preventing a drop in performance, for example, the ability to incorporate the delayed waves, and solving this problem is thought to be critical [6,7]. Therefore, in this paper, we propose introducing a scheme that inserts a guard interval (cyclic prefix), which is adopted in the Orthogonal Frequency Division Multiplexing (OFDM) [8], into normal data transmission to improve the multipath signal combining functions.…”

Performance Evaluation of DFT Beamformers for Broadband Antenna Array Processing

“…Since the weight vector in each frequency bin of the DFT beamformer is usually produced individually, the conclusion of [29] may not be appropriate for all kinds of DFT beamformers. In spite of the existing work in [22][23][24][25][26][27][28][29][30], the output SINR of the DFT beamformer is never welldefined and studied in detail. Moreover, the performance of the DFT beamformer with correlation matrices estimated by finite data samples are seldom evaluated or discussed in the literature.…”