Synthesis and Array Processor Realization of a 2-D IIR Beam Filter for Wireless Applications

Abstract

A broadband digital beamforming algorithm is proposed for directional filtering of temporally-broadband bandpass space-time plane-waves at radio frequencies (RFs). The enhancement of desired waves, as well as rejection of undesired interfering plane-waves, is simulated. A systolic-and wavefront-array architecture is proposed for the real-time implementation of second-order spatially-bandpass (SBP) 2-D infinite impulse response (IIR) beam filters having potential applications in broadband beamforming of temporally down-converted RF signals. The higher speed of operation and potentially reduced power consumption of the asynchronous architecture of wavefront-array processors (WAPs) in comparison to the conventional synchronous hardware has emerging applications in radio-astronomy, radar, navigation, space science, cognitive radio, and wireless communications. Further, the bit error rate (BER) performance improvement along with the reduced computational complexity of the 2-D IIR SBP frequency-planar digital filter over digital phased array feed (PAF) beamformer is provided. A nominal BER versus signal-to-interference ratio (SIR) gain of 10-16 dB compared to case where beamforming is not applied, and a gain of 2-3 dB at approximately half the number of parallel multipliers to digital PAF, are observed. The results of application-specific integrated circuit (ASIC) synthesis of the digital filter designs are also presented.Index Terms-Array processors, bit error rate (BER), digital phased array feed (PAF), field-programmable gate array (FPGA), multidimensional digital filters, spatial modulation, systolic, wavefront, wireless.

Wide‐band aperture array using a four‐channel manifold‐type planar multiplexer and digital 2‐D IIR filterbank

“…The wide-band signals under consideration are of Gaussian modulated cosine (GMC) type, which obey the 2-D Spatio-Temporal (ST) equation of the plane wave taking the form [68] W pw n 1 Δx; n 2 cΔT ð Þ¼cos…”

“…The polar angle is related to the spatial frequency via ω x = À ω ct tan θ, which in turn is related to the spatial and temporal Laplace variables via s x = σ x + jω x and s ct = σ ct + jω ct , respectively. The proposed 2-D IIR filter has well-defined design equations relating the beam parameters to the Laplace domain transfer function T B (s x , s ct ), and its digital realization having 2-D z-domain transfer function of the form H B (z x , z ct ) [35][36][37][38]. Note that although the antenna patterns are of the form A E (θ, ω ct ), our models can easily incorporate the spatial and temporal behavior into the 2-D IIR SBP filter synthesis steps.…”

Aperture-array directional sensing using 2-D beam digital filters with doppler-radar front-ends

“…In such a scenario where signals are down converted and down sampled with a temporal down sampling factor N s 2-D spectral properties are changed as shown in Fig. 3(b) [14].It could be seen that the spatiotemporal DOA changes to an angle α with a spatial shift, ω x , in the spatial frequency axis.Here, α = tan −1 1…”

“…To construct the passband centering along ω x , the 2-D IIR SBP filter can be designed by spatially modulating, i.e., by multiplying the impulse response of the 2-D IIR frequency planar beam filter with cos(ω x .n 1 ). The discrete domain transfer function of the 2-D IIR SBP filter is given by [14]- [16] H (10) where, b ij are the feedback coefficients, expressed in (8). Fig.…”

“…Thus, replacing FFT-based phased-arrays with 2-D digital beamfilter based steerable apertures reduces the overall complexity of the digital architecture. In this paper, we introduce a methodology that integrates doppler radars with array signal processing based on 2-D infinite impulse response (IIR) spatial bandpass (SBP) beam digital filters [14]- [16], in order to sense the direction of arrival (DOA) and velocity of moving objects.…”