Browsing by Author "Madanayake, A"

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item: Conference-Full-text
A 480mhz roach-2 fpga realization of 2-phase 2-d iir beam filters for digital rf apertures
(IEEE, 2016-04) Seneviratne, V; Madanayake, A; Bruton, LT; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
RF antenna array beamforming based on electronically steerable wideband phased-array apertures find applications in communications, radar, imaging and microwave sensing. High-bandwidth requirements for wideband RF applications necessitate hundreds of MHz or GHz frame-rates for the digital array processor. A systolic architecture is proposed for the realtime implementation of the 2-D IIR beam filter. This implementation employs a differential-form polyphase 2-D IIR frequencyplanar beam filter, and a corresponding circuit architecture in order to achieve the real-time computation of the input-output 2-D difference equation that defines the RF beam filter. The feasibility of real-time implementation for dense aperture arrays operating in the 0-240 MHz band using a beam filter is explored. The proposed 2-phase sampling scheme per antenna is based on a 2-D IIR polyphase structure. A digital hardware prototype is designed, implemented and tested using a ROACH-2 fitted with a Xilinx Virtex-6 Sx475t FPGA chip and a 32-channel timeinterleaved RF data converter, which support 16 antennas using 2-phase time-interleaved sampling at an FPGA clock rate of 240 MHz.
item: Conference-Full-text
Aperture-Array Directional Sensing using 2-D Beam Digital Filters with Doppler-Radar Front-Ends
(2015-08-03) Randeny, T; Madanayake, A; Sengupta, A; Li, Y; Li, C
A directional sensing algorithm is proposed employing doppler radar and low-complexity 2-D IIR spatially bandpass filters. The speed of the scatterer is determined by the frequency shift of the received signal following down-conversion. The downconversion is done by mixing it with the instantaneous transmitted signal. The direction of the scatterer is determined by the means of 2-D plane-wave spectral characteristics, using 2-D IIR beam filters. The proposed architecture was simulated for three scatterers at 10,o 30,o 60o from array broadside, traveling at speeds of 31 ms,−1 18 ms−1 and 27 ms−1, respectively. A doppler radar module was used to transmit and receive reflected signals, that has a carrier frequency of 2.4 GHz. Simulations show both direction and doppler information being enhanced.
item: Conference-Abstract
Aperture-array directional Sensing using 2-D Beam Digital Filters with Doppler-Radar Front-Ends
Randeny, T; Madanayake, A; Sengupta, A; Li, Y; Li, C
A directional sensing algorithm is proposed employing doppler radar and low-complexity 2-D IIR spatially bandpass filters. The speed of the scatterer is determined by the frequency shift of the received signal following down-conversion. The downconversion is done by mixing it with the instantaneous transmitted signal. The direction of the scatterer is determined by the means of 2-D plane-wave spectral characteristics, using 2-D IIR beam filters. The proposed architecture was simulated for three scatterers at 10,o 30,o 60o from array broadside, traveling at speeds of 31 ms,−1 18 ms−1 and 27 ms−1, respectively. A doppler radar module was used to transmit and receive reflected signals, that has a carrier frequency of 2.4 GHz. Simulations show both direction and doppler information being enhanced.
item: Conference-Full-text
Delta-sigma noise shaping in 2d spacetime for uniform linear aperture array receivers
(IEEE, 2016-04) Handagala, S; Madanayake, A; Belostotski, L; Bruton, LT; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
A multi-dimensional noise-shaping method based on delta-sigma modulation has been proposed. This method extends delta-sigma modulation into the two-dimensional (2-D) case (space, time). The proposed noise-shaping method employs lossless discrete integrators for realization in microwave and mmwave array processing systems. The paper shows that 2-D noiseshaping reduces the spectral overlap of a desired array signal with that of noise. By reducing the overlap of the ROSs, 2- D filtering can be used to improve the overall noise figure of the array receiver. A noise figure improvement of 2.6 dB could be simulated for a 4-times spatially over-sampled array with 65 simulated elements for an input signal to noise ratio of 10 dB and LNA noise figure of 5 dB. Simulation results based on wideband signals on 33, 65, 129 and 257 element antenna arrays with 2, 4 and 8 times oversampling show the potential capability of the proposed system in improving overall noise figure. Although mathematical modeling shows potential improvements in receiver noise figure, RF integrated circuit realizations are challenging and have not been attempted yet.
item: Conference-Abstract
Design methodology of an analog 9-beam squint-free wideband IF multi-beamformer for mmW applications
(2017) Ariyarathna, V; Udayanga, N; Madanayake, A; Perera, SM; Belostotski, L; Cintra, RJ
An intermediate frequency (IF) squinting-free multi-beamforming method is proposed for multi-antenna systems. The proposed approach uses a low-complexity factorization of a true-time-delay (TTD) multi-beam matrix, which is proposed to be realized using an analog integrated circuits approach. A TTD realization of multi-beams at intermediate frequency is achieved following amplification and synchronous down-conversion via the proposed Delay Vandermonde Matrix (DVM) in which matrix elements correspond to the compound phase compensation required for squint-free steering of each radio-frequency beam. True-time-delays are proposed to be efficiently realized on-chip by applying a sparse factorization to the DVM, which leads to a low circuit complexity implementation requiring a significantly lower number of TTD blocks and phase compensations compared to an equivalent direct implementation for a given N number of beams. The proposed method, for 9- beams, leads to a 60% reduction of analog integrated circuit based TTD blocks and phase compensators. The TTD blocks can be realized on chip using active-RC based integrated analog all-pass filters. The proposed multi-beam algorithm and circuit structure is simulated within the frequency range 55-65 GHz to demonstrate squinting-free wide-band multi-beams at millimeter wave carrier frequencies for emerging 5G applications.
item: Conference-Abstract
Energy-efficient ULF/VLF transmitters based on mechanically-rotating dipoles
(2017) Madanayake, A; Choi, S; Tarek, M; Dharmasena, S; Mandal, S; Glickstein, J; Sehirlioglu, A
We describe the design of miniaturized powerefficient ULF/VLF (0.3-30kHz) transmitters for underground and undersea wireless communications based on the mechanical rotation of permanently-polarized dipoles. The concept is validated using both theoretical analysis and simulations. Moreover, an integrated design and control strategy is proposed to overcome the resulting electromagnetic and mechanical design challenges
item: Conference-Full-text
Implementation and testing of a switching circulator for twin-pair star radio architectures
(IEEE, 2020-07) De Silva, U; Malavipathirana, H; Pulipati, S; Bhardwaj, S; Mandal, S; Madanayake, A; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Realization of simultaneous transmit and receive (STAR) wireless systems is desirable for spectral efficiency but challenging due to difficulties in isolating the receiver from the transmitter. A twin-pair STAR architecture based on two identical sequentially-switched delay line (SSDL) circulators is proposed for STAR. The twin-pair approach uses one circulator as a real-time model of the other circulator which is used for communication, thereby allowing cancellation of transmit signals from the receiver before reaching the first low-noise amplifier (LNA). A wideband SSDL circulator is designed and characterized to study its suitability in the proposed STAR architecture. The circulator has spur-free (over-multiplexed) operation up to 48 MHz and under-multiplexed operation up to 1.0 GHz with an insertion loss < 10 dB and isolation > 25 dB.
item: Conference-Full-text
A low-complexity 2-d fir parallelogram filter for broadband beamforming with sparse linear arrays
(IEEE, 2023-12-09) Pakiyarajah, D; Edussooriya, CUS; Wijenayake, C; Madanayake, A; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Broadband beamformers designed as twodimensional (2-D) spatially-interpolated finite-extent impulse responses (FIR) filters, using a cascade structure, cannot employ sparse linear arrays despite significantly reducing the computational complexity. This happens due to the fact that the 2-D masking filter requires spatial samples equal to the spatial order at the input. Therefore, the output of the 2-D spatially-interpolated prototype filter should be computed for more than one spatial index. In order to address this limitation, we propose a 2-D spatially-interpolated FIR filter using a parallel structure. With the proposed structure, both 2-D spatially-interpolated prototype filter and the 2-D masking filter need to compute the output only for one spatial index, therefore allowing to employ sparse linear arrays. In order to support broadband beamforming, we design the 2-D FIR filter to have a parallelogram passband. Furthermore, we design the 2-D FIR filter to have linear phase response and to be optimal in the minimax sense. The simulation results confirm that the proposed 2-D FIR filter provides a considerable reduction in the number of antennas, compared to previously proposed 2-D FIR filters, with a slight degradation in the fidelity of enhanced broadband signals, which are distorted by strong radio frequency interference and noise signals.
item: Conference-Full-text
Minimax design of m-d complex-coefficient fir filters with nearly-constant low group delays
(IEEE, 2023-12-09) Pakiyarajah, D; Edussooriya, CUS; Wijenayake, C; Madanayake, A; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
The optimal designs of multi-dimensional (M-D) complex-coefficient finite-extent impulse response (FIR) filters with low group delays predominantly consider only the minimization of the frequency response error. This leads to substantial deviation of the group delay from the desired constant group delay of such a filter, especially near the passband edges. In this paper, we propose a minimax design method for M-D complexcoefficient FIR filters with reduced group delay error. We incorporate constraints on phase response error while minimizing the frequency response error. We formulate the proposed minimax design method as a second-order cone programming problem. Design examples confirm that the proposed minimax design method significantly reduces the group delay error compared to previously proposed methods.
item: Conference-Full-text
Multi depth-velocity filters for enhancing multiple moving objects in 5-d light field videos
(IEEE, 2020-07) Liyanage, N; Jayaweera, SS; Edussooriya, CUS; Wijenayake, C; Madanayake, A; Agathoklis, P; Bruton, L; Ambikairajah, E; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
A moving object in a five-dimensional (5-D) light field video (LFV) can be selectively enhanced using the depth and the velocity of the object. In this paper, a 5-D depth-velocity (DV) filter is proposed to enhance multiple moving objects at different depths and with different velocities in an LFV. The 5-D DV filter is designed as a cascade of an infinite-extent impulse response multi-depth filter and a finite-extent impulse response multi-velocity filter. Experimental results obtained with numerically generated and real LFVs indicate that more than 15 dB improvement in signal-to-interference ratio can be achieved with the proposed 5-D multi DV filter compared to previously proposed multi depth-only filters.
item: Conference-Abstract
Multi-beam 8 × 8 RF aperture digital beamformers using mMultiplierless 2-D FFT appro ximations
Kulasekera, S; Madanayake, A; Wijenayake, C; Bayer, FM; Suarez, D; Cintra, RJ
The two-dimensional (2-D) discrete Fourier transform (DFT) is widely used in digital signal processing (DSP) and computing applications. Fast Fourier transforms (FFTs) are widely used as low-complexity algorithms for the computation of the DFT as it reduces the required computation operations from O(N2) to O(N log2 N). The multiplicative complexity is used as a benchmark in comparing different algorithms as it affects the circuit complexity, chip area and power. This paper introduces a new class of multiplierless hardware algorithm consisting only of arithmetic adder circuits that closely approximates the 2-D version of the 8-point DFT. The paper discusses the theory behind the proposed new algorithm, with the DFT presented in the form of an 8 × 8 matrix. Furthermore it provide a multi-beam RF aperture application example where the 2-D DFT approximation has been used to closely obtain the antenna array patterns.
item: Conference-Full-text
Multi-Beam 8 × 8 RF Aperture Digital Beamformers Using Multiplierless 2-D FFT Approximations
(2015-08-03) Kulasekera, S; Madanayake, A; Wijenayake, C; Bayer, FM; Cintra, RJ
The two-dimensional (2-D) discrete Fourier transform (DFT) is widely used in digital signal processing (DSP) and computing applications. Fast Fourier transforms (FFTs) are widely used as low-complexity algorithms for the computation of the DFT as it reduces the required computation operations from O(N2) to O(N log2 N). The multiplicative complexity is used as a benchmark in comparing different algorithms as it affects the circuit complexity, chip area and power. This paper introduces a new class of multiplierless hardware algorithm consisting only of arithmetic adder circuits that closely approximates the 2-D version of the 8-point DFT. The paper discusses the theory behind the proposed new algorithm, with the DFT presented in the form of an 8 × 8 matrix. Furthermore it provide a multi-beam RF aperture application example where the 2-D DFT approximation has been used to closely obtain the antenna array patterns.
item: Article-Full-text
Multi-depth filtering and occlusion suppression in 4-D light fields: Algorithms and architectures
(Elsevier, 2020) Liyanage, N; Wijenayake, C; Edussooriya, C; Madanayake, A; Agathoklis, P; Bruton, LT; Ambikairajah, E
Low-complexity signal processing algorithms and reconfigurable digital hardware architectures are proposed for multi-depth filtering and occlusion suppression in 4-D light fields (LFs). The proposed multi-depth-pass (MDP) and multi-depth-reject (MDR) 4-D filters allow simultaneous enhancement of planar objects at multiple desired depths and attenuation of planar objects at multiple undesired depths, thereby achieving electronically tunable multi-depth focusing. Partial-separability and recursive nature of the proposed MDP and MDR transfer functions ensure ultra-low hardware complexity suitable for real-time processing of large volume of input samples encountered in 4-D LFs. Filter synthesis details and examples with synthetic and real LFs of size 15  ×  15 × 434  ×  625 are presented. A generic framework encapsulating a multitude of possible digital hardware realizations is described, employing J-unfolding and look-ahead pipelining albeit with modifications as applicable to the underlying multi-dimensional signal flow graphs to obtain increased real-time throughput. Proof-of-concept digital designs are provided for the 2-passband case of a MDP filter verifying a real-time throughput of  ≈ 490 LFs of size 9  ×  9 × 434  ×  625 per second for filters operating at 135 MHz on a Xilinx Virtex-7 FPGA device.
item: Conference-Abstract
An Overview of multi-dimensional RF signal processing for array receivers
Madanayake, A; Wijenayake, C; Belostotski, L; Bruton, LT
In this review paper, recent advancements in multidimensional (MD) spatio-temporal signal processing for highlydirectional radio frequency (RF) antenna array based receivers are discussed. MD network-resonant beamforming filters having infinite impulse response (IIR) and recursive spatio-temporal signal flow graphs are reviewed. The concept of MD networkresonant pre-filtering is described as a modification to existing phased/timed array beamforming back-ends to achieve improved side-lobe performance in the array pattern, leading to better interference rejection capabilities. Both digital and analog signal processing models are described in terms of their system transfer functions and signal flow graphs. Example MD frequency response and RF antenna array pattern simulations are presented.
item: Conference-Full-text
An Overview of Multi-Dimensional RF Signal Processing for Array Receivers
(2015-08-03) Madanayake, A; Wijenayake, C; Belostotski, L; Bruton, Len T
In this review paper, recent advancements in multidimensional (MD) spatio-temporal signal processing for highlydirectional radio frequency (RF) antenna array based receivers are discussed. MD network-resonant beamforming filters having infinite impulse response (IIR) and recursive spatio-temporal signal flow graphs are reviewed. The concept of MD networkresonant pre-filtering is described as a modification to existing phased/timed array beamforming back-ends to achieve improved side-lobe performance in the array pattern, leading to better interference rejection capabilities. Both digital and analog signal processing models are described in terms of their system transfer functions and signal flow graphs. Example MD frequency response and RF antenna array pattern simulations are presented.
item: Conference-Full-text
Real-time 2-d fir trapezoidal digital filters for 2.4 ghz aperture receiver applications
(IEEE, 2018-05) Ariyarathna, V; Coutinho, VA; Pulipati, S; Madanayake, A; Wijesekara, RT; Edussooriya, CUS; Bruton, LT; Gunaratne, TK; Cintra, RJ; Chathuranga, D
This paper presents the implementation of a twodimensional (2-D) finite-impulse-response (FIR) trapezoidal filter based beamforming array receiver. A 2.4 GHz 16-element receivemode IQ array is designed and used for physically measuring the beam patterns corresponding to 2-D FIR trapezoidal filters. The 16-element beamformer is implemented using the reconfigurable open architecture computing hardware version-2 (ROACH-2) field programmable gate array (FPGA) platform to perform analog to digital conversion and digital signal processing. The 2-D FIR trapezoidal filter is designed as a 16-spatial input 32- tap filter and is implemented targeting the ROACH-2’s Xilinx Virtex 6 (sx475t) FPGA chip as a filter-and-sum architecture. The receiver array is precisely rotated (keeping the transmitter fixed) to digitally measure the received energy by integrating the instantaneous power of the output of the 2-D FIR trapezoidal filter for each angle of reception. The main lobe of the measured beam pattern is well aligned with the simulated beam pattern, and the highest measured side-lobe level is −17.8 dB.
item: Conference-Abstract
Real-Time FPGA-Based multi-beam directional sensing of 2.4 GHz ISM RF sources
PulipatI, S; Ariyarathna, V; Edussooriya, CUS; Wijenayake, C; Wang, X; Madanayake, A
A real-time directional sensing system is proposed for 2:4 GHz ISM band by exploiting the concept of spatiotemporal spectral white spaces. The proposed system consists of a 16-element patch antenna array, an FFT-based multi-beam beamformer and an energy detector. Our system operates at the baseband with quadrature sampling. Furthermore, digital architectures for two energy detectors that employ integrate-anddump circuits are presented. With the multi-beam beamformer, the first energy detector can be employed to directional sensing and the second can be employed for both directional and spectral sensing of radio frequency sources. The multi-beam beamformer having 16 beams and the energy detectors are implemented on a ROACH-2 based FPGA system with a 160 MHz clock. With an 8-point temporal FFT, the second energy detector provides approximately 20 MHz bandwidth per temporal FFTbin. Preliminary experimental measurements obtained with Wi- Fi devices and the first energy detector verify the proof-of-concept directional sensing of the proposed system.
item: Article-Full-text
Real-time light field signal processing using 4D/5D linear digital filter FPGA circuits
(IEEE, 2021) Edussooriya, CUS; Wijenayake, C; Madanayake, A; Liyanage, N; Premaratne, S; Vorhies, JT; Dansereau, DG; Agathoklis, P; Bruton, LT
Light fields (LFs) and light field videos (LFVs) capture both angular and spatial variation of light rays emanating from scenes. This richness of information leads to novel applications such as post-capture refocusing, depth estimation and depth-velocity filtering which are not possible with images and videos. These capabilities come, however, with a significant increase in data to be processed. In order to fully exploit opportunities provided by LFs and LFVs, low-complexity signal processing algorithms that process LF and LFV data in realtime are required. In this paper, we survey such state-of-theart algorithms, in particular for depth filtering, refocusing and denoising of LFs and depth-velcoty filtering for LFVs, and future directions for these real-time LF an LFV processing algorithms.
item: Conference-Abstract
Scanned–array audio beamforming using 2nd− and 3rd–order 2D IIR beam filters on FPGA
(2016-08-29) Ganganath, N; Attanayake, G; Bandara, TY; Ilangakoon, P; Rodrigo, BKRP; Madanayake, A; Bruton, LT
Real-time scanned-array direct-form-I hardware implementations of two-dimensional (2D) infinite impulse response (IIR) frequency-planar beam plane-wave (PW) filters have potentially wide applications in the directional enhancement of spatio-temporal broadband PWs based on their directions of arrival (DOAs). The proposed prototypes consist of a microphone sensor array, low-noise-amplifiers (LNAs), multiplexers (MUXs), a programmable gain amplifier (PGA), an analog to digital converter (ADC), a digital to analog converter (DAC), and a field programmable gate array (FPGA) circuit based 2D IIR spatiotemporal beam filter implemented on a single Xilinx Virtex2P xc2vp30-7ff896 FPGA chip. Starting from published 1st-order designs, novel FPGA architectures for highly-selective 2nd- and 3rd-order beam PW filters are proposed, simulated, implemented on FPGA, and verified on-chip.
item: Conference-Full-text
Xilinx rf-soc-based digital multi-beam array processors for 28/60 ghz wireless testbeds
(IEEE, 2020-07) Pulipati, S; Ariyarathna, V; Dhananjay, A; Eltayeb, ME; Mezzavilla, M; Jornet, JM; Mandal, S; Bhardwaj, S; Madanayake, A; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Emerging wireless applications such as 5G cellular, large intelligent surfaces (LIS), and holographic massive MIMO require antenna array processing at mm-wave frequencies with large numbers of independent digital transceivers. This paper summarizes the authors’ recent progress on the design and testing of 28 GHz and 60 GHz fully-digital array processing platforms based on wideband reconfigurable FPGA-based software-defined radios (SDRs). The digital baseband and microwave interfacing aspects of the SDRs are implemented on single-chip RF systemon- chip (RF-SoC) processors from Xilinx. Two versions of the RF-SoC technology (ZCU-111 and ZCU-1275) were used to implement fully-digital real-time array processors at 28 GHz (realizing 4 parallel beams with 0.8 GHz bandwidth per beam) and 60 GHz (realizing 4 parallel beams with 1.8 GHz bandwidth per beam). Dielectric lenslet arrays fed by a digital phased-array feed (PAF) located on the focal plane are proposed for further increasing antenna array gain.