WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Integrated True-Time-Delay based Large-Scale Arrays for Spatially Diverse Applications PI: I: Su Subha hanshu nshu Gupta ta Graduate uate student( dent(s): Erfan Ghaderi, Chase Puglisi, Shrestha Bansal, Qiuyan Xu School of Elec. Engineering and Comp. Sci. Washington State University, Pullman – WA https://labs.wsu.edu/systems-on-chip Oct Oct 18 18, 2019 Integrated True-Time-Delay based Large-Scale Arrays for Spatially 1 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Outline ❖ Motivation ❖ Background ❖ Proposed Discrete-Time Delay-Compensation True-time-delay beamforming for wide modulated BW and large arrays ❑ Spatial interference cancellation with wideband NULL ❑ ❖ Conclusions Integrated True-Time-Delay based Large-Scale Arrays for Spatially 2 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY CH1 Motivation LO/ SPI 3mm Delay ay Communications Compen pens BB BB True-time-Delay Beamforming Key challenges 1.2mm • Network of CubeSat crosslinks • mmWave links among • Swarm-to-ground CubeSats communication • True-time-delay beamforming • Network Scaling (ongoing) • Local ranging up to 100 km • Single/multiple spatial • Low-power edge computing interference cancellation → near-far problem • Closed-loop DoA estimation (ongoing) Integrated True-Time-Delay based Large-Scale Arrays for Spatially 3 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Motivation Spatial Interference Cancellation (SpICa) Sector UE2: Uplink Mode Boundary UE1: Downlink Mode Spatial Int. Canc. w/ Wideband Null UE2 Side-lobe Interference ❖ Dense small cells AP UE1 ❖ Aggressive Main-lobe Side-lobe Spatial-notch frequency re-use TX BS 2 ❖ MIMO 16-CH +6dBm ❖ Co-channel (same frequency) ❖ Inter-sectoral 30m RX interference 500MHz TX BS 1 BW 16-CH Subcarriers +6dBm Integrated True-Time-Delay based Large-Scale Arrays for Spatially 4 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Outline ❖ Motivation ❖ Background ❖ Proposed Discrete-Time Delay-Compensation True-time-delay beamforming for wide modulated BW and large arrays ❑ Spatial interference cancellation with wideband NULL ❑ ❖ Conclusions Integrated True-Time-Delay based Large-Scale Arrays for Spatially 5 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY RF/Analog Phase Shift Beamforming φ f ❖ Valid phase shift A 1 Δφ approximation for narrow- band signal A 2 Δφ θ + ADC ❖ Large antenna arrays suffer from lower normalized 3dB A N Δφ bandwidth (NBW 3dB ) ❖ Bandpass filtering results in signal distortion and performance degradation ❖ Easy to implement Integrated True-Time-Delay based Large-Scale Arrays for Spatially 6 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Leakage in Phase-Shifter based Phased Arrays 0 dB ❖ Cancel ncellat latio ion n of of u undesired esired 1 N=4 N=8 S UD Conversion Gain sig ignal al (S UD UD ) N=16 N=32 ❖ Leakag kage e is is d dependent endent on on: -6 dB 0.5 Bandwidth (BW), -10 dB Center frequency (fc), -14 dB -20 dB Number of elements, (N). 0 0.9 0.95 1 1.05 1.1 Normalized Frequency f c BW SUD Max Conversion nversion Gain Apps N (GHz) Hz) (MH MHz) z) in PS-Ba Based sed SpICa Ca (dB) 802. 2.11 11ay 60 8640 4 -7.1 .1 802. 2.11 11ac ac 5 160 8 -14.0 4.0 5G NR n261 28 800 16 -9.1 .1 5G NR n71 0.6 20 32 -5.1 .1 Integrated True-Time-Delay based Large-Scale Arrays for Spatially 7 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY RF TTD Beamforming φ ❖ No frequency-dependency f in beamforming gain A 1 Δ t ❖ Mismatched components A 2 Δ t at RF θ + ADC ❖ Power hungry RF active delay implementations A N Δ t ❖ Femto-second resolutions at mmWave frequencies ❖ Limited range of delay elements Integrated True-Time-Delay based Large-Scale Arrays for Spatially 8 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Digital TTD Beamforming φ f ❖ Higher ADC dynamic range due to no RF/Analog spatial A 1 ADC 1 processing D A 2 ADC 2 ❖ N Power hungry ADCs θ S P ❖ No frequency-dependency in beamforming gain A N ADC N Integrated True-Time-Delay based Large-Scale Arrays for Spatially 9 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY TTD vs Phase Shift Wideband Beamforming ❖ Phase shift A 1 Δ t 1 • Variable phase shift for different sub-carriers A 2 Δ t 2 θ + ❖ TTD • Constant time delay for the A N Δ t N entire bandwidth Δφ 1M A 1 Δφ 1 Δφ 11 Δφ 2M A 2 Δφ 2 θ Δφ 21 + Δφ N M A N Δφ N Δφ N 1 Integrated True-Time-Delay based Large-Scale Arrays for Spatially 10 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Cancellation requirements w/ TTD-based arrays RF TTD BB TTD Implementation Requirements Requirements ∆tUD BW f c ∆φUD ∆tUD Apps N Overall Resoluti ∆tUD Inter- (GHz) (GHz) Range Resolution on for 40 resolution for element Range N−1 ∙∆tUD for 40 dB dB 40 dB SpICa (ps) SpICa ( o ) (ps) SpICa (ps) (ps) 802.11ay 60 8640 4 8.3 25 1.2 0.395 0.053 802.11ac 5 160 8 100.0 700 0.9 15.17 0.48 5G NR 28 800 16 17.9 268 0.6 2.153 0.060 n261 5G NR 0.6 20 32 833.3 25833 0.4 60.97 2.00 n71 ❖ TTD requirement in baseband is significantly relaxed ❖ Needs a resolution of 2ps (BB TTD) instead of 60fs (RF TTD) at 28GHz. ❖ This makes it attractive to do TTD based SpICa at Baseband Integrated True-Time-Delay based Large-Scale Arrays for Spatially 11 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Delay Compensation Methods Δφ Δ t LO Δ t This Δ t Δφ Work LO LO Δφ Δ t LO RF/IF/LO phase shift IF Time Delay + RF/LO Phase Shift → single frequency → multiple frequencies Integrated True-Time-Delay based Large-Scale Arrays for Spatially 12 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Outline ❖ Motivation ❖ Background ❖ Proposed Discrete-Time Delay-Compensation True-time-delay beamforming for wide modulated BW and large arrays ❑ Spatial interference cancellation with wideband NULL ❑ ❖ Conclusions Integrated True-Time-Delay based Large-Scale Arrays for Spatially 13 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Discrete-time Delay Compensation Technique ( N -1) Δ t ❖ Discrete time implementation Δ t ❖ Introducing delay in signal path IN 1 φ 1 is HARD t ❖ Introduce the delay in the IN 2 CLOCK PATH φ 2 t ❖ Digitally controlled delay compensation ❖ Scalable IN N φ N t Integrated True-Time-Delay based Large-Scale Arrays for Spatially 14 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Discrete-time Beamforming Time alignment – delay compensation ( N -1) Δ t ❖ Discrete time implementation Δ t ❖ NOT in the signal path IN 1 φ 1 ❖ Minimum number of ADCs t ❖ Digitally controlled delay compensation IN 2 φ 2 t ❖ Scalable IN N φ N t Integrated True-Time-Delay based Large-Scale Arrays for Spatially 15 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Proposed Discrete-Time BMFRM Arch. Ghaderi, Gupta TCAS- 1’19 Analog Discrete-time Beamforming N Downconverted RF signals RST ❖ Non-Uniform-Sampling based φ 11 φ 21 φ N 1 σ 1 IN 1 IN 2 IN N C F switched-capacitor array φ 1 φ 2 φ N σ IN 1 IN IN 2 OUT SCA 1 OUT ❖ NOT in the signal path IN N φ 12 φ 22 φ N 2 σ 2 ❖ 1 ADC per beam φ 1 φ 2 φ N σ RST IN 1 IN 2 SCA 2 CLK ❖ Digitally controlled delay OUT OUT IN compensation IN N To ADC φ 1 σ ❖ Scalable IN 1 φ 1M φ 2M φ N M σ M . IN 2 φ 2 . σ . OUT φ 1 φ 2 φ N σ φ N σ ❖ High clocking power IN 1 IN N IN 2 SCA M consumption OUT C S IN N Integrated True-Time-Delay based Large-Scale Arrays for Spatially 16 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Discrete-time Delay Compensating Arch. Ghaderi, Gupta TCAS- 1’19 Clocking M*T S (M-1)*T S ❖ Delay compensation through ( N -1)* Δ t phase interpolation T S Δ t CLK φ 11 ❖ M-levels of interleaving for φ 12 covering larger delay ranges φ 1M φ 21 φ 22 ❖ f s = 1 / T s = 2*f BW φ 2M ∆ tmax = N − 1 ∙∆ t|θ=±60 φ N 1 φ N 2 φ N M 2 ∙ N − 1 ∙ d 3 λ c ∙ 1 = σ 1 f c σ 2 σ M RST Integrated True-Time-Delay based Large-Scale Arrays for Spatially 17 SSCS/MS Seminar Diverse Applications
WASHING INGTO TON STATE TE UNIVERSIT NIVERSITY Switched-Capacitor Adder (SCA) ❖ Parasitic insensitive topology Interference canc. at the OTA virtual ground ❖ Wide bandwidth OTA with 3mW P 11 S 1 RST /200 MHz 3dB BW C S BB 1 C F ❖ Interference cancellation at the 0.86pF S 1 P 11 0.86pF virtual ground node → output OUT swing and linearity requirement easy to meet P 41 S 1 C S BB 4 ❖ Sampling cap designed to meet 0.86pF thermal noise for 10-bit S 1 P 41 M 4 resolution. M 1 ❖ 𝛾 is limited when using multiple elements Integrated True-Time-Delay based Large-Scale Arrays for Spatially 18 SSCS/MS Seminar Diverse Applications
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