About

Najme Ebrahimi is an Assistant Professor in the Electrical and Computer Engineering department at Northeastern University College of Engineering, having joined the faculty in August 2023. Her research focuses on broadband, energy-efficient, reconfigurable, and high data rate RF, mm-wave, and THz integrated circuits and systems, as well as security, connectivity, and localization of IoTs. She leads Ebrahimi’s Labs, which is pioneering advancements in wireless communication and IoT technologies, with a primary emphasis on developing high-data-rate communications and sensing solutions for 6G and beyond. Her work also involves creating secure, precise localization and communication protocols for dense IoT networks, addressing critical challenges such as scalable beamforming, interference cancellation, and collision recovery through innovative approaches from circuit design to protocol development. Dr. Ebrahimi holds a PhD in Electrical Engineering from the University of California-San Diego, earned in 2017, and has received notable honors including the DARPA Director’s Fellowship in 2023 and the DARPA Young Faculty Award in 2021.

Research topics

• Computer Science
• Engineering
• Telecommunications
• Electronic engineering
• Electrical engineering
• Computer Security
• Physics
• Computer network
• Optics

Selected publications

• A Novel Dual-band and Bidirectional Nonlinear RFID Transponder Circuitry

  2022 IEEE/MTT-S International Microwave Symposium - IMS 2022 · 2022 · 12 citations

  Senior authorCorresponding
  • Computer Science
  • Electrical engineering
  • Computer Science

  This work presents the first bidirectional circuitry for Internet of Things (IoT) transponder that simultaneously generates harmonics and subharmonics, dual band frequencies. A multi-band or wideband localization system is essential for future wireless sensor network to mitigate the influence of multipath signals and interferences for indoor environment. The proposed frequency generation circuitry is based on novel nonlinear ring resonator (NRR) which is a standing wave resonator generating two sustainable resonant frequencies based on the periodic nonlinear unit-cell in a ring configuration. The NRR circuit consumes zero DC power and has 10 dB conversion loss at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f_{in}$</tex> of 4.8 GHz with 120 MHz bandwidth in subharmonic, divider mode, and 16 dB loss in harmonic at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f_{in}$</tex> of 2.4 GHz, doubler mode.

  DOI

• Physical Layer Secret Key Generation Using Joint Interference and Phase Shift Keying Modulation

  IEEE Transactions on Microwave Theory and Techniques · 2021 · 26 citations

  1st authorCorresponding
  • Computer Science
  • Computer Science
  • Computer network

  In existing physical layer security (PLS) and key generation protocols, major assumptions, including channel reciprocity, localization, and synchronization between the legitimate parties, are often considered. However, these assumptions are arguable in practice leading to major barriers in building systems based on PLS protocols. To overcome these barriers, we proposed, designed, and implemented a novel embedded architecture for distributed Internet-of-Things (IoT) networks that utilize a master-slave full-duplex communication to exchange a random secret key. In the proposed architecture, an IoT node generates a phase-modulated random key/data and transmits it to a master node in the presence of an eavesdropper, referred to as Eve. The master node, simultaneously, broadcasts a high-power signal using an omnidirectional antenna, which is received as a jammer signal or interference by Eve. This results in a high bit error rate (BER) making the data undetectable by Eve. The two legitimate nodes communicate in a full-duplex fashion and, consequently, subtract their transmitted signals from the received signal (self-interference cancellation). Our proposed protocol does not require any knowledge of the node locations. In particular, we show, using theoretical and measurement results, that our proposed approach provides significantly better security measures, in terms of the BER at Eve's location, compared to a conventional method based on directional beamforming antennas. Also, it is proved that in our novel system, the possible eavesdropping region, BER <; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , is always smaller than the reliable communication region, BER <; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> .

  DOI

• A 71-76/81-86 GHz, E-band,16-Element Phased-Array Transceiver Module With Image Selection Architecture for Low EVM Variation

  2020 · 14 citations

  1st authorCorresponding
  • Physics
  • Optics
  • Electronic engineering

  A 4-element, compact bidirectional phased-array transceiver die covers the full E-band (71-76 & 81-86GHz) and is tiled on PCB to demonstrate a 16-element antenna array. A Weaver image-selection architecture reduces the LORF tuning range to 3 GHz (4% FBW) while covering the 10 GHz band (20% FBW). The bidirectional architecture is proposed in a scalable array with a shared image-selection IF mixer. The 2x2 transceiver die is implemented in a 90-nm SiGe BiCMOS process and assembled on PCB with a compact differential aperture-coupled feed network for LO and IF distribution with low amplitude and phase mismatch between multiple chips input/output. The proposed 16-element array steers over a ±30° range and demonstrates 30-dBm EIRP and 32-dB RX conversion gain with 1.5 GHz modulation bandwidth for 64 QAM (9 Gb/s) and 2 GHz for 16 QAM with ± 2 dB EVM variation over the entire E-band under same calibration states. The power consumption is 250 mW for TX mode and 160 mW for RX mode at each element.

  DOI

Frequent coauthors

• Hessam Mahdavifar

  6 shared

• Shah Zaib Aslam

  University of Florida

  4 shared

• Hun-Seok Kim

  3 shared

• Haoling Li

  Northeastern University

  3 shared

• David Blaauw

  University of Michigan–Ann Arbor

  3 shared

• Shilpi Sharma

  2 shared

• L. Kurinjimalar

  2 shared

• Payman Pahlavan

  University of Florida

  2 shared

Awards & honors

• DARPA Director’s Fellowship (2023)
• DARPA Young Faculty Award (2021)

Similar researchers at Northeastern University

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