Overview

Localization (2022-Present)

• UAV-aided indoor localization for emergency applications
  • Drones as first responders or locating first responders
  • Cramér–Rao lower bound (CRLB) based analyses by considering various system parameters.
  • Algorithms for enhanced accuracy with low-complexity: Two-Stage Weighted Projection (TS-WPM), Reformulated IPPM.
  Resulted Publications: Low-Complexity TS-WPM, Analytical Framework + Reformulated IPPM, CRLB Sensitivity Analysis
  Collaborators: Prof. Harpreet S. Dhillon and Prof. R. Michael Buehrer
• NTN-based 6G localization
  • Feasibility of developing a positioning infrastructure complementary to or a potential replacement for GNSS.
  • Prospective study items for NTN-based accurate positioning in 6G: Multi-LEO positioning, GNSS + LEO positioning.
  • Design insights for LEO-based NTN positioning: LEO constellation, navigation signaling, initial acquisition, precise positioning.
  Resulted Publications: LEO Positioning Design Insights, Study Items for NTN-based 6G Localization
  Collaborators: Prof. Harpreet S. Dhillon, Prof. R. Michael Buehrer, and Dr. Chiranjib Saha
• 3GPP-compliant simulation frameworks to assess the positioning performance.

ORAN ULPI Architectures (Summer 2023)

Analysis of Performance Differences in ORAN ULPI Proposed Architectures

• Developed an uplink multi-user MIMO link level simulator (LLS) leveraging 5G toolbox in MATLAB.
• Investigated proposed uplink performance improvement (ULPI) architectures compliant to ORAN 7-2x.
• LLS Features: Channel estimation, equalization with modular granularity, MU-MIMO, hybrid ARQ, antenna array, CDL channel model, and evaluation metrics (sum throughput and post-processing SINR).

Collaborators: Dr. Serdar Ozen, Dr. Rapeepat Ratasuk, and Mark Cudak

RAN Intelligent Controller (RIC) (2021-2022)

Developed a system framework to enable real-time RIC functionality.

• Developed scheduling algorithms and enabled the wireless system (srsRAN) to support simultaneous connections from multiple users.
• Facilitated the collection of scheduling weights from the RIC and efficient resource allocation for the connected users.

Resulted Publications: Real-Time RIC
Resulted Patents: Google Patents
Collaborators: Prof. Srinivas G Shakkottai, Dr. Woo-Hyun Ko, Ujwal Dinesha, Dr. G. Venkata Siva Santosh, Dr. Dinesh Bharadia, Raini Y Wu, Ushasi Ghosh

System Level Simulator (SLS) (2018-2021)

Developed a 3GPP-compliant downlink and uplink SLS for design validation of massive MIMO beamforming and scheduling solutions.

• SLS Features: FD-MIMO Channel Model, Antenna Array, Different Numerologies, Flexible Slot Formats, CSI Feedback, Traffic Modeling, Proportional Fair Scheduler, SU/MU-MIMO Multiplexing, MU-MIMO User Pairing, Precoding, Hybrid ARQ, Outer Loop Rate Control, and Uplink Power Control.
• Conducted channel model and throughput calibration aligned with 3GPP.
• Devised an innovative scheduler capable of efficiently managing hundreds of users, supporting both SU-MIMO and MU-MIMO.
• Developed novel user pairing algorithms to spatially multiplex users for downlink MU-MIMO transmission.
• Designed and validated beamforming algorithms to enhance downlink control channel capacity in 4G systems.
• Designed receiver beamforming algorithms for the uplink to reduce computational complexity and hardware cost for receivers.
• Proposed uplink coverage enhancements for extremely large cells in 5G NR.
• Proposed port signaling for reference signals as a means to mitigate inter-cell interference.
• Self-Organizing Networks (SON):
  • Implemented SON functionality to monitor and control RAN parameters.
  • SON Features: Configuring cell-specific parameters such as transmit power, antenna pattern, boresight, downtilt, etc., flexible eNB locations, multiple eNBs, intra-inter frequency handover, and collecting key metrics (RSRP, SINR, CQI, etc.).

Resulted Publications: Enhancing DL PDCCH Capacity, Beamformed PDCCH, UL Coverage Enhancements
Resulted Patents: Google Patents, FPO Link
Collaborators: Dr. Pavan Reddy Manne, Prof. Kiran Kuchi, Dr. SaiDhiraj Amuru, G. Koteswara Rao, and Dr. M. Sibgath Ali Khan

Structural MIMO for 6G

Structural MIMO (S-MIMO) to overcome practical limitations of current 5G MU-MIMO systems and enhance network capacity.

• Highly directional beams associated with each antenna port/panel to maximize coverage and improve spectral efficiency.
• Assisted in the design and implementation of an MU-MIMO downlik precoder leveraging TDD reciprocity.

Resulted Publications: Massive MIMO with Circular Antenna Array, Outdoor Massive MIMO, OTFDM & Structural MIMO
Collaborators: Spandan Bisoyi, P Muralimohan, Dr. Pavan Reddy Manne, Dr. SaiDhiraj Amuru, and Prof. Kiran Kuchi